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Sample records for choppers

  1. Chopper spectrometers

    International Nuclear Information System (INIS)

    Chopper spectrometers are devices which measure the dynamics of condensed systems expressed in terms of the scattering function. The scattering function depends on the energy and momentum transfers which are related to the initial and final neutron wave vectors. The resolution of the instrument is limited by the time-of-flight measurements on the scattered beam but the wide range of accessible energy and momentum transfers make chopper spectrometers popular. Several examples of experiments using chopper spectrometers are presented

  2. Uhv compatible chopper system

    International Nuclear Information System (INIS)

    A time-of-flight system utilizing a novel mechanical chopper has been developed to measure the energy spectrum of neutral deuterium atoms emitted from a tokamak plasma. The chopper system consists of a motor, a magnetically levitated shaft, and a chopper disc. The 20 g disc is rigidly attached to a 159 g shaft assembly and the set is supported against gravity in vacuum by permanent magnets and a stabilizing servo system. All components are uhv compatible to avoid contamination to the tokamak and to the detector. The 25.4 cm OD, .005 cm thick, 301 stainless steel chopper disc has 24 .025 cm wide slots photoetched at an 11.4 cm radius. An effective aperture time of .55 μs is achieved during typical steady state operation at 22,500 rpm with a vacuum pressure of 2 x 10-8 torr

  3. Uhv compatible chopper system

    Energy Technology Data Exchange (ETDEWEB)

    Voss, D.E.; Cohen, S.A.

    1979-11-01

    A time-of-flight system utilizing a novel mechanical chopper has been developed to measure the energy spectrum of neutral deuterium atoms emitted from a tokamak plasma. The chopper system consists of a motor, a magnetically levitated shaft, and a chopper disc. The 20 g disc is rigidly attached to a 159 g shaft assembly and the set is supported against gravity in vacuum by permanent magnets and a stabilizing servo system. All components are uhv compatible to avoid contamination to the tokamak and to the detector. The 25.4 cm OD, .005 cm thick, 301 stainless steel chopper disc has 24 .025 cm wide slots photoetched at an 11.4 cm radius. An effective aperture time of .55 ..mu..s is achieved during typical steady state operation at 22,500 rpm with a vacuum pressure of 2 x 10/sup -8/ torr.

  4. New chopper control at ILL

    Energy Technology Data Exchange (ETDEWEB)

    Descamps, F. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    Proper phasing is an essential characteristic of the chopper systems used at ILL. A wide variety of choppers and selectors differing in weight, speed and bearing types are controlled by a unique electronic card performing digital adaptative filtering. The chopper regulation system is described. (author).

  5. Neutron chopper development at LANSCE

    International Nuclear Information System (INIS)

    Progress is reported on neutron chopper systems for the Los Alamos Neutron Scattering Center pulsed spallation neutron source. This includes the development of 600+ Hz active magnetic bearing neutron chopper and a high speed control system designed to operate with the Proton Storage Ring to phase the chopper to the neutron source. 5 refs., 3 figs

  6. Infrared Sensor with Liquid Crystal Chopper

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An infrared sensor using the liquid crystal chopper is presented. The infrared sensor is designed to detect infrared rays with a pyroelectric element used as a liquid crystal chopper in such an infrared sensor or the like.

  7. A microprocessor system for a neutron chopper

    International Nuclear Information System (INIS)

    An electronic system with the use of a microprocessor for operation automation, stabilization of speed and phase in the IBR-2 neutron chopper sis described. The root mean square deviation of chopper phase for 5 Hz frequency of reactor operation does not exceed 50 μs

  8. IPNS Chopper Control and Accelerator Interface Systems

    International Nuclear Information System (INIS)

    Several of the instruments at the Intense Pulsed Neutron Source (IPNS) at Argonne use rotating Fermi choppers. The techniques used to control the speed and phase of these rotating devices are discussed

  9. IPNS accelerator system and neutron chopper synchronization

    International Nuclear Information System (INIS)

    Several of the neutron scattering instruments at the Intense Pulsed Neutron Source (IPNS) at Argonne use neutron choppers for monochromatization of the neutron beam. Since the neutron burst is produced by a proton beam extracted from the Rapid Cycling Synchrotron (RCS), precise synchronization must be maintained between the RCS and the chopper aperture to minimize the degradation of energy resolution. The first attempts at synchronization were made in 1978 on the ZING-P' facility with a single chopper. Synchronization was further complicated after IPNS began operating in 1981 when a total of three chopper experiments came on-line. The system in use during that period of time was able to maintain synchronization with typical data collection efficiencies ranging from 20 to 70%. A synchronization system improvement, installed in late 1982, increased the data collection efficiencies of all the IPNS chopper systems to 99+%. The development of the RCS and neutron chopper synchronization system is described together with a detailed description of the present system

  10. Chopper Circuits Developed for EV Drive Application

    Science.gov (United States)

    Tsuruta, Yukinori; Kawamura, Atsuo

    In this paper, the technical stream on a high efficiency and high frequency chopper for the automotive industry, new energy and energy conservation technology field is surveyed. QRAS (Quasi-resonant Regenerating Active Snubber) and SAZZ (Snubber Assisted Zero Voltage and Zero Current Transition) topologies aimed for the electric vehicle (EV) drive application are proposed. 25kHz-8kW QRAS, 100kHz-8kW SAZZ choppers and 50kHz-25kW bilateral SAZZ-1 chopper are constructed and tested under rating conditions. It is verified that SAZZ topology retains high efficiency even at the increased operating frequency of 100kHz. It is shown that high efficiency can be realized at high operating frequency even in high power converters by QRAS and newly proposed SAZZ soft switching topologies.

  11. Conceptual design of a Disk Chopper Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Copley, J.R.D. [National Institute of Standards and Technology, Gaithersburg, MD (United States)

    1997-09-01

    We describe methods that we have used for the conceptual design of the Disk Chopper Spectrometer at the Cold Neutron Research Facility, National Institute of Standards and Technology. Most of the discussion concerns the multiple chopper system. No single design method is best in every situation. We believe that an analytical approach is preferable, whenever possible. Graphical methods of expressing problems have been very instructive. We have also found it useful, and occasionally invaluable, to cross-check results obtained using different methods, such as analytical integration and ray-tracing.

  12. Chopper:Efficient Algorithm for Tree Mining

    Institute of Scientific and Technical Information of China (English)

    Chen Wang; Ming-Sheng Hong; Wei Wang; Bai-Le Shi

    2004-01-01

    With the development of Internet, frequent pattern mining has been extended to more complex patterns like tree mining and graph mining. Such applications arise in complex domains like bioinformatics, web mining, etc. In this paper, we present a novel algorithm, named Chopper, to discover frequent subtrees from ordered labeled trees. An extensive performance study shows that the newly developed algorithm outperforms TreeMinerV, one of the fastest methods proposed previously, in mining large databases. At the end of this paper,the potential improvement of Chopper is mentioned.

  13. Development of a voltage scanner of chopper

    International Nuclear Information System (INIS)

    Development of voltage sweeper of chopper with CPNG are introduced. Voltage sweeper is one of important key parts of chopper. Two years working prove that it is stable and reliable. Its main technology performance save: sine wave frequency: 750 kHz +- 20 Hz; total distortion: 65 Db; output voltage (V-V): 0-≥4000 V; the error≤+-25 V; output power: >7 W; voltage supply: 220V AC +-10%, 50 +- 1 Hz; total power supply: <100W; Work temperature range: 0 - 40 degree; Stability in long time ≤1%

  14. Optical chopper for the HIRDLS instrument

    Science.gov (United States)

    Opyd, Walter G.; Loewenthal, Stuart

    2003-12-01

    Requirements, performance and life-test results are presented for the optical chopper installed in the High-Resolution Dynamics Limb Sounder (HIRDLS) to be flown on the AURA mission of the NASA Earth Observing System (EOS). Optical chopping is essential in order to achieve the required sensitivity and accuracy in measurement of infrared emission from various chemical species in the earth's atmosphere. Chopping of the optical input as far forward in the telescope as practical minimizes calibration errors arising from variations in emission from warm optics and due to electronic drifts in the infrared detecting system. At 500 Hz, a reflective chopper blade is used to alternate the instrument view between the atmospheric limb and cold space. The HIRDLS chopper is a six-toothed, mirrored wheel driven by a brushless DC motor. Chopper design was driven by requirements of 1) continuous operation at 5000 RPM for 50,000 hours in space vacuum, 2) chopping amplitude stability of one part in 100,000, 3) lubricant loss control for both bearing reliability and prevention of optics contamination, 4) compact size to fit in the folded telescope, and 5) survival in the launch environment.

  15. Negative coupled inductors for polyphase choppers

    Science.gov (United States)

    Jamieson, Robert S. (Inventor)

    1984-01-01

    A technique for negatively coupling the outputs of polyphase choppers is disclosed, wherein the output inductance of each phase is divided into two windings, and each winding is negatively coupled to a corresponding winding of a neighboring phase. In a preferred embodiment for a three-phase chopper circuit, the output inductance of phase A is divided into windings 100 and 102, the output inductance of phase B is divided into windings 110 and 112, and the output inductance of phase C is divided into windings 120 and 122. Pairs of windings 100 and 110, 112 and 120, and 102 and 122 are respectively disposed in transformers arranged for negatively coupling the windings of each pair.

  16. Modeling and control of parallel multicell chopper using Petri nets

    OpenAIRE

    Amghar, Bilal; Darcherif, Moumen; Barbot, Jean-Pierre; Gauthier, Patrick

    2012-01-01

    International audience In this paper a new class of converters power will be studied (Parallel Multicell Chopper). The topology of these chopper is based on a combination of n cells switching interconnected via independent inductors. This type of choppers is a new DC/DC static power converter which has an output current equals to n times the source current where n is the number of cells . After recalling the dynamical equations of the converter, its hybrid dynamical behavior and properties...

  17. Experimental results of an ExB chopper system

    Energy Technology Data Exchange (ETDEWEB)

    Wiesner, Christoph; Dinter, Hannes; Droba, Martin; Meusel, Oliver; Noll, Daniel; Nowottnick, Tobias; Payir, Onur; Ratzinger, Ulrich; Schneider, Philipp [IAP, Goethe-Universitaet Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany)

    2014-07-01

    A new chopper system for low-energy high-perveance beams and high repetition rates was developed for the Low Energy Beam Transport (LEBT) section of the accelerator-driven neutron source FRANZ. The chopper combines a static magnetic deflection field with a pulsed electric compensation field in a Wien filter-type E x B configuration. The total system length is 80 cm. Successful beam operation of the chopper has started. Helium beams with 14 keV energy were chopped with the required repetition rate of 257 kHz. The beam pulses have rise times of 120 ns and Full Width at Half Maximum (FWHM) of 240 ns to 370 ns. When the future high-current proton source of the FRANZ facility is available, the chopper will operate with a 50 mA, 120 keV beam. The design of the chopper and results of beam experiments are presented.

  18. Linac4 chopper line commissioning strategy

    CERN Document Server

    Bellodi, G; Lombardi, A M; Posocco, P A; Sargsyan, E

    2010-01-01

    The report outlines the strategy for beam-based commissioning of the Linac4 3 MeV chopper line as currently scheduled to start in the second half of 2011 in the Test Stand Area. A dedicated temporary diagnostics test bench will complement the measurement devices foreseen for permanent installation in the chopper line. A commissioning procedure is set out as a series of consecutive phases, each one supposed to meet a well- defined milestone in the path to fully characterise the beam-line. Specific set-ups for each stage are defined in terms of beam characteristics, machine settings and diagnostics used. Operational guidelines are given and expected results at the relative points of measurements are shown for simulated scenarios (on the basis of multi-particle tracking studies carried out with the codes PATH and TRACEWin). These are then interpreted in the light of the resolution limits of the available diagnostics instruments to assess the precision reach on individual measurements and the feasibility of techn...

  19. Analysis of Input and Output Ripples of PWM AC Choppers

    Directory of Open Access Journals (Sweden)

    Pekik Argo Dahono

    2008-11-01

    Full Text Available This paper presents an analysis of input and output ripples of PWM AC choppers. Expressions of input and output current and voltage ripples of single-phase PWM AC choppers are first derived. The derived expressions are then extended to three-phase PWM AC choppers. As input current and output voltage ripples specification alone cannot be used to determine the unique values of inductance and capacitance of the LC filters, an additional criterion based on the minimum reactive power is proposed. Experimental results are included in this paper to show the validity of the proposed analysis method.

  20. A new high-speed X-ray beam chopper

    International Nuclear Information System (INIS)

    A new high-speed x-ray beam chopper using laser scanner technology has been developed and tested on the SRI-CAT sector 1 beamline at the Advanced Photon Source (APS) storage ring (1). As illustrated in figure 1, it is compact in size and has two sets of transmission windows: BK-7 glass for visible light transmission and 0.23-mm-thick Be for the transmission of x-rays. The rotor is made of aluminum and has a diameter of 50.8 mm. A 0.5-mm-wide and 2.29-mm-tall slit is cut through the center of the rotor. The circumference of the rotor has a coating of 1-mm-thick Ni, which gives an attenuation of 108 at 30 keV. Turning at nearly 80000 RPM, this beam chopper has an opening time window of 2450 ns, corresponding to 67% of the revolution time of the APS storage ring. The primary feature in selecting laser scanner technology to develop into an x-ray beam chopper was the high level of rotational speed control of the rotor that makes up the beam chopper element (2). By using an optical feedback circuit to sample the rotational speed four times each revolution, the jitter in the position of the transmission open time window is only 3 ns at the 3 standard deviation level. The APS storage ring orbital frequency, supplied by the control room, is divided down to provide the appropriate drive frequency for the beam chopper motor controller. By this means, both the storage ring and the beam chopper are operating off the same master clock. After a turn-on time of about 15 to 20 seconds, the rotational precision of the motor results in immediate phase locking to the temporal structure of the APS storage ring. By inserting a Stanford delay generator between the frequency divider and the beam chopper motor controller, the phase between the storage ring temporal structure and the beam chopper rotation can be adjusted to position the transmission time window of the beam chopper on any desired part of the storage ring fill pattern. If an asymmetric fill pattern is used in the APS storage

  1. Study on Rotor IGBT Chopper Control for Induction Motor Drive

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Rotor chopper control is a simple and effective drive method for induction motor. This paper presents a novel IGBT chopper topology,which can both adjust rotor resistance and protect IGBT efficiently. Investigation on the quasi-transient state of the rotor rectifying circuit is made, and a nonlinear mapping between the equivalent resistance and the duty cycle is deduced. Furthermore, the method for determining the magnitude of the external resistor is introduced.

  2. Neural network based PWM AC chopper fed induction motor drive

    Directory of Open Access Journals (Sweden)

    Venkatesan Jamuna

    2009-01-01

    Full Text Available In this paper, a new Simulink model for a neural network controlled PWM AC chopper fed single phase induction motor is proposed. Closed loop speed control is achieved using a neural network controller. To maintain a constant fluid flow with a variation in pressure head, drives like fan and pump are operated with closed loop speed control. The need to improve the quality and reliability of the drive circuit has increased because of the growing demand for improving the performance of motor drives. With the increased availability of MOSFET's and IGBT's, PWM converters can be used efficiently in low and medium power applications. From the simulation studies, it is seen that the PWM AC chopper has a better harmonic spectrum and lesser copper loss than the Phase controlled AC chopper. It is observed that the drive system with the proposed model produces better dynamic performance, reduced overshoot and fast transient response. .

  3. A prototype chopper for synchrotron time-resolved crystallographic measurements

    International Nuclear Information System (INIS)

    A mechanical x-ray chopper has been designed to perform microsecond time-resolved crystallographic studies at the DIAMOND synchrotron I19 beamline. It consists of two asymmetric absorbers rotating synchronously at frequencies from 0 to 50 Hz in the same direction around a rotation axis that is parallel to the x-ray beam. The duration of the x-ray pulses produced by the chopper is determined by the relative phase between the two blades, which can be adjusted. The chopper system presented in this paper offers a time resolution suitable for conducting in situ experiments that afford the crystal structure of materials while in their transient (>10 μs) photoactivated excited states.

  4. First results from PHAROS, the new chopper spectrometer at LANSCE

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, B.J.; Sandoval, J.P.; Lysaght, P.; Nutter, M.; Robinson, R.A.

    1993-06-01

    In this article we present the first experimental measurements obtained on PHAROS during the 1992 run cycle at LANSCE. These are data on the phasing of the choppers relative to the accelerator system along with the consequent neutronic resolution, data on the real-space position resolution of the main detectors, a white-beam nickel powder calibration, and our first inelastic scattering measurement made on TiH{sub 2} with an incident energy of 300 MeV. The characteristic features of the new chopper spectrometer PHAROS, designed for low-angle inelastic neutron scattering and neutron Brillouin scattering, are described elsewhere in these proceedings.

  5. First results from PHAROS, the new chopper spectrometer at LANSCE

    International Nuclear Information System (INIS)

    In this article we present the first experimental measurements obtained on PHAROS during the 1992 run cycle at LANSCE. These are data on the phasing of the choppers relative to the accelerator system along with the consequent neutronic resolution, data on the real-space position resolution of the main detectors, a white-beam nickel powder calibration, and our first inelastic scattering measurement made on TiH2 with an incident energy of 300 MeV. The characteristic features of the new chopper spectrometer PHAROS, designed for low-angle inelastic neutron scattering and neutron Brillouin scattering, are described elsewhere in these proceedings

  6. Introduction to modern chopper spectrometers for pulsed neutron sources

    International Nuclear Information System (INIS)

    Introduction to the latest modern chopper spectrometers for pulsed neutron sources is shown. After coming up of recent high-performance pulsed neutron sources such as J-PARC, SNS and 2nd target station of ISIS, much progress have been achieved in technology regarding to chopper spectrometers in both hardware and software. A multi-Ei measurement based on repetition rate multiplication technique alters strategy of the measurements. Source pulse shaping provides opportunity precise measurements with high intensity. Current data analysis software enables us to access to the four dimensional space in energy and momentum transfers. (author)

  7. Design of an SFQ Microwave Chopper for Controlling Quantum Bits

    OpenAIRE

    Matsuda, G; Yamanashi, Y; Yoshikawa, N.

    2007-01-01

    A microwave chopper using single-flux-quantum (SFQ) circuits is proposed for the control of quantum bits (qubits). The proposed microwave chopper is composed of a DC/SFQ converter, an SFQ switch and a band-pass filter (BPF). In operation, an externally applied microwave is input to a DC/SFQ converter to generate an SFQ pulse train, which is chopped at high speed by the SFQ switch. The SFQ pulse train is then filtered by the BPYA I to remove higher harmonics. The transient response, the amplit...

  8. Quantitative structure refinement from the ARCS chopper spectrometer

    Science.gov (United States)

    Božin, E. S.; Juhás, P.; Zhou, W.; Stone, M. B.; Abernathy, D. L.; Huq, A.; Billinge, S. J. L.

    2010-11-01

    The new wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source at Oak Ridge National Laboratory has been successfully used in white-beam mode, with no Fermi chopper, to obtain neutron powder diffraction based atomic pair distribution functions (PDFs). Obtained PDF patterns of Si, Ni, and Al2O3 were refined using the PDFfit method and the results compared to data collected at the NPDF diffractometer at Los Alamos National Laboratory. High quality resulting fits are presented, demonstrating that reliable powder diffraction data can be obtained from ARCS when operated in this configuration.

  9. Fiber optic yield monitor for a sugarcane chopper harvester

    Science.gov (United States)

    A fiber optic yield monitoring system was developed for a sugarcane chopper harvester that utilizes a duty-cycle type approach with three fiber optic sensors mounted in the elevator floor to estimate cane yield. Field testing of the monitor demonstrated that there was a linear relationship between t...

  10. Thermal chopper spectrometer for the European spallation source

    DEFF Research Database (Denmark)

    Klenø, Kaspar Hewitt; Lefmann, Kim

    2011-01-01

    One of the instruments being considered for the ESS is a thermal chopper spectrometer, intended for the study of lattice vibrations and magnetic excitations. However, as the ESS will be a long pulsed source, we propose a very long instrument (180–300 m). We here present a guide system that can...

  11. A CMOS low-noise instrumentation amplifier using chopper modulation

    DEFF Research Database (Denmark)

    Nielsen, Jannik Hammel; Bruun, Erik

    2005-01-01

    This paper describes a low-power, low-noise chopper stabilized CMOS instrumentation amplifier for biomedical applications. Low thermal noise is achieved by employing MOSTs biased in the weak/moderate inversion region, whereas chopper stabilization is utilized to shift 1/f-noise out of the signal...... band hereby ensuring overall low noise performance. The resulting equivalent input referred noise is approximately 7 nV/rootHz for a chopping frequency of 20 kHz. The amplifier operates from a modest supply voltage of 1.8 V, drawing 136 muA of current thus consuming 245 muW of power. The gain is 72.5 d...

  12. New chopper modulators using differential voltage current conveyor

    OpenAIRE

    Kumngern, M.

    2011-01-01

    This paper presents new chopper modulators which can enable to assign three modulators in one circuit. Full amplitude modulators as Cowan and Ring modulators are kinds of the amplitude modulators as well. The proposed circuit is implemented from the differential voltage current conveyor, four-MOS transistors switch and two-MOS transistors inverter. The advantage of this proposed circuit is high input and low output impedance and is able to be connected with any load without buffer and the num...

  13. Travelling wave chopper for the high current injector at IUAC

    International Nuclear Information System (INIS)

    IUAC is developing High Current Injector (HCI) accelerator as an alternative injector for the existing superconducting linear accelerator. The HCI project was envisaged to overcome the low current limitation of the Pelletron Accelerator and to provide varieties of ion species like nobel gases etc. which are not possible with existing Pelletron Accelerator. The LEBT (low energy beam transport) section of HCI consists of various beam dynamics components like GP Tubes, Diagnostic Box, Chopper and TWD, Multi Harmonic Buncher (MHB), Vacuum System, Magnetic Quadruple, and Fast Faraday Cup etc. A Chopper and Travelling Wave Deflector (TWD) is required to provide the chopped beam with various repetition rate to IUAC experimental facilities ego NAND, HYRA, HlRA, INGA etc. The proposed MHB in the LEBT section of HCI, is having 60 ns linear portion in its saw tooth wave form. The requirement of the repetition rate for the experimental facilities are 250ns, 500ns, 1μs, 2μs, 4μs and 8μs. It was decided that output of chopper must have 60 ns pulse length with maximum current and TWD must provide the various repetition rate as mentioned above. In this paper we will present the details of the design and fabrication of prototype

  14. Feasibility demonstration of a new Fermi chopper with supermirror-coated slit package

    International Nuclear Information System (INIS)

    The efficiency of inelastic neutron scattering measurements using a chopper spectrometer can be markedly improved by utilizing multiple incident energies (Multi-Ei method). However, in conventional chopper systems, optimization of the experimental condition for all incident energies is absolutely impossible. We developed a new Fermi chopper with a supermirror-coated slit package in order to overcome the problem and experimentally demonstrated that the full optimization of the experimental condition for multiple incident energies is nearly achieved

  15. Chopper mode analysis of beam distribution based on time in HIRFL

    International Nuclear Information System (INIS)

    Chopper is an important equipment in beam distribution system based on time of heavy ion research facility in Lanzhou (HIRFL). This paper introduces its mode analysis system's architecture and hardware composition, analyzes corresponding software requirements, and designs the mode analysis program using multithreading technology. Firstly the program reads mode pulse data of chopper from data acquisition card by NI-DAQmx function, then uses the data for further analysis, and finally sends corresponding work mode control instruction to chopper controller through TCP/IP protocol. The designed program meets system requirements, realizing the function of chopper mode automatic conversion, and has passed the field test. (authors)

  16. Reflective Optical Chopper Used in NIST High-Power Laser Measurements

    Directory of Open Access Journals (Sweden)

    Cromer, Chris

    2008-11-01

    Full Text Available For the past ten years, NIST has used high-reflectivity, optical choppers as beamsplitters and attenuators when calibrating the absolute responsivity and response linearity of detectors used with high-power CW lasers. The chopper-based technique has several advantages over the use of wedge-shaped transparent materials (usually crystals often used as beam splitters in this type of measurement system. We describe the design, operation and calibration of these choppers. A comparison between choppers and transparent wedge beampslitters is also discussed.

  17. Text experiments of disk chopper with supermirror converging system

    International Nuclear Information System (INIS)

    We measured transportation property of neutron pulsed by disk chopper with three kinds of setting of supermirror guide at JRR-3M, JAERI. We confirmed a gain of supermirror converging system to narrow straight supermirror system. The gain is approximately same as the ratio of entrance width of converging guide to width of narrow straight guide. On the other hand, we did not get a gain of supermirror converging system to wide straight supermirror system which has a same width to entrance width of converging guide and we will plan more precisely experiment. (author)

  18. HELIOS: A high intensity chopper spectrometer at LANSCE

    Energy Technology Data Exchange (ETDEWEB)

    Mason, T.E. [Oak Ridge National Lab., TN (United States); Broholm, C. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Physics and Astronomy; Fultz, B. [California Inst. of Tech., Pasadena, CA (United States). Dept. of Materials Science] [and others

    1998-12-31

    A proposal to construct a high intensity chopper spectrometer at LANSCE as part of the SPSS upgrade project is discussed. HELIOS will be optimized for science requiring high sensitivity neutron spectroscopy. This includes studies of phonon density of states in small polycrystalline samples, magnetic excitations in quantum magnets and highly correlated electron systems, as well as parametric studies (as a function of pressure, temperature, or magnetic field) of S(Q,{omega}). By employing a compact design together with the use of supermirror guide in the incident flight path the neutron flux at HELIOS will be significantly higher than any other comparable instrument now operating.

  19. Development of fast beam-stop system using RF chopper

    International Nuclear Information System (INIS)

    To avoid heat damage and radioactivation by beam loss of the J-PARC accelerator, Machine Protection System (MPS) has been developed. Actually, high responsibility and high reliability have been achieved in J-PARC. Beam-stop method in addition to a way of RFQ OFF has been requested in order to avoid damage to the RFQ. Therefore, we have been developing a fast beam-stop system by using a RF chopper. The fast beam-stop system, including beam test, is described in this paper. (author)

  20. Tuning of MEBT-Chopper by using wire scanner monitor

    International Nuclear Information System (INIS)

    In J-PARC, a macro pulse with several hundred micro seconds is shaped into a pulse with medium bunch structure of about one MHz, by a RF chopper at MEBT section. The comb-like structured pulse is injected into the following DTL section. The remaining fraction of the beam in the bottom of the comb-like structure, is measured by a wire scanner monitor (with preamplifier) located in the downstream. The remaining fraction (compared to the nominal signal) is of the order of 0.1%. (author)

  1. HELIOS: A high intensity chopper spectrometer at LANSCE

    International Nuclear Information System (INIS)

    A proposal to construct a high intensity chopper spectrometer at LANSCE as part of the SPSS upgrade project is discussed. HELIOS will be optimized for science requiring high sensitivity neutron spectroscopy. This includes studies of phonon density of states in small polycrystalline samples, magnetic excitations in quantum magnets and highly correlated electron systems, as well as parametric studies (as a function of pressure, temperature, or magnetic field) of S(Q,ω). By employing a compact design together with the use of supermirror guide in the incident flight path the neutron flux at HELIOS will be significantly higher than any other comparable instrument now operating

  2. Ultra-high vacuum compatible optical chopper system for synchrotron x-ray scanning tunneling microscopy

    International Nuclear Information System (INIS)

    High-speed beam choppers are a crucial part of time-resolved x-ray studies as well as a necessary component to enable elemental contrast in synchrotron x-ray scanning tunneling microscopy (SX-STM). However, many chopper systems are not capable of operation in vacuum, which restricts their application to x-ray studies with high photon energies, where air absorption does not present a significant problem. To overcome this limitation, we present a fully ultra-high vacuum (UHV) compatible chopper system capable of operating at variable chopping frequencies up to 4 kHz. The lightweight aluminum chopper disk is coated with Ti and Au films to provide the required beam attenuation for soft and hard x-rays with photon energies up to about 12 keV. The chopper is used for lock-in detection of x-ray enhanced signals in SX-STM

  3. Ultra-high vacuum compatible optical chopper system for synchrotron x-ray scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hao, E-mail: hc000211@ohio.edu [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Nanoscale and Quantum Phenomena Institute, Physics & Astronomy Department, Ohio University, Athens, Ohio 45701 (United States); Cummings, Marvin; Shirato, Nozomi; Stripe, Benjamin; Preissner, Curt; Freeland, John W. [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Rosenmann, Daniel [Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Kersell, Heath; Hla, Saw-Wai [Nanoscale and Quantum Phenomena Institute, Physics & Astronomy Department, Ohio University, Athens, Ohio 45701 (United States); Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Rose, Volker, E-mail: vrose@anl.gov [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)

    2016-01-28

    High-speed beam choppers are a crucial part of time-resolved x-ray studies as well as a necessary component to enable elemental contrast in synchrotron x-ray scanning tunneling microscopy (SX-STM). However, many chopper systems are not capable of operation in vacuum, which restricts their application to x-ray studies with high photon energies, where air absorption does not present a significant problem. To overcome this limitation, we present a fully ultra-high vacuum (UHV) compatible chopper system capable of operating at variable chopping frequencies up to 4 kHz. The lightweight aluminum chopper disk is coated with Ti and Au films to provide the required beam attenuation for soft and hard x-rays with photon energies up to about 12 keV. The chopper is used for lock-in detection of x-ray enhanced signals in SX-STM.

  4. Design and placement considerations for propeller-type t-zero choppers

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, R.A.

    1998-12-31

    The author discusses factors to do with placement and running speeds of propeller-type t-zero choppers, as implemented at ISIS (on chopper spectrometers) and at LANSCE (on a reflectometer, chopper spectrometer and small-angle scattering instrument). In all cases, the purpose is to block the burst of high-energy neutrons that emanates from the source when the proton beam strikes the target, and still be fully open when the thermal neutrons of interest pass through the space occupied by the t-zero chopper. In general, roughly 30 cm of high-strength high-Ni alloy (like nimonic or inconel) is placed in the beam, and for background purposes, it is desirable to place the chopper as far upstream as possible.

  5. Status of CERN Chopper Driver and the Solid State Alternative

    CERN Document Server

    Paoluzzi, M

    2005-01-01

    The Superconducting H- Linac under study at CERN requires a high performance 3 MeV chopper. It has to establish the required beam time-structure by dumping part of the beam exiting the RFQ in 0.6 ms bursts of 1 ns bunches spaced by 2.84 ns and repeated at 50 Hz. For maximum flexibility, the system must be able to remove any number of consecutive bunches with a minimum of 3 and up to a few thousand. The amplifier driving the chopper structure has thus to provide 500 V on 50 omega, with rise and fall times below 2 ns and repetition rate as high as 45 MHz. To achieve the very wide frequency response required for this application a first proposal based on the idea of generating the low and high frequency part of the required spectrum with distinct amplifiers has been followed. In-depth studies and prototyping have proven the principle but also shown its fragilities. Distortions, saturation effects in the ferrite or in the driving circuits, vacuum tube ageing, etc. are difficult to keep within the limits required ...

  6. A fast chopper for programmed population of the longitudinal phase space of the AGS booster

    International Nuclear Information System (INIS)

    This paper reports on a fast chopper which has been built, that can switch the beam injected into the AGS or AGS Booster on and off with rise and fall times in the order of 10 ns. The chopper will be used to control the initial population of longitudinal phase space in order to eliminate rf capture losses and achieve an optimal phase space density distribution. The chopper operates on the 35 keV H- beam between the ion source and the RFQ. The interaction between the electrostatic fields of the chipper and the space charge neutralizing ions in the beam has been seen to be a significant but manageable effect

  7. SMALL-SIGNAL ANALYZING OF SEPARATELY EXCITED DC MOTOR FED DC - DC CHOPPER

    OpenAIRE

    İSMAİL COŞKUN

    1999-01-01

    Choppers are widely used in order to get smooth speed characteristics of DC motors. If the load or input voltage is changed, a feedback control technique is used to get the constant speed. To design the proper feedback control, the transfer function of the chopper-motor combination should be kno\\vn. ln this study, the effort was given to obtain the general black diagram, inciurling the field current and aı1na ture current of chopper-fed DC motor. It can be seen from the black diagram that the...

  8. New chopper modulators using differential voltage current conveyor

    Directory of Open Access Journals (Sweden)

    M. Kumngern

    2011-06-01

    Full Text Available This paper presents new chopper modulators which can enable to assign three modulators in one circuit. Full amplitude modulators as Cowan and Ring modulators are kinds of the amplitude modulators as well. The proposed circuit is implemented from the differential voltage current conveyor, four-MOS transistors switch and two-MOS transistors inverter. The advantage of this proposed circuit is high input and low output impedance and is able to be connected with any load without buffer and the number of transistors is quite less which is suitable for integrated circuits. The technique is to control the switch by using the square pulse which is obtained from a direct signal generator. All simulation results are based on the PSPICE program simulator which confirms the performance of the proposed circuit and technique.

  9. A fast chopper of TOF-LEIS experiments

    International Nuclear Information System (INIS)

    Full text: Time-Of-Flight Low Energy Ion Scattering (TOF-LEIS) is a very powerful technique for surface analysis. Recently, a new TOF-LEIS experiment (ACOLISSA) has been set to operation and measurements have been performed at the institute of experimental physics, department of atomic physics and surface science. Within this contribution we present a new, fast electrostatic chopper which has been designed and constructed for this experiment. As examples total intensity TOF-LEIS spectra from He-ions and Cu in the keV energy range are presented with a minimal time resolution of about 5-10 ns corresponding to a depth resolution in the total intensity TOF-LEIS spectra of less than 1 monolayer. (author)

  10. Analysis of Variable Speed PFC Chopper Fed BLDC Motor Drive

    Directory of Open Access Journals (Sweden)

    A Jeya Selvan Renius

    2015-02-01

    Full Text Available This paper provides the detailed analysis of the DC-DC chopper fed Brushless DC motor drive used for low-power applications. The various methods used to improve the power quality at the ac mains with lesser number of components are discussed. The most effective method of power quality improvement is also simulated using MATLAB Simulink. Improved method of speed control by controlling the dc link voltage of Voltage Source Inverter is also discussed with reduced switching losses. The continuous and discontinuous modes of operation of the converters are also discussed based on the improvement in power quality. The performance of the most effective solution is simulated in MATLAB Simulink environment and the obtained results are presented.

  11. Design, construction, and initial operation of the SNS MEBT chopper system

    International Nuclear Information System (INIS)

    The chopper system for the Spallation Neutron Source (SNS) provides a gap in the beans for clean extraction from the accumulator ring. It consists of a pre-chopper in the low-energy bean transport (LEBT) and a faster chopper in the medium-energy beam transport (MEBT). We report here on the final design, fabrication, installation, and first beans tests of the MEBT chopper. The traveling-wave deflector is a meander-line design that matches the propagation of the deflecting pulse with the velocity of the beam at 2.5 MeV, after the radio-frequency quadrupole (RFQ) acceleration stage. The pulses uses a series of fast-risetime MOSFET transistors to generate the deflecting pulses of +- 2.5 kV with rise and fall times of 10 ns. We describe the design and fabrication of the meander line and pulsers and report on the first operation during initial beam tests at SNS.

  12. The resolution function for a time-of-flight diffractometer with curved slits chopper

    Energy Technology Data Exchange (ETDEWEB)

    Ionita, I. [Institute for Nuclear Research, Pitesti (Romania); Stoica, A.D. [Institute for Physics and Technology for Materials (Romania)

    1996-07-01

    The procedure for computing the resolution function for a time-of-flight diffractometer with curved slits chopper is presented. Some focusing conditions concerning the sample and detector inclination angle are also given. (orig.)

  13. A new chopper spectrometer for neutron Brillouin scattering and low-angle neutron inelastic scattering: PHAROS (Phase 1)

    International Nuclear Information System (INIS)

    Phase I of PHAROS, the new chopper spectrometer at LANSCE, is described in detail. The main components are a water moderator, a 60-Hz double-bladed T-zero chopper, a 600Hz magnetic-bearing Fermi chopper, a 6m-long vacuum vessel with thin aluminium-alloy vacuum window and a 1.2m2 array of linear position-sensitive detectors

  14. The Effect of the Chopper on Granules from Wet High-Shear Granulation Using a PMA-1 Granulator

    OpenAIRE

    Briens, Lauren; Logan, Ryan

    2011-01-01

    Chopper presence and then chopper speed was varied during wet high shear granulation of a placebo formulation using a PMA-1 granulator while also varying the impeller speed. The granules were extensively analyzed for differences due to the chopper. The effect of the chopper on the granules varied with impeller speed from no effect at a low impeller speed of 300 rpm to flow interruptions at an impeller speed of 700 rpm to minimal impact at very high impeller speeds as caking at the bowl perime...

  15. Java-based software for chopper-spectrometer data reduction

    International Nuclear Information System (INIS)

    We introduce a software application for analyzing time-of-flight data obtained from a chopper spectrometer. This Chop Analysis Package (CAP) is written in Java to take advantage of its platform independence and Internet accessibility. CAP is a component within the architecture of the Integrated Spectral Analysis Workbench (ISAW) being developed at Argonne. Multiple large data sets, each containing ∼1000 spectra, can be examined for removal of noise and contamination. Appropriate sample, background and calibration runs are combined and normalized. Afterward, data from detector groups are binned and converted into various scattering functions in momentum- and energy-transfer (|Q|, E) space. The resulting datasets can be analyzed further by users with additional methods. By virtue of the object-oriented programming (OOP) methods and graphic user interface (GUI) of ISAW, immediate steps of the evaluation are easily displayed in interactive viewers as images or line plots. Repetitive procedures can be executed through command-line scripts. The results can be saved as formatted tables in text files or pasted into other applications. (author)

  16. SMALL-SIGNAL ANALYZING OF SEPARATELY EXCITED DC MOTOR FED DC - DC CHOPPER

    OpenAIRE

    İsmail COŞKUN

    1999-01-01

    Choppers are widely used in order to get smooth speed characteristics of DC motors. If the  load or input voltage is changed, a feedback control technique is used to get the constant speed. To design the proper feedback control, the transfer function of the chopper-motor combination should be kno\\vn. ln this study, the effort was given to obtain the general black diagram, inciurling the field current and aı1na ture current of chopper-fed DC motor. It can be seen from the black diagram that th...

  17. Hard disk drive based microsecond x-ray chopper for characterization of ionization chambers and photodiodes

    International Nuclear Information System (INIS)

    A fast X-ray chopper capable of producing ms long X-ray pulses with a typical rise time of few μs was realized. It is ideally suited to investigate the temporal response of X-ray detectors with response times of the order of μs to ms, in particular, any kind of ionization chambers and large area photo diodes. The drive mechanism consists of a brushless DC motor and driver electronics from a common hard disk drive, keeping the cost at an absolute minimum. Due to its simple construction and small dimensions, this chopper operates at home lab based X-ray tubes and synchrotron radiation sources as well. The dynamics of the most important detectors used in time resolved X-ray absorption spectroscopy, namely, ionization chambers and Passivated Implanted Planar Silicon photodiodes, were investigated in detail. The results emphasize the applicability of this X-ray chopper

  18. Risk Assessment of the Chopper Dipole Kicker Magnets for the MedAustron Facility

    CERN Document Server

    Kramer, T; Barnes, M J; Benedikt, M; Fowler, T

    2011-01-01

    The MedAustron facility, to be built in Wiener Neustadt (Austria), will provide protons and ions for both cancer therapy and research [1]. Different types of kicker magnets will be used in the accelerator complex, including fast beam chopper dipoles: these allow the beam to be switched on and off for routine operational reasons or in case of emergency. Main requirements for the beam chopper system are safety and reliability. A criticality analysis, to chart the probability of failure modes against the severity of their consequences of the fault, has been carried out for the chopper dipole system. This "Failure Mode, Effects, and Criticality Analysis" (FMECA), has been used to highlight failure modes with relatively high probability and severity of consequences: conservative ratings of critical components and appropriate redundancy, together with measurements and interlocks, have been used to reduce the probability and criticality of faults. This paper gives an overview of the Risk Assessment approach and pres...

  19. Hard disk drive based microsecond x-ray chopper for characterization of ionization chambers and photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    Müller, O., E-mail: o.mueller@uni-wuppertal.de; Lützenkirchen-Hecht, D.; Frahm, R. [Bergische Universität Wuppertal, Gaußstraße 20, Wuppertal 42119 (Germany)

    2015-03-15

    A fast X-ray chopper capable of producing ms long X-ray pulses with a typical rise time of few μs was realized. It is ideally suited to investigate the temporal response of X-ray detectors with response times of the order of μs to ms, in particular, any kind of ionization chambers and large area photo diodes. The drive mechanism consists of a brushless DC motor and driver electronics from a common hard disk drive, keeping the cost at an absolute minimum. Due to its simple construction and small dimensions, this chopper operates at home lab based X-ray tubes and synchrotron radiation sources as well. The dynamics of the most important detectors used in time resolved X-ray absorption spectroscopy, namely, ionization chambers and Passivated Implanted Planar Silicon photodiodes, were investigated in detail. The results emphasize the applicability of this X-ray chopper.

  20. Hard disk drive based microsecond x-ray chopper for characterization of ionization chambers and photodiodes

    Science.gov (United States)

    Müller, O.; Lützenkirchen-Hecht, D.; Frahm, R.

    2015-03-01

    A fast X-ray chopper capable of producing ms long X-ray pulses with a typical rise time of few μs was realized. It is ideally suited to investigate the temporal response of X-ray detectors with response times of the order of μs to ms, in particular, any kind of ionization chambers and large area photo diodes. The drive mechanism consists of a brushless DC motor and driver electronics from a common hard disk drive, keeping the cost at an absolute minimum. Due to its simple construction and small dimensions, this chopper operates at home lab based X-ray tubes and synchrotron radiation sources as well. The dynamics of the most important detectors used in time resolved X-ray absorption spectroscopy, namely, ionization chambers and Passivated Implanted Planar Silicon photodiodes, were investigated in detail. The results emphasize the applicability of this X-ray chopper.

  1. Buck-Boost Control of Four Quadrant Chopper using Symmetrical Impedance Network for Adjustable Speed Drive

    OpenAIRE

    Saswati Swapna Dash; Byamakesh Nayak

    2015-01-01

    This paper proposes buck-boost capabilities of four quadrant chopper for wide range speed control of DC motor drives using symmetrical impedance network called Z-source network. By controlling the shoot through duty ratio from 0 to 0.5 and non-shoot through techniques, the Z-source four quadrant choppers can produce any desired DC voltage across the DC motor. The switching patterns for both buck and boost operations are presented to achieve four modes of operation of DC motor. As a result, th...

  2. Development of TMS320F2810 DSP Based Bidirectional buck-boost Chopper

    OpenAIRE

    Mr. K.S. Chakradhar*1,; M.Ayesha siddiqa2; T.Vandhana3

    2014-01-01

    A DC - DC converter is an electronic circuit which converts a source of direct current (DC) from one voltage level to another. It is a class of power converter. One common application of DC - DC converters is DC motor control. The Buck - Boost Chopper is a type of DC - DC converter. They are static devices which are used to obtain variable DC voltage from the source of constant DC voltage. Besides the saving in power, Buck-Boost choppers offer greater efficiency, faster respon...

  3. Feasibility of a fast beam chopper using laser stripping of H- ions for the JHP

    International Nuclear Information System (INIS)

    The feasibility of a fast beam chopper of the photodetachment neutralizer type by means of a pulsed Nd laser was studied in order to realize a decrease in the beam losses after injection into a circular accelerator for the JHP (Japanese Hadron Project). A 54-kW peak-power laser of 400 μs in length and a fast external amplitude modulator are required in order to produce 130-ns H0 pulses from H- pulses in the beam line between the ion source and the RFQ. Several possible installation points for the chopper are discussed. (author)

  4. Chopper spectrometer (2). Toward the expansion of observation area in inelastic neutron scattering

    International Nuclear Information System (INIS)

    The High Resolution Chopper Spectrometer (HRC) was installed and is being operated at BL12 of J-PARC/MLF to study condensed matter dynamics with high resolutions using relatively high energy neutrons. The Polarized Neutron Spectrometer (POLANO) is being constructed at BL23 to utilize polarized neutrons for dynamical studies. We hope that these two chopper spectrometers provide an opportunity to expand the observation area in inelastic neutron scattering experiments by using high energy neutrons and polarized neutrons with a good sample environment. (author)

  5. Design and characteristics of a high-precision chopper wheel motor driver

    International Nuclear Information System (INIS)

    The circuit diagram and design principles of a high-stability chopper wheel motor driver are presented. Experimental results show that this unit can be interfaced to molecular-beam machines to generate supersonic beams with extremely stable root-mean-square and peak velocities fluctuating on a day-to-day basis by less than 0.2%

  6. A design study of VOR: a versatile optimal resolution chopper spectrometer for the ESS

    International Nuclear Information System (INIS)

    VOR, the versatile optimal resolution chopper spectrometer, is designed to probe dynamic phenomena that are currently inaccessible for inelastic neutron scattering due to flux limitations. VOR is a short instrument by the standards of the European Spallation Source (ESS), 30.2 m moderator to sample, and provides instantaneous access to a broad dynamic range, 1 - 120 meV within each ESS period. The short instrument length combined with the long ESS pulse width enables a quadratic flux increase, even at longer wavelengths, by relaxing energy resolution from ΔE/E = 1% up to ΔE/E = 7%. This is impossible both on a long chopper spectrometer at the ESS and with instruments at short pulsed sources. In comparison to current day chopper spectrometers, VOR can offer an order of magnitude improvement in flux for equivalent energy resolutions, ΔE/E = 1 - 3%. Further relaxing the energy resolution enables VOR to gain an extra order of magnitude in flux. In addition, VOR has been optimised for repetition rate multiplication (RRM) and is therefore able to measure, in a single ESS period, 6 - 14 incident wavelengths, across a wavelength band of 9 Angstroms with a novel chopper configuration that transmits all incident wavelengths with equivalent counting statistics. The characteristics of VOR make it a unique instrument with capabilities to access small, limited-lifetime samples and transient phenomena with inelastic neutron scattering. (authors)

  7. A design study of VOR: A versatile optimal resolution chopper spectrometer for the ESS

    Science.gov (United States)

    Deen, P. P.; Vickery, A.; Andersen, K. H.; Hall-Wilton, R.

    2015-01-01

    VOR, the versatile optimal resolution chopper spectrometer, is designed to probe dynamic phenomena that are currently inaccessible for inelastic neutron scattering due to flux limitations. VOR is a short instrument by the standards of the European Spallation Source (ESS), 30.2 m moderator to sample, and provides instantaneous access to a broad dynamic range, 1-120 meV within each ESS period. The short instrument length combined with the long ESS pulse width enables a quadratic flux increase, even at longer wavelengths, by relaxing energy resolution from ΔE/E = 1% up to ΔE/E = 7%. This is impossible both on a long chopper spectrometer at the ESS and with instruments at short pulsed sources. In comparison to current day chopper spectrometers, VOR can offer an order of magnitude improvement in flux for equivalent energy resolutions, ΔE/E = 1-3%. Further relaxing the energy resolution enables VOR to gain an extra order of magnitude in flux. In addition, VOR has been optimised for repetition rate multiplication (RRM) and is therefore able to measure, in a single ESS period, 6-14 incident wavelengths, across a wavelength band of 9 Å with a novel chopper configuration that transmits all incident wavelengths with equivalent counting statistics. The characteristics of VOR make it a unique instrument with capabilities to access small, limited-lifetime samples and transient phenomena with inelastic neutron scattering.

  8. A design study of VOR: A versatile optimal resolution chopper spectrometer for the ESS

    Directory of Open Access Journals (Sweden)

    Deen P.P.

    2015-01-01

    Full Text Available VOR, the versatile optimal resolution chopper spectrometer, is designed to probe dynamic phenomena that are currently inaccessible for inelastic neutron scattering due to flux limitations. VOR is a short instrument by the standards of the European Spallation Source (ESS, 30.2 m moderator to sample, and provides instantaneous access to a broad dynamic range, 1–120 meV within each ESS period. The short instrument length combined with the long ESS pulse width enables a quadratic flux increase, even at longer wavelengths, by relaxing energy resolution from ΔE/E = 1% up to ΔE/E = 7%. This is impossible both on a long chopper spectrometer at the ESS and with instruments at short pulsed sources. In comparison to current day chopper spectrometers, VOR can offer an order of magnitude improvement in flux for equivalent energy resolutions, ΔE/E = 1–3%. Further relaxing the energy resolution enables VOR to gain an extra order of magnitude in flux. In addition, VOR has been optimised for repetition rate multiplication (RRM and is therefore able to measure, in a single ESS period, 6–14 incident wavelengths, across a wavelength band of 9 Å with a novel chopper configuration that transmits all incident wavelengths with equivalent counting statistics. The characteristics of VOR make it a unique instrument with capabilities to access small, limited-lifetime samples and transient phenomena with inelastic neutron scattering.

  9. Upgrade of power supply system for RF-chopper at J-PARC linac

    International Nuclear Information System (INIS)

    In the J-PARC Linac, the radio frequency deflector was adopted as a chopper to capture the particles into the RF-bucket in the next synchrotron. The chopper, consists of two deflectors, was installed on the medium-energy beam-transport line. In the operation of the RF-chopper, the fast rise/fall time of the pulse is a fundamental requirement to minimize the beam loss. In the previous system, the two series coupled chopper deflectors were driven by one solid-state amplifier due to the cost. However, the fell time indicated a poor result to effect the ringing into each cavity. Therefore, the additional solid-state amplifier and low level RF system were installed in the summer 2012 and the connection changed to the parallel system from the series using two amplifiers. The rise/fall time of the chopped beam was about 20 nsec in the beam current of 15 mA and the effect of the ringing was decreased. (author)

  10. A mechanical chopper with continuously adjustable duty cycle for a wide X-ray beam

    International Nuclear Information System (INIS)

    The prototype of a fast beam chopper for hard X-rays, with a continuously variable duty cycle from less than 10 to more than 90% has been successfully developed, built and tested. The apparatus consists in 12 planetary stainless-steel blades that are 100 mm wide and are mounted on two large discs. All blades are kept permanently parallel to each other, thanks to a gear system, which also allows changing their orientation. The two main parameters of the chopper (duty cycle and chopping frequency) are controlled independently and remotely. In the present design, the device allows chopping frequencies ranging from 0 to 300 Hz. The principle of operation, preliminary results of the instrument's performance and an example demonstrating the capacity of the system for image quality improvement and X-ray dose reduction at the specimen are presented

  11. Design of RF chopper system for improving beam quality in FEL injector with thermionic gun

    International Nuclear Information System (INIS)

    For a linac-based Free Electron Laser (FEL), good beam quality largely contributes to the success of the final radiation. An imperfection confronted with the HUST THz-FEL facility is the long beam tail that emerges in the electron gun and exists through the whole beam line. This paper proposes to deploy a chopper system after the electron gun to truncate the beam tails before they enter into the linac. Physical dimensions of the chopper cavity are discussed in detail and we have developed and derived new analytical expressions applying to all frequencies for the optimal design. Also, technical issues of the cavity are considered. Beam dynamic simulation is performed to examine the truncation effect and the results show that more than 78% of the beam tail can be removed effectively, while preserving the emittance and energy spread in acceptable level

  12. Buck-Boost Control of Four Quadrant Chopper using Symmetrical Impedance Network for Adjustable Speed Drive

    Directory of Open Access Journals (Sweden)

    Saswati Swapna Dash

    2015-02-01

    Full Text Available This paper proposes buck-boost capabilities of four quadrant chopper for wide range speed control of DC motor drives using symmetrical impedance network called Z-source network. By controlling the shoot through duty ratio from 0 to 0.5 and non-shoot through techniques, the Z-source four quadrant choppers can produce any desired DC voltage across the DC motor. The switching patterns for both buck and boost operations are presented to achieve four modes of operation of DC motor. As a result, the proposed model will have ride through capability during voltage sags, manage during voltage swells, used in any types of DC voltage sources such as fuel cell and solar cell and improve the reliability by reducing EMI noise. Analysis and simulation results are presented to demonstrate these new findings.

  13. Development of a fast traveling-wave beam chopper for the SNS project

    International Nuclear Information System (INIS)

    High current and stringent restrictions on beam losses, below 1 nA/m, in the designed linac for the Spallation Neutron Source (SNS) require clean and fast--with the rise time from 2% to 98% less than 2.5 ns--beam chopping in its front end, at the beam energy 2.5 MeV. The development of new traveling-wave deflecting current structures based on meander lines is discussed. Three-dimensional time-domain computer simulations with MAFIA are used to study transient effects in the chopper and to optimize current structure design. Two options for the fast pulsed voltage generator--based on FETs and vacuum tubes--are considered, and their advantages and shortcomings for the SNS chopper are discussed

  14. Development of a fast traveling-wave beam chopper for the National Spallation Neutron Source

    International Nuclear Information System (INIS)

    High current and severe restrictions on beam losses, below 1 nA/m, in the designed linac for the National Spallation Neutron Source (NSNS) require clean and fast--with the rise time from 2% to 98% less than 2.5 ns to accommodate a 402.5-MHz beam structure--beam chopping in its front end, at the beam energy 2.5 MeV. The R and D program includes both modification of the existing LANSCE coax-plate chopper to reduce parasitic coupling between adjacent plates, and development of new traveling-wave deflecting structures, in particular, based on a meander line. Using analytical methods and three-dimensional time-domain computer simulations the authors study transient effects in such structures to choose an optimal chopper design

  15. The Multiple Functions of T Stellate/Multipolar/Chopper Cells in the Ventral Cochlear Nucleus

    OpenAIRE

    Oertel, Donata; Wright, Samantha; Cao, Xiao-Jie; Ferragamo, Michael; Bal, Ramazan

    2010-01-01

    Acoustic information is brought to the brain by auditory nerve fibers, all of which terminate in the cochlear nuclei, and is passed up the auditory pathway through the principal cells of the cochlear nuclei. A population of neurons variously known as T stellate, type I multipolar, planar multipolar, or chopper cells forms one of the major ascending auditory pathways through the brain stem. T Stellate cells are sharply tuned; as a population they encode the spectrum of sounds. In these neurons...

  16. A design study of VOR: a versatile optimal resolution chopper spectrometer for the ESS

    CERN Document Server

    Deen, P P; Andersen, K H; Hall-Wilton, R

    2014-01-01

    VOR, the versatile optimal resolution chopper spectrometer, is designed to probe dynamic phenomena that are currently inaccessible for inelastic neutron scattering due to flux limitations. VOR is a short instrument by the standards of the European Spallation Source (ESS), 30.2 m moderator to sample, and provides instantaneous access to a broad dynamic range, 1 - 120 meV within each ESS period. The short instrument length combined with the long ESS pulse width enables a quadratic flux increase, even at longer wavelengths, by relaxing energy resolution from $\\Delta$E/E = 1% up to $\\Delta$E/E = 7%. This is impossible both on a long chopper spectrometer at the ESS and with instruments at short pulsed sources. In comparison to current day chopper spectrometers, VOR can offer an order of magnitude improvement in flux for equivalent energy resolutions, $\\Delta$E/E = 1-3%. Further relaxing the energy resolution enables VOR to gain an extra order of magnitude in flux. In addition, VOR has been optimised for repetition...

  17. Longitudinal Bunch Shape Monitor Using the Beam Chopper of the J-PARC

    CERN Document Server

    Naito, F

    2004-01-01

    We propose the longitudinal bunch shape monitor for the low energy part of the linac of the J-PARC. The monitor uses the beam chopper cavity installled in the MEBT line between thr RFQ and the DTL of the J-PARC as a kind of the bunch rotator. Consequentry the longitudinal bunch shape is measured along the horizontal direction. If we can measure the energy distribution of the bunch also, the longitudinal emittance of the beam is derived. In the paper, the basic idea of the monitor is discussed in detail.

  18. Rapid and economical data acquisition in ultrafast frequency-resolved spectroscopy using choppers and a microcontroller.

    Science.gov (United States)

    Guo, Liang; Monahan, Daniele M; Fleming, Graham

    2016-08-01

    Spectrometers and cameras are used in ultrafast spectroscopy to achieve high resolution in both time and frequency domains. Frequency-resolved signals from the camera pixels cannot be processed by common lock-in amplifiers, which have only a limited number of input channels. Here we demonstrate a rapid and economical method that achieves the function of a lock-in amplifier using mechanical choppers and a programmable microcontroller. We demonstrate the method's effectiveness by performing a frequency-resolved pump-probe measurement on the dye Nile Blue in solution. PMID:27505778

  19. SIMULATION AND IMPLEMENTATION OF PID-ANN CONTROLLER FOR CHOPPER FED EMBEDDED PMDC MOTOR

    OpenAIRE

    M. Madheswaran; Muruganandam, M.

    2012-01-01

    The closed loop control of PMDC drive with an inner current controller and an outer PID-ANN (Proportional Integral Derivative – Artificial Neural Network) based speed controller is designed and presented in this paper. Motor is fed by DC / DC buck converter (DC Chopper). The controller is used to change the duty cycle of the converter and thereby, the voltage fed to the PMDC motor to regulate the speed. The PID-ANN controller designed was evaluated by computer simulation and it was implemente...

  20. SIMULATION AND IMPLEMENTATION OF PID-ANN CONTROLLER FOR CHOPPER FED EMBEDDED PMDC MOTOR

    Directory of Open Access Journals (Sweden)

    M. Madheswaran

    2012-04-01

    Full Text Available The closed loop control of PMDC drive with an inner current controller and an outer PID-ANN (Proportional Integral Derivative – Artificial Neural Network based speed controller is designed and presented in this paper. Motor is fed by DC / DC buck converter (DC Chopper. The controller is used to change the duty cycle of the converter and thereby, the voltage fed to the PMDC motor to regulate the speed. The PID-ANN controller designed was evaluated by computer simulation and it was implemented using an 8051 based embedded system. This system will operate in forward motoring with variable speed.

  1. Contamination from the next higher incident energy in inelastic neutron scattering measurements with multiple incident energies on chopper spectrometers

    International Nuclear Information System (INIS)

    A highly efficient measurement technique utilizing multiple incident energies (Eis) simultaneously on a neutron chopper spectrometer has recently become popular in inelastic neutron scattering studies of condensed matter. However, the inelastic scattering spectrum of a target incident energy can be contaminated by the scattering process of other Eis. In this study, we quantitatively evaluated the extent to which the spectrum of a target Ei in this type of measurement can be contaminated by the scattering process of the next higher Ei. We estimated the relative intensity of the scattering from the next higher Ei for the neutron chopper spectrometers 4SEASONS and AMATERAS at the Japan Proton Accelerator Research Complex (J-PARC)

  2. ARCS A wide-Anglular Range Chopper Spectrometer at the SNS

    Energy Technology Data Exchange (ETDEWEB)

    Prof. Brent Fultz; Dr. Doug Abernathy

    2005-01-03

    The ARCS spectrometer project has been funded for 39 months. Procurements are now amain activity, although engineering effort remains, and installation has begun. Most of the subsystems are under control, and represent no risk to the project. These are: cryo-goniometer, detectors and electronics, Fermi chopper system, computing cluster, basic reduction software, T0 chopper and main neutron guide. The sample hutch and radiationshielding are still items of some risk. At the time of this writing, we are awaiting vendor proposals for the scattering chamber with integrated sample isolation system. This is thelargest uncertainty in the ARCS project today. The ARCS Chief Engineer, Kevin Shaw, joined the project in 2004. Project controlsservices are now performed by the SNS. A construction progress review was held in the August, 2004, before which the project was rebaselined, and after which the ProjectExecution Plan was updated. The ARCS project will be rebaselined in March 2005 after a vendor is selected for the scattering chamber with integrated isolation system. Projectcompletion by Sept. 2006 is possible but challenging.

  3. Considerations about Chopper Configuration at a time-of-flight SANS Instrument at a Spallation Source

    CERN Document Server

    Jaksch, Sebastian

    2016-01-01

    In any neutron scattering experiment the measurement of the position of the scattered neutrons and their respective velocities is necessary. In order to do so, a position sensitive detector as well as a way to determine the velocities is needed. Measuring the velocities can either be done by using only a single wavelength and therefore velocity or by creating pulses, where the start and end time of each pulse is known and registering the time of arrival at the detector, which is the case we want to consider here. This pulse shaping process in neutron scattering instruments is usually done by using a configuration of several choppers. This set of choppers is then used to define both the beginning and the end of the pulse. Additionally there is of course also a selection in phase space determining the final resolution that can be achieved by the instrument. Taking into account the special requirements of a specific instrument, here a small-angle neutron scattering instrument, creates an additional set of restri...

  4. Design of the HEBT chopper system for multiple-energy operation at HIMAC

    International Nuclear Information System (INIS)

    To realize fast scanning irradiation without the use of the energy absorbers, NIRS has developed multiple-energy operation with more than 200 energy steps. This operation can change the output energy of the synchrotron quickly; however, a part of the circulating particles spills uncontrollably during the procedure of the energy variation. The cause of that is emittance growth due to beam deceleration, and we must prevent the spilled particles from delivering to the patient. For the purpose, we have developed the beam chopping system of the High Energy Beam Transport (HEBT) section. The chopping system will interrupt the beam within 1 ms, and it will allow the quick change of the output energy within 50 ms. This paper describes the system design of the HEBT chopper and its control scheme in multiple-energy operation. (author)

  5. A step-down chopper-controlled slip energy recovery induction motor drive

    Energy Technology Data Exchange (ETDEWEB)

    Refoufi, L. (Inst. National D' Electricite et D' Electronique, Boumerdes (Algeria)); Pillay, P. (Univ. of New Orleans, LA (United States). Dept. of Electrical Engineering); Harris, M.R. (Univ. of Southampton, England (United Kingdom). Dept. of Electrical Engineering)

    1993-09-01

    The design of a chopper-controlled slip energy recovery drive (SERIMD), also known as a static Kramer drive, demands an exact knowledge of the steady state and dynamic performance of the system over the complete operating range. To accomplish this, a coupled circuit approach is necessary whereby the self and mutual coupling effects, voltage and current harmonics in the machine and voltage and current ripple at different points in the drive system are duly taken into account. Such a model should enable the accurate prediction of all instantaneous current values which leads to accurate prediction of electric torque and harmonics injected into the supply. This paper presents a model to accomplish the above. Mathematical predictions are verified with detailed experimental results.

  6. Research on a new active power filter topology based on chopper circuit

    CERN Document Server

    Xiaoling, Guo; Bo, Zhang; Jing, Zhang

    2015-01-01

    The active power filter (APF) is attracting more and more attention for its outstanding performance in current and voltage ripple compensation. As modern high-energy accelerators are demanding much more stringent current ripple guideline, the APF is introduced to the magnet power supply (MPS) in accelerator system. However, the conventional APF has a lot of shortages and drawbacks due to its traditional topology, such as complex structure, nonadjustable working voltage, requirement of power supply, and so on. This paper proposes a new topology of APF, which is working as two types of chopper circuits. This APF need not extra electricity, but to use the power of the MPS current ripple to realize ripple depressing. At the end of this paper, the experiment result proves its feasibility and effect.

  7. Bi-level Control and Chopper Control Methods for Improving the Dynamic Performance of Stepper Motor

    Directory of Open Access Journals (Sweden)

    Dr. Walid Emar, Eng. Ziad Sobih, Dr. Musbah Aqel & Dr. Mahmoud Awad

    2010-06-01

    Full Text Available This paper compares between chopper control method and bi-level controlmethod. Both methods are used for improving the dynamic performance ofvariable reluctance stepper motor (VRSM by modifying its time constant andthus, increasing its stepping rate. Therefore, the initial torque developed by themotor is high; the switching from one coil to the next is faster than normal andconsequently, the rotor moves as quickly as it should be. The circuitry discussedin this paper is connected directly to the motor windings and the motor powersupply, and this circuitry is controlled by a digital system that determines whenthe switches are turned on or off. Each class of drive circuit is illustrated withpractical examples, but these examples are not intended as an exhaustivecatalog of the commercially available control circuits, nor is the information givenhere intended to substitute for the information found on the manufacturer'scomponent data sheets for the parts mentioned.

  8. Design of a medium-energy beam-transport line with an anti-chopper for the JAERI/KEK project

    International Nuclear Information System (INIS)

    The medium-energy beam-transport line (MEBT) plays an important role in reducing beam loss in the JAERI/KEK project. A MEBT was designed two years ago, with good beam matching and lower beam loss. To further reduce beam loss during the transient time of the chopper to meet the new requirement from the DTL, a medium-energy beam-transport line with an anti-chopper has been designed. The 3.5 m long transport line consists of nine quadrupole magnets, three bunchers and four chopper/anti-chopper cavities. It accomplishes two tasks: matching the beam from the RFQ to the acceptance of the DTL and chopping the beam to produce gaps for injection into the rapid-cycling ring, which follows the linac. A RF Chopper and an anti-chopper have been adopted in the lattice, resulting in a clean chopping effect and no beam losses during the transient time. Details of the beam dynamics analysis are given

  9. Design of a medium-energy beam-transport line with an anti-chopper for the JAERI/KEK project

    International Nuclear Information System (INIS)

    The medium-energy beam-transport line (MEBT) plays an important role in reducing beam loss in the JAERI/KEK project. A MEBT was designed two years ago, with good beam matching and lower beam loss. To further reduce beam loss during the transient time of the chopper to meet the new requirement from the DTL, a medium-energy beam-transport line with an anti-chopper has been designed. The 3.5 m long transport line consists of nine quadrupole magnets, three bunchers and four chopper/anti-chopper cavities. It accomplishes two tasks: matching the beam from the RFQ to the acceptance of the DTL and chopping the beam to produce gaps for injection into the rapid-cycling ring, which follows the linac. An RF Chopper and an anti-chopper have been adopted in the lattice, resulting in a clean chopping effect, and no beam losses during the transient time. Details of the beam dynamics analysis are given. (author)

  10. Feasibility study into the use of mechanical choppers to alter the natural time structure of the APS

    International Nuclear Information System (INIS)

    The prospect of extending static x-ray measurements into the time domain is an exciting one indeed. The foundations for this extension have already been laid by some very innovative experiments performed at existing storage ring sources. The enormous enhancement in brilliance that the APS will afford over existing sources will, I believe, foster a tremendous growth in the area of time-resolved x-ray experimentation. The growing interest in this field is evidenced by both the number of participants and their enthusiasm at an APS Workshop on Time-Resolved Studies and Ultrafast Detectors held on January 25-26, 1988, at Argonne. We present here what may be a viable approach to the problem of altering the natural time structure of the APS with a minimal impact on other users. Our technique involves placing 19 of the 20 circulating bunches of positrons in (nearly) contiguous RF buckets and the remaining one bunch 180 degrees around the ring from this pack. The method we are advocating has several advantages over other schemes (such as wobblers) in that it is a passive technique: there are no external forces on the particle beam to destroy its stability, emittance, or lifetime properties, and it will not limit the total number of bunches in the beam to one (or a few) in order to get long dark periods between x-ray bursts. In this configuaration is should be possible to transmit the lone bunch and mechanically shutter the remaining 19 bunches with a chopper running at approximately 18,000 RPM. Although high, such revolution frequencies are achieved in neutron choppers which are generally much more massive than what is envisioned for an x-ray chopper

  11. A high-resolution disk chopper with two-stage rotors for neutron time-of-flight spectroscopy

    Science.gov (United States)

    Ono, Masayoshi

    1997-02-01

    Two-stage three-rotor disk chopper has been designed and constructed with the aim of bringing the resolution of crystal lattive strain ° d/ d = 10 -4-10 -5. The first two of them rotate at 150 rps in reverse directions from each other by a timing-belt system. This means that the actual rotation speed becomes 300 rps. The last rotor rotates as a tail-cutter for TOF measurements. The highest time resolution of the present Bragg scattering set-up is about 15 μs for 2 Å neutrons, realizing ° {d}/{d}<10 -4.

  12. A high-resolution disk chopper with two-stage rotors for neutron time-of-flight spectroscopy

    International Nuclear Information System (INIS)

    Two-stage three-rotor disk chopper has been designed and constructed with the aim of bringing the resolution of crystal lattice strain δd/d=10-4-10-5. The first two of them rotate at 150 rps in reverse directions from each other by a timing-belt system. This means that the actual rotation speed becomes 300 rps. The last rotor rotates as a tail-cutter for TOF measurements. The highest time resolution of the present Bragg scattering set-up is about 15 μs for 2 A neutrons, realizing δd/d-4. (orig.)

  13. Charging of capacitors with double switch. The principle of operation of auto-zero and chopper-stabilized DC amplifiers

    CERN Document Server

    Yordanov, Vasil G; Manolev, Stojan G; Mishonov, Todor M

    2015-01-01

    The principle of operation of auto-zero and chopper-stabilized DC amplifiers, which is realized in many contemporary operational amplifiers is illustrated by a simple experimental setup given at the Open Experimental Physics Olympiad 2014 - "The Day of the Capacitor", held in Sofia and Gevgelija. The Olympiad was organized by the Sofia Branch of the Union of Physicists in Bulgaria and the Regional Society of Physicists of Strumica, Macedonia. In addition to the solution of the secondary school task in the paper is given a detailed engineering description of the patent by Edwin Goldberg and Jules Lehmann, Stabilized direct current amplifier, U.S. Patent 2,684,999 (1949).

  14. A chopper current-feedback instrumentation amplifier with a 1 mHz 1/f noise corner and an AC-coupled ripple reduction loop

    OpenAIRE

    Wu, R; Makinwa, K.A.A.; Huijsing, J.H.

    2009-01-01

    This paper presents a chopper instrumentation amplifier for interfacing precision thermistor bridges. For high CMRR and DC gain, the amplifier employs a three-stage current-feedback topology with nested-Miller compensation. By chopping both the input and intermediate stages of the amplifier, a 1 mHz 1/f noise corner was achieved at an input-referred noise power spectral density (PSD) of 15 nV/¿Hz. To reduce chopper ripple, the amplifier employs a continuous-time AC-coupled ripple reduction l...

  15. Pulse width control at 106 pulses/sec and 15 kV for the KAON factory beam chopper

    International Nuclear Information System (INIS)

    A beam chopper is required in the transfer line between the 1 GeV/c TRIUMF cyclotron and the Accumulator ring of the pro-posed 30 GeV/c KAON Factory synchrotrons. The beam chopper must generate pulses with a magnitude of at l-t 9.5 kV, with rise and fall times of less than 38 ns, at a repetition rate of 106 pulses per second, and at a 100% duty cycle. Precise control of grid timing aid voltage is required at the driver tetrode to achieve deflector kick pulse widths of 48 ns and 92 ns while maintaining an interpulse and flattop ripple at less than ±10% of the deflector kick magnitude. Results of measurements are presented where all of the design criteria have been met, for the first time, over a wide range of pulse widths with sub-nanosecond precision. Rise and fall times of 18 ns to 31 ns have been achieved on 15 kV pulses at 0.93 x 106 pulses per second continuous operation. (author) 10 refs., 9 figs., 1 tab

  16. Design and operation of the wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source.

    Science.gov (United States)

    Abernathy, D L; Stone, M B; Loguillo, M J; Lucas, M S; Delaire, O; Tang, X; Lin, J Y Y; Fultz, B

    2012-01-01

    The wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source (SNS) is optimized to provide a high neutron flux at the sample position with a large solid angle of detector coverage. The instrument incorporates modern neutron instrumentation, such as an elliptically focused neutron guide, high speed magnetic bearing choppers, and a massive array of (3)He linear position sensitive detectors. Novel features of the spectrometer include the use of a large gate valve between the sample and detector vacuum chambers and the placement of the detectors within the vacuum, both of which provide a window-free final flight path to minimize background scattering while allowing rapid changing of the sample and sample environment equipment. ARCS views the SNS decoupled ambient temperature water moderator, using neutrons with incident energy typically in the range from 15 to 1500 meV. This range, coupled with the large detector coverage, allows a wide variety of studies of excitations in condensed matter, such as lattice dynamics and magnetism, in both powder and single-crystal samples. Comparisons of early results to both analytical and Monte Carlo simulation of the instrument performance demonstrate that the instrument is operating as expected and its neutronic performance is understood. ARCS is currently in the SNS user program and continues to improve its scientific productivity by incorporating new instrumentation to increase the range of science covered and improve its effectiveness in data collection. PMID:22299993

  17. Spectrum measurements in the ZENITH plutonium core 7 using a neutron chopper

    International Nuclear Information System (INIS)

    As part of the experimental programme on the first plutonium loading of ZENITH (Core 7) a series of measurements was carried out with the neutron chopper on a beam emerging from the core centre. The general experimental programme on the two ZENITH plutonium cores has been covered elsewhere. Core 7 had a carbon/Pu239 atomic ratio of 2666 and a steel/Pu239 ratio of 76.8, giving an absorption cross-section at 2200 m/sec. of 0.31 barns/carbon atom. The fuel was in the form of 'spikes' of 0.020 in. thick Pu/Al alloy sheathed in 0.020 in. aluminium, the isotopic composition of the plutonium being 97.4% Pu239, 2.55% Pu240 and 0.1% Pu241. The overall layout of the reactor core and reflector is shown in the vertical section through the reactor vessel and the plan view. The core consists of a vertical array of 235 cylindrical graphite sleeves of outer diameter 7.37 cm into each of which a cylindrical graphite box may be loaded. Sunning longitudinally inside the box are six parallel grooves which act as locations for the edges of either the Pu/Al spikes or graphite dummies of the same external dimensions. Each groove accommodates two spikes end-to-end, with a small graphite spacer between to avoid welding together of the spike sheaths when heated. Lateral spacers of graphite or stainless steel fill the five spaces between the six spikes or dummies. The total length of the plutonium-loaded core region is 140 cm, the ends of the element forming graphite reflectors of length 53 cm. In Core 7 each fuel element contained 10 Pu-Al spikes. The fuel elements are arranged in a triangular lattice of pitch 7.62 cm to form the reactor core, of diameter 1.23 m. A radial graphite reflector approximately 1 metre thick surrounds the core and is separated from it by an annular lampblack thermal barrier, contained within graphite tiles, which reduces heat transfer from the core. The reactor can be heated by circulation of nitrogen through a 250 kW heater below the core. The nitrogen flows

  18. Study of converging neutron guides for the cold neutron double-chopper spectrometer at J-PARC

    Energy Technology Data Exchange (ETDEWEB)

    Kajimoto, Ryoichi [Neutron Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan)]. E-mail: ryoichi.kajimoto@j-parc.jp; Nakamura, Mitsutaka [Neutron Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Osakabe, Toyotaka [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Sato, Taku J. [Neutron Science Laboratory, Institute for Solid State Physics, University of Tokyo, Tokai, Ibaraki 316-1106 (Japan); Nakajima, Kenji [Neutron Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Arai, Masatoshi [Neutron Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan)

    2006-11-15

    Performance of converging neutron guides was studied for the cold neutron double-chopper spectrometer proposed for the spallation neutron source at J-PARC. Intensity, spatial distribution, and angular distribution of a neutron beam at a sample are compared for linearly tapered and elliptic geometries by Monte Carlo simulation. For low-energy neutrons, the flux on the sample is much increased by an elliptic geometry whose focal points are on the moderator and on the sample in compensation for the angular resolution. To keep a substantial gain for a wide energy range, an elliptic guide with one of the focal points far behind the moderator is better. It also gives good spatial and angular intensity profiles at the sample.

  19. The Cold Neutron Chopper Spectrometer at the Spallation Neutron Source - A Review of the first 8 Years of Operation

    CERN Document Server

    Ehlers, Georg; Kolesnikov, Alexander I

    2016-01-01

    The first eight years of operation of the Cold Neutron Chopper Spectrometer (CNCS) at the Spallation Neutron Source in Oak Ridge is being reviewed. The instrument has been part of the facility user program since 2009, and more than 250 individual user experiments have been performed to date. CNCS is an extremely powerful and versatile instrument and offers leading edge performance in terms of beam intensity, energy resolution, and flexibility to trade one for another. Experiments are being routinely performed with the sample at extreme conditions: T~0.05K, p>=2GPa and B=8T can be achieved individually or in combination. In particular, CNCS is in a position to advance the state of the art with inelastic neutron scattering under pressure, and some of the recent accomplishments in this area will be presented in more detail.

  20. FieldChopper, a new tool for automatic model generation and virtual screening based on molecular fields.

    Science.gov (United States)

    Kalliokoski, Tuomo; Ronkko, Toni; Poso, Antti

    2008-06-01

    Algorithms were developed for ligand-based virtual screening of molecular databases. FieldChopper (FC) is based on the discretization of the electrostatic and van der Waals field into three classes. A model is built from a set of superimposed active molecules. The similarity of the compounds in the database to the model is then calculated using matrices that define scores for comparing field values of different categories. The method was validated using 12 publicly available data sets by comparing the method to the electrostatic similarity comparison program EON. The results suggest that FC is competitive with more complex descriptors and could be used as a molecular sieve in virtual screening experiments when multiple active ligands are known. PMID:18489083

  1. The wavelength frame multiplication chopper system for the ESS test beamline at the BER II reactor—A concept study of a fundamental ESS instrument principle

    International Nuclear Information System (INIS)

    Contributing to the design update phase of the European Spallation Source ESS–scheduled to start operation in 2019–a test beamline is under construction at the BER II research reactor at Helmholtz Zentrum Berlin (HZB). This beamline offers experimental test capabilities of instrument concepts viable for the ESS. The experiments envisaged at this dedicated beamline comprise testing of components as well as of novel experimental approaches and methods taking advantage of the long pulse characteristic of the ESS source. Therefore the test beamline will be equipped with a sophisticated chopper system that provides the specific time structure of the ESS and enables variable wavelength resolutions via wavelength frame multiplication (WFM), a fundamental instrument concept beneficial for a number of instruments at ESS. We describe the unique chopper system developed for these purposes, which allows constant wavelength resolution for a wide wavelength band. Furthermore we discuss the implications for the conceptual design for related instrumentation at the ESS

  2. A chopper system for shortening the duration of pulsed supersonic beams seeded with NO or Br2 down to 13 microseconds

    CERN Document Server

    Lam, Jessica; Softley, Tim

    2015-01-01

    A chopper wheel construct is used to shorten the duration of a molecular beam to 13 microseconds. Molecular beams seeded with NO or with Br2 and an initial pulse width of greater or equal to 200 microseconds were passed through a spinning chopper wheel, which was driven by a brushless DC in vacuo motor at a range of speeds, from 3,000 rpm to 80,000 rpm. The resulting duration of the molecular-beam pulses measured at the laser detection volume ranged from 80 microseconds to 13 microseconds, and was the same for both NO and Br2. The duration is consistent with a simple analytical model, and the minimum pulse width measured is limited by the spreading of the beam between the chopper and the detection point as a consequence of the longitudinal velocity distribution of the beam. The setup adopted here effectively eliminates buildup of background gas without the use of a differential pumping stage, and a clean narrow pulse is obtained with low rotational temperature.

  3. A chopper system for shortening the duration of pulsed supersonic beams seeded with NO or Br2 down to 13 μs

    International Nuclear Information System (INIS)

    A chopper wheel construct is used to shorten the duration of a molecular beam to 13 μs. Molecular beams seeded with NO or with Br2 and an initial pulse width of ≥200 μs were passed through a spinning chopper wheel, which was driven by a brushless DC in vacuo motor at a range of speeds, from 3000 rpm to 80 000 rpm. The resulting duration of the molecular-beam pulses measured at the laser detection volume ranged from 80 μs to 13 μs and was the same for both NO and Br2. The duration is consistent with a simple analytical model, and the minimum pulse width measured is limited by the spreading of the beam between the chopper and the detection point as a consequence of the longitudinal velocity distribution of the beam. The setup adopted here effectively eliminates buildup of background gas without the use of a differential pumping stage, and a clean narrow pulse is obtained with low rotational temperature

  4. A chopper system for shortening the duration of pulsed supersonic beams seeded with NO or Br{sub 2} down to 13 μs

    Energy Technology Data Exchange (ETDEWEB)

    Lam, Jessica; Rennick, Christopher J.; Softley, Timothy P. [Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Rd, Oxford OX1 3TA (United Kingdom)

    2015-05-15

    A chopper wheel construct is used to shorten the duration of a molecular beam to 13 μs. Molecular beams seeded with NO or with Br{sub 2} and an initial pulse width of ≥200 μs were passed through a spinning chopper wheel, which was driven by a brushless DC in vacuo motor at a range of speeds, from 3000 rpm to 80 000 rpm. The resulting duration of the molecular-beam pulses measured at the laser detection volume ranged from 80 μs to 13 μs and was the same for both NO and Br{sub 2}. The duration is consistent with a simple analytical model, and the minimum pulse width measured is limited by the spreading of the beam between the chopper and the detection point as a consequence of the longitudinal velocity distribution of the beam. The setup adopted here effectively eliminates buildup of background gas without the use of a differential pumping stage, and a clean narrow pulse is obtained with low rotational temperature.

  5. A chopper system for shortening the duration of pulsed supersonic beams seeded with NO or Br2 down to 13 μs

    Science.gov (United States)

    Lam, Jessica; Rennick, Christopher J.; Softley, Timothy P.

    2015-05-01

    A chopper wheel construct is used to shorten the duration of a molecular beam to 13 μs. Molecular beams seeded with NO or with Br2 and an initial pulse width of ≥200 μs were passed through a spinning chopper wheel, which was driven by a brushless DC in vacuo motor at a range of speeds, from 3000 rpm to 80 000 rpm. The resulting duration of the molecular-beam pulses measured at the laser detection volume ranged from 80 μs to 13 μs and was the same for both NO and Br2. The duration is consistent with a simple analytical model, and the minimum pulse width measured is limited by the spreading of the beam between the chopper and the detection point as a consequence of the longitudinal velocity distribution of the beam. The setup adopted here effectively eliminates buildup of background gas without the use of a differential pumping stage, and a clean narrow pulse is obtained with low rotational temperature.

  6. Development and applications of the reverse neutron time-of-flight method with Fourier-type beam chopper

    International Nuclear Information System (INIS)

    The neutron powder diffraction method has been applied to the crystal structure analysis of high-temperature superconductors such as La0.8Sr0.2CuO4-y, YBa2Cu3O7-y and Bi2Sr2CaCu2O8+y optically active yttriumformate Y(HCOO)3, and β phase of deuterated acetonitrile, CD3CN. The structural information, containing symmetry, positional and thermal parameters, occupation factors and the order parameter, was obtained by measuring the coherent elastic scattering cross-section. The Rietveld profile refinement method was used for the extraction of structural parameters from experimental data. The diffraction spectra were obtained by measuring the time-of-flight distribution of neutrons with a Fourier-type beam chopper. The neutron diffraction spectrum is created by the on-line synthesis of the cross-correlation function between the beam modulation function and the detector intensity. Such an operational mode, called the reverse time-of-flight method, has many unique properties. The possibility of filtering out a low-frequency part of a diffraction spectrum, eg. incoherent background, by a properly selected band-pass filter has been studied. One of the practical applications of the reverse time-of-flight method, the Mini-Sfinks facility, is described with technical details, and its operational characteristics are compared with other high-resolution instruments

  7. Results of calculations on the beam deflection due to the 1 MHz chopper for the Kaon factory

    International Nuclear Information System (INIS)

    Deflection of 1 GeV/c H- beam bunches to be eliminated by the 1 MHz chopper, for the proposed Kaon factory at TRIUMF, will be provided by an electric field between a set of deflector plates. Deflection rise time is a function of beam transit time through the deflector plates and the rise time of the stored voltage pulse. This paper presents the results of time-domain mathematical simulations to assess the relationship between the above quantities: the results of these simulations allow an accurate determination of the required rise-time of the stored voltage pulse. The representation of the deflector plates is modified so that linear displacement of the beam, as well as angular deflection, may be assessed. Simulations have also been performed to assess the attenuating effect of the deflector plates upon both angular deflection and linear displacement of the H- beam caused by voltage ripple. A measured voltage pulse is simulated as driving the deflector plates, and beam deflection is predicted. (Author) 12 refs., 3 figs

  8. A 55-dB SNDR, 2.2-mW double chopper-stabilized analog front-end for a thermopile sensor

    International Nuclear Information System (INIS)

    A double chopper-stabilized analog front-end (DCS-AFE) circuit for a thermopile sensor is presented, which includes a closed-loop front-end amplifier and a 2nd-order 1 bit quantization sigma—delta modulator. The amplifier with a closed-loop structure ensures the gain stability against the temperature. Moreover, by adopting the chopper-stabilized technique both for the amplifier and 2nd-order 1-bit quantization sigma—delta modulator, the low-frequency 1/f noise and offset is reduced and high resolution is achieved. The AFE is implemented in the SMIC 0.18 μm 1P6M CMOS process. The measurement results show that in a 3.3 V power supply, 1 Hz input frequency and 3KHz clock frequency, the peak signal-to-noise and distortion ratio (SNDR) is 55.4 dB, the effective number of bits (ENOB) is 8.92 bit, and in the range of −20 to 85 degrees, the detection resolution is 0.2 degree. (semiconductor integrated circuits)

  9. Quasielastic high-resolution time-of-flight spectrometers employing multi-disk chopper cascades for spallation sources

    International Nuclear Information System (INIS)

    The design of multi-disk chopper time-of-flight (MTOF) spectrometers for high-resolution quasielastic and low-energy inelastic neutron scattering at spallation sources is discussed in some detail. A continuously variable energy resolution (1 μeV to 10 meV), and a large dynamic range (1 μeV to 100 meV), are outstanding features of this type of instrument, which are easily achieved also at a pulsed source using state-of-the-art technology. The method of intensity-resolution optimization of MTOF spectrometers at spallation sources is treated on the basis of the requirement of using (almost) 'all the neutrons of the pulse', taking into account the constant, but wavelength-dependent duration of the source pulse. It follows, that the optimization procedure (which is slightly different from that employed in the steady-state source case) should give priority to the highest resolution, whenever such a choice becomes necessary. This leads to long monochromator distances (Ll2) of the order of 50 m, for achieving resolutions now available at reactor sources. A few examples of spectrometer layout and corresponding design parameters for large-angle and for small-angle quasielastic scattering instruments are given. In the latter case higher energy resolution than for large-angle scattering is required and achieved. The use of phase-space transformers, neutron wavelength band-pass filters and multichromatic operation for the purpose of intensity-resolution optimization are discussed. This spectrometer can be designed to make full use of the pulsed source peak flux. Therefore, and because of a number of improvements, high resolution will be available at high intensity: for any given resolution the total intensity at the detectors, when placed at one of the planned new spallation sources (SNS, JSNS, ESS, AUSTRON) will be larger by at least three orders of magnitude than the total intensity of any of the presently existing instruments of this type in routine operation at steady

  10. Terahertz antenna electronic chopper

    Energy Technology Data Exchange (ETDEWEB)

    Sterczewski, L. A., E-mail: lukasz.sterczewski@pwr.edu.pl; Grzelczak, M. P.; Plinski, E. F. [Department of Electronics, Wroclaw University of Technology, 27 Wybrzeze Wyspianskiego St., 50-370 Wroclaw (Poland)

    2016-01-15

    In this paper, we present an electronic circuit used to bias a photoconductive antenna that generates terahertz radiation. The working principles and the design process for the device are discussed in detail. The noise and shape of the wave measurements for a built device are considered. Furthermore, their impact on a terahertz pulse and its spectra is also examined. The proposed implementation is simple to build, robust and offers a real improvement over THz instrumentation due to the frequency tuning. Additionally, it provides for galvanic isolation and ESD protection.

  11. A Vector Switching Method of Multiphase Chopper in Superconducting Magnetic Energy Storage Systems%超导磁储能系统用多相斩波器矢量切换控制方法

    Institute of Scientific and Technical Information of China (English)

    施啸寒; 王少荣; 左文平

    2013-01-01

    在高功率超导磁储能装置(superconducting magnetic energy storage,SMES)中,电压源型功率调节系统首先利用多相斩波器将超导磁体电流转化成稳定的直流电压,再利用后级电压源型变流器(voltage source converter,VSC)与交流%In the high power superconducting magnetic energy storage (SMES) device, the voltage source converter (VSC) based power conditioning system (PCS) first converts the current of the superconducting magnetic to a stable DC voltage with the help of a multiphase chopper, and then utilizes a VSC to communicate power with the AC system. However, in the situation when the power communication between SMES and the grid changes too fast, a multiphase chopper with traditional current-self-shared PI controller has some problems such as the DC voltage deviation and transient current unbalance. The DC voltage deviation will further exert adverse effects on the control accuracy and speed of the succeeding VSC. To overcome these problems, this paper deduces the switching-function model of the multiphase chopper, and proposes a vector-switching-based control method using the deduced model. This method utilizes the hysteresis to switch the control vector to realize the DC voltage control, at the same time utilizes the redundant switch combinations of a control vector to realize the current sharing. Simulation shows that the proposed method can eliminate the DC voltage deviation when the power communication suddenly changing, and thus, provides a favorable condition for the fast and accurate control of the VSC. Besides, the proposed method can also realize current-sharing of the multiphase chopper in most of the situations, and therefore ensure the long-term operation of the system reliably.

  12. Larger research programs at the beam holes of the Austrian TRIGA Mark II reactor. Design and construction of a Fourier chopper-selector at the Austrian TRIGA reactor

    International Nuclear Information System (INIS)

    A neutron chopping system utilizing Fourier analysis has great advantages to alternative systems. For this purpose the chopper consists of a disc, opaque to neutrons, rotating on an axis perpendicular to its centre. Around its outside edge a series of uniformly spaced teeth and spaces are formed with neutron transparent gaps extending towards the centre. By using a stationary section having the same pattern of teeth and gaps it is possible to utilize a beam area considerably larger than the area of one tooth. During the last years at the TRIGA Reactor in Vienna a neutron chopping-and selecting-system is developed and in construction, which will not only chop the beam in that way necessary for Fourier analysis but also select the energy. The selection is done by seven discs of the form described above mounted on an axis. The selector is designed for neutron wave lengths between 3 and 30 A. The resolution is constant over the whole range of energy and depends on the beam divergence. Thus the modulation frequency is 104 sec-1 and the half-width of the neutron pulse about 50 μsec

  13. QDG1-30型秸秆枝丫切碎机试验分析%Experimental Analysis of QDG1-30 Straw and Branch Chopper

    Institute of Scientific and Technical Information of China (English)

    吴兆迁; 牛晓华; 才丽华

    2015-01-01

    QDG1-30型秸秆枝丫切碎机是我国用于人工林采伐、森林抚育剩余物等木质原料及各种农作物秸秆碎化处理的专用设备,该机采用鼓式切碎装置,结构简单、实用,生产效率高。性能和生产试验的结果显示:与QGP3-30型枝丫切碎机相比,生产率提高了24%以上,作业成本降低了22%以上,具有显著的经济效益。%QDG1-30 Straw and Branch Chopper is special equipment intended for chopping treatment of wooden residuals from plantation felling and forest tending and straws of various kinds in the rural area. This machine has a drum type chopping device, featuring a simple structure and high production efficiency, with the performance and production test result showing that this machine has significantly improved operation efficiency and production efficiency, up more than 24%, compared with QDG3-30, with operation cost falling by more than 22%, showing significant economic benefits.

  14. Development of a pulsed uniform supersonic gas expansion system based on an aerodynamic chopper for gas phase reaction kinetic studies at ultra-low temperatures.

    Science.gov (United States)

    Jiménez, E; Ballesteros, B; Canosa, A; Townsend, T M; Maigler, F J; Napal, V; Rowe, B R; Albaladejo, J

    2015-04-01

    A detailed description of a new pulsed supersonic uniform gas expansion system is presented together with the experimental validation of the setup by applying the CRESU (French acronym for Cinétique de Réaction en Ecoulement Supersonique Uniforme or Reaction Kinetics in a Uniform Supersonic Flow) technique to the gas-phase reaction of OH radicals with 1-butene at ca. 23 K and 0.63 millibars of helium (carrier gas). The carrier gas flow, containing negligible mixing ratios of OH-precursor and 1-butene, is expanded from a high pressure reservoir (337 millibars) to a low pressure region (0.63 millibars) through a convergent-divergent nozzle (Laval type). The novelty of this experimental setup is that the uniform supersonic flow is pulsed by means of a Teflon-coated aerodynamic chopper provided with two symmetrical apertures. Under these operational conditions, the designed Laval nozzle achieves a temperature of (22.4 ± 1.4) K in the gas jet. The spatial characterization of the temperature and the total gas density within the pulsed uniform supersonic flow has also been performed by both aerodynamical and spectroscopic methods. The gas consumption with this technique is considerably reduced with respect to a continuous CRESU system. The kinetics of the OH+1-butene reaction was investigated by the pulsed laser photolysis/laser induced fluorescence technique. The rotation speed of the disk is temporally synchronized with the exit of the photolysis and the probe lasers. The rate coefficient (k(OH)) for the reaction under investigation was then obtained and compared with the only available data at this temperature. PMID:25933898

  15. FSY30型林木枝丫切碎机试验分析%Experimental Analysis of FSY30 Tree Branch Chopper

    Institute of Scientific and Technical Information of China (English)

    牛晓华; 吴兆迁; 樊涛; 王晓军

    2011-01-01

    FSY30型林木枝丫切碎机是林区林木剩余物碎化处理的专用设备,该机采用圆盘式切碎装置,结构简单实用,解决了我国现有林木剩余物碎化处理设备野外作业性能差、切削效率低和原料适应面窄等问题,为我国林区人工林迹地整理更新、抚育和采伐等作业产生的各种林木剩余物碎化处理提供了适用的设备。该机性能和生产试验结果表明:其作业效率比现有机型提高20%以上,作业成本减少15%以上,具有显著的经济效益和一定的生态效益。%FSY30 tree branch chopper is a machine specially used for chopping forest residuals in forest areas. The machine uses a disc type chopping device, with a simple and practical structure, and has solved the problems with poor Operation performance in the field, low chopping efficiency and narrow adaptive scope of raw materials of the existing equipment and provided proper equipment for regeneration, tending and harvesting operations in the plantation area in China. Performance and production experiments show that the operation efficiency of the machine has improved by 20% over the current machine types and the operation cost has reduced by15%, with noticeable economic and social benefits.

  16. 四象限斩波控制直流调速系统的技术研究%Technology Research of DC Speeding for Four-quadrant Chopper Control System

    Institute of Scientific and Technical Information of China (English)

    李一鸣; 荣军; 邓斌; 易学良

    2016-01-01

    DC motor has wide speeding range and high precision, and it has very important application for the industrial fields required to speeding and braking performance. Firstly, the mathematical model of DC motor is introduces, and the three methods of its speed regulation are given, and the method of changing the armature voltage is chosen as the method of its speed regulation. Then the working principle of DC speeding system for four-quadrant chopper control is analyzed in detail, andthemodels is established based on Matlab/Simulink, and the simulation results are given. Through the analysis of simulation results, the simulation results are consistent with the theoretical analysis, and the correctness of theoretical analysis and modeling simulation of DC speed control system for the four-quadrant chopper control is verified.Finally, the advantages of DC speed control system for the four-quadrant chopper control are highlighted by comparing the simulation results with the other two kinds of chopper DC drive system.%直流电动机具有调速范围广以及调速精度高的特点,因此在要求调速和制动性能高的工业领域有非常广泛的应用。本文首先介绍了直流电机的数学模型,给出其调速的三种方法,最后选择改变电枢电压作为其调速的方法。然后详细分析了四象限斩波控制直流调速的工作原理,并且在Matlab/Simulink中建立了四象限斩波控制直流调速模型,并给出了其仿真结果。仿真结果与理论分析完全一致,验证了四象限斩波控制直流调速系统理论分析和建模仿真的正确性。最后通过与其它两种斩波直流调速系统仿真结果比较,显示了四象限斩波控制直流调速系统的优越性。

  17. Chopper-stabilized phase detector

    Science.gov (United States)

    Hopkins, P. M.

    1978-01-01

    Phase-detector circuit for binary-tracking loops and other binary-data acquisition systems minimizes effects of drift, gain imbalance, and voltage offset in detector circuitry. Input signal passes simultaneously through two channels where it is mixed with early and late codes that are alternately switched between channels. Code switching is synchronized with polarity switching of detector output of each channel so that each channel uses each detector for half time. Net result is that dc offset errors are canceled, and effect of gain imbalance is simply change in sensitivity.

  18. Determination of efficiencies, loss mechanisms, and performance degradation factors in chopper controlled dc vehical motors. Section 2: The time dependent finite element modeling of the electromagnetic field in electrical machines: Methods and applications. Ph.D. Thesis

    Science.gov (United States)

    Hamilton, H. B.; Strangas, E.

    1980-01-01

    The time dependent solution of the magnetic field is introduced as a method for accounting for the variation, in time, of the machine parameters in predicting and analyzing the performance of the electrical machines. The method of time dependent finite element was used in combination with an also time dependent construction of a grid for the air gap region. The Maxwell stress tensor was used to calculate the airgap torque from the magnetic vector potential distribution. Incremental inductances were defined and calculated as functions of time, depending on eddy currents and saturation. The currents in all the machine circuits were calculated in the time domain based on these inductances, which were continuously updated. The method was applied to a chopper controlled DC series motor used for electric vehicle drive, and to a salient pole sychronous motor with damper bars. Simulation results were compared to experimentally obtained ones.

  19. An optimized SVPWM switching strategy for three-level NPC VSI and a novel switching strategy for three-level two-quadrant chopper to stabilize the voltage of capacitors

    International Nuclear Information System (INIS)

    Voltage source inverter (VSI) can produce single and three-phase (3P) AC voltages from a constant or variable DC voltage. There are many ways to control the VSI output voltage. Each control way produces some harmonics at the VSI output voltage. The space vector pulse width modulation (SVPWM) may be more effective than other modulation methods, e.g. harmonic injection, phase shifting, multi career pulse width modulation, in decreasing the low order harmonics (LOH). Different switching strategies (SSs) of power electronic devices in SVPWM have some specific advantages and disadvantages with regard to one another. In this paper, a comparative study between different SVPWM SSs is carried out by considering some objective functions such as total harmonic distortion (THD), power and switching losses, the ratio of the harmonic components to the fundamental component, distortion factor (DF). It is also shown that by selecting an optimized and appropriate SS for SVPWM, the harmonic orders, which are the multiples of the frequency index (FI), are eliminated. Then, to investigate the impact of variations of the capacitors voltage and switching frequency on power quality criteria, the most appropriate and optimized SS is applied to a 3P three-level (3L) neutral-point-clamped (NPC) VSI to supply a 3P load. This paper also presents a novel and optimized SS and control approach for a 3L two-quadrant (2Q) chopper in NPC VSI superconducting magnetic energy storage (SMES). Using the proposed SS, the voltage of the VSI capacitors in SMES can be independently controlled; also, the minimum power and switching losses - as well as the proper convection - can be achieved using this same strategy. The simulation results indicate that when combined with a proportional-integral (PI) control approach the proposed SS can be easily implemented in the power networks and can balance and stabilize the multi-level VSIs' capacitor voltage level. The voltage variation of the capacitors in the steady

  20. An optimized SVPWM switching strategy for three-level NPC VSI and a novel switching strategy for three-level two-quadrant chopper to stabilize the voltage of capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Mohammad Reza, Alizadeh Pahlavani [Department of Electrical Engineering, Iran University of Science and Technology (IUST), Tehran (Iran, Islamic Republic of); Ali, Mohammadpour Hossine [Department of Electrical Engineering, University of South Carolina, Columbia, SC (United States)

    2010-12-15

    Voltage source inverter (VSI) can produce single and three-phase (3P) AC voltages from a constant or variable DC voltage. There are many ways to control the VSI output voltage. Each control way produces some harmonics at the VSI output voltage. The space vector pulse width modulation (SVPWM) may be more effective than other modulation methods, e.g. harmonic injection, phase shifting, multi career pulse width modulation, in decreasing the low order harmonics (LOH). Different switching strategies (SSs) of power electronic devices in SVPWM have some specific advantages and disadvantages with regard to one another. In this paper, a comparative study between different SVPWM SSs is carried out by considering some objective functions such as total harmonic distortion (THD), power and switching losses, the ratio of the harmonic components to the fundamental component, distortion factor (DF). It is also shown that by selecting an optimized and appropriate SS for SVPWM, the harmonic orders, which are the multiples of the frequency index (FI), are eliminated. Then, to investigate the impact of variations of the capacitors voltage and switching frequency on power quality criteria, the most appropriate and optimized SS is applied to a 3P three-level (3L) neutral-point-clamped (NPC) VSI to supply a 3P load. This paper also presents a novel and optimized SS and control approach for a 3L two-quadrant (2Q) chopper in NPC VSI superconducting magnetic energy storage (SMES). Using the proposed SS, the voltage of the VSI capacitors in SMES can be independently controlled; also, the minimum power and switching losses - as well as the proper convection - can be achieved using this same strategy. The simulation results indicate that when combined with a proportional-integral (PI) control approach the proposed SS can be easily implemented in the power networks and can balance and stabilize the multi-level VSIs' capacitor voltage level. The voltage variation of the capacitors in the

  1. Transformer regulated self-stabilizing chopper

    Science.gov (United States)

    Raposa, F. L. (Inventor)

    1969-01-01

    A self-stabilizing voltage regulator is described. Direct current voltage regulation employing a series transistor rendered conductive during various portions of a cycle is controlled by saturation of an autotransformer. The constant volt-second capacity of the transformer provides conduction time inverse to the input voltage whereby average output voltage is maintained constant. Conduction commenced in response to short gate signals, and resistor feedback for degenerative turn-off of the transistor was after transformer saturation. Standard output filters are also included.

  2. Polarization analysis for the thermal chopper spectrometer TOPAS

    Directory of Open Access Journals (Sweden)

    Voigt Jörg

    2015-01-01

    Full Text Available We report on the progress of the construction of the thermal time-of-flight spectrometer with polarization analysis TOPAS at the Mayer-Leibnitz Zentrum (MLZ. The instrument components approach the status to be ready for installation. The special feature of the instrument is its capability for wide-angle polarization analysis in the thermal spectral range. Here we describe a novel approach to rotate the neutron spin adiabatically into the X, Y or Z direction of the laboratory frame by combination of permanent magnets aligned as Halbach rings and electrically generated fields. Despite the severe spatial restrictions the design exhibits a very high adiabaticity and interacts only weakly with the coil layout for the analyzing 3He spin filter cell (SFC.

  3. Modeling and Simulation of Choppers Switching via Matlab/Simulink

    Directory of Open Access Journals (Sweden)

    Ehsan HOSSEINI

    2015-06-01

    Full Text Available Modeling and simulating the converter using the modelling equations is necessary to design of power electronic converter circuit with the use of closed loop scheme. This can easily be done with the help of state equations and MATLAB/SIMULINK as a tool for simulation of those state equations. An attempt has been made in this paper to simulate all basic non-isolated power converters. So that these models can be readily used for any close loop design (say using PI, fuzzy, or sliding mode control etc..

  4. Extracting source parameters from beam monitors on a chopper spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Abernathy, Douglas L [ORNL; Niedziela, Jennifer L [ORNL; Stone, Matthew B [ORNL

    2015-01-01

    The intensity distributions of beam monitors in direct-geometry time-of-flight neutron spectrometers provide important information about the instrument resolution. For short-pulse spallation neutron sources in particular, the asymmetry of the source pulse may be extracted and compared to Monte Carlo source simulations. An explicit formula using a Gaussian-convolved Ikeda-Carpenter distribution is given and compared to data from the ARCS instrument at the Spallation Neutron Source.

  5. 小型反向式切桑机的研制及主要技术参数的优化试验%Development and Experimental Run of Small Scale Reverse-type Mulberry Leaf Chopper and Optimization Test of Main Technical Parameters

    Institute of Scientific and Technical Information of China (English)

    梁培生; 张国政; 韦亚东; 张业顺

    2011-01-01

    为提高蚕桑生产中切桑作业的工效和质量,满足小蚕共育规模化发展的需要,研制了一种小型反向式切桑机具.该机由独特结构的带齿形刀的刀辊、圆刀片组和定刀构成,三者之间的配合完成对桑叶横向和纵向切割,具有工效高、可保持桑叶新鲜度及造价低廉等特点.根据该机的切碎原理及工作过程,分析影响桑叶切碎质量的主要因素,通过对主要工作部件圆刀片组、刀辊的技术参数的分析及单因素试验,确定机具的最佳工作参数为:齿形刀与圆刀片组之间的间隙1.5 ~2.0 mm,齿形刀楔角12°,齿形刀厚度3 mm,圆刀片组转速1 000~1 200 r/min,刀辊转速650 r/min,输送带速度0.11 m/s.样机试用切桑工效达到400 kg/h,是人工切桑的12倍以上.%In order to improve the operation efficiency and quality of chopping mulberry leaves for sericultural production, especially for large scale cooperative rearing of young larvae, a novel small scale reverse-type mulberry leaf chopper has been developed. This device consists of a uniquely structured cutter roller with serrated blades, a round blade set, and a fixed blade. The cooperation of these three units leads to transverse and longitudinal cutting of mulberry leaves with high operation efficiency while maintaining good freshness of the leaves and having a low production cost. Based on the chopping principle and working process, the main factors that affect the cutting quality of mulberry leaves were analyzed. Analyses and single factor experiments to operating parameters of the main working parts (round blade set and cutter roller) showed that the optimal operating parameters are 1. 5 ~2. 0 mm gap between the round blade and serrated blade, 12 angel of the serrated blade, 3 mm thickness of the serrated blade, 1 000 ~1 200 r/min rotating speed of the round blade set, 650 r/min rotating speed of the cutter roller, and 0.11 m/s of the conveyer speed. The test run of model

  6. Evolution of Automotive Chopper Circuits Towards Ultra High Efficiency and Power Density

    Science.gov (United States)

    Pavlovsky, Martin; Tsuruta, Yukinori; Kawamura, Atsuo

    Automotive industry is considered to be one of the main contributors to environmental pollution and global warming. Therefore, many car manufacturers are in near future planning to introduce hybrid electric vehicles (HEV), fuel cell electric vehicles (FCEV) and pure electric vehicles (EV) to make our cars more environmentally friendly. These new vehicles require highly efficient and small power converters. In recent years, considerable improvements were made in designing such converters. In this paper, an approach based on so called Snubber Assisted Zero Voltage and Zero Current Switching topology otherwise also known as SAZZ is presented. This topology has evolved to be one of the leaders in the field of highly efficient converters with high power densities. Evolution and main features of this topology are briefly discussed. Capabilities of the topology are demonstrated on two case study prototypes based on different design approaches. The prototypes are designed to be fully bi-directional for peak power output of 30kW. Both designs reached efficiencies close to 99% in wide load range. Power densities over 40kW/litre are attainable in the same time. Combination of MOSFET technology and SAZZ topology is shown to be very beneficial to converters designed for EV applications.

  7. Research on a new active power filter topology based on chopper circuit

    OpenAIRE

    Xiaoling, Guo; Jian, Cheng; Bo, Zhang; Jing, Zhang

    2015-01-01

    The active power filter (APF) is attracting more and more attention for its outstanding performance in current and voltage ripple compensation. As modern high-energy accelerators are demanding much more stringent current ripple guideline, the APF is introduced to the magnet power supply (MPS) in accelerator system. However, the conventional APF has a lot of shortages and drawbacks due to its traditional topology, such as complex structure, nonadjustable working voltage, requirement of power s...

  8. Analysis of a PWM Resonant Buck Chopper for Use as a Ship Service Converter Module

    OpenAIRE

    Ciezki, John G.; Ashton, Robert W.

    1999-01-01

    The Navy's interest in implementing a DC Zonal Electric Distribution System (DC ZEDS) in the next generation of surface combatant has motivated considerable research work into dc-dc converters. The switching frequency of a hard-switched dc-dc converter is limited by the maximum admissible switching losses allowed by the switch, heat sink, and cooling process. Also, hard- switched converters contribute significant Electromagnetic Interference (EMI) concerns for the system. This study provides ...

  9. Parameterization of a synchronous generator to represent a doubly fed induction generator with chopper protection for fault studies

    OpenAIRE

    Martínez Navarro, Jorge; Kjaer, P.C.; Rodríguez Cortés, Pedro; Teodorescu, Remus

    2010-01-01

    This paper addresses the representation of the wound rotor asynchronous generators by an equivalent synchronous generator, valid for short circuit current calculations. Modern wind power plants are required and designed to ride through faults in the network, subjected to fault clearing. Accurate knowledge of the wind turbine short circuit current contribution is needed for component sizing and protection relay settings during faults within the wind power plant collector system or ...

  10. From scootes to choppers : Product protfolio change and organizational failure - Evidence from the UK motorcycle industry 1895 to 1993

    NARCIS (Netherlands)

    Wezel, FC; van Witteloostuijn, A

    2006-01-01

    This article explores the conditions under which organizational change increases the risk of organizational failure. To reach this goal, we examine the pros and cons of flexibility and inertia arguments. Empirically, we measure the survival consequences of product portfolio expansion in the British

  11. Parameterization of a synchronous generator to represent a doubly fed induction generator with chopper protection for fault studies

    DEFF Research Database (Denmark)

    Martinez, Jorge; Kjær, Philip C.; Rodriguez, Pedro;

    2011-01-01

    This paper addresses the representation of the wound rotor asynchronous generators by an equivalent synchronous generator, valid for short circuit current calculations. Modern wind power plants are required and designed to ride through faults in the network, subjected to fault clearing. Accurate...... knowledge of the wind turbine short circuit current contribution is needed for component sizing and protection relay settings during faults within the wind power plant collector system or in the external networks. When studying fault currents and protection settings for wind power installations, the...

  12. Wet granulation in laboratory-scale high shear mixers: Effect of chopper presence, design and impeller speed

    OpenAIRE

    Chitu, Toma Mihai; Oulahna, Driss; Hemati, Mehrdji

    2011-01-01

    The effect of the main means of agitation in a high shear mixer has been investigated in this study. Granulation runs have been performed on a fine cohesive microcrystalline cellulose powder (Avicel 105, d50 = 20 μm) often used as a pharmaceutical excipient in tablet formulations in two bowls of a Mi-Pro® laboratory high shearmixer with a capacity of 0.9 and 1.9 L, respectively. Torque curves recorded during granulation are found to allow good control of the process while increasing impeller ...

  13. Design and implementation of a zero-voltage-switching, pulse-width-modulated, high-frequency, resonant buck chopper

    OpenAIRE

    Turner, Clifton C.

    1999-01-01

    As the Navy moves toward a modular DC Zonal Electrical Distribution System (DC ZEDS) to reduce both cost and weight over traditional radial shipboard distribution, there is a need to capitalize on technological advances currently available. The 21st century shipboard power distribution system calls for a DC bus architecture to eliminate the need for large transformers and thousands of pounds of cable through the use of high-speed semiconductor converters. In order to realize dramatic reductio...

  14. Momentum and Energy Dependent Resolution Function of the ARCS Neutron Chopper Spectrometer at High Momentum Transfer: Comparing Simulation and Experimen

    CERN Document Server

    Diallo, S O; Abernathy, D L; Azuah, R T

    2016-01-01

    Inelastic neutron scattering at high momentum transfers (i.e. $Q\\ge20$ {\\AA}) or DINS provides direct observation of the momentum distribution of light atoms, making it a powerful probe for studying single-particle motions in liquids and solids. The quantitative analysis of DINS data requires an accurate knowledge of the instrument resolution function $R_{i}({Q},E)$ at each $Q$ and energy transfer $E$, where the label $i$ indicates whether the resolution was experimentally observed $i={obs}$ or simulated $i=sim$. Here, we describe two independent methods for determining the total resolution function $R_{i}({Q},E)$ of the ARCS neutron instrument at the Spallation Neutron Source, Oak Ridge National Laboratory. The first method uses experimental data from an archetypical system (liquid $^4$He) studied with DINS, which are then numerically deconvoluted using its previously determined intrinsic scattering function to yield $R_{obs}({Q},E)$. The second approach uses accurate Monte Carlo simulations of the ARCS spec...

  15. Beam dynamics simulation of injector for high power CW electron linac in PNC

    International Nuclear Information System (INIS)

    The injector consists of a 200 kV DC gun, a RF chopper, a chopper slit, a prebuncher and a buncher. Solenoid coils covered from the exit of gun to accelerating tube 1 except between the RF chopper and chopper slit. Beam trajectories are simulated by PARMELA in order to design the injector. In this report, two simulation results are shown. One is for a beam trajectory from gun to solenoid coils. There is thick concrete wall between gun to RF chopper. Low energy electrons are transported through long solenoid coil area. The other is for a chopper part. The novel chopper system is designed to reduce the emittance growth. (author)

  16. Tools for women’s empowerment? : the case of the forage chopper for smallholder dairy farmers in Uganda smallholder dairy farmers in Uganda

    OpenAIRE

    Lubwama Kiyimba, F.B.

    2011-01-01

    Labour-saving tools have been advocated as an important means of increasing production and improving the quality of life of rural Africans. They can be very useful in reducing household labour requirements, especially during the peak production season when these requirements are high. Women have been specifically targeted in the development and dissemination of such tools, with the aim of helping them reassign time from farming and domestic activities towards income generating activities. Eng...

  17. Research and Design of Circlecutter Chopper for Mulberry Leaf%圆弧刀式切桑机的研究设计

    Institute of Scientific and Technical Information of China (English)

    梁培生; 张国政; 方瑷

    2014-01-01

    根据小蚕用桑特点及小蚕共育户的要求,研究设计了一种圆弧刀式结构的桑叶条叶切割机。该机采用了圆弧式刀刃曲线,以凹凸刀刃相结合的方式实现切割,具有刀片结构简单、制造安装和磨刃方便的特点,整机工效达到450~500 kg/h,1~3龄蚕可用。为此,阐述该机的设计思路、结构形式和工作原理,介绍了该机的主要工作部件结构和参数的设计。该机的研制取代了目前的人工切桑方式,解决了小蚕共育户切桑劳动强度大、工效低的问题,大大提高了养蚕劳动生产率,而且具有保持叶质新鲜、机具维护方便、使用成本低等特点,受到小蚕共育户的欢迎。%According to the characteristics of the requirements with small silkworm mulberry and silkworm produced , a cutter article mulberry leaf is research design ,It is the structure of the circular knife .It adopted the blade curve of the arc, It cut in way of combination of concave and convex edge blade with characteristics of simple structure , The charac-teristics of convenient installation and the blade , Tts efficiency of 450-500 kg/h, suit to use 1-3 instars silkworm .De-sign idea , structure and working principle were expounded , the structure and parameters design of the main working parts are introduced .It replaced the way of manual cutting mulberry now , solved the problem of large labor intensity and low efficiency of mulberry silkworm produced users of small , It can improve the labor productivity greatly sericulture , and has the characteristics of the keep fresh leaf, machine maintenance convenience, low use cost, small silkworm produced popular users .

  18. 热释电型非制冷焦平面热像仪调制斩波器的分析--斩波器与信号读出模式%ANALYSIS OF MODULATING CHOPPER USED IN PYROELECTRIC UNCOOLED FPA THERMAL IMAGER--CHOPPER AND DETECTOR PIXELS' SIGNAL READOUT MODE

    Institute of Scientific and Technical Information of China (English)

    何玉青; 金伟其; 高雅允; 刘广荣; 王霞

    2003-01-01

    对阿基米德斩波器及其工作状态进行了模拟,分析了探测器像元的曝光时间、曝光顺序、信号读出及其对后续信号均匀性处理的影响.结果表明:探测器曝光的非均匀性与信号读出模式直接影响后续信号的均匀性处理,阿基米德螺旋线的参数、探测器几何尺寸、斩波器与探测器的相对位置等均影响探测器的曝光顺序和电荷均匀性.在热成像系统总体设计以及电子处理系统设计时,必须综合考虑斩波器各参数的影响.

  19. 热释电型非制冷焦平面热像仪调制斩波器的分析--斩波器的曝光效率%ANALYSIS OF MODULATING CHOPPER USED IN PYROELECTRIC UNCOOLED FPA THERMAL IMAGER--CHOPPER'S EXPOSURE EFFICIENCY

    Institute of Scientific and Technical Information of China (English)

    何玉青; 金伟其; 高稚允; 刘广荣; 王霞

    2004-01-01

    对阿基米德螺旋线调制斩波器的曝光效率进行了理论分析和数值模拟,得到斩波器曝光效率对后续信号处理的影响.曝光效率直接影响后续探测器单元的曝光时间及入射辐射信号,与探测器信号读出时刻共同影响探测器有效积累电荷的均匀性;同时应在斩波器中增加调制同步定位点,可使热像仪适宜不同曝光效率的斩波器.在热成像系统设计以及电子处理系统设计时,必须综合考虑斩波器曝光效率的影响.

  20. Development of methods for measuring materials nuclear characteristics, Phases, I, II, II and IV

    International Nuclear Information System (INIS)

    This report contains the following phases of the project 'measurement of nuclear characteristics of reactor materials': nuclear performances of the neutron chopper; method for measuring total effective cross sections by transmission method on the chopper; review of methods for measuring activation cross sections; measurement of neutron spectra of the RA reactor and measurement of total effective cross section of gold by using the chopper

  1. The design of maize chopper for stalk and stubble with double vertical shafts%双立轴式玉米秸秆切碎灭茬机的设计

    Institute of Scientific and Technical Information of China (English)

    曹艳玲; 高爱云; 付主木; 甄济营

    2003-01-01

    对传统的后置旋耕式秸秆还田机进行了改造,设计了前置双立轴式玉米秸秆切碎灭茬机,并对其工作原理和有关参数的选择进行了研究.试验证明,切碎动刀采用直线刀,动刀与刀盘配置采用了具有滑切功能的方式,可以大大降低功耗,达到很好的切碎效果.

  2. Design and experiment on banana stalk chopper with feeding type spindle flail%喂入式立轴甩刀香蕉秸秆粉碎还田机设计与试验

    Institute of Scientific and Technical Information of China (English)

    甘声豹; 李粤; 张喜瑞; 张国健; 王能

    2014-01-01

    由于香蕉秸秆粗大、含水率高,现有的粉碎还田机大多操作繁琐、作业不稳定。针对上述问题,研制了一种喂入式立轴甩刀香蕉秸秆粉碎还田机,描述了该机的总体设计方案及主要部件的结构,分析了各部件之间的相互关系,确定了其关键参数的最优值。试验结果表明:该机在前进速度为2.16~3.60 km/h、压辊进料转速为127.39 r/min、立轴甩刀旋转速度为1080 r/min时,秸秆粉碎质量合格率达94.9%、田间覆盖率达88.61%、茎杆留茬高度为30~35 mm,一次作业可将秸秆粉碎成丝状残渣,且残渣抛洒还田均匀。试验结果对解决因秸秆难处理而制约农村合作社小规模种植的难题具有重要意义。%Bananas occupy an extremely important position in the world of fruit trade; it is the most important fruit in tropical and subtropical areas. China is one of the world’s largest producers of bananas, and bananas have become an agricultural pillar industry in China’s subtropical regions. However, the banana stalks are a major agricultural waste. According to the Food and Agriculture Organization (FAO), in 2010, 24 million tons of annual output of waste is banana straw in China. If such a large amount of waste straw is not handled in time, it would seriously pollute the environment and affect the renewal of the banana plantation. Because banana stalks are thick with a high level of moisture and other issues, there are less mature mechanical equipments for banana stalks treatment at the present. There are usually two main types of banana stalk treatment: one is to cut down and pile the stalk in the fields by laborers, and then let it rot; the other one is a centrally smash processing with machines. This kind of machine can achieve a certain crushing effect, but, due to the characteristics of its own design, can't achieve the field operations, and thus brings great inconvenience for the laborers. In view of above situations, according to craft about the banana stalks’ crushing and returning in the field, this study designed a feeding type vertical shaft flail extracting machine for banana stalks’ crushing and returning, and expounded the machine's overall configuration and the main components of the structure, and determined the key parameters of the optimal value through the analysis of the relationship between components and performance test. The machine could work directly in the field under the tractor traction, for the stalks to achieve down, tackle, grab, feed, crush and return. Field experiments showed that: with the speed for forwarding at 2.16 - 3.60 km/h, for the feed roller at 127.39 r/min, and for the vertical sling knife at 1080 r/min, this machine could achieve a qualification rate of straw smashing of 94.9%, field coverage of 88.61%, stem stubble height of 30 - 35 mm, energy consumption of 4.625 kg/h, and working efficiency of 0.39 hm2/h. This machine was easy to operate and its crushing effect was satisfactory. Its successful implementation could not only greatly improve the production efficiency, and solve the problem of large-scale banana cultivation facing massive stalks processing, but also prevent the pollution of the environment and had important economic and ecological benefits.

  3. Control Design of HT-SMES Chopper Based on DSP2812%基于DSP2812高温超导储能系统斩波器控制设计

    Institute of Scientific and Technical Information of China (English)

    诸嘉慧; 杨斌; 黄宇淇; 郭云峥

    2010-01-01

    电压型超导储能(Superconduction Magnetic Energy Storge,简称SMES)系统的斩波器用于对超导磁体快速稳定充放电.研究了SMES系统用斩波器充放电的工作原理,采用状态空间平均法建立其数学模型,并提出一种斩波器充电、放电的闭环控制方法.基于第2代高温超导磁体及其限流保护,搭建了斩波器实验系统,应用DSP2812处理器实现对超导磁体充放电的控制.实验结果表明,所应用斩波器控制方法的性能良好,可以满足SMES系统的要求.

  4. Design and experiment on banana stalk chopper with feeding type spindle flail%喂入式立轴甩刀香蕉秸秆粉碎还田机设计与试验

    Institute of Scientific and Technical Information of China (English)

    甘声豹; 李粤; 张喜瑞; 张国健; 王能

    2014-01-01

    Bananas occupy an extremely important position in the world of fruit trade; it is the most important fruit in tropical and subtropical areas. China is one of the world’s largest producers of bananas, and bananas have become an agricultural pillar industry in China’s subtropical regions. However, the banana stalks are a major agricultural waste. According to the Food and Agriculture Organization (FAO), in 2010, 24 million tons of annual output of waste is banana straw in China. If such a large amount of waste straw is not handled in time, it would seriously pollute the environment and affect the renewal of the banana plantation. Because banana stalks are thick with a high level of moisture and other issues, there are less mature mechanical equipments for banana stalks treatment at the present. There are usually two main types of banana stalk treatment: one is to cut down and pile the stalk in the fields by laborers, and then let it rot; the other one is a centrally smash processing with machines. This kind of machine can achieve a certain crushing effect, but, due to the characteristics of its own design, can't achieve the field operations, and thus brings great inconvenience for the laborers. In view of above situations, according to craft about the banana stalks’ crushing and returning in the field, this study designed a feeding type vertical shaft flail extracting machine for banana stalks’ crushing and returning, and expounded the machine's overall configuration and the main components of the structure, and determined the key parameters of the optimal value through the analysis of the relationship between components and performance test. The machine could work directly in the field under the tractor traction, for the stalks to achieve down, tackle, grab, feed, crush and return. Field experiments showed that: with the speed for forwarding at 2.16 - 3.60 km/h, for the feed roller at 127.39 r/min, and for the vertical sling knife at 1080 r/min, this machine could achieve a qualification rate of straw smashing of 94.9%, field coverage of 88.61%, stem stubble height of 30 - 35 mm, energy consumption of 4.625 kg/h, and working efficiency of 0.39 hm2/h. This machine was easy to operate and its crushing effect was satisfactory. Its successful implementation could not only greatly improve the production efficiency, and solve the problem of large-scale banana cultivation facing massive stalks processing, but also prevent the pollution of the environment and had important economic and ecological benefits.%由于香蕉秸秆粗大、含水率高,现有的粉碎还田机大多操作繁琐、作业不稳定。针对上述问题,研制了一种喂入式立轴甩刀香蕉秸秆粉碎还田机,描述了该机的总体设计方案及主要部件的结构,分析了各部件之间的相互关系,确定了其关键参数的最优值。试验结果表明:该机在前进速度为2.16~3.60 km/h、压辊进料转速为127.39 r/min、立轴甩刀旋转速度为1080 r/min时,秸秆粉碎质量合格率达94.9%、田间覆盖率达88.61%、茎杆留茬高度为30~35 mm,一次作业可将秸秆粉碎成丝状残渣,且残渣抛洒还田均匀。试验结果对解决因秸秆难处理而制约农村合作社小规模种植的难题具有重要意义。

  5. Sistem Kendali Kecepatan Motor DC Dengan Menggunakan Mikrokontroler

    OpenAIRE

    Ompusunggu, Chandra Putra

    2012-01-01

    Motor DC merupakan alat pengubah energi listrik menjadi energi gerak yang dicatu oleh tegangan DC. Kecepatan putaran dapat diatur dengan mengubah nilai tegangan atau arus yang masuk ke motor. Salah satu cara pengaturan kecepatan pada motor DC yaitu dengan menggunakan DC-DC konverter atau sering disebut dengan chopper. Chopper adalah suatu alat yang berfungsi untuk mengubah tegangan DC tetap menjadi tegangan DC yang bervariasi. Tegangan keluaran chopper dapat lebih besar atau lebih kecil dari ...

  6. The electron test accelerator beam injector

    International Nuclear Information System (INIS)

    A beam chopper and buncher system has been designed to improve the capture efficiency and reduce the beam spill in the Electron Test Accelerator. The buncher increases the dc beam capture from 30 to 70%. 100% beam transmission through the accelerator structures is obtained with the chopper. This report describes results of experimental tests with the beam injector. Results from computer modeling and from measurements with prototypes that have led to the design of the beam chopper and buncher system are discussed

  7. Improved battery charger for electric vehicles

    Science.gov (United States)

    Rippel, W. E.

    1981-01-01

    Polyphase version of single-phase "boost chopper" significantly reduces ripple and electromagnetic interference (EMI). Drive circuit of n-phase boost chopper incorporates n-phase duty-cycle generator; inductor, transistor, and diode compose chopper which can run on single-phase or three-phase alternating current or on direct current. Device retains compactness and power factors approaching unity, while improving efficiency.

  8. Summary of electric vehicle dc motor-controller tests

    Science.gov (United States)

    Mcbrien, E. F.; Tryon, H. B.

    1982-01-01

    The differences in the performance of dc motors are evaluated when operating with chopper type controllers, and when operating on direct current. The interactions between the motor and the controller which cause these differences are investigated. Motor-controlled tests provided some of the data the quantified motor efficiency variations for both ripple free and chopper modes of operation.

  9. IMPROVING THE TECHNOLOGIES AND EQUIPMENT OF PREPARATION AND DISTRI-BUTION OF ROUGH FOOD PRODUCTS FROM ROLLS

    Directory of Open Access Journals (Sweden)

    Frolov V. Y.

    2014-05-01

    Full Text Available In this article we consider the analysis of structures of technical means used for the preparation and distribution of animal feed and develop a distributor-chopper, which allows distributing it while milling. The classification is designed for feeders; we also give economic and mathematical model and a constructively technical scheme of a distributor-chopper on its basis

  10. The performance and efficiency of four motor/controller/battery systems for the simpler electric vehicles

    Science.gov (United States)

    Shipps, P. R.

    1980-01-01

    A test and analysis program performed on four complete propulsion systems for an urban electric vehicle (EV) is described and results given. A dc series motor and a permanent magnet (PM) motor were tested, each powered by an EV battery pack and controlled by (1) a series/parallel voltage-switching (V-switch) system; and (2) a system using a pulse width modulation, 400 Hz transistorized chopper. Dynamometer tests were first performed, followed by eV performance predictions and data correlating road tests. During dynamometer tests using chopper control; current, voltage, and power were measured on both the battery and motor sides of the chopper, using three types of instrumentation. Conventional dc instruments provided adequate accuracy for eV power and energy measurements, when used on the battery side of the controller. When using the chopper controller, the addition of a small choke inductor improved system efficiency in the lower duty cycle range (some 8% increase at 50% duty cycle) with both types of motors. Overall system efficiency rankings during road tests were: (1) series motor with V-switch; (2) PM motor with V-switch; (3) series motor with chopper; and (4) PM motor with chopper. Chopper control of the eV was smoother and required less driver skill than V-switch control.

  11. A design study of VOR

    DEFF Research Database (Denmark)

    Deen, P. P.; Vickery, Anette; Andersen, K. H.;

    2015-01-01

    VOR, the versatile optimal resolution chopper spectrometer, is designed to probe dynamic phenomena that are currently inaccessible for inelastic neutron scattering due to flux limitations. VOR is a short instrument by the standards of the European Spallation Source (ESS), 30.2m moderator to sample...... impossible both on a long chopper spectrometer at the ESS and with instruments at short pulsed sources. In comparison to current day chopper spectrometers, VOR can offer an order of magnitude improvement in flux for equivalent energy resolutions, ΔE/E = 1-3%. Further relaxing the energy resolution enables...... VOR to gain an extra order of magnitude in flux. In addition, VOR has been optimised for repetition rate multiplication (RRM) and is therefore able to measure, in a single ESS period, 6-14 incident wavelengths, across a wavelength band of 9 Å with a novel chopper configuration that transmits all...

  12. Time of flight as a monochromatization technique for SANS

    International Nuclear Information System (INIS)

    Replacing the mechanical selector by a chopper on a small angle scattering spectrometer we obtain a monochromatization technique with a very high resolution. The description of the set up is given. An example in the polymer field is shown

  13. Design and performance of PEP dc-power systems

    International Nuclear Information System (INIS)

    The PEP Magnet Power Supply System represents a significant departure from previous technology with the goal of improved performance at lower cost. In nineteen of the magnet families around the ring, Chopper power supplies are used. The many choppers are powered from two 2 MW dc supplies, and control the average power to the various magnet loads by pulse-width modulation at a 2 kilohertz repetition rate. Each chopper utilizes SCR's for switching, and stores sufficient capacitive energy for turn-off on command. Most of the energy is recirculated, resulting in high-efficiency. The two kilohertz chopping rate allows a one kilohertz unity-gain bandwidth in the current-regulator loop, and this wide bandwidth, coupled with low drift components in the error-detection system, provides a high-performance system. The PEP system has also shown that the chopper system is economical compared to standard multi-pulse controlled-rectifier

  14. チョッパとインバータを用いた電気二重層コンデンサの電圧バランス回路<論文>

    OpenAIRE

    峯村, 明憲; 後藤, 純一; 金子, 裕良; 阿部, 茂

    2006-01-01

    Electric double layer capacitors(EDLCs) are used in series connection and the voltage balance among EDLCs is important. The voltage balance circuit with inverter has the merits of simple and low cost. However the voltage drop at diodes and transistors impedes the voltage balance operation. We have developed a new voltage balance circuit using chopper and inverter. The chopper steps up the input voltage of inverter to compensate the voltage drop. This paper describes the new voltage balance ci...

  15. Four-quadrant speed control circuit of DC servo motor using integrated voltage control method; Den`atsu sekibunchi seigyo wo mochoiita chokuryu dendoki no shishogen sokudo seigyo

    Energy Technology Data Exchange (ETDEWEB)

    Okui, H. [Osaka polytechnic College, Osaka (Japan); Irie, H. [Osaka Electro-Communication Univ., Osaka (Japan)

    1996-08-20

    The Two-Quadrant chopper is constructed by using smoothing reactor in common of the step-down chopper and step-up chopper of the DC chopper. Furthermore, since the circuit connected in bridge type by using these two groups has both of positive and negative voltage from DC source and can supplies the current from positive and negative directions for load, it is called in general as the Four-Quadrant chopper. As the Four-Quadrant chopper may supply and regenerate power, it works as power amplifier with high efficiency. In this paper, the speed control circuit of DC servo motor using Four-Quadrant integrated voltage control circuit is described. The speed control circuit is composed of simple circuits of one adder integrator and four hysteresis comparators. The Four-Quadrant speed control circuit has a DC motor speed feedback loop and a voltage feedback loop which connects with AC, it plays the Four-Quadrant speed control without current inspection. The speed control characteristics with no steady state error over four quadrants may be obtained, changing of the quadrant is smooth and transition response is rapid. 9 refs., 11 figs.

  16. TOF powder diffractometer on a reactor source

    International Nuclear Information System (INIS)

    Complete text of publication follows. The performance of time-of-flight (TOF) methods on Long Pulse Spallation Sources can be studied at a reactor source. For this purpose a prototype TOF monochromator instrument will be installed at the KFKI reactor in Budapest. The initial setup will be a powder diffractometer with a resolution of δd/d down to 2 x 10-3 at a wavelength of 1 A. The instrument uses choppers to produce neutron pulses of down to 10 μs FWHM. The optimal neutron source for a chopper instrument is a Long Pulse Spallation Source, but even on a continuous source simulations have shown that this instrument outperforms a conventional crystal monochromator powder diffractometer at high resolution. The main components of the TOF instrument are one double chopper defining the time resolution and two single choppers to select the wavelength range and to prevent frame overlap. For inelastic experiments a further chopper can be added in front of the sample. The neutron guide has a super-mirror coating and a curvature of 3500m. The total flight path is 20m and there are 24 single detectors in backscattering geometry. (author)

  17. Electro-magnetic compatibility for the IGBT based large current power supply

    International Nuclear Information System (INIS)

    The injection bump power supply of J-PARC 3-GeV RCS is composed of the assemblies that are multiple connection with the IGBT (Insulated Gate Bipolar Transistor) choppers, and it can make optionally current wave form. The switching frequency of the IGBT choppers is controlled over 48 kHz. The high-frequency noise due to the switching of the IGBT choppers has caused the damages to the control system. Then, the ground wires that connect to each power supply panel and each magnet has been changed to copper sheets and the neutral ground (ME) resistor of the IGBT assemblies have been installed. So that the voltage due to the switching noise has been decreased from 900 V to 24 V. (author)

  18. Enhanced Performance Neutron Scattering Spectroscopy by Use of Correlation Techniques

    CERN Document Server

    Mezei, F; Migliardo, F; Magazù, S

    2016-01-01

    Neutron correlation spectroscopy can exceed direct spectroscopy in the incoming beam intensity by up to two orders of magnitude at the same energy resolution. However, the propagation of the counting noise in the correlation algorithm of data reduction is disadvantageous for the lowest intensity parts of the observed spectrum. To mitigate this effect at pulsed neutron sources we propose two dimensional time-of-flight recording of each neutron detection event: with respect to both the neutron source pulses and to the rotation phase of the pseudo-random beam modulation statistical chopper. We have identified a formulation of the data reduction algorithm by matching the data processing time channel width to the inherent time resolution of this chopper, which makes the reconstruction of the direct time-of-flight spectra exact and independent of all other contributions to instrumental resolution. Two ways are proposed for most flexible choice of intensity vs. resolution without changing the statistical chopper or ...

  19. The effect of input phase modulation to a phase-sensitive optical amplifier

    CERN Document Server

    Li, Tian; Horrom, Travis; Jones, Kevin M; Lett, Paul D

    2016-01-01

    Many optical applications depend on amplitude modulating optical beams using devices such as acousto-optical modulators (AOMs) or optical choppers. Methods to add amplitude modulation (AM) often inadvertently impart phase modulation (PM) onto the light as well. While this PM is of no consequence to many phase-insensitive applications, phase-sensitive processes can be affected. Here we study the effects of input phase and amplitude modulation on the output of a quantum-noise limited phase-sensitive optical amplifier (PSA) realized in hot $^{85}$Rb vapor. We investigate the dependence of PM on AOM alignment and demonstrate a novel approach to quantifying PM by using the PSA as a diagnostic tool. We then use this method to measure the alignment-dependent PM of an optical chopper which arises due to diffraction effects as the chopper blade passes through the optical beam.

  20. RF Modeling of a Helical Kicker for Fast Chopping

    Energy Technology Data Exchange (ETDEWEB)

    Awida, Mohamed [Fermilab; Chen, Alex [Fermilab; Khabiboulline, Timergali [Fermilab; Saewert, Gregory [Fermilab; Yakovlev, Vyacheslav [Fermilab

    2015-06-01

    High intensity proton particle accelerators that supports several simultaneous physics experiments requires sharing the beam. A bunch by bunch beam chopper system located after the Radio Frequency Quadrupole (RFQ) is required in this case to structure the beam in the proper bunch format required by the several experiments. The unused beam will need to be kicked out of the beam path and is disposed in a beam dumb. In this paper, we report on the RF modeling results of a proposed helical kicker. Two beam kickers constitutes the proposed chopper. The beam sequence is formed by kicking in or out the beam bunches from the streamline. The chopper was developed for Project X Injection Experiment (PXIE).

  1. Cost to deliver sweet sorghum fermentables to a central mill

    International Nuclear Information System (INIS)

    Cost to provide readily fermentable feedstock (juice sugar) and silage for fiber conversion, up to the point fermentation begins, was determined for three harvesting systems: forage chopper, pith combine (forage chopper modified to leave a 10 percent rind-leaf fraction in the field), and Piedmont system (allows for 30 to 60 days whole-stalk storage before processing). Costs were $1.06/gal for the forage chopper system, $1.06/gal for the pith combine, and $1.16 for the Piedmont system. The most optimistic projection of ethanol yield from fiber conversion (100 gal/dry ton) was used. No opportunity was identified for a significant reduction in feedstock cost; consequently, current market value of ethanol must increase before a sweet sorghum-to-ethanol industry in the Piedmont will be economically viable

  2. An injection system for a linear accelerator

    International Nuclear Information System (INIS)

    An injection system for the Linear Accelerator is developed using the parameters of machines at the Centro Brasileiro de Pesquisas Fisicas and the Instituto Militar de Engenharia. The proposed system consists basically of a prebuncher and a chopper. The pre-buncher is used to improve the energy resolution and also to increase the accelerator target current. The chopper is used to remove from the beam the electrons that have no possibility of attaining the desired energy and that are usually lost in the walls and the cavity tube, thus producing undesirable background. Theoretical development of the chopper is performed in order to obtain its dimensions for future construction. The complete design the pre-buncher and its feed supply system and the experimental verication of its performance are also presented. It is intended to give the necessary information for the design and construction of the complete injection system proposed. (Author)

  3. A Dynamic Instrumentation Amplifier for Low-Power and Low-Noise Biopotential Acquisition

    Directory of Open Access Journals (Sweden)

    Jongpal Kim

    2016-03-01

    Full Text Available A low-power and low-noise dynamic instrumentation amplifier (IA for biopotential acquisition is presented. A dynamic IA that can reduce power consumption with a timely piecewise power-gating method, and noise level with an alternating input and chopper stabilization technique is fabricated with a 0.13-μm CMOS. Using the reconfigurable architecture of the IA, various combinations of the low-noise schemes are investigated. The combination of power gating and chopper stabilization shows a lower noise performance than the combination of power gating and alternating input switching scheme. This dynamic IA achieved a power reduction level of 50% from 10 µA to 5 µA and a noise reduction of 90% from 9.1 µVrms to 0.92 µVrms with the combination of the power gating and chopper stabilization scheme.

  4. A Dynamic Instrumentation Amplifier for Low-Power and Low-Noise Biopotential Acquisition

    Science.gov (United States)

    Kim, Jongpal; Ko, Hyoungho

    2016-01-01

    A low-power and low-noise dynamic instrumentation amplifier (IA) for biopotential acquisition is presented. A dynamic IA that can reduce power consumption with a timely piecewise power-gating method, and noise level with an alternating input and chopper stabilization technique is fabricated with a 0.13-μm CMOS. Using the reconfigurable architecture of the IA, various combinations of the low-noise schemes are investigated. The combination of power gating and chopper stabilization shows a lower noise performance than the combination of power gating and alternating input switching scheme. This dynamic IA achieved a power reduction level of 50% from 10 µA to 5 µA and a noise reduction of 90% from 9.1 µVrms to 0.92 µVrms with the combination of the power gating and chopper stabilization scheme.

  5. Characterization of the short Hydrogen Beam setup

    CERN Document Server

    Roelfs, Martin

    2015-01-01

    As part of the CERN summer student program I participated in building a short hydrogen beamline. After completion of the assembly my work consisted of characterization of the beamline. A so-called chopper is used for modulating the beam in order to distinguish the beam from the background hydrogen in the vacuum chambers. This modulation is also used to measure the velocity of the beam via a Time-of-Flight (TOF) measurement. It was found that the extracted velocity is dependent on the driving voltage of the chopper. Upstream of the chopper a pair of permanent sextupoles is used for polarizing the beam and velocity selection. The effect of the relative separation of these sextupoles on the velocity distribution was also investigated as part of this report.

  6. Straw and wood processing, including suitable drying processes

    Energy Technology Data Exchange (ETDEWEB)

    Strehler, A.; Perwanger, A.; Mitterleitner, H.; Hofstetter, E.M.

    1979-04-01

    A variety of plants designed for disintegrating and comminuting loose and compressed straw has been examined. The results obtained show that for most of the functions there are suitable plants available on the market, designed for disintegrating and comminuting individual trusses of straw. Specific energy requirements vary in function of the type of the plant. The farmhand large-truss chopper requires 1.8 kWh/dt, whereas a simple metering hopper combined with a harvester-thresher mounted chopper requires only 0.2 kWh/dt. Only by chopping it in special machines can waste wood (twigs, boughs, tree tops, barks) be brought into the shape required for utilizing cycle-saving machines and devices designed for the handling, processing, intermediate storing, sorting and dosing of fine particles into the press. A variety of choppers (brushwood choppers, culture choppers and trailed choppers) have been utilized with the aim to determine processing capacity, rate requirements and specific energy requirements, taking the degree of comminution into account. Specific energy requirements range between 0.15 kWh/dt (desintegration and little heaviness) and 2 kWh/dt (grinding, much heaviness). Technical straw drying is of little importance, since straw is generally dried in the field down to the required ultimate humidity of 14-16%. Should technical drying be necessary, conventional hay-drying plants may be used. The drying speed of chopped thinning wood (pulp chips) is relatively high as long as the particles are small as they were in the trial runs. Since wood - unlike food and feedstuff - cannot be expected to fall off in quality due to long drying cycles, the cheap process of ventilation without or with only little air heating may be used.

  7. 3.6MW Power Supply System of the 170GHz ECH&CD System in KSTAR

    OpenAIRE

    Joung Jin-Hyun; Bae Young-soon; Lee Seung-kyo; Seo Tae-won; Ahn Il-kun; Shim Eun-yong; Joung Mi

    2012-01-01

    A 3.6 MW (-66 kV/55 A) Gyrotron power supply system was developed for the 170 GHz ECH&CD gyrotron system in KSTAR. This power supply system consists of Cathode Power Supply(CPS), Anode Power Supply(APS) and Body Power Supply(BPS). The CPS is using the Pulse Step Modulation by the 32set of IGBT choppers. The respons time of Chopper is very fast. So the cathode voltaget is able to be controlled rapidly. The APS is a sort of voltage devider using zener and switch component. It was achieved 3kHz ...

  8. A 1024-channel, magnetic-drum, time analyser

    International Nuclear Information System (INIS)

    A 1024-channel time analyser with channel widths 0.2, 0.4, 0.8 and 1.6 μs (±0.1 μs) has been designed and built for work with a mechanical neutron chopper. Choice of the smallest channel width, 0.2 μs, was determined by the minimum duration of neutron pulses obtained with the mechanical chopper. A magnetic-drum memory system with a fast electrostatic temporary memory was employed. The data on the magnetic drum is recorded on an automatic register and on standard punched cards, which enable it to be handled in any computer. (author)

  9. Spin waves in antiferromagnetic FeF2

    DEFF Research Database (Denmark)

    Hutchings, M T; Rainford, B.D.; Guggenheim, H J

    1970-01-01

    Spin-wave dispersion in antiferromagnetic FeF2 has been investigated by inelastic neutron scattering using a chopper time-of-flight spectrometer. The single mode observed has a relatively flat dispersion curve rising from 53 cm-1 at the zone centre to 79 cm-1 at the zone boundary. A spin Hamilton......Spin-wave dispersion in antiferromagnetic FeF2 has been investigated by inelastic neutron scattering using a chopper time-of-flight spectrometer. The single mode observed has a relatively flat dispersion curve rising from 53 cm-1 at the zone centre to 79 cm-1 at the zone boundary. A spin...

  10. Genome sequence of Kocuria varians G6 ssolated from a slaughterhouse in Denmark

    DEFF Research Database (Denmark)

    Raghupathi, Prem Krishnan; Herschend, Jakob; Røder, Henriette Lyng;

    2016-01-01

    We report here the first draft genome sequence ofKocuria variansG6, which was isolated from a meat chopper at a small slaughterhouse in Denmark. The 2.90-Mb genome sequence consists of 95 contigs and contains 2,518 predicted protein-coding genes.......We report here the first draft genome sequence ofKocuria variansG6, which was isolated from a meat chopper at a small slaughterhouse in Denmark. The 2.90-Mb genome sequence consists of 95 contigs and contains 2,518 predicted protein-coding genes....

  11. Residual Stress Studies Using the Cairo Fourier Diffractometer Facility

    International Nuclear Information System (INIS)

    The present paper deals with residual stress studies using the Cairo Fourier diffractometer facility CFDF. The CFDF is a reverse - time of -flight (RTOF) diffractometer; applies a Fourier chopper. The measurements were performed for copper samples in order to study the residual stress after welding. The maximum modulation of the Fourier chopper during the measurements was 136 khz; leading to a time resolution half-width of about 7 μ s. It has been found from the present measurements that, the resulting diffraction spectra could be successfully used for studying the residual stress; in the wavelength range between 0.7-2.9 A degree at ∼ 0.45 % relative resolution

  12. Chopper: Efficient Algorithm for Tree Mining

    Institute of Scientific and Technical Information of China (English)

    ChenWang; Ming-ShengHong; WeiWang; Bai-LeShi

    2004-01-01

    With the development of Internet, frequent pattern mining has been extended to more complex patterns like tree mining and graph mining. Such applications arise in complex domains like bioinformatics, web mining, etc. In this paper, we present a novel algorithm, named Chopper, to discover frequent subtrees from ordered labeled trees. An extensive performance study shows that the newly developed algorithm outperforms TreeMinerV, one of the fastest methods proposed previously, in mining large databases. At the end of this paper, the potential improvement of Chopper is mentioned.

  13. A Multifunction Low-Power Preamplifier for MEMS Capacitive Microphones

    DEFF Research Database (Denmark)

    Jawed, Syed Arsalan; Nielsen, Jannik Hammel; Gottardi, Massimo;

    2009-01-01

    A multi-function two-stage chopper-stabilized preamplifier (PAMP) for MEMS capacitive microphones (MCM) is presented. The PAMP integrates digitally controllable gain, high-pass filtering and offset control, adding flexibility to the front-end readout of MCMs. The first stage of the PAMP consists of...

  14. The development of accelerator mass spectroscopy system

    Energy Technology Data Exchange (ETDEWEB)

    Mitarai, Shiro; Machida, Atsushi; Iwata, Yasunao; Tsubusaki, Yoshihiro; Tanaka, Katsuhiko; Maeda, Toyokazu; Nakajima, Takao [Kyushu Univ., Fukuoka (Japan)

    2001-02-01

    Inverse PIXE method was applied to the differentiation of Chlorine 36 and Sulfur 36. The contaminated soil from the USSR nuclear test site was measured. Terminal potential of the tandem accelerator was controlled by GVM. A new AMS system, using time-of flight method is under development. The development of beam buncher and beam chopper for the system is briefly described. (A. Yamamoto)

  15. Upgrading the Linac 400 MeV Switchyard

    International Nuclear Information System (INIS)

    This note describes changes in the 400 MeV beam transfer system from the Linac to improve the quality of the beam delivered to the Booster and to add the capability to direct beam to the MuCool Test Area (MTA). The new configuration has two pairs of pulsed dipole magnets on each side of the 400 MeV electrostatic Chopper. The smaller pair deflects vertically to replace the kick of the Chopper to send the beam to the Booster while the larger pair deflects horizontally to transfer the beam to the MTA. In this new scheme, the Chopper is uncharged while the beam is injected into the Booster such that the injection position does not rely on Chopper power supply regulation as it does now. A feature of the proposed upgrade is that no changes in the lattice functions are required in the lines to the Booster or to the Dump; once the four new magnets are installed, the switch between the old and new operating modes can be done from upstairs. The transfer to the MTA is already described in a previous note

  16. Bunch-to-bucket injection of linac beam into the Brookhaven AGS

    International Nuclear Information System (INIS)

    A new fast beam chopper has been used to study injection and capture in the AGS. The chopper is a fast beam switch with 10 ns rise and fall times that can be programmed on a bunch-by-bunch basis and is synchronized to the net accelerating voltage of the synchrotron, thus allowing bunch-to-bucket injection of the 200 MeV H- linac beam. The studies so far have concentrated on simple injection scenarios, at reduced intensity, where longitudinal effects are well separated from transverse. The evolution of the pre-bunched beam during the transition from injection to acceleration has been examined. Results have shown the importance of the detailed linac beam energy distribution. The ability to control the longitudinal emittance of the beam with the fast chopper has been used in other machine studies. This report includes a description of a measurement of the longitudinal coupling impedance of the AGS by the beam transfer function technique which utilized the control of longitudinal emittance provided by bunch-to-bucket injection. Plans for improvements to the chopper equipment are also describe. 6 refs., 4 figs

  17. Visit to FDI Technology, Saint Petersburg 4-6th December 2006 Travel Report

    CERN Document Server

    Paoluzzi, M

    2006-01-01

    The design and manufacture of the pulse amplifier required for the 3 MeV test stand chopper has been attributed to FID gmbh which is a branch of FID Technology of Saint Petersburg. This visit has been made to monitor the status of the supply.

  18. Sugarcane residue decomposition by white and brown rot microorganisms

    Science.gov (United States)

    Harvesting sugarcane with chopper harvesters results in up to 10 tons of field crop residue per acre. Residue management by soil microorganism decomposition offers numerous ecological and economical benefits to growers; however, this natural process is dependent on the biotic density, diversity and...

  19. Determination of the velocity of meteors based on sinodial modulation and frequency analysis

    NARCIS (Netherlands)

    Bettonvil, F.C.M.

    2008-01-01

    In meteor photography the velocity of meteors is generally obtained from a chopper which blocks periodically the incident light beam in front of the camera lens. In this paper I examine modulation of the meteor trail instead with a sinodial function and use frequency analysis to compute accurately t

  20. Refractive analysis of interfaces with neutron beam optimised for a white spectrum: RAINBOWS

    International Nuclear Information System (INIS)

    A new technique of refractive encoding for specular reflectometry is described that uses the full white beam without the need for choppers. Depending on the resolution, gains of many orders of flux are possible opening a new area of sub-second kinetics in interface research or allowing very small sample areas to be studied. (author)

  1. 76 FR 23854 - Reclassification of Motorcycles (Two and Three Wheeled Vehicles) in the Guide to Reporting...

    Science.gov (United States)

    2011-04-28

    ... Register's home page at: http://www.gpoaccess.gov/fr/index.html and the Government Printing Office's Web... Erickson, Highway Funding and Motor Fuels Team Leader, Office of Policy, HPPI-10, (202) 366-9235, or Adam..., cruiser, chopper, touring, dual purpose, standard, sport touring, unclad sport, sport, and super...

  2. Q-Switching in a Neodymium Laser

    Science.gov (United States)

    Holgado, Warein; Sola, Inigo J.; Jarque, Enrique Conejero; Jarabo, Sebastian; Roso, Luis

    2012-01-01

    We present a laboratory experiment for advanced undergraduate or graduate laser-related classes to study the performance of a neodymium laser. In the experiment, the student has to build the neodymium laser using an open cavity. After that, the cavity losses are modulated with an optical chopper located inside, so the Q-switching regime is…

  3. A modified time-of-flight method for precise determination of high speed ratios in molecular beams

    International Nuclear Information System (INIS)

    Time-of-flight (TOF) is a standard experimental technique for determining, among others, the speed ratio S (velocity spread) of a molecular beam. The speed ratio is a measure for the monochromaticity of the beam and an accurate determination of S is crucial for various applications, for example, for characterising chromatic aberrations in focussing experiments related to helium microscopy or for precise measurements of surface phonons and surface structures in molecular beam scattering experiments. For both of these applications, it is desirable to have as high a speed ratio as possible. Molecular beam TOF measurements are typically performed by chopping the beam using a rotating chopper with one or more slit openings. The TOF spectra are evaluated using a standard deconvolution method. However, for higher speed ratios, this method is very sensitive to errors related to the determination of the slit width and the beam diameter. The exact sensitivity depends on the beam diameter, the number of slits, the chopper radius, and the chopper rotation frequency. We present a modified method suitable for the evaluation of TOF measurements of high speed ratio beams. The modified method is based on a systematic variation of the chopper convolution parameters so that a set of independent measurements that can be fitted with an appropriate function are obtained. We show that with this modified method, it is possible to reduce the error by typically one order of magnitude compared to the standard method

  4. A modified time-of-flight method for precise determination of high speed ratios in molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    Salvador Palau, A.; Eder, S. D., E-mail: sabrina.eder@uib.no; Kaltenbacher, T.; Samelin, B.; Holst, B. [Department of Physics and Technology, University of Bergen, Allégaten 55, 5007 Bergen (Norway); Bracco, G. [Department of Physics and Technology, University of Bergen, Allégaten 55, 5007 Bergen (Norway); CNR-IMEM, Department of Physics, University of Genova, V. Dodecaneso 33, 16146 Genova (Italy)

    2016-02-15

    Time-of-flight (TOF) is a standard experimental technique for determining, among others, the speed ratio S (velocity spread) of a molecular beam. The speed ratio is a measure for the monochromaticity of the beam and an accurate determination of S is crucial for various applications, for example, for characterising chromatic aberrations in focussing experiments related to helium microscopy or for precise measurements of surface phonons and surface structures in molecular beam scattering experiments. For both of these applications, it is desirable to have as high a speed ratio as possible. Molecular beam TOF measurements are typically performed by chopping the beam using a rotating chopper with one or more slit openings. The TOF spectra are evaluated using a standard deconvolution method. However, for higher speed ratios, this method is very sensitive to errors related to the determination of the slit width and the beam diameter. The exact sensitivity depends on the beam diameter, the number of slits, the chopper radius, and the chopper rotation frequency. We present a modified method suitable for the evaluation of TOF measurements of high speed ratio beams. The modified method is based on a systematic variation of the chopper convolution parameters so that a set of independent measurements that can be fitted with an appropriate function are obtained. We show that with this modified method, it is possible to reduce the error by typically one order of magnitude compared to the standard method.

  5. Semiconductor DC amplifier AEP 1487

    International Nuclear Information System (INIS)

    A semiconductor dc amplifier has been designed with the object of achieving low drift without component selection or special temperature-balancing adjustments. Modulator and ac-amplifier techniques have been adopted in order to avoid the drifts that occur when transistors are directly coupled. The diode-ring modulator described in CREL-902 has been used as the input chopper. (author)

  6. First flux measurement in a SINQ supermirror neutron guide

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, S.; Schlumpf, N.; Bauer, G. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    On Dec. 3, 1996, the Swiss spallation neutron source SINQ was taken into operation and produced its first neutrons successfully. The neutron spectrum within one of the supermirror guides was estimated by a chopper Time-of-Flight method. The result shows a 30% higher neutron intensity at the flux maximum than expected from previous Monte-Carlo simulations. (author) 1 fig., 4 refs.

  7. FOCUS: neutron time-of-flight spectrometer at SINQ: recent progress

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, S.; Mesot, J.; Holitzner, L. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Hempelmann, R. [Saarbruecken Univ. (Germany)

    1997-09-01

    At the Swiss neutron spallation source SINQ a time-of-flight spectrometer for cold neutrons is under construction. The design foresees a Hybrid solution combining a Fermi chopper with a doubly focusing crystal monochromator. During 1996 important progress has been made concerning the main spectrometer components such as the spectrometer housing and the detector system. (author) 2 figs., 3 refs.

  8. 50 CFR 260.103 - Operations and operating procedures shall be in accordance with an effective sanitation program.

    Science.gov (United States)

    2010-10-01

    ... be in accordance with an effective sanitation program. 260.103 Section 260.103 Wildlife and Fisheries... Operations and operating procedures shall be in accordance with an effective sanitation program. (a) All..., choppers, and containers which fail to meet appropriate and adequate sanitation requirements will...

  9. Micromanipulatie: Nederlands onderdeel reuzentelescoop doorstaat alle tests

    NARCIS (Netherlands)

    Pil, A.

    2014-01-01

    De eerste Nederlandse bijdrage aan de European Extremely Large Telescope (E-ELT) is succesvol getest. Het gaat om de chopper, een zeer wendbaar spiegeltje dat is ontwikkeld door een samenwerkingsverband van universiteiten, technologische instituten en het bedrìjfsleven. Het hightech spiegeltje is ee

  10. Optimization of ''reverse time of flight'' neutron scattering devices

    International Nuclear Information System (INIS)

    The ''reverse time of flight'' (RTOF) elastic neutron scattering technique for powdered samples is briefly described. The advantages and some problems of this high resolution technique are discussed. The main task is to illustrate opportunities and solutions for an optimization of a RTOF instrument, especially for the neutron chopper device and the detector system. (orig.)

  11. PERFORMING DIAGNOSTICS ON THE SPALLATION NEUTRON SOURCE VISION BEAM LINE TO ELIMINATE HIGH VIBRATION LEVELS AND PROVIDE A SUSTAINABLE OPERATION

    Energy Technology Data Exchange (ETDEWEB)

    Van Hoy, Blake W [ORNL

    2014-01-01

    The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) provides variable energy neutrons for a variety of experiments. The neutrons proceed down beam lines to the experiment hall, which houses a variety of experiments and test articles. Each beam line has one or more neutron choppers which filter the neutron beam based on the neutron energy by using a rotating neutron absorbing material passing through the neutron beam. Excessive vibration of the Vision beam line, believed to be caused by the T0 chopper, prevented the Vision beam line from operating at full capacity. This problem had been addressed several times by rebalancing/reworking the T0 beam chopper but the problem stubbornly persisted. To determine the cause of the high vibration, dynamic testing was performed. Twenty-seven accelerometer and motor current channels of data were collected during drive up, drive down, coast down, and steady-state conditions; resonance testing and motor current signature analysis were also performed. The data was analyzed for traditional mechanical/machinery issues such as misalignment and imbalance using time series analysis, frequency domain analysis, and operating deflection shape analysis. The analysis showed that the chopper base plate was experiencing an amplified response to the excitation provided by the T0 beam chopper. The amplified response was diagnosed to be caused by higher than expected base plate flexibility, possibly due to improper grouting or loose floor anchors. Based on this diagnosis, a decision was made to dismantle the beam line chopper and remount the base plate. Neutron activation of the beam line components make modifications to the beam line especially expensive and time consuming due to the radiation handling requirements, so this decision had significant financial and schedule implications. It was found that the base plate was indeed loose because of improper grouting during its initial installation. The base plate was

  12. Fast Coordinated Control of DFIG Wind Turbine Generators for Low and High Voltage Ride-Through

    DEFF Research Database (Denmark)

    Wang, Yun; Wu, Qiuwei; Xu, Honghua; Guo, Qinglai; Sun, Hongbin

    2014-01-01

    This paper presents a fast coordinated control scheme of the rotor side converter (RSC), the DC chopper and the grid side converter (GSC) of doubly fed induction generator (DFIG) wind turbine generators (WTGs) which is to improve the low voltage ride through (LVRT) and high voltage ride through...... (HVRT) capability of the DFIG WTGs. The characteristics of DFIG WTGs under voltage sags and swells were studied focusing on the DFIG WTG stator flux and rotor voltages during the transient periods of grid voltage changes. The protection schemes of the rotor crowbar circuit and the dc chopper circuit...... were proposed considering the characteristics of the DFIG WTGs during voltage changes. The fast coordinated control of RSC and GSC were developed based on the characteristic analysis in order to realize efficient LVRT and HVRT of the DFIG WTGs. The proposed fast coordinated control schemes were...

  13. Time-of-flight analysis of charge-exchange neutral particles from the TORTUR II plasma

    International Nuclear Information System (INIS)

    A disc chopper for time-of-flight analysis of fast neutral particles was constructed for the determination of the ion energy spectrum at lower energies than can be obtained by conventional electro-magnetic analyzers. The method has been applied to the TORTUR II tokamak. The chopper and detection system are described and the measurements are presented. For the interpretation of the results of the measurements a data analysis procedure was developed. The influence of reflections of neutrals at the liner wall showed to be important in the calculations of the neutral density profile at the plasma edge. The neutral energy spectrum in the lower energy range is strongly pronounced by this effect

  14. Influence of capacitance characteristic on dye-sensitized solar cell's IPCE measurement

    Science.gov (United States)

    Tian, Hanmin; Liu, Lifei; Liu, Bin; Kui Yuan, Shi; Wang, Xiangyan; Wang, Ying; Yu, Tao; Zou, Zhigang

    2009-02-01

    It is found that the traditional monochromatic incident photon-to-electron conversion efficiency (IPCE) measurement method, such as the American Society for Testing and Materials standard (ASTM), is not suitable for measuring the IPCE of dye-sensitized solar cells (DSSCs). Experiments showed that the chopper's frequency in this method influences the measured DSSCs' IPCE value considerably, while no such impact was found in that of the Si cell. The quantitative analysis, which is based on equivalent circuits and parameter estimation, proved the existence of capacitance characteristics in DSSCs causing the fluctuation of the measured IPCE. An equivalent circuit parameter was estimated from a typical dye solar cell, which was characterized with the crystalline ingredient, the particle size and the I-V curve. The fluctuations of the measured IPCE were revealed by adjusting the chopper frequencies of one traditional IPCE measurement system. Finally, the method to obtain the real value of DSSCs' IPCE is proposed.

  15. A Particle In Cell code development for high current ion beam transport and plasma simulations

    CERN Document Server

    Joshi, N

    2016-01-01

    A simulation package employing a Particle in Cell (PIC) method is developed to study the high current beam transport and the dynamics of plasmas. This package includes subroutines those are suited for various planned projects at University of Frankfurt. In the framework of the storage ring project (F8SR) the code was written to describe the beam optics in toroidal magnetic fields. It is used to design an injection system for a ring with closed magnetic field lines. The generalized numerical model, in Cartesian coordinates is used to describe the intense ion beam transport through the chopper system in the low energy beam section of the FRANZ project. Especially for the chopper system, the Poisson equation is implemented with irregular geometries. The Particle In Cell model is further upgraded with a Monte Carlo Collision subroutine for simulation of plasma in the volume type ion source.

  16. Identification of RBC and WBC Count in Human Blood Using ARM Based Instrumentation

    Directory of Open Access Journals (Sweden)

    B.Dodda Basavanagoud

    2015-06-01

    Full Text Available The rapid growth in microelectronics and crunching RISC in the field of bio-medical sciences incorporated of soft tools to diagnose various parameters of human fluids. Conventional method of blood sample analysis makes use of laboratory technique of titration, which is operator-dependent and results in lot of errors depending on the skill of the technician. In order to eliminate the human errors involved in the conventional method, in this paper an attempt has been made to present a capillary centrifuge technique driven by high speed DC motor fed by Morgan chopper and controlled by powerful ARM processor. It results in accurate analysis of the blood samples. The various techniques involved in accurate sensing of speed using timer and generation of firing pulses to thyristor in the Morgan chopper is judiciously achieved. This paper clearly brings out the advantages of the proposed blood measurement technique which effectively gives blood analysis faster and at a low cost.

  17. Modeling and simulation of a solar power source at 3kW for a clean energy without pollution

    Directory of Open Access Journals (Sweden)

    Louzazni M.

    2014-04-01

    Full Text Available The air pollution was much worse, and it became necessary to replace the fossil energy sources by the renewable energies. The causes are related to reserves that can be exhausted, to pollution and their impacts on the environment. Production of toxic gases from the combustion of coal for the effect of increasing the temperature of the earth. Solar energy is a clean and inexhaustible excellent alternative. We propose a modeling and simulation of a solar system consists of a photovoltaic generator (PVG, a boost chopper, to supply a telecommunications relay station (BTS, According to the load characteristics (I = 60A, V = 48V DC (3 kW. A stage adaptation composed of this chopper controlled by a PWM controller (Pulse Width Modulation is used to control the optimal operating point (MPPT and optimize system performance using Matlab / Simulink.

  18. Construction of polarized inelastic neutron spectrometer in J-PARC

    International Nuclear Information System (INIS)

    The instrumental design of the Polarization Analysis Neutron Spectrometer with Correlation Method (POLANO) is almost ready for its construction, although some discussion on the design still remains. POLANO is a new inelastic neutron spectrometer in the Japan Proton Accelerator Research Complex (J-PARC) utilizing polarized neutrons for comprehensive materials research, focusing on the use of quasi-elastic and inelastic scattering techniques. For instrumental construction, the basic shield design is complete and the shielding capability against radiation has been assessed. Additionally, the designs of the beam transport section using 4 Qc supermirror guide tube are almost complete. Also, detecting section and a large vacuum chamber is now under designing. The development of polarization and chopper devices are the key to the success for the very first application of polarization analysis to inelastic scattering at spallation neutron source. High performance Fermi and T0 choppers are now under manufacturing.

  19. Status of intense permanent magnet proton source for China-accelerator driven sub-critical system Linac

    International Nuclear Information System (INIS)

    Two compact intense 2.45 GHz permanent magnet proton sources and their corresponding low energy beam transport (LEBT) system were developed successfully for China accelerator driven sub-critical system in 2014. Both the proton sources operate at 35 kV potential. The beams extracted from the ion source are transported by the LEBT, which is composed of two identical solenoids, to the 2.1 MeV Radio-Frequency Quadrupole (RFQ). In order to ensure the safety of the superconducting cavities during commissioning, an electrostatic-chopper has been designed and installed in the LEBT line that can chop the continuous wave beam into a pulsed one. The minimum width of the pulse is less than 10 μs and the fall/rise time of the chopper is about 20 ns. The performance of the proton source and the LEBT, such as beam current, beam profile, emittance and the impact to RFQ injection will be presented

  20. A reverse time of flight analyzer facility at the ETRR-1 reactor

    International Nuclear Information System (INIS)

    The present work deals both with the theory and performance of a reverse-time-of-flight (RTOF) analyzer designed to analyze pulses emitted from a fourier chopper recently put into operation at the ETRR-1 reactor. The RTOF analyze was found to be adequate for use with pick up pulses from the fourier chopper which operates following a frequency window suitable for rotation rates from 0-9000 rpm; synchronically with neutron pulses from a 6 Li glass detector set at time focusing geometry for scattering angle 20=90 degree. It was possible, with the present RTOF analyzer to obtain diffraction patterns at neutron wavelength range between 1 - 4 A within a resolution = 0.5%. 8 FIGS

  1. A Reverse Time of Flight Analyzer at the ETRR-1 Reactor

    International Nuclear Information System (INIS)

    The present work deals both with the theory and performance of a reverse-time of-flight (Roof) analyzer designed to analyze pulses emitted from a Fourier chopper; recently put into operation at the ETRR-1 reactor. The RTOF analyzer was found to be adequate for use with pick up pulses from the Fourier chopper which operates following a frequency window suitable for rotation rates from 0-9000 rpm; synchronically with neutron pulses from a 6Li glass detector set at time focusing geometry for scattering angle 2 theta = 90 degree. It was possible, with the present RTOF analyzer, to obtain diffraction patterns, with reasonable accuracy at D values between 0.7-2.9 A and within short measuring time

  2. Digitized detection of gamma-ray signals concentrated in narrow time windows for transient positron annihilation lifetime spectroscopy

    International Nuclear Information System (INIS)

    A pulsed slow-positron beam generated by an electron linear accelerator was directly used for positron annihilation lifetime spectroscopy without any positron storage devices. A waveform digitizer was introduced to simultaneously capture multiple gamma-ray signals originating from positron annihilation events during a single accelerator pulse. The positron pulse was chopped and bunched with the chopper signals also sent to the waveform digitizer. Time differences between the annihilation gamma-ray and chopper peaks were calculated and accumulated as lifetime spectra in a computer. The developed technique indicated that positron annihilation lifetime spectroscopy can be performed in a 20 μs time window at a pulse repetition rate synchronous with the linear accelerator. Lifetime spectra of a Kapton sheet and a thermally grown SiO2 layer on Si were successfully measured. Synchronization of positron lifetime measurements with pulsed ion irradiation was demonstrated by this technique

  3. Time-of-flight measurements in atomic beam devices using adiabatic high frequency transitions and sextupole magnets

    International Nuclear Information System (INIS)

    Atomic beam devices are frequently equipped with sextupole magnets to focus the beam or to act as spin filters in combination with RF-transitions for manipulating the hyperfine population within the atomic beam. A useful tool for the analysis of sextupole systems, the application of time-of-flight (TOF) measurements is presented. TOF measurements are enabled without mechanical beam chopper by utilizing adiabatic radio frequency transitions to select atoms within a certain time interval. This method is especially interesting for the use in atomic beam devices that are already equipped with RF-transitions and sextupole magnets and where space limitations or the required quality of the vacuum do not allow the installation of a mechanical chopper. The measurements presented here were performed with the atomic beam polarimeter of the HERMES polarized deuterium target and the results have been used to optimize the sextupole system of the polarimeter

  4. The CEBAF injector RF distribution and bunch-length measurement system

    International Nuclear Information System (INIS)

    The CEBAF injector includes 22 RF control modules which require an intermediate frequency (IF) of 70 MHz and a local oscillator (LO) frequency of 1427 MHz. A STAR network distributes the signals over coaxial cables that are of equal length so that all systems see the same phase drifts due to ambient temperature changes. To obtain the signal levels required by the individual RF control modules, amplifiers are used in both the LO and IF distribution. Temperature-dependent phase drifts associated with the amplifiers are minimized by a phase-lock loop around each amplifier. In addition to the frequency distribution, an automated beam bunch-length measurement is incorporated in the chopper cavities' intermediate frequency. This allows the phase of the chopper cavities to be modulated and bunch-length measurements to be performed on the electron beam downstream. (Author) 5 refs., 4 figs

  5. Monte-Carlo-simulations of a high resolution neutron TOF instrument at the FRM II

    International Nuclear Information System (INIS)

    It is proposed to build a flexible, high resolution time of flight diffractometer and spectrometer at the new reactor FRM II of the Technische Universitaet Muenchen. To optimize the layout of individual components and to estimate the performance of the entire instrument, analytical calculations and Monte-Carlo-simulations have been carried out mainly with 'McStas', programmed by RISO, Denmark. MC-simulation routines for neutron devices like curved guides, disc- and Fermi choppers have been added. The influence of diverging and curved guides in neutron phase space has been developed and are shown. Line shapes and widths of neutron pulses have been studied for disc- and Fermi choppers. Analytical calculations and MC-simulation results are discussed dependent on slit forms and beam asymmetries. (author)

  6. Status of intense permanent magnet proton source for China-accelerator driven sub-critical system Linac

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Q., E-mail: wuq@impcas.ac.cn; Ma, H. Y.; Yang, Y.; Sun, L. T.; Zhang, X. Z.; Zhang, Z. M.; Zhao, H. Y.; He, Y.; Zhao, H. W. [Institute of Modern Physics (IMP), Chinese Academy of Sciences, Lanzhou 730000 (China)

    2016-02-15

    Two compact intense 2.45 GHz permanent magnet proton sources and their corresponding low energy beam transport (LEBT) system were developed successfully for China accelerator driven sub-critical system in 2014. Both the proton sources operate at 35 kV potential. The beams extracted from the ion source are transported by the LEBT, which is composed of two identical solenoids, to the 2.1 MeV Radio-Frequency Quadrupole (RFQ). In order to ensure the safety of the superconducting cavities during commissioning, an electrostatic-chopper has been designed and installed in the LEBT line that can chop the continuous wave beam into a pulsed one. The minimum width of the pulse is less than 10 μs and the fall/rise time of the chopper is about 20 ns. The performance of the proton source and the LEBT, such as beam current, beam profile, emittance and the impact to RFQ injection will be presented.

  7. Quadrupole slow-wave deflector for chopping charged-particle beams

    International Nuclear Information System (INIS)

    We introduce a new beam-deflector design for chopping low-energy charged-particle beams, the quadrupole slow-wave deflector (QSWD). This new design integrates the traveling-wave beam deflector, an electrostatic quadrupole, and clearing electrodes into a single compact structure. The four-electrode device performs ion clearing and linear focusing in the quadrupole (or transmit) mode, and also serves as a fast kicker in the deflecting mode. A QSWD operates with a constantly sustained electric field that sweeps off the ions and electrons produced by beam-gas scattering. Thus, a chopper using the QSWD can avoid beam neutralization with consequent emittance growth due to the beam-plasma interaction. We shall present the theoretical studies and the design considerations of the quadrupole deflector. A conceptual design of the chopper for a proposed Long Pulse Spallation Neutron Source (LPSS) at Los Alamos will be given as an example. (author)

  8. Rotating crystal cube as a variable shutter for use with synchrotron radiation

    International Nuclear Information System (INIS)

    A beam chopper together with the temporal structure of x-rays emitted by a synchrotrons storage ring can be utilized to generate x-ray bursts of variable length and time separation. A Si cube, cut for diffraction from the (220) planes, was mounted to a low-speed motor to produce a beam chopper based upon the Darwin width of the crystal. An x-ray pulse, consisting of an envelope of individual pulses characterizing the loading pattern of the storage ring, was transmitted. The width of the transmitted pulse and the time between pulses was varied by varying the rotation frequency of the Si cube. Pulses as short as ∼75 ps or as long as ∼4 micros were transmitted with pulse separation spanning from 4 ms to 167 ms

  9. Correcting beam monitor and diffraction data for chopped delayed neutron backgrounds

    International Nuclear Information System (INIS)

    Delayed neutron choppers in pulsed source neutron beams serve to reduce the background caused by delayed neutrons in pulsed source instruments. The authors analyze the effect of a drum chopper placed in an incident pulsed beam which contains delayed neutrons and compute its influence on the detector counting rate. Expressions are found for the time and wavelength dependence of the counting rates for both prompt and delayed neutrons, in both monitor and scattered neutron detectors. On the basis of these results, they suggest an exact, random-phasing method for determining the delayed neutron background for use in measuring the delayed neutron counting rate, and propose a rapidly convergent iterative scheme for computing the correction from normally measured data. They report measurements which confirm the analysis. 5 refs., 7 figs

  10. Fast Coordinated Control of DFIG Wind Turbine Generators for Low and High Voltage Ride-Through

    Directory of Open Access Journals (Sweden)

    Yun Wang

    2014-06-01

    Full Text Available This paper presents a fast coordinated control scheme of the rotor side converter (RSC, the Direct Current (DC chopper and the grid side converter (GSC of doubly fed induction generator (DFIG wind turbine generators (WTGs to improve the low voltage ride through (LVRT and high voltage ride through (HVRT capability of the DFIG WTGs. The characteristics of DFIG WTGs under voltage sags and swells were studied focusing on the DFIG WTG stator flux and rotor voltages during the transient periods of grid voltage changes. The protection schemes of the rotor crowbar circuit and the DC chopper circuit were proposed considering the characteristics of the DFIG WTGs during voltage changes. The fast coordinated control of RSC and GSC were developed based on the characteristic analysis in order to realize efficient LVRT and HVRT of the DFIG WTGs. The proposed fast coordinated control schemes were verified by time domain simulations using Matlab-Simulink.

  11. 3.6MW Power Supply System of the 170GHz ECH&CD System in KSTAR

    Science.gov (United States)

    Shim, Eun-yong; Ahn, Il-kun; Seo, Tae-won; Lee, Seung-kyo; Bae, Young-soon; Joung, Jin-Hyun; Joung, Mi

    2012-09-01

    A 3.6 MW (-66 kV/55 A) Gyrotron power supply system was developed for the 170 GHz ECH&CD gyrotron system in KSTAR. This power supply system consists of Cathode Power Supply(CPS), Anode Power Supply(APS) and Body Power Supply(BPS). The CPS is using the Pulse Step Modulation by the 32set of IGBT choppers. The respons time of Chopper is very fast. So the cathode voltaget is able to be controlled rapidly. The APS is a sort of voltage devider using zener and switch component. It was achieved 3kHz modulation operation. The BPS is combined the commercial power supply and special high voltage switches. It is very simple topology but 5kHz modulation was accomplished easily. Theses power supply system were installed and commissioned successfully in 2011. This paper presents the topology of the each power supply and test result for 170 GHz gyrotron in KSTAR.

  12. Energetic Macroscopic Representation Applied To An Electrical Urban Transport System

    Directory of Open Access Journals (Sweden)

    Claudia POPESCU

    2002-12-01

    Full Text Available An energetic description of the electric transport urban system ASTRAIK 415T is proposed according to a specific formalism. This is used to simulate the trolleybus system, equipped with a chopper and a direct current series motor. DC series motor is still used for trolleybus and metro, driven by a GTO or IGBT chopper µC-controlled, which allows the implementation of command algorithms. From this synthetically representation a complete model of the electromechanical system was implemented using the Matlab-Simulink simulation environment. A control structure was deduced through model inversion. This will allow the study of the transient phenomena and the implementation of different command laws taking into account the minimum energy losses

  13. Operation of the rf controls in the CEBAF injector

    International Nuclear Information System (INIS)

    The CEBAF injector has produced its first relativistic beam with two superconducting cavities. Six RF control modules are used to control amplitude and phase in the chopper cavities, the buncher, the capture section, and the two superconducting cavities. In this paper the required stability and actual performance of the modules are discussed. For the superconducting cavity control, performance is consistent with energy stability of ∼10-4

  14. Analysis Of Single Phase Matrix Converter

    OpenAIRE

    Divya Ahirrao; Bhagyashri Gaware

    2014-01-01

    This paper presents concept of single phase matrix converter. Single phase matrix converter (SPMC) performs a function such as frequency changer, rectifier, inverter; chopper. This reduces the need for new converter hardware. Pulse width modulation (SPWM) techniques are used to calculate the switch duty ratio to synthesis the output. The simulation of converter is carried out in MATLAB/SIMULINK. Hardware design is obtained using readily available IC‟s and other components. Thi...

  15. Kecernaan Serat Kasar Dan Protein Kasar Ransum Yang Mengandung Pelepah Daun Kelapa Sawit Dengan Perlakuan Fisik, Biologi, Kimia Dan Kombinasinya Pada Domba

    OpenAIRE

    Gultom, Edidis Periasantana

    2016-01-01

    This research was conducted at the laboratory of anymal biology, departement of animal husbandry, faculty of agriculture, University of Sumatera Utara, from june – august 2013. This research used a completely randomized design (CRD) with four treatments and four replications, using 16local sheep ram with an average initial body weight of 10 + 1,16 kg. The treatments consist PO: OPF treated by physical (chopper), P1: OPF treated by biology (physical + Aspergillus niger), P2: OPF treated by che...

  16. Design and Development of DSP Controlled Filament Power Supply for 1 MW, 352.2 MHz Klystron

    OpenAIRE

    Akhilesh Tripathi# , M. K. Badapanda and P. R. Hannurkar

    2013-01-01

    A digitally controlled current regulated 20 V, 25 A dc power supply employing IGBT based chopper is developed as the filament power supply for 1 MW, 352.2 MHz, Thales make TH 2089 klystron amplifier. The filament of this klystron is floating at cathode voltage of -100 kV dc, hence this power supply is kept on a floated platform and isolated through a suitable HV isolation transformer. Control and protection of this power supply is implemented through Texas make ...

  17. Implementation of Brushed DC Motor Control in LabVIEW FPGA

    OpenAIRE

    K. Lamár; A. G. Kocsis

    2013-01-01

    The paper introduces the fundamentals of motor control. It explains the basic equations and introduces the control diagram of the brushed DC motor. It introduces the four quadrant DC chopper circuit and the basic methods to operate it. After that, it explains the fundamentals of the current control of DC motors and its two basic methods: the pulse width modulation and the hysteresis current control. Finally it gives a short example of the practical implementation of the hysteresis current con...

  18. Speed Control of Separately Excited DC Motor

    OpenAIRE

    Moleykutty George

    2008-01-01

    This paper proposes the speed control of a separately excited dc motor (SEDM) by varying armature voltage. The novelty of this paper lies in the application of nonlinear autoregressive-moving average (NARMA)L2 controller for the speed control of SEDM. This paper also discusses speed control of a SEDM using chopper circuit. The performance of the proposed system has been compared with the traditional one using conventional controllers. The entire system has been modeled using MATLAB 7.0 toolbo...

  19. Fast Coordinated Control of DFIG Wind Turbine Generators for Low and High Voltage Ride-Through

    OpenAIRE

    Yun Wang; Qiuwei Wu; Honghua Xu; Qinglai Guo; Hongbin Sun

    2014-01-01

    This paper presents a fast coordinated control scheme of the rotor side converter (RSC), the Direct Current (DC) chopper and the grid side converter (GSC) of doubly fed induction generator (DFIG) wind turbine generators (WTGs) to improve the low voltage ride through (LVRT) and high voltage ride through (HVRT) capability of the DFIG WTGs. The characteristics of DFIG WTGs under voltage sags and swells were studied focusing on the DFIG WTG stator flux and rotor voltages during the transient peri...

  20. Fermentation and epiphytic microflora dynamics in sugar cane silage

    OpenAIRE

    Pedroso André de Faria; Nussio Luiz Gustavo; Paziani Solidete de Fátima; Loures Daniele Rebouças Santana; Igarasi Mauricio Scoton; Coelho Rodrigo Michelini; Packer Irineu Humberto; Horii Jorge; Gomes Luiz Humberto

    2005-01-01

    Sugar cane silages are characterized by extensive yeast activity, alcohol production and great dry matter - DM - losses. Better knowledge of the fermentation process is fundamental to the development of efficient ensilage techniques for this forage. This study evaluates temporal changes in chemical composition, DM losses and epiphytic microflora in sugar cane silage. Mature sugar cane, variety RB835486 (12 months of vegetative growth), was hand harvested, processed in a stationary chopper and...

  1. Verschiedene Gründüngerpflanzen – Anbaueignung und Unkrautunterdrückung im Direktsaatsystem vor Winterweizen

    OpenAIRE

    Stadler, Marina; Zihlmann, Urs; Scherrer, Caroline; Jossi, Werner; Streit, Bernhard

    2009-01-01

    In a small-plot field trial 33 green manure plants (GM) were examined for their ability to suppress weeds in a no-tillage system. A roll-chopper was used to suppress the GMs before seeding winter wheat. The success of this organic method to control GMs was compared to the standard method using a non selective herbicide. Species of the group brassicaceae, monocotyles and plant mixtures covered the soil faster, produced more biomass and suppressed weeds more efficiently than spec...

  2. Comparative Study of Multicarrier PWM Techniques for a Modular Multilevel Inverter

    OpenAIRE

    Rajan, M S; R. Seyezhai

    2014-01-01

    This paper presents the simulation of three phase five-level modular multilevel cascade inverter based on double-star chopper-cell (DSCC). The multicarrier PWM techniques such as Phase disposition PWM (PDPWM), Phase opposition disposition PWM (PODPWM), Alternate phase opposition disposition PWM (APODPWM), and Phase shift PWM (PSPWM) is employed and a comparative study is done based on the spectral quality of the load voltage and load current waveforms. Simulation has been carried out for vari...

  3. Bulanık Kazanç Ayarlamalı Nonlineer PI Kontrolörün Kalıcı Mıknatıslı Doğru Akım Motor-Dinamo Sistemine Uygulanması = Applying the Fuzzy Gain Scheduling Nonlinear PI Controller to Permanent Magnet Direct Current Motor - Dynamo System

    OpenAIRE

    Kamil Burak DALCI

    2004-01-01

    This paper describes the realization of a fuzzy gain scheduling scheme of a PI controller using a RISC microcontroller. Fuzzy rules and reasoning are utilised on-line to determine the PI controller parameters based on the error signal and its first difference. The Fuzzy control algorithm is implemented in the RISC microcontroller to regulate the speed of a permanent magnet DC motor (PMDC) and works on-line. The microcontroller directly tunes the motor speed with a chopper converter which cha...

  4. The medium energy transfer spectrometer; a crystal monochromator design

    International Nuclear Information System (INIS)

    The report is in sections, entitled: introduction; scientific specification; monochromators (single crystal geometry; double crystal geometry; choice of crystals (copper)); an initial mechanical design; the resolution of the MET crystal monochromator (collimation; resolution calculations; comparison with other spectrometers); specifications of the MET (crystal) spectrometer; suppression of high orders; intensity calculations (intensity comparisons between crystal and chopper versions of (MET); neutron momentum transfer resolution. (U.K.)

  5. Afterglow mode and the new Micro Pulsed Beam mode applied to an ECR Ion Source

    OpenAIRE

    Maunoury, Laurent; Adoui, Lamri; Grandin, Jean-Pierre; Huber, Bernd; Lamour, Emily; Leherissier, Patrick; Noury, Fabien; Pacquet, Jean-Yves; Prigent, Christophe; Rozet, Jean-Pierre; Vernhet, Dominique

    2008-01-01

    An increasing number of experiments in the field of low energy ion physics ( µA) a pulsed beam chopper, installed downstream to the analyzing dipole, is used. For low-intensity beams (< 100 nA) the ion intensity delivered during the pulse may be increased by operating the ECR discharge in the afterglow mode [1]. This method gives satisfactory results (ie average current during the beam pulse is h...

  6. Present and future beam tube experiments at the 250 kW TRIGA Mark II reactor Wien

    International Nuclear Information System (INIS)

    The four beam tubes and the thermal column at the TRIGA reactor Wien were well used in the reporting period. Since the thermal column is used as a gamma source for different irradiation experiments and as a neutron source for radiography, the other facilities are mainly used for neutron spectroscopy experiments: polarized neutrons, neutron interferometry, small angle scattering and neutron choppers, In the piercing beam tube a fast rabbit system is installed which is mainly used for high precision activation analysis. (author)

  7. Processing and recycling of polymer- coated waste paper

    OpenAIRE

    Kurta, M.; Voronych, O.

    2012-01-01

    The technology of recycling polymer coated wall -paper waste was developed. Design included the first stage of shredding waste paper with chopper -disk and milling. During the second stage, shredding was carried out on drum mills with separation of cellulose fiber from polymer coating. The third stage consisted of separation of two fractions: polymer coating and cellulose fiber. As a result of this process, 50 -95% of pure cellulose and 5 -50% solid polymer waste were obtained. Obtained cell...

  8. Computer-based design technique of controllers for the plasma vertical stabilization

    International Nuclear Information System (INIS)

    A procedure for designing the parameters of a feedback controller for the plasma vertical stabilization is described. The procedure is based on a reduced order model for the plasma dynamics and a computer aided parameter optimization technique, which allows to reach a compromise between power requirements and good performance of the control system. An analysis model for a control scheme including a chopper-type amplifier is then described. (author)

  9. Intelligent Microstepping System for Bipolar Stepper Motor Control with Step and Direction Interface

    OpenAIRE

    Alexandru Morar; Lucian Dăscălescu

    2010-01-01

    The paper presents a intelligent system for stepper motor control in a microstepping mode, which was designed and performed with a specialized integrated circuit (L292), made by SGS-THOMSON Microelectronics Company. With an interface and an adequate software, L292 circuit can be used as a chopper in 2 or 4 quadrant. The microstepping control system improves the positioning accuracy and eliminates low speed ripple and resonance effects in a stepper motor electric drive. The same microstepping ...

  10. "Resonance" phenomena in thermal diffusion processes in two-layer structures

    OpenAIRE

    Gurevich, Yu. G.; Logvinov, G. N.; Munoz-Aguirre, N.; Martinez-Perez, L.

    2002-01-01

    The dependence on chopper frequency of the effective thermal diffusivity and effective thermal conductivity in photoacoustic experiments is discussed. The theoretical model of a two-layer structure at rear-surface illumination in the high frequency limit is considered. It is shown that the effective thermal diffusivity presents ``resonance'' while the effective thermal conductivity sharply changes its magnitude and sign. Such ``resonant'' behavior strongly depends on the surface thermal condu...

  11. Quasielastic neutron scattering study on polymer nanocomposites

    International Nuclear Information System (INIS)

    By using a quasielastic neutron scattering technique (disk-chopper-type spectrometer AMATERAS at J-PARC), we have investigated the microscopic dynamics of polybutadiene (PB) in which silica particles were embedded. The experimental results gave us both a damped vibration mode of PB and jumped diffusion motion of the segments. It was found that these dynamical features remain unaffected by the presence of the silica particle, while the residence time of the jumped diffusion motion becomes longer at the high filler loading.

  12. Performance Analysis of Savonius Rotor Based Hydropower Generation Scheme with Electronic Load Controller

    OpenAIRE

    Rajen Pudur; Sarsing Gao

    2016-01-01

    This paper describes the performance of electronic load controller (ELC) of asynchronous generator (AG) coupled to an uncontrolled Savonius turbine and variable water velocity. An AC-DC-AC converter with a dc link capacitor is employed to maintain the required frequency. The ELC which is feeding a resistive dump load is connected in parallel with the generating system and the power consumption is varied through the duty cycle of the chopper. Gate triggering of ELC is accomplished through sinu...

  13. Development of MOS-FET based Marx generator with self-proved gate power

    International Nuclear Information System (INIS)

    New MOS-FET based Marx generator is described. An electric gate power for the MOS-FET is provided from the Marx main circuit itself. Four-stage Marx generator generates -12kV of the output voltage. The Marx Generator is successfully used to drive an Einzel lens chopper to generate a short pulsed ion beam for a KEK digital accelerator. (author)

  14. High speed switching circuits for future accelerators

    International Nuclear Information System (INIS)

    We are developing a Klystron modulator power source for ILC (International Linear Collider). This modulator needs 120kV(±0.5%), 140A, 5pps, with a pulse width of 1.7ms, aiming for a compact, low-cost and reliable design. To meet these requirements, we propose solid state, chopper controlled pulsed power generator using Marx-topology. This paper shows circuit simulation and prototype experimental results. (author)

  15. A versatile microcomputer interface and peripheral devices: An application in deuterium lamp background correction graphite furnace atomic absorption spectrometry

    Science.gov (United States)

    Gökmen, A.; Yalcin, S.

    1992-01-01

    A versatile interface card for Apple IIe computer and various peripheral devices are designed to control instruments which generates transient signals like in graphite furnace atomic spectrometer. The interface card consists of a multiplexed analog-to-digital converter, a digital-to-analog converter, and a timer/counter chip. The timer/counter chip with 16 built-in registers can be programmed in many modes which provides a time base for real-time measurements. A stepper motor runs under the control of timer/counter chip independent of computer. A light chopper connected to the stepper motor is controlled easily by computer. A dual high-voltage switch can modulate dc light sources under computer control. This system is applied to D2-lamp background correction graphite furnace atomic absorption spectrometer. The D2 lamp is chopped by a mechanical chopper driven by a stepper motor and a hollow cathode lamp is modulated electronically. The data acquisition program is written in machine language and synchronization between light sources and computer is provided by chopper position signal through the interrupts. A sampling rate of 16 during a signal period at 50-Hz chopping frequency is found to be the optimum value. A large number of data collected during atomization period is compressed in machine code. This saved storage space and analysis time.

  16. Simulation and Implementation of an Embedded Hybrid Fuzzy Trained Artificial Neural Network Controller for Different DC Motor

    Directory of Open Access Journals (Sweden)

    M.Muruganandam

    2014-03-01

    Full Text Available In this article, the speed of the DC motor is controlled by Hybrid Fuzzy-Neuro controller (FNC. The Hybrid Fuzzy-Neuro controller is designed and tested for different types of DC motors like DC separately excited motor and DC series motor. The motor is fed by DC-DC buck converter (DC chopper. The system has two loops of inner current controller loop and outer Fuzzy-Neuro based speed controller loop. The speed controller gives the duty cycle to generate the PWM signal for the control of chopper. There by the DC chopper controls the speed of the DC motor to the set value. The training data for training the FNC is acquired from Fuzzy Logic Controller (FLC. The performances of FNC are analyzed in respect of load variation and speed variation using MATLAB/Simulink. The FNC reduces the peak overshoot, settling time and steady state error of the DC motor. It is found that the FNC can have better control compared with FLC. This system is implemented in a NXP 80C51 family Microcontroller (P89V51RD2BN based Embedded System.

  17. Straight and chopped dc performance data for a General Electric 5BT 2366C10 motor and an EV-1 controller

    Science.gov (United States)

    Edie, P. C.

    1981-01-01

    Performance data on the General Electric 5BT 2366C10 series wound dc motor and EV-1 Chopper Controller is supplied for the electric vehicle manufacturer. Data is provided for both straight and chopped dc input to the motor, at 2 motor temperature levels. Testing was done at 6 voltage increments to the motor, and 2 voltage increments to the controller. Data results are presented in both tabular and graphical forms. Tabular information includes motor voltage and current input data, motor speed and torque output data, power data and temperature data. Graphical information includes torque-speed, motor power output-speed, torque-current, and efficiency-speed plots under the various operating conditions. The data resulting from this testing shows the speed-torque plots to have the most variance with operating temperature. The maximum motor efficiency is between 86% and 87%, regardless of temperature or mode of operation. When the chopper is utilized, maximum motor efficiency occurs when the chopper duty cycle approaches 100%.

  18. Design of DC Motor Driver as a Control System Actuator for Electron Source in Electron Beam Machine

    International Nuclear Information System (INIS)

    A DC motor driver has been contracted using chopper DC circuit. The DC motor driver consists of an inverting amplifier, a comparator, and a DC chopper unit. The DC chopper circuit is based on H hybrid circuit, so that the polarization and angular velocity of DC motor can be regulated similar with the polarization and value of input signal. The result showed, that the DC motor driver circuit can be used as actuator on the electron source of electron beam machine. The maximum (duty cycle value = 1/2) angular velocity has same value for 10-1 - 10-2 Hertz oscillator frequency range. The increase of angular velocity will be proportional to the oscillator frequency at the constant duty cycle. If this characteristic is related with respond time of the control system, so the control system respond time is dependence on oscillator frequency being used. The use of control system with PC can be realized, because the input signal use low voltage, where the measurement shows that it has 3 - 10 Volt voltage range. (author)

  19. PC based speed control of dc motor using fuzzy logic controller

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, S.K.; Kanphade, R.D.; Lavekar, K.P.

    1998-07-01

    The dc motor is extensively used as constant speed drive in textile mills, paper mills, printing press, etc.. If the load and supply voltage are time varying, the speed will be changed. Since last few decades the conventional PID controllers are used to maintain the constant speed by controlling the duty ratio of Chopper. Generally, four quadrant chopper is used for regenerative braking and reverse motoring operation. Fuzzy Logic is newly introduced in control system. Fuzzy Control is based on Fuzzy Logic, a logical system which is too much closer in spirit to human thinking and natural language. The Fuzzy Logic Controller (FLC) provides a linguistic control strategy based on knowledge base of the system. Firstly, the machine is started very smoothly from zero to reference speed in the proposed scheme by increasing the duty ratio. Then change and rate of change of speed (dN, dN/dt), change and rate of change input voltage (dV, dV/dt) and load current are input to FLC. The new value of duty ratio is determined from the Fuzzy rule base and defuzzification method. The chopper will be 'ON' according to new duty ratio to maintain the constant speed. The dynamic and steady state performance of the proposed system is better than conventional control system. In this paper mathematical simulation and experimental implementation are carried out to investigate the drive performance.

  20. Initial Emittance Measurements of the Fermilab Linac Beam Using the MTA Beamline

    CERN Document Server

    Johnstone, C

    2012-01-01

    The MTA beam line has been specifically designed to facilitate measurements of the Fermilab Linac beam emittance and properties utilizing a long, 10m, element-free straight. Linac beam is extracted downstream of the 400-MeV electrostatic chopper located in the Booster injection line. This chopper cannot be utilized for MTA beam, and therefore the entire Linac beam pulse is directed into the MTA beamline. Pulse length manipulation is provided by the 750-keV electrostatic chopper at the upstream end of the Linac and, using this device, beam can be delivered from 8 {\\mu}sec up to the full 50 {\\mu}sec Linac pulse length. The 10 m emittance measurement straight exploits and begins at the 12' shield wall that separates the MTA Experimental Hall and beamline stub from the Linac enclosure. A quadrupole triplet has been installed upstream of the shield wall in order to focus a large, 1.5-2" (~95% width) beam through the shield wall and onto a profile monitor located at the exit of the shielding. Another profile monito...

  1. A 160 μW 8-Channel Active Electrode System for EEG Monitoring.

    Science.gov (United States)

    Jiawei Xu; Yazicioglu, R F; Grundlehner, B; Harpe, P; Makinwa, K A A; Van Hoof, C

    2011-12-01

    This paper presents an active electrode system for gel-free biopotential EEG signal acquisition. The system consists of front-end chopper amplifiers and a back-end common-mode feedback (CMFB) circuit. The front-end AC-coupled chopper amplifier employs input impedance boosting and digitally-assisted offset trimming. The former increases the input impedance of the active electrode to 2 GΩ at 1 Hz and the latter limits the chopping induced output ripple and residual offset to 2 mV and 20 mV, respectively. Thanks to chopper stabilization, the active electrode achieves 0.8 μVrms (0.5-100 Hz) input referred noise. The use of a back-end CMFB circuit further improves the CMRR of the active electrode readout to 82 dB at 50 Hz. Both front-end and back-end circuits are implemented in a 0.18 μm CMOS process and the total current consumption of an 8-channel readout system is 88 μA from 1.8 V supply. EEG measurements using the proposed active electrode system demonstrate its benefits compared to passive electrode systems, namely reduced sensitivity to cable motion artifacts and mains interference. PMID:23852553

  2. A 97 dB dynamic range CSA-based readout circuit with analog temperature compensation for MEMS capacitive sensors

    International Nuclear Information System (INIS)

    This paper presents a charge-sensitive-amplifier (CSA) based readout circuit for capacitive microelectro-mechanical-system (MEMS) sensors. A continuous-time (CT) readout structure using the chopper technique is adopted to cancel the low frequency noise and improve the resolution of the readout circuits. An operational trans-conductance amplifier (OTA) structure with an auxiliary common-mode-feedback-OTA is proposed in the fully differential CSA to suppress the chopper modulation induced disturbance at the OTA input terminal. An analog temperature compensation method is proposed, which adjusts the chopper signal amplitude with temperature variation to compensate the temperature drift of the CSA readout sensitivity. The chip is designed and implemented in a 0.35 μm CMOS process and is 2.1 × 2.1 mm2 in area. The measurement shows that the readout circuit achieves 0.9 aF / √Hz capacitive resolution, 97 dB dynamic range in 100 Hz signal bandwidth, and 0.8 mV/fF sensitivity with a temperature drift of 35 ppm/°C after optimized compensation. (semiconductor integrated circuits)

  3. Development of control system for multi-converter high voltage power supply using programmable SoC

    International Nuclear Information System (INIS)

    Multi-converter based High Voltage Power Supplies (HVPSs) find application in multi-megawatt accelerators, RF systems. Control system for HVPS must be a combination of superior parallel processing, real time performance, fast computation and versatile connectivity. The hardware platform is expected to be robust, easily scalable for future developments without any cost overhead. Typical HVPS control mechanism involves communication, generation of precise control signals/pulses for few hundred Nos of chopper and closed loop control in microsecond range for regulated output. Such kind of requirements can be met with Zynq All Programmable SoC, which is a combination of Dual core ARM Cortex A-9 Processing System (PS) and Xilinx 7 series FPGA based Programmable Logic (PL). Deterministic functions of power supply control system such as generation of control signals with precise inter-channel delay of nanosecond range and communication with individual chopper at 100kbps can be implemented on PL. PS should implement corrective tasks based on field feedback received from individual chopper, user interface and OS management that allows to take full advantage of system capabilities. PS and PL are connected with on-chip AXI-4 interface with low latency and higher bandwidth through 9 AXI ports. Typically PS boots first, this ensures secure booting and prevents external environment from tampering PL. This paper describes development of control system on Zynq All Programmable SoC for HVPS. (author)

  4. Analysis and simulation of a small-angle neutron scattering instrument on a 1 MW long pulse spallation source

    International Nuclear Information System (INIS)

    We studied the design and performance of a small-angle neutron scattering (SANS) instrument for a proposed 1 MW, 60 Hz long pulsed spallation source at the Los Alamos Neutron Science Center (LANSCE). An analysis of the effects of source characteristics and chopper performance combined with instrument simulations using the LANSCE Monte Carlo instrument simulations package shows that the T0 chopper should be no more than 5 m from the source with the frame overlap and frame definition choppers at 5.6 and greater than 7 m, respectively. The study showed that an optimal pulse structure has an exponential decaying tail with τ ∼ 750 μs. The Monte Carlo simulations were used to optimize the LPSS SANS, showing that an optimal length is 18 m. The simulations show that an instrument with variable length is best to match the needs of a given measurement. The performance of the optimized LPSS instrument was found to be comparable with present world standard instruments

  5. An Automatic Data-Logging System for Meteorological Studies in Reactor Environments

    International Nuclear Information System (INIS)

    An automatic data-logging system has been designed for meteorological studies for the Tarapur power reactor. The system is designed to log data from 256 sensors divided into two groups of 128 each. The outputs from the sensors in analog form, varying from 0 to 100 mV can be scanned sequentially. The scanning unit, used for time multiplexing, consists of a bank of 256 pairs of reed relays. It connects sequentially the outputs from the two groups of sensors to two chopper-modulated d.c. amplifiers. The output from the chopper-modulated d.c. amplifier varies from -4 to -10 V. A linear and highly stable A-D converter connected alternately to the chopper-modulated d. c. amplifiers digitizes the amplified outputs. The digitized data are stored in a ferrite core memory with a capacity of 256 5-digit words. The data are handled in the binary-coded decimal form. Each memory location corresponds to a particular input sensor. When sensor Mi is selected by the scanning unit, its digitized output is added to the previously stored data in the Mith memory location and the result is stored back in the same location. The Mi + 1 sensor is next selected. The scanning unit selects all the sensors every second. At the end of 10 min the memory locations contain the averages of outputs of all the sensors. This data' is punched on a paper tape in the next 2 min. The sensors are scanned again after clearing the memory. The logical operations are controlled with a 100-kc/s crystal controlled time clock. The data are fed to a digital computer for analysis. (author)

  6. Cross Section Measurements for Some Elements Suited as Thermal Spectrum indicators: Cd, Sm, Gd and Lu

    International Nuclear Information System (INIS)

    The effective cross sections of Cd, Sm, Gd and Lu have been measured by the oscillator technique in the spectrum of the central channel of the Swedish reactor R1. For Cd, Sm and Gd the 2200 m/s cross sections were deduced on the basis of Westcott's g and s factors. The values obtained were generally in agreement with other recent values obtained by integral methods, although a systematic trend indicated that the value Tn - Tm = 29 ± 10 deg C for the neutron spectrum, measured with a fast chopper, was slightly too high. A new value of Tn - Tm = 22.5 ± 3.5 deg C was deduced and new 2200 m/s cross sections were obtained by iteration. For natural Lu, the energy dependence of the cross section is not well known. Certain assumptions about the cross section function led to unreasonably high values for the 2200 m/s cross section. Complementary differential measurements of the cross sections of Cd, Sm and Gd were made with the Rl fast chopper. For Cd and Sm the 2200 m/s cross section thus obtained agreed within experimental error with those obtained from the integral measurements. For Gd, the chopper measured value was higher, confirming earlier findings and indicating that the Westcott g factor for Gd is too high. Cd: Integral meas. : σ(2200) = 2,390 ± 45 b; Differential meas. : σ(2200) = 2,445 ± 25 b; Sm: Integral meas. : σ(2200) = 5,880 ± 90 b; Differential meas. : σ(2200) = 5,740 ± 150 b; Gd: Integral meas. : σ(2200) 46,470 ± 550 b; Differential meas. : σ(2200) = 47,900 ± 700 b

  7. Fully Integrated Biopotential Acquisition Analog Front-End IC

    Directory of Open Access Journals (Sweden)

    Haryong Song

    2015-09-01

    Full Text Available A biopotential acquisition analog front-end (AFE integrated circuit (IC is presented. The biopotential AFE includes a capacitively coupled chopper instrumentation amplifier (CCIA to achieve low input referred noise (IRN and to block unwanted DC potential signals. A DC servo loop (DSL is designed to minimize the offset voltage in the chopper amplifier and low frequency respiration artifacts. An AC coupled ripple rejection loop (RRL is employed to reduce ripple due to chopper stabilization. A capacitive impedance boosting loop (CIBL is designed to enhance the input impedance and common mode rejection ratio (CMRR without additional power consumption, even under an external electrode mismatch. The AFE IC consists of two-stage CCIA that include three compensation loops (DSL, RRL, and CIBL at each CCIA stage. The biopotential AFE is fabricated using a 0.18 μm one polysilicon and six metal layers (1P6M complementary metal oxide semiconductor (CMOS process. The core chip size of the AFE without input/output (I/O pads is 10.5 mm2. A fourth-order band-pass filter (BPF with a pass-band in the band-width from 1 Hz to 100 Hz was integrated to attenuate unwanted signal and noise. The overall gain and band-width are reconfigurable by using programmable capacitors. The IRN is measured to be 0.94 μVRMS in the pass band. The maximum amplifying gain of the pass-band was measured as 71.9 dB. The CIBL enhances the CMRR from 57.9 dB to 67 dB at 60 Hz under electrode mismatch conditions.

  8. Fully Integrated Biopotential Acquisition Analog Front-End IC.

    Science.gov (United States)

    Song, Haryong; Park, Yunjong; Kim, Hyungseup; Ko, Hyoungho

    2015-01-01

    A biopotential acquisition analog front-end (AFE) integrated circuit (IC) is presented. The biopotential AFE includes a capacitively coupled chopper instrumentation amplifier (CCIA) to achieve low input referred noise (IRN) and to block unwanted DC potential signals. A DC servo loop (DSL) is designed to minimize the offset voltage in the chopper amplifier and low frequency respiration artifacts. An AC coupled ripple rejection loop (RRL) is employed to reduce ripple due to chopper stabilization. A capacitive impedance boosting loop (CIBL) is designed to enhance the input impedance and common mode rejection ratio (CMRR) without additional power consumption, even under an external electrode mismatch. The AFE IC consists of two-stage CCIA that include three compensation loops (DSL, RRL, and CIBL) at each CCIA stage. The biopotential AFE is fabricated using a 0.18 μm one polysilicon and six metal layers (1P6M) complementary metal oxide semiconductor (CMOS) process. The core chip size of the AFE without input/output (I/O) pads is 10.5 mm². A fourth-order band-pass filter (BPF) with a pass-band in the band-width from 1 Hz to 100 Hz was integrated to attenuate unwanted signal and noise. The overall gain and band-width are reconfigurable by using programmable capacitors. The IRN is measured to be 0.94 μVRMS in the pass band. The maximum amplifying gain of the pass-band was measured as 71.9 dB. The CIBL enhances the CMRR from 57.9 dB to 67 dB at 60 Hz under electrode mismatch conditions. PMID:26437404

  9. Finite element analysis of interface stress between neutron absorption coating and chop disk

    International Nuclear Information System (INIS)

    The performance of disk chopper is directly affected by bond strength between neutron absorption coating and chop disk. Based on the finite element analysis software ANSYS, the interface stress distribution under high speed centrifugal load was calculated, which was to investigate the effects of coating's elastic modulus, poisson ratio and coating thickness on the interfacial stress distribution. The results show that soft and tough coating can reduce the peak stress effectively, and coating thickness reducing is helpful to avoid the plastic failure of opening in the disk under high speed centrifugal load. (authors)

  10. The Dielectric Bolometer, A New Type of Thermal Radiation Detector

    Science.gov (United States)

    Hanel, R. A.

    1960-01-01

    Thermal detectors for the infrared, such as thermocouples and bolometers, are limited in their ultimate sensitivity predominantly by Johnson noise rather than temperature noise. Low noise figures are hard to achieve since Johnson noise preponderates temperature noise, which is the only essential noise for thermal detectors. The dielectric constants of some materials are sufficiently temperature dependent to make a new type of bolometer feasible. The basic theory of a dielectric bolometer, as shown here, promises noise figures below 3 decibels even at chopper frequencies well above the 1/tau value of the detector. Ferroelectrics such as barium-strontium titanate and others seem to be well suited for radiation-cooled dielectric bolometers.

  11. Integrated Efficiency Test for Pyrochemical Fuel Cycles

    Energy Technology Data Exchange (ETDEWEB)

    S. X. Li; D. Vaden; R. W. Benedict; T. A. Johnson; B. R. Westphal; Guy L. Frederickson

    2007-09-01

    An integrated efficiency test was conducted with sodium bonded, spent EBR-II drive fuel elements. The major equipment involved in the test were the element chopper, Mk-IV electrorefiner, cathode processor, and casting furnace. Four electrorefining batches (containing 54.4 kg heavy metal) were processes under the fixed operating parameters that have been developed for this equipment based on over a decade’s worth of processing experience. A mass balance across this equipment was performed. Actinide dissolution and recovery efficiencies were established based on the mass balance and chemical analytical results of various samples taken from process streams during the integrated efficiency test.

  12. Mitigation of Voltage Swells by Static Series Compensator

    DEFF Research Database (Denmark)

    Awad, Hilmy; Blaabjerg, Frede

    2004-01-01

    swells, active power may be drawn from the grid into the energy-storage capacitor (ESC) of the SSC, depending on the load current and the SSC impedance. This active power may overcharge the ESC. Two possibilities to overcome this situation are explored in this paper: 1) if the dc-voltage of the ESC is...... lower than a predetermined voltage level, the active power is employed to charge the ESC to this voltage level; 2) otherwise, the overvoltage protection of the SSC must operate. This paper also applies an overvoltage protection scheme based on a combination of a dc resistor with a chopper and the valves...

  13. Speed Control of Separately Excited DC Motor

    Directory of Open Access Journals (Sweden)

    Moleykutty George

    2008-01-01

    Full Text Available This paper proposes the speed control of a separately excited dc motor (SEDM by varying armature voltage. The novelty of this paper lies in the application of nonlinear autoregressive-moving average (NARMA–L2 controller for the speed control of SEDM. This paper also discusses speed control of a SEDM using chopper circuit. The performance of the proposed system has been compared with the traditional one using conventional controllers. The entire system has been modeled using MATLAB 7.0 toolbox. It has been found that both PI and hysteresis current controllers could be eliminated by the use of NARMA-L2 controller.

  14. Straight and chopped DC performance data for a General Electric 5BY436A1 DC shunt motor with a General Electric EV-1 controller

    Science.gov (United States)

    Edie, P. C.

    1981-01-01

    Both straight and chopped dc motor performance data for a General Electric 5BY436A1 motor with a General Electric EV-1 controller is presented in tabular and graphical formats. Effects of motor temperature and operating voltage are also shown. The maximum motor efficiency is approximately 85% at low operating temperatures in the straight dc mode. Chopper efficiency can be assumed to be 95% under all operating conditions. For equal speeds, the motor operated in the chopped mode develops slightly more torque and draws more current than it does in the straight mode.

  15. Inverters for interfacing of solar cells with the power grid

    Science.gov (United States)

    Karamanzanis, G. N.; Jackson, R. D.

    In this work, based on a research course in the Engineering Dep. Cambridge University, some non-classical inverter circuits are studied. They can be used for interfacing solar cells with the power grid at low voltage (230V) and at low power level. They are based on d.c. choppers which have a fast switching transistor. Their theoretical efficiency is 100 percent and they provide a satisfactory output current waveform in phase to the a.c. line voltage. The problems of control are also studied using a suitable mathematical model.

  16. System for Automation of experiments on Neutron Fourier Diffractometer FSD

    CERN Document Server

    Bogdzel, A A; Butenko, V A; Drozdov, V A; Zhuravlev, V V; Kuzmin, E S; Levchanovsky, F V; Pole, A V; Prikhodko, V I; Sirotin, A P

    2004-01-01

    The report presents a description of the system for the automation of experiments on the Fourier neutron diffractometer FSD at the reactor IBR-2 in FLNR JINR. The system is a complex of hard- and software that enables necessary control of experiments and data acquisition and includes - detector electronics, - electronics and instruments in sample environment, - device for control of fast Fourier chopper of neutron beam, - electronics for measurement and acquisition of low- and high-resolution spectra, - software for control of spectrometers and automation of experiments. The description and characteristics of basic blocks together with characteristics of the special-purpose software are also provided.

  17. Operators end helicopter flights ferrying crews over rough seas

    Energy Technology Data Exchange (ETDEWEB)

    Roche, Pat

    2011-04-15

    New criteria for offshore helicopter flight safety have been established by oil and gas operators in Newfoundland and Labrador following a 2009 crash investigation. Choppers will no longer fly personnel over rough seas when they exceed the capability of the flotation equipment. Seventeen people died when a Sikorsky S-92A helicopter crashed into the sea. Offshore oil and gas operators in Newfoundland presently contract five large helicopters; the three that are used regularly for passengers are enhanced with flotation equipment that can stand six metre waves and the other two have the standard manufacturer's equipment to survive four metre waves.

  18. Background-filtered transmission diffraction with internal intensity calibration

    International Nuclear Information System (INIS)

    It is inferred that by frequency filtering the logarithm of the time-of-flight spectrum of neutrons that have passed through a powdered isotropic crystalline sample a diffractogram may be obtained with many desirable properties for achieving high-quality refinemenet of structural parameters. Apart from multiple scattering no wavelength-dependent effects or corrections need to be introduced, which implies automatic internal calibration of the Bragg intensities. For utilization of the inherent high resolution of the transmission geometry, a Fourier chopper in the pulsed beam from an intensity-optimized quasi-steady-state moderator is suggested. Results of model calculations are presented. (orig.)

  19. Sensitivity analysis of an LCL-filter-based three-phase active rectifier via a virtual circuit approach

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Chiarantoni, Ernesto; Aquila, Antonio Dell’; Liserre, Marco; Vergura, Silvano

    2004-01-01

    Three-phase active rectifiers based on the voltage source converter topology can successfully replace traditional thyristor based rectifiers or diode bridge plus chopper in interfacing dc-systems to the grid. However, if the application in which they are employed has a high safety issue or if there......, to the grid side stiffness and to the parameters of the controller has never been detailed considered. In this paper the experimental results of an LCL-filter-based three-phase active rectifier are analysed with the circuit theory approach. A ?virtual circuit? is synthesized in role of the digital...

  20. Controller for computer control of brushless dc motors. [automobile engines

    Science.gov (United States)

    Hieda, L. S. (Inventor)

    1981-01-01

    A motor speed and torque controller for brushless d.c. motors provides an unusually smooth torque control arrangement. The controller provides a means for controlling a current waveform in each winding of a brushless dc motor by synchronization of an excitation pulse train from a programmable oscillator. Sensing of torque for synchronization is provided by a light beam chopper mounted on the motor rotor shaft. Speed and duty cycle are independently controlled by controlling the frequency and pulse width output of the programmable oscillator. A means is also provided so that current transitions from one motor winding to another is effected without abrupt changes in output torque.

  1. A method for comparison of experimental and theoretical differential neutron spectra in the Zenith reactor

    International Nuclear Information System (INIS)

    A method of calculation is given which assists the analyses of chopper measurements of spectra from ZENITH and enables complex multigroup theoretical calculations of the spectra to be put into a form which may be compared with experiment. In addition the theory of the cut-off function has been extended to give analytical expressions which take into account the effects of sub-collimators, off centre slits and of a rotor made of a material partially transparent to neutrons. The theoretical cut-off function suggested shows good agreement with experiment. (author)

  2. Local Optical Spectroscopies for Subnanometer Spatial Resolution Chemical Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, Paul

    2014-01-20

    The evanescently coupled photon scanning tunneling microscopes (STMs) have special requirements in terms of stability and optical access. We have made substantial improvements to the stability, resolution, and noise floor of our custom-built visible-photon STM, and will translate these advances to our infrared instrument. Double vibration isolation of the STM base with a damping system achieved increased rigidity, giving high tunneling junction stability for long-duration and high-power illumination. Light frequency modulation with an optical chopper and phase-sensitive detection now enhance the signal-to-noise ratio of the tunneling junction during irradiation.

  3. Short term Braking Capability during Power Interruptions for Integrated Matrix Converter-Motor Drives

    DEFF Research Database (Denmark)

    Klumpner, Christian; Blaabjerg, Frede

    2002-01-01

    The new trend in Adjustable Speed Drives (ASD) is to integrate the inverter and the motor into a single unit in order to reduce the production cost, the commissioning time and the physical size of the equipment. This last issue becomes more important, making the matrix converter topology more...... engages or to perform more effective a combined braking.This paper proposes a new method to provide short-term braking capability during a power outage for matrix converters. A braking chopper is needed in the clamp circuit, which allows for a drastically reduction of the capacitor size. The power flow in...

  4. Large Signal Model of a Four-quadrant AC to DC Converter for Accelerator Magnets

    CERN Document Server

    De la Calle, R; Rinaldi, L; Völker, F V

    2001-01-01

    This paper presents the large signal model of a four-quadrant AC to DC converter, which is expected to be used in the area of particle accelerators. The system’s first stage is composed of a three-phase boost PWM (Pulse Width Modulated) rectifier with DSP (Digital Signal Processing) based power factor correction (PFC) and output voltage regulation. The second stage is a full-bridge PWM inverter that allows fast four-quadrant operation. The structure is fully reversible, and an additional resistance (brake chopper) is not needed to dissipate the energy when the beam deflection magnet acts as generator.

  5. Digital humanitarians how big data is changing the face of humanitarian response

    CERN Document Server

    Meier, Patrick

    2015-01-01

    The Rise of Digital HumanitariansMapping Haiti LiveSupporting Search And Rescue EffortsPreparing For The Long Haul Launching An SMS Life Line Sending In The Choppers Openstreetmap To The Rescue Post-Disaster Phase The Human Story Doing Battle With Big Data Rise Of Digital Humanitarians This Book And YouThe Rise of Big (Crisis) DataBig (Size) Data Finding Needles In Big (Size) Data Policy, Not Simply Technology Big (False) Data Unpacking Big (False) Data Calling 991 And 999 Big (

  6. A Practical and Portable Solids-State Electronic Terahertz Imaging System

    Directory of Open Access Journals (Sweden)

    Ken Smart

    2016-04-01

    Full Text Available A practical compact solid-state terahertz imaging system is presented. Various beam guiding architectures were explored and hardware performance assessed to improve its compactness, robustness, multi-functionality and simplicity of operation. The system performance in terms of image resolution, signal-to-noise ratio, the electronic signal modulation versus optical chopper, is evaluated and discussed. The system can be conveniently switched between transmission and reflection mode according to the application. A range of imaging application scenarios was explored and images of high visual quality were obtained in both transmission and reflection mode.

  7. HHEBBES! All sky camera system: status update

    Science.gov (United States)

    Bettonvil, F.

    2015-01-01

    A status update is given of the HHEBBES! All sky camera system. HHEBBES!, an automatic camera for capturing bright meteor trails, is based on a DSLR camera and a Liquid Crystal chopper for measuring the angular velocity. Purpose of the system is to a) recover meteorites; b) identify origin/parental bodies. In 2015, two new cameras were rolled out: BINGO! -alike HHEBBES! also in The Netherlands-, and POgLED, in Serbia. BINGO! is a first camera equipped with a longer focal length fisheye lens, to further increase the accuracy. Several minor improvements have been done and the data reduction pipeline was used for processing two prominent Dutch fireballs.

  8. FOCUS: time-of-flight spectrometer for cold neutrons at SINQ

    International Nuclear Information System (INIS)

    The physical layout of the Time-Of-Flight spectrometer at the new spallation source SINQ is presented. The concept shows up a hybrid-TOF combining a Fermi-chopper with a crystal monochromator. The demand of a versatile and flexible instrument for several applications is taken into account by the option of switching from time-focusing to monochromatic focusing mode such that the spectrometer can be optimised for both quasielastic and inelastic scattering applications. (author) 5 figs., 2 tabs., 16 refs

  9. African Homo erectus: Old radiometric ages and young Oldowan assemblages in the middle Awash Valley, Ethiopia

    Energy Technology Data Exchange (ETDEWEB)

    Clark, J.D.; White, T.D.; Selassie, Y.H. (Univ. of California, Berkeley, CA (United States)); Heinzelin, J. de (Institut Royal des Sciences Naturelles de Belgique, Brussels (Belgium)); Schick, K.D. (Indiana Univ., Bloomington, IN (United States)); Hart, W.K. (Miami Univ., Oxford, OH (United States)); WoldeGabriel, G. (Los Alamos National Lab., NM (United States)); Walter, R.C. (Institute of Human Origins, Berkeley, CA (United States)); Suwa, G. (Univ. of Tokyo (Japan)); Asfaw, B. (Addis Ababa (Ethiopia)) (and others)

    1994-06-24

    Fossils and artifacts recovered from the middle Awash Valley of Ethiopia's Afar depression sample the Middle Pleistocene transition from Homo erectus to Homo sapiens. Ar/Ar ages, biostratigraphy, and tephrachronology from this area indicate that the Pleistocene Bodo hominid cranium and newer specimens are approximately 0.6 million years old. Only Oldowan chopper and flake assemblages are present in the lower stratigraphic units but Acheulean bifacial artifacts are consistently prevalent and widespread in directly overlying deposits. This technological transition is related to a shift in sedimentary regime, supporting the hypothesis that Middle Pleistocene Oldowan assemblages represent a behavioral facies of the Acheulean industrial complex.

  10. Analysis Of Single Phase Matrix Converter

    Directory of Open Access Journals (Sweden)

    Divya Ahirrao

    2014-03-01

    Full Text Available This paper presents concept of single phase matrix converter. Single phase matrix converter (SPMC performs a function such as frequency changer, rectifier, inverter; chopper. This reduces the need for new converter hardware. Pulse width modulation (SPWM techniques are used to calculate the switch duty ratio to synthesis the output. The simulation of converter is carried out in MATLAB/SIMULINK. Hardware design is obtained using readily available IC‟s and other components. This paper discusses the new multiple converter for single phase input using matrix topology using just a single control logic.

  11. Simulation and Implementation of an Embedded Hybrid Fuzzy Trained Artificial Neural Network Controller for Different DC Motor

    OpenAIRE

    M.Muruganandam; I.Thangaraju; Madheswaran, M.

    2014-01-01

    In this article, the speed of the DC motor is controlled by Hybrid Fuzzy-Neuro controller (FNC). The Hybrid Fuzzy-Neuro controller is designed and tested for different types of DC motors like DC separately excited motor and DC series motor. The motor is fed by DC-DC buck converter (DC chopper). The system has two loops of inner current controller loop and outer Fuzzy-Neuro based speed controller loop. The speed controller gives the duty cycle to generate the PWM signal for the control of chop...

  12. Review of Fast Beam Chopping

    CERN Document Server

    Caspers, Friedhelm

    2004-01-01

    Several types of fast beam chopping systems in use or under construction are presented. Emphasis is given to their specific technologies and in particular their various fields of application. Important parameters are duty cycle, rise- and fall-time, ringing and overall bandwidth. Certain systems have very specific driver concepts, since the generation of multi-kW peak power with nanosecond transients, high repetition rate and very good pulse shape fidelity is not a trivial issue. The design of driver amplifier and actual chopper structure are not always mutually independent and thus some of the limiting aspects will be discussed.

  13. Wide range double photoionisation spectra of N2 and CO2

    Science.gov (United States)

    Eland, J. H. D.; Plogmaker, S.; Lablanquie, P.; Penent, F.; Palaudoux, J.; Nicolas, C.; Robert, E.; Miron, C.; Feifel, R.

    2016-02-01

    Using a magnetic bottle time-of-flight electron spectrometer we have measured double photoionisation spectra of N2 and CO2 covering the range from threshold up to the triple ionisation energies. The experiments demonstrate the use of a new asynchronous chopper in eight-bunch mode of the synchrotron radiation source SOLEIL. For CO22+ some broad bands in the Auger spectra are found to have multiple resolved counterparts in the photoionisation spectrum. All the bands in the Auger spectra have counterparts in the photoionisation spectra, where extra bands attributed to triplet states are present. In the spectrum of N22+ we suggest reassignment of one band.

  14. Systematic experimental study on a highly efficient terahertz source based on two-color laser-induced air plasma

    Science.gov (United States)

    Xie, Jun; Fan, Wen-Hui; Chen, Xu

    2016-05-01

    In this paper, highly efficient terahertz radiation generated by two-color femtosecond laser-induced air plasma is reported. A number of variables that can obviously influence terahertz generation and detection have been investigated systematically. The dependence on experimental parameters, including pulse energy, the rotation angle of beta-barium boron oxide (BBO) crystal, the distance between BBO crystal and laser-induced plasma, focal length, chopper frequency, and detection angle are presented, and the optimal values of these parameters have also been obtained experimentally. Finally, a highly efficient terahertz source has been achieved and can be utilized to carry out further investigation on terahertz sensing, spectroscopy, and imaging.

  15. Visualization of cavitation phenomena in a Diesel engine fuel injection nozzle by neutron radiography

    Science.gov (United States)

    Takenaka, N.; Kadowaki, T.; Kawabata, Y.; Lim, I. C.; Sim, C. M.

    2005-04-01

    Visualization of cavitation phenomena in a Diesel engine fuel injection nozzle was carried out by using neutron radiography system at KUR in Research Reactor Institute in Kyoto University and at HANARO in Korea Atomic Energy Research Institute. A neutron chopper was synchronized to the engine rotation for high shutter speed exposures. A multi-exposure method was applied to obtain a clear image as an ensemble average of the synchronized images. Some images were successfully obtained and suggested new understanding of the cavitation phenomena in a Diesel engine fuel injection nozzle.

  16. Osprey – war for its own existence

    Directory of Open Access Journals (Sweden)

    Pavel NEČAS

    2012-09-01

    Full Text Available The aircraft that flies like an airplane but takes off and lands like a chopper. It has been a long, strange trip: the V-22 has been 25 years in development, more than twice as long as the Apollo program that put men on the moon. V-22 crashes have claimed the lives of 30 men — 10 times the lunar program's toll — all before the plane has seen combat. The Pentagon has put $20 billion into the Osprey and expects to spend an additional $35 billion before the program is finished. In exchange, the Marines, Navy and Air Force will get 458 aircraft, averaging $119 million per copy.

  17. Vibration Combined High Temperature Cycle Tests for Capacitive MEMS Accelerometers

    CERN Document Server

    Szucs, Z; Hodossy, S; Rencz, M; Poppe, A

    2008-01-01

    In this paper vibration combined high temperature cycle tests for packaged capacitive SOI-MEMS accelerometers are presented. The aim of these tests is to provide useful Design for Reliability information for MEMS designers. A high temperature test chamber and a chopper-stabilized read-out circuitry were designed and realized at BME - DED. Twenty thermal cycles of combined Temperature Cycle Test and Fatigue Vibration Test has been carried out on 5 samples. Statistical evaluation of the test results showed that degradation has started in 3 out of the 5 samples.

  18. The NC Power Supply Design of Large Current and Wide Frequency Pulse in SEAM

    OpenAIRE

    Jianping Zhou; Yan Xu; Qiang He; Bisheng Zhou

    2013-01-01

    There are a lot of ways to achieve large current pulse power supply, and the more common way is to adopt the inverter switching circuit to achieve pulse power supply. The core of the NC power supply design of large current and wide frequency pulse in SEAM is using two-stage modulation. Combined with inverter technology, DC chopper technology and NC technology, it not only can achieve the adjustability of the output pulse amplitude, but also can realize continuous adjustment of the output puls...

  19. ISEE - Information system for renewables on the Internet; ISEE - Informationssystem fuer Erneuerbare Energien im Internet

    Energy Technology Data Exchange (ETDEWEB)

    Rohrig, K. [ISET - Institut fuer Solare Energieversorgungstechnik e.V., Kassel (Germany)

    1997-12-31

    Since 1988 ISET has been operating a central information system for components of solar energy plants called ISEE. At present this online data base offers technical data, cost data, and manufacturers` information on photovoltaic modules, solar collectors, aerogenerators, inverters, DC chopper converters, batteries, solar charge control devices, solar irradiance measuring devices, and anemometers. (HW) [Deutsch] Seit 1988 betreibt das ISET ein zentrales Informationssystem fuer Komponenten solarer Energieversorgungsanlagen ISEE. Aktuell stehen in dieser Online-Datenbank technische Daten, Kostendaten sowie Herstellerinformationen zu Photovoltaikmodulen, Sonnenkollektoren, Windenergieanlagen, Stromrichtern, Gleichstromstellern, Batterien, Solarladereglern, Solarstrahlungsmessgeraeten und Windmessgeraeten zur Verfuegung. (HW)

  20. FOCUS: time-of-flight spectrometer for cold neutrons at SINQ

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, S.; Mesot, J. [Lab. for Neutron Scattering ETH Zurich, Zurich (Switzerland) and Paul Scherrer Institute, Villigen (Switzerland); Hempelmann, R. [Saarbruecken Univ., Physical Chemistry, Saarbruecken (Germany)

    1996-11-01

    The physical layout of the Time-Of-Flight spectrometer at the new spallation source SINQ is presented. The concept shows up a hybrid-TOF combining a Fermi-chopper with a crystal monochromator. The demand of a versatile and flexible instrument for several applications is taken into account by the option of switching from time-focusing to monochromatic focusing mode such that the spectrometer can be optimised for both quasielastic and inelastic scattering applications. (author) 5 figs., 2 tabs., 16 refs.

  1. Molecular structure-property correlations from optical nonlinearity and thermal-relaxation dynamics

    OpenAIRE

    Bhattacharyya, Indrajit; Priyadarshi, Shekhar; Goswami, Debabrata

    2009-01-01

    We apply ultrafast single beam Z-scan technique to measure saturation absorption coefficients and nonlinear-refraction coefficients of primary alcohols at 1560 nm. The nonlinear effects result from vibronic transitions and cubic nonlinear-refraction. To measure the pure total third-order nonlinear susceptibility, we removed thermal effects with a frequency optimized optical-chopper. Our measurements of thermal-relaxation dynamics of alcohols, from 1560 nm thermal lens pump and 780 nm probe ex...

  2. VESPA: The vibrational spectrometer for the European Spallation Source

    Science.gov (United States)

    Fedrigo, Anna; Colognesi, Daniele; Bertelsen, Mads; Hartl, Monika; Lefmann, Kim; Deen, Pascale P.; Strobl, Markus; Grazzi, Francesco; Zoppi, Marco

    2016-06-01

    VESPA, Vibrational Excitation Spectrometer with Pyrolytic-graphite Analysers, aims to probe molecular excitations via inelastic neutron scattering. It is a thermal high resolution inverted geometry time-of-flight instrument designed to maximise the use of the long pulse of the European Spallation Source. The wavelength frame multiplication technique was applied to provide simultaneously a broad dynamic range (about 0-500 meV) while a system of optical blind choppers allows to trade flux for energy resolution. Thanks to its high flux, VESPA will allow the investigation of dynamical and in situ experiments in physical chemistry. Here we describe the design parameters and the corresponding McStas simulations.

  3. Improved detection of paramagnetic contrast enhancement by PEACH imaging for the diagnosis of disk versus scar in lumbar MR imaging

    International Nuclear Information System (INIS)

    To assist in distinguishing recurrent disk herniation form scar in symptomatic patients after lumbar laminectomy, the authors have compared conventional Gd-DTPA-enhanced T1-weighted images with lipid suppressed (paramagnetic enhancement accentuation by chemical shift [PEACH] images. Conventional T1-weighted and paired PEACH images were obtained at 1.5 T through lumbar disk levels. Lipid suppression was achieved by using a hybrid approach that combines a frequency-selective pulse with Chopper fat suppression. In all cases, the detection of normal and abnormal enhancement was improved by using PEACH; enhanced isointense lesions that were infiltrating fat and were missed on the conventional series were easily detected on PEACH images

  4. The front end test stand high performance H- ion source at Rutherford Appleton Laboratory.

    Science.gov (United States)

    Faircloth, D C; Lawrie, S; Letchford, A P; Gabor, C; Wise, P; Whitehead, M; Wood, T; Westall, M; Findlay, D; Perkins, M; Savage, P J; Lee, D A; Pozimski, J K

    2010-02-01

    The aim of the front end test stand (FETS) project is to demonstrate that chopped low energy beams of high quality can be produced. FETS consists of a 60 mA Penning Surface Plasma Ion Source, a three solenoid low energy beam transport, a 3 MeV radio frequency quadrupole, a chopper, and a comprehensive suite of diagnostics. This paper details the design and initial performance of the ion source and the laser profile measurement system. Beam current, profile, and emittance measurements are shown for different operating conditions. PMID:20192390

  5. L'outillage lithique du site de dépeçage à Elephas recki ileretensis de Barogali (république de Djibouti)Stone tools from the butchery site with Elephas recki ileretensis of Barogali (Republic of Djibouti)

    Science.gov (United States)

    Berthelet, Arlette

    2001-03-01

    Three seasons of excavations (1985-1987) in the Gobaad region of the Republic of Djibouti have unearthed the fossilized skeletal remains of an Elephas recki (1.3-1.6 million years old). Numerous stone artefacts discovered among the bones indicates that the excavation is a butchery site where hominids cut up and perhaps consumed the elephant meat. The discovery of cores and small flakes near the elephant carcass indicates that the hominids knapped choppers and polyhedrons and retouched flakes during the scavenging operation.

  6. Lock-in based detection scheme for a hydrogen beam

    International Nuclear Information System (INIS)

    Full text: In this work we present the data acquisition for a atomic hydrogen beamline that will be used to simulate an antihydrogen beam. Single particle detection of the hydrogen atoms will be done using a quadrupole mass spectrometer. Since a high background count of hydrogen is expected, special treatment of the data is necessary. Therefore a tuning-fork chopper will be used to produce a bunched hydrogen beam. Afterwards the noise will be removed with a software based lock-in amplifier. (author)

  7. First measurements with the test stand for optical beam tomography

    OpenAIRE

    Wagner, Christopher; Meusel, Oliver; Ulrich, Ratzinger; Reichau, Hermine

    2011-01-01

    A test stand for optical beam tomography was developed. As a new non-destructive beam-diagnostic system for high current ion beams, the test stand will be installed in the low energy beam transport section (LEBT) of the Frankfurt Neutron Source (FRANZ) behind the chopper system. The test stand consists of a rotatable vacuum chamber with a mounted CCD camera. The maximum rotation angle amounts to 270°. In a first phase the optical beam profile measurement and 3D density reconstruction is teste...

  8. Power circuit design master from rectifier to switching regulator

    International Nuclear Information System (INIS)

    It is divided into two parts to introduce of power circuit design . The first part deals with design for regulator of dropper type such as rectifier circuit design, power for the simplest stabilizing and know-how of series regulator design. The second part lists switching regulator design, including regulator design with chopper type, RCC type, forward converter design, DC-DC converter, uninterruptible power supply design, high-power design, know-how for level packing technology for heat dissipation and new technology of power circuit.

  9. Advanced DC/DC converters

    CERN Document Server

    Luo, Fang Lin

    2003-01-01

    INTRODUCTIONHistorical ReviewMultiple Quadrant ChoppersPump CircuitsDevelopment of DC/DC Conversion TechniqueCategorize Prototypes and DC/DC Converters Family TreeVOLTAGE-LIFT CONVERTERSIntroductionSeven Self-Lift ConvertersPositive Output Luo-ConvertersNegative Output Luo-ConvertersModified Positive Output Luo-Converters Double Output Luo-ConvertersPOSITIVE OUTPUT SUPER-LIFT LUO-CONVERTERS IntroductionMain SeriesAdditional SeriesEnhanced Series Re-Enhanced Series Multiple-Enhanced Series Summary of Positive Output

  10. Passive Resonant Bidirectional Converter with Galvanic Barrier

    Science.gov (United States)

    Rosenblad, Nathan S. (Inventor)

    2014-01-01

    A passive resonant bidirectional converter system that transports energy across a galvanic barrier includes a converter using at least first and second converter sections, each section including a pair of transfer terminals, a center tapped winding; a chopper circuit interconnected between the center tapped winding and one of the transfer terminals; an inductance feed winding interconnected between the other of the transfer terminals and the center tap and a resonant tank circuit including at least the inductance of the center tap winding and the parasitic capacitance of the chopper circuit for operating the converter section at resonance; the center tapped windings of the first and second converter sections being disposed on a first common winding core and the inductance feed windings of the first and second converter sections being disposed on a second common winding core for automatically synchronizing the resonant oscillation of the first and second converter sections and transferring energy between the converter sections until the voltage across the pairs of transfer terminals achieves the turns ratio of the center tapped windings.

  11. Power supply system of J-PARC main ring main magnets for high repetition rate operation

    International Nuclear Information System (INIS)

    Japan Proton Accelerator Research Complex (J-PARC) aims at achieving a MW-class proton accelerator facility. One of the promising solutions for increasing the beam power is to fasten the repetition rate of Main Ring (MR) from current rating of 2.5 sec to 1 sec in the future. However, in this scheme, the increase of output voltage and the power variation on the electric system are serious concerns for main magnets. At the same time, current ripple reduction is required in order to increase the beam quality for the hadron experiments. We have been developing power supplies which have potentials to solve these problems and plan to replace the current power supplies with them. The new power supply system has following features. The number of power supply is twice so that one power supply drives half number of loads compared with the current system. The power supply is consists of some choppers which are wired in series. The energy recovery scheme based on the capacitive energy storage is introduced. Parallel connected choppers increase the equivalent switching frequency so that the switching ripple is possible to be reduced by the filter. This paper introduces the power supply system of J-PARC MR main magnets for high repetition rate operation. (author)

  12. 基于超级电容电动汽车制动能回收的研究%Research on the Recovery of Electric Vehicle Braking Energy Based on Super Capacitor

    Institute of Scientific and Technical Information of China (English)

    肖佐无; 王海波

    2015-01-01

    针对电动汽车制动能回收的问题,采用超级电容为储能器件,无刷直流电机的制动能通过BUCK斩波器以恒流充电的方式给超级电容充电,既能回收制动能又使制动力矩可控。采用电流闭环负反馈,自动调节BUCK斩波器的占空比,达到恒流充电的目的。仿真实验表明:这种方法是可行的、有效的。%For the problem of electric vehicle braking energy recovery, using the super capacitor as energy storage device, the braking energy of Brushless DC motor charging the super capacitor with the constant current charge by BUCK chopper, not only recovers the braking energy but also makes the brake torque controllable. Negative feedback of current closed-loop was adopted, and the duty cycle of the BUCK chopper is adjusted automatically, which achieves the constant current charging. The simulation experiment shows that this method is feasible and effective.

  13. ESR/U-series chronology of the Lower Palaeolithic palaeo-anthropological site of Visogliano, Trieste, Italy

    International Nuclear Information System (INIS)

    The Visogliano shelter, in north-eastern Italy, is an important Middle Pleistocene occupation site where human remains were found together with an archaic lithic industry, including choppers, chopping tools and a few proto-bifaces. It is of utmost importance to try to document this period, when a second wave of settlement colonised Western Europe, carrying new flaking techniques and tools. Combined ESR/U-series analyses, integrated with bio-stratigraphical and environmental data, define a chronological frame for the layers from which the artefacts were unearthed. The lower levels, including human remains, can be dated to the 350-500 kyr time span, in agreement with micro-mammal and stratigraphical studies. These data make Visogliano one of the oldest palaeo-anthropological sites in Italy, where human remains are directly associated with proto-bifaces, choppers and chopping tools. In Western Europe, Visogliano is contemporaneous to the G soil of the Arago Cave, France, with which it shares several similarities in faunal assemblages and radiometric data, and which contains human remains also. These data make Visogliano as one of the oldest sites in Europe where the Acheulian culture is observed. (authors)

  14. AMOR – the time-of-flight neutron reflectometer at SINQ/PSI

    Indian Academy of Sciences (India)

    Mukul Gupta; T Gutberlet; J Stahn; P Keller; D Clemens

    2004-07-01

    The apparatus for multioptional reflectometry (AMOR) at SINQ/PSI is a versatile reflectometer operational in the time-of-flight (TOF) mode (in a wavelength range of 0.15 nm > > 1.3 nm) as well as in the monochromatic ( - 2) mode with both polarized and unpolarized neutrons. AMOR is designed to perform reflectometry measurements in horizontal sample-plane geometry which allows studying both solid–liquid and liquid–liquid interfaces. A pulsed cold neutron beam from the end position of the neutron guide is produced by a dual-chopper system (side-by-side) having two windows at 180° and rotatable with a maximum frequency of 200 Hz. In the TOF mode, the chopper frequency, width of the gating window and the chopper–detector distance can be selected independently providing a wide range of -resolution ( / = 1–10%). Remanent FeCoV/Ti : N supermirrors are used as polarizer/analyzer with a polarization efficiency of ∼ 97%. For the monochromatic wavelength mode, a Ni/Ti multilayer is used as a monochromator, giving ∼ 50% reflectivity at a wavelength of 0.47 nm. In the present work, a detailed description of the instrument and setting-up of the polarization option is described. Results from some of the recent studies with polarized neutrons and measurements on liquid surfaces are presented.

  15. Correlation Fourier diffractometry: 20 Years of experience at the IBR-2 reactor

    Science.gov (United States)

    Balagurov, A. M.; Bobrikov, I. A.; Bokuchava, G. D.; Zhuravlev, V. V.; Simkin, V. G.

    2015-05-01

    The high-resolution Fourier diffractometer (HRFD) was commissioned at the IBR-2 pulsed reactor at FLNP JINR in 1994. The specific feature of the HRFD design is the use of fast Fourier chopper for modulating the primary neutron beam intensity and the correlation method of diffraction data acquisition. This allowed to reach with HRFD extremely high resolution (Δ d/ d ≈ 0.001) over a wide range of inter-planar spacings at a relatively short flight path between chopper and sample ( L = 20 m). Over time, a lot of diffraction experiments on crystalline materials, the main goal of which was to study their atomic and magnetic structures, were performed at HRFD. Successful implementation of the Fourier diffractometry technique at the IBR-2 reactor stimulated the construction of yet another Fourier diffractometer intended for internal mechanical stress studies in bulk materials (FSD, Fourier Stress Diffractometer). In this paper the experience of using this technique at the IBR-2, which is a long-pulse neutron source, is considered, the examples of HRFD studies are given, and possible solutions for existing technical problems of using correlation diffractometry and ways of increasing the intensity and resolution of HRFD are discussed.

  16. SOLAR TO AC POWER SOURCE FOR REMOTE AREAS USING SEIG

    Directory of Open Access Journals (Sweden)

    MEHMET AKBABA

    2012-02-01

    Full Text Available Photovoltaic generators (PVG are increasingly used to provide electricity in remote areas. However, in many applications the DC generated electricity by a PVG need to be converted to AC. Traditionally DC to AC inverters have been widely used for this purpose. In this paper, a different system is proposed in which a self excited induction generator (SEIG driven by a permanent magnet DC motor (DCM and powered from a PVG through a maximum power point tracker (MPPT are used. A step-up chopper is utilized as an MPPT unit. The proposed system is modelled in time domain, and a detailed transient and steady-state analysis are presented. The main reason behind analyzing the system in the time domain is because of the fact that for unknown speeds, the methods developed for steady-state analysis of SEIGs can not be applied. The presented work shows that the full available power of the PVG can be harnessed by selecting suitable values for the duty cycle and the frequency of the step up chopper and the excitation capacitor of the SEIG. It is also shown that with such a combination power utilization efficiency of more than 83% can be achieved.

  17. A New Vector Frequency Modulation Method for Power Conversion Circuits

    Science.gov (United States)

    Takano, Akio

    This paper presents an excellent PWM method for power conversion circuits. The proposed method is called a Vector Frequency Modulation (VFM) in this paper. VFM does not belong to any conventional PWM methods. Although an idea of space voltage vector is employed in VFM, any traditional equations to calculate the periods of the voltage vectors are not used. The voltage vectors are classified into two groups, zero vectors and non-zero ones. Instead of the complicated equations, a very simple algorithm is employed in VFM. One vector period is fixed and the zero vectors are distributed among the non-zero vectors in the ratio determined by the command voltage or frequency. The behavior of VFM is performed in software and any modulation-wave oscillators, comparators and up-down counters are not needed. At first, a reversible chopper is modulated by VFM and a 2kW DC motor is driven by the chopper. The motor speed is regulated by modern control theory. Next, a three-phase inverter is modulated by VFM and a 2.2kW induction motor is driven by the inverter. Experimental results are shown to prove that VFM is actually useful for power conversion circuits.

  18. A review of high beam current RFQ accelerators and funnels

    International Nuclear Information System (INIS)

    The authors review the design features of several high-current (> 20-mA) and high-power (> 1-mA average) proton or H- injectors, RFQs, and funnels. They include a summary of observed performance and will mention a sampling of new designs, including the proposed incorporation of beam choppers. Different programs and organizations have chosen to build the RFQ in diverse configurations. Although the majority of RFQs are either low-current or very low duty-factor, several versions have included high-current and/or high-power designs for either protons or H- ions. The challenges of cooling, handling high space-charge forces, and coupling with injectors and subsequent accelerators are significant. In all instances, beam tests were a valuable learning experience, because not always did these as-built structures perform exactly as predicted by the earlier design codes. They summarize the key operational parameters, indicate what was achieved, and highlight what was learned in these tests. Based on this generally good performance and high promise, even more challenging designs are being considered for new applications that include even higher powers, beam funnels and choppers

  19. Modelling and characterization of the PEM fuel cell to study interactions with power converters; Modelisation et caracterisation de la pile pem pour l'etude des interactions avec les convertisseurs statiques

    Energy Technology Data Exchange (ETDEWEB)

    Fontes, G.

    2005-09-15

    The climatic and energy challenges were now clearly stated. The use of hydrogen is one of the best ways which gives many hopes. Fuel cells are an essential link in the chain of the use of hydrogen. Thus, a lot of studies have been undertaken throughout the world on fuel cells in many fields of physics. Concerning the field of power electronics, a lot of work on distributed generation technologies using fuel cells has been realised too and a great number of power converters dedicated to fuel cells have been studied. However, very few studies have been undertaken on the interactions between fuel cells and power converters. The goals of this work are to study interactions between fuel cells and power converters. Some requirements for the power electronic engineer can follow from this work. This work proposes high signal dynamic models of a H{sub 2}/O{sub 2} PEM fuel cell. These models include the different physical and chemical phenomena. Specific methods based on a limited number of original experiments (low frequency current sweeps) allow to extract the model parameters. These models are used to study the interactions between fuel cells and power converters which are the most used: buck chopper, boost chopper, inverters. The important part of the double layer capacitors has thus been underlined: they can filter the current harmonics created by the power converters. Finally, some choices of filtering elements to be connected to the fuel cell are proposed. (author)

  20. The external PIXE setup for the analysis of manuscripts at the Florence University

    International Nuclear Information System (INIS)

    The external beam PIXE setup of the 3 MV Van de Graaff accelerator in Florence is extensively used for the analysis of parchments, rulings, inks and miniature temperas of Medieval and Renaissance manuscripts. The beam is collimated to about 200 μm and exits from the vacuum environment through a 8 μm Kapton window. Beam currents from 200 to 500 pA are used; they have been found to produce no visible damage to the examined materials. Two Si(Li) detectors are simultaneously used with different geometries in order to cover the widest possible Z-range of the detected elements: Even Na is detected with good sensitivity. A robust and versatile support has been constructed for safe and easy handling of the manuscripts. A laser alignment system allows accurate aiming at the detail of interest. A rotating chopper samples the beam at a frequency of the order of 1 Hz; X-rays produced on a Ni layer evaporated on the graphite vane of the chopper are used for charge normalization, since the weak current pulses would be unreliably measured in air due, in particular, to space, charge effects. An application is shortly presented, concerning the materials used for the 'colour' rulings which are found, starting from the 11th century, to delimit the writing field for the copyist. (orig.)

  1. Thermoacoustic range verification using a clinical ultrasound array provides perfectly co-registered overlay of the Bragg peak onto an ultrasound image

    Science.gov (United States)

    Patch, S. K.; Kireeff Covo, M.; Jackson, A.; Qadadha, Y. M.; Campbell, K. S.; Albright, R. A.; Bloemhard, P.; Donoghue, A. P.; Siero, C. R.; Gimpel, T. L.; Small, S. M.; Ninemire, B. F.; Johnson, M. B.; Phair, L.

    2016-08-01

    The potential of particle therapy due to focused dose deposition in the Bragg peak has not yet been fully realized due to inaccuracies in range verification. The purpose of this work was to correlate the Bragg peak location with target structure, by overlaying the location of the Bragg peak onto a standard ultrasound image. Pulsed delivery of 50 MeV protons was accomplished by a fast chopper installed between the ion source and the cyclotron inflector. The chopper limited the train of bunches so that 2 Gy were delivered in 2 μ \\text{s} . The ion pulse generated thermoacoustic pulses that were detected by a cardiac ultrasound array, which also produced a grayscale ultrasound image. A filtered backprojection algorithm focused the received signal to the Bragg peak location with perfect co-registration to the ultrasound images. Data was collected in a room temperature water bath and gelatin phantom with a cavity designed to mimic the intestine, in which gas pockets can displace the Bragg peak. Phantom experiments performed with the cavity both empty and filled with olive oil confirmed that displacement of the Bragg peak due to anatomical change could be detected. Thermoacoustic range measurements in the waterbath agreed with Monte Carlo simulation within 1.2 mm. In the phantom, thermoacoustic range estimates and first-order range estimates from CT images agreed to within 1.5 mm.

  2. Current saturation in free-air ionization chambers with chopped synchrotron radiation

    International Nuclear Information System (INIS)

    An expression for ion recombination in free-air ionization chambers irradiated by chopped X-rays is presented. The expression is validated by comparison with experiments using synchrotron radiation. Saturation curves for free-air ionization chambers with electrode gap widths of 4.2, 8.4 and 18 mm were obtained for 10 and 15 keV undulator synchrotron radiation thinned with a 230 Hz rotating-disk chopper. Ion recombination in free-air ionization chambers was found to be inversely proportional to the applied electric field, and an expression that satisfactorily reproduced the ion-recombination rate is determined. A comparison of the expressions for continuous and pulsed X-rays revealed that chopped high-intensity X-rays require a higher voltage to attain saturation when the product of the pulse width and electric field exceeds a value that depends on the X-ray energy. This behaviour was observed explicitly for 10 keV X-rays in measurements with the ionization chamber placed before and after the chopper

  3. Investigation Into the Utilization of 3D Printing in Laser Cooling Experiments

    Science.gov (United States)

    Hazlett, Eric; Nelson, Brandon; de Leon, Sam Diaz; Shaw, Jonah

    2016-05-01

    With the advancement of 3D printing new opportunities are abound in many different fields, but with the balance between the precisions of atomic physics experiments and the material properties of current 3D printers the benefit of 3D printing technology needs to be investigated. We report on the progress of two investigations of 3D printing of benefit to atomic physics experiments: laser feedback module and the other being an optical chopper. The first investigation looks into creation of a 3D printed laser diode feedback module. This 3D printed module would allow for the quick realization of an external cavity diode laser that would have an adjustable cavity distance. We will report on the first tests of this system, by looking at Rb spectroscopy and mode-hop free tuning range as well as possibilities of using these lasers for MOT generation. We will also discuss our investigation into a 3D-printed optical chopper that utilizes an Arduino and a computer hard drive motor. By implementing an additional Arduino we create a low cost way to quickly measure laser beam waists.

  4. Polarized neutron spectrometer for inelastic experiments at J-PARC - Status of POLANO project

    International Nuclear Information System (INIS)

    The construction of the newly developed polarization analysis neutron chopper spectrometer (POLANO) has begun in the Japan Proton Accelerator Research Complex (J-PARC), Materials and Life Science Experimental Facility (MLF). POLANO is a direct geometry chopper spectrometer with neutron polarization analysis capability for inelastic scattering experiments. In the suite of inelastic spectrometers, six instruments are now in operation involving direct geometry, inverted geometry, and spin echo instruments. POLANO will be the only spectrometer dedicated to polarization analysis experiments. The polarizer, analyzer, and other magnetic devices installed in the POLANO are currently under development. As the polarizer, a cylindrical 3He spin filter (HeSF) based on the spin-exchange optical pumping (SEOP) technique will be used to polarize neutrons in the wide energy range. During the experiments, the HeSF is operated in the on-beam mode to maintain 3He polarization The primary phase of the construction will be completed by 2014 with beam commissioning scheduled in 2015

  5. ESR/U-series chronology of the Lower Palaeolithic palaeo-anthropological site of Visogliano, Trieste, Italy

    Energy Technology Data Exchange (ETDEWEB)

    Falgueres, C.; Bahain, J.J.; Yokoyama, Y. [CNRS, UMR 5198, Museum Natl Hist Nat, Dept Prehist, F-75013 Paris, (France); Tozzi, C.; Boschian, G. [Univ Pisa, Dipartimento Sci Archeol, I-56100 Pisa, (Italy); Dolo, J.M. [CEA Saclay, Lab Natl Henri Becquerel, F-91191 Gif Sur Yvette, (France); Mercier, N.; Valladas, H. [CEA, CNRS, Lab Sci Climat and Environm, F-91198 Gif Sur Yvette, (France)

    2008-07-01

    The Visogliano shelter, in north-eastern Italy, is an important Middle Pleistocene occupation site where human remains were found together with an archaic lithic industry, including choppers, chopping tools and a few proto-bifaces. It is of utmost importance to try to document this period, when a second wave of settlement colonised Western Europe, carrying new flaking techniques and tools. Combined ESR/U-series analyses, integrated with bio-stratigraphical and environmental data, define a chronological frame for the layers from which the artefacts were unearthed. The lower levels, including human remains, can be dated to the 350-500 kyr time span, in agreement with micro-mammal and stratigraphical studies. These data make Visogliano one of the oldest palaeo-anthropological sites in Italy, where human remains are directly associated with proto-bifaces, choppers and chopping tools. In Western Europe, Visogliano is contemporaneous to the G soil of the Arago Cave, France, with which it shares several similarities in faunal assemblages and radiometric data, and which contains human remains also. These data make Visogliano as one of the oldest sites in Europe where the Acheulian culture is observed. (authors)

  6. Advanced Neutron Reflectometer for Investigation on Dynamic/Static Structures of Soft-Interfaces in J-PARC

    Energy Technology Data Exchange (ETDEWEB)

    Mitamura, Koji; Takahara, Atsushi [JST, ERATO Takahara Soft Interfaces Project (Japan); Yamada, Norifumi L; Sagehashi, Hidenori; Seto, Hideki [High Energy Accelerator Research Organization (KEK) (Japan); Torikai, Naoya [Graduate School of Engineering, Mie University (Japan); Sugita, Tsukasa; Furusaka, Michihiro, E-mail: takahara@cstf.kyushu-u.ac.jp [Graduate School of Engineering, Hokkaido University (Japan)

    2011-01-01

    A novel neutron reflectometer with horizontal geometry will be established at BL16 in Materials and Life Science Experimental Facility (MLF) of Japan Proton Accelerator Research Complex (J-PARC) as a successor of a reflectometer ARISA-II. ARISA-II corresponding to a single neutron beam downward at 2.22 deg has achieved off-specular and time-resolved reflectivity measurements. The novel reflectometer is designed so as to receive two tilted neutron beams (2.22 and 5.71 deg), which gives us an opportunity in investigation on a free liquid surface. The reflectometer can provide a micro-sized beam by slit collimation and obtain a fair reflectivity with small sample area. Also, T0 chopper and neutron focusing mirror are newly introduced. The T0 chopper can suppress the background due to fast neutrons. The focusing mirror produces further reduction of measurement time not only for specular reflection by focusing neutrons on a sample, but also grazing incidence small-angle neutron scattering (GISANS) measurements by focusing on a detector.

  7. Neutron spectrum measurements from a neutron guide tube facility at the ETRR-1 reactor

    International Nuclear Information System (INIS)

    The present work deals with measurements of the neutron spectrum emitted from a neutron guide tube (NGT) recently installed at one of the ETRR-1 reactor horizontal channels designed to deliver thermal neutrons, free from fast neutrons and gamma ray background, to a fourier reverse-time-of-flight (RTOF) diffractometer. The measurements were performed using a 6 Li glass scintillation detector combined with a multichannel analyzer set at channel width 4 M sec and installed at 3.4 m from a disc Fermi chopper. Also a theoretical model was specially developed for the neutron spectrum calculations. According to the model developed, the spectrum calculated was found to be in good agreement with the measured one. It was found, both from measurements and calculations, that the spectrum emitted from the NGT covers, after transmission through a fourier chopper, neutron wavelengths from 1-4 A adequate for neutron diffraction measurements at D values between 0.71-2.9 A respectively. 6 FIGS

  8. Neutron Spectrum Measurements from a Neutron Guide Tube Facility at the ETRR-1 Reactor

    International Nuclear Information System (INIS)

    The present work deals with measurements of the neutron spectrum emitted from a neutron guide tube (NGT) recently installed at one of the ETRR-1 reactor horizontal channels; designed to deliver thermal neutrons, free from fast neutrons and gamma-rays background, to a Fourier reverse-time-of-flight (RTOF) diffractometer. The measurements were preformed using a 6Li glass scintillation detector installed at 3.45 m from a disc Fermi chopper, combined with a multichannel analyzer set at channel width 4 mu sec. Also a theoretical model was especially developed for the neutron spectrum calculations. The spectrum calculated according to the developed model was found to be in good agreement with the measured one. It was found, both from measurements and calculations, that the spectrum emitted from the NGT covers, after transmission through a Fourier chopper, neutron wavelengths from 1-4 A degree. The maximum of the neutron spectrum was found to be at neutron wavelength lambda=1.39 A degree which is consistent with the value 1.377 A degree calculated for the curved NGT characteristic wavelength

  9. New capabilities in spectroscopy on pulsed sources: adjustable pulse repetition rate, resolution and line shape

    International Nuclear Information System (INIS)

    Spectroscopy with cold neutrons is one of the most important areas of current superiority of reactor based instruments over those at spallation sources. This is particularly due to the capability of continuous source time-of-flight spectrometers to use instrumental parameters optimally adapted for best data collection rate in each experiment. These parameters include the pulse repetition rate and the length of the pulses to achieve optimal balance between resolution and intensity. In addition, the disc chopper systems used provide perfect symmetrical line shapes with no tails and low background. We present a set of novel techniques making up the IN500 project at Los Alamos, which is based on the combined use of extended pulse length, coupled moderator, disc chopper system and advanced neutron optical beam delivery. This development will enable Lujan center to surpass the best reactor sources in cold neutron spectroscopy by realizing for the first time all of the above key capabilities of steady state instruments on a pulsed spallation source. (author)

  10. FEASIBILITY STUDY OF A PIVOTED-PLATE SENSOR FOR SILAGE CORN YIELD MONITORING

    Directory of Open Access Journals (Sweden)

    Maharlouie M.M., Loghavi M., and Kamgar S.

    2012-03-01

    Full Text Available Crop yield map is a useful means to quantify yield variations within the fields and to provide a scientific basis for implementing site-specific crop management strategies. This research explores the feasibility of developing a new silage yield monitoring system by employing a new mass flow sensor based on using the momentum of chopped material impacting a pivoted plate loaded by a retractable spring installed at the end of a chopper discharge spout. A precise rotary potentiometer was used to measure the degree of pivoted plate rotation. To save and process the output voltage of the potentiometer, a programmable circuit comprising of AVR microcontroller ATMEGA series and MAX 232 microchip was used and the output data was sent to a portable computer for further processing. To calibrate the output signal of the sensor versus instantaneous chopped material flow rate, the chopper was fed artificially with predetermined mass flow rates of 6, 8 and 10 kg s-1 of silage corn at five replications for each feeding rate. The results of statistical analysis showed high correlation between degrees of the pivoted-plate rotation and instantaneous feed rates with adjusted R2 of 0.98. To evaluate the accuracy of mass flow rate estimation, a platform scale weighing system was used during the field tests. The statistical analysis did not show any significant difference between sensor mass flow rate estimation and platform scale weighing system output. By using the resulted calibration equation, yield map of a silage cornfield was generated.

  11. KENS report-7, 1987/88

    International Nuclear Information System (INIS)

    The present issue summarizes the research activities performed at the KENS Facility from September, 1986 to March, 1988. In this issue, the style of the report is improved a little bit to the concise from with two columns. In this period, proton beam intensity was gradually increased, and a beam intensity of 2 x 1012 protons per pulse seemed to come within range. A new data acquisition and processing system was introduced last year, and the construction of a chopper spectrometer INC progressed. The total number of the papers published was about 250. This is the third year of the UK-Japan collaboration on neutron scattering study, and the construction of a chopper spectrometer MARI provided by KEK will be completed in 1990 on the ISIS in Rutherford Appleton Laboratory. A lot of the experiments on high Tc superconductors were proposed, and mostly carried out as a part of B1 experiments. The future program of the pulsed spallation neutron source KENS-2 was included in the Japanese Hadron Facility Project as an important part of four major fields. The project is now under examination by the government. In the last chapter of this report, the short reports on high intensity proton accelerators are compiled for future reference. The reports in the fields of instrumentation, neutron scattering, structures of liquid and glass, magnetic structure and excitation and others are collected. (K.I.)

  12. Experimental Investigations on PV Powered SVM-DTC Induction Motor without AC Phase Current Sensors

    Directory of Open Access Journals (Sweden)

    T. Muthamizhan

    2014-05-01

    Full Text Available The paper presents a low-cost, phase-current reconstruction algorithm for space vector modulated direct torque controlled induction motor using the information obtained from only one shunt resistor which is in series with low side switches in a conventional three-phase inverter. The aim is to develop a low-cost high - performance induction motor drive. It uses the dc-link voltage and dc current to reconstruct the stator currents needed to estimate the motor flux and the electromagnetic torque. Photovoltaic arrays convert solar power to dc electric power; uses chopper and dc-ac inverter to fed three phase Induction Motor. The chopper used here is current fed full bridge boost dc-dc converter, which is preferred and extensively used in high voltage applications and advantageous over voltage fed converters. The inverter switches are controlled by PWM techniques obtained from SVM-DTC of IM. The experimental investigations are given to prove the ability of the proposed scheme of reproducing the performances of a SVM- DTC IM drive.

  13. Investigation Into the Utilization of 3D Printing in Laser Cooling Experiments

    Science.gov (United States)

    Hazlett, Eric

    With the advancement of 3D printing new opportunities are abound in many different fields, but with the balance between the precisions of atomic physics experiments and the material properties of current 3D printers the benefit of 3D printing technology needs to be investigated. We report on the progress of two investigations of 3D printing of benefit to atomic physics experiments: laser feedback module and the other being an optical chopper. The first investigation looks into creation of a 3D printed laser diode feedback module. This 3D printed module would allow for the quick realization of an external cavity diode laser that would have an adjustable cavity distance. We will report on the first tests of this system, by looking at Rb spectroscopy and mode-hop free tuning range as well as possibilities of using these lasers for MOT generation. We will also discuss our investigation into a 3D-printed optical chopper that utilizes an Arduino and a computer hard drive motor. By implementing an additional Arduino we create a low cost way to quickly measure laser beam waists

  14. Current Development Status of Time-of-Flight Inelastic Neutron Spectrometer at HANARO

    International Nuclear Information System (INIS)

    As part of the Cold Neutron Research Facility (CNRF) project launched in 2003, disk chopper time-off light (DC-TOF) spectrometer was proposed for the study of slow dynamics of all condensed matter sciences, which has been increasingly proven to be invaluable information. Here we present the current status of the DC-TOF instrument development. The HANARO research reactor has started operation since 1995 and reached its full operation power of 30 MW in 2004. Three neutron scattering instruments such as HRPD, FCD and SANS have been since running for user program, both domestic and foreign researchers. Till now, however there has been no inelastic neutron spectrometer in Korea, which has deterred otherwise natural growth of an inelastic neutron scattering community. Disk chopper time-of-flight inelastic neutron spectrometer is an advanced neutron scattering instrument, which has been proven worldwide to be very versatile for both basic science and material engineering studies. Therefore, when the Korea Atomic Energy Research Institute (KAERI) started the CNRF project in 2003, it was a natural choice that it decided to build DC-TOF for the cold neutron laboratory. Day-1 instruments of the CNRF project include a DC-TOF, a cold TAS, a 40m-SANS, and two reflectometers. In this paper, we present the current design specifications of the DC-TOF at the KAERI

  15. Performance of TOF powder diffractometers on reactor sources

    Energy Technology Data Exchange (ETDEWEB)

    Peters, Judith [Hahn-Meitner-Institut Berlin, Glienicker Str. 100, D-14109 Berlin (Germany)]. E-mail: peters@hmi.de; Bleif, Hans-Juergen [Hahn-Meitner-Institut Berlin, Glienicker Str. 100, D-14109 Berlin (Germany); Kali, Gyoergy [Budapest Research Reactor, 1121 Budapest, Konkoly Thege ut 29-33 (Hungary); Rosta, Laszlo [Research Institute for Solid State Physics and Optics, 1525 Budapest, P.O.B. 49 (Hungary); Mezei, Ferenc [Hahn-Meitner-Institut Berlin, Glienicker Str. 100, D-14109 Berlin (Germany): LANSCE, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States)

    2006-11-15

    In 1998, a prototype of a time-of-flight (TOF) powder diffractometer was built at KFKI in Budapest in collaboration with the Hahn-Meitner-Institut (HMI) in Berlin. At a reactor source the neutron pulses are produced by a chopper system, which allows for shorter pulses than those obtained at pulsed spallation sources in the wavelength range most relevant for diffraction work, i.e. {lambda}{>=}0.7 A. Furthermore, the chopper system provides an ideal symmetric line shape. First results proved the high potential of the approach, namely an excellent resolution of 1-5x10{sup -3} for {delta}d/d was achieved. The prototype is presently rebuilt as a user instrument at the Budapest Neutron Centre. At HMI Berlin a new much more complex TOF powder diffractometer (EXED=extreme environment diffractometer) with higher resolution is under construction. It will benefit from variable resolution to achieve either ultrahigh resolution or very high intensities at conventional resolutions. EXED is devoted to studies under extreme sample conditions, for instance the TOF technique permits the access of a broad range of Q-values or d-spacing domains under scattering angle access strongly restricted by the use of highest field magnets. The whole instrument was simulated by Monte Carlo (MC) technique, and the simulations yield promising results.

  16. Performance of TOF powder diffractometers on reactor sources

    International Nuclear Information System (INIS)

    In 1998, a prototype of a time-of-flight (TOF) powder diffractometer was built at KFKI in Budapest in collaboration with the Hahn-Meitner-Institut (HMI) in Berlin. At a reactor source the neutron pulses are produced by a chopper system, which allows for shorter pulses than those obtained at pulsed spallation sources in the wavelength range most relevant for diffraction work, i.e. λ≥0.7 A. Furthermore, the chopper system provides an ideal symmetric line shape. First results proved the high potential of the approach, namely an excellent resolution of 1-5x10-3 for Δd/d was achieved. The prototype is presently rebuilt as a user instrument at the Budapest Neutron Centre. At HMI Berlin a new much more complex TOF powder diffractometer (EXED=extreme environment diffractometer) with higher resolution is under construction. It will benefit from variable resolution to achieve either ultrahigh resolution or very high intensities at conventional resolutions. EXED is devoted to studies under extreme sample conditions, for instance the TOF technique permits the access of a broad range of Q-values or d-spacing domains under scattering angle access strongly restricted by the use of highest field magnets. The whole instrument was simulated by Monte Carlo (MC) technique, and the simulations yield promising results

  17. Low noise and high CMRR front-end amplifier dedicated to portable EEG acquisition system.

    Science.gov (United States)

    Chebli, Robert; Sawan, Mohamad

    2013-01-01

    This paper concerns the design and implementation of a fully integrated low noise and high CMRR rail-to-rail preamplifier dedicated to EEG acquisition channel. The preamplification technique is based on two complementary CMOS True Logarithmic Amplifier (TLA) stages connected in parallel. The TLA largely amplifies small amplitude of EEG signals, and moderately the large amplitude ones created during epileptic. A chopper stabilization technique is used to filter the 1/ƒ noise and the DC offset voltage of the input CMOS transistors and to increase the common-mode rejection ratio (CMRR). Due to the TLA structure, a high CMRR and high power supply rejection ratio are achieved and the signal-to-noise ratio (of the channel is better enhanced). To snugly fit the ADC input window to the EEG signal magnitude a new programming gain approach is implemented. Also, a chopper spike filter is used to cancel the spike voltages generated by the charge injections of modulator/demodulator switches. The proposed preamplifier is implemented in 0.18 µm CMOS technology. Post-layout simulation results exhibit 253 dB @50/60 Hz as CMRR, 500 nVrms @100 Hz as input-referred noise while consuming 55 µA from a 1.8 V supply. PMID:24110240

  18. Application of Control charts and isotope correlations to spent fuel measurements at FCF

    International Nuclear Information System (INIS)

    The material control and accountancy system for the Fuel Conditioning Facility (FCF) initially uses calculated values for the mass flows of irradiated EBR-II driver fuel to be processed in the electrorefiner. These calculated values are continually verified by measurements performed by the Analytical Laboratory (AL) on samples from the fuel element chopper retained for each chopper batch. Measured values include U and Pu masses, U and Pu isotopic fractions, and burnup (via La and Tc). When the measured data become available, it is necessary to determine if the measured and calculated data are consistent. This verification involves accessing two databases and performing standard statistical analyses to produce control charts for these measurements. These procedures can now be invoked via a Web interface providing: a timely and efficient control of these measurements, a user-friendly interface, off-site remote access to the data, and a convenient means of studying correlations among the data. This paper will present the architecture of the interface and a description of the control procedures, as well as examples of the control charts and correlations

  19. A digital long pulse integrator for EAST Tokamak

    International Nuclear Information System (INIS)

    Highlights: • This digital integrator is done in real time integration and data transmission. • Chopper technology and linear compensation is used for drift correction. • This integrator has achieved results of 411 s long pulse plasma discharge in 2012 EAST campaign. - Abstract: A digital integrator has been developed to be compatible with the long pulse plasma discharges on the Experimental Advanced Superconductor Tokamak (EAST), in which the induced signal is modulated by a chopper, and a field programmable gate array (FPGA) in the 16-bit digitizer is used to realize the digital integration in real time. After rectification and integration, the drift is almost linear and stable in controlled temperature, so a period of 50 s is used to determine the linear drift rate for drift compensation. The integration data can be directly transferred to the reflective memory (RFM) card, which is installed in the same PCI eXtensions for Instrumentation (PXI) chassis, so the data transmission can be also done in real time. The test results show that the real time data transmission rate is up to 10 kHz, the integration drift is typically less than 0.4 uVs/s and drift performance is a little worse in real long pulse discharge, which can be reduced further by using more precise data acquisition

  20. Thermoacoustic range verification using a clinical ultrasound array provides perfectly co-registered overlay of the Bragg peak onto an ultrasound image.

    Science.gov (United States)

    Patch, S K; Kireeff Covo, M; Jackson, A; Qadadha, Y M; Campbell, K S; Albright, R A; Bloemhard, P; Donoghue, A P; Siero, C R; Gimpel, T L; Small, S M; Ninemire, B F; Johnson, M B; Phair, L

    2016-08-01

    The potential of particle therapy due to focused dose deposition in the Bragg peak has not yet been fully realized due to inaccuracies in range verification. The purpose of this work was to correlate the Bragg peak location with target structure, by overlaying the location of the Bragg peak onto a standard ultrasound image. Pulsed delivery of 50 MeV protons was accomplished by a fast chopper installed between the ion source and the cyclotron inflector. The chopper limited the train of bunches so that 2 Gy were delivered in [Formula: see text]. The ion pulse generated thermoacoustic pulses that were detected by a cardiac ultrasound array, which also produced a grayscale ultrasound image. A filtered backprojection algorithm focused the received signal to the Bragg peak location with perfect co-registration to the ultrasound images. Data was collected in a room temperature water bath and gelatin phantom with a cavity designed to mimic the intestine, in which gas pockets can displace the Bragg peak. Phantom experiments performed with the cavity both empty and filled with olive oil confirmed that displacement of the Bragg peak due to anatomical change could be detected. Thermoacoustic range measurements in the waterbath agreed with Monte Carlo simulation within 1.2 mm. In the phantom, thermoacoustic range estimates and first-order range estimates from CT images agreed to within 1.5 mm. PMID:27385261

  1. Web interface for control of spent fuel measurements at FCF

    International Nuclear Information System (INIS)

    The material control and accountancy system for the Fuel Conditioning Facility (FCF) initially uses calculated values for the mass flows of irradiated EBR-11 driver fuel to be processed in the electrorefiner. These calculated values are continually verified by measurements performed by the Analytical Laboratory (AL) on samples from the fuel element chopper retained for each chopper batch. Measured values include U and Pu masses, U and Pu isotopic fractions, and burnup (via La and Tc). When the measured data become available, it is necessary to determine if the measured and calculated data are consistent. This verification involves accessing two databases and performing standard statistical analyses to produce control charts for these measurements. These procedures can now be invoked via a Web interface providing: a timely and efficient control of these measurements, a user-friendly interface, off-site remote access to the data, and a convenient means of studying correlations among the data. This paper will present the architecture of the interface and a description of the control procedures, as well as examples of the control charts and correlations

  2. 3.6MW Power Supply System of the 170GHz ECH&CD System in KSTAR

    Directory of Open Access Journals (Sweden)

    Joung Jin-Hyun

    2012-09-01

    Full Text Available A 3.6 MW (-66 kV/55 A Gyrotron power supply system was developed for the 170 GHz ECH&CD gyrotron system in KSTAR. This power supply system consists of Cathode Power Supply(CPS, Anode Power Supply(APS and Body Power Supply(BPS. The CPS is using the Pulse Step Modulation by the 32set of IGBT choppers. The respons time of Chopper is very fast. So the cathode voltaget is able to be controlled rapidly. The APS is a sort of voltage devider using zener and switch component. It was achieved 3kHz modulation operation. The BPS is combined the commercial power supply and special high voltage switches. It is very simple topology but 5kHz modulation was accomplished easily. Theses power supply system were installed and commissioned successfully in 2011. This paper presents the topology of the each power supply and test result for 170 GHz gyrotron in KSTAR.

  3. A Report on the 1993 Excavation of the Gaolingpo Paleolithic Site in the Bose Basin%百色高岭坡旧石器遗址1993年发掘简报

    Institute of Scientific and Technical Information of China (English)

    侯亚梅; 高立红; 黄慰文; 谢光茂; 林强; 王頠; 田丰

    2011-01-01

    This paper is a preliminary report of the excavation and study of stone artifacts from work at the Gaolingpo site of Baise (Bose) Basin in 1993. From an area of40m2, totally 445 stone artifacts were collected together with some tektites. The majority of artifacts are flakes and chunks except for some formal tools and manuports. There are various types of choppers and also becs, which is the second most prominent tools after those from the Fengshudao site in Baise Basin. The character of flakes shows a high degree of complex working. The large proportion of flakes and chunks reveals that the excavated area was a stone tool - making workshop. These knapped flakes and debris may have close relationship with conventional tool types like handaxes,picks and chopper, etc. from other Paleolithic sites in the basin. New types of choppers and flake tools like becs indicate the potential of future research of the Baise Paleolithic industry.%本文是对1993年度高岭坡遗址发掘情况的初步研究.本次发掘共揭露面积40m2,获得石制品445件(7件采集),并在同层发现了玻璃陨石.石制品包括石片、断块、工具和备料;其中石片和断块占绝大多数,没有发现石核.工具有以砾石为毛坯的各类砍砸器和以石片为毛坯的鸟喙状器;石片特点揭示剥片程度很高,剥片程序复杂.高比例各类石片的存在揭示该发掘区位于一石器制造场内,反映出该遗址古人类石器制作工序的行为片段,与百色盆地旧石器遗址中常见的大型工具的制作存在密切联系.

  4. 旋转导向钻井工具发电机电磁转矩控制及其优化%Control and optimization of the generator electromagnetic torque of rotary steering drilling tools

    Institute of Scientific and Technical Information of China (English)

    金金; 程为彬; 郭颖娜

    2011-01-01

    Steering function of all-rotary steering drilling tools is achieved through adjusting electromagnetic torque of the downhole turbine generator. Through the control circuit model in a pulse-width-modulation (PWM) chop mode, the mathematical expression of electromagnetic torque of rotary steering drilling tools was deduced. A relationship between electromagnetic torque and control factors was established by means of numerical calculation and verified by bench test. The internal cause of ripple torque from a generator and its calculation were discussed in terms of magnetic energy storage and an active power factor calibration was introduced into the chopper control circuit. An optimized chopper control circuit was designed, which can improve power factors and circuit stability. The test result shows that the optimized chopper control circuit can eliminate harmonic ripple torque and enhance the stability of circuit while increasing the adjustment range of electromagnetic torque.%全旋转导向钻井工具的导向功能是通过调节其下涡轮发电机输出电磁转矩实现的.根据PWM斩波型控制电路模型,推导出旋转导向钻井工具涡轮发电机电磁转矩的数学表达式,通过数值计算确定了电磁转矩与控制量之间的关系,并进行了台架试验验证.从电机磁场储能角度讨论了发电机输出脉动转矩产生的内在原因及其计算方法,并在斩波型控制电路中引入有源功率因数校正技术,设计了一种可提高功率因数和电路稳定性的优化控制电路.试验测试结果表明,斩波优化控制电路消除了谐波脉动转矩,在增强电路稳定性的同时也增加了电磁转矩的调节范围.

  5. ACTIVE LONGITUDINAL PAINTING FOR THE H-CHARGE EXCHANGE INJECTION OF THE LINAC4 BEAM INTO THE PS BOOSTER

    CERN Document Server

    CARLI, C; CERN. Geneva. AB Department

    2008-01-01

    Linac4 will provide 160 MeV H- to the PS Booster synchrotron. The H-beam will be injected by charge exchange injection allowing injecting several times into the same volumes of phase space. Thus, a large number of turns can be injected with high efficiencies and â€ワpainting” in order to shape the initial particle distribution for optimum performance becomes possible. In particular, a chopper makes longitudinal painting possible in addition to painting in transverse phase spaces. The slow synchrotron motion in the PS Booster implies an active longitudinal painting scheme, where the Linac4 output energy is modulated. Several active longitudinal painting schemes are presented. One scheme, based on a triangular Linac energy modulation, is proposed for the PS Booster H- injection with Linac4.

  6. Optical alignment and testing of the Diffuse IR Background Experiment IR cryogenic telescope

    International Nuclear Information System (INIS)

    Diffuse Infrared Background Experiment (DIRBE) optical alignment and testing methods are discussed. Using strobe videography, vibration and performance testing of a 32 hz tuning-fork chopper was carried out. The Cosmic Background explorer satellite provides improved microwave and IR all-sky maps of the cosmic background radiation from a polar orbit. A liquid helium cryostat houses the DIRBE and the Far IR Absolute Spectrophotometer (FIRAS) instruments at a temperature of 2 K. Differential MicRowave Radiometers (DMRs) provide large scale maps of anisotropy of the 3 K background at wavelengths of 3.3, 5.7, and 9.6 mm. The DIRBE telescope is an IR photometric instrument with 10 wavelength bands between 1 and 300 microns, designed to measure radiation from the epoch of galaxy formation. Stringent stray light requirements mean that the DIRBE flight instrument has to be built and tested in a class 100 environment

  7. Growth and properties of CuAlSe{sub 2} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Bodnar, I.V. [Belarussian State Univ., Minsk (Belarus)

    1994-09-01

    The compound CuAlSe{sub 2} is one of the A{sup I}B{sup III}C{sup VI}{sub 2} ternary compounds that crystallize in the chalcopyrite structure (sp. gr. D{sup 12}{sub 2d} - I{bar 4}2m). Given that CuAlSe{sub 2} exhibits birefringence and an optical isotropy point (the intersection point of the dispersion curves for ordinary n{sub o} and extraordinary n{sub e} indices), it is considered as a promising material for producing electro-optic choppers and narrow-band visible/near-IR filters. Up to now, there have been no reports on growth of high-quality CuAlSe{sub 2} single crystals by the Bridgman technique. Therefore, the purpose of this work was to grow high-quality crystals of CuAlSe{sub 2} and to study their properties.

  8. An electric vehicle propulsion system's impact on battery performance: An overview

    Science.gov (United States)

    Bozek, J. M.; Smithrick, J. J.; Cataldo, R. C.; Ewashinka, J. G.

    1980-01-01

    The performance of two types of batteries, lead-acid and nickel-zinc, was measured as a function of the charging and discharging demands anticipated from electric vehicle propulsion systems. The benefits of rapid high current charging were mixed: although it allowed quick charges, the energy efficiency was reduced. For low power (overnight) charging the current wave shapes delivered by the charger to the battery tended to have no effect on the battery cycle life. The use of chopper speed controllers with series traction motors resulted in a significant reduction in the energy available from a battery whenever the motor operates at part load. The demand placed on a battery by an electric vehicle propulsion system containing electrical regenerative braking confirmed significant improvment in short term performance of the battery.

  9. Design and Development of DSP Controlled Filament Power Supply for 1 MW, 352.2 MHz Klystron

    Directory of Open Access Journals (Sweden)

    Akhilesh Tripathi# , M. K. Badapanda and P. R. Hannurkar

    2013-04-01

    Full Text Available A digitally controlled current regulated 20 V, 25 A dc power supply employing IGBT based chopper is developed as the filament power supply for 1 MW, 352.2 MHz, Thales make TH 2089 klystron amplifier. The filament of this klystron is floating at cathode voltage of -100 kV dc, hence this power supply is kept on a floated platform and isolated through a suitable HV isolation transformer. Control and protection of this power supply is implemented through Texas make TMS320F2812 digital signal processor (DSP and fibre optics based optical communication is adopted. Detailed simulation is carried out and a close match between simulated and experimental results was obtained, which are presented in this paper. The long term output current stability and peak to peak output current ripple of this power supply are found to be below 0.5 %

  10. FOCUS: a new time-of-flight spectrometer at the neutron spallation source SINQ/CH

    International Nuclear Information System (INIS)

    The design of the time-of-flight (TOF) spectrometer FOCUS to be built at the SINQ at the Paul Scherrer Institute is presented. The main purpose is to provide a versatile TOF machine well suited for a large variety of applications. The concept of the instrument consists in the combination of a doubly- and variably-focusing monochromator with a Fermi chopper. By changing the optical conditions FOCUS will have the option to be operated either in time- or monochromatic-focusing mode, for quasielastic and inelastic scattering measurements, respectively. The expected performances of FOCUS are presented and compared to the existing IN6-TOF spectrometer at the Institute Laue-Langevin (ILL). (author) 2 figs., 2 tabs., 4 refs

  11. Photovoltaic Power System with MPPT Functionality for a Small-Size Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Jianming Xu

    2014-01-01

    Full Text Available Electric vehicles are recognized as the best replacement of petrol vehicles in the future. However, there are several problems hampering their development, such as the short life span of batteries, poor performance of start-up, and a short driving range. In order to resolve these problems, a hybrid power system based on photovoltaic (PV cells, supercapacitors, and batteries is proposed. This paper focuses on PV cells using a maximum power point track (MPPT system based on a BUCK chopper circuit. Moreover, a novel MPPT algorithm named sectional variable step climbing (SVSC algorithm was proposed. To validate the proposed system, two main experiments have been done. The first experiment showed that the MPP of PV cells was tracked perfectly by use of this photovoltaic power system. The second one showed that the efficiency of SVSC was higher than two existing MPPT methods, the climbing algorithm and the open-circuit voltage (OCV algorithm.

  12. DSP controlled filament power supply for 1 MW, 352.2 MHz klystron

    International Nuclear Information System (INIS)

    A digitally controlled current regulated 20 V, 25 A dc power supply employing IGBT based chopper is developed as the filament power supply for 1 MW, 352.2 MHz, Thales make TH 2089 klystron amplifier. The filament of this klystron is floating at cathode voltage of -100 kV dc, hence this power supply is kept on a floated platform and isolated through a suitable HV isolation transformer. Control and protection of this power supply is implemented through Texas make TMS320F2812 digital signal processor (DSP) and fibre optics based optical communication is adopted. Detailed simulation is carried out and a close match between simulated and experimental results was obtained, which are presented in this paper. The long term output current stability and peak to peak output current ripple of this power supply are found to be below 0.5 %. (author)

  13. A battery-powered high-current power supply for superconductors

    International Nuclear Information System (INIS)

    Since superconductors do not require voltages, a high-current power supply could run with low power if the voltage is sufficiently reduced. Even a battery-powered power supply could give as much as 2,000A for a superconductor. To demonstrate this hypothesis, a battery-powered 2,000A power supply was constructed. It uses an IGBT chopper and Schottky diode together with a specially arranged transformer to produce a high current with low voltage. Testing of 2,000A operation was performed for about 1.5 hr using 10 car batteries. Charging time for this operation was 8 hr. Ramping control was smooth and caused no trouble. Although the IGBT frequency ripple of 16.6 kHz was easily removed using a passive filter, spike noise remained in the output voltage. This ripple did not cause any trouble in operating a pancake-type inductive superconducting load. (author)

  14. Resolution kernels in time-of-flight neutron reflectometers

    International Nuclear Information System (INIS)

    Instrumental resolution functions must be taken into account when analysing Neutron Reflectometry data. These resolution functions are obtained by convolving the resolution kernels for the angular and wavelength components. In the past most data reduction and analysis processes have assumed that the overall resolution kernel is Gaussian in shape. Whilst this is the case for monochromatic reflectometers this is not true for those Time-Of-Flight (TOF) Neutron Reflectometers, such as Platypus which possess rectangular wavelength resolution distributions (a consequence of the disc chopper systems used). In such situations the resolution function is typically trapezoidal in shape. Here we detail how a more detailed description of the instrumental resolution function is calculated2. In addition, we outline the situations where the differences between the detailed and approximate resolution kernels become apparent, with the main effects being observed when the width of the resolution kernel is similar to the width of the features in the reflectivity curve.

  15. The multipurpose time-of-flight neutron reflectometer “Platypus” at Australia's OPAL reactor

    Science.gov (United States)

    James, M.; Nelson, A.; Holt, S. A.; Saerbeck, T.; Hamilton, W. A.; Klose, F.

    2011-03-01

    In this manuscript we describe the major components of the Platypus time-of-flight neutron reflectometer at the 20 MW OPAL reactor in Sydney, Australia. Platypus is a multipurpose spectrometer for the characterisation of solid thin films, materials adsorbed at the solid-liquid interface and free-liquid surfaces. It also has the capacity to study magnetic thin films using spin-polarised neutrons. Platypus utilises a white neutron beam ( λ=2-20 Å) that is pulsed using boron-coated disc chopper pairs; thus providing the capacity to tailor the wavelength resolution of the pulses to suit the system under investigation. Supermirror optical components are used to focus, deflect or spin-polarise the broad bandwidth neutron beams, and typical incident spectra are presented for each configuration. A series of neutron reflectivity datasets are presented, indicating the quality and flexibility of this spectrometer. Minimum reflectivity values of Platypus time-of-flight neutron reflectometer are presented.

  16. Transient behaviour of a ''beam loaded'' prebuncher cavity and linac structure

    International Nuclear Information System (INIS)

    They present the evaluation of the effect of the beam loading on the time response of a 3 GHz prebuncher cavity to the generator and to an input 120 deg chopped electron beam for two different cavity materials. The lumped-element representation of the cavity as a parallel RLC circuit is used which allows to compute also the sensitivity of the prebuncher voltage amplitude and phase with respect to beam current fluctuations. The analysis has been extended to the transient behaviour of a linac positioned after the prebuncher cavity. The consequences of the computation results on the application of a chopper-prebuncher system in a linac devoted to the MUH FEL experiment are discussed

  17. Transient behaviour of a ``beam loaded`` prebuncher cavity and linac structure

    Energy Technology Data Exchange (ETDEWEB)

    Messina, Giovanni; Picardi, Luigi; Ronsivalle, Concetta; Vignati, Angelo [ENEA, Centro Ricerche Frascati, Rome (Italy)

    1997-03-01

    They present the evaluation of the effect of the beam loading on the time response of a 3 GHz prebuncher cavity to the generator and to an input 120 deg chopped electron beam for two different cavity materials. The lumped-element representation of the cavity as a parallel RLC circuit is used which allows to compute also the sensitivity of the prebuncher voltage amplitude and phase with respect to beam current fluctuations. The analysis has been extended to the transient behaviour of a linac positioned after the prebuncher cavity. The consequences of the computation results on the application of a chopper-prebuncher system in a linac devoted to the MUH FEL experiment are discussed.

  18. Mechanisms based on piezoactuators

    Science.gov (United States)

    Claeyssen, Frank; Le Letty, Ronan; Barillot, Francois; Lhermet, Nicolas; Fabbro, H.; Guay, Philippe; Yorck, Mickael; Bouchilloux, Philippe

    2001-06-01

    In several fields (optics, space, aircraft, fluid control, biomedical, and manufacturing) there is a strong need for compact, robust and efficient positioning mechanisms that also offer high precision, short response times, low power consumption, low electromagnetic interference and multiple degrees of freedom. Piezoelectric actuators are generally good candidates for building such mechanisms. The products manufactured by Cedrat Recherche SA are piezoelectric actuators offering compact size, high deformation (up to 1%) and high stiffness. These actuators have successfully passed different qualification tests (air and space qualification, lifetime tests). They can easily be integrated in applications, as shown by examples of mechanisms taken from various fields: a super amplified actuator for a MRI biomedical device, a tip-tilt for mirrors, a chopper for X-ray diffraction, a helicopter flap mechanism and an XYZ stage for the AFM microscope of the MIDAS instrument of the ESA ROSETTA space mission.

  19. Optical dating of the Jingshuiwan Paleolithic site of Three Gorges, China

    Institute of Scientific and Technical Information of China (English)

    PEI Shuwen; ZHANG Jiafu; GAO Xing; ZHOU Liping; FENG Xingwu; CHEN Fuyou

    2006-01-01

    The Jingshuiwan Paleolithic site occupies the second terrace on the right bank of the Yangtze River. The lithic assemblage is characterized by choppers and scrapers made on pebbles and large flakes--the typical lithic industry of South China. Deposits of the site are mainly composed of fluvial sediments. Quartz grains extracted from these fluvial sediments from which the artifacts were uncovered were dated using the optically stimulated luminescence/single-aliquot regenerative-dose technique. The dating results show that ancient human activities at this site took place in the early Upper Pleistocene (ca. 70 ka). The successful age analysis of the Jingshuiwan site is considered as a major break- through in chronological analysis of Paleolithic open site in the Three Gorges region and even in South China. The dates obtained help to establish a more complete chronological framework of the Paleolithic cultural sequence in the region, and bear significant implications in studying modern human origins in China.

  20. A DC-Voltage-Balancing Circuit for a Five-Level Diode-Clamped PWM Inverter Intended for Motor Drives

    Science.gov (United States)

    Hasegawa, Kazunori; Akagi, Hirofumi

    This paper proposes a new dc-voltage-balancing circuit for a five-level diode-clamped inverter intended for a medium-voltage motor drive. This circuit consists of two unidirectional choppers and a single coupled inductor with two galvanically-isolated windings. The dc magnetic fluxes in the magnetic core, which are generated by the two windings, cancel out each other. Therefore, the inductor does not generate any dc-magnetic flux in the magnetic core. This makes the inductor compact by a factor of six compared to previously used balancing circuits containing two non-coupled inductors. Experimental results obtained from a 200-V 5.5-kW downscaled model verify that the dc mean voltages of the four split dc capacitors are balanced well under all operating conditions.

  1. Laser dismantling of PHWR spent fuel bundles and decladding of fuel pins in the highly radioactive hot cells

    International Nuclear Information System (INIS)

    Full text: For reprocessing of PHWR fuel, fuel bundles are at present chopped mechanically into small pieces of pins using high tonnage mechanical press before dissolution. The existing method of bundle dismantling is purely mechanical using very high force for chopping. A laser based automated bundle dismantling system is developed. In the system, end-plates of bundle, which holds the fuel pins together, are cut using Nd-YAG laser to separate the bundles into pins. In addition to pin separation, the pins are to be chopped into small pieces using a small mechanical chopper. Since the spent fuel is highly radioactive, all these operations are performed remotely in hot cells. Post irradiation examination also requires dismantling of bundles into pins so that they can select the pins for the further examinations. In both these applications laser dismantling remains the most. important step and this system has been developed and tested. This paper describes the experience gained during the development efforts

  2. Low Emittance Growth in a LEBT with Un-Neutralized Section

    Energy Technology Data Exchange (ETDEWEB)

    Prost, Lionel [Fermilab; Carneiro, Jean-Paul [Fermilab; Shemyakin, Alexander [Fermilab

    2016-06-01

    In a Low Energy Beam Transport line (LEBT), the emittance growth due to the beam's own space charge is typically suppressed by way of neutralization from either electrons or ions, which originate from ionization of the background gas. In cases where the beam is chopped, the neutralization pattern changes throughout the beginning of the pulse, causing the Twiss parameters to differ significantly from their steady state values, which, in turn, may result in beam losses downstream. For a modest beam perveance, there is an alternative solution, in which the beam is kept un-neutralized in the portion of the LEBT that contains the chopper. The emittance can be nearly preserved if the transition to the un-neutralized section occurs where the beam exhibits low transverse tails. This report discusses the experimental realization of such a scheme at Fermilab's PXIE, where low beam emittance dilution was demonstrated

  3. 3 MeV Test Stand commissioning report

    CERN Document Server

    Bellodi, Guilia; Andreassen, O; Comblin, J-F; Dimov, V; Lallement, J-B; Martin, C; Midttun, O; Ovalle, E; Raich, U; Roncarolo, F; Rossi, C; Scrivens, R; Vollaire, J; Yarmohammadi Satri, M; Zocca, Z

    2013-01-01

    Linac4 is a normal-conducting 160 MeV H- linear accelerator, presently under construction, that will replace the present 50 MeV Linac2 as injector of the CERN proton accelerator complex with the goal of increasing the LHC luminosity. The Linac4 front-end, composed of a 45 keV ion source, a Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) and a Medium Energy Beam Transport (MEBT) housing a beam chopper, was commissioned at the 3 MeV test stand area during the first half of 2013. This report gives details of the installation and operational systems used, describes the commissioning phases and measurements performed and summarizes the results that were finally achieved and the lessons learnt in the process.

  4. Prompt gamma neutron activation analysis as an active interrogation technique for nuclear materials

    International Nuclear Information System (INIS)

    Prompt gamma neutron activation analysis (PGAA) is proposed as an instant, non-destructive method for the analysis of fissile materials and fission products. Measurements by PGAA were made on technetium and uranium compounds, the latter with various enrichments. Measurements were carried out in thermal and cold neutron beams at the Budapest Research Reactor. A beam chopper was used to collect the delayed decay gamma radiation from short lived nuclides separately. Accurate partial gamma ray production cross-sections were determined with internal standardization for a set of prompt and decay gamma rays following neutron capture in 235U, 238U and 99Tc and compared to those from the literature. In the case of 235U fission, prompt gamma lines were also applied.These cross-sections can be used for non-destructive analyses of uranium and technetium and also for the determination of the enrichment of uranium by prompt gamma activation analysis and neutron activation analysis. (author)

  5. A Wind Farm Electrical Systems Evaluation with EeFarm-II

    Directory of Open Access Journals (Sweden)

    Jan Pierik

    2010-03-01

    Full Text Available EeFarm-II is used to evaluate 13 different electrical systems for a 200 MW wind farm with a 100 km connection to shore. The evaluation is based on component manufacturer data of 2009. AC systems are compared to systems with DC connections inside the wind farm and DC connection to shore. Two options have the best performance for this wind farm size and distance: the AC system and the system with a DC connection to shore. EeFarm-II is a user friendly computer program for wind farm electrical and economic evaluation. It has been built as a Simulink Library in the graphical interface of Matlab-Simulink. EeFarm-II contains models of wind turbines, generators, transformers, AC cables, inductors, nodes, splitters, PWM converters, thyristor converters, DC cables, choppers and statcoms.

  6. Automation and environment of a sample of the modernized installation YuMO

    International Nuclear Information System (INIS)

    New possibilities of the modernized installation YuMO due to automation of separate units are shown. Main unique devices due to modernization are presented. Advantages of the upgraded spectrometer are shown. The basic approaches to creation of control systems by executive mechanisms of spectrometers on the basis of their unification and standardization are formulated. Circuits of the block of management by step-by-step engines, the switchboard-amplifier of step-by-step motors, the circuit of the system of stabilization of the period and phase of the chopper, and the block diagram of the control system of executive mechanisms of the spectrometer YuMO are submitted. Main technical parameters of the basic original mechanical devices are given. (author)

  7. Attempt to visualize cavitation in nozzle chamber of diesel engine by neutron radiography

    International Nuclear Information System (INIS)

    Preliminary experiment using neutron radiography was attempted on visualization of cavitation (= cold boiling) of fuel flow inside the metallic nozzle chamber of diesel engine. Fuel ejection from a diesel-engine nozzle is dependent on the cavitation conditions in fuel flow, subjective to pressure change, were studied using a cooled CCD camera with electric shutter open and with the help of a synchronous chopper for neutron beams which enables to observe visualized flow at 0.5 mm width nozzle chamber, 1 mm diameter sac chamber, and 0.2 mm diameter nozzle hole in a diesel engine. Each images could be obtained with short exposure time from 100 μs to 1 mx. (S. Ohno)

  8. A battery-powered high-current power supply for superconductors

    CERN Document Server

    Wake, M; Suda, K

    2002-01-01

    Since superconductors do not require voltages, a high-current power supply could run with low power if the voltage is sufficiently reduced. Even a battery-powered power supply could give as much as 2,000A for a superconductor. To demonstrate this hypothesis, a battery-powered 2,000A power supply was constructed. It uses an IGBT chopper and Schottky diode together with a specially arranged transformer to produce a high current with low voltage. Testing of 2,000A operation was performed for about 1.5 hr using 10 car batteries. Charging time for this operation was 8 hr. Ramping control was smooth and caused no trouble. Although the IGBT frequency ripple of 16.6 kHz was easily removed using a passive filter, spike noise remained in the output voltage. This ripple did not cause any trouble in operating a pancake-type inductive superconducting load. (author)

  9. Laser extensometer

    Science.gov (United States)

    Stocker, P. J.; Marcus, H. L. (Inventor)

    1977-01-01

    A drift compensated and intensity averaged extensometer for measuring the diameter or other properties of a substantially cylindrical sample based upon the shadow of the sample is described. A beam of laser light is shaped to provide a beam with a uniform intensity along an axis normal to the sample. After passing the sample, the portion of the beam not striking said sample is divided by a beam splitter into a reference signal and a measurement signal. Both of these beams are then chopped by a light chopper to fall upon two photodiode detectors. The resulting ac currents are rectified and then divided into one another, with the final output being proportional to the size of the sample shadow.

  10. Neutron Spectra Near to a Temperature Discontinuity in Graphite

    International Nuclear Information System (INIS)

    Thermal neutron spectra have been measured on either side of a temperature discontinuity in a large graphite stack. The stack was fed with thermal neutrons from the source reactor LIDO. Spectra were measured by the time-of-flight method using a chopper, and also by integral activation techniques. Simple diffusion theory calculations considering two Maxwellian groups give as good agreement with the measured 'neutron temperature' distributions as multigroup transport theory. Direction-averaged spectra were calculated using the transport theory code WDSN, with 39 thermal energy groups. Results using heavy gas (mass 30 or 35) scattering kernels for graphite or realistic kernels based on the measured scattering law give agreement with the measured spectra to better than 10%. The measured spectra of fluxes in the direction of the neutron current were found to be dependent on the orientation of the graphite blocks since the mean free path of neutrons in graphite depends on its extrusion direction. (author)

  11. Proceedings of the workshop on 'possible scientific view from new neutron spectroscopy opportunities in J-PARC'

    International Nuclear Information System (INIS)

    At Materials and Life Science Experimental Facility (MLF) at J-PARC, three chopper spectrometers, AMATERAS, 4SEASONS and HRC have been constructed and a near-backscattering spectrometer, DNA is under construction. By combination of a high intensity neutron source at MLF and advanced technologies equipped, these spectrometers are expected to open new possibilities in scientific research using neutron inelastic and quasi-elastic scattering methods. In such circumstances, the workshop entitled 'Possible Scientific View from New Neutron Spectroscopy Opportunities in J-PARC' was held on 8-9, July 2009 at Ibaraki Quantum Beam Research Center. The purpose of the workshop is to discuss the recent hot research topics and possible investigations utilizing the novel spectrometers at MLF in the wide range of the research field such as solid state physics, chemistry, material science, softmatter science, biology and industrial applications. This report includes abstracts and materials of the presentations in the workshop. (author)

  12. Beam diagnostics measurements at 3 MeV of the LINAC4 H- beam at CERN

    CERN Document Server

    Zocca, F; Duraffourg, M; Focker, G J; Gerard, D; Kolad, B; Lenardon, F; Ludwig, M; Raich, U; Roncarolo, F; Sordet, M; Tan, J; Tassan-Viol, J; Vuitton, C; Feshenko, A

    2014-01-01

    As part of the CERN LHC injector chain upgrade, LINAC4 [1, 2] will accelerate H- ions to 160 MeV, replacing the old 50 MeV proton linac. The ion source, the Low Energy Beam Transfer (LEBT) line, the 3 MeV Radio Frequency Quadrupole and the Medium Energy Beam Transfer (MEBT) line hosting a chopper, have been commissioned in the LINAC4 tunnel. Diagnostic devices are installed in the LEBT and MEBT line and in a movable diagnostics test bench which is temporarily added to the MEBT exit. The paper gives an overview of all the instruments used, including beam current transformers, beam position monitors, wire scanners and wire grids for transverse profile measurements, a longitudinal bunch shape monitor and a slit-and-grid emittance meter. The instrumentation performance is discussed and the measurement results that allowed characterizing the 3 MeV beam in the LINAC4 tunnel are summarized.

  13. History and results of astro-nuclear experiment using Kyushu University tandem accelerator

    International Nuclear Information System (INIS)

    4He+12C → 16O+γ reaction at Ecm = 0.3 MeV plays a crucial role in nuclear synthesis in stars, but measurement of the total reaction cross section has not been succeeded yet in spite of many experiments in the world for about 45 year. We have been preparing for the measurement for about 20 years using Kyushu University tandem accelerator facility. For this experiment we have developed many original instruments and tools, for example, a windowless He gas target, acceleration-deceleration operation of the tandem accelerator, a long-time chopper for reaction recoils, ΔE-E counter using an ionization chamber. Making many attempts and faults till the final goal is important. We succeeded in the measurement at 1.5 MeV first in the world, and we are now challenging the next measurement at 1.2 MeV. (author)

  14. Analog front-end measuring biopotential signal with effective offset rejection loop.

    Science.gov (United States)

    Lim, Seunghyun; Kim, Hyunho; Song, Haryong; Cho, Dong-il Dan; Ko, Hyoungho

    2015-01-01

    This paper presents an analog front-end (AFE) IC design for recording biopotential signals. The AFE employs a capacitively coupled instrumentation amplifier to achieve a low-noise and high-common mode rejection ratio (CMRR) system. A ripple reduction loop is proposed to reduce the ripple generated by the up-modulating chopper. The low frequency noise is attenuated by an input AC coupling capacitor, and is attenuated again by a DC servo loop. The proposed AFE features a differential gain of 71 dB, and a CMRR of 89 dB, at 50 Hz. Furthermore, the proposed AFE can robustly acquire biopotential signals even in the presence of an input offset and ripples. PMID:26406095

  15. A Circadian and Cardiac Intraocular Pressure Sensor for Smart Implantable Lens.

    Science.gov (United States)

    Donida, Achille; Di Dato, Giuseppe; Cunzolo, Paolo; Sala, Marco; Piffaretti, Filippo; Orsatti, Paolo; Barrettino, Diego

    2015-12-01

    This paper presents a new system to measure the Intraocular Pressure (IOP) with very high accuracy (0.036 mbar) used for monitoring glaucoma. The system not only monitors the daily variation of the IOP (circadian IOP), but also allows to perform an spectral analysis of the pressure signal generated by the heartbeat (cardiac IOP). The system comprises a piezoresistive pressure sensor, an application-specific integrated circuit (ASIC) to read out the sensor data and an external reader installed on customized glasses. The ASIC readout electronics combines chopping modulation with correlated double sampling (CDS) in order to eliminate both the amplifier offset and the chopper ripple at the sampling frequency. In addition, programmable current sources are used to compensate for the atmospheric pressure ( 800-1200 mbar ) and the circadian component (± 7 mbar) thus allowing to read out the very weak cardiac signals (± 1.6 mbar) with a maximum accuracy of 0.036 mbar. PMID:26800549

  16. Intelligent Microstepping System for Bipolar Stepper Motor Control with Step and Direction Interface

    Directory of Open Access Journals (Sweden)

    Alexandru Morar

    2010-06-01

    Full Text Available The paper presents a intelligent system for stepper motor control in a microstepping mode, which was designed and performed with a specialized integrated circuit (L292, made by SGS-THOMSON Microelectronics Company. With an interface and an adequate software, L292 circuit can be used as a chopper in 2 or 4 quadrant. The microstepping control system improves the positioning accuracy and eliminates low speed ripple and resonance effects in a stepper motor electric drive. The same microstepping system is ideal for robotics, printers, plotters, X-Y-Z tables and can facilitate the construction of very sophisticated positioning control systems while significantly reducing component cost, board space, design time and systems cost.

  17. Tests of Modulated Intensity Small Angle Scattering in time of flight mode

    CERN Document Server

    Brandl, G; Carpenter, J; Crow, L; Robertson, L; Georgii, R; Böni, P; Bleuel, M

    2011-01-01

    We report results of tests of the MISANS technique at the CG-1D beamline at High Flux Isotope Reactor (HFIR), Oak Ridge National Laboratory (ORNL). A chopper at 40 Hz simulated a pulsed neutron source at the beamline. A compact turn-key MISANS module operating with the pulsed beam was installed and a well characterised MnSi sample was tested. The feasibility of application of high magnetic fields at the sample position was also explored. These tests demonstrate the great potential of this technique, in particular for examining magnetic and depolarizing samples, under extreme sample environments at pulsed sources, such as the Spallation Neutron Source (SNS) or the planned European Spallation Source (ESS).

  18. 36Chlorine accelerator mass spectrometry programme at BARC-TIFR pelletron accelerator. RSP-12

    International Nuclear Information System (INIS)

    Accelerator mass spectrometry (AMS) is an ultra sensitive means of counting individual atoms having sufficiently long half life and available in small amount. The 14 UD Pelletron Accelerator is an ideal machine to carry out AMS studies with heavy isotopes like 36Cl and 129I. Cosmogenic radio isotope 36Cl is widely being detected using AMS as it has got applications in ground water research, radioactive waste management, atmospheric 36Cl transport mechanism studies of Arctic Alpine ice core etc. As a part of the ongoing AMS programme at 14UD Pelletron Accelerator Facility, Mumbai, a segmented gas detector developed for identification of 36Cl was tested for performance. Recently a beam chopper required for this measurement has been developed. 36Cl measurements carried out to detect and measure the ratio of 36Cl to 35Cl in an irradiated sample and dated sample are reported in this paper

  19. Accelerator mass spectrometry programme at BARC-TIFR pelletron accelerator

    International Nuclear Information System (INIS)

    Accelerator based mass spectrometry (ABMs) is an ultra sensitive means of counting individual atoms having sufficiently long half life and available in small amount. The 14 U D Pelletron Accelerator is an ideal machine to carry out ABMs studies with heavy isotopes like 36Cl and 129I. Cosmogenic radio isotope 36Cl is widely being detected using ABMs as it has got applications in ground water research, radioactive waste management, atmospheric 36Cl transport mechanism studies of Arctic Alpine ice core etc. As a part of the ongoing ABMs programme at 14UD Pelletron Accelerator Facility at Mumbai, a segmented gas detector developed for identification of 36Cl was tested for performance. Recently a beam chopper required for this measurement has been developed. Further progress made in this programme is discussed in this paper. (author)

  20. Comparative study of energy conversion system dedicated to a small wind turbine

    International Nuclear Information System (INIS)

    This study presents a comparison of architectures and strategies of energy management dedicated to VAWT turbines such as Savonius. A Maximum Power Point Tracking must be implemented in order to optimize the energetic behavior. A torque or a speed control, or an indirect control of the DC bus current is possible. In the fact that the wind turbine characteristic is unknown, an operational research based on fuzzy logic is proposed. Aiming to minimize the cost of the static conversion structure, simple structures (diode bridge inverter, associated with DC-DC chopper) are analyzed and compared with a system based on a PWM Voltage Source Inverter. A test bench has been realized in the meantime as a system simulation. Comparisons of the provided energy are made for different wind speeds allowing to evaluate the performance of each structure and of the control strategies. (author)

  1. Frascati Tokamak transformer switching system

    International Nuclear Information System (INIS)

    Plasma ionization and heating, in the Frascati Tokamak, is obtained generating an emf along the plasma column, by switching the dc current flowing in the Tokamak transformer. 30 kA flowing in the 60 mH transformer inductance must be commutated into a resistance to generate 40 kV across the transformer itself. Studies and tests to solve this problem have been conducted, on different types of breakers, in cooperation between Tecnomasio Italiano Brown Boveri, Milan and Laboratori Gas Ionizzati, Frascati. Satisfactory results have finally been obtained using a DLF commercial air blast breaker in a chopper type circuit. A capacitor bank in parallel to the breaker is discharged immediately after the contacts separation and the arc in the switching element is extinguished at the first current zero. A saturable reactance in series with the breaker reduces the current decay rate to allow sufficient deionization time

  2. Inelastic neutron scattering and lattice dynamics of GaPO4

    Indian Academy of Sciences (India)

    R Mittal; S L Chaplot; A I Kolesnikov; C-K Loong; O D Jayakumar; S K Kulshreshtha

    2004-08-01

    We report here measurements of phonon spectrum and lattice dynamical calculations for GaPO4. The measurements in low-cristobalite phase of GaPO4 are carried out using high-resolution medium-energy chopper spectrometer at ANL, USA in the energy transfer range 0–160 meV. Semiempirical interatomic potential in GaPO4, previously determined using ab-initio calculations have been widely used in studying the phase transitions among various polymorphs. The calculated phonon spectrum using the available potential show fair agreement with the experimental data. However, the agreement between the two is improved by including the polarisability of the oxygen atoms in the framework of the shell model. The lattice dynamical models are also exploited for calculations of various thermodynamic properties of GaPO4.

  3. Some general reflections on open-quotes long pulseclose quotes neutron sources

    International Nuclear Information System (INIS)

    A long pulse spallation neutron source (LPSS) having about 20 times more time average thermal flux than its short pulse counterpart (SPSS) at the same proton beam power and featuring a pronounced time structure not available on CW sources (CWNS) of equal time average flux can in principle host instruments typical for both classes of facilities. While the need for additional choppers introduces some restrictions on inverted time of flight techniques typical for SPSS and high incident neutron energies are not easier to use on LPSS than on CWNS, taking advantage of the pulsed nature of the neutron flux can enhance significantly the performance of direct time of flight instruments and of crystal spectrometers or diffractometers. In the paper some of the options are reviewed in a general manner and criteria are discussed which can be used to optimize the performance enhancement

  4. Design and manufacture of neutron time of flight spectrometer on China Advanced Research Reactor

    International Nuclear Information System (INIS)

    The cold or thermal neutron energy spectra on China Advanced Research Reactor (CARR) could be directly measured by neutron time of flight spectrometer. Spectrometer structure and selected parameters of its key components were introduced. The impact of chopper slit and flux limit slit on neutron counts and pulse width was analyzed. The formulas of neutron counts and pulse width which were dependent on neutron wavelength were acquired. According to neutron energy spectrum measurement requirement for high fluence rate neutron beam, low-sensitivity detector, detector flux limit slit and multi-channel scaler for data acquisition were selected. These would ensure that the count loss rate was less than 0.5%. Electronics framework of detection system was designed and the total resolution time was 22.15-29.46 μs. (authors)

  5. A new guide concept for a homogenous neutron beam without direct line of sight

    Energy Technology Data Exchange (ETDEWEB)

    Cussen, Leo D., E-mail: ldc_0@yahoo.com.au [Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); ESS Design Update Programme (Germany); Krist, Thomas, E-mail: krist@helmholtz-berlin.de [Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Lieutenant, Klaus, E-mail: klaus.lieutenant@helmholtz-berlin.de [Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); ESS Design Update Programme (Germany)

    2015-03-21

    Neutron guide tubes are used to transport neutrons efficiently from the source to distant instruments. Ballistic neutron guides, which have an expanding section in the beginning and a contracting section in the end, reduce the total number of reflections and improve transport efficiency in long guides. Long pulse spallation sources like the European Spallation Source require very long guides. Challenges in ballistic guide design are imposed by the need for small virtual sources and the prevention of direct line of sight to the source, because both tend to produce inhomogeneous beam distributions, and the latter reduces transmission for short wavelengths. This article describes a novel ballistic guide design based on elliptic profiles. It incorporates a carefully positioned and angled kink to avoid line of sight to the source and a narrow point to position a chopper. This design reduces the number of reflections in long guides and improves transmission, especially at short wavelengths, compared to other solutions avoiding a direct line of sight.

  6. Molecular beam sampling system with very high beam-to-background ratio: The rotating skimmer concept

    International Nuclear Information System (INIS)

    A novel method of reducing the background pressure in a vacuum system used for sampling a molecular beam from a high pressure region is presented. A triple differential pumping stage is constructed with a chopper with rotating skimmer within the first pumping stage, which serves effectively as a valve separating periodically the vacuum system from the ambient environment. The mass spectrometry measurement of the species in the molecular beam show an excellent beam-to-background ratio of 14 and a detection limit below 1 ppm. The potential of this method for detection of low density reactive species in atmospheric pressure plasmas is demonstrated for the detection of oxygen atoms generated in an atmospheric pressure microplasma source.

  7. A new regional group of the lower paleolithic in Brittany (France), recently dated by electron spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Monnier, J.L.; Hinguant, S.; Gebhardt, A.; Marguerie, D.; Molines, N.; Morzadec, H. (Rennes-1 Univ., 35 (France)); Hallegouet, B. (Brest Univ., 29 (France)); Laurent, M.; Auguste, P.; Bahain, J.J.; Falgueres, C.; Yokoyama, Y. (Institut de Paleontologie, 75 - Paris (France))

    1994-07-07

    ESR dates obtained at Menez-Dregan 1 (Brittany, France) focus interest on this Lower Paleolithic site and demonstrate that the preserved anthropic combustion structures are among the oldest known in the world. It allows the dating not only of the little known 'Colombanian Group' (it is an 'archaic' original group characterized by many choppers and very few handaxes, different from the Acheulian), but also, for the first time, of the old beaches on the southern coast of Brittany. Preserved bone remains are also very infrequent in Palaeolithic sites of Western France. The dating of the paleolithic layer at the top of the third fossil beach can be connected with isotopic stage 11 or the beginning of isotopic stage 10; it shows that the age of the geological and archaeological layers of Menez-Dregan 1 is probably between 350.000 and 500.000 years.

  8. Performance Analysis of a Grid connected Wind Energy system

    Directory of Open Access Journals (Sweden)

    Manju Khare

    2016-07-01

    Full Text Available This paper is concerned with the study of a small wind generation system used for battery charging. A topology that aims at the exploitation of maximum energy from the generator, generated at low speed is proposed. The characteristics of the wind turbine and the generator are discussed, providing the overview of the system modeling. Simulation tests of the system are obtained using MATLAB/SIMULINK. We adopt compact permanent magnet type synchronous generator, which doesn’t need exciting current, and step- up /down buck-boost chopper to wind power generating system of a few kW output with rotor speed sensor. In addition, we employ rectifier circuit using Diode Bridge instead of AC-DC converter with PWM method and a battery charging system. Using these methods we achieve a simple wind power generation system

  9. Near infrared multicolor photometry of late type stars with the balloon borne astronomical telescope BAT-1

    International Nuclear Information System (INIS)

    A new star follower has been developed for observing the near infrared emission of late type stars. The sensor of the follower consists of a semicircular rotating sector and a photomultiplier. The practical accuracy of the angle of tracing was about 1 minute. A photometer was installed at the focus point of the main telescope. The infrared photometer consists of a filter turret, a chopper, an infrared detector and a synchronous amplifier. Five flights of balloons were made since September 13, 1974. The height of the flights was about 25 km. The type of observed spectra ranges from A0 to M6. The results of analysis was compared with the atmospheric model by Tsuji. The physical parameters, such as effective temperature, logarithm of surface gravity and velocity of turbulent flow, of late type stars (K5 - M6) were determined. (Kato, T.)

  10. New developments of TOF neutron diffraction at the IBR-2 pulsed reactor

    International Nuclear Information System (INIS)

    Development of high-resolution RTOF Fourier technique for powder neutron diffraction studies is being continued at the IBR-2 pulsed reactor in Dubna. Besides some technical improvements in the operating HRFD instrument, a new dedicated instrument, Fourier Strain Diffractometer (FSD), for investigation of residual stresses in bulk materials has been constructed at IBR-2 in 1999. With a new HRFD Fourier chopper smaller than 10 μs TOF contribution in a resolution function was obtained in the experiment with perfect Si single crystal. A series of diffraction experiments with the beams from a new methane cold neutron moderator installed at the IBR-2 in 1999 is discussed. A comparison with the results obtained with the conventional water comb-like moderator shows that for various types of experiments, which are performed at HRFD and DN-2 diffractometers, the methane cold neutron source provides better conditions. (author)

  11. Installation and first operation of the International Fusion Materials Irradiation Facility injector at the Rokkasho site

    Energy Technology Data Exchange (ETDEWEB)

    Gobin, Raphael, E-mail: rjgobin@cea.fr; Bogard, Daniel; Bolzon, Benoit; Bourdelle, Gilles; Chauvin, Nicolas; Chel, Stéphane; Girardot, Patrick; Gomes, Adelino; Guiho, Patrice; Harrault, Francis; Loiseau, Denis; Lussignol, Yves; Misiara, Nicolas; Roger, Arnaud; Senée, Franck; Valette, Matthieu [Commissariat à l’Energie Atomique et aux Energies Alternatives, CEA/Saclay, DSM/IRFU, 91191 Gif/Yvette (France); Cara, Philippe; Duglué, Daniel; Gex, Dominique [Fusion for Energy, BFD Department, Garching (Germany); Okumura, Yoshikazu [IFMIF/EVEDA Project Team, Obuchi-Omotedate, 2-166, Rokkasho, Aomori (Japan); and others

    2016-02-15

    The International Fusion Materials Irradiation Facility (IFMIF) linear IFMIF prototype accelerator injector dedicated to high intensity deuteron beam production has been designed, built, and tested at CEA/Saclay between 2008 and 2012. After the completion of the acceptance tests at Saclay, the injector has been fully sent to Japan. The re-assembly of the injector has been performed between March and May 2014. Then after the check-out phase, the production of the first proton beam occurred in November 2014. Hydrogen and deuteron beam commissioning is now in progress after having proceeded with the final tests on the entire injector equipment including high power diagnostics. This article reports the different phases of the injector installation pointing out the safety and security needs, as well as the first beam production results in Japan and chopper tests. Detailed operation and commissioning results (with H{sup +} and D{sup +} 100 keV beams) are reported in a second article.

  12. Measurement of free neutron lifetime by electron decay detection with a migration chamber

    International Nuclear Information System (INIS)

    In this study, the different aspects of the realization of the experimental setup are successively described: creation of a pulsed monochromatic neutron beam, design and construction of a detector for neutron decay electrons, development of electronics and of the data acquisition system, measurement of the helium-3 density in a gaseous mixture. A mechanical system called double chopper and a monochromator crystal are used to obtain neutron bursts with a length of about 28 cm and a velocity of 846 m/s. The electron detector is a time projection chamber (TPC) filled at atmospheric pressure with a helium-4 (93%), helium-3 (10-5%) and carbon dioxide (7%) mixture. The problems encountered during the data acquisition with the neutron beam and preliminary results from analysis are also presented

  13. Special and innovative aspects of the GTC M2 drive mechanism

    Science.gov (United States)

    Garcia, Enrique; Zago, Lorenzo; Gallieni, Daniele

    2003-02-01

    The paper presents some special, innovative and technological aspects of the secondary mirror mechanism for the GTC 10.8-m telescope, such as: The dual control loop of the hexapod actuators, which provides the GTC M2 alignment system with an absolute accuracy better than a few microns, and a resolution as low as 200 nm. The particular design of the hexapod flexure joints, which ensures frictionless joints without backlash, while effectively limiting the travel of the hexapod to the desired range only. The locking devices, based on an original rotating cam principle, which ensure the safe locking of the M2 support to the hexapod lower plate when the chopper function is not utilized. CuBe flexure parts have been manufactured by Electrodischarge Machining (EDM), and heat treated for maximum strength and fatigue load. A systematic approach to the Reliability, Maintainability and Safety aspects, aimed at ensuring the operational feasibility of the mechanism along its life cycle.

  14. Magnetic model for Mn2La2 developed from spectroscopic studies with inelastic neutron scattering and frequency-domain Fourier-transform THz EPR

    International Nuclear Information System (INIS)

    Molecular nanomagnets which contain several magnetic centers with a large single-ion magnetic anisotropy are of general interest, because they could lead to interesting phenomena such as single-molecule magnet (SMM) behavior. We performed spectroscopic experiments on Mn2La2 using inelastic neutron scattering at the direct time-of-flight disc chopper spectrometer IN5 at ILL and the newly developed frequency-domain Fourier-transform THz EPR at BESSY. Based on the experimental results a magnetic model has been developed. It is discussed why no SMM behavior was observed, even though Mn2La2 exhibits a remarkably high energy barrier of about 37 K for spin relaxation. Furthermore our results can be applied to analogous clusters, with the diamagnetic LaIII ions replaced by magnetic rare earth ions.

  15. Magnetic model for Mn{sub 2}La{sub 2} developed from spectroscopic studies with inelastic neutron scattering and frequency-domain Fourier-transform THz EPR

    Energy Technology Data Exchange (ETDEWEB)

    Milazzo, R.; Nehrkorn, J.; Stuiber, S.; Waldmann, O. [Physikalisches Institut, Universitaet Freiburg (Germany); Akhtar, M.N.; Lan, Y.; Powell, A.K. [Institut fuer Anorganische Chemie, Universitaet Karlsruhe, KIT (Germany); Mutka, H. [Institut Laue Langevin, Grenoble (France); Dreiser, J. [Swiss Light Source, Paul Scherrer Institut (Switzerland); Schnegg, A. [Helmholtz-Zentrum Berlin, Institut fuer Silizium-Photovoltaik (Germany); Holldack, K. [Helmholtz-Zentrum Berlin, Institut fuer Synchrotonstrahlung (Germany)

    2011-07-01

    Molecular nanomagnets which contain several magnetic centers with a large single-ion magnetic anisotropy are of general interest, because they could lead to interesting phenomena such as single-molecule magnet (SMM) behavior. We performed spectroscopic experiments on Mn{sub 2}La{sub 2} using inelastic neutron scattering at the direct time-of-flight disc chopper spectrometer IN5 at ILL and the newly developed frequency-domain Fourier-transform THz EPR at BESSY. Based on the experimental results a magnetic model has been developed. It is discussed why no SMM behavior was observed, even though Mn{sub 2}La{sub 2} exhibits a remarkably high energy barrier of about 37 K for spin relaxation. Furthermore our results can be applied to analogous clusters, with the diamagnetic La{sup I}II ions replaced by magnetic rare earth ions.

  16. Recent Progress with the KWISP Force Sensor

    CERN Document Server

    Cantatore, G; Hoffmann, D.H.H.; Karuza, M.; Semertzidis, Y.K.; Zioutas, K.

    2015-01-01

    The KWISP opto-mechanical force sensor has been built and calibrated in the INFN Trieste optics laboratory and is now under off-beam commissioning at CAST. It is designed to detect the pressure exerted by a flux of solar Chameleons on a thin (100 nm) Si$_3$N$_4$ micromembrane thanks to their direct coupling to matter. A thermally-limited force sensitivity of $1.5 \\cdot 10^{-14}~\\mbox{N}/\\sqrt{\\mbox{Hz}}$, corresponding to $7.5 \\cdot 10^{-16}~\\mbox{m}/\\sqrt{\\mbox{Hz}}$ in terms of displacement, has been obtained. An originally developed prototype chameleon chopper has been used in combination with the KWISP force sensor to conduct preliminary searches for solar chamaleons.

  17. Automation and Environment of a Sample of the Modernized Installation YuMO

    CERN Document Server

    Kuklin, A I; Kirilov, A S; Islamov, A H; Petukhova, N V; Utrobin, P K; Kovalev, Yu S; Gordeliy, V I

    2004-01-01

    New possibilities of the modernized installation YuMO due to automation of separate units are shown. Main unique devices due to modernization are presented. Advantages of the upgraded spectrometer are shown. The basic approaches to creation of control systems by executive mechanisms of spectrometers on the basis of their unification and standardization are formulated. Circuits of the block of management by step-by-step engines, the switchboard-amplifier of step-by-step motors, the circuit of the system of stabilization of the period and phase of the chopper, and the block diagram of the control system of executive mechanisms of the spectrometer YuMO are submitted. Main technical parameters of the basic original mechanical devices are given.

  18. Basic Design Report of DC-TOF Inelastic Neutron Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    So, Ji Yong; Park, Je Geun; Moon, Myung Kook; Cho, Sang Jin; Choi, Yung Hyun; Lee, Chang Hee

    2006-04-15

    We made Basic designs of neutron guide, choppers, and detectors in order to optimize the design parameters of DC-TOF to be built in the HANARO Cold Neutron Guide Hall. In addition, we calculated the expected performance of DC-TOF using Monte Carlo simulations and evaluated the properties of neutron beam. Based on the results we obtained, we have compared the expected performance of the DC-TOF with those of existing instruments overseas. In conclusion, we believe that we will be able to construct the DC-TOF at HANARO as one of the best instruments of its kinds and it will become an invaluable instrument to researchers in the related field.

  19. A New approach for the data acquisition system of the cairo fourier diffractometer

    International Nuclear Information System (INIS)

    The present work deals with a new approach for the reverse time of flight (RTOF) analysis of the diffraction spectra. The approach is based on the same RTOF concept used for the design of a separate RTOF analyzer and applies, for data acquisition, a special interface card and software program installed in a PC computer, to perform the cross-correlation functions between the three signals received from the chopper decoder, detector and the pulsed neutron source respectively. The new approach have been realized for use with a Fourier diffractometer facility based on the RTOF concept. It has been found from test measurements performed with the high resolution Fourier diffractometer (HRFD) at the IBR-2 reactor (JINR, Dubna) that the new approach can successfully replace the RTOF analyzer

  20. Optical alignment and testing of the Diffuse IR Background Experiment IR cryogenic telescope

    Science.gov (United States)

    Wood, H. John

    1989-01-01

    Diffuse Infrared Background Experiment (DIRBE) optical alignment and testing methods are discussed. Using strobe videography, vibration and performance testing of a 32 hz tuning-fork chopper was carried out. The Cosmic Background explorer satellite provides improved microwave and IR all-sky maps of the cosmic background radiation from a polar orbit. A liquid helium cryostat houses the DIRBE and the Far IR Absolute Spectrophotometer (FIRAS) instruments at a temperature of 2 K. Differential MicRowave Radiometers (DMRs) provide large scale maps of anisotropy of the 3 K background at wavelengths of 3.3, 5.7, and 9.6 mm. The DIRBE telescope is an IR photometric instrument with 10 wavelength bands between 1 and 300 microns, designed to measure radiation from the epoch of galaxy formation. Stringent stray light requirements mean that the DIRBE flight instrument has to be built and tested in a class 100 environment.

  1. Installation and first operation of the International Fusion Materials Irradiation Facility injector at the Rokkasho site

    International Nuclear Information System (INIS)

    The International Fusion Materials Irradiation Facility (IFMIF) linear IFMIF prototype accelerator injector dedicated to high intensity deuteron beam production has been designed, built, and tested at CEA/Saclay between 2008 and 2012. After the completion of the acceptance tests at Saclay, the injector has been fully sent to Japan. The re-assembly of the injector has been performed between March and May 2014. Then after the check-out phase, the production of the first proton beam occurred in November 2014. Hydrogen and deuteron beam commissioning is now in progress after having proceeded with the final tests on the entire injector equipment including high power diagnostics. This article reports the different phases of the injector installation pointing out the safety and security needs, as well as the first beam production results in Japan and chopper tests. Detailed operation and commissioning results (with H+ and D+ 100 keV beams) are reported in a second article

  2. Embedded software for the CEBAF RF Control Module

    International Nuclear Information System (INIS)

    The CEBAF accelerator control system employs a distributed computer strategy. As part of this strategy, the RF control sub-system uses 342 RF Control Modules, one for each of four warm section beam forming cavities (i.e., choppers, buncher, capture) and 338 superconducting accelerating cavities. Each control module has its own microprocessor, which provides local intelligence to automatically control over 100 parameters, while keeping the user interface simple. The microprocessor controls analog and digital I/O, including the phase and gradient section, high power amplifier (HPA), and interlocks. Presently, the embedded code is used to commission the 14 RF control modules in the injector. This paper describes the operational experience of this complex real-time control system

  3. Measurement of proton momentum distributions using a direct geometry instrument

    International Nuclear Information System (INIS)

    We report the results of inelastic neutron scattering measurements on bulk water and ice using the direct geometry SEQUOIA chopper spectrometer at the Spallation Neutron Source (USA), with incident energy Ei= 6 eV. In this set up the measurements allow to access the Deep Inelastic Neutron Scattering regime. The scattering is centred at the proton recoil energy given by the impulse approximation, and the shape of the recoil peak conveys information on the proton momentum distribution in the system. The comparison with the performance of inverse geometry instruments, such as VESUVIO at the ISIS source (UK), shows that complementary information can be accessed by the use of direct and inverse geometry instruments. Analysis of the neutron Compton profiles shows that the proton kinetic energy in ice at 271 K is larger than in room temperature liquid water, in agreement with previous measurements on VESUVIO

  4. Enhancement of transient stability by fuzzy logic-controlled SMES considering communication delay

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Mohd Hasan; Wu, Bin [Dept. of Electrical and Computer Engineering, Ryerson University, 245 Church Street, Toronto, Ontario (Canada); Park, Minwon; Yu, In-Keun [Dept. of Electrical Engineering, Changwon National University, Changwon, Gyeongnam 641-773 (Korea); Murata, Toshiaki; Tamura, Junji [Dept. of Electrical and Electronic Engineering, Kitami Institute of Technology, 165 Koen-cho, Kitami, Hokkaido 090-8507 (Japan)

    2009-09-15

    This paper presents a fuzzy logic-controlled superconducting magnetic energy storage (SMES) for the enhancement of transient stability in a multi-machine power system. The control scheme of SMES is based on a pulse width modulation (PWM) voltage source converter (VSC) and a two-quadrant DC-DC chopper using gate-turn-off (GTO) thyristor. Total kinetic energy deviation (TKED) of the synchronous generators is used as the fuzzy input for SMES control. Communication delays introduced in online calculation of the TKED are considered for the actual analysis of transient stability. Global positioning system (GPS) is proposed for the practical implementation of the calculation of the TKED. Simulation results of balanced fault at different points in a multi-machine power system show that the proposed fuzzy logic-controlled SMES is an effective device for transient stability enhancement of multi-machine power system. Moreover, the transient stability performance is effected by the communication delay. (author)

  5. Tests of modulated intensity small angle scattering in time of flight mode

    International Nuclear Information System (INIS)

    We report results of tests of the MISANS technique at the CG-1D beamline at the High Flux Isotope Reactor (HFIR), Oak Ridge National Laboratory (ORNL). A chopper at 40 Hz simulated a pulsed neutron source at the beamline. A compact turn-key MISANS module operating with the pulsed beam was installed and a well characterized MnSi sample was tested. The feasibility of application of high magnetic fields at the sample position was also explored. These tests demonstrate the great potential of this technique, in particular for examining magnetic and depolarizing samples, under extreme sample environments at pulsed sources, such as the Spallation Neutron Source (SNS) or the planned European Spallation Source (ESS).

  6. Calculation of slip energy recovery induction motor drive behavior using the equivalent circuit

    Energy Technology Data Exchange (ETDEWEB)

    Pillay, P. (Univ. of New Orleans, LA (United States). Dept. of Electrical Engineering); Refoufi, L. (Inst. National D' Electricite et d' Electronique, Boumerdes (Algeria))

    A transformer-type equivalent circuit model for the calculation of the steady state performance of a slip energy recovery induction motor drive with a step down chopper in the dc link is described. Experimental data of rms currents, power, reactive power and overall efficiency satisfactorily correlate with calculations over most of the operating speed range. Also, detailed calculations of rotor, stator and supply harmonic currents due to the rectifier and inverter actions are performed using the conventional version of the equivalent circuit. The computed and measured instantaneous current waveforms show satisfactory agreement except at a slip of 1/6 where significant deviations appear. This effect is adequately catered for by using a more rigorous model.

  7. The SOFIA Observatory at the Start of Routine Science Operations : Mission capabilities and performance

    CERN Document Server

    Temi, Pasquale; Young, Erick; Adams, Joseph D; Adams, Sybil; Andersson, B -G; Becklin, Eric E; Boogert, Adwin; Brewster, Rick; Burgh, Eric; Cobleigh, Brent R; Culp, Steven; De Buizer, Jim; Dunham, Edward W; Engfer, Christian; Ediss, Geoffrey; Fujieh, Maura; Grashuis, Randy; Gross, Michael; Harmon, Edward; Helton, Andrew; Hoffman, Douglas; Homan, Jeff; Hutwohl, Michael; Jakob, Holger; Jensen, Stephen C; Kaminski, Charles; Kozarsky, Daniel; Krabbe, Alfred; Klein, Randolf; Lammen, Yannick; Lampater, Ulrich; Latter, William B; Le, Jeanette; McKown, Nancy; Melchiorri, Riccardo; Meyer, Allan W; Miles, John; Miller, Walter E; Miller, Scott; Moore, Elizabeth; Nickison, Donald J; Opshaug, Kortney; Pfueller, Enrico; Radomski, James; Rasmussen, John; Reach, William; Reinacher, Andreas; Roellig, Thomas L; Sandell, Goran; Sankrit, Ravi; Savage, Maureen L; Shenoy, Sachindev; Schonfeld, Julie E; Shuping, Ralph Y; Smith, Erin C; Talebi, Ehsan; Teufel, Stefan; Tseng, Ting C; Vacca, William D; Vaillancourt, John; Van Cleve, Jeffrey E; Wiedemann, Manuel; Wolf, Jurgen; Zavala, Eddie; Zeile, Oliver; Zell, Peter T; Zinnecker, Hans

    2014-01-01

    The Stratospheric Observatory for Infrared Astronomy (SOFIA) has recently concluded a set of engineering flights for Observatory performance evaluation. These in-flight opportunities are viewed as a first comprehensive assessment of the Observatory's performance and are used to guide future development activities, as well as to identify additional Observatory upgrades. Pointing stability was evaluated, including the image motion due to rigid-body and flexible-body telescope modes as well as possible aero-optical image motion. We report on recent improvements in pointing stability by using an active mass damper system installed on the telescope. Measurements and characterization of the shear layer and cavity seeing, as well as image quality evaluation as a function of wavelength have also been performed. Additional tests targeted basic Observatory capabilities and requirements, including pointing accuracy, chopper evaluation and imager sensitivity. This paper reports on the data collected during these flights ...

  8. Rf capture studies for injection into a synchrotron

    International Nuclear Information System (INIS)

    The capture process for a rapid cycling protron synchrotron is studied by numerical simulation. The rf-programming is optimized to allow efficient capture such that minimum particle losses and reasonable capture voltage are attained. The total capture time is constrained to be less than 700 μseconds. Two methods of trapping the injected beam by the synchrotron rf system are examined: by stationary adiabatic capture and by synchronous injection in a standing bucket of the ring. In the adiabatic method, the non-linear function of Lilliequist and Symon is employed. The simulation allows the ''tracking back'' of the original distribution of any set of particles, in particular of those not captured at a given time, which is useful in studying injection alternatives such as shaping the phase-space density prior to injection. The simulation results will be used to design a chopper system to facilitate loss-free injection

  9. Neutron polarizing set-up of the Sofia IRT research reactor

    International Nuclear Information System (INIS)

    Neutron polarizing set-up of one of the horizontal beam tubes of the IRT-200 research reactor of the Bulgarian Institute of Nuclear Research and Nuclear Energy is presented. Neutron mirrors are extensively used in an effort to compensate the moderate reactor beam intensity by the high reflected intensity and wide-band transmittance of the mirror neutron guides. Time-to-flight technique using a slotted neutron absorbing chopper with a horizontal rotation axis has been applied to obtain the exit neutron spectra. Beam polarization and flipping ratios have been determined. Cadmium ratio in the polarized beam has been found almost 104 and the average polarization has been measured to be higher than 96%. 3 figs, 3 refs

  10. THE SOFIA OBSERVATORY AT THE START OF ROUTINE SCIENCE OPERATIONS: MISSION CAPABILITIES AND PERFORMANCE

    International Nuclear Information System (INIS)

    The Stratospheric Observatory for Infrared Astronomy (SOFIA) has recently concluded a set of engineering flights for observatory performance evaluation. These in-flight opportunities are viewed as the first comprehensive assessment of the observatory's performance and are used to guide future development activities, as well as to identify additional observatory upgrades. Pointing stability was evaluated, including the image motion due to rigid-body and flexible-body telescope modes as well as possible aero-optical image motion. We report on recent improvements in pointing stability by using an active mass damper system installed on the telescope. Measurements and characterization of the shear layer and cavity seeing, as well as image quality evaluation as a function of wavelength have also been performed. Additional tests targeted basic observatory capabilities and requirements, including pointing accuracy, chopper evaluation, and imager sensitivity. This paper reports on the data collected during these flights and presents current SOFIA observatory performance and characterization

  11. Comparative study of energy conversion system dedicated to a small wind turbine; Etude comparative de chaines de conversion d'energie dediees a une eolienne de petite puissance

    Energy Technology Data Exchange (ETDEWEB)

    Mirecki, A

    2005-07-01

    This study presents a comparison of architectures and strategies of energy management dedicated to VAWT turbines such as Savonius. A Maximum Power Point Tracking must be implemented in order to optimize the energetic behavior. A torque or a speed control, or an indirect control of the DC bus current is possible. In the fact that the wind turbine characteristic is unknown, an operational research based on fuzzy logic is proposed. Aiming to minimize the cost of the static conversion structure, simple structures (diode bridge inverter, associated with DC-DC chopper) are analyzed and compared with a system based on a PWM Voltage Source Inverter. A test bench has been realized in the meantime as a system simulation. Comparisons of the provided energy are made for different wind speeds allowing to evaluate the performance of each structure and of the control strategies. (author)

  12. Experimental research on spectrum and imaging of continuous-wave terahertz radiation based on interferometry

    Science.gov (United States)

    Lu, Tie-Lin; Yuan, Hui; Kong, Ling-Qin; Zhao, Yue-Jin; Zhang, Liang-Liang; Zhang, Cun-Lin

    2016-08-01

    A system for measuring terahertz spectrum is proposed based on optical interferometer theory, and is experimentally demonstrated by using a backward-wave oscillator as the terahertz source. A high-resolution, high-precision interferometer is constructed by using a pyroelectric detector and a chopper. The results show that the spectral resolution is better than 1 GHz and the relative error of frequency is less than 3%. The terahertz energy density distribution is calculated by an inverse Fourier transform and tested to verify the feasibility of the interferometric approach. Two kinds of carbon-fiber composites are imaged. The results confirm that the interferometer is useful for transmission imaging of materials with different thickness values. Project supported by the National Natural Science Foundation of China (Grant Nos. 61377109 and 11374007).

  13. A neutron guide installation status and its first performance test result at KAERI

    Science.gov (United States)

    Cho, S. J.; Cho, Y. G.; Lee, C. H.; Lee, K. H.; Kim, K. P.

    2011-04-01

    A neutron guide system that includes neutron guides, a main shutter, and a vacuum system was successfully installed at the HANARO research reactor of the Korea Atomic Energy Research Institute (KAERI) last year, and is now operating with 5 cold neutron instruments. The neutron flux and spectrum were measured by using gold wire and a disc chopper. The total measured neutron fluxes for various position are about 10-25% lower than the calculated fluxes, which is probably caused by neutron guide misalignment, larger gap between neutron guides, low reflectivity, imperfect cold neutron source data, and so on. But the measured neutron fluxes of the neutron guides are very high. The status of the neutron guide installation and its first performance test result is described in this paper.

  14. REFSANS. A novel reflectometer for analyses of liquid and soft surfaces at the new research reactor FRM-II in Munich/Germany

    International Nuclear Information System (INIS)

    Complete text of publication follows. The new reflectometer REFSANS is designed for investigating surfaces and phase boundaries of liquid and soft samples and offers new perspectives for analysing lateral inhomogeneities. A time-of-flight operation modus together with a sophisticated beam guiding system allow for complete analyses without any sample movement. The neutron flux on the sample can be adjusted to the required resolution by means of a multi-disk chopper (2%<Δλ/λ<15%). Off-specular scattering is efficiently detected by means of a large position sensitive area detector (active area about 500 mm x 400 mm) with a high spatial resolution. A novel beam guiding system allows for analysing evanescent small-angle scattering resulting from rather small lateral inhomogeneities. REFSANS is expected to be put into operation at the new research reactor FRM-II in Munich/Germany in 2001. (author)

  15. TOSCA incoherent inelastic neutron spectrometer. Progress and results

    International Nuclear Information System (INIS)

    The back-scattering part (phase I) of the new incoherent inelastic neutron spectrometer, TOSCA, replacing the old TFXA, has been successfully installed at the ISIS pulsed neutron spallation source. The results, owing to the much larger detector area, show a significant enhancement of the counting rate and a slight improvement of the low energy resolution. In spring 2000 the forward scattering bank (phase II) will be completed and, during the final installation, the whole instrument will be moved from the present 12 m of primary flight path to 17 m. This will result in a large improvement of the overall resolution (from 2-3% to 1-1.5% of the energy transfer). In addition, a chopper will be added in order to avoid neutron frame overlap and to reduce the fast neutron background. (author)

  16. Semiconductor device models for circuit simulation power electronics; Modeles de composants semiconducteurs pour la simulation des circuits en electronique de puissance

    Energy Technology Data Exchange (ETDEWEB)

    Berraies, M.O.

    1998-09-10

    In this thesis, an alternative strategy based on a regional approach to modeling and a new partition of the model library in the simulation is proposed. The main objective is to substitute for the usual concept of `one device, on model` that of an adaptable assembly of a limited number of submodels associated with well-identified regions of semiconductor structures. In other words, the library will only contain the primitive building-blocks of the power device models. This strategy guarantees the compatibility of the various semiconductor models in terms of physical concepts, validity domain, accuracy, homogeneity of parameter identification procedures, similarly of implementation in the simulator. This approach has been applied to PIN diodes and IGBTs for experimental validation. The next step consisted on the simulation of circuit involving several interacting devices. A simple IGBT/PIN diode chopper cell has been chosen. The results obtained compare well with experiment. This demonstrates the consistency of the proposed approach. (author) 43 refs.

  17. Atmospheric pressure plasma analysis by modulated molecular beam mass spectrometry

    International Nuclear Information System (INIS)

    Fractional number density measurements for a rf plasma 'needle' operating at atmospheric pressure have been obtained using a molecular beam mass spectrometer (MBMS) system designed for diagnostics of atmospheric plasmas. The MBMS system comprises three differentially pumped stages and a mass/energy analyzer and includes an automated beam-to-background measurement facility in the form of a software-controlled chopper mechanism. The automation of the beam modulation allows the neutral components in the plasma to be rapidly and accurately measured using the mass spectrometer by threshold ionization techniques. Data are reported for plasma generated by a needle plasma source operated using a helium/air mixture. In particular, data for the conversion of atmospheric oxygen and nitrogen into nitric oxide are discussed with reference to its significance for medical applications such as disinfecting wounds and dental cavities and for microsurgery

  18. Aerial Radiation Detection Vehicle Manned and Unmanned Concepts

    International Nuclear Information System (INIS)

    We are developing an Unmanned Aerial Radiation Detection Vehicle that will give new abilities to the Manned Aerial Radiation Detection Vehicle, Air-Ram. A comparison between the two systems will be given, and a report to our first Unmanned Aerial Radiation Detection Vehicle flight. Air-Ram The Air-Ram system, figure 1, has been developed to measure and display online radiation level measurements taken above the radiation area with a chopper. The detected radiation levels are presented on a topographical map with the flight path colored with the radiation intensities. The air crew and controllers on the ground are updated every two seconds. It enables first responders to complete and real time picture of a radiological event which is essential in order to be able to activate and direct ground operations if necessary. The system measures radiation levels and produces a spectrum graph used to identify the isotopes

  19. The design of the inelastic neutron scattering mode for the Extreme Environment Diffractometer with the 26 T High Field Magnet

    Energy Technology Data Exchange (ETDEWEB)

    Bartkowiak, Maciej, E-mail: maciej.bartkowiak@helmholtz-berlin.de; Stüßer, Norbert; Prokhnenko, Oleksandr

    2015-10-11

    The Extreme Environment Diffractometer is a neutron time-of-flight instrument, designed to work with a constant-field hybrid magnet capable of reaching fields over 26 T, unprecedented in neutron science; however, the presence of the magnet imposes both spatial and technical limitations on the surrounding instrument components. In addition to the existing diffraction and small-angle neutron scattering modes, the instrument will operate also in an inelastic scattering mode, as a direct time-of-flight spectrometer. In this paper we present the Monte Carlo ray-tracing simulations, the results of which illustrate the performance of the instrument in the inelastic-scattering mode. We describe the focussing neutron guide and the chopper system of the existing instrument and the planned design for the instrument upgrade. The neutron flux, neutron spatial distribution, divergence distribution and energy resolution are calculated for standard instrument configurations.

  20. Stepper motor drive for on load tapchanger in electric locomotive

    Energy Technology Data Exchange (ETDEWEB)

    Aruna Kumar, G.V.D.; Kumar, S.; Mishra, P.; Wadhonkar, N.K. [Indian Railway Inst. of Electrical Engineering, Nasik (India)

    1995-12-31

    Indian Railways have a fleet of 2,200 electrical locomotives running on 25 KV ac traction. An on-load tap changer is used to select voltage for speed control of dc traction motor. A four stroke reciprocating type air motor is used presently to drive the tap changer (GR). Complex gear and camshaft mechanism is used to move tap changer and to generate various logic signals for safe loco operation. The annual failure rate for tap changer and its drive is of the order of 20%. A microprocessor controlled stepper motor drive has been designed and constructed to drive the on-load tap changer. A current controlled chopper is used to drive the motor and control logic has been generated through an optimum hardware and software combination. The assembly has been tested on a prototype tap changer in the laboratory.

  1. Levels in 237U studied by resonant neutron capture

    International Nuclear Information System (INIS)

    Primary and secondary γ rays in 237U from resonant neutron capture in 236U have been measured with the fast chopper facility, the neutron monochromator, and 2- and 24-keV neutron beam filters. A level scheme was constructed including 27 levels with spin and parity assignments. Rotational band members of the Nilsson configurations [631arrow-down], [622up-arrow], [624arrow-down], [631up-arrow], [633arrow-down], and [501arrow-down] and of the vibrational bands ][622up-arrow] - 2+] and ][631arrow-down] + 0+] were identified. There are more levels below 800 keV, in particular, K = 1/2- bands, than expected from comparison with 235U and 239U. The neutron binding energy in 237U was determined to be 5125.9 +- 0.5 keV

  2. The SSRL linacs for injection to the storage ring and rf gun testing

    International Nuclear Information System (INIS)

    The Stanford Synchrotron Radiation Laboratory (SSRL) operates two linac systems. One has three SLAC type linac sections powered by two klystrons for injection of electrons at 120 MeV into the booster ring, boosting the energy to 2.3 GeV to fill the SPEAR. After the ramping, the SPEAR stores up to 100 mA of the beam at 3.0 GeV. The preinjector consists of a thermionic RF gun, an alpha magnet, and a chopper along with focusing magnets. The other has one 10 foot section powered by the injector klystron for the testing of RF gun with photocathode, which is driven by a separate klystron. This paper describes present systems with their operational parameters, followed by plans for the upgrades and RF gun development efforts at the SSRL. (author)

  3. Soft x-ray circular dichroism and scattering using a modulated elliptically polarizing wiggler and double synchronous detection

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, J.C.; Polewski, K.; Monteleone, D.C. [and others

    1998-01-23

    We have constructed an experimental station (beamline) at the National Synchrotron Light Source to measure circular dichroism (CD) using soft x-rays (250 {le} hv {le} 900 eV) from a time modulated elliptically polarizing wiggler. The polarization of the soft x-ray beam switches periodically between two opposite polarizations, hence permitting the use of phase-sensitive (lock-in) detection. While the wiggler can be modulated at frequencies up to 100 Hz, switching transients limit the actual practical frequency to {approx}25 Hz. With analog detection, switching transients are blocked by a chopper synchronized to the frequency and phase of the wiggler. The CD is obtained from the ratio of the signal recovered at the frequency of polarization modulation, f, to the average beam intensity, which is recovered by synchronous detection at frequency 2f.

  4. Installation and first operation of the International Fusion Materials Irradiation Facility injector at the Rokkasho site

    Science.gov (United States)

    Gobin, Raphael; Bogard, Daniel; Bolzon, Benoit; Bourdelle, Gilles; Chauvin, Nicolas; Chel, Stéphane; Girardot, Patrick; Gomes, Adelino; Guiho, Patrice; Harrault, Francis; Loiseau, Denis; Lussignol, Yves; Misiara, Nicolas; Roger, Arnaud; Senée, Franck; Valette, Matthieu; Cara, Philippe; Duglué, Daniel; Gex, Dominique; Okumura, Yoshikazu; Marcos Ayala, Juan; Knaster, Juan; Marqueta, Alvaro; Kasugai, Atsushi; O'Hira, Shigeru; Shinto, Katsuhiro; Takahashi, Hiroki

    2016-02-01

    The International Fusion Materials Irradiation Facility (IFMIF) linear IFMIF prototype accelerator injector dedicated to high intensity deuteron beam production has been designed, built, and tested at CEA/Saclay between 2008 and 2012. After the completion of the acceptance tests at Saclay, the injector has been fully sent to Japan. The re-assembly of the injector has been performed between March and May 2014. Then after the check-out phase, the production of the first proton beam occurred in November 2014. Hydrogen and deuteron beam commissioning is now in progress after having proceeded with the final tests on the entire injector equipment including high power diagnostics. This article reports the different phases of the injector installation pointing out the safety and security needs, as well as the first beam production results in Japan and chopper tests. Detailed operation and commissioning results (with H+ and D+ 100 keV beams) are reported in a second article.

  5. CIAE 600 kV ns pulse neutron generator

    International Nuclear Information System (INIS)

    The overall composition of CIAE 600 kV ns Pulse Neutron Generator (CPNG) are introduced, and its characteristic, main technological performance and application were also given. CPNG consists of high voltage power supply with highest output voltage 600 kV, direct current 15 mA, stability and ripple ≤0.1%, 2214 mm x 1604 mm x 1504 mm stainless steel high voltage electrode, built in head equipment uniform field accelerating tube, ns pulsed installation, turbomolecular vacuum pump system and drift pipes at 0 degree and 45 degree. Its characteristics are: (1) high current beam; (2) high current beam ns pulsed installation made use of low energy for chopper and high energy for buncher; (3) compactly laid out and simple in structure

  6. A new controller for battery-powered electric vehicles

    Science.gov (United States)

    Belsterling, C. A.; Stone, J.

    1980-01-01

    This paper describes the development, under a NASA/DOE contract, of a new concept for efficient and reliable control of battery-powered vehicles. It avoids the detrimental effects of pulsed-power controllers like the SCR 'chopper' by using rotating machines to meter continuous currents to the traction motor. The concept is validated in a proof-of-principle demonstration system and a complete vehicle is simulated on an analog computer. Test results show exceptional promise for a full-scale system. Optimum control strategies to minimize controller weight are developed by means of the simulated vehicle. The design for an Engineering Model is then prepared in the form of a practical, compact two-bearing package with forced air cooling. Predicted performance is outstanding, with controller efficiency of over 90% at high speed.

  7. Generation of Electron Bunches at Low Repetition Rates Using a Beat-Frequency Technique

    Energy Technology Data Exchange (ETDEWEB)

    Poelker, Matt; Grames, Joseph; Hansknecht, John; Kazimi, Reza; Musson, John

    2007-05-01

    Even at a continuous wave facility such as CEBAF at Jefferson Lab, an electron beam with long time intervals (tens of ns) between individual bunches can be useful, for example to isolate sources of background via time of flight detection or to measure the energy of neutral particles that cannot be separated with a magnetic field. This paper describes a demonstrated method to quickly and easily deliver bunches with repetition rates of 20 to 100 MHz corresponding to time intervals between 10 to 50 ns (respectively). This is accomplished by changing the ON/OFF frequency of the RF-pulsed drive laser by a small amount (f/f < 20%), resulting in a bunch frequency equal to the beat frequency between the radio frequencies of the drive laser and the photoinjector chopper system.

  8. A Medium-Voltage Motor Drive with a Modular Multilevel PWM Inverter Part I. Experimental Verification by a 400-V, 15-kW Downscaled Model

    Science.gov (United States)

    Hagiwara, Makoto; Nishimura, Kazutoshi; Akagi, Hirofumi

    This paper presents a medium-voltage motor drive with a three-phase modular multilevel PWM inverter and focuses on its control method and operating performance. This motor drive is particularly suitable for fans, blowers, pumps, and compressors, in which the load torque is proportional to the square of the rotating speed. Particular attention is paid to the dc-capacitor voltage fluctuation of each chopper-cell because it may affect the voltage rating of the power switching devices used. This paper describes the theoretical equations related to the amount of the voltage fluctuation. A downscaled model rated at 400V and 15kW is designed and built to confirm the validity and effectiveness of the nine-level (17-level in line-to-line) PWM inverter that is intended for use in medium-voltage motor drives to achieve energy savings.

  9. The time-of-flight neutral particle analyzer on the Tandem Mirror Experiment-Upgrade

    International Nuclear Information System (INIS)

    The authors have recently installed a time-of-flight (TOF) neutral particle analyzer on the east end cell of the Tandem Mirror Experiment-Upgrade (TMX-U). The TOF analyzer consists of a modified turbo-molecular pump for use as a particle chopper, a 7-meter flight path and a secondary emission type particle detector. The TOF analyzer is designed to measure the velocity distribution of escaping charge exchange neutral particles (D0) with energies between 20 and 5000eV. The analyzer is presently viewing the midplane of the east plug at an angle of 22.6 degrees with respect to the magnetic field. This location and orientation is within the magnetic loss cone of the end cell. This allows study of the velocity distribution of the potentially confined ions. Initial data have shown an increase in signal magnitude during operation with end plugging

  10. A single-ended CMOS sensing circuit for MEMS gyroscope with noise cancellation

    KAUST Repository

    Elsayed, Mohannad Yomn

    2010-06-01

    In this work, a complete single-ended readout circuit for capacitive MEMS gyroscope using chopper stabilization technique is presented. A novel noise cancellation technique is used to get rid of the bias noise. The circuit offers superior performance over state of the art readout circuits in terms of cost, gain, and noise for the given area and power consumption. The full circuit exhibits a gain of 58dB, a power dissipation of 1.3mW and an input referred noise of 12nV/√Hz. This would significantly improve the overall sensitivity of the gyroscope. The full circuit has been fabricated in 0.6um CMOS technology and it occupies an area of 0.4mm × 1mm. © 2010 IEEE.

  11. Performance Analysis of Savonius Rotor Based Hydropower Generation Scheme with Electronic Load Controller

    Directory of Open Access Journals (Sweden)

    Rajen Pudur

    2016-01-01

    Full Text Available This paper describes the performance of electronic load controller (ELC of asynchronous generator (AG coupled to an uncontrolled Savonius turbine and variable water velocity. An AC-DC-AC converter with a dc link capacitor is employed to maintain the required frequency. The ELC which is feeding a resistive dump load is connected in parallel with the generating system and the power consumption is varied through the duty cycle of the chopper. Gate triggering of ELC is accomplished through sinusoidal pulse width modulation (SPWM by sensing the load current. A MATLAB/Simulink model of Savonius rotor, asynchronous generator, ELC, and three-phase load is presented. The proposed scheme is tested under various load conditions under varying water velocities and the performances are observed to be satisfactory.

  12. The design of the inelastic neutron scattering mode for the Extreme Environment Diffractometer with the 26 T High Field Magnet

    International Nuclear Information System (INIS)

    The Extreme Environment Diffractometer is a neutron time-of-flight instrument, designed to work with a constant-field hybrid magnet capable of reaching fields over 26 T, unprecedented in neutron science; however, the presence of the magnet imposes both spatial and technical limitations on the surrounding instrument components. In addition to the existing diffraction and small-angle neutron scattering modes, the instrument will operate also in an inelastic scattering mode, as a direct time-of-flight spectrometer. In this paper we present the Monte Carlo ray-tracing simulations, the results of which illustrate the performance of the instrument in the inelastic-scattering mode. We describe the focussing neutron guide and the chopper system of the existing instrument and the planned design for the instrument upgrade. The neutron flux, neutron spatial distribution, divergence distribution and energy resolution are calculated for standard instrument configurations

  13. The PASERO Project: parallel and serial readout systems for gas proportional synchrotron radiation X-ray detectors

    CERN Document Server

    Koch, M H J; Briquet-Laugier, F; Epstein, A; Sheldon, S; Beloeuvre, E; Gabriel, A; Hervé, C; Kocsis, M; Koschuch, A; Laggner, P; Leingartner, W; Raad-Iseli, C D; Reimann, T; Golding, F; Torki, K

    2001-01-01

    A project aiming at producing more efficient position sensitive gas proportional detectors and readout systems is presented. An area detector with reduced electrode spacing and a spatial resolution of 0.5 mm and two time to digital convertors (TDC) based on ASICs were produced. The first TDC, intended for use with linear detectors, relies on time to space conversion, whereas the second one, for area detectors, uses a ring oscillator with a phase locked loop. A parallel readout system for multi-anode detectors aiming at a maximum count rate extensively uses RISC microcontrollers. An electronic simulator of linear detectors built for test purposes and a mechanical chopper used for attenuation of the X-ray beam are also briefly described.

  14. Ceramic high temperature superconductor levitating motor with laser commutator

    International Nuclear Information System (INIS)

    The design of a magnetically levitating motor using a ceramic high temperature superconductor with laser commutator is discussed. A YBa sub 2 Cu sub 3 O sub 7-δ high temperature superconductor with 25 mm diameter and 6 mm thickness is used to levitate a Nd-Fe-B magnet (19.0 mm diameter and 4.8 mm thickness) which is attached symmetrically to a 150 mm long graphite rod. A smaller magnet (5.5 mm diameter and 2.0 mm thickness) is attached at each end of the rod with the appropriate poles arrangements. A suitable laser beam chopper is used to optically drive a solenoid which repels the smaller magnets thus driving the motor. A simple and efficient liquid nitrogen supply system is designed to cool the superconductor. The stability of the bearing is provided by the flux pinning in this type-II superconductor. Some characteristics of the motor are discussed

  15. Two-dimensional tomographic terahertz imaging by homodyne self-mixing.

    Science.gov (United States)

    Mohr, Till; Breuer, Stefan; Giuliani, G; Elsäßer, Wolfgang

    2015-10-19

    We realize a compact two-dimensional tomographic terahertz imaging experiment involving only one photoconductive antenna (PCA) simultaneously serving as a transmitter and receiver of the terahertz radiation. A hollow-core Teflon cylinder filled with α-Lactose monohydrate powder is studied at two terahertz frequencies, far away and at a specific absorption line of the powder. This sample is placed between the antenna and a chopper wheel, which serves as back reflector of the terahertz radiation into the PCA. Amplitude and phase information of the continuous-wave (CW) terahertz radiation are extracted from the measured homodyne self-mixing (HSM) signal after interaction with the cylinder. The influence of refraction is studied by modeling the set-up utilizing ZEMAX and is discussed by means of the measured 1D projections. The tomographic reconstruction by using the Simultaneous Algebraic Reconstruction Technique (SART) allows to identify both object geometry and α-Lactose filling. PMID:26480382

  16. Plating pulse switching power based on a CPLD

    International Nuclear Information System (INIS)

    This paper presents a method of using a CPLD to generate a PWM trigger pulse to a full bridge inverter and a chopper circuit. This method results in a very good high power and low voltage large current pulse plating power supply. A single-chip microcomputer is the core of the feedback control system. A fuzzy PID algorithm with SCM and CPLD complexes precisely controls the output voltage, allowing it to maintain a constant value. The system contains a protection circuit that detects output current and output voltage and can correct the system if it enters an over-current abnormal state, ensuring that the driving circuit can effectively drive the IGBT. The circuit is also protected by setting the inverter frequency and dead time of a digital PWM chip. This method for bidirectional pulse plating power supply digital control was verified to be correct and practicable by a Matlab software simulation

  17. 一种新型软开关 BUCK变换器%A NoveI Soft-switching BUCK Converter

    Institute of Scientific and Technical Information of China (English)

    刘吉星; 沈锦飞

    2014-01-01

    磁耦合谐振式无线电能传输采用直流斩波调压控制传输功率,传统的直流斩波电路开关损耗大,因此提出了一种新型的软开关BUCK变换器的改进电路,在电路中添加耦合电感、辅助电感和二极管,可以实现零电流开通和零电压关断。变换器结构简单,便于控制。介绍了电路工作原理和过程,设计了电路参数,进行了仿真和实验研究,最后给出了仿真和实验波形。%The magnetically coupled resonant wireless power transmission adopts DC chopper control over transmission power,while traditional DC chopper circuit switching has a high loss.This paper presents an improved circuit for a novel soft-switching BUCK DC-DC converter,where a coupled inductor,auxiliary inductor and diode are added to realize zero current switching-on and zero voltage switching-off.The converter has a simple structure and is easy to control.Furthermore,the paper describes the working principle and process of the circuit,designs circuit parameters,completes simulation and experimental research,and finally gives simulation and test waveforms.

  18. BioCARS: a synchrotron resource for time-resolved X-ray science

    International Nuclear Information System (INIS)

    BioCARS, a NIH-supported national user facility for macromolecular time-resolved X-ray crystallography at the Advanced Photon Source (APS), has recently completed commissioning of an upgraded undulator-based beamline optimized for single-shot laser-pump X-ray-probe measurements with time resolution as short as 100 ps. The source consists of two in-line undulators with periods of 23 and 27 mm that together provide high-flux pink-beam capability at 12 keV as well as first-harmonic coverage from 6.8 to 19 keV. A high-heat-load chopper reduces the average power load on downstream components, thereby preserving the surface figure of a Kirkpatrick-Baez mirror system capable of focusing the X-ray beam to a spot size of 90 (micro)m horizontal by 20 (micro)m vertical. A high-speed chopper isolates single X-ray pulses at 1 kHz in both hybrid and 24-bunch modes of the APS storage ring. In hybrid mode each isolated X-ray pulse delivers up to ∼4 x 1010 photons to the sample, thereby achieving a time-averaged flux approaching that of fourth-generation X-FEL sources. A new high-power picosecond laser system delivers pulses tunable over the wavelength range 450-2000 nm. These pulses are synchronized to the storage-ring RF clock with long-term stability better than 10 ps RMS. Monochromatic experimental capability with Biosafety Level 3 certification has been retained.

  19. A versatile source to produce high-intensity, pulsed supersonic radical beams for crossed-beam experiments: The cyanogen radical CN(X2Σ+) as a case study

    International Nuclear Information System (INIS)

    In our laboratory a novel and convenient technique has been developed to generate an intense pulsed cyano radical beam to be employed in crossed molecular beam experiments investigating the chemical dynamics of bimolecular reactions. CN radicals in their ground electronic state 2Σ+ are produced in situ via laser ablation of a graphite rod at 266 nm and 30 mJ output power and subsequent reaction of the ablated species with molecular nitrogen, which acts also as a seeding gas. A chopper wheel located after the ablation source and before the collision center selects a 9 μs segment of the beam. By changing the delay time between the pulsed valve and the choppper wheel, we can select a section of the pulsed CN(X2Σ+) beam choosing different velocities in the range of 900 - 1920 ms-1 with speed ratios from 4 to 8. A high-stability analog oscillator drives the motor of the chopper wheel (deviations less than 100 ppm of the period), and a high-precision reversible motor driver is interfaced to the rotating carbon rod. Both units are essential to ensure a stable cyanogen radical beam with velocity fluctuations of less than 3%. The high intensity of the pulsed supersonic CN beam of about 2 - 3x1011 cm-3 is three orders of magnitude higher than supersonic cyano radical beams employed in previous crossed molecular beams experiments. This data together with the tunable velocity range clearly demonstrate the unique power of our newly developed in situ production of a supersonic CN radical beam. This versatile concept is extendible to generate other intense, pulsed supersonic beams of highly unstable diatomic radicals, among them BC, BN, BO, BS, CS, SiC, SiN, SiO, and SiS, which are expected to play a crucial role in interstellar chemistry, chemistry in the solar system, and/or combustion processes. copyright 1999 American Institute of Physics

  20. A regulated high voltage power supply for accelerator driven system; A regulated high voltage power supply for accelerator driven system

    International Nuclear Information System (INIS)

    This paper discusses a regulated high voltage power supply (RHVPS) developed for accelerator driven systems to drive a klystron. The RHVPS uses a large no. of small voltage choppers. These choppers are switched in tandem by a novel technique to regulate output voltage. Various parts of the system are novel. The front end is a pair of transformer with 40 secondaries each. Each secondary feeds a switched power module (SPM) which has a rectifier-filter unit followed by an IGBT switch to get 1.3 kV. All 80 SPMs are connected in series. The final output is taken from the two end SPMs. A central controller uses voltage sample from each SPM and generates switching pulses for each IGBT switch. IGBTs of all SPMs are switched with a fixed phase lag from each other, resulting in purely constant voltage with ripple limited to one SPM voltage. The frequency of ripple is high and can be filtered out with a simpler filter. The system can turn off for protection of the load in less than 2 μs, the essential attribute for a power supply to be used with klystrons. The results of wire burn tests measure the low stored energy at fault turn off (less than 10 J). The power supply (rated for 100 kV at 2.5 MW) will be used for a continuous duty with the klystron for accelerator driven system at BARC (India). A power supply giving 80 kV. 75 A is being used with an accelerator system for extraction of beam along with a Neutral Beam Injector. This paper discusses the technology and experimental results of the system. It also discusses various other options with similar power supply. (author)

  1. A regulated power supply for accelerator driven system

    International Nuclear Information System (INIS)

    This paper discusses a regulated high voltage power supply (RHVPS) developed for accelerator driven systems to drive a klystron. The RHVPS uses a large no. of small voltage choppers. These choppers are switched in tandem by a novel technique to regulate output voltage. Various parts of the system are novel. The front end is a pair of transformer with 40 secondaries each. Each secondary feeds a switched power module (SPM) which has a rectifier-filter unit followed by an IGBT switch to get 1.3 kV. All 80 SPMs are connected in series. The final output is taken from the two end SPMs. A central controller uses voltage sample from each SPM and generates switching pulses for each IGBT switch. IGBTs of all SPMs are switched with a fixed phase lag from each other, resulting in purely constant voltage with ripple limited to one SPM voltage. The frequency of ripple is high and can be filtered out with a simpler filter. The system can turn off for protection of the load in less than 2 microseconds, the essential attribute for a power supply to be used with klystrons. The results of wire burn tests measure the low stored energy at fault turn off (less than10 J). The power supply (rated for 100 kV at 2.5 MW) will be used for a continuous duty with the klystron for accelerator driven system at BARC (India). A power supply giving 80 kV, 75A is being used with an accelerator system for extraction of beam along with a Neutral Beam Injector. This paper discusses the technology and experimental results of the system. It also discusses various other options with similar power supply. (author)

  2. A NoveI Soft-switching BUCK Converter%一种新型软开关 BUCK变换器

    Institute of Scientific and Technical Information of China (English)

    刘吉星; 沈锦飞

    2014-01-01

    磁耦合谐振式无线电能传输采用直流斩波调压控制传输功率,传统的直流斩波电路开关损耗大,因此提出了一种新型的软开关BUCK变换器的改进电路,在电路中添加耦合电感、辅助电感和二极管,可以实现零电流开通和零电压关断。变换器结构简单,便于控制。介绍了电路工作原理和过程,设计了电路参数,进行了仿真和实验研究,最后给出了仿真和实验波形。%The magnetically coupled resonant wireless power transmission adopts DC chopper control over transmission power,while traditional DC chopper circuit switching has a high loss.This paper presents an improved circuit for a novel soft-switching BUCK DC-DC converter,where a coupled inductor,auxiliary inductor and diode are added to realize zero current switching-on and zero voltage switching-off.The converter has a simple structure and is easy to control.Furthermore,the paper describes the working principle and process of the circuit,designs circuit parameters,completes simulation and experimental research,and finally gives simulation and test waveforms.

  3. Brush-eating device promises reforestation, wood energy aid

    Energy Technology Data Exchange (ETDEWEB)

    Blackman, T.

    1981-01-01

    An invention which began as a low-ground-pressure skidder developed into a machine which clears brush, thins plantations, and can harvest wood for energy. First came the notion of an extra-low-ground-pressure log skidder. A swinging chopper was added to the front to clear the skid roads. Working in manzanita brush 10 to 12 foot tall, and with stems up to 18 inches in diameter, the Shar 20 can clear one to two and a half acres an hour. The 30 will be able to clear two to five acres an hour. The big machine will have two chopper heads rotating in opposite directions to force the chopped wood into a chipper built into the machine. Chips will be blown to a van following the harvester so they can be used for hog fuel or as feedstock for methanol production. The head spins at a relatively slow 450 rpm - a safety factor. Surrounding brush catches most of the cut material, but an occasional chunk of wood does fly several yards. Companies are paying more attention to reforestation. Clearing the land will leave a mulch-like debris on the ground. This offers some shade and helps retain soil moisture. Even when brush is harvested for energy, about 10% of the material is left on the ground. California's Department of Forestry wants to start a five-year clearing cycle for the chaparral stands, ''mowing'' a million acres a year and returning every fifth year to reclear the brush. California alone has 27 million acres of brushland not suitable for timber. A brushy acre averages from 30 to 200 tons of wood at 10% moisture content. The machines are designed to run at up to 12 mph when moving.

  4. Neutron Scattering Experiment Automation with Python

    International Nuclear Information System (INIS)

    The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory currently holds the Guinness World Record as the world most powerful pulsed spallation neutron source. Neutrons scattered off atomic nuclei in a sample yield important information about the position, motions, and magnetic properties of atoms in materials. A neutron scattering experiment usually involves sample environment control (temperature, pressure, etc.), mechanical alignment (slits, sample and detector position), magnetic field controllers, neutron velocity selection (choppers) and neutron detectors. The SNS Data Acquisition System (DAS) consists of real-time sub-system (detector read-out with custom electronics, chopper interface), data preprocessing (soft real-time) and a cluster of control and ancillary PCs. The real-time system runs FPGA firmware and programs running on PCs (C++, LabView) typically perform one task such as motor control and communicate via TCP/IP networks. PyDas is a set of Python modules that are used to integrate various components of the SNS DAS system. It enables customized automation of neutron scattering experiments in a rapid and flexible manner. It provides wxPython GUIs for routine experiments as well as IPython command line scripting. Matplotlib and numpy are used for data presentation and simple analysis. We will present an overview of SNS Data Acquisition System and PyDas architectures and implementation along with the examples of use. We will also discuss plans for future development as well as the challenges that have to be met while maintaining PyDas for 20+ different scientific instruments.

  5. Simulation of Some of the Power Electronics Case Studies in Matlab Simpowsystem Toolbox

    Science.gov (United States)

    Alasooly, Hedaya; Redha, Mohammed

    2010-06-01

    Matlab SimPowerSystems is a modern design tool that allows scientists and engineers to rapidly and easily build models that simulate power systems. Not only can you draw the circuit topology rapidly, but your analysis of the circuit can include its interactions with mechanical, thermal, control, and other disciplines. The paper covers some case studies that provide detailed, realistic examples of how to use SimPowerSystems in power system analysis. The following types of studies is coverted on the paper: 1. Thyristor-Based Static Var Compensator: Study the steady-state and dynamic performance of a static var compensator (SVC) on a transmission system. 2. Transient Stability of a Power System with SVC and PSS: Study of the application of static var compensator (SVC) and power system stabilizers (PSS) to improve transient stability and power oscillation damping of the system. 3. GTO-Based STATCOM: Study the steady-state and dynamic performance of a static synchronous compensator (STATCOM) on a transmission system. 4. Control of load flow using UPFC: Study the steady-state and dynamic performance of a unified power flow controller (UPFC). 5. Chopper-Fed DC Motor Drive: Study of a DC motor drive with armature voltage controlled by a GTO thyristor chopper. 6. VSC-Based HVDC Link: Modeling of a forced-commutated Voltage-Sourced Converter high-voltage direct current (VSC-HVDC) transmission link. 7. Three-Phase Network with Electrical Machines: Simulation of a three-phase power system containing electrical machines and other three-phase models. 8. Variable-Frequency Induction Motor Drive: Study of a PWM inverter-driven variable-frequency AC induction motor in variable-voltage, variable-speed operation.

  6. Design of Power Conditioning System in Superconducting Magnetic Energy System Based on Voltage Source Converter%基于VSC的超导储能装置中功率调节系统的设计

    Institute of Scientific and Technical Information of China (English)

    张金良; 周博曦; 卞秋野

    2013-01-01

      针对超导储能装置中基于电压源型变流器的功率调节系统,给出了基于电压源型变流器(VSC)和斩波器(Chopper)的超导储能(SMES)装置功率调节系统(PCS)的主电路拓扑结构和使用占空比表达的PCS低频数学模型,提出了使用非线性变换实现状态方程线性化的方法,通过状态方程的线性化实现有功功率、无功功率及直流侧电压解耦控制的系统设计。Matlab/Simulink环境下系统仿真结果表明,设计的PCS系统控制器对阶跃和正弦波功率指令具有很强的跟踪能力,且直流侧电压有很强的抗干扰能力。%Aiming at the power conditioning system (PCS) in the superconducting magnetic energy system (SMES) based on volt-age source converter (VSC), this paper gave the main circuit structure of PCS in the SMES based on the VSC and Chopper, as well as the low-frequency mathematical model of PCS which is expressed in the functions of duty ratio. The non-linear transformation was used to linearize state equations to realize the decoupled control between active power, reactive power and DC voltage. The simulated results in Simulink of Matlab showed that the designed PCS has perfect performance in tracing power orders in the form of step and sine waves with strong anti-jamming ability for voltage at DC side.

  7. Neutron Scattering Experiment Automation with Python

    Energy Technology Data Exchange (ETDEWEB)

    Zolnierczuk, Piotr A [ORNL; Riedel, Richard A [ORNL

    2010-01-01

    The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory currently holds the Guinness World Record as the world most powerful pulsed spallation neutron source. Neutrons scattered off atomic nuclei in a sample yield important information about the position, motions, and magnetic properties of atoms in materials. A neutron scattering experiment usually involves sample environment control (temperature, pressure, etc.), mechanical alignment (slits, sample and detector position), magnetic field controllers, neutron velocity selection (choppers) and neutron detectors. The SNS Data Acquisition System (DAS) consists of real-time sub-system (detector read-out with custom electronics, chopper interface), data preprocessing (soft real-time) and a cluster of control and ancillary PCs. The real-time system runs FPGA firmware and programs running on PCs (C++, LabView) typically perform one task such as motor control and communicate via TCP/IP networks. PyDas is a set of Python modules that are used to integrate various components of the SNS DAS system. It enables customized automation of neutron scattering experiments in a rapid and flexible manner. It provides wxPython GUIs for routine experiments as well as IPython command line scripting. Matplotlib and numpy are used for data presentation and simple analysis. We will present an overview of SNS Data Acquisition System and PyDas architectures and implementation along with the examples of use. We will also discuss plans for future development as well as the challenges that have to be met while maintaining PyDas for 20+ different scientific instruments.

  8. 基于VO2薄膜非致冷红外探测器光电响应研究%INFRARED RESPONSIVITY OF UNCOOLED VO2-BASED THIN FILMS BOLOMETER

    Institute of Scientific and Technical Information of China (English)

    陈长虹; 易新建; 熊笔锋

    2001-01-01

    VO2 thin films are used for uncooled microbolometer due to their high temperature coefficient of resistance.In this paper,on the basis of fabricating the uncooled bolometer based on VO2 sputtered thin films,the responsivity for the spectral range of 8 - 12μm region dependence on bias current and chopper frequency is studied.The result indicates that the responsivity is over 17kV/W and up to 10kV/W at a chopper frequency of 10 and 30Hz,respectively.The device having a detectivity D* of exceeding 1.0 × 108 cm Hz/W and a thermal time constant of 0.011 seconds has been realized.%VO2薄膜是非致冷微测辐射热红外探测器热敏电阻材料。研究中应用微电子工艺制备了VO2溅射薄膜红外探测器,在296K的环境中测试了该探测器在不同的直流偏置、光调制频率下对873K标准黑体源8—12μm红外辐射的光电响应以及器件的噪声电压,在10和30Hz的调制频率下其响应率分别大于17kV/W和接近10kV/W。该探测器实现了探测率D*大于1.0×108cm Hz/W,热时间常量为0.011s的8-12μm非致冷红外探测。

  9. Pid Plus Fuzzy Logic Controller Based Electronic Load Controller For Self Exited Induction Generator.

    Directory of Open Access Journals (Sweden)

    S.Swathi,

    2014-01-01

    Full Text Available This paper deals with the electronic load controller for self exited induction generator using PID plus fuzzy logic controller. The self-excited induction generators (SEIGs are considered to be well suited for generating electricity by means of conventional energy sources and for supplying electrical energy in remote and rural areas. Induction generators have many advantages such as cost, reduced maintenance, rugged, and simple construction, brushless rotor (squirrel cage. A three phase induction generator can be operated on a delta connection for supplying single phase loads. The main disadvantage of SEIG has is that it poor voltage regulation, and its value depends on the prime mover speed, capacitance, load current and power factor of the load. The electronic load controller (ELC can be used for maintaining constant voltage and frequency of SEIG with variable consumer load driven by constant prime mover. This paper presents the simulation design and implementation of ELC using fuzzy logic method for an SEIG feeding single-phase load. The ELC consist of a rectifier, IGBT as a chopper switch, PI controller, voltage sensor, and resistive dump load in which power consumption was varied through the duty cycle of the chopper. However an ELC consist of electronics system, in general, has complex nonlinear model with parameter variation problem, and the control need to be very fast. The fuzzy logic based controller gives nonlinear control with fast response and virtually no overshoot. The simulation of ELC for self exited induction generator is carried out on MATLAB/SIMULINK. By this proposed ELC using FLC for SEIG we can maintain the constant voltage and frequency of SEIG with variable consumer load.

  10. Catenary DC Ice-Melting Technology and Device Development of Electrified Railway%电气化铁路接触网直流融冰技术及装置研制

    Institute of Scientific and Technical Information of China (English)

    敬华兵; 年晓红

    2012-01-01

    The icing of traction network seriously affects the normal operation of trunk railway. The characteristics of catenary ice-melting are described. The regulated method of ice-melting current and voltage be changed with the thickness of ice and the distance of the ice-melting line is discussed. A new ice-melting circuit topology witch based on power unit chopper cascaded is proposed. Equivalent circuit of this device with parallel input and output series is promoted, and the control methods of multiple rectifier is analysised. The input harmonic and power factor of phase dislocation four-quadrant rectifier is studied. The control method of chopper tolerant-phase output of cascaded power units is put forword. The working state of the circuit is analysised.The relationship of cascaded power unit voltage balance control principle, chopper output duty cycle, and capacitor voltage are studied and simulated. The high power experimental prototype is designed and full power experimental is completed with short of voltage feedback method. The results show that this ice-melting circuit has steady output voltage with low input harmonic content.It will do little influence on electric network, and can be aoolied to engineering oractice effectively.%铁路牵引网覆冰会严重影响铁路干线的正常运行,本文阐述了接触网融冰的特点,论述了融冰电流、电压随距离和覆冰厚度的调节方法,提出了新型功率单元斩波级联全控整流融冰电路拓扑,推出了该融冰装置的并联输入串联输出(IPOC)等效电路。分析了输入侧多重整流控制的方式,对四象限错相整流的输入谐波及功率因数控制进行了探讨,提出了级联功率单元的斩波错相输出控制方法,分析了电路的工作状态。研究了级联功率单元的均压控制原则以及斩波输出占空比与电容电压的关系,并进行了仿真研究。在此基础上设计了大功率实验样机

  11. Nucleodissecção & facoemulsificação Nucleodissection and phacoemulsification

    Directory of Open Access Journals (Sweden)

    Marcelo Siqueira de Freitas

    2002-03-01

    Full Text Available O autor descreve uma técnica para dissecar o núcleo cataratoso em duas porções: uma externa, ou camada externa, e outra interna, ou núcleo interno. A camada externa é segmentada com a ponteira do facoemulsificador e o gancho de Sinskey ou um "chopper" e o núcleo interno luxado e emulsificado sempre em primeiro lugar. A emulsificação da camada externa originou dois modelos cirúrgicos, um para cataratas maduras e outro para cataratas moderadamente duras. Nas cataratas maduras, emulsificamos cada divisão da camada externa anterior e depois a porção posterior, deslocada para câmara anterior. Nas cataratas moderadamente duras, é possível separar um conjunto de lamelas formadas por fibras duras, tanto anteriores como posteriores das lamelas superficiais que permanecem protegendo a cápsula posterior. As lamelas duras são emulsificadas no espaço que surge depois da emulsificação do núcleo interno, que denominamos de espaço intranuclear. A nucleodissecção assim como os modelos cirúrgicos referidos mostraram-se de grande utilidade e são usados na nossa rotina cirúrgica.The author describes a technique for dissection of the nucleus of the cataract into two parts: an external one or external layer, and an internal one or internal nucleus. The anterior portion of the external layer is divided into segmentes like a "pizza" with the phaco tip and a Sinskey hook or a "chopper" and the internal nucleus is dislocated and emulsified. The emulsification of the external layer gives rise to two different surgical models, one for mature and the other for moderately hard cataracts. In the case of mature cataracts we emulsify each segment of the anterior external layer and then the posterior portion, which has already been moved to the anterior chamber. In the case of moderately hard cataracts it is possible to separate a set of layers made of hard anterior and posterior fibers, emulsify them, and leave the superficial layers which continue

  12. Performance of the advanced cold neutron source and optics upgrades at the NIST Research Reactor

    International Nuclear Information System (INIS)

    On March 6, 2002, the NIST Research Reactor resumed routine operation following a six-month shutdown for facility upgrades and maintenance. During the shutdown, the original liquid hydrogen cold neutron source was removed, and the advanced cold source was installed. An optical filter was installed on one of the neutron guides, NG-3, replacing a crystal filter for the 30-m SANS instrument and the guide used between the chopper disks of the Disk Chopper time-of-flight Spectrometer (DCS) installed on NG-4 has been recently reconfigured. Additional improvements in the neutron optics of various instruments are being made. The advanced liquid hydrogen cold neutron source performs as expected, nearly doubling the flux available to most instruments. The measured gains range from about 1.4 at 2 A, to over a factor of two at 15 A. Also as expected, the heat load in the new source increased to 1200 watts, but the previously existing refrigerator has easily accommodated the increase. With intensity gains of a factor of two in the important long wavelength region of the spectrum, the advanced cold source significantly enhances the measurement capability of the cold neutron scattering instrumentation at NIST. The optical filter on NG-3 is also very successful; the 30-m SANS has an additional gain of two at 17 A. A system of refracting lenses and prisms near the SANS sample position has made possible measurements at low Q (0.0005 A-1) that were previously not feasible. The DCS has also seen additional intensity gain factors in excess of two for the majority of experiments and at short neutron wavelengths the gains exceed three. In addition, two new triple axis spectrometers will feature double-focusing monochromators in order to exploit the full size of the available thermal and cold neutron beam tubes. The success of the advanced cold source and enhanced neutron optics contributed to the recognition of the NIST Center for Neutron Research as 'the premiere neutron scattering

  13. Boost Converters for Gas Electric and Fuel Cell Hybrid Electric Vehicles

    Energy Technology Data Exchange (ETDEWEB)

    McKeever, JW

    2005-06-16

    Hybrid electric vehicles (HEVs) are driven by at least two prime energy sources, such as an internal combustion engine (ICE) and propulsion battery. For a series HEV configuration, the ICE drives only a generator, which maintains the state-of-charge (SOC) of propulsion and accessory batteries and drives the electric traction motor. For a parallel HEV configuration, the ICE is mechanically connected to directly drive the wheels as well as the generator, which likewise maintains the SOC of propulsion and accessory batteries and drives the electric traction motor. Today the prime energy source is an ICE; tomorrow it will very likely be a fuel cell (FC). Use of the FC eliminates a direct drive capability accentuating the importance of the battery charge and discharge systems. In both systems, the electric traction motor may use the voltage directly from the batteries or from a boost converter that raises the voltage. If low battery voltage is used directly, some special control circuitry, such as dual mode inverter control (DMIC) which adds a small cost, is necessary to drive the electric motor above base speed. If high voltage is chosen for more efficient motor operation or for high speed operation, the propulsion battery voltage must be raised, which would require some type of two-quadrant bidirectional chopper with an additional cost. Two common direct current (dc)-to-dc converters are: (1) the transformer-based boost or buck converter, which inverts a dc voltage, feeds the resulting alternating current (ac) into a transformer to raise or lower the voltage, and rectifies it to complete the conversion; and (2) the inductor-based switch mode boost or buck converter [1]. The switch-mode boost and buck features are discussed in this report as they operate in a bi-directional chopper. A benefit of the transformer-based boost converter is that it isolates the high voltage from the low voltage. Usually the transformer is large, further increasing the cost. A useful feature

  14. Outbreak of gastroenteritis in Tibetan transit school, dharamshala, Himachal Pradesh, India, 2006

    Directory of Open Access Journals (Sweden)

    Gupta Surender

    2009-01-01

    Full Text Available Background: On 28 th June, 2006, 55 cases of the gastroenteritis were reported among the hostellers of the Tibetan Transit School, Dharamshala. We investigated the outbreak to identify the source, propose control and preventive measures. Materials and Methods: We defined a case of the gastroenteritis as the occurrence of more than three smelly loose motions between 28 th June to 2 nd July, 2006 among some sections of the resident hostellers. We determined age and sex specific attack rate. We hypothesized it as a food borne beef meat outbreak. We conducted the case control study and collected the information about the food items consumed inside and outside the hostel at dinner using the standardized questionnaire. We calculated floor wise incidences of four hostels, odds ratios and attributable fractions. We interviewed food handlers. We lifted the seven rectal stool, four water and three samples from floor, kitchen and meat chopper room for culture and sensitivity. Results: 116 cases patients of 802 hostellers met the case definition. The maximum attack rate (16% was in the youngest group (15-20yrs and nil in staff and 31-40 years age group with 5 overall attack rate as 14%. Sex specific attack rate was more (18% in females. The floor wise incidences of the case patients were the highest in 2nd and 3rd floors, occupied by the youngest group. The median age was 20 yrs (Range 17-40 yrs. The most common symptoms were watery diarrhea (71/116, 61% and bloody diarrhea-(45/116, 39%; abdominal pains- (87/116, 75%. Of the six food/water items examined, the food specific attack rate was highly statistically significant in the beef meat eaters (82% with PAF 71%, and Odds Ratio 19.19 (95% C.I. as 9.3-140. The food handlers & their cooking conditions in the kitchen were unhygienic. The food was not available for testing. Escherichia coli were detected in the samples from rectal stools, kitchen and meat chopper room. No fatality was reported. Conclusion

  15. The Neutron Spectrum in a Uranium Tube

    International Nuclear Information System (INIS)

    A series of experimental and theoretical investigations on neutron spectra in lattice cells has been started at the reactor R1. This report gives the results from the first one of these cells - one with a tube of natural -uranium surrounded by heavy water. In the measurements the cell was placed in the central, vertical channel of the reactor. The neutron spectrum from a lead scatterer in the uranium tube - outer diameter 49.2 mm, inner diameter 28.3 mm - was measured with a fast chopper in the energy region 0.01 to 100 eV. Subsidiary measurements indicated that the spectrum in the beam from the lead piece corresponds to the spectrum of the angular flux integrated over all angles. This correspondence is important for the interpretation of the experimental data. The thermal part of the spectrum was found to deviate significantly from a Maxwellian. However, the deviation is not very large, and one could use a Maxwellian, at least to give a rough idea of the hardness of the spectrum. For the present tube the temperature of this Maxwellian was estimated as 90 to 100 deg C above the moderator temperature (33 deg C). In the joining region the rise of the spectrum towards the thermal part is slower than for the cell boundary spectrum, measured earlier. In the epithermal region the limited resolution of the chopper has affected the measurements at the energies of the uranium resonances. However, the shape of the spectrum on the flanks of the first resonance in 238U (6.68 eV) has been obtained accurately. In the theoretical treatment the THERMOS code with a free gas scattering model has been used. The energy region was 3.06 - 0.00025 eV. The agreement with the measurements is good for the thermal part - possibly the theoretical spectrum is a little softer than the experimental one. In the joining region the results from THERMOS are comparatively high - probably due to the scattering model used

  16. Generation of thermo-acoustic waves from pulsed solar/IR radiation

    Science.gov (United States)

    Rahman, Aowabin

    Acoustic waves could potentially be used in a wide range of engineering applications; however, the high energy consumption in generating acoustic waves from electrical energy and the cost associated with the process limit the use of acoustic waves in industrial processes. Acoustic waves converted from solar radiation provide a feasible way of obtaining acoustic energy, without relying on conventional nonrenewable energy sources. One of the goals of this thesis project was to experimentally study the conversion of thermal to acoustic energy using pulsed radiation. The experiments were categorized into "indoor" and "outdoor" experiments, each with a separate experimental setup. The indoor experiments used an IR heater to power the thermo-acoustic lasers and were primarily aimed at studying the effect of various experimental parameters on the amplitude of sound waves in the low frequency range (below 130 Hz). The IR radiation was modulated externally using a chopper wheel and then impinged on a porous solid, which was housed inside a thermo-acoustic (TA) converter. A microphone located at a certain distance from the porous solid inside the TA converter detected the acoustic signals. The "outdoor" experiments, which were targeted at TA conversion at comparatively higher frequencies (in 200 Hz-3 kHz range) used solar energy to power the thermo-acoustic laser. The amplitudes (in RMS) of thermo-acoustic signals obtained in experiments using IR heater as radiation source were in the 80-100 dB range. The frequency of acoustic waves corresponded to the frequency of interceptions of the radiation beam by the chopper. The amplitudes of acoustic waves were influenced by several factors, including the chopping frequency, magnitude of radiation flux, type of porous material, length of porous material, external heating of the TA converter housing, location of microphone within the air column, and design of the TA converter. The time-dependent profile of the thermo-acoustic signals

  17. A user configurable data acquisition and signal processing system for high-rate, high channel count applications

    Energy Technology Data Exchange (ETDEWEB)

    Salim, Arwa, E-mail: arwa.salim@eee.strath.ac.uk [University of Strathclyde, Scotland (United Kingdom); Crockett, Louise [University of Strathclyde, Scotland (United Kingdom); McLean, John; Milne, Peter [D-TACQ Solutions, Scotland (United Kingdom)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer The development of a new digital signal processing platform is described. Black-Right-Pointing-Pointer The system will allow users to configure the real-time signal processing through software routines. Black-Right-Pointing-Pointer The architecture of the DRUID system and signal processing elements is described. Black-Right-Pointing-Pointer A prototype of the DRUID system has been developed for the digital chopper-integrator. Black-Right-Pointing-Pointer The results of acquisition on 96 channels at 500 kSamples/s per channel are presented. - Abstract: Real-time signal processing in plasma fusion experiments is required for control and for data reduction as plasma pulse times grow longer. The development time and cost for these high-rate, multichannel signal processing systems can be significant. This paper proposes a new digital signal processing (DSP) platform for the data acquisition system that will allow users to easily customize real-time signal processing systems to meet their individual requirements. The D-TACQ reconfigurable user in-line DSP (DRUID) system carries out the signal processing tasks in hardware co-processors (CPs) implemented in an FPGA, with an embedded microprocessor ({mu}P) for control. In the fully developed platform, users will be able to choose co-processors from a library and configure programmable parameters through the {mu}P to meet their requirements. The DRUID system is implemented on a Spartan 6 FPGA, on the new rear transition module (RTM-T), a field upgrade to existing D-TACQ digitizers. As proof of concept, a multiply-accumulate (MAC) co-processor has been developed, which can be configured as a digital chopper-integrator for long pulse magnetic fusion devices. The DRUID platform allows users to set options for the integrator, such as the number of masking samples. Results from the digital integrator are presented for a data acquisition system with 96 channels simultaneously acquiring data

  18. 适用于农村电网的新型电压补偿装置设计%Design for a Novel Low-voltage Compensation Device Fit for Rural Power Grid

    Institute of Scientific and Technical Information of China (English)

    苏毅; 乐健; 刘开培; 谭甜源; 雷肖; 陈青恒

    2011-01-01

    针对配电网尤其是农村电网和偏远地区供电线路末端的电压偏低问题,研究了一种基于交流脉宽调制技术的低电压补偿电路。该电路串联于供电线路中,在线路末端电压偏低时投入运行,可保证负载电压在允许范围内。该装置仅需补偿供电电压不足的部分,降低了对装置的容量要求,采用交流斩波方式使得电压调节范围宽且连续,同时装置自身无需储能元件,结构简单。给出了该装置的拓扑结构设计和脉宽调制方法,研究分析了其适用范围;通过仿真计算、样机实验和现场运行验证了该装置的正确性和有效性。%A novel voltage regulator based on pulse width modulation(PWM) controlled AC chopper is proposed to solve the low voltage problem at the terminal of a distribution system,especially at the terminal of rural power network.Connected to the power supply line in series,the circuit starts up when the line voltage dropped and can maintain the load voltage within the acceptable range.The requirement on the capacity of this device is lowered since it only compensates for the insufficient part of the power supply line voltage.Based on AC chopper,the output voltage can be adjusted continuously within a wide range.The structure of this device is simple for its direct transfer of power from grid to load without the energy storage element.The topology and modulating method of the regulator are discussed in detail,and its application scope is studied.The accuracy and availability of this regulator are verified by both simulation and prototype results.

  19. A platform for development and evaluation of real - time wind energy conversion strategies

    International Nuclear Information System (INIS)

    Wind energy is one of the most promising power generation alternatives, and one of the most dynamic scenarios for novel control strategies. The particular characteristics of each geographical zone, and the inherent randomness of the wind impose important constrains for the evaluation of a wind energy conversion system (WECS). This is particularly true for wind turbines and their associated instrumentation. A wind turbine emulator (WTE) can be used to help in the evaluation of hardware-software alternatives, avoiding difficult field tests by recreating real environments on a controlled testbed. It consists of an electrical machine driven by a solid-state converter. WTEs are controlled to provide a desired dynamic Torque-Speed characteristic, equivalent to a real wind turbine under prescribed external conditions. The control system provides a desired torque value as a function of wind and turbine shaft speeds. This work presents the hardware / software development of a WECS emulator to be used in analysis and design of Real-Time control strategies for different types of electric generators. The proposed system is composed by a wind turbine emulator connected to an AC generator. The Wind Turbine Emulator consists of a direct current (DC) motor that is driven by a four-quadrant DC/DC converter or chopper. It is made of a MOSFET H-Bridge, with a current control loop. The generator block consists of an asynchronous AC machine, driven by static converters tailored to particular applications (autonomous or grid-connected WECS).With the objective to have a versatile system, the control of WTE and WECS generator is carried out by a Pentium PC equipped with an I/O multifunction acquisition board. It generates reference values for the current control loop driving the chopper and measures the shaft rotation speed using an incremental optical encoder. Software for the PC is developed in MatLab/Simulink, using Real Time WorkShop (RTW) and Real Time Windows Target (RTWT). This

  20. OPTIMIZATION OF THE HYSPEC DESIGN USING MONTE CARLO SIMULATIONS.

    Energy Technology Data Exchange (ETDEWEB)

    GHOSH, V.J.; HAGEN, M.E.; LEONHARDT, W.J.; ZALIZNYAK, I.; SHAPIRO, S.M.; PASSELL, L.

    2005-04-25

    HYSPEC is a direct geometry spectrometer to be installed at the SNS [1] on beamline 14B where it will view a cryogenic coupled hydrogen moderator, The ''hybrid'' design combines time-of-flight spectroscopy with focusing Bragg optics to provide a high monochromatic flux on small single crystal samples, with a very low background at an extended detector bank. The instrument is optimized for an incident energy range of 3-90meV. It will have a medium energy resolution (2-10%) and will provide a flux on sample of the order of 10{sup 6}-10{sup 7} neutrons/s-cm{sup 2}. The spectrometer will be located in a satellite building outside the SNS experimental hall at the end of a 35m curved supermirror guide. A straight-slotted Fermi chopper will be used to monochromate the neutron beam and to determine the burst width. The 15cm high, 4cm wide beam will be focused onto a 2cm by 2cm area at the sample position using Bragg reflection from one of two crystal arrays. For unpolarized neutron studies these will be Highly Oriented Pyrolitic graphite crystals while for polarized neutron studies these will be replaced with Heusler alloy crystals. These focusing crystal arrays will be placed in a drum shield similar to those used for triple axis spectrometers. Hyspec will have a movable detector bank housing 160 position sensitive detectors. This detector bank will pivot about the sample axis. It will have a radius of 4.5m, a horizontal range of 60{sup o}, and a vertical range of {+-} 7.5{sup o}. In order to reduce background at the detector bank both a curved guide and a T0 chopper will be used. A bank of 20 supermirror bender polarization analyzers [2] will be used to spatially separate the polarized neutrons in the scattered beam so that both scattered neutron spin states can be measured simultaneously. The results of Monte Carlo simulations performed to optimize the instrument design will be discussed.

  1. The System of the Calibration for Visibility Measurement Instrument Under the Atmospheric Aerosol Simulation Environment

    Directory of Open Access Journals (Sweden)

    Shu Zhifeng

    2016-01-01

    Full Text Available Visibility is one of the most important parameters for meteorological observation and numerical weather prediction (NWP.It is also an important factor in everyday life, mainly for surface and air traffic especially in the Aeronautical Meteorology. The visibility decides the taking off and landing of aircraft. If the airport visibility is lower than requirement for aircraft taking off stipulated by International Civil Aviation Administration, then the aircraft must be parked at the airport. So the accurate measurement of visibility is very important. Nowadays, many devices can be measured the visibility or meteorological optical range (MOR such as Scatterometers, Transmissometers and visibility lidar. But there is not effective way to verify the accuracy of these devices expect the artificial visual method. We have developed a visibility testing system that can be calibration and verification these devices. The system consists of laser transmitter, optical chopper, phase-locking amplifier, the moving optic receiving system, signal detection and data acquisition system, atmospheric aerosol simulation chamber. All of them were placed in the atmosphere aerosol simulation chamber with uniform aerosol concentration. The Continuous wave laser, wavelength 550nm, has been transmitted into the collimation system then the laser beam expanded into 40mm diameter for compressing the laser divergence angle before modulated by optical chopper. The expanding beam transmitting in the atmosphere aerosol cabin received by the optic receiving system moving in the 50m length precision guide with 100mm optical aperture. The data of laser signal has been acquired by phase-locking amplifier every 5 meter range. So the 10 data points can be detected in the 50 meters guide once. The slope of the fitting curve can be obtained by linear fitting these data using the least square method. The laser extinction coefficient was calculated from the slope using the Koschmieder

  2. The System of the Calibration for Visibility Measurement Instrument Under the Atmospheric Aerosol Simulation Environment

    Science.gov (United States)

    Shu, Zhifeng; Yang, ShaoChen; Xu, Wenjing

    2016-06-01

    Visibility is one of the most important parameters for meteorological observation and numerical weather prediction (NWP).It is also an important factor in everyday life, mainly for surface and air traffic especially in the Aeronautical Meteorology. The visibility decides the taking off and landing of aircraft. If the airport visibility is lower than requirement for aircraft taking off stipulated by International Civil Aviation Administration, then the aircraft must be parked at the airport. So the accurate measurement of visibility is very important. Nowadays, many devices can be measured the visibility or meteorological optical range (MOR) such as Scatterometers, Transmissometers and visibility lidar. But there is not effective way to verify the accuracy of these devices expect the artificial visual method. We have developed a visibility testing system that can be calibration and verification these devices. The system consists of laser transmitter, optical chopper, phase-locking amplifier, the moving optic receiving system, signal detection and data acquisition system, atmospheric aerosol simulation chamber. All of them were placed in the atmosphere aerosol simulation chamber with uniform aerosol concentration. The Continuous wave laser, wavelength 550nm, has been transmitted into the collimation system then the laser beam expanded into 40mm diameter for compressing the laser divergence angle before modulated by optical chopper. The expanding beam transmitting in the atmosphere aerosol cabin received by the optic receiving system moving in the 50m length precision guide with 100mm optical aperture. The data of laser signal has been acquired by phase-locking amplifier every 5 meter range. So the 10 data points can be detected in the 50 meters guide once. The slope of the fitting curve can be obtained by linear fitting these data using the least square method. The laser extinction coefficient was calculated from the slope using the Koschmieder formula, then it been

  3. A Novel Infrared Gas Monitor

    Science.gov (United States)

    Wang, Yingding; Zhong, Hongjie

    2000-03-01

    In the paper a novel non-dispersive infrared(IR) gas monitor is described.It is based on the principle that certain gases absorb IR radiation at specific(and often unique) wavelengths.Conventional devices typically include several primary components:a broadband source, usually an incandescent filament,a rotating chopper shutter,a narrow-band filter,a sample tube and a detector. We have developed a number of IR light emitting diodes(LED) having narrow optical bandwidths and which can be intensity modulated by electrical means,for example InAsSbP(4.2 micron)LED.The IR LED can thus replace the thermal source,narrow-band filter and chopper assembly of the conventional IR gas monitor,yielding a solid state,low- powered,compact and almost maintenance-free instrument with high sensitivity and stability and which free of the effects of mechanical vibration too. The detector used in the IR gas monitor is the solid-state detector,such as PbS,PbSe, InSb,HgCdTe,TGS,LT and PZT detector etc. The different configuration of the IR gas monitor is designed.For example,two-path version for measuring methane concentration by monitoring the 3.31 micron absorption band,it can eliminate the interference effects,such as to compensate for LED intensity changes caused by power and temperature variations,and for signal fluctuations due to changes in detector bias. we also have designed portable single-beam version without the sample tube.Its most primary advantage is very cheap(about cost USD 30 ).It measures carbon dioxide concentration by monitoring the 4.25 micron absorption band.Thought its precisions is low,it is used to control carbon dioxide concentration in the air in the green houses and plastic houses(there are about twenty millon one in the China).Because more carbon dioxide will increase the quanity of vegetable and flower production to a greatextent. It also is used in medical,sanitary and antiepidemic applications,such as hospital, store,hotel,cabin and ballroom etc. Key words

  4. A survey of silage management practices on California dairies.

    Science.gov (United States)

    Heguy, J M; Meyer, D; Silva-del-Río, N

    2016-02-01

    The aim of the present study was to gather baseline information on corn silage-management practices to develop an outreach curriculum for dairy producers and growers. In spring 2013, dairy producers in the San Joaquin Valley (California) were surveyed on their silage-management practices. Response rate was 14.5% (n=160) and herd size averaged 1,512 milking cows. Harvest date was set solely by the dairy producer (53.4%) or with the assistance of the crop manager, custom chopper, or nutritionist (23.3%). On some dairies (23.3%), the dairy producer delegated the harvest date decision. Most dairies (75.0%) estimated crop dry matter before harvest, and the preferred method was milk line evaluation. Dairy producers were mostly unfamiliar with harvest rate but the number [1 (35.9%), 2 (50.3%), or 3 to 5 (13.8%)] and size [6-row (17.7%), 8-row (67.3%), or 10-row (15.0%)] of choppers working simultaneously was reported. Most dairies used a single packing tractor (68.8%) and weighed every load of fresh chopped corn delivered to the silage pit (62%). During harvest, dry matter (66.9%), particle length (80.4%), and kernel processing (92.5%) were monitored. Most dairies completed filling their largest silage structure in less than 3 d (48.5%) or in 4 to 7 d (30.9%). Silage covering was completed no later than 7 2h after structure completion in all dairies, and was often completed within 24 h (68.8%). Packed forage was covered as filled in 19.6% of dairies. Temporary covers were used on some dairies (51.0%), with filling durations of 1 to 60 d. When temporary covers were not used, structures were filled in no more than 15 d. After structure closure, silage feedout started in 1 to 3 wk (44.4%), 4 to 5 wk (31.4%), or 8 or more wk (24.2%). Future considerations included increasing the silage storage area (55.9%), increasing the number of packing tractors (37.0%), planting brown mid-rib varieties (34.4%), buying a defacer to remove silage (33.1%), and creating drive-over piles (32

  5. Neutron Compound Refractive Prisms - DOE SBIR Phase II Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Cremer, Jr, Jay Theodore

    2011-06-25

    The results of the research led to a pulsed electromagnetic periodic magnetic field array (PMF), which coupled with a pair of collimation slits, and a mechanical chopper slit, were able to deflect spin-up neutrons to a band of line-fused neutrons a focal plane heights that correspond to the time-varying magnetic field amplitude. The electromagnetic field PMF produced 5.4 pulses per minute in which each pulse was 50 msec in duration with a full width half maximum (FWHM) of 7.5 msec. The calculated 7.7 mm vertical height of the band of focused spin-up neutrons corresponded closely to the measured 7.5 mm height of the center line of the imaged band of neutrons. The band of deflected spin-up neutrons was 5 mm in vertical width and the bottom of the band was 5 mm above the surface of the PMF pole. The limited exposure time of 3 hours and the smaller 0.78 T magnetic field allowed focused and near focused neutrons of 1.8 to 2.6 neutrons, which were in the tails of the McClellan Nuclear Radiation Center Bay 4 Maxwell Boltzmann distribution of neutrons with peak flux at 1.1-1.2. The electromagnetic PMF was expected to produces a 2.0 T peak magnetic field amplitude, which would be operational at a higher duty factor, rather than the as built 7.5 msec FWHM with pulse repetition frequency of 5.4 pulses per minute. The fabricated pulsed electromagnetic PMF with chopper is expected to perform well on a cold, very cold or ultra cold beam line as a spectrometer or monochromator source of spin-up polarized neutron. In fact there may be a possible use of the PMF to do ultra-cold neutron trapping, see paper by A. I. Frank1, V. G. Nosov, Quantum Effects in a One-Dimensional Magnetic Gravitational Trap for Ultracold Neutrons, JETP Letters, Vol. 79, No. 7, 2004, pp. 313-315. The next step is to find a cold or very cold neutron facility, where further testing or use of the pulsed magnetic field PMF can be pursued.

  6. Research on the Pulse Electrolysis Power Supply with Soft-switch and Energy-release Function%带软开关和能量释放功能的脉冲电解电源的研制

    Institute of Scientific and Technical Information of China (English)

    石必利; 张永俊; 罗红平

    2015-01-01

    Aim at the problem of insufficient stability and no rapid protection for tools and workpiece in existing electrolytic power supply ,a specific protection functions is introduced. To improve current waveform and processing quality ,a topology including full-bridge inverter and chopper is employed on this power supply. Based on the traditional over current and over voltage protection ,the energy-release module is added to the power supply to provide a quick short-circuit protection system and a discharge channel for residual electric energy in inductor and capacitor timely ,in order to prevent voltage spike damage to the device ,and prevent large current damage to tools and workpiece. Based on routine chopper,soft-switch function module based on FPGA is proposed to reduce switch loss on chopping IGBT to decrease the temperature rise and improve the stability.%针对现有电解电源稳定性不足及对工具、工件保护不够及时的问题,提出一种带特殊保护功能的脉冲电解电源的实现方法。为改善输出电流波形,提高加工质量,电源采用全桥逆变加斩波的拓扑结构。在传统的过压、过流保护的基础上,增加能量快速释放功能模块,实现快速短路保护,及时为残留在电感电容中的电能提供泄放通道,防止电源系统损坏和工具、工件损伤。在常规斩波方式的基础上,提出基于FPGA的斩波软开关功能,在一定程度上降低斩波IGBT的开关损耗,减小了温升,提高了稳定性。

  7. The KAON Factory at TRIUMF

    International Nuclear Information System (INIS)

    The TRIUMF KAON Factory is designed to produce beams of kaons, antiprotons, other hadrons and neutrinos 100 times more intense, or cleaner, than are available now, for a broad range of particle and nuclear physics experiments. This will require a 100 μA beam of 30 GeV protons, to be produced by an interleaved sequence of two fast-cycling synchrotrons and three storage rings, with the existing TRIUMF H- cyclotron as injector. An $11-million preconstruction study has enabled the overall design to be reviewed and prototypes of various components to be built and evaluated -fast-cycling dipole and quadrupole magnets, a dual-frequency magnet power supply, ceramic beam pipes with internal rf shields, and rf cavity (using perpendicular bias), an extraction kicker, and rf beam chopper, and production targets. Environmental, industrial and economic impact studies have also been completed and the cost estimates and schedule updated. The total cost of $708 million (Canadian) will be shared equally between Canada, British Columbia and international contributors: the first two-thirds of this sum have already been approved and negotiations for the remainder are under way. 25 refs., 7 figs

  8. The KAON factory at TRIUMF

    International Nuclear Information System (INIS)

    The TRIUMF KAON Factory is designed to produce beams of kaons, antiprotons, other hadrons and neutrinos 100 times more intense, or cleaner, than are available now, for a broad range of particle and nuclear physics experiments. This will require a 100 μA beam of 30 GeV protons, to be produced by an interleaved sequence of two fast-cycling synchrotrons and three storage rings, with the existing TRIUMF H- cyclotron as injector. An $11-million pre-construction study has enabled the overall design to be reviewed and prototypes of various components to be built and evaluated: fast-cycling dipole and quadrupole magnets, a dual frequency magnet power supply, ceramic beam pipes with internal rf shields, an rf cavity (using perpendicular bias), an extraction kicker, an rf beam chopper, and production targets. Environmental, industrial and economic impact studies have also been completed and the cost estimates and schedule updated. The total cost of $708 million (Canadian) will be shared equally between Canada, British Columbia and international contributors; the first two-thirds of this sum have already been approved and negotiations for the remainder are under way. 26 refs., 6 figs

  9. Focusing adaptive-optics for neutron spectroscopy at extreme conditions

    Science.gov (United States)

    Simeoni, G. G.; Valicu, R. G.; Borchert, G.; Böni, P.; Rasmussen, N. G.; Yang, F.; Kordel, T.; Holland-Moritz, D.; Kargl, F.; Meyer, A.

    2015-12-01

    Neutron Spectroscopy employing extreme-conditions sample environments is nowadays a crucial tool for the understanding of fundamental scientific questions as well as for the investigation of materials and chemical-physical properties. For all these kinds of studies, an increased neutron flux over a small sample area is needed. The prototype of a focusing neutron guide component, developed and produced completely at the neutron source FRM II in Garching (Germany), has been installed at the time-of-flight (TOF) disc-chopper neutron spectrometer TOFTOF and came into routine-operation. The design is based on the compressed Archimedes' mirror concept for finite-size divergent sources. It represents a unique device combining the supermirror technology with Adaptive Optics, suitable for broad-bandwidth thermal-cold TOF neutron spectroscopy (here optimized for 1.4-10 Å). It is able to squeeze the beam cross section down to a square centimeter, with a more than doubled signal-to-background ratio, increased efficiency at high scattering angles, and improved symmetry of the elastic resolution function. We present a comparison between the simulated and measured beam cross sections, as well as the performance of the instrument within real experiments. This work intends to show the unprecedented opportunities achievable at already existing instruments, along with useful guidelines for the design and construction of next-generation neutron spectrometers.

  10. Progress on PEP-II magnet power conversion system

    International Nuclear Information System (INIS)

    The various power systems for supplying the PEP-II DC magnets rely exclusively on switchmode conversion, utilizing a variety of means depending on the requirements. All of the larger power supplies, ranging from 10 to 200 kW, are powered from DC sources utilizing rectified 480 V AC. Choppers can be used for the series connected strings, but for smaller groups and individual magnets, inverters driving high-frequency transformers with rectifiers comprise the best approach. All of the various systems use a ''building block'' approach of multiple standard-size units connected in series or parallel to most cost-effectively deal with a great range of voltage and current requirements. Utilization of existing infrastructure from PEP-I has been a cost-effective determinant. Equipment is being purchased either off-the-shelf, through performance specification, or by hardware purchase based on design-through-prototype. The corrector magnet power system, utilizing inexpensive, off-the-shelf, four-quadrant switching motor-controllers, has already proven very reliable: 120 of the total of 900 units have been running on the injection system for four months with no failures

  11. A novel source of MeV positron bunches driven by energetic protons for PAS application

    Science.gov (United States)

    Tan, Zongquan; Xu, Wenzhen; Liu, Yanfen; Xiao, Ran; Kong, Wei; Ye, Bangjiao

    2014-11-01

    This paper proposes a novel methodology of MeV positrons generation for PAS application. Feasibility of this proposal analyzed by G4Beamline and Transport have shown reasonable success. Using 2 Hz, 1.6 GeV, 100 ns and 1.5 μC/bunch proton bunches for bombarding a graphite target, about 100 ns e+ bunches are generated. Quasi-monochromatic positrons in the range of 1-10 MeV included in these bunches have a flux of >107/s, peak brightness of 1014/s. A magnetic-confinement beamline is utilized to transport the positrons and a "Fast Beam Chopper" is unprecedentedly extended to chop those relativistic bunches. The positron beam can be finally characterized by the energy range of 1-10 MeV and bunch width from one hundred ps up to 1 ns. Such ultrashort bunches can be useful in tomography-type positron annihilation spectroscopy (PAS) as well as other applications.

  12. The neutron reflectometer at 'SINQ'

    International Nuclear Information System (INIS)

    SINQ's dedicated reflectometer will be a flexible instrument in many respect. A 'white beam time of flight' as well as a 'constant wavelength' setup are possible for reflectometric experiments in a vertical scattering geometry. The phase controlled double chopper at the beginning of the instrument together with properly chosen time channels at the detector allow for the variation of the temporal resolution. Collimation slits serve to determine the angular resolution. In combination, the resolution can be tailored to the experimental needs. Additionally, one can adjust the illumination of the sample by setting the sample table and the detector to an appropriate distance. A mounting for exchangeable mirrors can be used to supply polarized neutrons by a multilayer polarizer or monochromatic neutrons by a multilayer monochromator. When it is equipped with a supermirror as a deflecting unit one can maintain a horizontal sample position which makes reflectometry on liquid samples practicable. Remanent polarizers are assigned for the changing over of the neutron polarization. A 1 T electromagnet installed on the sample manipulation table and polarization analyzers complete the polarized reflectometry setup. Alternately, an x-y-detector and single detectors will be available. By 1997/1998 the neutron reflectometer will be operational as a users' instrument. (author) 9 figs., 2 tabs., 30 refs

  13. Measurement of IR atmospheric band dayglow by S-520-4 rocket

    International Nuclear Information System (INIS)

    The measurement of IR atmospheric band dayglow was made by rocket S-520-4 flown from Uchinoura at 1000 JST on Sept. 5, 1981. The instrument loaded on the rocket was the same type as the one loaded on EXOS-C satellite which will be launched in 1984 in order to observe the mesospheric ozone. This rocket experiment was performed for the purpose of testing the functions of this instrument in flight. The 1.27 μm filter radiometer consisted of three plane mirros, a camera lens, a chopper and a PbS detector array. The PbS array (4x5=20 elements) was operated at about -40C with a thermoelectric cooler. We obtained the following results from the rocket experiment: (i) this instrument worked well during the flight, (ii) the intensities of the solar radiation scattered by the sea and clouds were obtained at 1.27 μm, and (iii) the baffle designed to permit the daytime measurement of the atmospheric emission could attenuate the off-axis radiation as weak as possible. The altitude distribution of the daytime mesospheric ozone density derived from the downleg data was in agreement with the previous profile obtained in twilight condition. (author)

  14. Computational analysis on plug-in hybrid electric motorcycle chassis

    Science.gov (United States)

    Teoh, S. J.; Bakar, R. A.; Gan, L. M.

    2013-12-01

    Plug-in hybrid electric motorcycle (PHEM) is an alternative to promote sustainability lower emissions. However, the PHEM overall system packaging is constrained by limited space in a motorcycle chassis. In this paper, a chassis applying the concept of a Chopper is analysed to apply in PHEM. The chassis 3dimensional (3D) modelling is built with CAD software. The PHEM power-train components and drive-train mechanisms are intergraded into the 3D modelling to ensure the chassis provides sufficient space. Besides that, a human dummy model is built into the 3D modelling to ensure the rider?s ergonomics and comfort. The chassis 3D model then undergoes stress-strain simulation. The simulation predicts the stress distribution, displacement and factor of safety (FOS). The data are used to identify the critical point, thus suggesting the chassis design is applicable or need to redesign/ modify to meet the require strength. Critical points mean highest stress which might cause the chassis to fail. This point occurs at the joints at triple tree and bracket rear absorber for a motorcycle chassis. As a conclusion, computational analysis predicts the stress distribution and guideline to develop a safe prototype chassis.

  15. Profile and Emittance Measurements at the CERN LINAC4 3 MeV test Stand

    CERN Document Server

    Zocca, F; Duraffourg, M; Focker, GJ; Gerard, D; Raich, U; Roncarolo, F

    2013-01-01

    A new 160 MeV H- Linac named Linac-4 will be built at CERN to replace the old 50 MeV proton Linac. The ion source, the 3 MeV Radio Frequency Quadrupole (RFQ) and the Medium Energy Beam Transport (MEBT) line hosting a chopper, have been commissioned in a dedicated test stand. Wire grids and wire scanners were used to measure the transverse beam profile and a slit/grid emittance meter was installed on a temporary test bench plugged at the RFQ and MEBT exit in different stages. The emittance meter slit was also used as a scanning scraper able to reconstruct the transverse profile by measuring the transmission with a downstream current transformer. On the same measurement bench, a spectrometer in conjunction with a wire grid allowed measuring the energy spread of the particles. This paper summarizes the measurement results that allowed characterizing the 3 MeV beam and discusses the present understanding of monitor performance.

  16. Slow light in ruby: delaying energy beyond the input pulse

    Science.gov (United States)

    Wisniewski-Barker, Emma; Gibson, Graham; Franke-Arnold, Sonja; Shi, Zhimin; Narum, Paul; Boyd, Robert W.; Padgett, Miles J.

    2015-03-01

    The mechanism by which light is slowed through ruby has been the subject of great debate. To distinguish between the two main proposed mechanisms, we investigate the problem in the time domain by modulating a laser beam with a chopper to create a clean square wave. By exploring the trailing edge of the pulsed laser beam propagating through ruby, we can determine whether energy is delayed beyond the input pulse. The effects of a time-varying absorber alone cannot delay energy into the trailing edge of the pulse, as a time-varying absorber can only attenuate a coherent pulse. Therefore, our observation of an increase in intensity at the trailing edge of the pulse provides evidence for a complicated model of slow light in ruby that requires more than just pulse reshaping. In addition, investigating the Fourier components of the modulated square wave shows that harmonic components with different frequencies are delayed by different amounts, regardless of the intensity of the component itself. Understanding the difference in delays of the individual Fourier components of the modulated beam reveals the cause of the distortion the pulse undergoes as it propagates through the ruby.

  17. Complementarity of long pulse and short pulse spallation sources

    International Nuclear Information System (INIS)

    The complementarity of short pulse spallation sources (SPSS) and steady state (CW) reactors is a widely accepted concept. SPSS and long pulse spallation sources (LPSS) are complementary in two ways: a) in their performance in neutron scattering experiments LPSS closely emulate CW reactors. In this respect two facets of the time-of-flight (TOF) monochromator method adequate for LPSS will be discussed: the superiority of the TOF approach to the crystal monochromator method in high resolution powder diffraction, and the novel technique of repetition rate multiplication in TOF spectroscopy, b) LPSS combined with adequate chopper systems can also emulate SPSS in a number of applications. It will be shown that the LPSS method of producing short neutron pulses is more efficient for cold and thermal neutrons (below an energy of about 100 MeV), while SPSS is the more favourable approach for hot, epithermal neutrons, i.e. in the slowing down regime in contrast to the moderated regime. These two aspects of complementarity of LPSS and SPSS lead to the conclusions that for about 75% of the spectrum of neutron scattering experiments as known of today the LPSS approach is the most advantageous one with a feasible neutron intensity exceeding that available at ILL by a factor of about 30, while for the remaining 25% of applications the SPSS technique is superior with a well-known potential of a similar gain over present day performances. (author) 7 figs., 6 refs

  18. Latest version of the Munich pulsed low energy positron system

    International Nuclear Information System (INIS)

    Further improvements of the Munich pulsed low energy positron system have been performed. A new chopper, configured as a double plate deflection system with an external resonator and a new buncher working like a classical double gap buncher, are implemented. The complete rf-power electronic was redesigned and operates now at an overall master-frequency of 50 MHz for all bunching and chopping components. A new target station with an enlarged Faraday cage is installed. The sample temperature is variable between 30 K and 600 K. Up to ten samples can be stored in a magazine and transferred under vacuum conditions to the measuring position. With a primary source of 30 mCi 22Na a count rate of up to 4 kHz can be achieved with a peak-to-background ratio of 3000:1. This ratio can be further improved by the use of a Wien filter. A beam diameter of about 2 mm was determined. The total time resolution (pulsing plus detector system) is 250 ps (FWHM). (orig.)

  19. The multipurpose time-of-flight neutron reflectometer 'Platypus' at Australia's OPAL reactor

    International Nuclear Information System (INIS)

    In this manuscript we describe the major components of the Platypus time-of-flight neutron reflectometer at the 20 MW OPAL reactor in Sydney, Australia. Platypus is a multipurpose spectrometer for the characterisation of solid thin films, materials adsorbed at the solid-liquid interface and free-liquid surfaces. It also has the capacity to study magnetic thin films using spin-polarised neutrons. Platypus utilises a white neutron beam (λ=2-20 A) that is pulsed using boron-coated disc chopper pairs; thus providing the capacity to tailor the wavelength resolution of the pulses to suit the system under investigation. Supermirror optical components are used to focus, deflect or spin-polarise the broad bandwidth neutron beams, and typical incident spectra are presented for each configuration. A series of neutron reflectivity datasets are presented, indicating the quality and flexibility of this spectrometer. Minimum reflectivity values of -7 are observed; while maximum thickness values of 325 nm have been measured for single-component films and 483 nm for a multilayer system. Off-specular measurements have also been made to investigate in-plane features as opposed to those normal to the sample surface. Finally, the first published studies conducted using the Platypus time-of-flight neutron reflectometer are presented.

  20. The multipurpose time-of-flight neutron reflectometer 'Platypus' at Australia's OPAL reactor

    Energy Technology Data Exchange (ETDEWEB)

    James, M., E-mail: mja@ansto.gov.a [Bragg Institute, Building 87, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); School of Chemistry, University of New South Wales, Kensington, NSW 2052 (Australia); Nelson, A.; Holt, S.A.; Saerbeck, T.; Hamilton, W.A.; Klose, F. [Bragg Institute, Building 87, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia)

    2011-03-11

    In this manuscript we describe the major components of the Platypus time-of-flight neutron reflectometer at the 20 MW OPAL reactor in Sydney, Australia. Platypus is a multipurpose spectrometer for the characterisation of solid thin films, materials adsorbed at the solid-liquid interface and free-liquid surfaces. It also has the capacity to study magnetic thin films using spin-polarised neutrons. Platypus utilises a white neutron beam ({lambda}=2-20 A) that is pulsed using boron-coated disc chopper pairs; thus providing the capacity to tailor the wavelength resolution of the pulses to suit the system under investigation. Supermirror optical components are used to focus, deflect or spin-polarise the broad bandwidth neutron beams, and typical incident spectra are presented for each configuration. A series of neutron reflectivity datasets are presented, indicating the quality and flexibility of this spectrometer. Minimum reflectivity values of <10{sup -7} are observed; while maximum thickness values of 325 nm have been measured for single-component films and 483 nm for a multilayer system. Off-specular measurements have also been made to investigate in-plane features as opposed to those normal to the sample surface. Finally, the first published studies conducted using the Platypus time-of-flight neutron reflectometer are presented.

  1. ATOMIC BEAM POLARIZATION MEASUREMENT OF THE RHIC POLARIZED H-JET TARGET.

    Energy Technology Data Exchange (ETDEWEB)

    MAKDISI,Y.; NASS,A.; GRAHAM,D.; KPONOU,A.; MAHLER,G.; MENG,W.; RITTER,J.; ET AL.

    2005-01-28

    The RHIC polarized H-Jet measures the polarization of the RHIC proton beam via elastic scattering off a nuclear polarized atomic hydrogen beam. The atomic beam is produced by a dissociator, a beam forming system and sextupole magnets. Nuclear polarization is achieved by exchanging occupation numbers of hyperfine states using high frequency transitions. The polarization was measured using a modified form of a Breit-Rabi polarimeter including focusing magnets and another set of high frequency transitions. The sampling of a large part of the beam and low noise electronics made it possible to measure the polarization to a high degree of accuracy in a very short time period (1 min). Using this system, we measured no depolarization of the atomic beam due to the RF fields of the bunched proton beam. Time-of-Flight measurements were done using a fast chopper and a QMA at the position of the RHIC interaction point to determine the areal density of the atomic beam seen by the RHIC beam.

  2. The System of Nanosecond 280-keV-He+ Pulsed Beam

    CERN Document Server

    Junphong, Pimporn; Lekprasert, Banyat; Suwannakachorn, Dusadee; Thongnopparat, N; Vilaithong, Thiraphat; Wiedemann, Helmut

    2005-01-01

    At Fast Neutron Research Facility,the 150 kV-pulseds neutron generator is being upgraded to produce a 280-keV-pulsed-He beam for time-of-flight Rutherford backscattering spectrometry. It involves replacing the existing beam line elements by a multicusp ion source, a 400-kV accelerating tube, 45o-double focusing dipole magnet and quadrupole lens. The Multicusp ion source is a compact filament-driven of 2.6 cm in diameter and 8 cm in length. The current extracted is 20.4 μA with 13 kV of extraction voltage and 8.8 kV of Einzel lens voltage. The beam emittance has been found to vary between 6-12 mm mrad. The beam transport system has to be redesigned based on the new elements. The important part of a good pulsed beam depends on the pulsing system. The two main parts are the chopper and buncher. An optimized geometry for the 280 keV pulsed helium ion beam will be presented and discussed. The PARMELA code has been used to optimize the space charge effect, resulting in pulse width of less than 2 ns at a t...

  3. A beam-displacement prism based, three band stellar photo-polarimeter

    CERN Document Server

    Raveendran, A V; Muneer, S; Mekkaden, M V; Jayavel, N; Somashekar, M R; Sagayanathan, K; Ramamoorthy, S; Rosario, M J; Jayakumar, K

    2015-01-01

    A new astronomical photo-polarimeter that can measure linear polarization of point sources simultaneously in three spectral bands was designed and built in Indian Institute of Astrophysics. The polarimeter has a Calcite beam-displacement prism as the analyzer. The ordinary and extra-ordinary emerging beams in each spectral band are quasi-simultaneously detected by the same photomultiplier by using a high speed rotating chopper. The effective chopping frequency can be set to as high as 200 Hz. A rotating superachromatic Pancharatnam halfwave plate is used to modulate the light incident on the analyzer. The spectral bands are isolated using appropriate dichroic and glass filters. A detailed analysis shows that the reduction of 50% in the efficiency of the polarimeter because of the fact that the intensities of the two beams are measured alternately is partly compensated by the reduced time to be spent on the observation of the sky background. The position angle of polarization produced by the Glan-Taylor prism ...

  4. A multi-spectral band stellar photo-polarimeter

    CERN Document Server

    Srinivasulu, G; Muneer, S; Mekkaden, M V; Jayavel, N; Somashekar, M R; Sagayanathan, K; Ramamoorthy, S; Rosario, M J; Jayakumar, K

    2015-01-01

    We designed and built a new astronomical photo-polarimeter that can measure linear polarization simultaneously in three spectral bands. It has a Calcite beamdisplacement prism as the analyzer. The ordinary and extra-ordinary emerging beams in each spectral bands are quasi-simultaneously detected by the same photomultiplier by using a high speed rotating chopper. A rotating superachromatic Pancharatnam halfwave plate is used to modulate the light incident on the analyzer. The spectral bands are isolated using appropriate dichroic and glass filters. We show that the reduction of 50% in the efficiency of the polarimeter because of the fact that the intensities of the two beams are measured alternately is partly compensated by the reduced time to be spent on the observation of the sky background. The use of a beam-displacement prism as the analyzer completely removes the polarization of background skylight, which is a major source of error during moonlit nights, especially, in the case of faint stars. The field t...

  5. The SPL Front End: A 3 MeV$H^{-}$ Test Stand at CERN

    CERN Document Server

    Rossi, C; Caspers, Friedhelm; Garoby, R; Genest, J; Hanke, K; Hori, Masaki; Küchler, D; Lombardi, A M; Magistris, M; Millich, Antonio; Paoluzzi, M; Sargsyan, E; Silari, M; Steiner, T; Vretenar, M; Beauvais, Pierre Yves; Ausset, P; LINAC'04

    2004-01-01

    In the frame of the SPL (Superconducting Proton Linac) study at CERN, a new 160 MeV proton injector for the CERN PS Booster is presently under development. This linear accelerator (Linac4) would not only be a first step towards a future, multi-MW superconducting linac, but would also improve in the medium term both the beam availability and beam quality for CERN’s proton users. Within the framework of the Linac4 study and with the support of the EU funded Joint Research Activity HIPPI (High Intensity Pulsed Proton Injectors), a 3 MeV test stand is under construction at CERN. This test stand will explore some of the most critical issues of the linac, such as the beam dynamics at low energy, with special emphasis on the chopper line that has been designed to generate the required time structure of the beam, to clean the beam halo, and to match it to the subsequent RF structures. In this context, a new Beam Shape and Halo Monitor is under construction. The beam acceleration will be performed by an RFQ that is ...

  6. Fabrication of Multi-Harmonic Buncher for Pulsed Proton Beam Generation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H. S.; Kwon, H. J.; Cho, Y. S. [Korea Multipurpose Accelerator Complex, Gyeongju (Korea, Republic of)

    2015-05-15

    Fast neutrons with a broad spectrum can be generated by irradiating the proton beams on target materials. To measure the neutron energy by time of flight (TOF) method, the short pulse width of the proton beam is preferred because the neutron energy uncertainty is proportional to the pulse width. In addition, the pulse repetition rate should be low enough to extend the lower limit of the available neutron energy. Pulsed proton beam generation system is designed based on an electrostatic deflector and slit system as shown in Fig. 1. In a simple deflector with slit system, most of the proton beam is blocked by slit, especially when the beam pulse width is short. The ideal field pattern inside the buncher cavity is saw-tooth wave. To make the field pattern similar to the saw-tooth waveform, we adopted a multi-harmonic buncher (MHB). The design for the multi-harmonic buncher including 3D electromagnetic calculation has been performed. Based on the design, a multi-harmonic buncher cavity was fabricated. It consists of two resonators, two drift tubes and a vacuum chamber. The resonator is a quarter-wave coaxial resonator type. The drift tube is connected to the resonator by using a coaxial vacuum feedthrough. Design summary and detailed fabrication method of the multi-harmonic buncher is presented in this paper. A multi-harmonic buncher for a proton beam chopper system to generate a short pulse neutron beam was designed, fabricated and assembled.

  7. Evaluation of a handling system for ley crop used in biogas production. Capacities and costs for a centralised system

    Energy Technology Data Exchange (ETDEWEB)

    Vaagstroem, Lena

    2005-07-01

    Within the Vaextkraft project in Vaesteraas, Sweden, biogas is to be produced out of ley crop and organic waste. The aim of this study has been to estimate the capacities within the handling system used for the ley crop harvest, and the resources needed. For this purpose a model in the form of a calculation program in Excel was built. The model makes it possible to vary parameters such as transport system design, distance from fields to storage, dry matter content and yield. The results showed that it is essential to match the capacities between chopper and transport to minimise the time and cost connected to the harvest. To avoid creating costly bottlenecks in the Vaextkraft case the transport system has to consist of at least two trucks with trailers. The estimates made with the model suggests that the distance to storage is strongly linked to the dimensioning of the transport system, whereas the number of fields and their size has a lesser impact on harvest time and cost. Variation of the dry matter yield from a base scenario had an impact on the cost for harvesting, but not on the choice of transport system. The model couldn't detect any reliable differences in total costs due to the variation of dry matter content between 25-45%. The choice of chopping machinery in the Vaextkraft project leads to small timeliness costs. Together with a reasonable choice of transport system they will only constitute a few percent of the total costs for harvesting.

  8. Word-decoding as a function of temporal processing in the visual system.

    Directory of Open Access Journals (Sweden)

    Steven R Holloway

    Full Text Available This study explored the relation between visual processing and word-decoding ability in a normal reading population. Forty participants were recruited at Arizona State University. Flicker fusion thresholds were assessed with an optical chopper using the method of limits by a 1-deg diameter green (543 nm test field. Word decoding was measured using reading-word and nonsense-word decoding tests. A non-linguistic decoding measure was obtained using a computer program that consisted of Landolt C targets randomly presented in four cardinal orientations, at 3-radial distances from a focus point, for eight compass points, in a circular pattern. Participants responded by pressing the arrow key on the keyboard that matched the direction the target was facing. The results show a strong correlation between critical flicker fusion thresholds and scores on the reading-word, nonsense-word, and non-linguistic decoding measures. The data suggests that the functional elements of the visual system involved with temporal modulation and spatial processing may affect the ease with which people read.

  9. The Effect of a Brief Salivary α-Amylase Exposure During Chewing on Subsequent in Vitro Starch Digestion Curve Profiles

    Directory of Open Access Journals (Sweden)

    Charles S. Brennan

    2010-07-01

    Full Text Available There is inconsistency between current in vitro digestion methods with regard to accommodation of a (salivary α-amylase exposure during the oral phase. The effect of a salivary α-amylase pre-exposure on subsequent in vitro starch digestion curve profiles for various foods was investigated. Foods were chewed, expectorated and the boluses left to rest for 0–15 min. During pancreatic digestion, aliquots were taken and hydrolysis curves constructed for comparison against those of the same foods comminuted with a manually-operated chopper, hence spared exposure to saliva. Hydrolysate aliquots taken at T0 (time zero of the digestion of chewed samples contained higher levels of glucose and dextrins compared with chopped samples. Pancreatin activity immediately overwhelmed differences in sugar released due to salivary amylase activity. Within 10 min no differences were detectable between hydrolysis curves for chewed and chopped foods. Salivary amylase pretreatment does not contribute to the robustness or relative accuracy of in vitro methods.

  10. Neutron diffractometers for structural biology at spallation neutron sources

    International Nuclear Information System (INIS)

    Spallation neutron sources are ideal for diffraction studies of proteins and oriented molecular complexes. With spoliation neutrons and their time dependent wavelength structure, it is easy to electronically select data with an optimal wavelength bandwidth and cover the whole Laue spectrum as time (wavelength) resolved snapshots. This optimized data quality with best peak-to-background ratios and provides adequate spatial and energy resolution to eliminate peak overlaps. The application of this concept will use choppers to select the desired Laue wavelength spectrum and employ focusing optics and large cylindrical 3He detectors to optimize data collection rates. Such a diffractometer will cover a Laue wavelength range from 1 to 5 Angstrom with a flight path length of 10m and an energy resolution of 0.25 Angstrom. Moderator concepts for maximal flux distribution within this energy range will be discussed using calculated flux profiles. Since the energy resolution required for such timed data collection in this super Laue techniques is not very high, the use of a linac only (LAMPF) spoliation target is an exciting possibility with an order of magnitude increase in flux

  11. Variation of the Binary-to-Ternary Fission Ratio for U235 in the Thermal-Neutron-Energy Region

    International Nuclear Information System (INIS)

    The slow chopper installed at BRI was used to make an accurate determination of the binary-to-ternary fission ratio for U235 in the neutron-energy range from 0.005 eV to 0.2 eV. Large gold-silicon suríace-barrier detectors are used for the consecutive measurement of long-range α-particles (absorber in) and fission fragments (absorber out). The time analysis is done with a 100-channel time-of-flight analyser. A one-metre flight-path and a rotor speed of 50 rev/s is used. The B/T ratio was also measured with a high statistical accuracy (about 1%) in intense beams with well-defined neutron spectra, i.e. a ''cold neutron'' beam, a beam extracted from a thermal column and a beam of 0.3-eV neutrons produced by crystal diffraction. The B/T ratio exhibits a small and smooth variation in the energy range considered. This effect seems to be correlated with measurements of some other fission parameters in the same neutron-energy range. (author)

  12. The Transmission of Thermal Neutrons through a Large Single Crystal of Bismuth at Liquid Nitrogen Temperature

    International Nuclear Information System (INIS)

    The transmission of a bismuth filter, at the temperature of liquid nitrogen, was measured using a slow chopper and a flight path of 5.4 m. The filter is made of two ''single crystals'', each 20 cm long and 5 cm in diameter. According to specification of the manufacturer each ''single crystal'' consists of maximum three of four columns of single crystals. In the energy range from 25 - 10 meV, the transmitted intensity is about 30% of the expected value. In the range from 5 meV to lower energies, the transmission is of the order of 60 - 70%. A cadmium ratio of 5000 was measured. The actual cadmium ratio may still be higher since the measurement was not made with a really fast neutron collimator. In spite of manv coherent dips in the transmission curve, the performance of the filter is rather satisfactory for thhe production of a thermal neutron beam that is predominantly free from fast neutrons and γ-rays. Possible applications of a filtered neutron beam are discussed. (author)

  13. Two instruments for far-infrared astrophysics

    International Nuclear Information System (INIS)

    Two instruments for far-infrared astrophysics are described. The first is a broad-band photometer used on White Mountain for astronomical observations from 10 to 30 cm-1 (300 GHz to 1 THz; lambda, 1 mm to 330 μ). The optical system of the telescope includes a light-weight, high-speed, chopping secondary. The L 4He-cooled photometer uses low-pass filters and a L3He-cooled, composite bolometer. The system performance is evaluated, and the site is compared to other possible platforms. The second project is a balloon-borne spectroradiometer to measure the cosmic background radiation from 3 to 10 cm-1 (100 GHz to 300 GHz; lambda, 3 mm to 1 mm). The apparatus has five band-pass filters with excellent rejection at higher frequencies, a low-noise chopper, and an internal calibrator. We describe the design and use of calibrators for such an experiment and develop a model of calibration procedures. The calibrations of several reported measurements are analyzed with this model, and flaws are found in one procedure. Finally, the system performance is used to estimate the accuracy this experiment can achieve

  14. Development of a DC propulsion system for an electric vehicle

    Science.gov (United States)

    Kelledes, W. L.

    1984-01-01

    The suitability of the Eaton automatically shifted mechanical transaxle concept for use in a near-term dc powered electric vehicle is evaluated. A prototype dc propulsion system for a passenger electric vehicle was designed, fabricated, tested, installed in a modified Mercury Lynx vehicle and track tested at the contractor's site. The system consisted of a two-axis, three-speed, automatically-shifted mechanical transaxle, 15.2 Kw rated, separately excited traction motor, and a transistorized motor controller with a single chopper providing limited armature current below motor base speed and full range field control above base speed at up to twice rated motor current. The controller utilized a microprocessor to perform motor and vehicle speed monitoring and shift sequencing by means of solenoids applying hydraulic pressure to the transaxle clutches. Bench dynamometer and track testing was performed. Track testing showed best system efficiency for steady-state cruising speeds of 65-80 Km/Hz (40-50 mph). Test results include acceleration, steady speed and SAE J227A/D cycle energy consumption, braking tests and coast down to characterize the vehicle road load.

  15. Synergistic effect of EUV from the laser-sustained detonation plasma in a ground-based atomic oxygen simulation on fluorinated polymers

    International Nuclear Information System (INIS)

    The contribution of extreme ultraviolet (EUV) from a laser-sustained plasma on the mass loss phenomenon of fluorinated polymer in a ground-based laser-detonation atomic oxygen beam source was evaluated. The atomic oxygen beam and EUV from the oxygen plasma were separated by the high-speed chopper wheel installed in the beam source. The mass changes of the fluorinated polymer and polyimide were measured from the frequency shift of the quartz crystal microbalance during the beam exposures. It has been made clear that the fluorinated polymer erodes by EUV exposure alone. In contrast, no erosion was detected for polyimide by EUV alone. The atomic oxygen-induced erosion was measured for both materials even without EUV exposure. However, no strong synergistic effect was observed for a fluorinated polymer even under the simultaneous exposure condition of atomic oxygen and EUV. Similar results were observed even in simultaneous exposure of atomic oxygen (without EUV) and 172 nm vacuum ultraviolet (VUV) from an excimer lamp. These experiments suggest that the primary origin of the accelerated erosion of fluorinated polymer observed in a laser detonation atomic oxygen source is not the EUV from the laser-sustained plasma.

  16. Monte Carlo simulation of the spear reflectometer at LANSCE

    International Nuclear Information System (INIS)

    The Monte Carlo instrument simulation code, MCLIB, contains elements to represent several components found in neutron spectrometers including slits, choppers, detectors, sources and various samples. Using these elements to represent the components of a neutron scattering instrument, one can simulate, for example, an inelastic spectrometer, a small angle scattering machine, or a reflectometer. In order to benchmark the code, we chose to compare simulated data from the MCLIB code with an actual experiment performed on the SPEAR reflectometer at LANSCE. This was done by first fitting an actual SPEAR data set to obtain the model scattering-length-density profile, Β(z), for the sample and the substrate. Then these parameters were used as input values for the sample scattering function. A simplified model of SPEAR was chosen which contained all of the essential components of the instrument. A code containing the MCLIB subroutines was then written to simulate this simplified instrument. The resulting data was then fit and compared to the actual data set in terms of the statistics, resolution and accuracy

  17. Exploring control parameters of two photon processes in solutions

    Indian Academy of Sciences (India)

    Debabrata Goswami; Amit Nag

    2012-01-01

    Two-photon microscopy depends extensively on the two-photon absorption cross-sections of biologically relevant chromophores. High repetition rate (HRR) lasers are essential in multiphoton microscopy for generating satisfactory signal to noise at low average powers. However, HRR lasers generate thermal distortions in samples even with the slightest single photon absorption. We use an optical chopper with HRR lasers to intermittently `blank’ irradiation and effectively minimize thermal effects to result in a femtosecond z-scan setup that precisely measures the two-photon absorption (TPA) cross-sections of chromophores. Though several experimental factors impact such TPA measurements, a systematic effort to modulate and influence TPA characteristics is yet to evolve. Here, we present the effect of several control parameters on the TPA process that are independent of chromophore characteristics for femtosecond laser pulse based measurements; and demonstrate how the femtosecond laser pulse repetition rate, chromophore environment and incident laser polarization can become effective control parameters for such nonlinear optical properties.

  18. Neutron Spectra in Subcritical Graphite- and Beryllia-Moderated Assemblies

    International Nuclear Information System (INIS)

    A number of subcritical graphite- and beryllia-moderated assemblies fuelled with plutonium and highly enriched uranium plates have been constructed with ratios of moderator atoms to fissile atoms as low as 300. As part of a general study of these small under moderated systems in which fission takes place predominantly at energies above 0.1 eV , time-of-flight measurements have been carried out using a neutron chopper having a resolution of 4 μs/m. This adequately resolves the spectrum in the thermal region and in the region of the resonance in 239Pu at 0.296 eV. Calculations have been carried out using a multigroup transport code with scattering matrices for graphite and beryllia based on data obtained from the Chalk River scattering law experiments. A correct weighting over the experimental source area of the vector flux in the direction of the extracted beam produces a spectrum which can be compared directly with the observed spectrum. It has been found that in the region 0.4 to 1.0 eV the experimental spectra have fewer neutrons than are predicted and this is particularly noticeable in the BeO-moderated assemblies. The factors which could give rise to the discrepancy are discussed but it has not been possible to attribute it to any particular one. (author)

  19. Beam transport and polarization at TOPAS, the thermal time-of-flight spectrometer with polarization analysis

    International Nuclear Information System (INIS)

    We present the design for the polarization analysis of the future thermal time-of-flight spectrometer at the Juelich Centre for Neutron Science (JCNS) at the FRM II. TOPAS is a time-of-flight spectrometer covering a range of incident energies 20 meV i 0 0. A set of Fermi choppers selects the incoming energy Ei with a resolution up to 3 %. The instrument is optimized for a high flux on small samples using an elliptical neutron guide. The special feature of TOPAS is the polarization analysis. The incident polarization will be realized by means of a 3He continuously pumped polarizer, which is a downscaled version of the device developed for small angle applications at JCNS. The polarization analysis over a wide angular range demands either short distances between the sample and the analyzer or a large volume of polarized 3He. Here we propose the latter alternative to allow the study of magnetic samples and modest magnetic fields at the sample position.

  20. Far Sidelobes Measurement of the Atacama Cosmology Telescope

    Science.gov (United States)

    Duenner, Rolando; Gallardo, Patricio; Wollack, Ed; Henriquez, Fernando; Jerez-Hanckes, Carlos

    2012-01-01

    The Atacama Cosmology Telescope (ACT) is a 6m telescope designed to map the Cosmic Microwave Background (CMB) simultaneously at 145GHz, 220 GHz and 280 GHz. Its off-axis Gregorian design is intended to minimize and control the off-axis sidelobe response, which is critical for scientific purposes. The expected sidelobe level for this kind of design is less than -50 dB and can be challenging to measure. Here we present a measurement of the 145 GHz far sidelobes of ACT done on the near-field of the telescope. We used a 1 mW microwave source placed 13 meters away from the telescope and a chopper wheel to produce a varying signal that could be detected by the camera for different orientations of the telescope. The source feed was designed to produce a wide beam profile. Given that the coupling is expected to be dominated by diffraction over the telescope shielding structure, when combined with a measurements of the main beam far field response, these measurement can be used to validate elements of optical design and constrain the level of spurious coupling at large angles. Our results show that the diffractive coupling beyond the ground screen is consistently below -75 dB, satisfying the design expectations.

  1. H- Ion Sources For CERN’s Linac4

    CERN Document Server

    Lettry, J; Coutron, Y; Chaudeta, E; Dallocchio, A; Gil Flores, J; Hansen, J; Mahner, E; Mathot, S; Mattei, S; Midttun, O; Moyret, P; Nisbet, D; O’Neil, M; Paoluzzi, M; Pasquino, C; Pereira, H; Sanchez Arias, J; Schmitzer, C; Scrivens, R; Steyaert, D

    2013-01-01

    The specifications set to the Linac4 ion source are: H- ion pulses of 0.5 ms duration, 80 mA intensity and 45 keV energy within a normalized emittance of 0.25 mmmrad RMS at a repetition rate of 2 Hz. In 2010, during the commissioning of a prototype based on H- production from the plasma volume, it was observed that the powerful co-extracted electron beam inherent to this type of ion source could destroy its electron beam dump well before reaching nominal parameters. However, the same source was able to provide 80 mA of protons mixed with a small fraction of H2+ and H3+ molecular ions. The commissioning of the radio frequency quadrupole accelerator (RFQ), beam chopper and H- beam diagnostics of the Linac4 are scheduled for 2012 and its final installation in the underground building is to start in 2013. Therefore, a crash program was launched in 2010 and reviewed in 2011 aiming at keeping the original Linac4 schedule with the following deliverables: Design and production of a volume ion source prototype suitabl...

  2. Microcontroller based two axis microtron beam extraction system

    International Nuclear Information System (INIS)

    Microtron is an electron accelerator which is used to accelerate the electron beam. The Microtron consists of electro magnet with two poles separated by yoke for completion of path for magnetic flux lines. A compact Microtron capable of accelerating electrons up to 12 MeV has been developed in RRCAT. The beam from the Microtron has to be extracted from various orbits depending upon the user requirement (X-Y stage is built with an accuracy of 100 μm). This paper describes the design and development of microcontroller based two axis beam extraction system for Microtron, with a resolution of 50 μm to position the extraction tube with respect to selected orbit. Two axis motion controller is developed using current controlled micro-stepping driver mechanism, which uses Bipolar Chopper Drive for driving stepper motors. Each phase has 2A continuous driving capability. The system is provided with user selectable controls like speed, steps, direction, and mode. This system is provided with RS-232 interface, to accept commands from PC. This system also has local keyboard and LCD interface to use in Stand-alone mode (local Mode). (author)

  3. All-optical logic gate based on transient grating from disperse red 1 doped organic-inorganic hybrid films with an improved figure of merit

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Tianxi; Que, Wenxiu, E-mail: wxque@mail.xjtu.edu.cn; Shao, Jinyou [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, International Center for Dielectric Research, School of Electronic and Information Engineering, State Key Laboratory for Manufacturing Systems Engineering, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China); Wang, Yushu [School of Materials Science and Engineering, Georgia Institute of Technology, 500 Tenth Street NW, Atlanta, Georgia 30318 (United States)

    2015-10-21

    Azobenzene dyes have large refractive index near their main resonance, but the poor figure of merit (FOM) limits their potential for all-optical applications. To improve this situation, disperse red 1 (DR1) molecules were dispersed in a sol-gel germanium/Ormosil organic-inorganic hybrid matrix. Z-scan measurement results showed a good compatibility between the dopant and the matrix, and also, an improved FOM was obtained as compared to the DR1/polymer films reported previously. To demonstrate the all-optical signal processing effect, a cw Nd:YAG laser emitting at 532 nm and a He-Ne laser emitting at 632.8 nm were used as pump and probe beams, respectively. DR1 acts as an initiator of the photo-induced transient holographic grating, which is attributed to the trans-cis-trans photoisomerization. Thus, a three inputs AND all-optical logic gate was achieved by using choppers with different frequencies. The detailed mechanism of operation is discussed. These results indicate that the DR1 doped germanium/Ormosil organic-inorganic hybrid film with an improved FOM has a great potential in all-optical devices around its main resonance.

  4. Results of the SNS front end commissioning at Berkeley Lab

    Energy Technology Data Exchange (ETDEWEB)

    Ratti, A.; Ayers, J.J.; Doolittle, L.; Greer, J.B.; Keller, R.; Lewis, S.; Lionberger, C.; Monroy, M.; Pruyn, J.; Staples, J.W.; Syversrude, D.; Thomae, R.; Virostek, S.; Aleksandrov, A.; Shea, T.; SNS Accelerator Physics Group; SNS Beam Diagnostics Collaboration

    2002-08-16

    The Front-End Systems (FES) for the Spallation Neutron Source (SNS) project comprise an rf-driven H{sup -} ion source, an electrostatic 2-lens LEBT, a 2.5 MeV RFQ, followed by a 14-quadrupole, 4-rebuncher MEBT including traveling-wave fast choppers. The nominal 2.5 MeV H{sup -} beam has a current of 38 mA at a repetition rate of 60 Hz and 1 ms pulse length, for a macro duty-factor of 6%, and is chopped at a rate of approximately 1 MHz with a mini duty-factor of 68%. The normalized rms beam emittance at the MEBT exit, matching the first tank of a 402.5 MHz Alvarez linac, is measured to be approximately 0.3 {pi} mm mrad. Diagnostic elements include wire scanners, BPMs, fast current monitors, a slit-harp emittance device and RFQ field monitoring probes. The results of the beam commissioning and the operation of the RFQ and diagnostic instrumentation are reported. The entire FES was shut down at LBNL at the end of May 2002 and will be recommissioned at ORNL prior to installation of the drift-tube linac.

  5. Results of the SNS front end commissioning at Berkeley Lab

    International Nuclear Information System (INIS)

    The Front-End Systems (FES) for the Spallation Neutron Source (SNS) project comprise an rf-driven H- ion source, an electrostatic 2-lens LEBT, a 2.5 MeV RFQ, followed by a 14-quadrupole, 4-rebuncher MEBT including traveling-wave fast choppers. The nominal 2.5 MeV H- beam has a current of 38 mA at a repetition rate of 60 Hz and 1 ms pulse length, for a macro duty-factor of 6%, and is chopped at a rate of approximately 1 MHz with a mini duty-factor of 68%. The normalized rms beam emittance at the MEBT exit, matching the first tank of a 402.5 MHz Alvarez linac, is measured to be approximately 0.3 π mm mrad. Diagnostic elements include wire scanners, BPMs, fast current monitors, a slit-harp emittance device and RFQ field monitoring probes. The results of the beam commissioning and the operation of the RFQ and diagnostic instrumentation are reported. The entire FES was shut down at LBNL at the end of May 2002 and will be recommissioned at ORNL prior to installation of the drift-tube linac

  6. Sofia Observatory Performance and Characterization

    Science.gov (United States)

    Temi, Pasquale; Miller, Walter; Dunham, Edward; McLean, Ian; Wolf, Jurgen; Becklin, Eric; Bida, Tom; Brewster, Rick; Casey, Sean; Collins, Peter; Jakob, Holger; Killebrew, Jana; Lampater, Ulrich; Mandushev, Georgi; Marcum, Pamela; Meyer, Allan; Pfueller, Enrico; Reinacher, Andreas; Roeser, Hans-Peter; Savage, Maureen; Teufel, Stefan; Wiedemann, Manuel

    2012-01-01

    The Stratospheric Observatory for Infrared Astronomy (SOFIA) has recently concluded a set of engineering flights for Observatory performance evaluation. These in-flight opportunities have been viewed as a first comprehensive assessment of the Observatory's performance and will be used to address the development activity that is planned for 2012, as well as to identify additional Observatory upgrades. A series of 8 SOFIA Characterization And Integration (SCAI) flights have been conducted from June to December 2011. The HIPO science instrument in conjunction with the DSI Super Fast Diagnostic Camera (SFDC) have been used to evaluate pointing stability, including the image motion due to rigid-body and flexible-body telescope modes as well as possible aero-optical image motion. We report on recent improvements in pointing stability by using an Active Mass Damper system installed on Telescope Assembly. Measurements and characterization of the shear layer and cavity seeing, as well as image quality evaluation as a function of wavelength have been performed using the HIPO+FLITECAM Science Instrument configuration (FLIPO). A number of additional tests and measurements have targeted basic Observatory capabilities and requirements including, but not limited to, pointing accuracy, chopper evaluation and imager sensitivity. SCAI activities included in-flight partial Science Instrument commissioning prior to the use of the instruments as measuring engines. This paper reports on the data collected during the SCAI flights and presents current SOFIA Observatory performance and characterization.

  7. X-ray diagnostic apparatus

    International Nuclear Information System (INIS)

    A falling load type X-ray diagnostic apparatus comprises a low voltage power source, AC-DC converting means connected to the low voltage power source so as to apply a rectified low DC voltage, chopping means connected to the AC-DC converting means and chopping said DC voltage into a low AC voltage, high voltage applying means for transforming said low AC voltage into a high AC voltage, said high AC voltage being applied as a tube voltage to an X-ray tube from which X-rays are irradiated toward an object to be examined, means for controlling a filament heating power of the X-ray tube, programming means for supplying a control signal to said filament heating control means so as to reduce the emission current of said X-ray tube during the irradiation, and chopper control means for controlling the chopping ratio of said chopping means by evaluating said rectified DC voltage with a preset tube voltage generated in said programming means, said programming means compensating said tube voltage by receiving said control signal in such a manner that said tube voltage is maintained substantially constant during the irradiation by varying said preset tube voltage so as to control the chopping ratio based upon the reduction of the filament heating power for the X-ray tube

  8. Focusing adaptive-optics for neutron spectroscopy at extreme conditions

    International Nuclear Information System (INIS)

    Neutron Spectroscopy employing extreme-conditions sample environments is nowadays a crucial tool for the understanding of fundamental scientific questions as well as for the investigation of materials and chemical-physical properties. For all these kinds of studies, an increased neutron flux over a small sample area is needed. The prototype of a focusing neutron guide component, developed and produced completely at the neutron source FRM II in Garching (Germany), has been installed at the time-of-flight (TOF) disc-chopper neutron spectrometer TOFTOF and came into routine-operation. The design is based on the compressed Archimedes' mirror concept for finite-size divergent sources. It represents a unique device combining the supermirror technology with Adaptive Optics, suitable for broad-bandwidth thermal-cold TOF neutron spectroscopy (here optimized for 1.4–10 Å). It is able to squeeze the beam cross section down to a square centimeter, with a more than doubled signal-to-background ratio, increased efficiency at high scattering angles, and improved symmetry of the elastic resolution function. We present a comparison between the simulated and measured beam cross sections, as well as the performance of the instrument within real experiments. This work intends to show the unprecedented opportunities achievable at already existing instruments, along with useful guidelines for the design and construction of next-generation neutron spectrometers

  9. Novel pulsed switched power supply for a fast field cycling NMR spectrometer.

    Science.gov (United States)

    Sousa, D M; Fernandes, P A L; Marques, G D; Ribeiro, A C; Sebastião, P J

    2004-01-01

    In this paper, we outline the operating principles of a pulsed switched power supply for a fast field-cycling nuclear magnetic resonance spectrometer. The power supply uses a variant of a four-quadrant chopper with a duty cycle that defines the average output current. With this topology only two semiconductors are necessary to drive hundreds of amperes with an output power of several kilowatts. The output current ripple has a well-defined shape that can be reduced to acceptable values by a careful design of the semiconductors' controlling circuits and drivers. A power supply prototype was tested with a home build air-core magnet operating with fields between 0 and 0.21 T. The system is computer controlled using pulse generator and data acquisition PC cards, and specific user-friendly home-developed software. A comparative proton relaxometry study in two well-known liquid crystal compounds 5CB and MBBA was performed to check the reproducibility of the T1 measurements. PMID:14698404

  10. Investigation of torque control using a variable slip induction generator

    Energy Technology Data Exchange (ETDEWEB)

    Bossanyi, E.A.; Gamble, C.R.

    1991-07-01

    An investigation of the possibilities of using a variable slip induction generator to control wind turbine transmission torque has been carried out. Such a generator consists of a wound rotor induction generator with its rotor winding connected to an external variable resistance circuit. By controlling the external resistance, the torque-slip characteristic of the generator can be modified, allowing efficient, low-slip operation below rated wind speed and compliant, high-slip operation above rated, where the additional losses are of no consequence but the resulting compliance allows a much reduced duty to be specified for the transmission and gearbox. A number of hardware options have been investigated for the variable resistance rotor circuit, the main options being either a rectifier and DC chopper or an AC regulator. Both of these options use semiconductor switching devices, for which the relative merits of thyristors, MOSFETs, GTOs and transistors have been investigated. A favoured scheme consisting of an AC regulator using GTOs has been provisionally selected. This choice uses some non-standard equipment but is expected to give negligible problems with harmonics. A comprehensive simulation model has been set up and used to investigate the behaviour of the whole system. (author).

  11. Accelerator mass spectrometry programme at BARC-TIFR pelletron accelerator. PD-1-2

    International Nuclear Information System (INIS)

    Accelerator mass spectrometry (AMS) is an ultra sensitive means of counting individual atoms having sufficiently long half-life and available in small amount. The 14 UD Pelletron Accelerator is an ideal machine to carry out AMS studies with heavy isotopes like 36Cl and 129I. Cosmogenic radioisotope 36Cl is widely being detected using AMS as it has got applications in ground water research, radioactive waste management, atmospheric 36Cl transport mechanism studies of Arctic Alpine ice core etc . The AMS programme at the 14 UD Mumbai Pelletron Accelerator has taken off with the installation of the state of the art Terminal Potential Stabilizer setup and operation of the accelerator in Generating Volt Meter (GVM) mode. Feasibility studies have been carried out for detection/identification of 14C from a charcoal sample and 3He in natural Helium. As the primary interest of AMS programme at Mumbai Pelletron Accelerator is related to the cosmogenic nuclei, 36Cl and 129I, a segmented gas detector developed for identification of 36Cl was tested for performance. Recently a beam chopper required for this measurement has also been developed

  12. Cascaded multilevel converter based superconducting magnetic energy storage system for frequency control

    International Nuclear Information System (INIS)

    The Super conducting magnetic energy storage (SMES), owing to high energy density and capacity, has been widely applied in different stages of power systems. One of these applications is the frequency control of the electric power systems. Frequency of a power system depends on the balance of produced and demanded energy in any instant of time. Subsequent to a sudden change in the system, which causes produced and demanded energy mismatch, frequency oscillates. According to standards, the permissible variation band of the frequency is very restricted. Larger swings of frequency may result in instability and undesirable trips. As a result, suitable frequency control mechanisms should be implemented in the system. SMES is well-suited for this application because of high energy density and fast response. SMES is attached to system by a power conditioning system (PCS) which include power electronic converters, mainly a dc–dc chopper and an inverter. This paper, studies the application of a cascaded H-bridge (CHB) multilevel converter for frequency control. As far as the authors' knowledge, such a study has not been done before. The design procedure of the converter is presented. Simulation results on a sample system are presented to verify the performance of the proposed PCS. - Highlights: • The cascaded multilevel power converter is applied for electrical power system frequency control. • The multilevel converter is supplied by superconducting magnetic energy storage. • Better quality of the output voltage is obtained. • Computer simulations in different scenarios verify the proposed conversion system

  13. Performance Analysis of Phase Controlled Unidirectional and Bidirectional AC Voltage Controllers

    Directory of Open Access Journals (Sweden)

    Abdul Sattar Larik

    2011-01-01

    Full Text Available AC voltage controllers are used to vary the output ac voltage from a fixed ac input source. They are also commonly called ac voltage regulators or ac choppers. The output voltage is either controlled by PAC (Phase Angle Control method or on-off control method. Due to various advantages of ac voltage controllers, such as high efficiency, simplicity, low cost and ability to control large amount of power they efficiently control the speed of ac motors, light dimming and industrial heating, etc. These converters are variable structure systems and generate harmonics during the operation which will affect the power quality when connected to system network. During the last couple of years, a number of new semiconductor devices and various power electronic converters has been introduced. Accordingly the subject of harmonics and its problems are of great concern to power industry and customers. In this research work, initially the simulation models of single phase unidirectional and bidirectional ac voltage controllers were developed by using MATLAB software. The harmonics of these models are investigated by simulation. In the end, the harmonics were also analyzed experimentally. The simulated as well as experimental results are presented.

  14. Measurement of double-differential neutron emission cross sections of 238U, 232Th and 12C for 18 MeV neutrons

    International Nuclear Information System (INIS)

    Double-differential neutron emission cross sections of 238U, 232Th and 12C have been measured for 18-MeV incident neutrons using the neutron time-of-flight technique and Tohoku University 4.5MV Dynamitron accelerator as a pulsed neutron generator. In the experiment, energy resolution of the spectrometer was improved by employing a newly developed post-acceleration beam-chopper and by adjustment of timing property of the neutron detector. Measurements were made at laboratory angles between 30- and 145- deg., and data were obtained for secondary neutrons between 0.8 and 18 MeV. In the data processing, a care was taken for the data correction for the effects of parasitic neutrons associated with primary neutrons; the correction proved to be of special importance in the present measurement. We compared the data obtained in the present experiment with the evaluated data, JENDL-3 and ENDF/B-IV (B-V for 12C), and discussed the origin of the discrepancies. The anisotropy observed for secondary neutrons from 238U and 232Th was found to be reproduced by Kalbach-Mann systematics on the assumption of isotropy of fission neutrons. The experimental results for 12C showed marked discrepancies concerning the scattering cross sections and neutron spectrum in the continuum region. (author)

  15. Beam Shape and Halo Monitor Study

    CERN Document Server

    Lallement, J B; Hori, M; CERN. Geneva. AB Department

    2006-01-01

    The Beam Shape and Halo Monitor, designed by Masaki Hori, is the main diagnostic tool for the 3 MeV test stand scheduled in 2008. This detector will be able to measure the transverse halo generated in the RFQ and the Chopper-line and to detect and measure the longitudinal halo composed of the incompletely chopped bunches. Its principle of functioning is the following: H- ions hit a carbon foil and generate secondary electrons with the same spatial distribution than the incoming beam and a current depending on an emission coefficient given by the carbon foil. These electrons are accelerated towards a phosphor screen by an electric field applied between accelerating grids. Once the electrons reach the phosphor screen, they generate light which is transmitted to a CCD camera via optic fibers [1]. It is expected to give a time resolution of 1-2ns and a spatial resolution of 1mm. The first test of the BSHM done with a Laser has shown a spatial resolution bigger than 1cm and the time resolution bigger than 2ns[2]. ...

  16. Pink-beam focusing with a one-dimensional compound refractive lens.

    Science.gov (United States)

    Dufresne, Eric M; Dunford, Robert W; Kanter, Elliot P; Gao, Yuan; Moon, Seoksu; Walko, Donald A; Zhang, Xusheng

    2016-09-01

    The performance of a cooled Be compound refractive lens (CRL) has been tested at the Advanced Photon Source (APS) to enable vertical focusing of the pink beam and permit the X-ray beam to spatially overlap with an 80 µm-high low-density plasma that simulates astrophysical environments. Focusing the fundamental harmonics of an insertion device white beam increases the APS power density; here, a power density as high as 500 W mm(-2) was calculated. A CRL is chromatic so it does not efficiently focus X-rays whose energies are above the fundamental. Only the fundamental of the undulator focuses at the experiment. A two-chopper system reduces the power density on the imaging system and lens by four orders of magnitude, enabling imaging of the focal plane without any X-ray filter. A method to measure such high power density as well as the performance of the lens in focusing the pink beam is reported. PMID:27577759

  17. The performance of the small-angle diffractometer, SAND at IPNS

    International Nuclear Information System (INIS)

    The time-of-flight small-angle diffractometer SAND has been serving the scientific user community since 1996. One notable feature of SAND is its capability to measure the scattered intensity in a wide Q (4πsinθ/λ, where 2θ is the scattering angle and λ is the wavelength of the neutrons) range of 0.0035 to 0.5 angstrom-1 in a single measurement. The optical alignment system makes it easy to set up the instrument and the sample. The cryogenically cooled MgO filter reduces the fast neutrons over two orders of magnitude, while still transmitting over 70% of the cold neutrons. A drum chopper running at 15 Hz suppresses the delayed neutron background. SAND has a variety of ancillary equipment to control the sample environment. In this paper we describe the features of the SAND instrument, compare its data on a few standard samples with those measured at well established centers in the world, and display two scientific examples which take advantage of measuring data in a wide Q-range in a single measurement. With a new set of tight collimators the Qmin can be lowered to 0.002 angstrom-1 and the presently installed high-angle bank of detectors will extend the Qmax to 2 angstrom-1

  18. Influence of moisture content, rate of loading and height regions on tensile strength of alfalfa stems

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available The objective of this study was to determine tensile strength of alfalfa stems as a function of moisture content, rate of loading and height region. Information on the physical and mechanical properties of alfalfa stem is important for the design of machines such as mowers, balers and choppers. The experiments were conducted at four moisture levels of 10, 20, 40, and 80% w.b., and three rates of loading of 5, 10 and 20 mm min-1. Each alfalfa stem was divided equally into three height regions, as upper, middle and lower. The tensile strength increased exponentially with decrease in the moisture content and towards the lower regions. The values of the tensile strength were within 9.24-26.35, 16.31-32.74, and 28.88-43.82MPa for the upper, middle and lower regions, respectively, at the different moisture contents studied and 10 mm min-1 rate of loading. The tensile strength increased linearly with increases in the rate of loading for all the regions. Its values varied between 9.24-12.27, 16.31-20.46, and 28.80-32.75 MPa for the upper, middle and lower regions, respectively, with increases in the rate of loading from 5 to 20 mm min-1, at the moisture content of 80% w.b.

  19. Stone tools associated with middle pleistocene fauna in the Toca da Esperanca, central region, Bahia state, Brazil

    International Nuclear Information System (INIS)

    Excavations (1) organized on a 12 m2 surface have exhumed quaternary deposits under a 50 cm carbonate crust (layer I). These deposits were composed of angular broken stones compacted into breccia (layer II), yellowish sand (layer III) and reddish clayey sand (leyer IV), containing fossilized bones. These bones belong to extinct quaternary species, in particular Equidae. The uranium-thorium method was used to date several bone samples found in situ which gave these faunas an age of about 300,000 years. Several quartzite stone tools as well as fragments of quartzite and quartz pebbles were discovered among the fossil bones. In particular, the fragment of a pebble, broken by violent percussion and a chopper were found. The raw materials, quartzite and quartz, naturally absent from the cave could only have been brought there by prehistoric man. The Toca da Esperanca is, therefore, the most ancient site known on the American continent which contains evidence of early man. It provides evidence of human presence from the Middle Pleistocene period, about 300,000 years ago, well before the Calico sites in California (about 200,000 years) and the Santa Raimundo Nonato sites (about 30,000 years). In the light of these new discoveries, it is possible to surmise that Homo Erectus came from Asia very early during the Middle Pleistocene, passing the Behring Strait, during one of the big recessions in ocean levels which took place in the cold quaternary periods. (author)

  20. Separation of cirrus cloud from clear surface from AVIRIS data using the 1.38 micron water vapor band

    Science.gov (United States)

    Gao, Bo-Cai; Goetz, Alexander F. H.

    1992-01-01

    Cirrus clouds play an important role in climate systems because of their large area coverage, persistence, and radiative effects. Thin cirrus clouds are difficult to detect in visible images and infrared images in the 10-12 micron atmospheric window region, particularly over land, because these clouds are partially transparent. Ackerman recently developed a method for detecting cirrus clouds using three narrow channels centered near 8, 11, and 12 microns, respectively, based on the analysis of IR emission spectra measured with a high spectral resolution interferometer. Barton also described a method for estimating cirrus cloud height and amount from measurements with two narrow channel radiometers of the Selective Chopper Radiometer on Nimbus 5. Both channels are located within the strong 2.7 micron water vapor band absorption region. One of the channels includes additional carbon dioxide absorption. A differential absorption technique with sets of empirical coefficients was used in the estimation of cirrus cloud heights and amounts. A technique using narrow channels in the strong 1.38 micron water vapor band absorption region for detecting cirrus clouds from spectral imaging data acquired by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) on 5 Dec. 1991 during the FIRE (The First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment) Phase 2 Field Experiment is described.