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Sample records for axial guide field

  1. Experimental study of flow field in interference area between impeller and guide vane of axial flow pump

    Institute of Scientific and Technical Information of China (English)

    张华; 施卫东; 陈斌; 曹卫东; 张启华

    2014-01-01

    Axial flow pump is a kind of typical pumps with rotor-stator interaction, thus the measurement of the flow field between impeller and guide vane would facilitate the study of the internal rotor-stator interaction mechanism. Through a structural modifi-cation of a traditional axial flow pump, the requirements of particle image velocimetry (PIV) measurement are met. Under the condition of opt.0.8Q , the axial vortex is identified between impeller hub and guide vane hub, which is developed into the main flow and to affect the movement when the relative positions of impeller and guide vane at different flow rates are the same. Besides, the development and the dissipation of the tip leakage and the passage vortex in impeller passages are mainly responsible for the difference of the flow field close to the outer rim. As the flow rate decreases, the distribution of the meridional velocities at the impeller outlet becomes more non-uniform and the radial velocity component keeps increasing. The PIV measurement results under the condition of opt.1.0Q indicate that the flow separation and the trailing vortex at the trailing edge of a blade are likely to result in a velocity sudden change in this area, which would dramatically destroy the continuity of the flow field. Moreover, the radial direction of the flow between impeller and guide vane on the measurement plane does not always point from hub to rim. For a certain position, the direction is just from rim to hub, as is affected by the location of the intersection line of the shooting section and the impeller blade on the impeller as well as the angle between the intersection line and the rotating shaft.

  2. The effects of self-fields on the electron trajectory in a two-stream free electron laser with a helical wiggler and an axial guiding magnetic field

    Institute of Scientific and Technical Information of China (English)

    S. Saviz; E. Lashani; Farzin M. Aghamir

    2012-01-01

    A theory for the two-stream free-electron laser (TSFEL) with a helical wiggler and an axial guide magnetic field is developed.In the analysis,the effects of self-fields are taken into account.An analysis of the two-stream steady-state electron trajectories is given by solving the equation of motion.Numerical calculations show that there are seven groups of orbits in the presence of self-fields instead of two groups reported in the absence of self-fields.The stability of the trajectories is studied numerically.

  3. Electron acceleration in the inverse free electron laser with a helical wiggler by axial magnetic field and ion-channel guiding

    Institute of Scientific and Technical Information of China (English)

    Reza Khazaeinezhad; Mahdi Esmaeilzadeh

    2012-01-01

    Electron acceleration in the inverse free electron laser (IFEL) with a helical wiggler in the presence of ion-channel guiding and axial magnetic field is investigated in this article.The effects of tapering wiggler amplitude and axial magnetic field are calculated for the electron acceleration.In free electron lasers,electron beams lose energy through radiation while in IFEL electron beams gain energy from the laser.The equation of electron motion and the equation of energy exchange between a single electron and electromagnetic waves are derived and then solved numerically using the fourth order Runge-Kutta method.The tapering effects of a wiggler magnetic field on electron acceleration are investigated and the results show that the electron acceleration increases in the case of a tapered wiggler magnetic field with a proper taper constant.

  4. Build Axial Gradient Field by Using Axial Magnetized Permanent Rings

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Axial magnetic field produced by an axial magnetized permanent ring was studied. For two permanent rings, if they are magnetized in the same directions, a nearly uniform axial field can be produced. If they are magnetized in opposite direction,an axial gradient magnetic field can be generated, with the field range changing from -B0 to B0. A permanent magnet with a high axial gradient field was fabricated, the measured results agree with the PANDIRA calculation very well. For wider usage,it is desirable for the field gradient to be changed. Some methods to produce the variable gradient field are presented. These kinds of axial gradient magnetic field can also be used as a beam focusing for linear accelerator if the periodic field can be produced along the beam trajectory. The axial magnetic field is something like a solenoid, large stray field will leak to the outside environment if no method is taken to control them. In this paper, one method is illustrated to shield off the outside leakage field.

  5. View of the Axial Field Spectrometer

    CERN Multimedia

    1980-01-01

    The Axial Field Spectrometer, with the vertical uranium/scintillator calorimeter and the central drift chamber retracted for service. One coil of the Open Axial Field Magnet is just visible to the right.

  6. Wiggler Effects on the Growth Rate of a Raman Free-electron Laser with Axial Magnetic Field or Ion-Channel Guiding

    CERN Document Server

    Maraghechi, Behrouz

    2004-01-01

    A relativistic theory for Raman backscattering in the beam frame of electrons is presented and is used to find the growth rate of a free-electron laser (FEL), in the Raman regime. A one dimensional helical wiggler and an axial magnetic field are considered. The effects of static self-electric and self-magnetic fields, induced by the steady-state charge density and currents of the non-neutral electron beam, are taken into account to find the steady-state trajectories. The wiggler effects on the linear dispersion relations of the space-charge wave and radiation are included in the analysis. A numerical computation is conducted to compare the growth rate of the excited waves with nonrelativistic treatment. It was found that self-field effects increase the growth rate in the group II orbits and decrease it in the group I orbits. However, the wiggler effects on growth rate are stronger and increase the growth rate on both group I and group II orbits. The discontinuity, due to the cyclotron resonance with the radia...

  7. Performance analysis of axial flow pump on gap changing between impeller and guide vane

    Science.gov (United States)

    Wang, W. J.; Liang, Q. H.; Wang, Y.; Yang, Y.; Yin, G.; Shi, X. X.

    2013-12-01

    In order to study the influence on gap changing of the static and dynamic components in axial flow pump, the axial flow pump model (TJ04-ZL-06) that used in the eastern of south-to-north water diversion project was selected. Steady turbulence field with different gaps was simulated by standard κ-ε turbulence model and double-time stepping methods. Information on the pressure distribution and velocity distribution of impeller surfaces were obtained. Then, calculated results were compared with the test results and analyzed. The results show that the performance of pump is not sensitive with the axial gap width under design conditions and the large flow rate condition. With increasing gap width, it will be improved in low flow rate condition. The attack angle of impeller inlet in small flow rate condition become small and the flow separation phenomenon can be observed in this condition. The axial velocity distribution of impeller outlet is nonlinear and to increase the axial gap is to improve the flow pattern near the hub effectively. The trend of calculating results is identical with test. It will play a guiding role to the axial pump operation and design in south-to-north water diversion project.

  8. Characterization of mechanical and geometrical properties of a tube with axial and circumferential guided waves.

    Science.gov (United States)

    Yeh, Cheng-Hung; Yang, Che-Hua

    2011-05-01

    Guided waves propagating in cylindrical tubes are frequently applied for the characterization of material or geometrical properties of tubes. In a tube, guided waves can propagate in the axial direction and called axial guided waves, or in the circumferential direction called circumferential guided waves. Dispersion spectra for the axial and circumferential guided waves share some common behaviors and however exhibit some particular behaviors of their own. This study provides an investigation with theoretical modeling, experimental measurements, and a simplex-based inversion procedure to explore the similarity and difference between the axial guided waves and circumferential guided waves, aiming at providing useful information while axial and circumferential guided waves are applied in the area of material characterization. The sensitivity to the radius curvature for the circumferential guided waves dispersion spectra is a major point that makes circumferential guided waves different from axial guided waves. For the purpose of material characterization, both axial and circumferential guided waves are able to extract an elastic moduli and wall-thickness information from the dispersion spectra, however, radius information can only be extracted from the circumferential guided waves spectra. Copyright © 2010 Elsevier B.V. All rights reserved.

  9. Field Guide to Radiometry

    CERN Document Server

    Grant, Barbara

    2011-01-01

    Written from a systems engineering perspective, this SPIE Field Guide covers topics in optical radiation propagation, material properties, sources, detectors, system components, measurement, calibration, and photometry. The book's organization and extensive collection of diagrams, tables, and graphs will enable the reader to efficiently identify and apply relevant information to radiometric problems arising amid the demands of today's fast-paced technical environment.

  10. Axisymmetric field generation within an ambient axial field

    Science.gov (United States)

    Darah, A. A.; Sarson, G. R.

    2007-01-01

    The generation of magnetic field in a homogeneous, electrically conducting fluid - as required for the dynamo generation of the fields of many astrophysical bodies - is normally a threshold process; the dynamo mechanism, applicable to such bodies in unmagnetised environments, requires motions of sufficient strength to overcome the innate magnetic diffusion. In the presence of an ambient field, however, the critical nature of the field generation process is relaxed. Motions can distort and amplify the ambient field for all amplitudes of flow. For motions with appropriate geometries, an internal `dynamo-like' field of appreciable strength can be generated, even for relatively weak flows. At least a minority of planets, moons and other bodies exist within significant external astrophysical fields. For these bodies, the ambient field problem is more relevant than the classical dynamo problem, yet it remains relatively little studied. In this paper we consider the effect of an axial ambient field on a spherical mean-field α2 ω dynamo model, through nonlinear calculations with α-quenching feedback. Ambient fields of varying strengths, and both stationary and oscillatory in time, are imposed. Particular focus is placed on the effects of these fields on the equatorial symmetry and the time dependence of the preferred solutions.

  11. Open-Axial-Field Magnet at ISR intersection I8

    CERN Multimedia

    1979-01-01

    This axial field spectrometer left the central collision region unobstructed in order to ease analysis of secondary particles emitted at large angle. The ISR circulating beams were passing through a hole in the magnet poles.

  12. Bistability between equatorial and axial dipoles during magnetic field reversals

    CERN Document Server

    Gissinger, Christophe; Schrinner, Martin; Dormy, Emmanuel

    2012-01-01

    Numerical simulations of the geodynamo in presence of an heterogeneous heating are presented. We study the dynamics and the structure of the magnetic field when the equatorial symmetry of the flow is broken. If the symmetry breaking is sufficiently strong, the m = 0 axial dipolar field is replaced by an hemispherical magnetic field, dominated by an oscillating m = 1 magnetic field. Moreover, for moderate symmetry breaking, a bistability between the axial and the equatorial dipole is observed. In this bistable regime, the axial magnetic field exhibits chaotic switches of its polarity, involving the equatorial dipole during the transition period. This new scenario for magnetic field reversals is discussed within the framework of the Earth's dynamo.

  13. Bistability between equatorial and axial dipoles during magnetic field reversals.

    Science.gov (United States)

    Gissinger, Christophe; Petitdemange, Ludovic; Schrinner, Martin; Dormy, Emmanuel

    2012-06-08

    Numerical simulations of the geodynamo in the presence of heterogeneous heating are presented. We study the dynamics and the structure of the magnetic field when the equatorial symmetry of the flow is broken. If the symmetry breaking is sufficiently strong, the m=0 axial dipolar field is replaced by a hemispherical magnetic field, dominated by an oscillating m=1 magnetic field. Moreover, for moderate symmetry breaking, a bistability between the axial and the equatorial dipole is observed. In this bistable regime, the axial magnetic field exhibits chaotic switches of its polarity, involving the equatorial dipole during the transition period. This new scenario for magnetic field reversals is discussed within the framework of Earth's dynamo.

  14. Interaction of impeller and guide vane in a series-designed axial-flow pump

    Science.gov (United States)

    Kim, S.; Choi, Y. S.; Lee, K. Y.; Kim, J. H.

    2012-11-01

    In this paper, the interaction of the impeller and guide vane in a series-designed axial-flow pump was examined through the implementation of a commercial CFD code. The impeller series design refers to the general design procedure of the base impeller shape which must satisfy the various flow rate and head requirements by changing the impeller setting angle and number of blades of the base impeller. An arc type meridional shape was used to keep the meridional shape of the hub and shroud with various impeller setting angles. The blade angle and the thickness distribution of the impeller were designed as an NACA airfoil type. In the design of the guide vane, it was necessary to consider the outlet flow condition of the impeller with the given setting angle. The meridional shape of the guide vane were designed taking into consideration the setting angle of the impeller, and the blade angle distribution of the guide vane was determined with a traditional design method using vane plane development. In order to achieve the optimum impeller design and guide vane, three-dimensional computational fluid dynamics and the DOE method were applied. The interaction between the impeller and guide vane with different combination set of impeller setting angles and number of impeller blades was addressed by analyzing the flow field of the computational results.

  15. Improvement of the Efficiency of the Axial-Flow Pump at Part Loads due to Installing Outlet Guide Vanes Mechanism

    Directory of Open Access Journals (Sweden)

    Fan Yang

    2016-01-01

    Full Text Available In order to investigate the influence of adjustable outlet guide vane on the hydraulic performance of axial-flow pump at part loads, the axial-flow pump with 7 different outlet guide vane adjustable angles was simulated based on the RNG k-ε turbulent model and Reynolds time-averaged equations. The Vector graphs of airfoil flow were analyzed in the different operating conditions for different adjustable angles of guide vane. BP-ANN prediction model was established about the effect of adjustable outlet guide vane on the hydraulic performance of axial-flow pump based on the numerical results. The effectiveness of prediction model was verified by theoretical analysis and numerical simulation. The results show that, with the adjustable angle of guide vane increasing along clockwise, the high efficiency area moves to the large flow rate direction; otherwise, that moves to the small flow rate direction. The internal flow field of guide vane is improved by adjusting angle, and the flow separation of tail and guide vane inlet ledge are decreased or eliminated, so that the hydraulic efficiency of pumping system will be improved. The prediction accuracy of BP-ANN model is 1%, which can meet the requirement of practical engineering.

  16. View of the Axial Field Spectrometer (R807)

    CERN Multimedia

    1980-01-01

    In this view of the Axial Field Spectrometer at I8, the vertical uranium/scintillator hadron calorimeter (just left of centre) is retracted to give access to the cylindrical central drift chamber. The yellow iron structure served as a filter to identify muons, with MWPCs and the array of Cherenkov counters to the right.

  17. Overview of the Axial Field Spectrometer in the ISR tunnel

    CERN Multimedia

    1980-01-01

    A view of the Axial Field Spectrometer – the last large experiment at the ISR. The horizontal top and vertical outer arrays of the uranium-scintillator hadron calorimeter are clear to be seen, with the blue cylindrical pole piece of the magnet just visible. The pipes that are visible in front of the pole piece are cryogenic feed pipes for the superconducting low-beta quadrupoles.

  18. Field guide to nonlinear optics

    CERN Document Server

    Powers, Peter E

    2013-01-01

    Optomechanics is a field of mechanics that addresses the specific design challenges associated with optical systems. This [i]Field Guide [/i]describes how to mount optical components, as well as how to analyze a given design. It is intended for practicing optical and mechanical engineers whose work requires knowledge in both optics and mechanics. This Field Guide is designed for those looking for a condensed and concise source of key concepts, equations, and techniques for nonlinear optics. Topics covered include technologically important effects, recent developments in nonlinear optics

  19. Field Guide to Diffractive Optics

    CERN Document Server

    Soskind, Yakov

    2011-01-01

    This SPIE Field Guide provides the operational principles and established terminology of diffractive optics as well as a comprehensive overview of the main types of diffractive optics components. An emphasis is placed on the qualitative explanation of the diffraction phenomenon by the use of field distributions and graphs, providing the basis for understanding the fundamental relations and important trends.

  20. New librarianship field guide

    CERN Document Server

    Lankes, R David

    2016-01-01

    This book offers a guide for librarians who see their profession as a chance to make a positive difference in their communities -- librarians who recognize that it is no longer enough to stand behind a desk waiting to serve. R. David Lankes, author of "The Atlas of New Librarianship," reminds librarians of their mission: to improve society by facilitating knowledge creation in their communities. In this book, he provides tools, arguments, resources, and ideas for fulfilling this mission. Librarians will be prepared to become radical positive change agents in their communities, and other readers will learn to understand libraries in a new way. The librarians of Ferguson, Missouri, famously became positive change agents in August 2014 when they opened library doors when schools were closed because of civil unrest after the shooting of an unarmed teen by police. Working with other local organizations, they provided children and their parents a space for learning, lunch, and peace. But other libraries serve othe...

  1. Experimental studies of axial magnetic fields generated in ultrashort-pulse laser-plasma interaction

    Institute of Scientific and Technical Information of China (English)

    李玉同; 张杰; 陈黎明; 赵理曾; 夏江帆; 魏志义; 江文勉

    2000-01-01

    The quasistatic axial magnetic fields in plasmas produced by ultrashort laser pulses were measured by measuring the Faraday rotation angle of the backscattered emission. The spatial distribution of the axial magnetic field was obtained with a peak value as high as 170 Tesla. Theory suggests that the axial magnetic field is generated by dynamo effect in laser-plasma interaction.

  2. Collimation of laser-produced plasmas using axial magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Amitava; Harilal, Sivanandan S.; Hassan, Syed M.; Endo, Akira; Mocek, Tomas; Hassanein, A.

    2015-06-01

    We investigated the expansion dynamics of laser-produced plasmas expanding into an axial magnetic field. Plasmas were generated by focusing 1.064 µm Nd:YAG laser pulses onto a planar tin target in vacuum and allowed to expand into a 0.5 T magnetic-filed where field lines were aligned along the plume expansion direction. Gated images employing intensified CCD showed focusing of the plasma plume, which were also compared with results obtained using particle-in-cell modelling methods. The estimated density and temperature of the plasma plumes employing emission spectroscopy revealed significant changes in the presence and absence of the 0.5T magnetic field. In the presence of the field, the electron temperature is increased with distance from the target, while the density showed opposite effects.

  3. Field guide to adaptive optics

    CERN Document Server

    Tyson, Robert K

    2004-01-01

    ""...These field guides will be immensely useful to all scientists and engineers who wish to brush up on authentic definitions, equations, and tables of data in optics. And the format is really user friendly! I...wonder now how I ever got along in optics without this ready reference....a real winner!"" --Dr. Leno S. Pedrotti, Center for Occupational Research and Development (CORD) Third in the Field Guide Series, this is a summary of the methods for determining the requirements of an adaptive optics system, the performance of the system, and the requirements for the components of th

  4. Experimental Investigation on Design Enhancement of Axial Fan Using Fixed Guide Vane

    Science.gov (United States)

    Munisamy, K. M.; Govindasamy, R.; Thangaraju, S. K.

    2015-09-01

    Airflow passes through the rotating blade in an axial flow fan will experience a helical flow pattern. This swirling effect leads the system to experience swirl energy losses or pressure drop yet reducing the total efficiency of the fan system. A robust tool to encounter this air spin past the blade is by introducing guide vane to the system. Owing to its importance, a new approach in designing outlet guide vane design for a commercial usage 1250mm diameter axial fan with a 30° pitch angle impeller has been introduced in this paper. A single line metal of proper curvature guide vane design technique has been adopted for this study. By choosing fan total efficiency as a target variable to be improved, the total and static pressure on the design point were set to be constraints. Therefore, the guide vane design was done based on the improvement target on the static pressure in system. The research shows that, with the improvement in static pressure by 29.63% through guide vane installation, the total fan efficiency is increased by 5.12%, thus reduces the fan power by 5.32%. Good agreement were found, that when the fan total efficiency increases, the power consumption of the fan is reduced. Therefore, this new approach of guide vane design can be applied to improve axial fan performance.

  5. Aerial field guide

    Science.gov (United States)

    Nummedal, D.

    1978-01-01

    There are two overflights planned for the field conference; one for the Cheney-Palouse tract of the eastern channeled scabland, the other covering the coulees and basins of the western region. The approximate flight lines are indicated on the accompanying LANDSAT images. The first flight will follow the eastern margin of this large scabland tract, passing a series of loess remnants, gravel bars and excavated rock basins. The western scablands overflight will provide a review of the structurally controlled complex pattern of large-scale erosion and deposition characteristic of the region between the upper Grand Coulee (Banks Lake) and the Pasco Basin.

  6. Analysis of brushless DC generator incorporating an axial field coil

    Energy Technology Data Exchange (ETDEWEB)

    Moradi, Hassan, E-mail: H_moradi@sbu.ac.i [Department of Electrical and Computer Engineering, Shahid Beheshti University, GC, Tehran (Iran, Islamic Republic of); Afjei, E. [Department of Electrical and Computer Engineering, Shahid Beheshti University, GC, Tehran (Iran, Islamic Republic of)

    2011-07-15

    Highlights: {yields} Magnetic analysis and experiment of a three-phase field assisted BLDC generator. {yields} Confirm the accuracy of the predicted flux-linkage by 2-D FE analysis. {yields} Confirm the accuracy of the FE analysis results by coupling the FE and BE method. {yields} Control the output voltage to a desired level by control the amplitude of the I{sub f}. {yields} Compatible with any application that requires variable speed operation. -- Abstract: This paper describes the magnetic analysis and experiment of a three-phase field assisted brushless DC (BLDC) generator. Unlike conventional BLDC generators, the permanent magnet is replaced with an assisted field winding. The stator and rotor are constructed with two dependent magnetically sets, in which each stator set includes nine salient poles with coil windings, and the rotor comprises of six salient poles. Other pole combinations also are possible. This construction is similar to a homopolar inductor alternator. The DC current in the assisted field winding produces axial flux which makes the rotor magnetically polarized at its ends. The magnetic field flows axially through the rotor shaft and closes through the stator teeth and the machine housing. To evaluate the generator performance, two types of analysis, namely the numerical technique and the experimental study have been utilized. In the numerical analysis, 2-D finite element (FE) analysis has been carried out using a MagNet CAD package (Infolytica Corporation Ltd.), to confirm the accuracy of the predicted flux-linkage characteristics, whereas in the experimental study, a prototype BLDC generator was constructed for verifying the actual performance. Furthermore, the evaluation method based on a hybrid numerical method coupling the finite element (FE) analysis and boundary element (BE) method, has been carried out to confirm the accuracy of the 2-D FE analysis simulation results. It provides not only confirmations of the investigation in results

  7. Field guide to adaptive optics

    CERN Document Server

    Tyson, Robert

    2012-01-01

    This SPIE Field Guide provides a summary of the methods for determining the requirements of an adaptive optics system, the performance of the system, and the requirements for the components of the system. This second edition has a greatly expanded presentation of adaptive optics control system design and operation. Discussions of control models are accompanied by various recommendations for implementing the algorithms in hardware.

  8. Learning That Lasts: Field Guide

    Science.gov (United States)

    Education Commission of the States, 2005

    2005-01-01

    This "Learning That Lasts Field Guide" is intended to trigger discussion about ways to integrate and sustain high-quality service-learning, as well as to provide a clearer path to finding and employing the information in the Education Commission of the States' (ECS) 2002 publication "Learning That Lasts: How Service-Learning Can Become an Integral…

  9. Mass Structure of Axial Vector Types of Leptons and Fields

    CERN Document Server

    Sharafiddinov, Rasulkhozha S

    2011-01-01

    A classification of currents with respect to C-operation admits the existence of C-noninvariant types of Dirac fermions. Among them one can meet an electroweakly charged C-antisymmetrical leptons, the mass of which includes the electric and weak components responsible for the existence of their anapole charge, charge radius and electric dipole moment. Such connections can constitute the paraleptons of axial-vector currents, for example, at the interactions with field of spinless nuclei of true neutrality. We derive the united equations which relate the structural parts of mass to anapole, charge radius and electric dipole of any truly neutral lepton in the framework of flavour symmetry. Thereby, they establish the C-odd nature of leptons and fields at the level of constancy law of the size implied from the multiplication of a weak mass of C-antisymmetrical lepton by its electric mass. Therefore, all leptons of C-antisymmetricality regardless of the difference in masses of an axial-vector character, have the s...

  10. Light fields with an axially expanded intensity distribution for stable three-dimensional optical trapping.

    Science.gov (United States)

    Zwick, Susanne; Schaub, Christian; Haist, Tobias; Osten, Wolfgang

    2010-09-13

    We introduce a new kind of light field to improve and simplify the trapping process of axially displaced particles. To this end we employ a light field with an axially expanded intensity distribution, which at the same time enables stable axial trapping. We present simulations of the axial intensity distribution of the novel trapping field and first experimental results, which demonstrate the improvement of the reliability of the axial trapping process. The method can be used to automate trapping of particles that are located outside of the focal plane of the microscope.

  11. Flow control in axial fan inlet guide vanes by synthetic jets

    OpenAIRE

    Wurst P.; Trávníček Z.; Cyrus V.; Kordík J.

    2013-01-01

    Tested high pressure axial flow fan with hub/tip ratio of 0.70 and external diameter of 600 mm consisted of inlet guide vanes (IGV), rotor and stator blade rows. Fan peripheral velocity was 47 m/s. Air volume flow rate was changed by turning of rear part of the inlet guide vanes. At turning of 20 deg the flow was separated on the IGV profiles. The synthetic jets were introduced through radial holes in machine casing in the location before flow separation origin. Synthetic jet actuator was des...

  12. High temperature superconducting axial field magnetic coupler: realization and test

    Science.gov (United States)

    Belguerras, L.; Mezani, S.; Lubin, T.; Lévêque, J.; Rezzoug, A.

    2015-09-01

    Contactless torque transmission through a large airgap is required in some industrial applications in which hermetic isolation is necessary. This torque transmission usually uses magnetic couplers, whose dimension strongly depends on the airgap flux density. The use of high temperature superconducting (HTS) coils to create a strong magnetic field may constitute a solution to reduce the size of the coupler. It is also possible to use this coupler to replace a torque tube in transmitting the torque produced by a HTS motor to its load. This paper presents the detailed construction and tests of an axial field HTS magnetic coupler. Pancake coils have been manufactured from BSCCO tape and used in one rotor of the coupler. The second rotor is mainly composed of NdFeB permanent magnets. Several tests have been carried out showing that the constructed coupler is working properly. A 3D finite element (FE) model of the studied coupler has been developed. Airgap magnetic field and torque measurements have been carried out and compared to the FE results. It has been shown that the measured and the computed quantities are in satisfactory agreement.

  13. Field Guides in Academe: A Citation Study

    Science.gov (United States)

    Schmidt, Dianne

    2006-01-01

    Field guides are common in libraries but are generally not considered scholarly. This study examines citations to fifty field guides to determine how they were used in scholarly publications, finding that field guides are frequently cited as a source of data on the ranges, habits, and descriptions of plants and animals.

  14. Field guide to geometrical optics

    CERN Document Server

    Greivenkamp, John E

    2004-01-01

    This Field Guide derives from the treatment of geometrical optics that has evolved from both the undergraduate and graduate programs at the Optical Sciences Center at the University of Arizona. The development is both rigorous and complete, and it features a consistent notation and sign convention. This volume covers Gaussian imagery, paraxial optics, first-order optical system design, system examples, illumination, chromatic effects, and an introduction to aberrations. The appendices provide supplemental material on radiometry and photometry, the human eye, and several other topics.

  15. Cyclotron radiation cooling of a short electron bunch kicked in an undulator with guiding magnetic field

    Directory of Open Access Journals (Sweden)

    I. V. Bandurkin

    2015-11-01

    Full Text Available We propose to use of an undulator with the guiding axial magnetic field as a “kicker” forming a bunch of electron gyro-oscillators with a small spread in the axial velocity. The cyclotron emission from the bunch leads to losing oscillatory velocity of electron gyrorotation, but it does not perturb the axial electron velocity. This effect can be used for transformation of minimization of the spread in electron axial velocity in the undulator section into minimization of the spread in electron energy in the cyclotron radiation section.

  16. Magnetic field uniformity of the practical tri-axial Helmholtz coils systems.

    Science.gov (United States)

    Beiranvand, R

    2014-05-01

    In this paper, effects of the assembly misalignments and the manufacturing mismatches on the magnetic field uniformity of a practical tri-axial Helmholtz coils system have been modeled mathematically. These undesired effects regularly occur in any practical tri-axial Helmholtz coils system. To confirm the mathematical calculations, a tri-axial Helmholtz coils system has been constructed and the uniformity of its magnetic field has been measured under different conditions. The experimental results are in good agreement with the mathematical analyses.

  17. Subjected to Axial Compressive Load and Transverse Magnetic Field

    Directory of Open Access Journals (Sweden)

    Mei-Feng Liu

    2010-01-01

    Full Text Available The interactive behaviors between transverse magnetic fields and axial loads of a magnetoelastic (ME beam subjected to general boundary conditions are investigated. In particular, the instability criterion for the magneto-mechanical buckling problem is intricately discussed based on the structure characteristics and the initial conditions. The equation of motion for the proposed physical model is introduced according to the Hamilton's principle, and the stability criterion is obtained by using the method of multiple scales implemented on both spatial and time domains. Eventually a so-called Schrodinger equation with cubic nonlinearity (NLS can be generated by suitably changing the variables; as a result, the stable criterion for the magnetoelastic beam can be acquired after dissecting the nonlinear Schrodinger equation and requiring the imaginary part of the time domain solution to be vanished. Stability criterion curve for the dispersion equation of the ME beam is firstly depicted in order to reveal the magnificent influence of the structure characteristic itself, followed by the instability constraint due to the variation of initial conditions and the observation locations. The results indicate that the prior one actually denotes a parabola, whereas the latter one is sometimes a diamond-like or ellipse-like region spotting along the prior one.

  18. Effect of axial magnetic field on the shape of copper ribbon crystal grown by Czochralski method

    OpenAIRE

    Shen, Zhe; Zhong, Yunbo; Dong, Licheng; FAN, Lijun; Wang, Huai; Li, Chuanjun; Ren, Weili; Lei, Zuosheng; Ren, Zhongming

    2015-01-01

    International audience; During the process of growing ribbon crystal by Czochralski method, Turbulent convection in copper melt was effectively suppressed by applying an axial magnetic field (magnetic induction B≤57mT). The changes of thermal fluctuation and flow field were measured and modeled. With the magnetic field increased gradually (from 0 to 57mT), the shape of ribbon crystal became regularly wider. We concluded that the axial magnetic field could promote to form a suitable temperatur...

  19. Improvement of the Efficiency of the Axial-Flow Pump at Part Loads due to Installing Outlet Guide Vanes Mechanism

    OpenAIRE

    Fan Yang; Hao-ru Zhao; Chao Liu

    2016-01-01

    In order to investigate the influence of adjustable outlet guide vane on the hydraulic performance of axial-flow pump at part loads, the axial-flow pump with 7 different outlet guide vane adjustable angles was simulated based on the RNG k-ε turbulent model and Reynolds time-averaged equations. The Vector graphs of airfoil flow were analyzed in the different operating conditions for different adjustable angles of guide vane. BP-ANN prediction model was established about the effect of adjustabl...

  20. Axial guided wave technique for rapid inspection of the "Noodle" regions in a stiffened composite component

    Science.gov (United States)

    Manogharan, Prabhakaran; Rajagopal, Prabhu; Balasubramaniam, Krishnan

    2015-03-01

    Composite structures are used in a wide variety of applications. The use of stiffened composites is common in aerospace box-like components and provides the additional stiffness required. Examples of such stiffened structural geometries include airfoils, fuselage, wing box, tail section, etc. The inspection of the radius filler "Noodle" that fills the interface between skin and stiffener has been of great concern to the aerospace composites industry. This paper describes the 3D FEM models of the ultrasonic axially propagating guided wave modes. Additionally, the models were used for understanding their confinement in the Noodle region, their leakage to the remaining sections of the component and their interaction with defects of different types, sizes and their locations along Noodle region. The ultrasonic guided wave modes that propagate along the length of the Noodle were identified using the 3D finite element model. These simulations were validated using graphite-epoxy test coupons and components from aerospace industry.

  1. Tunable Clamped–Guided Arch Resonators Using Electrostatically Induced Axial Loads

    KAUST Repository

    Alcheikh, Nouha

    2017-01-04

    We present a simulation and experimental investigation of bi-directional tunable in-plane clamped-guided arch microbeam resonators. Tensile and compressive axial forces are generated from a bi-directional electrostatic actuator, which modulates the microbeam stiffness, and hence changes its natural frequency to lower or higher values from its as-fabricated value. Several devices of various anchor designs and geometries are fabricated. We found that for the fabricated shallow arches, the effect of the curvature of the arch is less important compared to the induced axial stress from the axial load. We have shown that the first mode resonance frequency can be increased up to twice its initial value. Additionally, the third mode resonance frequency can be increased up to 30% of its initial value. These results can be promising as a proof-of-concept for the realization of wide-range tunable microresonators. The experimental results have been compared to finite-element simulations, showing good agreement among them.

  2. Automatic efficiency optimization of an axial compressor with adjustable inlet guide vanes

    Science.gov (United States)

    Li, Jichao; Lin, Feng; Nie, Chaoqun; Chen, Jingyi

    2012-04-01

    The inlet attack angle of rotor blade reasonably can be adjusted with the change of the stagger angle of inlet guide vane (IGV); so the efficiency of each condition will be affected. For the purpose to improve the efficiency, the DSP (Digital Signal Processor) controller is designed to adjust the stagger angle of IGV automatically in order to optimize the efficiency at any operating condition. The A/D signal collection includes inlet static pressure, outlet static pressure, outlet total pressure, rotor speed and torque signal, the efficiency can be calculated in the DSP, and the angle signal for the stepping motor which control the IGV will be sent out from the D/A. Experimental investigations are performed in a three-stage, low-speed axial compressor with variable inlet guide vanes. It is demonstrated that the DSP designed can well adjust the stagger angle of IGV online, the efficiency under different conditions can be optimized. This establishment of DSP online adjustment scheme may provide a practical solution for improving performance of multi-stage axial flow compressor when its operating condition is varied.

  3. Dopant segregation during vertical Bridgman-Stockbarger growth with melt stabilization by strong axial magnetic fields

    Science.gov (United States)

    Matthiesen, D. H.; Wargo, M. J.; Motakef, S.; Carlson, D. J.; Nakos, J. S.

    1987-01-01

    Ga-doped germanium was grown in a vertical Bridgman-Stockbarger system with melt stabilization by axial magnetic fields of 30 kG. It was found that radial segregation of gallium is negligible and that the initial transient of axial macro-segregation is in apparent compliance with the theory of diffusion controlled plane front solidification.

  4. Indispensability of Ghost Fields and Extended Hamiltonian Formalism in Axial Gauge Quantization of Gauge Fields

    CERN Document Server

    Nakawaki, Y

    2000-01-01

    It is shown that ghost fields are indispensable in deriving well-defined antiderivatives in pure space-like axial gauge quantizations of gauge fields. To avoid inessential complications we confine ourselves to noninteracting abelian fields and incorporate their quantizations as a continuous deformation of those in light-cone gauge. We attain this by constructing an axial gauge formulation in auxiliary coordinates $x^{\\mu}= (x^+,x^-,x^1,x^2)$, where $x^+=x^0{\\rm sin}{\\theta}+x^3{\\rm cos}{\\theta}, x^-=x^0{\\rm cos}{\\theta}-x^3{\\rm sin}{\\theta}$ and $x^+$ and $A_-=A^0{\\rm cos} {\\theta}+A^3{\\rm sin}{\\theta}=0$ are taken as the evolution parameter and the gauge fixing condition, respectively. We introduce $x^-$-independent residual gauge fields as ghost fields and accomodate them to the Hamiltonian formalism by applying McCartor and Robertson's method. As a result, we obtain conserved translational generators $P_{\\mu}$, which retain ghost degrees of freedom integrated over the hyperplane $x^-=$ constant. They enabl...

  5. Experiments on the stability of a liquid bridge in an axial electric field

    Science.gov (United States)

    Sankaran, Subramanian; Saville, D. A.

    1993-01-01

    The behavior of a neutrally buoyant liquid bridge was studied in the presence of axial electric fields. Silicone oil and a castor-oil-eugenol mixture were used to form cylinders with slenderness ratios larger than pi with strong, axial, dc electric fields. Below a certain field strength, a smooth transition to an axisymmetric, vaselike shape occurred. Circulation patterns were observed in these bridges. At lower field strengths, the bridge shape was more deformed and, at a well-defined field, pinch-off occurred. With ac fields, the field strength required to stabilize the bridge was higher and the collapse of the cylinder was much sharper. Upon interchanging the fluids, a steady axial field was found to destabilize cylinders with slenderness ratios less than 3. This behavior is consistent with that anticipated if the fluids behave as leaky dielectrics but not if they act as perfect dielectrics.

  6. Principal parametric resonance of axially accelerating rectangular thin plate in magnetic field

    Institute of Scientific and Technical Information of China (English)

    胡宇达; 张金志

    2013-01-01

    Nonlinear parametric vibration and stability is investigated for an axially accelerating rectangular thin plate subjected to parametric excitations resulting from the axial time-varying tension and axial time-varying speed in the magnetic field. Consid-ering geometric nonlinearity, based on the expressions of total kinetic energy, potential energy, and electromagnetic force, the nonlinear magneto-elastic vibration equations of axially moving rectangular thin plate are derived by using the Hamilton principle. Based on displacement mode hypothesis, by using the Galerkin method, the nonlinear para-metric oscillation equation of the axially moving rectangular thin plate with four simply supported edges in the transverse magnetic field is obtained. The nonlinear principal parametric resonance amplitude-frequency equation is further derived by means of the multiple-scale method. The stability of the steady-state solution is also discussed, and the critical condition of stability is determined. As numerical examples for an axially moving rectangular thin plate, the influences of the detuning parameter, axial speed, axial tension, and magnetic induction intensity on the principal parametric resonance behavior are investigated.

  7. Melt Motion Due to Peltier Marking During Bridgman Crystal Growth with an Axial Magnetic Field

    Science.gov (United States)

    Sellers, C. C.; Walker, John S.; Szofran, Frank R.; Motakef, Shariar

    2000-01-01

    This paper treats a liquid-metal flow inside an electrically insulating cylinder with electrically conducting solids above and below the liquid region. There is a uniform axial magnetic field, and there is an electric current through the liquid and both solids. Since the lower liquid-solid interface is concave into the solid and since the liquid is a better electrical conductor than the adjacent solid, the electric current is locally concentrated near the centerline. The return to a uniform current distribution involves a radial electric current which interacts with the axial magnetic field to drive an azimuthal flow. The axial variation of the centrifugal force due to the azimuthal velocity drives a meridional circulation with radial and axial velocities. This problem models the effects of Peltier marking during the vertical Bridgman growth of semiconductor crystals with an externally applied magnetic field, where the meridional circulation due to the Peltier Current may produce important mixing in the molten semiconductor.

  8. Students Create Their Own Field Guide.

    Science.gov (United States)

    Grinstad, Roxanne

    2001-01-01

    Describes how K-8 students wrote and illustrated a field guide at Bay View School. Presents some examples from the "Bay View Nature Trail Guide Book" and includes suggestions for teachers on how to proceed in drawing illustrations and writing entries for different grade levels. (YDS)

  9. Students Create Their Own Field Guide.

    Science.gov (United States)

    Grinstad, Roxanne

    2001-01-01

    Describes how K-8 students wrote and illustrated a field guide at Bay View School. Presents some examples from the "Bay View Nature Trail Guide Book" and includes suggestions for teachers on how to proceed in drawing illustrations and writing entries for different grade levels. (YDS)

  10. Design method and magnetic field analysis of axial-magnetized permanent magnet micromotor

    Institute of Scientific and Technical Information of China (English)

    YANG Jiewei; WU Yihui; JIA Hongguang; ZHANG Ping; WANG Shurong

    2007-01-01

    To investigate the impact of size on its performance in designing an axial-magnetized permanent magnet micromotor,the finite element method is adopted to simulate the magnetic field of the dual rotor motor,and the flux density wave form distributed in the airgap is obtained.The influence of the external dimensions,pole numbers and magnet thicknesses of the rotor,and the airgap distances on the flux density,are analyzed and analytical results are given.With the increase of the airgap distance,the flux density under more poles reduces more quickly than under fewer poles.With the increase of the magnet thickness,the flux density is a rising curve,and after the magnet thickness attains a certain point,the flux density is almost a constant.While reducing the diameter of the rotor,the decrease of the flux density slows down as magnet thickness is reduced.To avoid having a seriously distorted waveform,the distance between inner and outer radii of the rotor must be larger than 1.5 millimeter.Results of the magnetic field analysis can guide a microminiaturization of the motor.Moreover,the results are analyzed theoretically and the simulated values are almost consistent with the experimental values.

  11. The flow field investigations of no load conditions in axial flow fixed-blade turbine

    Science.gov (United States)

    Yang, J.; Gao, L.; Wang, Z. W.; Zhou, X. Z.; Xu, H. X.

    2014-03-01

    During the start-up process, the strong instabilities happened at no load operation in a low head axial flow fixed-blade turbine, with strong pressure pulsation and vibration. The rated speed can not reach until guide vane opening to some extent, and stable operation could not be maintained under the rated speed at some head, which had a negative impact on the grid-connected operation of the unit. In order to find the reason of this phenomenon, the unsteady flow field of the whole flow passage at no load conditions was carried out to analyze the detailed fluid field characteristics including the pressure pulsation and force imposed on the runner under three typical heads. The main hydraulic cause of no load conditions instability was described. It is recommended that the power station should try to reduce the no-load running time and go into the high load operation as soon as possible when connected to grid at the rated head. Following the recommendations, the plant operation practice proved the unstable degree of the unit was reduced greatly during start up and connect to the power grid.

  12. Flow control in axial fan inlet guide vanes by synthetic jets

    Directory of Open Access Journals (Sweden)

    Wurst P.

    2013-04-01

    Full Text Available Tested high pressure axial flow fan with hub/tip ratio of 0.70 and external diameter of 600 mm consisted of inlet guide vanes (IGV, rotor and stator blade rows. Fan peripheral velocity was 47 m/s. Air volume flow rate was changed by turning of rear part of the inlet guide vanes. At turning of 20 deg the flow was separated on the IGV profiles. The synthetic jets were introduced through radial holes in machine casing in the location before flow separation origin. Synthetic jet actuator was designed with the use of a speaker by UT AVCR. Its membrane had diameter of 63 mm. Excitation frequency was chosen in the range of 500 Hz – 700 Hz. Synthetic jets favourably influenced separated flow on the vane profiles in the distance of (5 – 12 mm from the casing surface. The reduction of flow separation area caused in the region near the casing the decrease of the profile loss coefficient approximately by 20%.

  13. Flow control in axial fan inlet guide vanes by synthetic jets

    Science.gov (United States)

    Cyrus, V.; Trávníček, Z.; Wurst, P.; Kordík, J.

    2013-04-01

    Tested high pressure axial flow fan with hub/tip ratio of 0.70 and external diameter of 600 mm consisted of inlet guide vanes (IGV), rotor and stator blade rows. Fan peripheral velocity was 47 m/s. Air volume flow rate was changed by turning of rear part of the inlet guide vanes. At turning of 20 deg the flow was separated on the IGV profiles. The synthetic jets were introduced through radial holes in machine casing in the location before flow separation origin. Synthetic jet actuator was designed with the use of a speaker by UT AVCR. Its membrane had diameter of 63 mm. Excitation frequency was chosen in the range of 500 Hz - 700 Hz. Synthetic jets favourably influenced separated flow on the vane profiles in the distance of (5 - 12) mm from the casing surface. The reduction of flow separation area caused in the region near the casing the decrease of the profile loss coefficient approximately by 20%.

  14. A field guide to digital color

    CERN Document Server

    Stone, Maureen

    2013-01-01

    Maureen Stone's field guide to digital color presents a survey of digital color with special emphasis on those fields important for computer graphics. The book provides the foundation for understanding color and its applications, discusses color media and color management and the use of color in computer graphics, including color design and selection. The book provides a guide for anyone who wants to understand and apply digital color. An annotated bibliography provides in-depth references for further study on each topic.

  15. Three-dimensional model and simulation of vacuum arcs under axial magnetic fields

    Science.gov (United States)

    Wang, Lijun; Jia, Shenli; Zhou, Xin; Wang, Haijing; Shi, Zongqian

    2012-01-01

    In this paper, a three-dimensional (3d) magneto-hydro-dynamic (MHD) model of axial magnetic field vacuum arcs (AMFVAs) is established. Based on this model, AMFVAs are simulated and analyzed. Three-dimensional spatial distributions of many important plasma parameters and electric characteristics in AMFVAs can be obtained, such as ion number density, ion temperature, electron temperature, plasma pressure, current densities along different directions (x, y, and z), ion velocities along different directions, electric fields strength along different directions, and so on. Simulation results show that there exist significant spiral-shaped rotational phenomena in the AMFVAs, this kind of rotational phenomenon also can be verified by the many related experiments (AMFVAs photographs, especially for stronger AMF strength). For current simulation results of AMFVAs, the maximal rotational velocity at anode side is about 1100 m/s. Radial electric field is increased from arc center to arc edge; axial electric field is decreased from cathode side to anode side. Radial electric field at arc edge can be larger than axial electric field. Azimuthal electric field in most regions is much smaller than radial and axial electric field, but it can reach about 1.19 kV/m. Radial magnetic field is the smallest one compared with other components, it reaches to maximum value at the position near to anode, it can influence arc characteristics.

  16. Field guide to hospital cafeterias.

    Science.gov (United States)

    Smith, R P

    1986-09-01

    We have all faced the problem of whether or not to venture into that gastronomic wasteland known as the hospital cafeteria. Hospital cafeterias have developed a reputation, deserved or otherwise, as less than ideal places to eat. Many people overlook the fact that this is a direct result of trying to provide patient meals that are salt-free, sugar-free, fiber-free, and taste-free. (Some faint traces of color may, occasionally, be found.) How then does one go about choosing whether to venture in, and how does one survive the encounter once there? The following guide has been assembled to help the reader through this difficult process.

  17. Enhancement of the Excitation Efficiency of the Non-Contact Magnetostrictive Sensor for Pipe Inspection by Adjusting the Alternating Magnetic Field Axial Length

    Directory of Open Access Journals (Sweden)

    Pengfei Sun

    2014-01-01

    Full Text Available The non-contact magnetostrictive sensor (MsS has been widely used in the guided wave testing of pipes, cables, and so on. However, it has a disadvantage of low excitation efficiency. A new method for enhancing the excitation efficiency of the non-contact MsS for pipe inspection using guided waves, by adjusting the axial length of the excitation magnetic field, is proposed. A special transmitter structure, in which two copper rings are added beside the transmitter coil, is used to adjust the axial length at the expense of weakening the excitation magnetic field. An equivalent vibration model is presented to analyze the influence of the axial length variation. The final result is investigated by experiments. Results show that the excitation efficiency of the non-contact MsS is enhanced in the whole inspection frequency range of the L(0,2 mode if the axial length is adjusted to a certain value. Moreover that certain axial length is the same for pipes of different sizes but made of the same material.

  18. Experimental investigation of axial plasma injection into a magnetic dipole field

    DEFF Research Database (Denmark)

    Jensen, Vagn Orla

    1968-01-01

    A high-density helium plasma, accelerated from a conical pinch, is injected axially into a magnetic dipole field. Magnetic probe measurements show that, near the axis, a compression of the field is super-imposed on the standard diamagnetic depression. The compression starts downstream and moves...

  19. Watching Nature: A Beginner's Field Guide.

    Science.gov (United States)

    Russo, Monica

    This field guide provides guidance to beginners on how to look for clues to animal activities; remember bird songs; attract birds, butterflies, and other wildlife to the backyard; develop the skills needed to identify wildflowers; look for distinctive field marks on wildlife; keep an accurate journal of outdoor discoveries; and make on-the-spot…

  20. Tangential Velocity Profile for Axial Flow Through Two Concentric Rotating Cylinders with Radial Magnetic Field

    Directory of Open Access Journals (Sweden)

    Girishwar Nath

    1970-10-01

    Full Text Available A closed form solution of the Navier-Stokes equations has been obtained in the case of steady axisymmetric flow of an incompressible electrically conducting viscous fluid between two concentric rotating cylinders composed of an insulating material under the influence of radial magnetic field. It has been found that the velocity components are less than those of the classical hydrodynamic case. In the presence of the magnetic field, the tangential velocity becomes fully developed in a smaller axial distance than in the absence of the magnetic field. For small Reynolds number, the fully developed tangential velocity is achieved in a small axial distance, but it requires greater axial distance for large Reynolds number.

  1. Numerical Investigation of Influence of Tangent Pitch and Slanting Flow of Guide Vanes on the Axial Compressor Stage Parameters

    Directory of Open Access Journals (Sweden)

    D. V. Arkhipov

    2015-01-01

    Full Text Available The flow redistribution in the axial stage through the stator axis blade deformation can create favorable conditions for raising stage efficiency and combined actions for axial compressor elements especially in ambient conditions. For this purpose, the axis deformation impact on the gas-dynamic stability margin and the coefficient of efficiency of axial compressor has been numerically investigated.The influence of guide vane (GV axis was considered with invariable rotor blades and different variants of stator. The GV axis form was changed on the arc of a circle in the range of ± 15% guide vane height in circumferential direction and in the axial direction in the range ± 10% of guide vane height, increments ± 2.5%.As an object, for investigation was chosen a numerical 3D model of transonic stage of axial compressor with the following values of basic parameters: circumferential speed in the rotor blade trips of 345 m/s, relative diameter of the hub being 0.7, and coefficient of discharge being 0.5. The stage was profiling by classic low Cu*r=const. Rotor and stator profiles for all variants under investigation were the same in the same radii.As to initial radial axis guide vane, the losses of total pressure in stator become substantially less throughout the height of blade in case there is a guide vane axis bending in axial direction in line of flow. Bending of the axis in the circumferential direction against the rotation leads to reducing total pressure losses especially in hub and shroud regions, and in the flow core there is no change.In future, the effects of a tangent pitch and a slanting flow can be of interest in case of the simultaneous bending in both directions, as well as when studying the influence of bending of the guide vanes, which are a part of a sector of stages and a multi-stage compressor in a wide range of operating conditions.

  2. Axial-field permanent magnet motors for electric vehicles

    Science.gov (United States)

    Campbell, P.

    1981-01-01

    The modelling of an anisotropic alnico magnet for the purpose of field computation involves assigning a value for the material's permeability in the transverse direction. This is generally based upon the preferred direction properties, being all that are easily available. By analyzing the rotation of intrinsic magnetization due to the self demagnetizing field, it is shown that the common assumptions relating the transverse to the preferred direction are not accurate. Transverse magnetization characteristics are needed, and these are given for Alnico 5, 5-7, and 8 magnets, yielding appropriate permeability values.

  3. Remote Sensing Field Guide - Desert

    Science.gov (United States)

    1991-09-01

    sea in North America is in the Gran Desierto of northern Sonora, Mexico, which extends northward into the Yuma Desert of Arizona and the Algodones...parallel to the dune chains. PATTERN INDICATOR SHEET - DESERT DUNES PHOTO: AERIAL (OBLIQUE) STAR - COMPOUND LOCATION: Mexico (Northern) El Gran Desierto ...dunes. This field is in the central part of El Gran Desierto about 20 km south of the Arizona-Mexico border Photo B (on back) is a closer view. For orien

  4. The concept of a plasma centrifuge with a high frequency rotating magnetic field and axial circulation

    Science.gov (United States)

    Borisevich, V. D.; Potanin, E. P.

    2017-07-01

    The possibility of using a rotating magnetic field (RMF) in a plasma centrifuge (PC), with axial circulation to multiply the radial separation effect in an axial direction, is considered. For the first time, a traveling magnetic field (TMF) is proposed to drive an axial circulation flow in a PC. The longitudinal separation effect is calculated for a notional model, using specified operational parameters and the properties of a plasma, comprising an isotopic mixture of 20Ne-22Ne and generated by a high frequency discharge. The optimal intensity of a circulation flow, in which the longitudinal separation effect reaches its maximum value, is studied. The optimal parameters of the RMF and TMF for effective separation, as well as the centrifuge performance, are calculated.

  5. The Astrobiology Field Guide in World Wind

    Science.gov (United States)

    Scalice, D. M.

    2004-12-01

    In collaboration with the Australian Centre for Astrobiology (ACA), and NASA Learning Technologies (NLT), and utilizing the powerful visualization capabilities of their "World Wind" software, the NASA Astrobiology Institute (NAI) is crafting a prototype "Astrobiology Field Guide" to bring the field experiences and stories of astrobiology science to the public and classrooms around the world. The prototype focuses on one region in particular - The Pilbara in Western Australia. This first Field Guide "hotspot" is an internationally recognized area hosting the best known example of the earliest evidence of life on Earth - a stromatolitic chert precipitation in the 3.45 Ga Warrawoona Group. The goal of the Astrobiology Field Guide is to engage students of all ages with the ongoing field expeditions of today's astrobiologists as they explore the ends of the Earth searching for clues to life's origin, evolution, and distribution in the Universe. The NAI hopes to expand this Field Guide to include many more astrobiologically relevant areas across the globe such as Cuatro Cienegas in Mexico, the Rio Tinto in Spain, Yellowstone National Park in the US, and the Lost City hydrothermal vent field on the mid-Atlantic ridge - and possibly sites on Mars. To that end, we will be conducting feasibility studies and evaluations with informal and formal education contacts. The Astrobiology Field Guide is also serving as a cornerstone to educational materials being developed focused on the Pilbara region for use in classrooms in Australia, the UK, and potentially the US. These materials are being developed by the Australian Centre for Astrobiology, and the ICT Innovations Centre at Macquarie University in Sydney, in collaboration with the NAI and the Centre for Astronomy and Science Education at the University of Glamorgan in the UK.

  6. CFD Numerical Simulation of the Complex Turbulent Flow Field in an Axial-Flow Water Pump

    Directory of Open Access Journals (Sweden)

    Wan-You Li

    2014-09-01

    Full Text Available Further optimal design of an axial-flow water pump calls for a thorough recognition of the characteristics of the complex turbulent flow field in the pump, which is however extremely difficult to be measured using the up-to-date experimental techniques. In this study, a numerical simulation procedure based on computational fluid dynamics (CFD was elaborated in order to obtain the fully three-dimensional unsteady turbulent flow field in an axial-flow water pump. The shear stress transport (SST k-ω model was employed in the CFD calculation to study the unsteady internal flow of the axial-flow pump. Upon the numerical simulation results, the characteristics of the velocity field and pressure field inside the impeller region were discussed in detail. The established model procedure in this study may provide guidance to the numerical simulations of turbomachines during the design phase or the investigation of flow and pressure field characteristics and performance. The presented information can be of reference value in further optimal design of the axial-flow pump.

  7. Nonexistence of interactions between axially symmetric massive scalar field and perfect fluid distribution

    Energy Technology Data Exchange (ETDEWEB)

    Tarachand, R.K.; Singh, N.I.

    1988-07-01

    Considering the axially symmetric Einstein-Rosen metric, the problem of massive scalar field interactions in the presence of perfect fluid distribution has been studied, and it has been observed that there cannot exist any solution for the coupled massive scalar field and perfect fluid distribution for the metric. The problem reduces to the finding of interactions between zero-mass scalar field and stiff fluid.

  8. Cold atmospheric plasma jet in an axial DC electric field

    Science.gov (United States)

    Lin, Li; Keidar, Michael

    2016-08-01

    Cold atmospheric plasma (CAP) jet is currently intensively investigated as a tool for new and potentially transformative cancer treatment modality. However, there are still many unknowns about the jet behavior that requires attention. In this paper, a helium CAP jet is tested in an electrostatic field generated by a copper ring. Using Rayleigh microwave scattering method, some delays of the electron density peaks for different ring potentials are observed. Meanwhile, a similar phenomenon associated with the bullet velocity is found. Chemical species distribution along the jet is analyzed based on the jet optical emission spectra. The spectra indicate that a lower ring potential, i.e., lower DC background electric field, can increase the amount of excited N2, N2+, He, and O in the region before the ring, but can decrease the amount of excited NO and HO almost along the entire jet. Combining all the results above, we discovered that an extra DC potential mainly affects the temporal plasma jet properties. Also, it is possible to manipulate the chemical compositions of the jet using a ring with certain electric potentials.

  9. Numerical simulation of a helical shape electric arc in the external axial magnetic field

    Science.gov (United States)

    Urusov, R. M.; Urusova, I. R.

    2016-10-01

    Within the frameworks of non-stationary three-dimensional mathematical model, in approximation of a partial local thermodynamic equilibrium, a numerical calculation was made of characteristics of DC electric arc burning in a cylindrical channel in the uniform external axial magnetic field. The method of numerical simulation of the arc of helical shape in a uniform external axial magnetic field was proposed. This method consists in that that in the computational algorithm, a "scheme" analog of fluctuations for electrons temperature is supplemented. The "scheme" analogue of fluctuations increases a weak numerical asymmetry of electrons temperature distribution, which occurs randomly in the course of computing. This asymmetry can be "picked up" by the external magnetic field that continues to increase up to a certain value, which is sufficient for the formation of helical structure of the arc column. In the absence of fluctuations in the computational algorithm, the arc column in the external axial magnetic field maintains cylindrical axial symmetry, and a helical form of the arc is not observed.

  10. Drift-diffusion model of normal glow discharge in an axial magnetic field

    Science.gov (United States)

    Surzhikov, S. T.

    2016-12-01

    A two-dimensional axisymmetrical computing model is formulated with using of which the mathematical modeling of the normal glow discharge in molecular hydrogen is fulfilled in an axial magnetic field with the induction B = 0.1 T in the pressure range p = 1.25-5 Torr and the current-source electromotive force E = 1-3 kV.

  11. Parallax error in long-axial field-of-view PET scanners—a simulation study

    Science.gov (United States)

    Schmall, Jeffrey P.; Karp, Joel S.; Werner, Matt; Surti, Suleman

    2016-07-01

    There is a growing interest in the design and construction of a PET scanner with a very long axial extent. One critical design challenge is the impact of the long axial extent on the scanner spatial resolution properties. In this work, we characterize the effect of parallax error in PET system designs having an axial field-of-view (FOV) of 198 cm (total-body PET scanner) using fully-3D Monte Carlo simulations. Two different scintillation materials were studied: LSO and LaBr3. The crystal size in both cases was 4  ×  4  ×  20 mm3. Several different depth-of-interaction (DOI) encoding techniques were investigated to characterize the improvement in spatial resolution when using a DOI capable detector. To measure spatial resolution we simulated point sources in a warm background in the center of the imaging FOV, where the effects of axial parallax are largest, and at several positions radially offset from the center. Using a line-of-response based ordered-subset expectation maximization reconstruction algorithm we found that the axial resolution in an LSO scanner degrades from 4.8 mm to 5.7 mm (full width at half max) at the center of the imaging FOV when extending the axial acceptance angle (α) from  ±12° (corresponding to an axial FOV of 18 cm) to the maximum of  ±67°—a similar result was obtained with LaBr3, in which the axial resolution degraded from 5.3 mm to 6.1 mm. For comparison we also measured the degradation due to radial parallax error in the transverse imaging FOV; the transverse resolution, averaging radial and tangential directions, of an LSO scanner was degraded from 4.9 mm to 7.7 mm, for a measurement at the center of the scanner compared to a measurement with a radial offset of 23 cm. Simulations of a DOI detector design improved the spatial resolution in all dimensions. The axial resolution in the LSO-based scanner, with α  =  ± 67°, was improved from 5.7 mm to 5.0 mm by

  12. Field Guide to Interferometric Optical Testing

    CERN Document Server

    Goodwin, Eric P

    2006-01-01

    A distillation of Dr. Wyant's course at the University of Arizona, this Field Guide covers the key fundamentals of interferometry, types of interferometers and interferograms, concepts of phase-shifting interferometry, long-wavelength interferometry, testing of aspheric surfaces, measurement of surface microstructure, flat and curved surface testing, and absolute measurements.

  13. Direct measurement of the beam deflection angle using the axial B-dot field

    Directory of Open Access Journals (Sweden)

    Xiaozhong He

    2011-05-01

    Full Text Available Beam position monitors are an important diagnostics tool for particle accelerator operation and related beam dynamics research. The measurement of the beam deflection angle, or moving direction of a charged particle beam with respect to the beam pipe axis, can provide useful additional information. Beam monitors sensitive to the beam’s azimuthal B-dot field (sometimes referred as B dots are used to measure the displacement (position of the beam centroid, as the beam generates a dipole term of the azimuthal magnetic field. Similarly, a dipole term of the axial magnetic field will be generated by the beam moving in a direction not parallel to the axis of the beam pipe. In this paper, a new method using the axial B-dot field is presented to measure the beam deflection angle directly, including the theoretical background. Simulations using the MAFIA numerical code have been performed, demonstrating a good agreement to the new established analytical model.

  14. Night sky a falcon field guide

    CERN Document Server

    Nigro, Nicholas

    2012-01-01

    Night Sky: A Falcon Field Guide covers both summer and winter constellations, planets, and stars found in the northern hemisphere. Conveniently sized to fit in a pocket and featuring detailed photographs, this informative guide makes it easy to identify objects in the night sky even from one's own backyard. From information on optimal weather conditions, preferred viewing locations, and how to use key tools of the trade, this handbook will help you adeptly navigate to and fro the vast and dynamic nighttime skies, and you'll fast recognize that the night sky's the limit.

  15. Pulsed field gel electrophoresis a practical guide

    CERN Document Server

    Birren, Bruce

    1993-01-01

    Pulsed Field Gel Electrophoresis: A Practical Guide is the first laboratory manual to describe the theory and practice of this technique. Based on the authors' experience developing pulsed field gel instruments and teaching procedures, this book provides everything a researcher or student needs to know in order to understand and carry out pulsed field gel experiments. Clear, well-tested protocols assume only that users have a basic familiarity with molecular biology. Thorough coverage of useful data, theory, and applications ensures that this book is also a lasting resource for more adv

  16. Proterozoic low orbital obliquity and axial-dipolar geomagnetic field from evaporite palaeolatitudes.

    Science.gov (United States)

    Evans, David A D

    2006-11-02

    Palaeomagnetism of climatically sensitive sedimentary rock types, such as glacial deposits and evaporites, can test the uniformitarianism of ancient geomagnetic fields and palaeoclimate zones. Proterozoic glacial deposits laid down in near-equatorial palaeomagnetic latitudes can be explained by 'snowball Earth' episodes, high orbital obliquity or markedly non-uniformitarian geomagnetic fields. Here I present a global palaeomagnetic compilation of the Earth's entire basin-scale evaporite record. Magnetic inclinations are consistent with low orbital obliquity and a geocentric-axial-dipole magnetic field for most of the past two billion years, and the snowball Earth hypothesis accordingly remains the most viable model for low-latitude Proterozoic ice ages. Efforts to reconstruct Proterozoic supercontinents are strengthened by this demonstration of a consistently axial and dipolar geomagnetic reference frame, which itself implies stability of geodynamo processes on billion-year timescales.

  17. Proterozoic low orbital obliquity and axial-dipolar geomagnetic field from evaporite palaeolatitudes

    Science.gov (United States)

    Evans, David A. D.

    2006-11-01

    Palaeomagnetism of climatically sensitive sedimentary rock types, such as glacial deposits and evaporites, can test the uniformitarianism of ancient geomagnetic fields and palaeoclimate zones. Proterozoic glacial deposits laid down in near-equatorial palaeomagnetic latitudes can be explained by `snowball Earth' episodes, high orbital obliquity or markedly non-uniformitarian geomagnetic fields. Here I present a global palaeomagnetic compilation of the Earth's entire basin-scale evaporite record. Magnetic inclinations are consistent with low orbital obliquity and a geocentric-axial-dipole magnetic field for most of the past two billion years, and the snowball Earth hypothesis accordingly remains the most viable model for low-latitude Proterozoic ice ages. Efforts to reconstruct Proterozoic supercontinents are strengthened by this demonstration of a consistently axial and dipolar geomagnetic reference frame, which itself implies stability of geodynamo processes on billion-year timescales.

  18. Radiofrequency hydrogen ion source with permanent magnets providing axial magnetic field.

    Science.gov (United States)

    Oikawa, Kohei; Saito, Yuta; Komizunai, Shota; Takahashi, Kazunori; Ando, Akira

    2014-02-01

    Uniform axial magnetic field of about 70 G is applied to a radiofrequency (rf) hydrogen ion source by arrays of permanent magnets. The plasma density and electron temperature downstream of the source and near the magnetic filter are compared with those in the previously described ion source, where the axial field has been applied by two solenoids. The source is operated at ∼350 kHz and above 10 kW rf power with a field-effect-transistor-based invertor power supply in 1.5 Pa hydrogen. The results show that the plasma density of ∼10(19) m(-3) near the source exit and ∼10(18) m(-3) near the magnetic filter can be obtained, which are higher than those with the solenoids.

  19. Radiofrequency hydrogen ion source with permanent magnets providing axial magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Oikawa, Kohei, E-mail: oikawa@ecei.tohoku.ac.jp; Saito, Yuta; Komizunai, Shota; Takahashi, Kazunori; Ando, Akira [Department of Electrical Engineering, Tohoku University, Sendai 980-8579 (Japan)

    2014-02-15

    Uniform axial magnetic field of about 70 G is applied to a radiofrequency (rf) hydrogen ion source by arrays of permanent magnets. The plasma density and electron temperature downstream of the source and near the magnetic filter are compared with those in the previously described ion source, where the axial field has been applied by two solenoids. The source is operated at ∼350 kHz and above 10 kW rf power with a field-effect-transistor-based invertor power supply in 1.5 Pa hydrogen. The results show that the plasma density of ∼10{sup 19} m{sup −3} near the source exit and ∼10{sup 18} m{sup −3} near the magnetic filter can be obtained, which are higher than those with the solenoids.

  20. Influence of axial self-magnetic field component on arcing behavior of spiral-shaped contacts

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Dingyu; Xiu, Shixin, E-mail: xsx@mail.xjtu.edu.cn; Wang, Yi; Liu, Gang [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China); Zhang, Yali; Bi, Dongli [Shaanxi Baoguang Vacuum Electric Device Co., Ltd., 53 Xibao Road, Baoji 721006 (China)

    2015-10-15

    The transverse magnetic field (TMF) contact design is commonly used in vacuum interrupters. When arcing occurs between the TMF contacts, the contact structure can create a self-induced magnetic field that drives the arc to move and rotate on the contact, and thus local overheating and severe erosion can be avoided. However, TMF contacts could also create an axial self-magnetic component, and the influence of this component on the arc behavior has not been considered to date. In this paper, five different types of Cu-Cr spiral-shaped TMF contacts with three different structures are investigated in a demountable vacuum chamber that contains a high-speed charge-coupled device video camera. It was found that the contact structure greatly influenced the arc behavior, especially in terms of arc rotation and the effective contact area, while contacts with the same slot structure but different diameters showed similar arc behavior and arc motion. The magnetic field distribution and the Lorentz force of each of the three different contact structures are simulated, and the axial self-magnetic field was first taken into consideration for investigation of the TMF contact design. It was found that contact designs that have higher axial self-magnetic field components tend to have arc columns with larger diameters and show poorer arc motion and rotation performance in the experiments.

  1. Study Report of Design Guide for Single Circular Cylinder in Axial Flow

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The vibration of a flexible cylinder in axial flow is random, so the quantities of interests are the root-mean-square value of the response and the amplitude distribution. This design guideline presents a relationship for calculating the

  2. Empirical trials of plant field guides.

    Science.gov (United States)

    Hawthorne, W D; Cable, S; Marshall, C A M

    2014-06-01

    We designed 3 image-based field guides to tropical forest plant species in Ghana, Grenada, and Cameroon and tested them with 1095 local residents and 20 botanists in the United Kingdom. We compared users' identification accuracy with different image formats, including drawings, specimen photos, living plant photos, and paintings. We compared users' accuracy with the guides to their accuracy with only their prior knowledge of the flora. We asked respondents to score each format for usability, beauty, and how much they would pay for it. Prior knowledge of plant names was generally low (<22%). With a few exceptions, identification accuracy did not differ significantly among image formats. In Cameroon, users identifying sterile Cola species achieved 46-56% accuracy across formats; identification was most accurate with living plant photos. Botanists in the United Kingdom accurately identified 82-93% of the same Cameroonian species; identification was most accurate with specimens. In Grenada, users accurately identified 74-82% of plants; drawings yielded significantly less accurate identifications than paintings and photos of living plants. In Ghana, users accurately identified 85% of plants. Digital color photos of living plants ranked high for beauty, usability, and what users would pay. Black and white drawings ranked low. Our results show the potential and limitations of the use of field guides and nonspecialists to identify plants, for example, in conservation applications. We recommend authors of plant field guides use the cheapest or easiest illustration format because image type had limited bearing on accuracy; match the type of illustration to the most likely use of the guide for slight improvements in accuracy; avoid black and white formats unless the audience is experienced at interpreting illustrations or keeping costs low is imperative; discourage false-positive identifications, which were common; and encourage users to ask an expert or use a herbarium for

  3. Axial electric wake field inside the induction gap exited by the intense electron beam

    Institute of Scientific and Technical Information of China (English)

    ZHANG Kai-Zhi; ZHANG Huang; LONG Ji-Dong; YANG Guo-Jun; HE Xiao-Zhong; WANG Hua-Cen

    2008-01-01

    While an intense electron beam passes through the accelerating gaps of a linear induction accelerator,a strong wake field will be excited.In this paper a relatively simple model is established based on the interaction between the transverse magnetic wake field and the electron beam,and the numerical calculation in succession generates a magnetic wake field distribution along the accelerator and along the beam pulse as well.The axial electric wake field is derived based on the relation between field components of a resonant mode.According to some principles in existence,the influence of this field on the high voltage properties of the induction gap is analyzed.The Dragon-I accelerator is taken as an example,and its maximum electric wake field is about 17 kV/cm,which means the effect of the wake field is noticeable.

  4. Orbital motion in generalized static fields of FELs accounting for axial magnetic field, beam forces, undulator and external focusing

    Energy Technology Data Exchange (ETDEWEB)

    Papadichev, V.A. [Lebedev Physical Institute, Moscow (Russian Federation)

    1995-12-31

    Various types of undulators with or without axial magnetic field are used in FELs. Supplementary beam focusing can be applied by wedging, inclining or profiling pole faces of plan undulators or superposing external focusing magnetic fields in addition to undulator own focusing. Space-charge forces influence significantly particle motion in high-current, low-energy electron beams. Finally, one can use simultaneously two or more different undulators for some specific purpose: more efficient and selective higher harmonics generation, changing polarization types and direction, gain enhancement in double-period undulator etc. All these cases can be treated by solving the generalized equations of transverse orbital motion in a linear approximation, which is widely used for orbit calculation, gives sufficient accuracy for practical purposes and allows to consider many variants and optimize the chosen one. The undulator field is described as a field of two plane undulators with mutually orthogonal fields and an arbitrary axial (phase) shift between them. Various values of the phase shift correspond to right- or left-handed helical undulators, plane undulator of different polarization etc. The general formulae are reduced to forms that allow easier examination of particular cases: planar or helical undulator combined with axial magnetic field or without it, gyroresonance, limiting beam current, polarization etc.

  5. Analysis of the axial electric field in a plasma-loaded-helix travelling wave tube

    Institute of Scientific and Technical Information of China (English)

    Xie Hong-Quan; Liu Pu-Kun

    2006-01-01

    A helix type slow wave structure filled with plasma is immersed in a strong longitudinal magnetic field. Taking into account the effect of the plasma and the dielectric, the system is separated radially into three regions. By means of the sheath model and Maxwell equation, the distribution of the electromagnetic field is established. Using the boundary conditions of each region, the dispersion relation of the slow wave structure is derived. The trend of change for the radial profile of the axial electric field is analysed respectively in different plasma densities, plasma column radius and dielectric constant by numerical computation. Some useful results are obtained on the basis of the discussion.

  6. The use of circumferentially varying stagger guide vanes in an axial flow pump or compressor

    Science.gov (United States)

    Horlock, J. H.

    1990-04-01

    An actuator disk analysis is given of the flow through a guide vane and rotor combination. It is shown that changes in total pressure across the rotor are, in general, related to circumferential variations in guide vane outlet angle. In particular, known variations in inlet total pressure may be eliminated by suitable circumferential changes in guide vane stagger.

  7. 轴流式血泵流场CFD仿真%Flow field CFD analysis of axial flow blood pump

    Institute of Scientific and Technical Information of China (English)

    谢雄; 谭建平

    2014-01-01

    In the development of axial flow blood pump,the arterial partial flow field may produce an area with very low flow shear rate,so it is necessary to consider the non-Newtonian charac-teristics of blood fluid.In this paper,a model of axial flow blood pump was established,and flow and rotate-speed’s impacts on the inlet and outlet of the flow field in the blood pump were ana-lyzed through Computational Fluid Dynamics (CFD)simulation,as wel as the influence of the guide vane on the flow field.By the pump water experiment of the designed blood pump,its out-put flow and pressure were measured;the results show that the designed blood pump is consist-ent on the law with the simulation.%在轴流式血泵的研发过程中,动脉局部流场中可能产生流动剪切率非常低的区域,因此有必要考虑血液的非牛顿特性。建立了轴流式血泵模型,通过CFD仿真分析得到血泵转速和流量的变化对血泵出入口压力分布和速度分布的影响,并采用水和甘油(2∶1)的混合流体替代血液,对设计的血泵进行驱动实验,测量了轴流式血泵输出流量和压力参数。结果表明:所设计的血泵在规律上和仿真是相符的。

  8. Modelling of the Noise Spectra of Axial Flow Fans in a Free Field

    Science.gov (United States)

    Wu, S. F.; Su, S. G.; Shah, H. S.

    1997-03-01

    This paper presents a semi-empirical formula for predicting the noise spectra of axial flow fans in a free field. The basic assumption made in deriving this formula is that sound radiation from an axial flow fan in a free field is primarily due to the fluctuating pressure exerted on the fan blade surface. This fluctuating pressure is correlated to the lift force per unit length acting on the fan blade, and is subsequently approximated by pressure pulses that decay both in space and time. Accordingly, the radiated acoustic pressure is expressed in terms of superposition of contributions from these pressure pulses, and the line spectrum is obtained by taking a Fourier series expansion. To simulate the narrow and broad band sound spectra, a normal distribution-like shape function is designed which divides the frequency into consecutive bands centered at the blade passage frequency and its harmonics. The amplitude of this shape function at the center frequency of each band is unity but decays exponentially. The decay rate decreases with an increase in the number of bands. Thus, at high frequencies the narrow bands merge to form broad band-like spectra. The noise spectra thus obtained are compared with the measured ones from four different types of axial flow fans running under various conditions, and a favorable agreement in each case is obtained.

  9. Field trials results of guided wave tomography

    Science.gov (United States)

    Volker, Arno; van Zon, Tim; van der Leden, Edwin

    2015-03-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Guided wave travel time tomography is a method capable of providing an absolute wall thickness map. This method is currently making the transition from the laboratory to the field. For this purpose a dedicated data acquisition system and special purpose EMAT sensor rings have been developed. The system can be deployed for permanent monitoring and inspections. Field trials have been conducted on various pipes with different diameters, containing either liquid or gas. The main focus has been on pipe supports. The results demonstrate the successful operation of the technology in the field. Expected corrosion damage was clearly visible on the produced results enabling asset owner to make calculated decisions on the pipelines safety, maintenance and operations.

  10. Control of Collection Efficiency for Axial Flow Cyclone Dust Collectors with Fixed Guide Vanes and with Funnel Shaped Exit Pipes

    Institute of Scientific and Technical Information of China (English)

    Akira Ogawa; Masaru Arakawa

    2006-01-01

    The experimental result of the collection efficiency of the axial flow cyclone with the fixed guide vanes is lower than that with the tangential inlet pipe to the cyclone body due to the weak angular momentum transfer given by flowing through the guide vanes. However, one of the interesting points is the control of the collection efficiency depended on the funnel shaped exit pipes. The collection efficiencies for these funnel shaped exit pipes are depended on the Froude number. Then, in this paper, the experimental results of the pressure drop and also the collection efficiency using the fly-ash particles and also the comparison of the calculated results of the collection efficiency with the experimental results are described in detail.

  11. Guided wave propagation as a measure of axial loads in rails

    CSIR Research Space (South Africa)

    Loveday, PW

    2010-03-01

    Full Text Available was formulated analytically and computed. In practice, by using separation of signals in time it would only be possible to separate the mode with the greatest group velocity over a reasonable distance. It was found that the influence of axial load...

  12. Effect of axial magnetic field on a 2.45 GHz permanent magnet ECR ion source

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, T., E-mail: tsubasa@oshima-k.ac.jp; Wada, H.; Furuse, M. [National Institute of Technology, Oshima College, 1091-1 Komatsu, Suouoshima, Oshima, Yamaguchi 742-2193 (Japan); Asaji, T. [National Institute of Technology, Toyama College, 13 Hongo, Toyama 939-8630 (Japan)

    2016-02-15

    Herein, we conduct a fundamental study to improve the generation efficiency of a multi-charged ion source using argon. A magnetic field of our electron cyclotron resonance ion source is composed of a permanent magnet and a solenoid coil. Thereby, the axial magnetic field in the chamber can be tuned. Using the solenoid coil, we varied the magnetic field strength in the plasma chamber and measured the ion beam current extracted at the electrode. We observed an approximately three times increase in the Ar{sup 4+} ion beam current when the magnetic field on the extractor-electrode side of the chamber was weakened. From our results, we can confirm that the multi-charged ion beam current changes depending on magnetic field intensity in the plasma chamber.

  13. Nongyrotropic Electrons in Guide Field Reconnection

    Science.gov (United States)

    Wendel, D. E.; Hesse, M.; Bessho, N.; Adrian, M. L.; Kuznetsova, M.

    2016-01-01

    We apply a scalar measure of nongyrotropy to the electron pressure tensor in a 2D particle-in-cell simulation of guide field reconnection and assess the corresponding electron distributions and the forces that account for the nongyrotropy. The scalar measure reveals that the nongyrotropy lies in bands that straddle the electron diffusion region and the separatrices, in the same regions where there are parallel electric fields. Analysis of electron distributions and fields shows that the nongyrotropy along the inflow and outflow separatrices emerges as a result of multiple populations of electrons influenced differently by large and small-scale parallel electric fields and by gradients in the electric field. The relevant parallel electric fields include large-scale potential ramps emanating from the x-line and sub-ion inertial scale bipolar electron holes. Gradients in the perpendicular electric field modify electrons differently depending on their phase, thus producing nongyrotropy. Magnetic flux violation occurs along portions of the separatrices that coincide with the parallel electric fields. An inductive electric field in the electron EB drift frame thus develops, which has the effect of enhancing nongyrotropies already produced by other mechanisms and under certain conditions producing their own nongyrotropy. Particle tracing of electrons from nongyrotropic populations along the inflows and outflows shows that the striated structure of nongyrotropy corresponds to electrons arriving from different source regions. We also show that the relevant parallel electric fields receive important contributions not only from the nongyrotropic portion of the electron pressure tensor but from electron spatial and temporal inertial terms as well.

  14. SharePoint 2010 Field Guide

    CERN Document Server

    Mann, Steven; Gazmuri, Pablo; Caravajal, Steve; Wheeler, Christina

    2012-01-01

    Hands-on solutions for common SharePoint 2010 challenges Aimed at the more than 100 million licensed SharePoint 2010 users, this indispensable field guide addresses an abundance of common SharePoint 2010 problems and offers proven solutions. A team of authors encourages you to customize SharePoint beyond the out-of-the-box functionality so that you can build more complex solutions to these challenges. You?ll discover intricate details and specific full-scale solutions that you can then implement to your own SharePoint 2010 solutions.Tackles a variety of SharePoint 2010 problems ranging from si

  15. Numerical simulations on the flow fields of dynamic axial compression columns in chromatography processes

    Science.gov (United States)

    Chien Liang, Ru; Che Liu, Cheng; Tsai Liang, Ming; Chen, Jiann Lin

    2017-02-01

    Dynamic axial compression (DAC) columns are key elements in Simulated Moving Bed, which is a chromatography process in drug industry and chemical engineering. In this study, we apply the computational fluid dynamics (CFD) technique to analyze the flow fields in the DAC column and propose rules for distributor design based on mass conservation in fluid dynamics. Computer aided design (CAD) is used in constructing the numerical 3D modelling for the mesh system. The laminar flow fields with Darcy’s law to model the porous zone are governed by the Navier-Stokes equations and employed to describe the porous flow fields. Experimental works have been conducted as the benchmark for us to choose feasible porous parameters for CFD. Besides, numerical treatments are elaborated to avoid calculation divergence resulting from large source terms. Results show that CFD combined with CAD is a good approach to investigate detailed flow fields in DAC columns and the design for distributors is straightforward.

  16. A Field Trip Planning Guide for Early Childhood Classes.

    Science.gov (United States)

    Martin, Sylvia S.; Seevers, Randy L.

    2003-01-01

    This article provides a guide for planning field trips for educational engagement of all children in early childhood education settings. Based on interviews, environmental assessments, and evaluations of activities, it includes field trip considerations and a field trip planning guide that includes the teacher, the parents, and the field site…

  17. Effect of Radial Density Configuration on Wave Field and Energy Flow in Axially Uniform Helicon Plasma

    Science.gov (United States)

    Chang, Lei; Li, Qingchong; Zhang, Huijie; Li, Yinghong; Wu, Yun; Zhang, Bailing; Zhuang, Zhong

    2016-08-01

    The effect of the radial density configuration in terms of width, edge gradient and volume gradient on the wave field and energy flow in an axially uniform helicon plasma is studied in detail. A three-parameter function is employed to describe the density, covering uniform, parabolic, linear and Gaussian profiles. It finds that the fraction of power deposition near the plasma edge increases with density width and edge gradient, and decays in exponential and “bump-on-tail” profiles, respectively, away from the surface. The existence of a positive second-order derivative in the volume density configuration promotes the power deposition near the plasma core, which to our best knowledge has not been pointed out before. The transverse structures of wave field and current density remain almost the same during the variation of density width and gradient, confirming the robustness of the m=1 mode observed previously. However, the structure of the electric wave field changes significantly from a uniform density configuration, for which the coupling between the Trivelpiece-Gould (TG) mode and the helicon mode is very strong, to non-uniform ones. The energy flow in the cross section of helicon plasma is presented for the first time, and behaves sensitive to the density width and edge gradient but insensitive to the volume gradient. Interestingly, the radial distribution of power deposition resembles the radial profile of the axial component of current density, suggesting the control of the power deposition profile in the experiment by particularly designing the antenna geometry to excite a required axial current distribution. supported by National Natural Science Foundation of China (No. 11405271)

  18. Field Guides Made Easy. 4-H Leader's Guide L-5-21.

    Science.gov (United States)

    Phillips, Diane Held; Krasny, Marianne E.

    This illustrated leader's guide describes activities for teaching children to use field guides to identify trees and birds. Background information for leaders explains the two types of field guides, those that use a series of steps in what is called a key to identify things in nature, such as trees, and those that use groupings based on…

  19. Detailed measurement of the flow field in an axial transonic compressor; Mesure detaillee des ecoulements dans un compresseur axial transsonique

    Energy Technology Data Exchange (ETDEWEB)

    Fradin, C.

    1998-07-01

    The prediction of flow structure and performances of an axial transonic compressor requires accurate solvers. Taking into account the complex flow patterns, it is important to validate codes by comparing it with experimental results. It is well understood that the availability of experimental data is fundamentally important for the improvement of the solvers. An axial transonic compressor has been fitted in the ERECA test facility of ONERA. The rotor of this compressor is isolated from stators. This experimental configuration allows to obtain a steady flow into the relative frame linked to the rotor. Due to this fact, experimental tests became easier because the basic phenomena are not hidden by mutual interactions rotor-stator. Measurements have been made in a test section far upstream the rotor, to provide the inlet conditions in the computation domain. Non intrusive and fast response measurement techniques allow to obtain the detailed flow structure in several test sections located in the rotor and far downstream it. All tests were carried out at four operating conditions of the compressor. Results provide good test cases for numerical prediction methods using three-dimensional Navier-Stokes solvers. (author)

  20. Chiral extrapolation of nucleon axial charge gA in effective field theory

    Science.gov (United States)

    Li, Hong-na; Wang, P.

    2016-12-01

    The extrapolation of nucleon axial charge gA is investigated within the framework of heavy baryon chiral effective field theory. The intermediate octet and decuplet baryons are included in the one loop calculation. Finite range regularization is applied to improve the convergence in the quark-mass expansion. The lattice data from three different groups are used for the extrapolation. At physical pion mass, the extrapolated gA are all smaller than the experimental value. Supported by National Natural Science Foundation of China (11475186) and Sino-German CRC 110 (NSFC 11621131001)

  1. Distribution of Cathode Spots in Vacuum Arc Under Nonuniform Axial Magnetic Fields

    Institute of Scientific and Technical Information of China (English)

    SHI Zong-qian; JIA Shen-li; WANG Li-jun; LI Xing-wen; WANG Zheng

    2007-01-01

    Recent results on the distribution of vacuum arc cathode spots (CSs) in nonuniform axial magnetic field (AMF) are presented.Based on previous studies,we deem that two contrary influences of AMF,inward effect and outward effect,are attributed to CSs distribution.With this notion,we have analyzed the controlling effectiveness of nonuniform AMF on CSs distribution. Experiments were conducted in a detachable vacuum chamber with iron-style AMF electrodes.Images of vacuum arc column and the distribution of CSs were photographed with a high-speed charge coupled device (CCD) camera. Experimental results agreed well with the theoretical analysis.

  2. A Simple Method of FLow Field DIagnosis in Multistage Axial Flow Compressors

    Institute of Scientific and Technical Information of China (English)

    JieLiu; DajunYe

    1994-01-01

    The calculating method of flow field diagnosis in multistage axial compressors is presented in this paper.The distributions of loss and deviation angle of every blade row,and blockage factors are evalusted using tested total temperature and total pressure at inlet and outlet of compressor,as well as the endwall static pressures.One operating Mode of a two-stage fan is presented comparing results from the diagnostic method with measurements,and the results have demonstrated the important effects of diagnostic method.

  3. Growth rate enhancement of free-electron laser by two consecutive wigglers with axial magnetic field

    Indian Academy of Sciences (India)

    A Hasanbeigi; A Farhadian; E Khademi Bidhendi

    2014-06-01

    The operative mechanism for a free-electron laser (FEL) with two consecutive helical wigglers having opposite circular polarization in the presence of an axial magnetic field is proposed and analysed. With the help of fluid theory, a tenth-degree polynomial dispersion equation for electromagnetic and space-charge waves is derived. The results are used to illustrate and discuss the dependence of growth rate on different system parameters. Finally, it is shown that for the same system parameters the growth rate of the proposed structure is more than the growth rate of instability in a conventional FEL.

  4. Simulation Research of Magnetic Constriction Effect and Controlling by Axial Magnetic Field of Vacuum Arc

    Institute of Scientific and Technical Information of China (English)

    王立军; 贾申利; 史宗谦; 荣命哲

    2005-01-01

    Based on magnetohydrodynamic (MHD) model of vacuum arc, the computer simulation of vacuum arc was carried out in this paper. In the MHD model, mass conservation equation,momentum conservation equations, energy conservation equations, generalized ohm's law and Maxwell equation were considered. MHD equations were calculated by numerical method, and the distribution of vacuum arc plasma parameters and current density were obtained. Simulation results showed that the magnetic constriction effect of vacuum arc is primarily caused by the Hall effect. In addition, the inhibition of axial magnetic field (AMF) on constriction of vacuum arc was calculated and analyzed.

  5. Malware Forensics Field Guide for Windows Systems Digital Forensics Field Guides

    CERN Document Server

    Malin, Cameron H; Aquilina, James M

    2010-01-01

    Dissecting the dark side of the Internet with its infectious worms, botnets, rootkits, and Trojan horse programs (known as malware) is a treaterous condition for any forensic investigator or analyst. Written by information security experts with real-world investigative experience, Malware Forensics Field Guide for Windows Systems is a "tool" with checklists for specific tasks, case studies of difficult situations, and expert analyst tips. *A condensed hand-held guide complete with on-the-job tasks and checklists *Specific for Windows-based systems, the largest running OS in the world

  6. Kr II and Xe II axial velocity distribution functions in a cross-field ion source

    Science.gov (United States)

    Lejeune, A.; Bourgeois, G.; Mazouffre, S.

    2012-07-01

    Laser induced fluorescence measurements were carried out in a cross-field ion source to examine the behaviour of the axial ion velocity distribution functions (VDFs) in the expanding plasma. In the present paper, we focus on the axial VDFs of Kr II and Xe II ions. We examine the contourplots in a 1D-phase space (x,vx) representation in front of the exhaust channel and along the centerline of the ion source. The main ion beam, whose momentum corresponds to the ions that are accelerated through the whole potential drop, is observed. A secondary structure reveals the ions coming from the opposite side of the channel. We show that the formation of the neutralized ion flow is governed by the annular geometry. The assumption of a collisionless shock or a double layer due to supersonic beam interaction is not necessary. A non-negligible fraction of slow ions originates in local ionization or charge-exchange collision events between ions of the expanding plasma and atoms of the background residual gas. Slow ions that are produced near the centerline in the vicinity of the exit plane are accelerated toward the source body with a negative velocity leading to a high sputtering of front face. On the contrary, the ions that are produced in the vicinity of the channel exit plane are partially accelerated by the extended electric field.

  7. High-rate axial-field ionization chamber for particle identification of Radioactive beams

    Science.gov (United States)

    Desouza, Romualdo; Vadas, Justin; Singh, Varinderjit; Visser, G.; Alexander, A.; Hudan, S.; Huston, J.; Wiggins, B.; Chbihi, A.; Famiano, M.; Bischak, M.

    2017-01-01

    The design, construction and performance characteristics of a simple axial-field ionization chamber suitable for identifying ions in a radioactive beam are presented. The detector is optimized for use with low-energy radioactive beams (<) 5 MeV/A. A fast charge sensitive amplifier (CSA) integrated into the detector design is also described. Coupling this fast CSA to the axial field ionization chamber produces an output pulse with a rise-time of 60 to 70 ns and a fall time of 100 ns, making the detector capable of sustaining a relatively high rate while providing a time resolution of 6 to 8 ns. Tests with an α source establish the detector energy resolution as 8 % for an energy deposit of 3.5 MeV. Beam tests indicate that the detector is an effective tool for the characterization of low-energy radioactive beams at beam intensities up to 3 x 105 ions/s. Supported by the U.S. DOE under Award # DE-FG02-88ER-40404 and the NSF under Grant No. 1342962.

  8. High-rate axial-field ionization chamber for particle identification of radioactive beams

    CERN Document Server

    Vadas, J; Visser, G; Alexander, A; Hudan, S; Huston, J; Wiggins, B B; Chbihi, A; Famiano, M; Bischak, M M; deSouza, R T

    2016-01-01

    The design, construction and performance characteristics of a simple axial-field ionization chamber suitable for identifying ions in a radioactive beam are presented. Optimized for use with low-energy radioactive beams (< 5 MeV/A) the detector presents only three 0.5 $\\mu$m/cm$^2$ foils to the beam in addition to the detector gas. A fast charge sensitive amplifier (CSA) integrated into the detector design is also described. Coupling this fast CSA to the axial field ionization chamber produces an output pulse with a risetime of 60-70 ns and a fall time of 100 ns, making the detector capable of sustaining a relatively high rate. Tests with an $\\alpha$ source establish the detector energy resolution as $\\sim$8 $\\%$ for an energy deposit of $\\sim$3.5 MeV. The energy resolution with beams of 2.5 and 4.0 MeV/A $^{39}$K ions and the dependence of the energy resolution on beam intensity is measured. At an instantaneous rate of 3 x 10$^5$ ions/s the energy resolution has degraded to 14% with a pileup of 12%. The go...

  9. On the equivalence of approximate stationary axially symmetric solutions of Einstein field equations

    CERN Document Server

    Boshkayev, Kuantay; Toktarbay, Saken; Zhami, Bakytzhan

    2015-01-01

    We study stationary axially symmetric solutions of the Einstein vacuum field equations that can be used to describe the gravitational field of astrophysical compact objects in the limiting case of slow rotation and slight deformation. We derive explicitly the exterior Sedrakyan-Chubaryan approximate solution, and express it in analytical form, which makes it practical in the context of astrophysical applications. In the limiting case of vanishing angular momentum, the solution reduces to the well-known Schwarzschild solution in vacuum. We demonstrate that the new solution is equivalent to the exterior Hartle-Thorne solution. We establish the mathematical equivalence between the Sedrakyan-Chubaryan, Fock-Abdildin and Hartle-Thorne formalisms.

  10. On the equivalence of approximate stationary axially symmetric solutions of the Einstein field equations

    Science.gov (United States)

    Boshkayev, Kuantay; Quevedo, Hernando; Toktarbay, Saken; Zhami, Bakytzhan; Abishev, Medeu

    2016-10-01

    We study stationary axially symmetric solutions of the Einstein vacuum field equations that can be used to describe the gravitational field of astrophysical compact objects in the limiting case of slow rotation and slight deformation. We derive explicitly the exterior Sedrakyan-Chubaryan approximate solution, and express it in analytical form, which makes it practical in the context of astrophysical applications. In the limiting case of vanishing angular momentum, the solution reduces to the well-known Schwarzschild solution in vacuum. We demonstrate that the new solution is equivalent to the exterior Hartle-Thorne solution. We establish the mathematical equivalence between the Sedrakyan-Chubaryan, Fock-Abdildin and Hartle-Thorne formalisms.

  11. Optimization of the recovery efficiency in an axial HGMF cell with bounded flow field

    Science.gov (United States)

    Badescu, V.; Murariu, V.; Rotariu, O.; Rezlescu, N.

    1996-09-01

    This work presents a method to optimize the recovery efficiency of fine paramagnetic particles from a liquid suspension in an axial HGMF cell. The cell has the flow field bounded by a circular cylindrical wall. It has only one ferromagnetic wire mounted outside the flow field, parallel with its axis and in `paramagnetic capture mode'. The optimization criterion was deduced from the analysis of the particles' trajectories inside the magnetic active space. It is based on the relationship between the geometrical 0022-3727/29/9/042/img1 and operational 0022-3727/29/9/042/img2 parameters for which the filtration efficiency is 100%. The work also presents some experimental data which are in good agreement with theoretical results.

  12. Electron states in quantum rings with structural distortions under axial or in-plane magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Planelles, J [Departament de Quimica Fisica i Analitica, Universitat Jaume I, Box 224, E-12080 Castello (Spain); Rajadell, F [Departament de Quimica Fisica i Analitica, Universitat Jaume I, Box 224, E-12080 Castello (Spain); Climente, J I [Departament de Quimica Fisica i Analitica, Universitat Jaume I, Box 224, E-12080 Castello (Spain)

    2007-09-19

    A comprehensive study of anisotropic quantum rings, QRs, subject to axial and in-plane magnetic field, both aligned and transverse to the anisotropy direction, is carried out. Elliptical QRs for a wide range of eccentricity values and also perfectly circular QRs including one or more barriers disturbing the QR current are considered. These models mimic anisotropic geometry deformations and mass diffusion occurring in the QR fabrication process. Symmetry considerations and simplified analytical models supply physical insight into the obtained numerical results. Our study demonstrates that, except for unusual extremely large eccentricities, QR geometry deformations only appreciably influence a few low-lying states, while the effect of barriers disturbing the QR current is stronger and affects all studied states to a similar extent. We also show that the response of the electron states to in-plane magnetic fields provides accurate information on the structural anisotropy.

  13. Advanced axial field D.C. motor development for electric passenger vehicle

    Science.gov (United States)

    Jones, W. J.

    1982-01-01

    A wound-field axial-flux dc motor was developed for an electric vehicle drive system. The motor is essentially an axial-flux version of the classical Gramme-ring winding motor, but the active conductors are recessed into slots cut into the two opposite faces of the laminated tape-wound core ring. Three motors were built and tested in the program. The second (functional) model was a six-pole machine which weighed 88.5 kg. It developed 16.9 km (33.0 hp), and a max speed of 4800 rpm. Full load efficiency was 92% and predicted SAE D-cycle efficiency was 88%. The last engineering) model was a 4-pole machine with compoles, allowing a weight reduction to 45 kg (100 lbs.) while addressing some manufacturability problems. The engineering model was rated at 13.2 kw (17.6 hp) at 3000 rpm, with a peak power of 19.8 km (26.4 hp) and a max speed of 7200 rpm. Initial test results on this motor showed poor commutation and efficiency; the program was terminated without resolution of these problems.

  14. Experimental Investigation of the Flow Field in a Multistage Axial Flow Compressor

    Directory of Open Access Journals (Sweden)

    B. Lakshminarayana

    1996-01-01

    Full Text Available The nature of the flow field in a three stage axial flow compressor, including a detailed survey at the exit of an embedded stator as well as the overall performance of the compressor is presented and interpreted in this paper. The measurements include area traverse of a miniature five hole probe (1.07 mm dia downstream of stator 2, radial traverses of a miniature five hole probe at the inlet, downstream of stator 3 and at the exit of the compressor at various circumferential locations, area traverse of a low response thermocouple probe downstream of stator 2, radial traverses of a single sensor hot-wire probe at the inlet, and casing static pressure measurements at various circumferential and axial locations across the compressor at the peak efficiency operating point. Mean velocity, pressure and total temperature contours as well as secondary flow contours at the exit of the stator 2 are reported and interpreted. Secondary flow contours show the migration of fluid particles toward the core of the low pressure regions located near the suction side casing endwall corner.

  15. Dynamics of liquid metal droplets and jets influenced by a strong axial magnetic field

    Science.gov (United States)

    Hernández, D.; Karcher, Ch

    2017-07-01

    Non-contact electromagnetic control and shaping of liquid metal free surfaces is crucial in a number of high-temperature metallurgical processes like levitation melting and electromagnetic sealing, among others. Other examples are the electromagnetic bending or stabilization of liquid metal jets that frequently occur in casting or fusion applications. Within this context, we experimentally study the influence of strong axial magnetic fields on the dynamics of falling metal droplets and liquid metal jets. GaInSn in eutectic composition is used as test melt being liquid at room temperature. In the experiments, we use a cryogen-free superconducting magnet (CFM) providing steady homogeneous fields of up to 5 T and allowing a tilt angle between the falling melt and the magnet axis. We vary the magnetic flux density, the tilt angle, the liquid metal flow rate, and the diameter and material of the nozzle (electrically conducting/insulating). Hence, the experiments cover a parameter range of Hartmann numbers Ha, Reynolds numbers Re, and Weber numbers We within 0 magnetic field, droplet rotation ceases and the droplets are stretched in the field direction. Moreover, we observe that the jet breakup into droplets (spheroidization) is suppressed, and in the case of electrically conducting nozzles and tilt, the jets are bent towards the field axis.

  16. Heat transfer and performance characteristics of axial cooling fans with downstream guide vanes

    Science.gov (United States)

    Terzis, Alexandros; Stylianou, Ioannis; Kalfas, Anestis I.; Ott, Peter

    2012-04-01

    This study examines experimentally the effect of stators on the performance and heat transfer characteristics of small axial cooling fans. A single fan impeller, followed by nine stator blades in the case of a complete stage, was used for all the experimental configurations. Performance measurements were carried out in a constant speed stage performance test rig while the transient liquid crystal technique was used for the heat transfer measurements. Full surface heat transfer coefficient distributions were obtained by recording the temperature history of liquid crystals on a target plate. The experimental data indicated that the results are highly affected by the flow conditions at the fan outlet. Stators can be beneficial in terms of pressure drop and efficiency, and thus more economical operation, as well as, in the local heat transfer distribution at the wake of the stator blades if the fan is installed very close to the cooling object. However, as the separation distance increases, enhanced heat transfer rate in the order of 25% is observed in the case of the fan impeller.

  17. Non-Abelian fields in AdS$_4$ spacetime: axially symmetric, composite configurations

    CERN Document Server

    Kichakova, Olga; Radu, Eugen; Shnir, Yasha

    2014-01-01

    We construct new finite energy regular solutions in Einstein-Yang-Mills-SU(2) theory. They are static, axially symmetric and approach at infinity the anti-de Sitter spacetime background. These configurations are characterized by a pair of integers $(m, n)$, where $m$ is related to the polar angle and $n$ to the azimuthal angle, being related to the known flat space monopole-antimonopole chains and vortex rings. Generically, they describe composite configurations with several individual components, possesing a nonzero magnetic charge, even in the absence of a Higgs field. Such Yang-Mills configurations exist already in the probe limit, the AdS geometry supplying the attractive force needed to balance the repulsive force of Yang-Mills gauge interactions. The gravitating solutions are constructed by numerically solving the elliptic Einstein-DeTurck--Yang-Mills equations. The variation of the gravitational coupling constant $\\alpha$ reveals the existence of two branches of gravitating solutions which bifurcate at...

  18. The Axial Double Probe and Fields Signal Processing for the MMS Mission

    Science.gov (United States)

    Ergun, R. E.; Tucker, S.; Westfall, J.; Goodrich, K. A.; Malaspina, D. M.; Summers, D.; Wallace, J.; Karlsson, M.; Mack, J.; Brennan, N.; Pyke, B.; Withnell, P.; Torbert, R.; Macri, J.; Rau, D.; Dors, I.; Needell, J.; Lindqvist, P.-A.; Olsson, G.; Cully, C. M.

    2016-03-01

    The Axial Double Probe (ADP) instrument measures the DC to ˜100 kHz electric field along the spin axis of the Magnetospheric Multiscale (MMS) spacecraft (Burch et al., Space Sci. Rev., 2014, this issue), completing the vector electric field when combined with the spin plane double probes (SDP) (Torbert et al., Space Sci. Rev., 2014, this issue, Lindqvist et al., Space Sci. Rev., 2014, this issue). Two cylindrical sensors are separated by over 30 m tip-to-tip, the longest baseline on an axial DC electric field ever attempted in space. The ADP on each of the spacecraft consists of two identical, 12.67 m graphite coilable booms with second, smaller 2.25 m booms mounted on their ends. A significant effort was carried out to assure that the potential field of the MMS spacecraft acts equally on the two sensors and that photo- and secondary electron currents do not vary over the spacecraft spin. The ADP on MMS is expected to measure DC electric field with a precision of ˜1 mV/m, a resolution of ˜25 μV/m, and a range of ˜±1 V/m in most of the plasma environments MMS will encounter. The Digital Signal Processing (DSP) units on the MMS spacecraft are designed to perform analog conditioning, analog-to-digital (A/D) conversion, and digital processing on the ADP, SDP, and search coil magnetometer (SCM) (Le Contel et al., Space Sci. Rev., 2014, this issue) signals. The DSP units include digital filters, spectral processing, a high-speed burst memory, a solitary structure detector, and data compression. The DSP uses precision analog processing with, in most cases, >100 dB in dynamic range, better that -80 dB common mode rejection in electric field ( E) signal processing, and better that -80 dB cross talk between the E and SCM ( B) signals. The A/D conversion is at 16 bits with ˜1/4 LSB accuracy and ˜1 LSB noise. The digital signal processing is powerful and highly flexible allowing for maximum scientific return under a limited telemetry volume. The ADP and DSP are

  19. Field guide to diseases & insects of the Rocky Mountain Region

    Science.gov (United States)

    Forest Health Protection. Rocky Mountain Region

    2010-01-01

    This field guide is a forest management tool for field identification of biotic and abiotic agents that damage native trees in Colorado, Kansas, Nebraska, South Dakota, and Wyoming, which constitute the USDA Forest Service's Rocky Mountain Region. The guide focuses only on tree diseases and forest insects that have significant economic, ecological, and/ or...

  20. Axial anomaly effects in finite isospin $\\chi$PT in a magnetic field

    CERN Document Server

    Adhikari, Prabal

    2015-01-01

    In this paper, we consider finite isospin chiral perturbation theory including the effects of the axial anomaly (through the Wess-Zumino-Witten term) in a strong magnetic field. We firstly prove that in a strong external magnetic field ($H_{\\rm ext}$) or more precisely the Schwinger limit, where photon back-reactions are suppressed, only neutral pions can condense and the condensation of charged pions is forbidden. Secondly, we find that the $\\pi^{0}$ domain wall is an example of a phase that can exist in a strong magnetic field and suggest the existence of a new phase transition line from the normal vacuum state to the $\\pi^{0}$ domain wall state. This phase transition exists for non-zero pion masses if the baryon chemical potential exceeds a critical value $16\\pi f_{\\pi}^{2}m_{\\pi}/eH_{\\rm ext}$. The phase transition line persists away from the Schwinger limit when the photons can back-react to the external magnetic field.

  1. Study of Magnetic Field Behavior at Lower Pressure of Neon in the Axial Phase of INTI Plasma Focus

    Directory of Open Access Journals (Sweden)

    K.K.A. Devi

    2014-03-01

    Full Text Available The magnetic field distribution substantially affects mechanisms for the generation of radiation in Z-pinches. Investigation of the axial component of the magnetic field is one of the important problems in plasma focus studies. The designed magnetic probe is intended to use for the study of current sheet in INTI plasma focus device with energy of about 3.3 kJ. The measurements of the azimuthal component of the magnetic field on the INTI Plasma Focus operated at neon pressures below 1 Torr was carried out using a custom built calibrated magnetic probe. The probe was tested for neon gas under the various lower pressures (i.e., 0.1, 0.3, 0.5 and 0.7, 1, 2, 3, 5 torr etc.. It is observed that the time response of the designed probe is sufficient for the rise time of the magnetic field associated with the current in the axial phase. We also note that the small size of the designed probe is well suited to sense the magnetic field without perturbing the plasma unduly. The probe designed and constructed is also suitable to carryout measurements to obtain axial distributions of trajectory, average axial velocity and magnetic field of the current sheath at a certain radial distances along the axis of the tube.

  2. Flow Fields with Vortex in a Small Semi-open Axial Fan

    Institute of Scientific and Technical Information of China (English)

    Norimasa. Shiomi; Yoichi Kinoue; Ying zi Jin; Toshiaki Setoguchi; Kenji Kaneko

    2009-01-01

    In order to clarify the effect of tip clearance (TC) size on fan performance and the flow field at rotor outlet in a small semi-open axial fan, the experimental investigation was carried out. The tip diameter of test fan rotor was 180mm and test TC sizes were 1 mm (TC=1 mm) and 4mm (TC=4mm). Fan characteristics tests were carried out for two cases of TC size and three-dimensional velocity fields at rotor outlet were measured using a single slant hot-wire probe at four flow-rate conditions. As a result, it was found that the pressure -flow-rate characteristics curves for two cases showed almost the same tendency. However, the ensemble averaged velocity profiles along radial measurement stations of TC=4mm largely changed compared with that of TC=1mm in cases of small flow-rate condition. From the phase-locked averaging results, it was also found that the vortex existed in the rotor outlet flow field of high flow-rate condition for each TC case. Compared with the vortices for TC=1mm and TC=4mm, the vortex for TC=4mm was stronger than that for TC=1mm.

  3. Axial Myopia Is Associated with Visual Field Prognosis of Primary Open-Angle Glaucoma.

    Directory of Open Access Journals (Sweden)

    Chen Qiu

    Full Text Available To identify whether myopia was associated with the visual field (VF progression of primary open-angle glaucoma (POAG.A total of 270 eyes of 270 POAG followed up for more than 3 years with ≥9 reliable VFs by Octopus perimetry were retrospectively reviewed. Myopia was divided into: mild myopia (-2.99 diopter [D], 0, moderate myopia (-5.99, 3.00 D, marked myopia (-9.00, -6.00 D and non-myopia (0 D or more. An annual change in the mean defect (MD slope >0.22 dB/y and 0.30 dB/y was defined as fast progression, respectively. Logistic regression was performed to determine prognostic factors for VF progression.For the cutoff threshold at 0.22 dB/y, logistic regression showed that vertical cup-to-disk ratio (VCDR; p = 0.004 and the extent of myopia (p = 0.002 were statistically significant. When logistic regression was repeated after excluding the extent of myopia, axial length (AL; p = 0.008, odds ratio [OR] = 0.796 reached significance, as did VCDR (p = 0.001. Compared to eyes with AL≤23 mm, the OR values were 0.334 (p = 0.059, 0.309 (p = 0.044, 0.266 (p = 0.019, 0.260 (p = 0.018, respectively, for 23 26 mm. The significance of vertical cup-to-disk ratio of (p = 0.004 and the extent of myopia (p = 0.008 did not change for the cutoff threshold at 0.30dB/y.VCDR and myopia were associated with VF prognosis of POAG. Axial myopia may be a protective factor against VF progression.

  4. Striations in CZ silicon crystals grown under various axial magnetic field strengths

    Science.gov (United States)

    Kim, K. M.; Smetana, P.

    1985-10-01

    Inhibition of fluid flow instabilities in the melt by the axial magnetic field in Czochralski silicon crystal growth (AMCZ) is investigated precisely by a high-sensitivity striation etch in conjunction with temperature measurements. The magnetic field strength (B) was varied up to 4.0 kG, incremented mostly in 0.5-kG/2.5-cm crystal length. The convection flow was substantially suppressed at B greater than or equal to 1.0 kG. A low oxygen level of 2-3 ppm and a high resistivity of 400 ohm-cm is achieved in the AMCZ silicon crystals at B greater than or equal to 1.0 kG. Random striations at B = O, characteristic of turbulent convection, assumed progressively a periodicity, indicative of oscillatory convection at B from 0.35-4.0 kG. The striation contrast or 'intensity' decreased steadily with the increase in B. At B = 4 kG, most of the crystal was free of striations, although some weak, localized periodic striations persisted near the crystal periphery. Spreading-resistance measurement shows, however, a uniform dopant distribution in all crystal sections grown at B from 0.35-4.0 kG within a few percent.

  5. Intermittency in Hall-magnetohydrodynamics with a strong guide field

    CERN Document Server

    Imazio, P Rodriguez; Dmitruk, P; Mininni, P D

    2013-01-01

    We present a detailed study of intermittency in the velocity and magnetic field fluctuations of compressible Hall-magnetohydrodynamic turbulence with an external guide field. To solve the equations numerically, a reduced model valid when a strong guide field is present is used. Different values for the ion skin depth are considered in the simulations. The resulting data is analyzed computing field increments in several directions perpendicular to the guide field, and building structure functions and probability density functions. In the magnetohydrodynamic limit we recover the usual results with the magnetic field being more intermittent than the velocity field. In the presence of the Hall effect, field fluctuations at scales smaller than the ion skin depth show a substantial decrease in the level of intermittency, with close to monofractal scaling.

  6. Magnetic Field Analysis of Plasma Guide in Galathea Trimyx

    Directory of Open Access Journals (Sweden)

    Jin Xianji

    2016-01-01

    Full Text Available You Galathea Trimyx is a kind of small size, multipole magnetic confinement devices in controlled thermonuclear fusion. Plasma guide is one of important part in Galathea Trimyx which is responsible for transporting fast and slow plasma bunches ejected from plasma gun. The distribution and uniformity of magnetic field in completed plasma guide is analyzed in detail, including in x -axis direction and in z-axis direction. On the basis, the motion of plasma in the guide is discussed.

  7. Vacuum effects in magnetic field with with account for fermion anomalous magnetic moment and axial-vector interaction

    Science.gov (United States)

    Bubnov, Andrey; Gubina, Nadezda; Zhukovsky, Vladimir

    2016-05-01

    We study vacuum polarization effects in the model of Dirac fermions with additional interaction of an anomalous magnetic moment with an external magnetic field and fermion interaction with an axial-vector condensate. The proper time method is used to calculate the one-loop vacuum corrections with consideration for different configurations of the characteristic parameters of these interactions.

  8. Enhanced Axial Resolution of Wide-Field Two-Photon Excitation Microscopy by Line Scanning Using a Digital Micromirror Device

    Directory of Open Access Journals (Sweden)

    Jong Kang Park

    2017-03-01

    Full Text Available Temporal focusing multiphoton microscopy is a technique for performing highly parallelized multiphoton microscopy while still maintaining depth discrimination. While the conventional wide-field configuration for temporal focusing suffers from sub-optimal axial resolution, line scanning temporal focusing, implemented here using a digital micromirror device (DMD, can provide substantial improvement. The DMD-based line scanning temporal focusing technique dynamically trades off the degree of parallelization, and hence imaging speed, for axial resolution, allowing performance parameters to be adapted to the experimental requirements. We demonstrate this new instrument in calibration specimens and in biological specimens, including a mouse kidney slice.

  9. Effect of Guiding Magnetic Field on Weibel Instability

    Institute of Scientific and Technical Information of China (English)

    LI Ji-Wei; PEI Wen-Bing

    2005-01-01

    @@ We derive a linear dispersion relation in the presence of a constant uniform guiding magnetic field parallel to the beam velocity direction, which shows a strong background magnetic field suppresses or even stabilizes the Weibel instability produced by two counter streams in electron-ion plasmas. The simulation results are in good agreement with the analytical ones. Also observed in the simulations are the suppression of electrostatic field, a higher level of saturation of self-generated magnetic field, and the apparent difference in phase space compared with those in the absence of guiding magnetic field.

  10. Calculation of the zero-field splitting D and g(perp)parameters in EPR for d3 spin systems in strong and moderate axial fields

    NARCIS (Netherlands)

    Kool, Th.W.; Bollegraaf, B.

    2010-01-01

    Numerical and analytical methods are used to investigate the calculation of the zero field splitting |2D| and g(perp) parameters in EPR for octahedrally surrounded d3 spin systems (S = 3/2) in strong and moderate axial crystal fields (|D|>=h{\

  11. Healthy Water Healthy People Field Monitoring Guide

    Science.gov (United States)

    Project WET Foundation, 2003

    2003-01-01

    This 100-page manual serves as a technical reference for the "Healthy Water, Healthy People Water Quality Educators Guide" and the "Healthy Water Healthy People Testing Kits". Yielding in-depth information about ten water quality parameters, it answers questions about water quality testing using technical overviews, data interpretation guidelines,…

  12. Value Added School Review Field Guide

    Science.gov (United States)

    Alberta Education, 2009

    2009-01-01

    The "Value-Added School Review (VSR)" is an analytical model designed to assist schools in identifying and addressing opportunities for school improvement. The model works best when it is focused purposefully on students and the student learning outcomes as defined in the "Guide to Education". It complements the processes…

  13. 76 FR 9039 - Emergency Responder Field Operations Guide

    Science.gov (United States)

    2011-02-16

    ... Incident Management System Incident Command System during incident operations. DATES: Comments must be...., and Homeland Security Presidential Directive (HSPD) 5--Management of Domestic Incidents. Dated... SECURITY Federal Emergency Management Agency Emergency Responder Field Operations Guide AGENCY: Federal...

  14. Field guide to fishes of the chesapeake bay

    CERN Document Server

    Murdy, Edward O.

    2013-01-01

    The only comprehensive field guide to the Chesapeake’s fishes, this book is an indispensable resource for both anglers and students of the Bay. Vivid illustrations by Val Kells complement the expertise of researchers Edward O. Murdy and John A. Musick. They describe fishes that inhabit waters ranging from low-salinity estuaries to the point where the Bay meets the Atlantic Ocean. Key features of this field guide include• full-color illustrations of more than 200 species• text that is presented adjacent to illustrations for easy reference• detailed descriptions of physical characteristics, range, occurrence in the Bay, reproduction, diet, and statistics from fisheries research• spot illustrations that highlight critical features of certain fish• illustrations of juveniles when they look different from adults• appendices that include identification keys Formatted as a compact field guide for students, scientists, researchers, and fishermen, Field Guide to Fishes of the Chesapeake Bay should be a ...

  15. Two-dimensional model of the Penning discharge in a cylindrical chamber with the axial magnetic field

    Science.gov (United States)

    Surzhikov, S. T.

    2017-08-01

    The drift-diffusion model of a Penning discharge in molecular hydrogen under pressures of about 1 Torr with regard to the external electric circuit has been proposed. A two-dimensional axially symmetric discharge geometry with a cylindrical anode and flat cathodes perpendicular to the symmetry axis has been investigated. An external magnetic field of about 0.1 T is applied in the axial direction. Using the developed drift-diffusion model, the electrodynamic structure of a Penning discharge in the pressure range of 0.5-5 Torr at a current source voltage of 200-500 V is numerically simulated. The evolution of the discharge electrodynamic structure upon pressure variations in zero magnetic field (the classical glow discharge mode) and in the axial magnetic field (Penning discharge) has been studied using numerical experiments. The theoretical predictions of the existence of an averaged electron and ion motion in a Penning discharge both in the axial and radial directions and in the azimuthal direction have been confirmed by the calculations.

  16. Solving outside-axial-field-of-view scatter correction problem in PET via digital experimentation

    Science.gov (United States)

    Andreyev, Andriy; Zhu, Yang-Ming; Ye, Jinghan; Song, Xiyun; Hu, Zhiqiang

    2016-03-01

    Unaccounted scatter impact from unknown outside-axial-field-of-view (outside-AFOV) activity in PET is an important degrading factor for image quality and quantitation. Resource consuming and unpopular way to account for the outside- AFOV activity is to perform an additional PET/CT scan of adjacent regions. In this work we investigate a solution to the outside-AFOV scatter problem without performing a PET/CT scan of the adjacent regions. The main motivation for the proposed method is that the measured random corrected prompt (RCP) sinogram in the background region surrounding the measured object contains only scattered events, originating from both inside- and outside-AFOV activity. In this method, the scatter correction simulation searches through many randomly-chosen outside-AFOV activity estimates along with known inside-AFOV activity, generating a plethora of scatter distribution sinograms. This digital experimentation iterates until a decent match is found between a simulated scatter sinogram (that include supposed outside-AFOV activity) and the measured RCP sinogram in the background region. The combined scatter impact from inside- and outside-AFOV activity can then be used for scatter correction during final image reconstruction phase. Preliminary results using measured phantom data indicate successful phantom length estimate with the method, and, therefore, accurate outside-AFOV scatter estimate.

  17. Topological approach to examine the singularity of the axial-vector current in an Abelian gauge field theory (QED)

    Institute of Scientific and Technical Information of China (English)

    BAO Ai-Dong; YAO Hai-Bo; WU Shi-Shu

    2009-01-01

    A topological way to distinguish divergences of the Abelian axial-vector current in quantum field theory is proposed. By usirg the properties of the Atiyah-Singer index theorem, the non-trivial Jacobian factor of the integration measure in the path-integral formulation of the theory is connected with the topological properties of the gauge field. The singularity of the fermion current related to the topological character can be correctly examined in a gauge background.

  18. Observing the sun a pocket field guide

    CERN Document Server

    Jenkins, Jamey L

    2013-01-01

    A comprehensive solar observing guide for use at the telescope by amateur astronomers at all three levels: beginning, intermediate, and advanced. Users will find invaluable information for identifying features through photos, charts, diagrams in a logical, orderly fashion and then interpreting the observations. Because the Sun is a dynamic celestial body in constant flux, astronomers rarely know for certain what awaits them at the eyepiece. All features of the Sun are transient and sometimes rather fleeting. Given the number of features and the complex life cycles of some solar features, it can be a challenging hobby, and this guide provides all of the guidance necessary to inform observers about the sights and events unfolding before their eyes on the most active and powerful member of our Solar System.

  19. Nonlocal vibration of axially moving graphene sheet resting on orthotropic visco-Pasternak foundation under longitudinal magnetic field

    Science.gov (United States)

    Arani, A. Ghorbanpour; Haghparast, E.; BabaAkbar Zarei, H.

    2016-08-01

    In the present research, vibration and instability of axially moving single-layered graphene sheet (SLGS) subjected to magnetic field is investigated. Orthotropic visco-Pasternak foundation is developed to consider the influences of orthotropy angle, damping coefficient, normal and shear modulus. Third order shear deformation theory (TSDT) is utilized due to its accuracy of polynomial functions than other plate theories. Motion equations are obtained by means of Hamilton's principle and solved analytically. Influences of various parameters such as axially moving speed, magnetic field, orthotropic viscoelastic surrounding medium, thickness and aspect ratio of SLGS on the vibration characteristics of moving system are discussed in details. The results indicated that the critical speed of moving SLGS is strongly dependent on the moving speed. Therefore, the critical speed of moving SLGS can be improved by applying magnetic field. The results of this investigation can be used in design and manufacturing of marine vessels in nanoscale.

  20. Nonlocal vibration of axially moving graphene sheet resting on orthotropic visco-Pasternak foundation under longitudinal magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Arani, A. Ghorbanpour, E-mail: aghorban@kashanu.ac.ir [Faculty of Mechanical Engineering University of Kashan, Kashan (Iran, Islamic Republic of); Institute of Nanoscience & Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Haghparast, E.; BabaAkbar Zarei, H. [Faculty of Mechanical Engineering University of Kashan, Kashan (Iran, Islamic Republic of)

    2016-08-15

    In the present research, vibration and instability of axially moving single-layered graphene sheet (SLGS) subjected to magnetic field is investigated. Orthotropic visco-Pasternak foundation is developed to consider the influences of orthotropy angle, damping coefficient, normal and shear modulus. Third order shear deformation theory (TSDT) is utilized due to its accuracy of polynomial functions than other plate theories. Motion equations are obtained by means of Hamilton’s principle and solved analytically. Influences of various parameters such as axially moving speed, magnetic field, orthotropic viscoelastic surrounding medium, thickness and aspect ratio of SLGS on the vibration characteristics of moving system are discussed in details. The results indicated that the critical speed of moving SLGS is strongly dependent on the moving speed. Therefore, the critical speed of moving SLGS can be improved by applying magnetic field. The results of this investigation can be used in design and manufacturing of marine vessels in nanoscale.

  1. Electric-field guiding of magnetic skyrmions

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyaya, Pramey; Yu, Guoqiang; Amiri, Pedram Khalili; Wang, Kang L.

    2015-10-01

    We theoretically study equilibrium and dynamic properties of nanosized magnetic skyrmions in thin magnetic films with broken inversion symmetry, where an electric field couples to magnetization via spin-orbit coupling. Based on a symmetry-based phenomenology and micromagnetic simulations we show that this electric-field coupling, via renormalizing the micromagnetic energy, modifies the equilibrium properties of the skyrmion. This change, in turn, results in a significant alteration of the current-induced skyrmion motion. Particularly, the speed and direction of the skyrmion can be manipulated by designing a desired energy landscape electrically, which we describe within Thiele's analytical model and demonstrate in micromagnetic simulations including electric-field-controlled magnetic anisotropy. We additionally use this electric-field control to construct gates for controlling skyrmion motion exhibiting a transistorlike and multiplexerlike function. The proposed electric-field effect can thus provide a low-energy electrical knob to extend the reach of information processing with skyrmions.

  2. Axially uniform magnetic field-modulation excitation for electron paramagnetic resonance in rectangular and cylindrical cavities by slot cutting

    Science.gov (United States)

    Sidabras, Jason W.; Richie, James E.; Hyde, James S.

    2017-01-01

    In continuous-wave (CW) Electron Paramagnetic Resonance (EPR) a low-frequency time-harmonic magnetic field, called field modulation, is applied parallel to the static magnetic field and incident on the sample. Varying amplitude of the field modulation incident on the sample has consequences on spectral line-shape and line-height over the axis of the sample. Here we present a method of coupling magnetic field into the cavity using slots perpendicular to the sample axis where the slot depths are designed in such a way to produce an axially uniform magnetic field along the sample. Previous literature typically assumes a uniform cross-section and axial excitation due to the wavelength of the field modulation being much larger than the cavity. Through numerical analysis and insights obtained from the eigenfunction expansion of dyadic Green's functions, it is shown that evanescent standing-wave modes with complex cross-sections are formed within the cavity. From this analysis, a W-band (94 GHz) cylindrical cavity is designed where modulation slots are optimized to present a uniform 100 kHz field modulation over the length of the sample.

  3. Effects of slot closure by soft magnetic powder wedge material in axial-field permanent magnet brushless machines

    Science.gov (United States)

    Gair, S.; Eastham, J. F.; Canova, A.

    1996-04-01

    The article reports on a study of the effects of slot closure in axial-field permanent magnet brushless machines by a two-dimensional finite element method (2D FEM) of analysis. The closure of the slots is made by using soft magnetic powder wedge material. Parameter values and machine performance for the open and closed slot configuration are computed. In order to test the 2D FEM model, calculated results are compared with measurements and favorable agreement is shown.

  4. Investigation of Blade-row Flow Distributions in Axial-flow-compressor Stage Consisting of Guide Vanes and Rotor-blade Row

    Science.gov (United States)

    Mahoney, John J; Dugan, Paul D; Budinger, Raymond E; Goelzer, H Fred

    1950-01-01

    A 30-inch tip-diameter axial-flow compressor stage was investigated with and without rotor to determine individual blade-row performance, interblade-row effects, and outer-wall boundary-layer conditions. Velocity gradients at guide-vane outlet without rotor approximated design assumptions, when the measured variation of leaving angle was considered. With rotor in operation, Mach number and rotor-blade effects changed flow distribution leaving guide vanes and invalidated design assumption of radial equilibrium. Rotor-blade performance correlated interpolated two-dimensional results within 2 degrees, although tip stall was indicated in experimental and not two-dimensional results. Boundary-displacement thickness was less than 1.0 and 1.5 percent of passage height after guide vanes and after rotor, respectively, but increased rapidly after rotor when tip stall occurred.

  5. Field Guide to Meteors and Meteorites

    CERN Document Server

    Norton, O. Richard

    2008-01-01

    Imagine the unique experience of being the very first person to hold a newly-found meteorite in your hand – a rock from space, older than Earth! "Weekend meteorite hunting" with magnets and metal detectors is becoming ever more popular as a pastime, but of course you can’t just walk around and pick up meteorites in the same way that you can pick up seashells on the beach. Those fragments that survived the intense heat of re-entry tend to disguise themselves as natural rocks over time, and it takes a trained eye – along with the information in this book – to recognize them. Just as amateur astronomers are familiar with the telescopes and accessories needed to study a celestial object, amateur meteoriticists have to use equipment ranging from simple hand lenses to microscopes to study a specimen, to identify its type and origins. Equipment and techniques are covered in detail here of course, along with a complete and fully illustrated guide to what you might find and where you might find it. In fact, th...

  6. The wireshark field guide analyzing and troubleshooting network traffic

    CERN Document Server

    Shimonski, Robert

    2013-01-01

    The Wireshark Field Guide provides hackers, pen testers, and network administrators with practical guidance on capturing and interactively browsing computer network traffic. Wireshark is the world's foremost network protocol analyzer, with a rich feature set that includes deep inspection of hundreds of protocols, live capture, offline analysis and many other features. The Wireshark Field Guide covers the installation, configuration and use of this powerful multi-platform tool. The book give readers the hands-on skills to be more productive with Wireshark as they drill

  7. Ultralow power complementary inverter circuits using axially doped p- and n-channel Si nanowire field effect transistors

    Science.gov (United States)

    van, Ngoc Huynh; Lee, Jae-Hyun; Whang, Dongmok; Kang, Dae Joon

    2016-06-01

    We have successfully synthesized axially doped p- and n-type regions on a single Si nanowire (NW). Diodes and complementary metal-oxide-semiconductor (CMOS) inverter devices using single axial p- and n-channel Si NW field-effect transistors (FETs) were fabricated. We show that the threshold voltages of both p- and n-channel Si NW FETs can be lowered to nearly zero by effectively controlling the doping concentration. Because of the high performance of the p- and n-type Si NW channel FETs, especially with regard to the low threshold voltage, the fabricated NW CMOS inverters have a low operating voltage (high voltage gain (~6) and ultralow static power dissipation (high-performance high-density logic circuit using a low-temperature fabrication process, which makes it suitable for flexible electronics.We have successfully synthesized axially doped p- and n-type regions on a single Si nanowire (NW). Diodes and complementary metal-oxide-semiconductor (CMOS) inverter devices using single axial p- and n-channel Si NW field-effect transistors (FETs) were fabricated. We show that the threshold voltages of both p- and n-channel Si NW FETs can be lowered to nearly zero by effectively controlling the doping concentration. Because of the high performance of the p- and n-type Si NW channel FETs, especially with regard to the low threshold voltage, the fabricated NW CMOS inverters have a low operating voltage (high voltage gain (~6) and ultralow static power dissipation (high-performance high-density logic circuit using a low-temperature fabrication process, which makes it suitable for flexible electronics. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01040g

  8. A field guide to geophysics in archaeology

    CERN Document Server

    Oswin, John

    2009-01-01

    Geophysics operations in archaeology have become well known through exposure on television. However, the technique is presented as the action of specialists and something of a mystery, where people walk about with strange contraptions, and results appear from a computer. This is not the case, however. Some scientific knowledge is needed in order to understand how the machines work and what they detect but otherwise it is only necessary to know how to handle the instruments, how to survey a field and how to interpret the computer results. This book provides all the relevant information. It explains geophysics operations in archaeology, describes the science that gives the soil properties to measure and the means by which the instruments make their measurements. Dr John Oswin is in charge of the geophysics operation of the Bath and Camerton Archaeological Society and his work has recently been the subject of a television programme. He has taught many students how to use geophysical equipment.

  9. Influence of an external axial magnetic field on betatron radiation from the interaction of a circularly polarized laser with plasma

    Science.gov (United States)

    Du, Bao; Wang, Xiao-Fang

    2017-09-01

    In this paper, theoretical analyses and numerical calculations are carried out to investigate the influence of an externally applied axial constant magnetic field on electrons' betatron radiation when an ultra-short, circularly polarized laser pulse of a peak intensity I0 = 5 × 1019 W/cm2 propagates in plasma of an electron density n0 = 1020/cm3. Ring-like x-ray radiation is emitted from the electrons' betatron oscillations. The applied magnetic field can modulate the resonance process between an electron's betatron oscillation and the laser electric field, and the electron energy gain from the direct laser acceleration is thus changed. When a magnetic field of strength B0=3 × 103 T is applied, which is in anti-parallel to the self-generated axial magnetic field, both the trapping efficiency of electrons by the wakefield and the maximum accelerated energy are increased. The maximum electron energy, the peak of angular radiation, and the total radiation energy are increased by 11.0%, 45.6%, and 41.1%, respectively, and the radiation spectra are blue-shifted significantly.

  10. Nuclear axial current operators to fourth order in chiral effective field theory

    OpenAIRE

    Krebs, H; Epelbaum, E.; Meißner, U.-G

    2016-01-01

    We present the complete derivation of the nuclear axial charge and current operators as well as the pseudoscalar operators to fourth order in the chiral expansion relative to the dominant one-body contribution using the method of unitary transformation. We demonstrate that the unitary ambiguity in the resulting operators can be eliminated by the requirement of renormalizability and by matching of the pion-pole contributions to the nuclear forces. We give expressions for the renormalized singl...

  11. On guided versus deflected fields in controlled-source electromagnetics

    Science.gov (United States)

    Swidinsky, Andrei

    2015-06-01

    The detection of electrically resistive targets in applied geophysics is of interest to the hydrocarbon, mining and geotechnical industries. Elongated thin resistive bodies have been extensively studied in the context of offshore hydrocarbon exploration. Such targets guide electromagnetic fields in a process which superficially resembles seismic refraction. On the other hand, compact resistive bodies deflect current in a process which has more similarities to diffraction and scattering. The response of a real geological structure is a non-trivial combination of these elements-guiding along the target and deflection around its edges. In this note the electromagnetic responses of two end-member models are compared: a resistive layer, which guides the electromagnetic signal, and a resistive cylinder, which deflects the fields. Results show that the response of a finite resistive target tends to saturate at a much lower resistivity than a resistive layer, under identical survey configurations. Furthermore, while the guided electromagnetic fields generated by a buried resistive layer contain both anomalous horizontal and vertical components, the process of electromagnetic deflection from a buried resistive cylinder creates mainly anomalous vertical fields. Finally, the transmitter orientation with respect to the position of a finite body is an important survey parameter: when the distance to the target is much less than the host skin depth, a transmitter pointing towards the resistive cylinder will produce a stronger signal than a transmitter oriented azimuthally with respect to the cylinder surface. The opposite situation is observed when the distance to the target is greater than the host skin depth.

  12. My Inquiry Journey: A Field Guide for Learners

    Science.gov (United States)

    Mazzola, Alison Fox

    2009-01-01

    Children start asking questions as soon as they speak their first sentences. And they continue to ask them at home and in the classroom if adults let them. Mosaic of Thought (Keene and Zimmermann 2007) has provided the author with a "field guide" to both her son's questions at home and her second-grade students' questions in the classroom. Keene…

  13. Boundary-value problem for a counterrotating electrical discharge in an axial magnetic field. [plasma centrifuge for isotope separation

    Science.gov (United States)

    Hong, S. H.; Wilhelm, H. E.

    1978-01-01

    An electrical discharge between two ring electrodes embedded in the mantle of a cylindrical chamber is considered, in which the plasma in the anode and cathode regions rotates in opposite directions under the influence of an external axial magnetic field. The associated boundary-value problem for the coupled partial differential equations describing the azimuthal velocity and radial current-density fields is solved in closed form. The velocity, current density, induced magnetic induction, and electric fields are presented for typical Hartmann numbers, magnetic Reynolds numbers, and geometry parameters. The discharge is shown to produce anodic and cathodic plasma sections rotating at speeds of the order 1,000,000 cm/sec for conventional magnetic field intensities. Possible application of the magnetoactive discharge as a plasma centrifuge for isotope separation is discussed.

  14. Star formation from dark filamentary clouds: Gravitational stability of a cylindrical plasma with an azimuthal and axial magnetic field

    CERN Document Server

    McLeman, James A; Bingham, Robert

    2012-01-01

    The precise process by which dark filamentary clouds collapse to form stars is a subject of intense debate. In this paper we consider a cylindrical distribution of plasma with both axial and azimuthal magnetic field and examine the resulting gravitational stability. The azimuthal magnetic field is created from an electric current in the plasma and is found to be dictated by Ampere's law. We model this system by using the magnetohydrodynamic (MHD) equation to derive a new virial theorem. We can reduce it to the virial theorem due to Chandrasekhar and Fermi (1953) if we remove the azimuthal magnetic field, as this will represent the case which they have considered. This new virial theorem gives us a fresh insight into the stability of the system. We also derive from this new virial theorem the case where there is only an azimuthal magnetic field. Our generalised stability condition allows for a possible electric current within realistic astronomical values.

  15. Quantitative study of guide-field effects on Hall reconnection in a laboratory plasma.

    Science.gov (United States)

    Tharp, T D; Yamada, M; Ji, H; Lawrence, E; Dorfman, S; Myers, C E; Yoo, J

    2012-10-19

    The effect of guide field on magnetic reconnection is quantitatively studied by systematically varying an applied guide field in the Magnetic Reconnection Experiment (MRX). The quadrupole field, a signature of two-fluid reconnection at zero guide field, is altered by a finite guide field. It is shown that the reconnection rate is significantly reduced with increasing guide field, and this dependence is explained by a combination of local and global physics: locally, the in-plane Hall currents are reduced, while globally guide field compression produces an increased pressure both within and downstream of the reconnection region.

  16. Analysis and Design Considerations of a High-Power Density, Dual Air Gap, Axial-Field Brushless, Permanent Magnet Motor.

    Science.gov (United States)

    Cho, Chahee Peter

    1995-01-01

    Until recently, brush dc motors have been the dominant drive system because they provide easily controlled motor speed over a wide range, rapid acceleration and deceleration, convenient control of position, and lower product cost. Despite these capabilities, the brush dc motor configuration does not satisfy the design requirements for the U.S. Navy's underwater propulsion applications. Technical advances in rare-earth permanent magnet materials, in high-power semiconductor transistor technology, and in various rotor position-sensing devices have made using brushless permanent magnet motors a viable alternative. This research investigates brushless permanent magnet motor technology, studying the merits of dual-air gap, axial -field, brushless, permanent magnet motor configuration in terms of power density, efficiency, and noise/vibration levels. Because the design objectives for underwater motor applications include high-power density, high-performance, and low-noise/vibration, the traditional, simplified equivalent circuit analysis methods to assist in meeting these goals were inadequate. This study presents the development and verification of detailed finite element analysis (FEA) models and lumped parameter circuit models that can calculate back electromotive force waveforms, inductance, cogging torque, energized torque, and eddy current power losses. It is the first thorough quantification of dual air-gap, axial -field, brushless, permanent magnet motor parameters and performance characteristics. The new methodology introduced in this research not only facilitates the design process of an axial field, brushless, permanent magnet motor but reinforces the idea that the high-power density, high-efficiency, and low-noise/vibration motor is attainable.

  17. Automated particulate sampler field test model operations guide

    Energy Technology Data Exchange (ETDEWEB)

    Bowyer, S.M.; Miley, H.S.

    1996-10-01

    The Automated Particulate Sampler Field Test Model Operations Guide is a collection of documents which provides a complete picture of the Automated Particulate Sampler (APS) and the Field Test in which it was evaluated. The Pacific Northwest National Laboratory (PNNL) Automated Particulate Sampler was developed for the purpose of radionuclide particulate monitoring for use under the Comprehensive Test Ban Treaty (CTBT). Its design was directed by anticipated requirements of small size, low power consumption, low noise level, fully automatic operation, and most predominantly the sensitivity requirements of the Conference on Disarmament Working Paper 224 (CDWP224). This guide is intended to serve as both a reference document for the APS and to provide detailed instructions on how to operate the sampler. This document provides a complete description of the APS Field Test Model and all the activity related to its evaluation and progression.

  18. Jet deflection by very weak guide fields during magnetic reconnection.

    Science.gov (United States)

    Goldman, M V; Lapenta, G; Newman, D L; Markidis, S; Che, H

    2011-09-23

    Previous 2D simulations of reconnection using a standard model of initially antiparallel magnetic fields have detected electron jets outflowing from the x point into the ion outflow exhausts. Associated with these jets are extended "outer electron diffusion regions." New PIC simulations with an ion to electron mass ratio as large as 1836 (an H(+) plasma) now show that the jets are strongly deflected and the outer electron diffusion region is broken up by a very weak out-of-plane magnetic guide field, even though the diffusion rate itself is unchanged. Jet outflow and deflection are interpreted in terms of electron dynamics and are compared to recent measurements of jets in the presence of a small guide field in Earth's magnetosheath.

  19. Three-Dimensional Modeling of Guide-Field Magnetic Reconnection

    Science.gov (United States)

    Hesse, Michael

    2005-01-01

    The dissipation mechanism of guide field magnetic reconnection remains a subject of intense scientific interest. On one hand, one set of recent studies have shown that particle inertia-based processes, which include thermal and bulk inertial effects, provide the reconnection electric field in the diffusion region. On the other hand, a second set of studies emphasizes the role of wave-particle interactions in providing anomalous resistivity in the diffusion region. In this presentation, we analyze three-dimensional PIC simulations of guide-field magnetic reconnection. Specific emphasis will be on the question whether thermal-inertia processes, mediated by the electron pressure tensor, remain a viable dissipation mechanism in fully three-dimensional systems.

  20. Nuclear axial current operators to fourth order in chiral effective field theory

    CERN Document Server

    Krebs, H; Meißner, U -G

    2016-01-01

    We present the complete derivation of the nuclear axial charge and current operators as well as the pseudoscalar operators to fourth order in the chiral expansion relative to the dominant one-body contribution using the method of unitary transformation. We demonstrate that the unitary ambiguity in the resulting operators can be eliminated by the requirement of renormalizability and by matching of the pion-pole contributions to the nuclear forces. We give expressions for the renormalized single-, two- and three-nucleon contributions to the charge and current operators and pseudoscalar operators including the relevant relativistic corrections. We also verify explicitly the validity of the continuity equation.

  1. Computer Calculations of Eddy-Current Power Loss in Rotating Titanium Wheels and Rims in Localized Axial Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Mayhall, D J; Stein, W; Gronberg, J B

    2006-05-15

    We have performed preliminary computer-based, transient, magnetostatic calculations of the eddy-current power loss in rotating titanium-alloy and aluminum wheels and wheel rims in the predominantly axially-directed, steady magnetic fields of two small, solenoidal coils. These calculations have been undertaken to assess the eddy-current power loss in various possible International Linear Collider (ILC) positron target wheels. They have also been done to validate the simulation code module against known results published in the literature. The commercially available software package used in these calculations is the Maxwell 3D, Version 10, Transient Module from the Ansoft Corporation.

  2. Local electric field enhancement at the heterojunction of Si/SiGe axially heterostructured nanowires under laser illumination

    Science.gov (United States)

    Pura, Jose Luis; Anaya, Julián; Souto, Jorge; Carmelo Prieto, Ángel; Rodríguez, Andrés; Rodríguez, Tomás; Jiménez, Juan

    2016-11-01

    We present a phenomenon concerning electromagnetic enhancement at the heterojunction region of axially heterostructured Si/SiGe nanowires when the nanowire is illuminated by a focused laser beam. The local electric field is sensed by micro Raman spectroscopy, which allows the enhancement of the Raman signal arising from the heterojunction region to be revealed; the Raman signal per unit volume increases at least ten times with respect to the homogeneous Si and SiGe nanowire segments. In order to explore the physical meaning of this phenomenon, a three-dimensional solution of the Maxwell equations of the interaction between the focused laser beam and the nanowire was carried out by finite element methods. A local enhancement of the electric field at the heterojunction was deduced. However, the magnitude of the electromagnetic field enhancement only approaches the experimental one when the free carriers are considered, showing enhanced absorption at the carrier depleted heterojunction region. The existence of this effect promises a way of improving photon harvesting using axially heterostructured semiconductor nanowires.

  3. Lie map for the nonlinear transport of continuous intense beams in the axial-symmetric electrostatic fields

    Institute of Scientific and Technical Information of China (English)

    Jianqin Lü; Xiaosong Zhao

    2008-01-01

    Nonlinear transport of intense continuous beam in the axial-symmetric electrostatic fields is analyzed with the Lie algebraic method.The K-V particle distribution is adopted in the analysis. The results obtained can be used in the calculations of the intense continuous beam dynamics in the beam optical systems consisting of drift spaces, electrostatic lenses, and DC electrostatic accelerating tubes. A com-puter code has been designed for practical simulations. To meet the needs of accurate calculation, all the elements are divided into many small segments, the electric fields in each segment are regarded as uniform fields, and the dividing points are treated as thin lenses. Iter-ation procedures are adopted in the code to obtain self-consistent solutions. The code can be used to design low energy dc beam transport systems, electrostatic accelerators, and ion implantation machines.

  4. An experimental study on the effects of tip clearance on flow field and losses in an axial flow compressor rotor

    Science.gov (United States)

    Lakshminarayana, B.; Zhang, J.; Murthy, K. N. S.

    1987-01-01

    Detailed measurement of the flow field in the tip region of a compressor rotor was carried out using a Laser Doppler Velocimeter (LDV) and a Kiel probe at two different tip clearance heights. At both clearance sizes, the relative stagnation pressure and the axial and tangential components of relative velocities were measured upstream, inside the passage and downstream of the rotor, up to about 20 percent of the blade span from the annulus wall. The velocities, outlet angles, losses, momentum thickness, and force defect thickness are compared for the two clearances. A detailed interpretation of the effect of tip clearance on the flow field is given. There are substantial differences in flow field, on momentum thickness, and performance as the clearance is varied. The losses increase linearly within the passage and their values increase in direct proportion to tip clearance height. No discernable vortex (discrete) is observed downstream of the rotor.

  5. Correction of static axial alignment in children with knee varus or valgus deformities through guided growth: Does it also correct dynamic frontal plane moments during walking?

    Science.gov (United States)

    Böhm, Harald; Stief, Felix; Sander, Klaus; Hösl, Matthias; Döderlein, Leonhard

    2015-09-01

    Malaligned knees are predisposed to the development and progression of unicompartmental degenerations because of the excessive load placed on one side of the knee. Therefore, guided growth in skeletally immature patients is recommended. Indication for correction of varus/valgus deformities are based on static weight bearing radiographs. However, the dynamic knee abduction moment during walking showed only a weak correlation to malalignment determined by static radiographs. Therefore, the aim of the study was to measure the effects of guided growth on the normalization of frontal plane knee joint moments during walking. 15 legs of 8 patients (11-15 years) with idiopathic axial varus or valgus malalignment were analyzed. 16 typically developed peers served as controls. Instrumented gait analysis and clinical assessment were performed the day before implantation and explantation of eight-plates. Correlation between static mechanical tibiofemoral axis angle (MAA) and dynamic frontal plane knee joint moments and their change by guided growth were performed. The changes in dynamic knee moment in the frontal plane following guided growth showed high and significant correlation to the changes in static MAA (R=0.97, pknee moment before treatment showed a more pathological one after treatment. In conclusion, the changes in the dynamic load situation during walking can be predicted from the changes in static alignment. If pre-surgical gait analysis reveals a natural load situation, despite a static varus or valgus deformity, the intervention must be critically discussed.

  6. GUIDING OF PLASMA BY ELECTRIC FIELD AND MAGNETIC FIELD

    Institute of Scientific and Technical Information of China (English)

    ZHANG TAO; HOU JUN-DA; TANG BAO-YIN; P. K. CHU; I. G. BROWN

    2001-01-01

    The relationship between the transported ion current and the cathodic arc current is determined in a vacuum arc plasma source equipped with a curved magnetic filter. Our results suggest that the outer and inner walls of the duct interact with the plasma independently. The duct magnetic field is a critical factor of the plasma output. The duct transport efficiency is to maximize at a value of bias plate voltage in the range +10 V to +20 V, and independent (within our limit of measurement) of the magnetic field strength in the duct. The plasma flux is composed of two components:a diffusion flux in the transverse direction due to particle collisions, and a drift flux due to the ion inertia. The inner wall of the magnetic duct sees only the diffusion flux while the outer wall receives both fluxes. Thus, applying a positive potential to the outer duct wall can reflect the ions and increase the output current. Our experimental data also show that biasing both sides of the duct is more effective than biasing the outer wall alone.

  7. A Field Guide to Constructivism in the College Science Classroom: Four Essential Criteria and a Guide to Their Usage

    Science.gov (United States)

    Hartle, R. Todd; Baviskar, Sandhya; Smith, Rosemary

    2012-01-01

    This field guide provides four essential criteria for constructivism as well as a guide for using these criteria to identify and assess the level of constructivism being used in an educational experience. The criteria include: 1) prior knowledge, 2) cognitive dissonance, 3) application with feedback, and 4) metacognition. This guide provides…

  8. Primordial magnetic fields of non-minimal photon-torsion axial coupling origin

    CERN Document Server

    de Andrade, Garcia

    2010-01-01

    Dynamo action is shown to be induced from homogeneous non-minimal photon-torsion axial coupling in the quantum electrodynamics (QED) framework in Riemann flat spacetime contortion decays. The geometrical optics in Riemann-Cartan spacetime is considering and a plane wave expansion of the electromagnetic vector potential is considered leading to a set of the equations for the ray congruence. Since we are interested mainly on the torsion effects in this first report we just consider the Riemann-flat case composed of the Minkowskian spacetime with torsion. It is also shown that in torsionic de Sitter background the vacuum polarisation does alter the propagation of individual photons, an effect which is absent in Riemannian spaces. It is shown that the cosmological torsion background inhomogeneities induce Lorentz violation and massive photon modes in this QED. Magnetic dynamos in this torsioned spacetime electrodynamics are simpler obtained in Fourier space than the cosmic ones, previously obtained by Bassett et ...

  9. Three dimensional density cavities in guide field collisionless magnetic reconnection

    CERN Document Server

    Markidis, Stefano; Divin, Andrey; Goldman, Martin V; Newman, D; Andersson, Laila

    2012-01-01

    Particle-in-Cell simulations of collisionless magnetic reconnection with a guide field reveal for the first time the three dimensional features of the low density regions along the magnetic reconnection separatrices, the so-called "cavities". It is found that structures with further lower density develop within the cavities. Because their appearance is similar to the rib shape, these formations are here called "low density ribs". Their location remains approximately fixed in time and their density progressively decreases, as electron currents along the cavities evacuate them. They develop along the magnetic field lines and are supported by a strong perpendicular electric field that oscillates in space. In addition, bipolar parallel electric field structures form as isolated spheres between the cavities and the outflow plasma, along the direction of the low density ribs and of magnetic field lines.

  10. Generation of Helical and Axial Magnetic Fields by the Relativistic Laser Pulses in Under-dense Plasma: Three-Dimensional Particle-in-Cell Simulation

    Science.gov (United States)

    Zheng, Chun-Yang; Zhu, Shao-Ping; He, Xian-Tu

    2002-07-01

    The quasi-static magnetic fields created in the interaction of relativistic laser pulses with under-dense plasmas have been investigated by three-dimensional particle-in-cell simulation. The relativistic ponderomotive force can drive an intense electron current in the laser propagation direction, which is responsible for the generation of a helical magnetic field. The axial magnetic field results from a difference beat of wave-wave, which drives a solenoidal current. In particular, the physical significance of the kinetic model for the generation of the axial magnetic field is discussed.

  11. Collective Effects on the Operation of Free Electron Lasers with an Axial Guide Field.

    Science.gov (United States)

    1982-02-19

    lnstituto de Fisica , Universidade Federal do Rio Grande do Sul, 90.000 Porto Alegre-RS, Brazil 19. KEY WORDS (Continue on rover.ee d if necessry aid... vector potential of the form 19 - - 2B- [ -L I(k~r) cos (0-kz)., - I, (kr) sin (O-k,,z)i. (2) in cylindrical coordinates. In Eq. (2), B. and k, (ME...form exp(- iw r) and choose to work with the scalar and vector potentials 86z t) - (z) exp(-icat) + c.c.. 2 4 i.U- NRL MEMORANDUM REPORT 4763 and 8 A

  12. Observations of altered instability structure for imploding z-pinch liners that are premagnetized with a uniform axial field

    Science.gov (United States)

    Awe, Thomas

    2013-10-01

    Magnetically driven implosions provide an energy-rich platform for inertial confinement fusion. The magnetized liner inertial fusion concept (MagLIF, Slutz et al., Phys. Plasmas 17, 056303 (2010)) uses a pulsed-power-driven metallic liner to compress and inertially confine preheated and premagnetized fusion fuel. The fuel is premagnetized with a uniform axial seed field Bz , 0 of 10 to 30 T, which is then compressed by the liner to nearly 1000 T. In the fuel, the ultra-high field reduces thermal conduction and enhances alpha-particle heating. Preheating the fuel to 100-300 eV eases requirements on liner-convergence; nonetheless, convergence ratios at stagnation of 20 or more may be necessary. The ability to maintain liner stability and uniformity through stagnation may ultimately determine the success of the MagLIF concept. The integrity of magnetically imploded liners is compromised both by electrode instabilities and by the magneto-Rayleigh Taylor (MRT) instability. Electrode instabilities form local perturbations that can mix liner material into the fuel prior to bulk compression. Recent experiments on the Z facility have shown that this instability is mitigated when the liner's ends implode onto a nylon ``cushion,'' which impedes local perturbation growth. Other recent experiments have, for the first time, studied the implosion dynamics of premagnetized (Bz , 0 > 0) MagLIF-type liners. When seeded with a 7 or 10 T axial field, these liners developed 3D-helix-like surface instabilities; such instabilities starkly contrast with the azimuthally-correlated MRT instabilities that have been consistently observed in many earlier unmagnetized (Bz , 0 = 0 T) experiments. Quite unexpectedly, the helical structure persisted throughout the implosion, even though the azimuthal drive field greatly exceeded the expected axial field at the liner surface for all but the earliest stages of the experiment. Thus far, no self-consistent model has reproduced this fundamentally 3D

  13. Characteristic and magnetic field analysis of a high temperature superconductor axial-flux coreless induction maglev motor

    Science.gov (United States)

    Wei, Qin; Yu, Fan; Jin, Fang; Shuo, Li; Guoguo, Li; Gang, Lv

    2012-04-01

    A new high temperature superconductor axial-flux coreless maglev motor (HTS AFIM) is proposed, of which the primary windings are made of HTS tapes and the secondary is a non-magnetic conductor. The main works of this paper are the magnetic-field computation and characteristics analysis of HTS AFIM. For the first one, the reduction of magnetic fields near outer and inner radius of the HTS AFIM is solved by introducing the sub-loop electro-magnetic model along the radial position. For the second one, the AC losses of HTS coils are calculated. The relationships between the device's characteristics and device parameters are presented, and the results indicate that under certain frequency and current levitation device can output enough lift force. The conclusions are verified by finite element calculations.

  14. Characteristic and magnetic field analysis of a high temperature superconductor axial-flux coreless induction maglev motor.

    Science.gov (United States)

    Wei, Qin; Yu, Fan; Jin, Fang; Shuo, Li; Guoguo, Li; Gang, Lv

    2012-04-01

    A new high temperature superconductor axial-flux coreless maglev motor (HTS AFIM) is proposed, of which the primary windings are made of HTS tapes and the secondary is a non-magnetic conductor. The main works of this paper are the magnetic-field computation and characteristics analysis of HTS AFIM. For the first one, the reduction of magnetic fields near outer and inner radius of the HTS AFIM is solved by introducing the sub-loop electro-magnetic model along the radial position. For the second one, the AC losses of HTS coils are calculated. The relationships between the device's characteristics and device parameters are presented, and the results indicate that under certain frequency and current levitation device can output enough lift force. The conclusions are verified by finite element calculations.

  15. Sweet reason a field guide to modern logic

    CERN Document Server

    Henle, James M; Tymoczko, Thomas; Altreuter, Emily

    2011-01-01

    Sweet Reason: A Field Guide to Modern Logic, 2nd Edition offers an innovative, friendly, and effective introduction to logic. It integrates formal first order, modal, and non-classical logic with natural language reasoning, analytical writing, critical thinking, set theory, and the philosophy of logic and mathematics.An innovative introduction to the field of logic designed to entertain as it informsIntegrates formal first order, modal, and non-classical logic with natural language reasoning, analytical writing, critical thinking, set theory, and the philosophy of

  16. A Field Guide for Science Writers - The Official Guide of the National Association of Science Writers

    Science.gov (United States)

    Blum, Deborah; Knudson, Mary; Marantz Henig, Robin

    2005-09-01

    This is the official text for the National Association of Science Writers. In the eight years since the publication of the first edition of A Field Guide for Science Writing, much about the world has changed. Some of the leading issues in today's political marketplace - embryonic stem cell research, global warming, health care reform, space exploration, genetic privacy, germ warfare - are informed by scientific ideas. Never has it been more crucial for the lay public to be scientifically literate. That's where science writers come in. And that's why it's time for an update to the Field Guide, already a staple of science writing graduate programs across the country. The academic community has recently recognized how important it is for writers to become more sophisticated, knowledgeable, and skeptical about what they write. More than 50 institutions now offer training in science writing. In addition mid-career fellowships for science writers are growing, giving journalists the chance to return to major universities for specialized training. We applaud these developments, and hope to be part of them with this new edition of the Field Guide. In A Field Guide for Science Writers, 2nd Edition, the editors have assembled contributions from a collections of experienced journalists who are every bit as stellar as the group that contributed to the first edition. In the end, what we have are essays written by the very best in the science writing profession. These wonderful writers have written not only about style, but about content, too. These leaders in the profession describe how they work their way through the information glut to find the gems worth writing about. We also have chapters that provide the tools every good science writer needs: how to use statistics, how to weigh the merits of conflicting studies in scientific literature, how to report about risk. And, ultimately, how to write.

  17. Estimation of the collection efficiency of the axial flow cyclone dust collector with the fixed guide vanes

    Science.gov (United States)

    Ogawa, Akira; Iwanami, Tetzuya; Shono, Hideki

    1997-03-01

    In order to estimate the cut-size Xc and the mechanically balanced particles in the axial flow cyclone with the slit-separation method, the tangential velocity distributions were calculated by the finite difference method. In comparison of the calculated results of the total collection efficiency with the experimental results, the calculated results showed a little higher than the experimental results due to the re-entrainment of the collected particles by turbulence. The effect of the slit for promoting the collection efficiency was not recognized.

  18. Estimation of the Collection Efficiency of the Axial FLow Cyclone Dust Collector with the Fixed Guide Vanes

    Institute of Scientific and Technical Information of China (English)

    AkiraOGAWA; TetzuyaIWANAMI; 等

    1997-01-01

    In order to estimate the cut-size Xc and the mechanically balanced particles in the axial flow cyclone with the slit-separation method,the tangential velocity distributions were calculated by the finite difference method.In comparison of the calculated results of the total collection effciency with the experimental results,the calculated results showed a little higher than the experimental results due to the re-entrainment of the collected particles by turbulence.The effect of the slit for promoting the collection efficiency was not recognized.

  19. Localized Electron Heating by Strong Guide-Field Magnetic Reconnection

    Science.gov (United States)

    Guo, Xuehan; Sugawara, Takumichi; Inomoto, Michiaki; Yamasaki, Kotaro; Ono, Yasushi; UTST Team

    2015-11-01

    Localized electron heating of magnetic reconnection was studied under strong guide-field (typically Bt 15Bp) using two merging spherical tokamak plasmas in Univ. Tokyo Spherical Tokamak (UTST) experiment. Our new slide-type two-dimensional Thomson scattering system documented for the first time the electron heating localized around the X-point. The region of high electron temperature, which is perpendicular to the magnetic field, was found to have a round shape with radius of 2 [cm]. Also, it was localized around the X-point and does not agree with that of energy dissipation term Et .jt . When we include a guide-field effect term Bt / (Bp + αBt) for Et .jt where α =√{ (vin2 +vout2) /v∥2 } , the energy dissipation area becomes localized around the X-point, suggesting that the electrons are accelerated by the reconnection electric field parallel to the magnetic field and thermalized around the X-point. This work was supported by JSPS A3 Foresight Program ``Innovative Tokamak Plasma Startup and Current Drive in Spherical Torus,'' a Grant-in-Aid from the Japan Society for the Promotion of Science (JSPS) Fellows 15J03758.

  20. Mechanisms influencing student understanding on an outdoor guided field trip

    Science.gov (United States)

    Caskey, Nourah Al-Rashid

    Field trips are a basic and important, yet often overlooked part of the student experience. They provide the opportunity to integrate real world knowledge with classroom learning and student previous personal experiences. Outdoor guided field trips leave students with an increased understanding, awareness and interest and in science. However, the benefits of this experience are ambiguous at best (Falk and Balling, 1982; Falk and Dierking, 1992; Kisiel, 2006.) Students on an outdoor guided field trip to a local nature park experienced a significant increase in their understanding of the rock cycle. The changes in the pre-field trip test and the post-field trip test as well as their answers in interviews showed a profound change in the students' understanding and in their interest in the subject matter. The use of the "student's voice" (Bamberger and Tal, 2008) was the motivation for data analysis. By using the students' voice, I was able to determine the mechanisms that might influence their understanding of a subject. The central concepts emerging from the data were: the outdoor setting; the students' interest; the social interaction. From these central concepts, a conceptual model was developed. The outdoor setting allows for the freedom to explore, touch, smell and movement. This, in turn, leads to an increased interest in subject matter. As the students are exploring, they are enjoying themselves and become more open to learning. Interest leads to a desire to learn (Dewey, 1975). In addition to allowing the freedom to explore and move, the outdoor setting creates the condition for social interaction. The students talk to each other as they walk; they have in-depth discourse regarding the subject matter---with the teachers, each other and with the guides. The guides have an extremely important role in the students' learning. The more successful guides not only act as experts, but also adjust to the students' needs and act or speak accordingly. The

  1. Earth magnetism a guided tour through magnetic fields

    CERN Document Server

    Campbell, Wallace H

    2001-01-01

    An introductory guide to global magnetic field properties, Earth Magnetism addresses, in non-technical prose, many of the frequently asked questions about Earth''s magnetic field. Magnetism surrounds and penetrates our Earth in ways basic science courses can rarely address. It affects navigation, communication, and even the growth of crystals. As we observe and experience an 11-year solar maximum, we may witness spectacular satellite-destroying solar storms as they interact with our magnetic field. Written by an acknowledged expert in the field, this book will enrich courses in earth science, atmospheric science, geology, meteorology, geomagnetism, and geophysics. Contains nearly 200 original illustrations and eight pages of full-color plates.* Largely mathematics-free and with a wide breadth of material suitable for general readers* Integrates material from geomagnetism, paleomagnetism, and solar-terrestrial space physics.* Features nearly 200 original illustrations and 4 pages of colour plates

  2. Magnetic guide field generation in collisionless current sheets

    Directory of Open Access Journals (Sweden)

    W. Baumjohann

    2010-03-01

    Full Text Available In thin (Δ< few λi collisionless current sheets in a space plasma like the magnetospheric tail or magnetopause current layer, magnetic fields can grow from thermal fluctuation level by the action of the non-magnetic Weibel instability (Weibel, 1959. The instability is driven by the counter-streaming electron inflow from the "ion diffusion" (ion inertial Hall region into the inner current (electron inertial region after thermalisation by the two-stream instability. Under magnetospheric tail conditions it takes ~50 e-folding times (~100 s for the Weibel field to reach observable amplitudes |bW|~1 nT. In counter-streaming inflows these fields are of guide field type.

  3. 基于CFD的前置导叶轴流泵通用特性曲线预报%General characteristic curve forecast for axial flow pump with front guide vane by CFD

    Institute of Scientific and Technical Information of China (English)

    戴原星; 王立祥

    2013-01-01

    Based on the solution of relative steady time-averaged Reynolds equation enclosed by the RNG k-εtwo-equation turbulence model,general characteristic curve for axial flow pump with front guide vane has been drawn out by full 3D numerical simulation during preliminary design. The design point is evaluated by analysis whether the design operation point has optimal efficiency. The internal flow field is captured to observe whether the prerotation reaches proper position and whether there is rotational flow in the wake. The results have important significance for improvement and optimization of axial flow pump with front guide vane during the preliminary design.%通过求解由RNG k-ε二方程湍流模型封闭的相对定常雷诺时均方程,对初始设计的前置导叶轴流泵进行全三维数值模拟,得到通用特性曲线。分析设计工况点是否在最佳效率处,设计点是否成功。捕捉前置导叶轴流泵内流场,观察导叶预旋是否到位,尾流场是否有旋流。所得的结果对初始设计的前置导叶轴流泵的改进和优化具有十分重要的意义。

  4. A phase-field approach to model multi-axial and microstructure dependent fracture in nuclear grade graphite

    Science.gov (United States)

    Chakraborty, Pritam; Sabharwall, Piyush; Carroll, Mark C.

    2016-07-01

    The fracture behavior of nuclear grade graphites is strongly influenced by underlying microstructural features such as the character of filler particles, and the distribution of pores and voids. These microstructural features influence the crack nucleation and propagation behavior, resulting in quasi-brittle fracture with a tortuous crack path and significant scatter in measured bulk strength. This study uses a phase-field method to model the microstructural and multi-axial fracture in H-451, a historic variant of nuclear graphite that provides the basis for an idealized study on a legacy grade. The representative volume elements are constructed from randomly located pores with random size obtained from experimentally determined log-normal distribution. The representative volume elements are then subjected to simulated multi-axial loading, and a reasonable agreement of the resulting fracture stress with experiments is obtained. Quasi-brittle stress-strain evolution with a tortuous crack path is also observed from the simulations and is consistent with experimental results.

  5. Axial magnetic field and toroidally streaming fast ions in the dense plasma focus are natural consequences of conservation laws in the curved axisymmetric geometry of the current sheath

    CERN Document Server

    Auluck, S K H

    2014-01-01

    Direct measurement of axial magnetic field in the PF-1000 dense plasma focus (DPF), and its reported correlation with neutron emission, call for a fresh look at previous reports of existence of axial magnetic field component in the DPF from other laboratories, and associated data suggesting toroidal directionality of fast ions participating in fusion reactions, with a view to understand the underlying physics. In this context, recent work dealing with application of the hyperbolic conservation law formalism to the DPF is extended in this paper to a curvilinear coordinate system, which reflects the shape of the DPF current sheath. Locally-unidirectional shock propagation in this coordinate system enables construction of a system of 7 one-dimensional hyperbolic conservation law equations with geometric source terms, taking into account all the components of magnetic field and flow velocity. Rankine-Hugoniot jump conditions for this system lead to expressions for the axial magnetic field and three components of ...

  6. Performance Analysis of a New Axial Guide Vane Based on Numerical Simulation%基于数值模拟的新型轴向导叶性能分析

    Institute of Scientific and Technical Information of China (English)

    徐媛晖; 张启华; 施卫东; 陆伟刚; 王川; 周岭

    2014-01-01

    由于塑料具有成本低、轻巧、表面光洁等优点已获得广泛的工程应用。但传统扭曲空间导叶由于叶片几何边界复杂,很难通过注塑工艺进行生产,而应采用圆柱叶片。因此,本文通过125QJ20型塑料泵的研发,设计出新型轴向导叶。为分析该导叶的性能,结合自主开发的导叶设计软件DLSJ,根据参数设计出另一径向导叶模型,并将同一叶轮分别与两个导叶进行匹配。再通过Fluent 软件,采用标准k-ε模型、SIMPLEC 算法对这两组模型分别进行了全流场数值计算,并对导叶内部内流场进行对比分析,结果表明轴向导叶外特性明显优于径向导叶。通过流场分析,该新型轴向导叶能改善导叶内部流动,提高井泵水力性能。同时,新导叶具有注塑简单的特点,可有效降低成本,有着较好的市场前景。%Plastic moldings were widely applied due to the merits of light-weight and low surface roughness. Twisted blade in space guide vane can not be easily casted by plastic injection molding process because of its complex surface boundaries. There-fore, through development of 125QJ20 deep well pump, a new axial guide vane was designed. In order to examine its perform-ance, a radial guide vane was designed which was conducted by the in-house design software DLSJ for guide vanes. Each guide vane was assembled with the same impeller. Then the numerical simulations of internal flow field of the two models were carried out on the platform of FLUENT software. The comparative analysis of the internal flow field of the two guide vanes reveals that the axial guide vane can effectively improve the internal flow and obtain better hydraulic performance. Obviously the molding process of the new guide vane is simple which can effectively reduce the cost of production. Thus this design shows a promising market prospect for deep well pumps.

  7. Flow Field Measurement in Multi-stage Axial Compressor Stator by Using Multi-hole Pneumatic Probes

    Science.gov (United States)

    Zhiqiang, Wang; Bo, Lu; Chenkai, Zhang; Jun, Hu

    2017-04-01

    In order to realize the stator's internal flow field measurement of the multi-stage axial compressor, many different lengths of L-type five-hole probes and one four-hole probe have been designed. The detailed 3D (three-dimensional) flow fields in the stator blade passage of original and modified large scale compressors have been measured with the probes traversed by a probe traverse mechanism. The objective of the study is to assess the measurement method of adopting multi-hole pneumatic probes to achieve the flow field of stator vane passage. Results clearly demonstrate the flow field characteristics of stator blade passage in original and modified compressors. Furthermore, the reliability of adopted multi-hole pneumatic probes is validated. Therefore, it is proved that the probe traverse mechanism drives the L-type five-hole probe or other probe method can be applied to internal flow field measurements for the stator of large scale multi-stage compressors.

  8. Time and space correlated investigations of confinement effects due to static axial magnetic fields acting on laser produced carbon plasmas

    Science.gov (United States)

    Favre, Mario; Wyndham, Edmund; Veloso, Felipe; Bhuyan, Heman; Reyes, Sebastian; Ruiz, Hugo Marcelo; Caballero-Bendixsen, Luis Sebastian

    2016-10-01

    We present further detailed studies of the dynamics and plasma properties of a laser produced Carbon plasma expanding in a static axial magnetic field. The laser plasmas are produced in vacuum, 1 .10-6 Torr, using a graphite target, with a Nd:YAG laser, 3.5 ns, 340 mJ at 1.06 μm, focused at 2 .109 W/cm2, and propagate in static magnetic fields of maximum value 0.2 T. 15 ns time and spaced resolved OES is used to investigate plasma composition. 50 ns time resolved plasma imaging is used to visualize the plasma dynamics. A mm size B-dot probe is used, in combination with a Faraday cup, to characterize the interaction between the expanding plasma and the magnetic field. As a result of time and space correlated measurements, unique features of the laser plasma dynamics in the presence of the magnetic field are identified, which highlight the confinement effects of the static magnetic field Funded by project FONDECYT 1141119.

  9. ¹⁴N Quadrupole Resonance line broadening due to the earth magnetic field, occuring only in the case of an axially symmetric electric field gradient tensor.

    Science.gov (United States)

    Aissani, Sarra; Guendouz, Laouès; Marande, Pierre-Louis; Canet, Daniel

    2015-01-01

    As demonstrated before, the application of a weak static B0 magnetic field (less than 10 G) may produce definite effects on the ¹⁴N Quadrupole Resonance line when the electric field gradient tensor at the nitrogen nucleus level is of axial symmetry. Here, we address more precisely the problem of the relative orientation of the two magnetic fields (the static field and the radio-frequency field of the pure NQR experiment). For a field of 6G, the evolution of the signal intensity, as a function of this relative orientation, is in very good agreement with the theoretical predictions. There is in particular an intensity loss by a factor of three when going from the parallel configuration to the perpendicular configuration. By contrast, when dealing with a very weak magnetic field (as the earth field, around 0.5 G), this effect drops to ca. 1.5 in the case Hexamethylenetetramine (HMT).This is explained by the fact that the Zeeman shift (due to the very weak magnetic field) becomes comparable to the natural line-width. The latter can therefore be determined by accounting for this competition. Still in the case of HMT, the estimated natural line-width is half the observed line-width. The extra broadening is thus attributed to earth magnetic field. The latter constitutes therefore the main cause of the difference between the natural transverse relaxation time (T₂) and the transverse relaxation time derived from the observed line-width (T₂(⁎)).

  10. Magnetic Field, Force, and Inductance Computations for an Axially Symmetric Solenoid

    Science.gov (United States)

    Lane, John E.; Youngquist, Robert C.; Immer, Christopher D.; Simpson, James C.

    2001-01-01

    The pumping of liquid oxygen (LOX) by magnetic fields (B field), using an array of electromagnets, is a current topic of research and development at Kennedy Space Center, FL. Oxygen is paramagnetic so that LOX, like a ferrofluid, can be forced in the direction of a B field gradient. It is well known that liquid oxygen has a sufficient magnetic susceptibility that a strong magnetic gradient can lift it in the earth's gravitational field. It has been proposed that this phenomenon can be utilized in transporting (i.e., pumping) LOX not only on earth, but on Mars and in the weightlessness of space. In order to design and evaluate such a magnetic pumping system, it is essential to compute the magnetic and force fields, as well as inductance, of various types of electromagnets (solenoids). In this application, it is assumed that the solenoids are air wrapped, and that the current is essentially time independent.

  11. Population Mixing in Asymmetric Magnetic Reconnection with a Guide Field.

    Science.gov (United States)

    Hesse, M; Chen, L J; Liu, Y-H; Bessho, N; Burch, J L

    2017-04-07

    We investigate how population mixing leads to structured electron distribution functions in asymmetric guide-field magnetic reconnection based on particle-in-cell simulations. The change of magnetic connectivity patches populations from different inflow regions to form multicomponent distributions in the exhaust, illustrating the direct consequence of the breaking and rejoining of magnetic flux tubes. Finite Larmor radius (FLR) effects of electrons accelerated by the perpendicular electric fields result in crescent-type nongyrotropic distributions. A new type of nongyrotropy is found to be caused by the combined effects of the FLR and velocity dispersion of electrons accelerated by the parallel electric field. The patching together of populations and the effects of acceleration and the FLR form the first steps of mixing in the exhaust and separatrix regions.

  12. Analysis of axially symmetric wire antennas by the use of exact kernel of electric field integral equation

    Directory of Open Access Journals (Sweden)

    Krneta Aleksandra J.

    2016-01-01

    Full Text Available The paper presents a new method for the analysis of wire antennas with axial symmetry. Truncated cones have been applied to precisely model antenna geometry, while the exact kernel of the electric field integral equation has been used for computation. Accuracy and efficiency of the method has been further increased by the use of higher order basis functions for current expansion, and by selecting integration methods based on singularity cancelation techniques for the calculation of potential and impedance integrals. The method has been applied to the analysis of a typical dipole antenna, thick dipole antenna and a coaxial line. The obtained results verify the high accuracy of the method. [Projekat Ministarstva nauke Republike Srbije, br. TR-32005

  13. Quantum transport of the semiconductor pump: Due to an axial external field

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Yun-Chang, E-mail: phyxiaofan@163.com [College of Electrical and Information Engineering, Hunan University of Arts and Science, Changde 415000 (China); Wang, Ri-Xing, E-mail: wangrixing@sina.com [College of Electrical and Information Engineering, Hunan University of Arts and Science, Changde 415000 (China); Deng, Wei-Ying, E-mail: weiyindeng@gmail.com [Department of Physics, South China University of Technology, Guangzhou 510640 (China)

    2014-09-15

    Parametric semiconductor pump modulated by the external field is investigated. The pump center attaching to two normal leads is driven by the potentials formed in the interfaces. With the Floquet scattering matrix method, the pumped currents modulated by the parameters are studied. Results reveal that the charge and spin currents pumped from the system can be strengthen by the external field besides the potentials. Directed spin currents can be pumped more strongly than the charge currents, and even the pure spin currents can be achieved in some external field couplings to the pump parameters.

  14. Spin-orbit qubits of rare-earth-metal ions in axially symmetric crystal fields.

    Science.gov (United States)

    Bertaina, S; Shim, J H; Gambarelli, S; Malkin, B Z; Barbara, B

    2009-11-27

    Contrary to the well-known spin qubits, rare-earth-metal qubits are characterized by a strong influence of crystal field due to large spin-orbit coupling. At low temperature and in the presence of resonance microwaves, it is the magnetic moment of the crystal-field ground state which nutates (for several micros) and the Rabi frequency Omega(R) is anisotropic. Here, we present a study of the variations of Omega(R)(H(0)) with the magnitude and direction of the static magnetic field H(0) for the odd 167Er isotope in a single crystal CaWO(4):Er(3+). The hyperfine interactions split the Omega(R)(H(0)) curve into eight different curves which are fitted numerically and described analytically. These "spin-orbit qubits" should allow detailed studies of decoherence mechanisms which become relevant at high temperature and open new ways for qubit addressing using properly oriented magnetic fields.

  15. Field guide to infrared systems, detectors, and FPAs

    CERN Document Server

    Daniels, Arnold

    2011-01-01

    This second edition is written to clarify and summarize the theoretical principles of infrared technology. It is intended as a reference for the practicing engineer and/or scientist who requires effective practical information to design, build, and/or test infrared equipment in a wide variety of applications. This Field Guide combines numerous engineering disciplines necessary for the development of an infrared system. It describes the basic elements involving image formation and image quality, radiometry and flux transfer, and explains the figures of merit involving detector performance. It c

  16. On guided circumferential waves in soft electroactive tubes under radially inhomogeneous biasing fields

    Science.gov (United States)

    Wu, Bin; Su, Yipin; Chen, Weiqiu; Zhang, Chuanzeng

    2017-02-01

    Soft electroactive (EA) tube actuators and many other cylindrical devices have been proposed recently in literature, which show great advantages over those made from conventional hard solid materials. However, their practical applications may be limited because these soft EA devices are prone to various failure modes. In this paper, we present an analysis of the guided circumferential elastic waves in soft EA tube actuators, which has potential applications in the in-situ nondestructive evaluation (NDE) or online structural health monitoring (SHM) to detect structural defects or fatigue cracks in soft EA tube actuators and in the self-sensing of soft EA tube actuators based on the concept of guided circumferential elastic waves. Both circumferential SH and Lamb-type waves in an incompressible soft EA cylindrical tube under inhomogeneous biasing fields are considered. The biasing fields, induced by the application of an electric voltage difference to the electrodes on the inner and outer cylindrical surfaces of the EA tube in addition to an axial pre-stretch, are inhomogeneous in the radial direction. Dorfmann and Ogden's theory of nonlinear electroelasticity and the associated linear theory for small incremental motion constitute the basis of our analysis. By means of the state-space formalism for the incremental wave motion along with the approximate laminate technique, dispersion relations are derived in a particularly efficient way. For a neo-Hookean ideal dielectric model, the proposed approach is first validated numerically. Numerical examples are then given to show that the guided circumferential wave propagation characteristics are significantly affected by the inhomogeneous biasing fields and the geometrical parameters. Some particular phenomena such as the frequency veering and the nonlinear dependence of the phase velocity on the radial electric voltage are discussed. Our numerical findings demonstrate that it is feasible to use guided circumferential

  17. Performance of 15-Stage Experimental J71 Axial-Flow Compressor. III - Effects of Inlet-Guide-Vane Adjustment

    Science.gov (United States)

    Lucas, James G.; Filippi, Richard E.

    1955-01-01

    The stall-limit line at low speeds was improved somewhat by closing the inlet guide vanes 6 deg, while the design-speed maximum flow and pressure ratio were reduced. The first-stage characteristic curve was moved to lower values of both flog coefficient and equivalent pressure ratio. The second-stage pressure ratio was decreased slightly at high speeds, while the later stages were unaffected.

  18. Thermo-Magneto-Convective Transport around a Square Cylinder in a Square Duct under Strong Axial Magnetic Field

    Directory of Open Access Journals (Sweden)

    Dipankar Chatterjee

    2016-01-01

    Full Text Available A quasi two-dimensional numerical study is performed to analyze the thermo-magneto-convective transport of liquid metal around a square cylinder in a square duct subjected to a strong externally imposed axial magnetic field. The channel bottom wall is considered heated while the top wall is maintained at the free stream temperature keeping the cylinder adiabatic. The Reynolds and Hartmann numbers are kept in the range and . The flow dynamics in the aforementioned range of parameters reveals the existence of four different regimes out of which the first three ones are similar to the classical non-MHD 2-D cylinder wakes while the fourth one is characterized by the vortices evolved from the duct side walls due to the boundary layer separation which strongly disturbs the Kármán vortex street. The flow dynamics and heat transfer rate from the heated channel wall are observed to depend on the imposed magnetic field strength. With increasing magnetic field, the flow becomes stabilized resulting in a degradation in the forced convection heat transfer. A special case at a very high Reynolds number with Ha = 2160 is also considered to show the development of a Kelvin–Helmholtz-type instability that substantially affects the heat transfer rate.

  19. Characteristics of trapped magnetic fields in HTS bulk annuli with various axial spaces for compact NMR magnets

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.B., E-mail: kim@elec.okayama-u.ac.j [Electrical and Electronic Engineering, Okayama University, 3-1-1, Tsushima Naka, Kita-ku, Okayama 700-8530 (Japan); Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139 (United States); Imai, M.; Takano, R.; Kashima, K.; Hahn, S. [Electrical and Electronic Engineering, Okayama University, 3-1-1, Tsushima Naka, Kita-ku, Okayama 700-8530 (Japan); Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139 (United States)

    2010-11-01

    Recently, the performance of high-temperature superconducting (HTS) bulks such as a critical current density, size, and mechanical strength has been improved. In consequence, various applications with HTS bulks such as motors, bearings, and flywheels are being investigated by many research groups; Compact nuclear magnetic resonance (NMR) magnet is one of the new applications after a technique to enhance maximum trapped field of an HTS bulk more than 11.7 T, 500 MHz {sup 1}H NMR frequency, has been developed. This new compact NMR magnet out of HTS bulks is far less expensive than those conventional NMR magnets and expected to be widely used in food and drug industry. In design and manufacture of those compact NMR magnets, the issues of spatial homogeneity and temporal stability of trapped magnetic fields in HTS bulk annuli are very important. In this paper, the characteristics of the trapped magnetic fields in a stack of assembled HTS bulk annuli were investigated with various axial spaces between HTS bulks, experimentally and analytically.

  20. Optical visualisation of the flow around a cylinder in electrolyte under strong axial magnetic field.

    Science.gov (United States)

    Andreev, O.; Kobzev, A.; Kolesnikov, Yu.; Thess, A.

    Flows around obstacles are among the most common problems encountered in the fluid mechanics literature, and cylindrical obstacles definitely received the most extensive attention. The reason for this is that this relatively simple geometry already encompasses most of the important physical effects likely to play a role in flow around more complicated obstacles. This means that understanding the cylinder problem provides relevant insight on a wide variety of problem ranging from aerodynamics, with the flow around a wing or a vehicle, to pollutant dispersion around building, flows in turbines … When the working fluid conducts electricity additional effects are involved. In particular, the presence of a magnetic field tends to homogenise the flow in the direction of the magnetic field lines which leads to strong alterations of the flow patterns known from the classical nonconducting case. This configuration is also a very generic one as Magnetohydrodynamic flows around obstacle also occur in a wide variety of applications: for instance, the space vehicle re-entry problem features the flow of a conducting plasma around an obstacle: [1] and [2] have shown that it could be influenced by a strong magnetic field in order to reduce heat transfer. The cooling blanket of the future nuclear fusion reactor ITER soon to be built in France, features a complex flow of liquid metal in a very high magnetic field (typically 10 T), in which the occurrence of obstacles cannot be avoided.

  1. Field Guide for Designing Human Interaction with Intelligent Systems

    Science.gov (United States)

    Malin, Jane T.; Thronesbery, Carroll G.

    1998-01-01

    The characteristics of this Field Guide approach address the problems of designing innovative software to support user tasks. The requirements for novel software are difficult to specify a priori, because there is not sufficient understanding of how the users' tasks should be supported, and there are not obvious pre-existing design solutions. When the design team is in unfamiliar territory, care must be taken to avoid rushing into detailed design, requirements specification, or implementation of the wrong product. The challenge is to get the right design and requirements in an efficient, cost-effective manner. This document's purpose is to describe the methods we are using to design human interactions with intelligent systems which support Space Shuttle flight controllers in the Mission Control Center at NASA/Johnson Space Center. Although these software systems usually have some intelligent features, the design challenges arise primarily from the innovation needed in the software design. While these methods are tailored to our specific context, they should be extensible, and helpful to designers of human interaction with other types of automated systems. We review the unique features of this context so that you can determine how to apply these methods to your project Throughout this Field Guide, goals of the design methods are discussed. This should help designers understand how a specific method might need to be adapted to the project at hand.

  2. Turbulent transport in 2D collisionless guide field reconnection

    CERN Document Server

    Muñoz, P A; Kilian, P

    2016-01-01

    Transport in collisionless plasmas is usually called anomalous, being due to the interaction between the particles and the self-generated turbulence by their collective interactions. Because of its relevance for astrophysical and space plasmas, we explore the excitation of turbulence in current sheets prone to component- or guide-field reconnection, a process not well understood, yet. We analyze the anomalous transport properties by using 2.5D Particle-in-Cell (PiC) code simulations. We split off the mean, slow variation (in contrast to the fast turbulent fluctuations) of the macroscopic observables and determine the main transport terms of the generalized Ohm's law. We verify our findings by comparing with the independently determined slowing-down rate of the macroscopic currents and with the transport terms obtained by the first order correlations of the turbulent fluctuations. We find that the turbulence is most intense in the "low density" separatrix region of guide-field reconnection. It is excited by st...

  3. Teach Like a Champion Field Guide: A Practical Resource to Make the 49 Techniques Your Own

    Science.gov (United States)

    Lemov, Doug

    2012-01-01

    In his acclaimed book "Teach Like a Champion", Doug Lemov shared 49 essential techniques used by excellent teachers. In his companion Field Guide, he further explores those techniques in a practical guide. With the "Teach Like a Champion Field Guide", teachers will have an indispensable resource that complements their classroom application of…

  4. Turbulent convection in a horizontal duct with strong axial magnetic field

    Science.gov (United States)

    Zhang, Xuan; Zikanov, Oleg

    2014-11-01

    Convection in a horizontal duct with one heated wall is studied computationally. The work is motivated by the concept of a blanket for fusion reactors, according to which liquid metal slowly flows in toroidal ducts aligned with the main component of the magnetic field. We first assume that the magnetic field is sufficiently strong for the flow to be purely two-dimensional and analyze chaotic flow regimes at very high Grashof numbers. Furthermore, three-dimensional perturbations are considered and the relation between the length of the duct and the critical Hartmann number, below which the flow becomes three-dimensional, is determined. Financial support was provided by the US NSF (Grant CBET 1232851).

  5. Axial myopathy

    DEFF Research Database (Denmark)

    Witting, Nanna; Andersen, Linda K; Vissing, John

    2016-01-01

    musculature involvement in the majority of myopathies in which paraspinal musculature was examined. Even in diseases named after a certain pattern of non-axial muscle affection, such as facioscapulohumeral and limb girdle muscular dystrophies, affection of the axial musculature was often severe and early...

  6. THERMAL STRESS FIELD WHEN CRACK ARREST IN AN AXIAL SYMMETRY METAL DIE USING ELECTROMAGNETIC HEATING

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In order to solve the thermal stress field around crack tip in metal die when crack prevention using electromagnetic heating, a metal die with a half-embedded round crack was selected as the study object. The complex function method was used as a basis for the theoretical model of the space crack prevention in metal dies using electromagnetic heating. The crack arrest was accomplished by a pulse current discharge through the inner and outer. The theoretical analysis results show that the temperature around the crack tip rises instantly above the melting point of the metal. Small welded joints are formed at a small sphere near the crack tip inside the metal die by metal melting as a result of the heat concentration effect when the current pulse discharged. The thermal compressive stress field appears around the crack tip at the moment. The research results show that the crack prevention using electromagnetic heating can decrease the stress concentration and forms a compressive stress area around the crack tip, and also prevents the main crack from propagating further, and the goal of crack preventing can be reached.

  7. Cone-guided fast ignition with no imposed magnetic fields

    Directory of Open Access Journals (Sweden)

    Strozzi D.

    2013-11-01

    Full Text Available Simulations are presented of ignition-scale fast ignition targets with the integrated Zuma-Hydra PIC-hydrodynamic capability. We consider a spherical DT fuel assembly with a carbon cone, and an artificially-collimated fast electron source. We study the role of E and B fields and the fast electron energy spectrum. For mono-energetic 1.5 MeV fast electrons, without E and B fields, ignition can be achieved with fast electron energy Efig = 30kJ. This is 3.5× the minimal deposited ignition energy of 8.7 kJ for our fuel density of 450 g/cm3. Including E and B fields with the resistive Ohm's law E = ηJb gives Efig = 20kJ, while using the full Ohm's law gives Efig > 40 kJ. This is due to magnetic self-guiding in the former case, and ∇n ×∇T magnetic fields in the latter. Using a realistic, quasi two-temperature energy spectrum derived from PIC laser-plasma simulations increases Efig to (102, 81, 162 kJ for (no E/B, E = ηJb, full Ohm's law. Such electrons are too energetic to stop in the optimal hot spot depth.

  8. Encke's special perturbation technique associated with the KS regularized variables. I - Satellite motions in the earth's gravitational field with axial symmetry

    Science.gov (United States)

    Awad, Mervat El-Sayed

    1988-10-01

    A special perturbation technique of Encke type associated with the Kustaanheimo-Stiefel (KS) regularized variables is developed for satellite motions in the earth's gravitational field with axial symmetry. Its computational algorithm is of recursive nature and could be applied to any perturbed conic motion, whatever the number of the zonal harmonic coefficients may be. Applications of the algorithm are also included.

  9. Field scale simulation of axial hydrokinetic turbines in a natural marine environment

    Science.gov (United States)

    Chawdhary, Saurabh; Angelidis, Dionysios; Shen, Lian; Sotiropoulos, Fotis

    2016-11-01

    Commercialization of marine and hydrokinetic (MHK) energy technologies is still in the development stage. Existing technologies need fundamental research to enable efficient energy extraction from identified MHK sites. We propose a large eddy simulation (LES)-based framework to investigate the site-specific flow dynamics past MHK arrays in a real-life marine environment. To this end, we use advanced computational tools developed at the Saint Anthony Falls Laboratory (SAFL) to resolve the vast range of scales present in the flow. The new generation unstructured Cartesian flow solver, coupled with a sharp interface immersed boundary method for 3D incompressible flows, is used to numerically investigate New York City's East River, where an array of MHK turbines is to be deployed as part of the Roosevelt Island Tidal Energy (RITE) Project. Multi-resolution simulations on locally refined grids are used to simulate the flow in a section of the East River with detailed river bathymetry and inset turbines at field scale. The results are analyzed in terms of the wake recovery, overall wake dynamics, and the power produced by the turbines. These results will help develop design guidelines for the site-specific turbine array configuration. This work was supported by NSF Grant IIP-1318201.

  10. Turbulent transport in 2D collisionless guide field reconnection

    Science.gov (United States)

    Muñoz, P. A.; Büchner, J.; Kilian, P.

    2017-02-01

    Transport in hot and dilute, i.e., collisionless, astrophysical and space, plasmas is called "anomalous." This transport is due to the interaction between the particles and the self-generated turbulence by their collective interactions. The anomalous transport has very different and not well known properties compared to the transport due to binary collisions, dominant in colder and denser plasmas. Because of its relevance for astrophysical and space plasmas, we explore the excitation of turbulence in current sheets prone to component- or guide-field reconnection, a process not well understood yet. This configuration is typical for stellar coronae, and it is created in the laboratory for which a 2.5D geometry applies. In our analysis, in addition to the immediate vicinity of the X-line, we also include regions outside and near the separatrices. We analyze the anomalous transport properties by using 2.5D Particle-in-Cell code simulations. We split off the mean slow variation (in contrast to the fast turbulent fluctuations) of the macroscopic observables and determine the main transport terms of the generalized Ohm's law. We verify our findings by comparing with the independently determined slowing-down rate of the macroscopic currents (due to a net momentum transfer from particles to waves) and with the transport terms obtained by the first order correlations of the turbulent fluctuations. We find that the turbulence is most intense in the "low density" separatrix region of guide-field reconnection. It is excited by streaming instabilities, is mainly electrostatic and "patchy" in space, and so is the associated anomalous transport. Parts of the energy exchange between turbulence and particles are reversible and quasi-periodic. The remaining irreversible anomalous resistivity can be parametrized by an effective collision rate ranging from the local ion-cyclotron to the lower-hybrid frequency. The contributions to the parallel and the perpendicular (to the magnetic

  11. Geologic field-trip guide to Long Valley Caldera, California

    Science.gov (United States)

    Hildreth, Wes; Fierstein, Judy

    2017-07-26

    This guide to the geology of Long Valley Caldera is presented in four parts: (1) An overview of the volcanic geology; (2) a chronological summary of the principal geologic events; (3) a road log with directions and descriptions for 38 field-trip stops; and (4) a summary of the geophysical unrest since 1978 and discussion of its causes. The sequence of stops is arranged as a four-day excursion for the quadrennial General Assembly of the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI), centered in Portland, Oregon, in August 2017. Most stops, however, are written freestanding, with directions that allow each one to be visited independently, in any order selected.

  12. Field induced by an axial magnetic dipole in the presence of two fused superconducting spheres: Analytic solution

    Science.gov (United States)

    Palaniappan, D.

    2009-04-01

    An exact solution for a magnetostatic boundary value problem involving two fused (overlapping) spheres placed in a field generated by an axial magnetic point dipole is constructed based on the image method. The basic idea is illustrated for two unequal superconducting spheres intersecting with a vertex angle π /2 and the analytical solution for the scalar magnetic potential satisfying the Neumann boundary condition at the surface is derived. The image solution for a dipole-twin-sphere configuration consists of three image dipoles—one inside each sphere and the third inside a pseudo-/virtual sphere—all located at the respective inverse points inside the superconducting two-sphere assembly. The levitation force acting on the two-sphere superconducting surface is also calculated for the overlapping geometry. These exact results can be used as a benchmark for testing numerical algorithms for overlapping spherical superconductors. Our simple approach also offers clues for solving the Neumann boundary value problem for vertex angles π /n, n is an integer, and other related superconducting geometries.

  13. On a two-dimensional mode-matching technique for sound generation and transmission in axial-flow outlet guide vanes

    Science.gov (United States)

    Bouley, Simon; François, Benjamin; Roger, Michel; Posson, Hélène; Moreau, Stéphane

    2017-09-01

    The present work deals with the analytical modeling of two aspects of outlet guide vane aeroacoustics in axial-flow fan and compressor rotor-stator stages. The first addressed mechanism is the downstream transmission of rotor noise through the outlet guide vanes, the second one is the sound generation by the impingement of the rotor wakes on the vanes. The elementary prescribed excitation of the stator is an acoustic wave in the first case and a hydrodynamic gust in the second case. The solution for the response of the stator is derived using the same unified approach in both cases, within the scope of a linearized and compressible inviscid theory. It is provided by a mode-matching technique: modal expressions are written in the various sub-domains upstream and downstream of the stator as well as inside the inter-vane channels, and matched according to the conservation laws of fluid dynamics. This quite simple approach is uniformly valid in the whole range of subsonic Mach numbers and frequencies. It is presented for a two-dimensional rectilinear-cascade of zero-staggered flat-plate vanes and completed by the implementation of a Kutta condition. It is then validated in sound generation and transmission test cases by comparing with a previously reported model based on the Wiener-Hopf technique and with reference numerical simulations. Finally it is used to analyze the tonal rotor-stator interaction noise in a typical low-speed fan architecture. The interest of the mode-matching technique is that it could be easily transposed to a three-dimensional annular cascade in cylindrical coordinates in a future work. This makes it an attractive alternative to the classical strip-theory approach.

  14. Geologic field-trip guide to the Lassen segment of the Cascades Arc, northern California

    Science.gov (United States)

    Clynne, Michael A.; Muffler, L. J. Patrick

    2017-08-17

    This field-trip guide provides an overview of Quaternary volcanism in and around Lassen Volcanic National Park, California, emphasizing the stratigraphy of the Lassen Volcanic Center. The guide is designed to be self-guided and to focus on geologic features and stratigraphy that can be seen easily from the road network.

  15. Crustal magnetization and the subseafloor structure of the ASHES vent field, Axial Seamount, Juan de Fuca Ridge: Implications for the investigation of hydrothermal sites

    Science.gov (United States)

    Caratori Tontini, Fabio; Crone, Timothy J.; Ronde, Cornel E. J.; Fornari, Daniel J.; Kinsey, James C.; Mittelstaedt, Eric; Tivey, Maurice

    2016-06-01

    High-resolution geophysical data have been collected using the Autonomous Underwater Vehicle (AUV) Sentry over the ASHES (Axial Seamount Hydrothermal Emission Study) high-temperature (~348°C) vent field at Axial Seamount, on the Juan de Fuca Ridge. Multiple surveys were performed on a 3-D grid at different altitudes above the seafloor, providing an unprecedented view of magnetic data resolution as a function of altitude above the seafloor. Magnetic data derived near the seafloor show that the ASHES field is characterized by a zone of low magnetization, which can be explained by hydrothermal alteration of the host volcanic rocks. Surface manifestations of hydrothermal activity at the ASHES vent field are likely controlled by a combination of local faults and fractures and different lava morphologies near the seafloor. Three-dimensional inversion of the magnetic data provides evidence of a vertical, pipe-like upflow zone of the hydrothermal fluids with a vertical extent of ~100 m.

  16. Generation of Helical and Axial Magnetic Fields by the Relativistic Laser Pulses in Under-dense Plasma: Three-Dimensional Particle-in-Cell Simulation

    Institute of Scientific and Technical Information of China (English)

    郑春阳; 朱少平; 贺贤土

    2002-01-01

    The quasi-static magnetic fields created in the interaction of relativistic laser pulses with under-dense plasmashave been investigated by three-dimensional particle-in-cell simulation. The relativistic ponderomotive force candrive an intense electron current in the laser propagation direction, which is responsible for the generation ofa helical magnetic field. The axial magnetic field results from a difference beat of wave-wave, which drives asolenoidal current. In particular, the physical significance of the kinetic model for the generation of the axialmagnetic field is discussed.

  17. A Field Guide to Outdoor Learning in Powell County, Biome Descriptions, Field Activities, Field Sites.

    Science.gov (United States)

    Powell County High School, Deer Lodge, MT.

    Serving as a guide to the outdoor areas of Powell County, Montana, and the surrounding area, this resource book is useful for teachers who wish to explore the out-of-doors with their students, particularly those interested in nature studies. Its aim is to produce a citizenry that is knowledgeable concerning the biophysical environment and its…

  18. Electron cyclotron maser instability (ECMI in strong magnetic guide field reconnection

    Directory of Open Access Journals (Sweden)

    R. A. Treumann

    2017-08-01

    Full Text Available The ECMI model of electromagnetic radiation from electron holes is shown to be applicable to spontaneous magnetic reconnection. We apply it to reconnection in strong current-aligned magnetic guide fields. Such guide fields participate only passively in reconnection, which occurs in the antiparallel components to both sides of the guide-field-aligned current sheets with current carried by kinetic Alfvén waves. Reconnection generates long (the order of hundreds of electron inertial scales electron exhaust regions at the reconnection site X point, which are extended perpendicular to the current and the guide fields. Exhausts contain a strongly density-depleted hot electron component and have properties similar to electron holes. Exhaust electron momentum space distributions are highly deformed, exhibiting steep gradients transverse to both the reconnecting and guide fields. Such properties suggest application of the ECMI mechanism with the fundamental ECMI X-mode emission beneath the nonrelativistic guide field cyclotron frequency in localized source regions. An outline of the mechanism and its prospects is given. Potential applications are the kilometric radiation (AKR in auroral physics, solar radio emissions during flares, planetary emissions and astrophysical scenarios (radiation from stars and compact objects involving the presence of strong magnetic fields and field-aligned currents. Drift of the exhausts along the guide field maps the local field and plasma properties. Escape of radiation from the exhaust and radiation source region still poses a problem. The mechanism can be studied in 2-D particle simulations of strong guide field reconnection which favours 2-D, mapping the deformation of the electron distribution perpendicular to the guide field, and using it in the numerical calculation of the ECMI growth rate. The mechanism suggests also that reconnection in general may become a source of the ECMI with or without guide fields. This is

  19. Congenital Heart Defects in Adults : A Field Guide for Cardiologists.

    Science.gov (United States)

    Romfh, Anitra; Pluchinotta, Francesca Romana; Porayette, Prashob; Valente, Anne Marie; Sanders, Stephen P

    2012-06-15

    Advances in cardiology and cardiac surgery allow a large proportion of patients with congenital heart defects to survive into adulthood. These patients frequently develop complications characteristic of the defect or its treatment. Consequently, adult cardiologists participating in the care of these patients need a working knowledge of the more common defects. Occasionally, patients with congenital heart defects such as atrial septal defect, Ebstein anomaly or physiologically corrected transposition of the great arteries present for the first time in adulthood. More often patients previously treated in pediatric cardiology centers have transitioned to adult congenital heart disease centers for ongoing care. Some of the more important defects in this category are tetralogy of Fallot, transposition of the great arteries, functionally single ventricle defects, and coarctation. Through this field guide, we provide an overview of the anatomy of selected defects commonly seen in an adult congenital practice using pathology specimens and clinical imaging studies. In addition, we describe the physiology, clinical presentation to the adult cardiologist, possible complications, treatment options, and outcomes.

  20. Nonlinear evolution of electron shear flow instabilities in the presence of an external guide magnetic field

    CERN Document Server

    Jain, Neeraj

    2016-01-01

    The dissipation mechanism by which the magnetic field reconnects in the presence of an external (guide) magnetic field in the direction of the main current is not well understood. In thin electron current sheets (ECS) (thickness ~ an electron inertial length) formed in collisionless magnetic reconnection, electron shear flow instabilities (ESFI) are potential candidates for providing an anomalous dissipation mechanism which can break the frozen-in condition of the magnetic field affecting the structure and rate of reconnection. We investigate the evolution of ESFI in guide field magnetic reconnection. The properties of the resulting plasma turbulence and their dependence on the strength of the guide field are studied. Utilizing 3-D electron-magnetohydrodynamic simulations of ECS we show that, unlike the case of ECS self-consistently embedded in anti-parallel magnetic fields, the evolution of thin ECS in the presence of a guide field (equal to the asymptotic value of the reconnecting magnetic field or larger) ...

  1. Field Guide to the Geology of Parts of the Appalachian Highlands and Adjacent Interior Plains.

    Science.gov (United States)

    McKenzie, Garry D.; Utgard, Russell O.

    This field guide is the basis for a five-day, 1000-mile trip through six states and six geomorphic provinces. The trip and the pre- and post-trip exercises included in the guide constitute a three credit course at The Ohio State University entitled "Field Geology for Science Teachers." The purpose of the trip is to study the regional geology,…

  2. CASASTART Field Guide: A Proven Youth Development Strategy That Prevents Substance Abuse and Builds Communities.

    Science.gov (United States)

    Columbia Univ., New York, NY. National Center on Addiction and Substance Abuse.

    The CASASTART Field Guide is the result of 9 years of research, experience, and evaluation in cities where the program has enhanced the capacity of communities to serve high-risk youth through formal partnerships that reduce their use of drugs and alcohol and promote their positive development. The Field Guide is a practical "how to" manual on…

  3. On the Electron Agyrotropy during Rapid Asymmetric Magnetic Island Coalescence in Presence of a Guide Field

    CERN Document Server

    Cazzola, Emanuele; Goldman, Martin V; Newman, David L; Markidis, Stefano; Lapenta, Giovanni

    2016-01-01

    We present an analysis of the properties of the electron velocity distribution during island coalescence in asymmetric reconnection with and without guide field. In a previous study, three main domains were identified, in the case without guide field, as X-, D- and M-regions featuring different reconnection evolutions {Cazzola et al. 2015). These regions are also identified here in the case with guide field. We study the departure from isotropic and gyrotropic behavior by means of different robust detection algorithms proposed in the literature. While in the case without guide field these metrics show an overall agreement, when the guide field is present a discrepancy in the agyrotropy within some relevant regions is observed, such as at the separatrices and inside magnetic islands. Moreover, in light of the new observations from the Multiscale MagnetoSpheric mission, an analysis of the electron velocity phase-space in these domains is presented.

  4. A Study of the Conditions of Maximum Filtration Efficiency for a HGMF-Axial Magnetic Filter Cell With Bounded Flow Field

    OpenAIRE

    Badescu, V.; Murariu, V.; Rotariu, O; Rezlescu, N.

    1996-01-01

    The theory of magnetic particles′ capture on a HGMF-axial magnetic filter cell with bounded flow field is presented. The equations of particle motion for both potential and laminar flow are obtained. By analytical solving of these equations, the trajectories of particles are established. The flow velocity of the fluid suspension for the case of potential flow is set equal with the velocity averaged across the tube section for the laminar flow. Thus, it is possible to make a comparison between...

  5. Grasses and Grasslike Plants of Utah, A Field Guide

    OpenAIRE

    Pratt, Mindy

    2011-01-01

    This guide is meant to serve as a help in identifying many of the grasses and grass-like plants common to the rangelands, forests, and farmlands of Utah. It is not an exhaustive guide to the plants contained herein, nor is it a comprehensive summary of all the grasses and grass-like plants in Utah.

  6. INVESTIGATION OF VISCOUS FLOW FIELD AROUND AN APPENDED REVOLUTION BODY WITH GUIDE VANE PROPELLER

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A RANS solver is presented to numerically simulate the viscous wake of an appended revolution body with guide vane propeller at the Reynolds number 107. The k-ε turbulence model together with wall function is used. The resulting finite difference equations are solved by SIMPLEC and ADI. The technique of rising up the bottom surface is presented to overcome radial contraction problem in Cartesian coordinate system. The three-dimensional body forces are separately adopted to model the affection of the guide vane and propeller. The detailed flow characteristics,especially the counter-swirl component generated by the guide vane in the propeller inflow, are numerically seized successfully. Compared with the experimental data, The computational axial velocity on the propeller disk plane comes up to engineering requirement.

  7. Variation-Aware Design of Custom Integrated Circuits A Hands-on Field Guide A Hands-on Field Guide

    CERN Document Server

    McConaghy, Trent; Dyck, Jeffrey; Gupta, Amit

    2013-01-01

    This book targets custom IC designers who are encountering variation issues in their designs, especially for modern process nodes at 45nm and below, such as statistical process variations, environmental variations, and layout effects.  The authors have created a field guide to show how to handle variation proactively, and to understand the benefits of doing so. Readers facing variation challenges in their memory, standard cell, analog/RF, and custom digital designs will find easy-to-read, pragmatic solutions.   Reviews the most important concepts in variation-aware design, including types of variables and variation, useful variation-aware design terminology, and an overview and comparison of high-level design flows. Describes and compares a suite of approaches and flows for PVT corner-driven design and verification. Presents Fast PVT, a novel, confidence-driven global optimization technique for PVT corner extraction and verification that is both rapid and reliable. Presents a visually-oriented overview of ...

  8. Self-similarity in radial Walsh filters and axial intensity distributions in the far-field diffraction pattern.

    Science.gov (United States)

    Mukherjee, P; Hazra, L N

    2014-02-01

    Pupil plane filtering by radial Walsh filters is a convenient technique for tailoring the axial intensity distribution near the focal plane of a rotationally symmetric imaging system. Radial Walsh filters, derived from radial Walsh functions, form a set of orthogonal phase filters that take on values either 0 or π phase, corresponding to +1 or -1 values of the radial Walsh functions over prespecified annular regions of the circular filter. Order of these filters is given by the number of zero-crossings, or equivalently phase transitions within the domain over which the set is defined. In general, radial Walsh filters are binary phase zone plates, each of them demonstrating distinct focusing characteristics. The set of radial Walsh filters can be classified into distinct groups, where the members of each group possess self-similar structures. Self-similarity can also be observed in the corresponding axial intensity distributions. These observations provide valuable clues in tackling the inverse problem of synthesis of phase filter in accordance with prespecified axial intensity distributions. This paper reports our observations on self-similarity in radial Walsh filters of various orders and corresponding axial intensity distributions.

  9. The differential equations defining deflection of particles of ion beam from axial trajectory in electric and magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Baisanov, O.A. [Military Institute of Air Defense Forces, Aktobe (Kazakhstan); Doskeyev, G.A.; Doskeyev, T.G. [Aktobe State University named after K. Zhubanov, Aktobe (Kazakhstan); Spivak-Lavrov, I.F., E-mail: spivakif@rambler.ru [Aktobe State University named after K. Zhubanov, Aktobe (Kazakhstan)

    2011-07-21

    The exact differential equations defining deviations of the paths of charged particles from the axial trajectory are derived in curvilinear coordinates. These equations are in a form suited for carrying out relativistically correct numerical calculations of the dynamics of charged particle beams.

  10. MMS observations of oblique small-scale magnetopause flux ropes near the ion diffusion region during weak guide-field reconnection

    Science.gov (United States)

    Teh, W.-L.; Denton, R. E.; Sonnerup, B. U. Ã.-.; Pollock, C.

    2017-07-01

    We report Magnetospheric Multiscale observations of a series of five small-scale magnetic flux ropes (FR1-5) embedded in the southward reconnection outflow during a magnetopause reconnection event with a small guide field ( 2.2 nT). These small-scale flux ropes (diameter 3-11 ion inertial lengths) are found inside or near the ion diffusion region on the magnetosheath side of the magnetopause boundary layer. A consistent result for determining the axis orientation of the flux ropes is achieved using two different methods, namely, minimum variance analysis of the axial electric field and constrained minimum variance analysis of the magnetic field. Our results show that the axes of these flux ropes (FR1-4) form a large angle (53°-66°) to the guide-field orientation and are tilted toward the direction of the reconnecting field. These observations provide evidence for the presence of oblique ion-scale flux ropes near the ion diffusion region during reconnection with a weak guide field. Our findings are similar to those obtained from a 3-D kinetic simulation of turbulent reconnection.

  11. The Scaling of Electron Acceleration in Magnetic Reconnection with a Guide Field

    CERN Document Server

    Dahlin, J T; Swisdak, M

    2016-01-01

    Kinetic simulations of two-dimensional collisionless magnetic reconnection with a guide field reveal disparate behavior in the weak and strong guide field regimes. In systems where the guide field is smaller than the reconnecting component, the dominant electron accelerator is a Fermi-type mechanism that preferentially energizes the most energetic particles. In the strong guide field regime, however, the field-line contraction that drives Fermi reflection becomes weak. Instead, parallel electric fields ($E_\\parallel$) are primarily responsible for driving electron heating but are ineffective in driving the energetic component of the spectrum. This is due to the the weaker energy scaling of acceleration by $E_\\parallel$ compared with Fermi reflection. These results have important implications for understanding electron acceleration in solar flares and reconnection-driven dissipation in astrophysical turbulence.

  12. Computational Cavitation Flows at Inception and Light Stages on an Axial-Flow Pump Blade and in a Cage-Guided Control Valve

    Institute of Scientific and Technical Information of China (English)

    Sumio SAITO; Masahiro SHIBATA; Hideo FUKAE; Eisuke OUTA

    2007-01-01

    Cavitation flows induced around an axial-flow pump blade and inside a high pressure cage-type valve are simulated by a two-dimensional unsteady Navier-Stokes analysis with the simplest treatment of bubble dynamics. The fluid is assumed as a continuum of homogeneous dispersed mixture of water and vapor nuclei. The analysis is aimed to capture transient stages with high amplitude pressure change during the birth and collapse of the bubble especially at the stage of cavitation inception. By the pump blade analysis, in which the field pressure is moderate,cavitation number of the inception and locations of developed cavitation are found to agree with experimental results in a wide flow range between high incidence and negative incidence. In the valve flow analysis, in which the water pressure of 5MPa is reduced to 2MPa, pressure change responding to the bubble collapse between the vapor pressure lower than 1 KPa and the extreme pressure of higher than 104 KPa is captured through a stable computation. Location of the inception bubble and pressure force to the valve plug is found agree well with the respective experimental features.

  13. Effects of a Guide Field on the Larmor Electric Field and Upstream Electron Temperature Anisotropy in Collisionless Asymmetric Magnetic Reconnection

    Science.gov (United States)

    Ek-In, Surapat; Malakit, Kittipat; Ruffolo, David; Shay, Michael A.; Cassak, Paul A.

    2017-08-01

    We perform the first study of the properties of the Larmor electric field (LEF) in collisionless asymmetric magnetic reconnection in the presence of an out-of-plane (guide) magnetic field for different sets of representative upstream parameters at Earth’s dayside magnetopause with an ion temperature greater than the electron temperature (the ion-to-electron temperature ratio fixed at 2) using two-dimensional particle-in-cell simulations. We show that the LEF does persist in the presence of a guide field. We study how the LEF thickness and strength change as a function of guide field and the magnetospheric temperature and reconnecting magnetic field strength. We find that the thickness of the LEF structure decreases, while its magnitude increases when a guide field is added to the reconnecting magnetic field. The added guide field makes the Larmor radius smaller, so the scaling with the magnetospheric ion Larmor radius is similar to that reported for the case without a guide field. Note, however, that the physics causing the LEF is not well understood, so future work in other parameter regimes is needed to fully predict the LEF for arbitrary conditions. We also find that a previously reported upstream electron temperature anisotropy arises in the vicinity of the LEF region both with and without a guide field. We argue that the generation of the anisotropy is linked to the existence of the LEF. The LEF can be used in combination with the electron temperature anisotropy as a signature to effectively identify dayside reconnection sites in observations.

  14. Guiding-center Hamiltonian figure-8 particles in axisymmetric field-reversed configurations

    Energy Technology Data Exchange (ETDEWEB)

    Mynick, H.E.

    1979-09-01

    The guiding-center Hamiltonian K is derived for so-called figure-8 particles which are present in field-reversed mirror configurations, using a formalism developed previously. For such particles, the gyro-orbit cannot be approximated by a circle, and standard approaches to guiding-center theory are thus totally inapplicable. K manifests this intrinsic difference by a quite different dependence on the gyroaction, and by familiar effects such as mirroring and magnetic-gradient drifts being controlled by the radial derivative of the magnetic field strength B at the point of field-reversal, rather than by B itself, as occurs in standard guiding-center theory.

  15. Cultural Transmission in Three Societies: Testing a Systems-Based Field Guide.

    Science.gov (United States)

    Dobbert, Marion Lundy; And Others

    1984-01-01

    Reports on: (1) the formulation of a holistic, systems-based theory of cultural transmission; (2) a field guide developed for gathering the precise data needed to test the theory; and (3) a pilot study, involving the collection and analysis of data about six- to 12-year-old Americans, Israelis, and Mexicans, to test both guide and theory. (CMG)

  16. Interaction between Gaming and Multistage Guiding Strategies on Students' Field Trip Mobile Learning Performance and Motivation

    Science.gov (United States)

    Chen, Chih-Hung; Liu, Guan-Zhi; Hwang, Gwo-Jen

    2016-01-01

    In this study, an integrated gaming and multistage guiding approach was proposed for conducting in-field mobile learning activities. A mobile learning system was developed based on the proposed approach. To investigate the interaction between the gaming and guiding strategies on students' learning performance and motivation, a 2 × 2 experiment was…

  17. Interaction between Gaming and Multistage Guiding Strategies on Students' Field Trip Mobile Learning Performance and Motivation

    Science.gov (United States)

    Chen, Chih-Hung; Liu, Guan-Zhi; Hwang, Gwo-Jen

    2016-01-01

    In this study, an integrated gaming and multistage guiding approach was proposed for conducting in-field mobile learning activities. A mobile learning system was developed based on the proposed approach. To investigate the interaction between the gaming and guiding strategies on students' learning performance and motivation, a 2 × 2 experiment was…

  18. A Field Guide for Change Facilitators Working with Low-Performing Schools

    Science.gov (United States)

    Miller, Bruce; Campbell, Jean

    2005-01-01

    The Field Guide for Change Facilitators Working With Low-Performing Schools was written to assist those working with schools in the improvement process, especially low-performing ones. As a primer for change facilitators, this research-based guide is arranged in sections so that the user can easily find needed information on specific topics.…

  19. Field Guide for the Biological Control of Weeds in Eastern North America

    Science.gov (United States)

    This field guide provides information about invasive weeds in Eastern North America and their associated biological control agents. Information about plant identification and ecology is provided through photographs and descriptions for each weed species. The guide also includes photographs of the bi...

  20. Axial-flow pump hydraulic analysis and experiment under different swept-angles of guide vane%不同导叶叶片掠角下轴流泵段水力特性分析及试验

    Institute of Scientific and Technical Information of China (English)

    石丽建; 汤方平; 周捍珑; 涂恋恋; 谢荣盛

    2015-01-01

    Based on the computational fluid dynamics (CFD) software, this paper studied the influence of the post guide vane under different sweep angles on the hydraulic performance of the axial flow pump device. The purpose was that through changing the angle of blade forward and back sweeping, the post guide vane could as much as possibly recover the velocity circulation of the impeller outlet, at the same time, the hydraulic loss of the guide vane could be not too large, so as to improve the hydraulic characteristics of the axial flow pump device. This paper used the Turbo-Grid software to build the model and carry out the mesh division of the post guide vane and the impeller, used the Pro/E software to build the models of the inlet straight pipe with water-guiding cone and the standard 60°outlet pipe, and then used the ICEM to carry out the structured-grid division. Then, the hydraulic property of the axial flow pump device was analyzed through the CFX software. There were 6 different post guide vane sweeping schemes, which were forward sweep 24°, forward sweep 16°, forward sweep 8°, 0°, back sweep 8°and back sweep 16°. Numerical simulation of the axial flow pump device adopted the standardk-ε model, and each sweeping scheme of post guide vane had 8 flow points including 280, 300, 320, 340, 360, 380, 400 and 420 L/s. The influence of different post guide vane sweeping angles on the energy characteristics of the axial flow pump was analyzed under the design condition and the non-design condition. Then the hydraulic loss of the post guide vane and the outlet pipe was calculated and analyzed. Finally, the experimental study of the energy performance of the axial flow pump device was carried out. The results showed that, the test performance curve trend was consistent with the numerical simulation; the flow-head curve showed a little deviation under small flow, other parts fitted well, and the flow-efficiency curve did not fit so well, but the error between the test

  1. The Onset of Ion Heating During Magnetic Reconnection with a Strong Guide Field

    CERN Document Server

    Drake, J F

    2014-01-01

    The onset of the acceleration of ions during magnetic reconnection is explored via particle-in-cell simulations in the limit of a strong ambient guide field that self-consistently and simultaneously follow the motions of protons and $\\alpha$ particles. Heating parallel to the local magnetic field during reconnection with a guide field is strongly reduced compared with the reconnection of anti-parallel magnetic fields. The dominant heating of thermal ions during guide field reconnection results from pickup behavior of ions during their entry into reconnection exhausts and dominantly produces heating perpendicular rather than parallel to the local magnetic field. Pickup behavior requires that the ion transit time across the exhaust boundary (with a transverse scale of the order of the ion sound Larmor radius) be short compared with the ion cyclotron period. This translates into a threshold in the strength of reconnecting magnetic field that favors the heating of ions with high mass-to-charge. A simulation with ...

  2. Continuous quantum phase transitions in the one-dimensional spin-1/2 axial next-nearest-neighbour Ising model in two orthogonal magnetic fields

    Indian Academy of Sciences (India)

    Kunle Adegoke; Helmut Büttner

    2010-02-01

    We have investigated the one-dimensional spin-1/2 axial next-nearest-neighbour Ising (ANNNI) model in two orthogonal magnetic fields at zero temperature. There are four different possible ground state configurations for the ANNNI model in a longitudinal field, in the thermodynamic limit. The inclusion of a transverse field introduces quantum fluctuations which destroy the existing spin order along certain critical lines. The effects of the fluctuations in three of the four ordered regions were investigated using the finite-size scaling technique. The phase boundaries of the ANNNI model in two orthogonal magnetic fields were thus determined numerically. For certain limits of the Hamiltonian we compared the obtained results with the existing literature and our results were in good agreement with the results in the existing literature.

  3. A Field Guide to Heidegger: Understanding "The Question Concerning Technology"

    Science.gov (United States)

    Waddington, David I.

    2005-01-01

    This essay serves as a guide for scholars, especially those in education, who want to gain a better understanding of Heidegger's essay, "The Question Concerning Technology". The paper has three sections: an interpretive summary, a critical commentary, and some remarks on Heidegger scholarship in education. Since Heidegger's writing style is rather…

  4. Suitability for field service in 4 breeds of guide dogs

    NARCIS (Netherlands)

    Ennik, E.; Liinamo, A.E.; Leighton, E.; Arendonk, van J.A.M.

    2006-01-01

    This study examines the relative importance of a longer than normal 4-month training period, or being ¿passed back¿ from the original training class to join a class in which dogs are at an earlier stage of their training, on the overall probability that a dog entering guide dog training will ultimat

  5. Special Concretes and Field Problems; Instructor's Guide; Pilot Program Edition.

    Science.gov (United States)

    Portland Cement Association, Cleveland, OH.

    This guide, prepared for a 2-year program in junior colleges and technical institutes, is designed for a national program to train persons for employment as technicians in the cement and concrete industries. Included are 48 session oultines divided into four units of study. Each unit contains session objectives and outlines, presentation outlines,…

  6. Illustrated field guide to the Lahontan Valley wetlands flora, Churchill County, Nevada

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The illustrated field guide to wetland and adjacent upland (transitional) plants has been designed to aid the layperson in identification of the more common species...

  7. Aerobic Biodegradation of Oily Wastes: A Field Guide For Federal On-scene Coordinators

    Science.gov (United States)

    Intentionally limited in scope to best serve the requirements of the Region 6 Oil Program, this field guide consists of three parts complemented by appendices. Helps evaluate environment and consider factors, existing regulations/policies, operation issues

  8. Electronic Field Guides and User Communities in the Eco-informatics Revolution

    Directory of Open Access Journals (Sweden)

    R. D. Stevenson

    2003-07-01

    Full Text Available The recognition that taxonomy is central to the conservation of biodiversity has reestablished the critical role of taxonomy in biology. However, many of the tools taxonomists produce for the identification and characterization of species, e.g., dichotomous keys, have been difficult to use and largely ignored by the general public in favor of field guides, which are essentially browsable picture guides. We review the role of field guides in species identification and discuss the application of a host of digital technologies to produce user-friendly tools for identification that are likely to greatly enhance species identification in the field by nonspecialists. We suggest that wider adoption of the citizen science model and the use of electronic field guides will enhance public understanding and participation in biodiversity monitoring.

  9. A3-D Numerical Optimization Design Method and Its Application in Axial Fans with Outlet Guide Vanes%轴流风机后导叶三维数值优化设计方法及其应用

    Institute of Scientific and Technical Information of China (English)

    孟丽; 林丽华; 吴海英; 陈永宁; 何海江; 陶中兰; 李嵩

    2014-01-01

    基于轴流风机安装后导叶能明显改善性能,但用目前使用的二维理想的工程方法无法设计良好导叶,必须通过大量后导叶安装角试验,才能改进使用。本文提出轴流风机后导叶三维数值优化设计方法,并用于一个商用风机,设计工况全压和全压效率均提高13%,有很好的变工况性能;本文还对比了用传统工程方法设计的后导叶的性能。%The performance of an axial flow fan can be obviously improved after installing outlet guide vanes. But the commonly used 2-D ideal engineering method can’t be applied to design the good outlet guide vanes. After that a lot of experiments about the installing angle of outlet guide vane must be carried out in order to improve the designed vanes. In this paper, a 3-D numerical optimization design method of axial flow fans with outlet guide vanes is presented and used to a commercial fan. The total pressure and its efficiency are improved about 13% at the design operation and the performances of the off-design operation are also obviously improved. Moreover, the performance of the outlet guide vanes designed by the traditional engineering method is also compared with the presented one in the paper.

  10. Effects of Exit Guide Vane on Performance of Axial-flow Pump System%后置导叶对立式轴流泵装置性能影响

    Institute of Scientific and Technical Information of China (English)

    冯俊; 郑源; 罗欣

    2012-01-01

    为深入研究后置导叶对轴流泵装置性能的影响,结合南水北调北坍泵站模型机组试验,利用Gambit软件,基于雷诺时均Navier-Stokes方程,选用S-A湍流模型与SIMPLEC算法对模型泵进行数值模拟.对比模拟结果与试验结果的外特性,并观察其内流场特性,发现在无导叶时叶轮出水后方区域流动紊乱,流线出现明显的旋转,安装导叶后较好地改善了轴流泵的内流态,有助于提高轴流泵的做功能力.%For further study on the effects of exit guide vane on performance of axial-flow pump,numerical and exper imental methods are both adopted. Based on the Reynolds averaged Navier-Stokes equation,the turbulence model and SIMPLEC algorithm in software Gambit are chosen to simulate model pump of Beitan station in South-to-North water di version projrct. Comparing numerical simulation results with experimental results and observing internal flow characteris tics of axial-flow pump,it can be drawn a conclusion that the water in outlet passage flow appears turbulence and its stre amline has obvious rotation without guide vane; while the guide vane can improve flow pattern and increase efficiency of axial-flow pump.

  11. High School/Preschool Partnership Program: Administrative Guide [and] Curriculum Guide. Field Test Edition.

    Science.gov (United States)

    Pinellas County School Board, Clearwater, FL.

    An administrative and curriculum guide are presented for the High School/Preschool Partnership Program in which high school students gain experience with handicapped preschoolers in a mainstreamed setting. The program is intended to expand services to high schoolers (parenting skills and career skills) as well as preschoolers. The administrative…

  12. FEA modeling of effect of axial feeding velocity on strain field of rotary swaging process of pure magnesium

    Institute of Scientific and Technical Information of China (English)

    RONG Li; NIE Zuo-ren; ZUO Tie-yong

    2006-01-01

    A coupled thermal-mechanical model of the rotary swaging of pure magnesium was developed using the general finite-element software program MSC/Marc to visualize the effect of axial feeding velocity on the rotary swaging process. The radial displacement occurring in one pulse impact increases in proportion to axial feeding velocity (vax). When the other processing parameters are fixed, the surface roughness of the swaged bar increases with vax and is in parabolic relation with vax. There exists a minimum velocity vax, min below which the decrease of vax will no longer improve the surface roughness. Under the technological conditions of this simulation, when the finial diameter d=6.6 mm, vax, min=1.82 m/min, and when d=7.0 mm, vax, min=1.83 m/min. If Ra=3.2 is required for the end product, then vax, max=6.02 m/min is gotten for d=6.6 mm and vax, max=7.05 m/min for d=7.0mm. The increase of vax has no notable influence on strain distribution along radial direction. The errors between the experimental and simulated height of the spiral spine-like ridges are below 8.0%.

  13. Evaluation of the performance and flow in an axial compressor

    Science.gov (United States)

    Waddell, J. L.

    1982-10-01

    An experimental evaluation of the axial compressor test rig with one stage of symmetric blading was conducted to determine its suitability for studies of tip clearance effects. Measurements were made of performance parameters and internal flow fields. The configuration tested was found to be unsuitable due to poor flow from the inlet guide vanes, particularly near the tip region. Secondary flows and flaws in construction of the guide vanes were suggested as probable causes. Recommendations were made for a program to resolve the problem.

  14. A simple method for assessment and minimization of errors in determination of electrophoretic or electroosmotic mobilities and velocities associated with the axial electric field distortion.

    Science.gov (United States)

    Nowak, Paweł Mateusz; Woźniakiewicz, Michał; Kościelniak, Paweł

    2015-12-01

    It is commonly accepted that the modern CE instruments equipped with efficient cooling system enable accurate determination of electrophoretic or electroosmotic mobilities. It is also often assumed that velocity of migration in a given buffer is constant throughout the capillary length. It is simultaneously neglected that the noncooled parts of capillary produce extensive Joule heating leading to an axial electric field distortion, which contributes to a difference between the effective and nominal electric field potentials and between velocities in the cooled and noncooled parts of capillary. This simplification introduces systematic errors, which so far were however not investigated experimentally. There was also no method proposed for their elimination. We show a simple and fast method allowing for estimation and elimination of these errors that is based on combination of a long-end and short-end injections. We use it to study the effects caused by variation of temperature, electric field, capillary length, and pH.

  15. Mode field expansion in index-guiding microstructured optical fibers

    Science.gov (United States)

    Sharma, Dinesh Kumar; Sharma, Anurag

    2013-05-01

    The mode-field expander (MFE) is a microstructured optical fiber (MOF) based device that enlarges the modal field distribution and can couple light from large mode area (LMA) fibers into small core fibers or vice-versa and other optical waveguides. Using our earlier developed analytical field model, we studied the mode-field expansion in MOFs having triangular lattice, and low-loss splicing of MOFs to standard single-mode fibers (SMFs), based on the controlled all airhole collapse method, which leads to an optimum mode-field match at the joint interface of the MOF-SMF. Comparisons with available experimental and simulation results have also been included.

  16. Particle-in-Cell Simulations of Collisionless Magnetic Reconnection with a Non-Uniform Guide Field

    CERN Document Server

    Wilson, Fiona; Hesse, Michael; Harrison, Michael G; Stark, Craig R

    2015-01-01

    Results are presented of a first study of collisionless magnetic reconnection starting from a recently found exact nonlinear force-free Vlasov-Maxwell equilibrium. The initial state has a Harris sheet magnetic field profile in one direction and a non-uniform guide field in a second direction, resulting in a spatially constant magnetic field strength as well as a constant initial plasma density and plasma pressure. It is found that the reconnection process initially resembles guide field reconnection, but that a gradual transition to anti-parallel reconnection happens as the system evolves. The time evolution of a number of plasma parameters is investigated, and the results are compared with simulations starting from a Harris sheet equilibrium and a Harris sheet plus constant guide field equilibrium.

  17. 轴流泵水力模型内部流场数值模拟%Numerical simulation of internal flow field in hydraulic model of axial-flow pump

    Institute of Scientific and Technical Information of China (English)

    齐学义; 汪玮华; 郝连松

    2012-01-01

    Based on the Reynolds time-averaged Navier-Stokes equations with turbulence mode, by using SIMPLEC algorithm to make pressure-velocity coupling, and by using the implicit different format with second-order accuracy, the stationary 3-D turbulent flow in axial-flow pump was numerically simulated and the velocity vectors, static pressure contours, and other flow informations were obtained. The simulation result showed that the flow field distribution and flow form were better in general in design condition, but a local low pressure area occurred at the inlet of impeller blade back near the wheel rim and the load on the outer wall of guide vane was large, indicating that it would be necessary to improve the axial-flow pump model and pump performance.%基于Reynolds时均N-S方程,采用标准k-ε湍流模型,压力、速度耦合使用SIMPLEC算法,离散采用具有二阶精度的隐式格式差分,对轴流泵过流部件内部流场进行三维定常湍流数值模拟,得到泵内流动的速度和压力矢量分布图,以及其他一些流动的信息.数值模拟结果表明,设计工况下的流场分布和流态总体较好,但叶轮叶片背面进口靠近轮缘处出现局部低压,导叶外壁区域负荷大,说明该轴流泵水力模型还有进一步改进和对其性能进一步提高的必要.

  18. Field Guide to Marine Ecology of Kenyan Coast.

    OpenAIRE

    2000-01-01

    This guide introduces you to a model of Kenyan coast: from sandy shore across a lagoon of shallow water with sea grass and coral garden, out to the flinging reef where the waves break and the coral rises like a wall from the depths of the ocean. The beach and lagoon are in a marine park where shells, plants, fish and other marine life is protected. In the marine ecosystem here there are 6 habitats, which have their own plants and animals that adapted to the particular environment.

  19. Small-amplitude magnetic Rayleigh-Taylor instability growth in cylindrical liners and Z-pinches imploded in an axial magnetic field

    Science.gov (United States)

    Velikovich, A. L.; Giuliani, J. L.; Clark, R. W.; Mikitchuk, D.; Kroupp, E.; Maron, Y.; Fisher, A.; Schmit, P. F.

    2014-10-01

    Recent progress in developing the MagLIF approach to pulsed-power driven inertial confinement fusion has stimulated the interest in observation and mitigation of the magnetic Rayleigh-Taylor instability (MRTI) of liners and Z-pinches imploded in an axial magnetic field. Theoretical analysis of these issues is particularly important because direct numerical simulation of the MRTI development is challenging due to intrinsically 3D helical structure of the fastest-growing modes. We review the analytical small-amplitude theory of the MRTI perturbation development and the weakly nonlinear theory of MRTI mode interaction, emphasizing basic physics, opportunity for 3D code verification against exact analytical solutions, and stabilization criteria. The theory is compared to the experimental results obtained at Weizmann Institute with gas-puff Z pinches and on the Z facility at Sandia with solid liners imploded in an axial magnetic field. Work supported by the US DOE/NNSA, and by the US-Israel Binational Science Foundation. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  20. 新型轴流导叶式气液旋流器流场数值模拟%Numerical Simulation of the Flow Filed of Axial-flow Vane-Guided Cyclone for Gas-Liquid Separation

    Institute of Scientific and Technical Information of China (English)

    黄龙; 邓松圣; 王斌; 陈志

    2015-01-01

    A numerical simulation of the flow filed of axial⁃flow vane⁃guided cyclone for gas⁃liquid separation was carried out using CFD software. Hybrid grid on split volumes was used to improve the quality of the grid and the turbulence simulation was based on RSM model. The results include velocity and pressure field of the cyclone, and show that they are different from the traditional cyclone’ s. The flow field is of good symmetrical, and there exists only downward external vortex and no upward inner vortex in the straight part. The tangential velocity and axial velocity distribution is the same but radial velocity is very small. The pressure drop is mainly caused by dynamic pressure loss, and the biggest loss is located in the flow around the vanes.%针对某新型轴流导叶式气液旋流器,利用CFD软件进行了真实工况下的流场数值模拟。采用分区段的混合网格提高了网格质量,湍流模拟采用了精度较高的RSM模型。通过模拟得到了旋流器内部流场的速度及压强变化规律,结果表明:该旋流器流场与传统旋流器有较大区别,流场对称性很好,且直筒部分流场只存在下降外旋流,而无上升内旋流;切向速度与轴向速度分布规律相似,径向速度由于直筒结构保持较小水平;压降主要表现为动压损失,且导叶处压降损失最大。

  1. Effect of guide field on three dimensional electron shear flow instabilities in collisionless magnetic reconnection

    CERN Document Server

    Jain, Neeraj

    2014-01-01

    We examine the effect of an external guide field and current sheet thickness on the growth rates and nature of three dimensional unstable modes of an electron current sheet driven by electron shear flow. The growth rate of the fastest growing mode drops rapidly with current sheet thickness but increases slowly with the strength of the guide field. The fastest growing mode is tearing type only for thin current sheets (half thickness $\\approx d_e$, where $d_e=c/\\omega_{pe}$ is electron inertial length) and zero guide field. For finite guide field or thicker current sheets, fastest growing mode is non-tearing type. However growth rates of the fastest 2-D tearing mode and 3-D non-tearing mode are comparable for thin current sheets ($d_e < $half thickness $ < 2\\,d_e$) and small guide field (of the order of the asymptotic value of the component of magnetic field supporting electron current sheet). It is shown that the general mode resonance conditions for electron-magnetohydrodynamic (EMHD) and magnetohydrody...

  2. Chaos-induced resistivity of collisionless magnetic reconnection in the presence of a guide field

    Science.gov (United States)

    Shang, Meng; Wu, De-Jin; Chen, Ling; Chen, Peng-Fei

    2017-01-01

    One of the most puzzling problems in astrophysics is to understand the anomalous resistivity in collisionless magnetic reconnection that is believed extensively to be responsible for the energy release in various eruptive phenomena. The magnetic null point in the reconnecting current sheet, acting as a scattering center, can lead to chaotic motions of particles in the current sheet, which is one of the possible mechanisms for anomalous resistivity and is called chaos-induced resistivity. In many interesting cases, however, instead of the magnetic null point, there is a nonzero magnetic field perpendicular to the merging field lines, usually called the guide field, whose effect on chaos-induced resistivity has been an open problem. By use of the test particle simulation method and statistical analysis, we investigate chaos-induced resistivity in the presence of a constant guide field. The characteristics of particle motion in the reconnecting region, in particular, the chaotic behavior of particle orbits and evolving statistical features, are analyzed. The results show that as the guide field increases, the radius of the chaos region increases and the Lyapunov index decreases. However, the effective collision frequency, and hence the chaos-induced resistivity, reach their peak values when the guide field approaches half of the characteristic strength of the reconnection magnetic field. The presence of a guide field can significantly influence the chaos of the particle orbits and hence the chaos-induced resistivity in the reconnection sheet, which decides the collisionless reconnection rate. The present result is helpful for us to understand the microphysics of anomalous resistivity in collisionless reconnection with a guide field.

  3. On the BRST and finite field dependent BRST of a model where vector and axial vector interaction get mixed up with different weight

    CERN Document Server

    Rahaman, Anisur

    2016-01-01

    The generalized version of a lower dimensional model where vector and axial vector interaction get mixed up with different weight is considered. The bosonized version of which does not posses the local gauge symmetry. An attempt has been made here to construct BRST invariant reformulation of this model using Batalin Fradlin and Vilkovisky formalism. It is found that the extra field needed to make it gauge invariant turns into Wess-Zumino scalar with appropriate choice of gauge fixing. An application of finite field dependent BRST and anti-BRST transformation is also made here in order to show the transmutation between the BRST symmetric and the usual non-symmetric version of the model.

  4. Standard Guide for Conducting Corrosion Tests in Field Applications

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This guide covers procedures for conducting corrosion tests in plant equipment or systems under operating conditions to evaluate the corrosion resistance of engineering materials. It does not cover electrochemical methods for determining corrosion rates. 1.1.1 While intended primarily for immersion tests, general guidelines provided can be applicable for exposure of test specimens in plant atmospheres, provided that placement and orientation of the test specimens is non-restrictive to air circulation. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See also 10.4.2.

  5. Field guide to next-generation DNA sequencers.

    Science.gov (United States)

    Glenn, Travis C

    2011-09-01

    The diversity of available 2(nd) and 3(rd) generation DNA sequencing platforms is increasing rapidly. Costs for these systems range from $10/Mb for 454 and some Ion Torrent chips). In terms of cost per nonmultiplexed sample and instrument run time, the Pacific Biosciences and Ion Torrent platforms excel, with the 454 GS Junior and Illumina MiSeq also notable in this regard. All platforms allow multiplexing of samples, but details of library preparation, experimental design and data analysis can constrain the options. The wide range of characteristics among available platforms provides opportunities both to conduct groundbreaking studies and to waste money on scales that were previously infeasible. Thus, careful thought about the desired characteristics of these systems is warranted before purchasing or using any of them. Updated information from this guide will be maintained at: http://dna.uga.edu/ and http://tomato.biol.trinity.edu/blog/. © 2011 Blackwell Publishing Ltd.

  6. Quantum field theory a tourist guide for mathematicians

    CERN Document Server

    Folland, Gerald B

    2008-01-01

    Quantum field theory has been a great success for physics, but it is difficult for mathematicians to learn because it is mathematically incomplete. Folland, who is a mathematician, has spent considerable time digesting the physical theory and sorting out the mathematical issues in it. Fortunately for mathematicians, Folland is a gifted expositor. The purpose of this book is to present the elements of quantum field theory, with the goal of understanding the behavior of elementary particles rather than building formal mathematical structures, in a form that will be comprehensible to mathematicians. Rigorous definitions and arguments are presented as far as they are available, but the text proceeds on a more informal level when necessary, with due care in identifying the difficulties. The book begins with a review of classical physics and quantum mechanics, then proceeds through the construction of free quantum fields to the perturbation-theoretic development of interacting field theory and renormalization theor...

  7. Geologic field-trip guide to Lassen Volcanic National Park and vicinity, California

    Science.gov (United States)

    Muffler, L. J. Patrick; Clynne, Michael A.

    2015-07-22

    This geologic field-trip guide provides an overview of Quaternary volcanism in and around Lassen Volcanic National Park in northern California. The guide begins with a comprehensive overview of the geologic framework and the stratigraphic terminology of the Lassen region, based primarily on the “Geologic map of Lassen Volcanic National Park and vicinity” (Clynne and Muffler, 2010). The geologic overview is then followed by detailed road logs describing the volcanic features that can readily be seen in the park and its periphery. Twenty-one designated stops provide detailed explanations of important volcanic features. The guide also includes mileage logs along the highways leading into the park from the major nearby communities. The field-trip guide is intended to be a flexible document that can be adapted to the needs of a visitor approaching the park from any direction.

  8. Columnar-to-Equiaxed Transition and Equiaxed Grain Alignment in Directionally Solidified Ni3Al Alloy Under an Axial Magnetic Field

    Science.gov (United States)

    Liu, Huan; Xuan, Weidong; Xie, Xinliang; Li, Chuanjun; Wang, Jiang; Yu, Jianbo; Li, Xi; Zhong, Yunbo; Ren, Zhongming

    2017-09-01

    The effect of an axial magnetic field on the solidification structure in directionally solidified Ni-21.5Al-0.4Zr-0.1B (at. pct) alloy was investigated. The experimental results indicated that the application of a high magnetic field caused the deformation of dendrites and the occurrence of columnar-to-equiaxed transition (CET). The magnetic field tended to orient the 〈001〉 crystal direction of the equiaxed grains along the magnetic field direction. The bulk solidification experiment under a high magnetic field showed that the crystal exhibited magnetic crystalline anisotropy. Further, the thermoelectric (TE) magnetic force and TE magnetic convention were analyzed by three-dimensional (3-D) numerical simulations. The results showed that the maximum value of TE magnetic force localized in the vicinity of the secondary dendrite arm root, which should be responsible for the dendrite break and CET. Based on the high-temperature creep mechanism, a simple model was proposed to describe the magnetic field intensity needed for CET: B \\ge kG^{ - 1.5} R^{1.25} . The model is in good agreement with the experiment results. The experimental results should be attributed to the combined action of TE magnetic effects and the magnetic moment.

  9. Flow Field Characteristics Analysis of Axial Flow Pump Based on CFD%基于 CFD的轴流泵流场特性分析

    Institute of Scientific and Technical Information of China (English)

    曹婷; 郑源

    2014-01-01

    For more further research on axial-flow pump,learning pump running under different conditions and to further emphasizing the impor-tance of optimal conditions running,combined with a model pump data in South-to-North Water Transfer Project,the model pump were numerically simulated by using CFD software Fluent with multiple reference system coordinates were chosen and based on the S-A turbulence model. Axial flow pump hydraulic performance under different conditions were estimated by calculating,the external characteristic curve were drawn. Compared with the experimental result,they were approximate,showing the simulation’s accuracy. The pressure and velocity distribution of blade and guide vanes were analyzed based on the result of the numerical simulation. Some laws of blade and guide vanes’flow pattern under different conditions were showed,the bland pressure was increased in the radial. The magnitude of relative velocity presented cylindrical surface distribution increased from hub to rim. The pressure of Guide vanes was presented as zonal distribution and water flowed out along the axial finally.%为更深入研究轴流泵,了解不同工况下轴流泵的运行状态,进一步强调最优工况运行的重要性,结合南水北调工程中某泵站模型的数据,采用流体力学软件Fluent,在多重参考坐标系下,选用S-A湍流模型对模型泵进行数值模拟。通过计算,对不同工况下的轴流泵水力性能进行了预估,绘制了轴流泵的特性曲线,与试验值进行比较,吻合较好,说明了数值模拟的准确性。根据数值计算结果,分析了轴流泵叶轮叶片和导叶叶片表面的速度及压力分布,揭示了叶片和导叶表面流态和压力的分布规律:叶片压力径向递增,相对速度由轮毂到轮缘逐渐加快,按圆柱面分布,导叶表面压力呈带状分布,水流最终从导叶出口沿轴向流出。

  10. Guided transect sampling - a new design combining prior information and field surveying

    Science.gov (United States)

    Anna Ringvall; Goran Stahl; Tomas Lamas

    2000-01-01

    Guided transect sampling is a two-stage sampling design in which prior information is used to guide the field survey in the second stage. In the first stage, broad strips are randomly selected and divided into grid-cells. For each cell a covariate value is estimated from remote sensing data, for example. The covariate is the basis for subsampling of a transect through...

  11. [Book review] A field guide to the birds of New Zealand and outlying islands

    Science.gov (United States)

    Robbins, Chandler S.

    1969-01-01

    This field guide is so closely patterned after the familiar Peterson style that it may best be described in terms of its departures from that style. Color plates are disappointingly few. They depict: Penguin heads, parrots and kingfisher, eight species of ducks, a pigeon and seven species of native songbirds, eight other passerines and two cuckoos, and nine introduced songbirds (eight of which have been figured more expertly by Peterson in his European or Western guides).

  12. An illustrated gardener's guide to transgenic Arabidopsis field experiments.

    Science.gov (United States)

    Frenkel, Martin; Jänkänpää, Hanna Johansson; Moen, Jon; Jansson, Stefan

    2008-01-01

    Field studies with transgenic Arabidopsis lines have been performed over 8 yr, to better understand the influence that certain genes have on plant performance. Many (if not most) plant phenotypes cannot be observed under the near constant, low-stress conditions in growth chambers, making field experiments necessary. However, there are challenges in performing such experiments: permission must be obtained and regulations obeyed, the profound influence of uncontrollable biotic and abiotic factors has to be considered, and experimental design has to be strictly controlled. The aim here is to provide inspiration and guidelines for researchers who are not used to setting up such experiments, allowing others to learn from our mistakes. This is believed to be the first example of a 'manual' for field experiments with transgenic Arabidopsis plants. Many of the challenges encountered are common for all field experiments, and many researchers from ecological backgrounds are skilled in such methods. There is huge potential in combining the detailed mechanistic understanding of molecular biologists with ecologists' expertise in examining plant performance under field conditions, and it is suggested that more interdisciplinary collaborations will open up new scientific avenues to aid analyses of the roles of genetic and physiological variation in natural systems.

  13. Study of axial magnetic effect

    Energy Technology Data Exchange (ETDEWEB)

    Braguta, Victor [IHEP, Protvino, Moscow region, 142284 Russia ITEP, B. Cheremushkinskaya street 25, Moscow, 117218 (Russian Federation); School of Biomedicine, Far Eastern Federal University, Ajax 10 Building 25, Russian island, Vladivostok, 690922 (Russian Federation); Chernodub, M. N. [CNRS, Laboratoire de Mathématiques et Physique Théorique, Université François-Rabelais Tours, Fédération Denis Poisson, Parc de Grandmont, 37200 Tours, France Department of Physics and Astronomy, University of Gent, Krijgslaan 281, S9, B-9000 Gent (Belgium); School of Biomedicine, Far Eastern Federal University, Ajax 10 Building 25, Russian island, Vladivostok, 690922 (Russian Federation); Goy, V. A. [School of Natural Sciences, Far Eastern Federal University, Sukhanova street 8, Vladivostok, 690950 (Russian Federation); Landsteiner, K. [Instituto de Física Teórica UAM/CSIC, C/ Nicolás Cabrera 13-15, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Molochkov, A. V. [School of Biomedicine, Far Eastern Federal University, Ajax 10 Building 25, Russian island, Vladivostok, 690922 (Russian Federation); Ulybyshev, M. [ITEP, B. Cheremushkinskaya street 25, Moscow, 117218 Russia Institute for Theoretical Problems of Microphysics, Moscow State University, Moscow, 119899 (Russian Federation)

    2016-01-22

    The Axial Magnetic Effect manifests itself as an equilibrium energy flow of massless fermions induced by the axial (chiral) magnetic field. Here we study the Axial Magnetic Effect in the quenched SU(2) lattice gauge theory with massless overlap fermions at finite temperature. We numerically observe that in the low-temperature hadron phase the effect is absent due to the quark confinement. In the high-temperature deconfinement phase the energy flow is an increasing function of the temperature which reaches the predicted asymptotic T{sup 2} behavior at high temperatures. We find, however, that energy flow is about one order of magnitude lower compared to a theoretical prediction.

  14. A field guide to current advances in paediatric movement disorders.

    Science.gov (United States)

    Silveira-Moriyama, Laura; Lin, Jean-Pierre

    2015-08-01

    Recent advances in neurogenetics, neuroimmunology and nonpharmacological treatments have reshaped the field of paediatric movement disorders. In this review, we put recent findings into context providing a framework to enable navigation of the expanding literature in this field. Anti-NMDA receptor encephalitis has proven to be a significant cause of treatable movement disorder in children and to present a multifaceted link with herpes simplex encephalitis. The growing use of next-generation sequencing in both research and clinical practice has unravelled an expanding number of genes related to paediatric movement disorders as well as expanding spectrums of variable expressivity and phenotypic pleiotropy for various genes. Behavioural therapies have been proven efficacious in Tourette's syndrome and are likely to be helpful in complex motor stereotypies. Management of dystonia remains a clinical priority and challenge. The rapid advance of translational medicine has had major impacts on the field of paediatric movement disorders including diagnosis and treatment of these conditions.

  15. Multipoint Measurements of the Electron Jet of Symmetric Magnetic Reconnection with a Moderate Guide Field

    Science.gov (United States)

    Wilder, F. D.; Ergun, R. E.; Eriksson, S.; Phan, T. D.; Burch, J. L.; Ahmadi, N.; Goodrich, K. A.; Newman, D. L.; Trattner, K. J.; Torbert, R. B.; Giles, B. L.; Strangeway, R. J.; Magnes, W.; Lindqvist, P.-A.; Khotyaintsev, Yu-V.

    2017-06-01

    We report observations from the Magnetospheric Multiscale (MMS) satellites of the electron jet in a symmetric magnetic reconnection event with moderate guide field. All four spacecraft sampled the ion diffusion region and observed the electron exhaust. The observations suggest that the presence of the guide field leads to an asymmetric Hall field, which results in an electron jet skewed towards the separatrix with a nonzero component along the magnetic field. The jet appears in conjunction with a spatially and temporally persistent parallel electric field ranging from -3 to -5 mV /m , which led to dissipation on the order of 8 nW /m3 . The parallel electric field heats electrons that drift through it, and is associated with a streaming instability and electron phase space holes.

  16. Equations of state for collisionless guide-field reconnection.

    Science.gov (United States)

    Le, A; Egedal, J; Daughton, W; Fox, W; Katz, N

    2009-02-27

    Direct in situ observation of magnetic reconnection in the Earth's magnetotail as well as kinetic numerical studies have recently shown that the electron pressure in a collisionless reconnection region is strongly anisotropic. This anisotropy is mainly caused by the trapping of electrons in parallel electric fields. We present new equations of state for the parallel and perpendicular pressures for magnetized electrons. This model-derived here and tested against a kinetic simulation-allows a fluid description in a collisionless regime where parallel electric fields and the dynamics of both passing and trapped electrons are essential.

  17. Experimental investigation on axial-flow turbine arrays in erodible and non-erodible channels: Performance, flow-field, and bathymetric interactions

    Science.gov (United States)

    Hill, Craig; Sotiropoulos, Fotis; Guala, Michele

    2014-11-01

    Natural channels ideal for hydrokinetic turbine installations present complex environments containing asymmetric flow, regions of high shear and turbulent eddies that impact turbine performance. To understand the impacts caused by variable topography, baseline conditions in a laboratory flume are compared to turbine performance, flow characteristics, and channel topography measurements from two additional experiments with small-scale and large-scale bathymetric features. Both aligned and staggered multi-turbine configurations were investigated. Small-scale axial-flow rotors attached to miniature DC motors provided measurements of turbine performance and response to i) complex topographic features and ii) flow features induced by upstream turbines. Discussion will focus on optimal streamwise and lateral spacing for axial-flow devices, turbine-topography interactions within arrays and inter-array flow-field measurements. Primary focus will center on results from turbines separated by a streamwise distance of 7dT. Additionally, results indicate possible control strategies for turbines installed in complex natural environments. This work was supported by NSF PFI Grant IIP-1318201, CAREER: Geophysical Flow Control (NSF).

  18. EXPERIMENTAL RESEARCH ON AERODYNAMIC PERFORMANCE AND EXIT FLOW FIELD OF LOW PRESSURE AXIAL FLOW FAN WITH CIRCUMFERENTIAL SKEWED BLADES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this article, the low pressure axial flow fan with circumferential skewed rotor blade, including the radial blade, the forward-skewed blade and the backward-skewed blade, was studied with experimental methods. The aerodynamic performance of the rotors was measured. At the design condition at outlet of the rotors, detailed flow measurements were performed with a five-hole probe and a Hot-Wire Anemometer (HWA). The results show that compared to the radial rotor, the forward-skewed rotor demonstrates a wider Stable Operating Range (SOR), is able to reduce the total pressure loss in the hub region and make main loading of blade accumulating in the mid-span region. There is a wider wake in the upper mid-span region of the forward-skewed rotor. Compared to the radial rotor, in the backward-skewed rotor there is higher total pressure loss near the hub and shroud regions and lower loss in the mid-span region. In addition, the velocity deficit in the wake is lower at mid-span of the backward-skewed rotor than the forward-skewed rotor.

  19. Moonwalk with Your Eyes A Pocket Field Guide

    CERN Document Server

    Plotner, Tammy

    2010-01-01

    Are you ready to take a quarter of a million mile journey with just your eyes? Then welcome to "Moon Walk with Your Eyes"! We often take the beauty of our nearest astronomical neighbor for granted. How often do we really stop to think about why it looks the way it does or what a closer look will reveal? In this book, written in easy-to-understand language by one backyard astronomer to another, we'll explore the Moon night by night, as it goes through a full cycle. Every lunar day has something new to learn! And along your journey, you will be reading about the history, mystery, poetry, and legends that are associated with our Moon. Charts will help guide you to specific lunar features, as well as annotated photographic maps that pinpoint important or unusual craters. You'll soon learn to identify major features at just a glance and be able to create your own world-class images. You'll have right at hand the times and dates for every lunar day, phase, and eclipse for years to come. Imagine yourself at the tele...

  20. Field Encapsulation Library The FEL 2.2 User Guide

    Science.gov (United States)

    Moran, Patrick J.; Henze, Chris; Ellsworth, David

    1999-01-01

    This document describes version 2.2 of the Field Encapsulation Library (FEL), a library of mesh and field classes. FEL is a library for programmers - it is a "building block" enabling the rapid development of applications by a user. Since FEL is a library intended for code development, it is essential that enough technical detail be provided so that one can make full use of the code. Providing such detail requires some assumptions with respect to the reader's familiarity with the library implementation language, C++, particularly C++ with templates. We have done our best to make the explanations accessible to those who may not be completely C++ literate. Nevertheless, familiarity with the language will certainly help one's understanding of how and why things work the way they do. One consolation is that the level of understanding essential for using the library is significantly less than the level that one should have in order to modify or extend the library. One more remark on C++ templates: Templates have been a source of both joy and frustration for us. The frustration stems from the lack of mature or complete implementations that one has to work with. Template problems rear their ugly head particularly when porting. When porting C code, successfully compiling to a set of object files typically means that one is almost done. With templated C++ and the current state of the compilers and linkers, generating the object files is often only the beginning of the fun. On the other hand, templates are quite powerful. Used judiciously, templates enable more succinct designs and more efficient code. Templates also help with code maintenance. Designers can avoid creating objects that are the same in many respects, but not exactly the same. For example, FEL fields are templated by node type, thus the code for scalar fields and vector fields is shared. Furthermore, node type templating allows the library user to instantiate fields with data types not provided by the FEL

  1. 2D-particle image velocimetry measurement for internal flow field of axial flow pump%轴流泵内部流场的二维粒子成像测速试验

    Institute of Scientific and Technical Information of China (English)

    张华; 施卫东; 陈斌; 张德胜; 胡啟祥

    2013-01-01

    To investigate the flow field distribution at the regions of the impeller and guide vane inlet and outlet under condition of 0.8Qopt, the axial flow pump with ns=700 was selected for model scaling and structural modification, from which we could get a test bed suitable for a 2D-PIV internal flow field test. Structural modifications included: the conventional metal material was replaced with transparent organic glass material to achieve the purpose of internal visualization;the conventional conical diffuser vane was designed into cylindrical shape to reduce the complexity of optical refraction;the runner chamber was merged with a guide vane casing to form as a whole to eliminate the occlusion of the flange to an internal flow field between the region of impeller and diffuser vane;the bearing within the diffuser vane was moved backward and rib plates were installed to make the load transfer to foundation smoothly. Based on the above methods, an experiment pump section was modified successfully, and the efficiency of the experimental pump reached 73.79%, which was close to that of the prototype pump. It was indicated that less damage occurred to the original flow field with structural modification. During the PIV measurement, the shaft encoder and synchronizer were used for better synchronous effect. Meanwhile, an ideal experimental result was obtained by using organic glass hollow spheres as tracer particles, and a new calibration method. As shown in the original PIV images, the particle distribution was homogeneous with most particles appearing to be micro-exposure, which meant an ideal experiment effect. From the analysis of the experimental result, it was indicated that, owing to the effect of the tip leakage flow at the 0.8Qopt operating point, the inflow at the rim of an impeller leading edge deflects to the hub side, but the whole flow field is evenly distributed on the front section of an impeller; a clockwise vortex with an outer diameter larger than the hub

  2. The Deep Change Field Guide A Personal Course to Discovering the Leader Within

    CERN Document Server

    Quinn, Robert E

    2012-01-01

    How to realize your own leadership potential Based on the bestselling book, Deep Change, The Deep Change Field Guide takes readers through the introspective journey of personal transformation. The field guide streamlines, updates, and augments the content of the original book into an interactive self-teaching course that helps readers learn how to become powerful agents of change. Learning tools include reflection questions, film assignments, and action plans that help readers think about the concepts in terms of their own situations, and identify actions to embody the concepts in their lives.

  3. Linux malware incident response an excerpt from malware forensic field guide for Linux systems

    CERN Document Server

    Malin, Cameron H; Aquilina, James M

    2013-01-01

    Linux Malware Incident Response is a ""first look"" at the Malware Forensics Field Guide for Linux Systems, exhibiting the first steps in investigating Linux-based incidents. The Syngress Digital Forensics Field Guides series includes companions for any digital and computer forensic investigator and analyst. Each book is a ""toolkit"" with checklists for specific tasks, case studies of difficult situations, and expert analyst tips. This compendium of tools for computer forensics analysts and investigators is presented in a succinct outline format with cross-references to suppleme

  4. A Visual Astronomer's Photographic Guide to the Deep Sky A Pocket Field Guide

    CERN Document Server

    Rumistrzewicz, Stefan

    2010-01-01

    How many times have you ‘found’ a deep sky object (DSO), ticked it off the list, and moved on, or used the ‘Tour’ function on your GO-TO ‘scope and said, ‘Oh that’s a just a smudge’ or ‘Can’t see it – I’ll move on to the next one.’ If this has happened to you, then this book is for you. It will challenge you to go back to the ‘smudge’ and really look. Can you see the faint wisp or the detail in the southeastern corner? Can you see the small cluster within the cluster? Try to classify the open cluster for yourself. Compare it to the ‘accepted’ Trumpler classification. Whether you have a GO-TO ‘scope or not, this book gets you to rediscover one of the great things that got you into this hobby in the first place – looking through the eyepiece of a telescope. So pack away the DSLR, CCD camera, the guide ‘scope, and laptop and open your pencil case! You’re in for some fun!

  5. On the Electron Diffusion Region in Asymmetric Reconnection with a Guide Magnetic Field

    Science.gov (United States)

    Hesse, Michael; Liu, Yi-Hsin; Chen, Li-Jen; Bessho, Naoki; Kuznetsova, Masha; Birn, Joachim; Burch, James L.

    2016-01-01

    Particle-in-cell simulations in a 2.5-D geometry and analytical theory are employed to study the electron diffusion region in asymmetric reconnection with a guide magnetic field. The analysis presented here demonstrates that similar to the case without guide field, in-plane flow stagnation and null of the in-plane magnetic field are well separated. In addition, it is shown that the electric field at the local magnetic X point is again dominated by inertial effects, whereas it remains dominated by nongyrotropic pressure effects at the in-plane flow stagnation point. A comparison between local electron Larmor radii and the magnetic gradient scale lengths predicts that distribution should become nongyrotropic in a region enveloping both field reversal and flow stagnation points. This prediction is verified by an analysis of modeled electron distributions, which show clear evidence of mixing in the critical region.

  6. Experimental demonstration of the role of electron pressure in fast magnetic reconnection with a guide field

    Science.gov (United States)

    Fox, W.; Sciortino, F.; von Stechow, A.; Jara-Almonte, J.; Yoo, J.; Ji, H.; Yamada, M.

    2016-10-01

    We report detailed laboratory observations of the structure of reconnection current sheets in a two-fluid plasma regime with a guide magnetic field, conducted on the Magnetic Reconnection Experiment. We observe in the laboratory for the first time the quadrupolar electron pressure variation in the ion-diffusion region, as originally predicted by extended MHD simulation. We quantitatively analyze the parallel and perpendicular force balance, and observe the projection of the electron pressure gradient parallel to the B field balances the parallel electric field. The resulting cross-field electron jets in the reconnection layer are diamagnetic in origin. Electron density variations are observed to dominate temperature variations and may provide a new diagnostic of reconnection with finite guide field for fusion experiments and spacecraft missions. Supported by Max-Planck Princeton Center for Plasma Physics.

  7. A Novel Electrostatic Guiding Scheme for Cold Polar Molecules in Weak-Field-Seeking States

    Institute of Scientific and Technical Information of China (English)

    DENG Lian-Zhong; XIA Yong; YIN Jian-Ping

    2005-01-01

    @@ We propose a novel electrostatic guiding scheme for cold polar molecules in weak-field-seeking states using a single charged wire half embanked in a ceramic substrate (i.e., a chip) and a homogeneous bias electric field, which is produced by a capacitor composed of two large parallel metal plates. We calculate the spatial distribution of the electrostatic fields generated by the combination of the charged wire and the plate capacitor and the corresponding trapping potentials for CO molecules, and analyse the relationships between the electric field and the parameters of the charged-wire layout. Our study shows that the proposed scheme with a single charged-wire can be used to guide cold polar molecules in the weak-field-seeking states, and has some potential applications in construction of various molecule-optical elements.

  8. On the Electron Diffusion Region in Asymmetric Reconnection with a Guide Magnetic Field

    Science.gov (United States)

    Hesse, Michael; Liu, Yi-Hsin; Chen, Li-Jen; Bessho, Naoki; Kuznetsova, Masha; Birn, Joachim; Burch, James L.

    2016-01-01

    Particle-in-cell simulations in a 2.5-D geometry and analytical theory are employed to study the electron diffusion region in asymmetric reconnection with a guide magnetic field. The analysis presented here demonstrates that similar to the case without guide field, in-plane flow stagnation and null of the in-plane magnetic field are well separated. In addition, it is shown that the electric field at the local magnetic X point is again dominated by inertial effects, whereas it remains dominated by nongyrotropic pressure effects at the in-plane flow stagnation point. A comparison between local electron Larmor radii and the magnetic gradient scale lengths predicts that distribution should become nongyrotropic in a region enveloping both field reversal and flow stagnation points. This prediction is verified by an analysis of modeled electron distributions, which show clear evidence of mixing in the critical region.

  9. Experimental Verification of the Role of Electron Pressure in Fast Magnetic Reconnection with a Guide Field.

    Science.gov (United States)

    Fox, W; Sciortino, F; V Stechow, A; Jara-Almonte, J; Yoo, J; Ji, H; Yamada, M

    2017-03-24

    We report detailed laboratory observations of the structure of a reconnection current sheet in a two-fluid plasma regime with a guide magnetic field. We observe and quantitatively analyze the quadrupolar electron pressure variation in the ion-diffusion region, as originally predicted by extended magnetohydrodynamics simulations. The projection of the electron pressure gradient parallel to the magnetic field contributes significantly to balancing the parallel electric field, and the resulting cross-field electron jets in the reconnection layer are diamagnetic in origin. These results demonstrate how parallel and perpendicular force balance are coupled in guide field reconnection and confirm basic theoretical models of the importance of electron pressure gradients for obtaining fast magnetic reconnection.

  10. Reconnection Guide Field and Quadrupolar Structure Observed by MMS on 16 October 2015 at 1307 UT

    Science.gov (United States)

    Denton, R. E.; Sonnerup, B. U. O.; Hasagawa, H.; Phan, T. D.; Russell, C. T.; Strangeway, R. J.; Giles, B. L.; Torbert, R. B.

    2016-01-01

    We estimate the guide field near the X point, B(sub M0), for a magnetopause crossing by the Magnetospheric Multiscale (MMS) spacecraft at 1307 UT on 16 October 2015 that showed features of electron-scale reconnection. This component of the magnetic field is normal to the reconnection plane L-N containing the reconnection magnetic field, B(sub L), and the direction e(sub N) normal to the current sheet. The B(sub M) field component appears to approximately have quadrupolar structure close to the X point. Using several different methods to estimate values of the guide field near the X point, some of which use an assumed quadrupolar symmetry, we find values ranging between -3.1 nT and -1.2 nT, with a nominal value of about -2.5 nT. The rough consistency of these values is evidence that the quadrupolar structure exists.

  11. Field guide to Muddy Formation outcrops, Crook County, Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    Rawn-Schatzinger, V.

    1993-11-01

    The objectives of this research program are to (1) determine the reservoir characteristics and production problems of shoreline barrier reservoirs; and (2) develop methods and methodologies to effectively characterize shoreline bamer reservoirs to predict flow patterns of injected and produced fluids. Two reservoirs were selected for detailed reservoir characterization studies -- Bell Creek field, Carter County, Montana that produces from the Lower Cretaceous (Albian-Cenomanian) Muddy Formation, and Patrick Draw field, Sweetwater County, Wyoming that produces from the Upper Cretaceous (Campanian) Almond Formation of the Mesaverde Group. An important component of the research project was to use information from outcrop exposures of the producing formations to study the spatial variations of reservoir properties and the degree to which outcrop information can be used in the construction of reservoir models. This report contains the data and analyses collected from outcrop exposures of the Muddy Formation, located in Crook County, Wyoming, 40 miles south of Bell Creek oil field. The outcrop data set contains permeability, porosity, petrographic, grain size and geologic data from 1-inch-diameter core plugs chilled from the outcrop face, as well as geological descriptions and sedimentological interpretations of the outcrop exposures. The outcrop data set provides information about facies characteristics and geometries and the spatial distribution of permeability and porosity on interwell scales. Appendices within this report include a micropaleontological analyses of selected outcrop samples, an annotated bibliography of papers on the Muddy Formation in the Powder River Basin, and over 950 permeability and porosity values measured from 1-inch-diameter core plugs drilled from the outcrop. All data contained in this resort are available in electronic format upon request. The core plugs drilled from the outcrop are available for measurement.

  12. Near-to-far field transformations for radiative and guided waves

    CERN Document Server

    Yang, Jianji; Lalanne, Philippe

    2015-01-01

    Light emitters or scatterers embedded in stratified media may couple energy to both free space and guided modes of the stratified structure. For a thorough analysis of such structures, it is important to evaluate the angular intensity distribution of both the free-space-propagative and guided waves. In this work, we propose an original method based on Lorentz-reciprocity theorem and on the computation of the near-field around the emitters or scatterers, to efficiently calculate the free-space and guided radiation diagrams with a high accuracy. We also provide an open-source code that may be used with virtually any Maxwells solver. The numerical tool may help to engineer various devices, such as light-emitting diodes or nanoantennas to achieve directional and efficient radiative spontaneous decays in free space and guided optics.

  13. Numerical simulation and analysis of performance of axial flow pump with adjustable guide vanes%可调导叶式轴流泵水力特性数值模拟

    Institute of Scientific and Technical Information of China (English)

    钱忠东; 王焱; 郑彪; 刘德祥

    2011-01-01

    为了减小轴流泵导叶段水力损失,提高轴流泵性能,本文提出一种新型后置导叶--可调式导叶.通过理论推导,得出了可调式导叶的调整规律,在实验结果验证的基础上,采用数值模拟方法,对固定导叶和可调式导叶两种模型下轴流泵内的水力特性进行了分析.分析结果表明:导叶进口冲角和尾部脱流是导致导叶段水力损失的两大主要因素;可调式导叶可以通过调节角度显著改善轴流泵导叶段的流态,减小水力损失,提高水泵扬程和效率.%This paper proposes a new adjustable guide vane (AGV) that reduces hydraulic loss and improves performance of axial flow pump. The relationship between the guide vane angle and operating parameters of the pump is obtained by theoretical analysis. Flows in the pump are simulated for the cases of fixed vanes and AGV. The calculated Q-H curve of fixed vanes agrees well with the experiment. Results show that inflow incidence and flow separation of the guide vane flow are two major factors to the formation of vortices that cause extra hydraulic loss in the guide vane channel, and that the capability of adjusting guide vane angle is responsible for the decrease in hydraulic loss and the increases in pump head and pumping efficiency.

  14. The role of guide field in magnetic reconnection driven by island coalescence

    CERN Document Server

    Stanier, A; Simakov, Andrei N; Chacon, L; Le, A; Karimabadi, H; Ng, Jonathan; Bhattacharjee, A

    2016-01-01

    A number of studies have considered how the rate of magnetic reconnection scales in large and weakly collisional systems by the modelling of long reconnecting current sheets. However, this set-up neglects both the formation of the current sheet and the coupling between the diffusion region and a larger system that supplies the magnetic flux. Recent studies of magnetic island merging, which naturally include these features, have found that ion kinetic physics is crucial to describe the reconnection rate and global evolution of such systems. In this paper, the effect of a guide field on reconnection during island merging is considered. In contrast to the earlier current sheet studies, we identify a limited range of guide fields for which the reconnection rate, outflow velocity, and pile-up magnetic field increase in magnitude as the guide field increases. The Hall-MHD fluid model is found to reproduce kinetic reconnection rates only for a sufficiently strong guide field, for which ion inertia breaks the frozen-...

  15. Geologic guide to the island of Hawaii: A field guide for comparative planetary geology

    Science.gov (United States)

    Greeley, R. (Editor)

    1974-01-01

    With geological data available for all inner planets except Venus, we are entering an era of true comparative planetary geology, when knowledge of the differences and similarities for classes of structures (e.g., shield volcanoes) will lead to a better understanding of general geological processes, regardless of planet. Thus, it is imperative that planetologists, particularly those involved in geological mapping and surface feature analysis for terrestrial planets, be familiar with volcanic terrain in terms of its origin, structure, and morphology. One means of gaining this experience is through field trips in volcanic terrains - hence, the Planetology Conference in Hawaii. In addition, discussions with volcanologists at the conference provide an important basis for establishing communications between the two fields that will facilitate comparative studies as more data become available.

  16. Impact of detector design on imaging performance of a long axial field-of-view, whole-body PET scanner

    Science.gov (United States)

    Surti, S.; Karp, J. S.

    2015-07-01

    Current generation of commercial time-of-flight (TOF) PET scanners utilize 20-25 mm thick LSO or LYSO crystals and have an axial FOV (AFOV) in the range of 16-22 mm. Longer AFOV scanners would provide increased intrinsic sensitivity and require fewer bed positions for whole-body imaging. Recent simulation work has investigated the sensitivity gains that can be achieved with these long AFOV scanners, and has motivated new areas of investigation such as imaging with a very low dose of injected activity as well as providing whole-body dynamic imaging capability in one bed position. In this simulation work we model a 72 cm long scanner and prioritize the detector design choices in terms of timing resolution, crystal size (spatial resolution), crystal thickness (detector sensitivity), and depth-of-interaction (DOI) measurement capability. The generated list data are reconstructed with a list-mode OSEM algorithm using a Gaussian TOF kernel that depends on the timing resolution and blob basis functions for regularization. We use lesion phantoms and clinically relevant metrics for lesion detectability and contrast measurement. The scan time was fixed at 10 min for imaging a 100 cm long object assuming a 50% overlap between adjacent bed positions. Results show that a 72 cm long scanner can provide a factor of ten reduction in injected activity compared to an identical 18 cm long scanner to get equivalent lesion detectability. While improved timing resolution leads to further gains, using 3 mm (as opposed to 4 mm) wide crystals does not show any significant benefits for lesion detectability. A detector providing 2-level DOI information with equal crystal thickness also does not show significant gains. Finally, a 15 mm thick crystal leads to lower lesion detectability than a 20 mm thick crystal when keeping all other detector parameters (crystal width, timing resolution, and DOI capability) the same. However, improved timing performance with 15

  17. Impact of detector design on imaging performance of a long axial field-of-view, whole-body PET scanner.

    Science.gov (United States)

    Surti, S; Karp, J S

    2015-07-07

    Current generation of commercial time-of-flight (TOF) PET scanners utilize 20-25 mm thick LSO or LYSO crystals and have an axial FOV (AFOV) in the range of 16-22 mm. Longer AFOV scanners would provide increased intrinsic sensitivity and require fewer bed positions for whole-body imaging. Recent simulation work has investigated the sensitivity gains that can be achieved with these long AFOV scanners, and has motivated new areas of investigation such as imaging with a very low dose of injected activity as well as providing whole-body dynamic imaging capability in one bed position. In this simulation work we model a 72 cm long scanner and prioritize the detector design choices in terms of timing resolution, crystal size (spatial resolution), crystal thickness (detector sensitivity), and depth-of-interaction (DOI) measurement capability. The generated list data are reconstructed with a list-mode OSEM algorithm using a Gaussian TOF kernel that depends on the timing resolution and blob basis functions for regularization. We use lesion phantoms and clinically relevant metrics for lesion detectability and contrast measurement. The scan time was fixed at 10 min for imaging a 100 cm long object assuming a 50% overlap between adjacent bed positions. Results show that a 72 cm long scanner can provide a factor of ten reduction in injected activity compared to an identical 18 cm long scanner to get equivalent lesion detectability. While improved timing resolution leads to further gains, using 3 mm (as opposed to 4 mm) wide crystals does not show any significant benefits for lesion detectability. A detector providing 2-level DOI information with equal crystal thickness also does not show significant gains. Finally, a 15 mm thick crystal leads to lower lesion detectability than a 20 mm thick crystal when keeping all other detector parameters (crystal width, timing resolution, and DOI capability) the same. However, improved timing performance with 15

  18. Asymmetry of the ion diffusion region Hall electric and magnetic fields during guide field reconnection: observations and comparison with simulations.

    Science.gov (United States)

    Eastwood, J P; Shay, M A; Phan, T D; Øieroset, M

    2010-05-21

    In situ measurements of magnetic reconnection in the Earth's magnetotail are presented showing that even a moderate guide field (20% of the reconnecting field) considerably distorts ion diffusion region structure. The Hall magnetic and electric fields are asymmetric and shunted away from the current sheet; an appropriately scaled particle-in-cell simulation is found to be in excellent agreement with the data. The results show the importance of correctly accounting for the effects of the magnetic shear when attempting to identify and study magnetic reconnection diffusion regions in nature.

  19. The Six-Inch Lunar Atlas A Pocket Field Guide

    CERN Document Server

    Spain, Don

    2009-01-01

    The Six-Inch Lunar Atlas has been designed specifically for use in the field by lunar observers so it’s perfect for fitting into an observer’s pocket! The author’s own lunar photographs were taken with a 6-inch (150mm) telescope and CCD camera, and closely match the visual appearance of the Moon when viewed through 3-inch to 8-inch telescopes. Each picture is shown oriented "as the Moon really is" when viewed from the northern hemisphere, and is supplemented by exquisite computer sketches that list the main features. Two separate computer sketches are provided to go with each photograph, one oriented to appear as seen through an SCT telescope (e.g. the Meade and Celestron ranges), the other oriented for Newtonian and refracting telescopes. Observers using the various types telescopes will find it extremely helpful to identify lunar features as the human brain is very poor at making "mirror-image" visual translations.

  20. Field Test of the World Health Organization Multi-Professional Patient Safety Curriculum Guide

    Science.gov (United States)

    Farley, Donna; Zheng, Hao; Rousi, Eirini; Leotsakos, Agnès

    2015-01-01

    Introduction Although the importance of training in patient safety has been acknowledged for over a decade, it remains under-utilized and under-valued in most countries. WHO developed the Multi-professional Patient Safety Curriculum Guide to provide schools with the requirements and tools for incorporating patient safety in education. It was field tested with 12 participating schools across the six WHO regions, to assess its effectiveness for teaching patient safety to undergraduate and graduate students in a global variety of settings. Methods The evaluation used a combined prospective/retrospective design to generate formative information on the experiences of working with the Guide and summative information on the impacts of the Guide. Using stakeholder interviews and student surveys, data were gathered from each participating school at three times: the start of the field test (baseline), soon after each school started teaching, and soon after each school finished teaching. Results Stakeholders interviewed were strongly positive about the Guide, noting that it emphasized universally important patient safety topics, was culturally appropriate for their countries, and gave credibility and created a focus on patient safety at their schools. Student perceptions and attitudes regarding patient safety improved substantially during the field test, and their knowledge of the topics they were taught doubled, from 10.7% to 20.8% of correct answers on the student survey. Discussion This evaluation documented the effectiveness of the Curriculum Guide, for both ease of use by schools and its impacts on improving the patient safety knowledge of healthcare students. WHO should be well positioned to refine the contents of the Guide and move forward in encouraging broader use of the Guide globally for teaching patient safety. PMID:26406893

  1. Field Test of the World Health Organization Multi-Professional Patient Safety Curriculum Guide.

    Science.gov (United States)

    Farley, Donna; Zheng, Hao; Rousi, Eirini; Leotsakos, Agnès

    2015-01-01

    Although the importance of training in patient safety has been acknowledged for over a decade, it remains under-utilized and under-valued in most countries. WHO developed the Multi-professional Patient Safety Curriculum Guide to provide schools with the requirements and tools for incorporating patient safety in education. It was field tested with 12 participating schools across the six WHO regions, to assess its effectiveness for teaching patient safety to undergraduate and graduate students in a global variety of settings. The evaluation used a combined prospective/retrospective design to generate formative information on the experiences of working with the Guide and summative information on the impacts of the Guide. Using stakeholder interviews and student surveys, data were gathered from each participating school at three times: the start of the field test (baseline), soon after each school started teaching, and soon after each school finished teaching. Stakeholders interviewed were strongly positive about the Guide, noting that it emphasized universally important patient safety topics, was culturally appropriate for their countries, and gave credibility and created a focus on patient safety at their schools. Student perceptions and attitudes regarding patient safety improved substantially during the field test, and their knowledge of the topics they were taught doubled, from 10.7% to 20.8% of correct answers on the student survey. This evaluation documented the effectiveness of the Curriculum Guide, for both ease of use by schools and its impacts on improving the patient safety knowledge of healthcare students. WHO should be well positioned to refine the contents of the Guide and move forward in encouraging broader use of the Guide globally for teaching patient safety.

  2. Field trip guide to the Valles Caldera and its geothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Goff, F.E.; Bolivar, S.L.

    1983-12-01

    This field trip guide has been compiled from extensive field trips led at Los Alamos National Laboratory during the past six years. The original version of this guide was designed to augment a workshop on the Valles Caldera for the Continental Scientific Drilling Program (CSDP). This workshop was held at Los Alamos, New Mexico, 5-7 October 1982. More stops were added to this guide to display the volcanic and geothermal features at the Valles Caldera. The trip covers about 90 miles (one way) and takes two days to complete; however, those who wish to compress the trip into one day are advised to use the designated stops listed in the Introduction. Valles Caldera and vicinity comprise both one of the most exciting geothermal areas in the United States and one of the best preserved Quaternary caldera complexes in the world.

  3. Magnetospheric Multiscale Observations of the Electron Diffusion Region of Large Guide Field Magnetic Reconnection.

    Science.gov (United States)

    Eriksson, S; Wilder, F D; Ergun, R E; Schwartz, S J; Cassak, P A; Burch, J L; Chen, L-J; Torbert, R B; Phan, T D; Lavraud, B; Goodrich, K A; Holmes, J C; Stawarz, J E; Sturner, A P; Malaspina, D M; Usanova, M E; Trattner, K J; Strangeway, R J; Russell, C T; Pollock, C J; Giles, B L; Hesse, M; Lindqvist, P-A; Drake, J F; Shay, M A; Nakamura, R; Marklund, G T

    2016-07-01

    We report observations from the Magnetospheric Multiscale (MMS) satellites of a large guide field magnetic reconnection event. The observations suggest that two of the four MMS spacecraft sampled the electron diffusion region, whereas the other two spacecraft detected the exhaust jet from the event. The guide magnetic field amplitude is approximately 4 times that of the reconnecting field. The event is accompanied by a significant parallel electric field (E_{∥}) that is larger than predicted by simulations. The high-speed (∼300  km/s) crossing of the electron diffusion region limited the data set to one complete electron distribution inside of the electron diffusion region, which shows significant parallel heating. The data suggest that E_{∥} is balanced by a combination of electron inertia and a parallel gradient of the gyrotropic electron pressure.

  4. The Mechanisms of Electron Acceleration During Multiple X Line Magnetic Reconnection with a Guide Field

    CERN Document Server

    Wang, Huanyu; Huang, Can; Wang, Shui

    2016-01-01

    The interactions between magnetic islands are considered to play an important role in electron acceleration during magnetic reconnection. In this paper, two-dimensional (2-D) particle-in-cell (PIC) simulations are performed to study electron acceleration during multiple X line reconnection with a guide field. The electrons remain almost magnetized, and we can then analyze the contributions of the parallel electric field, Fermi and betatron mechanisms to electron acceleration during the evolution of magnetic reconnection by comparing with a guide-center theory. The results show that with the proceeding of magnetic reconnection, two magnetic islands are formed in the simulation domain. The electrons are accelerated by both the parallel electric field in the vicinity of the X lines and Fermi mechanism due to the contraction of the two magnetic islands. Then the two magnetic islands begin to merge into one, and in such a process electrons can be accelerated by the parallel electric field and betatron mechanisms. ...

  5. Magnetospheric Multiscale Observations of the Electron Diffusion Region of Large Guide Field Magnetic Reconnection

    Science.gov (United States)

    Eriksson, S.; Wilder, F. D.; Ergun, R. E.; Schwartz, S. J.; Cassak, P. A.; Burch, J. L.; Chen, Li-Jen; Torbert, R. B.; Phan, T. D.; Lavraud, B.; hide

    2016-01-01

    We report observations from the Magnetospheric Multiscale (MMS) satellites of a large guide field magnetic reconnection event. The observations suggest that two of the four MMS spacecraft sampled the electron diffusion region, whereas the other two spacecraft detected the exhaust jet from the event. The guide magnetic field amplitude is approximately 4 times that of the reconnecting field. The event is accompanied by a significant parallel electric field (E(sub parallel lines) that is larger than predicted by simulations. The high-speed (approximately 300 km/s) crossing of the electron diffusion region limited the data set to one complete electron distribution inside of the electron diffusion region, which shows significant parallel heating. The data suggest that E(sub parallel lines) is balanced by a combination of electron inertia and a parallel gradient of the gyrotropic electron pressure.

  6. Wake Vortex Field Measurement Program at Memphis, Tennessee: Data Guide

    Science.gov (United States)

    Campbell, S. D.; Dasey, T. J.; Freehart, R. E.; Heinrichs, R. M.; Mathews, M. P.; Perras, G. H.; Rowe, G. S.

    1997-01-01

    Eliminating or reducing current restrictions in the air traffic control system due to wake vortex considerations would yield increased capacity, decreased delays, and cost savings. Current wake vortex separation standards are widely viewed as very conservative under most conditions. However, scientific uncertainty about wake vortex behavior under different atmospheric conditions remains a barrier to development of an adaptive vortex spacing system. The objective of the wake vortex field measurement efforts during December, 1994 and August, 1995 at Memphis, TN were to record wake vortex behavior for varying atmospheric conditions and types of aircraft. This effort is part of a larger effort by the NASA Langley Research Center to develop an Aircraft Vortex Spacing System (AVOSS) as an element of the Terminal Area Productivity (TAP) program. The TAP program is being performed in concert with the FAA Terminal Air Traffic Control Automation (TATCA) program and ATC Automation. Wake vortex behavior was observed using a mobile continuous-wave (CW) coherent laser Doppler radar (lidar) developed at Lincoln Laboratory. This lidar features a number of improvements over previous systems, including the first-ever demonstration of an automatic wake vortex detection and tracking algorithm.

  7. Field trip guide to selected outcrops, Arbuckle Mountains, Oklahoma

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1991-11-17

    The Arbuckle Mountains, named for Brigadier General Matthew Arbuckle, are located in south-central Oklahoma. The formations that comprise the Arbuckle Mountains have been extensively studied for hydrocarbon source rock and reservoir rock characteristics that can be applied to the subsurface in the adjacent Anadarko and Ardmore basins. Numerous reports and guidebooks have been written concerning the Arbuckle Mountains. A few important general publications are provided in the list of selected references. The purpose of this handout is to provide general information on the geology of the Arbuckle Mountains and specific information on the four field trip stops, adapted from the literature. The four stops were at: (1) Sooner Rock and Sand Quarry; (2) Woodford Shale; (3) Hunton Anticline and Hunton Quarry; and (4) Tar Sands of Sulfur Area. As part of this report, two papers are included for more detail: Paleomagnetic dating of basinal fluid migration, base-metal mineralization, and hydrocarbon maturation in the Arbuckle Mountains, Oklahoma and Laminated black shale-bedded chert cyclicity in the Woodford Formation, southern Oklahoma.

  8. Stalled and stall-free performance of axial-flow compressor stage with three inlet-guide-vane and stator-blade settings

    Science.gov (United States)

    Urasek, D. C.; Steinke, R. J.; Cunnan, W. S.

    1977-01-01

    The performance of the first stage of a transonic, multistage compressor was mapped over a range of inlet-guide-vane and stator-blade settings. Both stall-free and deep-stall performance data were obtained. For the settings tested, as stall was encountered and flow was further reduced, a relatively sharp drop in pressure ratio occurred and was followed by a continuing but more gradual reduction in pressure ratio with reduced flow. The position of the stall line on the map of pressure ratio against equivalent weight flow was essentially unaffected over the range of inlet-guide-vane and stator-blade settings.

  9. A wave guide model of lightning currents and their electromagnetic field

    Science.gov (United States)

    Volland, H.

    1980-01-01

    Lightning channels are considered as resonant wave guides in which only standing resonant wave modes can be excited. Two types of discharging currents develop. Type 1 is an aperiodic wave; type 2 is a damped oscillation. The electromagnetic radiation field of both types of currents is calculated and compared with the observation.

  10. Trees of Laos and Vietnam: a field guide to 100 economically or ecologically important species

    NARCIS (Netherlands)

    Sam, Hoang Van; Nanthavong, Khamseng; Keßler, P.J.A.

    2004-01-01

    This field guide to 100 economically or ecologically important tree species from Laos and Vietnam enables the user to identify the included taxa with user-friendly keys. It includes scientific names, botanical descriptions of families, genera, and species. Specific information on distribution, habit

  11. Operation of Wastewater Treatment Plants: A Field Study Training Program. Volume II, Instructor's Guide. Second Edition.

    Science.gov (United States)

    California State Univ., Sacramento. Dept. of Civil Engineering.

    The objective of this instructor's guide is to help provide students with knowledge and skills for employment in the field of wastewater treatment. Included in each chapter outline are: (1) objectives, (2) instructional approach, (3) answers to the objective test in the student's text, and (4) an explanation of these answers. The material…

  12. Operation of Wastewater Treatment Plants: A Field Study Training Program. Volume I, Instructor's Guide. Second Edition.

    Science.gov (United States)

    California State Univ., Sacramento. Dept. of Civil Engineering.

    The objective of this instructor's guide is to help provide students with knowledge and skills for employment in the field of wastewater treatment. Included in each chapter outline are: (1) objectives, (2) instructional approach, (3) answers to the objective test in the student's text, and (4) an explanation of these answers. The material…

  13. Quarry Quest. A Field Trip Guide to the Indiana Limestone District, Monroe and Lawrence Counties, Indiana.

    Science.gov (United States)

    Shewmaker, Sherman N.

    This guide provides information for planning a field trip to the Indiana Limestone District. This district, located in Monroe and Lawrence Counties, Indiana, is responsible for material that has dominated the building-limestone market in the United States for nearly a century. A few of the many well-known buildings using Indiana limestone are the…

  14. Trees of Laos and Vietnam: a field guide to 100 economically or ecologically important species

    NARCIS (Netherlands)

    Sam, Hoang Van; Nanthavong, Khamseng; Keßler, P.J.A.

    2004-01-01

    This field guide to 100 economically or ecologically important tree species from Laos and Vietnam enables the user to identify the included taxa with user-friendly keys. It includes scientific names, botanical descriptions of families, genera, and species. Specific information on distribution, habit

  15. Distinguishing among Declarative, Descriptive and Causal Questions to Guide Field Investigations and Student Assessment

    Science.gov (United States)

    Odom, Arthur Louis; Bell, Clare V.

    2011-01-01

    Teachers as well as students often have difficulty formulating good research questions because not all questions lend themselves to scientific investigation. The following is a guide for high-school and college life-science teachers to help students define question types central to biological field studies. The mayfly nymph was selected as the…

  16. Measurements of the unsteady flow field within the stator row of a transonic axial-flow fan. 1: Measurement and analysis technique

    Science.gov (United States)

    Suder, K. L.; Hathaway, M. D.; Okiishi, T. H.; Strazisar, A. J.; Adamczyk, J. J.

    1987-01-01

    This two-part paper presents laser anemometer measurements of the unsteady velocity field within the stator row of a transonic axial-flow fan. The objective is to provide additional insight into unsteady blade-row interactions within high speed compressors which affect stage efficiency, energy transfer, and other design considerations. Part 1 describes the measurement and analysis techniques used for resolving the unsteady flow field features. The ensemble-average and variance of the measured velocities are used to identify the rotor wake generated and unresolved unsteadiness, respectively. (Rotor wake generated unsteadiness refers to the unsteadiness generated by the rotor wake velocity deficit and the term unresolved unsteadiness refers to all remaining contributions to unsteadiness such as vortex shedding, turbulence, mass flow fluctuations, etc.). A procedure for calculating auto and cross correlations of the rotor wake generated and unresolved unsteady velocity fluctuations is described. These unsteady-velocity correlations have significance since they also result from a decomposition of the Navier-Stokes equations. This decomposition of the Navier-Stokes equations resulting in the velocity correlations used to describe the unsteady velocity field will also be outlined in this paper.

  17. Measurements of the unsteady flow field within the stator row of a transonic axial-flow fan. I - Measurement and analysis technique

    Science.gov (United States)

    Suder, K. L.; Strazisar, A. J.; Adamczyk, J. J.; Hathaway, M. D.; Okiishi, T. H.

    1987-01-01

    This two-part paper presents laser anemometer measurements of the unsteady velocity field within the stator row of a transonic axial-flow fan. The objective is to provide additional insight into unsteady blade-row interactions within highspeed compressors which affect stage efficiency, energy transfer, and other design considerations. Part 1 describes the measurement and analysis techniques used for resolving the unsteady flow field features. The ensemble-average and variance of the measured velocities are used to identify the rotor wake generated and unresolved unsteadiness, respectively. (Rotor wake generated unsteadiness refers to the unsteadiness generated by the rotor wake velocity deficit and the term unresolved unsteadiness refers to all remaining contributions to unsteadiness such as vortex shedding, turbulence, mass flow fluctutions, etc.). A procedure for calculating auto and cross correlations of the rotor wake generated and unresolved unsteady velocity fluctuations is described. These unsteady-velocity correlations have significance since they also result from a decomposition of the Navier-Stokes equations. This decomposition of the Navier-Stokes equations resulting in the velocity correlations used to describe the unsteady velocity field will also be outlined in this paper.

  18. Electron beam guiding by external magnetic fields in imploded fuel plasma

    Science.gov (United States)

    Johzaki, T.; Sentoku, Y.; Nagatomo, H.; Sunahara, A.; Sakagami, H.; Fujioka, S.; Shiraga, H.; Endo, T.; FIREX project Group

    2016-05-01

    For enhancing the core heating efficiency in fast ignition laser fusion, we proposed the fast electron beam by externally-applied the kilo-tesla (kT) class longitudinal magnetic field. We evaluated the imploded core and the magnetic field profiles formed through the implosion dynamics by resistive MHD radiation hydro code. Using those profiles, the guiding effect was evaluated by fast electron transport simulations, which shows that in addition to the feasible field configuration (moderate mirror ratio), the kT-class magnetic field is required at the fast electron generation point. In this case, the significant enhancement in heating efficiency is expected.

  19. Improved analytical model for the field of index-guiding microstructured optical fibers

    Science.gov (United States)

    Sharma, Dinesh Kumar; Sharma, Anurag

    2016-05-01

    We present an improved version of our earlier developed analytical field model for the fundamental mode of index-guiding microstructured optical fibers (MOFs), to obtain better accuracy in the simulated results. Using this improved field model, we have studied the splice losses between an MOF and a traditional step-index single-mode fiber (SMF). Comparisons with available experimental and numerical simulation results have also been included.

  20. Extension of the characteristic field - taking into account the influence of hub and casing boundary layers in characteristic field calculations for axial blowers. Final report; Kennfelderweiterung - Erfassung des Einflusses der Naben- und Gehaeusegrenzschichten zur Kennfeldberechnung von Axialventilatoren. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Rohdenburg, M.; Saathoff, H.

    2002-07-01

    Research of TU Brunswick University showed that the performance of single-stage axial blowers is influenced significantly by 3D loss while profile loss is insignificant. Calculation methods should take account of this fact. A characteristic field calculation method was therefore developed based on practical measurements and on a method presented in an earlier publication. New correlations for side wall boundary layer parameters for single-stage axial blowers could be established by this method. This provides a modified characteristic field method and new correlations for calculating characteristic fields with rotor adjustment angles of {+-}15 already in the design stage. The research project was concluded successfully. (orig.) [German] An der TU-Braunschweig in juengerer Zeit durchgefuehrte Forschungsarbeiten zeigen, dass das Betriebsverhalten von einstufigen Ventilatoren axialer Bauart erheblich von den 3D-Verlusten gepraegt wird, die Profilverluste dagegen nur eine kleine Rolle spielen. Ein Kennfeld-Nachrechnungsverfahren sollte daher neben den Profilgrenzschichten (2D-Verluste) auch die Naben- und Gehaeusegrenzschichten (3D-Verluste) in korrekter Weise beruecksichtigen. Zu dessen Entwicklung wurden Grenzschichtkenngroessen der Naben- und Gehaeusegrenzschichten von drei Versuchsventilatoren an einer Reihe von ausgewaehlten Betriebspunkten ermittelt. Bei den Messungen handelte es sich um Sonden- und Hitzdrahtmessungen in den Zu- und Nachlaeufen der Beschaufelungen und um Druckverteilungsmessungen im Gehaeusebereich oberhalb des Rotors; bei ebenfalls noetigen Berechnungen der Geschwindigkeitsverteilungen handelte es sich um einfache Rechnungen mit Hilfe der Gleichgewichtsbedingung. Das Kennlinienberechnungsverfahren wurde in Anlehnung an ein vorhandenes Verfahren aus der Literatur entwickelt. Aus den im Vorhaben gewonnenen Messergebnissen konnten neue Korrelationen der Seitenwandgrenzschichtparameter fuer einstufige Axialventilatoren abgeleitet werden. Damit steht

  1. The effect of the tangential angle of the guide vanes on the flow structure and characteristics of an axial-flow turbine stage

    Science.gov (United States)

    Lapshin, K. L.; Fomin, V. S.; Avrutov, E. A.; Kirillov, V. I.

    1985-07-01

    It is demonstrated that the direct axisymmetric problem can be efficiently used for calculating three-dimensional flow and characteristics of turbine stages, both regular and those having a low thrust ratio gradient. It is further shown that the performance characteristics of turbine stages can be improved through the use of tangentially tilted guide vanes.

  2. THE MECHANISMS OF ELECTRON ACCELERATION DURING MULTIPLE X LINE MAGNETIC RECONNECTION WITH A GUIDE FIELD

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huanyu; Lu, Quanming; Huang, Can; Wang, Shui, E-mail: qmlu@ustc.edu.cn [CAS Key Lab of Geospace Environment, Department of Geophysics and Planetary Science, University of Science and Technology of China, Hefei 230026 (China)

    2016-04-20

    The interactions between magnetic islands are considered to play an important role in electron acceleration during magnetic reconnection. In this paper, two-dimensional particle-in-cell simulations are performed to study electron acceleration during multiple X line reconnection with a guide field. Because the electrons remain almost magnetized, we can analyze the contributions of the parallel electric field, Fermi, and betatron mechanisms to electron acceleration during the evolution of magnetic reconnection through comparison with a guide-center theory. The results show that with the magnetic reconnection proceeding, two magnetic islands are formed in the simulation domain. Next, the electrons are accelerated by both the parallel electric field in the vicinity of the X lines and the Fermi mechanism due to the contraction of the two magnetic islands. Then, the two magnetic islands begin to merge into one, and, in such a process, the electrons can be accelerated by both the parallel electric field and betatron mechanisms. During the betatron acceleration, the electrons are locally accelerated in the regions where the magnetic field is piled up by the high-speed flow from the X line. At last, when the coalescence of the two islands into one big island finishes, the electrons can be further accelerated by the Fermi mechanism because of the contraction of the big island. With the increase of the guide field, the contributions of the Fermi and betatron mechanisms to electron acceleration become less and less important. When the guide field is sufficiently large, the contributions of the Fermi and betatron mechanisms are almost negligible.

  3. 可调导叶式轴流泵马鞍区水力特性试验研究%Experimental study on hydraulic performance of saddle zone in axial flow pump with adjustable guide vane

    Institute of Scientific and Technical Information of China (English)

    钱忠东; 王凡; 王志远; 周皖

    2013-01-01

    In order to analyze the effects of adjustable guide vane (AGV) on axial pumps working in saddle zone,in the hope of optimizing adjusting laws,performance test of a new axial-flow pump with AGV was carried out on the pump test bed.Q-H,Q-ηand Q-P curves at different guide vane angles were obtained.The effects of AGV on hydraulic performance of the model pump in saddle zone were analyzed.The results show that,at the same flow rate,head and efficiency of axial flow pump increase as guide vane angle is adjusted from 0° to-5°.With AGV,the separation vortex in the flow channel is suppressed effectively; flow regime at pump outlet is optimized obviously; kinetic energy recovery rate is improved.Head and efficiency of the pump are improved by 0.15 m (0.046 9Hd) and 1.93% respectively.The critical flow discharge is decreased by 0.004 94 m3/s and the range of saddle-shaped zone is narrowed by 6.64%,broadening the range of stable working zone.At guide vane angle of-5°-0°,the shaft power changes little.In this experiment,the best values of hydraulic performance obtained are at-5° guide vane angle,but they can be further improved.%为了分析不同导叶安放角对轴流泵在马鞍区工况运行时的影响,探究导叶角度的优化规律,在水泵模型试验台上,对一种新型可调导叶式轴流泵的外特性进行测试,得到不同导叶安放角下H-Q、η-Q、P-Q曲线,分析了导叶安放角对轴流泵马鞍区水力特性的影响.试验结果表明:相同流量工况下轴流泵的扬程和效率随着导叶安放角由0°向-5 °调节而增大,调节导叶安放角,能够有效抑制叶片背面脱流旋涡的扩散,显著改善轴流泵出口的流态,提高动能回收的比例;在马鞍区工况下,扬程最大提升0.15m,为设计扬程的4.69%,效率最大提升1.93%;马鞍区起始点流量向小流量偏移了0.004 94 m3/s,马鞍区范围减小了6.64%,拓宽了轴流泵稳定运行的区域;导叶安放角在-5°~0°的

  4. Guiding Neutral Atoms with Two Current-Carrying Wires and a Vertical Bias Field on the Atom Chip

    Institute of Scientific and Technical Information of China (English)

    KE Min; YAN Bo; LI Xiao-Lin; WANG Yu-Zhu

    2008-01-01

    @@ We demonstrate the guiding of neutral atoms with two parallel microfabricated current-carrying wires on the atom chip and a verticai magnetic bias field.The atoms are guided along a magnetic field minimum parallel to the current-carrying wires and confined in the other two directions.We describe in detail how the precooled atoms are efficiently loaded into the two-wire guide.

  5. Quantum states of neutral atoms bound in the magnetic field of a Kepler-guide

    Institute of Scientific and Technical Information of China (English)

    HE Ming; WANG Jin; ZHAN Ming-sheng

    2003-01-01

    The spectrum and the wave function of neutral atoms in the magnetic field of a Kepler-guide are presented by reducing a two-dimensional stationary Schrdinger equation to a one-dimensional hydrogen atom in Rydberg states. In addition, we set the scale for the atomic orbits and binding energy i n the quantum regime, and compare it with the outcome of the experiment. At the same time, we find that reducing the current and radius of the wire properly wil l increase the loading efficiency of the Kepler-guide.

  6. A field induced guide-antiguide modulator of GaAs-AlGaAs

    Science.gov (United States)

    Huang, T. C.; Chung, Y.; Young, D. B.; Dagli, N.; Coldren, L. A.

    1991-01-01

    A guide-antiguide modulator of GaAs-AlGaAs using the electric-field-induced waveguide concept was demonstrated. The device was formed with a central waveguide electrode sandwiched between two antiguide electrodes on the surface of a p-i-n multiple quantum well (MQW). Switching between lateral guiding and antiguiding was accomplished by reverse biasing either the central electrode or the adjacent electrodes to increase the index beneath these respective regions. The on-off ratio was measured to be 20:1 with a propagation loss of the on-state of about 5 dB/mm.

  7. Apps for Angiosperms: The Usability of Mobile Computers and Printed Field Guides for UK Wild Flower and Winter Tree Identification

    Science.gov (United States)

    Stagg, Bethan C.; Donkin, Maria E.

    2017-01-01

    We investigated usability of mobile computers and field guide books with adult botanical novices, for the identification of wildflowers and deciduous trees in winter. Identification accuracy was significantly higher for wildflowers using a mobile computer app than field guide books but significantly lower for deciduous trees. User preference…

  8. Prediction and near-field observation of skull-guided acoustic waves

    CERN Document Server

    Estrada, Héctor; Razansky, Daniel

    2016-01-01

    Ultrasound waves propagating in water or soft biological tissue are strongly reflected when encountering the skull, which limits the use of ultrasound-based techniques in transcranial imaging and therapeutic applications. Current knowledge on the acoustic properties of the cranial bone is restricted to far-field observations, leaving its near-field properties unexplored. We report on the existence of skull-guided acoustic waves, which was herein confirmed by near-field measurements of optoacoustically-induced responses in ex-vivo murine skulls immersed in water. Dispersion of the guided waves was found to reasonably agree with the prediction of a multilayered flat plate model. It is generally anticipated that our findings may facilitate and broaden the application of ultrasound-mediated techniques in brain diagnostics and therapy.

  9. Cancellation properties in Hall magnetohydrodynamics with a strong guide magnetic field.

    Science.gov (United States)

    Martin, L N; De Vita, G; Sorriso-Valvo, L; Dmitruk, P; Nigro, G; Primavera, L; Carbone, V

    2013-12-01

    We present a signed measure analysis of compressible Hall magnetohydrodynamic turbulence with an external guide field. Signed measure analysis allows us to characterize the scaling behavior of the sign-oscillating flow structures and their geometrical properties (fractal dimensions of structures). A reduced numerical model, valid when a strong guide magnetic field is present, is used here. In order to discuss the effect of the Hall term, different values for the ion skin depth are considered in the simulations. Results show that as the Hall term is increased, the fractal dimension of the current and vorticity sheets decreases. This observation, together with previous analysis of the same fields, provides a comprehensive description of the effect of the Hall force on the formation of structures. Two main processes are identified, namely, the widening and unraveling of the sheets.

  10. 3D MHD Simulations of Laser Plasma Guiding in Curved Magnetic Field

    Science.gov (United States)

    Roupassov, S.; Rankin, R.; Tsui, Y.; Capjack, C.; Fedosejevs, R.

    1999-11-01

    The guiding and confinement of laser produced plasma in a curved magnetic field has been investigated numerically. These studies were motivated by experiments on pulsed laser deposition of diamond-like films [1] in which a 1kG magnetic field in a curved solenoid geometry was utilized to steer a carbon plasma around a curved trajectory and thus to separate it from unwanted macroparticles produced by the laser ablation. The purpose of the modeling was to characterize the plasma dynamics during the propagation through the magnetic guide field and to investigate the effect of different magnetic field configurations. A 3D curvilinear ADI code developed on the basis of an existing Cartesian code [2] was employed to simulate the underlying resistive one-fluid MHD model. Issues such as large regions of low background density and nonreflective boundary conditions were addressed. Results of the simulations in a curved guide field will be presented and compared to experimental results. [1] Y.Y. Tsui, D. Vick and R. Fedosejevs, Appl. Phys. Lett. 70 (15), pp. 1953-57, 1997. [2] R. Rankin, and I. Voronkov, in "High Performance Computing Systems and Applications", pp. 59-69, Kluwer AP, 1998.

  11. Experimental Investigation on the Influence of Axial Magnetic Field Distribution on Resisting the Constriction of a High-Current Vacuum Arc

    Institute of Scientific and Technical Information of China (English)

    SHI Zongqian; LIU Zhigang; JIA Shenli; SONG Xiaochuan; WANG Lijun

    2009-01-01

    Effect of the axial magnetic field (AMF) on resisting the constriction of a high-current vacuum arc is studied in this paper. Two typical AMF distributions were investigated, i.e., the traditional bell-shaped AMF, and the saddle-shaped AMF. Experiments were conducted in a detachable vacuum chamber with a rms arc current in the range of 10 kA to 25 kA. The arc column was photographed by a high-speed digital camera with an exposure time of 2 microseconds. The constriction of the vacuum arc was compared by processing the images of the arc column under the two different field configurations and numerically determining the dimensions of the arc column near the electrodes. It was also confirmed that the AMF distribution had a signifcant influence on its effectiveness in resisting arc constriction, Furthermore, the AMF strength near the periphery of the arc is more influential than that at the centre of the electrodes in resisting arc constriction.

  12. Numerical simulation of breakup and detachment of an axially stretching Newtonian liquid bridge with a moving contact line phase field method

    Indian Academy of Sciences (India)

    KISHORE SINGH PATEL; RATNESH K SHUKLA

    2017-04-01

    The extensional, breakup and detachment dynamics of an axially stretching Newtonian liquid bridge are investigated numerically with a dynamic domain multiphase incompressible flow solver. The multiphase flow solver employs a Cahn–Hilliard phase field model to describe the evolution of the diffuse interfaceseparating the liquid bridge fluid from the surrounding medium. The governing axisymmetric Navier–Stokes and Cahn–Hilliard phase field equations are discretized on a continuously expanding domain, the boundaries ofwhich coincide with the planar solid surfaces containing the liquid bridge. The entire formulation, including the fast pressure correction for high density ratios and the semi-implicit discretization that overcomes the numerical stiffness of the fourth-order spatial operators, is performed on a fixed simplified computational domain using time-dependent transformation. Simulations reveal that the dynamic domain interface capturing technique effectively captures the deformation dynamics of the stretching liquid bridge, including the capillary waveformation, necking and interface evolution post breakup and detachment. It is found that the liquid bridge detachment is strongly influenced by the contact angle prescribed at the stationary and moving solid surfaces. At relatively small pulling speeds, the entire liquid is found to preferentially adhere to the less hydrophobic surface.When the prescribed contact angles are equal, however, the liquid bridge undergoes complete detachment so that no liquid resides either on the stationary or on the moving solid surface.

  13. Effects of a Kind of Non-smooth Blade on the Unsteady Flow Field at the Exit of an Axial Fan

    Institute of Scientific and Technical Information of China (English)

    Hongwei MA; Jibo GUO

    2008-01-01

    An experimental investigation of effects of a kind of streamwise-grooved blade on the unsteady flow field at an exit of an axial-flow fan was performed. The flow field at 25% chord downstream from the trailing edge at hub was measured using a fast-response five-hole pressure probe at different mass-flow conditions. The unsteady flow of the grooved blades was compared with that of the smooth blades. The measurement results indicate that: (1)the grooved blades restrain the velocity fluctuation and the pressure fluctuation by modulating the blade boundary layers, which contributes to the flow loss reduction in the hub region and in the rotor wake region at the design condition; (2) the atream-wise grooves play an important role in restraining the radial migration in the blade boundary layer and abating the tip flow mixing, which contributes to the flow loss reduction in the tip region at the design condition; (3) at the near stall condition, the grooved surface can not reduce the flow loss, even increase the loss nearby when the separation happens in the blade boundary layer.

  14. Effects of a kind of non-smooth blade on the unsteady flow field at the exit of an axial fan

    Science.gov (United States)

    Hongwei, Ma; Jibo, Guo

    2008-03-01

    An experimental investigation of effects of a kind of streamwise-grooved blade on the unsteady flow field at an exit of an axial-flow fan was performed. The flow field at 25% chord downstream from the trailing edge at hub was measured using a fast-response five-hole pressure probe at different mass-flow conditions. The unsteady flow of the grooved blades was compared with that of the smooth blades. The measurement results indicate that: (1) the grooved blades restrain the velocity fluctuation and the pressure fluctuation by modulating the blade boundary layers, which contributes to the flow loss reduction in the hub region and in the rotor wake region at the design condition; (2) the stream-wise grooves play an important role in restraining the radial migration in the blade boundary layer and abating the tip flow mixing, which contributes to the flow loss reduction in the tip region at the design condition; (3) at the near stall condition, the grooved surface can not reduce the flow loss, even in-crease the loss nearby when the separation happens in the blade boundary layer.

  15. Wide band noise: Calculation of the wide-band aeroacoustic noise spectrum of axial blower rotors on the basis of flow field variables. With user info on the program 'SIBNOISE-AX'. Final report; Breitbandlaerm - Berechnung des breitbandigen aeroakustischen Geraeuschspektrums von Axialventilatorlaufraedern aus Stromfeldgroessen. Mit Benutzeranleitung zum Programm 'SIBNOISE-AX'. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Carolus, T.; Schneider, M.

    2002-10-01

    A computer program for predicting the wide-band noise spectrom of axial blower rotors from flow field variables was developed. First, a bibliographic search was carried out on current methods of noise prediction. The main input parameters of the selected methods were varied systematically in the sense of a sensitivity analysis in order to check the plausibility of the results and assess the accuracy required of the input parameters. The selected methods were implemented in a user-friendly PC program ('SIBNOISE-AX'). The methods and the computer program were tested using the example of two blowers, i.e. a low-pressure and a high-pressure axial blower. Both blowers were calculated without guide wheels as the research project focused on rotor wheel noise only. Aerodynamic and acoustic data were obtained in a standard test stand in order to provide a data base. Time-averaged flow fields in the rotor wheels were calculated using a commercial CFD code, and parameters like boundary layer thickness and relevant velocities in the blade region were derived which - in addition to simple estimates - were used as input parameters in the noise prediction methods. The results provided by the calculations differed depending on the method employed, but some methods provided results that were in good agreement with the measurements. Their accuracy was sufficient even when the input parameters were only estimated and could be improved further by using the numerically calculated flow field parameters. The research project was thus completed successfully.

  16. Geologic field-trip guide to Medicine Lake Volcano, northern California, including Lava Beds National Monument

    Science.gov (United States)

    Donnelly-Nolan, Julie M.; Grove, Timothy L.

    2017-08-17

    Medicine Lake volcano is among the very best places in the United States to see and walk on a variety of well-exposed young lava flows that range in composition from basalt to rhyolite. This field-trip guide to the volcano and to Lava Beds National Monument, which occupies part of the north flank, directs visitors to a wide range of lava flow compositions and volcanic phenomena, many of them well exposed and Holocene in age. The writing of the guide was prompted by a field trip to the California Cascades Arc organized in conjunction with the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) quadrennial meeting in Portland, Oregon, in August of 2017. This report is one of a group of three guides describing the three major volcanic centers of the southern Cascades Volcanic Arc. The guides describing the Mount Shasta and Lassen Volcanic Center parts of the trip share an introduction, written as an overview to the IAVCEI field trip. However, this guide to Medicine Lake volcano has descriptions of many more stops than are included in the 2017 field trip. The 23 stops described here feature a range of compositions and volcanic phenomena. Many other stops are possible and some have been previously described, but these 23 have been selected to highlight the variety of volcanic phenomena at this rear-arc center, the range of compositions, and for the practical reason that they are readily accessible. Open ground cracks, various vent features, tuffs, lava-tube caves, evidence for glaciation, and lava flows that contain inclusions and show visible evidence of compositional zonation are described and visited along the route.

  17. Aerodynamic performance of axial-flow fan stage operated at nine inlet guide vane angles. [to be used on vertical lift aircraft

    Science.gov (United States)

    Moore, R. D.; Reid, L.

    1979-01-01

    The overall performance of a fan stage with nine inlet guide vane angle settings is presented. These data were obtained over the stable flow range at speeds from 60 to 120 percent of design for vane setting angles from -25 to 42.5 degrees. At design speed and design inlet guide vane angle, the stage has a peak efficiency of 0.892 at a pressure ratio of 1.322 and a flow of 25.31 kg/s. The stall margin based on peak efficiency and stall was 20 percent. Based on an operating line passing through the peak efficiency point at the design setting angle, the useful operating range of the stage at design speed is limited by stall at the positive setting angles and by choke at the negative angles. At design the calculated static thrust along the operating line varied from 68 to 114 percent of that obtained at design setting angle.

  18. Self-Guided Field Explorations: Integrating Earth Science into Students' Lives

    Science.gov (United States)

    Kirkby, K. C.; Kirkby, S.

    2013-12-01

    Self-guided field explorations are a simple way to transform an earth science class into a more pedagogically effective experience. Previous experience demonstrated that self-guided student explorations of museum and aquarium exhibits were both extremely popular and remarkably effective. That success led our program to test an expansion of the concept to include self-guided student explorations in outdoor field settings. Preliminary assessment indicates these self-guided field explorations are nearly as popular with students as the museum and aquarium explorations and are as pedagogically effective. Student gains on post-instruction assessment match or exceed those seen in instructor-assisted, hands-on, small group laboratory activities and completely eclipse gains achieved by traditional lecture instruction. As importantly, self-guided field explorations provide a way to integrate field experiences into large enrollment courses where the sheer scale of class trips makes them logistically impossible. This expands course breadth, integrating new topics that could not be as effectively covered by the original class structure. Our introductory program assessed two models of self-guided field explorations. A walking/cycling exploration of the Saint Anthony Falls area, a mile from campus, focuses on the intersections of geological processes with human history. Students explore the geology behind the waterfalls' evolution as well as its subsequent social and economic impacts on human history. A second exploration focuses on the campus area geology, including its building stones as well as its landscape evolution. In both explorations, the goal was to integrate geology with the students' broader understanding of the world they live in. Although the explorations' creation requires a significant commitment, once developed, self-guided explorations are surprisingly low maintenance. These explorations provide a model of a simple, highly effective pedagogical tool that is

  19. Laser-guided energetic discharges over large air gaps by electric-field enhanced plasma filaments

    Science.gov (United States)

    Théberge, Francis; Daigle, Jean-François; Kieffer, Jean-Claude; Vidal, François; Châteauneuf , Marc

    2017-01-01

    Recent works on plasma channels produced during the propagation of ultrashort and intense laser pulses in air demonstrated the guiding of electric discharges along the laser path. However, the short plasma lifetime limits the length of the laser-guided discharge. In this paper, the conductivity and lifetime of long plasma channels produced by ultrashort laser pulses is enhanced efficiently over many orders of magnitude by the electric field of a hybrid AC-DC high-voltage source. The AC electric pulse from a Tesla coil allowed to stimulate and maintain the highly conductive channel during few milliseconds in order to guide a subsequent 500 times more energetic discharge from a 30-kV DC source. This DC discharge was laser-guided over an air gap length of two metres, which is more than two orders of magnitude longer than the expected natural discharge length. Long plasma channel induced by laser pulses and stimulated by an external high-voltage source opens the way for wireless and efficient transportation of energetic current pulses over long air gaps and potentially for guiding lightning. PMID:28053312

  20. Laser-guided energetic discharges over large air gaps by electric-field enhanced plasma filaments

    Science.gov (United States)

    Théberge, Francis; Daigle, Jean-François; Kieffer, Jean-Claude; Vidal, François; Châteauneuf, Marc

    2017-01-01

    Recent works on plasma channels produced during the propagation of ultrashort and intense laser pulses in air demonstrated the guiding of electric discharges along the laser path. However, the short plasma lifetime limits the length of the laser-guided discharge. In this paper, the conductivity and lifetime of long plasma channels produced by ultrashort laser pulses is enhanced efficiently over many orders of magnitude by the electric field of a hybrid AC-DC high-voltage source. The AC electric pulse from a Tesla coil allowed to stimulate and maintain the highly conductive channel during few milliseconds in order to guide a subsequent 500 times more energetic discharge from a 30-kV DC source. This DC discharge was laser-guided over an air gap length of two metres, which is more than two orders of magnitude longer than the expected natural discharge length. Long plasma channel induced by laser pulses and stimulated by an external high-voltage source opens the way for wireless and efficient transportation of energetic current pulses over long air gaps and potentially for guiding lightning.

  1. Contributions of the secondary jet to the maximum tangential velocity and to the collection efficiency of the fixed guide vane type axial flow cyclone dust collector

    Science.gov (United States)

    Ogawa, Akira; Anzou, Hideki; Yamamoto, So; Shimagaki, Mituru

    2015-11-01

    In order to control the maximum tangential velocity Vθm(m/s) of the turbulent rotational air flow and the collection efficiency ηc (%) using the fly ash of the mean diameter XR50=5.57 µm, two secondary jet nozzles were installed to the body of the axial flow cyclone dust collector with the body diameter D1=99mm. Then in order to estimate Vθm (m/s), the conservation theory of the angular momentum flux with Ogawa combined vortex model was applied. The comparisons of the estimated results of Vθm(m/s) with the measured results by the cylindrical Pitot-tube were shown in good agreement. And also the estimated collection efficiencies ηcth (%) basing upon the cut-size Xc (µm) which was calculated by using the estimated Vθ m(m/s) and also the particle size distribution R(Xp) were shown a little higher values than the experimental results due to the re-entrainment of the collected dust. The best method for adjustment of ηc (%) related to the contribution of the secondary jet flow is principally to apply the centrifugal effect Φc (1). Above stated results are described in detail.

  2. How Does Collisionless Magnetic Reconnection Work in the Presence of a Guide Magnetic Field?

    Science.gov (United States)

    Hesse, Michael

    2006-01-01

    The dissipation mechanism of guide field magnetic reconnection remains a subject of intense scientific interest. On one hand, one set of recent studies have shown that particle inertia-based processes, which include thermal and bulk inertial effects, provide the reconnection electric field in the diffusion region. On the other hand, a second set of studies emphasizes the role of wave-particle interactions in providing anomalous resistivity in the diffusion region. In this presentation, we present analytical theory results, as well as 2.5 and three-dimensional PIC simulations of guide-field magnetic reconnection. We will show that diffusion region scale sizes in moderate and large guide field cases are determined by electron Larmor radii, and that analytical estimates of diffusion region dimensions need to include description of the heat flux tensor. The dominant electron dissipation process appears to be based on thermal electron inertia, expressed through nongyrotropic electron pressure tensors. We will argue that this process remains viable in three dimensions by means of a detailed comparison of high resolution particle-in-cell simulations.

  3. MiDAS: the field guide to the microbes of activated sludge.

    Science.gov (United States)

    McIlroy, Simon Jon; Saunders, Aaron Marc; Albertsen, Mads; Nierychlo, Marta; McIlroy, Bianca; Hansen, Aviaja Anna; Karst, Søren Michael; Nielsen, Jeppe Lund; Nielsen, Per Halkjær

    2015-01-01

    The Microbial Database for Activated Sludge (MiDAS) field guide is a freely available online resource linking the identity of abundant and process critical microorganisms in activated sludge wastewater treatment systems to available data related to their functional importance. Phenotypic properties of some of these genera are described, but most are known only from sequence data. The MiDAS taxonomy is a manual curation of the SILVA taxonomy that proposes a name for all genus-level taxa observed to be abundant by large-scale 16 S rRNA gene amplicon sequencing of full-scale activated sludge communities. The taxonomy can be used to classify unknown sequences, and the online MiDAS field guide links the identity to the available information about their morphology, diversity, physiology and distribution. The use of a common taxonomy across the field will provide a solid foundation for the study of microbial ecology of the activated sludge process and related treatment processes. The online MiDAS field guide is a collaborative workspace intended to facilitate a better understanding of the ecology of activated sludge and related treatment processes--knowledge that will be an invaluable resource for the optimal design and operation of these systems. © The Author(s) 2015. Published by Oxford University Press.

  4. Field-trip guides to selected volcanoes and volcanic landscapes of the western United States

    Science.gov (United States)

    ,

    2017-06-23

    The North American Cordillera is home to a greater diversity of volcanic provinces than any comparably sized region in the world. The interplay between changing plate-margin interactions, tectonic complexity, intra-crustal magma differentiation, and mantle melting have resulted in a wealth of volcanic landscapes.  Field trips in this guide book collection (published as USGS Scientific Investigations Report 2017–5022) visit many of these landscapes, including (1) active subduction-related arc volcanoes in the Cascade Range; (2) flood basalts of the Columbia Plateau; (3) bimodal volcanism of the Snake River Plain-Yellowstone volcanic system; (4) some of the world’s largest known ignimbrites from southern Utah, central Colorado, and northern Nevada; (5) extension-related volcanism in the Rio Grande Rift and Basin and Range Province; and (6) the eastern Sierra Nevada featuring Long Valley Caldera and the iconic Bishop Tuff.  Some of the field trips focus on volcanic eruptive and emplacement processes, calling attention to the fact that the western United States provides opportunities to examine a wide range of volcanological phenomena at many scales.The 2017 Scientific Assembly of the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) in Portland, Oregon, was the impetus to update field guides for many of the volcanoes in the Cascades Arc, as well as publish new guides for numerous volcanic provinces and features of the North American Cordillera. This collection of guidebooks summarizes decades of advances in understanding of magmatic and tectonic processes of volcanic western North America. These field guides are intended for future generations of scientists and the general public as introductions to these fascinating areas; the hope is that the general public will be enticed toward further exploration and that scientists will pursue further field-based research.

  5. Light axial vector mesons

    CERN Document Server

    Chen, Kan; Liu, Xiang; Matsuki, Takayuki

    2015-01-01

    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 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 to further experimental exploration of the observed and predicted axial vector mesons.

  6. Natural guide-star processing for wide-field laser-assisted AO systems

    CERN Document Server

    Correia, Carlos M; Conan, Jean-Marc; Petit, Cyril; Sauvage, Jean-Francois; Fusco, Thierry; Vernet, Joel D R; Thatte, Niranjan

    2016-01-01

    Sky-coverage in laser-assisted AO observations largely depends on the system's capability to guide on the faintest natural guide-stars possible. Here we give an up-to-date status of our natural guide-star processing tailored to the European-ELT's visible and near-infrared (0.47 to 2.45 {\\mu}m) integral field spectrograph - Harmoni. We tour the processing of both the isoplanatic and anisoplanatic tilt modes using the spatio-angular approach whereby the wave-front is estimated directly in the pupil plane avoiding a cumbersome explicit layered estimation on the 35-layer profiles we're currently using. Taking the case of Harmoni, we cover the choice of wave-front sensors, the number and field location of guide-stars, the optimised algorithms to beat down angular anisoplanatism and the performance obtained with different temporal controllers under split high-order/low-order tomography or joint tomography. We consider both atmospheric and far greater telescope wind buffeting disturbances. In addition we provide the...

  7. Performance of Axial-Flow Supersonic Compressor of XJ55-FF-1 Turbojet Engine. II - Performance of Inlet Guide Vanes as Separate Component

    Science.gov (United States)

    Graham, Robert C.; Tysl, Edward R.

    1949-01-01

    The inlet wide vanes for the supersonic compressor of the XJ55-FF-1 engine were studied as a separate component in order to determine the performance prior to installation in the compressor test rig. Turning angles approached design values, and increased approximately to through the inlet Mach number range from 0.30 to choke. A sharp break in turning angle was experienced when the choke condition was reached. The total-pressure loss through the guide vanes was approximately 1 percent for the unchoked conditions and from 5 to 6 percent when choked.

  8. Field guide on reduction and disposal of waste from oil refineries and marketing installations

    Energy Technology Data Exchange (ETDEWEB)

    Dando, D.A.J.; Bossand, B.; Lilie, R.H.; Ooms, A.C.; Sutherland, H.

    1990-07-01

    The field guide has been written primarily for those in the oil refining and marketing industry who have responsibility for the management of waste and its disposal. It should also provide useful information to the authorities who exercise legal control over these activities. It lists the types of wastes commonly encountered in the industry and highlights techniques for minimizing the quantities generated. Guidance is given on the methods of pre-treatment and disposal, together with information on how to select and monitor waste facilities and contractors, to ensure a high quality and safe disposal operation. Information is also provided on documentation and labelling of waste cargoes, and reference is made to legislation and sources of additional information. While use of the field guide cannot guarantee a problem-free operation, it will minimize the risks involved in disposal of waste materials from oil industry installations.

  9. Modeling colliding beams with an element by element representation of the storage ring guide field

    Directory of Open Access Journals (Sweden)

    D. L. Rubin

    2006-01-01

    Full Text Available A detailed model of the Cornell Electron Storage Ring (CESR guide field, including beam-beam interaction computed in the weak-strong regime, is the basis for a multiturn simulation of luminosity. The simulation reproduces the dependence of luminosity on bunch current that is measured in the storage ring, at both high-energy (5.3   GeV/beam and in the wiggler-dominated low energy (CESR-c configuration (1.9   GeV/beam. Dynamics are determined entirely by the physics of propagation through the individual guide field elements with no free parameters. Energy dependence of the compensation of the transverse coupling introduced by the experimental solenoid is found to significantly degrade specific luminosity. The simulation also indicates a strong dependence of limiting beam-beam tune shift parameter on the geometric mean of synchrotron tune and bunch length.

  10. Study of $ \\bar{p} $ and $ \\bar{n} $ annihilations at LEAR with OBELIX, a large acceptance and high resolution detector based on the Open Axial Field Spectrometer

    CERN Multimedia

    2002-01-01

    % PS201 Study of $\\bar{p}$ and $\\bar{n}$ annihilations at LEAR with OBELIX, a large acceptance and high resolution detector based on the Open Axial Field Spectrometer \\\\ \\\\OBELIX is designed to study exclusive final states of antiproton and antineutron annihilations at low energies with protons and nuclei. \\\\ \\\\The physics motivations of the experiment are:\\\\ \\\\\\begin{itemize} \\item (gg, ggg), hybrids ($ q \\bar{q} g $), multiquarks ($ q q \\bar{q} \\bar{q} $) and light mesons ($ q \\bar{q} $) produced in $ N \\bar{N} $ annihilations and study of their spectroscopy and decays. Also broad structures will be searched for by comparing identical decay modes in exclusive final states of the same type occuring from initial states with different angular momentum or isospin. \\item Study of the dynamics of $ N \\bar{N} $ interactions and of the dependence of the final and intermediate resonant states of annihilation upon the quantum numbers of the initial $ N \\bar{N} $ state (angular momentum: S and P-wave in $\\bar{p}p $ at...

  11. Effect of Partial Shrouds on the Performance and Flow Field of a Low-Aspect-Ratio Axial-Flow Fan Rotor

    Directory of Open Access Journals (Sweden)

    N. Sitaram

    2011-01-01

    Full Text Available The flow field at the rotor exit of a low aspect ratio axial flow fan for different tip geometries and for different flow coefficients is measured in the present study. The following configurations are tested: (1 rotor without partial shroud, designated as rotor (wos, (2 rotor with partial shroud, designated as rotor (ws, and (3 rotor with perforated (perforations in the shape of discrete circular holes partial shroud, designated as rotor (wps. From steady state measurements, the performance of rotor (wps is found to be the best. Both the rotors with partial shrouds have stalled at a higher flow coefficient compared to that of rotor (wos. From periodic flow measurements, it is concluded that the low velocity region near the tip section is considerably reduced with the use of partial shrouds with perforations. The extent of this low velocity region for both rotor (wos and rotor (wps increases with decreasing flow coefficient due to increased stage loading. This core of low momentum fluid has moved inwards of the annulus and towards the pressure side as the flow coefficient decreases. The extent of the low momentum fluid is smaller for rotor (wps than that of rotor (wos at all flow coefficients.

  12. MEASUREMENT AND VISUALIZATION OF FLOW FIELD IN AXIAL FLOW FAN%在轴流风扇中的流场测量和显示

    Institute of Scientific and Technical Information of China (English)

    葛宁

    2000-01-01

    介绍了利用激光多普勒测速仪(LDA)和激光片光流场显示技术在一轴流风扇转子叶尖附近流场测量得到的结果.试验结果表明,转子叶尖处的通道涡并不是叶尖间隙流卷起造成的,而是由于端壁附面层受到叶尖间隙流的横向冲击后从机匣壁面上脱落形成的.%An experimental investigation associated with the basic fluid mechanics in an axial flow fan is described in this paper. The flow field in the tip region has been studied by laser Doppler anemometer (LDA) and flow visualization technique. Some experimental data and images are interpreted to understand the complex interactions between the annulus wall boundary layer and the leakage flow. It shows that the vortex inside the blade passage is produced by the separation of annulus wall boundary layer rather than the rolling up of leakage flow.

  13. Measurements of the unsteady flow field within the stator row of a transonic axial-flow fan. II - Results and discussion

    Science.gov (United States)

    Hathaway, M. D.; Suder, K. L.; Strazisar, A. J.; Adamczyk, J. J.; Okiishi, T. H.

    1987-01-01

    Unsteady velocity field measurements made within the stator row of a transonic axial-flow fan are presented. Measurements were obtained at midspan for two different stator blade rows using a laser anemometer. The first stator row consists of double circular-arc airfoils with a solidity of 1.68. The second features controlled-diffusion airfoils with a solidity of 0.85. Both were tested at design-speed peak efficiency conditions. In addition, the controlled-diffusion stator was also tested at near stall conditions. The procedures developed here are used to identify the rotor wake generated and unresolved unsteadiness from the velocity measurements (rotor wake generated unsteadiness refers to the unsteadiness generated by the rotor wake velocity deficit and unresolved unsteadiness refers to all remaining unsteadiness which contributes to the spread in the distribution of velocities such as vortex shedding, turbulence, etc.). Auto and cross correlations of these unsteady velocity fluctuations are presented to show their relative magnitude and spatial distributions. Amplification and attenuation of both rotor wake generated and unresolved unsteadiness are shown to occur within the stator blade passage.

  14. Measurements of the unsteady flow field within the stator row of a transonic axial-flow fan. Part 2: Results and discussion

    Science.gov (United States)

    Hathaway, M. D.; Suder, K. L.; Okiishi, T. H.; Strazisar, A. J.; Adamczyk, J. J.

    1987-01-01

    Unsteady velocity field measurements made within the stator row of a transonic axial-flow fan are presented. Measurements were obtained at midspan for two different stator blade rows using a laser anemometer. The first stator row consists of double circular-arc airfoils with a solidity of 1.68. The second features controlled-diffusion airfoils with a solidity of 0.85. Both were tested at design-speed peak efficiency conditions. In addition, the controlled-diffusion stator was also tested at near stall conditions. The procedures developed here are used to identify the rotor wake generated and unresolved unsteadiness from the velocity measurements (rotor wake generated unsteadiness refers to the unsteadiness generated by the rotor wake velocity deficit and unresolved unsteadiness refers to all remaining unsteadiness which contributes to the spread in the distribution of velocities such as vortex shedding, turbulence, etc.). Auto and cross correlations of these unsteady velocity fluctuations are presented to show their relative magnitude and spatial distributions. Amplification and attenuation of both rotor wake generated and unresolved unsteadiness are shown to occur within the stator blade passage.

  15. Multi-dimensional potential energy surfaces and non-axial octupole correlations in actinide and transfermium nuclei from relativistic mean field models

    CERN Document Server

    Lu, Bing-Nan; Zhao, En-Guang; Zhou, Shan-Gui

    2013-01-01

    We have developed multi-dimensional constrained covariant density functional theories (MDC-CDFT) for finite nuclei in which the shape degrees of freedom \\beta_{\\lambda\\mu} with even \\mu, e.g., \\beta_{20}, \\beta_{22}, \\beta_{30}, \\beta_{32}, \\beta_{40}, etc., can be described simultaneously. The functional can be one of the following four forms: the meson exchange or point-coupling nucleon interactions combined with the non-linear or density-dependent couplings. For the pp channel, either the BCS approach or the Bogoliubov transformation is implemented. The MDC-CDFTs with the BCS approach for the pairing (in the following labelled as MDC-RMF models with RMF standing for "relativistic mean field") have been applied to investigate multi-dimensional potential energy surfaces and the non-axial octupole $Y_{32}$-correlations in N=150 isotones. In this contribution we present briefly the formalism of MDC-RMF models and some results from these models. The potential energy surfaces with and without triaxial deformatio...

  16. Influence of Outlet Guide Vanes upon Performances of Waterjet Axial-Flow Pump%后导叶对喷水推进轴流泵性能的影响

    Institute of Scientific and Technical Information of China (English)

    汤方平; 王国强

    2006-01-01

    通过三维紊流数值计算和模型试验研究后导叶对轴流泵整体性能的影响.计算和泵试验表明,基于RNG k-ε紊流模型的定常流动分析能有效预测高效区内的泵特性.叶轮和导叶之间的轴向间隙为0.1 D时,后导叶对叶轮性能几乎没有影响,后导叶主要以对叶轮出口水流的旋转动能的回收和水力损失的形式对泵的特性产生影响.通过后导叶设计工况的选择,可适应不同的应用要求,实现叶轮和后导叶优化配置的目的.%With the use of three-dimensional turbulence numerical simulation and model test,the influence of the outlet guide vanes (OGV) on the overall performances of the axial-flow pump is studied.The computational and experimental results indicate that the steady numerical simulation based on the RNG k-ε turbulence model can effectively predict the pump performances at the design flow rate. When the axial clearance between the impeller and the OGV is greater than 0.1D,the OGV almost has no influence on the performance of the impeller. The existence of OGV will recycle the rotating kinetic energy of the impeller outlet, and cause hydraulic losses at the same time. By selecting the design operation point of the OGV,the configuration between the impeller and the OGV can be optimized in order to satisfy user's requirements.

  17. Prediction and near-field observation of skull-guided acoustic waves.

    Science.gov (United States)

    Estrada, Hector; Rebling, Johannes; Razansky, Daniel

    2017-03-01

    Ultrasound waves propagating in water or soft biological tissue are strongly reflected when encountering the skull, which limits the use of ultrasound-based techniques in transcranial imaging and therapeutic applications. Current knowledge on the acoustic properties of the cranial bone is restricted to far-field observations, leaving its near-field unexplored. We report on the existence of skull-guided acoustic waves, which was herein confirmed by near-field measurements of optoacoustically-induced responses in ex-vivo murine skulls immersed in water. Dispersion of the guided waves was found to reasonably agree with the prediction of a multilayered flat plate model. We observed a skull-guided wave propagation over a lateral distance of at least 3 mm, with a half-decay length in the direction perpendicular to the skull ranging from 35 to 300 μm at 6 and 0.5 MHz, respectively. Propagation losses are mostly attributed to the heterogenous acoustic properties of the skull.. It is generally anticipated that our findings may facilitate and broaden the application of ultrasound-mediated techniques in brain diagnostics and therapy.

  18. Prediction and near-field observation of skull-guided acoustic waves

    Science.gov (United States)

    Estrada, Héctor; Rebling, Johannes; Razansky, Daniel

    2017-06-01

    Ultrasound waves propagating in water or soft biological tissue are strongly reflected when encountering the skull, which limits the use of ultrasound-based techniques in transcranial imaging and therapeutic applications. Current knowledge on the acoustic properties of the cranial bone is restricted to far-field observations, leaving its near-field unexplored. We report on the existence of skull-guided acoustic waves, which was herein confirmed by near-field measurements of optoacoustically-induced responses in ex-vivo murine skulls immersed in water. Dispersion of the guided waves was found to reasonably agree with the prediction of a multilayered flat plate model. We observed a skull-guided wave propagation over a lateral distance of at least 3 mm, with a half-decay length in the direction perpendicular to the skull ranging from 35 to 300 μm at 6 and 0.5 MHz, respectively. Propagation losses are mostly attributed to the heterogenous acoustic properties of the skull. It is generally anticipated that our findings may facilitate and broaden the application of ultrasound-mediated techniques in brain diagnostics and therapy.

  19. Relativistic RPA in axial symmetry

    CERN Document Server

    Arteaga, D Pena; 10.1103/PhysRevC.77.034317

    2009-01-01

    Covariant density functional theory, in the framework of self-consistent Relativistic Mean Field (RMF) and Relativistic Random Phase approximation (RPA), is for the first time applied to axially deformed nuclei. The fully self-consistent RMF+RRPA equations are posed for the case of axial symmetry and non-linear energy functionals, and solved with the help of a new parallel code. Formal properties of RPA theory are studied and special care is taken in order to validate the proper decoupling of spurious modes and their influence on the physical response. Sample applications to the magnetic and electric dipole transitions in $^{20}$Ne are presented and analyzed.

  20. 1991/91 North Sea field development guide, 3rd ed

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    All the data included in The North Sea Platform and Subsea Construction Guides has been updated and expanded to make this new volume quite exceptional. This book presents 205 Oil and Gas Fields - full details including equity, exploration history, geology, reservoir, crude and production data and development concepts; 680 Production installations - full details on every fixed or floating facility existing or proposed including weights, dimensions, modules, production/process plants, drilling, production throughput, well/injection slots and all components; 275 Subsea installation -including all subsea completions, templates, manifolds, risers, trunk, in-field lines, tie-ins, burial and trenching data.

  1. [Book review] A field guide to western reptiles and amphibians (Second Edition, Revised), by Robert C. Stebbins and Roger Tory Peterson

    Science.gov (United States)

    Jennings, M.R.

    1987-01-01

    Review of: A Field Guide to Western Reptiles and Amphibians (Peterson Field Guides, No. 16). Robert C. Stebbins and Roger Tory Peterson. Houghton Mifflin; 2nd Revised edition (June 10, 1985). 448 pages. ISBN: 978-0395382530.

  2. Impact of field number and beam angle on functional image-guided lung cancer radiotherapy planning

    Science.gov (United States)

    Tahir, Bilal A.; Bragg, Chris M.; Wild, Jim M.; Swinscoe, James A.; Lawless, Sarah E.; Hart, Kerry A.; Hatton, Matthew Q.; Ireland, Rob H.

    2017-09-01

    To investigate the effect of beam angles and field number on functionally-guided intensity modulated radiotherapy (IMRT) normal lung avoidance treatment plans that incorporate hyperpolarised helium-3 magnetic resonance imaging (3He MRI) ventilation data. Eight non-small cell lung cancer patients had pre-treatment 3He MRI that was registered to inspiration breath-hold radiotherapy planning computed tomography. IMRT plans that minimised the volume of total lung receiving  ⩾20 Gy (V20) were compared with plans that minimised 3He MRI defined functional lung receiving  ⩾20 Gy (fV20). Coplanar IMRT plans using 5-field manually optimised beam angles and 9-field equidistant plans were also evaluated. For each pair of plans, the Wilcoxon signed ranks test was used to compare fV20 and the percentage of planning target volume (PTV) receiving 90% of the prescription dose (PTV90). Incorporation of 3He MRI led to median reductions in fV20 of 1.3% (range: 0.2-9.3% p  =  0.04) and 0.2% (range: 0 to 4.1%; p  =  0.012) for 5- and 9-field arrangements, respectively. There was no clinically significant difference in target coverage. Functionally-guided IMRT plans incorporating hyperpolarised 3He MRI information can reduce the dose received by ventilated lung without comprising PTV coverage. The effect was greater for optimised beam angles rather than uniformly spaced fields.

  3. Standard guide for data fields for computerized transfer of digital radiological examination data

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This guide provides a listing and description of the fields that are recommended for inclusion in a digital radiological examination data base to facilitate the transfer of such data. This guide sets guidelines for the format of data fields for computerized transfer of digital image files obtained from radiographic, radioscopic, computed radiographic, or other radiological examination systems. The field listing includes those fields regarded as necessary for inclusion in the data base: (1) regardless of the radiological examination method (as indicated by Footnote C in Table 1), (2) for radioscopic examination (as indicated by Footnote E in Table 1), and (3) for radiographic examination (as indicated by Footnote D in Table 1). In addition, other optional fields are listed as a reminder of the types of information that may be useful for additional understanding of the data or applicable to a limited number of applications. 1.2 It is recognized that organizations may have in place an internal format for the...

  4. Dissipative Axial Inflation

    CERN Document Server

    Notari, Alessio

    2016-01-01

    We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term $\\frac{\\phi}{f_\\gamma} F \\tilde{F}$, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density $\\rho_R$, which which can lead to inflation without the need of a flat potential. We analyze the system, for momenta $k$ smaller than the cutoff $f_\\gamma$, including numerically the backreaction. We consider the evolution from a given static initial condition and explicitly show that, if $f_\\gamma$ is smaller than the field excursion $\\phi_0$ by about a factor of at least ${\\cal O} (20)$, there is a friction effect which turns on before that the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of...

  5. Guided migration of neural stem cells derived from human embryonic stem cells by an electric field.

    Science.gov (United States)

    Feng, Jun-Feng; Liu, Jing; Zhang, Xiu-Zhen; Zhang, Lei; Jiang, Ji-Yao; Nolta, Jan; Zhao, Min

    2012-02-01

    Small direct current (DC) electric fields (EFs) guide neurite growth and migration of rodent neural stem cells (NSCs). However, this could be species dependent. Therefore, it is critical to investigate how human NSCs (hNSCs) respond to EF before any possible clinical attempt. Aiming to characterize the EF-stimulated and guided migration of hNSCs, we derived hNSCs from a well-established human embryonic stem cell line H9. Small applied DC EFs, as low as 16 mV/mm, induced significant directional migration toward the cathode. Reversal of the field polarity reversed migration of hNSCs. The galvanotactic/electrotactic response was both time and voltage dependent. The migration directedness and distance to the cathode increased with the increase of field strength. (Rho-kinase) inhibitor Y27632 is used to enhance viability of stem cells and has previously been reported to inhibit EF-guided directional migration in induced pluripotent stem cells and neurons. However, its presence did not significantly affect the directionality of hNSC migration in an EF. Cytokine receptor [C-X-C chemokine receptor type 4 (CXCR4)] is important for chemotaxis of NSCs in the brain. The blockage of CXCR4 did not affect the electrotaxis of hNSCs. We conclude that hNSCs respond to a small EF by directional migration. Applied EFs could potentially be further exploited to guide hNSCs to injured sites in the central nervous system to improve the outcome of various diseases.

  6. Spectroscopic analysis of high electric field enhanced ionization in laser filaments in air for corona guiding

    Institute of Scientific and Technical Information of China (English)

    Yingxia Wei; Yaoxiang Liu; Tie-Jun Wang; Na Chen; Jingjing Ju; Yonghong Liu; Haiyi Sun; Cheng Wang; Jiansheng Liu; Haihe Lu; See Leang Chin; Ruxin Li

    2016-01-01

    We report on a systematic experimental study on the fluorescence spectra produced from a femtosecond laser filament in air under a high electric field. The electric field alone was strong enough to create corona discharge(CD). Fluorescence spectra from neutral and ionic air molecules were measured and compared with pure high-voltage CD and pure laser filamentation(FIL). Among them, high electric field assisted laser FIL produced nitrogen fluorescence more efficiently than either pure CD or pure FIL processes. The nonlinear enhancement of fluorescence from the interaction of the laser filament and corona discharging electric field resulted in a more efficient ionization along the laser filament zone, which was confirmed by the spectroscopic measurement of both ionization-induced fluorescence and plasma-scattered 800 nm laser pulses. This is believed to be the key precursor process for filament-guided discharge.

  7. On the 2D behavior of 3D MHD with a strong guiding field

    CERN Document Server

    Alexakis, Alexandros

    2011-01-01

    The Magneto-hydrodynamic (MHD) equations in the presence of a guiding magnetic field are investigated by means of direct numerical simulations. The basis of the investigation consists of 9 runs forced at the small scales. The results demonstrate that for a large enough uniform magnetic field the large scale flow behaves as a two dimensional (non-MHD) fluid exhibiting an inverse cascade of energy in the direction perpendicular to the magnetic field, while the small scales behave like a three dimensional MHD-fluid cascading the energy forwards. The amplitude of the inverse cascade is sensitive to the magnetic field amplitude, the domain size, the forcing mechanism, and the forcing scale. All these dependencies are demonstrated by the varying parameters of simulations. Furthermore, in the case that the system is forced anisotropically in the small parallel scales an inverse cascade in the parallel direction is observed that is feeding the 2D modes.

  8. Illustrated field guide for aquatic insects study: A collection that lets you view life

    Directory of Open Access Journals (Sweden)

    Andrea Castiblanco-Zerda

    2017-01-01

    Full Text Available This work was developed from the aquatic insects collection (CIA of National Pedagogical University of Colombia, Bogotá. A field guide and ID portable key was outlined, which contributed to the study of aquatic insects with alternative collection methods, through the development of methodologies for observation of living organisms (in situ and in vivo for identification until taxonomic level of family during the field practice and its subsequent return to the habitat, taking into account students’ practical work needs in the field and the active use of Biology Department biological resources. It was concluded that the recognition of aquatic insects families allows articulation between collection and field practices, as well as students’ reflection on methods and goals of the collection, and evaluation of other procedural possibilities as those presented in this work.

  9. Simulating Magnetic Reconnection Experiment (MRX) with a Guide Field using Fluid Code, HiFi

    Science.gov (United States)

    Budner, Tamas; Chen, Yangao; Meier, Eric; Ji, Hantao; MRX Team

    2015-11-01

    Magnetic reconnection is a phenomenon that occurs in plasmas when magnetic field lines effectively ``break'' and reconnect resulting in a different topological configuration. In this process, energy that was once stored in the magnetic field is transfered into the thermal velocity of the particles, effectively heating the plasma. MRX at the Princeton Plasma Physics Laboratory creates the conditions under which reconnection can occur by initially ramping the current in two adjacent coils and then rapidly decreasing with and without a guide magnetic field along the reconnecting current. We simulate this experiment using a fluid code called HiFi, an implicit and adaptive high order spectral element modeling framework, and compare our results to experimental data from MRX. The purpose is to identify physics behind the observed reconnection process for the field line break and the resultant plasma heating.

  10. Two-dimensional behavior of three-dimensional magnetohydrodynamic flow with a strong guiding field.

    Science.gov (United States)

    Alexakis, Alexandros

    2011-11-01

    The magnetohydrodynamic (MHD) equations in the presence of a guiding magnetic field are investigated by means of direct numerical simulations. The basis of the investigation consists of nine runs forced at the small scales. The results demonstrate that for a large enough uniform magnetic field the large scale flow behaves as a two-dimensional (2D) (non-MHD) fluid exhibiting an inverse cascade of energy in the direction perpendicular to the magnetic field, while the small scales behave like a three-dimensional (3D) MHD fluid cascading the energy forwards. The amplitude of the inverse cascade is sensitive to the magnetic field amplitude, the domain size, the forcing mechanism, and the forcing scale. All these dependences are demonstrated by the varying parameters of the simulations. Furthermore, in the case that the system is forced anisotropically in the small parallel scales an inverse cascade in the parallel direction is observed that is feeding the 2D modes k(//)=0.

  11. Field-trip guide to a volcanic transect of the Pacific Northwest

    Science.gov (United States)

    Geist, Dennis; Wolff, John; Harpp, Karen

    2017-08-01

    The Pacific Northwest region of the United States provides world-class and historically important examples of a wide variety of volcanic features. This guide is designed to give a broad overview of the region’s diverse volcanism rather than focusing on the results of detailed studies; the reader should consult the reference list for more detailed information on each of the sites, and we have done our best to recognize previous field trip leaders who have written the pioneering guides. This trip derives from one offered as a component of the joint University of Idaho- Washington State University volcanology class taught from 1995 through 2014, and it borrows in theme from the classic field guide of Johnston and Donnelly-Nolan (1981). For readers interested in using this field guide as an educational tool, we have included an appendix with supplemental references to resources that provide useful background information on relevant topics, as well as a few suggestions for field-based exercises that could be useful when bringing students to these locations in the future. The 4-day trip begins with an examination of lava flow structures of the Columbia River Basalt, enormous lava fields that were emplaced during one of the largest eruptive episodes in Earth’s recent history. On the second day, the trip turns to the High Lava Plains, a bimodal volcanic province that transgressed from southeast to northwest from the Miocene through the Holocene, at the northern margin of the Basin and Range Province. This volcanic field provides excellent examples of welded ignimbrite, silicic lavas and domes, monogenetic basaltic lava fields, and hydrovolcanic features. The third day is devoted to a circumnavigation of Crater Lake, the result of one of the world’s best-documented caldera-forming eruptions. The caldera walls also expose the anatomy of Mount Mazama, a stratovolcano of the Cascade Range. The last day is spent at Newberry Volcano, a back-arc shield volcano topped by a

  12. Image-guided spinal injection procedures in open high-field MRI with vertical field orientation: feasibility and technical features

    Energy Technology Data Exchange (ETDEWEB)

    Streitparth, F.; Walter, T.; Wonneberger, U.; Wagner, M.; Hermann, K.G.; Hamm, B.; Teichgraeber, U. [Charite, Humboldt-Universitaet zu Berlin, Department of Radiology, Berlin (Germany); Chopra, S. [Charite-Universitaetsmedizin Berlin, Campus Virchow Klinikum, Department of General, Visceral, and Transplantation Surgery, Berlin (Germany); Wichlas, F. [Charite-Universitaetsmedizin Berlin, Campus Virchow Klinikum, Center for Musculoskeletal Surgery, Berlin (Germany)

    2010-02-15

    We prospectively evaluated the feasibility and technical features of MR-guided lumbosacral injection procedures in open high-field MRI at 1.0 T. In a CuSO{sub 4}.5H{sub 2}O phantom and five human cadaveric spines, fluoroscopy sequences (proton-density-weighted turbo spin-echo (PDw TSE), T1w TSE, T2w TSE; balanced steady-state free precession (bSSFP), T1w gradient echo (GE), T2w GE) were evaluated using two MRI-compatible 20-G Chiba-type needles. Artefacts were analysed by varying needle orientation to B{sub 0}, frequency-encoding direction and slice orientation. Image quality was described using the contrast-to-noise ratio (CNR). Subsequently, a total of 183 MR-guided nerve root (107), facet (53) and sacroiliac joint (23) injections were performed in 53 patients. In vitro, PDw TSE sequence yielded the best needle-tissue contrasts (CNR = 45, 18, 15, 9, and 8 for needle vs. fat, muscle, root, bone and sclerosis, respectively) and optimal artefact sizes (width and tip shift less than 5 mm). In vivo, PDw TSE sequence was sufficient in all cases. The acquisition time of 2 s facilitated near-real-time MRI guidance. Drug delivery was technically successful in 100% (107/107), 87% (46/53) and 87% (20/23) of nerve root, facet and sacroiliac joint injections, respectively. No major complications occurred. The mean procedure time was 29 min (range 19-67 min). MR-guided spinal injections in open high-field MRI are feasible and accurate using fast TSE sequence designs. (orig.)

  13. Sub-solar Magnetopause Observation and Simulation of a Tripolar Guide-Magnetic Field Perturbation

    Science.gov (United States)

    Eriksson, S.; Cassak, P.; Retino, A.; Mozer, F.

    2015-12-01

    The Polar satellite recorded two reconnection exhausts within 6 min on 1 April 2001 at a rather symmetric sub-solar magnetopause that displayed different out-of-plane signatures for similar solar wind conditions. The first case was reported by Mozer et al. [2002] and displayed a bipolar guide field supporting a quadrupole Hall field consistent with a single X-line. The second case, however, shows the first known example of a tripolar guide-field perturbation at Earth's magnetopause reminiscent of the types of solar wind exhausts that Eriksson et al. [2014; 2015] have reported to be in agreement with multiple X-lines. A dedicated particle-in-cell simulation is performed for the prevailing conditions across the magnetopause. We propose an explanation in terms of asymmetric Hall magnetic fields due to a presence of a magnetic island between two X-lines, and discuss how higher resolution MMS observations can be used to further study this problem at the magnetopause.

  14. Design of a high efficiency relativistic backward wave oscillator with low guiding magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaoze; Song, Wei; Tan, Weibing; Zhang, Ligang; Su, Jiancang; Zhu, Xiaoxin; Hu, Xianggang; Shen, Zhiyuan; Liang, Xu; Ning, Qi [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi' an 710024 (China)

    2016-07-15

    A high efficiency relativistic backward wave oscillator working at a low guiding magnetic field is designed and simulated. A trapezoidal resonant reflector is used to reduce the modulation field in the resonant reflector to avoid overmodulation of the electron beam which will lead to a large momentum spread and then low conversion efficiency. The envelope of the inner radius of the slow wave structure (SWS) increases stepwise to keep conformal to the trajectory of the electron beam which will alleviate the bombardment of the electron on the surface of the SWS. The length of period of the SWS is reduced gradually to make a better match between phase velocity and electron beam, which decelerates continually and improves the RF current distribution. Meanwhile the modulation field is reduced by the introduction of nonuniform SWS also. The particle in cell simulation results reveal that a microwave with a power of 1.8 GW and a frequency of 14.7 GHz is generated with an efficiency of 47% when the diode voltage is 620 kV, the beam current 6.1 kA, and the guiding magnetic field 0.95 T.

  15. Field guide to Cretaceous-tertiary boundary sections in northeastern Mexico

    Science.gov (United States)

    Keller, Gerta; Stinnesbeck, Wolfgang; Adatte, Thierry; Macleod, Norman; Lowe, Donald R.

    1994-01-01

    This guide was prepared for the field trip to the KT elastic sequence of northeastern Mexico, 5-8 February 1994, in conjunction with the Conference on New Developments Regarding the KT Event and Other Catastrophes in Earth History, held in Houston, Texas. The four-day excursion offers an invaluable opportunity to visit three key outcrops: Arroyo El Mimbral, La Lajilla, and El Pinon. These and other outcrops of this sequence have recently been interpreted as tsunami deposits produced by the meteorite impact event that produced the 200 to 300-km Chicxulub basin in Yucatan, and distributed ejecta around the world approximately 65 m.y. ago that today is recorded as a thin clay layer found at the K/T boundary. The impact tsunami interpretation for these rocks has not gone unchallenged, and others examining the outcrops arrive at quite different conclusions: not tsunami deposits but turbidites; not KT at all but 'upper Cretaceous.' Indeed, it is in hopes of resolving this debate through field discussion, outcrop evaluation, and sampling that led the organizers of the conference to sanction this field trip. This field guide provides participants with background information on the KT clastic sequence outcrops and is divided into two sections. The first section provides regional and logistical context for the outcrops and a description of the clastic sequence. The second section presents three representative interpretations of the outcrops by their advocates. There is clearly no way that these models can be reconciled and so two, if not all three, must be fundamentally wrong. Readers of this guide should keep in mind that many basic outcrop observations that these models are based upon remain unresolved. While great measures were taken to ensure that the information in the description section was as objective as possible, many observations are rooted in interpretations and the emphasis placed on certain observations depends to some degree upon the perspective of the author.

  16. 轴流导叶式水力旋流器井下油水分离系统方案设计%Design of Downhole Oil-water Separation System with Axial-flow Guide Vane Type Hydrocyclone

    Institute of Scientific and Technical Information of China (English)

    杨晓惠

    2011-01-01

    A downhole oil-water separation system with an axial-flow guide vane type hydrocyclone and rod pump was designed to solve the current problems, and its working principle and structure characteristics were analyzed. Compared with conventional downhole oil-water separation system of a tangential inlet hydrocyclone,the system has low energy loss,compact structure,small radial size and other characteristics.%针对目前井下油水分离系统中存在的问题,设计了一种轴流导叶式水力旋流器与有杆泵组合的井下油水分离系统,并对其工作原理和结构特点进行了分析.与采用切入式水力旋流器的常规井下油水分离系统相比,该系统具有能耗低、结构紧凑、径向尺寸小等特点.

  17. HDR Pathological Image Enhancement Based on Improved Bias Field Correction and Guided Image Filter

    Directory of Open Access Journals (Sweden)

    Qingjiao Sun

    2016-01-01

    Full Text Available Pathological image enhancement is a significant topic in the field of pathological image processing. This paper proposes a high dynamic range (HDR pathological image enhancement method based on improved bias field correction and guided image filter (GIF. Firstly, a preprocessing including stain normalization and wavelet denoising is performed for Haematoxylin and Eosin (H and E stained pathological image. Then, an improved bias field correction model is developed to enhance the influence of light for high-frequency part in image and correct the intensity inhomogeneity and detail discontinuity of image. Next, HDR pathological image is generated based on least square method using low dynamic range (LDR image, H and E channel images. Finally, the fine enhanced image is acquired after the detail enhancement process. Experiments with 140 pathological images demonstrate the performance advantages of our proposed method as compared with related work.

  18. Impact of compressibility and a guide field on Fermi acceleration during magnetic island coalescence

    Science.gov (United States)

    Montag, P.; Egedal, J.; Lichko, E.; Wetherton, B.

    2017-06-01

    Previous work has shown that Fermi acceleration can be an effective heating mechanism during magnetic island coalescence, where electrons may undergo repeated reflections as the magnetic field lines contract. This energization has the potential to account for the power-law distributions of particle energy inferred from observations of solar flares. Here, we develop a generalized framework for the analysis of Fermi acceleration that can incorporate the effects of compressibility and non-uniformity along field lines, which have commonly been neglected in previous treatments of the problem. Applying this framework to the simplified case of the uniform flux tube allows us to find both the power-law scaling of the distribution function and the rate at which the power-law behavior develops. We find that a guide magnetic field of order unity effectively suppresses the development of power-law distributions.

  19. Non-Maxwellian electron distribution functions due to self-generated turbulence in collisionless guide-field reconnection

    OpenAIRE

    Muñoz, P. A.; J. Büchner

    2016-01-01

    Non-Maxwellian electron velocity space distribution functions (EVDF) are useful signatures of plasma conditions and non-local consequences of collisionless magnetic reconnection. In the past, EVDFs were obtained mainly for antiparallel reconnection and under the influence of weak guide-fields in the direction perpendicular to the reconnection plane. EVDFs are, however, not well known, yet, for oblique (or component-) reconnection in dependence on stronger guide-magnetic fields and for the exh...

  20. Overview for geologic field-trip guides to volcanoes of the Cascades Arc in northern California

    Science.gov (United States)

    Muffler, L. J. Patrick; Donnelly-Nolan, Julie M.; Grove, Timothy L.; Clynne, Michael A.; Christiansen, Robert L.; Calvert, Andrew T.; Ryan-Davis, Juliet

    2017-08-15

    The California Cascades field trip is a loop beginning and ending in Portland, Oregon. The route of day 1 goes eastward across the Cascades just south of Mount Hood, travels south along the east side of the Cascades for an overview of the central Oregon volcanoes (including Three Sisters and Newberry Volcano), and ends at Klamath Falls, Oregon. Day 2 and much of day 3 focus on Medicine Lake Volcano. The latter part of day 3 consists of a drive south across the Pit River into the Hat Creek Valley and then clockwise around Lassen Volcanic Center to the town of Chester, California. Day 4 goes from south to north across Lassen Volcanic Center, ending at Burney, California. Day 5 and the first part of day 6 follow a clockwise route around Mount Shasta. The trip returns to Portland on the latter part of day 6, west of the Cascades through the Klamath Mountains and the Willamette Valley. Each of the three sections of this guidebook addresses one of the major volcanic regions: Lassen Volcanic Center (a volcanic field that spans the volcanic arc), Mount Shasta (a fore-arc stratocone), and Medicine Lake Volcano (a rear-arc, shield-shaped edifice). Each section of the guide provides (1) an overview of the extensive field and laboratory studies, (2) an introduction to the literature, and (3) directions to the most important and accessible field localities. The field-trip sections contain far more stops than can possibly be visited in the actual 6-day 2017 IAVCEI excursion from Portland. We have included extra stops in order to provide a field-trip guide that will have lasting utility for those who may have more time or may want to emphasize one particular volcanic area.

  1. Magnetic-field-induced dose effects in MR-guided radiotherapy systems: dependence on the magnetic field strength.

    Science.gov (United States)

    Raaijmakers, A J E; Raaymakers, B W; Lagendijk, J J W

    2008-02-21

    Several institutes are currently working on the development of a radiotherapy treatment system with online MR imaging (MRI) modality. The main difference between their designs is the magnetic field strength of the MRI system. While we have chosen a 1.5 Tesla (T) magnetic field strength, the Cross Cancer Institute in Edmonton will be using a 0.2 T MRI scanner and the company Viewray aims to use 0.3 T. The magnetic field strength will affect the severity of magnetic field dose effects, such as the electron return effect (ERE): considerable dose increase at tissue air boundaries due to returning electrons. This paper has investigated how the ERE dose increase depends on the magnetic field strength. Therefore, four situations where the ERE occurs have been simulated: ERE at the distal side of the beam, the lateral ERE, ERE in cylindrical air cavities and ERE in the lungs. The magnetic field comparison values were 0.2, 0.75, 1.5 and 3 T. Results show that, in general, magnetic field dose effects are reduced at lower magnetic field strengths. At the distal side, the ERE dose increase is largest for B = 0.75 T and depends on the irradiation field size for B = 0.2 T. The lateral ERE is strongest for B = 3 T but shows no effect for B = 0.2 T. Around cylindrical air cavities, dose inhomogeneities disappear if the radius of the cavity becomes small relative to the in-air radius of the secondary electron trajectories. At larger cavities (r > 1 cm), dose inhomogeneities exist for all magnetic field strengths. In water-lung-water phantoms, the ERE dose increase takes place at the water-lung transition and the dose decreases at the lung-water transition, but these effects are minimal for B = 0.2 T. These results will contribute to evaluating the trade-off between magnetic field dose effects and image quality of MR-guided radiotherapy systems.

  2. 可调进口导叶和叶片角向缝处理机匣相互作用的实验研究及机理分析%Experiment Investigation and Mechanism Analysis of Interaction of Variable Inlet Guide Vanes and Axial Skewed Slots Casing Treatment

    Institute of Scientific and Technical Information of China (English)

    楚武利; 申凯

    2014-01-01

    可调进口导叶和叶片角向缝处理机匣都能扩大压气机的稳定工作范围,为了分析同时采用这两种措施对压气机稳定性的影响及二者之间相互作用的机理,在单转子轴流压气机实验台上对不同导叶弯角下实壁机匣和叶片角向缝机匣进行了详细的实验测试。同时,对导叶弯角为+10°的每一种机匣结构和导叶0°的实壁机匣结构进行了数值模拟,数值模拟结果与实验结果符合良好,相对于导叶0°的实壁机匣,实验及数值模拟结果均表明,导叶正弯角结合叶片角向缝机匣处理结构能更好地扩大压气机的稳定工作裕度。对转子流场进行对比分析可得,导叶正预旋能抑制叶背气流的分离,提高压气机的稳定工作范围,但仍然没有改变转子叶尖部诱发失速的流动现象,而叶片角向缝主要是通过对叶顶气流的抽吸作用抑制了间隙泄漏流达到扩稳效果,因此耦合时能独立发挥各自的扩稳作用,从而能获得比单独使用任何一种方法都要更大的稳定工作范围的提升。%The variable inlet guide vanes and axial skewed slots casing treatment are effective measures that can extend the operating range of compressor. In order to analyze the mechanism of the interaction of these two measures,the different guide vanes angle with original smooth wall as well as slots configuration were tested on a single-rotor compressor. At the same time,the guide vane angle of 10° with each casing configuration and the guide vane angle of 0° with original smooth wall configuration are simulated. The results of experiment and cal-culation show that the introduction of these two kinds of measures can gain greater improvement of the stall mar-gin. The difference of the flow fields of the rotor was analyzed. The positive angle of the inlet guide vane can weak-en the separation of suction part flow,but it does not change the phenomenon of the stall

  3. Book review: Field guide to the common grasses of Oklahoma, Kansas, and Nebraska

    Science.gov (United States)

    Symstad, Amy J.

    2015-01-01

    Grass identification is not for the faint of heart, especially when one has to rely on dichotomous keys using terms like “glume” and “flexuous pedicels.” A good, illustrated field guide that avoids such specialized terms is invaluable for ranchers, amateur naturalists, landscapers, and a variety of grassland professionals that aren’t hard-core botanists. These are the audience that Iralee Barnard targets, and none of them will have any trouble using this handy volume that is short on words but generous with full-color photographs.

  4. Through flow analysis within axial flow turbomachinery blade rows

    Science.gov (United States)

    Girigoswami, H.

    1986-09-01

    Using Katsanis' Through Flow Code, inviscid flow through an axial flow compressor rotor blade as well as flow through inlet guide vanes are analyzed and the computed parameters such as meridional velocity distribution, axial velocity distribution along radial lines, and velocity distribution over blade surfaces are presented.

  5. Gyrokinetic and kinetic particle-in-cell simulations of guide-field reconnection

    Science.gov (United States)

    Munoz Sepulveda, Patricio Alejandro; Büchner, Jörg; Kilian, Patrick; Told, Daniel; Jenko, Frank

    2016-07-01

    Fully kinetic Particle-in-Cell (PIC) simulations of (strong) guide-field reconnection can be computationally very demanding, due to the intrinsic stability and accuracy conditions required by this numerical method. One convenient approach to circumvent this issue is using gyrokinetic theory, an approximation of the Vlasov-Maxwell equations for strongly magnetized plasmas that eliminates the fast gyromotion, and thus reduces the computational cost. Although previous works have started to compare the features of reconnection between both approaches, a complete understanding of the differences is far from being complete. This knowledge is essential to discern the limitations of the gyrokinetic simulations of magnetic reconnection when applied to scenarios with moderate guide fields, such as the Solar corona, in contrast to most of the fusion/laboratory plasmas. We extend a previous work by our group, focused in the differences in the macroscopic flows, by analyzing the heating processes and non-thermal features developed by reconnection between both plasma approximations. We relate these processes by identifying some high-frequency cross-streaming instabilities appearing only in the fully kinetic approach. We characterize the effects of these phenonema such as anisotropic electron heating, beam formation and turbulence under different parameter regimes. And finally, we identify the conditions under which these instabilities tends to become negligible in the fully kinetic model, and thus a comparison with gyrokinetic theory becomes more reliable.

  6. The effect of guide-field and boundary conditions on collisionless magnetic reconnection in a stressed X-point collapse

    Energy Technology Data Exchange (ETDEWEB)

    Graf von der Pahlen, J.; Tsiklauri, D. [School of Physics and Astronomy, Queen Mary University of London, London E1 4NS (United Kingdom)

    2014-01-15

    Works of Tsiklauri and Haruki [Phys. Plasmas 15, 102902 (2008); 14, 112905 (2007)] are extended by inclusion of the out-of-plane magnetic (guide) field. In particular, magnetic reconnection during collisionless, stressed X-point collapse for varying out-of-plane guide-fields is studied using a kinetic, 2.5D, fully electromagnetic, relativistic particle-in-cell numerical code. For zero guide-field, cases for both open and closed boundary conditions are investigated, where magnetic flux and particles are lost and conserved, respectively. It is found that reconnection rates, out-of-plane currents and density in the X-point increase more rapidly and peak sooner in the closed boundary case, but higher values are reached in the open boundary case. The normalized reconnection rate is fast: 0.10-0.25. In the open boundary case it is shown that an increase of guide-field yields later onsets in the reconnection peak rates, while in the closed boundary case initial peak rates occur sooner but are suppressed. The reconnection current changes similarly with increasing guide-field; however for low guide-fields the reconnection current increases, giving an optimal value for the guide-field between 0.1 and 0.2 times the in-plane field in both cases. Also, in the open boundary case, it is found that for guide-fields of the order of the in-plane magnetic field, the generation of electron vortices occurs. Possible causes of the vortex generation, based on the flow of decoupled particles in the diffusion region and localized plasma heating, are discussed. Before peak reconnection onset, oscillations in the out-of-plane electric field at the X-point are found, ranging in frequency from approximately 1 to 2 ω{sub pe} and coinciding with oscillatory reconnection. These oscillations are found to be part of a larger wave pattern in the simulation domain. Mapping the out-of-plane electric field along the central lines of the domain over time and applying a 2D Fourier transform reveal that

  7. Overview for geologic field-trip guides to Mount Mazama, Crater Lake Caldera, and Newberry Volcano, Oregon

    Science.gov (United States)

    Bacon, Charles R.; Donnelly-Nolan, Julie M.; Jensen, Robert A.; Wright, Heather M.

    2017-08-16

    These field-trip guides were written for the occasion of the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) quadrennial scientific assembly in Portland, Oregon, in August 2017. The guide to Mount Mazama and Crater Lake caldera is an updated and expanded version of the guide (Bacon, 1989) for part of an earlier IAVCEI trip to the southern Cascade Range. The guide to Newberry Volcano describes the stops included in the 2017 field trip. Crater Lake and Newberry are the two best-preserved and most recent calderas in the Cascades Volcanic Arc. Although located in different settings in the arc, with Crater Lake on the arc axis and Newberry in the rear-arc, both volcanoes are located at the intersection of the arc and the northwest corner region of the extensional Basin and Range Province.

  8. Observations of turbulence within reconnection jet in the presence of guide field

    Science.gov (United States)

    Huang, S. Y.; Zhou, M.; Sahraoui, F.; Vaivads, A.; Deng, X. H.; André, M.; He, J. S.; Fu, H. S.; Li, H. M.; Yuan, Z. G.; Wang, D. D.

    2012-06-01

    We present the first comprehensive observations of turbulence properties within high speed reconnection jet in the plasma sheet with moderate guide field. The power spectral density index is about -1.73 in the inertial range, and follows the value of -2.86 in the ion dissipation range. The turbulence is strongly anisotropic in the wave-vector space with the major power having its wave-vector highly oblique to the ambient magnetic field, suggesting that the turbulence is quasi-2D. The measured "dispersion relations" obtained using the k-filtering technique are compared with theory and are found to be consistent with the Alfvén-Whistler mode. In addition, both Probability Distribution Functions and flatness results show that the turbulence in the reconnection jet is intermittent (multifractal) at scales less than the proton gyroradius/inertial lengths. The estimated electric field provided by anomalous resistivity caused by turbulence is about 3 mV/m, which is close to the typical reconnection electric field in the magnetotail.

  9. A practical guide to in vivo proton magnetic resonance spectroscopy at high magnetic fields.

    Science.gov (United States)

    Xin, Lijing; Tkáč, Ivan

    2017-07-15

    Localized proton magnetic resonance spectroscopy ((1)H-MRS) is a noninvasive tool for measuring in vivo neurochemical information in animal and human brains. With the increase of magnetic field strength, whereas localized (1)H-MRS benefits from higher sensitivity and spectral dispersion, it is challenged by increased spatial inhomogeneity of the B0 and B1 fields, larger chemical shift displacement error, and shortened T2 relaxation times of metabolites. Advanced localized (1)H-MRS methodologies developed for high magnetic fields have shown promising results and allow the measurement of neurochemical profiles with up to 19 brain metabolites, including less-abundant metabolites, such as glutathione, glycine, γ-aminobutyric acid and ascorbate. To provide a practical guide for conducting in vivo(1)H-MRS studies at high magnetic field strength, we reviewed various essential technical aspects from data acquisition (hardware requirements, B1 and B0 inhomogeneity, water suppression, localization sequences and acquisition strategies) to data processing (frequency and phase correction, spectral quality control, spectral fitting and concentration referencing). Additionally, we proposed guidelines for choosing the most appropriate data acquisition and processing approaches to maximize the achievable neurochemical information. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Development and field testing of a self-assessment guide for computer-based provider order entry.

    Science.gov (United States)

    Vartian, Carl V; Singh, Hardeep; Russo, Elise; Sittig, Dean F

    2014-01-01

    Despite the benefits of computerized provider order entry (CPOE), numerous reports of unexpected CPOE-related safety concerns have surfaced. As part of a larger project to improve the safety of electronic health records (EHRs), we developed and field tested a CPOE "safety self-assessment" guide through literature searches, expert opinion, and site visits. We then conducted a field test of this guide with nine hospital chief medical informatics officers (CMIOs), who were identified through the Association of Medical Directors of Information Systems. The CPOE safety self-assessment guide was sent electronically to the CMIOs. Once the assessments were returned, we conducted structured telephone interviews for further comments about the guide's format and content. The CMIOs in our study found the CPOE safety guide useful and relatively easy to complete, taking no more than 30 minutes. Analysis of responses to the guide suggest that most recommended practices were implemented inconsistently across facilities. Despite consensus for certain CPOE best practices in the medical literature and among experts, there appeared to be considerable variation among CMIOs' opinions of best practices. Interview data suggested this inconsistency was mostly due to system limitations and/or differing opinions about the necessity of certain EHR-related safety measures. Despite the absence of consensus on best practices, a self-assessment safety guide provides a practical starting point for organizations to assess and improve safety and the effectiveness of their CPOE system.

  11. The Effects of 910-MHz Electromagnetic Field on Rat Cranial Arachnoid and Dura Mater Collagen. The Axial Periodicity of Collagen Fibrils

    Directory of Open Access Journals (Sweden)

    Margaret Tzaphlidou

    2004-01-01

    Full Text Available The axial periodicity of rat arachnoid and dura mater collagen fibrils exposed to 910 MHz for 2 h/day for 30 consecutive days was measured by means of image analysis of electron-optical data. Such measurements were compared with those from sham-exposed animals. These measurements reveal that on exposure, the intermolecular interactions during collagen fibril assembly are affected.

  12. Modeling the effect of unsteady flows on the time average flow field of a blade row embedded in an axial flow multistage turbomachine

    Science.gov (United States)

    Adamczyk, John J.

    1996-01-01

    The role of unsteady flow processes in establishing the performance of axial flow turbomachinery was investigated. The development of the flow model, as defined by the time average flow equations associated with the passage of the blade row embedded in a multistage configuration, is presented. The mechanisms for unsteady momentum and energy transport is outlined. The modeling of the unsteady momentum and energy transport are discussed. The procedure for simulating unsteady multistage turbomachinery flows is described.

  13. Dissipative axial inflation

    Science.gov (United States)

    Notari, Alessio; Tywoniuk, Konrad

    2016-12-01

    We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term phi/fγ F ~F, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density ρR, which can lead to inflation without the need of a flat potential. We analyze the system, for momenta k smaller than the cutoff fγ, including the backreaction numerically. We consider the evolution from a given static initial condition and explicitly show that, if fγ is smaller than the field excursion phi0 by about a factor of at least Script O (20), there is a friction effect which turns on before the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of perturbations, scalars and tensors. Such oscillations have a period of 4-5 efolds and an amplitude which is typically less than a few percent and decreases linearly with fγ. We also stress that the curvature perturbation on uniform density slices should be sensitive to slow-roll parameters related to ρR rather than dot phi2/2 and we discuss the existence of friction terms acting on the perturbations, although we postpone a calculation of the power spectrum and of non-gaussianity to future work and we simply define and compute suitable slow roll parameters. Finally we stress that this scenario may be realized in the axion case, if the coupling 1/fγ to U(1) (photons) is much larger than the coupling 1/fG to non-abelian gauge fields (gluons), since the latter sets the range of the potential and therefore the maximal allowed phi0~ fG.

  14. OPSO - The OpenGL based Field Acquisition and Telescope Guiding System

    Science.gov (United States)

    Škoda, P.; Fuchs, J.; Honsa, J.

    2006-07-01

    We present OPSO, a modular pointing and auto-guiding system for the coudé spectrograph of the Ondřejov observatory 2m telescope. The current field and slit viewing CCD cameras with image intensifiers are giving only standard TV video output. To allow the acquisition and guiding of very faint targets, we have designed an image enhancing system working in real time on TV frames grabbed by BT878-based video capture card. Its basic capabilities include the sliding averaging of hundreds of frames with bad pixel masking and removal of outliers, display of median of set of frames, quick zooming, contrast and brightness adjustment, plotting of horizontal and vertical cross cuts of seeing disk within given intensity range and many more. From the programmer's point of view, the system consists of three tasks running in parallel on a Linux PC. One C task controls the video capturing over Video for Linux (v4l2) interface and feeds the frames into the large block of shared memory, where the core image processing is done by another C program calling the OpenGL library. The GUI is, however, dynamically built in Python from XML description of widgets prepared in Glade. All tasks are exchanging information by IPC calls using the shared memory segments.

  15. Student representation of magnetic field concepts in learning by guided inquiry

    Science.gov (United States)

    Desy Fatmaryanti, Siska; Suparmi; Sarwanto; Ashadi

    2017-01-01

    The purpose of this study was to determine the change of student’s representation after the intervention of learning by guided inquiry. The population in this research were all students who took a fundamental physics course, consisted of 28 students academic year 2016, Department of Physics Education, Faculty of Teacher Training and Education, University of Muhammadiyah Purworejo. This study employed a quasi-experimental design with group pre-test and post-test. The result of the research showed that the average of students representation of magnetic field before implementation of guided inquiry was 28,6 % and after implementation was 71,4%. It means that the student’s ability of multi-representation increase. Moreover, the number of students who is able to write and draw based on experiment data increased from 10,7% to 21,4 %. It was also showed that the number of student with no answer decreased from 28,5% to 10,7%.

  16. BWR AXIAL PROFILE

    Energy Technology Data Exchange (ETDEWEB)

    J. Huffer

    2004-09-28

    The purpose of this calculation is to develop axial profiles for estimating the axial variation in burnup of a boiling water reactor (BWR) assembly spent nuclear fuel (SNF) given the average burnup of an assembly. A discharged fuel assembly typically exhibits higher burnup in the center and lower burnup at the ends of the assembly. Criticality safety analyses taking credit for SNF burnup must account for axially varying burnup relative to calculations based on uniformly distributed assembly average burnup due to the under-burned tips. Thus, accounting for axially varying burnup in criticality analyses is also referred to as accounting for the ''end effect'' reactivity. The magnitude of the reactivity change due to ''end effect'' is dependent on the initial assembly enrichment, the assembly average burnup, and the particular axial profile characterizing the burnup distribution. The set of bounding axial profiles should incorporate multiple BWR core designs and provide statistical confidence (95 percent confidence that 95 percent of the population is bound by the profile) that end nodes are conservatively represented. The profiles should also conserve the overall burnup of the fuel assembly. More background on BWR axial profiles is provided in Attachment I.

  17. Novel Integration Radial and Axial Magnetic Bearing

    Science.gov (United States)

    Blumenstock, Kenneth; Brown, Gary

    2000-01-01

    Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics; separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and magnetic field modeling results will be presented.

  18. [Management of axial spondyloarthritis].

    Science.gov (United States)

    Kiltz, U; Baraliakos, X; Braun, J

    2016-11-01

    The term spondyloarthritis (SpA) is now increasingly used to classify and diagnose patients who are characterized by inflammation in the axial skeleton and peripheral manifestations (arthritis and enthesitis). The management of SpA should be tailored according to the current manifestations of the disease, the disease activity and functional impairment. The current article focuses on diagnosis and therapy in patients with axial SpA. Diagnostic procedures are discussed in light of diagnostic utility and feasibility in daily routine care. Cornerstones of treatment in patients with axial SpA are a combination of regular exercise and pharmacological treatment options aiming at anti-inflammatory strategies.

  19. Collapse of the wave field in a one-dimensional system of weakly coupled light guides

    Science.gov (United States)

    Balakin, A. A.; Litvak, A. G.; Mironov, V. A.; Skobelev, S. A.

    2016-12-01

    The analytical and numerical study of the radiation self-action in a system of coupled light guides is fulfilled on the basis of the discrete nonlinear Schrödinger equation (DNSE). We develop a variational method for qualitative study of DNSE and classify self-action modes. We show that the diffraction of narrow (in grating scale) wave beams weakens in discrete media and, consequently, the "collapse" of the one-dimensional wave field with power exceeding the critical value occurs. This results in the ability to self-channel radiation in the central fiber. Qualitative analytical results were confirmed by numerical simulation of DNSE, which also shows the stability of the collapse mode.

  20. Three Questions to Guide Study and Practice in the Information Systems Field

    Directory of Open Access Journals (Sweden)

    JuanQiong Gou

    2014-09-01

    Full Text Available Gaining an understanding of Information Systems and improving IS education has become a serious issue for the IS discipline. Prior to undertaking Management Information Systems (MIS in an MBA course, students sometimes cannot clearly explain exactly what information systems are and what they should do in practice. This paper begins by considering the various influences on the MIS curriculum and some of the conventional approaches to curriculum design, selection and organisation of teaching materials. It then offers an alternative approach by presenting a three question framework for understanding and explaining the IS field. From this basis the paper argues that these three questions can be used to guide the study, teaching and practice of MIS.

  1. Guiding of relativistic electron beams in solid targets by resistively controlled magnetic fields.

    Science.gov (United States)

    Kar, S; Robinson, A P L; Carroll, D C; Lundh, O; Markey, K; McKenna, P; Norreys, P; Zepf, M

    2009-02-06

    Guided transport of a relativistic electron beam in solid is achieved experimentally by exploiting the strong magnetic fields created at the interface of two metals of different electrical resistivities. This is of substantial relevance to the Fast Ignitor approach to fusion energy production [M. Tabak, Phys. Plasmas 12, 057305 (2005)10.1063/1.1871246], since it allows the electron deposition to be spatially tailored-thus adding substantial design flexibility and preventing inefficiencies due to electron beam spreading. In the experiment, optical transition radiation and thermal emission from the target rear surface provide a clear signature of the electron confinement within a high resistivity tin layer sandwiched transversely between two low resistivity aluminum slabs. The experimental data are found to agree well with numerical simulations.

  2. Analytical Model of Fast Magnetic Reconnection with a Large Guide Field

    CERN Document Server

    Simakov, Andrei N; Zocco, A

    2010-01-01

    Analytical theory of fast magnetic reconnection with a large guide field is presented for the first time. We confirm that two distinct reconnection regimes are possible depending on whether the diffusion region thickness $\\delta$ is larger or smaller than the sound gyroradius $\\rho_s$. The reconnection is slow or Sweet-Parker-like for $\\delta \\gtrsim \\rho_s$, and fast otherwise. In the fast regime, however, we find that ion viscosity $\\mu$ plays a critical role. In particular, for $\\delta < \\rho_s$ the diffusion region thickness is proportional to $Ha^{-1}$ with $Ha \\propto 1/\\sqrt{\\eta \\mu}$ the Hartmann number, and the reconnection rate is proportional to $Pr^{-1/2}$ with $Pr = \\mu/\\eta$ the Prandtl number and $\\eta$ the resistivity. If the perpendicular ion viscosity is employed for $\\mu$ the reconnection rate becomes independent of both plasma $\\beta$ and collision frequencies and therefore potentially fast.

  3. The IEEE guide to writing in the engineering and technical fields

    CERN Document Server

    Kmiec, David

    2017-01-01

    This book introduces students and practicing engineers to all the components of writing in the workplace. It teaches readers how considerations of audience and purpose govern the structure of their documents within particular work settings. The IEEE Guide to Writing in the Engineering and Technical Fields is broken up into two sections: "Writing in Engineering Organizations" and "What Can You Do With Writing?" The first section helps readers approach their writing in a logical and persuasive way as well as analyze their purpose for writing. The second section demonstrates how to distinguish rhetorical situations and the generic forms to inform, train, persuade, and collaborate. The emergence of the global workplace has brought with it an increasingly important role for effective technical communication. Engineers more often need to work in cross-functional teams with people in different disciplines, in different countries, and in different parts of the world. Engineers must know how to communicate in a rapid...

  4. Field Guide to the Plant Community Types of Voyageurs National Park

    Science.gov (United States)

    Faber-Langendoen, Don; Aaseng, Norman; Hop, Kevin; Lew-Smith, Michael

    2007-01-01

    INTRODUCTION The objective of the U.S. Geological Survey-National Park Service Vegetation Mapping Program is to classify, describe, and map vegetation for most of the park units within the National Park Service (NPS). The program was created in response to the NPS Natural Resources Inventory and Monitoring Guidelines issued in 1992. Products for each park include digital files of the vegetation map and field data, keys and descriptions to the plant communities, reports, metadata, map accuracy verification summaries, and aerial photographs. Interagency teams work in each park and, following standardized mapping and field sampling protocols, develop products and vegetation classification standards that document the various vegetation types found in a given park. The use of a standard national vegetation classification system and mapping protocol facilitate effective resource stewardship by ensuring compatibility and widespread use of the information throughout the NPS as well as by other Federal and state agencies. These vegetation classifications and maps and associated information support a wide variety of resource assessment, park management, and planning needs, and provide a structure for framing and answering critical scientific questions about plant communities and their relation to environmental processes across the landscape. This field guide is intended to make the classification accessible to park visitors and researchers at Voyageurs National Park, allowing them to identify any stand of natural vegetation and showing how the classification can be used in conjunction with the vegetation map (Hop and others, 2001).

  5. Physical processes of driven magnetic reconnection in collisionless plasmas: Zero guide field case

    Science.gov (United States)

    Cheng, C. Z.; Inoue, S.; Ono, Y.; Horiuchi, R.

    2015-10-01

    The key physical processes of the electron and ion dynamics, the structure of the electric and magnetic fields, and how particles gain energy in the driven magnetic reconnection in collisionless plasmas for the zero guide field case are presented. The key kinetic physics is the decoupling of electron and ion dynamics around the magnetic reconnection region, where the magnetic field is reversed and the electron and ion orbits are meandering, and around the separatrix region, where electrons move mainly along the field line and ions move mainly across the field line. The decoupling of the electron and ion dynamics causes charge separation to produce a pair of in-plane bipolar converging electrostatic electric field ( E→ e s ) pointing toward the neutral sheet in the magnetic field reversal region and the monopolar E→ e s around the separatrix region. A pair of electron jets emanating from the reconnection current layer generate the quadrupole out-of-plane magnetic field, which causes the parallel electric field ( E→ || ) from E→ i n d to accelerate particles along the magnetic field. We explain the electron and ion dynamics and their velocity distributions and flow structures during the time-dependent driven reconnection as they move from the upstream to the downstream. In particular, we address the following key physics issues: (1) the decoupling of electron and ion dynamics due to meandering orbits around the field reversal region and the generation of a pair of converging bipolar electrostatic electric field ( E→ e s ) around the reconnection region; (2) the slowdown of electron and ion inflow velocities due to acceleration/deceleration of electrons and ions by E→ e s as they move across the neutral sheet; (3) how the reconnection current layer is enhanced and how the orbit meandering particles are accelerated inside the reconnection region by E→ i n d ; (4) why the electron outflow velocity from the reconnection region reaches super-Alfvenic speed

  6. Axial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2008-01-01

    Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

  7. Comment on 'Consequences of phase separation on the distribution of hydrothermal fluids at ASHES vent field, axial volcano, Juan de Fuca ridge' by Christopher G. Fox

    Science.gov (United States)

    Scholl, M. A.; Ingebritsen, S. E.; Essaid, H. I.

    1993-02-01

    Fox (1990), in order to explain observations during the Axial Seamount Hydrothermal Emissions Study (ASHES), proposed a conceptual model for a two-phase subsea hydrothermal system in which steam controlled flow patterns by blocking liquid flow. An attempt is made here to demonstrate with a very general model that relative permeability contrasts by themselves do not cause spatial isolation of phases in steam/liquid water systems and that density segregation, independent of relative permeability effects, should not be ruled out as an explanation for the observations at the ASHES site. Fox replies that density segregation is probably not the only mechanism at work.

  8. Role of electron inertia and reconnection dynamics in a stressed X-point collapse with a guide-field

    Science.gov (United States)

    Graf von der Pahlen, J.; Tsiklauri, D.

    2016-11-01

    Aims: In previous simulations of collisionless 2D magnetic reconnection it was consistently found that the term in the generalised Ohm's law that breaks the frozen-in condition is the divergence of the electron pressure tensor's non-gyrotropic components. The motivation for this study is to investigate the effect of the variation of the guide-field on the reconnection mechanism in simulations of X-point collapse, and the related changes in reconnection dynamics. Methods: A fully relativistic particle-in-cell (PIC) code was used to model X-point collapse with a guide-field in two and three spatial dimensions. Results: We show that in a 2D X-point collapse with a guide-field close to the strength of the in-plane field, the increased induced shear flows along the diffusion region lead to a new reconnection regime in which electron inertial terms play a dominant role at the X-point. This transition is marked by the emergence of a magnetic island - and hence a second reconnection site - as well as electron flow vortices moving along the current sheet. The reconnection electric field at the X-point is shown to exceed all lower guide-field cases for a brief period, indicating a strong burst in reconnection. By extending the simulation to three spatial dimensions it is shown that the locations of vortices along the current sheet (visualised by their Q-value) vary in the out-of-plane direction, producing tilted vortex tubes. The vortex tubes on opposite sides of the diffusion region are tilted in opposite directions, similarly to bifurcated current sheets in oblique tearing-mode reconnection. The tilt angles of vortex tubes were compared to a theoretical estimation and were found to be a good match. Particle velocity distribution functions for different guide-field runs, for 2.5D and 3D simulations, are analysed and compared.

  9. Field-trip guide to the geologic highlights of Newberry Volcano, Oregon

    Science.gov (United States)

    Jensen, Robert A.; Donnelly-Nolan, Julie M.

    2017-08-09

    Newberry Volcano and its surrounding lavas cover about 3,000 square kilometers (km2) in central Oregon. This massive, shield-shaped, composite volcano is located in the rear of the Cascades Volcanic Arc, ~60 km east of the Cascade Range crest. The volcano overlaps the northwestern corner of the Basin and Range tectonic province, known locally as the High Lava Plains, and is strongly influenced by the east-west extensional environment. Lava compositions range from basalt to rhyolite. Eruptions began about half a million years ago and built a broad composite edifice that has generated more than one caldera collapse event. At the center of the volcano is the 6- by 8-km caldera, created ~75,000 years ago when a major explosive eruption of compositionally zoned tephra led to caldera collapse, leaving the massive shield shape visible today. The volcano hosts Newberry National Volcanic Monument, which encompasses the caldera and much of the northwest rift zone where mafic eruptions occurred about 7,000 years ago. These young lava flows erupted after the volcano was mantled by the informally named Mazama ash, a blanket of volcanic ash generated by the eruption that created Crater Lake about 7,700 years ago. This field trip guide takes the visitor to a variety of easily accessible geologic sites in Newberry National Volcanic Monument, including the youngest and most spectacular lava flows. The selected sites offer an overview of the geologic story of Newberry Volcano and feature a broad range of lava compositions. Newberry’s most recent eruption took place about 1,300 years ago in the center of the caldera and produced tephra and lava of rhyolitic composition. A significant mafic eruptive event occurred about 7,000 years ago along the northwest rift zone. This event produced lavas ranging in composition from basalt to andesite, which erupted over a distance of 35 km from south of the caldera to Lava Butte where erupted lava flowed west to temporarily block the Deschutes

  10. The Onset of Magnetic Reconnection: Tearing Instability in Current Sheets with a Guide Field

    Science.gov (United States)

    Daldorff, Lars K. S.; Klimchuk, James A.; Leake, James E.; Knizhnik, Kalman

    2017-08-01

    Magnetic reconnection is fundamental to many solar phenomena, ranging from coronal heating, to jets, to flares and CMEs. A poorly understood yet crucial aspect of reconnection is that it does not occur until magnetic stresses have built to sufficiently high levels for significant energy release. If reconnection were to happen too soon, coronal heating would be weak and flares would be small. As part of our program to study the onset conditions for magnetic reconnection, we have investigated the instability of current sheets to tearing. Surprisingly little work has been done on this problem for sheets that include a guide field, i.e., for which the field rotates by less than 180 degrees. This is the most common situation on the Sun. We present numerical 3D resistive MHD simulations of several sheets and show how the behavior depends on the shear angle (rotation). We compare our results to the predictions of linear theory and discuss the nonlinear evolution in terms of plasmoid formation and the interaction of different oblique tearing modes. The relevance to the Sun is explained.

  11. Guiding of relativistic electron beams in dense matter by longitudinally imposed strong magnetic fields

    CERN Document Server

    Bailly-Grandvaux, M; Bellei, C; Forestier-Colleoni, P; Fujioka, S; Giuffrida, L; Honrubia, J J; Batani, D; Bouillaud, R; Chevrot, M; Cross, J E; Crowston, R; Dorard, S; Dubois, J -L; Ehret, M; Gregori, G; Hulin, S; Kojima, S; Loyez, E; Marques, J -R; Morace, A; Nicolai, Ph; Roth, M; Sakata, S; Schaumann, G; Serres, F; Servel, J; Tikhonchuk, V T; Woolsey, N; Zhang, Z

    2016-01-01

    High-energy-density flows through dense matter are needed for effective progress in the production of laser-driven intense sources of energetic particles and radiation, in driving matter to extreme temperatures creating state regimes relevant for planetary or stellar science as yet inaccessible at the laboratory scale, or in achieving high-gain laser-driven thermonuclear fusion. When interacting at the surface of dense (opaque) targets, intense lasers accelerate relativistic electron beams which transport a significant fraction of the laser energy into the target depth. However, the overall laser-to-target coupling efficiency is impaired by the large divergence of the electron beam, intrinsic to the laser-plasma interaction. By imposing a longitudinal 600T laser-driven magnetic-field, our experimental results show guided >10MA-current of MeV-electrons in solid matter. Due to the applied magnetic field, the transported energy-density and the peak background electron temperature at the 60micron-thick targets re...

  12. A compact field guide to the study of microsaccades: Challenges and functions.

    Science.gov (United States)

    Poletti, Martina; Rucci, Michele

    2016-01-01

    Following a period of quiescence at the end of last century, the study of microsaccades has now regained strong impetus and broad attention within the vision research community. This wave of interest, partly fueled by the advent of user-friendly high-resolution eyetrackers, has attracted researchers and led to novel ideas. Old hypothesis have been revisited and new ones formulated. This article is designed to serve as a practical guide for researchers in the field. Because of the history of the field and the difficulty of measuring very small eye movements, the study of microsaccades presents peculiar challenges. Here, we summarize some of the main challenges and describe methods for assessing and improving the quality of the recordings. Furthermore, we examine how these experimental challenges have influenced analysis of the visual functions of microsaccades and critically review current evidence on three long-debated proposals: the maintenance of fixation, the prevention of visual fading, and the exploration of fine spatial detail. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. A field ornithologist’s guide to genomics: Practical considerations for ecology and conservation

    Science.gov (United States)

    Oyler-McCance, Sara J.; Oh, Kevin; Langin, Kathryn; Aldridge, Cameron L.

    2016-01-01

    Vast improvements in sequencing technology have made it practical to simultaneously sequence millions of nucleotides distributed across the genome, opening the door for genomic studies in virtually any species. Ornithological research stands to benefit in three substantial ways. First, genomic methods enhance our ability to parse and simultaneously analyze both neutral and non-neutral genomic regions, thus providing insight into adaptive evolution and divergence. Second, the sheer quantity of sequence data generated by current sequencing platforms allows increased precision and resolution in analyses. Third, high-throughput sequencing can benefit applications that focus on a small number of loci that are otherwise prohibitively expensive, time-consuming, and technically difficult using traditional sequencing methods. These advances have improved our ability to understand evolutionary processes like speciation and local adaptation, but they also offer many practical applications in the fields of population ecology, migration tracking, conservation planning, diet analyses, and disease ecology. This review provides a guide for field ornithologists interested in incorporating genomic approaches into their research program, with an emphasis on techniques related to ecology and conservation. We present a general overview of contemporary genomic approaches and methods, as well as important considerations when selecting a genomic technique. We also discuss research questions that are likely to benefit from utilizing high-throughput sequencing instruments, highlighting select examples from recent avian studies.

  14. Advances in RNA molecular dynamics: a simulator's guide to RNA force fields.

    Science.gov (United States)

    Vangaveti, Sweta; Ranganathan, Srivathsan V; Chen, Alan A

    2017-03-01

    Molecular simulations have become an essential tool for biochemical research. When they work properly, they are able to provide invaluable interpretations of experimental results and ultimately provide novel, experimentally testable predictions. Unfortunately, not all simulation models are created equal, and with inaccurate models it becomes unclear what is a bona fide prediction versus a simulation artifact. RNA models are still in their infancy compared to the many robust protein models that are widely in use, and for that reason the number of RNA force field revisions in recent years has been rapidly increasing. As there is no universally accepted 'best' RNA force field at the current time, RNA simulators must decide which one is most suited to their purposes, cognizant of its essential assumptions and their inherent strengths and weaknesses. Hopefully, armed with a better understanding of what goes inside the simulation 'black box,' RNA biochemists can devise novel experiments and provide crucial thermodynamic and structural data that will guide the development and testing of improved RNA models. WIREs RNA 2017, 8:e1396. doi: 10.1002/wrna.1396 For further resources related to this article, please visit the WIREs website. © 2016 Wiley Periodicals, Inc.

  15. Evidence of magnetic field switch-off in Particle In Cell simulations of collisionless magnetic reconnection with guide field

    Science.gov (United States)

    Innocenti, M. E.; Goldman, M. V.; Newman, D. L.; Markidis, S.; Lapenta, G.

    2015-12-01

    The long term evolution of large domain Particle In Cell simulations of collisionless magnetic reconnection is investigated following observations that show two possible outcomes for collisionless reconnection: towards a Petschek-like configuration (Gosling 2007) or towards multiple X points (Eriksson et al. 2014). In the simulations presented here and described in [Innocenti2015*], a mixed scenario develops. At earlier time, plasmoids are emitted, disrupting the formation of Petschek-like structures. Later, an almost stationary monster plasmoid forms, preventing the emission of other plasmoids. A situation reminding of Petschek's switch-off then ensues. Switch-off is obtained through a slow shock / rotational discontinuity (SS/RD) compound structure, with the rotation discontinuity downstreamthe slow shock. Two external slow shocks located in correspondence of the separatrices reduce the in plane tangential component of the magnetic field, but not to zero. Two transitions reminding of rotational discontinuities in the internal part of the exhausts then perform the final switch-off. Both the slow shocks and the rotational discontinuities are characterized as such through the analysis of their Rankine-Hugoniot jump conditions. A moderate guide field is used to suppress the development of the firehose instability in the exhaust that prevented switch off in [Liu2012]. Compound SS/RD structures, with the RD located downstream the SS, have been observed in both the solar wind and the magnetosphere in Wind and Geotail data respectively [Whang1998, Whang2004]. Ion trajectiories across the SS/RD structure are followed and the kinetic origin of the SS/RD structure is investigated. * Innocenti, Goldman, Newman, Markidis, Lapenta, Evidence of magnetic field switch-off in collisionless magnetic reconnection, accepted in Astrophysical Journal Letters, 2015 Acknowledgements: NERSC, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of

  16. Proton beam deflection in MRI fields: Implications for MRI-guided proton therapy.

    Science.gov (United States)

    Oborn, B M; Dowdell, S; Metcalfe, P E; Crozier, S; Mohan, R; Keall, P J

    2015-05-01

    This paper investigates, via magnetic modeling and Monte Carlo simulation, the ability to deliver proton beams to the treatment zone inside a split-bore MRI-guided proton therapy system. Field maps from a split-bore 1 T MRI-Linac system are used as input to geant4 Monte Carlo simulations which model the trajectory of proton beams during their paths to the isocenter of the treatment area. Both inline (along the MRI bore) and perpendicular (through the split-bore gap) orientations are simulated. Monoenergetic parallel and diverging beams of energy 90, 195, and 300 MeV starting from 1.5 and 5 m above isocenter are modeled. A phase space file detailing a 2D calibration pattern is used to set the particle starting positions, and their spatial location as they cross isocenter is recorded. No beam scattering, collimation, or modulation of the proton beams is modeled. In the inline orientation, the radial symmetry of the solenoidal style fringe field acts to rotate the protons around the beam's central axis. For protons starting at 1.5 m from isocenter, this rotation is 19° (90 MeV) and 9.8° (300 MeV). A minor focusing toward the beam's central axis is also seen, but only significant, i.e., 2 mm shift at 150 mm off-axis, for 90 MeV protons. For the perpendicular orientation, the main MRI field and near fringe field act as the strongest to deflect the protons in a consistent direction. When starting from 1.5 m above isocenter shifts of 135 mm (90 MeV) and 65 mm (300 MeV) were observed. Further to this, off-axis protons are slightly deflected toward or away from the central axis in the direction perpendicular to the main deflection direction. This leads to a distortion of the phase space pattern, not just a shift. This distortion increases from zero at the central axis to 10 mm (90 MeV) and 5 mm (300 MeV) for a proton 150 mm off-axis. In both orientations, there is a small but subtle difference in the deflection and distortion pattern between protons fired parallel to the

  17. Trail Blazers: Fourth-Grade Students Create Digital Field Guides for Visitors to the School's Nature Trail

    Science.gov (United States)

    Connors, Lisa Marie

    2011-01-01

    As a fourth-grade science teacher, the author wanted a project that was (a) yearlong in scope, (b) got her students outside more, and (c) laid the groundwork for a learning progression. In this article, she describes a project in which her fourth-grade students created digital field guides for visitors to their school's nature trail. In the…

  18. Dynamic Instructional Leadership to Support Student Learning and Development: The Field Guide to Comer Schools in Action

    Science.gov (United States)

    Joyner, Edward T., Ed.; Ben-Avie, Michael, Ed.; Comer, James P., Ed.

    2004-01-01

    Schools are the only universally accessible institutions where there are enough adults to provide continuous support for children's growth, development, and success in life. Using the process pioneered by renowned child psychiatrist Dr. James P. Comer and his colleagues at the Yale School Development Program (SDP), this unique field guide offers…

  19. Systems Thinkers in Action: A Field Guide for Effective Change Leadership in Education. Leading School Improvement #10

    Science.gov (United States)

    Despres, Blane, Ed.

    2007-01-01

    This field guide provides a look into education in relation to a concept that has already been established in science, business and therapy. This book will encourage and educate readers about systemic thinking through examples and ideas pertinent to education and its reform. Following a Foreword (Michael Fullan) and Introduction (Blane Despres),…

  20. Trail Blazers: Fourth-Grade Students Create Digital Field Guides for Visitors to the School's Nature Trail

    Science.gov (United States)

    Connors, Lisa Marie

    2011-01-01

    As a fourth-grade science teacher, the author wanted a project that was (a) yearlong in scope, (b) got her students outside more, and (c) laid the groundwork for a learning progression. In this article, she describes a project in which her fourth-grade students created digital field guides for visitors to their school's nature trail. In the…

  1. Excitation of radial ion motion in an rf-only multipole ion guide immersed in a strong magnetic field gradient.

    Science.gov (United States)

    Beu, Steven C; Hendrickson, Christopher L; Marshall, Alan G

    2011-03-01

    Radiofrequency (rf) multipole ion guides are widely used to transfer ions through the strong magnetic field gradient between source and analyzer regions of external source Fourier transform ion cyclotron resonance mass spectrometers. Although ion transfer as determined solely by the electric field in a multipole ion guide has been thoroughly studied, transfer influenced by immersion in a strong magnetic field gradient has not been as well characterized. Recent work has indicated that the added magnetic field can have profound effects on ion transfer, ultimately resulting in loss of ions initially contained within the multipole. Those losses result from radial ejection of ions due to transient cyclotron resonance that occurs when ions traverse a region in which the magnetic field results in an effective cyclotron frequency equal to the multipole rf drive frequency divided by the multipole order (multipole order is equal to one-half the number of poles). In this work, we describe the analytical basis for ion resonance in a rf multipole ion guide with superposed static magnetic field and compare with results of numerical trajectory simulations. © American Society for Mass Spectrometry, 2011

  2. Faults Analysis of the Axial Magnetic Field Switched Reluctance Drive System%轴向磁场开关磁阻电机系统的故障分析∗

    Institute of Scientific and Technical Information of China (English)

    李洋; 王德明; 张广明; 梅磊

    2014-01-01

    The structure of an axial magnetic field switched reluctance motor was briefly introduced, and the winding faults and power converter were analyzed. The fault of power converter frequently occurs in the axial magnetic field switched reluctance drive system and the winding is the weakest part of the motor. The mechanism of these two faults was illustrated, and the conception of fault tolerant control method of switched reluctance motor was put forward.%介绍了轴向磁场开关磁阻电机的结构,对功率变换器的故障和电机本体的绕组故障进行分析。功率变换器是开关磁阻电机系统中发生故障比较频繁的环节之一,电机的绕组是开关磁阻电机本体上最薄弱的部分。详细说明了这两类故障的发生机理,并提出开关磁阻电机容错控制方法的构想。

  3. Antibiotic sensitivity patterns in field isolates of Mycoplasma gallisepticum as a guide to chemotherapy.

    Science.gov (United States)

    Levisohn, S

    1981-07-01

    Control of Mycoplasma gallisepticum (Mg) infection in commercial poultry flocks has sometimes been achieved by the intensive use of antibiotics. In some cases, a single drug, tylosin tartrate, has been used repeatedly in prophylactic and therapeutic applications. It appears that this selective pressure can lead to the emergence of strains with reduced sensitivity to tylosin. This was observed in Mg strains isolated in 1978 from turkey breeding flocks repeatedly treated with tylosin, but not in isolates from acute disease outbreaks. Moreover, in a study of four recent outbreaks of mycoplasma respiratory disease in poultry, some of the Mg strains isolated in each of the outbreaks showed reduced sensitivity to tylosin and, at the same time, to spiramycin. This suggests that the buildup of these strains in the general pool of Mg is playing an increasingly significant role in clinical outbreaks. Periodic in vitro antibiotic sensitivity testing of field isolates of mycoplasma is indicated as a means of monitoring the impact of mass medication programs and as a guide to therapeutic treatment.

  4. Electric fields guide migration of epidermal stem cells and promote skin wound healing.

    Science.gov (United States)

    Li, Li; Gu, Wei; Du, Juan; Reid, Brian; Deng, Xianjian; Liu, Zhidai; Zong, Zhaowen; Wang, Haiyan; Yao, Bo; Yang, Ce; Yan, Jun; Zeng, Ling; Chalmers, Laura; Zhao, Min; Jiang, Jianxin

    2012-01-01

    Migration of epidermal stem cells (EpSCs) into wounds may play an important role in wound healing. Endogenous electric fields (EFs) arise naturally at wounds. Consistent with previous reports, we measured outward electric currents at rat skin wounds using vibrating probes. Topical use of prostaglandin E2 significantly promoted wound healing. However, it is not known whether EpSCs respond to EFs. We first isolated and characterized EpSCs from rat skin. We then demonstrated that EpSCs isolated from the epidermis migrated directionally toward the cathode in EFs of 50-400 mV/mm. The directedness values increased in a dose- and time-dependent fashion. The migration speed of EpSCs was significantly increased in EFs. EFs induced asymmetric polymerization of intracellular F-actin and activation of the extracellular signal-regulated kinase 1/2 and phosphatidylinositol-3-kinase (PI3K)/protein kinase B pathways. Inhibition of epidermal growth factor receptor, extracellular signal-regulated kinase 1/2, or PI3K significantly inhibited the cathodal distribution of F-actin and the electrotactic response of EpSCs. These data for the first time show that EpSCs possess obvious electrotaxis, in which the epidermal growth factor receptor-mitogen activated protein kinase-PI3K pathways are involved. These data thus suggest a novel aspect of electric signaling in wound healing-to stimulate and guide migration of EpSCs and to regulate wound healing.

  5. Hebbian plasticity guides maturation of glutamate receptor fields in vivo.

    Science.gov (United States)

    Ljaschenko, Dmitrij; Ehmann, Nadine; Kittel, Robert J

    2013-05-30

    Synaptic plasticity shapes the development of functional neural circuits and provides a basis for cellular models of learning and memory. Hebbian plasticity describes an activity-dependent change in synaptic strength that is input-specific and depends on correlated pre- and postsynaptic activity. Although it is recognized that synaptic activity and synapse development are intimately linked, our mechanistic understanding of the coupling is far from complete. Using Channelrhodopsin-2 to evoke activity in vivo, we investigated synaptic plasticity at the glutamatergic Drosophila neuromuscular junction. Remarkably, correlated pre- and postsynaptic stimulation increased postsynaptic sensitivity by promoting synapse-specific recruitment of GluR-IIA-type glutamate receptor subunits into postsynaptic receptor fields. Conversely, GluR-IIA was rapidly removed from synapses whose activity failed to evoke substantial postsynaptic depolarization. Uniting these results with developmental GluR-IIA dynamics provides a comprehensive physiological concept of how Hebbian plasticity guides synaptic maturation and sparse transmitter release controls the stabilization of the molecular composition of individual synapses.

  6. Hebbian Plasticity Guides Maturation of Glutamate Receptor Fields In Vivo

    Directory of Open Access Journals (Sweden)

    Dmitrij Ljaschenko

    2013-05-01

    Full Text Available Synaptic plasticity shapes the development of functional neural circuits and provides a basis for cellular models of learning and memory. Hebbian plasticity describes an activity-dependent change in synaptic strength that is input-specific and depends on correlated pre- and postsynaptic activity. Although it is recognized that synaptic activity and synapse development are intimately linked, our mechanistic understanding of the coupling is far from complete. Using Channelrhodopsin-2 to evoke activity in vivo, we investigated synaptic plasticity at the glutamatergic Drosophila neuromuscular junction. Remarkably, correlated pre- and postsynaptic stimulation increased postsynaptic sensitivity by promoting synapse-specific recruitment of GluR-IIA-type glutamate receptor subunits into postsynaptic receptor fields. Conversely, GluR-IIA was rapidly removed from synapses whose activity failed to evoke substantial postsynaptic depolarization. Uniting these results with developmental GluR-IIA dynamics provides a comprehensive physiological concept of how Hebbian plasticity guides synaptic maturation and sparse transmitter release controls the stabilization of the molecular composition of individual synapses.

  7. Geologic field-trip guide to Mount Shasta Volcano, northern California

    Science.gov (United States)

    Christiansen, Robert L.; Calvert, Andrew T.; Grove, Timothy L.

    2017-08-18

    off, in a field of high-alumina olivine tholeiite lavas (HAOTs, referred to elsewhere in this guide as low-potassium olivine tholeiites, LKOTs). It proceeds around the southern, western, and northern flanks of Mount Shasta and onto a part of the arc axis. The stops feature elements of the Mount Shasta area in an approximately chronological order, from oldest to youngest.

  8. Field-trip guide to Mount Hood, Oregon, highlighting eruptive history and hazards

    Science.gov (United States)

    Scott, William E.; Gardner, Cynthia A.

    2017-06-22

    This guidebook describes stops of interest for a geological field trip around Mount Hood volcano. It was developed for the 2017 International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) Scientific Assembly in Portland, Oregon. The intent of this guidebook and accompanying contributions is to provide an overview of Mount Hood, including its chief geologic processes, magmatic system, eruptive history, local tectonics, and hazards, by visiting a variety of readily accessible localities. We also describe coeval, largely monogenetic, volcanoes in the region. Accompanying the field-trip guidebook are separately authored contributions that discuss in detail the Mount Hood magmatic system and its products and behavior (Kent and Koleszar, this volume); Mount Hood earthquakes and their relation to regional tectonics and the volcanic system (Thelen and Moran, this volume); and young surface faults cutting the broader Mount Hood area whose extent has come to light after acquisition of regional light detection and ranging coverage (Madin and others, this volume).The trip makes an approximately 175-mile (280-kilometer) clockwise loop around Mount Hood, starting and ending in Portland. The route heads east on Interstate 84 through the Columbia River Gorge National Scenic Area. The guidebook points out only a few conspicuous features of note in the gorge, but many other guides to the gorge are available. The route continues south on the Mount Hood National Scenic Byway on Oregon Route 35 following Hood River, and returns to Portland on U.S. Highway 26 following Sandy River. The route traverses rocks as old as the early Miocene Eagle Creek Formation and overlying Columbia River Basalt Group of middle Miocene age, but chiefly lava flows and clastic products of arc volcanism of late Miocene to Holocene age.

  9. An Unbroken Axial Vector Current Conservation Law

    CERN Document Server

    Sharafiddinov, Rasulkhozha S

    2015-01-01

    The mass, energy and momentum of the neutrino of a true flavor have an axial-vector nature. As a consequence, the left-handed truly neutral neutrino in an axial-vector field of emission can be converted into a right-handed one and vice versa. This predicts the unidenticality of masses, energies and momenta of neutrinos of the different components. Recognizing such a difference in masses, energies, momenta and accepting that the left-handed axial-vector neutrino and the right-handed antineutrino of true neutrality refer to long-lived C-odd leptons, and the right-handed truly neutral neutrino and the left-handed axial-vector antineutrino are of short-lived fermions of C-oddity, we would write a new CP-even Dirac equation taking into account the flavor symmetrical axial-vector mass, energy and momentum matrices. Their presence explains the spontaneous mirror symmetry violation, confirming that an axial-vector current conservation law has never violated. They reflect the availability of a mirror Minkowski space i...

  10. MiDAS Field Guide – a Comprehensive Online Source of Information About the Microbes of Activated Sludge

    DEFF Research Database (Denmark)

    Nierychlo, Marta; McIlroy, Simon Jon; Saunders, Aaron Marc

    activated sludge wastewater treatment systems, linking their identity with available information on their function and distribution. The guide includes the approx. 100 abundant genera that are present in most treatment plants (based on a survey of 25 full-scale Danish wastewater treatment plants...... that would be otherwise excluded from analyses. The MiDAS database importantly provides a common taxonomy for the field that gives a solid foundation for the study of microbial ecology of the activated sludge process and related wastewater treatment processes, such as biofilms and granular sludge. Each genus...... are provided. The MiDAS Field Guide is a continuously developing resource where all working in the field are invited to contribute....

  11. THEMIS multispacecraft observations of a reconnecting magnetosheath current sheet with symmetric boundary conditions and a large guide field

    Science.gov (United States)

    Øieroset, M.; Phan, T. D.; Shay, M. A.; Haggerty, C. C.; Fujimoto, M.; Angelopoulos, V.; Eastwood, J. P.; Mozer, F. S.

    2017-08-01

    We report three spacecraft observations of a reconnecting magnetosheath current sheet with a guide field of unity, with THEMIS D (THD) and THEMIS E (THE)/THEMIS A (THA) observing oppositely directed reconnection exhausts, indicating the presence of an X line between the spacecraft. The near-constant convective speed of the magnetosheath current sheet allowed the direct translation of the observed time series into spatial profiles. THD observed asymmetries in the plasma density and temperature profiles across the exhaust, characteristics of symmetric reconnection with a guide field. The exhausts at THE and THA, on the other hand, were not the expected mirror image of the THD exhaust in terms of the plasma and field profiles. They consisted of a main outflow at the center of the current sheet, flanked by oppositely directed flows at the two edges of the current sheet, suggesting the presence of a second X line, whose outflow wraps around the outflow from the first X line.

  12. Three-dimensional evolution of a relativistic current sheet: triggering of magnetic reconnection by the guide field.

    Science.gov (United States)

    Zenitani, S; Hoshino, M

    2005-08-26

    The linear and nonlinear evolution of a relativistic current sheet of pair (e(+/-)) plasmas is investigated by three-dimensional particle-in-cell simulations. In a Harris configuration, it is obtained that the magnetic energy is fast dissipated by the relativistic drift kink instability (RDKI). However, when a current-aligned magnetic field (the so-called "guide field") is introduced, the RDKI is stabilized by the magnetic tension force and it separates into two obliquely propagating modes, which we call the relativistic drift-kink-tearing instability. These two waves deform the current sheet so that they trigger relativistic magnetic reconnection at a crossover thinning point. Since relativistic reconnection produces a lot of nonthermal particles, the guide field is of critical importance to study the energetics of a relativistic current sheet.

  13. Role of Electron Inertia and Reconnection Dynamics in a Stressed X-point Collapse with a Guide-Field

    CERN Document Server

    von der Pahlen, Jan Graf

    2016-01-01

    In previous simulations of collisionless 2D magnetic reconnection it was consistently found that the term in the generalised Ohm's law that breaks the frozen-in condition is the divergence of the electron pressure tensor's non-gyrotropic components. A fully relativistic particle-in-cell (PIC) code was used to model $X$-point collapse with a guide-field in two and three spatial dimensions. We show that in a 2D $X$-point collapse with a guide-field close to the strength of the in-plane field, the increased induced shear flows along the diffusion region lead to a new reconnection regime in which electron inertial terms play a dominant role at the $X$-point. This transition is marked by the emergence of a magnetic island - and hence a second reconnection site - as well as electron flow vortices moving along the current sheet. The reconnection electric field at the $X$-point is shown to exceed all lower guide-field cases for a brief period, indicating a strong burst in reconnection. By extending the simulation to ...

  14. Image use in field guides and identification keys: review and recommendations

    Science.gov (United States)

    Leggett, Roxanne; Kirchoff, Bruce K.

    2011-01-01

    Background and aims Although illustrations have played an important role in identification keys and guides since the 18th century, their use has varied widely. Some keys lack all illustrations, while others are heavily illustrated. Even within illustrated guides, the way in which images are used varies considerably. Here, we review image use in paper and electronic guides, and establish a set of best practices for image use in illustrated keys and guides. Scope Our review covers image use in both paper and electronic guides, though we only briefly cover apps for mobile devices. With this one exception, we cover the full range of guides, from those that consist only of species descriptions with no keys, to lavishly illustrated technical keys. Emphasis is placed on how images are used, not on the operation of the guides and key, which has been reviewed by others. We only deal with operation when it impacts image use. Main points Few illustrated keys or guides use images in optimal ways. Most include too few images to show taxonomic variation or variation in characters and character states. The use of multiple images allows easier taxon identification and facilitates the understanding of characters. Most images are usually not standardized, making comparison between images difficult. Although some electronic guides allow images to be enlarged, many do not. Conclusions The best keys and guides use standardized images, displayed at sizes that are easy to see and arranged in a standardized manner so that similar images can be compared across species. Illustrated keys and glossaries should contain multiple images for each character state so that the user can judge variation in the state. Photographic backgrounds should not distract from the subject and, where possible, should be of a standard colour. When used, drawings should be prepared by professional botanical illustrators, and clearly labelled. Electronic keys and guides should allow images to be enlarged so that

  15. Non-Maxwellian electron distribution functions due to self-generated turbulence in collisionless guide-field reconnection

    Science.gov (United States)

    Muñoz, P. A.; Büchner, J.

    2016-10-01

    Non-Maxwellian electron velocity space distribution functions (EVDFs) are useful signatures of plasma conditions and non-local consequences of collisionless magnetic reconnection. In the past, EVDFs were obtained mainly for antiparallel reconnection and under the influence of weak guide-fields in the direction perpendicular to the reconnection plane. EVDFs are, however, not well known, yet, for oblique (or component-) reconnection in case and in dependence on stronger guide-magnetic fields and for the exhaust (outflow) region of reconnection away from the diffusion region. In view of the multi-spacecraft Magnetospheric Multiscale Mission (MMS), we derived the non-Maxwellian EVDFs of collisionless magnetic reconnection in dependence on the guide-field strength bg from small ( b g ≈ 0 ) to very strong (bg = 8) guide-fields, taking into account the feedback of the self-generated turbulence. For this sake, we carried out 2.5D fully kinetic Particle-in-Cell simulations using the ACRONYM code. We obtained anisotropic EVDFs and electron beams propagating along the separatrices as well as in the exhaust region of reconnection. The beams are anisotropic with a higher temperature in the direction perpendicular rather than parallel to the local magnetic field. The beams propagate in the direction opposite to the background electrons and cause instabilities. We also obtained the guide-field dependence of the relative electron-beam drift speed, threshold, and properties of the resulting streaming instabilities including the strongly non-linear saturation of the self-generated plasma turbulence. This turbulence and its non-linear feedback cause non-adiabatic parallel electron acceleration. We further obtained the resulting EVDFs due to the non-linear feedback of the saturated self-generated turbulence near the separatrices and in the exhaust region of reconnection in dependence on the guide field strength. We found that the influence of the self-generated plasma turbulence

  16. Geologic field trip guide to Mount Mazama and Crater Lake Caldera, Oregon

    Science.gov (United States)

    Bacon, Charles R.; Wright, Heather M.

    2017-08-08

    geologic research at Crater Lake have been incorporated not only in scientific investigations elsewhere, but also in the practical evaluation of local hazards (Bacon and others, 1997b) and geothermal resources (Bacon and Nathenson, 1996). The 1:24,000-scale geologic map of Mount Mazama and Crater Lake caldera (Bacon, 2008) is unusual because it portrays bedrock (outcrop), surficial, and lake floor geology. Caldera wall geology is depicted in detail on the accompanying geologic panoramas, and bedrock geology is shown in a 1:50,000-scale geologic map. This field guide supersedes earlier geology guides of Crater Lake (Bacon, 1987, 1989).

  17. Extended Hamiltonian Formalism of the Pure Space-Like Axial Gauge Schwinger Model. II

    Science.gov (United States)

    Nakawaki, Y.; McCartor, G.

    2004-06-01

    Canonical methods are not sufficient to properly quantize space-like axial gauges. In this paper, we obtain guiding principles that allow for the construction of an extended Hamiltonian formalism for pure space-like axial gauge fields. To do so, we clarify the general role that residual gauge fields play in the space-like axial gauge Schwinger model. In all the calculations, we fix the gauge using the rule n•A=0, where n is a space-like constant vector, and we refer to its direction as x-. Then, to begin with, we construct a formulation in which the quantization surface is space-like but not parallel to the direction of n. The quantization surface has a parameter that allows us to rotate it, but when we do so, we keep the gauge fixing direction fixed. In that formulation, we can use canonical methods. We bosonize the model to simplify the investigation. We find that the inverse differentiation, (∂-)-1, is ill-defined whatever quantization coordinates we use, as long as the direction of n is space-like. We find that the physical part of the dipole ghost field includes infrared divergences. However, we also find that if we introduce residual gauge fields in such a way that the dipole ghost field satisfies the canonical commutation relations, then the residual gauge fields are determined so as to regularize the infrared divergences contained in the physical part. The propagators then take the form prescribed by Mandelstam and Leibbrandt. We make use of these properties to develop guiding principles that allow us to construct consistent operator solutions in the pure space-like case, in which the quantization surface is parallel to the direction of n, and canonical methods do not suffice.

  18. Effects of blade thickness on performance of axial flow pump and analysis of internal flow field%叶片厚度对轴流泵性能影响及内部流场分析

    Institute of Scientific and Technical Information of China (English)

    沙毅; 侯丽艳

    2012-01-01

    In order to investigate the variable-thickness performance of blade in a axial flow pump, a QY90-4.4-1.5 submersible axial flow pump with specific speed 550 and rotate velocity 2900 r/min, especially its particular impeller and guide vane has been designed on the basis of arc method and streamline method. Based on experiments with increasing in leaf thickness, the reason about the difference among curves of qv-H, qv-P, qv-tj were studied. The three-dimensional internal flow with effect of impeller blade thickness within axial flow has been numerically simulated by CFD, both the relative velocity distribution on the optimal condition and static pressure distribution on the different condition of blade surface were obtained. It can be revealed that pump performance with thin blade was improved, but the anti-cavitation was reduced. It also can be showed that the situations of flow separation, backflow and secondary flow were more serious for the thick blades, which were the main reasons for the low efficiency of pump.%为研究叶片厚度对轴流泵性能影响及其内部流场变化规律,该文采用圆弧法和流线法进行比转速550、转速2 900 r/min的QY90-4.4-1.5型潜水轴流泵水力模型设计,完成产品开发及样机型式试验.通过加厚叶轮叶片进行对比试验,阐明泵流量—扬程、流量—轴功率和流量—效率曲线产生差别的原因.采用计算流体动力学(CFD)方法进行叶片厚度对流场影响的数值计算,得到最优工况叶片表面相对速度分布和不同工况叶片表面静压分布.经过分析,阐明薄叶片总体性能优于厚叶片,但抗汽蚀性能可能劣于厚叶片.厚叶片翼型脱流、叶片进出口出现回流及二次流情况更为严重,水力损失较大,是泵效率等性能参数偏低的主要原因.

  19. Altered Axial Skeletal Development

    Science.gov (United States)

    The axial skeleton is routinely examined in standard developmental toxicity bioassays and has proven to be sensitive to a wide variety of chemical agents. Dysmorphogenesis in the skull, vertebral column and ribs has been described in both human populations and in laboratory anima...

  20. Remote field eddy current technique for gap measurement of horizontal flux detector guide tube in pressurized heavy water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong Hoon; Jung, Hyun Kyu; Yang, Dong Ju; Cheong, Yong Moo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2004-11-15

    The fuel channels including the pressure tube(PT) and the calandria tube(CT) are important components of the pressurized heavy water reactor(PHWR). A sagging of fuel channel increases by heat and radiation exposure with the increasing operation time. The contact of fuel channel to the Horizontal flux Detector(HFD) guide tube is needed for the power plant safety. In order to solve this safety issue, the electromagnetic technique was applied to measure the status of the guide tube. The Horizontal flux Detector(HFD) guide tube and the Calandria tube(CT) in the Pressurized Heavy Water Reactor(PHWR) are cross-aligned horizontally. The remote field eddy current(RFEC) technology is applied for gap measurement between the HFD guide tube and the CT HFD guide tube can be detected by inserting the RFEC probe into pressure tube(PT) at the crossing point directly. The RFEC signals using the volume integral method(VIM) were simulated for obtaining the optimal inspection parameters. This paper shows that the simulated eddy current signals and the experimental results in variance with the CT/HFD gap.

  1. The effect of reconnection electric field on crescent and U-shaped distribution functions in asymmetric reconnection with no guide field

    Science.gov (United States)

    Bessho, N.; Chen, L.-J.; Hesse, M.; Wang, S.

    2017-07-01

    Electron distribution functions in the electron diffusion region in asymmetric reconnection without a guide field are studied by means of theory and 2-dimensional particle-in-cell (PIC) simulations. The effect of the reconnection electric field on crescent-shaped distribution functions is to broaden the thickness of the crescent. We express the thickness of the crescent as a function of field strengths, the distance from the X-line, and the time electrons spend executing meandering orbits. The electron distribution at the reconnection X-line exhibits a U-shaped structure with an opening angle in the direction of the reconnection electric field. We predict the opening angle of the U-shaped distribution by considering acceleration of the meandering electrons by the reconnection electric field. Results from particle tracing in PIC simulations and theoretical analysis agree. The above predictions provide guidance to interpret measurements by spacecraft from electron diffusion regions in asymmetric reconnection.

  2. Ingestion into the upstream wheelspace of an axial turbine stage

    Science.gov (United States)

    Green, T.; Turner, A. B.

    1994-04-01

    The upstream wheelspace of an axial air turbine stage complete with nozzle guide vanes (NGVs) and rotor blades (430 mm mean diameter) has been tested with the objective of examining the combined effect of NGVs and rotor blades on the level of mainstream ingestion for different seal flow rates. A simple axial clearance seal was used with the rotor spun up to 6650 rpm by drawing air through it from atmospheric pressure with a large centrifugal compressor. The effect of rotational speed was examined for several constant mainstream flow rates by controlling the rotor speed with an air brake. The circumferential variation in hub static pressure was measured at the trailing edge of the NGVs upstream of the seal gap and was found to affect ingestion significantly. The hub static pressure distribution on the rotor blade leading edges was rotor speed dependent and could not be measured in the experiments. The Denton three-dimensional CFD computer code was used to predict the smoothed time-dependent pressure field for the rotor together with the pressure distribution downstream of the NGVs. The level and distribution of mainstream ingestion, and thus, the seal effectiveness, was determined from nitrous oxide gas concentration measurements and related to static pressure measurements made throughout the wheelspace. With the axial clearance rim seal close to the rotor the presence of the blades had a complex effect. Rotor blades in connection with NGVs were found to reduce mainstream ingestion seal flow rates significantly, but a small level of ingestion existed even for very high levels of seal flow rate.

  3. Numerical Simulation of Flow Field in Flow-guide Tank of China Advanced Research Reactor

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The flow-guide tank of China advanced research reactor (CARR) is located at the top of the reactor vessel and connected with the inlet coolant pipe. It acts as a reactor inlet coolant distributor and plays an important role in reducing the flow-induced vibration of the internal components of the reactor core. Several designs of the flow-guide tank have been proposed, however, the final design option has to be made after detailed investigation of the velocity profile within the flow-guide tank for each configuration.

  4. SU-E-T-255: Optimized Supine Craniospinal Irradiation with Image-Guided and Field Matched Beams

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Z; Holupka, E; Naughton, J; Williams, H; Galper, S; Huang, K [Beth Israel Deaconess Medical Center, Boston, MA (Israel)

    2014-06-01

    Purpose: Conventional craniospinal irradiation (CSI) challenges include dose inhomogeneity at field junctions and position uncertainty due to the field divergence, particular for the two spinal fields. Here we outline a new supine CSI technique to address these difficulties. Methods: Patient was simulated in supine position. The cranial fields had isocenter at C2/C3 vertebral and were matched with 1st spinal field. Their inferior border was chosen to avoid the shoulder, as well as chin from the 1st spine field. Their collimator angles were dependent on asymmetry jaw setting of the 1st spinal field. With couch rotation, the spinal field gantry angles were adjusted to ensure, the inferior border of 1st and superior border of 2nd spinal fields were perpendicular to the table top. The radio-opaque wire position for the spinal junction was located initially by the light field from an anterior setup beam, and was finalized by the portal imaging of the 1st spinal field. With reference to the spinal junction wire, the fields were matched by positioning the isocenter of the 2nd spinal field. A formula was derived to optimize supine CSI treatment planning, by utilizing the relationship among the Yjaw setting, the spinal field gantry angles, cranial field collimator angles, and the spinal field isocenters location. The plan was delivered with portal imaging alignment for the both cranial and spinal junctions. Results: Utilizing this technique with matching beams, and conventional technique such as feathering and forwarding planning, a homogenous dose distribution was achieved throughout the entire CSI treatment volume including the spinal junction. Placing the spinal junction wire visualized in both spinal portals, allows for precise determination and verification of the appropriate match line of the spine fields. Conclusion: This technique of optimization supine CSI achieved a homogenous dose distributions and patient localization accuracy with image-guided and matched beams.

  5. Extended Hamiltonian Formalism of the Pure Space-Like Axial Gauge Schwinger Model II

    CERN Document Server

    Nakawaki, Y; Nakawaki, Yuji; Cartor, Gary Mc

    2004-01-01

    Canonical methods are not sufficient to properly quantize space-like axial gauges. In this paper, we obtain guiding principles which allow the construction of an extended Hamiltonian formalism for pure space-like axial gauge fields. To do so, we clarify the general role residual gauge fields play in the space-like axial gauge Schwinger model. In all the calculations we fix the gauge using a rule, $n{\\cdot}A=0$, where $n$ is a space-like constant vector and we refer to its direction as $x_-$. Then, to begin with, we construct a formulation in which the quantization surface is space-like but not parallel to the direction of $n$. The quantization surface has a parameter which allows us to rotate it, but when we do so we keep the direction of the gauge field fixed. In that formulation we can use canonical methods. We bosonize the model to simplify the investigation. We find that the antiderivative, $({\\partial}_-)^{-1}$, is ill-defined whatever quantization coordinates we use as long as the direction of $n$ is sp...

  6. Evaluation of Guiding Device for Downstream Fish Migration with in-Field Particle Tracking Velocimetry and CFD

    Directory of Open Access Journals (Sweden)

    Staffan Lundstrom

    2015-01-01

    Full Text Available The performance of a fish guiding device located just upstream a hydropower plant is scrutinized. The device is designed to redirect surface orientated down-stream migrating fish (smolts away from the turbines towards a spillway that act as a relatively safe fishway. Particles are added up-stream the device and the fraction particles going to the spillway is measured. A two-frame Particle Tracking Velocimetry algorithm is used to derive the velocity field of the water. The experimental results are compared to simulations with CFD. If the smolts move passively as the particles used in the study the guiding device works very well and some modifications may optimize its performance. In-field Particle Tracking Velocimetry is a suitable technique for the current case and the results compare well with numerical simulations.

  7. Preliminary experimental investigation of an X-band Cerenkov-type high power microwave oscillator without guiding magnetic field

    Science.gov (United States)

    Guo, Liming; Shu, Ting; Li, Zhiqiang; Ju, Jinchuan; Fang, Xiaoting

    2017-02-01

    Among high power microwave (HPM) generators without guiding magnetic field, Cerenkov-type oscillator is expected to achieve a relatively high efficiency, which has already been realized in X-band in our previous simulation work. This paper presents the preliminary experimental investigations into an X-band Cerenkov-type HPM oscillator without guiding magnetic field. Based on the previous simulation structure, some modifications regarding diode structure were made. Different cathode structures and materials were tested in the experiments. By using a ring-shaped graphite cathode, microwave of about one hundred megawatt level was generated with a pure center frequency of 9.14 GHz, and an efficiency of about 1.3%. As analyzed in the paper, some practical issues reduce the efficiency in experiments, such as real features of the electron beam, probable breakdown regions on the cathode surface which can damage the diode, and so forth.

  8. Analysis of the dependence of the guided mode field distribution on the silica bridges in hollow-core Bragg fibers

    DEFF Research Database (Denmark)

    Selleri, S.; Poli, F.; Foroni, M.

    2007-01-01

    The guiding properties of fabricated air-silica Bragg fibers with different geometric characteristics have been numerically investigated through a modal solver based on the finite element method. The method has been used to compute the dispersion curves, the loss spectra and the field distribution......, a rounded air-hole one, which better describes the real fiber transverse section. Results have shown.the presence of anti-crossing points in the effective index curves associated with the transition of the guided mode to a surface mode. Moreover, it has been verified that these surface modes are responsible...... of the loss peaks in the fiber transmission spectra, also experimentally measured. Surface modes are mainly localized in the regions of the cladding where the bridge supports join the cladding rings, forming silica islands where the field can focuses....

  9. Surface nanoscale axial photonics

    CERN Document Server

    Sumetsky, M

    2011-01-01

    Dense photonic integration promises to revolutionize optical computing and communications. However, efforts towards this goal face unacceptable attenuation of light caused by surface roughness in microscopic devices. Here we address this problem by introducing Surface Nanoscale Axial Photonics (SNAP). The SNAP platform is based on whispering gallery modes circulating around the optical fiber surface and undergoing slow axial propagation readily described by the one-dimensional Schr\\"odinger equation. These modes can be steered with dramatically small nanoscale variation of the fiber radius, which is quite simple to introduce in practice. The extremely low loss of SNAP devices is achieved due to the fantastically low surface roughness inherent in a drawn fiber surface. In excellent agreement with the developed theory, we experimentally demonstrate localization of light in quantum wells, halting light by a point source, tunneling through potential barriers, dark states, etc. This demonstration, prototyping basi...

  10. Non-Maxwellian electron distribution functions due to self-generated turbulence in collisionless guide-field reconnection

    CERN Document Server

    Muñoz, P A

    2016-01-01

    Non-Maxwellian electron velocity space distribution functions (EVDF) are useful signatures of plasma conditions and non-local consequences of collisionless magnetic reconnection. In the past, the evolution of the EVDFs was investigated mainly for antiparallel or weak-guide-field reconnection. The shape of EVDFs is, however, not well known yet for oblique (or component-) reconnection in dependence on a finite guide magnetic field component perpendicular to the reconnection plane. In view of the multi-spacecraft mission MMS, we derive the non-Maxwellian features of EVDFs formed by collisionless magnetic reconnection starting from very weak ($b_g\\approx0$) up to very strong ($b_g=8$) guide-field strengths $b_g$, taking into account the feedback of the self-generated turbulence. For this sake, we carry out 2.5D fully-kinetic Particle-in-Cell (PiC) simulations using the ACRONYM code. We obtained anisotropic EVDFs and the distribution of electron beams propagating along the separatrices as well as in the exhaust re...

  11. Optimum Tilt Angle of Flow Guide in Steam Turbine Exhaust Hood Considering the Effect of Last Stage Flow Field

    Science.gov (United States)

    CAO, Lihua; LIN, Aqiang; LI, Yong; XIAO, Bin

    2017-07-01

    Heat transfer and vacuum in condenser are influenced by the aerodynamic performance of steam turbine exhaust hood. The current research on exhaust hood is mainly focused on analyzing flow loss and optimal design of its structure without consideration of the wet steam condensing flow and the exhaust hood coupled with the front and rear parts. To better understand the aerodynamic performance influenced by the tilt angle of flow guide inside a diffuser, taking a 600 MW steam turbine as an example, a numerical simulator CFX is adopted to solve compressible three-dimensional (3D) Reynolds time-averaged N-S equations and standard k- ɛ turbulence model. And the exhaust hood flow field influenced by different tilt angles of flow guide is investigated with consideration of the wet steam condensing flow and the exhaust hood coupled with the last stage blades and the condenser throat. The result shows that the total pressure loss coefficient and the static pressure recovery coefficient of exhaust hood change regularly and monotonously with the gradual increase of tilt angle of flow guide. When the tilt angle of flow guide is within the range of 30° to 40°, the static pressure recovery coefficient is in the range of 15.27% to 17.03% and the total pressure loss coefficient drops to approximately 51%, the aerodynamic performance of exhaust hood is significantly improved. And the effective enthalpy drop in steam turbine increases by 0.228% to 0.274%. It is feasible to obtain a reasonable title angle of flow guide by the method of coupling the last stage and the condenser throat to exhaust hood in combination of the wet steam model, which provides a practical guidance to flow guide transformation and optimal design in exhaust hood.

  12. Optimum Tilt Angle of Flow Guide in Steam Turbine Exhaust Hood Considering the Effect of Last Stage Flow Field

    Science.gov (United States)

    CAO, Lihua; LIN, Aqiang; LI, Yong; XIAO, Bin

    2017-03-01

    Heat transfer and vacuum in condenser are influenced by the aerodynamic performance of steam turbine exhaust hood. The current research on exhaust hood is mainly focused on analyzing flow loss and optimal design of its structure without consideration of the wet steam condensing flow and the exhaust hood coupled with the front and rear parts. To better understand the aerodynamic performance influenced by the tilt angle of flow guide inside a diffuser, taking a 600 MW steam turbine as an example, a numerical simulator CFX is adopted to solve compressible three-dimensional (3D) Reynolds time-averaged N-S equations and standard k-ɛ turbulence model. And the exhaust hood flow field influenced by different tilt angles of flow guide is investigated with consideration of the wet steam condensing flow and the exhaust hood coupled with the last stage blades and the condenser throat. The result shows that the total pressure loss coefficient and the static pressure recovery coefficient of exhaust hood change regularly and monotonously with the gradual increase of tilt angle of flow guide. When the tilt angle of flow guide is within the range of 30° to 40°, the static pressure recovery coefficient is in the range of 15.27% to 17.03% and the total pressure loss coefficient drops to approximately 51%, the aerodynamic performance of exhaust hood is significantly improved. And the effective enthalpy drop in steam turbine increases by 0.228% to 0.274%. It is feasible to obtain a reasonable title angle of flow guide by the method of coupling the last stage and the condenser throat to exhaust hood in combination of the wet steam model, which provides a practical guidance to flow guide transformation and optimal design in exhaust hood.

  13. Axial super-resolution evanescent wave tomography.

    Science.gov (United States)

    Pendharker, Sarang; Shende, Swapnali; Newman, Ward; Ogg, Stephen; Nazemifard, Neda; Jacob, Zubin

    2016-12-01

    Optical tomographic reconstruction of a three-dimensional (3D) nanoscale specimen is hindered by the axial diffraction limit, which is 2-3 times worse than the focal plane resolution. We propose and experimentally demonstrate an axial super-resolution evanescent wave tomography method that enables the use of regular evanescent wave microscopes like the total internal reflection fluorescence microscope beyond surface imaging and achieve a tomographic reconstruction with axial super-resolution. Our proposed method based on Fourier reconstruction achieves axial super-resolution by extracting information from multiple sets of 3D fluorescence images when the sample is illuminated by an evanescent wave. We propose a procedure to extract super-resolution features from the incremental penetration of an evanescent wave and support our theory by one-dimensional (along the optical axis) and 3D simulations. We validate our claims by experimentally demonstrating tomographic reconstruction of microtubules in HeLa cells with an axial resolution of ∼130  nm. Our method does not require any additional optical components or sample preparation. The proposed method can be combined with focal plane super-resolution techniques like stochastic optical reconstruction microscopy and can also be adapted for THz and microwave near-field tomography.

  14. Axial super-resolution evanescent wave tomography

    Science.gov (United States)

    Pendharker, Sarang; Shende, Swapnali; Newman, Ward; Ogg, Stephen; Nazemifard, Neda; Jacob, Zubin

    2016-12-01

    Optical tomographic reconstruction of a 3D nanoscale specimen is hindered by the axial diffraction limit, which is 2-3 times worse than the focal plane resolution. We propose and experimentally demonstrate an axial super-resolution evanescent wave tomography (AxSET) method that enables the use of regular evanescent wave microscopes like Total Internal Reflection Fluorescence Microscope (TIRF) beyond surface imaging, and achieve tomographic reconstruction with axial super-resolution. Our proposed method based on Fourier reconstruction achieves axial super-resolution by extracting information from multiple sets of three-dimensional fluorescence images when the sample is illuminated by an evanescent wave. We propose a procedure to extract super-resolution features from the incremental penetration of an evanescent wave and support our theory by 1D (along the optical axis) and 3D simulations. We validate our claims by experimentally demonstrating tomographic reconstruction of microtubules in HeLa cells with an axial resolution of $\\sim$130 nm. Our method does not require any additional optical components or sample preparation. The proposed method can be combined with focal plane super-resolution techniques like STORM and can also be adapted for THz and microwave near-field tomography.

  15. Gapless line for the anisotropic Heisenberg spin-1/2 chain in a magnetic field and the quantum axial next-nearest-neighbor Ising chain

    OpenAIRE

    2003-01-01

    We study the anisotropic Heisenberg (XYZ) spin-1/2 chain placed in a magnetic field pointing along the x-axis. We use bosonization and a renormalization group analysis to show that the model has a non-trivial fixed point at a certain value of the XY anisotropy a and the magnetic field h. Hence, there is a line of critical points in the (a,h) plane on which the system is gapless, even though the Hamiltonian has no continuous symmetry. The quantum critical line corresponds to a spin-flop transi...

  16. Theoretical predictions for spatially-focused heating of magnetic nanoparticles guided by magnetic particle imaging field gradients

    Energy Technology Data Exchange (ETDEWEB)

    Dhavalikar, Rohan [Department of Chemical Engineering, University of Florida, 1030 Center Drive, Gainesville, FL 32611 (United States); Rinaldi, Carlos, E-mail: carlos.rinaldi@bme.ufl.edu [Department of Chemical Engineering, University of Florida, 1030 Center Drive, Gainesville, FL 32611 (United States); J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, 1275 Center Drive, Gainesville, FL 32611 (United States)

    2016-12-01

    Magnetic nanoparticles in alternating magnetic fields (AMFs) transfer some of the field's energy to their surroundings in the form of heat, a property that has attracted significant attention for use in cancer treatment through hyperthermia and in developing magnetic drug carriers that can be actuated to release their cargo externally using magnetic fields. To date, most work in this field has focused on the use of AMFs that actuate heat release by nanoparticles over large regions, without the ability to select specific nanoparticle-loaded regions for heating while leaving other nanoparticle-loaded regions unaffected. In parallel, magnetic particle imaging (MPI) has emerged as a promising approach to image the distribution of magnetic nanoparticle tracers in vivo, with sub-millimeter spatial resolution. The underlying principle in MPI is the application of a selection magnetic field gradient, which defines a small region of low bias field, superimposed with an AMF (of lower frequency and amplitude than those normally used to actuate heating by the nanoparticles) to obtain a signal which is proportional to the concentration of particles in the region of low bias field. Here we extend previous models for estimating the energy dissipation rates of magnetic nanoparticles in uniform AMFs to provide theoretical predictions of how the selection magnetic field gradient used in MPI can be used to selectively actuate heating by magnetic nanoparticles in the low bias field region of the selection magnetic field gradient. Theoretical predictions are given for the spatial decay in energy dissipation rate under magnetic field gradients representative of those that can be achieved with current MPI technology. These results underscore the potential of combining MPI and higher amplitude/frequency actuation AMFs to achieve selective magnetic fluid hyperthermia (MFH) guided by MPI. - Highlights: • SAR predictions based on a field-dependent magnetization relaxation model.

  17. L2F anemometry measurements of the inter-row flow field within a transonic axial compressor provided with curved windows

    Science.gov (United States)

    Ottavy, Xavier; Trébinjac, Isabelle; Vouillarmet, André

    1999-09-01

    When measurements are performed in high speed, small-scale compressors, the use of curved glass windows is required in order to avoid any mismatch between the measurement window and the casing. However, the glass curvature leads to optical distortions, which hinder acceptable measurements and can even prevent the acquisition of any data. Thus, an original optical assembly, which consists in inserting a simple and inexpensive corrective window between the frontal lens of the anemometer and the shroud window, is proposed. The way of determining the geometric characteristics and the position of this corrective window, which restores very acceptable foci, is presented in the paper. The reliability of this corrective optical assembly is highlighted by comparative measurements in a test case. Using such an optical setting, L2F measurements were realised along a section, downstream of the inlet guide vane (IGV) of a transonic compressor stage. The spatial resolution leads to a good description of the interaction of the wake with the oblique shock emanating from the leading edge of the rotor. A phenomenological study of the wake/shock interaction with a change of frame is realised using the streamwise equation of the transport of vorticity.

  18. L2F Anemometry Measurements of the Inter-Row Flow Field Within a Transonic Axial Compressor Provided with Curved Windows

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    When measurements are performed in high speed,small-scale compressors,the use of curved glass windows is required in order to avoid any mismatch between the measurement window and the casing.However,the glass curvature leads to optical distortions,which hinder acceptable measurements and can even prevent the acquisition of any data.Thus,an original optical assembly,which consists in inserting a simple and inexpensive corrective window between the frontal lens of the anemometer and the shroud window,is proposed.The way of determining the geometric characteristics and the position of this corrective window,which restores very acceptable foci,is presented in the paper.The reliability of this corrective optical assembly is highlighted by comparative measurements in a test case .Using such an optical setting,L2F measurements were realised along a section,downstream of the inlet guide vane(IGV) of a transonic compressor stage.The spatial resolution leads to a good description of the interaction of the wake with the oblique shock emanating from the leading edge of the rotor.A phenomenological study of the wake/shock interaction with a change of frame is realised using the streamwise equation of the transport of vorticity.

  19. Air-coupled guided wave detection and wavenumber filtering to full-field representation of delamination in composite plates

    Science.gov (United States)

    Testoni, N.; De Marchi, L.; Marzani, A.

    2014-03-01

    Delamination faults in composite plates are considered dangerous as they can cause catastrophic failure before being visually assessed. Effects of delaminations are particularly relevant in guided waves scattering, local resonances and mode conversion. Detecting and analyzing these phenomena is relevant for plate characterization. In this work, leaky guided waves are used to detect delamination in composite plates. To such purpose, a hybrid ultrasonic set-up and a dedicated signal processing are proposed. An air-probe with a proper lift-off is used to detect the leakage in terms of air pressure wave over the plate surface. A piezoelectric transducer is used to generate acoustic guided waves in the composite plate. Multiple acquisitions are averaged to increase the SNR for each position of the air-probe. Curvelet Transform (CT) domain processing of the projection coefficients of the acquired elastic wave is exploited to decompose waves that are overlapped both in the time/space and in the frequency/wavenumber domain. In fact, CT is a special member of the family of multiscale and multidimensional transforms whose spatial and temporal localization is very well suited for processing signals which are sparse in the above mentioned domains. In this work this sparsity is exploited to emphasize the information of leaky guided waves scattered by the delamination by removing from the data the information related to the incident wave field. As an application, the presence of a delamination generated by a 21 Joule impact performed on a 4.9 mm thickness composite laminate was detected contactless by exploiting guided wave leakage.

  20. INFX GUIDE: DEPARTMENT OF ENERGY BILATERAL AGREEMENTS FOR COOPERATION IN THE FIELD OF RADIOACTIVE WASTE MANAGEMENT (INFX: INTERNATIONAL INFORMATION EXCHANGE)

    Energy Technology Data Exchange (ETDEWEB)

    Harman, K. M.; Lakey, L. T.; Leigh, I. W.; Jeffs, A. G.

    1985-07-01

    As the U. S. Department of Energy (DOE) and DOE contractors have increased the magnitude and scope of their cooperative activities with other nations in the nuclear fuel cycle and waste management field, a need has developed for ready sources of information concerning foreign waste management programs, DOE technology exchange policies, bilateral fuel cycle and waste management agreements and plans and activities to implement those agreements. The INFX (International InLormation E~change) Guide is one of a series of documents that have been prepared to provide that information. The INFX Guide has been compiled under the charter of PNL's International Support Office (IPSO) to maintain for DOE a center to collect, organize, evaluate and disseminate information on foreign and international radioactive waste management programs. Because the information in this document is constantly subject to change, the document is assembled in loose-leaf form to accommodate frequent updates.

  1. Critical Axial Load

    Directory of Open Access Journals (Sweden)

    Walt Wells

    2008-01-01

    Full Text Available Our objective in this paper is to solve a second order differential equation for a long, simply supported column member subjected to a lateral axial load using Heun's numerical method. We will use the solution to find the critical load at which the column member will fail due to buckling. We will calculate this load using Euler's derived analytical approach for an exact solution, as well as Euler's Numerical Method. We will then compare the three calculated values to see how much they deviate from one another. During the critical load calculation, it will be necessary to calculate the moment of inertia for the column member.

  2. Field Guide to Fossils. Earth Science Curriculum Project Pamphlet Series PS-4.

    Science.gov (United States)

    Beerbower, James R.

    This guide introduces the study of fossils and means through which this study may provide clues to ancient environments and geology. Presented are discussions about the origin of many types of organisms, origin of organic communities, evolution, and extinction of species. Suggestions are provided for likely collection sites, methods of collection,…

  3. A field guide to the Silurian Echinodermata of the British Isles: Part 1 - Eleutherozoa and Rhombifera

    NARCIS (Netherlands)

    Lewis, D.N.; Donovan, S.K.; Crabb, P.; Gladwell, D.J.

    2007-01-01

    The Palaeozoic echinoderms of the British Isles are most diverse in the Silurian and Lower Carboniferous. This guide discusses and illustrates members of all major groups of echinoderms, apart from the crinoids, from the Silurian of these islands. Groups considered include the echinoids (five taxa),

  4. Strategies for Change: A Field Guide to Social Marketing for School Health Professionals

    Science.gov (United States)

    American School Health Association (NJ3), 2004

    2004-01-01

    Strategies for Change outlines how to use social marketing strategies to influence change in the health programs in a building, district or community. Authors describe how to develop a strategy to influence district administrators, school board members, colleagues and parents. This step-by-step guide leads through the process for developing,…

  5. Supplement for Curriculum Guide for Science: Vietnamese-Speaking Students, Kindergarten-Upper Two. Field Test.

    Science.gov (United States)

    Chicago Board of Education, IL.

    This supplement to the Chicago public schools' science curriculum guide is for use with Vietnamese-speaking students and is designed to help students make the transition to science learning in English. English-Vietnamese vocabulary lists, independent learning activities (in Vietnamese), and teaching aids (cultural activities such as songs,…

  6. Solar Energy Education. Industrial arts: teacher's guide. Field test edition. [Includes glossary

    Energy Technology Data Exchange (ETDEWEB)

    1981-05-01

    An instructional aid is presented which integrates the subject of solar energy into the classroom study of industrial arts. This guide for teachers was produced in addition to the student activities book for industrial arts by the USDOE Solar Energy Education. A glossary of solar energy terms is included. (BCS)

  7. Field Guide to Northeastern Ferns. New York State Museum Bulletin Number 444.

    Science.gov (United States)

    Ogden, Eugene C.

    This guide was developed for use by individuals with little or no botanical training who wish to identify native ferns of New York, New England, New Jersey, and Pennsylvania. A random access key, developed by the author, provides multiple pathways for identification of 60 species in 29 genera of ferns. (CS)

  8. Strategies for Change: A Field Guide to Social Marketing for School Health Professionals

    Science.gov (United States)

    American School Health Association (NJ3), 2004

    2004-01-01

    Strategies for Change outlines how to use social marketing strategies to influence change in the health programs in a building, district or community. Authors describe how to develop a strategy to influence district administrators, school board members, colleagues and parents. This step-by-step guide leads through the process for developing,…

  9. Cascaded fiber-optic Fabry-Perot interferometers with Vernier effect for highly sensitive measurement of axial strain and magnetic field.

    Science.gov (United States)

    Zhang, Peng; Tang, Ming; Gao, Feng; Zhu, Benpeng; Fu, Songnian; Ouyang, Jun; Shum, Perry Ping; Liu, Deming

    2014-08-11

    We report a highly sensitive fiber-optic sensor based on two cascaded intrinsic fiber Fabry-Perot interferometers (IFFPIs). The cascaded IFFPIs have different free spectral ranges (FSRs) and are formed by a short section of hollow core photonic crystal fiber sandwiched by two single mode fibers. With the superposition of reflective spectrum with different FSRs, the Vernier effect will be generated in the proposed sensor and we found that the strain sensitivity of the proposed sensor can be improved from 1.6 pm/με for a single IFFPI sensor to 47.14 pm/με by employing the Vernier effect. The sensor embed with a metglas ribbon can be also used to measure the magnetic field according to the similar principle. The sensitivity of the magnetic field measurement is achieved to be 71.57 pm/Oe that is significantly larger than the 2.5 pm/Oe for a single IFFPI sensor.

  10. Measurement of Full Field Strains in Filament Wound Composite Tubes Under Axial Compressive Loading by the Digital Image Correlation (DIC) Technique

    Science.gov (United States)

    2013-05-01

    McNeill , S. R. Determination of Displacements Using an Improved Digital Image Correlation Method. Computer Vision August 1983. 13 12. Bruck, H. A... McNeill , S. R.; Russell, S. S.; Sutton, M. A. Use of Digital Image Correlation for Determination of Displacements and Strains. Non-Destructive...Evaluation for Aerospace Requirements, 1989. 13. Sutton, M. A.; McNeill , S. R.; Helm, J. D.; Schreier, H. Full-field Non-Contacting Measurement of

  11. A Guided Self-Consistent-Field Method for Excited-State Wave Function Optimization: Applications to Ligand-Field Transitions in Transition-Metal Complexes.

    Science.gov (United States)

    Peng, Bo; Van Kuiken, Benjamin E; Ding, Feizhi; Li, Xiaosong

    2013-09-10

    A guided self-consistent field (SCF) method is presented in this paper. This method uses the eigenspace update-and-following idea to improve the SCF method for optimizing wave functions that are higher-energy solutions to the Roothaan-Hall equation. In this method, the eigenvectors of the previous SCF step are used to prediagonalize the current Fock/Kohn-Sham matrix, preserving the ordering of orbital occupations. When the subject of interest is an excited state of the same spin symmetry as the ground state, the initial guess of excited wave function is improved with a preconditioning step. The preconditioning step is an SCF iteration applied to the β spin manifold if the initial guess is generated by orbital permutation in the α spin manifold. This simple preconditioning step gives rise to more-stable SCF convergence using the algorithm presented herein. The guided SCF method is used to optimize ligand-field excited states in tetrahedral transition-metal complexes, and calculate ΔSCF excitation energies. The calculated ligand-field transition energies are compared with those obtained from orbital energy differences, linear response time-dependent density functional theory, and experiments. The excitation energies obtained using the method presented in this work show a significant improvement over orbital energy differences and linear response method.

  12. Theoretical predictions for spatially-focused heating of magnetic nanoparticles guided by magnetic particle imaging field gradients

    Science.gov (United States)

    Dhavalikar, Rohan; Rinaldi, Carlos

    2016-12-01

    Magnetic nanoparticles in alternating magnetic fields (AMFs) transfer some of the field's energy to their surroundings in the form of heat, a property that has attracted significant attention for use in cancer treatment through hyperthermia and in developing magnetic drug carriers that can be actuated to release their cargo externally using magnetic fields. To date, most work in this field has focused on the use of AMFs that actuate heat release by nanoparticles over large regions, without the ability to select specific nanoparticle-loaded regions for heating while leaving other nanoparticle-loaded regions unaffected. In parallel, magnetic particle imaging (MPI) has emerged as a promising approach to image the distribution of magnetic nanoparticle tracers in vivo, with sub-millimeter spatial resolution. The underlying principle in MPI is the application of a selection magnetic field gradient, which defines a small region of low bias field, superimposed with an AMF (of lower frequency and amplitude than those normally used to actuate heating by the nanoparticles) to obtain a signal which is proportional to the concentration of particles in the region of low bias field. Here we extend previous models for estimating the energy dissipation rates of magnetic nanoparticles in uniform AMFs to provide theoretical predictions of how the selection magnetic field gradient used in MPI can be used to selectively actuate heating by magnetic nanoparticles in the low bias field region of the selection magnetic field gradient. Theoretical predictions are given for the spatial decay in energy dissipation rate under magnetic field gradients representative of those that can be achieved with current MPI technology. These results underscore the potential of combining MPI and higher amplitude/frequency actuation AMFs to achieve selective magnetic fluid hyperthermia (MFH) guided by MPI.

  13. High Power Disk Loaded Guide Load

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, Z.D.; /SLAC

    2006-02-22

    A method to design a matching section from a smooth guide to a disk-loaded guide, using a variation of broadband matching, [1, 2] is described. Using this method, we show how to design high power loads. The load consists of a disk-loaded coaxial guide operating in the TE{sub 01}-mode. We use this mode because it has no electric field terminating on a conductor, has no axial currents, and has no current at the cylinder-disk interface. A high power load design that has -35 dB reflection and a 200 MHz, -20 dB bandwidth, is presented. It is expected that it will carry the 600 MW output peak power of the pulse compression network. We use coaxial geometry and stainless steel material to increase the attenuation per cell.

  14. Electromagnetic ultrasonic guided waves

    CERN Document Server

    Huang, Songling; Li, Weibin; Wang, Qing

    2016-01-01

    This book introduces the fundamental theory of electromagnetic ultrasonic guided waves, together with its applications. It includes the dispersion characteristics and matching theory of guided waves; the mechanism of production and theoretical model of electromagnetic ultrasonic guided waves; the effect mechanism between guided waves and defects; the simulation method for the entire process of electromagnetic ultrasonic guided wave propagation; electromagnetic ultrasonic thickness measurement; pipeline axial guided wave defect detection; and electromagnetic ultrasonic guided wave detection of gas pipeline cracks. This theory and findings on applications draw on the author’s intensive research over the past eight years. The book can be used for nondestructive testing technology and as an engineering reference work. The specific implementation of the electromagnetic ultrasonic guided wave system presented here will also be of value for other nondestructive test developers.

  15. 进口导流叶排角度对轴流压气机总压畸变的影响%Numerical Simulation on the Effect of Inlet Guide Vanes on An Axial Flow Compressor under Total Pressure Distortion

    Institute of Scientific and Technical Information of China (English)

    李成龙; 李军; 强晓明; 李凡玉; 罗志煌

    2013-01-01

    Based on three-dimensional Euler equation,a model of a certain three-stages compressor is estab-lished and calculated by adopting a method of body force.This paper mainly analyzes the effect of inlet guide vanes (IGV)on inlet distortion and the relation between IGV's angle and total pressure distortion in operation at the designed rotating speed.The result shows that IGV can improve the flow field and reduce the distortion parameter.The distortion range and the intensity are respectively reduced by 21.4% and 10.2% at the three stage rotor entrance.IGV has a favorable ability of rectification and anti-distortion. With the rise of IGV's angle,the distortion intensity gets lower,but it will come to increase while the IGV's angle reaches a certain value.Meanwhile,IGV will do the best with 45°.%对某三级轴流压气机,利用三维欧拉方程建立模型,采用体积力法进行计算仿真。研究分析 IGV(进口导流叶排)对压气机进气畸变的影响,以及设计转速状态下改善畸变效果最好的IGV 角度。计算结果表明:IGV 可以有效改善流场品质,使压气机各截面的畸变参数都有所减小,例如三级转子进口的畸变角度降低了21.4%,畸变强度降低了10.2%;IGV 起到了很好的整流作用,表现出了显著的减小畸变程度的能力;随着 IGV 角度的增加,畸变强度随之降低,当IGV 角度达到临界值后畸变强度反而开始增大;设计转速下,IGV 临界角度为45°左右,在此角度下改善畸变的效果最好。

  16. 1978 Insect Pest Management Guide: Field and Forage Crops. Circular 899.

    Science.gov (United States)

    Illinois Univ., Urbana. Cooperative Extension Service.

    This circular lists suggested uses of insecticides for the control of field crop pests. Suggestions are given for selection, dosage and application of insecticides to control pests in field corn, alfalfa and clover, small grains, soybeans and grain sorghum. (CS)

  17. 1978 Insect Pest Management Guide: Field and Forage Crops. Circular 899.

    Science.gov (United States)

    Illinois Univ., Urbana. Cooperative Extension Service.

    This circular lists suggested uses of insecticides for the control of field crop pests. Suggestions are given for selection, dosage and application of insecticides to control pests in field corn, alfalfa and clover, small grains, soybeans and grain sorghum. (CS)

  18. Effects of Axial Non-uniform Tip Clearances on Aerodynamic Performance of a Transonic Axial Compressor

    Institute of Scientific and Technical Information of China (English)

    Hongwei MA; Baihe LI

    2008-01-01

    This paper presents a numerical investigation of effects of axial non-uniform tip clearances on the aerodynamic performance of a transonic axial compressor rotor (NASA Rotor 37). The three-dimensional steady flow field within the rotor passage was simulated with the datum tip clearance of 0.356 mm at the design wheel speed of 17188.7 rpm. The simulation results are well consistent with the measurement results, which verified the numeri-cal method. Then the three-dimensional steady flow field within the rotor passage was simulated respectively with different axial non-uniform tip clearances. The calculation results showed that optimal axial non-uniform tip clearances could improve the compressor performance, while the efficiency and the pressure ratio of the com-pressor were increased. The flow mechanism is that the axial non-uniform tip clearance can weaken the tip leak-age vortex, blow down low-energy fluids in boundary layers and reduce both flow blockage and tip loss.

  19. MMS observations of plasma wave and electron energization in the electron diffusion region of asymmetric reconnection with strong guide field

    Science.gov (United States)

    Xiao, Chijie; Zhao, Siqi; Shi, Mijie; Pu, Zuyin; Wang, Xiaogang

    2016-10-01

    Here we report an asymmetric reconnection event with strong guide field observed by Magnetospheric Multiscale Mission (MMS) on the dayside magnetopause. In this event there are multiple wave modes, such as electron Alfvenic mode, broadband waves between the lower-hybrid and electron cyclotron frequencies, exist in the vicinity of the electron diffusion region and the separatrix. And the electron velocity distribution functions show that bi-stream electrons with low energy (processes are investigated and comparison with some 3D numerical simulation results. This work was supported by NSFC (Grants 41274168 and 11375053).

  20. Degenerate seaweed to tilted dendrite transition and their growth dynamics in directional solidification of non-axially oriented crystals: a phase-field study

    Science.gov (United States)

    Xing, Hui; Dong, Xianglei; Wu, Hongjing; Hao, Guanhua; Wang, Jianyuan; Chen, Changle; Jin, Kexin

    2016-05-01

    We report the results of a phase-field study of degenerate seaweed to tilted dendrite transition and their growth dynamics during directional solidification of a binary alloy. Morphological selection maps in the planes of (G, Vp) and (ε4, Vp) show that lower pulling velocity, weaker anisotropic strength and higher thermal gradient can enhance the formation of the degenerate seaweed. The tip undercooling shows oscillations in seaweed growth, but it keeps at a constant value in dendritic growth. The M-S instability on the tips and the surface tension anisotropy of the solid-liquid interface are responsible for the formation of the degenerate seaweed. It is evidenced that the place where the interfacial instability occurs determines the morphological transition. The transient transition from degenerate seaweed to tilted dendrite shows that dendrites are dynamically preferred over seaweed. For the tilted dendritic arrays with a large tilted angle, primary spacing is investigated by comparing predicted results with the classical scaling power law, and the growth direction is found to be less sensitive to the pulling velocity and the primary spacing. Furthermore, the effect of the initial interface wavelength on the morphological transition is investigated to perform the history dependence of morphological selection.

  1. Simulation and Experiment Research of Aerodynamic Performance of Small Axial Fans with Struts

    Institute of Scientific and Technical Information of China (English)

    CHU Wei; LIN Peifeng; ZHANG Li; JIN Yingzi; WANG Yanping; Heuy Dong Kim; Toshiaki Setoguchi

    2016-01-01

    Interaction between rotor and struts has great effect on the performance of small axial fan systems.The small axial fan systems are selected as the studied objects in this paper,and four square struts are downstream of the rotor.The cross section of the struts is changed to the cylindrical shapes for the investigation:one is in the same hydranlic diameter as the square struts and another one is in the same cross section as the square struts.Influence of the shape of the struts on the static pressure characteristics,the internal flow and the sound emission of the small axial fans are studied.Standard K-ε turbulence model and SIMPLE algorithm are applied in the calculation of the steady fluid field,and the curves of the pressure rising against the flow rate are obtained,which demonstrates that the simulation results are in nice consistence with the experimental data.The steady calculation results are set as the initial field in the unsteady calculation.Large eddy simulation and PISO algorithm are used in the transient calculation,and the Ffowcs Wtlliams-Hawkings model is introduced to predict the sound level at the eight monitoring points.The research results show that:the static pressure coefficients of the fan with cylindrical struts increase by about 25% compared to the fan with square struts,and the efficiencies increase by about 28.6%.The research provides a theoretical guide for shape optimization and noise reduction of small axial fan with struts.

  2. Excursion guide for the 6th IMCG field symposium in Norway 1994

    OpenAIRE

    1994-01-01

    This guide contains a description of the variations found among the mires in central Norway. The main emphasis is on the hydromorphology, flora and vegetation, but the bird fauna and conservational aspects are also included. The regionality of the vegetation is stressed (5 zones/belts and 5 sections have been mapped). Nine main mire localities that will be visited during the excursion are also described. Rørmyra (locality l), Kaldvassmyra (2) and Toppmyr/Røkmyr (9) are southern boreal mires w...

  3. A microwave transmission-line network guiding electromagnetic fields through a dense array of metallic objects

    CERN Document Server

    Alitalo, Pekka; Vehmas, Joni; Tretyakov, Sergei

    2008-01-01

    We present measurements of a transmission-line network, designed for cloaking applications in the microwave region. The network is used for channelling microwave energy through an electrically dense array of metal objects, which is basically impenetrable to the impinging electromagnetic radiation. With the designed transmission-line network the waves emitted by a source placed in an air-filled waveguide, are coupled into the network and guided through the array of metallic objects. Our goal is to illustrate the simple manufacturing, assembly, and the general feasibility of these types of cloaking devices.

  4. Field and laboratory guide to freshwater cyanobacteria harmful algal blooms for Native American and Alaska Native communities

    Science.gov (United States)

    Rosen, Barry H.; Ann St. Amand,

    2015-09-14

    Cyanobacteria can produce toxins and form harmful algal blooms. The Native American and Alaska Native communities that are dependent on subsistence fishing have an increased risk of exposure to these cyanotoxins. It is important to recognize the presence of an algal bloom in a waterbody and to distinguish a potentially toxic harmful algal bloom from a non-toxic bloom. This guide provides field images that show cyanobacteria blooms, some of which can be toxin producers, as well as other non-toxic algae blooms and floating plants that might be confused with algae. After recognition of a potential toxin-producing cyanobacterial bloom in the field, the type(s) of cyanobacteria present needs to be identified. Species identification, which requires microscopic examination, may help distinguish a toxin-producer from a non-toxin producer. This guide also provides microscopic images of the common cyanobacteria that are known to produce toxins, as well as images of algae that form blooms but do not produce toxins.

  5. An Unbroken Axial-Vector Current Conservation Law

    Science.gov (United States)

    Sharafiddinov, Rasulkhozha S.

    2016-04-01

    The mass, energy and momentum of the neutrino of a true flavor have an axial-vector nature. As a consequence, the left-handed truly neutral neutrino in an axial-vector field of emission can be converted into a right-handed one and vice versa. This predicts the unidenticality of masses, energies and momenta of neutrinos of the different components. Recognizing such a difference in masses, energies, momenta and accepting that the left-handed axial-vector neutrino and the right-handed antineutrino of true neutrality refer to long-lived C-odd leptons, and the right-handed truly neutral neutrino and the left-handed axial-vector antineutrino are of short-lived fermions of C-oddity, we would write a new CP-even Dirac equation taking into account the flavor symmetrical axial-vector mass, energy and momentum matrices. Their presence explains the spontaneous mirror symmetry violation, confirming that an axial-vector current conservation law has never violated. They reflect the availability of a mirror Minkowski space in which a neutrino is characterized by left as well as by right space-time coordinates. Therefore, it is not surprising that whatever the main purposes experiments about a quasielastic axial-vector mass say in favor of an axial-vector mirror Minkowski space-time.

  6. Field Guide to Rock Weathering. Earth Science Curriculum Project Pamphlet Series PS-1.

    Science.gov (United States)

    Boyer, Robert E.

    Highlighted are the effects of weathering through field investigations of the environment, both natural rocks, and the urban environment's pavements, buildings, and cemeteries. Both physical weathering and chemical weathering are discussed. Questions are presented for post-field trip discussion. References and a glossary are provided. (Author/RE)

  7. Bessel beam CARS of axially structured samples

    Science.gov (United States)

    Heuke, Sandro; Zheng, Juanjuan; Akimov, Denis; Heintzmann, Rainer; Schmitt, Michael; Popp, Jürgen

    2015-01-01

    We report about a Bessel beam CARS approach for axial profiling of multi-layer structures. This study presents an experimental implementation for the generation of CARS by Bessel beam excitation using only passive optical elements. Furthermore, an analytical expression is provided describing the generated anti-Stokes field by a homogeneous sample. Based on the concept of coherent transfer functions, the underling resolving power of axially structured geometries is investigated. It is found that through the non-linearity of the CARS process in combination with the folded illumination geometry continuous phase-matching is achieved starting from homogeneous samples up to spatial sample frequencies at twice of the pumping electric field wave. The experimental and analytical findings are modeled by the implementation of the Debye Integral and scalar Green function approach. Finally, the goal of reconstructing an axially layered sample is demonstrated on the basis of the numerically simulated modulus and phase of the anti-Stokes far-field radiation pattern. PMID:26046671

  8. Monte Carlo study of the impact of a magnetic field on the dose distribution in MRI-guided HDR brachytherapy using Ir-192

    NARCIS (Netherlands)

    Beld, E; Seevinck, P R; Lagendijk, J J W; Viergever, M A; Moerland, M A

    2016-01-01

    In the process of developing a robotic MRI-guided high-dose-rate (HDR) prostate brachytherapy treatment, the influence of the MRI scanner's magnetic field on the dose distribution needs to be investigated. A magnetic field causes a deflection of electrons in the plane perpendicular to the magnetic f

  9. Mind the gap - tip leakage vortex in axial turbines

    Science.gov (United States)

    Dreyer, M.; Decaix, J.; Münch-Alligné, C.; Farhat, M.

    2014-03-01

    The tendency of designing large Kaplan turbines with a continuous increase of output power is bringing to the front the cavitation erosion issue. Due to the flow in the gap between the runner and the discharge ring, axial turbine blades may develop the so called tip leakage vortex (TLV) cavitation with negative consequences. Such vortices may interact strongly with the wake of guide vanes leading to their multiple collapses and rebounds. If the vortex trajectory remains close to the blade tip, these collapses may lead to severe erosion. One is still unable today to predict its occurrence and development in axial turbines with acceptable accuracy. Numerical flow simulations as well as the actual scale-up rules from small to large scales are unreliable. The present work addresses this problematic in a simplified case study representing TLV cavitation to better understand its sensitivity to the gap width. A Naca0009 hydrofoil is used as a generic blade in the test section of EPFL cavitation tunnel. A sliding mounting support allowing an adjustable gap between the blade tip and wall was manufactured. The vortex trajectory is visualized with a high speed camera and appropriate lighting. The three dimensional velocity field induced by the TLV is investigated using stereo particle image velocimetry. We have taken into account the vortex wandering in the image processing to obtain accurate measurements of the vortex properties. The measurements were performed in three planes located downstream of the hydrofoil for different values of the flow velocity, the incidence angle and the gap width. The results clearly reveal a strong influence of the gap width on both trajectory and intensity of the tip leakage vortex.

  10. Measurement and definitions of obesity in childhood and adolescence: a field guide for the uninitiated.

    Science.gov (United States)

    Sweeting, Helen N

    2007-10-26

    This paper aims to guide readers embarking on the complex literature in respect of childhood and adolescent obesity. It opens with a discussion of definitions of 'obesity' based on overall fat levels and the significance of fat distribution. This is followed by simple descriptions of the various techniques used to measure fat, including density-based, scanning, bioelectrical impedance and anthropometric methods. The paper then turns to 'overweight' and the measurement of weight in relation to height, particularly via body mass index (BMI). While it is a relatively simple measure and a valuable tool, BMI has several disadvantages, which are described. These include a lack of consensus on which values should be used to define 'overweight' or 'obese', with the result that the literature contains a confusing multiplicity of child and adolescent obesity rates.

  11. FINITE ELEMENT ANALYSIS OF AXIAL FEED BAR ROLLING

    Institute of Scientific and Technical Information of China (English)

    C.G. Xu; G.H. Liu; G.S. Ren; Z. Shen; C.P. Ma; W. W. Ren

    2007-01-01

    A flexible technique of hot working of bars by axial feed rolling was introduced. The processdeformation, strain field, stress field, and temperature field of the parts are analyzed by finite elementmethod (FEM)-simulation software DEFORM-3D. The material flow rule and tool load have beeninvestigated.

  12. Axially Symmetric Cosmological Mesonic Stiff Fluid Models in Lyra's Geometry

    CERN Document Server

    Gad, Ragab M

    2009-01-01

    In this paper, we obtained a new class of axially symmetric cosmological mesonic stiff fluid models in the context of Lyra's geometry. Expressions for the energy, pressure and the massless scalar field are derived by considering the time dependent displacement field. We found that the mesonic scalar field depends on only $t$ coordinate. Some physical properties of the obtained models are discussed.

  13. Growth cone neurotransmitter receptor activation modulates electric field-guided nerve growth.

    Science.gov (United States)

    Erskine, L; McCaig, C D

    1995-10-01

    We have studied the interactions between two nerve guidance cues, which alone induce substantial growth cone turning: endogenous neurotransmitters and small dc electric fields. d-tubocurarine, a nicotinic AChR (acetylcholine receptor) antagonist, inhibited field-induced cathodal orientation of cultured neurites, whereas atropine, a muscarinic AChR blocker, and suramin, a P2-purinoceptor antagonist, markedly enhanced the guidance properties of the applied field. These experiments implicate the activation of growth cone nicotinic AChRs by self-released acetylcholine in the mechanism underpinning electric field-induced neurite orientation and raise the possibility that growth cones release neurotransmitter prior to target interaction in order to assist their own pathfinding. Additionally, they provide the first evidence that coactivation of several neurotransmitter receptors may interact to regulate directed nerve growth. Such interaction in vivo, where guidance signals coexist, would add further levels of control to neurite guidance.

  14. Visual field defects after stroke--a practical guide for GPs.

    Science.gov (United States)

    Luu, Susie; Lee, Andrew W; Daly, Andrew; Chen, Celia S

    2010-07-01

    Visual field defect after stroke can result in significant disability and reduction in quality of life. Visual rehabilitation aims to maximise the residual vision and decrease functional disability. Understanding the rehabilitation options available, and where to refer patients with visual defects after a stroke, can help patients, and their families, in the rehabilitation process. This article provides a review of the functional disability from visual field loss and discusses the various forms of visual rehabilitation. Optical therapy, eye movement therapy and visual field restitution are the rehabilitation therapies currently available. Rehabilitation needs to cater to each patient's specific needs. Any patient recognised as having a visual field defect after stroke needs prompt referral for further assessment and consideration for visual rehabilitation.

  15. Research on a Novel Axial Field Disk Type Switched Reluctance Motor%新型轴向磁场盘式开关磁阻电机的研究

    Institute of Scientific and Technical Information of China (English)

    梅营; 潘再平

    2011-01-01

    提出了一种新型的采用三相6/4极结构的轴向磁场盘式开关磁阻电机,与前人研究较多的单相盘式开关磁阻电机相比,定、转子结构更加简单,加工成本更低,便于调速控制,且克服了单相电机不能自起动的缺陷.使用Ansoft公司的Maxwell 3D软件进行了三维有限元仿真分析,并制作实验样机,验证了电机的性能.%This paper proposed a novel axial field disk type switched reluctance motor ( AFSRM ), which has both the merit of SRM such as simple and robust structure, easy to control and the merit of disk machine such as short shaft, high torque/inertia rate. Comparing with the single phase AFSRM fully researched before, the novel AFSRM has simpler rotor and stator structure, and lower manufacturing cost. Since the novel AFSRM has 6/4 poles, it avoided the weakness of single phase AFSRM, inability to self start-up. In this paper, three-dimensional field and torque analysis of the novel AFSRM were carried out using Maxwell 3D, a 3D finite-element analysis (FEA) software. In addition, a prototype of novel AFSRM was made to validate the design and test the performance.

  16. Toward real-time endoscopically-guided robotic navigation based on a 3D virtual surgical field model

    Science.gov (United States)

    Gong, Yuanzheng; Hu, Danying; Hannaford, Blake; Seibel, Eric J.

    2015-03-01

    The challenge is to accurately guide the surgical tool within the three-dimensional (3D) surgical field for roboticallyassisted operations such as tumor margin removal from a debulked brain tumor cavity. The proposed technique is 3D image-guided surgical navigation based on matching intraoperative video frames to a 3D virtual model of the surgical field. A small laser-scanning endoscopic camera was attached to a mock minimally-invasive surgical tool that was manipulated toward a region of interest (residual tumor) within a phantom of a debulked brain tumor. Video frames from the endoscope provided features that were matched to the 3D virtual model, which were reconstructed earlier by raster scanning over the surgical field. Camera pose (position and orientation) is recovered by implementing a constrained bundle adjustment algorithm. Navigational error during the approach to fluorescence target (residual tumor) is determined by comparing the calculated camera pose to the measured camera pose using a micro-positioning stage. From these preliminary results, computation efficiency of the algorithm in MATLAB code is near real-time (2.5 sec for each estimation of pose), which can be improved by implementation in C++. Error analysis produced 3-mm distance error and 2.5 degree of orientation error on average. The sources of these errors come from 1) inaccuracy of the 3D virtual model, generated on a calibrated RAVEN robotic platform with stereo tracking; 2) inaccuracy of endoscope intrinsic parameters, such as focal length; and 3) any endoscopic image distortion from scanning irregularities. This work demonstrates feasibility of micro-camera 3D guidance of a robotic surgical tool.

  17. Conceptual design and sample preparation of electrode covered single glass macro-capillaries for studying the effect of an external electric field on particle guiding

    Energy Technology Data Exchange (ETDEWEB)

    Wartak, A. [Institute of Applied Physics, TU Wien, A-1040 Vienna (Austria); Bereczky, R.J., E-mail: bereczky.reka@atomki.mta.hu [Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI), H-4026 Debrecen, P.O. Box 51 (Hungary); Kowarik, G. [Institute of Applied Physics, TU Wien, A-1040 Vienna (Austria); Tőkési, K. [Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI), H-4026 Debrecen, P.O. Box 51 (Hungary); Aumayr, F. [Institute of Applied Physics, TU Wien, A-1040 Vienna (Austria)

    2015-07-01

    We present the design and construction of a macroscopic glass capillary covered by electrodes on the outside. With these new capillary targets it will be possible to study the influence of an external electric field on the process of guiding of charged particles through a capillary. The new degrees of freedoms will contribute to both a better fundamental understanding of the guiding phenomenon but might also be of use in practical applications.

  18. Variational Symplectic Integrator for Long-Time Simulations of the Guiding-Center Motion of Charged Particles in General Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    H. Qin and X. Guan

    2008-02-11

    A variational symplectic integrator for the guiding-center motion of charged particles in general magnetic fields is developed for long-time simulation studies of magnetized plasmas. Instead of discretizing the differential equations of the guiding-center motion, the action of the guiding-center motion is discretized and minimized to obtain the iteration rules for advancing the dynamics. The variational symplectic integrator conserves exactly a discrete Lagrangian symplectic structure, and has better numerical properties over long integration time, compared with standard integrators, such as the standard and variable time-step fourth order Runge-Kutta methods.

  19. Decision coaching using the Ottawa family decision guide with parents and their children: a field testing study.

    Science.gov (United States)

    Feenstra, Bryan; Lawson, Margaret L; Harrison, Denise; Boland, Laura; Stacey, Dawn

    2015-02-07

    Although children can benefit from being included in health decisions, little is known about effective interventions to support their involvement. The objective of this study was to evaluate the feasibility and acceptability of decision coaching guided by the Ottawa Family Decision Guide with children and parents considering insulin delivery options for type 1 diabetes (insulin pump, multiple daily injections, or standard insulin injections). Pre-/post-test field testing design. Eligible participants were children (≤18 years) with type 1 diabetes and their parents attending an ambulatory diabetes clinic in a tertiary children's hospital. Parent-child dyads received decision coaching using the Ottawa Family Decision Guide that was pre-populated with evidence on insulin delivery options, benefits, and harms. Primary outcomes were feasibility of recruitment and data collection, and parent and child acceptability of the intervention. Of 16 families invited to participate, 12 agreed and 7 attended the decision coaching session. For the five missed families, two families were unable to attend the session or the decision coach was not available (N=3). Baseline and immediately post-coaching questionnaires were all completed and follow-up questionnaires two weeks post-coaching were missing from one parent-child dyad. Missing questionnaire items were 5 of 340 items for children (1.5%) and 1 of 429 for parents (0.2%). Decision coaching was rated as acceptable with higher scores from parents and their children who were in earlier stages of decision making. Decision coaching with children and their parents considering insulin options was feasible implement and evaluate in our diabetes clinic and was acceptable to participants. Recruitment was difficult due to scheduling restrictions related to the timing of the study. Coaching should target participants earlier in the decision making process and be scheduled at times that are convenient for families and coaches. Findings were

  20. Enhancing isolation of antenna arrays by simultaneously blocking and guiding magnetic field lines using magnetic metamaterials

    Science.gov (United States)

    Liu, Zhaotang; Wang, Jiafu; Qu, Shaobo; Zhang, Jieqiu; Ma, Hua; Xu, Zhuo; Zhang, Anxue

    2016-10-01

    In this article, we propose to enhance the isolation of antenna arrays by manipulating the near-field magnetic coupling between adjacent antennas using magnetic metamaterials (MMs). Due to the artificially designed negative or large permeability, MMs can concentrate or block the magnetic field lines where they are located, which allows us to tune the near-field magnetic coupling strengths between antennas. MMs can play a two-fold role in enhancing antenna isolation. On one hand, the magnetic fields can be blocked in gaps between adjacent antennas using MMs with negative permeability; on the other hand, the magnetic fields can be pulled towards the borders of the antenna array using MMs with large permeability. As an example, we demonstrated a four-element patch antenna array with split-ring resonators (SRR) integrated in the substrate. The measured results show that the isolation can be enhanced by more than 10 dB with the integration of SRRs, even if the gap between antennas is only about 0.082λ. This work provides an effective alternative to the design of high-isolation antenna arrays.