WorldWideScience

Sample records for generated magnetic signals

  1. Ocean circulation generated magnetic signals

    DEFF Research Database (Denmark)

    Manoj, C.; Kuvshinov, A.; Maus, S.

    2006-01-01

    Conducting ocean water, as it flows through the Earth's magnetic field, generates secondary electric and magnetic fields. An assessment of the ocean-generated magnetic fields and their detectability may be of importance for geomagnetism and oceanography. Motivated by the clear identification...... of ocean tidal signatures in the CHAMP magnetic field data we estimate the ocean magnetic signals of steady flow using a global 3-D EM numerical solution. The required velocity data are from the ECCO ocean circulation experiment and alternatively from the OCCAM model for higher resolution. We assume...... of the magnetic field, as compared to the ECCO simulation. Besides the expected signatures of the global circulation patterns, we find significant seasonal variability of ocean magnetic signals in the Indian and Western Pacific Oceans. Compared to seasonal variation, interannual variations produce weaker signals....

  2. Investigation on magnetoacoustic signal generation with magnetic induction and its application to electrical conductivity reconstruction

    International Nuclear Information System (INIS)

    Ma Qingyu; He Bin

    2007-01-01

    A theoretical study on the magnetoacoustic signal generation with magnetic induction and its applications to electrical conductivity reconstruction is conducted. An object with a concentric cylindrical geometry is located in a static magnetic field and a pulsed magnetic field. Driven by Lorentz force generated by the static magnetic field, the magnetically induced eddy current produces acoustic vibration and the propagated sound wave is received by a transducer around the object to reconstruct the corresponding electrical conductivity distribution of the object. A theory on the magnetoacoustic waveform generation for a circular symmetric model is provided as a forward problem. The explicit formulae and quantitative algorithm for the electrical conductivity reconstruction are then presented as an inverse problem. Computer simulations were conducted to test the proposed theory and assess the performance of the inverse algorithms for a multi-layer cylindrical model. The present simulation results confirm the validity of the proposed theory and suggest the feasibility of reconstructing electrical conductivity distribution based on the proposed theory on the magnetoacoustic signal generation with magnetic induction

  3. Extracting Ocean-Generated Tidal Magnetic Signals from Swarm Data Through Satellite Gradiometry

    Science.gov (United States)

    Sabaka, Terence J.; Tyler, Robert H.; Olsen, Nils

    2016-01-01

    Ocean-generated magnetic field models of the Principal Lunar, M2, and the Larger Lunar elliptic, N2, semidiurnal tidal constituents were estimated through a "Comprehensive Inversion" of the first 20.5 months of magnetic measurements from European Space Agency's (ESA) Swarm satellite constellation mission. While the constellation provides important north-south along-track gradiometry information, it is the unique low-spacecraft pair that allows for east-west cross-track gradiometry. This latter type is crucial in delivering an M2 estimate of similar quality with that derived from over 10 years of CHAMP satellite data but over a shorter interval, at higher altitude, and during more magnetically disturbed conditions. Recovered N2 contains nonoceanic signal but is highly correlated with theoretical models in regions of maximum oceanic amplitude. Thus, satellite magnetic gradiometry may eventually enable the monitoring of ocean electrodynamic properties at temporal resolutions of 1 to 2 years, which may have important implications for the inference of ocean temperature and salinity.

  4. Extracting Ocean-Generated Tidal Magnetic Signals from Swarm Data through Satellite Gradiometry

    DEFF Research Database (Denmark)

    Sabaka, Terence J.; Tyler, Robert H.; Olsen, Nils

    2016-01-01

    Ocean-generated magnetic field models of the Principal Lunar, M2, and the Larger Lunar elliptic, N2, semi-diurnal tidal constituents were estimated through a “Comprehensive Inversion" of the first 20.5 months of magnetic measurements from ESA's Swarm satellite constellation mission. While...

  5. Generation of earthquake signals

    International Nuclear Information System (INIS)

    Kjell, G.

    1994-01-01

    Seismic verification can be performed either as a full scale test on a shaker table or as numerical calculations. In both cases it is necessary to have an earthquake acceleration time history. This report describes generation of such time histories by filtering white noise. Analogue and digital filtering methods are compared. Different methods of predicting the response spectrum of a white noise signal filtered by a band-pass filter are discussed. Prediction of both the average response level and the statistical variation around this level are considered. Examples with both the IEEE 301 standard response spectrum and a ground spectrum suggested for Swedish nuclear power stations are included in the report

  6. Review of Micro Magnetic Generator

    OpenAIRE

    Lin DU; Gengchen SHI; Jingjing ZHAO

    2014-01-01

    This paper discusses the research progress of micro magnetic generator systems. Micro magnetic generator systems convert energy from the environment to electric energy with advantages as high reliability, high power density, long life time and can be applied to extreme environment. This paper summarizes methods for improving generator performance of micro magnetic generator, including rotational magnetic generator, vibrational magnetic generator and hybrid magnetic generator, analyzes and com...

  7. Digitally programmable signal generator

    International Nuclear Information System (INIS)

    Priatko, G.J.; Kaskey, J.A.

    1988-01-01

    A digitally programmable signal generator (DPSG) includes a first memory from which data is written into a second memory formed of n banks. Each bank includes four memories and a multiplexer, the banks being read once during each time frame, the read-out bits being multiplexed and fed out serially in synchronism with a plurality of clock pulses occuring during a time frame. The resulting serial bit streams may be fed in parallel to a digital-to-analog converter. The DPSG can be used in applications such as Atomic Vapor Laser Isotope Separation (AVLIS) to create an optimal match between the process laser's spectral profile and that of the vaporized material, optical telecommunications, non-optical telecommunication in the microwave and radio spectrum, radar, electronic countermeasures, high speed computer interconnects, local area networks, high definition video transport and the multiplexing of large quantities of slow digital memory into high speed data streams. This invention extends the operation of DPSGs into the GHz range. (author)

  8. Review of Micro Magnetic Generator

    Directory of Open Access Journals (Sweden)

    Lin DU

    2014-08-01

    Full Text Available This paper discusses the research progress of micro magnetic generator systems. Micro magnetic generator systems convert energy from the environment to electric energy with advantages as high reliability, high power density, long life time and can be applied to extreme environment. This paper summarizes methods for improving generator performance of micro magnetic generator, including rotational magnetic generator, vibrational magnetic generator and hybrid magnetic generator, analyzes and compares their design and performance, and concludes key technologies and ongoing challenges for further progress. The paper is instructive and meaningful to for research work of related field.

  9. Generation of nuclear magnetic resonance images

    International Nuclear Information System (INIS)

    Beckmann, N.X.

    1986-01-01

    Two generation techniques of nuclear magnetic resonance images, the retro-projection and the direct transformation method are studied these techniques are based on the acquisition of NMR signals which phases and frequency components are codified in space by application of magnetic field gradients. The construction of magnet coils is discussed, in particular a suitable magnet geometry with polar pieces and air gap. The obtention of image contrast by T1 and T2 relaxation times reconstructed from generated signals using sequences such as spin-echo, inversion-recovery and stimulated echo, is discussed. The mathematical formalism of matrix solution for Bloch equations is also presented. (M.C.K.)

  10. Signal generation in gas detectors

    International Nuclear Information System (INIS)

    Stillman, A.

    1993-01-01

    This tutorial describes the generation of electrical signals in gas detectors. Ionization of the gas by the passage of charged particles generates these signals. Starting with the Bethe-Bloch equation, the treatment is a general introduction to the production of ion-pairs in gas devices. I continue with the characterization of the ionization as an electrical signal, and calculate the signal current in a simple example. Another example demonstrates the effect of space charge on the design of a detector. The AGS Booster ionization profile monitor is a model for this calculation

  11. Satellite tidal magnetic signals constrain oceanic lithosphere-asthenosphere boundary

    DEFF Research Database (Denmark)

    Grayver, Alexander V.; Schnepf, Neesha R.; Kuvshinov, Alexey V.

    2016-01-01

    The tidal flow of electrically conductive oceans through the geomagnetic field results in the generation ofsecondary magnetic signals, which provide information on the subsurface structure. Data from the new generation of satellites were shown to contain magnetic signals due to tidal flow; howeve...

  12. Satellite Tidal Magnetic Signals Constrain Oceanic Lithosphere-Asthenosphere Boundary Earth Tomography with Tidal Magnetic Signals

    Science.gov (United States)

    Grayver, Alexander V.; Schnepf, Neesha R.; Kuvshinov, Alexey V.; Sabaka, Terence J.; Chandrasekharan, Manoj; Olsen, Niles

    2016-01-01

    The tidal flow of electrically conductive oceans through the geomagnetic field results in the generation of secondary magnetic signals, which provide information on the subsurface structure. Data from the new generation of satellites were shown to contain magnetic signals due to tidal flow; however, there are no reports that these signals have been used to infer subsurface structure. Here we use satellite-detected tidal magnetic fields to image the global electrical structure of the oceanic lithosphere and upper mantle down to a depth of about 250 km. The model derived from more than 12 years of satellite data reveals an Approximately 72 km thick upper resistive layer followed by a sharp increase in electrical conductivity likely associated with the lithosphere-asthenosphere boundary, which separates colder rigid oceanic plates from the ductile and hotter asthenosphere.

  13. Generator of combined logical signals

    International Nuclear Information System (INIS)

    Laviron, Andre; Berard, Claude.

    1982-01-01

    The invention concerns a generator of combined logical signals to form combinations of two outputs at logical level 1 and N-2 outputs at logical level 0, among N generator outputs. This generator is characterized in that it includes a set of N means for storing combinations. Means enable the N storage means to be loaded with the logical levels corresponding to a pre-set starting combination, to control the operations for shifting the contents of the storage means and to control, by transfer facilities, the transfers of contents between these storage means. Controls enable the storage means to be actuated in order to obtain combinations of logical levels 1 and 0. The generation of combinations can be stopped after another pre-set combination. Application is for testing of safety circuits for nuclear power stations [fr

  14. Distributed generation induction and permanent magnet generators

    CERN Document Server

    Lai, L

    2007-01-01

    Distributed power generation is a technology that could help to enable efficient, renewable energy production both in the developed and developing world. It includes all use of small electric power generators, whether located on the utility system, at the site of a utility customer, or at an isolated site not connected to the power grid. Induction generators (IGs) are the cheapest and most commonly used technology, compatible with renewable energy resources. Permanent magnet (PM) generators have traditionally been avoided due to high fabrication costs; however, compared with IGs they are more reliable and productive. Distributed Generation thoroughly examines the principles, possibilities and limitations of creating energy with both IGs and PM generators. It takes an electrical engineering approach in the analysis and testing of these generators, and includes diagrams and extensive case study examples o better demonstrate how the integration of energy sources can be accomplished. The book also provides the ...

  15. Coding and signal processing for magnetic recording systems

    CERN Document Server

    Vasic, Bane

    2004-01-01

    RECORDING SYSTEMSA BriefHistory of Magnetic Storage, Dean PalmerPhysics of Longitudinal and Perpendicular Recording, Hong Zhou, Tom Roscamp, Roy Gustafson, Eric Boernern, and Roy ChantrellThe Physics of Optical Recording, William A. Challener and Terry W. McDanielHead Design Techniques for Recording Devices, Robert E. RottmayerCOMMUNICATION AND INFORMATION THEORY OF MAGNETIC RECORDING CHANNELSModeling the Recording Channel, Jaekyun MoonSignal and Noise Generation for Magnetic Recording Channel Simulations, Xueshi Yang and Erozan M. KurtasStatistical Analysis of Digital Signals and Systems, Dra

  16. Generation of magnetic fields for accelerators with permanent magnets

    International Nuclear Information System (INIS)

    Meinander, T.

    1994-01-01

    Commercially available permanent magnet materials and their properties are reviewed. Advantages and disadvantages of using permanent magnets as compared to electromagnets for the generation of specific magnetic fields are discussed. Basic permanent magnet configurations in multipole magnets and insertion devices are presented. (orig.)

  17. Wakefield generation in magnetized plasmas

    International Nuclear Information System (INIS)

    Holkundkar, Amol; Brodin, Gert; Marklund, Mattias

    2011-01-01

    We consider wakefield generation in plasmas by electromagnetic pulses propagating perpendicular to a strong magnetic field, in the regime where the electron cyclotron frequency is equal to or larger than the plasma frequency. Particle-in-cell simulations reveal that for moderate magnetic field strengths previous results are reproduced, and the wakefield wave number spectrum has a clear peak at the inverse skin depth. However, when the cyclotron frequency is significantly larger than the plasma frequency, the wakefield spectrum becomes broadband, and simultaneously the loss rate of the driving pulse is much enhanced. A set of equations for the scalar and vector potentials reproducing these results are derived, using only the assumption of a weakly nonlinear interaction.

  18. Permanent magnet based dipole magnets for next generation light sources

    Directory of Open Access Journals (Sweden)

    Takahiro Watanabe

    2017-07-01

    Full Text Available We have developed permanent magnet based dipole magnets for the next generation light sources. Permanent magnets are advantageous over electromagnets in that they consume less power, are physically more compact, and there is a less risk of power supply failure. However, experience with electromagnets and permanent magnets in the field of accelerators shows that there are still challenges to replacing main magnets of accelerators for light sources with permanent magnets. These include the adjustability of the magnetic field, the temperature dependence of permanent magnets, and the issue of demagnetization. In this paper, we present a design for magnets for future light sources, supported by experimental and numerical results.

  19. Magnetic resonance signal moment determination using the Earth's magnetic field

    KAUST Repository

    Fridjonsson, Einar Orn; Creber, Sarah A.; Vrouwenvelder, Johannes S.; Johns, Michael L.

    2015-01-01

    We demonstrate a method to manipulate magnetic resonance data such that the moments of the signal spatial distribution are readily accessible. Usually, magnetic resonance imaging relies on data acquired in so-called k-space which is subsequently Fourier transformed to render an image. Here, via analysis of the complex signal in the vicinity of the centre of k-space we are able to access the first three moments of the signal spatial distribution, ultimately in multiple directions. This is demonstrated for biofouling of a reverse osmosis (RO) membrane module, rendering unique information and an early warning of the onset of fouling. The analysis is particularly applicable for the use of mobile magnetic resonance spectrometers; here we demonstrate it using an Earth's magnetic field system.

  20. Magnetic resonance signal moment determination using the Earth's magnetic field

    KAUST Repository

    Fridjonsson, Einar Orn

    2015-03-01

    We demonstrate a method to manipulate magnetic resonance data such that the moments of the signal spatial distribution are readily accessible. Usually, magnetic resonance imaging relies on data acquired in so-called k-space which is subsequently Fourier transformed to render an image. Here, via analysis of the complex signal in the vicinity of the centre of k-space we are able to access the first three moments of the signal spatial distribution, ultimately in multiple directions. This is demonstrated for biofouling of a reverse osmosis (RO) membrane module, rendering unique information and an early warning of the onset of fouling. The analysis is particularly applicable for the use of mobile magnetic resonance spectrometers; here we demonstrate it using an Earth\\'s magnetic field system.

  1. Self-generation of magnetic fields

    International Nuclear Information System (INIS)

    Dolan, T.J.

    2000-01-01

    The stars generate self-magnetic fields on large spatial scales and long time scales,and laser-produced plasmas generate intense self-magnetic fields on very short spatial and time scales. Two questions are posed : (1) Could a self-magnetic field be generated in a laboratory plasma with intermediate spatial and time scales? (2) If a self-magnetic field were generated,would it evolve towards a minimum energy state? If the answers turned out to be affirmative,then self-magnetic fields could possibly have interesting applications

  2. Magnetic field generation device for magnetohydrodynamic electric power generation

    International Nuclear Information System (INIS)

    Kuriyama, Yoshihiko.

    1993-01-01

    An existent magnetic field generation device for magnetohydrodynamic electric power generation comprises at least a pair of permanent magnets disposed to an inner circumferential surface of a yoke having such a cross sectional area that two pairs of parallel sides are present, in which different magnetic poles are opposed while interposing a flow channel for a conductive fluid therebetween. Then, first permanent magnets which generate main magnetic fields are disposed each at a gap sandwiching a plane surface including a center axis of a flow channel for the conductive fluid. Second permanent magnets which generate auxiliary magnetic fields are disposed to an inner circumferential surface of a yoke intersecting the yoke to which the first permanent magnets are disposed. The magnetic poles on the side of the flow channel for the second permanent magnets have identical polarity with that of the magnetic poles of the adjacent first permanent magnets. As a result, a magnetic flux density in the flow channel for the conductive fluid can be kept homogeneous and at a high level from a position of the axial line of the flow channel to the outer circumference, thereby enabling to remarkably improve a power generation efficiency. (N.H.)

  3. Cosmic microwave background polarization signals from tangled magnetic fields.

    Science.gov (United States)

    Seshadri, T R; Subramanian, K

    2001-09-03

    Tangled, primordial cosmic magnetic fields create small rotational velocity perturbations on the last scattering surface of the cosmic microwave background radiation. For fields which redshift to a present value of B0 = 3 x 10(-9) G, these vector modes are shown to generate polarization anisotropies of order 0.1-4 microK on small angular scales (500signals result for n = 2 spectra. Unlike inflation generated, scalar modes, these signals are dominated by the odd parity, B-type polarization, which could help in their detection.

  4. Generating the optimal magnetic field for magnetic refrigeration

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Insinga, Andrea Roberto; Smith, Anders

    2016-01-01

    In a magnetic refrigeration device the magnet is the single most expensive component, and therefore it is crucially important to ensure that an effective magnetic field as possible is generated using the least amount of permanent magnets. Here we present a method for calculating the optimal...... remanence distribution for any desired magnetic field. The method is based on the reciprocity theorem, which through the use of virtual magnets can be used to calculate the optimal remanence distribution. Furthermore, we present a method for segmenting a given magnet design that always results...... in the optimal segmentation, for any number of segments specified. These two methods are used to determine the optimal magnet design of a 12-piece, two-pole concentric cylindrical magnet for use in a continuously rotating magnetic refrigeration device....

  5. Nuclear signals in magnetically ordered media

    International Nuclear Information System (INIS)

    Ignatchenko, V.A.; Tsifrinovich, V.I.

    1993-01-01

    The book contains a review of theoretical and experimental investigations in the field of nuclear magnetism in magnetically ordered media. The semiclassical theory of nuclear spins motion is developed that takes into consideration three main features of magnetically ordered media: Suhl-Nakamura interaction, quadrupole interaction and microscopic inhomogeneity of nuclear frequencies. The detailed classification of nuclear spin echo signals is given for standard conditions of experiments, when the Suhl-Nakamura interaction is small in comparison with the NMR line width. The extremal states of the electron - nuclear magnetic system are described in detail: the coexistence of NMR and FMR, nuclear ferromagnetism and NMR at fast remagnetization of a ferromagnet. 157 refs., 20 figs

  6. Strong and superstrong pulsed magnetic fields generation

    CERN Document Server

    Shneerson, German A; Krivosheev, Sergey I

    2014-01-01

    Strong pulsed magnetic fields are important for several fields in physics and engineering, such as power generation and accelerator facilities. Basic aspects of the generation of strong and superstrong pulsed magnetic fields technique are given, including the physics and hydrodynamics of the conductors interacting with the field as well as an account of the significant progress in generation of strong magnetic fields using the magnetic accumulation technique. Results of computer simulations as well as a survey of available field technology are completing the volume.

  7. Magnetic flux generator for balanced membrane loudspeaker

    DEFF Research Database (Denmark)

    Rehder, Jörg; Rombach, Pirmin; Hansen, Ole

    2002-01-01

    This paper reports the development of a magnetic flux generator with an application in a hearing aid loudspeaker produced in microsystem technology (MST). The technology plans for two different designs for the magnetic flux generator utilizing a softmagnetic substrate or electroplated Ni...

  8. A linear magnetic motor and generator

    Science.gov (United States)

    Studer, P. A.

    1980-01-01

    In linear magnetic motor and generator suitable for remote and hostile environments, magnetic forces drive reciprocating shaft along its axis. Actuator shaft is located in center of cylindrical body and may be supported by either contacting or noncontacting bearings. When device operates as bidirectional motor, drive coil selectively adds and subtracts magnetic flux to and from flux paths, producing forces that drive actuator along axis. When actuator is driven by external reciprocating engine, device becomes ac generator.

  9. Test signal generation for analog circuits

    Directory of Open Access Journals (Sweden)

    B. Burdiek

    2003-01-01

    Full Text Available In this paper a new test signal generation approach for general analog circuits based on the variational calculus and modern control theory methods is presented. The computed transient test signals also called test stimuli are optimal with respect to the detection of a given fault set by means of a predefined merit functional representing a fault detection criterion. The test signal generation problem of finding optimal test stimuli detecting all faults form the fault set is formulated as an optimal control problem. The solution of the optimal control problem representing the test stimuli is computed using an optimization procedure. The optimization procedure is based on the necessary conditions for optimality like the maximum principle of Pontryagin and adjoint circuit equations.

  10. Depth of origin of ocean-circulation-induced magnetic signals

    Science.gov (United States)

    Irrgang, Christopher; Saynisch-Wagner, Jan; Thomas, Maik

    2018-01-01

    As the world ocean moves through the ambient geomagnetic core field, electric currents are generated in the entire ocean basin. These oceanic electric currents induce weak magnetic signals that are principally observable outside of the ocean and allow inferences about large-scale oceanic transports of water, heat, and salinity. The ocean-induced magnetic field is an integral quantity and, to first order, it is proportional to depth-integrated and conductivity-weighted ocean currents. However, the specific contribution of oceanic transports at different depths to the motional induction process remains unclear and is examined in this study. We show that large-scale motional induction due to the general ocean circulation is dominantly generated by ocean currents in the upper 2000 m of the ocean basin. In particular, our findings allow relating regional patterns of the oceanic magnetic field to corresponding oceanic transports at different depths. Ocean currents below 3000 m, in contrast, only contribute a small fraction to the ocean-induced magnetic signal strength with values up to 0.2 nT at sea surface and less than 0.1 nT at the Swarm satellite altitude. Thereby, potential satellite observations of ocean-circulation-induced magnetic signals are found to be likely insensitive to deep ocean currents. Furthermore, it is shown that annual temporal variations of the ocean-induced magnetic field in the region of the Antarctic Circumpolar Current contain information about sub-surface ocean currents below 1000 m with intra-annual periods. Specifically, ocean currents with sub-monthly periods dominate the annual temporal variability of the ocean-induced magnetic field.

  11. Linear magnetic motor/generator. [to generate electric energy using magnetic flux for spacecraft power supply

    Science.gov (United States)

    Studer, P. A. (Inventor)

    1982-01-01

    A linear magnetic motor/generator is disclosed which uses magnetic flux to provide mechanical motion or electrical energy. The linear magnetic motor/generator includes an axially movable actuator mechanism. A permament magnet mechanism defines a first magnetic flux path which passes through a first end portion of the actuator mechanism. Another permament magnet mechanism defines a second magnetic flux path which passes through a second end portion of the actuator mechanism. A drive coil defines a third magnetic flux path passing through a third central portion of the actuator mechanism. A drive coil selectively adds magnetic flux to and subtracts magnetic flux from magnetic flux flowing in the first and second magnetic flux path.

  12. Magnet Free Generators - 3rd Generation Wind Turbine Generators

    DEFF Research Database (Denmark)

    Jensen, Bogi Bech; Mijatovic, Nenad; Henriksen, Matthew Lee

    2013-01-01

    This paper presents an introduction to superconducting wind turbine generators, which are often referred to as 3rd generation wind turbine generators. Advantages and challenges of superconducting generators are presented with particular focus on possible weight and efficiency improvements. A comp...

  13. Miniaturized Air-Driven Planar Magnetic Generators

    Directory of Open Access Journals (Sweden)

    Jingjing Zhao

    2015-10-01

    Full Text Available This paper presents the design, analysis, fabrication and testing of two miniaturized air-driven planar magnetic generators. In order to reduce the magnetic resistance torque, Generator 1 establishes a static magnetic field by consisting a multilayer planar coil as the stator and two multi-pole permanent-magnet (PM rotors on both sides of the coil. To further decrease the starting torque and save more space, Generator 2 adopts the multilayer planar coil as the rotor and the multi-pole PMs as the stator, eliminating the casing without compromising the magnetic structure or output performance. The prototypes were tested gathering energy from wind which can work at a low wind speed of 1~2 m/s. Prototype of Generator 1 is with a volume of 2.61 cm3 and its normalized voltage reaches 485 mV/krpm. Prototype of Generator 2 has a volume of 0.92 cm3 and a normalized voltage as high as 538 mV/krpm. Additionally, output voltage can be estimated at better than 96% accuracy by the theoretical model developed in this paper. The two micro generators are capable of producing substantial electricity with little volume to serve as compact power conversion devices.

  14. Signal loss in magnetic resonance imaging caused by intraoral anchored dental magnetic materials

    International Nuclear Information System (INIS)

    Blankenstein, F.H.; Naumann, M.; Truong, B.; Thomas, A.; Schroeder, R.J.

    2006-01-01

    Purpose: to measure the maximum extent of the signal loss areas in the center of the susceptibility artifacts generated by ferromagnetic dental magnet attachments using three different sequences in the 1.5 and 3.0 Tesla MRI. Materials and methods: five different pieces of standard dental magnet attachments with volumes of 6.5 to 31.4 mm 3 were used: a NdFeB magnet with an open magnetic field, a NdFeB magnet with a closed magnetic field, a SmCo magnet with an open magnetic field, a stainless steel keeper (AUM-20) and a PdCo piece. The attachments were placed between two cylindrical phantoms and examined in 1.5 and 3.0 Tesla MRI using gradient echo and T1- and T2-weighted spin echoes. We measured the maximum extent of the generated signal loss areas parallel and perpendicular to the direction of B O . Results: in gradient echoes the artifacts were substantially larger and symmetrically adjusted around the object. The areas with total signal loss were mushroom-like with a maximum extent of 7.4 to 9.7 cm parallel to the direction of B O and 6.7 to 7.4 cm perpendicular to B O . In spin echoes the signal loss areas were obviously smaller, but not centered. The maximum values ranged between 4.9 and 7.2 cm (parallel B O ) and 3.6 and 7.0 cm (perpendicular B O ). The different ferromagnetic attachments had no clinically relevant influence on the signal loss neither in 1.5 T nor 3.0 T MRI. Conclusions: ferromagnetic materials used in dentistry are not intraorally standardized. To ensure, that the area of interest is not affected by the described artifacts, the maximum extent of the signal loss area should be assumed: a radius of up to 7 cm in 1.5 and 3.0 T MRI by T1 and T2 sequences, and a radius of up to 10 cm in T2* sequences. To decide whether magnet attachments have to be removed before MR imaging, physicians should consider both the intact retention of the keepers and the safety distance between the ferromagnetic objects and the area of interest. (orig.)

  15. X-ray image signal generator

    International Nuclear Information System (INIS)

    Dalton, B.L.; Lill, B.H.

    1981-01-01

    This patent claim on behalf on EMI Ltd. relates to a flat plate X-ray detector which uses a plate detector exhibiting so-called permanent induced electric polarization in response to a pattern of radiation emergent from a patient to generate a polarization pattern which is scanned by means of a laser to cause discharge of the polarization through the plate and so generate electric signals representative of the X-ray image of the patient. In addition a second laser operating at a different wavelength e.g. infra-red, also scans or floods the plate detector to move 'dark polarisation'. The plate detector may be a phosphor screen or a phosphor screen in combination with a scintillator. (author)

  16. Second harmonic generation in a molecular magnetic chain

    Science.gov (United States)

    Cavigli, L.; Sessoli, R.; Gurioli, M.; Bogani, L.

    2006-05-01

    A setup for the determination of all the components of the second harmonic generation tensor in molecular materials is presented. It allows overcoming depletion problems, which one can expect to be common in molecular systems. A preliminary characterization of the nonlinear properties of the single chain magnet CoPhOMe is carried out. We observe a high second harmonic signal, comparable to that of urea, and show that the bulk contributions are dominant over the surface ones.

  17. A Low-cost Multi-channel Analogue Signal Generator

    CERN Document Server

    Müller, F; The ATLAS collaboration; Shen, W; Stamen, R

    2009-01-01

    A scalable multi-channel analogue signal generator is presented. It uses a commercial low-cost graphics card with multiple outputs in a standard PC as signal source. Each color signal serves as independent channel to generate an analogue signal. A custom-built external PCB was developed to adjust the graphics card output voltage levels for a specific task, which needed differential signals. The system furthermore comprises a software package to program the signal shape. The signal generator was successfully used as independent test bed for the ATLAS Level-1 Trigger Pre-Processor, providing up to 16 analogue signals.

  18. Analog Filter Design Rules for Multilevel Polybinary Signaling Generation

    DEFF Research Database (Denmark)

    Vegas Olmos, Juan José; Cavallero, Francisco javier Vaquero; Tafur Monroy, Idelfonso

    2014-01-01

    Polybinary signaling has gained attention lately due to its generation simplicity and reduced spectral usage. This paper presents a study on the requirements for analog filters for the generation of multilevel polybinary signals with three to nine levels.......Polybinary signaling has gained attention lately due to its generation simplicity and reduced spectral usage. This paper presents a study on the requirements for analog filters for the generation of multilevel polybinary signals with three to nine levels....

  19. Generation of intense transient magnetic fields

    International Nuclear Information System (INIS)

    Benjamin, R.F.

    1983-01-01

    In a laser system, the return current of a laser generated plasma is conducted near a target to subject that target to a magnetic field. The target may be either a small non-fusion object for testing under the magnetic field or a laser-fusion pellet. In the laser-fusion embodiment, the laser-fusion pellet is irradiated during the return current flow and the intense transient magnetic field is used to control the hot electrons thereof to hinder them from striking and heating the core of the irradiated laser-fusion pellet. An emitter, e.g. a microballoon of glass, metal or plastics, is subjected to a laser pulse to generate the plasma from which the return current flows into a wire cage or a coil and then to earth. (author)

  20. Optical magnetic flux generation in superconductor

    Indian Academy of Sciences (India)

    Keywords. Ultrafast phenomena; femtosecond laser; optical magnetic flux generation. PACS Nos 85.25.Oj; 74.25.-q; 42.65.Re. 1. Introduction. Excitation and observation of ultrafast phenomena in solid states are of essential interest in the field of condensed matter physics. Recent femtosecond (fs) laser technology is now.

  1. 21 CFR 882.1430 - Electroencephalograph test signal generator.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Electroencephalograph test signal generator. 882.1430 Section 882.1430 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Electroencephalograph test signal generator. (a) Identification. An electroencephalograph test signal generator is a...

  2. Pulsed magnetic field generation suited for low-field unilateral nuclear magnetic resonance systems

    Science.gov (United States)

    Gaunkar, Neelam Prabhu; Selvaraj, Jayaprakash; Theh, Wei-Shen; Weber, Robert; Mina, Mani

    2018-05-01

    Pulsed magnetic fields can be used to provide instantaneous localized magnetic field variations. In presence of static fields, pulsed field variations are often used to apply torques and in-effect to measure behavior of magnetic moments in different states. In this work, the design and experimental performance of a pulsed magnetic field generator suited for low static field nuclear magnetic resonance (NMR) applications is presented. One of the challenges of low bias field NMR measurements is low signal to noise ratio due to the comparable nature of the bias field and the pulsed field. Therefore, a circuit is designed to apply pulsed currents through an inductive load, leading to generation of pulsed magnetic fields which can temporarily overpower the effect of the bias field on magnetic moments. The designed circuit will be tuned to operate at the precession frequency of 1H (protons) placed in a bias field produced by permanent magnets. The designed circuit parameters may be tuned to operate under different bias conditions. Therefore, low field NMR measurements can be performed for different bias fields. Circuit simulations were used to determine design parameters, corresponding experimental measurements will be presented in this work.

  3. A Low-cost Multi-channel Analogue Signal Generator

    CERN Document Server

    Muller, F; Shen, W; Stamen, R

    2009-01-01

    A scalable multi-channel analogue signal generator is presented. It uses a commercial low-cost graphics card with multiple outputs in a standard PC as signal source. Each color signal serves as independent channel to generate an analogue signal. A custom-built external PCB was developed to adjust the graphics card output voltage levels for a specific task, which needed differential signals. The system furthermore comprises a software package to program the signal shape. The implementation of the signal generator is presented as well as an application where it was successfully utilized.

  4. On-chip signal amplification of magnetic bead-based immunoassay by aviating magnetic bead chains.

    Science.gov (United States)

    Jalal, Uddin M; Jin, Gyeong Jun; Eom, Kyu Shik; Kim, Min Ho; Shim, Joon S

    2017-11-06

    In this work, a Lab-on-a-Chip (LOC) platform is used to electromagnetically actuate magnetic bead chains for an enhanced immunoassay. Custom-made electromagnets generate a magnetic field to form, rotate, lift and lower the magnetic bead chains (MBCs). The cost-effective, disposable LOC platform was made with a polymer substrate and an on-chip electrochemical sensor patterned via the screen-printing process. The movement of the MBCs is controlled to improve the electrochemical signal up to 230% when detecting beta-type human chorionic gonadotropin (β-hCG). Thus, the proposed on-chip MBC-based immunoassay is applicable for rapid, qualitative electrochemical point-of-care (POC) analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Generate the scale-free brain music from BOLD signals.

    Science.gov (United States)

    Lu, Jing; Guo, Sijia; Chen, Mingming; Wang, Weixia; Yang, Hua; Guo, Daqing; Yao, Dezhong

    2018-01-01

    Many methods have been developed to translate a human electroencephalogram (EEG) into music. In addition to EEG, functional magnetic resonance imaging (fMRI) is another method used to study the brain and can reflect physiological processes. In 2012, we established a method to use simultaneously recorded fMRI and EEG signals to produce EEG-fMRI music, which represents a step toward scale-free brain music. In this study, we used a neural mass model, the Jansen-Rit model, to simulate activity in several cortical brain regions. The interactions between different brain regions were represented by the average normalized diffusion tensor imaging (DTI) structural connectivity with a coupling coefficient that modulated the coupling strength. Seventy-eight brain regions were adopted from the Automated Anatomical Labeling (AAL) template. Furthermore, we used the Balloon-Windkessel hemodynamic model to transform neural activity into a blood-oxygen-level dependent (BOLD) signal. Because the fMRI BOLD signal changes slowly, we used a sampling rate of 250 Hz to produce the temporal series for music generation. Then, the BOLD music was generated for each region using these simulated BOLD signals. Because the BOLD signal is scale free, these music pieces were also scale free, which is similar to classic music. Here, to simulate the case of an epileptic patient, we changed the parameter that determined the amplitude of the excitatory postsynaptic potential (EPSP) in the neural mass model. Finally, we obtained BOLD music for healthy and epileptic patients. The differences in levels of arousal between the 2 pieces of music may provide a potential tool for discriminating the different populations if the differences can be confirmed by more real data. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.

  6. SEED BANKS FOR MAGNETIC FLUX COMPRESSION GENERATORS

    Energy Technology Data Exchange (ETDEWEB)

    Fulkerson, E S

    2008-05-14

    In recent years the Lawrence Livermore National Laboratory (LLNL) has been conducting experiments that require pulsed high currents to be delivered into inductive loads. The loads fall into two categories (1) pulsed high field magnets and (2) the input stage of Magnetic Flux Compression Generators (MFCG). Three capacitor banks of increasing energy storage and controls sophistication have been designed and constructed to drive these loads. One bank was developed for the magnet driving application (20kV {approx} 30kJ maximum stored energy.) Two banks where constructed as MFCG seed banks (12kV {approx} 43kJ and 26kV {approx} 450kJ). This paper will describe the design of each bank including switching, controls, circuit protection and safety.

  7. SUNQUAKE GENERATION BY CORONAL MAGNETIC RESTRUCTURING

    Energy Technology Data Exchange (ETDEWEB)

    Russell, A. J. B.; Mooney, M. K. [School of Science and Engineering, University of Dundee, Dundee DD1 4HN (United Kingdom); Leake, J. E. [Naval Research Laboratory, Washington, DC 20375 (United States); Hudson, H. S. [Space Sciences Lab, University of California Berkeley, Berkeley, CA 94720 (United States)

    2016-11-01

    Sunquakes are the surface signatures of acoustic waves in the Sun’s interior that are produced by some but not all flares and coronal mass ejections (CMEs). This paper explores a mechanism for sunquake generation by the changes in magnetic field that occur during flares and CMEs, using MHD simulations with a semiempirical FAL-C atmosphere to demonstrate the generation of acoustic waves in the interior in response to changing magnetic tilt in the corona. We find that Alfvén–sound resonance combined with the ponderomotive force produces acoustic waves in the interior with sufficient energy to match sunquake observations when the magnetic field angle changes of the order of 10° in a region where the coronal field strength is a few hundred gauss or more. The most energetic sunquakes are produced when the coronal field is strong, while the variation of magnetic field strength with height and the timescale of the change in tilt are of secondary importance.

  8. SUNQUAKE GENERATION BY CORONAL MAGNETIC RESTRUCTURING

    International Nuclear Information System (INIS)

    Russell, A. J. B.; Mooney, M. K.; Leake, J. E.; Hudson, H. S.

    2016-01-01

    Sunquakes are the surface signatures of acoustic waves in the Sun’s interior that are produced by some but not all flares and coronal mass ejections (CMEs). This paper explores a mechanism for sunquake generation by the changes in magnetic field that occur during flares and CMEs, using MHD simulations with a semiempirical FAL-C atmosphere to demonstrate the generation of acoustic waves in the interior in response to changing magnetic tilt in the corona. We find that Alfvén–sound resonance combined with the ponderomotive force produces acoustic waves in the interior with sufficient energy to match sunquake observations when the magnetic field angle changes of the order of 10° in a region where the coronal field strength is a few hundred gauss or more. The most energetic sunquakes are produced when the coronal field is strong, while the variation of magnetic field strength with height and the timescale of the change in tilt are of secondary importance.

  9. Magnetic field generations in planetary interiors

    International Nuclear Information System (INIS)

    Singh, R.N.

    1981-01-01

    One of the most fundamental properties of some better known planets is their internally generated magnetic field. A successful explanation of such magnetic fields in 'large hot planetary interiors' remains elusive. Starting from Sir Joseph Larmor's discussions of 'How could a rotating body such as Sun become a magnet' (1979) to present day general consensus that 'the existence of the geomagnetic field is a manifestation of a finite amplitude instability of the Earth's core', significant theoretical developments have taken place in this field. The essential ingredients of the successful theories are the presence of a rotating fluid core of large size having sufficiently high electrical conductivity and energy source to drive the convection. These theories use equations of Newton and Maxwell to generate the requisite kind of the magnetic and velocity fields in response to the preferred distribution of the energy sources. Studies before early seventies, were devoted, mainly, to resolve the kinematics of the problem, and have convincingly demonstrated the plausibility of regeneration action of the organised motion. However, the main problem of the dynamo-processes is yet in the early stages of development despite important contributions made by Soward and Busse. A review of some of these developments is presented. (author)

  10. Spin transfer torque generated magnetic droplet solitons (invited)

    International Nuclear Information System (INIS)

    Chung, S.; Mohseni, S. M.; Sani, S. R.; Iacocca, E.; Dumas, R. K.; Pogoryelov, Ye.; Anh Nguyen, T. N.; Muduli, P. K.; Eklund, A.; Hoefer, M.; Åkerman, J.

    2014-01-01

    We present recent experimental and numerical advancements in the understanding of spin transfer torque generated magnetic droplet solitons. The experimental work focuses on nano-contact spin torque oscillators (NC-STOs) based on orthogonal (pseudo) spin valves where the Co fixed layer has an easy-plane anisotropy, and the [Co/Ni] free layer has a strong perpendicular magnetic anisotropy. The NC-STO resistance and microwave signal generation are measured simultaneously as a function of drive current and applied perpendicular magnetic field. Both exhibit dramatic transitions at a certain current dependent critical field value, where the microwave frequency drops 10 GHz, modulation sidebands appear, and the resistance exhibits a jump, while the magnetoresistance changes sign. We interpret these observations as the nucleation of a magnetic droplet soliton with a large fraction of its magnetization processing with an angle greater than 90°, i.e., around a direction opposite that of the applied field. This interpretation is corroborated by numerical simulations. When the field is further increased, we find that the droplet eventually collapses under the pressure from the Zeeman energy

  11. Accelerator magnet power supply using storage generator

    International Nuclear Information System (INIS)

    Karady, G.; Thiessen, H.A.

    1987-01-01

    Recently, a study investigated the feasibility of a large, 60 GeV accelerator. This paper presents the conceptual design of the magnet power supply (PS() and energy storage system. The main ring magnets are supplied by six, high-voltage and two, low-voltage power supplies. These power supplies drive a trapezoidal shaped current wave through the magnets. The peak current is 10 kA and the repetition frequency is 3.3 Hz. During the acceleration period the current is increased from 1040 A to 10,000 A within 50 msec which requires a loop voltage of 120 kV and a peak power of 1250 MW. During the reset period, the PS operates as an inverter with a peak power of -1250 MW. The large energy fluctuation necessitates the use of a storage generator. Because of the relatively high operation frequency, this generator operates in a transient mode which significantly increases the rotor current and losses. The storage generator is directly driven by a variable speed drive, which draws a practically constant power of 17 MW from the ac supply network and eliminates the pulse loading. For the reduction of dc ripple, the power supplies operate in a 24 pulse mode

  12. Error field generation of solenoid magnets

    International Nuclear Information System (INIS)

    Saunders, J.L.

    1982-01-01

    Many applications for large solenoids and solenoidal arrays depend on the high precision of the axial field profile. In cases where requirements of ΔB/B for nonaxial fields are on the order of 10 -4 , the actual winding techniques of the solenoid need to be considered. Whereas an ideal solenoid consisting of current loops would generate no radial fields along the axis, in reality, the actual current-carrying conductors must follow spiral or helical paths. A straightforward method for determining the radial error fields generated by coils wound with actual techniques employed in magnet fabrication has been developed. The method devised uses a computer code which models a magnet by sending a single, current-carrying filament along the same path taken by the conductor during coil winding. Helical and spiral paths are simulated using small, straight-line current segments. This technique, whose results are presented in this paper, was used to predict radial field errors for the Elmo Bumpy Torus-Proof of Principle magnet. These results include effects due to various winding methods, not only spiral/helical and layer-to-layer transitions, but also the effects caused by worst-case tolerance conditions both from the conductor and the winding form (bobbin). Contributions made by extraneous circuitry (e.g., overhead buswork and incoming leads) are also mentioned

  13. Generating strain signals under consideration of road surface profiles

    Science.gov (United States)

    Putra, T. E.; Abdullah, S.; Schramm, D.; Nuawi, M. Z.; Bruckmann, T.

    2015-08-01

    The current study aimed to develop the mechanism for generating strain signal utilising computer-based simulation. The strain data, caused by the acceleration, were undertaken from a fatigue data acquisition involving car movements. Using a mathematical model, the measured strain signals yielded to acceleration data used to describe the bumpiness of road surfaces. The acceleration signals were considered as an external disturbance on generating strain signals. Based on this comparison, both the actual and simulated strain data have similar pattern. The results are expected to provide new knowledge to generate a strain signal via a simulation.

  14. Learning sparse generative models of audiovisual signals

    OpenAIRE

    Monaci, Gianluca; Sommer, Friedrich T.; Vandergheynst, Pierre

    2008-01-01

    This paper presents a novel framework to learn sparse represen- tations for audiovisual signals. An audiovisual signal is modeled as a sparse sum of audiovisual kernels. The kernels are bimodal functions made of synchronous audio and video components that can be positioned independently and arbitrarily in space and time. We design an algorithm capable of learning sets of such audiovi- sual, synchronous, shift-invariant functions by alternatingly solving a coding and a learning pr...

  15. Design of the Chaotic Signal Generator Based on LABVIEW

    Directory of Open Access Journals (Sweden)

    Jian-Guo Zhang

    2014-01-01

    Full Text Available We introduces a new method that can achieve the generation of Colpitts chaotic signal The system is based on virtual instrument platform and combined with MATLAB calculation to achieve the generation of Colpitts chaotic signal and making it analysis with autocorrelation and power spectrum at the same time. Signal channel output of chaotic signal was realized through USB-6009 acquisition module extending DA5405 high-speed DAC (Digital-to-Analog Converter chip. The system can adjust parameters based on customers’ requirements to achieve different frequency chaotic signal generation. Compared with the traditional autonomy Colpitts chaotic signal generator, this generator is simple and clear in structure, simple to operate, strong stability, easy to achieve etc.

  16. Measuring methods, registration and signal processing for magnetic field research

    International Nuclear Information System (INIS)

    Nagiello, Z.

    1981-01-01

    Some measuring methods and signal processing systems based on analogue and digital technics, which have been applied in magnetic field research using magnetometers with ferromagnetic transducers, are presented. (author)

  17. Search for a QGP with a TPC spectrometer, and QGP signals predicted by new event generator

    International Nuclear Information System (INIS)

    Lindenbaum, S.J.

    1988-01-01

    The BNL/CCNY/Johns Hopkins/Rice Collaboration has developed and successfully tested a TPC Magnetic Spectrometer to search for OGP signals produced by ion beams at AGS. Test data with 14.5 GeV/c /times/ A Oxygen ions incident on a Pb target has been obtained. These include a 78-prong nuclear interaction in the MPS magnet which was pattern recognized with an efficiency ∼75%. A cascade and plasma event generator has also been developed, the predictions of which are used to illustrate how our technique can detect possible plasma signals at AGS and RHIC. A 4π tracking TPC magnetic spectrometer has been proposed for RHIC. The new event generator predicts striking central rapidity bump QGP signals at RHIC for p, /bar p/, π/sup +-/, K/sup +-/, etc., produced by 100 GeV/c /times/ A Au on Au collisions and these are presented. 2 refs., 13 figs., 1 tab

  18. High Speed Wireless Signal Generation and Demodulation

    DEFF Research Database (Denmark)

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

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

  19. A device and method for generating a polybinary signal

    DEFF Research Database (Denmark)

    2018-01-01

    The present disclosure relates to a method for generating an L-level polybinary signal, comprising the steps of: providing a baseband signal with a spectrum defined by a predefined frequency period, f p ; filtering the baseband signal using a low-pass filter having a pre-defined cut-off frequency...

  20. Fluorescent lamp with static magnetic field generating means

    Science.gov (United States)

    Moskowitz, P.E.; Maya, J.

    1987-09-08

    A fluorescent lamp wherein magnetic field generating means (e.g., permanent magnets) are utilized to generate a static magnetic field across the respective electrode structures of the lamp such that maximum field strength is located at the electrode's filament. An increase in efficacy during operation has been observed. 2 figs.

  1. Brushless DC motor control system responsive to control signals generated by a computer or the like

    Science.gov (United States)

    Packard, Douglas T. (Inventor); Schmitt, Donald E. (Inventor)

    1987-01-01

    A control system for a brushless DC motor responsive to digital control signals is disclosed. The motor includes a multiphase wound stator and a permanent magnet rotor. The rotor is arranged so that each phase winding, when energized from a DC source, will drive the rotor through a predetermined angular position or step. A commutation signal generator responsive to the shaft position provides a commutation signal for each winding. A programmable control signal generator such as a computer or microprocessor produces individual digital control signals for each phase winding. The control signals and commutation signals associated with each winding are applied to an AND gate for that phase winding. Each gate controls a switch connected in series with the associated phase winding and the DC source so that each phase winding is energized only when the commutation signal and the control signal associated with that phase winding are present. The motor shaft may be advanced one step at a time to a desired position by applying a predetermined number of control signals in the proper sequence to the AND gates and the torque generated by the motor may be regulated by applying a separate control signal to each AND gate which is pulse width modulated to control the total time that each switch connects its associated winding to the DC source during each commutation period.

  2. A low noise photoelectric signal acquisition system applying in nuclear magnetic resonance gyroscope

    Science.gov (United States)

    Lu, Qilin; Zhang, Xian; Zhao, Xinghua; Yang, Dan; Zhou, Binquan; Hu, Zhaohui

    2017-10-01

    The nuclear magnetic resonance gyroscope serves as a new generation of strong support for the development of high-tech weapons, it solves the core problem that limits the development of the long-playing seamless navigation and positioning. In the NMR gyroscope, the output signal with atomic precession frequency is detected by the probe light, the final crucial photoelectric signal of the probe light directly decides the quality of the gyro signal. But the output signal has high sensitivity, resolution and measurement accuracy for the photoelectric detection system. In order to detect the measured signal better, this paper proposed a weak photoelectric signal rapid acquisition system, which has high SNR and the frequency of responded signal is up to 100 KHz to let the weak output signal with high frequency of the NMR gyroscope can be detected better.

  3. Multi-Purpose Radio Signal Generation System, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The MRSiG will be able to replace many of the expensive, highly specialized RF signal generators with cheaper generic boxes that can be customized as the...

  4. Magnetic memory signals variation induced by applied magnetic field and static tensile stress in ferromagnetic steel

    International Nuclear Information System (INIS)

    Huang, Haihong; Yang, Cheng; Qian, Zhengchun; Han, Gang; Liu, Zhifeng

    2016-01-01

    Stress can induce a spontaneous magnetic field in ferromagnetic steel under the excitation of geomagnetic field. In order to investigate the impact of applied magnetic field and tensile stress on variation of the residual magnetic signals on the surface of ferromagnetic materials, static tensile tests of Q235 structural steel were carried out, with the normal component of the residual magnetic signals, H p (y), induced by applied magnetic fields with different intensities measured through the tensile tests. The H p (y), its slope coefficient K S and maximum gradient K max changing with the applied magnetic field H and tensile stress were observed. Results show that the magnitude of H p (y) and its slope coefficient K S increase linearly with the increase of stress in the elastic deformation stage. Under yield stress, H p (y) and K S reach its maximum, and then decrease slightly with further increase of stress. Applied magnetic field affects the magnitude of H p (y) instead of changing the signal curve′s profile; and the magnitude of H p (y), K S , K max and the change rate of K S increase with the increase of applied magnetic field. The phenomenon is also discussed from the viewpoint of magnetic charge in ferromagnetic materials. - Highlights: • We investigated how applied magnetic field and tensile stress impact H p (y) signals. • Magnitude of H p (y), K S and K max increase with the increase of applied magnetic field. • Both applied magnetic field and tensile stress impact material magnetic permeability. • Applied magnetic field can help to evaluate the stress distribution of components.

  5. Magnetic memory signals variation induced by applied magnetic field and static tensile stress in ferromagnetic steel

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Haihong, E-mail: huanghaihong@hfut.edu.cn; Yang, Cheng; Qian, Zhengchun; Han, Gang; Liu, Zhifeng

    2016-10-15

    Stress can induce a spontaneous magnetic field in ferromagnetic steel under the excitation of geomagnetic field. In order to investigate the impact of applied magnetic field and tensile stress on variation of the residual magnetic signals on the surface of ferromagnetic materials, static tensile tests of Q235 structural steel were carried out, with the normal component of the residual magnetic signals, H{sub p}(y), induced by applied magnetic fields with different intensities measured through the tensile tests. The H{sub p}(y), its slope coefficient K{sub S} and maximum gradient K{sub max} changing with the applied magnetic field H and tensile stress were observed. Results show that the magnitude of H{sub p}(y) and its slope coefficient K{sub S} increase linearly with the increase of stress in the elastic deformation stage. Under yield stress, H{sub p}(y) and K{sub S} reach its maximum, and then decrease slightly with further increase of stress. Applied magnetic field affects the magnitude of H{sub p}(y) instead of changing the signal curve′s profile; and the magnitude of H{sub p}(y), K{sub S}, K{sub max} and the change rate of K{sub S} increase with the increase of applied magnetic field. The phenomenon is also discussed from the viewpoint of magnetic charge in ferromagnetic materials. - Highlights: • We investigated how applied magnetic field and tensile stress impact H{sub p}(y) signals. • Magnitude of H{sub p}(y), K{sub S} and K{sub max} increase with the increase of applied magnetic field. • Both applied magnetic field and tensile stress impact material magnetic permeability. • Applied magnetic field can help to evaluate the stress distribution of components.

  6. Second generation superconducting super collider dipole magnet cryostat design

    International Nuclear Information System (INIS)

    Niemann, R.C.; Bossert, R.C.; Carson, J.A.; Engler, N.H.; Gonczy, J.D.; Larson, E.T.; Nicol, T.H.; Ohmori, T.

    1988-12-01

    The SSC Magnet Development Program is developing accelerator dipole magnets in successive iterations. The initial iteration is complete with six full length model magnets and a thermal model having been built and tested. This initial experience along with the evolving SSC Magnet System Requirements have resulted in the second generation magnet cryostat design. It is this configuration that will be employed for the near term ongoing magnetic, thermal, string and accelerated life testing and will be the design considered for Phase I; i.e., Technology Orientation, of the SSC Magnet Industrialization Program. 5 refs., 7 figs., 1 tab

  7. Application of NMR circuit for superconducting magnet using signal averaging

    International Nuclear Information System (INIS)

    Yamada, R.; Ishimoto, H.; Shea, M.F.; Schmidt, E.E.; Borer, K.

    1977-01-01

    An NMR circuit was used to measure the absolute field values of Fermilab Energy Doubler magnets up to 44 kG. A signal averaging method to improve the S/N ratio was implemented by means of a Tektronix Digital Processing Oscilloscope, followed by the development of an inexpensive microprocessor based system contained in a NIM module. Some of the data obtained from measuring two superconducting dipole magnets are presented

  8. CAMAC based Test Signal Generator using Re-configurable device

    International Nuclear Information System (INIS)

    Sharma, Atish; Raval, Tushar; Srivastava, Amit K; Reddy, D Chenna

    2010-01-01

    There are many different types of signal generators, with different purposes and applications (and at varying levels of expense). In general, no device is suitable for all possible applications. Hence the selection of signal generator is as per requirements. For SST-1 Data Acquisition System requirements, we have developed a CAMAC based Test Signal Generator module using Re-configurable device (CPLD). This module is based on CAMAC interface but can be used for testing both CAMAC and PXI Data Acquisition Systems in SST-1 tokamak. It can also be used for other similar applications. Unlike traditional signal generators, which are embedded hardware, it is a flexible hardware unit, programmable through Graphical User Interface (GUI) developed in LabVIEW application development tool. The main aim of this work is to develop a signal generator for testing our data acquisition interface for a large number of channels simultaneously. The module front panel has various connectors like LEMO and D type connectors for signal interface. The module can be operated either in continuous signal generation mode or in triggered mode depending upon application. This can be done either by front panel switch or through CAMAC software commands (for remote operation). Similarly module reset and trigger generation operation can be performed either through front panel push button switch or through software CAMAC commands. The module has the facility to accept external TTL level trigger and clock through LEMO connectors. The module can also generate trigger and the clock signal, which can be delivered to other devices through LEMO connectors. The module generates two types of signals: Analog and digital (TTL level). The analog output (single channel) is generated from Digital to Analog Converter through CPLD for various types of waveforms like Sine, Square, Triangular and other wave shape that can vary in amplitude as well as in frequency. The module is quite useful to test up to 32 channels

  9. Strong magnetic field generation in laser plasma

    International Nuclear Information System (INIS)

    Nakarmi, J.J.; Jha, L.N.

    1996-12-01

    An attempt has been made to solve the magnetic field evolution equation by using Green function and taking convective, diffusion and nabla n x nabla T as a dominant source term. The maximum magnetic field is obtained to be an order of megagauss. (author). 14 refs, 1 fig

  10. The magnetic field gradients generation for magnetic resonance tomography; Generacja gradientow pola magnetyczbego dla tomografii MR

    Energy Technology Data Exchange (ETDEWEB)

    Jasinski, A.; Skorka, T.; Kwiecinski, S. [Institute of Nuclear Physics, Cracow (Poland)

    1994-12-31

    To obtain three-dimensional images in the computerized tomography a gradient of magnetic field should be generated. In this paper the analytical as well as computerized calculations of magnetic coils for such purposes are presented. 4 refs, 8 figs.

  11. Chiral magnetism of magnetic adatoms generated by Rashba electrons

    Science.gov (United States)

    Bouaziz, Juba; dos Santos Dias, Manuel; Ziane, Abdelhamid; Benakki, Mouloud; Blügel, Stefan; Lounis, Samir

    2017-02-01

    We investigate long-range chiral magnetic interactions among adatoms mediated by surface states spin-splitted by spin-orbit coupling. Using the Rashba model, the tensor of exchange interactions is extracted wherein a thepseudo-dipolar interaction is found, in addition to the usual isotropic exchange interaction and the Dzyaloshinskii-Moriya interaction. We find that, despite the latter interaction, collinear magnetic states can still be stabilized by the pseudo-dipolar interaction. The interadatom distance controls the strength of these terms, which we exploit to design chiral magnetism in Fe nanostructures deposited on a Au(111) surface. We demonstrate that these magnetic interactions are related to superpositions of the out-of-plane and in-plane components of the skyrmionic magnetic waves induced by the adatoms in the surrounding electron gas. We show that, even if the interatomic distance is large, the size and shape of the nanostructures dramatically impacts on the strength of the magnetic interactions, thereby affecting the magnetic ground state. We also derive an appealing connection between the isotropic exchange interaction and the Dzyaloshinskii-Moriya interaction, which relates the latter to the first-order change of the former with respect to spin-orbit coupling. This implies that the chirality defined by the direction of the Dzyaloshinskii-Moriya vector is driven by the variation of the isotropic exchange interaction due to the spin-orbit interaction.

  12. Task-related signal decrease on functional magnetic resonance imaging

    International Nuclear Information System (INIS)

    Hara, Yoshie; Nakamura, Mitsugu; Tamaki, Norihiko; Tamura, Shogo; Kitamura, Junji

    2001-01-01

    An atypical pattern of signal change was identified on functional magnetic resonance (fMR) imaging in pathologic patients. Three normal volunteers and 34 patients with pathologic lesions near the primary motor cortex underwent fMR imaging with echo-planar imaging while performing a hand motor task. Signal intensities were evaluated with the z-score method, and the time course and changes of the signal intensity were calculated. Nine of the 34 patients with pathologic lesions displayed a significant task-related signal reduction in motor-related areas. They also presented a conventional task-related signal increase in other motor-related areas. The time courses of the increase and decrease were the inverse of each other. There was no significant difference between rates of signal increase and decrease. Our findings suggest that this atypical signal decrease is clinically significant, and that impaired vascular reactivity and altered oxygen metabolism could contribute to the task-related signal reduction. Brain areas showing such task-related signal decrease should be preserved at surgery. (author)

  13. Spectral Properties of Chaotic Signals Generated by the Bernoulli Map

    Directory of Open Access Journals (Sweden)

    Rafael A. da Costa

    2014-11-01

    Full Text Available In the last decades, the use of chaotic signals as broadband carriers has been considered in Telecommunications. Despite the relevance of the frequency domain analysis in this field, there are few studies that are concerned with spectral properties of chaotic signals. Bearing this in mind, this paper aims the characterization of the power spectral density (PSD of chaotic orbits generated by Bernoulli maps. We obtain analytic expressions for autocorrelation sequence, PSD and essential bandwidth for chaotic orbits generated by this map as function of the family parameter and Lyapunov exponent. Moreover, we verify that analytical expressions match numerical results. We conclude that the power of the generated orbits is concentrated in low frequencies for all parameters values. Besides, it is possible to obtain chaotic narrowband signals.

  14. Generation of high magnetic fields using superconducting magnets

    International Nuclear Information System (INIS)

    Kiyoshi, T.; Otsuka, A.; Kosuge, M.; Yuyama, M.; Nagai, H.; Matsumoto, F.

    2006-01-01

    High-field superconducting magnets have opened new frontiers for several kinds of applications, such as fusion reactors, particle accelerators, and nuclear magnetic resonance (NMR) spectrometers. The present record for the highest field in a fully superconducting state is 23.4 T. It was achieved with a combination of NbTi, Nb 3 Sn, and Bi-2212 conductors in 1999. Since high T c (critical temperature) superconductors (HTS) have sufficiently high critical current density even in excess of 30 T, they are promising for use as high-field superconducting magnets. However, several problems still remain to be resolved for practical applications, and the use of HTS coils will be limited to the inner part of a high-field magnet system in the near future. The required technologies to develop a high-field superconducting magnet with a field of up to 28 T have already been established. Such a magnet is certain to provide information to all leading research areas

  15. Positional information generated by spatially distributed signaling cascades.

    Directory of Open Access Journals (Sweden)

    Javier Muñoz-García

    2009-03-01

    Full Text Available The temporal and stationary behavior of protein modification cascades has been extensively studied, yet little is known about the spatial aspects of signal propagation. We have previously shown that the spatial separation of opposing enzymes, such as a kinase and a phosphatase, creates signaling activity gradients. Here we show under what conditions signals stall in the space or robustly propagate through spatially distributed signaling cascades. Robust signal propagation results in activity gradients with long plateaus, which abruptly decay at successive spatial locations. We derive an approximate analytical solution that relates the maximal amplitude and propagation length of each activation profile with the cascade level, protein diffusivity, and the ratio of the opposing enzyme activities. The control of the spatial signal propagation appears to be very different from the control of transient temporal responses for spatially homogenous cascades. For spatially distributed cascades where activating and deactivating enzymes operate far from saturation, the ratio of the opposing enzyme activities is shown to be a key parameter controlling signal propagation. The signaling gradients characteristic for robust signal propagation exemplify a pattern formation mechanism that generates precise spatial guidance for multiple cellular processes and conveys information about the cell size to the nucleus.

  16. Time-Frequency Analysis of Signals Generated by Rotating Machines

    Directory of Open Access Journals (Sweden)

    R. Zetik

    1999-06-01

    Full Text Available This contribution is devoted to the higher order time-frequency analyses of signals. Firstly, time-frequency representations of higher order (TFRHO are defined. Then L-Wigner distribution (LWD is given as a special case of TFRHO. Basic properties of LWD are illustrated based on the analysis of mono-component and multi-component synthetic signals and acoustical signals generated by rotating machine. The obtained results confirm usefulness of LWD application for the purpose of rotating machine condition monitoring.

  17. Dynamical mass generation in QED with weak magnetic fields

    International Nuclear Information System (INIS)

    Ayala, A.; Rojas, E.; Bashir, A.; Raya, A.

    2006-01-01

    We study the dynamical generation of masses for fundamental fermions in quenched quantum electrodynamics in the presence of magnetic fields using Schwinger-Dyson equations. We show that, contrary to the case where the magnetic field is strong, in the weak field limit eB << m(0)2, where m(0) is the value of the dynamically generated mass in the absence of the magnetic field, masses are generated above a critical value of the coupling and that this value is the same as in the case with no magnetic field. We carry out a numerical analysis to study the magnetic field dependence of the mass function above critical coupling and show that in this regime the dynamically generated mass and the chiral condensate for the lowest Landau level increase proportionally to (eB)2

  18. Modeling the diffusion magnetic resonance imaging signal inside neurons

    International Nuclear Information System (INIS)

    Nguyen, D V; Li, J R; Grebenkov, D S; Le Bihan, D

    2014-01-01

    The Bloch-Torrey partial differential equation (PDE) describes the complex transverse water proton magnetization due to diffusion-encoding magnetic field gradient pulses. The integral of the solution of this PDE yields the diffusion magnetic resonance imaging (dMRI) signal. In a complex medium such as cerebral tissue, it is difficult to explicitly link the dMRI signal to biological parameters such as the cellular geometry or the cellular volume fraction. Studying the dMRI signal arising from a single neuron can provide insight into how the geometrical structure of neurons influences the measured signal. We formulate the Bloch-Torrey PDE inside a single neuron, under no water exchange condition with the extracellular space, and show how to reduce the 3D simulation in the full neuron to a 3D simulation around the soma and 1D simulations in the neurites. We show that this latter approach is computationally much faster than full 3D simulation and still gives accurate results over a wide range of diffusion times

  19. Relativistic Scott correction in self-generated magnetic fields

    DEFF Research Database (Denmark)

    Erdos, Laszlo; Fournais, Søren; Solovej, Jan Philip

    2012-01-01

    /3}$ and it is unchanged by including the self-generated magnetic field. We prove the first correction term to this energy, the so-called Scott correction of the form $S(\\alpha Z) Z^2$. The current paper extends the result of \\cite{SSS} on the Scott correction for relativistic molecules to include a self......-generated magnetic field. Furthermore, we show that the corresponding Scott correction function $S$, first identified in \\cite{SSS}, is unchanged by including a magnetic field. We also prove new Lieb-Thirring inequalities for the relativistic kinetic energy with magnetic fields....

  20. Highly stable and finely tuned magnetic fields generated by permanent magnet assemblies.

    Science.gov (United States)

    Danieli, E; Perlo, J; Blümich, B; Casanova, F

    2013-05-03

    Permanent magnetic materials are the only magnetic source that can be used to generate magnetic fields without power consumption or maintenance. Such stand-alone magnets are very attractive for many scientific and engineering areas, but they suffer from poor temporal field stability, which arises from the strong sensitivity of the magnetic materials and mechanical support to temperature variation. In this work, we describe a highly efficient method useful to cancel the temperature coefficient of permanent magnet assemblies in a passive and accurate way. It is based on the combination of at least two units made of magnetic materials with different temperature coefficients arranged in such a way that the ratio of the fields generated by each unit matches the ratio of their effective temperature coefficients defined by both the magnetic and mechanical contributions. Although typically available magnetic materials have negative temperature coefficients, the cancellation is achieved by aligning the fields generated by each unit in the opposite direction. We demonstrate the performance of this approach by stabilizing the field generated by a dipolar Halbach magnet, recently proposed to achieve high field homogeneity. Both the field drift and the homogeneity are monitored via nuclear magnetic resonance spectroscopy experiments. The results demonstrate the compatibility of the thermal compensation approach with existing strategies useful to fine-tune the spatial dependence of the field generated by permanent magnet arrays.

  1. Wind turbine integrated multipole permanent magnet generator (PMG)

    Energy Technology Data Exchange (ETDEWEB)

    Vilsboell, N.; Pinegin, A.; Goussarov, D.

    1996-01-01

    Designed permanent magnet generator (PMG - 20 kW) possesses a number of advantages: it makes possible to replace gearbox, the generator and possibly the hub of the wind turbine by combining wind rotor with external rotor of the generator; use of rare earth magnets Nd-Fe-B allows to reduce mass and dimensions of the generator; use of the PMG for wind turbines increases the reliability of the construction during the life time, comparing to the conventional design (gearbox, asynchronous generator). The test of the PMG -20 kW informs that design method, developed for calculation of multipole permanent magnet generators is correct in general and meets engineering requirements. The calculation uncertainty of the magnetic system and output characteristics does not exceed 2-3%. The test shows, that the maximum efficiency of the PGM - 20 kW with full load can be achieved as high as 90-91.5% and excels the efficiency of the traditional system `generator-gearbox` by 4-5.5%. Designing permanent magnet generator, it is recommended to take into account voltage stabilization (capacitance). Efficiency is expected to be higher, mass and production cost of the generator can be reduced by 25-30%. The frequency converter shall be used not only for control of rotational speed, but also to obtain sinusoidal capacitive current on the generator side. For PMG - 20 kW the angle between voltage and current should be within the range 0-23%. (au)

  2. Ultra-Compact linear chirped microwave signal generator

    DEFF Research Database (Denmark)

    Yan, Siqi; Zhou, Feng; Dong, Jianji

    2017-01-01

    A novel concept to generate linear chirped microwave signal is proposed and experimentally verified. The frequency to time mapping method is used while the Mach-Zehnder interferometer based on the photonic crystal waveguide is employed as the key device with its significant advantages of the ultra...

  3. Prioritizing Signaling Information Transmission in Next Generation Networks

    Directory of Open Access Journals (Sweden)

    Jasmina Baraković

    2011-01-01

    Full Text Available Next generation transport network is characterized by the use of in-band signaling, where Internet Protocol (IP packets carrying signaling or media information are mixed in transmission. Since transport resources are limited, when any segment of access or core network is congested, IP packets carrying signaling information may be discarded. As a consequence, it may be impossible to implement reachability and quality of service (QoS. Since present approaches are insufficient to completely address this problem, a novel approach is proposed, which is based on prioritizing signaling information transmission. To proof the concept, a simulation study was performed using Network Simulator version 2 (ns-2 and independently developed Session Initiation Protocol (SIP module. The obtained results were statistically processed using Statistical Package for the Social Sciences (SPSS version 15.0. Summarizing our research results, several issues are identified for future work.

  4. The design of photoelectric signal processing system for a nuclear magnetic resonance gyroscope based on FPGA

    Science.gov (United States)

    Zhang, Xian; Zhou, Binquan; Li, Hong; Zhao, Xinghua; Mu, Weiwei; Wu, Wenfeng

    2017-10-01

    Navigation technology is crucial to the national defense and military, which can realize the measurement of orientation, positioning, attitude and speed for moving object. Inertial navigation is not only autonomous, real-time, continuous, hidden, undisturbed but also no time-limited and environment-limited. The gyroscope is the core component of the inertial navigation system, whose precision and size are the bottleneck of the performance. However, nuclear magnetic resonance gyroscope is characteristic of the advantage of high precision and small size. Nuclear magnetic resonance gyroscope can meet the urgent needs of high-tech weapons and equipment development of new generation. This paper mainly designs a set of photoelectric signal processing system for nuclear magnetic resonance gyroscope based on FPGA, which process and control the information of detecting laser .The photoelectric signal with high frequency carrier is demodulated by in-phase and quadrature demodulation method. Finally, the processing system of photoelectric signal can compensate the residual magnetism of the shielding barrel and provide the information of nuclear magnetic resonance gyroscope angular velocity.

  5. Observation of voltage fluctuations in a superconducting magnet during MHD power generation

    International Nuclear Information System (INIS)

    Smith, R.P.; Niemann, R.C.; Kraimer, M.R.; Zinneman, T.E.

    1978-01-01

    Fluctuating voltage signals on the potential taps of the ANL 5.0 T MHD Superconducting Dipole Magnet have been observed during MHD power generation at the U-25B Facility at the High Temperature Institute (IVTAN) Moscow, USSR. Various other thermodynamic and electrical parameters of the U-25B flow train have been recorded, and statistical analysis concerning correlations between the phenomena with a view of discerning causal interdependence is in progress. Voltage fluctuations observed at the magnet terminals are analyzed with special emphasis on magnet stability

  6. Generation of zonal flows in rotating fluids and magnetized plasmas

    DEFF Research Database (Denmark)

    Juul Rasmussen, J.; Garcia, O.E.; Naulin, V.

    2006-01-01

    The spontaneous generation of large-scale flows by the rectification of small-scale turbulent fluctuations is of great importance both in geophysical flows and in magnetically confined plasmas. These flows regulate the turbulence and may set up effective transport barriers. In the present....... The analogy to large-scale flow generation in drift-wave turbulence dynamics in magnetized plasma is briefly discussed....

  7. Electron holography of magnetic field generated by a magnetic recording head.

    Science.gov (United States)

    Goto, Takayuki; Jeong, Jong Seok; Xia, Weixing; Akase, Zentaro; Shindo, Daisuke; Hirata, Kei

    2013-06-01

    The magnetic field generated by a magnetic recording head is evaluated using electron holography. A magnetic recording head, which is connected to an electric current source, is set on the specimen holder of a transmission electron microscope. Reconstructed phase images of the region around the magnetic pole show the change in the magnetic field distribution corresponding to the electric current applied to the coil of the head. A simulation of the magnetic field, which is conducted using the finite element method, reveals good agreement with the experimental observations.

  8. Microwave and Millimeter-Wave Signal Power Generation

    DEFF Research Database (Denmark)

    Hadziabdic, Dzenan

    Among the major limitations in high-speed communications and highresolution radars is the lack of efficient and powerful signal sources with low distortion. Microwave and millimeter-wave (mm-wave) signal power is needed for signal transmission. Progress in signal generation stems largely from...... distortion and high PAE were observed. The estimated output power of 42.5 dBm and PAE of 31.3% are comparable to the state-of-the-art results reported for GaN HEMT amplifiers. Wireless communication systems planned in the near future will operate at E-band, around 71-86 GHz, and require mm-wave-PAs to boost...... the application of novel materials like galliumnitride (GaN) and silicon-carbide (SiC) and fabrication of indiumphosphide (InP) based transistors. One goal of this thesis is to assess GaN HEMT technology with respect to linear efficient signal power generation. While most reports on GaN HEMT high-power devices...

  9. 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.

  10. Brief communication "Modeling tornado dynamics and the generation of infrasound, electric and magnetic fields"

    Directory of Open Access Journals (Sweden)

    E. D. Schmitter

    2010-02-01

    Full Text Available Recent observations endorse earlier measurements of time varying electric and magnetic fields generated by tornadoes and dust devils. These signals may provide a means for early warning but together with a proper modeling approach can also provide insight into geometry and dynamics of the vortices. Our model calculations show the existence of pressure resonances characterized as acoustic duct modes with well defined frequencies. These resonances not only generate infrasound but also modulate the charge density and the velocity field and in this way lead to electric and magnetic field oscillations in the 0.5–20-Hz range that can be monitored from a distance of several kilometers.

  11. Magnetic MIMO Signal Processing and Optimization for Wireless Power Transfer

    Science.gov (United States)

    Yang, Gang; Moghadam, Mohammad R. Vedady; Zhang, Rui

    2017-06-01

    In magnetic resonant coupling (MRC) enabled multiple-input multiple-output (MIMO) wireless power transfer (WPT) systems, multiple transmitters (TXs) each with one single coil are used to enhance the efficiency of simultaneous power transfer to multiple single-coil receivers (RXs) by constructively combining their induced magnetic fields at the RXs, a technique termed "magnetic beamforming". In this paper, we study the optimal magnetic beamforming design in a multi-user MIMO MRC-WPT system. We introduce the multi-user power region that constitutes all the achievable power tuples for all RXs, subject to the given total power constraint over all TXs as well as their individual peak voltage and current constraints. We characterize each boundary point of the power region by maximizing the sum-power deliverable to all RXs subject to their minimum harvested power constraints. For the special case without the TX peak voltage and current constraints, we derive the optimal TX current allocation for the single-RX setup in closed-form as well as that for the multi-RX setup. In general, the problem is a non-convex quadratically constrained quadratic programming (QCQP), which is difficult to solve. For the case of one single RX, we show that the semidefinite relaxation (SDR) of the problem is tight. For the general case with multiple RXs, based on SDR we obtain two approximate solutions by applying time-sharing and randomization, respectively. Moreover, for practical implementation of magnetic beamforming, we propose a novel signal processing method to estimate the magnetic MIMO channel due to the mutual inductances between TXs and RXs. Numerical results show that our proposed magnetic channel estimation and adaptive beamforming schemes are practically effective, and can significantly improve the power transfer efficiency and multi-user performance trade-off in MIMO MRC-WPT systems.

  12. Novel ocean energy permanent magnet linear generator buoy

    Energy Technology Data Exchange (ETDEWEB)

    Rhinefrank, K.; Agamloh, E.B.; Jouanne, A. von; Wallace, A.K.; Prudell, J.; Kimble, K.; Aills, J.; Schmidt, E.; Schacher, A. [School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331-3211 (United States); Chan, P.; Sweeny, B. [Department of Mechanical Engineering, Oregon State University, Corvallis, OR 97331-3211 (United States)

    2006-07-15

    This paper describes the research, design, construction and prototype testing process of a novel ocean energy direct drive permanent magnet linear generator buoy. The buoy employs the vertical component of the motion of ocean waves to power a linear generator. The generator consists of a permanent magnet field system (mounted on the central translator shaft) and an armature, in which the power is generated (mounted on the buoy). The translator shaft is anchored to the sea floor, and the buoy/floater moves armature coils relative to the permanent magnet translator to induce voltages. The electrical and mechanical structures of the buoy generator are provided, along with performance characteristics, including voltage, current and developed power. (author)

  13. Channel modeling, signal processing and coding for perpendicular magnetic recording

    Science.gov (United States)

    Wu, Zheng

    With the increasing areal density in magnetic recording systems, perpendicular recording has replaced longitudinal recording to overcome the superparamagnetic limit. Studies on perpendicular recording channels including aspects of channel modeling, signal processing and coding techniques are presented in this dissertation. To optimize a high density perpendicular magnetic recording system, one needs to know the tradeoffs between various components of the system including the read/write transducers, the magnetic medium, and the read channel. We extend the work by Chaichanavong on the parameter optimization for systems via design curves. Different signal processing and coding techniques are studied. Information-theoretic tools are utilized to determine the acceptable region for the channel parameters when optimal detection and linear coding techniques are used. Our results show that a considerable gain can be achieved by the optimal detection and coding techniques. The read-write process in perpendicular magnetic recording channels includes a number of nonlinear effects. Nonlinear transition shift (NLTS) is one of them. The signal distortion induced by NLTS can be reduced by write precompensation during data recording. We numerically evaluate the effect of NLTS on the read-back signal and examine the effectiveness of several write precompensation schemes in combating NLTS in a channel characterized by both transition jitter noise and additive white Gaussian electronics noise. We also present an analytical method to estimate the bit-error-rate and use it to help determine the optimal write precompensation values in multi-level precompensation schemes. We propose a mean-adjusted pattern-dependent noise predictive (PDNP) detection algorithm for use on the channel with NLTS. We show that this detector can offer significant improvements in bit-error-rate (BER) compared to conventional Viterbi and PDNP detectors. Moreover, the system performance can be further improved by

  14. Thermal spin current generation and spin transport in Pt/magnetic-insulator/Py heterostructures

    Science.gov (United States)

    Chen, Ching-Tzu; Safranski, Christopher; Krivorotov, Ilya; Sun, Jonathan

    Magnetic insulators can transmit spin current via magnon propagation while blocking charge current. Furthermore, under Joule heating, magnon flow as a result of the spin Seeback effect can generate additional spin current. Incorporating magnetic insulators in a spin-orbit torque magnetoresistive memory device can potentially yield high switching efficiencies. Here we report the DC magneto-transport studies of these two effects in Pt/magnetic-insulator/Py heterostructures, using ferrimagnetic CoFexOy (CFO) and antiferromagnet NiO as the model magnetic insulators. We observe the presence and absence of the inverse spin-Hall signals from the thermal spin current in Pt/CFO/Py and Pt/NiO/Py structures. These results are consistent with our spin-torque FMR linewidths in comparison. We will also report investigations into the magnetic field-angle dependence of these observations.

  15. Motor-Generator powering the PS (Proton Synchrotron) main magnets

    CERN Multimedia

    1983-01-01

    This motor-generator,30 MW peak, 1500 r.p.m.,pulsed power supply for the PS main magnet replaced in 1968 the initial 3000 r.p.m. motor-generator-flywheel set which had served from the PS start-up in 1959 until end 1967. See also photo 8302337 and its abstract.

  16. Development of remote control software for multiformat test signal generator

    Directory of Open Access Journals (Sweden)

    Gao Yang

    2017-01-01

    Full Text Available The multi format test signal generator mentioned in this paper is the video signal generator named TG8000 produced by Tektronix Company. I will introduce the function about remote control for signal generator, how to connect the computer to the instrument, and how to remote control. My topic uses my computer to connect the instrument through the 10/100/1000 BASE-T port on the rear panel of TG8000. Then I write program to transmit SCPI (Standard Commands for Programmable Instruments to control TG8000. The application is running on the Windows operating system, the programming language is C#, development environment is Microsoft Visual Studio 2010, using the TCP/IP protocol based on Socket. And the method of remote control refers to the application called TGSetup which is developed by Tektronix Company. This paper includes a brief summary of the basic principle, and introduce for details about the process of remote control software development, and how to use my software. In the end, I will talk about the advantages of my software compared with another one.

  17. A fast continuous magnetic field measurement system based on digital signal processors

    Energy Technology Data Exchange (ETDEWEB)

    Velev, G.V.; Carcagno, R.; DiMarco, J.; Kotelnikov, S.; Lamm, M.; Makulski, A.; /Fermilab; Maroussov, V.; /Purdue U.; Nehring, R.; Nogiec, J.; Orris, D.; /Fermilab; Poukhov,; Prakoshyn, F.; /Dubna, JINR; Schlabach, P.; Tompkins, J.C.; /Fermilab

    2005-09-01

    In order to study dynamic effects in accelerator magnets, such as the decay of the magnetic field during the dwell at injection and the rapid so-called ''snapback'' during the first few seconds of the resumption of the energy ramp, a fast continuous harmonics measurement system was required. A new magnetic field measurement system, based on the use of digital signal processors (DSP) and Analog to Digital (A/D) converters, was developed and prototyped at Fermilab. This system uses Pentek 6102 16 bit A/D converters and the Pentek 4288 DSP board with the SHARC ADSP-2106 family digital signal processor. It was designed to acquire multiple channels of data with a wide dynamic range of input signals, which are typically generated by a rotating coil probe. Data acquisition is performed under a RTOS, whereas processing and visualization are performed under a host computer. Firmware code was developed for the DSP to perform fast continuous readout of the A/D FIFO memory and integration over specified intervals, synchronized to the probe's rotation in the magnetic field. C, C++ and Java code was written to control the data acquisition devices and to process a continuous stream of data. The paper summarizes the characteristics of the system and presents the results of initial tests and measurements.

  18. A fast continuous magnetic field measurement system based on digital signal processors

    International Nuclear Information System (INIS)

    Velev, G.V.; Carcagno, R.; DiMarco, J.; Kotelnikov, S.; Lamm, M.; Makulski, A.; Maroussov, V.; Nehring, R.; Nogiec, J.; Orris, D.; Poukhov, O.; Prakoshyn, F.; Schlabach, P.; Tompkins, J.C.

    2005-01-01

    In order to study dynamic effects in accelerator magnets, such as the decay of the magnetic field during the dwell at injection and the rapid so-called ''snapback'' during the first few seconds of the resumption of the energy ramp, a fast continuous harmonics measurement system was required. A new magnetic field measurement system, based on the use of digital signal processors (DSP) and Analog to Digital (A/D) converters, was developed and prototyped at Fermilab. This system uses Pentek 6102 16 bit A/D converters and the Pentek 4288 DSP board with the SHARC ADSP-2106 family digital signal processor. It was designed to acquire multiple channels of data with a wide dynamic range of input signals, which are typically generated by a rotating coil probe. Data acquisition is performed under a RTOS, whereas processing and visualization are performed under a host computer. Firmware code was developed for the DSP to perform fast continuous readout of the A/D FIFO memory and integration over specified intervals, synchronized to the probe's rotation in the magnetic field. C, C++ and Java code was written to control the data acquisition devices and to process a continuous stream of data. The paper summarizes the characteristics of the system and presents the results of initial tests and measurements

  19. Superparamagnetic perpendicular magnetic tunnel junctions for true random number generators

    Science.gov (United States)

    Parks, Bradley; Bapna, Mukund; Igbokwe, Julianne; Almasi, Hamid; Wang, Weigang; Majetich, Sara A.

    2018-05-01

    Superparamagnetic perpendicular magnetic tunnel junctions are fabricated and analyzed for use in random number generators. Time-resolved resistance measurements are used as streams of bits in statistical tests for randomness. Voltage control of the thermal stability enables tuning the average speed of random bit generation up to 70 kHz in a 60 nm diameter device. In its most efficient operating mode, the device generates random bits at an energy cost of 600 fJ/bit. A narrow range of magnetic field tunes the probability of a given state from 0 to 1, offering a means of probabilistic computing.

  20. Microwave generation for magnetic fusion energy applications

    International Nuclear Information System (INIS)

    Antonsen, T.M. Jr.; Destler, W.W.; Granatstein, V.; Levush, B.

    1994-05-01

    This task involves the feasibility of high-power pulsed, high- efficiency, millimeter-wave free electron lasers (FEL) for ecr of thermonuclear plasmas. The research undertaken is to develop high average power FEL at voltage below IMV allowing for smaller and less costly power supplies. Linear amplification experiments employing a No. 56 period untapered wiggler have been conducted, and substantial small signal gain was observed at 95 GHz over a wide range of experimental conditions consistent with the prediction of one-dimensional numerical simulation. Progress is also reported on theoretical studies relating to the development of high-power gryotron and the ability to predict and improve the performance of various cavity designs

  1. Preliminary Modeling of Permanent Magnet Probe Flowmeter for Voltage Signal Estimation

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Uiju; Kim, Sung Joong [Hanyang Univ., Seoul (Korea, Republic of); Jeong, Ji Young; Kim, Tae Joon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    An experimental study on performance analysis of the flowmeter has been performed. The study shows that sodium flow rate is linearly proportional to the induced voltage signal from the flowmeter under the turbulent flow condition. The experimental results support its availability in the PDRC system. But, the flowmeter should be able to measure sodium flow at low Reynolds number as well. That is because the PDRC system uses sodium natural convection for its operation. Thus, calibration of the flowmeter should be done at very low sodium flow rates. However, Von Weissenfluh et al. showed that the relationship between flow rate and measured voltage signal from the flowmeter may become non-linear at very low flow rates. The nonlinearity restricts the utilization of level sensor which provide reference flow rate in the calibration experiment. The primary objective of this study is to predict the sodium flow rate range where the induced voltage signals are linearly proportional to flow rates by estimating the induced voltage signals against sodium flow rates for a wide range of flows numerically. A commercial code FLUENT is adopted for the analysis of flow field. And MAXWELL which is an electromagnetic analysis software using a finite volume method has been used to analyze the magnetic field generated by permanent magnet of the flowmeter. The induced voltage signals have been estimated by coupling the sodium flow field and the magnetic field using FLUENT MHD module. It is expected that the PMPF voltage signals are linearly proportional to flow rates range of 0.0059 to 1.96 lps. This suggests that simple calibration technique using the linearity between flow rate and the voltage signal can be adopted in calibration of the PMPF.

  2. A multifunctional energy-saving magnetic field generator

    Science.gov (United States)

    Xiong, Hui; Sun, Wanpeng; Liu, Jinzhen; Shi, Jinhua

    2018-03-01

    To improve the energy utilization of magnetic field generators for biological applications, a multifunctional energy-saving magnetic field generator (ESMFG) is presented. It is capable of producing both an alternating magnetic field (AMF) and a bipolar pulse magnetic field (BPMF) with high energy-saving and energy-reuse rates. Based on a theoretical analysis of an RLC second-order circuit, the energy-saving and energy-reuse rates of both types of magnetic fields can be calculated and are found to have acceptable values. The results of an experimental study using the proposed generator show that for the BPMF, the peak current reaches 130 A and the intensity reaches 70.3 mT. For the AMF, the intensity is 11.0 mT and the RMS current is 20 A. The energy-saving and energy-reuse rates for the AMF generator are 61.3% and 63.5%, respectively, while for the BPMF generator, the energy-saving rate is 33.6%. Thus, the proposed ESMFG has excellent potential for use in biomedical applications.

  3. Evaluation of In-Situ Magnetic Signals from Iron Oxide Nanoparticle-Labeled PC12 Cells by Atomic Force Microscopy.

    Science.gov (United States)

    Wang, Lijun; Min, Yue; Wang, Zhigang; Riggio, Cristina; Calatayud, M Pilar; Pinkernelle, Josephine; Raffa, Vittoria; Goya, Gerardo F; Keilhoff, Gerburg; Cuschieri, Alfred

    2015-03-01

    The magnetic signals from magnetite nanoparticle-labeled PC12 cells were assessed by magnetic force microscopy by deploying a localized external magnetic field to magnetize the nanoparticles and the magnetic tip simultaneously so that the interaction between the tip and PC12 cell-associated Fe3O4 nanoparticles could be detected at lift heights (the distance between the tip and the sample) larger than 100 nm. The use of large lift heights during the raster scanning of the probe eliminates the non-magnetic interference from the complex and rugged cell surface and yet maintains the sufficient sensitivity for magnetic detection. The magnetic signals of the cell-bound nanoparticles were semi-quantified by analyzing cell surface roughness upon three-dimensional reconstruction generated by the phase shift of the cantilever oscillation. The obtained data can be used for the evaluation of the overall cellular magnetization as well as the maximum magnetic forces from magnetic nanoparticle-labeled cells which is crucial for the biomedical application of these nanomaterials.

  4. VXIbus-based signal generator for resonant power supply system of the 3 GeV RCS

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fengqing; Watanabe, Yasuhiro; Koseki, Shoichiro; Tani, Norio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Adachi, Toshikazu; Someya, Hirohiko [High Energy Accelerator Reseach Organization, Tsukuba, Ibaraki (Japan)

    2002-03-01

    The 3 GeV Proton RCS of the JAERI-KEK Joint Project is a 25 Hz separate-function rapid cycling synchrotron under design. Bending magnets (BM) and quadrupole magnets (QM) are excited separately. The 3 GeV RCS requests above 10 families of magnets excited independently, far beyond 3 families in practical RCS's. Difficulty of field tracking between BM and QM is significantly increased. Magnet strings are grouped into resonant networks and excited resonantly with power supplies driven by a waveform pattern, typically a DC-biased sinusoidal signal. To achieve a close tracking between many families, the driving signal of each power supply should be adjusted in phase and amplitude flexibly and dynamically. This report proposes a signal generator based on VXIbus. The VXIbus, an extension of VMEbus (VME eXtensions for Instrument), provides an open architecture with shared process bus and timing. The VXIbus-based signal generator facilitates the timing synchronization and is easy to extend to many channels needed by the 3 GeV RCS. Experimental results of the signal generator are reported. (author)

  5. The properties of ULF/VLF signals generated by the SURA facility without ionospheric currents modulation

    Science.gov (United States)

    Kotik, D. S.; Raybov, A. V.; Ermakova, E. N.

    2012-12-01

    During the last three years the comprehensive study of ionospheric generation of the artificial signals in ULF/VLF band was carried out at SURA facility. This research was stimulated by successive HAARP experiments on detection the low frequency signals genreated due the action of the ponderomotive forces. Two experimental campaigns under different ionospheric, geomagnetic and facility operation mode conditions was undertaken every year from 2010 to 2012. Here we are summarizing the main features of the artificial ULF/VLF signals observed in vicinity the SURA site. The signals in the 2-20 Hz band were observed in the small area around the facility with the radius approximately 15 km. It was not signal detection at the 30 km distance. The maximum of the amplitude was detected in the nearest receiving point about 3 km away from the transmitting array. The amplitude increased about 3 times when the beam was inclined on16 degrees to the south so the footprint of the geomagnetic field line comes close to the point of observation. The ULF signals increased slightly when the SURA operating frequency overlaps the critical foF2 frequency. As a rule the daytime signals are smaller then nighttime one. No any correlation was observed with geomagnetic disturbances. The time delay of the ionospheric ULF signals measured by phase method was estimated as 300-400 ms. Polarization of the ULF signals has a pronounced elliptical character. Sometimes it was linear. The part of measurements in June 2012 was coincide with magnetic storm (June 16-18, Kp=6). It was observed broadening of the signal line at frequencies of 11 and 17 Hz up to 0.2 Hz at the recovery stage of the storm at June 18 (see the figure). This fact can be interpreted as the result of the signal interaction with the radiation belt protons appeared over there during the storm time. In 2012 campaigns it was firstly observed at SURA signals on frequencies of several kilohertz at nightime which could not be explained by

  6. Exterior rotor permanent magnet generator in variable speed applications

    OpenAIRE

    Sattar, Rauf

    2016-01-01

    This thesis explores approaches for converting rotational mechanical power from diesel engines into electrical power of fixed frequency and voltage. Advances in high energy permanent magnets and power electronics are enabling technologies that provide opportunities for electrical machines with increased efficiency and compact size for variable speed power generation. The overall objective was to design a permanent magnet machine with concentrated winding that could be used in variable spe...

  7. Magnetic Field Generation and Electron Acceleration in Relativistic Laser Channel

    International Nuclear Information System (INIS)

    Kostyukov, I.Yu.; Shvets, G.; Fisch, N.J.; Rax, J.M.

    2001-01-01

    The interaction between energetic electrons and a circularly polarized laser pulse inside an ion channel is studied. Laser radiation can be resonantly absorbed by electrons executing betatron oscillations in the ion channel and absorbing angular momentum from the laser. The absorbed angular momentum manifests itself as a strong axial magnetic field (inverse Faraday effect). The magnitude of this magnetic field is calculated and related to the amount of the absorbed energy. Absorbed energy and generated magnetic field are estimated for the small and large energy gain regimes. Qualitative comparisons with recent experiments are also made

  8. Morphology of magnetic fields generated in laser-produced plasmas

    International Nuclear Information System (INIS)

    Boyd, T.J.M.; Cooke, D.

    1988-01-01

    Magnetic fields in the megagauss range have been measured in experiments on plasmas generated by irradiating targets with high power lasers. A study of the morphology of these self-generated fields is important not only for its intrinsic interest but for possible implications in laser--target physics. In this paper work on the numerical modeling of large magnetic fields generated in target experiments is reported. The results show generally satisfactory agreement with the fields measured experimentally both in terms of the magnitude of the peak fields and their morphology. In the numerical model the contribution from the Hall term in describing the evolution of the magnetic field is shown to be important especially in short pulse (≅100 psec) experiments

  9. Applying computer modeling to eddy current signal analysis for steam generator and heat exchanger tube inspections

    International Nuclear Information System (INIS)

    Sullivan, S.P.; Cecco, V.S.; Carter, J.R.; Spanner, M.; McElvanney, M.; Krause, T.W.; Tkaczyk, R.

    2000-01-01

    Licensing requirements for eddy current inspections for nuclear steam generators and heat exchangers are becoming increasingly stringent. The traditional industry-standard method of comparing inspection signals with flaw signals from simple in-line calibration standards is proving to be inadequate. A more complete understanding of eddy current and magnetic field interactions with flaws and other anomalies is required for the industry to generate consistently reliable inspections. Computer modeling is a valuable tool in improving the reliability of eddy current signal analysis. Results from computer modeling are helping inspectors to properly discriminate between real flaw signals and false calls, and improving reliability in flaw sizing. This presentation will discuss complementary eddy current computer modeling techniques such as the Finite Element Method (FEM), Volume Integral Method (VIM), Layer Approximation and other analytic methods. Each of these methods have advantages and limitations. An extension of the Layer Approximation to model eddy current probe responses to ferromagnetic materials will also be presented. Finally examples will be discussed demonstrating how some significant eddy current signal analysis problems have been resolved using appropriate electromagnetic computer modeling tools

  10. Laser propagation and soliton generation in strongly magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Feng, W.; Li, J. Q.; Kishimoto, Y. [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

    2016-03-15

    The propagation characteristics of various laser modes with different polarization, as well as the soliton generation in strongly magnetized plasmas are studied numerically through one-dimensional (1D) particle-in-cell (PIC) simulations and analytically by solving the laser wave equation. PIC simulations show that the laser heating efficiency substantially depends on the magnetic field strength, the propagation modes of the laser pulse and their intensities. Generally, large amplitude laser can efficiently heat the plasma with strong magnetic field. Theoretical analyses on the linear propagation of the laser pulse in both under-dense and over-dense magnetized plasmas are well confirmed by the numerical observations. Most interestingly, it is found that a standing or moving soliton with frequency lower than the laser frequency is generated in certain magnetic field strength and laser intensity range, which can greatly enhance the laser heating efficiency. The range of magnetic field strength for the right-hand circularly polarized (RCP) soliton formation with high and low frequencies is identified by solving the soliton equations including the contribution of ion's motion and the finite temperature effects under the quasi-neutral approximation. In the limit of immobile ions, the RCP soliton tends to be peaked and stronger as the magnetic field increases, while the enhanced soliton becomes broader as the temperature increases. These findings in 1D model are well validated by 2D simulations.

  11. Magnetostrictive hypersound generation by spiral magnets in the vicinity of magnetic field induced phase transition

    Energy Technology Data Exchange (ETDEWEB)

    Bychkov, Igor V. [Chelyabinsk State University, 129 Br. Kashirinykh Str., Chelyabinsk 454001 (Russian Federation); South Ural State University (National Research University), 76 Lenin Prospekt, Chelyabinsk 454080 (Russian Federation); Kuzmin, Dmitry A., E-mail: kuzminda@csu.ru [Chelyabinsk State University, 129 Br. Kashirinykh Str., Chelyabinsk 454001 (Russian Federation); South Ural State University (National Research University), 76 Lenin Prospekt, Chelyabinsk 454080 (Russian Federation); Kamantsev, Alexander P.; Koledov, Victor V.; Shavrov, Vladimir G. [Kotelnikov Institute of Radio-engineering and Electronics of RAS, Mokhovaya Street 11-7, Moscow 125009 (Russian Federation)

    2016-11-01

    In present work we have investigated magnetostrictive ultrasound generation by spiral magnets in the vicinity of magnetic field induced phase transition from spiral to collinear state. We found that such magnets may generate transverse sound waves with the wavelength equal to the spiral period. We have examined two types of spiral magnetic structures: with inhomogeneous exchange and Dzyaloshinskii–Moriya interactions. Frequency of the waves from exchange-caused spiral magnetic structure may reach some THz, while in case of Dzyaloshinskii–Moriya interaction-caused spiral it may reach some GHz. These waves will be emitted like a sound pulses. Amplitude of the waves is strictly depends on the phase transition speed. Some aspects of microwaves to hypersound transformation by spiral magnets in the vicinity of phase transition have been investigated as well. Results of the work may be interesting for investigation of phase transition kinetics as well, as for various hypersound applications. - Highlights: • Magnetostrictive ultrasound generation by spiral magnets at phase transition (PT) is studied. • Spiral magnets during PT may generate transverse sound with wavelength equal to spiral period. • Amplitude of the sound is strictly depends on the phase transition speed. • Microwave-to-sound transformation in the vicinity of PT is investigated as well.

  12. Simulation study on avoiding runaway electron generation by magnetic perturbations

    International Nuclear Information System (INIS)

    Tokuda, S.; Yoshino, R.; Matsumoto, T.; Hudson, S.R.; Kawano, Y.; Takizuka, T.

    2001-01-01

    Simulations have demonstrated that magnetic islands having the widths expected on the major disruption cause the collisionless loss of the relativistic electrons, and that the resultant loss rate is high enough to avoid or to suppress the runaway generation. It is because, for the magnetic fluctuations in the disruption, the loss of the electron confinement due to the breakdown of the toroidal momentum conservation overwhelms the runaway electron confinement due to the phase-averaging effect of relativistic electrons. Simulation results agree closely with recent experiments on fast plasma shutdown, showing that it is possible to prevent the generation of runaway electrons. (author)

  13. SATURATION OF MAGNETOROTATIONAL INSTABILITY THROUGH MAGNETIC FIELD GENERATION

    International Nuclear Information System (INIS)

    Ebrahimi, F.; Prager, S. C.; Schnack, D. D.

    2009-01-01

    The saturation mechanism of magnetorotational instability (MRI) is examined through analytical quasi-linear theory and through nonlinear computation of a single mode in a rotating disk. We find that large-scale magnetic field is generated through the α-effect (the correlated product of velocity and magnetic field fluctuations) and causes the MRI mode to saturate. If the large-scale plasma flow is allowed to evolve, the mode can also saturate through its flow relaxation. In astrophysical plasmas, for which the flow cannot relax because of gravitational constraints, the mode saturates through field generation only.

  14. Realization of Quadrature Signal Generator Using Accurate Magnitude Integrator

    DEFF Research Database (Denmark)

    Xin, Zhen; Yoon, Changwoo; Zhao, Rende

    2016-01-01

    Second-Order Generalized Integrator based Quadrature Signal Generator (SOGI-QSG) has been widely used in single- or three-phase power converter systems due to its simplicity and flexibility. Howeever, its dynamic response is not onyl decided by its damping gain but also influences by the input...... of the AMI-QSG can thus be as simple as the typical FOS. Besides, the structure of the AMI-QSG is further configurated to be able to extract the dc component and harmonic components. The effectiveness of the proposed structures and the correctness of the theoretical analysis are evaluated by experimental...

  15. Wiggler magnetic field assisted third harmonic generation in expanding clusters

    Science.gov (United States)

    Vij, Shivani

    2018-04-01

    A simple theoretical model is constructed to study the wiggler magnetic field assisted third harmonic generation of intense short pulse laser in a cluster in its expanding phase. The ponderomotive force of laser causes density perturbations in cluster electron density which couples with wiggler magnetic field to produce a nonlinear current that generates transverse third harmonic. An intense short pulse laser propagating through a gas embedded with atomic clusters, converts it into hot plasma balls via tunnel ionization. Initially, the electron plasma frequency inside the clusters ω pe > \\sqrt{3}{ω }1 (with ω 1 being the frequency of the laser). As the cluster expands under Coulomb force and hydrodynamic pressure, ω pe decreases to \\sqrt{3}{ω }1. At this time, there is resonant enhancement in the efficiency of the third harmonic generation. The efficiency of third harmonic generation is enhanced due to cluster plasmon resonance and by phase matching due to wiggler magnetic field. The effect of cluster size on the expansion rate is studied to observe that the clusters of different radii would expand differently. The impact of laser intensity and wiggler magnetic field on the efficiency of third harmonic generation is also explored.

  16. Contribution of the magnetic resonance to the third harmonic generation from a fishnet metamaterial

    Science.gov (United States)

    Reinhold, J.; Shcherbakov, M. R.; Chipouline, A.; Panov, V. I.; Helgert, C.; Paul, T.; Rockstuhl, C.; Lederer, F.; Kley, E.-B.; Tünnermann, A.; Fedyanin, A. A.; Pertsch, T.

    2012-09-01

    We investigate experimentally and theoretically the third harmonic generated by a double-layer fishnet metamaterial. To unambiguously disclose most notably the influence of the magnetic resonance, the generated third harmonic was measured as a function of the angle of incidence. It is shown experimentally and numerically that when the magnetic resonance is excited by a pump beam, the angular dependence of the third harmonic signal has a local maximum at an incidence angle of θ≃20∘. This maximum is shown to be a fingerprint of the antisymmetric distribution of currents in the gold layers. An analytical model based on the nonlinear dynamics of the electrons inside the gold shows excellent agreement with experimental and numerical results. This clearly indicates the difference in the third harmonic angular pattern at electric and magnetic resonances of the metamaterial.

  17. Modeling Guidelines for Code Generation in the Railway Signaling Context

    Science.gov (United States)

    Ferrari, Alessio; Bacherini, Stefano; Fantechi, Alessandro; Zingoni, Niccolo

    2009-01-01

    Modeling guidelines constitute one of the fundamental cornerstones for Model Based Development. Their relevance is essential when dealing with code generation in the safety-critical domain. This article presents the experience of a railway signaling systems manufacturer on this issue. Introduction of Model-Based Development (MBD) and code generation in the industrial safety-critical sector created a crucial paradigm shift in the development process of dependable systems. While traditional software development focuses on the code, with MBD practices the focus shifts to model abstractions. The change has fundamental implications for safety-critical systems, which still need to guarantee a high degree of confidence also at code level. Usage of the Simulink/Stateflow platform for modeling, which is a de facto standard in control software development, does not ensure by itself production of high-quality dependable code. This issue has been addressed by companies through the definition of modeling rules imposing restrictions on the usage of design tools components, in order to enable production of qualified code. The MAAB Control Algorithm Modeling Guidelines (MathWorks Automotive Advisory Board)[3] is a well established set of publicly available rules for modeling with Simulink/Stateflow. This set of recommendations has been developed by a group of OEMs and suppliers of the automotive sector with the objective of enforcing and easing the usage of the MathWorks tools within the automotive industry. The guidelines have been published in 2001 and afterwords revisited in 2007 in order to integrate some additional rules developed by the Japanese division of MAAB [5]. The scope of the current edition of the guidelines ranges from model maintainability and readability to code generation issues. The rules are conceived as a reference baseline and therefore they need to be tailored to comply with the characteristics of each industrial context. Customization of these

  18. SCMS-1, Superconducting Magnet System for an MHD generator

    International Nuclear Information System (INIS)

    Zenkevich, V.B.; Kirenin, I.A.; Tovma, V.A.

    1977-01-01

    The research and development effort connected with the building of the superconducting magnet systems for MHD generators at the Institute for High Temperatures of the U.S.S.R. Academy of Sciences included the designing, fabrication and testing of the superconducting magnet system for an MHD generator (SCMS-1), producing a magnetic field up to 4 Tesla in a warm bore tube 300 mm in diameter and 1000 mm long (the nonuniformity of the magnetic field in the warm bore did not exceed +-5%. The superconducting magnet system is described. The design selected consisted of a dipole, saddle-form coil, wound around a tube. The cooling of the coils is of the external type with helium access to each layer of the winding. For winding of the superconducting magnet system a 49-strand cable was used consisting of 42 composition conductors, having a diameter of 0.3 mm each, containing six superconducting strands with a niobium-titanium alloy base (the superconducting strands were 70 microns in diameter), and seven copper conductors of the same diameter as the composite conductors. The cable is made monolithic with high purity indium and insulated with lavsan fiber. The cable diameter with insulation is 3.5 mm

  19. Design and analysis of tubular permanent magnet linear wave generator.

    Science.gov (United States)

    Si, Jikai; Feng, Haichao; Su, Peng; Zhang, Lufeng

    2014-01-01

    Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG) and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG.

  20. Design and Analysis of Tubular Permanent Magnet Linear Wave Generator

    Directory of Open Access Journals (Sweden)

    Jikai Si

    2014-01-01

    Full Text Available Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG.

  1. Design and Analysis of Tubular Permanent Magnet Linear Wave Generator

    Science.gov (United States)

    Si, Jikai; Feng, Haichao; Su, Peng; Zhang, Lufeng

    2014-01-01

    Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG) and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG. PMID:25050388

  2. Laser light absorption and harmonic generation due to self-generated magnetic fields

    International Nuclear Information System (INIS)

    Kruer, W.L.; Estabrook, K.G.

    1977-01-01

    It is shown that self-generated magnetic fields can play a significant role in laser light absorption. Even normally incident light will then be resonantly absorbed. Computer simulations and theoretical estimates for this absorption and the concomitant harmonic generation are given for parameters characteristic of some recent experiments

  3. Method for increasing nuclear magnetic resonance signals in living biological tissue

    International Nuclear Information System (INIS)

    Krongrad, A.

    1995-01-01

    A method of enhancing a magnetic resonance comprising the steps of administering a quantity of a selected magnetic isotope to a living biological tissue at a concentration greater than the naturally occurring concentration of such isotope and detecting magnetic resonance signal from the administered magnetic isotope in the living biological tissue. (author)

  4. Dynamic Analysis of Permanent Magnet Synchronous Generator with Power Electronics

    Directory of Open Access Journals (Sweden)

    OZCIRA, S.

    2010-05-01

    Full Text Available Permanent magnet DC motor-generators (PMDC, PMSG have been widely used in industrial and energy sectors recently. Power control of these systems can be achieved by controlling the output voltage. In this study, PMDC-PMSG systems are mathematically modeled and simulated in MATLAB and Simulink software. Then the results are discussed. A low power permanent magnet synchronous generator is driven by a permanent magnet DC motor and the output voltage is controlled by a frequency cycle-converter. The output of a half-wave uncontrolled rectifier is applied to an SPWM inverter and the power is supplied to a 300V, 50Hz load. The load which is connected to an LC filter is modeled by state-space equations. LC filter is utilized in order to suppress the voltage oscillations at the inverter output.

  5. Superconducting super collider second generation dipole magnet cryostat design

    International Nuclear Information System (INIS)

    Niemann, R.C.; Bossert, R.C.; Carson, J.A.; Engler, N.H.; Gonczy, J.D.; Larson, E.T.; Nicol, T.H.; Ohmori, T.

    1988-12-01

    The Superconducting Super Collider, a planned colliding beam particle physics research facility, requires /approximately/10,000 superconducting devices for the control of high energy particle beams. The /approximately/7,500 collider ring superconducting dipole magnets require cryostats that are functional, cryogenically efficient, mass producible and cost effective. A second generation cryostat design has been developed utilizing the experiences gained during the construction, installation and operation of several full length first generation dipole magnet models. The nature of the cryostat improvements is presented. Considered are the connections between the magnet cold mass and its supports, cryogenic supports, cold mass axial anchor, thermal shields, insulation, vacuum vessel and interconnections. The details of the improvements are enumerated and the abstracted results of available component and system evaluations are presented. 8 refs., 11 figs

  6. Laser-generated magnetic fields in quasi-hohlraum geometries

    Science.gov (United States)

    Pollock, Bradley; Turnbull, David; Ross, Steven; Hazi, Andrew; Ralph, Joseph; Lepape, Sebastian; Froula, Dustin; Haberberger, Dan; Moody, John

    2014-10-01

    Laser-generated magnetic fields of 10--40 T have been produced with 100--4000 J laser drives at Omega EP and Titan. The fields are generated using the technique described by Daido et al. [Phys. Rev. Lett. 56, 846 (1986)], which works by directing a laser through a hole in one plate to strike a second plate. Hot electrons generated in the laser-produced plasma on the second plate collect on the first plate. A strap connects the two plates allowing a current of 10 s of kA to flow and generate a solenoidal magnetic field. The magnetic field is characterized using Faraday rotation, b-dot probes, and proton radiography. Further experiments to study the effect of the magnetic field on hohlraum performance are currently scheduled for Omega. This work was performed under the auspices of the United States Department of Energy by the Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA-27344.

  7. Digitally generated excitation and near-baseband quadrature detection of rapid scan EPR signals.

    Science.gov (United States)

    Tseitlin, Mark; Yu, Zhelin; Quine, Richard W; Rinard, George A; Eaton, Sandra S; Eaton, Gareth R

    2014-12-01

    The use of multiple synchronized outputs from an arbitrary waveform generator (AWG) provides the opportunity to perform EPR experiments differently than by conventional EPR. We report a method for reconstructing the quadrature EPR spectrum from periodic signals that are generated with sinusoidal magnetic field modulation such as continuous wave (CW), multiharmonic, or rapid scan experiments. The signal is down-converted to an intermediate frequency (IF) that is less than the field scan or field modulation frequency and then digitized in a single channel. This method permits use of a high-pass analog filter before digitization to remove the strong non-EPR signal at the IF, that might otherwise overwhelm the digitizer. The IF is the difference between two synchronized X-band outputs from a Tektronix AWG 70002A, one of which is for excitation and the other is the reference for down-conversion. To permit signal averaging, timing was selected to give an exact integer number of full cycles for each frequency. In the experiments reported here the IF was 5kHz and the scan frequency was 40kHz. To produce sinusoidal rapid scans with a scan frequency eight times IF, a third synchronized output generated a square wave that was converted to a sine wave. The timing of the data acquisition with a Bruker SpecJet II was synchronized by an external clock signal from the AWG. The baseband quadrature signal in the frequency domain was reconstructed. This approach has the advantages that (i) the non-EPR response at the carrier frequency is eliminated, (ii) both real and imaginary EPR signals are reconstructed from a single physical channel to produce an ideal quadrature signal, and (iii) signal bandwidth does not increase relative to baseband detection. Spectra were obtained by deconvolution of the reconstructed signals for solid BDPA (1,3-bisdiphenylene-2-phenylallyl) in air, 0.2mM trityl OX63 in water, 15 N perdeuterated tempone, and a nitroxide with a 0.5G partially-resolved proton

  8. Methods of high current magnetic field generator for transcranial magnetic stimulation application

    International Nuclear Information System (INIS)

    Bouda, N. R.; Pritchard, J.; Weber, R. J.; Mina, M.

    2015-01-01

    This paper describes the design procedures and underlying concepts of a novel High Current Magnetic Field Generator (HCMFG) with adjustable pulse width for transcranial magnetic stimulation applications. This is achieved by utilizing two different switching devices, the MOSFET and insulated gate bipolar transistor (IGBT). Results indicate that currents as high as ±1200 A can be generated with inputs of +/−20 V. Special attention to tradeoffs between field generators utilizing IGBT circuits (HCMFG 1 ) and MOSFET circuits (HCMFG 2 ) was considered. The theory of operation, design, experimental results, and electronic setup are presented and analyzed

  9. Methods of high current magnetic field generator for transcranial magnetic stimulation application

    Science.gov (United States)

    Bouda, N. R.; Pritchard, J.; Weber, R. J.; Mina, M.

    2015-05-01

    This paper describes the design procedures and underlying concepts of a novel High Current Magnetic Field Generator (HCMFG) with adjustable pulse width for transcranial magnetic stimulation applications. This is achieved by utilizing two different switching devices, the MOSFET and insulated gate bipolar transistor (IGBT). Results indicate that currents as high as ±1200 A can be generated with inputs of +/-20 V. Special attention to tradeoffs between field generators utilizing IGBT circuits (HCMFG1) and MOSFET circuits (HCMFG2) was considered. The theory of operation, design, experimental results, and electronic setup are presented and analyzed.

  10. Methods of high current magnetic field generator for transcranial magnetic stimulation application

    Energy Technology Data Exchange (ETDEWEB)

    Bouda, N. R., E-mail: nybouda@iastate.edu; Pritchard, J.; Weber, R. J.; Mina, M. [Department of Electrical and Computer engineering, Iowa State University, Ames, Iowa 50011 (United States)

    2015-05-07

    This paper describes the design procedures and underlying concepts of a novel High Current Magnetic Field Generator (HCMFG) with adjustable pulse width for transcranial magnetic stimulation applications. This is achieved by utilizing two different switching devices, the MOSFET and insulated gate bipolar transistor (IGBT). Results indicate that currents as high as ±1200 A can be generated with inputs of +/−20 V. Special attention to tradeoffs between field generators utilizing IGBT circuits (HCMFG{sub 1}) and MOSFET circuits (HCMFG{sub 2}) was considered. The theory of operation, design, experimental results, and electronic setup are presented and analyzed.

  11. Experimentally generated randomness certified by the impossibility of superluminal signals.

    Science.gov (United States)

    Bierhorst, Peter; Knill, Emanuel; Glancy, Scott; Zhang, Yanbao; Mink, Alan; Jordan, Stephen; Rommal, Andrea; Liu, Yi-Kai; Christensen, Bradley; Nam, Sae Woo; Stevens, Martin J; Shalm, Lynden K

    2018-04-01

    From dice to modern electronic circuits, there have been many attempts to build better devices to generate random numbers. Randomness is fundamental to security and cryptographic systems and to safeguarding privacy. A key challenge with random-number generators is that it is hard to ensure that their outputs are unpredictable 1-3 . For a random-number generator based on a physical process, such as a noisy classical system or an elementary quantum measurement, a detailed model that describes the underlying physics is necessary to assert unpredictability. Imperfections in the model compromise the integrity of the device. However, it is possible to exploit the phenomenon of quantum non-locality with a loophole-free Bell test to build a random-number generator that can produce output that is unpredictable to any adversary that is limited only by general physical principles, such as special relativity 1-11 . With recent technological developments, it is now possible to carry out such a loophole-free Bell test 12-14,22 . Here we present certified randomness obtained from a photonic Bell experiment and extract 1,024 random bits that are uniformly distributed to within 10 -12 . These random bits could not have been predicted according to any physical theory that prohibits faster-than-light (superluminal) signalling and that allows independent measurement choices. To certify and quantify the randomness, we describe a protocol that is optimized for devices that are characterized by a low per-trial violation of Bell inequalities. Future random-number generators based on loophole-free Bell tests may have a role in increasing the security and trust of our cryptographic systems and infrastructure.

  12. Feedback Signal from Motoneurons Influences a Rhythmic Pattern Generator.

    Science.gov (United States)

    Rotstein, Horacio G; Schneider, Elisa; Szczupak, Lidia

    2017-09-20

    the actual rhythmic pattern of movements. We have investigated whether motoneurons are limited to function as output units. Analysis of the network that controls crawling behavior in the leech has clearly indicated that motoneurons, in addition to controlling muscle activity, send signals to the pattern generator. Physiological and modeling studies on the role of specific motoneurons suggest that these feedback signals modulate the phase relationship of the rhythmic activity. Copyright © 2017 the authors 0270-6474/17/379149-11$15.00/0.

  13. Entropy Generation in Natural Convection Under an Evanescent Magnetic Field

    International Nuclear Information System (INIS)

    Magherbi, Mourad; El Jery, Atef; Ben Brahim, Ammar

    2009-01-01

    We numerically study the effect of an externally-evanescent magnetic field on total entropy generation in conducting and non-reactive fluid enclosed in a square cavity. The horizontal walls of the enclosure are assumed to be insulated while the vertical walls are kept isothermal. A control volume finite element method is used to solve the conservation equations at Prandtl number of 0.71. The values of relaxation time of the magnetic field are chosen, so that the Lorentz force acts only in the transient state of entropy generation in natural convection. The total entropy generation was calculated for fixed value of irreversibility distribution ratio, different relaxation time varying from 0 to 1/5 and Grashof number equal to 10 5

  14. Macromolecular crystallization in microgravity generated by a superconducting magnet.

    Science.gov (United States)

    Wakayama, N I; Yin, D C; Harata, K; Kiyoshi, T; Fujiwara, M; Tanimoto, Y

    2006-09-01

    About 30% of the protein crystals grown in space yield better X-ray diffraction data than the best crystals grown on the earth. The microgravity environments provided by the application of an upward magnetic force constitute excellent candidates for simulating the microgravity conditions in space. Here, we describe a method to control effective gravity and formation of protein crystals in various levels of effective gravity. Since 2002, the stable and long-time durable microgravity generated by a convenient type of superconducting magnet has been available for protein crystal growth. For the first time, protein crystals, orthorhombic lysozyme, were grown at microgravity on the earth, and it was proved that this microgravity improved the crystal quality effectively and reproducibly. The present method always accompanies a strong magnetic field, and the magnetic field itself seems to improve crystal quality. Microgravity is not always effective for improving crystal quality. When we applied this microgravity to the formation of cubic porcine insulin and tetragonal lysozyme crystals, we observed no dependence of effective gravity on crystal quality. Thus, this kind of test will be useful for selecting promising proteins prior to the space experiments. Finally, the microgravity generated by the magnet is compared with that in space, considering the cost, the quality of microgravity, experimental convenience, etc., and the future use of this microgravity for macromolecular crystal growth is discussed.

  15. Study and realisation of a programmable generator of pulse sequences, for nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Lambert, Daniel

    1974-01-01

    After having recalled the operation of pulse-based nuclear magnetic resonance and the use of pulse sequences in NMR-based measurements, and outlined the need for a pulse sequence generator, the author reports the design and realisation of such a device. He describes its general organisation with its base sequence, base clock, sequence start, duration, displays, data transfers, data processing, and signal distribution. He presents the chosen technology (ECL logics), the sequence base set, time bases, multiplexers, comparison sets, the distribution set, the sequence programming, the sampling and output set. He reports tests and the use of the so-designed generator [fr

  16. Generation and reception of spread-spectrum signals

    Science.gov (United States)

    Moser, R.

    1983-05-01

    The term 'spread-spectrum' implies a technique whereby digitized information is added to a pseudo-random number sequence and the resultant bit stream changes some parameter of the carrier frequency in discrete increments. The discrete modulation of the carrier frequency is usually realized either as a multiple level phase shift keyed or frequency shift keyed signal. The resultant PSK-modulated frequency spectrum is referred to as direct sequence spread-spectrum, whereas the FSK-modulated carrier frequency is referred to as a frequency hopped spread spectrum. These can be considered the major subsets of the more general term 'spread-spectrum'. In discussing signal reception, it is pointed out that active correlation methods are used for channel synchronization when the psuedo random sequences are long or when the processing gain is large, whereas the passive methods may be used for either short pseudo-random noise generation codes or to assist in attaining initial synchronization in long sequence spread-spectrum systems.

  17. Power Maximization Control of Variable Speed Wind Generation System Using Permanent Magnet Synchronous Generator

    Science.gov (United States)

    Morimoto, Shigeo; Nakamura, Tomohiko; Takeda, Yoji

    This paper proposes the sensorless output power maximization control of the wind generation system. A permanent magnet synchronous generator (PMSG) is used as a variable speed generator in the proposed system. The generator torque is suitably controlled according to the generator speed and thus the power from a wind turbine settles down on the maximum power point by the proposed MPPT control method, where the information of wind velocity is not required. Moreover, the maximum available generated power is obtained by the optimum current vector control. The current vector of PMSG is optimally controlled according to the generator speed and the required torque in order to minimize the losses of PMSG considering the voltage and current constraints. The proposed wind power generation system can be achieved without mechanical sensors such as a wind velocity detector and a position sensor. Several experimental results show the effectiveness of the proposed control method.

  18. Search for QGP signals at AGS with a TPC spectrometer, and comparison of our event generator predictions for plasma model and cascade interactions

    International Nuclear Information System (INIS)

    Lindenbaum, S.J.; Foley, K.J.; Eiseman, S.E.

    1988-01-01

    We have developed and successfully tested a TPC Magnetic Spectrometer to search for QGP signals produced by ion beams at AGS. We also developed a cascade and plasma event generator the predictions of which are used to illustrate how our technique can detect possible plasma signals. 4 refs., 6 figs., 1 tab

  19. Photonic Ultra-Wideband 781.25-Mb/s Signal Generation and Transmission Incorporating Digital Signal Processing Detection

    DEFF Research Database (Denmark)

    Gibbon, Timothy Braidwood; Yu, Xianbin; Tafur Monroy, Idelfonso

    2009-01-01

    The generation of photonic ultra-wideband (UWB) impulse signals using an uncooled distributed-feedback laser is proposed. For the first time, we experimentally demonstrate bit-for-bit digital signal processing (DSP) bit-error-rate measurements for transmission of a 781.25-Mb/s photonic UWB signal...

  20. Magnetic separation technique for environmental water purification by strong magnetic field generator loading HTS bulk magnets

    International Nuclear Information System (INIS)

    Oka, T.; Tanaka, K.; Kimura, T.; Mimura, D.; Fukui, S.; Ogawa, J.; Sato, T.; Ooizumi, M.; Yokoyama, K.; Yamaguchi, M.

    2010-01-01

    The magnetic separation technique in combination with high temperature superconducting bulk magnets has been investigated to purify the ground water which has been used in the coolant system for the incinerator furnace to cool the burning gas. The experiment has been operated by means of the newly-built alternating channel type magnetic separating device. The separation ratios of ferromagnetic flocks including fine magnetite powder have been estimated by means of the high gradient magnetic separation method with small iron balls filled in the water channels. As the magnetic force acting on the magnetic particle is given by the product of a magnetization of the material and a gradient of magnetic field, and as the ferromagnetic stainless steel balls yield the steep gradient of magnetic field around them in a strong magnetic field, the system has exhibited a quite excellent performance with respect to the separation ratios. The separation ratios of the flocks which contain the magnetite powder with the values more than 50 ppm have remained over 80% for under the flow rates less than 5 L/min.

  1. Research of Cubic Bezier Curve NC Interpolation Signal Generator

    Directory of Open Access Journals (Sweden)

    Shijun Ji

    2014-08-01

    Full Text Available Interpolation technology is the core of the computer numerical control (CNC system, and the precision and stability of the interpolation algorithm directly affect the machining precision and speed of CNC system. Most of the existing numerical control interpolation technology can only achieve circular arc interpolation, linear interpolation or parabola interpolation, but for the numerical control (NC machining of parts with complicated surface, it needs to establish the mathematical model and generate the curved line and curved surface outline of parts and then discrete the generated parts outline into a large amount of straight line or arc to carry on the processing, which creates the complex program and a large amount of code, so it inevitably introduce into the approximation error. All these factors affect the machining accuracy, surface roughness and machining efficiency. The stepless interpolation of cubic Bezier curve controlled by analog signal is studied in this paper, the tool motion trajectory of Bezier curve can be directly planned out in CNC system by adjusting control points, and then these data were put into the control motor which can complete the precise feeding of Bezier curve. This method realized the improvement of CNC trajectory controlled ability from the simple linear and circular arc to the complex project curve, and it provides a new way for economy realizing the curve surface parts with high quality and high efficiency machining.

  2. Experimental and simulation studies on the behavior of signal harmonics in magnetic particle imaging.

    Science.gov (United States)

    Murase, Kenya; Konishi, Takashi; Takeuchi, Yuki; Takata, Hiroshige; Saito, Shigeyoshi

    2013-07-01

    Our purpose in this study was to investigate the behavior of signal harmonics in magnetic particle imaging (MPI) by experimental and simulation studies. In the experimental studies, we made an apparatus for MPI in which both a drive magnetic field (DMF) and a selection magnetic field (SMF) were generated with a Maxwell coil pair. The MPI signals from magnetic nanoparticles (MNPs) were detected with a solenoid coil. The odd- and even-numbered harmonics were calculated by Fourier transformation with or without background subtraction. The particle size of the MNPs was measured by transmission electron microscopy (TEM), dynamic light-scattering, and X-ray diffraction methods. In the simulation studies, the magnetization and particle size distribution of MNPs were assumed to obey the Langevin theory of paramagnetism and a log-normal distribution, respectively. The odd- and even-numbered harmonics were calculated by Fourier transformation under various conditions of DMF and SMF and for three different particle sizes. The behavior of the harmonics largely depended on the size of the MNPs. When we used the particle size obtained from the TEM image, the simulation results were most similar to the experimental results. The similarity between the experimental and simulation results for the even-numbered harmonics was better than that for the odd-numbered harmonics. This was considered to be due to the fact that the odd-numbered harmonics were more sensitive to background subtraction than were the even-numbered harmonics. This study will be useful for a better understanding, optimization, and development of MPI and for designing MNPs appropriate for MPI.

  3. On the electric and magnetic field generation in expanding plasmas

    International Nuclear Information System (INIS)

    Gielen, H.J.G.

    1989-01-01

    This thesis deals with the generation of electric and magnetic fields in expanding plasmas. The theoretical model used to calculate the different field quantities in such plasmas is discussed in part 1 and is in fact an analysis of Ohm's law. A general method is given that decomposes each of the forces terms in Ohm's law in a component that induces a charge separation in the plasma and in a component that can drive current. This decomposition is unambiguous and depends upon the boundary conditions for the electric potential. It is shown that in calculating the electromagnetic field quantities in a plasma that is located in the vicinity of a boundary that imposes constraints on the electric potential, Ohm's law should be analyzed instead of the so-called induction equation. Three applications of the model are presented. A description is given of the unipolar arc discharge where both plasma and sheath effects have been taken into account. Secondly a description is presented of the plasma effects of a cathode spot. The third application of the model deals with the generation of magnetic fields in laser-produced plasmas. The second part of this thesis describes the experiments on a magnetized argon plasma expanding from a cascaded arc. With the use of spectroscopic techniques the electron density, ion temperature and the rotation velocity profiles of the ion gas have been determined. The magnetic field generated by the plasma has been measured with the use of the Zeeman effect. Depending on the channel diameter of the nozzle of the cascaded arc, self-generated magnetic fields with axial components of the order of 1% of the externally applied mangetic field have been observed. From the measured ion rotation it has been concluded that this magnetic field is mainly generated by azimuthal electron currents. The corresponding azimuthal current density is of the order of 15% of the axial current density. The observed ion rotation is caused by electron-ion friction. (author

  4. FUZZY FAULT DETECTION FOR PERMANENT MAGNET SYNCHRONOUS GENERATOR

    Directory of Open Access Journals (Sweden)

    N. Selvaganesan

    2011-07-01

    Full Text Available Faults in engineering systems are difficult to avoid and may result in serious consequences. Effective fault detection and diagnosis can improve system reliability and avoid expensive maintenance. In this paper fuzzy system based fault detection scheme for permanent magnet synchronous generator is proposed. The sequence current components like positive and negative sequence currents are used as fault indicators and given as inputs to fuzzy fault detector. Also, the fuzzy inference system is created and rule base is evaluated, relating the sequence current component to the type of faults. These rules are fired for specific changes in sequence current component and the faults are detected. The feasibility of the proposed scheme for permanent magnet synchronous generator is demonstrated for different types of fault under various operating conditions using MATLAB/Simulink.

  5. Higher magnetic field multipoles generated by superconductor magnetization within a set of nested superconducting correction coils

    International Nuclear Information System (INIS)

    Green, M.A.

    1990-01-01

    Correction elements in colliding beam accelerators such as the Superconducting Super Collider (SSC) can be the source of undesirable higher magnetic field multipoles due to magnetization of the superconductor within the corrector. Quadrupole and sextupole correctors located within the main dipole will produce sextupole and decapole due to magnetization of the superconductor within the correction coils. Lumped nested correction coils can produce a large number of skew and normal magnetization multipoles which may have an adverse effect on a stored beam at injection into a high energy colliding beam machine such as the SSC. Multipole magnetization field components have been measured within the HERA storage ring dipole magnets. Calculations of these components using the SCMAG04 code, which agree substantially with the measured multipoles, are presented in the report. As a result, in the proposed continuous correction winding for the SSC, dipoles have been replaced with lumped correction elements every six dipole magnets (about 120 meters apart). Nested lumped correction elements will also produce undesirable higher magnetization multipoles. This report shows a method by which the higher multipole generated by nested correction elements can be identified. (author)

  6. Precise Thermometry for Next Generation LHC Superconducting Magnet Prototypes

    CERN Document Server

    Datskov, V; Bottura, L; Perez, J C; Borgnolutti, F; Jenninger, B; Ryan, P

    2013-01-01

    The next generation of LHC superconducting magnets is very challenging and must operate in harsh conditions: high radiation doses in a range between 10 and 50 MGy, high voltage environment of 1 to 5 kV during the quench, dynamic high magnetic field up to 12 T, dynamic temperature range 1.8 K to 300 K in 0.6 sec. For magnet performance and long term reliability it is important to study dynamic thermal effects, such as the heat flux through the magnet structure, or measuring hot spot in conductors during a magnet quench with high sampling rates above 200 Hz. Available on the market cryogenic temperature sensors comparison is given. An analytical model for special electrically insulating thermal anchor (Kapton pad) with high voltage insulation is described. A set of instrumentation is proposed for fast monitoring of thermal processes during normal operation, quenches and failure situations. This paper presents the technology applicable for mounting temperature sensors on high voltage superconducting (SC) cables....

  7. Axial Permanent Magnet Generator for Wearable Energy Harvesting

    DEFF Research Database (Denmark)

    Högberg, Stig; Sødahl, Jakob Wagner; Mijatovic, Nenad

    2016-01-01

    An increasing demand for battery-free electronics is evident by the rapid increase of wearable devices, and the design of wearable energy harvesters follows accordingly. An axial permanent magnet generator was designed to harvest energy from human body motion and supplying it to a wearable......W, respectively) with an iron yoke is subject to losses that exceed the realistic input power, and was therefore deemed infeasible. A generator without the iron yoke was concluded to perform well as a wearable energy harvester. An experimental investigation of a prototype revealed an output power of almost 1 m...

  8. Magnetic nanoparticles: reactive oxygen species generation and potential therapeutic applications

    Science.gov (United States)

    Mai, Trang; Hilt, J. Zach

    2017-07-01

    Magnetic nanoparticles have been demonstrated to produce reactive oxygen species (ROS), which play a major role in various cellular pathways, via Fenton and Haber-Weiss reaction. ROS act as a double-edged sword inside the body. At normal conditions, the generation of ROS is in balance with their elimination by scavenger systems, and they can promote cell proliferation as well as differentiation. However, at an increased level, they can cause damages to protein, lead to cellular apoptosis, and contribute to many diseases including cancer. Many recent studies proposed a variety of strategies to either suppress toxicity of ROS generation or exploit the elevated ROS levels for cancer therapy.

  9. Numerical simulation of explosive magnetic cumulative generator EMG-720

    Energy Technology Data Exchange (ETDEWEB)

    Deryugin, Yu N; Zelenskij, D K; Kazakova, I F; Kargin, V I; Mironychev, P V; Pikar, A S; Popkov, N F; Ryaslov, E A; Ryzhatskova, E G [All-Russian Research Inst. of Experimental Physics, Sarov (Russian Federation)

    1997-12-31

    The paper discusses the methods and results of numerical simulations used in the development of a helical-coaxial explosive magnetic cumulative generator (EMG) with the stator up to 720 mm in diameter. In the process of designing, separate units were numerically modeled, as was the generator operation with a constant inductive-ohmic load. The 2-D processes of the armature acceleration by the explosion products were modeled as well as those of the formation of the sliding high-current contact between the armature and stator`s insulated turns. The problem of the armature integrity in the region of the detonation waves collision was numerically analyzed. 8 figs., 2 refs.

  10. Distortions in processed signals and their application in electronic design - III: An automated generator of communication jamming signals

    International Nuclear Information System (INIS)

    Njau, E.C.

    1987-10-01

    We describe the design and operational features of a simple electronic circuit that is capable of automatically generating a narrow bandwidth jamming signal around each frequency signal received from target transmitters. It is noted that jamming based upon this circuit is fairly difficult to nullify using some of the conventional ''counter jamming'' strategies since in this case the jamming signals are flexibly locked onto the spectral components of the received signals. (author). 3 refs, 3 figs

  11. Low-level-signal data acquisition for the MFTF superconducting-magnet system

    International Nuclear Information System (INIS)

    Montoya, C.R.

    1981-01-01

    Acquisition of low level signals from sensors mounted on the superconducting yin-yang magnet in the Mirror Fusion Test Facility (MFTF) imposes very strict requirements on the magnet signal conditioning and data acquisition system. Of the various types of sensors required, thermocouples, strain gages, and voltage taps produce very low level outputs. These low level outputs must be accurately measured in the harsh environment of slowly varying magnetic fields, cryogenic temperatures, high vacuum, pulse power and 60 Hz electrical noise, possible neutron radiation, and high common mode voltage resulting from superconducting magnet quench. Successful measurements require careful attention to grounding, shielding, signal handling and processing in the data acquisition system. The magnet instrumentation system provides a means of effectively measuring both low level signals and high level signals from all types of sensors

  12. Low level signal data acquisition for the MFTF-B superconducting magnet system

    International Nuclear Information System (INIS)

    Montoya, C.R.

    1984-01-01

    Acquisition of low level signals from sensors mounted on the superconducting magnets in the Tandem Mirror Fusion Test Facility (MFTF-B) impose very strict requirements on the magnet signal conditioning and data acquisition system. Of the various types of sensors required, thermocouples and strain gages produce very low level outputs. These low level outputs must be accurately measured in the harsh environment of slowly varying magnetic fields, cryogenic temperatures, high vacuum, 80 kV pulse power, 60 Hz, 17 MHz and 28, 35, and 56 GHz electrical noise and possible neutron radiation. Successful measurements require careful attention to grounding, shielding, signal handling and processing in the data acquisition system. The magnet instrumentation system provides a means of effectively measuring both low level signals and high level signals from all types of sensors. Various methods involved in the design and implementation of the system for signal conditioning and data gathering will be presented

  13. Experimental investigation of powerful pulse current generators based on capacitive storage and explosive magnetic generators

    Science.gov (United States)

    Shurupov, A. V.; Zavalova, V. E.; Kozlov, A. V.; Shurupov, M. A.; Povareshkin, M. N.; Kozlov, A. A.; Shurupova, N. P.

    2018-01-01

    Experimental models of microsecond duration powerful generators of current pulses on the basis of explosive magnetic generators and voltage impulse generator have been developed for the electromagnetic pulse effects on energy facilities to verify their stability. Exacerbation of voltage pulse carried out through the use of electro explosive current interrupter made of copper wires with diameters of 80 and 120 μm. Experimental results of these models investigation are represented. Voltage fronts about 100 ns and the electric field strength of 800 kV/m are registered.

  14. Design and Implementation of the Permanent- Magnet Synchronous Generator Drive in Wind Generation Systems

    Directory of Open Access Journals (Sweden)

    Yuan-Chih Chang

    2018-06-01

    Full Text Available The design and implementation of the permanent-magnet synchronous generator drive in wind generation systems is presented in this paper. The permanent-magnet synchronous generator (PMSG can converse the alternating current (AC power of the wind turbine to direct current (DC power. In this paper, the dynamic model of a PMSG is first introduced. The current controller is designed based on T-S fuzzy models of the PMSG. The stability of the proposed PMSG drive system is analyzed and proved. The proposed T-S fuzzy current control possesses a disturbance suppression ability. Compared with the traditional fuzzy logic system, its stability can be proved and verified. Finally, the control performance of the PMSG drive is verified by experimental results.

  15. Novel ultra-wideband photonic signal generation and transmission featuring digital signal processing bit error rate measurements

    DEFF Research Database (Denmark)

    Gibbon, Timothy Braidwood; Yu, Xianbin; Tafur Monroy, Idelfonso

    2009-01-01

    We propose the novel generation of photonic ultra-wideband signals using an uncooled DFB laser. For the first time we experimentally demonstrate bit-for-bit DSP BER measurements for transmission of a 781.25 Mbit/s photonic UWB signal.......We propose the novel generation of photonic ultra-wideband signals using an uncooled DFB laser. For the first time we experimentally demonstrate bit-for-bit DSP BER measurements for transmission of a 781.25 Mbit/s photonic UWB signal....

  16. Control of Permanent Magnet Synchronous Generator for large wind turbines

    DEFF Research Database (Denmark)

    Busca, Cristian; Stan, Ana-Irina; Stanciu, Tiberiu

    2010-01-01

    Direct Torque Control (DTC) and Field Oriented Control (FOC) are the most dominant control strategies used in generators for wind turbines. In this paper both control methods were implemented on a Permanent Magnet Synchronous Generator (PMSG). The variable speed wind turbine with full scale power...... converter topology was chosen for design. Parameters from a 2 MW wind turbine were used for system modeling. All the components of the wind turbine system (WTS), except the DC-link and the grid site converter were implemented in MATLAB/Simulink. The pitch controller was used to limit the output power...... produced by the turbine. DTC and FOC strategies, using SVM were used to control the generator rotor speed. The performance of the two control strategies were compared after different tests have been carried out....

  17. CHROMOSPHERIC AND CORONAL WAVE GENERATION IN A MAGNETIC FLUX SHEATH

    International Nuclear Information System (INIS)

    Kato, Yoshiaki; Hansteen, Viggo; Gudiksen, Boris; Wedemeyer, Sven; Carlsson, Mats; Steiner, Oskar

    2016-01-01

    Using radiation magnetohydrodynamic simulations of the solar atmospheric layers from the upper convection zone to the lower corona, we investigate the self-consistent excitation of slow magneto-acoustic body waves (slow modes) in a magnetic flux concentration. We find that the convective downdrafts in the close surroundings of a two-dimensional flux slab “pump” the plasma inside it in the downward direction. This action produces a downflow inside the flux slab, which encompasses ever higher layers, causing an upwardly propagating rarefaction wave. The slow mode, excited by the adiabatic compression of the downflow near the optical surface, travels along the magnetic field in the upward direction at the tube speed. It develops into a shock wave at chromospheric heights, where it dissipates, lifts the transition region, and produces an offspring in the form of a compressive wave that propagates further into the corona. In the wake of downflows and propagating shock waves, the atmosphere inside the flux slab in the chromosphere and higher tends to oscillate with a period of ν ≈ 4 mHz. We conclude that this process of “magnetic pumping” is a most plausible mechanism for the direct generation of longitudinal chromospheric and coronal compressive waves within magnetic flux concentrations, and it may provide an important heat source in the chromosphere. It may also be responsible for certain types of dynamic fibrils.

  18. Permanent magnet working point ripple in synchronous generators

    Directory of Open Access Journals (Sweden)

    Stefan Sjökvist

    2017-04-01

    Full Text Available Permanent magnets (PMs are today widely used in electrical machines of all sorts. With their increase in popularity, the amount of research has increased as well. In this study, the magnetic flux density ripple of the working point of the PMs in a 100 kW PM synchronous generator has been investigated for three different load cases: no load, AC load, and DC load. The PMs will be subjected to a shift in working point as a consequence of the characteristics of the electrical loading. This study is based on finite element method simulations where the ripple of the magnetic flux density in the PMs was recorded at three positions within a PM. The slot harmonic of 7.5 times the electrical frequency (f(el was present in the results for all load cases, but mainly at the surface of the PM, as expected. Results showed an unexpected harmonic of 1.5 f(el, assumed to be an undertone of the slot harmonics. The 6f(el harmonic for the DC load case was significantly higher than for the AC load case and is caused by the current fluctuation during passive rectification. For the studied machine, the added harmonics in the magnetic field due to passive rectification are less than the slot-related harmonics.

  19. CHROMOSPHERIC AND CORONAL WAVE GENERATION IN A MAGNETIC FLUX SHEATH

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Yoshiaki; Hansteen, Viggo; Gudiksen, Boris; Wedemeyer, Sven; Carlsson, Mats [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway); Steiner, Oskar, E-mail: yoshiaki.kato@astro.uio.no [Kiepenheuer-Institut für Sonnenphysik, Schöneckstrasse 6, D-79104 Freiburg (Germany)

    2016-08-10

    Using radiation magnetohydrodynamic simulations of the solar atmospheric layers from the upper convection zone to the lower corona, we investigate the self-consistent excitation of slow magneto-acoustic body waves (slow modes) in a magnetic flux concentration. We find that the convective downdrafts in the close surroundings of a two-dimensional flux slab “pump” the plasma inside it in the downward direction. This action produces a downflow inside the flux slab, which encompasses ever higher layers, causing an upwardly propagating rarefaction wave. The slow mode, excited by the adiabatic compression of the downflow near the optical surface, travels along the magnetic field in the upward direction at the tube speed. It develops into a shock wave at chromospheric heights, where it dissipates, lifts the transition region, and produces an offspring in the form of a compressive wave that propagates further into the corona. In the wake of downflows and propagating shock waves, the atmosphere inside the flux slab in the chromosphere and higher tends to oscillate with a period of ν ≈ 4 mHz. We conclude that this process of “magnetic pumping” is a most plausible mechanism for the direct generation of longitudinal chromospheric and coronal compressive waves within magnetic flux concentrations, and it may provide an important heat source in the chromosphere. It may also be responsible for certain types of dynamic fibrils.

  20. ADMAP-2: The second generation Antarctic crustal magnetic anomaly map.

    Science.gov (United States)

    Ferraccioli, F.; Golynsky, A.; Golynsky, D.; Young, D. A.; Eagles, G.; Damaske, D.; Finn, C.; Aitken, A.; von Frese, R. R. B.; Ghidella, M. E.; Kim, H. R.; Hong, J.

    2017-12-01

    ADMAP-2 is the second generation crustal magnetic anomaly compilation for the Antarctic region south of 60°S. It was produced from more than 3.5 million line-km of near-surface terrestrial, airborne and marine magnetic observations collected since the International Geophysical Year 1957/58 through 2013. The data were edited, IGRF corrected, profile levelled and gridded at a 1.5-km interval on a polar stereographic projection using the minimum curvature technique. Given the ubiquitous polar cover of snow, ice and sea water, the magnetic anomaly compilation offers important constraints on the global tectonic processes and crustal properties of the Antarctic. It also links widely separated areas of outcrop to help unify disparate geologic studies, and provides insights on the lithospheric transition between Antarctica and adjacent oceans, as well as the geodynamic evolution of the Antarctic lithosphere in the assembly and break-up of the Gondwana, Rodinia, and Columbia supercontinents and key piercing points for reconstructing linkages between the protocontinents. The magnetic data together with ice-probing radar and gravity information greatly facilitate understanding the evolution of fundamental large-scale geological processes such as continental rifting, intraplate mountain building, subduction and terrane accretion processes, and intraplate basin formation.

  1. ADMAP-2: The next-generation Antarctic magnetic anomaly map

    Science.gov (United States)

    Golynsky, Alexander; Golynsky, Dmitry; Ferraccioli, Fausto; Jordan, Tom; Damaske, Detlef; Blankenship, Don; Holt, Jack; Young, Duncan; Ivanov, Sergey; Kiselev, Alexander; Jokat, Wilfried; Gohl, Karsten; Eagles, Graeme; Bell, Robin; Armadillo, Egidio; Bozzo, Emanuelle; Caneva, Giorgio; Finn, Carol; Forsberg, Rene; Aitken, Alan

    2017-04-01

    The Antarctic Digital Magnetic Anomaly Project compiled the first international magnetic anomaly map of the Antarctic region south of 60°S (ADMAP-1) some six years after its 1995 launch (Golynsky et al., 2001; Golynsky et al., 2007; von Frese et al., 2007). This magnetic anomaly compilation provided new insights into the structure and evolution of Antarctica, including its Proterozoic-Archaean cratons, Proterozoic-Palaeozoic orogens, Palaeozoic-Cenozoic magmatic arc systems, continental rift systems and rifted margins, large igneous provinces and the surrounding oceanic gateways. The international working group produced the ADMAP-1 database from more than 1.5 million line-kilometres of terrestrial, airborne, marine and satellite magnetic observations collected during the IGY 1957-58 through 1999. Since the publication of the first magnetic anomaly map, the international geomagnetic community has acquired more than 1.9 million line-km of new airborne and marine data. This implies that the amount of magnetic anomaly data over the Antarctic continent has more than doubled. These new data provide important constraints on the geology of the enigmatic Gamburtsev Subglacial Mountains and Prince Charles Mountains, Wilkes Land, Dronning Maud Land, and other largely unexplored Antarctic areas (Ferraccioli et al., 2011, Aitken et al., 2014¸ Mieth & Jokat, 2014, Golynsky et al., 2013). The processing of the recently acquired data involved quality assessments by careful statistical analysis of the crossover errors. All magnetic data used in the ADMAP-2 compilation were delivered as profiles, although several of them were in raw form. Some datasets were decimated or upward continued to altitudes of 4 km or higher with the higher frequency geological signals smoothed out. The line data used for the ADMAP-1 compilation were reprocessed for obvious errors and residual corrugations. The new near-surface magnetic data were corrected for the international geomagnetic reference field

  2. Review in Transverse Flux Permanent Magnet Generator Design

    Directory of Open Access Journals (Sweden)

    A. Ejlali

    2016-12-01

    Full Text Available Recently, Transverse Flux Permanent Magnet Generators (TFPMGs have been proposed as a possible generator in direct drive variable speed wind turbines due to their unique merits. Generally, the quality of output power in these systems is lower than multi stage fixed speed systems, because of removing the gears, so it’s important to design these kinds of generators with low ripple and lowest harmful harmonics and cogging torque that is one of the most important terms in increasing the quality of output power of generator. The objective of this paper is introducing a simple design method and optimization of high power TFPMG applied in vertical axis direct drive wind turbine system by lowest possible amplitude of cogging torque and highest possible power factor, efficiency and power density.  In order to extract the output values of generator and sensitivity analysis for design and optimization, 3D-Finite element model, has been used. This method has high accuracy and gives us a better insight of generator performance and presents back EMF, cogging torque, flux density and FFT of this TFPMG. This study can help designers in design approach of such motors.

  3. Arbitrary function generator for APS injector synchrotron correction magnets

    International Nuclear Information System (INIS)

    Despe, O.D.

    1991-01-01

    The APS injector synchrotron has eighty correction magnets around its circumference to provide the vernier field changes required for beam orbit correction during acceleration. The arbitrary function generator (AFG) design is based on scanning out encoded data from a semi-conductor memory, a first-in-first-out (FIFO) device. The data input consists of a maximum of 20 correction values specified within the acceleration window. Additional points between these values are then linearly interpolated to create a uniformly spaced 1000 data-point function stored in the FIFO. Each point, encoded as a 3-bit value is scanned out in synchronism with the injection pulse and used to clock the up/down counter driving the DAC. The DAC produces the analog reference voltage used to control the magnet current. 1 ref., 4 figs

  4. Z a Fast Pulsed Power Generator for Ultra-High Magnetic Field Generation

    Science.gov (United States)

    Spielman, R. B.; Stygar, W. A.; Struve, K. W.; Asay, J. R.; Hall, C. A.; Bernard, M. A.; Bailey, J. E.; McDaniel, D. H.

    2004-11-01

    Advances in fast, pulsed-power technologies have resulted in the development of very high current drivers that have current rise times ~100 ns. The largest such pulsed power driver today is the new Z accelerator located at Sandia National Laboratories in Albuquerque, New Mexico. Z can deliver more than 20 MA with a time-to-peak of 105 ns to low inductance (~1 nH) loads. Such large drivers are capable of directly generating magnetic fields approaching 3 kT in small, 1 cm3 volumes. In addition to direct field generation, Z can be used to compress an applied, axial seed field with a plasma. Flux compression schemes are not new and are, in fact, the basis of all explosive flux-compression generators, but we propose the use of plasma armatures rather than solid, conducting armatures. We present experimental results from the Z accelerator in which magnetic fields of ~2 kT are generated and measured with several diagnostics. Issues such as energy loss in solid conductors and dynamic response of current-carrying conductors to very large magnetic fields are reviewed in context with Z experiments. We describe planned flux-compression experiments that are expected to create the highest-magnitude uniform-field volumes yet attained in the laboratory.

  5. Wavelet-Based Signal Processing of Electromagnetic Pulse Generated Waveforms

    National Research Council Canada - National Science Library

    Ardolino, Richard S

    2007-01-01

    This thesis investigated and compared alternative signal processing techniques that used wavelet-based methods instead of traditional frequency domain methods for processing measured electromagnetic pulse (EMP) waveforms...

  6. Magnetic field generation during intense laser channelling in underdense plasma

    Energy Technology Data Exchange (ETDEWEB)

    Smyth, A. G.; Sarri, G.; Doria, D.; Kar, S.; Borghesi, M. [School of Mathematics and Physics, The Queen' s University of Belfast, University Road, Belfast BT7 1NN (United Kingdom); Vranic, M.; Guillaume, E.; Silva, L. O.; Vieira, J. [GoLP/IPFN, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon (Portugal); Amano, Y.; Habara, H.; Tanaka, K. A. [Graduate School of Engineering Osaka University. Suita, Osaka 5650871 (Japan); Heathcote, R.; Norreys, P. A. [STFC Rutherford Appleton Laboratory, Didcot, Oxon OX1 0Qx (United Kingdom); Hicks, G.; Najmudin, Z.; Nakamura, H. [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BZ (United Kingdom)

    2016-06-15

    Channel formation during the propagation of a high-energy (120 J) and long duration (30 ps) laser pulse through an underdense deuterium plasma has been spatially and temporally resolved via means of a proton imaging technique, with intrinsic resolutions of a few μm and a few ps, respectively. Conclusive proof is provided that strong azimuthally symmetric magnetic fields with a strength of around 0.5 MG are created inside the channel, consistent with the generation of a collimated beam of relativistic electrons. The inferred electron beam characteristics may have implications for the cone-free fast-ignition scheme of inertial confinement fusion.

  7. Optical third harmonic generation in the magnetic semiconductor EuSe

    Science.gov (United States)

    Lafrentz, M.; Brunne, D.; Kaminski, B.; Pavlov, V. V.; Pisarev, R. V.; Henriques, A. B.; Yakovlev, D. R.; Springholz, G.; Bauer, G.; Bayer, M.

    2012-01-01

    Third harmonic generation (THG) has been studied in europium selenide EuSe in the vicinity of the band gap at 2.1-2.6 eV and at higher energies up to 3.7 eV. EuSe is a magnetic semiconductor crystalizing in centrosymmetric structure of rock-salt type with the point group m3m. For this symmetry the crystallographic and magnetic-field-induced THG nonlinearities are allowed in the electric-dipole approximation. Using temperature, magnetic field, and rotational anisotropy measurements, the crystallographic and magnetic-field-induced contributions to THG were unambiguously separated. Strong resonant magnetic-field-induced THG signals were measured at energies in the range of 2.1-2.6 eV and 3.1-3.6 eV for which we assign to transitions from 4f7 to 4f65d1 bands, namely involving 5d(t2g) and 5d(eg) states.

  8. Design of High Performance Permanent-Magnet Synchronous Wind Generators

    Directory of Open Access Journals (Sweden)

    Chun-Yu Hsiao

    2014-11-01

    Full Text Available This paper is devoted to the analysis and design of high performance permanent-magnet synchronous wind generators (PSWGs. A systematic and sequential methodology for the design of PMSGs is proposed with a high performance wind generator as a design model. Aiming at high induced voltage, low harmonic distortion as well as high generator efficiency, optimal generator parameters such as pole-arc to pole-pitch ratio and stator-slot-shoes dimension, etc. are determined with the proposed technique using Maxwell 2-D, Matlab software and the Taguchi method. The proposed double three-phase and six-phase winding configurations, which consist of six windings in the stator, can provide evenly distributed current for versatile applications regarding the voltage and current demands for practical consideration. Specifically, windings are connected in series to increase the output voltage at low wind speed, and in parallel during high wind speed to generate electricity even when either one winding fails, thereby enhancing the reliability as well. A PMSG is designed and implemented based on the proposed method. When the simulation is performed with a 6 Ω load, the output power for the double three-phase winding and six-phase winding are correspondingly 10.64 and 11.13 kW. In addition, 24 Ω load experiments show that the efficiencies of double three-phase winding and six-phase winding are 96.56% and 98.54%, respectively, verifying the proposed high performance operation.

  9. Analysis of Voltage Signals from Superconducting Accelerator Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Lizarazo, J.; Caspi, S.; Ferracin, P.; Joseph, J.; Lietzke, A. F.; Sabbi, G. L.; Wang, X.

    2009-10-30

    We present two techniques used in the analysis of voltage tap data collected during recent tests of superconducting magnets developed by the Superconducting Magnet Program at Lawrence Berkeley National Laboratory. The first technique was used on a quadrupole to provide information about quench origins that could not be obtained using the time-of-flight method. The second technique illustrates the use of data from transient flux imbalances occurring during magnet ramping to diagnose changes in the current-temperature margin of a superconducting cable. In both cases, the results of this analysis contributed to make improvements on subsequent magnets.

  10. Generation of strong pulsed magnetic fields using a compact, short pulse generator

    Science.gov (United States)

    Yanuka, D.; Efimov, S.; Nitishinskiy, M.; Rososhek, A.; Krasik, Ya. E.

    2016-04-01

    The generation of strong magnetic fields (˜50 T) using single- or multi-turn coils immersed in water was studied. A pulse generator with stored energy of ˜3.6 kJ, discharge current amplitude of ˜220 kA, and rise time of ˜1.5 μs was used in these experiments. Using the advantage of water that it has a large Verdet constant, the magnetic field was measured using the non-disturbing method of Faraday rotation of a polarized collimated laser beam. This approach does not require the use of magnetic probes, which are sensitive to electromagnetic noise and damaged in each shot. It also avoids the possible formation of plasma by either a flashover along the conductor or gas breakdown inside the coil caused by an induced electric field. In addition, it was shown that this approach can be used successfully to investigate the interesting phenomenon of magnetic field enhanced diffusion into a conductor.

  11. Optimization of Multibrid Permanent-Magnet Wind Generator Systems

    DEFF Research Database (Denmark)

    Chen, Zhe; Li, H.; Polinder, H.

    2009-01-01

    and multibrid wind turbine configurations are obtained, and the suitable ranges of gear ratios for different power ratings are investigated. Finally, the detailed comparisons of themost cost-effective multibridPMgenerator system and the optimized direct-drive PM generator system are also presented and discussed....... The comparative results have shown that the multibrid wind turbine concept appears more cost-effective than the direct-drive concept.......This paper investigates the cost-effective ranges of gearbox ratios and power ratings of multibrid permanent-magnet (PM) wind generator systems by using a design optimization method. First, the analytical model of a multibrid wind turbine concept consisting of a single-stage gearbox and a three...

  12. Particle Acceleration, Magnetic Field Generation and Emission from Relativistic Jets

    Science.gov (United States)

    Nishikawa, K.-I.; Hardee, P.; Hededal, C.; Mizuno, Yosuke; Fishman, G. Jerry; Hartmann, D. H.

    2006-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), supernova remnants, and Galactic microquasar systems usually have power-law emission spectra. Fermi acceleration is the mechanism usually assumed for the acceleration of particles in astrophysical environments. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that particle acceleration occurs within the downstream jet, rather than by the scattering of particles back and forth across the shock as in Fermi acceleration. Shock acceleration' is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different spectral properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. We will review recent PIC simulations of relativistic jets and try to make a connection with observations.

  13. Comparison of superconducting generators and permanent magnet generators for 10-MW direct-drive wind turbines

    DEFF Research Database (Denmark)

    Liu, Dong; Polinder, Henk; Abrahamsen, Asger Bech

    2016-01-01

    Large offshore direct-drive wind turbines of 10-MW power levels are being extensively proposed and studied because of a reduced cost of energy. Conventional permanent magnet generators currently dominating the direct-drive wind turbine market are still under consideration for such large wind...... turbines. In the meantime, superconducting generators (SCSGs) have been of particular interest to become a significant competitor because of their compactness and light weight. This paper compares the performance indicators of these two direct-drive generator types in the same 10-MW wind turbine under...... the same design and optimization method. Such comparisons will be interesting and insightful for commercialization of superconducting generators and for development of future wind energy industry, although SCSGs are still far from a high technology readiness level. The results show that the SCSGs may...

  14. Novel attempt to create uniform magnetic-field space generated by face-to-face settled HTS bulk magnets

    International Nuclear Information System (INIS)

    Oka, Tetsuo; Ichiju, Kana; Higa, Kazuya; Fukui, Satoshi; Ogawa, Jun; Sato, Takao; Yokoyama, Kazuya; Nakamura, Takashi

    2017-01-01

    Various experimental attempts have been made to obtain a uniform magnetic field in the space between face-to-face HTS bulk magnets that could possibly be utilized as NMR magnets. In general, the magnetic fields emitted from the magnetic pole surfaces containing HTS bulk magnets are characterized as non-uniform field distributions. Since the NMR magnets require highly uniform magnetic-field spaces, it has been assumed to be difficult to form uniform magnetic-field spaces between magnetic poles placed face-to-face. The authors modified the shapes of the magnetic-field distribution from convex to concave by attaching ferromagnetic iron plates to the pole surfaces. The magnets were then set face-to-face with various gaps of 30-70 mm, and the experimental data on magnetic-field uniformity was precisely measured in the space. In order to detect the NMR signals, the target performance for uniformity was set as 1,500 ppm throughout the 4-mm span on the x-axis, which is equivalent to performance in the past when the world's first detection of NMR signals was observed in the bore of hollow-type HTS bulk magnets. When we combined the concave and convex field distributions to compensate the uneven field distributions, the data of the best uniformity reached 358 ppm and 493 ppm in the 30 mm and 50 mm gaps, respectively, which exceeded the target value for the purpose of detecting the NMR signals within the space. Furthermore, it was shown that the field distributions change from concave to convex shape without any change at 1.1 T in the range from 7 to 11 mm in the 30-mm gap, indicating that the distributions are uniform. This suggests the possibility that the uniform magnetic-field space between the HTS bulk magnets set face-to-face expands. (author)

  15. A battery-operated pilot balloon time-signal generator

    Science.gov (United States)

    Ralph H. Moltzau

    1966-01-01

    Describes the design and construction of a 1-pound, battery-operated, time-signal transmitter, which is usable with portable radio or field telephone circuits for synchronizing multi-theodolite observation of pilot balloons.

  16. THEORY OF SIGNAL GENERATION IN A PHOTOACOUSTIC CELL

    OpenAIRE

    Bein , B.; Pelzl , J.

    1983-01-01

    Based on the fundamental physical equations governing the dynamical behaviour of a gas, the pressure signal is derived for a gas-filled photoacoustic cell in contact with a radiation-heated solid sample.

  17. Detection of magnetic resonance signals using a magnetoresistive sensor

    Science.gov (United States)

    Budker, Dmitry; Pines, Alexander; Xu, Shoujun; Hilty, Christian; Ledbetter, Micah P; Bouchard, Louis S

    2013-10-01

    A method and apparatus are described wherein a micro sample of a fluidic material may be assayed without sample contamination using NMR techniques, in combination with magnetoresistive sensors. The fluidic material to be assayed is first subject to pre-polarization, in one embodiment, by passage through a magnetic field. The magnetization of the fluidic material is then subject to an encoding process, in one embodiment an rf-induced inversion by passage through an adiabatic fast-passage module. Thereafter, the changes in magnetization are detected by a pair of solid-state magnetoresistive sensors arranged in gradiometer mode. Miniaturization is afforded by the close spacing of the various modules.

  18. Proton magnetic resonance with parahydrogen induced polarization. Imaging strategies and continuous generation

    Energy Technology Data Exchange (ETDEWEB)

    Dechent, Jan Falk Frederik

    2012-12-17

    A major challenge in imaging is the detection of small amounts of molecules of interest. In the case of magnetic resonance imaging (MRI) their signals are typically concealed by the large background signal of e.g. the tissue of the body. This problem can be tackled by hyperpolarization which increases the NMR signals up to several orders of magnitude. However, this strategy is limited for {sup 1}H, the most widely used nucleus in NMR and MRI, because the enormous number of protons in the body screen the small amount of hyperpolarized ones. Here, I describe a method giving rise to high {sup 1}H MRI contrast for hyperpolarized molecules against a large background signal. The contrast is based on the J-coupling induced rephasing of the NMR signal of molecules hyperpolarized via parahydrogen induce polarization (PHIP) and it can easily be implemented in common pulse sequences. Hyperpolarization methods typically require expensive technical equipment (e.g. lasers or microwaves) and most techniques work only in batch mode, thus the limited lifetime of the hyperpolarization is limiting its applications. Therefore, the second part of my thesis deals with the simple and efficient generation of an hyperpolarization. These two achievements open up alternative opportunities to use the standard MRI nucleus {sup 1}H for e.g. metabolic imaging in the future.

  19. Proton magnetic resonance with parahydrogen induced polarization. Imaging strategies and continuous generation

    International Nuclear Information System (INIS)

    Dechent, Jan Falk Frederik

    2012-01-01

    A major challenge in imaging is the detection of small amounts of molecules of interest. In the case of magnetic resonance imaging (MRI) their signals are typically concealed by the large background signal of e.g. the tissue of the body. This problem can be tackled by hyperpolarization which increases the NMR signals up to several orders of magnitude. However, this strategy is limited for 1 H, the most widely used nucleus in NMR and MRI, because the enormous number of protons in the body screen the small amount of hyperpolarized ones. Here, I describe a method giving rise to high 1 H MRI contrast for hyperpolarized molecules against a large background signal. The contrast is based on the J-coupling induced rephasing of the NMR signal of molecules hyperpolarized via parahydrogen induce polarization (PHIP) and it can easily be implemented in common pulse sequences. Hyperpolarization methods typically require expensive technical equipment (e.g. lasers or microwaves) and most techniques work only in batch mode, thus the limited lifetime of the hyperpolarization is limiting its applications. Therefore, the second part of my thesis deals with the simple and efficient generation of an hyperpolarization. These two achievements open up alternative opportunities to use the standard MRI nucleus 1 H for e.g. metabolic imaging in the future.

  20. Concentrated Windings in Compact Permanent Magnet Synchronous Generators: Managing Efficiency

    Directory of Open Access Journals (Sweden)

    Olivier Barré

    2016-01-01

    Full Text Available In electric power generation, customers want generators with high efficiency. Nowadays, modern turbo-generators have efficiencies greater than 98%. Although this amount should not be obtained for all kind of machines, efficiency will remain one of the main parameters for customer choice. Efficiency is also linked to the life of the machine: the higher the efficiency is, the longer the machine’s lifetime. During the past decade, new forms of energy production have appeared and generators have been developed to fit well into this market. For example, wind generators evolved towards permanent magnet generators having high polarity and running at low speed. Nevertheless, their structure is not fixed. An industrial company has built a prototype of such a generator which uses fractional-slot concentrated-windings (FSCW. This kind of winding is not the structure used by default in such electrical machines. Another field of interest is in autonomous generators which can be used on boats. Even if everyone has in mind large merchant ships, we must not forget smaller ships, such as fishing boats and short-range cruise ships, which spend the most of their time near the coast. This kind of ship does nothave large areas for installing the electric generation or the electric propulsion. It is the reason why, in this article, we focus on the efficiency of machines using fractional-slot concentrated-windings. In many publications which compare performances between distributed and concentrated windings, the result is almost the same. The efficiency of FSCW is not as high as the efficiency associated to the machines which are using distributed windings. Design methods have to be redrawn to integrate, as soon as possible, the loss mitigation in order to provide the best efficiency in power conversion. The following discussion, step by step, introduces the loss mitigation in every part of a machine using FSCW. To close the discussion, a design is produced and it

  1. Electron Cloud Generation and Trapping in a Quadrupole Magnet at the Los Alamos Proton Storage Ring

    International Nuclear Information System (INIS)

    Macek, Robert J.; Browman, Andrew A.; Ledford, John E.; TechSource, Santa Fe; Los Alamos; Borden, Michael J.; O'Hara, James F.; McCrady, Rodney C.; Rybarcyk, Lawrence J.; Spickermann, Thomas; Zaugg, Thomas J.; Pivi, Mauro T.F.

    2008-01-01

    Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR) have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the 'prompt' electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the 'swept' electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100 (micro)s. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the quadrupole

  2. Electron cloud generation and trapping in a quadrupole magnet at the Los Alamos proton storage ring

    Directory of Open Access Journals (Sweden)

    Robert J. Macek

    2008-01-01

    Full Text Available Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the “prompt” electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the “swept” electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100  μs. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the quadrupole.

  3. Ocean tidal signals in observatory and satellite magnetic measurements

    DEFF Research Database (Denmark)

    Maus, S.; Kuvshinov, A.

    2004-01-01

    , and P1 periods turn out to be dominated by unrelated external fields. In contrast, observed lunar M2 and N2 tidal signals are in fair agreement with predictions from motional induction. The lunar diurnal O1 signal, visible at some observatories, could be caused by ocean flow but disagrees in amplitude...

  4. Isolated Power Generation System Using Permanent Magnet Synchronous Generator with Improved Power Quality

    Science.gov (United States)

    Arya, Sabha Raj; Patel, Ashish; Giri, Ashutosh

    2018-03-01

    This paper deals wind energy based power generation system using Permanent Magnet Synchronous Generator (PMSG). It is controlled using advanced enhanced phase-lock loop for power quality features using distribution static compensator to eliminate the harmonics and to provide KVAR compensation as well as load balancing. It also manages rated potential at the point of common interface under linear and non-linear loads. In order to have better efficiency and reliable operation of PMSG driven by wind turbine, it is necessary to analyze the governing equation of wind based turbine and PMSG under fixed and variable wind speed. For handling power quality problems, power electronics based shunt connected custom power device is used in three wire system. The simulations in MATLAB/Simulink environment have been carried out in order to demonstrate this model and control approach used for the power quality enhancement. The performance results show the adequate performance of PMSG based power generation system and control algorithm.

  5. Analysis of a 3-phase tubular permanent magnet linear generator

    Energy Technology Data Exchange (ETDEWEB)

    Nor, K.M.; Arof, H.; Wijono [Malaya Univ., Kuala Lumpur (Malaysia). Faculty of Engineering

    2005-07-01

    A 3-phase tubular permanent linear generator design was described. The generator was designed to be driven by a single or a double 2-stroke combustion linear engine. Combustion took place alternately between 2 opposed chambers. In the single combustion engine, one of the combustion chambers was replaced by a kickback mechanism. The force on the translator generated by the explosion in the combustion chamber was used to compress the air in the kickback chamber. The pressed air was then used to release the stored energy to push back the translator in the opposite direction. The generator was modelled as a 2D object. A parametric simulation was performed to give a series of discrete data required to calculate machine electrical parameters; flux distribution; coil flux linkage; and, cogging force. Fringing flux was evaluated through the application of a magnetic boundary condition. The infinity boundary was used to include the zero electromagnetic potential in the surface boundary. A complete simulation was run for each step of the translator's motion, which was considered as sinusoidal. The simplification was further corrected using the real engine speed curve. The EMF was derived from the flux linkage difference in the coils at every consecutive translator position. Force was calculated in the translator and stator using a virtual work method. Optimization was performed using a subproblem strategy. It was concluded that the generator can be used to supply electric power as a stand-alone system, emergency power supply, or as part of an integrated system. 11 refs., 2 tabs., 10 figs.

  6. Compact biomedical pulsed signal generator for bone tissue stimulation

    Science.gov (United States)

    Kronberg, James W.

    1993-01-01

    An apparatus for stimulating bone tissue for stimulating bone growth or treating osteoporosis by applying directly to the skin of the patient an alternating current electrical signal comprising wave forms known to simulate the piezoelectric constituents in bone. The apparatus may, by moving a switch, stimulate bone growth or treat osteoporosis, as desired. Based on low-power CMOS technology and enclosed in a moisture-resistant case shaped to fit comfortably, two astable multivibrators produce the desired waveforms. The amplitude, pulse width and pulse frequency, and the subpulse width and subpulse frequency of the waveforms are adjustable. The apparatus, preferably powered by a standard 9-volt battery, includes signal amplitude sensors and warning signals indicate an output is being produced and the battery needs to be replaced.

  7. Nuclear magnetic relaxation and origins of RMN signals from GdAl2

    International Nuclear Information System (INIS)

    Santos Oliveira Junior, I. dos.

    1988-12-01

    The intermetallic compound GdAl 2 crystallizes in the cubic Laves phase C15. It is a simple ferromagnet below 176K. The easy direction of magnetization in this compound is such that the Al ions are distributed among two magnetically inequivalent sites. The pulsed NMR technique was used to study the origin of the signals from these two sites and the nuclear magnetic relaxation. (author) [pt

  8. Fast dictionary generation and searching for magnetic resonance fingerprinting.

    Science.gov (United States)

    Jun Xie; Mengye Lyu; Jian Zhang; Hui, Edward S; Wu, Ed X; Ze Wang

    2017-07-01

    A super-fast dictionary generation and searching (DGS) algorithm was developed for MR parameter quantification using magnetic resonance fingerprinting (MRF). MRF is a new technique for simultaneously quantifying multiple MR parameters using one temporally resolved MR scan. But it has a multiplicative computation complexity, resulting in a big burden of dictionary generating, saving, and retrieving, which can easily be intractable for any state-of-art computers. Based on retrospective analysis of the dictionary matching object function, a multi-scale ZOOM like DGS algorithm, dubbed as MRF-ZOOM, was proposed. MRF ZOOM is quasi-parameter-separable so the multiplicative computation complexity is broken into additive one. Evaluations showed that MRF ZOOM was hundreds or thousands of times faster than the original MRF parameter quantification method even without counting the dictionary generation time in. Using real data, it yielded nearly the same results as produced by the original method. MRF ZOOM provides a super-fast solution for MR parameter quantification.

  9. Design considerations for permanent magnet direct drive generators for wind energy applications

    NARCIS (Netherlands)

    Jassal, A.K.; Polinder, H.; Damen, M.E.C.; Versteegh, K.

    2012-01-01

    Permanent Magnet Direct Drive (PMDD) generators offer very high force density, high efficiency and low number of components. Due to these advantages, PMDD generators are getting popular in the wind energy industry especially for offshore application. Presence of permanent magnets gives magnetic

  10. The use of mirror image symmetry in coil winding, applications and advantages in magnetic field generation

    International Nuclear Information System (INIS)

    Grotz, T.

    1992-01-01

    In this paper, an improved method of winding inductors, transformers and motors is discovered. This invention greatly enhances the ability to generate magnetic fields with a given amount of wire. This invention may be as fundamental to the use of magnetic fields as was Nikola Tesla's use of rotating magnetic fields for the generation of alternating current

  11. Fast electron generation and transport in a turbulent, magnetized plasma

    International Nuclear Information System (INIS)

    Stoneking, W.R.

    1994-05-01

    The nature of fast electron generation and transport in the Madison Symmetric Torus (MST) reversed field pinch (RFP) is investigated using two electron energy analyzer (EEA) probes and a thermocouple calorimeter. The parallel velocity distribution of the fast electron population is well fit by a drifted Maxwellian distribution with temperature of about 100 eV and drift velocity of about 2 x 10 6 m/s. Cross-calibration of the EEA with the calorimeter provides a measurement of the fast electron perpendicular temperature of 30 eV, much lower than the parallel temperature, and is evidence that the kinetic dynamo mechanism (KDT) is not operative in MST. The fast electron current is found to match to the parallel current at the edge, and the fast electron density is about 4 x 10 11 cm -3 independent of the ratio of the applied toroidal electric field to the critical electric field for runaways. First time measurements of magnetic fluctuation induced particle transport are reported. By correlating electron current fluctuations with radial magnetic fluctuations the transported flux of electrons is found to be negligible outside r/a∼0.9, but rises the level of the expected total particle losses inside r/a∼0.85. A comparison of the measured diffusion coefficient is made with the ausilinear stochastic diffusion coefficient. Evidence exists that the reduction of the transport is due to the presence of a radial ambipolar electric field of magnitude 500 V/m, that acts to equilibrate the ion and electron transport rates. The convective energy transport associated with the measured particle transport is large enough to account for the observed magnetic fluctuation induced energy transport in MST

  12. Practical methods for generating alternating magnetic fields for biomedical research

    Science.gov (United States)

    Christiansen, Michael G.; Howe, Christina M.; Bono, David C.; Perreault, David J.; Anikeeva, Polina

    2017-08-01

    Alternating magnetic fields (AMFs) cause magnetic nanoparticles (MNPs) to dissipate heat while leaving surrounding tissue unharmed, a mechanism that serves as the basis for a variety of emerging biomedical technologies. Unfortunately, the challenges and costs of developing experimental setups commonly used to produce AMFs with suitable field amplitudes and frequencies present a barrier to researchers. This paper first presents a simple, cost-effective, and robust alternative for small AMF working volumes that uses soft ferromagnetic cores to focus the flux into a gap. As the experimental length scale increases to accommodate animal models (working volumes of 100s of cm3 or greater), poor thermal conductivity and volumetrically scaled core losses render that strategy ineffective. Comparatively feasible strategies for these larger volumes instead use low loss resonant tank circuits to generate circulating currents of 1 kA or greater in order to produce the comparable field amplitudes. These principles can be extended to the problem of identifying practical routes for scaling AMF setups to humans, an infrequently acknowledged challenge that influences the extent to which many applications of MNPs may ever become clinically relevant.

  13. Mercury's thermal history and the generation of its magnetic field

    International Nuclear Information System (INIS)

    Schubert, G.; Ross, M.N.; Stevenson, D.J.; Spohn, T.

    1988-01-01

    Thermal history of Mercury's interior is examined using the model of Stevenson et al. (1983), extended to include the effects of tidal heating in Mercury's solid inner core. The implications of Mercury's thermal history for the source of the planet's magnetic field are discussed. It is shown that the major results of this model are similar to the results obtained with the Stevenson et al. model, except for the addition of inner-core tidal dissipation. It is concluded that the extended model properly characterizes Mercury's internal structure and thermal history, and that the criteria for dynamo generation are not properly satisfied. Alternative explanations, including the possibility of a weak thermoelectric dynamo, are examined

  14. Structural looseness investigation in slow rotating permanent magnet generators

    DEFF Research Database (Denmark)

    Skrimpas, Georgios Alexandros; Mijatovic, Nenad; Sweeney, Christian Walsted

    2016-01-01

    Structural looseness in electric machines is a condition influencing the alignment of the machine and thus the overall bearing health. In this work, assessment of the above mentioned failure mode is tested on a slow rotating (running speed equal to 0.7Hz) permanent magnet generator (PMG), while...... collecting vibration and current data in order to cross-reference the indications from the two monitoring techniques. It is found that electric signature analysis shows no response even when two hold down bolts are untightened, whereas the analysis results from the vibration data exhibit superior performance....... The vibration-based condition indicators with the best response are the stator slot pass frequency, which can be directly related to the cogging torque in PMGs, and the 4th electric frequency harmonic, whose amplitudes increase due to the overall lower structure damping coefficient under looseness...

  15. Exploring on the Sensitivity Changes of the LC Resonance Magnetic Sensors Affected by Superposed Ringing Signals.

    Science.gov (United States)

    Lin, Tingting; Zhou, Kun; Yu, Sijia; Wang, Pengfei; Wan, Ling; Zhao, Jing

    2018-04-25

    LC resonance magnetic sensors are widely used in low-field nuclear magnetic resonance (LF-NMR) and surface nuclear magnetic resonance (SNMR) due to their high sensitivity, low cost and simple design. In magnetically shielded rooms, LC resonance magnetic sensors can exhibit sensitivities at the fT/√Hz level in the kHz range. However, since the equivalent magnetic field noise of this type of sensor is greatly affected by the environment, weak signals are often submerged in practical applications, resulting in relatively low signal-to-noise ratios (SNRs). To determine why noise increases in unshielded environments, we analysed the noise levels of an LC resonance magnetic sensor ( L ≠ 0) and a Hall sensor ( L ≈ 0) in different environments. The experiments and simulations indicated that the superposed ringing of the LC resonance magnetic sensors led to the observed increase in white noise level caused by environmental interference. Nevertheless, ringing is an inherent characteristic of LC resonance magnetic sensors. It cannot be eliminated when environmental interference exists. In response to this problem, we proposed a method that uses matching resistors with various values to adjust the quality factor Q of the LC resonance magnetic sensor in different measurement environments to obtain the best sensitivity. The LF-NMR experiment in the laboratory showed that the SNR is improved significantly when the LC resonance magnetic sensor with the best sensitivity is selected for signal acquisition in the light of the test environment. (When the matching resistance is 10 kΩ, the SNR is 3.46 times that of 510 Ω). This study improves LC resonance magnetic sensors for nuclear magnetic resonance (NMR) detection in a variety of environments.

  16. High-speed ultra-wideband wireless signals over fiber systems: photonic generation and DSP detection

    DEFF Research Database (Denmark)

    Yu, Xianbin; Gibbon, Timothy Braidwood; Tafur Monroy, Idelfonso

    2009-01-01

    We firstly review the efforts in the literature on ultra-wideband (UWB)-over-fiber systems. Secondly, we present experimental results on photonic generation of high-speed UWB signals by both direct modulation and external optical injecting an uncooled semiconductor laser. Furthermore, we introduce...... the use of digital signal processing (DSP) technology to receive the generated UWB signal at 781.25 Mbit/s. Error-free transmission is achieved....

  17. Design and analysis of permanent magnet moving coil type generator used in a micro-CHP generation system

    Science.gov (United States)

    Oros Pop, Susana Teodora; Berinde, Ioan; Vadan, Ioan

    2015-12-01

    This paper presents the design and analysis of a permanent magnet moving coil type generator driven by a free piston Stirling engine. This assemble free piston Stirling engine - permanent magnet moving coil type generator will be used in a combined heat and power (CHP) system for producing heat and power in residential area. The design procedure for moving coil type linear generator starts from the rated power imposed and finally uses the Faraday law of induction. The magneto-static magnetic field generated by permanent magnets is analyzed by means of Reluctance method and Finite Element Method in order to evaluate the magnetic flux density in the air gap, which is a design data imposed in the design stage, and the results are compared.

  18. Magnetic Generation due to Mass Difference between Charge Carriers

    OpenAIRE

    Chen, Shi; Dan, JiaKun; Chen, ZiYu; Li, JianFeng

    2013-01-01

    The possibility of spontaneous magnetization due to the "asymmetry in mass" of charge carriers in a system is investigated. Analysis shows that when the masses of positive and negative charge carriers are identical, no magnetization is predicted. However, if the masses of two species are different, spontaneous magnetic field would appear, either due to the equipartition of magnetic energy or due to fluctuations together with a feedback mechanism. The conditions for magnetization to occur are ...

  19. Magnetogenetics: Remote Control of Cellular Signaling with Magnetic Fields

    Science.gov (United States)

    Sauer, Jeremy P.

    Means for temporally regulating gene expression and cellular activity are invaluable for elucidating the underlying physiological processes and have therapeutic implications. Here we report the development of a system for remote regulation of gene expression by low frequency radiowaves (RF) or by a static magnetic field. We accomplished this by first adding iron oxide nanoparticles - either exogenously or as genetically encoded ferritin/ferric oxyhydroxide particle. These particles have been designed with affinity to the plasma membrane ion channel Transient Receptor Potential Vanilloid 1 (TRPV1) by a conjugated antibody. Application of a magnetic field stimulates the particle to gate the ion channel and this, in turn, initiates calcium-dependent transgene expression. We first demonstrated in vitro that TRPV1 can be actuated to cause calcium flux into the cell by directly applying a localized magnetic field. In mice expressing these genetically encoded components, application of external magnetic field caused remote stimulation of insulin transgene expression and significantly lowered blood glucose. In addition, we are investigating mechanisms by which iron oxide nanoparticles can absorb RF, and transduce this energy to cause channel opening. This robust, repeatable method for remote cellular regulation in vivo may ultimately have applications in basic science, as well as in technology and therapeutics.

  20. Low pressure arc discharge lamp apparatus with magnetic field generating means

    Science.gov (United States)

    Grossman, Mark W.; George, William A.; Maya, Jakob

    1987-01-01

    A low-pressure arc discharge apparatus having a magnetic field generating means for increasing the output of a discharge lamp is disclosed. The magnetic field generating means, which in one embodiment includes a plurality of permanent magnets, is disposed along the lamp for applying a constant transverse magnetic field over at least a portion of the positive discharge column produced in the arc discharge lamp operating at an ambient temperature greater than about 25.degree. C.

  1. Low pressure arc discharge lamp apparatus with magnetic field generating means

    Science.gov (United States)

    Grossman, M.W.; George, W.A.; Maya, J.

    1987-10-06

    A low-pressure arc discharge apparatus having a magnetic field generating means for increasing the output of a discharge lamp is disclosed. The magnetic field generating means, which in one embodiment includes a plurality of permanent magnets, is disposed along the lamp for applying a constant transverse magnetic field over at least a portion of the positive discharge column produced in the arc discharge lamp operating at an ambient temperature greater than about 25 C. 3 figs.

  2. Waves generated in the plasma plume of helicon magnetic nozzle

    International Nuclear Information System (INIS)

    Singh, Nagendra; Rao, Sathyanarayan; Ranganath, Praveen

    2013-01-01

    Experimental measurements have shown that the plasma plume created in a helicon plasma device contains a conical structure in the plasma density and a U-shaped double layer (US-DL) tightly confined near the throat where plasma begins to expand from the source. Recently reported two-dimensional particle-in-cell simulations verified these density and US-DL features of the plasma plume. Simulations also showed that the plasma in the plume develops non-thermal feature consisting of radial ion beams with large densities near the conical surface of the density structure. The plasma waves that are generated by the radial ion beams affecting the structure of the plasma plume are studied here. We find that most intense waves persist in the high-density regions of the conical density structure, where the transversely accelerated ions in the radial electric fields in the plume are reflected setting up counter-streaming. The waves generated are primarily ion Bernstein modes. The nonlinear evolution of the waves leads to magnetic field-aligned striations in the fields and the plasma near the conical surface of the density structure.

  3. Waves generated in the plasma plume of helicon magnetic nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Nagendra; Rao, Sathyanarayan; Ranganath, Praveen [Department of Electrical and Computer Engineering, University of Alabama, Huntsville, Alabama 35899 (United States)

    2013-03-15

    Experimental measurements have shown that the plasma plume created in a helicon plasma device contains a conical structure in the plasma density and a U-shaped double layer (US-DL) tightly confined near the throat where plasma begins to expand from the source. Recently reported two-dimensional particle-in-cell simulations verified these density and US-DL features of the plasma plume. Simulations also showed that the plasma in the plume develops non-thermal feature consisting of radial ion beams with large densities near the conical surface of the density structure. The plasma waves that are generated by the radial ion beams affecting the structure of the plasma plume are studied here. We find that most intense waves persist in the high-density regions of the conical density structure, where the transversely accelerated ions in the radial electric fields in the plume are reflected setting up counter-streaming. The waves generated are primarily ion Bernstein modes. The nonlinear evolution of the waves leads to magnetic field-aligned striations in the fields and the plasma near the conical surface of the density structure.

  4. Can We Probe the Conductivity of the Lithosphere and Upper Mantle Using Satellite Tidal Magnetic Signals?

    Science.gov (United States)

    Schnepf, N. R.; Kuvshinov, A.; Sabaka, T.

    2015-01-01

    A few studies convincingly demonstrated that the magnetic fields induced by the lunar semidiurnal (M2) ocean flow can be identified in satellite observations. This result encourages using M2 satellite magnetic data to constrain subsurface electrical conductivity in oceanic regions. Traditional satellite-based induction studies using signals of magnetospheric origin are mostly sensitive to conducting structures because of the inductive coupling between primary and induced sources. In contrast, galvanic coupling from the oceanic tidal signal allows for studying less conductive, shallower structures. We perform global 3-D electromagnetic numerical simulations to investigate the sensitivity of M2 signals to conductivity distributions at different depths. The results of our sensitivity analysis suggest it will be promising to use M2 oceanic signals detected at satellite altitude for probing lithospheric and upper mantle conductivity. Our simulations also suggest that M2 seafloor electric and magnetic field data may provide complementary details to better constrain lithospheric conductivity.

  5. Effect of Dimension and Shape of Magnet on the Performance AC Generator with Translation Motion

    Science.gov (United States)

    Indriani, A.; Dimas, S.; Hendra

    2018-02-01

    The development of power plants using the renewable energy sources is very rapid. Renewable energy sources used solar energy, wind energy, ocean wave energy and other energy. All of these renewable energy sources require a processing device or a change of motion system to become electrical energy. One processing device is a generator which have work principle of converting motion (mechanical) energy into electrical energy with rotary shaft, blade and other motion components. Generator consists of several types of rotation motion and linear motion (translational). The generator have components such as rotor, stator and anchor. In the rotor and stator having magnet and winding coil as an electric generating part of the electric motion force. Working principle of AC generator with linear motion (translation) also apply the principle of Faraday that is using magnetic induction which change iron magnet to produce magnetic flux. Magnetic flux is captured by the stator to be converted into electrical energy. Linear motion generators consist of linear induction machine, wound synchronous machine field, and permanent magnet synchronous [1]. Performance of synchronous generator of translation motion is influenced by magnet type, magnetic shape, coil winding, magnetic and coil spacing and others. In this paper focus on the neodymium magnet with varying shapes, number of coil windings and gap of magnetic distances. This generator work by using pneumatic mechanism (PLTGL) for power plants system. Result testing of performance AC generator translation motion obtained that maximum voltage, current and power are 63 Volt for diameter winding coil 0.15 mm, number of winding coil 13000 and distance of magnet 20 mm. For effect shape of magnet, maximum voltage happen on rectangle magnet 30x20x5 mm with 4.64 Volt. Voltage and power on effect of diameter winding coil is 14.63 V and 17.82 W at the diameter winding coil 0.7 and number of winding coil is 1260 with the distance of magnet 25

  6. 125-GHz Microwave Signal Generation Employing an Integrated Pulse Shaper

    DEFF Research Database (Denmark)

    Liao, Shasha; Ding, Yunhong; Dong, Jianji

    2017-01-01

    We propose and experimentally demonstrate an on-chip pulse shaper for 125-GHz microwave waveform generation. The pulse shaper is implemented based on a silicon-on-insulator (SOI) platform that has a structure with eight-tap finite impulse response (FIR) and there is an amplitude modulator on each...... of the generated microwave waveforms is larger than 100 GHz, and it has wide bandwidth when changing the time delay of the adjacent taps and compactness, capability for integration with electronics and small power consumption are also its merits.......We propose and experimentally demonstrate an on-chip pulse shaper for 125-GHz microwave waveform generation. The pulse shaper is implemented based on a silicon-on-insulator (SOI) platform that has a structure with eight-tap finite impulse response (FIR) and there is an amplitude modulator on each...

  7. Digital generation of stochastic signals of arbitrary spectral shape

    International Nuclear Information System (INIS)

    Behringer, K.; Nishihara, H.; Spiekerman, G.

    1986-10-01

    For computer-simulation experiments in the development of noise monitoring systems three methods of generating ergodic Gaussian random noise with specified spectral properties have been investigated: digital filtering of white noise optimum symmetric FIR filters, a modified Rice formulation and an approximation of the Kac representation of noise. The proposed modified Rice formulation is a new noise generation method which is most efficient with regard to the computation time. By windowing subsequent Rice sequences a smooth noise record of any desired length can be produced. (author)

  8. Digital generation of stochastic signals of arbitrary spectral shape

    International Nuclear Information System (INIS)

    Behringer, K.; Nishihara, H.; Spiekerman, G.

    1986-01-01

    For computer-simulation experiments in the development of noise monitoring systems three methods of generating ergodic Gaussian random noise with specified spectral properties have been investigated: digital filtering of white noise with optimum symmetric FIR filters, a modified Rice formulation and an approximation of the Kac representation of noise. The proposed modified Rice formulation is a new noise generation method which is most efficient with regard to the computation time. By windowing subsequent Rice sequences a smooth noise record of any desired length can be produced. (author)

  9. Automated Layout Generation of Analogue and Mixed-Signal ASIC's

    DEFF Research Database (Denmark)

    Bloch, Rene

    search for better solutions can be guided into new and more prosperous areas of the search space. This feature also provides the designer with the ability to easily try out several implementation options, thus exploring the solution space, which are especially important in the early stages of the design...... is generated using a full-custom layout style and is based on a library of CMOS process independent device generators. The placement for the analogue circuit is derived using the interactive floorplan optimization algorithm described above. This ensures that a high degree of user control is implemented...

  10. Theoretical investigation of metal magnetic memory testing technique for detection of magnetic flux leakage signals from buried defect

    Science.gov (United States)

    Xu, Kunshan; Qiu, Xingqi; Tian, Xiaoshuai

    2018-01-01

    The metal magnetic memory testing (MMMT) technique has been extensively applied in various fields because of its unique advantages of easy operation, low cost and high efficiency. However, very limited theoretical research has been conducted on application of MMMT to buried defects. To promote study in this area, the equivalent magnetic charge method is employed to establish a self-magnetic flux leakage (SMFL) model of a buried defect. Theoretical results based on the established model successfully capture basic characteristics of the SMFL signals of buried defects, as confirmed via experiment. In particular, the newly developed model can calculate the buried depth of a defect based on the SMFL signals obtained via testing. The results show that the new model can successfully assess the characteristics of buried defects, which is valuable in the application of MMMT in non-destructive testing.

  11. Heterogeneously Integrated Microwave Signal Generators with Narrow Linewidth Lasers

    Science.gov (United States)

    2017-03-20

    have shown that heterogeneous integration not only allows for a reduced cost due to economy of scale, but also allows for same or even better...advantage of introducing SOAs for microwave generator is the control and boosting of optical power before the detector providing higher RF powers. A

  12. Diagnosis of Short-Circuit Fault in Large-Scale Permanent-Magnet Wind Power Generator Based on CMAC

    Directory of Open Access Journals (Sweden)

    Chin-Tsung Hsieh

    2013-01-01

    Full Text Available This study proposes a method based on the cerebellar model arithmetic controller (CMAC for fault diagnosis of large-scale permanent-magnet wind power generators and compares the results with Error Back Propagation (EBP. The diagnosis is based on the short-circuit faults in permanent-magnet wind power generators, magnetic field change, and temperature change. Since CMAC is characterized by inductive ability, associative ability, quick response, and similar input signals exciting similar memories, it has an excellent effect as an intelligent fault diagnosis implement. The experimental results suggest that faults can be diagnosed effectively after only training CMAC 10 times. In comparison to training 151 times for EBP, CMAC is better than EBP in terms of training speed.

  13. Generation and coherent detection of QPSK signal using a novel method of digital signal processing

    Science.gov (United States)

    Zhao, Yuan; Hu, Bingliang; He, Zhen-An; Xie, Wenjia; Gao, Xiaohui

    2018-02-01

    We demonstrate an optical quadrature phase-shift keying (QPSK) signal transmitter and an optical receiver for demodulating optical QPSK signal with homodyne detection and digital signal processing (DSP). DSP on the homodyne detection scheme is employed without locking the phase of the local oscillator (LO). In this paper, we present an extracting one-dimensional array of down-sampling method for reducing unwanted samples of constellation diagram measurement. Such a novel scheme embodies the following major advantages over the other conventional optical QPSK signal detection methods. First, this homodyne detection scheme does not need strict requirement on LO in comparison with linear optical sampling, such as having a flat spectral density and phase over the spectral support of the source under test. Second, the LabVIEW software is directly used for recovering the QPSK signal constellation without employing complex DSP circuit. Third, this scheme is applicable to multilevel modulation formats such as M-ary PSK and quadrature amplitude modulation (QAM) or higher speed signals by making minor changes.

  14. Generation of on-line test signals for nuclear instrumentation for PFBR

    International Nuclear Information System (INIS)

    Ram, Rajit; Bhatnagar, P.V.; Rajesh, M.G.; Das, Debashis

    2010-01-01

    Neutron flux monitoring system for PFBR employs pulse signal processing in start up and intermediate power range of reactor operation and Campbell signal processing in intermediate and full power range of reactor operation. Pulse signal processing unit as well as Campbell signal processing unit incorporates FPGA that generates pulse/white noise signal for on-line testing and diagnostic of the channels. In pulse channel fixed/linearly/exponentially varying pulse rate signal is generated over three decades of reactor operation. In the Campbell channel, Poisson distributed noise varying linearly/exponentially is generated over four decades of reactor operation. Multiple numbers of Poisson distributed random pulse trains are summed and amplified to get the white noise signal. Exponentially increasing gain pattern, generated by MATLAB is used to increase the RMS value of the generated noise. The paper discuses the successful testing and validation of pulse and Campbell channel by making use of the generated pulse/white noise signal over wide range of operation for nuclear instrumentation. (author)

  15. Losses in magnetic flux compression generators: Part 2, Radiation losses

    International Nuclear Information System (INIS)

    Fowler, C.M.

    1988-06-01

    This is the second monograph devoted to the analysis of flux losses in explosive driven magnetic flux compression generators. In the first monograph, flux losses from magnetic field penetration into conductor walls was studied by conventional diffusion theory. In the present report flux loss by radiation from the outer conductor walls is treated. Flux leakage rates through walls of finite thickness are first obtained by diffusion theory. It is shown, for normal wall thicknesses, that flux leakage is determined essentially by the wall conductance, defined as the product of wall thickness and wall conductivity. This remains true when the wall thickness is reduced to zero at unchanged conductance. In this case the wall is said to be coalesced. Solutions for a cavity bounded by a perfect conductor on one side and a coalesced wall on the other are then obtained using the complete Maxwell wave equations in both the cavity and free space beyond the coalesced wall. Several anomalies, noted earlier, that arise from diffusion analysis are resolved by the wave treatment. Conditions for the validity of the diffusion treatment are noted, and an expression is obtained within the framework of diffusion theory for energy radiated into space from the cavity walls. The free space wave equations are solved by using the method of characteristics in both the cavity and free space regions. An extension of the characteristic method to situations where the constitutive relations are non-linear is outlined in an appendix. For a special class of these relations, Riemann-like invariants are determined explicitly and used to solve a particular example

  16. Design and implementation of the NaI(Tl)/CsI(Na) detectors output signal generator

    International Nuclear Information System (INIS)

    Zhou Xu; Liu Congzhan; Zhao Jianling

    2014-01-01

    We designed and implemented a signal generator that can simulate the output of the NaI(Tl)/CsI(Na) detectors' pre-amplifier onboard the Hard X-ray Modulation Telescope (HXMT). Using the development of the FPGA (Field Programmable Gate Array) with VHDL language and adding a random constituent, we have finally produced the double exponential random pulse signal generator. The statistical distribution of the signal amplitude is programmable. The occurrence time intervals of the adjacent signals contain negative exponential distribution statistically. (authors)

  17. Design and implementation of the NaI(Tl)/CsI(Na) detectors output signal generator

    Science.gov (United States)

    Zhou, Xu; Liu, Cong-Zhan; Zhao, Jian-Ling; Zhang, Fei; Zhang, Yi-Fei; Li, Zheng-Wei; Zhang, Shuo; Li, Xu-Fang; Lu, Xue-Feng; Xu, Zhen-Ling; Lu, Fang-Jun

    2014-02-01

    We designed and implemented a signal generator that can simulate the output of the NaI(Tl)/CsI(Na) detectors' pre-amplifier onboard the Hard X-ray Modulation Telescope (HXMT). Using the development of the FPGA (Field Programmable Gate Array) with VHDL language and adding a random constituent, we have finally produced the double exponential random pulse signal generator. The statistical distribution of the signal amplitude is programmable. The occurrence time intervals of the adjacent signals contain negative exponential distribution statistically.

  18. High magnetic field generation for laser-plasma experiments

    International Nuclear Information System (INIS)

    Pollock, B. B.; Froula, D. H.; Davis, P. F.; Ross, J. S.; Fulkerson, S.; Bower, J.; Satariano, J.; Price, D.; Krushelnick, K.; Glenzer, S. H.

    2006-01-01

    An electromagnetic solenoid was developed to study the effect of magnetic fields on electron thermal transport in laser plasmas. The solenoid, which is driven by a pulsed power system supplying 30 kJ, achieves magnetic fields of 13 T. The field strength was measured on the solenoid axis with a magnetic probe and optical Zeeman splitting. The measurements agree well with analytical estimates. A method for optimizing the solenoid design to achieve magnetic fields exceeding 20 T is presented

  19. Analysis and optimization of hybrid excitation permanent magnet synchronous generator for stand-alone power system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huijun, E-mail: huijun024@gmail.com [School of Instrumentation Science and Opto-electronics Engineering, Beihang University (China); Qu, Zheng; Tang, Shaofei; Pang, Mingqi [School of Instrumentation Science and Opto-electronics Engineering, Beihang University (China); Zhang, Mingju [Shanghai Aerospace Control Technology Institute, Shanghai (China)

    2017-08-15

    Highlights: • One novel permanent magnet generator structure has been proposed to reduce voltage regulation ratio. • Finite element method and equivalent circuit methods are both employed to realize rapid generator design. • Design of experiment (DOE) method is used to optimize permanent magnet shape for reduce voltage waveform distortion. • The obtained analysis and experiment results verify the proposed design methods. - Abstract: In this paper, electromagnetic design and permanent magnet shape optimization for permanent magnet synchronous generator with hybrid excitation are investigated. Based on generator structure and principle, design outline is presented for obtaining high efficiency and low voltage fluctuation. In order to realize rapid design, equivalent magnetic circuits for permanent magnet and iron poles are developed. At the same time, finite element analysis is employed. Furthermore, by means of design of experiment (DOE) method, permanent magnet is optimized to reduce voltage waveform distortion. Finally, the validity of proposed design methods is validated by the analytical and experimental results.

  20. Analysis and optimization of hybrid excitation permanent magnet synchronous generator for stand-alone power system

    International Nuclear Information System (INIS)

    Wang, Huijun; Qu, Zheng; Tang, Shaofei; Pang, Mingqi; Zhang, Mingju

    2017-01-01

    Highlights: • One novel permanent magnet generator structure has been proposed to reduce voltage regulation ratio. • Finite element method and equivalent circuit methods are both employed to realize rapid generator design. • Design of experiment (DOE) method is used to optimize permanent magnet shape for reduce voltage waveform distortion. • The obtained analysis and experiment results verify the proposed design methods. - Abstract: In this paper, electromagnetic design and permanent magnet shape optimization for permanent magnet synchronous generator with hybrid excitation are investigated. Based on generator structure and principle, design outline is presented for obtaining high efficiency and low voltage fluctuation. In order to realize rapid design, equivalent magnetic circuits for permanent magnet and iron poles are developed. At the same time, finite element analysis is employed. Furthermore, by means of design of experiment (DOE) method, permanent magnet is optimized to reduce voltage waveform distortion. Finally, the validity of proposed design methods is validated by the analytical and experimental results.

  1. Arrays of surface-normal electroabsorption modulators for the generation and signal processing of microwave photonics signals

    NARCIS (Netherlands)

    Noharet, Bertrand; Wang, Qin; Platt, Duncan; Junique, Stéphane; Marpaung, D.A.I.; Roeloffzen, C.G.H.

    2011-01-01

    The development of an array of 16 surface-normal electroabsorption modulators operating at 1550nm is presented. The modulator array is dedicated to the generation and processing of microwave photonics signals, targeting a modulation bandwidth in excess of 5GHz. The hybrid integration of the

  2. Using Magnets and Magnetic Beads to Dissect Signaling Pathways Activated by Mechanical Tension Applied to Cells

    Science.gov (United States)

    Marjoram, R.J.; Guilluy, C; Burridge, K.

    2015-01-01

    Cellular tension has implications in normal biology and pathology. Membrane adhesion receptors serve as conduits for mechanotransduction that lead to cellular responses. Ligand-conjugated magnetic beads are a useful tool in the study of how cells sense and respond to tension. Here we detail methods for their use in applying tension to cells and strategies for analyzing the results. We demonstrate the methods by analyzing mechanotransduction through VE-cadherin on endothelial cells using both permanent magnets and magnetic tweezers. PMID:26427549

  3. Signal Processing for the Impedance Measurement on an Electrochemical Generator

    Directory of Open Access Journals (Sweden)

    El-Hassane AGLZIM

    2008-04-01

    Full Text Available Improving the life time of batteries or fuel cells requires the optimization of components such as membranes and electrodes and enhancement of the flow of gases [1], [2]. These goals could be reached by using a real time measurement on loaded generator. The impedance spectroscopy is a new way that was recently investigated. In this paper, we present an electronic measurement instrumentation developed in our laboratory to measure and plot the impedance of a loaded electrochemical generator like batteries and fuel cells. Impedance measures were done according to variations of the frequency in a larger band than what is usually used. The electronic instrumentation is controlled by Hpvee® software which allows us to plot the Nyquist graph of the electrochemical generator impedance. The theoretical results obtained in simulation under Pspice® confirm the choice of the method and its advantage. For safety reasons, the experimental preliminary tests were done on a 12 V vehicle battery, having an input current of 330 A and a capacity of 40 Ah and are now extended to a fuel cell. The results were plotted at various nominal voltages of the battery (12.7 V, 10 V, 8 V and 5 V and with two imposed currents (0.6 A and 4 A. The Nyquist diagram resulting from the experimental data enable us to show an influence of the load of the battery on its internal impedance. The similitude in the graph form and in order of magnitude of the values obtained (both theoretical and practical enables us to validate our electronic measurement instrumentation. Different sensors (temperature, pressure were placed around the device under test (DUT. These influence parameters were permanently recorded. Results presented here concern a classic loaded 12 V vehicle battery. The Nyquist diagram resulting from the experimental data confirms the influence of the load of the DUT on its internal impedance.

  4. The random signal generator of imitated nuclear radiation pulse

    International Nuclear Information System (INIS)

    Li Dongcang; Yang Lei; Yuan Shulin; Yang Yinghui; Zang Fujia

    2007-01-01

    Based in pseudo-random uniformity number, it produces random numbers of Gaussian distribution and exponential distribution by arithmetic. The hardware is the single-chip microcomputer of 89C51. Program language makes use of Keil C. The output pulse amplitude is Gaussian distribution, exponential distribution or uniformity distribution. Likewise, it has two mode or upwards two. The time alternation of output pulse is both periodic and exponential distribution. The generator has achieved output control of multi-mode distribution, imitated random characteristic of nuclear pulse in amplitude and in time. (authors)

  5. Magnetic anomaly depth and structural index estimation using different height analytic signals data

    Science.gov (United States)

    Zhou, Shuai; Huang, Danian; Su, Chao

    2016-09-01

    This paper proposes a new semi-automatic inversion method for magnetic anomaly data interpretation that uses the combination of analytic signals of the anomaly at different heights to determine the depth and the structural index N of the sources. The new method utilizes analytic signals of the original anomaly at different height to effectively suppress the noise contained in the anomaly. Compared with the other high-order derivative calculation methods based on analytic signals, our method only computes first-order derivatives of the anomaly, which can be used to obtain more stable and accurate results. Tests on synthetic noise-free and noise-corrupted magnetic data indicate that the new method can estimate the depth and N efficiently. The technique is applied to a real measured magnetic anomaly in Southern Illinois caused by a known dike, and the result is in agreement with the drilling information and inversion results within acceptable calculation error.

  6. Optimization of Linear Permanent Magnet (PM Generator with Triangular-Shaped Magnet for Wave Energy Conversion using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Aamir Hussain

    2016-06-01

    Full Text Available This paper presents the design optimization of linear permanent magnet (PM generator for wave energy conversion using finite element method (FEM. A linear PM generator with triangular-shaped magnet is proposed, which has higher electromagnetic characteristics, superior performance and low weight as compared to conventional linear PM generator with rectangular shaped magnet. The Individual Parameter (IP optimization technique is employed in order to optimize and achieve optimum performance of linear PM generator. The objective function, optimization variables; magnet angle,M_θ(∆ (θ, the pole-width ratio, P_w ratio(τ_p/τ_mz,, and split ratio between translator and stator, δ_a ratio(R_m/R_e, and constraints are defined. The efficiency and its main parts; copper and iron loss are computed using time-stepping FEM. The optimal values after optimization are presented which yields highest efficiency. Key

  7. SSWL and BWL: finite element models of compressed magnetic field current generators

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, T.J.; Leeman, J.E.

    1976-01-01

    Documentation is presented for two new computer codes modeling the behavior of compressed magnetic field current generators. Code output results for the typical generator configurations are presented and compared to experimental results. (auth)

  8. Magnetic-field dependence of the signal of a uranium-scintillator calorimeter

    International Nuclear Information System (INIS)

    Bruehl, S.

    1991-11-01

    The magnetic-field dependence of the signal from 3 GeV electrons and the signal from the uranium radioactivity of a uranium-SCSN-38 test calorimeter was studied with the three in the ZEUS calorimeter implemented uranium-plate coatings 0.2 mm V2A, 0.4 mm V2A, and 0.2 mm V2A and 0.2 mm magnetic C10 in two field directions with fields between 0.01 and 1.4 tesla. In fields oriented parallel to the calorimeter axis uranium and particle signal behave equally except for the case, in which V2A and C10 are applied. At 0.01 tesla the particle signal varies by 1% and the uranium signal by 1.5%. Both signals remain up to 0.1 tesla on this level and increase from this magnetic field. The variation reaches at 1 tesla 4.5% for the particle and 6% for the uranium signal. In the application of V2A and C10 no variation of the particle signal is to be recognized within the errors, while the uranium signal increases monotoneously from 0 to 1.5%. In perpendicularly to the calorimeter axis oriented fields from ≅ 0.3 tesla a different development in the particle and uranium signal occurs. Up to this fields the behaviour of particle and uranium signal is identical with the behaviour in the other field direction. In the application of V2A and C10 the particle respectively the uranium signal increases from 0 at 0.01 tesla to 1% respectively 1.5% at 0.03 tesla. Thereafter the plateau up to 0.1 tesla with the subsequent increasement follows. Independently on the uranium-plate coating the increasement of the uranium signal decreases from 0.3 tesla, reaches at 0.5 tesla a maximum of 3 to 4% and decreases thereafter to 1% at 1 tesla. The particle signal increases as in the other field direction and reaches a signal variation of 7% at 1 tesla. The results are used in the regardment of the magnetic-field effects on the calibration of the ZEUS calorimeter. (orig.) [de

  9. Direct UV written Michelson interferometer for RZ signal generation using phase-to-intensity modulation conversion

    DEFF Research Database (Denmark)

    Peucheret, Christophe; Geng, Yan; Zsigri, Beata

    2005-01-01

    An integrated Michelson delay interferometer structure making use of waveguide gratings as reflective elements is proposed and fabricated by direct ultraviolet writing. Successful return-to-zero alternate-mark-inversion signal generation using phase-to-intensity modulation conversion...

  10. Automatic bearing fault diagnosis of permanent magnet synchronous generators in wind turbines subjected to noise interference

    Science.gov (United States)

    Guo, Jun; Lu, Siliang; Zhai, Chao; He, Qingbo

    2018-02-01

    An automatic bearing fault diagnosis method is proposed for permanent magnet synchronous generators (PMSGs), which are widely installed in wind turbines subjected to low rotating speeds, speed fluctuations, and electrical device noise interferences. The mechanical rotating angle curve is first extracted from the phase current of a PMSG by sequentially applying a series of algorithms. The synchronous sampled vibration signal of the fault bearing is then resampled in the angular domain according to the obtained rotating phase information. Considering that the resampled vibration signal is still overwhelmed by heavy background noise, an adaptive stochastic resonance filter is applied to the resampled signal to enhance the fault indicator and facilitate bearing fault identification. Two types of fault bearings with different fault sizes in a PMSG test rig are subjected to experiments to test the effectiveness of the proposed method. The proposed method is fully automated and thus shows potential for convenient, highly efficient and in situ bearing fault diagnosis for wind turbines subjected to harsh environments.

  11. Analysis and optimization of hybrid excitation permanent magnet synchronous generator for stand-alone power system

    Science.gov (United States)

    Wang, Huijun; Qu, Zheng; Tang, Shaofei; Pang, Mingqi; Zhang, Mingju

    2017-08-01

    In this paper, electromagnetic design and permanent magnet shape optimization for permanent magnet synchronous generator with hybrid excitation are investigated. Based on generator structure and principle, design outline is presented for obtaining high efficiency and low voltage fluctuation. In order to realize rapid design, equivalent magnetic circuits for permanent magnet and iron poles are developed. At the same time, finite element analysis is employed. Furthermore, by means of design of experiment (DOE) method, permanent magnet is optimized to reduce voltage waveform distortion. Finally, the validity of proposed design methods is validated by the analytical and experimental results.

  12. An Improved Second-Order Generalized Integrator Based Quadrature Signal Generator

    DEFF Research Database (Denmark)

    Xin, Zhen; Wang, Xiongfei; Qin, Zian

    2016-01-01

    The second-order generalized integrator based quadrature signal generator (SOGI-QSG) is able to produce in-quadrature signals for many applications, such as frequency estimation, grid synchronization, and harmonic extraction. However, the SOGI-QSG is sensitive to input dc and harmonic components...

  13. Integration of Optically Generated Impulse Radio UWB Signals into Baseband WDM-PON

    DEFF Research Database (Denmark)

    Pham, Tien Thang; Yu, Xianbin; Dittmann, Lars

    2011-01-01

    We propose a compact integration system to simultaneously provide wireline and wireless (baseband and ultra-wide band (UWB)) services to end-users in a WDM-PON. A 1-Gbps UWB signal is optically generated and shares the same wavelength with the baseband signal. Error-free performance was achieved...

  14. An ultra-efficient nonlinear planar integrated platform for optical signal processing and generation

    DEFF Research Database (Denmark)

    Pu, Minhao; Ottaviano, Luisa; Semenova, Elizaveta

    2017-01-01

    This paper will discuss the recently developed integrated platform: AlGaAs-oninsulator and its broad range of nonlinear applications. Recent demonstrations of broadband optical signal processing and efficient frequency comb generations in this platform will be reviewed.......This paper will discuss the recently developed integrated platform: AlGaAs-oninsulator and its broad range of nonlinear applications. Recent demonstrations of broadband optical signal processing and efficient frequency comb generations in this platform will be reviewed....

  15. Engineering Synthetic Proteins to Generate Ca2+ Signals in Mammalian Cells.

    Science.gov (United States)

    Qudrat, Anam; Truong, Kevin

    2017-03-17

    The versatility of Ca 2+ signals allows it to regulate diverse cellular processes such as migration, apoptosis, motility and exocytosis. In some receptors (e.g., VEGFR2), Ca 2+ signals are generated upon binding their ligand(s) (e.g., VEGF-A). Here, we employed a design strategy to engineer proteins that generate a Ca 2+ signal upon binding various extracellular stimuli by creating fusions of protein domains that oligomerize to the transmembrane domain and the cytoplasmic tail of the VEGFR2. To test the strategy, we created chimeric proteins that generate Ca 2+ signals upon stimulation with various extracellular stimuli (e.g., rapamycin, EDTA or extracellular free Ca 2+ ). By coupling these chimeric proteins that generate Ca 2+ signals with proteins that respond to Ca 2+ signals, we rewired, for example, dynamic cellular blebbing to increases in extracellular free Ca 2+ . Thus, using this design strategy, it is possible to engineer proteins to generate a Ca 2+ signal to rewire a wide range of extracellular stimuli to a wide range of Ca 2+ -activated processes.

  16. Projectile-power-compressed magnetic-field pulse generator

    International Nuclear Information System (INIS)

    Barlett, R.H.; Takemori, H.T.; Chase, J.B.

    1983-01-01

    Design considerations and experimental results are presented of a compressed magnetic field pulsed energy source. A 100-mm-diameter, gun-fired projectile of approx. 2MJ kinetic energy was the input energy source. An initial magnetic field was trapped and compressed by the projectile. With a shorted load, a magajoule in a nanohenry was the design goal, i.e., 50 percent energy transformation from kinetic to magnetic. Five percent conversion was the highest recorded before gauge failure

  17. Estimation of Threshold for the Signals of the BLMs around the LHC Final Focus Triplet Magnets

    CERN Document Server

    Cerutti, F; Ferrari, A; Hoa, C; Mauri, M; Mereghetti, A; Sapinski, M; Wildner, E; CERN. Geneva. ATS Department

    2012-01-01

    The Interaction Points of the Large Hadron Collider are the regions where the two circulating beams collide. Hence, the magnets the closest to any Interaction Point are exposed to an elevated radiation field due to the collision debris. In this study the signal in the Beam Loss Monitors due to the debris is estimated. In addition, for three different scenarios of beam losses, the energy density in the coils and the signal in the Beam Loss Monitors at quench are computed. It is shown that the Beam Loss Monitors, as presently installed on the vacuum vessel of the magnets, cannot disentangle the signal due to a localised loss from the constant signal due to the debris in case of steady-state losses.

  18. Soliton generation from a multi-frequency optical signal

    International Nuclear Information System (INIS)

    Panoiu, N-C; Mel'nikov, I V; Mihalache, D; Etrich, C; Lederer, F

    2002-01-01

    We present a comprehensive analysis of the generation of optical solitons in a monomode optical fibre from a superposition of soliton-like optical pulses at different frequencies. It is demonstrated that the structure of the emerging optical field is highly dependent on the number of input channels, the inter-channel frequency separation, the time shift between the pulses belonging to adjacent channels, and the polarization of the pulses. Also, it is found that there exists a critical frequency separation above which wavelength-division multiplexing with solitons is feasible and that this critical frequency increases with the number of transmission channels. Moreover, for the case in which only two channels are considered, we analyse the propagation of the emerging two-soliton solutions in the presence of several perturbations important for optical networks: bandwidth-limited amplification, nonlinear amplification, and amplitude and phase modulation. Finally, the influence of the birefringence of the fibre on the structure of the emerging optical field is discussed. (review article)

  19. Design and Finite Element Analysis of a Novel Transverse Flux Permanent Magnet Disk Generator

    DEFF Research Database (Denmark)

    Hosseini, Seyedmohsen; Moghani, Javad Shokrollahi; Ershad, Nima Farrokhzad

    2011-01-01

    This paper presents a novel structure of a transverse flux permanent magnet disk generator. The proposed disk shape structure simplifies prototyping by using simple laminated steel sheets in comparison with previous transverse flux structures that employ bent laminations and soft magnetic...... composites. Also the proposed structure has a higher power factor than what has been reported previously for transverse flux permanent magnet structures. After introducing the transverse flux permanent magnet disk generator, the design process is explained and a small power generator is designed...

  20. The magnetic field generated by a rotating charged polygon

    International Nuclear Information System (INIS)

    Wan, Songlin; Chen, Xiangyu; Teng, Baohua; Fu, Hao; Li, Yefeng; Wu, Minghe; Wu, Shaoyi; Balfour, E A

    2014-01-01

    The magnetic field along the symmetry axis of a regular polygon carrying a uniform electric charge on its edges is calculated systematically when the polygon is rotated about this axis of symmetry. A group of circular current-carrying coils arranged concentrically about the axis of the polygon has been designed to simulate the magnetic field characteristics of the rotating charged polygon. The magnetic field of the simulated coils is measured using the PASCO magnetic field sensor. The results show that the theoretical calculation agrees well with the experimental results. (paper)

  1. Improved cost of energy comparison of permanent magnet generators for large offshore wind turbines

    NARCIS (Netherlands)

    Hart, K.; McDonald, A.; Polinder, H.; Corr, E.; Carroll, J.

    2014-01-01

    This paper investigates geared and direct-drive permanent magnet generators for a typical offshore wind turbine, providing a detailed comparison of various wind turbine drivetrain configurations in order to minimise the Cost of Energy. The permanent magnet generator topologies considered include a

  2. Generation of intense, high-energy ion pulses by magnetic compression of ion rings

    International Nuclear Information System (INIS)

    Kapetanakos, C.A.

    1981-01-01

    A system based on the magnetic compression of ion rings, for generating intense (High-current), high-energy ion pulses that are guided to a target without a metallic wall or an applied external magnetic field includes a vacuum chamber; an inverse reflex tetrode for producing a hollow ion beam within the chamber; magnetic coils for producing a magnetic field, bo, along the axis of the chamber; a disc that sharpens a magnetic cusp for providing a rotational velocity to the beam and causing the beam to rotate; first and second gate coils for producing fast-rising magnetic field gates, the gates being spaced apart, each gate modifying a corresponding magnetic mirror peak (Near and far peaks) for trapping or extracting the ions from the magnetic mirror, the ions forming a ring or layer having rotational energy; a metal liner for generating by magnetic flux compression a high, time-varying magnetic field, the time-varying magnetic field progressively increasing the kinetic energy of the ions, the magnetic field from the second gate coil decreasing the far mirror peak at the end of the compression for extracting the trapped rotating ions from the confining mirror; and a disc that sharpens a magnetic half-cusp for increasing the translational velocity of the ion beam. The system utilizes the self-magnetic field of the rotating, propagating ion beam to prevent the beam from expanding radially upon extraction

  3. An X-ray CCD signal generator with true random arrival time

    International Nuclear Information System (INIS)

    Huo Jia; Xu Yuming; Chen Yong; Cui Weiwei; Li Wei; Zhang Ziliang; Han Dawei; Wang Yusan; Wang Juan

    2011-01-01

    An FPGA-based true random signal generator with adjustable amplitude and exponential distribution of time interval is presented. Since traditional true random number generators (TRNG) are resource costly and difficult to transplant, we employed a method of random number generation based on jitter and phase noise in ring oscillators formed by gates in an FPGA. In order to improve the random characteristics, a combination of two different pseudo-random processing circuits is used for post processing. The effects of the design parameters, such as sample frequency are discussed. Statistical tests indicate that the generator can well simulate the timing behavior of random signals with Poisson distribution. The X-ray CCD signal generator will be used in debugging the CCD readout system of the Low Energy X-ray Instrument onboard the Hard X-ray Modulation Telescope (HXMT). (authors)

  4. Lipid rafts generate digital-like signal transduction in cell plasma membranes.

    Science.gov (United States)

    Suzuki, Kenichi G N

    2012-06-01

    Lipid rafts are meso-scale (5-200 nm) cell membrane domains where signaling molecules assemble and function. However, due to their dynamic nature, it has been difficult to unravel the mechanism of signal transduction in lipid rafts. Recent advanced imaging techniques have revealed that signaling molecules are frequently, but transiently, recruited to rafts with the aid of protein-protein, protein-lipid, and/or lipid-lipid interactions. Individual signaling molecules within the raft are activated only for a short period of time. Immobilization of signaling molecules by cytoskeletal actin filaments and scaffold proteins may facilitate more efficient signal transmission from rafts. In this review, current opinions of how the transient nature of molecular interactions in rafts generates digital-like signal transduction in cell membranes, and the benefits this phenomenon provides, are discussed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Magnetic Signals of High-Temperature Superconductor Bulk During the Levitation Force Measurement Process

    Science.gov (United States)

    Huang, Huan; Zheng, Jun; Qian, Nan; Che, Tong; Zheng, Botian; Jin, Liwei; Deng, Zigang

    2017-05-01

    In order to study the commonly neglected magnetic field information in the course of levitation force measurement process in a superconducting maglev system, a multipoint magnetic field measurement platform was employed to acquire magnetic signals of a bulk high-Tc superconductor on both the top and the bottom surface. Working conditions including field cooling (FC) and zero field cooling were investigated for these vertical down and up motions above a permanent magnet guideway performed on a HTS maglev measurement system. We have discussed the magnetic flux variation process based on the Bean model. A magnetic hysteresis effect similar to the levitation force hysteresis loop of the bulk superconductor was displayed and analyzed in this paper. What is more valuable, there exists some available magnetic flux on the top surface of the bulk superconductor, and the proportion is as high as 62.42% in the FC condition, which provides an experimental hint to design the superconductor bulk and the applied field for practical use in a more efficient way. In particular, this work reveals real-time magnetic flux variation of the bulk superconductor in the levitation application, which is the other important information in contrast to the macroscopic levitation and guidance force investigations in previous studies, and it enriches the existing research methods. The results are significant for understanding the magnetic characteristic of superconductors, and they can contribute to optimize the present HTS maglev system design.

  6. A Technique for Generating Volumetric Cine-Magnetic Resonance Imaging

    International Nuclear Information System (INIS)

    Harris, Wendy; Ren, Lei; Cai, Jing; Zhang, You; Chang, Zheng; Yin, Fang-Fang

    2016-01-01

    Purpose: The purpose of this study was to develop a techique to generate on-board volumetric cine-magnetic resonance imaging (VC-MRI) using patient prior images, motion modeling, and on-board 2-dimensional cine MRI. Methods and Materials: One phase of a 4-dimensional MRI acquired during patient simulation is used as patient prior images. Three major respiratory deformation patterns of the patient are extracted from 4-dimensional MRI based on principal-component analysis. The on-board VC-MRI at any instant is considered as a deformation of the prior MRI. The deformation field is represented as a linear combination of the 3 major deformation patterns. The coefficients of the deformation patterns are solved by the data fidelity constraint using the acquired on-board single 2-dimensional cine MRI. The method was evaluated using both digital extended-cardiac torso (XCAT) simulation of lung cancer patients and MRI data from 4 real liver cancer patients. The accuracy of the estimated VC-MRI was quantitatively evaluated using volume-percent-difference (VPD), center-of-mass-shift (COMS), and target tracking errors. Effects of acquisition orientation, region-of-interest (ROI) selection, patient breathing pattern change, and noise on the estimation accuracy were also evaluated. Results: Image subtraction of ground-truth with estimated on-board VC-MRI shows fewer differences than image subtraction of ground-truth with prior image. Agreement between normalized profiles in the estimated and ground-truth VC-MRI was achieved with less than 6% error for both XCAT and patient data. Among all XCAT scenarios, the VPD between ground-truth and estimated lesion volumes was, on average, 8.43 ± 1.52% and the COMS was, on average, 0.93 ± 0.58 mm across all time steps for estimation based on the ROI region in the sagittal cine images. Matching to ROI in the sagittal view achieved better accuracy when there was substantial breathing pattern change. The technique was robust against

  7. A Technique for Generating Volumetric Cine-Magnetic Resonance Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Wendy [Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States); Ren, Lei, E-mail: lei.ren@duke.edu [Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States); Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Cai, Jing [Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States); Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Zhang, You [Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States); Chang, Zheng; Yin, Fang-Fang [Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States); Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States)

    2016-06-01

    Purpose: The purpose of this study was to develop a techique to generate on-board volumetric cine-magnetic resonance imaging (VC-MRI) using patient prior images, motion modeling, and on-board 2-dimensional cine MRI. Methods and Materials: One phase of a 4-dimensional MRI acquired during patient simulation is used as patient prior images. Three major respiratory deformation patterns of the patient are extracted from 4-dimensional MRI based on principal-component analysis. The on-board VC-MRI at any instant is considered as a deformation of the prior MRI. The deformation field is represented as a linear combination of the 3 major deformation patterns. The coefficients of the deformation patterns are solved by the data fidelity constraint using the acquired on-board single 2-dimensional cine MRI. The method was evaluated using both digital extended-cardiac torso (XCAT) simulation of lung cancer patients and MRI data from 4 real liver cancer patients. The accuracy of the estimated VC-MRI was quantitatively evaluated using volume-percent-difference (VPD), center-of-mass-shift (COMS), and target tracking errors. Effects of acquisition orientation, region-of-interest (ROI) selection, patient breathing pattern change, and noise on the estimation accuracy were also evaluated. Results: Image subtraction of ground-truth with estimated on-board VC-MRI shows fewer differences than image subtraction of ground-truth with prior image. Agreement between normalized profiles in the estimated and ground-truth VC-MRI was achieved with less than 6% error for both XCAT and patient data. Among all XCAT scenarios, the VPD between ground-truth and estimated lesion volumes was, on average, 8.43 ± 1.52% and the COMS was, on average, 0.93 ± 0.58 mm across all time steps for estimation based on the ROI region in the sagittal cine images. Matching to ROI in the sagittal view achieved better accuracy when there was substantial breathing pattern change. The technique was robust against

  8. Magnetic resonance imaging apparatus

    International Nuclear Information System (INIS)

    Ehnholm, G.J.

    1991-01-01

    This patent describes an electron spin resonance enhanced magnetic resonance (MR) imaging (ESREMRI) apparatus able to generate a primary magnetic field during periods of nuclear spin transition excitation and magnetic resonance signal detection. This allows the generation of ESREMRI images of a subject. A primary magnetic field of a second and higher value generated during periods of nuclear spin transition excitation and magnetic resonance signal detection can be used to generate conventional MR images of a subject. The ESREMRI and native MR images so generated may be combined, (or superimposed). (author)

  9. Impulse Magnetic Fields Generated by Electrostatic Discharges in Protoplanetary Nebulae

    Science.gov (United States)

    Tunyi, I.; Guba, P.; Roth, L. E.; Timko, M.

    2002-01-01

    We examine quantitative aspects associated with the hypothesis of nebular lightnings as a source of impulse magnetic fields. Our findings support our previous accretion model in which a presence of impulse magnetic fields was of a key necessity. Additional information is contained in the original extended abstract.

  10. Batteryless wireless transmission system for electronic drum uses piezoelectric generator for play signal and power source

    International Nuclear Information System (INIS)

    Nishikawa, H; Yoshimi, A; Takemura, K; Tanaka, A; Douseki, T

    2015-01-01

    A batteryless self-powered wireless transmission system has been developed that sends a signal from a drum pad to a synthesizer. The power generated by a piezoelectric generator functions both as the “Play” signal for the synthesizer and as the power source for the transmitter. An FM transmitter, which theoretically operates with zero latency, and a receiver with quick-response squelch of the received signal were developed for wireless transmission with a minimum system delay. Experimental results for an electronic drum without any connecting wires fully demonstrated the feasibility of self-powered wireless transmission with a latency of 900 μs. (paper)

  11. Signal validation and failure correction algorithms for PWR steam generator feedwater control

    International Nuclear Information System (INIS)

    Nasrallah, C.N.; Graham, K.F.

    1986-01-01

    A critical contributor to the reliability of a nuclear power plant is the reliability of the control systems which maintain plant operating parameters within desired limits. The most difficult system to control in a PWR nuclear power plant and the one which causes the most reactor trips is the control of the feedwater flow to the steam generators. The level in the steam generator must be held within relatively narrow limits, with reactor trips set for both too high and too low a level. The steam generator level is inherently unstable in that it is an open integrator of feedwater flow steam flow mismatch. The steam generator feedwater control system relies on sensed variables in order to generate the appropriate feedwater valve control signal. In current systems, each of these sensed variables comes from a single sensor which may be a separate control sensor or one of the redundant protection sensors that is manually selected by the operator. In case this single signal is false, either due to sensor malfunction or due to a test signal being substituted during periodic test and maintenance, the control system will generate a wrong control signal to the feedwater control valve. This will initiate a steam generator level upset. The solution to this problem is for the control system to sense a given variable with more than one redundant sensor. Normally there are three or four sensors for each variable monitored by the reactor protection system. The techniques discussed allow the control system to compare these redundant sensor signals and generate a validated signal for each measured variable that is insensitive to false signals

  12. PC-based analog signal generator for simulated detector signals and arbitrary test waveforms for testing the nuclear instruments

    International Nuclear Information System (INIS)

    Catanescu, V.

    1999-01-01

    This work is performed in cooperation with IAEA-Vienna as a project, proposed as part of Agency's C o-ordinated Research Programme of Development of Computer-based Troubleshooting Tools and Instruments. A convenient way for testing and calibrating modern scientific equipment is to connect the test instruments to a personal computer to get additional feasibilities. This way, all settings for test, measurement and data acquisition functions are done by means of PC and are controlled by software drivers. This multifunctional spectrometric pulse generator is able to characterize different parts of high-resolution nuclear spectroscopy chain (preamplifier, amplifier, analog to digital converter, multichannel analyzer) as well as the whole chain. For this it generates periodic or random pulses with shape, time and amplitude specifications controlled by PC. Characteristics such as integral linearity, differential linearity, dead time, rate channel shifting and others will be easily determined. The block diagram of the multifunctional spectrometric generator is shown. The main sections are: PC-interface, control registers and command generation; PC-controlled periodic and random logic pulse oscillators; PC-controlled delay and width of periodic or random logic pulses; constant and ultra-linear ramp references for spectrometric pulse generation; generation of the tail and flat top pulses with PC-controlled amplitude and decay time; semi-gaussian pulse generation, polarity inverter and output amplifier. The specifications for generated signal correspond to: shape, time specifications and amplitude size. (author)

  13. Cultural Transmission and Evolution of Melodic Structures in Multi-generational Signaling Games

    DEFF Research Database (Denmark)

    Lumaca, Massimo; Baggio, G.

    2017-01-01

    , and basic and compound emotions as meanings, were transmitted from senders to receivers along diffusion chains in which the receiver in each game became the sender in the next game. During transmission, structural regularities accumulated in the signaling systems, following principles of proximity, symmetry...... and cognitive constraints similarly affect the evolution of musical systems? We conducted an experiment on the cultural evolution of artificial melodic systems, using multi-generational signaling games as a laboratory model of cultural transmission. Signaling systems, using five-tone sequences as signals...

  14. Ultrasonic signal analysis according to laser ultrasound generation position for the detection of delamination in composites

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Kyung Min; Choi In Young; Kim, Seong Jong; Kang, Young June [Chonbuk National University, Jeonju (Korea, Republic of); Lee, Gil Dong [GP Inc., Daejeon (Korea, Republic of)

    2015-11-15

    Carbon-fiber-reinforced plastic should be inspected in the fabrication process to enhance quality by preventing defects, such as delamination and voids. Conventional ultrasonic evaluation methods cannot be applied during the fabrication process because they require contact measurement by a transducer. Thus, an optical method using a laser was employed in this study for non-contact ultrasonic evaluation. Ultrasonic signals were generated by a pulsed laser and received by using a laser interferometer. First, an ultrasonic signal was generated from the back side of a material sample with artificial internal defects in the composite. The ultrasonic signal directed through the interior of the specimen was then detected at the front side. After determining the locations of the internal defects, the defects were quantitatively evaluated from the front side of the composite by using ultrasonic signal generation and reception.

  15. Distribution of photonically generated 5 Gbits=s impulse radio ultrawideband signals over fiber

    DEFF Research Database (Denmark)

    Yu, Xianbin; Tafur Monroy, Idelfonso

    2011-01-01

    We propose an approach to generate ultrawideband (UWB) pulses with tunable high-speed modulation based on pulse compression. Flexible generation of up to a record 5 Gbits=s on-off keying impulse radio UWB signals are successfully demonstrated as well. We also investigate 5 Gbits=s on-off keying bit...

  16. A study of MRI gradient echo signals from discrete magnetic particles with considerations of several parameters in simulations.

    Science.gov (United States)

    Kokeny, Paul; Cheng, Yu-Chung N; Xie, He

    2018-05-01

    Modeling MRI signal behaviors in the presence of discrete magnetic particles is important, as magnetic particles appear in nanoparticle labeled cells, contrast agents, and other biological forms of iron. Currently, many models that take into account the discrete particle nature in a system have been used to predict magnitude signal decays in the form of R2* or R2' from one single voxel. Little work has been done for predicting phase signals. In addition, most calculations of phase signals rely on the assumption that a system containing discrete particles behaves as a continuous medium. In this work, numerical simulations are used to investigate MRI magnitude and phase signals from discrete particles, without diffusion effects. Factors such as particle size, number density, susceptibility, volume fraction, particle arrangements for their randomness, and field of view have been considered in simulations. The results are compared to either a ground truth model, theoretical work based on continuous mediums, or previous literature. Suitable parameters used to model particles in several voxels that lead to acceptable magnetic field distributions around particle surfaces and accurate MR signals are identified. The phase values as a function of echo time from a central voxel filled by particles can be significantly different from those of a continuous cubic medium. However, a completely random distribution of particles can lead to an R2' value which agrees with the prediction from the static dephasing theory. A sphere with a radius of at least 4 grid points used in simulations is found to be acceptable to generate MR signals equivalent from a larger sphere. Increasing number of particles with a fixed volume fraction in simulations reduces the resulting variance in the phase behavior, and converges to almost the same phase value for different particle numbers at each echo time. The variance of phase values is also reduced when increasing the number of particles in a fixed

  17. Effect of nonlinear-electrodynamic lagging of electromagnetic signals in the field of magnetic dipole

    International Nuclear Information System (INIS)

    Denisov, V.I.; Krivchenkov, I.V.; Denisov, I.P.

    2002-01-01

    The study on the electromagnetic waves propagation in the neutron star magnetic dipole and gravitation fields, taking place according to the vacuum nonlinear electrodynamics laws, is carried out. It is shown that depending on the polarization the electromagnetic signals in this field propagate by different beams and with various velocities. The law on these signals motion by beams is established. The calculation of differences in the times of the electromagnetic signals propagation, having the same source up to the detector, is presented. It is shown that this difference in some cases may reach enough measurable value of 1 μs [ru

  18. The spatial distribution and time evolution of impact-generated magnetic fields

    Science.gov (United States)

    Crawford, D. A.; Schultz, P. H.

    1991-01-01

    The production of magnetic fields was revealed by laboratory hypervelocity impacts in easily vaporized targets. As quantified by pressure measurements, high frame-rate photography, and electrostatic probes, these impacts tend to produce large quantities of slightly ionized vapor, which is referred to as impact-generated plasma. Nonaligned electron density and temperature gradients within this plasma may lead to production of the observed magnetic fields. Past experiments were limited to measuring a single component of the impact-generated magnetic fields at only a few locations about the developing impact crater and consequently gave little information about the field production mechanism. To understand this mechanism, the techniques were extended to map the three components of the magnetic field both in space and time. By conducting many otherwise identical experiments with arrayed magnetic detectors, a preliminary 3-D picture was produced of impact-generated magnetic fields as they develop through time.

  19. Effect of pole number and slot number on performance of dual rotor permanent magnet wind power generator using ferrite magnets

    Directory of Open Access Journals (Sweden)

    Peifeng Xu

    2017-05-01

    Full Text Available Dual rotor permanent magnet (DRPM wind power generator using ferrite magnets has the advantages of low cost, high efficiency, and high torque density. How to further improve the performance and reduce the cost of the machine by proper choice of pole number and slot number is an important problem to be solved when performing preliminarily design a DRPM wind generator. This paper presents a comprehensive performance comparison of a DRPM wind generator using ferrite magnets with different slot and pole number combinations. The main winding factors are calculated by means of the star of slots. Under the same machine volume and ferrite consumption, the flux linkage, back-electromotive force (EMF, cogging torque, output torque, torque pulsation, and losses are investigated and compared using finite element analysis (FEA. The results show that the slot and pole number combinations have an important impact on the generator properties.

  20. SQUID magnetometer using sensitivity correction signal for non-magnetic metal contaminants detection

    Energy Technology Data Exchange (ETDEWEB)

    Yagi, Toshifumi, E-mail: sakuta.k@usp.ac.jp; Ohashi, Masaharu; Sakuta, Ken

    2016-11-15

    Highlights: • A high-frequency excitation is necessary to detect nonmagnetic metals using SQUID. • It is possible to detect a high-frequency magnetic field using the open loop technique. • Open loop operation leads to a change in the conversion factor. • Conversion between voltage and magnetic field for open loop operation are examined. - Abstract: Measurement methods with SQUID can accurately detect small magnetic metal contaminants based on their magnetic remanence. But, a high-frequency excitation is necessary to detect nonmagnetic metals, on the base of contrasts in electric conductivity. In this work, an open loop technique is introduced to facilitate this. The SQUID is negative feedback controlled (flux locked loop (FLL) operation) for the low frequency range, which includes significant noise due to the movement of the magnetic body or the change of the ambient magnetic field composed of the geomagnetic field and technical signals, and it operates in an open loop configuration for the high frequency range. When using the open loop technique, negative feedback is not applied to the high frequency range. Consequently, the V–Φ characteristic changes due to various causes, which leads to variations in the conversion factor between the SQUID output voltage and the magnetic field. In this study, conversion techniques for the magnetic field for open loop operation of SQUID in the high frequency range are examined.

  1. SQUID magnetometer using sensitivity correction signal for non-magnetic metal contaminants detection

    International Nuclear Information System (INIS)

    Yagi, Toshifumi; Ohashi, Masaharu; Sakuta, Ken

    2016-01-01

    Highlights: • A high-frequency excitation is necessary to detect nonmagnetic metals using SQUID. • It is possible to detect a high-frequency magnetic field using the open loop technique. • Open loop operation leads to a change in the conversion factor. • Conversion between voltage and magnetic field for open loop operation are examined. - Abstract: Measurement methods with SQUID can accurately detect small magnetic metal contaminants based on their magnetic remanence. But, a high-frequency excitation is necessary to detect nonmagnetic metals, on the base of contrasts in electric conductivity. In this work, an open loop technique is introduced to facilitate this. The SQUID is negative feedback controlled (flux locked loop (FLL) operation) for the low frequency range, which includes significant noise due to the movement of the magnetic body or the change of the ambient magnetic field composed of the geomagnetic field and technical signals, and it operates in an open loop configuration for the high frequency range. When using the open loop technique, negative feedback is not applied to the high frequency range. Consequently, the V–Φ characteristic changes due to various causes, which leads to variations in the conversion factor between the SQUID output voltage and the magnetic field. In this study, conversion techniques for the magnetic field for open loop operation of SQUID in the high frequency range are examined.

  2. Inflationary susceptibilities, duality and large-scale magnetic fields generation

    CERN Document Server

    Giovannini, Massimo

    2013-01-01

    We investigate what can be said about the interaction of scalar fields with Abelian gauge fields during a quasi-de Sitter phase of expansion and under the assumption that the electric and the magnetic susceptibilities do not coincide. The duality symmetry, transforming the magnetic susceptibility into the inverse of the electric susceptibility, exchanges the magnetic and electric power spectra. The mismatch between the two susceptibilities determines an effective refractive index affecting the evolution of the canonical fields. The constraints imposed by the duration of the inflationary phase and by the magnetogenesis requirements pin down the rate of variation of the susceptibilities that is consistent with the observations of the magnetic field strength over astrophysical and cosmological scales but avoids back-reaction problems. The parameter space of this magnetogenesis scenario is wider than in the case when the susceptibilities are equal, as it happens when the inflaton or some other spectator field is ...

  3. Evanescent magnetic field effects on entropy generation at the onset ...

    Indian Academy of Sciences (India)

    application of evanescent magnetic field not only suppresses the fluctuation of the ..... the Prigogine's theorem of minimum entropy production is unproven. ... consists in a double spiral configuration and viscous boundary layers in close ...

  4. Generation of magnetic structures on the solar photosphere

    Energy Technology Data Exchange (ETDEWEB)

    Gangadhara, R. T.; Krishan, V. [Indian Institute of Astrophysics, Bangalore-560034 (India); Bhowmick, A. K.; Chitre, S. M., E-mail: ganga@iiap.res.in [Centre for Excellence in Basic Sciences, University of Mumbai, Mumbai-400098 (India)

    2014-06-20

    The lower solar atmosphere is a partially ionized plasma consisting of electrons, ions, and neutral atoms. In this, which is essentially a three-fluid system, the Hall effect arises from the treatment of the electrons and ions as two separate fluids and the ambipolar diffusion arises from the inclusion of neutrals as the third fluid. The Hall effect and ambipolar diffusion have been shown to be operational in a region beginning from near the photosphere up to the chromosphere. In a partially ionized plasma, the magnetic induction is subjected to ambipolar diffusion and the Hall drift in addition to the usual resistive dissipation. These nonlinear effects create sharp magnetic structures which then submit themselves to various relaxation mechanisms. A first-principles derivation of these effects in a three-fluid system and an analytic solution to the magnetic induction equation in a stationary state are presented, which in the general case includes the Hall effect, ambipolar diffusion, and ohmic dissipation. The temporal evolution of the magnetic field is then investigated under the combined as well as the individual effects of the Hall drift and ambipolar diffusion to demonstrate the formation of steep magnetic structures and the resultant current sheet formation. These structures have just the right features for the release of magnetic energy into the solar atmosphere.

  5. Particle Acceleration, Magnetic Field Generation, and Emission in Relativistic Shocks

    Science.gov (United States)

    Nishikawa, Ken-IchiI.; Hededal, C.; Hardee, P.; Richardson, G.; Preece, R.; Sol, H.; Fishman, G.

    2004-01-01

    Shock acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (m) code, we have investigated particle acceleration associated with a relativistic jet front propagating through an ambient plasma with and without initial magnetic fields. We find only small differences in the results between no ambient and weak ambient parallel magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates particles perpendicular and parallel to the jet propagation direction. New simulations with an ambient perpendicular magnetic field show the strong interaction between the relativistic jet and the magnetic fields. The magnetic fields are piled up by the jet and the jet electrons are bent, which creates currents and displacement currents. At the nonlinear stage, the magnetic fields are reversed by the current and the reconnection may take place. Due to these dynamics the jet and ambient electron are strongly accelerated in both parallel and perpendicular directions.

  6. Particle Acceleration, Magnetic Field Generation in Relativistic Shocks

    Science.gov (United States)

    Nishikawa, Ken-Ichi; Hardee, P.; Hededal, C. B.; Richardson, G.; Sol, H.; Preece, R.; Fishman, G. J.

    2005-01-01

    Shock acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet front propagating through an ambient plasma with and without initial magnetic fields. We find only small differences in the results between no ambient and weak ambient parallel magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates particles perpendicular and parallel to the jet propagation direction. New simulations with an ambient perpendicular magnetic field show the strong interaction between the relativistic jet and the magnetic fields. The magnetic fields are piled up by the jet and the jet electrons are bent, which creates currents and displacement currents. At the nonlinear stage, the magnetic fields are reversed by the current and the reconnection may take place. Due to these dynamics the jet and ambient electron are strongly accelerated in both parallel and perpendicular directions.

  7. Heat generation and cooling of SSC magnets at high ramp rates

    International Nuclear Information System (INIS)

    Snitchler, G.; Capone, D.; Kovachev, V.; Schermer, R.

    1992-01-01

    This presentation will address a summary of AC loss calculations (SSCL), experimental results on cable samples (Westinghouse STC), short model magnets test results (FNAL, KEK-Japan), and recent full length magnets test data on AC losses and quench current ramp rate sensitivity (FNAL, BNL). Possible sources of the observed enhanced heat generation and quench sensitivity for some magnets will be discussed. A model for cooling conditions of magnet coils considering heat generation distribution and specific anisotropy of the heat transfer will be presented. The crossover contact resistance in cables and curing procedure influence on resistivity, currently under study, will be briefly discussed. (author)

  8. Characteristics of Helicopter-Generated and Volcano-Related Seismic Tremor Signals

    Science.gov (United States)

    Eibl, Eva P. S.; Lokmer, Ivan; Bean, Christopher J.; Akerlie, Eggert; Vogfjörd, Kristin S.

    2017-04-01

    In volcanic environments it is crucial to distinguish between man-made seismic signals and signals created by the volcano. We compare volcanic, seismic signals with helicopter generated, seismic signals recorded in the last 2.5 years in Iceland. In both cases a long-lasting, emergent seismic signal, that can be referred to as seismic tremor, was generated. In the case of a helicopter, the rotating blades generate pressure pulses that travel through the air and excite Rayleigh waves at up to 40 km distance depending on wind speed, wind direction and topographic features. The longest helicopter related seismic signal we recorded was at the order of 40 minutes long. The tremor usually has a fundamental frequency of more than 10 Hz and overtones at integers of the fundamental frequency. Changes in distance lead to either increases or decreases of the frequency due to the Doppler Effect and are strongest for small source-receiver distances. The volcanic tremor signal was recorded during the Bardarbunga eruption at Holuhraun in 2014/15. For volcano-related seismic signals it is usually more difficult to determine the source process that generated the tremor. The pre-eruptive tremor persists for 2 weeks, while the co-eruptive tremor lasted for 6 months. We observed no frequency changes, most energy between 1 and 2 Hz and no or very little energy above 5 Hz. We compare the different characteristics of helicopter-related and volcano-related seismic signals and discuss how they can be distinguished. In addition we discuss how we can determine if a frequency change is related to a moving source or change in repeat time or a change in the geometry of the resonating body.

  9. Simple method for the generation of multiple homogeneous field volumes inside the bore of superconducting magnets.

    Science.gov (United States)

    Chou, Ching-Yu; Ferrage, Fabien; Aubert, Guy; Sakellariou, Dimitris

    2015-07-17

    Standard Magnetic Resonance magnets produce a single homogeneous field volume, where the analysis is performed. Nonetheless, several modern applications could benefit from the generation of multiple homogeneous field volumes along the axis and inside the bore of the magnet. In this communication, we propose a straightforward method using a combination of ring structures of permanent magnets in order to cancel the gradient of the stray field in a series of distinct volumes. These concepts were demonstrated numerically on an experimentally measured magnetic field profile. We discuss advantages and limitations of our method and present the key steps required for an experimental validation.

  10. Techniques for processing remote field eddy current signals from bend regions of steam generator tubes of prototype fast breeder reactor

    Energy Technology Data Exchange (ETDEWEB)

    Thirunavukkarasu, S. [Non Destructive Evaluation Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, TN 603 102 (India); Rao, B.P.C., E-mail: bpcrao@igcar.gov.in [Non Destructive Evaluation Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, TN 603 102 (India); Jayakumar, T.; Raj, Baldev [Non Destructive Evaluation Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, TN 603 102 (India)

    2011-04-15

    Steam generator (SG) is one of the most critical components of sodium cooled fast breeder reactor. Remote field eddy current (RFEC) technique has been chosen for in-service inspection (ISI) of these ferromagnetic SG tubes made of modified 9Cr-1Mo steel (Grade 91). Expansion bends are provided in the SGs to accommodate differential thermal expansion. During ISI using RFEC technique, in expansion bend regions, exciter-receiver coil misalignment, bending stresses, probe wobble and magnetic permeability variations produce disturbing noise hindering detection of defects. Fourier filtering, cross-correlation and wavelet transform techniques have been studied for noise reduction as well as enhancement of RFEC signals of defects in bend regions, having machined grooves and localized defects. Performance of these three techniques has been compared using signal-to-noise ratio (SNR). Fourier filtering technique has shown better performance for noise reduction while cross-correlation technique has resulted in significant enhancement of signals. Wavelet transform technique has shown the combined capability of noise reduction and signal enhancement and resulted in unambiguous detection of 10% of wall loss grooves and localized defects in the bend regions with SNR better than 7 dB.

  11. Magnetic diagnostic of SOL-filaments generated by type I ELMs on JET and ASDEX Upgrade

    DEFF Research Database (Denmark)

    Naulin, Volker; Vianello, N.; Schrittwieser, R.

    2011-01-01

    to a simple model, motivated by observations. A new diagnostic in the form of a reciprocating probe with three magnetic pickup loops was developed for ASDEX Upgrade (AUG). Measurements during the passage of type-I ELM filaments determine the filaments to be in the scrape off layer (SOL) and to carry currents......This contribution is focused on the magnetic signatures of type I ELM filaments. On JET a limited number of high time resolution magnetic coils were used to derive essential ELM filament parameters. The method uses forward modelling and simultaneous fitting of magnetic pickup coil signals...

  12. A robust random number generator based on differential comparison of chaotic laser signals.

    Science.gov (United States)

    Zhang, Jianzhong; Wang, Yuncai; Liu, Ming; Xue, Lugang; Li, Pu; Wang, Anbang; Zhang, Mingjiang

    2012-03-26

    We experimentally realize a robust real-time random number generator by differentially comparing the signal from a chaotic semiconductor laser and its delayed signal through a 1-bit analog-to-digital converter. The probability density distribution of the output chaotic signal based on the differential comparison method possesses an extremely small coefficient of Pearson's median skewness (1.5 × 10⁻⁶), which can yield a balanced random sequence much easily than the previously reported method that compares the signal from the chaotic laser with a certain threshold value. Moveover, we experimently demonstrate that our method can stably generate good random numbers at rates of 1.44 Gbit/s with excellent immunity from external perturbations while the previously reported method fails.

  13. Histopathologic correlation of magnetic resonance imaging signal patterns in a spinal cord injury model.

    Science.gov (United States)

    Weirich, S D; Cotler, H B; Narayana, P A; Hazle, J D; Jackson, E F; Coupe, K J; McDonald, C L; Langford, L A; Harris, J H

    1990-07-01

    Magnetic resonance imaging (MRI) provides a noninvasive method of monitoring the pathologic response to spinal cord injury. Specific MR signal intensity patterns appear to correlate with degrees of improvement in the neurologic status in spinal cord injury patients. Histologic correlation of two types of MR signal intensity patterns are confirmed in the current study using a rat animal model. Adult male Sprague-Dawley rats underwent spinal cord trauma at the midthoracic level using a weight-dropping technique. After laminectomy, 5- and 10-gm brass weights were dropped from designated heights onto a 0.1-gm impounder placed on the exposed dura. Animals allowed to regain consciousness demonstrated variable recovery of hind limb paraplegia. Magnetic resonance images were obtained from 2 hours to 1 week after injury using a 2-tesla MRI/spectrometer. Sacrifice under anesthesia was performed by perfusive fixation; spinal columns were excised en bloc, embedded, sectioned, and observed with the compound light microscope. Magnetic resonance axial images obtained during the time sequence after injury demonstrate a distinct correlation between MR signal intensity patterns and the histologic appearance of the spinal cord. Magnetic resonance imaging delineates the pathologic processes resulting from acute spinal cord injury and can be used to differentiate the type of injury and prognosis.

  14. Generating a synthetic axion signal for cold cark matter axion searches using microwave cavities

    CERN Document Server

    AUTHOR|(CDS)2108502; Miceli, Lino

    2017-01-01

    We demonstrated that an axion signal in a RF resonator can be synthesized and controlled with commercially available instrumentation. Although this signal needs refinements, it can be customized to the needs of a specific cold dark matter axion search experiment. Since the modulator in the setup has arbitrary function generator capabilities, this apparatus is already capable to produce the necessary refinements, for instance a maxwellian line shape.

  15. Modeling SMAP Spacecraft Attitude Control Estimation Error Using Signal Generation Model

    Science.gov (United States)

    Rizvi, Farheen

    2016-01-01

    Two ground simulation software are used to model the SMAP spacecraft dynamics. The CAST software uses a higher fidelity model than the ADAMS software. The ADAMS software models the spacecraft plant, controller and actuator models, and assumes a perfect sensor and estimator model. In this simulation study, the spacecraft dynamics results from the ADAMS software are used as CAST software is unavailable. The main source of spacecraft dynamics error in the higher fidelity CAST software is due to the estimation error. A signal generation model is developed to capture the effect of this estimation error in the overall spacecraft dynamics. Then, this signal generation model is included in the ADAMS software spacecraft dynamics estimate such that the results are similar to CAST. This signal generation model has similar characteristics mean, variance and power spectral density as the true CAST estimation error. In this way, ADAMS software can still be used while capturing the higher fidelity spacecraft dynamics modeling from CAST software.

  16. Influence of sodium deposits in steam generator tubes on remote field eddy current signals

    Energy Technology Data Exchange (ETDEWEB)

    Thirunavukkarasu, S. [EMSI Section, NDE Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India); Rao, B.P.C. [EMSI Section, NDE Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India)], E-mail: bpcrao@igcar.gov.in; Vaidyanathan, S.; Jayakumar, T.; Raj, Baldev [EMSI Section, NDE Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India)

    2008-04-15

    The presence of sodium deposits in defective regions of steam generator (SG) tubes of fast-breeder reactors is expected to influence the remote field eddy current (RFEC) signals. By exposing five SG tubes having uniform wall loss grooves to a sodium environment in a specially designed test vessel, changes in the shape of RFEC signals were observed and it was possible to approximate the volume of sodium deposited in defects. An invariant signal parameter was determined for quantitative characterization of defects despite the presence of sodium in the defects.

  17. A New Second-Order Generalized Integrator Based Quadrature Signal Generator With Enhanced Performance

    DEFF Research Database (Denmark)

    Xin, Zhen; Qin, Zian; Lu, Minghui

    2016-01-01

    Due to the simplicity and flexibility of the structure of the Second-Order Generalized Integrator based Quadrature Signal Generator (SOGI-QSG), it has been widely used over the past decade for many applications such as frequency estimation, grid synchronization, and harmonic extraction. However......, the SOGI-QSG will produce errors when its input signal contains a dc component or harmonic components with unknown frequencies. The accuracy of the signal detection methods using it may hence be compromised. To overcome the drawback, the First-Order System (FOS) concept is first used to illustrate...

  18. Turbulence-driven anisotropic electron tail generation during magnetic reconnection

    Science.gov (United States)

    DuBois, A. M.; Scherer, A.; Almagri, A. F.; Anderson, J. K.; Pandya, M. D.; Sarff, J. S.

    2018-05-01

    Magnetic reconnection (MR) plays an important role in particle transport, energization, and acceleration in space, astrophysical, and laboratory plasmas. In the Madison Symmetric Torus reversed field pinch, discrete MR events release large amounts of energy from the equilibrium magnetic field, a fraction of which is transferred to electrons and ions. Previous experiments revealed an anisotropic electron tail that favors the perpendicular direction and is symmetric in the parallel. New profile measurements of x-ray emission show that the tail distribution is localized near the magnetic axis, consistent modeling of the bremsstrahlung emission. The tail appears first near the magnetic axis and then spreads radially, and the dynamics in the anisotropy and diffusion are discussed. The data presented imply that the electron tail formation likely results from a turbulent wave-particle interaction and provides evidence that high energy electrons are escaping the core-localized region through pitch angle scattering into the parallel direction, followed by stochastic parallel transport to the plasma edge. New measurements also show a strong correlation between high energy x-ray measurements and tearing mode dynamics, suggesting that the coupling between core and edge tearing modes is essential for energetic electron tail formation.

  19. Octupolar out-of-plane magnetic field structure generation during collisionless magnetic reconnection in a stressed X-point collapse

    Energy Technology Data Exchange (ETDEWEB)

    Graf von der Pahlen, J.; Tsiklauri, D. [School of Physics and Astronomy, Queen Mary University of London, London E1 4NS (United Kingdom)

    2014-06-15

    The out-of-plane magnetic field, generated by fast magnetic reconnection, during collisionless, stressed X-point collapse, was studied with a kinetic, 2.5D, fully electromagnetic, relativistic particle-in-cell numerical code, using both closed (flux conserving) and open boundary conditions on a square grid. It was discovered that the well known quadrupolar structure in the out-of-plane magnetic field gains four additional regions of opposite magnetic polarity, emerging near the corners of the simulation box, moving towards the X-point. The emerging, outer, magnetic field structure has opposite polarity to the inner quadrupolar structure, leading to an overall octupolar structure. Using Ampere's law and integrating electron and ion currents, defined at grid cells, over the simulation domain, contributions to the out-of-plane magnetic field from electron and ion currents were determined. The emerging regions of opposite magnetic polarity were shown to be the result of ion currents. Magnetic octupolar structure is found to be a signature of X-point collapse, rather than tearing mode, and factors relating to potential discoveries in experimental scenarios or space-craft observations are discussed.

  20. Amplitude inversion of the 2D analytic signal of magnetic anomalies through the differential evolution algorithm

    Science.gov (United States)

    Ekinci, Yunus Levent; Özyalın, Şenol; Sındırgı, Petek; Balkaya, Çağlayan; Göktürkler, Gökhan

    2017-12-01

    In this work, analytic signal amplitude (ASA) inversion of total field magnetic anomalies has been achieved by differential evolution (DE) which is a population-based evolutionary metaheuristic algorithm. Using an elitist strategy, the applicability and effectiveness of the proposed inversion algorithm have been evaluated through the anomalies due to both hypothetical model bodies and real isolated geological structures. Some parameter tuning studies relying mainly on choosing the optimum control parameters of the algorithm have also been performed to enhance the performance of the proposed metaheuristic. Since ASAs of magnetic anomalies are independent of both ambient field direction and the direction of magnetization of the causative sources in a two-dimensional (2D) case, inversions of synthetic noise-free and noisy single model anomalies have produced satisfactory solutions showing the practical applicability of the algorithm. Moreover, hypothetical studies using multiple model bodies have clearly showed that the DE algorithm is able to cope with complicated anomalies and some interferences from neighbouring sources. The proposed algorithm has then been used to invert small- (120 m) and large-scale (40 km) magnetic profile anomalies of an iron deposit (Kesikköprü-Bala, Turkey) and a deep-seated magnetized structure (Sea of Marmara, Turkey), respectively to determine depths, geometries and exact origins of the source bodies. Inversion studies have yielded geologically reasonable solutions which are also in good accordance with the results of normalized full gradient and Euler deconvolution techniques. Thus, we propose the use of DE not only for the amplitude inversion of 2D analytical signals of magnetic profile anomalies having induced or remanent magnetization effects but also the low-dimensional data inversions in geophysics. A part of this paper was presented as an abstract at the 2nd International Conference on Civil and Environmental Engineering, 8

  1. Studies of Current Induced Magnetization reversal and generation of GHz radiation in magnetic nanopillars

    Science.gov (United States)

    Alhajdarwish, Mustafa Yousef

    This thesis describes studies of two phenomena: Current-Induced Magnetization Switching (CIMS), and Current-Induced Generation of GHz Radiation. The CIMS part contains results of measurements of current-perpendicular-to-plane (CPP) magnetoresistance (MR) and CIMS behavior on Ferromagnetic/Nonmetal/Ferromagnetic (F1/N/F2) nanopillars. Judicious combinations of F1 and F2 metals with different bulk scattering asymmetries, and with F1/N and N/F2 interfaces having different interfacial scattering asymmetries, are shown to be able to controllably, and independently, 'invert' both the CPP-MR and the CIMS. In 'normal' CPP-MR, R(AP) > R(P), where R(AP) and R(P) are the nanopillar resistances for the anti-parallel (AP) and parallel (P) orientations of the Fi and F2 magnetic moments. In 'inverse' CPP-MR, R(P) > R(AP). In 'normal' CIMS, positive current switches the nanopillar from the P to the AP state. In 'inverse' CIMS, positive current switches the nanopillar from AP to P. All four possible combinations of CPP-MR and CIMS---(a) 'normal'-'normal', (b) 'normal'- 'inverse', 'inverse'-'normal', and (d) 'inverse'-'inverse' are shown and explained. These results rule out the self-Oersted field as the switching source, since the direction of that field is independent of the bulk or interfacial scattering asymmetries. Successful use of impurities to reverse the bulk scattering asymmetry shows the importance of scattering off of impurities within the bulk F1 and F2 metals---i.e. that the transport must be treated as 'diffusive' rather than 'ballistic'. The GHz studies consist of five parts: (1) designing a sample geometry that allows reliable measurements; (2) making nanopillar samples with this geometry; (3) constructing a system for measuring frequencies up to 12 GHz and measuring current-driven GHz radiation data with it; (4) showing 'scaling' behavior of GHz data with the critical fields and currents for nominally identical (but actually slightly different) samples, and

  2. Evanescent magnetic field effects on entropy generation at the onset ...

    Indian Academy of Sciences (India)

    This paper numerically investigates the effect of an externally evanescent magnetic field on total entropy generation in a fluid enclosed in a square cavity by using a control volume finite element method to solve the conservation equations at Prandtl number of 0·71. The values of relaxation time of the magnetic field are ...

  3. Experimental and theoretical study of helical explosive electrical current generators with magnetic field compression

    International Nuclear Information System (INIS)

    Antoni, Bernard; Nazet, Christian.

    1975-07-01

    A generator of electrical energy in which magnetic field compression is achieved by a solid explosive is described. The magnetic flux losses have been calculated for generators of various configurations by the skin depth concept. Calculations take the Joule heating of conductors into account. In helical generators the magnetic flux losses are higher than those calculated by considering diffusion only. Additional losses approximately as important as diffusion losses have already been observed elsewhere on similar devices. Detailed calculations of the motion of the explosively driven inner conductor show that losses come from the jumps encountered by sliding contact moving along the helix. The jumps are caused by little geometrical defects and the consequence on losses is strongly dependent on current intensity. The jumps decrease when the pitch of helix increases. The jumps are detrimental to the efficient use of the explosive energy. With helical generators only 5% of the energy is transferred into magnetic energy [fr

  4. Ultra-low power transmitter for encoding non-MR signals in Magnetic Resonance (MR) recordings

    DEFF Research Database (Denmark)

    Petersen, Jan Raagaard; Pedersen, Jan Ole; Zhurbenko, Vitaliy

    collection of data from non-MRI sensors. The transmitter consumes only 1.3mW while transmitting 2.7µW at 120MHz with high frequency stability. The presented design is useful in low power applications requiring high frequency stability and is intended for wireless transmission of non-MR signal recordings......Advancing Magnetic Resonance Imaging (MRI) technology requires integration of the MRI scanners with sensors and systems for monitoring various non-MRI signals. In this paper, we present design and integration of a low power AM radio transmitter into a 3T MRI scanner, which can be used for efficient...

  5. Particle Acceleration, Magnetic Field Generation and Emission from Relativistic Jets and Supernova Remnants

    Science.gov (United States)

    Nishikawa, K.-I.; Hartmann, D. H.; Hardee, P.; Hededal, C.; Mizunno, Y.; Fishman, G. J.

    2006-01-01

    We performed numerical simulations of particle acceleration, magnetic field generation, and emission from shocks in order to understand the observed emission from relativistic jets and supernova remnants. The investigation involves the study of collisionless shocks, where the Weibel instability is responsible for particle acceleration as well as magnetic field generation. A 3-D relativistic particle-in-cell (RPIC) code has been used to investigate the shock processes in electron-positron plasmas. The evolution of theWeibe1 instability and its associated magnetic field generation and particle acceleration are studied with two different jet velocities (0 = 2,5 - slow, fast) corresponding to either outflows in supernova remnants or relativistic jets, such as those found in AGNs and microquasars. Slow jets have intrinsically different structures in both the generated magnetic fields and the accelerated particle spectrum. In particular, the jet head has a very weak magnetic field and the ambient electrons are strongly accelerated and dragged by the jet particles. The simulation results exhibit jitter radiation from inhomogeneous magnetic fields, generated by the Weibel instability, which has different spectral properties than standard synchrotron emission in a homogeneous magnetic field.

  6. Permanent-Magnet Motors and Generators for Aircraft

    Science.gov (United States)

    Echolds, E. F.

    1983-01-01

    Electric motors and generators that use permarotating machinery, but aspects of control and power conditioning are also considered. The discussion is structured around three basic areas: rotating machine design considerations presents various configuration and material options, generator applications provides insight into utilization areas and shows actual hardware and test results, and motor applications provides the same type of information for drive systems.

  7. High magnetic field multipoles generated by superconductor magnetization within a set of nested superconducting correction coils

    International Nuclear Information System (INIS)

    Green, M.A.

    1990-04-01

    Correction elements in colliding beam accelerators such as the SSC can be the source of undesirable higher magnetic field multipoles due to magnetization of the superconductor within the corrector. Quadrupole and sextupole correctors located within the main dipole will produce sextupole and decapole due to magnetization of the superconductor within the correction coils. Lumped nested correction coils can produce a large number of skew and normal magnetization multipoles which may have an adverse effect on a stored beam at injection into a high energy colliding beam machine such as the SSC. 6 refs., 2 figs., 2 tabs

  8. Effects of external magnetic field on harmonics generated in laser interaction with underdense plasma

    International Nuclear Information System (INIS)

    Faghihi-Nik, M.; Ghorbanalilu, M.; Shokri, B.

    2010-01-01

    Complete text of publication follows. Generation of harmonic radiation is an important subject of laser plasma interaction and attracts great attention due to a wide range of applications. It has been seen that intense electromagnetic and quasi-static transverse magnetic fields are generated in laser plasma interaction. An extremely intense magnetic field (up to hundreds of MG) has been observed by experimental measurements in interaction of short laser pulses with plasma. These self-generated or applied magnetic fields affect the propagation of the laser pulses. In most laser interactions with homogeneous plasma, odd harmonics of laser frequency are generated. In this paper, we point out the possibility of even harmonics generation when a linearly polarized laser beam propagates in homogeneous plasma in the presence of a transverse magnetic field. It is shown that applying external field induces a transverse current density oscillating twice of the laser field which leds to generation of second harmonic radiation. This current density is derived using the perturbation method, and the steady state amplitude of the second harmonic obtained by solution of the wave equation. By the same procedure the current density and then the steady state amplitude of higher order harmonics are calculated. The efficiency of harmonic generation (the ratio of harmonic power to incident power) is a drastically function of the strength of external magnetic field. It is found that the efficiency of even harmonics is zero in the absence of magnetic field and increases as the magnetic field is increased. For odd harmonics, applying the external magnetic field enhances the generated harmonics as well. The conversion efficiency also increases with increase in plasma density and intensity of the laser beam.

  9. Parametric Amplification Protocol for Frequency-Modulated Magnetic Resonance Force Microscopy Signals

    Science.gov (United States)

    Harrell, Lee; Moore, Eric; Lee, Sanggap; Hickman, Steven; Marohn, John

    2011-03-01

    We present data and theoretical signal and noise calculations for a protocol using parametric amplification to evade the inherent tradeoff between signal and detector frequency noise in force-gradient magnetic resonance force microscopy signals, which are manifested as a modulated frequency shift of a high- Q microcantilever. Substrate-induced frequency noise has a 1 / f frequency dependence, while detector noise exhibits an f2 dependence on modulation frequency f . Modulation of sample spins at a frequency that minimizes these two contributions typically results in a surface frequency noise power an order of magnitude or more above the thermal limit and may prove incompatible with sample spin relaxation times as well. We show that the frequency modulated force-gradient signal can be used to excite the fundamental resonant mode of the cantilever, resulting in an audio frequency amplitude signal that is readily detected with a low-noise fiber optic interferometer. This technique allows us to modulate the force-gradient signal at a sufficiently high frequency so that substrate-induced frequency noise is evaded without subjecting the signal to the normal f2 detector noise of conventional demodulation.

  10. Clinical significance of pontine high signals identified on magnetic resonance imaging

    International Nuclear Information System (INIS)

    Watanabe, Masaki; Takahashi, Akira; Arahata, Yutaka; Motegi, Yoshimasa; Furuse, Masahiro.

    1993-01-01

    Spin-echo magnetic resonance imaging (MRI) was evaluated to 530 cases in order to investigate the clinical significance of pontine high signals. The subjects comprised 109 cases of pontine infarction with high signal on T 2 -weighted image and low signal on T 1 -weighted image (PI group), 145 of pontine high signal with high signal on T 2 -weighted image but normal signal on T 1 -weighted image (PH group) and 276 of age-matched control without abnormality either on T 1 or T 2 -weighted images (AC group). Subjective complaints such as vertigo-dizziness were more frequent in the PH group than in the PI group. In both PI and groups, periventricular hyperintensity as well as subcortical high signals in the supratentorium were more severe than in the AC group. These degrees were higher in the PI group than in the PH group. In conclusion, PH as well as PI may result from diffuse arteriosclerosis and PH is considered to be an early finding of pontine ischemia. (author)

  11. Clinical significance of pontine high signals identified on magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Masaki; Takahashi, Akira (Nagoya Univ. (Japan). Faculty of Medicine); Arahata, Yutaka; Motegi, Yoshimasa; Furuse, Masahiro

    1993-07-01

    Spin-echo magnetic resonance imaging (MRI) was evaluated to 530 cases in order to investigate the clinical significance of pontine high signals. The subjects comprised 109 cases of pontine infarction with high signal on T[sub 2]-weighted image and low signal on T[sub 1]-weighted image (PI group), 145 of pontine high signal with high signal on T[sub 2]-weighted image but normal signal on T[sub 1]-weighted image (PH group) and 276 of age-matched control without abnormality either on T[sub 1] or T[sub 2]-weighted images (AC group). Subjective complaints such as vertigo-dizziness were more frequent in the PH group than in the PI group. In both PI and groups, periventricular hyperintensity as well as subcortical high signals in the supratentorium were more severe than in the AC group. These degrees were higher in the PI group than in the PH group. In conclusion, PH as well as PI may result from diffuse arteriosclerosis and PH is considered to be an early finding of pontine ischemia. (author).

  12. Edge detection of magnetic anomalies using analytic signal of tilt angle (ASTA)

    Science.gov (United States)

    Alamdar, K.; Ansari, A. H.; Ghorbani, A.

    2009-04-01

    Magnetic is a commonly used geophysical technique to identify and image potential subsurface targets. Interpretation of magnetic anomalies is a complex process due to the superposition of multiple magnetic sources, presence of geologic and cultural noise and acquisition and positioning error. Both the vertical and horizontal derivatives of potential field data are useful; horizontal derivative, enhance edges whereas vertical derivative narrow the width of anomaly and so locate source bodies more accurately. We can combine vertical and horizontal derivative of magnetic field to achieve analytic signal which is independent to body magnetization direction and maximum value of this lies over edges of body directly. Tilt angle filter is phased-base filter and is defined as angle between vertical derivative and total horizontal derivative. Tilt angle value differ from +90 degree to -90 degree and its zero value lies over body edge. One of disadvantage of this filter is when encountering with deep sources the detected edge is blurred. For overcome this problem many authors introduced new filters such as total horizontal derivative of tilt angle or vertical derivative of tilt angle which Because of using high-order derivative in these filters results may be too noisy. If we combine analytic signal and tilt angle, a new filter termed (ASTA) is produced which its maximum value lies directly over body edge and is easer than tilt angle to delineate body edge and no complicity of tilt angle. In this work new filter has been demonstrated on magnetic data from an area in Sar- Cheshme region in Iran. This area is located in 55 degree longitude and 32 degree latitude and is a copper potential region. The main formation in this area is Andesith and Trachyandezite. Magnetic surveying was employed to separate the boundaries of Andezite and Trachyandezite from adjacent area. In this regard a variety of filters such as analytic signal, tilt angle and ASTA filter have been applied which

  13. Initial assessment of the COMPASS/BeiDou-3: new-generation navigation signals

    Science.gov (United States)

    Zhang, Xiaohong; Wu, Mingkui; Liu, Wanke; Li, Xingxing; Yu, Shun; Lu, Cuixian; Wickert, Jens

    2017-10-01

    The successful launch of five new-generation experimental satellites of the China's BeiDou Navigation Satellite System, namely BeiDou I1-S, I2-S, M1-S, M2-S, and M3-S, marks a significant step in expanding BeiDou into a navigation system with global coverage. In addition to B1I (1561.098 MHz) and B3I (1269.520 MHz) signals, the new-generation BeiDou-3 experimental satellites are also capable of transmitting several new navigation signals in space, namely B1C at 1575.42 MHz, B2a at 1176.45 MHz, and B2b at 1207.14 MHz. For the first time, we present an initial characterization and performance assessment for these new-generation BeiDou-3 satellites and their signals. The L1/L2/L5 signals from GPS Block IIF satellites, E1/E5a/E5b signals from Galileo satellites, and B1I/B2I/B3I signals from BeiDou-2 satellites are also evaluated for comparison. The characteristics of the B1C, B1I, B2a, B2b, and B3I signals are evaluated in terms of observed carrier-to-noise density ratio, pseudorange multipath and noise, triple-frequency carrier-phase ionosphere-free and geometry-free combination, and double-differenced carrier-phase and code residuals. The results demonstrate that the observational quality of the new-generation BeiDou-3 signals is comparable to that of GPS L1/L2/L5 and Galileo E1/E5a/E5b signals. However, the analysis of code multipath shows that the elevation-dependent code biases, which have been previously identified to exist in the code observations of the BeiDou-2 satellites, seem to be not obvious for all the available signals of the new-generation BeiDou-3 satellites. This will significantly benefit precise applications that resolve wide-lane ambiguity based on Hatch-Melbourne-Wübbena linear combinations and other applications such as single-frequency precise point positioning (PPP) based on the ionosphere-free code-carrier combinations. Furthermore, with regard to the triple-frequency carrier-phase ionosphere-free and geometry-free combination, it is found

  14. Diagnostic of corrosion defects in steam generator tubes using advanced signal processing from Eddy current testing

    International Nuclear Information System (INIS)

    Formigoni, Andre L.; Lopez, Luiz A.N.M.; Ting, Daniel K.S.

    2009-01-01

    Recently, the Brazilian Angra I PWR nuclear power plant went into a programmed shutdown for substitution of its Steam Generator (SG) which life was shortened due to stress corrosion in its tubes. The total cost of investment were around R$724 million. The signals generated during an Eddy-current Testing (ECT) inspection in SG tubes of nuclear plant allows for the localization and dimensioning of defects in the tubes. The defects related with corrosion generate complex signals that are difficult to analyze and are the most common cause in SG replacement in nuclear power plants around the world. The objective of this paper is the development of a methodology that allows for the characterization of corrosion signals by ECT inspections applied in the heat exchangers tubes of SG of a nuclear power plant. In this present work, the aim is to investigate distributed type defects by inducing controlled corrosion in sample tubes of different materials The ECT signals obtained from these samples tubes with corrosion implanted, will be analyzed using Zetec ECT equipment, the MIZ-17ET and its probes. The data acquisition will use a NI PC A/D CARD 700 card and the LabVIEW program. Subsequently, we will apply mathematical tools for signal processing like time windowed Fast Fourier transforms and Wavelets transforms, in MATLAB platform, which will allow effectiveness to remove the noises and to extract representative characteristics for the defect being analyzed. Previously obtained results as well as the proposal for the future work will be presented. (author)

  15. Detection of electron magnetic circular dichroism signals under zone axial diffraction geometry

    Energy Technology Data Exchange (ETDEWEB)

    Song, Dongsheng [National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE) and The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Rusz, Jan [Department of Physics and Astronomy, Uppsala University, Box 516, S-751 20 Uppsala (Sweden); Cai, Jianwang [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Zhu, Jing, E-mail: jzhu@mail.tsinghua.edu.cn [National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE) and The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2016-10-15

    EMCD (electron magnetic circular dichroism) technique provides us a new opportunity to explore magnetic properties in the transmission electron microscope. However, specific diffraction geometry is the major limitation. Only the two-beam and three-beam case are demonstrated in the experiments until now. Here, we present the more general case of zone axial (ZA) diffraction geometry through which the EMCD signals can be detected even with the very strong sensitivity to dynamical diffraction conditions. Our detailed calculations and well-controlled diffraction conditions lead to experiments in agreement with theory. The effect of dynamical diffraction conditions on EMCD signals are discussed both in theory and experiments. Moreover, with the detailed analysis of dynamical diffraction effects, we experimentally obtain the separate EMCD signals for each crystallographic site in Y{sub 3}Fe{sub 5}O{sub 12}, which is also applicable for other materials and cannot be achieved by site-specific EMCD and XMCD technique directly. Our work extends application of more general diffraction geometries and will further promote the development of EMCD technique. - Highlights: • The zone axial (ZA) diffraction geometry is presented for EMCD technique. • The detailed calculations for EMCD signals under ZA case are conducted. • The EMCD signals are obtained under the ZA case in the experiments. • The effect of dynamical effect on EMCD signals under ZA case is discussed. • Site-specific EMCD signals of Fe in Y{sub 3}Fe{sub 5}O{sub 12} are obtained by specific ZA conditions.

  16. Cultural Transmission and Evolution of Melodic Structures in Multi-generational Signaling Games.

    Science.gov (United States)

    Lumaca, Massimo; Baggio, Giosuè

    2017-01-01

    It has been proposed that languages evolve by adapting to the perceptual and cognitive constraints of the human brain, developing, in the course of cultural transmission, structural regularities that maximize or optimize learnability and ease of processing. To what extent would perceptual and cognitive constraints similarly affect the evolution of musical systems? We conducted an experiment on the cultural evolution of artificial melodic systems, using multi-generational signaling games as a laboratory model of cultural transmission. Signaling systems, using five-tone sequences as signals, and basic and compound emotions as meanings, were transmitted from senders to receivers along diffusion chains in which the receiver in each game became the sender in the next game. During transmission, structural regularities accumulated in the signaling systems, following principles of proximity, symmetry, and good continuation. Although the compositionality of signaling systems did not increase significantly across generations, we did observe a significant increase in similarity among signals from the same set. We suggest that our experiment tapped into the cognitive and perceptual constraints operative in the cultural evolution of musical systems, which may differ from the mechanisms at play in language evolution and change.

  17. Increased Efficiency of a Permanent Magnet Synchronous Generator through Optimization of NdFeB Magnet Arrays

    Science.gov (United States)

    Khazdozian, Helena; Hadimani, Ravi; Jiles, David

    2014-03-01

    The United States is currently dependent on fossil fuels for the majority of its energy needs, which has many negative consequences such as climate change. Wind turbines present a viable alternative, with the highest energy return on investment among even fossil fuel generation. Traditional commercial wind turbines use an induction generator for energy conversion. However, induction generators require a gearbox to increase the rotational speed of the drive shaft. These gearboxes increase the overall cost of the wind turbine and account for about 35 percent of reported wind turbine failures. Direct drive permanent magnet synchronous generators (PMSGs) offer an alternative to induction generators which eliminate the need for a gearbox. Yet, PMSGs can be more expensive than induction generators at large power output due to their size and weight. To increase the efficiency of PMSGs, the geometry and configuration of NdFeB permanent magnets were investigated using finite element techniques. The optimized design of the PMSG increases flux density and minimizes cogging torque with NdFeB permanent magnets of a reduced volume. These factors serve to increase the efficiency and reduce the overall cost of the PMSG. This work is supported by a National Science Foundation IGERT fellowship and the Barbara and James Palmer Endowment at the Department of Electrical and Computer Engineering of Iowa State University.

  18. Analysis and software development for controlling RF signal generator proton cyclotron Decy-13 using DDS Technique

    International Nuclear Information System (INIS)

    Prajitno

    2012-01-01

    Analysis and manufacture of computer programs for controlling the signal generator Radio Frequency (RF) proton cyclotron Decy-13 have been done. Signal generator uses a technique Direct Digital Synthesiser (DDS) which settings must be done with software. Signal generator consists of electronic modules which are: DDS, micro controller ATmega16, amplifier RF.dan ± 12 Vdc power supply. Function of the programs that have been made is to set the DDS module, namely: output frequency, step frequency and phase settings and displays the operating parameters of the DDS and the RF amplifier on the monitor screen. Computer programs created with Visual Basic and has been tested to control the RF signal generator to send data serially to the module ATmega16 and receives data to be displayed on the monitor screen. Testing sending and receiving data is done with a baudrate of 1200 bps to 19200 bps with perfect results. Computer programs that have been made equipped with a Human Machine Interface to provide values parameter input on the DDS operations. (author)

  19. Comparative Performance Evaluation of Orthogonal-Signal-Generators-Based Single-Phase PLL Algorithms

    DEFF Research Database (Denmark)

    Han, Yang; Luo, Mingyu; Zhao, Xin

    2016-01-01

    The orthogonal signal generator based phase-locked loops (OSG-PLLs) are among the most popular single-phase PLLs within the areas of power electronics and power systems, mainly because they are often easy to be implement and offer a robust performance against the grid disturbances. The main aim o...

  20. High-speed ultra-wideband wireless signals over fiber systems: Photonic generation and DSP detection

    DEFF Research Database (Denmark)

    Yu, Xianbin; Gibbon, Timothy Braidwood; Tafur Monroy, Idelfonso

    2009-01-01

    We firstly review the efforts in the literature on UWB over-fiber systems. Secondly, we present experimental results on photonic generation of high-speed UWB signals by both direct modulation and external optical injecting an uncooled semiconductor laser. Furthermore, we introduce the use of digi...

  1. Design, Prototyping, and Analysis of a Novel Modular Permanent Magnet Transverse Flux Disk Generator

    DEFF Research Database (Denmark)

    Hosseini, Seyedmohsen; Moghani, Javad Shokrollahi; Ershad, Nima Farrokhzad

    2011-01-01

    by circular flat shaped Nd-Fe-B permanent magnets. First, a typical low power generator is designed, and then partially optimized. The optimization objective is to find an inner radius which maximizes the power factor, the output power to mass ratio and the efficiency. The generator equivalent circuit......This paper presents the design, prototyping, and analysis of a novel modular transverse flux permanent magnet disk generator. The disk-shaped structure simplifies the construction procedure by using laminated steel sheets. To reduce output harmonics, the excitation of the generator is done...... parameters are computed by three dimensional finite element analyses. The simulation results show that the power factor of the proposed structure is considerably greater than the power factor previously reported for other transverse flux permanent magnet generator structures. To verify the simulation results...

  2. Generation of a Magnetic Field by Dynamo Action in a Turbulent Flow of Liquid Sodium

    International Nuclear Information System (INIS)

    Monchaux, R.; Chiffaudel, A.; Daviaud, F.; Dubrulle, B.; Gasquet, C.; Marie, L.; Ravelet, F.; Berhanu, M.; Fauve, S.; Mordant, N.; Petrelis, F.; Bourgoin, M.; Moulin, M.; Odier, Ph.; Pinton, J.-F.; Volk, R.

    2007-01-01

    We report the observation of dynamo action in the von Karman sodium experiment, i.e., the generation of a magnetic field by a strongly turbulent swirling flow of liquid sodium. Both mean and fluctuating parts of the field are studied. The dynamo threshold corresponds to a magnetic Reynolds number R m ∼30. A mean magnetic field of the order of 40 G is observed 30% above threshold at the flow lateral boundary. The rms fluctuations are larger than the corresponding mean value for two of the components. The scaling of the mean square magnetic field is compared to a prediction previously made for high Reynolds number flows

  3. Axis-encircling electron beam generation using a smooth magnetic cusp for gyrodevices

    International Nuclear Information System (INIS)

    He, W.; Whyte, C. G.; Rafferty, E. G.; Cross, A. W.; Phelps, A. D. R.; Ronald, K.; Young, A. R.; Robertson, C. W.; Speirs, D. C.; Rowlands, D. H.

    2008-01-01

    The generation of an annular-shaped axis-encircling electron beam using a smooth magnetic cusp was studied through numerical simulations and experiments for harmonic operation of a gyrodevice. Two magnetic coils were used to form a magnetic cusp located just downstream from the velvet cathode of an accelerator diode. An electron beam of current 34 A and voltage 130 kV with an adjustable velocity ratio α up to 1.2 was fully transported to the downstream uniform magnetic field region and used to drive a gyrotron traveling wave amplifier into saturation

  4. Generation of a cold, intense relativistic electron beam using a magnetized foilless diode

    International Nuclear Information System (INIS)

    Sheffield, R.L.; Montgomery, M.D.; Parker, J.V.; Riepe, K.B.; Singer, S.

    1982-01-01

    An annular electron beam with less than 30 mrad of angular velocity spread, a radius of 1 cm, and a current density exceeding 0.4 MA/cm 2 has been generated with a magnetized foilless diode. The diode current loss is limited to less than a few percent by careful design of the tapered transition region connecting a self-magnetically insulated vacuum transmission line to the externally magnetized foilless diode. Details of the transition section design and operating characteristics of the electron beam generator are given

  5. Analysis on the roundness of bulb turbine generator based on the unbalanced magnetic

    International Nuclear Information System (INIS)

    Li, Z G; Yang, F Y; Chen, J H; Si, G L

    2012-01-01

    Because of design, manufacture, installation and operation, there are some relatively eccentric in bulb tubular turbine units under operating condition. It easily caused uneven air gap, unbalanced magnetic field, unbalanced magnetic pull and torque. It could also increase the bending and torsion vibration of generator,at the same time, the roundness of stator and rotor would be aggravated which often caused by accidents such as generator sweep chamber. In this paper, basing on the design, installation and operation experience, the reasons of the unbalanced magnetic pull, mechanism and operation research were analyzed by theoretical calculation and the prototype test.

  6. Halbach array-based design and simulation of disc coreless permanen-magnet integrated starter generator

    Science.gov (United States)

    Li, Y. B.; Yang, Z. X.; Chen, W.; He, Q. Y.

    2017-11-01

    The functional performance, such as magnetic flux leakage, power density and efficiency, is related to the structural characteristics and design technique for the disc permanent magnet synchronous generators (PMSGs). Halbach array theory-based magnetic circuit structure is developed, and Maxwell3D simulation analysis approach of PMSG is proposed in this paper for integrated starter generator (ISG). The magnetization direction of adjacent permanent magnet is organized in difference of 45 degrees for focusing air gap side, and improving the performance of the generator. The magnetic field distribution and functional performance in load and/or unload conditions are simulated by Maxwell3D module. The proposed approach is verified by simulation analysis, the air gap flux density is 0.66T, and the phase voltage curve has the characteristics of a preferable sinusoidal wave and the voltage amplitude 335V can meet the design requirements while the disc coreless PMSG is operating at rated speed. And the developed magnetic circuit structure can be used for engineering design of the disc coreless PMSG to the integrated starter generator.

  7. Heat generation in agglomerated ferrite nanoparticles in an alternating magnetic field

    International Nuclear Information System (INIS)

    Lima, E Jr; De Biasi, E; Mansilla, M Vasquez; Saleta, M E; Granada, M; Troiani, H E; Zysler, R D; Effenberger, F B; Rossi, L M; Rechenberg, H R

    2013-01-01

    The role of agglomeration and magnetic interparticle interactions in heat generation of magnetic ferrofluids in an ac magnetic field is still unclear, with apparent discrepancy between the results presented in the literature. In this work, we measured the heat generating capability of agglomerated ferrite nanoparticles in a non-invasive ac magnetic field with f = 100 kHz and H 0 = 13 kA m -1 . The nanoparticles were morphologically and magnetically characterized, and the specific absorption rate (SAR) for our ac magnetic field presents a clear dependence on the diameter of the nanoparticles, with a maximum SAR = 48 W g -1 for 15 nm. Our agglomerated nanoparticles have large hydrodynamic diameters, thus the mechanical relaxation can be neglected as a heat generation mechanism. Therefore, we present a model that simulates the SAR dependence of the agglomerated samples on the diameter of the nanoparticles based on the hysteresis losses that is valid for the non-linear region (with H 0 comparable to the anisotropy field). Our model takes into account the magnetic interactions among the nanoparticles in the agglomerate. For comparison, we also measured the SAR of non-agglomerated nanoparticles in a similar diameter range, in which Néel and Brown relaxations dominate the heat generation.

  8. Role of particle masses in the magnetic field generation driven by the parity violating interaction

    Energy Technology Data Exchange (ETDEWEB)

    Dvornikov, Maxim, E-mail: maxdvo@izmiran.ru [Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation (IZMIRAN), 142190 Troitsk, Moscow (Russian Federation); Physics Faculty, National Research Tomsk State University, 36 Lenin Avenue, 634050 Tomsk (Russian Federation); II. Institute for Theoretical Physics, University of Hamburg, 149 Luruper Chaussee, D-22761 Hamburg (Germany)

    2016-09-10

    Recently the new model for the generation of strong large scale magnetic fields in neutron stars, driven by the parity violating interaction, was proposed. In this model, the magnetic field instability results from the modification of the chiral magnetic effect in presence of the electroweak interaction between ultrarelativistic electrons and nucleons. In the present work we study how a nonzero mass of charged particles, which are degenerate relativistic electrons and nonrelativistic protons, influences the generation of the magnetic field in frames of this approach. For this purpose we calculate the induced electric current of these charged particles, electroweakly interacting with background neutrons and an external magnetic field, exactly accounting for the particle mass. This current is calculated by two methods: using the exact solution of the Dirac equation for a charged particle in external fields and computing the polarization operator of a photon in matter composed of background neutrons. We show that the induced current is vanishing in both approaches leading to the zero contribution of massive particles to the generated magnetic field. We discuss the implication of our results for the problem of the magnetic field generation in compact stars.

  9. A technique for the deconvolution of the pulse shape of acoustic emission signals back to the generating defect source

    International Nuclear Information System (INIS)

    Houghton, J.R.; Packman, P.F.; Townsend, M.A.

    1976-01-01

    Acoustic emission signals recorded after passage through the instrumentation system can be deconvoluted to produce signal traces indicative of those at the generating source, and these traces can be used to identify characteristics of the source

  10. Second order semiclassics with self-generated magnetic fields

    DEFF Research Database (Denmark)

    Erdös, Laszlo; Fournais, Søren; Solovej, Jan Philip

    2012-01-01

    $ effectively determines the strength of the field. We consider the weak field regime with $\\beta h^{2}\\ge {const}>0$, where $h$ is the semiclassical parameter. For smooth potentials we prove that the semiclassical asymptotics of the total energy is given by the non-magnetic Weyl term to leading order...... with an error bound that is smaller by a factor $h^{1+\\e}$, i.e. the subleading term vanishes. However, for potentials with a Coulomb singularity the subleading term does not vanish due to the non-semiclassical effect of the singularity. Combined with a multiscale technique, this refined estimate is used...

  11. Probabilistic Inference on Multiple Normalized Signal Profiles from Next Generation Sequencing: Transcription Factor Binding Sites

    KAUST Repository

    Wong, Ka-Chun; Peng, Chengbin; Li, Yue

    2015-01-01

    With the prevalence of chromatin immunoprecipitation (ChIP) with sequencing (ChIP-Seq) technology, massive ChIP-Seq data has been accumulated. The ChIP-Seq technology measures the genome-wide occupancy of DNA-binding proteins in vivo. It is well-known that different DNA-binding protein occupancies may result in a gene being regulated in different conditions (e.g. different cell types). To fully understand a gene's function, it is essential to develop probabilistic models on multiple ChIP-Seq profiles for deciphering the gene transcription causalities. In this work, we propose and describe two probabilistic models. Assuming the conditional independence of different DNA-binding proteins' occupancies, the first method (SignalRanker) is developed as an intuitive method for ChIP-Seq genome-wide signal profile inference. Unfortunately, such an assumption may not always hold in some gene regulation cases. Thus, we propose and describe another method (FullSignalRanker) which does not make the conditional independence assumption. The proposed methods are compared with other existing methods on ENCODE ChIP-Seq datasets, demonstrating its regression and classification ability. The results suggest that FullSignalRanker is the best-performing method for recovering the signal ranks on the promoter and enhancer regions. In addition, FullSignalRanker is also the best-performing method for peak sequence classification. We envision that SignalRanker and FullSignalRanker will become important in the era of next generation sequencing. FullSignalRanker program is available on the following website: http://www.cs.toronto.edu/∼wkc/FullSignalRanker/ © 2015 IEEE.

  12. Probabilistic Inference on Multiple Normalized Signal Profiles from Next Generation Sequencing: Transcription Factor Binding Sites

    KAUST Repository

    Wong, Ka-Chun

    2015-04-20

    With the prevalence of chromatin immunoprecipitation (ChIP) with sequencing (ChIP-Seq) technology, massive ChIP-Seq data has been accumulated. The ChIP-Seq technology measures the genome-wide occupancy of DNA-binding proteins in vivo. It is well-known that different DNA-binding protein occupancies may result in a gene being regulated in different conditions (e.g. different cell types). To fully understand a gene\\'s function, it is essential to develop probabilistic models on multiple ChIP-Seq profiles for deciphering the gene transcription causalities. In this work, we propose and describe two probabilistic models. Assuming the conditional independence of different DNA-binding proteins\\' occupancies, the first method (SignalRanker) is developed as an intuitive method for ChIP-Seq genome-wide signal profile inference. Unfortunately, such an assumption may not always hold in some gene regulation cases. Thus, we propose and describe another method (FullSignalRanker) which does not make the conditional independence assumption. The proposed methods are compared with other existing methods on ENCODE ChIP-Seq datasets, demonstrating its regression and classification ability. The results suggest that FullSignalRanker is the best-performing method for recovering the signal ranks on the promoter and enhancer regions. In addition, FullSignalRanker is also the best-performing method for peak sequence classification. We envision that SignalRanker and FullSignalRanker will become important in the era of next generation sequencing. FullSignalRanker program is available on the following website: http://www.cs.toronto.edu/∼wkc/FullSignalRanker/ © 2015 IEEE.

  13. Lineshape estimation for magnetic resonance spectroscopy (MRS) signals: self-deconvolution revisited

    International Nuclear Information System (INIS)

    Sima, D M; Garcia, M I Osorio; Poullet, J; Van Huffel, S; Suvichakorn, A; Antoine, J-P; Van Ormondt, D

    2009-01-01

    Magnetic resonance spectroscopy (MRS) is an effective diagnostic technique for monitoring biochemical changes in an organism. The lineshape of MRS signals can deviate from the theoretical Lorentzian lineshape due to inhomogeneities of the magnetic field applied to patients and to tissue heterogeneity. We call this deviation a distortion and study the self-deconvolution method for automatic estimation of the unknown lineshape distortion. The method is embedded within a time-domain metabolite quantitation algorithm for short-echo-time MRS signals. Monte Carlo simulations are used to analyze whether estimation of the unknown lineshape can improve the overall quantitation result. We use a signal with eight metabolic components inspired by typical MRS signals from healthy human brain and allocate special attention to the step of denoising and spike removal in the self-deconvolution technique. To this end, we compare several modeling techniques, based on complex damped exponentials, splines and wavelets. Our results show that self-deconvolution performs well, provided that some unavoidable hyper-parameters of the denoising methods are well chosen. Comparison of the first and last iterations shows an improvement when considering iterations instead of a single step of self-deconvolution

  14. Mechanical design parameters for detection of nuclear signals by magnetic resonance force microscopy

    International Nuclear Information System (INIS)

    Moore, G.J.; Hanlon, J.A.; Lamartine, B.; Hawley, M.; Solem, J.C.; Signer, S.; Jarmer, J.J.; Penttila, S.; Sillerud, L.O.; Pryputniewicz, R.J.

    1993-01-01

    Recent theoretical work has shown that mechanical detection of magnetic resonance from a single nuclear spin is in principle possible. This theory has recently been experimentally validated by the mechanical detection of electron spin resonance signals using microscale cantilevers. Currently we are extending this technology in an attempt to detect nuclear signals which are extending this technology in an attempt to detect nuclear signals which are three orders of magnitude lower in intensity than electron signals. In order to achieve the needed thousand-fold improvement in sensitivity we have undertaken the development of optimized mechanical cantilevers and highly polarized samples. Finite element modeling is used as a tool to simulate cantilever beam dynamics and to optimize the mechanical properties including Q, resonant frequency, amplitude of vibration and spring constant. Simulations are compared to experiments using heterodyne hologram interferometry. Nanofabrication of optimized cantilevers via ion milling will be directed by the outcome of these simulations and experiments. Highly polarized samples are developed using a three-fold approach: (1) high magnetic field strength (2.5T), (2) low temperature (1K), and (3) use of samples polarized by dynamic nuclear polarization. Our recent experiments have demonstrated nuclear polarizations in excess of 50% in molecules of toulene

  15. A simple predistortion technique for suppression of nonlinear effects in periodic signals generated by nonlinear transducers

    Science.gov (United States)

    Novak, A.; Simon, L.; Lotton, P.

    2018-04-01

    Mechanical transducers, such as shakers, loudspeakers and compression drivers that are used as excitation devices to excite acoustical or mechanical nonlinear systems under test are imperfect. Due to their nonlinear behaviour, unwanted contributions appear at their output besides the wanted part of the signal. Since these devices are used to study nonlinear systems, it should be required to measure properly the systems under test by overcoming the influence of the nonlinear excitation device. In this paper, a simple method that corrects distorted output signal of the excitation device by means of predistortion of its input signal is presented. A periodic signal is applied to the input of the excitation device and, from analysing the output signal of the device, the input signal is modified in such a way that the undesirable spectral components in the output of the excitation device are cancelled out after few iterations of real-time processing. The experimental results provided on an electrodynamic shaker show that the spectral purity of the generated acceleration output approaches 100 dB after few iterations (1 s). This output signal, applied to the system under test, is thus cleaned from the undesirable components produced by the excitation device; this is an important condition to ensure a correct measurement of the nonlinear system under test.

  16. Evaluation of Eddy Current Signals from the Inner Wall Axial Cracks of Steam Generator Tubes

    International Nuclear Information System (INIS)

    Choi, Myung Sik; Hur, Do Haeng; Lee, Doek Hyun; Han, Jung Ho; Park, Jung Am

    2001-01-01

    For the enhancement of ECT reliability on the primary water stress corrosion cracks of nuclear steam generator tubes, of which the occurrence is on the increase, it is important to comprehend the signal characteristics on crack morphology and to select an appropriate probe type. In this paper, the sizing accuracy and the detectability for the inner wall axial cracks of tubes were quantitatively evaluated using the following specimens: the electric discharge machined notches and the corrosion cracks which were developed on the operating steam generator tubes. The difference of eddy current signal characteristics between pancake and axial coil were also Investigated. The results obtained from this study provide a useful information for more precise evaluation on the inner wall axial tracks oi steam generator tubes

  17. Microwave generation for magnetic fusion energy applications, Task A

    International Nuclear Information System (INIS)

    Antonsen, T.M. Jr.; Destler, W.W.; Granatstein, V.L.; Levush, B.; Mayergoyz, I.D.; Singh, A.

    1990-05-01

    This report details progress over the past year in the research program ''Free Electron Lasers with Short Period Wigglers.'' The work is performed jointly by the laboratory for Plasma Research and the Electrical Engineering Department of the University of Maryland and is funded by the US Department of Energy Office of Fusion Energy. The goal of the work is the development of an electron cyclotron resonance heating (ECRH) scheme for magnetic fusion plasmas such as the Compact Ignition Tokamak (CIT). Our approach is the development of a free electron laser using a sheet electron beam and a short period wiggler magnet. The specific requirements for the heating method include 10 to 30 MW of average power with pulse durations of several seconds to CW at a frequency near 300 GHz (∼600 GHz) in the case of second harmonic (ECRH). Compatible with the experimental nature of the program, radiation frequency flexibility of 30% total bandwidth and 5% rapid dynamic (approx-lt 10 ms) bandwidth is desirable. As the source will eventually be applied to a reactor, priority is placed upon high system efficiency and reliability. Use of established technologies is encouraged where possible

  18. Time-frequency peak filtering for random noise attenuation of magnetic resonance sounding signal

    Science.gov (United States)

    Lin, Tingting; Zhang, Yang; Yi, Xiaofeng; Fan, Tiehu; Wan, Ling

    2018-05-01

    When measuring in a geomagnetic field, the method of magnetic resonance sounding (MRS) is often limited because of the notably low signal-to-noise ratio (SNR). Most current studies focus on discarding spiky noise and power-line harmonic noise cancellation. However, the effects of random noise should not be underestimated. The common method for random noise attenuation is stacking, but collecting multiple recordings merely to suppress random noise is time-consuming. Moreover, stacking is insufficient to suppress high-level random noise. Here, we propose the use of time-frequency peak filtering for random noise attenuation, which is performed after the traditional de-spiking and power-line harmonic removal method. By encoding the noisy signal with frequency modulation and estimating the instantaneous frequency using the peak of the time-frequency representation of the encoded signal, the desired MRS signal can be acquired from only one stack. The performance of the proposed method is tested on synthetic envelope signals and field data from different surveys. Good estimations of the signal parameters are obtained at different SNRs. Moreover, an attempt to use the proposed method to handle a single recording provides better results compared to 16 stacks. Our results suggest that the number of stacks can be appropriately reduced to shorten the measurement time and improve the measurement efficiency.

  19. Analysis of the superconducting wiggler magnets for the ATF Harmonic Generation FEL experiment

    International Nuclear Information System (INIS)

    Zhang, X.; Ben-Zvi, I.; Ingold, G.; Krinsky, S.; Yu, L.H.

    1992-01-01

    In this paper, we consider the superconducting wiggler magnet under construction for the High Gain Harmonic Generation experiment (HGHG) at the Accelerator Test Facility (ATF) at BNL. This wiggler consists of an energy modulation section, a dispersion magnet and a radiator section. We present an analysis of the dispersion magnet and the end effects in the other wiggler sections. The purpose of the dispersion magnet is to convert energy modulation of the electron beam into spatial bunching. For the dispersion magnet, we discuss the physical requirements, analyze the magnetic design, determine the focusing properties, and consider the effect of departures from ideal behavior on the FEL gain. In the modulator and radiator wigglers we analyze the effects due to the ends of the wiggler and discuss their correction. In addition, the localized field produced by a trim coil for horizontal beam steering is investigated

  20. Towards 5G: A Photonic Based Millimeter Wave Signal Generation for Applying in 5G Access Fronthaul

    OpenAIRE

    Alavi, S. E.; Soltanian, M. R. K.; Amiri, I. S.; Khalily, M.; Supa?at, A. S. M.; Ahmad, H.

    2016-01-01

    5G communications require a multi Gb/s data transmission in its small cells. For this purpose millimeter wave (mm-wave) RF signals are the best solutions to be utilized for high speed data transmission. Generation of these high frequency RF signals is challenging in electrical domain therefore photonic generation of these signals is more studied. In this work, a photonic based simple and robust method for generating millimeter waves applicable in 5G access fronthaul is presented. Besides gene...

  1. Tunable microwave signal generation based on an Opto-DMD processor and a photonic crystal fiber

    International Nuclear Information System (INIS)

    Wang Tao; Sang Xin-Zhu; Yan Bin-Bin; Li Yan; Song Fei-Jun; Zhang Xia; Wang Kui-Ru; Yuan Jin-Hui; Yu Chong-Xiu; Ai Qi; Chen Xiao; Zhang Ying; Chen Gen-Xiang; Xiao Feng; Kamal Alameh

    2014-01-01

    Frequency-tunable microwave signal generation is proposed and experimentally demonstrated with a dual-wavelength single-longitudinal-mode (SLM) erbium-doped fiber ring laser based on a digital Opto-DMD processor and four-wave mixing (FWM) in a high-nonlinear photonic crystal fiber (PCF). The high-nonlinear PCF is employed for the generation of the FWM to obtain stable and uniform dual-wavelength oscillation. Two different short passive sub-ring cavities in the main ring cavity serve as mode filters to make SLM lasing. The two lasing wavelengths are electronically selected by loading different gratings on the Opto-DMD processor controlled with a computer. The wavelength spacing can be smartly adjusted from 0.165 nm to 1.08 nm within a tuning accuracy of 0.055 nm. Two microwave signals at 17.23 GHz and 27.47 GHz are achieved. The stability of the microwave signal is discussed. The system has the ability to generate a 137.36-GHz photonic millimeter signal at room temperature

  2. Study of magnetic field expansion using a plasma generator for space radiation active protection

    International Nuclear Information System (INIS)

    Jia Xianghong; Jia Shaoxia; Wan Jun; Wang Shouguo; Xu Feng; Bai Yanqiang; Liu Hongtao; Jiang Rui; Ma Hongbo

    2013-01-01

    There are many active protecting methods including Electrostatic Fields, Confined Magnetic Field, Unconfined Magnetic Field and Plasma Shielding etc. for defending the high-energy solar particle events (SPE) and Galactic Cosmic Rays (GCR) in deep space exploration. The concept of using cold plasma to expand a magnetic field is the best one of all possible methods so far. The magnetic field expansion caused by plasma can improve its protective efficiency of space particles. One kind of plasma generator has been developed and installed into the cylindrical permanent magnet in the eccentric. A plasma stream is produced using a helical-shaped antenna driven by a radio-frequency (RF) power supply of 13.56 MHz, which exits from both sides of the magnet and makes the magnetic field expand on one side. The discharging belts phenomenon is similar to the Earth's radiation belt, but the mechanism has yet to be understood. A magnetic probe is used to measure the magnetic field expansion distributions, and the results indicate that the magnetic field intensity increases under higher increments of the discharge power. (authors)

  3. Design and results of testing the SHF-generator magnetic system of the T-15 device

    International Nuclear Information System (INIS)

    Borisov, V.D.; Koretskij, A.Yu.; Kostenko, A.I.; Monoszon, N.A.; Ostroumov, Yu.N.; Suvorov, M.M.; Trokhachev, G.V.; Churakov, G.F.; Shmal'ko, G.I.; Yakubovskij, V.G.

    1984-01-01

    Design and engineering solutions accepted in the development of the 5T superconducting solenoid of the auxillary heating SHF-generator for the T-15 tokamak are presented. A superconducting coil generates an axially symmetric field with a definite distribution along the SHF-generator gyrocon axis. Limited sizes, high accuracy of coincidence of geometric and magnetic axes, and possibility of operation with different gyrocons are the main peculiarities of the developed cryostat. The required magnetic field of 5T was attained after some training. Heat input at 4.5 K corresponds to the rated value of 2.5 W. Test results for solenoid functional models are presented

  4. Robust high-resolution quantification of time signals encoded by in vivo magnetic resonance spectroscopy

    Science.gov (United States)

    Belkić, Dževad; Belkić, Karen

    2018-01-01

    This paper on molecular imaging emphasizes improving specificity of magnetic resonance spectroscopy (MRS) for early cancer diagnostics by high-resolution data analysis. Sensitivity of magnetic resonance imaging (MRI) is excellent, but specificity is insufficient. Specificity is improved with MRS by going beyond morphology to assess the biochemical content of tissue. This is contingent upon accurate data quantification of diagnostically relevant biomolecules. Quantification is spectral analysis which reconstructs chemical shifts, amplitudes and relaxation times of metabolites. Chemical shifts inform on electronic shielding of resonating nuclei bound to different molecular compounds. Oscillation amplitudes in time signals retrieve the abundance of MR sensitive nuclei whose number is proportional to metabolite concentrations. Transverse relaxation times, the reciprocal of decay probabilities of resonances, arise from spin-spin coupling and reflect local field inhomogeneities. In MRS single voxels are used. For volumetric coverage, multi-voxels are employed within a hybrid of MRS and MRI called magnetic resonance spectroscopic imaging (MRSI). Common to MRS and MRSI is encoding of time signals and subsequent spectral analysis. Encoded data do not provide direct clinical information. Spectral analysis of time signals can yield the quantitative information, of which metabolite concentrations are the most clinically important. This information is equivocal with standard data analysis through the non-parametric, low-resolution fast Fourier transform and post-processing via fitting. By applying the fast Padé transform (FPT) with high-resolution, noise suppression and exact quantification via quantum mechanical signal processing, advances are made, presented herein, focusing on four areas of critical public health importance: brain, prostate, breast and ovarian cancers.

  5. Modeling of Self-Excited Isolated Permanent Magnet Induction Generator Using Iterative Numerical Method

    Directory of Open Access Journals (Sweden)

    Mohamed Mostafa R.

    2016-01-01

    Full Text Available Self-Excited Permanent Magnet Induction Generator (PMIG is commonly used in wind energy generation systems. The difficulty of Self-Excited Permanent Magnet Induction Generator (SEPMIG modeling is the circuit parameters of the generator vary at each load conditions due to the a change in the frequency and stator voltage. The paper introduces a new modeling for SEPMIG using Gauss-sidle relaxation method. The SEPMIG characteristics using the proposed method are studied at different load conditions according to the wind speed variation, load impedance changes and different shunted capacitor values. The system modeling is investigated due to the magnetizing current variation, the efficiency variation, the power variation and power factor variation. The proposed modeling system satisfies high degree of simplicity and accuracy.

  6. Programming a DSP card for generating an ECG signal with possibility of anomalies

    International Nuclear Information System (INIS)

    Hamrouni, Sayma

    2013-01-01

    This project consists of programming a DSP designed to generate an ECG signal with a probability of anomaly. To begin with, we get to know the characteristics of a DSP card and its architecture. As a second step, we programmed the DSP32C using the compiler D3CC associated with Textpad in order to obtain an analog signal in the respective outputs. And then finally, we developed a graphical user interface using the programming software LabVIEW that aims controlling the good operation of DSP. The tests previously made have proved the good operation of the application.

  7. Signal to noise ratio enhancement for Eddy Current testing of steam generator tubes in PWR's

    International Nuclear Information System (INIS)

    Georgel, B.

    1985-01-01

    Noise reduction is a compulsory task when we try to recognize and characterize flaws. The signals we deal with come from Eddy Current testings of steam generator steel tubes. We point out the need for a spectral invariant in digital spectral analysis of 2 components signals. We make clear the pros and cons of classical passband filtering and suggest the use of a new noise cancellation method first discussed by Moriwaki and Tlusty. We generalize this tricky technique and prove it is a very special case of the well-known Wiener filter. In that sense the M-T method is shown to be optimal. 6 refs

  8. Microwave-signal generation in a planar Gunn diode with radiation exposure taken into account

    Energy Technology Data Exchange (ETDEWEB)

    Obolenskaya, E. S., E-mail: bess009@mail.ru, E-mail: obolensk@rf.unn.ru; Tarasova, E. A.; Churin, A. Yu.; Obolensky, S. V. [Lobachevsky State University of Nizhny Novgorod (NNSU) (Russian Federation); Kozlov, V. A. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

    2016-12-15

    Microwave-signal generation in planar Gunn diodes with a two-dimensional electron gas, in which we previously studied steady-state electron transport, is theoretically studied. The applicability of a control electrode similar to a field-effect transistor gate to control the parameters of the output diode microwave signal is considered. The results of physical-topological modeling of semiconductor structures with different diode active-region structures, i.e., without a quantum well, with one and two quantum wells separated by a potential barrier, are compared. The calculated results are compared with our previous experimental data on recording Gunn generation in a Schottky-gate field-effect transistor. It is theoretically and experimentally shown that the power of the signal generated by the planar Gunn diode with a quantum well and a control electrode is sufficient to implement monolithic integrated circuits of different functionalities. It is theoretically and experimentally shown that the use of a control electrode on account of the introduction of corrective feedback allows a significant increase in the radiation resistance of a microwave generator with Schottky-gate field-effect transistors.

  9. Microwave-signal generation in a planar Gunn diode with radiation exposure taken into account

    International Nuclear Information System (INIS)

    Obolenskaya, E. S.; Tarasova, E. A.; Churin, A. Yu.; Obolensky, S. V.; Kozlov, V. A.

    2016-01-01

    Microwave-signal generation in planar Gunn diodes with a two-dimensional electron gas, in which we previously studied steady-state electron transport, is theoretically studied. The applicability of a control electrode similar to a field-effect transistor gate to control the parameters of the output diode microwave signal is considered. The results of physical-topological modeling of semiconductor structures with different diode active-region structures, i.e., without a quantum well, with one and two quantum wells separated by a potential barrier, are compared. The calculated results are compared with our previous experimental data on recording Gunn generation in a Schottky-gate field-effect transistor. It is theoretically and experimentally shown that the power of the signal generated by the planar Gunn diode with a quantum well and a control electrode is sufficient to implement monolithic integrated circuits of different functionalities. It is theoretically and experimentally shown that the use of a control electrode on account of the introduction of corrective feedback allows a significant increase in the radiation resistance of a microwave generator with Schottky-gate field-effect transistors.

  10. Magnetic fields of AM band radio broadcast signals at the Richmond Field Station

    International Nuclear Information System (INIS)

    Becker, Alex; Frangos, William

    1998-01-01

    Non-invasive sensing of the shallow subsurface is necessary for detection and delineation of buried hazardous wastes, monitoring of the condition of clay containment caps, and a variety of other purposes. Electromagnetic methods have proven to be effective in environmental site characterization where there is a need for increased resolution in subsurface characterization. Two considerations strongly suggest the use of frequencies between 100 kHz and 100 MHz for such applications: 1) the induction response of many targets is small due to small size, and 2) a need to determine both the electrical conductivity and dielectric permittivity which are related to chemistry and hydrology. Modeling and physical parameter studies confirm that measurements at frequencies between 1 and 100 MHz can resolve variations in subsurface conductivity and permittivity. To provide the necessary technology for shallow subsurface investigations, we propose to exploit the concept of electromagnetic impedance, the ratio of orthogonal horizontal electric and magnetic fields. Prior to assembling the equipment for measuring surface impedance using controlled, local source it was felt prudent to measure the surface impedance of geological materials at the University of California at Berkeley's Richmond Field (RFS) using ambient energy in the broadcast band. As a first step toward this intermediate goal, we have examined and characterized local AM band radio signals in terms of both signal strength and polarization of the magnetic component as received at RFS. In addition, we have established the viability of a commercial radio-frequency magnetic sensor

  11. S100 lathe bed pulse generator applied to pulsed nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Cernicchiaro, G.R.C.; Rudge, M.G.; Albuquerque, M.P.

    1989-01-01

    The project and construction of four channel pulse generator in the S100 standard plate and its control software for microcomputer are described. The microcomputer has total control on the pulse generator, which has seven programable parameters, defining the position of four pulses and the width for the three first ones. This pulse generator is controlled by a software developed in c language, and is used in pulsed nuclear magnetic resonance experiences. (M.C.K.) [pt

  12. Direct Driven Permanent Magnet Synchronous Generators with Diode Rectifiers for Use in Offshore Wind Turbines

    OpenAIRE

    Reigstad, Tor Inge

    2007-01-01

    This work is focused on direct-driven permanent magnets synchronous generators (PMSG) with diode rectifiers for use in offshore wind turbines. Reactive compensation of the generator, power losses and control of the generator are studied. Configurations for power transmission to onshore point of common connection are also considered. Costs, power losses, reliability and interface with the PMSG are discussed. The purpose of the laboratory tests and simulations are to learn how a PMSG with dio...

  13. Enhancing the utilization of photovoltaic power generation by superconductive magnetic energy storage

    International Nuclear Information System (INIS)

    Tam, K.S.; Kumar, P.; Foreman, M.

    1989-01-01

    This paper demonstrates that a superconductive magnetic energy storage (SMES) system can enhance large scale utilization of PV generation. With SMES support, power generated from PV arrays van be fully utilized under different weather conditions and PV penetrations can be increased to significant levels without causing adverse effects to the power system. Coupled with PV generation, a SMES system is even more effective in performing diurnal load leveling. A coordinated PV/SMES operation scheme is proposed and demonstrated under different weather conditions

  14. New performance in harmonic analysis device generation used for magnetic fields measurements

    International Nuclear Information System (INIS)

    Evesque, C.; Tkatchenko, M.

    1996-01-01

    In particle accelerator, correcting high multipole components of magnets are of high importance for quality magnet: to get a pure quadrupole to within 10 -4 , we have to know the field quality to 10 -5 through the 30. order. Our laboratory needed such a very sharp device to find small harmonic components of magnetic field. For harmonic analysis of magnetic field, we adopted the standard method, i.e. a rotating coil connected to a flux integrator. Nowadays, coils measuring azimuthal component of magnetic field are used. In order to obtain correct and accurate measurements, we were guided by two imperatives: first, optimisation of construction constraints and second, comparison of azimuthal and radial component measurements. With this background, this article describes both new technological solutions adopted and new performance obtained. We also discuss the most suitable geometric structure for the coils. We obtained a noiseless signal, a repeatability of 10 -5 and a sensitivity up to 10 -8 Weber for both types of coils. Our device is able to find and measure main component, normal and skew multipole components up to the 32. order, when simulating local defects. The magnetic axis is located within 5 μm. The central gradient is also measured and magnetic length deduced. Complementary functions of two types of coils were noticed in detecting local defects of magnetic structure. (authors)

  15. New performance in harmonic analysis device generation used for magnetic fields measurements

    Energy Technology Data Exchange (ETDEWEB)

    Evesque, C.; Tkatchenko, M.

    1996-12-31

    In particle accelerator, correcting high multipole components of magnets are of high importance for quality magnet: to get a pure quadrupole to within 10{sup -4}, we have to know the field quality to 10{sup -5} through the 30. order. Our laboratory needed such a very sharp device to find small harmonic components of magnetic field. For harmonic analysis of magnetic field, we adopted the standard method, i.e. a rotating coil connected to a flux integrator. Nowadays, coils measuring azimuthal component of magnetic field are used. In order to obtain correct and accurate measurements, we were guided by two imperatives: first, optimisation of construction constraints and second, comparison of azimuthal and radial component measurements. With this background, this article describes both new technological solutions adopted and new performance obtained. We also discuss the most suitable geometric structure for the coils. We obtained a noiseless signal, a repeatability of 10{sup -5} and a sensitivity up to 10{sup -8} Weber for both types of coils. Our device is able to find and measure main component, normal and skew multipole components up to the 32. order, when simulating local defects. The magnetic axis is located within 5 {mu}m. The central gradient is also measured and magnetic length deduced. Complementary functions of two types of coils were noticed in detecting local defects of magnetic structure. (authors).

  16. Design of a signal conditioner for the Fermilab Magnet Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    Giannelli, Pietro [Turin Polytechnic

    2012-01-01

    This thesis describes the design of a remotely-programmable signal conditioner for the harmonic measurement of accelerator magnets. A 10-channel signal conditioning circuit featuring bucking capabilities was designed from scratch and implemented to the level of the printed circuit board layout. Other system components were chosen from those available on the market. Software design was started with the definition of routine procedures. This thesis is part of an upgrade project for replacing obsolescent automated test equipment belonging to the Fermilab Magnet Test Facility. The design started with a given set of requirements. Using a top-down approach, all the circuits were designed and their expected performances were theoretically predicted and simulated. A limited prototyping phase followed. The printed circuit boards were laid out and routed using a CAD software and focusing the design on maximum electromagnetic interference immunity. An embedded board was selected for controlling and interfacing the signal conditioning circuitry with the instrumentation network. Basic low level routines for hardware access were defined. This work covered the entire design process of the signal conditioner, resulting in a project ready for manufacturing. The expected performances are in line with the requirements and, in the cases where this was not possible, approval of trade-offs was sought and received from the end users. Part I deals with the global structure of the signal conditioner and the subdivision in functional macro-blocks. Part II treats the hardware design phase in detail, covering the analog and digital circuits, the printed circuit layouts, the embedded controller and the power supply selection. Part III deals with the basic hardware-related routines to be implemented in the final software.

  17. Theory and simulations of electron vortices generated by magnetic pushing

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, A. S.; Angus, J. R.; Swanekamp, S. B.; Schumer, J. W. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Ottinger, P. F. [An Independent Consultant through ENGILITY, Chantilly, Virginia 20151 (United States)

    2013-08-15

    Vortex formation and propagation are observed in kinetic particle-in-cell (PIC) simulations of magnetic pushing in the plasma opening switch. These vortices are studied here within the electron-magnetohydrodynamic (EMHD) approximation using detailed analytical modeling. PIC simulations of these vortices have also been performed. Strong v×B forces in the vortices give rise to significant charge separation, which necessitates the use of the EMHD approximation in which ions are fixed and the electrons are treated as a fluid. A semi-analytic model of the vortex structure is derived, and then used as an initial condition for PIC simulations. Density-gradient-dependent vortex propagation is then examined using a series of PIC simulations. It is found that the vortex propagation speed is proportional to the Hall speed v{sub Hall}≡cB{sub 0}/4πn{sub e}eL{sub n}. When ions are allowed to move, PIC simulations show that the electric field in the vortex can accelerate plasma ions, which leads to dissipation of the vortex. This electric field contributes to the separation of ion species that has been observed to occur in pulsed-power experiments with a plasma-opening switch.

  18. Properties of spheromaks generated by a magnetized coaxial source

    International Nuclear Information System (INIS)

    Hoida, H.W.; Henins, I.; Jarboe, T.R.; Linford, R.K.; Lipson, J.; Marshall, J.; Platts, D.A.; Sherwood, A.R.; Tuszewski, M.

    1981-01-01

    In gun-generated spheromaks impurity contamination plays an important role in determining the energy loss. Metallic impurities can be reduced by an appropriate change of source parameters. The reduction of the level of metal impurities results in a spectrum showing a preponderance of oxygen and carbon lines and OIV radiation is observed to increase indicating a warmer plasma. However, the plasma lifetime is not changed. Discharge cleaning techniques appear to be necessary. It is still possible that electron heat conduction during the reconnection processs will be found to be important once the impurities are reduced

  19. Properties of spheromaks generated by a magnetized coaxial source

    Energy Technology Data Exchange (ETDEWEB)

    Hoida, H.W.; Henins, I.; Jarboe, T.R.; Linford, R.K.; Lipson, J.; Marshall, J.; Platts, D.A.; Sherwood, A.R.; Tuszewski, M.

    1981-01-01

    In gun-generated spheromaks impurity contamination plays an important role in determining the energy loss. Metallic impurities can be reduced by an appropriate change of source parameters. The reduction of the level of metal impurities results in a spectrum showing a preponderance of oxygen and carbon lines and OIV radiation is observed to increase indicating a warmer plasma. However, the plasma lifetime is not changed. Discharge cleaning techniques appear to be necessary. It is still possible that electron heat conduction during the reconnection processs will be found to be important once the impurities are reduced.

  20. A novel HTS SMES application in combination with a permanent magnet synchronous generator type wind power generation system

    Science.gov (United States)

    Kim, G. H.; Kim, A. R.; Kim, S.; Park, M.; Yu, I. K.; Seong, K. C.; Won, Y. J.

    2011-11-01

    Superconducting magnetic energy storage (SMES) system is a DC current driven device and can be utilized to improve power quality particularly in connection with renewable energy sources due to higher efficiency and faster response than other devices. This paper suggests a novel connection topology of SMES which can smoothen the output power flow of the wind power generation system (WPGS). The structure of the proposed system is cost-effective because it reduces a power converter in comparison with a conventional application of SMES. One more advantage of SMES in the proposed system is to improve the capability of low voltage ride through (LVRT) for the permanent magnet synchronous generator (PMSG) type WPGS. The proposed system including a SMES has been modeled and analyzed by a PSCAD/EMTDC. The simulation results show the effectiveness of the novel SMES application strategy to not only mitigate the output power of the PMSG but also improve the capability of LVRT for PMSG type WPGS.

  1. Generation of Electron Whistler Waves at the Mirror Mode Magnetic Holes: MMS Observations and PIC Simulation

    Science.gov (United States)

    Ahmadi, N.; Wilder, F. D.; Usanova, M.; Ergun, R.; Argall, M. R.; Goodrich, K.; Eriksson, S.; Germaschewski, K.; Torbert, R. B.; Lindqvist, P. A.; Le Contel, O.; Khotyaintsev, Y. V.; Strangeway, R. J.; Schwartz, S. J.; Giles, B. L.; Burch, J.

    2017-12-01

    The Magnetospheric Multiscale (MMS) mission observed electron whistler waves at the center and at the gradients of magnetic holes on the dayside magnetosheath. The magnetic holes are nonlinear mirror structures which are anti-correlated with particle density. We used expanding box Particle-in-cell simulations and produced the mirror instability magnetic holes. We show that the electron whistler waves can be generated at the gradients and the center of magnetic holes in our simulations which is in agreement with MMS observations. At the nonlinear regime of mirror instability, the proton and electron temperature anisotropy are anti-correlated with the magnetic hole. The plasma is unstable to electron whistler waves at the minimum of the magnetic field structures. In the saturation regime of mirror instability, when magnetic holes are dominant, electron temperature anisotropy develops at the edges of the magnetic holes and electrons become isotropic at the magnetic field minimum. We investigate the possible mechanism for enhancing the electron temperature anisotropy and analyze the electron pitch angle distributions and electron distribution functions in our simulations and compare it with MMS observations.

  2. Analysis of the Magnetic Field Effect on Entropy Generation at Thermosolutal Convection in a Square Cavity

    Directory of Open Access Journals (Sweden)

    Ammar Ben Brahim

    2011-05-01

    Full Text Available Thermosolutal convection in a square cavity filled with air and submitted to an inclined magnetic field is investigated numerically. The cavity is heated and cooled along the active walls with a mass gradient whereas the two other walls of the cavity are adiabatic and insulated. Entropy generation due to heat and mass transfer, fluid friction and magnetic effect has been determined in transient state for laminar flow by solving numerically the continuity, momentum energy and mass balance equations, using a Control Volume Finite—Element Method. The structure of the studied flows depends on four dimensionless parameters which are the Grashof number, the buoyancy ratio, the Hartman number and the inclination angle. The results show that the magnetic field parameter has a retarding effect on the flow in the cavity and this lead to a decrease of entropy generation, Temperature and concentration decrease with increasing value of the magnetic field parameter.

  3. Application of random numbers at computerized simulation of proton magnetic resonance signals

    International Nuclear Information System (INIS)

    Populyakh, S.N.; Sapiga, A.V.

    2006-01-01

    One calculated numerically spectra of proton magnetic resonance of water molecules diffusing along the regular positions in a natrolite. One reached adequate conformity of the experimental and the calculated spectra within wide temperature range including a transition region. To ensure calculations one used generators of the pseudorandom Markov sequences. The numerical analysis, in particular, has shown that at the binary Markov process the time period when physical value remains unchanged is described by the random value with exponential distribution [ru

  4. Low power laser generated ultrasound: Signal processing for time domain data acquisition

    International Nuclear Information System (INIS)

    Cleary, A; Thursby, G; McKee, C; Armstrong, I; Culshaw, B; Veres, I; Pierce, S G

    2011-01-01

    The use of low power modulated laser diode systems has previously been established as a suitable method for non-destructive laser generation of ultrasound. Using a quasi-continuous optical excitation amplified by an erbium-doped fibre amplifier (EDFA) allows flexible generation of ultrasonic waves, offering control of further parameters such as the frequency content or signal shape. In addition, pseudo-random binary sequences (PRBS) can be used to improve the detected impulse response. Here we compare two sequences, the m-sequence and the Golay code, and discuss the advantages and practical limits of their application with laser diode based optical excitation of ultrasound.

  5. Improving heat generation of magnetic nanoparticles by pre-orientation of particles in a static three tesla magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Mathias M., E-mail: Mathias.Beck@tum.de [Institute for Machine Tools and Industrial Management, Technical University of Munich, Boltzmannstr. 15, 85748 Garching (Germany); Lammel, Christian [Institute for Machine Tools and Industrial Management, Technical University of Munich, Boltzmannstr. 15, 85748 Garching (Germany); Gleich, Bernhard [Institute of Medical Engineering, Technical University of Munich, Boltzmannstr. 11, 85748 Garching (Germany)

    2017-04-01

    Inductive heating of electrically insulating materials like fiberglass reinforced thermoplastics (FRTP) without susceptors is not possible. However, due to their low thermal conductivity a volumetric heat generation method is advisable to reach short heating times to melt this material for reshaping. This can be done with magnetic nanoparticles as susceptors within the thermoplastic of the FRTP using Néel relaxation. During the heating process the particle's magnetic moment rotates with the field while the particle itself is fixed within the thermoplastic. Therefore the heat dissipation of each particle depends on its orientation within the field. To achieve the maximum heat generation of the particles we pre-oriented the particles within a plastic at the best angle to the applied AC field for induction. To do this, five mass percent nanoparticles were dispersed in an epoxy resin, which was then hardened at room temperature in a static three Tesla magnetic field. After its solidification the heating behavior of the sample was compared to a reference sample, which was hardened without a field. The oriented particles showed an increased heating rate when oriented parallel to the applied AC field. The absorption rate was 3.3 times as high as the undirected reference sample. When the alternating electromagnetic field was perpendicular to the oriented particles, the specific absorption rate was similar to that of the reference sample. We compare this result with theory and with calculations from literature, and conduct a numerical simulation. - Highlights: • Magnetic nanoparticles are aligned using a static three tesla magnetic field. • Inductive heating depends on the particles pre-orientation in a solid matrix. • Alignment increases the heat generation significantly.

  6. Fluorescence In Situ Hybridization (FISH Signal Analysis Using Automated Generated Projection Images

    Directory of Open Access Journals (Sweden)

    Xingwei Wang

    2012-01-01

    Full Text Available Fluorescence in situ hybridization (FISH tests provide promising molecular imaging biomarkers to more accurately and reliably detect and diagnose cancers and genetic disorders. Since current manual FISH signal analysis is low-efficient and inconsistent, which limits its clinical utility, developing automated FISH image scanning systems and computer-aided detection (CAD schemes has been attracting research interests. To acquire high-resolution FISH images in a multi-spectral scanning mode, a huge amount of image data with the stack of the multiple three-dimensional (3-D image slices is generated from a single specimen. Automated preprocessing these scanned images to eliminate the non-useful and redundant data is important to make the automated FISH tests acceptable in clinical applications. In this study, a dual-detector fluorescence image scanning system was applied to scan four specimen slides with FISH-probed chromosome X. A CAD scheme was developed to detect analyzable interphase cells and map the multiple imaging slices recorded FISH-probed signals into the 2-D projection images. CAD scheme was then applied to each projection image to detect analyzable interphase cells using an adaptive multiple-threshold algorithm, identify FISH-probed signals using a top-hat transform, and compute the ratios between the normal and abnormal cells. To assess CAD performance, the FISH-probed signals were also independently visually detected by an observer. The Kappa coefficients for agreement between CAD and observer ranged from 0.69 to 1.0 in detecting/counting FISH signal spots in four testing samples. The study demonstrated the feasibility of automated FISH signal analysis that applying a CAD scheme to the automated generated 2-D projection images.

  7. Self-generated magnetic flux in YBa$_2$Cu$_3$O$_{7-x}$ grain boundaries

    OpenAIRE

    Mints, R. G.; Papiashvili, Ilya

    2000-01-01

    Grain boundaries in YBa$_2$Cu$_3$O$_{7-x}$ superconducting films are considered as Josephson junctions with a critical current density $j_c(x)$ alternating along the junction. A self-generated magnetic flux is treated both analytically and numerically for an almost periodic distribution of $j_c(x)$. We obtained a magnetic flux-pattern similar to the one which was recently observed experimentally.

  8. A terminal fluoride ligand generates axial magnetic anisotropy in dysprosium complexes

    Energy Technology Data Exchange (ETDEWEB)

    Norel, Lucie [Department of Chemistry, University of California, Berkeley, CA (United States); Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, Rennes (France); Darago, Lucy E.; Chakarawet, Khetpakorn; Gonzalez, Miguel I.; Olshansky, Jacob H.; Long, Jeffrey R. [Department of Chemistry, University of California, Berkeley, CA (United States); Le Guennic, Boris; Rigaut, Stephane [Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, Rennes (France)

    2018-02-12

    The first dysprosium complexes with a terminal fluoride ligand are obtained as air-stable compounds. The strong, highly electrostatic dysprosium-fluoride bond generates a large axial crystal-field splitting of the J=15/2 ground state, as evidenced by high-resolution luminescence spectroscopy and correlated with the single-molecule magnet behavior through experimental magnetic susceptibility data and ab initio calculations. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Computer soundcard as an AC signal generator and oscilloscope for the physics laboratory

    Science.gov (United States)

    Sinlapanuntakul, Jinda; Kijamnajsuk, Puchong; Jetjamnong, Chanthawut; Chotikaprakhan, Sutharat

    2018-01-01

    The purpose of this paper is to develop both an AC signal generator and a dual-channel oscilloscope based on standard personal computer equipped with sound card as parts of the laboratory of the fundamental physics and the introduction to electronics classes. The setup turns the computer into the two channel measured device which can provides sample rate, simultaneous sampling, frequency range, filters and others essential capabilities required to perform amplitude, phase and frequency measurements of AC signal. The AC signal also generate from the same computer sound card output simultaneously in any waveform such as sine, square, triangle, saw-toothed pulsed, swept sine and white noise etc. These can convert an inexpensive PC sound card into powerful device, which allows the students to measure physical phenomena with their own PCs either at home or at university attendance. A graphic user interface software was developed for control and analysis, including facilities for data recording, signal processing and real time measurement display. The result is expanded utility of self-learning for the students in the field of electronics both AC and DC circuits, including the sound and vibration experiments.

  10. Evaluation of the use of envelope analysis and DWT on AE signals generated from degrading shafts

    International Nuclear Information System (INIS)

    Gu, Dongsik; Kim, Jaegu; Kelimu, Tulugan; Huh, Sun-Chul; Choi, Byeong-Keun

    2012-01-01

    Vibration analysis is widely used in machinery diagnosis. Wavelet transforms and envelope analysis, which have been implemented in many applications in the condition monitoring of machinery, are applied in the development of a condition monitoring system for early detection of faults generated in several key components of machinery. Early fault detection is a very important factor in condition monitoring and a basic component for the application of condition-based maintenance (CBM) and predictive maintenance (PM). In addition, acoustic emission (AE) sensors have specific characteristics that are highly sensitive to high-frequency and low-energy signals. Therefore, the AE technique has been applied recently in studies on the early detection of failure. In this paper, AE signals caused by crack growth on a rotating shaft were captured through an AE sensor. The AE signatures were pre-processed using the proposed signal processing method, after which power spectrums were generated from the FFT results. In the power spectrum, some peaks from fault frequencies were presented. According to the results, crack growth in rotating machinery can be considered and detected using an AE sensor and the signal processing method.

  11. Hybrid excited claw pole generator with skewed and non-skewed permanent magnets

    Science.gov (United States)

    Wardach, Marcin

    2017-12-01

    This article contains simulation results of the Hybrid Excited Claw Pole Generator with skewed and non-skewed permanent magnets on rotor. The experimental machine has claw poles on two rotor sections, between which an excitation control coil is located. The novelty of this machine is existence of non-skewed permanent magnets on claws of one part of the rotor and skewed permanent magnets on the second one. The paper presents the construction of the machine and analysis of the influence of the PM skewing on the cogging torque and back-emf. Simulation studies enabled the determination of the cogging torque and the back-emf rms for both: the strengthening and the weakening of magnetic field. The influence of the magnets skewing on the cogging torque and the back-emf rms have also been analyzed.

  12. Hybrid excited claw pole generator with skewed and non-skewed permanent magnets

    Directory of Open Access Journals (Sweden)

    Wardach Marcin

    2017-12-01

    Full Text Available This article contains simulation results of the Hybrid Excited Claw Pole Generator with skewed and non-skewed permanent magnets on rotor. The experimental machine has claw poles on two rotor sections, between which an excitation control coil is located. The novelty of this machine is existence of non-skewed permanent magnets on claws of one part of the rotor and skewed permanent magnets on the second one. The paper presents the construction of the machine and analysis of the influence of the PM skewing on the cogging torque and back-emf. Simulation studies enabled the determination of the cogging torque and the back-emf rms for both: the strengthening and the weakening of magnetic field. The influence of the magnets skewing on the cogging torque and the back-emf rms have also been analyzed.

  13. Nonlinear Optical Magnetism Revealed by Second-Harmonic Generation in Nanoantennas.

    Science.gov (United States)

    Kruk, Sergey S; Camacho-Morales, Rocio; Xu, Lei; Rahmani, Mohsen; Smirnova, Daria A; Wang, Lei; Tan, Hark Hoe; Jagadish, Chennupati; Neshev, Dragomir N; Kivshar, Yuri S

    2017-06-14

    Nonlinear effects at the nanoscale are usually associated with the enhancement of electric fields in plasmonic structures. Recently emerged new platform for nanophotonics based on high-index dielectric nanoparticles utilizes optically induced magnetic response via multipolar Mie resonances and provides novel opportunities for nanoscale nonlinear optics. Here, we observe strong second-harmonic generation from AlGaAs nanoantennas driven by both electric and magnetic resonances. We distinguish experimentally the contribution of electric and magnetic nonlinear response by analyzing the structure of polarization states of vector beams in the second-harmonic radiation. We control continuously the transition between electric and magnetic nonlinearities by tuning polarization of the optical pump. Our results provide a direct observation of nonlinear optical magnetism through selective excitation of multipolar nonlinear modes in nanoantennas.

  14. The trans-generational impact of population density signals on host-parasite interactions.

    Science.gov (United States)

    Michel, Jessica; Ebert, Dieter; Hall, Matthew D

    2016-11-25

    The density of a host population is a key parameter underlying disease transmission, but it also has implications for the expression of disease through its effect on host physiology. In response to higher densities, individuals are predicted to either increase their immune investment in response to the elevated risk of parasitism, or conversely to decrease their immune capacity as a consequence of the stress of a crowded environment. However, an individual's health is shaped by many different factors, including their genetic background, current environmental conditions, and maternal effects. Indeed, population density is often sensed through the presence of info-chemicals in the environment, which may influence a host's interaction with parasites, and also those of its offspring. All of which may alter the expression of disease, and potentially uncouple the presumed link between changes in host density and disease outcomes. In this study, we used the water flea Daphnia magna and its obligate bacterial parasite Pasteuria ramosa, to investigate how signals of high host density impact on host-parasite interactions over two consecutive generations. We found that the chemical signals from crowded treatments induced phenotypic changes in both the parental and offspring generations. In the absence of a pathogen, life-history changes were genotype-specific, but consistent across generations, even when the signal of density was removed. In contrast, the influence of density on infected animals depended on the trait and generation of exposure. When directly exposed to signals of high-density, host genotypes responded differently in how they minimised the severity of disease. Yet, in the subsequent generation, the influence of density was rarely genotype-specific and instead related to ability of the host to minimise the onset of infection. Our findings reveal that population level correlations between host density and infection capture only part of the complex relationship

  15. Cross-talk between signaling pathways can generate robust oscillations in calcium and cAMP.

    Directory of Open Access Journals (Sweden)

    Fernando Siso-Nadal

    Full Text Available BACKGROUND: To control and manipulate cellular signaling, we need to understand cellular strategies for information transfer, integration, and decision-making. A key feature of signal transduction is the generation of only a few intracellular messengers by many extracellular stimuli. METHODOLOGY/PRINCIPAL FINDINGS: Here we model molecular cross-talk between two classic second messengers, cyclic AMP (cAMP and calcium, and show that the dynamical complexity of the response of both messengers increases substantially through their interaction. In our model of a non-excitable cell, both cAMP and calcium concentrations can oscillate. If mutually inhibitory, cross-talk between the two second messengers can increase the range of agonist concentrations for which oscillations occur. If mutually activating, cross-talk decreases the oscillation range, but can generate 'bursting' oscillations of calcium and may enable better filtering of noise. CONCLUSION: We postulate that this increased dynamical complexity allows the cell to encode more information, particularly if both second messengers encode signals. In their native environments, it is unlikely that cells are exposed to one stimulus at a time, and cross-talk may help generate sufficiently complex responses to allow the cell to discriminate between different combinations and concentrations of extracellular agonists.

  16. Rancang Bangun Generator Sinkron 1 Fasa Magnet Permanen Kecepatan Rendah 750 RPM

    Directory of Open Access Journals (Sweden)

    Herudin Herudin

    2016-11-01

    Full Text Available Energi listrik merupakan hal yang sangat penting dalam kehidupan manusia untuk meningkatkan kesejahteraan hidup. Untuk memenuhi peningkatan kebutuhan akan energi listrik maka diperlukan juga pengembangan sistem pembangkit energi listrik alternatif yang dapat diperbaharui (renewable . Salah satu komponen utama untuk menghasilkan energi listrik alternatif yaitu generator. Generator berfungsi sebagai perubah energy mekanik menjadi energy listrik. Berdasarkan kondisi tersebut maka pada penelitian ini akan dirancang dan dibuat sebuah generator sinkron magnet permanen 8 kutub, satu fasa dengan menggunakan magnet Neodynium Ferit Boron ( NdFeB tipe Neoflux-30 yang dioperasikan pada kecepatan 750 rpm. Hasil pengujian menunjukan bahwa pada saat generator tidak dibebani menghasilkan tegangan sebesar 7,91 Volt dan pada saat berbeban, tegangan yang dihasilkan generator sebesar 6,11 Volt dengan efisiensi sebesar 32,84% .

  17. The influence of the edge effect on the skyrmion generation in a magnetic nanotrack

    Directory of Open Access Journals (Sweden)

    N. Ran

    2017-02-01

    Full Text Available Magnetic skyrmions might be used for building next-generation nanomagnetic and spintronic devices, as they have several perspective properties, such as topologically protected stability, nanoscale size, and ultra-low depinning current density. Here we study the influence of the edge effect on the current-induced generation of a magnetic skyrmion in a finite-length thin-film ferromagnetic nanotrack with interface-induced Dzyaloshinskii-Moriya interaction. It shows that a stable skyrmion or a bunch of skyrmions can be successfully generated as long as the distance between the current injection region and the nanotrack terminal is larger than a certain threshold. We investigate the failed skyrmion generation caused by the edge effect, which will lead to an error writing event. We also present the phase diagrams of the skyrmion generation obtained for different material and geometric parameters. Our results could be useful for designing skyrmion-based information storage devices.

  18. Reduction of Cogging Torque in Dual Rotor Permanent Magnet Generator for Direct Coupled Wind Energy Systems

    Science.gov (United States)

    Paulsamy, Sivachandran

    2014-01-01

    In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation. In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. This paper is a result of an ongoing research work that deals with various methods to reduce cogging torque in dual rotor radial flux permanent magnet generator (DRFPMG) for direct coupled stand alone wind energy systems (SAWES). Three methods were applied to reduce the cogging torque in DRFPMG. The methods were changing slot opening width, changing magnet pole arc width and shifting of slot openings. A combination of these three methods was applied to reduce the cogging torque to a level suitable for direct coupled SAWES. Both determination and reduction of cogging torque were carried out by finite element analysis (FEA) using MagNet Software. The cogging torque of DRFPMG has been reduced without major change in induced emf. A prototype of 1 kW, 120 rpm DRFPMG was fabricated and tested to validate the simulation results. The test results have good agreement with the simulation predictions. PMID:25202746

  19. Reduction of cogging torque in dual rotor permanent magnet generator for direct coupled wind energy systems.

    Science.gov (United States)

    Paulsamy, Sivachandran

    2014-01-01

    In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation. In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. This paper is a result of an ongoing research work that deals with various methods to reduce cogging torque in dual rotor radial flux permanent magnet generator (DRFPMG) for direct coupled stand alone wind energy systems (SAWES). Three methods were applied to reduce the cogging torque in DRFPMG. The methods were changing slot opening width, changing magnet pole arc width and shifting of slot openings. A combination of these three methods was applied to reduce the cogging torque to a level suitable for direct coupled SAWES. Both determination and reduction of cogging torque were carried out by finite element analysis (FEA) using MagNet Software. The cogging torque of DRFPMG has been reduced without major change in induced emf. A prototype of 1 kW, 120 rpm DRFPMG was fabricated and tested to validate the simulation results. The test results have good agreement with the simulation predictions.

  20. Relaxation of the chiral imbalance and the generation of magnetic fields in magnetars

    Energy Technology Data Exchange (ETDEWEB)

    Dvornikov, M. S., E-mail: maxdvo@izmiran.ru [Ionosphere and Radiowave Propagation (IZMIRAN), Pushkov Institute of Terrestrial Magnetism (Russian Federation)

    2016-12-15

    The model for the generation of magnetic fields in a neutron star, based on the magnetic field instability caused by the electroweak interaction between electrons and nucleons, is developed. Using the methods of the quantum field theory, the helicity flip rate of electrons in their scattering off protons in dense matter of a neutron star is calculated. The influence of the electroweak interaction between electrons and background nucleons on the process of the helicity flip is studied. The kinetic equation for the evolution of the chiral imbalance is derived. The obtained results are applied for the description of the magnetic fields evolution in magnetars.

  1. Encouragement of Enzyme Reaction Utilizing Heat Generation from Ferromagnetic Particles Subjected to an AC Magnetic Field.

    Science.gov (United States)

    Suzuki, Masashi; Aki, Atsushi; Mizuki, Toru; Maekawa, Toru; Usami, Ron; Morimoto, Hisao

    2015-01-01

    We propose a method of activating an enzyme utilizing heat generation from ferromagnetic particles under an ac magnetic field. We immobilize α-amylase on the surface of ferromagnetic particles and analyze its activity. We find that when α-amylase/ferromagnetic particle hybrids, that is, ferromagnetic particles, on which α-amylase molecules are immobilized, are subjected to an ac magnetic field, the particles generate heat and as a result, α-amylase on the particles is heated up and activated. We next prepare a solution, in which α-amylase/ferromagnetic particle hybrids and free, nonimmobilized chitinase are dispersed, and analyze their activities. We find that when the solution is subjected to an ac magnetic field, the activity of α-amylase immobilized on the particles increases, whereas that of free chitinase hardly changes; in other words, only α-amylase immobilized on the particles is selectively activated due to heat generation from the particles.

  2. Encouragement of Enzyme Reaction Utilizing Heat Generation from Ferromagnetic Particles Subjected to an AC Magnetic Field.

    Directory of Open Access Journals (Sweden)

    Masashi Suzuki

    Full Text Available We propose a method of activating an enzyme utilizing heat generation from ferromagnetic particles under an ac magnetic field. We immobilize α-amylase on the surface of ferromagnetic particles and analyze its activity. We find that when α-amylase/ferromagnetic particle hybrids, that is, ferromagnetic particles, on which α-amylase molecules are immobilized, are subjected to an ac magnetic field, the particles generate heat and as a result, α-amylase on the particles is heated up and activated. We next prepare a solution, in which α-amylase/ferromagnetic particle hybrids and free, nonimmobilized chitinase are dispersed, and analyze their activities. We find that when the solution is subjected to an ac magnetic field, the activity of α-amylase immobilized on the particles increases, whereas that of free chitinase hardly changes; in other words, only α-amylase immobilized on the particles is selectively activated due to heat generation from the particles.

  3. Dynamics of self-generated magnetic fields in stagnation phase and their effects on hot spark formation

    International Nuclear Information System (INIS)

    Hata, Akiro; Mima, Kunioki; Nagatomo, Hideo; Sunahara, Atsushi; Nishiguchi, Akio

    2006-01-01

    The generalized temporal evolution equation of a magnetic field is derived for high density laser-fusion plasmas. Magnetic field generation and convection are simulated by using the 2D hydrodynamic code together with the magnetic field equation. It is found that magnetic fields are generated and compressed in association with the Rayleigh-Taylor instability of an imploding shell. In particular, the magnetic field convection by the Nernst effect is found to play an important role in the amplification of magnetic fields. The maximum magnetic field reaches 30 MG at maximum compression. This magnetic field may reduce the electron heat conduction around the hot spark. Therefore, it is concluded that the ignition condition for non-uniform implosion is influenced by self-generated magnetic fields. (author)

  4. Generation of electromagnetic waves and Alfven waves during coalescence of magnetic islands in pair plasmas

    International Nuclear Information System (INIS)

    Sakai, J.I.; Haruki, T.; Kazimura, Y.

    2000-01-01

    It is shown by using a 2-D fully relativistic electromagnetic particle-in-cell (PIC) code that the tearing instability in a current sheet of pair plasmas is caused by Landau resonances of both electrons and positrons. Strong magnetic flux can be generated during coalescence of magnetic islands in the nonlinear phase of the tearing instability. The magnetic flux produced in an O-type magnetic island is caused from the counter-streaming instability found by Kazimura et al. (1998). It is also shown that charge separation with a quadrupole-like structure is generated from the localized strong magnetic flux. During the decay of the quadrupole-like charge structure as well as the magnetic flux, there appear wave emission with high-frequency electromagnetic waves and Alfven waves as well as Langmuir waves. We also show by using a 3-D PIC code that current filaments associated with the O-type magnetic islands become unstable against the kink instability during the coalescence of current filaments. (orig.)

  5. An optimal design of coreless direct-drive axial flux permanent magnet generator for wind turbine

    International Nuclear Information System (INIS)

    Ahmed, D; Ahmad, A

    2013-01-01

    Different types of generators are currently being used in wind power technology. The commonly used are induction generator (IG), doubly-fed induction generator (DFIG), electrically excited synchronous generator (EESG) and permanent magnet synchronous generator (PMSG). However, the use of PMSG is rapidly increasing because of advantages such as higher power density, better controllability and higher reliability. This paper presents an innovative design of a low-speed modular, direct-drive axial flux permanent magnet (AFPM) generator with coreless stator and rotor for a wind turbine power generation system that is developed using mathematical and analytical methods. This innovative design is implemented in MATLAB / Simulink environment using dynamic modelling techniques. The main focus of this research is to improve efficiency of the wind power generation system by investigating electromagnetic and structural features of AFPM generator during its operation in wind turbine. The design is validated by comparing its performance with standard models of existing wind power generators. The comparison results demonstrate that the proposed model for the wind power generator exhibits number of advantages such as improved efficiency with variable speed operation, higher energy yield, lighter weight and better wind power utilization.

  6. An optimal design of coreless direct-drive axial flux permanent magnet generator for wind turbine

    Science.gov (United States)

    Ahmed, D.; Ahmad, A.

    2013-06-01

    Different types of generators are currently being used in wind power technology. The commonly used are induction generator (IG), doubly-fed induction generator (DFIG), electrically excited synchronous generator (EESG) and permanent magnet synchronous generator (PMSG). However, the use of PMSG is rapidly increasing because of advantages such as higher power density, better controllability and higher reliability. This paper presents an innovative design of a low-speed modular, direct-drive axial flux permanent magnet (AFPM) generator with coreless stator and rotor for a wind turbine power generation system that is developed using mathematical and analytical methods. This innovative design is implemented in MATLAB / Simulink environment using dynamic modelling techniques. The main focus of this research is to improve efficiency of the wind power generation system by investigating electromagnetic and structural features of AFPM generator during its operation in wind turbine. The design is validated by comparing its performance with standard models of existing wind power generators. The comparison results demonstrate that the proposed model for the wind power generator exhibits number of advantages such as improved efficiency with variable speed operation, higher energy yield, lighter weight and better wind power utilization.

  7. Investigation on the performance of an optically generated RF local oscillator signal in Ku-band DVB-S systems

    NARCIS (Netherlands)

    Khan, M.R.H.; Marpaung, D.A.I.; Burla, M.; Roeloffzen, C.G.H.; Bernhardi, Edward; de Ridder, R.M.

    2011-01-01

    We investigate a way to externally generate the local oscillator (LO) signal used for downconversion of the Ku-band (10.7 − 12.75 GHz) RF signal received from a phased array antenna (PAA). The signal is then translated to an intermediate frequency (950 − 2150 MHz) at the output of the mixer of

  8. High-Capacity Wireless Signal Generation and Demodulation in 75- to 110-GHz Band Employing All-Optical OFDM

    DEFF Research Database (Denmark)

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

    2011-01-01

    We present a radio-frequency (RF) and bit-rate scalable technique for multigigabit wireless signal generation based on all-optical orthogonal frequency-division multiplexing (OFDM) and photonic up-conversion. Coherent detection supported by digital signal processing is used for signal demodulatio...

  9. Proton nuclear magnetic resonance imaging of regionally ischemic canine hearts: effects of paramagnetic proton signal enhancement

    International Nuclear Information System (INIS)

    Brady, T.J.; Goldman, M.R.; Pykett, I.L.; Buonanno, F.S.; Kistler, J.P.; Newhouse, J.H.; Burt, C.T.; Hinshaw, W.S.; Pohost, G.M.

    1982-01-01

    In a study to evaluate the potential of proton nuclear magnetic resonance (NMR) imaging with and without manganese contrast enhancement for detecting acute myocardial infarction, 12 dogs underwent 90-minute occlusion of the left circumflex coronary artery. Transverse-section NMR images of the excised, nonbeating heart were obtained at 1-cm intervals using the steady-state-free-precession (SSFP) technique. All NMR images revealed detailed structure of the heart. The three hearts without manganese showed no difference in intensity between the normal and the ischemic posterior regions, whereas those with manganese demonstrated a clearly demarcated zone of reduced signal intensity consistent with the ischemic zone. It is concluded that high-resolution tomograms of the excised canine myocardium can be obtained using proton NMR imaging. With the SSFP imaging technique, proton signal enhancement with manganese infusion is necessary to differentiate between ischemic and nonischemic myocardium after 90 minutes of coronary occlusion

  10. Quantitation of magnetic resonance spectroscopy signals: the jMRUI software package

    International Nuclear Information System (INIS)

    Stefan, D; Andrasescu, A; Cesare, F Di; Popa, E; Lazariev, A; Graveron-Demilly, D; Vescovo, E; Williams, S; Strbak, O; Starcuk, Z; Cabanas, M; Van Ormondt, D

    2009-01-01

    The software package jMRUI with Java-based graphical user interface enables user-friendly time-domain analysis of magnetic resonance spectroscopy (MRS) and spectroscopic imaging (MRSI) and HRMAS-NMR signals. Version 3.x has been distributed in more than 1200 groups or hospitals worldwide. The new version 4.x is a plug-in platform enabling the users to add their own algorithms. Moreover, it offers new functionalities compared to versions 3.x. The quantum-mechanical simulator based on NMR-SCOPE, the quantitation algorithm QUEST and the main MRSI functionalities are described. Quantitation results of signals obtained in vivo from a mouse and a human brain are given

  11. Coronary artery stent mimicking intracardiac thrombus on cardiac magnetic resonance imaging due to signal loss

    DEFF Research Database (Denmark)

    Qayyum, Abbas Ali; Vejlstrup, Niels Grove; Ahtarovski, Kiril Aleksov

    2012-01-01

    Since the introduction of percutaneous coronary intervention for coronary artery disease, thousands of patients have been treated with the implantation of coronary stents. Moreover, several of the patients with coronary stent undergo cardiac magnetic resonance (CMR) imaging every year. This case...... report is of a 77-year-old man who was previously treated with the implantation of a coronary stent in the left circumflex artery. He underwent CMR imaging, which revealed a process 14×21 mm in the left atrium. Cardiac contrast computed tomography did not demonstrate any cardiac pathology. While...... the signal loss on MRI associated with implanted metallic devices is known, we report a case where an implanted coronary stent in the left circumflex artery led to an intracardiac signal loss mimicking intracardiac thrombus/tumor....

  12. Loss evaluation and design optimisation for direct driven permanent magnet synchronous generators for wind power

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, Sandra; Bernhoff, Hans [Swedish Centre for Renewable Electric Energy Conversion, Division for Electricity, Department of Engineering Sciences, Uppsala University, Box 534, 751 21 Uppsala (Sweden)

    2011-01-15

    When designing a generator for a wind turbine it is important to adapt the generator to the source, i.e. the wind conditions at the specific site. Furthermore, the variable speed operation of the generator needs to be considered. In this paper, electromagnetic losses in direct driven permanent magnet synchronous generators are evaluated through simulations. Six different generators are compared to each other. The simulations are performed by using an electromagnetic model, solved in a finite element environment and a control model developed in MATLAB. It is shown that when designing a generator it is important to consider the statistical wind distribution, control system, and aerodynamic efficiency in order to evaluate the performance properly. In this paper, generators with high overload capability are studied since they are of interest for this specific application. It is shown that a generator optimised for a minimum of losses will have a high overload capability. (author)

  13. Generation of Long-time Complex Signals for Testing the Instruments for Detection of Voltage Quality Disturbances

    Science.gov (United States)

    Živanović, Dragan; Simić, Milan; Kokolanski, Zivko; Denić, Dragan; Dimcev, Vladimir

    2018-04-01

    Software supported procedure for generation of long-time complex test sentences, suitable for testing the instruments for detection of standard voltage quality (VQ) disturbances is presented in this paper. This solution for test signal generation includes significant improvements of computer-based signal generator presented and described in the previously published paper [1]. The generator is based on virtual instrumentation software for defining the basic signal parameters, data acquisition card NI 6343, and power amplifier for amplification of output voltage level to the nominal RMS voltage value of 230 V. Definition of basic signal parameters in LabVIEW application software is supported using Script files, which allows simple repetition of specific test signals and combination of more different test sequences in the complex composite test waveform. The basic advantage of this generator compared to the similar solutions for signal generation is the possibility for long-time test sequence generation according to predefined complex test scenarios, including various combinations of VQ disturbances defined in accordance with the European standard EN50160. Experimental verification of the presented signal generator capability is performed by testing the commercial power quality analyzer Fluke 435 Series II. In this paper are shown some characteristic complex test signals with various disturbances and logged data obtained from the tested power quality analyzer.

  14. On the theory of magnetic field generation by relativistically strong laser radiation

    International Nuclear Information System (INIS)

    Berezhiani, V.I.; Shatashvili, N.L.; Mahajan, S.M.

    1996-07-01

    The authors consider the interaction of subpicosecond relativistically strong short laser pulses with an underdense cold unmagnetized electron plasma. It is shown that the strong plasma inhomogeneity caused by laser pulses results in the generation of a low frequency (quasistatic) magnetic field. Since the electron density distribution is determined completely by the pump wave intensity, the generated magnetic field is negligibly small for nonrelativistic laser pulses but increases rapidly in the ultrarelativistic case. Due to the possibility of electron cavitation (complete expulsion of electrons from the central region) for narrow and intense beams, the increase in the generated magnetic field slows down as the beam intensity is increased. The structure of the magnetic field closely resembles that of the field produced by a solenoid; the field is maximum and uniform in the cavitation region, then it falls, changes polarity and vanishes. In extremely dense plasmas, highly intense laser pulses in the self-channeling regime can generate magnetic fields ∼ 100 Mg and greater

  15. Reducing costs of wind power with a gearless permanent-magnet generator

    International Nuclear Information System (INIS)

    Vihriaelae, H.; Peraelae, R.; Soederlund, L.; Eriksson, J.T.

    1995-01-01

    This article examines a disc-type axial-field permanent magnet generator (PMG) utilizing the latest generation of permanent magnet material, namely Nd 15 B 8 Fe 77 . A frequency converter (FC) is needed to keep the system synchronized with the grid. It also offers a possibility to use variable speed. The main advantages of this novel system compared to the conventional one are a higher overall efficiency, better reliability, reduced weight and diminished need for maintenance, all contributing to the cost-reduction of wind power. (author)

  16. Reducing costs of wind power with a gearless permanent-magnet generator

    Energy Technology Data Exchange (ETDEWEB)

    Vihriaelae, H; Peraelae, R; Soederlund, L; Eriksson, J T [Tampere Univ. of Technology (Finland). Lab. of Electricity and Magnetism

    1996-12-31

    This article examines a disc-type axial-field permanent magnet generator (PMG) utilizing the latest generation of permanent magnet material, namely Nd{sub 15}B{sub 8}Fe{sub 77}. A frequency converter (FC) is needed to keep the system synchronized with the grid. It also offers a possibility to use variable speed. The main advantages of this novel system compared to the conventional one are a higher overall efficiency, better reliability, reduced weight and diminished need for maintenance, all contributing to the cost-reduction of wind power. (author)

  17. Reducing costs of wind power with a gearless permanent-magnet generator

    Energy Technology Data Exchange (ETDEWEB)

    Vihriaelae, H.; Peraelae, R.; Soederlund, L.; Eriksson, J.T. [Tampere Univ. of Technology (Finland). Lab. of Electricity and Magnetism

    1995-12-31

    This article examines a disc-type axial-field permanent magnet generator (PMG) utilizing the latest generation of permanent magnet material, namely Nd{sub 15}B{sub 8}Fe{sub 77}. A frequency converter (FC) is needed to keep the system synchronized with the grid. It also offers a possibility to use variable speed. The main advantages of this novel system compared to the conventional one are a higher overall efficiency, better reliability, reduced weight and diminished need for maintenance, all contributing to the cost-reduction of wind power. (author)

  18. Magnetic Field Generation through Angular Momentum Exchange between Circularly Polarized Radiation and Charged Particles

    CERN Document Server

    Shvets, G

    2002-01-01

    The interaction between circularly polarized (CP) radiation and charged particles can lead to generation of magnetic field through an inverse Faraday effect. The spin of the circularly polarized electromagnetic wave can be converted into the angular momentum of the charged particles so long as there is dissipation. We demonstrate this by considering two mechanisms of angular momentum absorption relevant for laser-plasma interactions: electron-ion collisions and ionization. The precise dissipative mechanism, however, plays a role in determining the efficiency of the magnetic field generation.

  19. Magnetic Field Generation through Angular Momentum Exchange between Circularly Polarized Radiation and Charged Particles

    International Nuclear Information System (INIS)

    G. Shvets; N.J. Fisch; J.-M. Rax

    2002-01-01

    The interaction between circularly polarized (CP) radiation and charged particles can lead to generation of magnetic field through an inverse Faraday effect. The spin of the circularly polarized electromagnetic wave can be converted into the angular momentum of the charged particles so long as there is dissipation. We demonstrate this by considering two mechanisms of angular momentum absorption relevant for laser-plasma interactions: electron-ion collisions and ionization. The precise dissipative mechanism, however, plays a role in determining the efficiency of the magnetic field generation

  20. Combination of geo- pedo- and technogenic magnetic and geochemical signals in soil profiles - Diversification and its interpretation: A new approach.

    Science.gov (United States)

    Szuszkiewicz, Marcin; Łukasik, Adam; Magiera, Tadeusz; Mendakiewicz, Maria

    2016-07-01

    Magnetic and geochemical parameters of soils are determined with respect to geology, pedogenesis and anthropopression. Depending on local conditions these factors affect magnetic and geochemical signals simultaneously or in various configurations. We examined four type of soils (Entic Podzol, Eutric Cambisol, Humic Cambisol and Dystric Cambisol) developed on various bedrock (the Tumlin Sandstone, basaltoid, amphibolite and serpentinite, respectively). Our primary aim was to characterize the origin and diversification of the magnetic and geochemical signal in soils in order to distinguish the most reliable methods for correct interpretation of measured parameters. Presented data include selected parameters, both magnetic (mass magnetic susceptibility - χ, frequency-dependent magnetic susceptibility - χfd and thermomagnetic susceptibility measurement - TSM), and geochemical (selected heavy metal contents: Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn). Additionally, the enrichment factor (EF) and index of geoaccumulation (Igeo) were calculated. Our results suggest the following: (1) the χ/Fe ratio may be a reliable indicator for determining changes of magnetic signal origin in soil profiles; (2) magnetic and geochemical signals are simultaneously higher (the increment of χ and lead and zinc was noted) in topsoil horizons because of the deposition of technogenic magnetic particles (TMPs); (3) EF and Igeo evaluated for lead and zinc unambiguously showed anthropogenic influence in terms of increasing heavy metal contents in topsoil regardless of bedrock or soil type; (4) magnetic susceptibility measurements supported by TSM curves for soil samples of different genetic horizons are a helpful tool for interpreting the origin and nature of the mineral phases responsible for the changes of magnetic susceptibility values. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Quantification of in vivo 1H magnetic resonance spectroscopy signals with baseline and lineshape estimation

    International Nuclear Information System (INIS)

    Osorio-Garcia, M I; Sima, D M; Van Huffel, S; Nielsen, F U; Dresselaers, T; Himmelreich, U; Van Leuven, F

    2011-01-01

    The in vivo quantification of magnetic resonance spectroscopy (MRS) signals is a method to estimate metabolite concentrations of living tissue. Obtaining reliable concentrations is still a challenge due to the experimental conditions affecting spectral quality. Additionally, lipids and macromolecules overlap with the metabolites of interest, affecting their reliable estimation. In this study, we propose to combine the self-deconvolution lineshape estimation method, which accounts for spectral shape distortions, with two different approaches for taking into account the macromolecular baseline contribution: (a) based on macromolecules and lipids measured in vivo using an inversion recovery technique, and (b) based on the simulation of macromolecular resonances using prior knowledge from a database of inversion recovery signals. The ultimate goal is to measure macromolecular and lipid data only once as described in (a) to create macromolecular and lipid profiles. These profiles then can be used as described in (b) for data measured under the same conditions. The method is evaluated on in vivo 1 H MRS signals at 9.4 T from mouse hippocampus. Results show that better metabolite fits are obtained when lineshape and baseline estimations are simultaneously performed and that baseline estimation based on prior knowledge from macromolecular measured signals can be reliably used to replace time-consuming individual macromolecular and lipid acquisitions

  2. Design and fabrication of radial flux permanent magnet generator for wind turbine applications

    International Nuclear Information System (INIS)

    Ashraf, M.M.; Malik, T.N.; Zafar, S.; Raja, U.N.

    2013-01-01

    Presently alternate energy resources are replacing conventional energy sources to produce electrical power to minimize the usage of fossil fuels. Wind power is one of the potential alternate energy resources and is being exploited and deployed actively. The wind energy system is basically composed of two core components: wind turbine and electrical generator. This paper presents the design and fabrication of permanent magnet generator for direct drive wind turbine applications. Radial flux permanent magnet generator (RFPMG) producing three phase alternating current voltage has been designed subject to satisfying the features of low operating shaft speed, higher power density , higher current density, cost effectiveness and compact structure. RFPMG design focuses on usage of neodymium permanent magnets for excitation instead of electromagnets to minimize the excitation arrangement challenges and losses. A 300 W prototype RFPMG has been fabricated. The performance of the generator has been evaluated on specially designed wind tunnel. The generator is directly coupled with wind turbine shaft to eliminate the gearbox losses. No load and load tests show that the performance of the machine is up to the mark. The improved design parameters of power density and current density are 73.2 W/kg and 5.9 A/mm 2 respectively. The same machine output has been rectified using bridge rectifier for battery charging application. The desired output voltages are obtained at minimum shaft speed of the generator. Thus the design of generator confirms its application with small scale domestic wind turbines produci ng direct current supply. (author)

  3. Explosive magnetic flux compression plate generators as fast high-energy power sources

    International Nuclear Information System (INIS)

    Caird, R.S.; Erickson, D.J.; Garn, W.B.; Fowler, C.M.

    1976-01-01

    A type of explosive driven generator, called a plate generator, is described. It is capable of delivering electrical energies in the MJ range at TW power levels. Plane wave detonated explosive systems accelerate two large-area metal plates to high opposing velocities. An initial magnetic field is compressed and the flux transferred to an external load. The characteristics of the plate generator are described and compared with those of other types of generators. Methods of load matching are discussed. The results of several high-power experiments are also given

  4. GDE2 regulates subtype-specific motor neuron generation through inhibition of Notch signaling.

    Science.gov (United States)

    Sabharwal, Priyanka; Lee, Changhee; Park, Sungjin; Rao, Meenakshi; Sockanathan, Shanthini

    2011-09-22

    The specification of spinal interneuron and motor neuron identities initiates within progenitor cells, while motor neuron subtype diversification is regulated by hierarchical transcriptional programs implemented postmitotically. Here we find that mice lacking GDE2, a six-transmembrane protein that triggers motor neuron generation, exhibit selective losses of distinct motor neuron subtypes, specifically in defined subsets of limb-innervating motor pools that correlate with the loss of force-generating alpha motor neurons. Mechanistically, GDE2 is expressed by postmitotic motor neurons but utilizes extracellular glycerophosphodiester phosphodiesterase activity to induce motor neuron generation by inhibiting Notch signaling in neighboring motor neuron progenitors. Thus, neuronal GDE2 controls motor neuron subtype diversity through a non-cell-autonomous feedback mechanism that directly regulates progenitor cell differentiation, implying that subtype specification initiates within motor neuron progenitor populations prior to their differentiation into postmitotic motor neurons. Copyright © 2011 Elsevier Inc. All rights reserved.

  5. Application of signal processing techniques for islanding detection of distributed generation in distribution network: A review

    International Nuclear Information System (INIS)

    Raza, Safdar; Mokhlis, Hazlie; Arof, Hamzah; Laghari, J.A.; Wang, Li

    2015-01-01

    Highlights: • Pros & cons of conventional islanding detection techniques (IDTs) are discussed. • Signal processing techniques (SPTs) ability in detecting islanding is discussed. • SPTs ability in improving performance of passive techniques are discussed. • Fourier, s-transform, wavelet, HHT & tt-transform based IDTs are reviewed. • Intelligent classifiers (ANN, ANFIS, Fuzzy, SVM) application in SPT are discussed. - Abstract: High penetration of distributed generation resources (DGR) in distribution network provides many benefits in terms of high power quality, efficiency, and low carbon emissions in power system. However, efficient islanding detection and immediate disconnection of DGR is critical in order to avoid equipment damage, grid protection interference, and personnel safety hazards. Islanding detection techniques are mainly classified into remote, passive, active, and hybrid techniques. From these, passive techniques are more advantageous due to lower power quality degradation, lower cost, and widespread usage by power utilities. However, the main limitations of these techniques are that they possess a large non detection zones and require threshold setting. Various signal processing techniques and intelligent classifiers have been used to overcome the limitations of passive islanding. Signal processing techniques, in particular, are adopted due to their versatility, stability, cost effectiveness, and ease of modification. This paper presents a comprehensive overview of signal processing techniques used to improve common passive islanding detection techniques. A performance comparison between the signal processing based islanding detection techniques with existing techniques are also provided. Finally, this paper outlines the relative advantages and limitations of the signal processing techniques in order to provide basic guidelines for researchers and field engineers in determining the best method for their system

  6. Signal generation in highly irradiated silicon microstrip detectors for the ATLAS experiment

    International Nuclear Information System (INIS)

    Ruggiero, Gennaro

    2003-01-01

    Silicon detectors are the most diffused tracking devices in High Energy Physics (HEP). The reason of such success can be found in the characteristics of the material together with the existing advanced technology for the fabrication of these devices. Nevertheless in many modem HEP experiments the observation of vary rare events require data taking at high luminosity with a consequent extremely intense hadron radiation field that damages the silicon and degrades the performance of these devices. In this thesis work a detailed study of the signal generation in microstrip detectors has been produced with a special care for the ATLAS semiconductor tracker geometry. This has required a development of an appropriate setup to perform measurements with Transient Current/ Charge Technique. This has allowed studying the evolution of the signal in several microstrips detector samples irradiated at fluences covering the range expected in the ATLAS Semiconductor Tracker. For a better understanding of these measurements a powerful software package that simulates the signal generation in these devices has been developed. Moreover in this thesis it has been also shown that the degradation due to radiation in silicon detectors can be strongly reduced if the data taking is done with detectors operated at 130 K. This makes low temperature operation that benefits of the recovery of the charge collection efficiency in highly irradiated silicon detectors (also known as Lazarus effect) an optimal option for future high luminosity experiments. (author)

  7. Extraction of two tsunamis signals generated by earthquakes around the Pacific rim

    Directory of Open Access Journals (Sweden)

    Chu Yonghai

    2014-05-01

    Full Text Available As one of the ocean sudden natural disasters, the tsunami is not easily to differentiate from the ocean variation in the open ocean due to the tsunami wave amplitude is lees than one meter with hundreds of kilometers wavelength. But the wave height will increases up to tens of meters with enormous energy when the tsunami aarives at the coast. It would not only devastate entire cities near coast, but also kill miilions of people. It is necessary to forecast and make warning before the tsunami aariving for many countries and regions around the Pacific rim. Two kinds of data were used in this study to extract the signals of 2011 Tohoku tsunami and 2014 Iquique tsunami. Wave undulations from DART (Deep-ocean Assessment and Reporting of Tsunamis buoys and SLA from altimetry could extract the tsunami signals generated by this two earthquake. The signals of Tohoku tsunami were stronger than that of Iquique tsunami probably due to the 2011 Tohoku tsunami was generated by a magnitude 9. 0 earthquake and the 2014 Iquique tsunami was triggered by a magnitude 8. 2 earthquake.

  8. Generation of macroscopic magnetic-field-aligned electric fields by the convection surge ion acceleratiom mechanism

    International Nuclear Information System (INIS)

    Mauk, B.H.

    1989-01-01

    The ''convection surge'' computer model presented previously (concerning the dramatic, nonadiabatic, magnetic-field-aligned energization of ions near the Earth's geosynchronous orbit in the presence of strong, transient, magnetic-field-perpendicular inductive electric fields) has been extended to include the self-consistent generation of magnetic-field-aligned electric fields. The field-aligned electric potential is obtained by imposing the quasi-neutrality condition using approximated electron distribution forms. The ions are forced to respond self-consistently to this potential. It is found that field-aligned potential drops up to 1 to 10 kV can be generated depending on electron temperatures and on the mass species of the ions. During transient periods of the process, these large potential drops can be confined to a few degrees of magnetic latitude at positions close to the magnetic equator. Anomalous, sometimes dramatic, additional magnetic-field-aligned ion acceleration also occurs in part as a result of a quasi-resonance between the parallel velocities of some ions and the propagating electric potential fronts. It is speculated that the convection surge mechanism could be a key player in the transient, field-aligned electromagnetic processes observed to operate within the middle (e.g., geosynchronous) magnetosphere. copyright American Geophysical Union 1989

  9. Design and analysis of a flux intensifying permanent magnet embedded salient pole wind generator

    Science.gov (United States)

    Guo, Yujing; Jin, Ping; Lin, Heyun; Yang, Hui; Lyu, Shukang

    2018-05-01

    This paper presents an improved flux intensifying permanent magnet embedded salient pole wind generator (FI-PMESPWG) with mirror symmetrical magnetizing directions permanent magnet (PM) for improving generator's performances. The air-gap flux densities, the output voltage, the cogging torque and the d- and q-axis inductances of FI-PMESPWG are all calculated and analyzed by using the finite element method (FEM). To highlight the advantages of the proposed FI-PMESPWG, an original permanent magnet embedded salient pole wind generator (PMESPWG) model is adopted for comparison under the same operating conditions. The calculating results show that the air-gap flux densities of FI-PMESPWG are intensified with the same magnet amounts because the PMs are set in a form of V shape in each pole. The difference between d-axis inductance and q-axis inductance of the proposed FI-PMESPWG is reduced. Thus, the output power of the proposed FI-PMESPWG reaches a higher value than that of the original PMESPWG at the same current phase angle. The cogging torque is diminished because the flux path is changed. All the analysis results indicate that the electromagnetic characteristics of the proposed FI-PMESPWG are significantly better than that of the original PMESPWG.

  10. Use of generator substitution to determine the real attenuation of informative signals in the compromising emanation

    Directory of Open Access Journals (Sweden)

    Alexander A. Golyakhov

    2018-05-01

    Full Text Available A determination of real attenuation of information signal's radiation on a way from the source to a possible location of intelligence devices is considered to be the most difficult operation while assessing information security against leakage of electromagnetic emanation. In this context the problem of automation of this kind of measurement is of great interest. It takes considerable effort and time to measure the attenuation by existing automated systems. That is why the measurements are generally taken within the limited range of frequencies only. Along with that, a spectre of a single information impulse has a leaf-structure and is solid on every frequency leaf. So electromagnetic field intensity attenuation measurement carried on the some preselected frequencies is not able to represent the complete attenuation characteristics. The measurements of attenuation in the whole informative signal spectre within the given frequency range requires a few thousand measurements, which makes the current method ineffective and time consuming. The relevant specialized automatized measurement systems of security verification has active protection system noise measurement mode, which can be used to measure the real attenuation. In this article a rather exact method of real attenuation of informative signal of video subsystem of electron-ray tube monitor measurement is described and confirmed in experiment. The measurements were made using specialized automatized system “Sigurd” and video subsystem informative signal noise generator. The described method allows a significant reduction of  the time needed for specialized investigations of security verification on electromagnetic emanation.

  11. Expert system for eddy current signal analysis: non destructive testing of steam generator tubings

    International Nuclear Information System (INIS)

    Benoist, B.

    1991-01-01

    Automatic analysis, by computer, of defect signals in steam generator tubes, based on Eddy current multifrequency technique, is must often inefficient due to pilgrim noise. The first step is to use a method that allows us to eleminate the noise: the adaptative interpolation. Thanks to this method, which ensures reliable data on each channel, the analysis can be realised by taking into account the data corresponding to each basic or mixed channel. By correlating these diverse data, we can class the signals according to two types of defects: single defects (symmetrical), multiple defects (several in the same place). The second step is to use an expert system which allows a reliable diagnosis for whatever family the defect belongs to. According to this classification, analysis is continued and results in the characterization of the defect. The expert system has already been developed with the general purpose application expert system shell SUPER, which is briefly described. The knowledge base (SOCRATE) and the specific tools developed for this application are thoroughly described. The first results obtained with signals corresponding to real defects, that have been recorded in different places, are presented and discussed. The expert system is revealed efficient in all the studied cases, even with signals obtained in very noisy environments [fr

  12. Coordinated Low Voltage Ride through strategies for Permanent Magnet Direct Drive Synchronous Generators

    Directory of Open Access Journals (Sweden)

    Zhang Ge

    2016-01-01

    Full Text Available By analyzing the mechanism of the low voltage ride through on the permanent magnet direct drive synchronous wind power generating units, this paper proposes a coordinated control strategy for permanent magnet synchronous generator. In order to avoid over speed operation of the generation units, over voltage on DC capacitor and over current on convert, the improved pitch angle control and inverter control are used. When the grid voltage drops, the captured wind power is cut down by the variable pitch system, which limits the speed of the generator, the generator side converter keeps the DC capacitor voltage stabile; and the grid side converter provides reactive power to the grid to help the grid voltage recover. The control strategy does not require any additional hardware equipment, with existing control means, the unit will be able to realize low voltage ride through. Finally, based on Matlab/Simulink to build permanent magnet direct drive wind power generation system, the simulation results verify the correctness and effectiveness of the control strategy.

  13. Ultrafast generation of skyrmionic defects with vortex beams: Printing laser profiles on magnets

    Science.gov (United States)

    Fujita, Hiroyuki; Sato, Masahiro

    2017-02-01

    Controlling electric and magnetic properties of matter by laser beams is actively explored in the broad region of condensed matter physics, including spintronics and magneto-optics. Here we theoretically propose an application of optical and electron vortex beams carrying intrinsic orbital angular momentum to chiral ferro- and antiferromagnets. We analyze the time evolution of spins in chiral magnets under irradiation of vortex beams by using the stochastic Landau-Lifshitz-Gilbert equation. We show that beam-driven nonuniform temperature leads to a class of ring-shaped magnetic defects, what we call skyrmion multiplex, as well as conventional skyrmions. We discuss the proper beam parameters and the optimal way of applying the beams for the creation of these topological defects. Our findings provide an ultrafast scheme of generating topological magnetic defects in a way applicable to both metallic and insulating chiral (anti-) ferromagnets.

  14. Study of two medium size 'C' core electromagnets generating low magnetic fields

    International Nuclear Information System (INIS)

    Bhatia, M.S.; Dass, S.; Chatterjee, U.K.

    1987-01-01

    Magnetic field requirements of laboratories may impose constraints that often call for a variety of non-standard designs. The designer has to fulfil these demands without letting the design to become too inefficient. Since no ready design procedures are available he has to resort to intuition calculation and modelling. In spite of this there may be wide discrepancy between the design values and the actual results. This report describes the experience gained on two 'C' core electromagnets being used by authors. These magnets generate low magnetic fields over reasonably large volumes, a requirement that runs opposite to that of most other magnets. The study reveals the dependence of overall performance efficiency, field uniformity etc. on the design parameters. 31 figures. (author)

  15. Thermal Analysis on Radial Flux Permanent Magnet Generator (PMG using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Hilman Syaeful A Syaeful A

    2011-05-01

    Full Text Available The main source of heat in the permanent magnet generator (PMG is the total losses which f come from winding losses, core losses and rotational losses. Total heat arising from such these losses must be properly distributed and maintained so as not to exceed the maximum allowable temperature to prevent damage to insulation on the winding and demagnetization on the permanent magnet machines. In this research, we consider thermal analysis which is occurred on the radial flux PMG by using finite element method to determine the extent to which the heat generated can be properly distributed. The simulation results show that there are no points of heat concentration or hot spot. The simulation maximum temperatures of the permanent magnet and the winding are 39.1oC and 72.5oC respectively while the experimental maximum temperature of the winding is 62oC.

  16. Measurements of magnetic fields generated in underdense plasmas by intense lasers

    International Nuclear Information System (INIS)

    Najmudin, Z.; Walton, B. R.; Mangles, S. P. D.; Dangor, A. E.; Krushelnick, K.; Fritzler, S.; Malka, V.; Faure, J.; Tatarakis, M.

    2006-01-01

    Measurements have been made of the magnetic field generated by the passage of high intensity short laser pulses through underdense plasmas. For a 30 fs, 1 J, 800 nm linearly-polarised laser pulse, an azimuthal magnetic field is observed at a radial extent of approximately 200 μm. The field is found to exceed 2.8 MG. For a 1 ps, 40 J, 1054 nm circularly-polarised laser pulse, a solenoidal field is observed that can exceed 7 MG. This solenoidal field is absent with linear polarised light, and hence can be considered as an Inverse Faraday effect. Both types of field are found to decay on the picosecond timescale. For both the azimuthal and solenoidal fields produced by such intense lasers, the production of energetic electrons by the interaction is thought to be vital for magnetic field generation

  17. Analytic reconstruction of magnetic resonance imaging signal obtained from a periodic encoding field.

    Science.gov (United States)

    Rybicki, F J; Hrovat, M I; Patz, S

    2000-09-01

    We have proposed a two-dimensional PERiodic-Linear (PERL) magnetic encoding field geometry B(x,y) = g(y)y cos(q(x)x) and a magnetic resonance imaging pulse sequence which incorporates two fields to image a two-dimensional spin density: a standard linear gradient in the x dimension, and the PERL field. Because of its periodicity, the PERL field produces a signal where the phase of the two dimensions is functionally different. The x dimension is encoded linearly, but the y dimension appears as the argument of a sinusoidal phase term. Thus, the time-domain signal and image spin density are not related by a two-dimensional Fourier transform. They are related by a one-dimensional Fourier transform in the x dimension and a new Bessel function integral transform (the PERL transform) in the y dimension. The inverse of the PERL transform provides a reconstruction algorithm for the y dimension of the spin density from the signal space. To date, the inverse transform has been computed numerically by a Bessel function expansion over its basis functions. This numerical solution used a finite sum to approximate an infinite summation and thus introduced a truncation error. This work analytically determines the basis functions for the PERL transform and incorporates them into the reconstruction algorithm. The improved algorithm is demonstrated by (1) direct comparison between the numerically and analytically computed basis functions, and (2) reconstruction of a known spin density. The new solution for the basis functions also lends proof of the system function for the PERL transform under specific conditions.

  18. Generation and tunable enhancement of a sum-frequency signal in lithium niobate nanowires

    Science.gov (United States)

    Sergeyev, Anton; Reig Escalé, Marc; Grange, Rachel

    2017-02-01

    Recent developments in the fabrication of lithium niobate (LiNbO3) structures down to the nanoscale opens up novel applications of this versatile material in nonlinear optics. Current nonlinear optical studies in sub-micron waveguides are mainly restricted to the generation of second and third harmonics. In this work, we demonstrate the generation and waveguiding of the sum-frequency generation (SFG) signal in a single LiNbO3 nanowire with a cross-section of 517 nm  ×  654 nm. Furthermore, we enhance the guided SFG signal 17.9 times by means of modal phase matching. We also display tuning of the phase-matched wavelength by varying the nanowire cross-section and changing the polarization of the incident laser. The results prove that LiNbO3 nanowires can be successfully used for nonlinear wave-mixing applications and assisting the miniaturization of optical devices. , which features invited work from the best early-career researchers working within the scope of J Phys D. This project is part of the Journal of Physics series’ 50th anniversary celebrations in 2017. Rachel Grange was selected by the Editorial Board of J Phys D as an Emerging Leader.

  19. Digital Signal Processing and Generation for a DC Current Transformer for Particle Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Zorzetti, Silvia [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2013-01-01

    The thesis topic, digital signal processing and generation for a DC current transformer, focuses on the most fundamental beam diagnostics in the field of particle accelerators, the measurement of the beam intensity, or beam current. The technology of a DC current transformer (DCCT) is well known, and used in many areas, including particle accelerator beam instrumentation, as non-invasive (shunt-free) method to monitor the DC current in a conducting wire, or in our case, the current of charged particles travelling inside an evacuated metal pipe. So far, custom and commercial DCCTs are entirely based on analog technologies and signal processing, which makes them inflexible, sensitive to component aging, and difficult to maintain and calibrate.

  20. Eddy currents signal processing for steam generator inspection in PWR nuclear power plants

    International Nuclear Information System (INIS)

    Georgel, B.

    1992-01-01

    Steam generator tubes in nuclear power plants are periodically checked by means of eddy current probes. The output of a probe is composed of three types of signals: known events (rolling zone, support plates, U-bend part), noise (mainly metallurgical noise) and possible flaws. The latter are random transients, both in arrival time and in shape: they have to be detected and then estimated, before to be fed to the high level stages of a diagnostic system. The objective of the study presented is to develop a semi-automatic system, which could manage and process more than 1 M-bytes of data per tube and provide an operator with reliable diagnostics proposals within a few minutes. This can be achieved only by cooperation of several digital signal processing techniques: detection, segmentation, estimation, noise subtraction, adaptive filtering, modelization, pattern recognition. The paper describes some of these items

  1. Thermal generation of the magnetic field in the surface layers of massive stars

    Science.gov (United States)

    Urpin, V.

    2017-11-01

    A new magnetic field-generation mechanism based on the Nernst effect is considered in hot massive stars. This mechanism can operate in the upper atmospheres of O and B stars where departures from the LTE form a region with the inverse temperature gradient.

  2. Generation mechanisms for magnetic-field-aligned electric fields in the magnetosphere

    International Nuclear Information System (INIS)

    Faelthammar, C.-G.

    1977-09-01

    Magnetic-field-aligned electric fields in the magnetosphere can be generated in several different ways, and in this review some possible mechanisms are presented. Observational data now available indicates that more than one of the mechanisms mentioned are operative in the magnetosphere but it is not yet possible to evaluate their relative importance. (author)

  3. Development of FEMAG. Calculation code of magnetic field generated by ferritic plates in the tokamak devices

    Energy Technology Data Exchange (ETDEWEB)

    Urata, Kazuhiro [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    2003-03-01

    In design of the future fusion devises in which low activation ferritic steel is planned to use as the plasma facing material and/or the inserts for ripple reduction, the appreciation of the error field effect against the plasma as well as the optimization of ferritic plate arrangement to reduce the toroidal field ripple require calculation of magnetic field generated by ferritic steel. However iterative calculations concerning the non-linearity in B-H curve of ferritic steel disturbs high-speed calculation required as the design tool. In the strong toroidal magnetic field that is characteristic in the tokamak fusion devices, fully magnetic saturation of ferritic steel occurs. Hence a distribution of magnetic charges as magnetic field source is determined straightforward and any iteration calculation are unnecessary. Additionally objective ferritic steel geometry is limited to the thin plate and ferritic plates are installed along the toroidal magnetic field. Taking these special conditions into account, high-speed calculation code ''FEMAG'' has been developed. In this report, the formalization of 'FEMAG' code, how to use 'FEMAG', and the validity check of 'FEMAG' in comparison with a 3D FEM code, with the measurements of the magnetic field in JFT-2M are described. The presented examples are numerical results of design studies for JT-60 modification. (author)

  4. New generation of cryogen free advanced superconducting magnets for neutron scattering experiments

    International Nuclear Information System (INIS)

    Kirichek, O; Adroja, D T; Manuel, P; Bewley, R I; Brown, J; Kouzmenko, G; Wotherspoon, R

    2012-01-01

    Recent advances in superconducting technology and cryocooler refrigeration have resulted in a new generation of advanced superconducting magnets for neutron beam applications. These magnets have outstanding parameters such as high homogeneity and stability at highest magnetic fields possible, a reasonably small stray field, low neutron scattering background and larger exposure to neutron detectors. At the same time the pulse tube refrigeration technology provides a complete re-condensing regime which allows to minimise the requirements for cryogens without introducing additional noise and mechanical vibrations. The magnets can be used with dilution refrigerator insert which expands the temperature range from 20mK to 300K. Here we are going to present design, test results and the operational data of the 14T magnet for neutron diffraction and the 9T wide angle chopper magnet for neutron spectroscopy developed by Oxford Instruments in collaboration with ISIS neutron source. First scientific results obtained from the neutron scattering experiments with these magnets are also going to be discussed.

  5. A novel HTS SMES application in combination with a permanent magnet synchronous generator type wind power generation system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, G.H.; Kim, A.R.; Kim, S. [Changwon National University, 9 Sarim-dong, Changwon 641-773 (Korea, Republic of); Park, M., E-mail: paku@changwon.ac.kr [Changwon National University, 9 Sarim-dong, Changwon 641-773 (Korea, Republic of); Yu, I.K. [Changwon National University, 9 Sarim-dong, Changwon 641-773 (Korea, Republic of); Seong, K.C. [Superconducting Device and Cryogenics Group, Korea Electrotechnology Research Institute, Changwon 641-120 (Korea, Republic of); Won, Y.J. [Korea Electric Power Corporation, Changwon 641-241 (Korea, Republic of)

    2011-11-15

    A novel connection topology of SMES is proposed in this paper. Structure of the proposed system is cost-effective because it reduces a converter. The proposed system smoothens output power of wind power generation system. Advantage of the system is to improve the low voltage ride through capability. Superconducting magnetic energy storage (SMES) system is a DC current driven device and can be utilized to improve power quality particularly in connection with renewable energy sources due to higher efficiency and faster response than other devices. This paper suggests a novel connection topology of SMES which can smoothen the output power flow of the wind power generation system (WPGS). The structure of the proposed system is cost-effective because it reduces a power converter in comparison with a conventional application of SMES. One more advantage of SMES in the proposed system is to improve the capability of low voltage ride through (LVRT) for the permanent magnet synchronous generator (PMSG) type WPGS. The proposed system including a SMES has been modeled and analyzed by a PSCAD/EMTDC. The simulation results show the effectiveness of the novel SMES application strategy to not only mitigate the output power of the PMSG but also improve the capability of LVRT for PMSG type WPGS.

  6. A novel HTS SMES application in combination with a permanent magnet synchronous generator type wind power generation system

    International Nuclear Information System (INIS)

    Kim, G.H.; Kim, A.R.; Kim, S.; Park, M.; Yu, I.K.; Seong, K.C.; Won, Y.J.

    2011-01-01

    A novel connection topology of SMES is proposed in this paper. Structure of the proposed system is cost-effective because it reduces a converter. The proposed system smoothens output power of wind power generation system. Advantage of the system is to improve the low voltage ride through capability. Superconducting magnetic energy storage (SMES) system is a DC current driven device and can be utilized to improve power quality particularly in connection with renewable energy sources due to higher efficiency and faster response than other devices. This paper suggests a novel connection topology of SMES which can smoothen the output power flow of the wind power generation system (WPGS). The structure of the proposed system is cost-effective because it reduces a power converter in comparison with a conventional application of SMES. One more advantage of SMES in the proposed system is to improve the capability of low voltage ride through (LVRT) for the permanent magnet synchronous generator (PMSG) type WPGS. The proposed system including a SMES has been modeled and analyzed by a PSCAD/EMTDC. The simulation results show the effectiveness of the novel SMES application strategy to not only mitigate the output power of the PMSG but also improve the capability of LVRT for PMSG type WPGS.

  7. Neuropeptidomics Mass Spectrometry Reveals Signaling Networks Generated by Distinct Protease Pathways in Human Systems

    Science.gov (United States)

    Hook, Vivian; Bandeira, Nuno

    2015-12-01

    Neuropeptides regulate intercellular signaling as neurotransmitters of the central and peripheral nervous systems, and as peptide hormones in the endocrine system. Diverse neuropeptides of distinct primary sequences of various lengths, often with post-translational modifications, coordinate and integrate regulation of physiological functions. Mass spectrometry-based analysis of the diverse neuropeptide structures in neuropeptidomics research is necessary to define the full complement of neuropeptide signaling molecules. Human neuropeptidomics has notable importance in defining normal and dysfunctional neuropeptide signaling in human health and disease. Neuropeptidomics has great potential for expansion in translational research opportunities for defining neuropeptide mechanisms of human diseases, providing novel neuropeptide drug targets for drug discovery, and monitoring neuropeptides as biomarkers of drug responses. In consideration of the high impact of human neuropeptidomics for health, an observed gap in this discipline is the few published articles in human neuropeptidomics compared with, for example, human proteomics and related mass spectrometry disciplines. Focus on human neuropeptidomics will advance new knowledge of the complex neuropeptide signaling networks participating in the fine control of neuroendocrine systems. This commentary review article discusses several human neuropeptidomics accomplishments that illustrate the rapidly expanding diversity of neuropeptides generated by protease processing of pro-neuropeptide precursors occurring within the secretory vesicle proteome. Of particular interest is the finding that human-specific cathepsin V participates in producing enkephalin and likely other neuropeptides, indicating unique proteolytic mechanisms for generating human neuropeptides. The field of human neuropeptidomics has great promise to solve new mechanisms in disease conditions, leading to new drug targets and therapeutic agents for human

  8. Strong Static Magnetic Fields Increase the Gel Signal in Partially Hydrated DPPC/DMPC Membranes.

    Science.gov (United States)

    Tang, Jennifer; Alsop, Richard J; Schmalzl, Karin; Epand, Richard M; Rheinstädter, Maikel C

    2015-09-29

    NIt was recently reported that static magnetic fields increase lipid order in the hydrophobic membrane core of dehydrated native plant plasma membranes [Poinapen, Soft Matter 9:6804-6813, 2013]. As plasma membranes are multicomponent, highly complex structures, in order to elucidate the origin of this effect, we prepared model membranes consisting of a lipid species with low and high melting temperature. By controlling the temperature, bilayers coexisting of small gel and fluid domains were prepared as a basic model for the plasma membrane core. We studied molecular order in mixed lipid membranes made of dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) using neutron diffraction in the presence of strong static magnetic fields up to 3.5 T. The contribution of the hydrophobic membrane core was highlighted through deuterium labeling the lipid acyl chains. There was no observable effect on lipid organization in fluid or gel domains at high hydration of the membranes. However, lipid order was found to be enhanced at a reduced relative humidity of 43%: a magnetic field of 3.5 T led to an increase of the gel signal in the diffraction patterns of 5%. While all biological materials have weak diamagnetic properties, the corresponding energy is too small to compete against thermal disorder or viscous effects in the case of lipid molecules. We tentatively propose that the interaction between the fatty acid chains' electric moment and the external magnetic field is driving the lipid tails in the hydrophobic membrane core into a better ordered state.

  9. Strong Static Magnetic Fields Increase the Gel Signal in Partially Hydrated DPPC/DMPC Membranes

    Directory of Open Access Journals (Sweden)

    Jennifer Tang

    2015-09-01

    Full Text Available NIt was recently reported that static magnetic fields increase lipid order in the hydrophobic membrane core of dehydrated native plant plasma membranes [Poinapen, Soft Matter 9:6804-6813, 2013]. As plasma membranes are multicomponent, highly complex structures, in order to elucidate the origin of this effect, we prepared model membranes consisting of a lipid species with low and high melting temperature. By controlling the temperature, bilayers coexisting of small gel and fluid domains were prepared as a basic model for the plasma membrane core. We studied molecular order in mixed lipid membranes made of dimyristoyl-sn-glycero-3-phosphocholine (DMPC and dipalmitoyl-sn-glycero-3-phosphocholine (DPPC using neutron diffraction in the presence of strong static magnetic fields up to 3.5 T. The contribution of the hydrophobic membrane core was highlighted through deuterium labeling the lipid acyl chains. There was no observable effect on lipid organization in fluid or gel domains at high hydration of the membranes. However, lipid order was found to be enhanced at a reduced relative humidity of 43%: a magnetic field of 3.5 T led to an increase of the gel signal in the diffraction patterns of 5%. While all biological materials have weak diamagnetic properties, the corresponding energy is too small to compete against thermal disorder or viscous effects in the case of lipid molecules. We tentatively propose that the interaction between the fatty acid chains’ electric moment and the external magnetic field is driving the lipid tails in the hydrophobic membrane core into a better ordered state.

  10. Incidence and Evaluation of Incidental Abnormal Bone Marrow Signal on Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    Gunjan L. Shah

    2014-01-01

    Full Text Available Purpose. The increased use of magnetic resonance imaging (MRI has resulted in reports of incidental abnormal bone marrow (BM signal. Our goal was to determine the evaluation of an incidental abnormal BM signal on MRI and the prevalence of a subsequent oncologic diagnosis. Methods. We conducted a retrospective cohort study of patients over age 18 undergoing MRI between May 2005 and October 2010 at Tufts Medical Center (TMC with follow-up through November 2013. The electronic medical record was queried to determine imaging site, reason for scan, evaluation following radiology report, and final diagnosis. Results. 49,678 MRIs were done with 110 patients meeting inclusion criteria. Twenty two percent underwent some evaluation, most commonly a complete blood count, serum protein electrophoresis, or bone scan. With median follow-up of 41 months, 6% of patients were diagnosed with malignancies including multiple myeloma, non-Hodgkins lymphoma, metastatic non-small cell lung cancer, and metastatic adenocarcinoma. One patient who had not undergone evaluation developed breast cancer 24 months after the MRI. Conclusions. Incidentally noted abnormal or heterogeneous bone marrow signal on MRI was not inconsequential and should prompt further evaluation.

  11. On the energy flux of a signal in a moving magnetized plasma

    International Nuclear Information System (INIS)

    Gavrilenko, V.G.; Zelekson, L.A.

    1980-01-01

    Energy exchange of an electromagnetic signal with a homogeneous plasma moving along a strong magnetic field, provided that the initial signal is given in a plane parallel or normal to the drift velocity, has been analyzed. In the first case expressions for the fields excited in the long-range zone are obtained by the stationary phase method. It follows from the expressions that starting from some moment of time the direction of the energy flux and the sign of the energy density change into opposite. This is caused by the fact that the fast harmonic components (with a phase velocity exceeding the drift velocity) of the initial signal reach first the point of observation, and then the slow ones do, the energy density of the show waves being negative. On longitudinal propagation of perturbations excited by a quasimonochromatic source, the averaged flux and energy density in the weakly relativistic approximation have been shown to be zero. In conclusion electromagnetic waves moving with a superlight velocity in a non-dispersive medium are studied, the energy of the waves changing the sign with time [ru

  12. Application of permanent magnet BaFe12O19 and NdFeB on small scale low speed permanent magnet generator

    International Nuclear Information System (INIS)

    Pudji Irasari; Novrita Idayanti

    2009-01-01

    Designing and manufacturing of low speed permanent magnet generator (PMG) for small scale electric power plant have been conducted. In this paper, the characteristics of generator using permanent magnet of barium ferrite (BaFe 12 O 19 ) and neodymium iron boron (NdFeB) were compared. Surface mounted type is selected as the rotor structure as all flux faces to stator winding and take a role in energy conversion. The experiment result demonstrates that at nominal speed, generator with BaFe 12 O 19 magnet can only generate power of 8.87 W while generator with NdFeB magnet can generate power of 1,988.93 W. (author)

  13. Design Optimization and Site Matching of Direct-Drive Permanent Magnet Wind Generator Systems

    DEFF Research Database (Denmark)

    Li, H.; Chen, Zhe

    2009-01-01

    This paper investigates the possible site matching of the direct-drive wind turbine concepts based on the electromagnetic design optimization of permanent magnet (PM) generator systems. Firstly, the analytical models of a three-phase radial-flux PM generator with a back-to-back power converter...... of the maximum wind energy capture, the rotor diameter and the rated wind speed of a direct-drive wind turbine with the optimum PM generator are determined. The annual energy output (AEO) is also presented using the Weibull density function. Finally, the maximum AEO per cost (AEOPC) of the optimized wind...... are presented. The optimum design models of direct-drive PM wind generation system are developed with an improved genetic algorithm, and a 500-kW direct-drive PM generator for the minimal generator active material cost is compared to demonstrate the effectiveness of the design optimization. Forty-five PM...

  14. MODELING AND STUDY OF HYDROELECTRIC GENERATING SETS OF SMALL HYDRO POWER PLANTS WITH FREQUENCY-CONTROLLED PERMANENT MAGNET SYNCHRONOUS GENERATORS

    Directory of Open Access Journals (Sweden)

    R. I. Mustafayev

    2016-01-01

    Full Text Available Currently, the hydroelectric generating sets of small HPPs with Pelton turbines employ as their generating units conventional synchronous generators with electromagnetic excitation. To deal with the torque pulsatile behaviour, they generally install a supplementary flywheel on the system shaft that levels the pulsations. The Pelton turbine power output is adjusted by the needle changing water flow in the nozzle, whose advancement modifies the nozzle area and eventually – the flow. They limit the needle full stroke time to 20–40 sec. since quick shutting the nozzle for swift water flow reduction may result in pressure surges. For quick power adjustment so-called deflectors are employed, whose task is retraction of water jets from the Pelton turbine buckets. Thus, the mechanical method of power output regulation requires agreement between the needle stroke inside the turbine nozzles and the deflector. The paper offers employing frequency-controlled synchronous machines with permanent magnets qua generating units for the hydroelectric generating sets of small HPPs with Pelton turbines. The developed computer model reveals that this provides a higher level of adjustability towards rapid-changing loads in the grid. Furthermore, this will replace the power output mechanical control involving the valuable deflector drive and the turbine nozzle needles with electrical revolution rate and power output regulation by a frequency converter located in the generator stator circuit. Via frequency start, the controllable synchronous machine ensures stable operation of the hydroelectric generating set with negligibly small amount of water (energy carrier. Finally, in complete absence of water, the frequency-relay start facilitates shifting the generator operation to the synchronous capacitor mode, which the system operating parameter fluctograms obtained through computer modeling prove. 

  15. Four New Applications of Second-Order Generalized Integrator Quadrature Signal Generator

    DEFF Research Database (Denmark)

    Xin, Zhen; Zhao, Rende; Wang, Xiongfei

    2016-01-01

    The Second-Order Generalized Integrator (SOGI) was used as a building block for the SOGI-Quadrature-Signal Generator (SOGI-QSG) which has been widely used for grid synchronization, frequency estimation, and harmonic extraction over the past decade. This paper further investigates its integration...... and differentiation characteristics, with four new integrators and differentiators proposed. Theoretical analysis shows that the proposed SOGI-QSG based integration and differentiation methods can effectively overcome the drawbacks of the pure integrator and differentiator. The proposed four new methods...

  16. Signal Characteristics of Eddy Current Test for Intergranular Attack of Steam Generator Tubes

    International Nuclear Information System (INIS)

    Choi, Myung Sik; Lee, Deok Hyun; Han, Jung Ho; Hur, Do Haeng; Cho, Se Gon; Yim, Chang Jae

    2002-01-01

    Because intergranular attack (IGA), one of the localized corrosion forms occurring on steam generator tubes, can not be fabricated by an electric discharge machining method, there are few data for the eddy current test (ECT) characteristics of IGA. In this paper, the characteristics of eddy current signals are evaluated using nonexpanded tubes with IGA defects formed in 0.1 M sodium tetrathionate solution at 40 .deg. C. The detectability and sizing accuracy of IGA were discussed in terms of the coil type and frequency of the ECT probes

  17. Analysis of Magnetic Resonance Image Signal Fluctuations Acquired During MR-Guided Radiotherapy.

    Science.gov (United States)

    Breto, Adrian L; Padgett, Kyle R; Ford, John C; Kwon, Deukwoo; Chang, Channing; Fuss, Martin; Stoyanova, Radka; Mellon, Eric A

    2018-03-28

    Magnetic resonance-guided radiotherapy (MRgRT) is a new and evolving treatment modality that allows unprecedented visualization of the tumor and surrounding anatomy. MRgRT includes daily 3D magnetic resonance imaging (MRI) for setup and rapidly repeated near real-time MRI scans during treatment for target tracking. One of the more exciting potential benefits of MRgRT is the ability to analyze serial MRIs to monitor treatment response or predict outcomes. A typical radiation treatment (RT) over the span of 10-15 minutes on the MRIdian system (ViewRay, Cleveland, OH) yields thousands of "cine" images, each acquired in 250 ms. This unique data allows for a glimpse in image intensity changes during RT delivery. In this report, we analyze cine images from a single fraction RT of a glioblastoma patient on the ViewRay platform in order to characterize the dynamic signal changes occurring during RT therapy. The individual frames in the cines were saved into DICOM format and read into an MIM image analysis platform (MIM Software, Cleveland, OH) as a time series. The three possible states of the three Cobalt-60 radiation sources-OFF, READY, and ON-were also recorded. An in-house Java plugin for MIM was created in order to perform principal component analysis (PCA) on each of the datasets. The analysis resulted in first PC, related to monotonous signal increase over the course of the treatment fraction. We found several distortion patterns in the data that we postulate result from the perturbation of the magnetic field due to the moving metal parts in the platform while treatment was being administered. The largest variations were detected when all Cobalt-60 sources were OFF. During this phase of the treatment, the gantry and multi-leaf collimators (MLCs) are moving. Conversely, when all Cobalt-60 sources were in the ON position, the image signal fluctuations were minimal, relating to very little mechanical motion. At this phase, the gantry, the MLCs, and sources are fixed

  18. Damping System for Torsional Resonances in Generator Shafts Using a Feedback Controlled Buffer Storage of Magnetic Energy at ASDEX Upgrade

    International Nuclear Information System (INIS)

    Kaesemann, C.-P.; Huart, M.; Mueller, P.; Sigalov, A.

    2006-01-01

    The electrical power and energy for ASDEX Upgrade (AUG) is provided by three separate pulsed networks based on flywheel generators. Major damages at couplings of the shaft of the synchronous generator EZ4 (220 MVA / 600 MWs) were discovered during a routine check. The damage can only be explained by torsional resonances in the generator shaft which are excited by active power transients from the converter loads. For generator protection, torque sensors were installed near the coupling between the flywheel and the rotor. They cause an early termination of plasma experiments if a predefined torque level is exceeded. These terminations limited the achievable plasma current flattop time of AUG significantly. Since a low natural damping of the torsional resonances was identified as a major cause of the phenomena observed, novel feedback controlled DC circuits were developed providing electromagnetic damping for the generator shafts in case of excitation. Each damping circuit consists of a DC choke, acting as a buffer storage of magnetic energy, fed by a thyristor converter. The current reference for the converter is derived from the torque sensor signals. This enables the choke current to alternate with the measured natural frequency of the shaft assembly. Thus, with proper phasing, torsional resonances in generator shaft systems weighing more than 100 tons can be damped with little additional power. Since April 2003, the damping circuits have been routinely operated during all plasma experiments. Despite the low damping power used, torsional resonances could be reduced to a value that avoids a trip signal from the torque sensors. This paper describes the results from analysing, designing and testing of the feedback controlled buffer storage of magnetic energy, representing an effective and low cost solution for damping torsional resonances in electric power systems. It will present the layout, analyse the results of measurements obtained during commissioning and

  19. Stability Augmentation of Wind Farm using Variable Speed Permanent Magnet Synchronous Generator

    Science.gov (United States)

    Rosyadi, Marwan; Muyeen, S. M.; Takahashi, Rion; Tamura, Junji

    This paper presents a new control strategy of variable speed permanent magnet wind generator for stability augmentation of wind farm including fixed speed wind turbine with Induction Generator (IG). A new control scheme is developed for two levels back-to-back converters of Permanent Magnet Synchronous Generator (PMSG), by which both active and reactive powers delivered to the grid can be controlled easily. To avoid the converter damage, the DC link protection controller is also proposed in order to protect the dc link circuit during fault condition. To evaluate the control capability of the proposed controllers, simulations are performed on two model systems composed of wind farms connected to an infinite bus. From transient and steady state analyses by using PSCAD/EMTDC, it is concluded that the proposed control scheme is very effective to improve the stability of wind farm for severe network disturbance and randomly fluctuating wind speed.

  20. Changes in Earth's core-generated magnetic field, as observed by Swarm

    DEFF Research Database (Denmark)

    Finlay, Chris; Olsen, Nils; Gillet, Nicolas

    By far the largest part of the Earth's magnetic field is generated by motions taking place within our planet's liquid metal outer core. Variations of this core-generated field thus provide us with a unique means of probing the dynamics taking place in the deepest reaches of the Earth....... In this contribution, we will present the core-generated magnetic field, and its recent time changes, as seen by ESA's Earth explorer mission Swarm. We will present a new time-dependent geomagnetic field model, called CHAOS-6, derived from satellite data collected by the Swarm constellation, as well as data from...... the previous missions CHAMP and Oersted together with ground observatory data. Advantage is taken of the constellation aspect of the Swarm mission by ingesting field differences along track and across track between the lower pair of Swarm satellites. Evaluating the global field model at the outer boundary...

  1. A Permanent-Magnet Microwave Ion Source for a Compact High-Yield Neutron Generator

    International Nuclear Information System (INIS)

    Waldmann, Ole; Ludewigt, Bernhard

    2010-01-01

    We present recent work on the development of a microwave ion source that will be used in a high-yield compact neutron generator for active interrogation applications. The sealed tube generator will be capable of producing high neutron yields, 5 · 10 11 n/s for D-T and ∼ 1 · 10 10 n/s for D-D reactions, while remaining transportable. We constructed a microwave ion source (2.45 GHz) with permanent magnets to provide the magnetic field strength of 87.5 mT necessary for satisfying the electron cyclotron resonance (ECR) condition. Microwave ion sources can produce high extracted beam currents at the low gas pressures required for sealed tube operation and at lower power levels than previously used RF-driven ion sources. A 100 mA deuterium/tritium beam will be extracted through a large slit (60 · 6 mm 2 ) to spread the beam power over a larger target area. This paper describes the design of the permanent-magnet microwave ion source and discusses the impact of the magnetic field design on the source performance. The required equivalent proton beam current density of 40 mA/cm 2 was extracted at a moderate microwave power of 400 W with an optimized magnetic field.

  2. Evaluation of the attractive force of different types of new-generation magnetic attachment systems.

    Science.gov (United States)

    Akin, Hakan; Coskun, M Emre; Akin, E Gulsah; Ozdemir, A Kemal

    2011-03-01

    Rare earth magnets have been used in prosthodontics, but their tendency for corrosion in the oral cavity and insufficient attractive forces limit long-term clinical application. The purpose of this study was to evaluate the attractive force of different types of new-generation magnetic attachment systems. The attractive force of the neodymium-iron-boron (Nd-Fe-B) and samarium-cobalt (Sm-Co) magnetic attachment systems, including closed-field (Hilop and Hicorex) and open-field (Dyna and Steco) systems, was measured in a universal testing machine (n=5). The data were statistically evaluated with 1-way ANOVA and post hoc Tukey-Kramer multiple comparison test (α=.05). The closed-field systems exhibited greater (Pattractive force than the open-field systems. Moreover, there was a statistically significant difference in attractive force between Nd-Fe-B and Sm-Co magnets (Pattractive force was found with the Hilop system (9.2 N), and the lowest force was found with the Steco system (2.3 N). The new generation of Nd-Fe-B closed-field magnets, along with improved technology, provides sufficient denture retention for clinical application. Copyright © 2011 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  3. Self-Generated Magnetic Fields in Stagnation-Phase ICF Implosions

    Science.gov (United States)

    Walsh, Christopher; Chittenden, Jeremy; McGlinchey, Kristopher; Niasse, Nicolas

    2016-10-01

    3-D extended-MHD simulations of the stagnation phase of an ICF implosion are presented, showing significant self-generated magnetic fields (1000-5000T) due to the Biermann Battery effect. Perturbed hot-spots generate magnetic fields at their edges, as the extremities of hot bubbles are rapidly cooled by the surrounding low temperature fuel, giving non-parallel electron pressure and density gradients. Larger amplitude and higher mode-number perturbations lead to an increased hot-spot surface area and more heat flow, developing greater non-parallel gradients and therefore larger magnetic fields. Due to this, largely perturbed hot-spots can be affected more by magnetic fields, although the accelerated cooling associated with greater deviations from symmetry lowers magnetisation. The Nernst effect advects magnetic field down temperature gradients towards the outer region of the hot-spot, which can also lower the magnetisation of the plasma. In some regions, however, the Nernst velocity is convergent, magnetising the tips of cold fuel spikes, resulting in anisotropic heat-flow and an improvement in energy containment. Low-mode and multi-high-mode simulations are shown, with magnetisations reaching sufficiently high levels in some regions of the hot-spot to suppress thermal conduction to lower than 50% of the unmagnetised case. A quantitative analysis of how this affects the hot-spot energy balance is included.

  4. Modal analysis of a grid-connected direct-drive permanent magnet synchronous generator wind turbine system

    DEFF Research Database (Denmark)

    Tan, Jin; Wang, Xiao Ru; Chen, Zhe

    2013-01-01

    In order to study the stability of a grid-connected direct-drive permanent magnet synchronous generator (PMSG) wind turbine systems, this paper presents the modal analysis of a PMSG wind turbine system. A PMSG model suitable for small signal stability analysis is presented. The modal properties...... of a grid-connected PMSG wind turbine system are studied. Then the comprehensive impacts of the shaft model, shaft parameters, operation points and lengths of the transmission line on the modal characteristic of the system are investigated by the eigenvalue analysis method. Meanwhile, the corresponding...... analysis. It offers a better understanding about the essence of the stability of grid-connected PMSG wind turbine system....

  5. The electrical conductivity of the upper mantle and lithosphere from satellite magnetic signal due to ocean tidal flow

    Science.gov (United States)

    Schnepf, N. R.; Kuvshinov, A. V.; Grayver, A.; Sabaka, T. J.; Olsen, N.

    2015-12-01

    Global electromagnetic (EM) studies provide information on mantle electrical conductivity with the ultimate aim of understanding the composition, structure, and dynamics of Earth's interior. There is great much interest in mapping the global conductivity of the lithosphere and upper mantle (i.e., depths of 10-400 km) because recent laboratory experiments demonstrate that the electrical conductivity of minerals in these regions are greatly affected by small amounts of water or by partial melt. For decades, studies of lithospheric/mantle conductivity were based on interpretation of magnetic data from a global network of observatories. The recent expansion in magnetic data from low-Earth orbiting satellite missions (Ørsted, CHAMP, SAC-C, and Swarm) has led to a rising interest in probing Earth from space. The largest benefit of using satellite data is much improved spatial coverage. Additionally, and in contrast to ground-based data, satellite data are overall uniform and very high quality. Probing the conductivity of the lithosphere and upper mantle requires EM variations with periods of a few hours. This is a challenging period range for global EM studies since the ionospheric (Sq) source dominates these periods and has a much more complex spatial structure compared to the magnetospheric ring current. Moreover, satellite-based EM induction studies in principle cannot use Sq data since the satellites fly above the Sq source causing the signals to be seen by the satellite as a purely internal source, thus precluding the separation of satellite Sq signals into internal and external parts. Lastly, magnetospheric and ionospheric sources interact inductively with Earth's conducting interior. Fortunately, there exists an alternative EM source in the Sq period range: electric currents generated by oceanic tides. Tides instead interact galvanically with the lithosphere (i.e. by direct coupling of the source currents in the ocean with the underlying substrate), enabling

  6. The generation and amplification of intergalactic magnetic fields in analogue laboratory experiments with high power lasers

    Science.gov (United States)

    Gregori, G.; Reville, B.; Miniati, F.

    2015-11-01

    The advent of high-power laser facilities has, in the past two decades, opened a new field of research where astrophysical environments can be scaled down to laboratory dimensions, while preserving the essential physics. This is due to the invariance of the equations of magneto-hydrodynamics to a class of similarity transformations. Here we review the relevant scaling relations and their application in laboratory astrophysics experiments with a focus on the generation and amplification of magnetic fields in cosmic environment. The standard model for the origin of magnetic fields is a multi stage process whereby a vanishing magnetic seed is first generated by a rotational electric field and is then amplified by turbulent dynamo action to the characteristic values observed in astronomical bodies. We thus discuss the relevant seed generation mechanisms in cosmic environment including resistive mechanism, collision-less and fluid instabilities, as well as novel laboratory experiments using high power laser systems aimed at investigating the amplification of magnetic energy by magneto-hydrodynamic (MHD) turbulence. Future directions, including efforts to model in the laboratory the process of diffusive shock acceleration are also discussed, with an emphasis on the potential of laboratory experiments to further our understanding of plasma physics on cosmic scales.

  7. Mathematical models for the diffusion magnetic resonance signal abnormality in patients with prion diseases

    Directory of Open Access Journals (Sweden)

    Matteo Figini

    2015-01-01

    Full Text Available In clinical practice signal hyperintensity in the cortex and/or in the striatum on magnetic resonance (MR diffusion-weighted images (DWIs is a marker of sporadic Creutzfeldt–Jakob Disease (sCJD. MR diagnostic accuracy is greater than 90%, but the biophysical mechanisms underpinning the signal abnormality are unknown. The aim of this prospective study is to combine an advanced DWI protocol with new mathematical models of the microstructural changes occurring in prion disease patients to investigate the cause of MR signal alterations. This underpins the later development of more sensitive and specific image-based biomarkers. DWI data with a wide a range of echo times and diffusion weightings were acquired in 15 patients with suspected diagnosis of prion disease and in 4 healthy age-matched subjects. Clinical diagnosis of sCJD was made in nine patients, genetic CJD in one, rapidly progressive encephalopathy in three, and Gerstmann–Sträussler–Scheinker syndrome in two. Data were analysed with two bi-compartment models that represent different hypotheses about the histopathological alterations responsible for the DWI signal hyperintensity. A ROI-based analysis was performed in 13 grey matter areas located in affected and apparently unaffected regions from patients and healthy subjects. We provide for the first time non-invasive estimate of the restricted compartment radius, designed to reflect vacuole size, which is a key discriminator of sCJD subtypes. The estimated vacuole size in DWI hyperintense cortex was in the range between 3 and 10 µm that is compatible with neuropathology measurements. In DWI hyperintense grey matter of sCJD patients the two bi-compartment models outperform the classic mono-exponential ADC model. Both new models show that T2 relaxation times significantly increase, fast and slow diffusivities reduce, and the fraction of the compartment with slow/restricted diffusion increases compared to unaffected grey matter of

  8. Compact toroids generated by a magnetized coaxial source in the CTX experiment

    International Nuclear Information System (INIS)

    Sherwood, A.R.; Henins, I.; Hoida, H.W.; Jarboe, T.R.; McKenna, K.F.; Linford, R.K.; Marshall, J.; Platts, D.A.

    1981-01-01

    Compact toroids containing both toroidal and poloidal magnetic field (Spheromak-type) have been generated in CTX using a magnetized coaxial plasma gun. These CTs tear loose from the gun by magnetic field line reconnection, and they are trapped in flux conservers having various geometries. In a straight cylindrical flux conserver the CTs are observed to be unstable to a gross tilting mode. Stability to the tilting mode has been demonstrated in flux conservers having an oblate trapping region; however, the geometry of the entrance region leading to the trapping volume can also have important effects. Lifetimes of about 150 μs for the CTs are typically observed. Interferometric measurements give a value of about 2 x 10 14 cm -3 for the initial plasma density. The plasma temperature measured at a single spot near the minor magnetic axis decreases to around 10 eV by the time the magnetic reconnection is complete. Spectrographic measurements and pressure probe results are in agreement with this temperature. A snipper coil has been installed to induce the CT to tear loose from the gun sooner. The use of this coil is observed to speed up the magnetic field reconnection process by about a factor of 2

  9. Compact toroids generated by a magnetized coaxial source in the CTX experiment

    Energy Technology Data Exchange (ETDEWEB)

    Sherwood, A.R.; Henins, I.; Hoida, H.W.; Jarboe, T.R.; McKenna, K.F.; Linford, R.K.; Marshall, J.; Platts, D.A.

    1981-01-01

    Compact toroids containing both toroidal and poloidal magnetic field (Spheromak-type) have been generated in CTX using a magnetized coaxial plasma gun. These CTs tear loose from the gun by magnetic field line reconnection, and they are trapped in flux conservers having various geometries. In a straight cylindrical flux conserver the CTs are observed to be unstable to a gross tilting mode. Stability to the tilting mode has been demonstrated in flux conservers having an oblate trapping region; however, the geometry of the entrance region leading to the trapping volume can also have important effects. Lifetimes of about 150 ..mu..s for the CTs are typically observed. Interferometric measurements give a value of about 2 x 10/sup 14/ cm/sup -3/ for the initial plasma density. The plasma temperature measured at a single spot near the minor magnetic axis decreases to around 10 eV by the time the magnetic reconnection is complete. Spectrographic measurements and pressure probe results are in agreement with this temperature. A snipper coil has been installed to induce the CT to tear loose from the gun sooner. The use of this coil is observed to speed up the magnetic field reconnection process by about a factor of 2.

  10. Electrochemical immunoassay for thyroxine detection using cascade catalysis as signal amplified enhancer and multi-functionalized magnetic graphene sphere as signal tag

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jing; Zhuo, Ying, E-mail: yingzhuo@swu.edu.cn; Chai, Yaqin; Yu, Yanqing; Liao, Ni; Yuan, Ruo, E-mail: yuanruo@swu.edu.cn

    2013-08-06

    Graphical abstract: -- Highlights: •A reusable electrochemical immunosensor is developed for thyroxine detection. •Cascade catalysis as signal amplified enhancer. •Multi-functionalized magnetic graphene sphere as signal tag. •The novel strategy has the advantages of high sensitivity, good selectivity and reproducibility. -- Abstract: This paper constructed a reusable electrochemical immunosensor for the detection of thyroxine at an ultralow concentration using cascade catalysis of cytochrome c (Cyt c) and glucose oxidase (GOx) as signal amplified enhancer. It is worth pointing out that numerous Cyt c and GOx were firstly carried onto the double-stranded DNA polymers based on hybridization chain reaction (HCR), and then the amplified responses could be achieved by cascade catalysis of Cyt c and GOx recycling with the help of glucose. Moreover, multi-functionalized magnetic graphene sphere was synthesized and used as signal tag, which not only exhibited good mechanical properties, large surface area and an excellent electron transfer rate of graphene, but also possessed excellent redox activity and desirable magnetic property. With a sandwich-type immunoreaction, the proposed cascade catalysis amplification strategy could greatly enhance the sensitivity for the detection of thyroxine. Under the optimal conditions, the immunosensor showed a wide linear ranged from 0.05 pg mL{sup −1} to 5 ng mL{sup −1} and a low detection limit down to 15 fg mL{sup −1}. Importantly, the proposed method offers promise for reproducible and cost-effective analysis of biological samples.

  11. Design and analysis of tubular permanent magnet linear generator for small-scale wave energy converter

    Science.gov (United States)

    Kim, Jeong-Man; Koo, Min-Mo; Jeong, Jae-Hoon; Hong, Keyyong; Cho, Il-Hyoung; Choi, Jang-Young

    2017-05-01

    This paper reports the design and analysis of a tubular permanent magnet linear generator (TPMLG) for a small-scale wave-energy converter. The analytical field computation is performed by applying a magnetic vector potential and a 2-D analytical model to determine design parameters. Based on analytical solutions, parametric analysis is performed to meet the design specifications of a wave-energy converter (WEC). Then, 2-D FEA is employed to validate the analytical method. Finally, the experimental result confirms the predictions of the analytical and finite element analysis (FEA) methods under regular and irregular wave conditions.

  12. Generation of static magnetic fields by a test charge in a plasma with anisotropic electron temperature

    Energy Technology Data Exchange (ETDEWEB)

    Aliev, Yu.M.; Bychenkov, V.Yu.; Frolov, A.A. (AN SSSR, Moscow. Fizicheskij Inst.)

    Structure of electomagnetic field generated with a charge in a plasma with anisotropic electron temperature has been studied. Unlike a hydrodynamical approach to study on the magnetic field qeneration with a test charge a kinetic theory describing spatial distribution of both magnetic and electrostatic components of charge field was constructed. Such theory results permit to investigate the charge field structure both at distances larger than length of free electron path and not exceeding it. The developed theory can serve as the basis for development of new methods for anisotropic plasma diagnostics.

  13. Dual-tone optical vector millimeter wave signal generated by frequency-nonupling the radio frequency 16-star quadrature-amplitude-modulation signal

    Science.gov (United States)

    Wu, Tonggen; Ma, Jianxin

    2017-12-01

    This paper proposes an original scheme to generate the photonic dual-tone optical millimeter wave (MMW) carrying the 16-star quadrature-amplitude-modulation (QAM) signal via an optical phase modulator (PM) and an interleaver with adaptive photonic frequency-nonupling without phase precoding. To enable the generated optical vector MMW signal to resist the power fading effect caused by the fiber chromatic dispersion, the modulated -5th- and +4th-order sidebands are selected from the output of the PM, which is driven by the precoding 16-star QAM signal. The modulation index of the PM is optimized to gain the maximum opto-electrical conversion efficiency. A radio over fiber link is built by simulation, and the simulated constellations and the bit error rate graph demonstrate that the frequency-nonupling 16-star QAM MMW signal has good transmission performance. The simulation results agree well with our theoretical results.

  14. Problems of the processing of nuclear magnetic logging signals (identification of fluid-containing strata from a number of measurements)

    International Nuclear Information System (INIS)

    Aliev, T.M.; Orlov, G.L.; Lof, V.M.; Mityushin, E.M.; Ragimova, E.K.

    1978-01-01

    Problems of the processing of nuclear magnetic logging signals to identification of fluid-containing strata from a number of measurements. Problems of application statistical decision theory to discovery of fluid-containing beds from a number of measurements are considered. Using the technique possibilities of nuclear magnetic logging method the necessary volume of samples is motivated, the rational algorithm for processing of sequential measurements is obtained

  15. Design and Optimization of Tube Type Interior Permanent Magnets Generator for Free Piston Applications

    Directory of Open Access Journals (Sweden)

    Serdal ARSLAN

    2017-05-01

    Full Text Available In this study a design and optimization of a generator to be used in free piston applications was made. In order to supply required initial force, an IPM (interior permanent magnets cavity tube type linear generator was selected. By using analytical equations’ basic dimensioning of generator was made. By using Ansys-Maxwell dimensioning, analysis and optimization of the generator was realized. Also, the effects of design basic variables (pole step ratio, cavity step ratio, inner diameter - outer diameter ratio, primary final length, air interval on pinking force were examined by using parametric analyses. Among these variables, cavity step ratio, inner diameter - outer diameter ratio, primary final length were optimally determined by algorithm and sequential nonlinear programming. The two methods were compared in terms of pinking force calculation problem. Preliminary application of the linear generator was performed for free piston application.

  16. Generation of mesoscale magnetic fields and the dynamics of Cosmic Ray acceleration

    Science.gov (United States)

    Diamond, P. H.; Malkov, M. A.

    The problem of the cosmic ray origin is discussed in connection with their acceleration in supernova remnant shocks. The diffusive shock acceleration mechanism is reviewed and its potential to accelerate particles to the maximum energy of (presumably) galactic cosmic rays (1018eV ) is considered. It is argued that to reach such energies, a strong magnetic field at scales larger than the particle gyroradius must be created as a result of the acceleration process, itself. One specific mechanism suggested here is based on the generation of Alfven wave at the gyroradius scale with a subsequent transfer to longer scales via interaction with strong acoustic turbulence in the shock precursor. The acoustic turbulence in turn, may be generated by Drury instability or by parametric instability of the Alfven waves. The generation mechanism is modulational instability of CR generated Alfven wave packets induced, in turn, by scattering off acoustic fluctuations in the shock precursor which are generated by Drury instability.

  17. Controlled and spontaneous magnetic field generation in a gun-driven spheromak

    International Nuclear Information System (INIS)

    Woodruff, S.; Cohen, B.I.; Hooper, E.B.; Mclean, H.S.; Stallard, B.W.; Hill, D.N.; Holcomb, C.T.; Romero-Talamas, C.; Wood, R.D.; Cone, G.; Sovinec, C.R.

    2005-01-01

    In the Sustained Spheromak Physics Experiment, SSPX [E. B. Hooper, D. Pearlstein, and D. D. Ryutov, Nucl. Fusion 39, 863 (1999)], progress has been made in understanding the mechanisms that generate fields by helicity injection. SSPX injects helicity (linked magnetic flux) from 1 m diameter magnetized coaxial electrodes into a flux-conserving confinement region. Control of magnetic fluctuations (δB/B∼1% on the midplane edge) yields T e profiles peaked at >200 eV. Trends indicate a limiting beta (β e ∼4%-6%), and so we have been motivated to increase T e by operating with stronger magnetic field. Two new operating modes are observed to increase the magnetic field: (A) Operation with constant current and spontaneous gun voltage fluctuations. In this case, the gun is operated continuously at the threshold for ejection of plasma from the gun: stored magnetic energy of the spheromak increases gradually with δB/B∼2% and large voltage fluctuations (δV∼1 kV), giving a 50% increase in current amplification, I tor /I gun . (B) Operation with controlled current pulses. In this case, spheromak magnetic energy increases in a stepwise fashion by pulsing the gun, giving the highest magnetic fields observed for SSPX (∼0.7 T along the geometric axis). By increasing the time between pulses, a quasisteady sustainment is produced (with periodic good confinement), comparing well with resistive magnetohydrodynamic simulations. In each case, the processes that transport the helicity into the spheromak are inductive and exhibit a scaling of field with current that exceeds those previously obtained. We use our newly found scaling to suggest how to achieve higher temperatures with a series of pulses

  18. Controlled and Spontaneous Magnetic Field Generation in a Gun-Driven Spheromak

    International Nuclear Information System (INIS)

    Woodruff, S; Cohen, B I; Hooper, E B; McLean, H S; Stallard, B W; Hill, D N; Holcomb, C T; Romero-Talamas, C; Wood, R D; Cone, G; Sovinec, C R

    2005-04-01

    In the Sustained Spheromak Physics Experiment, SSPX, progress has been made in understanding the mechanisms that generate fields by helicity injection. SSPX injects helicity (linked magnetic flux) from 1-m diameter magnetized coaxial electrodes into a flux-conserving confinement region. Control of magnetic fluctuations ((delta)B/B∼1% on the midplane edge) yields T e profiles peaked at > 200eV. Trends indicate a limiting beta (β e ∼ 4-6%), and so we have been motivated to increase T e by operating with stronger magnetic field. Two new operating modes are observed to increase the magnetic field: (A) Operation with constant current and spontaneous gun voltage fluctuations. In this case, the gun is operated continuously at the threshold for ejection of plasma from the gun: stored magnetic energy of the spheromak increases gradually with (delta)B/B ∼2% and large voltage fluctuations ((delta)V ∼ 1kV), giving a 50% increase in current amplification, I tor /I gun . (B) Operation with controlled current pulses. In this case, spheromak magnetic energy increases in a stepwise fashion by pulsing the gun, giving the highest magnetic fields observed for SSPX (∼0.7T along the geometric axis). By increasing the time between pulses, a quasi-steady sustainment is produced (with periodic good confinement), comparing well with resistive MHD simulations. In each case, the processes that transport the helicity into the spheromak are inductive and exhibit a scaling of field with current that exceeds those previously obtained. We use our newly found scaling to suggest how to achieve higher temperatures with a series of pulses

  19. Stacouf: A new system for automatic processing of eddy current signal from steam generator testing of PWR power plants

    International Nuclear Information System (INIS)

    Ducreux, J.; Eyrolles, P.; Meylogan, T.

    1990-01-01

    A new system called STACOUF will be soon industrialized. The aim is to improve on-site signal processing for eddy testing of steam generators. Testing time, quality and productivity will be improved [fr

  20. Towards 5G: A Photonic Based Millimeter Wave Signal Generation for Applying in 5G Access Fronthaul.

    Science.gov (United States)

    Alavi, S E; Soltanian, M R K; Amiri, I S; Khalily, M; Supa'at, A S M; Ahmad, H

    2016-01-27

    5G communications require a multi Gb/s data transmission in its small cells. For this purpose millimeter wave (mm-wave) RF signals are the best solutions to be utilized for high speed data transmission. Generation of these high frequency RF signals is challenging in electrical domain therefore photonic generation of these signals is more studied. In this work, a photonic based simple and robust method for generating millimeter waves applicable in 5G access fronthaul is presented. Besides generating of the mm-wave signal in the 60 GHz frequency band the radio over fiber (RoF) system for transmission of orthogonal frequency division multiplexing (OFDM) with 5 GHz bandwidth is presented. For the purpose of wireless transmission for 5G application the required antenna is designed and developed. The total system performance in one small cell was studied and the error vector magnitude (EVM) of the system was evaluated.

  1. Towards 5G: A Photonic Based Millimeter Wave Signal Generation for Applying in 5G Access Fronthaul

    Science.gov (United States)

    Alavi, S. E.; Soltanian, M. R. K.; Amiri, I. S.; Khalily, M.; Supa'At, A. S. M.; Ahmad, H.

    2016-01-01

    5G communications require a multi Gb/s data transmission in its small cells. For this purpose millimeter wave (mm-wave) RF signals are the best solutions to be utilized for high speed data transmission. Generation of these high frequency RF signals is challenging in electrical domain therefore photonic generation of these signals is more studied. In this work, a photonic based simple and robust method for generating millimeter waves applicable in 5G access fronthaul is presented. Besides generating of the mm-wave signal in the 60 GHz frequency band the radio over fiber (RoF) system for transmission of orthogonal frequency division multiplexing (OFDM) with 5 GHz bandwidth is presented. For the purpose of wireless transmission for 5G application the required antenna is designed and developed. The total system performance in one small cell was studied and the error vector magnitude (EVM) of the system was evaluated.

  2. Up to 40 Gb/s wireless signal generation and demodulation in 75-110 GHz band using photonic techniques

    DEFF Research Database (Denmark)

    Sambaraju, R.; Zibar, Darko; Caballero Jambrina, Antonio

    2010-01-01

    Record wireless signal capacity of up to 40 Gb/s is demonstrated in the 75-110 GHz band. All-optical OFDM and photonic up-conversion are used for generation and digital coherent detection for demodulation....

  3. Signal intensity of lanthanum carbonate on magnetic resonance images: phantom study.

    Science.gov (United States)

    Nakamura, Shinichi; Awai, Kazuo; Komi, Masanori; Morita, Kosuke; Namimoto, Tomohiro; Yanaga, Yumi; Utsunomiya, Daisuke; Date, Shuji; Yamashita, Yasuyuki

    2011-06-01

    Lanthanum carbonate (LC) is used to treat hyperphosphatemia. The purpose of this study was to investigate the signal intensity (SI) of LC on magnetic resonance imaging (MRI) scans of phantoms. LC tablets were thoroughly ground and mixed with distilled water or edible agar (0.05, 0.25, 0.5, and 2.5 mg/ml) in plastic bottles. Four intact tablets were placed in plastic bottles that did or did not contain distilled water or agar. Two radiologists consensually evaluated T1- and T2-weighted images (WIs) obtained with 1.5- and 3.0-T MRI systems for the SI of unground and ground tablets. On T1- and T2WI, the SIs of the LC suspensions and the solvents alone were similar; the SIs of unground tablets alone and of the air were also similar. Unground tablets in phantoms filled with solvent exhibited lower SI than the solvent. Ground tablets in suspension were not visualized on MRI or computed tomography. These results remained unchanged regardless of differences in magnetic field strength or the solvent used. Ground LC had no contrast enhancement effect on T1WI; on T2WI it did not affect the SI of the solvent. Unground LC tablets may be visualized as a "filling defect" on MRI.

  4. Signal intensity of lanthanum carbonate on magnetic resonance images. Phantom study

    International Nuclear Information System (INIS)

    Nakamura, Shinichi; Awai, Kazuo; Namimoto, Tomohiro; Yanaga, Yumi; Utsunomiya, Daisuke; Date, Shuji; Yamashita, Yasuyuki; Komi, Masanori; Morita, Kosuke

    2011-01-01

    Lanthanum carbonate (LC) is used to treat hyperphosphatemia. The purpose of this study was to investigate the signal intensity (SI) of LC on magnetic resonance imaging (MRI) scans of phantoms. LC tablets were thoroughly ground and mixed with distilled water or edible agar (0.05, 0.25, 0.5, and 2.5 mg/ml) in plastic bottles. Four intact tablets were placed in plastic bottles that did or did not contain distilled water or agar. Two radiologists consensually evaluated T1- and T2-weighted images (WIs) obtained with 1.5- and 3.0-T MRI systems for the SI of unground and ground tablets. On T1- and T2WI, the SIs of the LC suspensions and the solvents alone were similar; the SIs of unground tablets alone and of the air were also similar. Unground tablets in phantoms filled with solvent exhibited lower SI than the solvent. Ground tablets in suspension were not visualized on MRI or computed tomography. These results remained unchanged regardless of differences in magnetic field strength or the solvent used. Ground LC had no contrast enhancement effect on T1WI; on T2WI it did not affect the SI of the solvent. Unground LC tablets may be visualized as a 'filling defect' on MRI. (author)

  5. Solar and atmospheric neutrinos in three generations with a magnetic moment

    International Nuclear Information System (INIS)

    Pulido, J.; Tao, Z.

    1995-01-01

    A solution to the solar and atomospheric neutrino problems in three generations in the joint context of matter oscillations and the magnetic moment is investigated. An appropriate rotation of the evolution Hamiltonian reduces the three generation case to a two generation one. A convenient background for such a scenario with small neutrino masses and large magnetic moments is given by the Zee-type models, in which the mass generation mechanism leads to a pair of separate orders of magnitude for the mass square differences between neutrino species. We obtain a ratio var-epsilon congruent 10 -2 --10 -3 between these orders of magnitude, so that one of them [(0.3--3)x10 -2 eV 2 ] is suitable for the atmospheric neutrino solution and the other (∼10 -5 eV 2 ) for the solar neutrino solution. The magnetic moment leads to a decrease of the survival probability with solar neutrino energy. Such a decrease is consistent with the experimental situation

  6. Physiological modules for generating discrete and rhythmic movements: component analysis of EMG signals.

    Science.gov (United States)

    Bengoetxea, Ana; Leurs, Françoise; Hoellinger, Thomas; Cebolla, Ana Maria; Dan, Bernard; Cheron, Guy; McIntyre, Joseph

    2014-01-01

    A central question in Neuroscience is that of how the nervous system generates the spatiotemporal commands needed to realize complex gestures, such as handwriting. A key postulate is that the central nervous system (CNS) builds up complex movements from a set of simpler motor primitives or control modules. In this study we examined the control modules underlying the generation of muscle activations when performing different types of movement: discrete, point-to-point movements in eight different directions and continuous figure-eight movements in both the normal, upright orientation and rotated 90°. To test for the effects of biomechanical constraints, movements were performed in the frontal-parallel or sagittal planes, corresponding to two different nominal flexion/abduction postures of the shoulder. In all cases we measured limb kinematics and surface electromyographic activity (EMG) signals for seven different muscles acting around the shoulder. We first performed principal component analysis (PCA) of the EMG signals on a movement-by-movement basis. We found a surprisingly consistent pattern of muscle groupings across movement types and movement planes, although we could detect systematic differences between the PCs derived from movements performed in each shoulder posture and between the principal components associated with the different orientations of the figure. Unexpectedly we found no systematic differences between the figure eights and the point-to-point movements. The first three principal components could be associated with a general co-contraction of all seven muscles plus two patterns of reciprocal activation. From these results, we surmise that both "discrete-rhythmic movements" such as the figure eight, and discrete point-to-point movement may be constructed from three different fundamental modules, one regulating the impedance of the limb over the time span of the movement and two others operating to generate movement, one aligned with the

  7. Dynamic optical routing and simultaneous generation of millimeter-wave signals for in-building access network

    NARCIS (Netherlands)

    Zou, S.; Okonkwo, C.M.; Cao, Z.; Tran, N.C.; Tangdiongga, E.; Koonen, A.M.J.

    2012-01-01

    Two-stage optical routing using SOA and integrated micro-ring resonator, and remote generation of millimeter-wave signals by optical frequency multiplication is demonstrated for inbuilding network. Both 150Mb/s 64-QAM and 802.11a WLAN signal at 38GHz are transmitted.

  8. Accuracy of signal-to-noise ratio measurement method for magnetic resonance images

    International Nuclear Information System (INIS)

    Ogura, Akio; Miyai, Akira; Maeda, Fumie; Fukutake, Hiroyuki; Kikumoto, Rikiya

    2003-01-01

    The signal-to-noise ratio (SNR) of a magnetic resonance image is a common measure of imager performance. However, evaluations for the calculation of the SNR use various methods. A problem with measuring SNR is caused by the distortion of noise statistics in commonly used magnitude images. In this study, measurement accuracy was compared among four methods of evaluating SNR according to the size and position of regions of interest (ROIs). The results indicated that the method that used the difference between two images showed the best agreement with the theoretical value. In the method that used a single image, the SNR calculated by using a small size of ROI showed better agreement with the theoretical value because of noise bias and image artifacts. However, in the method that used the difference between two images, a large size of ROI was better in reducing statistical errors. In the same way, the methods that used air noise and air signal were better when applied to a large ROI. In addition, the image subtraction process used to calculate pixel-by-pixel differences in images may reach zero on a minus pixel value when using an image processor with the MRI system and apparatuses associated with it. A revised equation is presented for this case. It is important to understand the characteristics of each method and to choose a suitable method carefully according to the purpose of the study. (author)

  9. Modeling and analysis of solar wind generated contributions to the near-Earth magnetic field

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Moretto, T.; Rastatter, L.

    2006-01-01

    Solar wind generated magnetic disturbances are currently one of the major obstacles for improving the accuracy in the determination of the magnetic field due to sources internal to the Earth. In the present study a global MHD model of solar wind magnetosphere interaction is used to obtain...... a physically consistent, divergence-free model of ionospheric, field-aligned and magnetospheric currents in a realistic magnetospheric geometry. The magnetic field near the Earth due to these currents is analyzed by estimating and comparing the contributions from the various parts of the system, with the aim...... of identifying the most important aspects of the solar wind disturbances in an internal field modeling context. The contribution from the distant magnetospheric currents is found to consist of two, mainly opposing, contributions from respectively the dayside magnetopause currents and the cross-tail current...

  10. Self-generated magnetic fields and energy transport by ultra-intense laser-plasma interaction

    International Nuclear Information System (INIS)

    Abudurexiti, A.; Tuniyazi, P.; Wang Qian

    2011-01-01

    The electromagnetic instability (Weibel instability) and its mechanism in ultra-intense laser-plasma interactions are studied by using three-dimensional particle-in-cell simulations. The transport of energy in electron thermal conduction is analyzed by the Spitzer-Harm theory, and the election's vertical pyrogenation phenomenon that resulted from anisotropic heating of laser is observed. The results indicate that the strong magnetic field excited by Weibel instability makes the electron beam deposit its energy within a very short distance, and it restrains the electron thermal flux formed when the laser ponderomotive force bursts through the electron. With the increase of the self-generated magnetic field, the electron will be seized by the wave of magnetic field, and the transport of heat will be restricted. (authors)

  11. Astrophysics of magnetically collimated jets generated from laser-produced plasmas.

    Science.gov (United States)

    Ciardi, A; Vinci, T; Fuchs, J; Albertazzi, B; Riconda, C; Pépin, H; Portugall, O

    2013-01-11

    The generation of astrophysically relevant jets, from magnetically collimated, laser-produced plasmas, is investigated through three-dimensional, magnetohydrodynamic simulations. We show that for laser intensities I∼10(12)-10(14) W cm(-2), a magnetic field in excess of ∼0.1  MG, can collimate the plasma plume into a prolate cavity bounded by a shock envelope with a standing conical shock at its tip, which recollimates the flow into a supermagnetosonic jet beam. This mechanism is equivalent to astrophysical models of hydrodynamic inertial collimation, where an isotropic wind is focused into a jet by a confining circumstellar toruslike envelope. The results suggest an alternative mechanism for a large-scale magnetic field to produce jets from wide-angle winds.

  12. External Magnetic Field Reduction Techniques for the Advanced Stirling Radioisotope Generator

    Science.gov (United States)

    Niedra, Janis M.; Geng, Steven M.

    2013-01-01

    Linear alternators coupled to high efficiency Stirling engines are strong candidates for thermal-to-electric power conversion in space. However, the magnetic field emissions, both AC and DC, of these permanent magnet excited alternators can interfere with sensitive instrumentation onboard a spacecraft. Effective methods to mitigate the AC and DC electromagnetic interference (EMI) from solenoidal type linear alternators (like that used in the Advanced Stirling Convertor) have been developed for potential use in the Advanced Stirling Radioisotope Generator. The methods developed avoid the complexity and extra mass inherent in data extraction from multiple sensors or the use of shielding. This paper discusses these methods, and also provides experimental data obtained during breadboard testing of both AC and DC external magnetic field devices.

  13. Magnetization rotation or generation of incoherent spin waves? Suggestions for a spin-transfer effect experiment

    International Nuclear Information System (INIS)

    Bazaliy, Y. B.; Jones, B. A.

    2002-01-01

    ''Spin-transfer'' torque is created when electric current is passed through metallic ferromagnets and may have interesting applications in spintronics. So far it was experimentally studied in ''collinear'' geometries, where it is difficult to predict whether magnetization will coherently rotate or spin-waves will be generated. Here we propose an easy modification of existing experiment in which the spin-polarization of incoming current will no longer be collinear with magnetization and recalculate the switching behavior of the device. We expect that a better agreement with the magnetization rotation theory will be achieved. That can be an important step in reconciling alternative points of view on the effect of spin-transfer torque

  14. TMSEEG: A MATLAB-Based Graphical User Interface for Processing Electrophysiological Signals during Transcranial Magnetic Stimulation

    Directory of Open Access Journals (Sweden)

    Sravya Atluri

    2016-10-01

    Full Text Available Concurrent recording of electroencephalography (EEG during transcranial magnetic stimulation (TMS is an emerging and powerful tool for studying brain health and function. Despite a growing interest in adaptation of TMS-EEG across neuroscience disciplines, its wide-spread utility is limited by signal processing challenges. These challenges arise due to the nature of TMS and the sensitivity of EEG to artifacts that often mask TMS-evoked potentials (TEPs. With an increase in the complexity of data processing methods and a growing interest in multi-site data integration, analysis of TMS-EEG data requires the development of a standardized method to recover TEPs from various sources of artifacts. This paper introduces TMSEEG, an open-source MATLAB application comprised of multiple algorithms organized to facilitate a step-by-step procedure for TMS-EEG signal processing. Using a modular design and interactive GUIs, this toolbox aims to streamline TMS-EEG signal processing for both novice and experienced users. Specifically, TMSEEG provides (i targeted removal of TMS-induced and general EEG artifacts, (ii a step-by-step modular workflow with flexibility to modify existing algorithms and add customized algorithms, (iii a comprehensive display and quantification of artifacts, (iv quality control check points with visual feedback of TEPs throughout the data processing workflow, and (v capability to label and store a database of artifacts. In addition to these features, the software architecture of TMSEEG ensures minimal user effort in initial setup and configuration of parameters for each processing step. This is partly accomplished through a close integration with EEGLAB, a widely used open-source toolbox for EEG signal processing. In this paper we introduce TMSEEG, validate its features, and demonstrate its application in extracting TEPs across several single- and multi-pulse TMS protocols. As the first open-source GUI-based pipeline for TMS-EEG signal

  15. TMSEEG: A MATLAB-Based Graphical User Interface for Processing Electrophysiological Signals during Transcranial Magnetic Stimulation

    Science.gov (United States)

    Atluri, Sravya; Frehlich, Matthew; Mei, Ye; Garcia Dominguez, Luis; Rogasch, Nigel C.; Wong, Willy; Daskalakis, Zafiris J.; Farzan, Faranak

    2016-01-01

    Concurrent recording of electroencephalography (EEG) during transcranial magnetic stimulation (TMS) is an emerging and powerful tool for studying brain health and function. Despite a growing interest in adaptation of TMS-EEG across neuroscience disciplines, its widespread utility is limited by signal processing challenges. These challenges arise due to the nature of TMS and the sensitivity of EEG to artifacts that often mask TMS-evoked potentials (TEP)s. With an increase in the complexity of data processing methods and a growing interest in multi-site data integration, analysis of TMS-EEG data requires the development of a standardized method to recover TEPs from various sources of artifacts. This article introduces TMSEEG, an open-source MATLAB application comprised of multiple algorithms organized to facilitate a step-by-step procedure for TMS-EEG signal processing. Using a modular design and interactive graphical user interface (GUI), this toolbox aims to streamline TMS-EEG signal processing for both novice and experienced users. Specifically, TMSEEG provides: (i) targeted removal of TMS-induced and general EEG artifacts; (ii) a step-by-step modular workflow with flexibility to modify existing algorithms and add customized algorithms; (iii) a comprehensive display and quantification of artifacts; (iv) quality control check points with visual feedback of TEPs throughout the data processing workflow; and (v) capability to label and store a database of artifacts. In addition to these features, the software architecture of TMSEEG ensures minimal user effort in initial setup and configuration of parameters for each processing step. This is partly accomplished through a close integration with EEGLAB, a widely used open-source toolbox for EEG signal processing. In this article, we introduce TMSEEG, validate its features and demonstrate its application in extracting TEPs across several single- and multi-pulse TMS protocols. As the first open-source GUI-based pipeline

  16. TMSEEG: A MATLAB-Based Graphical User Interface for Processing Electrophysiological Signals during Transcranial Magnetic Stimulation.

    Science.gov (United States)

    Atluri, Sravya; Frehlich, Matthew; Mei, Ye; Garcia Dominguez, Luis; Rogasch, Nigel C; Wong, Willy; Daskalakis, Zafiris J; Farzan, Faranak

    2016-01-01

    Concurrent recording of electroencephalography (EEG) during transcranial magnetic stimulation (TMS) is an emerging and powerful tool for studying brain health and function. Despite a growing interest in adaptation of TMS-EEG across neuroscience disciplines, its widespread utility is limited by signal processing challenges. These challenges arise due to the nature of TMS and the sensitivity of EEG to artifacts that often mask TMS-evoked potentials (TEP)s. With an increase in the complexity of data processing methods and a growing interest in multi-site data integration, analysis of TMS-EEG data requires the development of a standardized method to recover TEPs from various sources of artifacts. This article introduces TMSEEG, an open-source MATLAB application comprised of multiple algorithms organized to facilitate a step-by-step procedure for TMS-EEG signal processing. Using a modular design and interactive graphical user interface (GUI), this toolbox aims to streamline TMS-EEG signal processing for both novice and experienced users. Specifically, TMSEEG provides: (i) targeted removal of TMS-induced and general EEG artifacts; (ii) a step-by-step modular workflow with flexibility to modify existing algorithms and add customized algorithms; (iii) a comprehensive display and quantification of artifacts; (iv) quality control check points with visual feedback of TEPs throughout the data processing workflow; and (v) capability to label and store a database of artifacts. In addition to these features, the software architecture of TMSEEG ensures minimal user effort in initial setup and configuration of parameters for each processing step. This is partly accomplished through a close integration with EEGLAB, a widely used open-source toolbox for EEG signal processing. In this article, we introduce TMSEEG, validate its features and demonstrate its application in extracting TEPs across several single- and multi-pulse TMS protocols. As the first open-source GUI-based pipeline

  17. Magnetic resonance angiography signal intensity as a marker of hemodynamic impairment in intracranial arterial stenosis.

    Directory of Open Access Journals (Sweden)

    Xinyi Leng

    Full Text Available Intracranial arterial stenosis (ICAS is the predominant cause of ischemic stroke and transient ischemic attack in Asia. Change of signal intensities (SI across an ICAS on magnetic resonance angiography (MRA may reflect its hemodynamic severity.In-patients with a symptomatic single ICAS detected on 3D time-of-flight MRA were recruited from 2 hospitals. Baseline and 1-year follow-up data were collected. Signal intensity ratio (SIR [ =  (mean post-stenotic SI -mean background SI/(mean pre-stenotic SI - mean background SI] was evaluated on baseline MRA to represent change of SIs across an ICAS. Acute infarct volume was measured on baseline diffusion-weighted images (DWI. Relationships between SIR and baseline characteristics as well as 1y outcomes were evaluated.Thirty-six subjects (86.1% males, mean age 55.0 were recruited. Overall, mean SIR was 0.84±0.23. Mean SIRs were not significantly different between the 23 (63.9% anatomically severe stenoses and the 13 (36.1% anatomically moderate stenoses (0.80±0.23 versus 0.92±0.21, p = 0.126. SIR was significantly, linearly and negatively correlated to acute infarct volume on DWI (Spearman correlation coefficient -0.471, p = 0.011. Two patients (5.6% had recurrent ischemic strokes at 1y, not related to SIR values.Change of signal intensities across an ICAS on MRA may reflect its hemodynamic and functional severity. Future studies are warranted to further verify the relationships between this index and prognosis of patients with symptomatic ICAS.

  18. Regulator of G-protein signaling 18 controls both platelet generation and function.

    Directory of Open Access Journals (Sweden)

    Nathalie Delesque-Touchard

    Full Text Available RGS18 is a myeloerythroid lineage-specific regulator of G-protein signaling, highly expressed in megakaryocytes (MKs and platelets. In the present study, we describe the first generation of a RGS18 knockout mouse model (RGS18-/-. Interesting phenotypic differences between RGS18-/- and wild-type (WT mice were identified, and show that RGS18 plays a significant role in both platelet generation and function. RGS18 deficiency produced a gain of function phenotype in platelets. In resting platelets, the level of CD62P expression was increased in RGS18-/- mice. This increase correlated with a higher level of plasmatic serotonin concentration. RGS18-/- platelets displayed a higher sensitivity to activation in vitro. RGS18 deficiency markedly increased thrombus formation in vivo. In addition, RGS18-/- mice presented a mild thrombocytopenia, accompanied with a marked deficit in MK number in the bone marrow. Analysis of MK maturation in vitro and in vivo revealed a defective megakaryopoiesis in RGS18-/- mice, with a lower bone marrow content of only the most committed MK precursors. Finally, RGS18 deficiency was correlated to a defect of platelet recovery in vivo under acute conditions of thrombocytopenia. Thus, we highlight a role for RGS18 in platelet generation and function, and provide additional insights into the physiology of RGS18.

  19. Fabrication of Micro-Needle Electrodes for Bio-Signal Recording by a Magnetization-Induced Self-Assembly Method

    Directory of Open Access Journals (Sweden)

    Keyun Chen

    2016-09-01

    Full Text Available Micro-needle electrodes (MEs have attracted more and more attention for monitoring physiological electrical signals, including electrode-skin interface impedance (EII, electromyography (EMG and electrocardiography (ECG recording. A magnetization-induced self-assembling method (MSM was developed to fabricate a microneedle array (MA. A MA coated with Ti/Au film was assembled as a ME. The fracture and insertion properties of ME were tested by experiments. The bio-signal recording performance of the ME was measured and compared with a typical commercial wet electrode (Ag/AgCl electrode. The results show that the MA self-assembled from the magnetic droplet array under the sum of gravitational surface tension and magnetic potential energies. The ME had good toughness and could easily pierce rabbit skin without being broken or buckling. When the compression force applied on the ME was larger than 2 N, ME could stably record EII, which was a lower value than that measured by Ag/AgCl electrodes. EMG signals collected by ME varied along with the contraction of biceps brachii muscle. ME could record static ECG signals with a larger amplitude and dynamic ECG signals with more distinguishable features in comparison with a Ag/AgCl electrode, therefore, ME is an alternative electrode for bio-signal monitoring in some specific situations.

  20. Structured light generation by magnetic metamaterial half-wave plates at visible wavelength

    Science.gov (United States)

    Zeng, Jinwei; Luk, Ting S.; Gao, Jie; Yang, Xiaodong

    2017-12-01

    Metamaterial or metasurface unit cells functioning as half-wave plates play an essential role for realizing ideal Pancharatnam-Berry phase optical elements capable of tailoring light phase and polarization as desired. Complex light beam manipulation through these metamaterials or metasurfaces unveils new dimensions of light-matter interactions for many advances in diffraction engineering, beam shaping, structuring light, and holography. However, the realization of metamaterial or metasurface half-wave plates in visible spectrum range is still challenging mainly due to its specific requirements of strong phase anisotropy with amplitude isotropy in subwavelength scale. Here, we propose magnetic metamaterial structures which can simultaneously exploit the electric field and magnetic field of light for achieving the nanoscale half-wave plates at visible wavelength. We design and demonstrate the magnetic metamaterial half-wave plates in linear grating patterns with high polarization conversion purity in a deep subwavelength thickness. Then, we characterize the equivalent magnetic metamaterial half-wave plates in cylindrical coordinate as concentric-ring grating patterns, which act like an azimuthal half-wave plate and accordingly exhibit spatially inhomogeneous polarization and phase manipulations including spin-to-orbital angular momentum conversion and vector beam generation. Our results show potentials for realizing on-chip beam converters, compact holograms, and many other metamaterial devices for structured light beam generation, polarization control, and wavefront manipulation.

  1. Effects of induced magnetic field on large scale pulsed MHD generator with two phase flow

    International Nuclear Information System (INIS)

    Ishikawa, M.; Koshiba, Y.; Matsushita, T.

    2004-01-01

    A large pulsed MHD generator 'SAKHALIN' was constructed in Russia (the former Soviet-Union) and operated with solid fuels. The 'SAKHALIN' with the channel length of 4.5 m could demonstrate the electric power output of 510 MW. The effects of induced magnetic field and two phase flow on the shock wave within the 'SAKHALIN' generator have been studied by time dependent, one dimensional analyses. It has been shown that the magnetic Reynolds number is about 0.58 for Run No. 1, and the induced magnetic flux density is about 20% at the entrance and exit of the MHD channel. The shock wave becomes stronger when the induced magnetic field is taken into account, when the operation voltage becomes low. The working gas plasma contains about 40% of liquid particles (Al 2 O 3 ) in weight, and the present analysis treats the liquid particles as another gas. In the case of mono-phase flow, the sharp shock wave is induced when the load voltage becomes small such as 500 V with larger Lorentz force, whereas in the case of two phase flow, the shock wave becomes less sharp because of the interaction with liquid particles

  2. MAGNETIC-RECONNECTION GENERATED SHOCK WAVES AS A DRIVER OF SOLAR SURGES

    International Nuclear Information System (INIS)

    Yang, Heesu; Chae, Jongchul; Park, Hyungmin; Song, Dong-uk; Cho, Kyuhyoun; Lim, Eun-Kyung; Lee, Kyoung-sun

    2014-01-01

    We found that a surge consists of multiple shock features. In our high-spatiotemporal spectroscopic observation of the surge, each shock is identified with the sudden appearance of an absorption feature at the blue wings of the Ca II 8542 Å line and Hα line that gradually shifts to the red wings. The shock features overlap with one another with the time interval of 110 s, which is much shorter than the duration of each shock feature, 300-400 s. This finding suggests that the multiple shocks might not have originated from a train of sinusoidal waves generated by oscillations and flows in the photosphere. As we found the signature of the magnetic flux cancelations at the base of the surge, we conclude that the multiple shock waves in charge of the surge were generated by the magnetic reconnection that occurred in the low atmosphere in association with the flux cancelation

  3. Study for a failsafe trigger generation system for the Large Hadron Collider beam dump kicker magnets

    CERN Document Server

    Rampl, M

    1999-01-01

    The 27 km-particle accelerator Large Hadron Collider (LHC), which will be completed at the European Laboratory for Particle Physics (CERN) in 2005, will work with extremely high beam energies (~334 MJ per beam). Since the equipment and in particular the superconducting magnets must be protected from damage caused by these high energy beams the beam dump must be able to absorb this energy very reliable at every stage of operation. The kicker magnets that extract the particles from the accelerator are synchronised with the beam by the trigger generation system. This thesis is a first study for this electronic module and its functions. A special synchronisation circuit and a very reliable electronic switch were developed. Most functions were implemented in a Gate-Array to improve the reliability and to facilitate modifications during the test stage. This study also comprises the complete concept for the prototype of the trigger generation system. During all project stages reliability was always the main determin...

  4. Nuclear magnetic resonance imaging

    International Nuclear Information System (INIS)

    Young, I.R.

    1984-01-01

    In a method of imaging a body in which nuclear magnetic resonance is excited in a region including part of the body, and the free induction decay signal is measured, a known quantity of a material of known nuclear magnetic resonance properties, for example a bag of water, is included in the region so as to enhance the measured free induction decay signal. This then reduces the generation of noise during subsequent processing of the signal. (author)

  5. Use of Three-Level Power Converters in Wind-Driven Permanent-Magnet Synchronous Generators with Unbalanced Loads

    Directory of Open Access Journals (Sweden)

    Ming-Hung Chen

    2015-06-01

    Full Text Available This paper describes the design and implementation of three-level power converters for wind-driven permanent-magnet synchronous generators with unbalanced loads. To increase voltage stress and reduce current harmonics in the electrical power generated by a wind generator, a three-phase, three-level rectifier is used. Because a synchronous rotating frame is used on the AC-input side, the use of a neutral-point-clamped controller is proposed to increase the power factor to unity and reduce current harmonics. Furthermore, a novel six-leg inverter is proposed for transferring energy from the DC voltage to a three-phase, four-wire AC source with a constant voltage and a constant frequency. The power converters also contain output transformers and filters for power buffering and filtering, respectively. All three output phase voltages are fed back to control the inverter output during load variations. A digital signal processor is used as the core control device for implementing a 1.5 kV, 75 kW drive system. Experimental data show that the power factor is successfully increased to unity and the total current harmonic distortion is 3.2% on the AC-input side. The entire system can attain an efficiency of 91%, and the voltage error between the upper and lower capacitors is approximately zero. Experimental results that confirm the high performance of the proposed system are presented.

  6. Significance of self magnetic field in long-distance collimation of laser-generated electron beams

    OpenAIRE

    Chen, Shi; Huang, Jiaofeng; Niu, Yifei; Dan, Jiakun; Chen, Ziyu; Li, Jianfeng

    2014-01-01

    Long-distance collimation of fast electron beams generated by laser-metallic-wire targets has been observed in recent experiments, while the mechanism behind this phenomenon remains unclear. In this work, we investigate in detail the laser-wire interaction processes with a simplified model and Classical Trajectory Monte Carlo simulations, and demonstrate the significance of the self magnetic fields of the beams in the long-distance collimation. Good agreements of simulated image plate pattern...

  7. A current controlled matrix converter for wind energy conversion systems based on permanent magnet synchronous generator

    OpenAIRE

    Naggar H. Saad; Ahmed A. El-Sattar; Mohamed I. Marei

    2016-01-01

    The main challenges of wind energy conversion systems (WECS) are to maximize the energy capture from the wind and injecting reactive power during the fault. This paper presents a current controlled matrix converter to interface Permanent Magnet Synchronous Generators (PMSG) based WECS with the grid. To achieve fast dynamic response with reduced current ripples, a hysteresis current control is utilized. The proposed control system decouples the active and reactive components of the PMSG curren...

  8. Reduction of thermal expansion in Z-pinches by electron beam assisted magnetic field generation

    International Nuclear Information System (INIS)

    Heikkinen, J.A.; Karttunen, S.J.

    1989-01-01

    Weak radial expansion of a Z-pinch plasma column during its strong initial ohmic heating phase is expected when the generation of a confining magnetic field is assisted by a correctly formed electron beam pulse. Appropriate one-dimensional magnetohydrodynamic equations are numerically solved, and the observed increase of plasma radius as a function of time for various discharge parameters is compared to a normal Z-pinch discharge initiation. (author)

  9. Design and construction of a uniform magnetic field generator for a 32 channel cosmic ray detector

    Science.gov (United States)

    Herrera-Guzman, K. N.; Gutierrez-Sanchez, R. A.; Felix, J.; Arceo, L. J.; Araujo, C.

    2017-10-01

    The trajectory of a particle can be measured if some points of its track are known. This is applied to any kind of particle, including cosmic rays. We have designed and built a device for this purpose. We present the design, construction and characterization of a uniform magnetic field generator system in a finite volume. An array of Cerenkov detectors will be placed inside of it for determining the cosmic rays charge and to reconstruct their trajectories.

  10. Calculations of self-generated magnetic fields in parylene disc experiments

    International Nuclear Information System (INIS)

    Dahlbacka, G.H.; Mead, W.C.; Max, C.E.; Thomson, J.J.

    1975-01-01

    Experiments have been planned at Livermore to measure self-generated magnetic fields using the Faraday Rotation of frequency quadrupled 1.1 μm laser light. The LASNEX code was used during the planning of these experiments and has provided valuable information in establishing the conditions under which the thermoelectric fields expected can be measured. Suspected thermoelectric fields have been inferred from experiments that have been carried out at NRL

  11. Predictive control of a chaotic permanent magnet synchronous generator in a wind turbine system

    International Nuclear Information System (INIS)

    Messadi, Manal; Mellit, Adel; Kemih, Karim; Ghanes, Malek

    2015-01-01

    This paper investigates how to address the chaos problem in a permanent magnet synchronous generator (PMSG) in a wind turbine system. Predictive control approach is proposed to suppress chaotic behavior and make operating stable; the advantage of this method is that it can only be applied to one state of the wind turbine system. The use of the genetic algorithms to estimate the optimal parameter values of the wind turbine leads to maximization of the power generation. Moreover, some simulation results are included to visualize the effectiveness and robustness of the proposed method. (paper)

  12. Modeling and control of a variable-speed wind turbine equipped with permanent magnet synchronous generator

    Energy Technology Data Exchange (ETDEWEB)

    Aliprantis, D.C.; Papathanassiou, S.A.; Papadopoulos, M.P.; Kladas, A.G. [Purdue University, Electrical and Computer Engineering, West Lafayette, IN (United States)

    2000-08-01

    In this paper the operation of a variable-speed, stall regulated wind turbine equipped with a permanent magnet synchronous generator (PMSG) is examined. The emphasis is placed on the analysis of the electric part of the system, i.e. the electrical generator, the power electronics converters and the control. The operational characteristics of the machine are investigated through a series of computer simulations and the speed control system is designed to maximize the power output and achieve a smooth torque and power profile. (orig.)

  13. Predictive control of a chaotic permanent magnet synchronous generator in a wind turbine system

    Science.gov (United States)

    Manal, Messadi; Adel, Mellit; Karim, Kemih; Malek, Ghanes

    2015-01-01

    This paper investigates how to address the chaos problem in a permanent magnet synchronous generator (PMSG) in a wind turbine system. Predictive control approach is proposed to suppress chaotic behavior and make operating stable; the advantage of this method is that it can only be applied to one state of the wind turbine system. The use of the genetic algorithms to estimate the optimal parameter values of the wind turbine leads to maximization of the power generation. Moreover, some simulation results are included to visualize the effectiveness and robustness of the proposed method. Project supported by the CMEP-TASSILI Project (Grant No. 14MDU920).

  14. Local entropy generation analysis of a rotary magnetic heat pump regenerator

    International Nuclear Information System (INIS)

    Drost, M.K.; White, M.D.

    1990-01-01

    The rotary magnetic heat pump has attractive thermodynamic performance but it is strongly influenced by the effectiveness of the regenerator. This paper uses local entropy generation analysis to evaluate the regenerator design and to suggest design improvements. The results show that performance of the proposed design is dominated by heat transfer related entropy generation. This suggests that enhancement concepts that improve heat transfer should be considered, even if the enhancement causes a significant increase in viscous losses (pressure drop). One enhancement technique, the use of flow disruptors, was evaluated and the results showed that flow disruptors can significantly reduce thermodynamic losses

  15. Efficient generation of monoclonal antibodies against peptide in the context of MHCII using magnetic enrichment.

    Science.gov (United States)

    Spanier, Justin A; Frederick, Daniel R; Taylor, Justin J; Heffernan, James R; Kotov, Dmitri I; Martinov, Tijana; Osum, Kevin C; Ruggiero, Jenna L; Rust, Blake J; Landry, Samuel J; Jenkins, Marc K; McLachlan, James B; Fife, Brian T

    2016-06-13

    Monoclonal antibodies specific for foreign antigens, auto-antigens, allogeneic antigens and tumour neo-antigens in the context of major histocompatibility complex II (MHCII) are highly desirable as novel immunotherapeutics. However, there is no standard protocol for the efficient generation of monoclonal antibodies that recognize peptide in the context of MHCII, and only a limited number of such reagents exist. In this report, we describe an approach for the generation and screening of monoclonal antibodies specific for peptide bound to MHCII. This approach exploits the use of recombinant peptide:MHC monomers as immunogens, and subsequently relies on multimers to pre-screen and magnetically enrich the responding antigen-specific B cells before fusion and validation, thus saving significant time and reagents. Using this method, we have generated two antibodies enabling us to interrogate antigen presentation and T-cell activation. This methodology sets the standard to generate monoclonal antibodies against the peptide-MHCII complexes.

  16. Modeling of the Direct Current Generator Including the Magnetic Saturation and Temperature Effects

    Directory of Open Access Journals (Sweden)

    Alfonso J. Mercado-Samur

    2013-11-01

    Full Text Available In this paper the inclusion of temperature effect on the field resistance on the direct current generator model DC1A, which is valid to stability studies is proposed. First, the linear generator model is presented, after the effect of magnetic saturation and the change in the resistance value due to temperature produced by the field current are included. The comparison of experimental results and model simulations to validate the model is used. A direct current generator model which is a better representation of the generator is obtained. Visual comparison between simulations and experimental results shows the success of the proposed model, because it presents the lowest error of the compared models. The accuracy of the proposed model is observed via Modified Normalized Sum of Squared Errors index equal to 3.8979%.

  17. Modeling and Analysis of Double Stator Slotted Rotor Permanent Magnet Generator

    Directory of Open Access Journals (Sweden)

    Suhairi Rizuan Che Ahmad

    2017-03-01

    Full Text Available This paper discusses the modeling and analysis of three phase double stator slotted rotor permanent magnet generator (DSSR-PMG. The use of double stator topology through the double magnetic circuit helps to maximize the usage of flux linkage in the yoke structure of the single stator topology. The analytical computation is done using Permeance Analysis Method (PAM. Finite Element Analysis (FEA is used for numerical verifications and to verify the design structure a prototype laboratory is performed. The analysis is done with various loading conditions to derive the electromagnetic torque, output power and efficiency for the proposed structure. The analytical, numerical and experimental results from the analysis are found to be in good agreement. The maximum power developed by this generator at rated speed of 2000 rpm is of 1 kW with the operational efficiency of 75%. A rectifier bridge circuit is used to make the generated voltage a storage capable constant voltage to make it suitable for mobile applications (such as Direct Current DC generator. The proposed generator structure is highly recommended for applications such as micro-hydro and small renewable plants.

  18. Size Reduction Techniques for Large Scale Permanent Magnet Generators in Wind Turbines

    Science.gov (United States)

    Khazdozian, Helena; Hadimani, Ravi; Jiles, David

    2015-03-01

    Increased wind penetration is necessary to reduce U.S. dependence on fossil fuels, combat climate change and increase national energy security. The U.S Department of Energy has recommended large scale and offshore wind turbines to achieve 20% wind electricity generation by 2030. Currently, geared doubly-fed induction generators (DFIGs) are typically employed in the drivetrain for conversion of mechanical to electrical energy. Yet, gearboxes account for the greatest downtime of wind turbines, decreasing reliability and contributing to loss of profit. Direct drive permanent magnet generators (PMGs) offer a reliable alternative to DFIGs by eliminating the gearbox. However, PMGs scale up in size and weight much more rapidly than DFIGs as rated power is increased, presenting significant challenges for large scale wind turbine application. Thus, size reduction techniques are needed for viability of PMGs in large scale wind turbines. Two size reduction techniques are presented. It is demonstrated that 25% size reduction of a 10MW PMG is possible with a high remanence theoretical permanent magnet. Additionally, the use of a Halbach cylinder in an outer rotor PMG is investigated to focus magnetic flux over the rotor surface in order to increase torque. This work was supported by the National Science Foundation under Grant No. 1069283 and a Barbara and James Palmer Endowment at Iowa State University.

  19. Field generated within the SSC magnets due to persistant currents in the superconductor

    International Nuclear Information System (INIS)

    Green, M.A.

    1984-01-01

    This report presents the results of a number of computer studies of the magnetic fields generated by persistent circulating currents in the superconductor of superconducting dipoles. These magnetic fields are referred to as residual fields throughout this report. Since the field generated by persistent currents have a hysteric behavior, they are analagous to the residual filed found in iron bound conventional solenoids. The residual field calculations presented in this report were done using the LBL SCMAG4 computer code. This code has not been well tested against measured data, but a comparison with measured CBA data given in this report suggests that good agreement is possible. The residual fields generated by persistent superconducting currents are rich in higher multipoles. This is of concern to the accelerator designer for SSC. This report shows the effect of various superconductor parameters and coil parameters on the magnitude and structure of the residual fields. The effect of the magnet charging history on residual fields is aldo discussed. 14 references

  20. Design study of superconducting magnets for a combustion magnetohydrodynamic (MHD) generator

    Science.gov (United States)

    Thome, R. J.; Ayers, J. W.

    1977-01-01

    Design trade off studies for 13 different superconducting magnet systems were carried out. Based on these results, preliminary design characteristics were prepared for several superconducting magnet systems suitable for use with a combustion driven MHD generator. Each magnet generates a field level of 8 T in a volume 1.524 m (60 in.) long with a cross section 0.254 m x 0.254 m (10 in. x 10 in.) at the inlet and 0.406 m x .406 m (16 in. x 16 in.) at the outlet. The first design involves a racetrack coil geometry intended for operation at 4.2 K; the second design uses a racetrack geometry at 2.0 K; and the third design utilizes a rectangular saddle geometry at 4.2 K. Each case was oriented differently in terms of MHD channel axis and main field direction relative to gravity in order to evaluate fabrication ease. All cases were designed such that the system could be disassembled to allow for alteration of field gradient in the MHD channel by changing the angle between coils. Preliminary design characteristics and assembly drawings were generated for each case.

  1. Polyinosinic:polycytidylic acid loading onto different generations of PAMAM dendrimer-coated magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Khodadust, Rouhollah, E-mail: raoul.1357@gmail.com [Middle East Technical University, Department of Biotechnology (Turkey); Mutlu, Pelin [Middle East Technical University, Central Laboratory, Molecular Biology and Biotechnology R and D Center (Turkey); Yalc Latin-Small-Letter-Dotless-I n, Serap [Ahi Evran University, Department of Food Engineering (Turkey); Unsoy, Gozde; Gunduz, Ufuk, E-mail: ufukg@metu.edu.tr [Middle East Technical University, Department of Biotechnology (Turkey)

    2013-08-15

    Poly (I:C), which is a synthetic double-stranded RNA, have significant toxicity on tumor cells. The immobilization of Poly (I:C) onto nanoparticles is important for the fabrication of targeted delivery systems. In this study, different generations of newly synthesized PAMAM dendron-coated magnetic nanoparticles (DcMNP) which can be targeted to the tumor site under magnetic field were efficiently loaded for the first time with Poly (I:C). Different generations of DcMNPs (G{sub 2}, G{sub 3}, G{sub 4}, G{sub 5}, G{sub 6}, and G{sub 7}) were synthesized. Poly (I:C) activation was achieved in the presence of EDC and 1-methylimidazole. Loading of Poly (I:C) onto DcMNPs was followed by agarose gel electrophoresis. Acidic reaction conditions were found as superior to basic and neutral for binding of Poly (I:C). In addition, having more functional groups at the surface, higher generations (G{sub 7}, G{sub 6}, and G{sub 5}) of PAMAM DcMNPs were found more suitable as a delivery system for Poly (I:C). Further in vitro and in vivo analyses of Poly (I:C)/PAMAM magnetic nanoparticles may provide new opportunities for the selective targeting and killing of tumor cells.

  2. Analysis on the Acoustic Emission Signals in the Crack Evolution of Steam Generator Tube

    International Nuclear Information System (INIS)

    Han, Jung Ho; Hur, Do Haeng; Kim, Kyung Mo; Choi, Myung Sik; Lee, Deok Hyun

    2007-01-01

    The evolution of a defect in steam generator (SG) tube during plant operation can be classified into the stages of initiation and propagation. However, the detection and discrimination of these two stages are difficult, and the real time monitoring of the defect evolution in plant operation is impossible. Moreover, it was generally known that the commercial nondestructive examination techniques such as eddy current test(ECT) can detect the defect already grown up to the size of more than 40% in tube wall thickness. Therefore, the scope of the present study is to develop the fundamental technology for monitoring the degradation process from the initiation stage to the subsequent propagation stage by acoustic emission (AE) signal measurement

  3. Experimentally Generated Random Numbers Certified by the Impossibility of Superluminal Signaling

    Science.gov (United States)

    Bierhorst, Peter; Shalm, Lynden K.; Mink, Alan; Jordan, Stephen; Liu, Yi-Kai; Rommal, Andrea; Glancy, Scott; Christensen, Bradley; Nam, Sae Woo; Knill, Emanuel

    Random numbers are an important resource for applications such as numerical simulation and secure communication. However, it is difficult to certify whether a physical random number generator is truly unpredictable. Here, we exploit the phenomenon of quantum nonlocality in a loophole-free photonic Bell test experiment to obtain data containing randomness that cannot be predicted by any theory that does not also allow the sending of signals faster than the speed of light. To certify and quantify the randomness, we develop a new protocol that performs well in an experimental regime characterized by low violation of Bell inequalities. Applying an extractor function to our data, we obtain 256 new random bits, uniform to within 10- 3 .

  4. EIRP Characterization of Electrically Large Wireless Equipment with Integrated Signal Generator in a Compact Environment

    Directory of Open Access Journals (Sweden)

    Soon-Soo Oh

    2015-01-01

    Full Text Available We describe a measurement technique to characterize the equivalent isotropically radiated power (EIRP of electrically large wireless equipment in a compact environment. A modified phase-measurement method was proposed and, thus, the separation of the signal generator and radiating element was not required during the measurement. A Fresnel-to-far-field transformation was used for the fast measurement time in a compact anechoic chamber. An experimental verification of the method was carried out in a compact anechoic chamber, where the source-detector separation was approximately 1/5 of the far-field distance. The measured magnitude and phase pattern exhibited only a small error. The EIRP obtained using a Fresnel-to-far-field transformation was compared with a reference value, and the error was within 0.5 dB.

  5. Acoustic Leak Detection Testing Using KAERI Sodium-Water Reaction Signals for a SFR Steam Generator

    International Nuclear Information System (INIS)

    Kim, Tae-Joon; Jeong, Ji-Young; Kim, Jong-Man; Kim, Byung-Ho; Hahn, Do-Hee; Yugay, Valeriy S.

    2009-01-01

    The results of an experimental study of water in a sodium leak noise spectrum formation at 0.004-0.54 g/sec, various rates of water into a sodium leak, smaller than 1.0 g/sec, are presented. We focused on studying a micro leak detection with an increasing rate of water into sodium. On the basis of the experimental leak noise data manufactured in KAERI the simple dependency of an acoustic signal level from the rate of a micro and small leak at different frequency bands is presented to understand the principal analysis for the development of an acoustic leak detection methodology used in a K- 600 steam generator

  6. Validated Models for Radiation Response and Signal Generation in Scintillators: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Kerisit, Sebastien N.; Gao, Fei; Xie, YuLong; Campbell, Luke W.; Van Ginhoven, Renee M.; Wang, Zhiguo; Prange, Micah P.; Wu, Dangxin

    2014-12-01

    This Final Report presents work carried out at Pacific Northwest National Laboratory (PNNL) under the project entitled “Validated Models for Radiation Response and Signal Generation in Scintillators” (Project number: PL10-Scin-theor-PD2Jf) and led by Drs. Fei Gao and Sebastien N. Kerisit. This project was divided into four tasks: 1) Electronic response functions (ab initio data model) 2) Electron-hole yield, variance, and spatial distribution 3) Ab initio calculations of information carrier properties 4) Transport of electron-hole pairs and scintillation efficiency Detailed information on the results obtained in each of the four tasks is provided in this Final Report. Furthermore, published peer-reviewed articles based on the work carried under this project are included in Appendix. This work was supported by the National Nuclear Security Administration, Office of Nuclear Nonproliferation Research and Development (DNN R&D/NA-22), of the U.S. Department of Energy (DOE).

  7. Review of Microwave Photonics Technique to Generate the Microwave Signal by Using Photonics Technology

    Science.gov (United States)

    Raghuwanshi, Sanjeev Kumar; Srivastav, Akash

    2017-12-01

    Microwave photonics system provides high bandwidth capabilities of fiber optic systems and also contains the ability to provide interconnect transmission properties, which are virtually independent of length. The low-loss wide bandwidth capability of optoelectronic systems makes them attractive for the transmission and processing of microwave signals, while the development of high-capacity optical communication systems has required the use of microwave techniques in optical transmitters and receivers. These two strands have led to the development of the research area of microwave photonics. So, we can considered microwave photonics as the field that studies the interaction between microwave and optical waves for applications such as communications, radars, sensors and instrumentations. In this paper we have thoroughly reviewed the microwave generation techniques by using photonics technology.

  8. Coherent Optical Generation of a 6 GHz Microwave Signal with Directly Phase Locked Semiconductor DFB Lasers

    DEFF Research Database (Denmark)

    Gliese, Ulrik Bo; Nielsen, Torben Nørskov; Bruun, Marlene

    1992-01-01

    Experimental results of a wideband heterodyne second order optical phase locked loop with 1.5 ¿m semiconductor lasers are presented. The loop has a bandwidth of 180 MHz, a gain of 181 dBHz and a propagation delay of only 400 ps. A beat signal of 8 MHz linewidth is phase locked to become a replica...... of a microwave reference source close to carrier with a noise level of ¿125 dBc/Hz. The total phase variance of the locked carrier is 0.04 rad2 and carriers can be generated in a continuous range from 3 to 18 GHz. The loop reliability is excellent with an average time to cycle slip of 1011 seconds...

  9. Passive electromagnetic NDE for mechanical damage inspection by detecting leakage magnetic flux. (I. Reconstruction of magnetic charges from detected field signals)

    International Nuclear Information System (INIS)

    Chen, Zhenmao; Aoto, Kazumi; Kato, Syoichi

    1999-07-01

    In this report, reconstruction of magnetic charges induced by mechanical damages in a test piece of SUS304 stainless steel is performed as a part of efforts to establish a passive nondestructive testing method on the basis of the inspection of leakage magnetic field. The approach for solving this typical ill-posed inverse problem is selected as a way in the least square method category. Concerning the ill-poseness of the system of equations, an iteration algorithm is adopted to its solving in which the designations of initial profile, the weight coefficients and the total number of iterations are taken as means of regularization. From examples using simulated input data, it is verified that the approach gives good reconstruction results in case of signals with a relative high S/N ratio. For improving the robustness of the proposed method, a Galerkin procedure with base functions chosen as the Daubechies' wavelet is also introduced for discretizing the governing equation. By comparing the reconstruction results of the least square method and those using wavelet discretization, it is found that the wavelet used approach is more feasible in the inversion of noise polluted signals. Reconstruction of 1-D and 2-D magnetic charges with the least square strategy and reconstruction of an 1-D problem with the wavelet used method are carried out from both simulated and measured magnetic field signals which are used as the validation of the proposed inversion strategy. (author)

  10. Campbelling-type theory of fission chamber signals generated by neutron chains in a multiplying medium

    International Nuclear Information System (INIS)

    Pál, L.; Pázsit, I.

    2015-01-01

    The signals of fission chambers are usually evaluated with the help of the co-called Campbelling techniques. These are based on the Campbell theorem, which states that if the primary incoming events, generating the detector pulses, are independent, then relationships exist between the moments of various orders of the signal in the current mode. This gives the possibility to determine the mean value of the intensity of the detection events, which is proportional to the static flux, from the higher moments of the detector current, which has certain advantages. However, the main application area of fission chambers is measurements in power reactors where, as is well known, the individual detection events are not independent, due to the branching character of the neutron chains (neutron multiplication). Therefore it is of interest to extend the Campbelling-type theory for the case of correlated neutron events. Such a theory could address two questions: partly, to investigate the bias when the traditional Campbell techniques are used for correlated incoming events; and partly, to see whether the correlation properties of the detection events, which carry information on the multiplying medium, could be extracted from the measurements. This paper is devoted to the investigation of these questions. The results show that there is a potential possibility to extract the same information from fission chamber signals in the current mode as with the Rossi- or Feynman-alpha methods, or from coincidence and multiplicity measurements, which so far have required detectors working in the pulse mode. It is also shown that application of the standard Campbelling techniques to neutron detection in multiplying systems does not lead to an error for estimating the stationary flux as long as the detector is calibrated in in situ measurements

  11. BMP4 signaling is involved in the generation of inner ear sensory epithelia

    Directory of Open Access Journals (Sweden)

    Wang Yucheng

    2005-08-01

    Full Text Available Abstract Background The robust expression of BMP4 in the incipient sensory organs of the inner ear suggests possible roles for this signaling protein during induction and development of auditory and vestibular sensory epithelia. Homozygous BMP4-/- animals die before the inner ear's sensory organs develop, which precludes determining the role of BMP4 in these organs with simple gene knockout experiments. Results Here we use a chicken otocyst culture system to perform quantitative studies on the development of inner ear cell types and show that hair cell and supporting cell generation is remarkably reduced when BMP signaling is blocked, either with its antagonist noggin or by using soluble BMP receptors. Conversely, we observed an increase in the number of hair cells when cultured otocysts were treated with exogenous BMP4. BMP4 treatment additionally prompted down-regulation of Pax-2 protein in proliferating sensory epithelial progenitors, leading to reduced progenitor cell proliferation. Conclusion Our results implicate BMP4 in two events during chicken inner ear sensory epithelium formation: first, in inducing the switch from proliferative sensory epithelium progenitors to differentiating epithelial cells and secondly, in promoting the differentiation of hair cells within the developing sensory epithelia.

  12. Particle Acceleration and Magnetic Field Generation in Electron-Positron Relativistic Shocks

    Science.gov (United States)

    Nishikawa, K.-I.; Hardee, P.; Richardson, G.; Preece, R.; Sol, H.; Fishman, G. J.

    2005-01-01

    Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., Buneman, Weibel, and other two-stream instabilities) created in collisionless shocks are responsible for particle (electron, positron, and ion) acceleration. Using a three-dimensional relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic electron-positron jet front propagating into an ambient electron-positron plasma with and without initial magnetic fields. We find small differences in the results for no ambient and modest ambient magnetic fields. New simulations show that the Weibel instability created in the collisionless shock front accelerates jet and ambient particles both perpendicular and parallel to the jet propagation direction. Furthermore, the nonlinear fluctuation amplitudes of densities, currents, and electric and magnetic fields in the electron-positron shock are larger than those found in the electron-ion shock studied in a previous paper at a comparable simulation time. This comes from the fact that both electrons and positrons contribute to generation of the Weibel instability. In addition, we have performed simulations with different electron skin depths. We find that growth times scale inversely with the plasma frequency, and the sizes of structures created by tine Weibel instability scale proportionally to the electron skin depth. This is the expected result and indicates that the simulations have sufficient grid resolution. While some Fermi acceleration may occur at the jet front, the majority of electron and positron acceleration takes place behind the jet front and cannot be characterized as Fermi acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying nonuniform, small-scale magnetic fields, which contribute to the electron s (positron s) transverse deflection behind the jet head. This

  13. Generation of synthetic surface electromyography signals under fatigue conditions for varying force inputs using feedback control algorithm.

    Science.gov (United States)

    Venugopal, G; Deepak, P; Ghosh, Diptasree M; Ramakrishnan, S

    2017-11-01

    Surface electromyography is a non-invasive technique used for recording the electrical activity of neuromuscular systems. These signals are random, complex and multi-component. There are several techniques to extract information about the force exerted by muscles during any activity. This work attempts to generate surface electromyography signals for various magnitudes of force under isometric non-fatigue and fatigue conditions using a feedback model. The model is based on existing current distribution, volume conductor relations, the feedback control algorithm for rate coding and generation of firing pattern. The result shows that synthetic surface electromyography signals are highly complex in both non-fatigue and fatigue conditions. Furthermore, surface electromyography signals have higher amplitude and lower frequency under fatigue condition. This model can be used to study the influence of various signal parameters under fatigue and non-fatigue conditions.

  14. Self-Tuning Linear Quadratic Supervisory Regulation of a Diesel Generator using Large-Signal State Estimation

    DEFF Research Database (Denmark)

    Knudsen, Jesper Viese; Bendtsen, Jan Dimon; Andersen, Palle

    2016-01-01

    In this paper, a self-tuning linear quadratic supervisory regulator using a large-signal state estimator for a diesel driven generator set is proposed. The regulator improves operational efficiency, in comparison to current implementations, by (i) automating the initial tuning process and (ii...... throughout the operating range of the diesel generator....

  15. Optical Second Harmonic Generation in the BaTiO3 phase of magnetically aligned multiferroic nanofibers

    Science.gov (United States)

    Gasperi, Katia

    Multiferroic materials enable the exploration of electrical control of magnetic properties and vice versa. Their increasing interest is especially due to their potential applications in the industry of information storage. Thanks to recent progress in nanotechnology, they have also been found to have many other applications such as transducers and sensors, and they already occupy a unique place in the biomedical field. The objective of this project is to study multiferroic nanofibers made of cobalt ferrite CoFe2O 4 (CFO) and barium titanate BaTiO3 (BTO) with a specific focus in the characterization of the ferroelectric phase. We researched the state of knowledge concerning the size effects on phase transition for nanoparticles and polycrystals BTO. The ferroelectric phase transition of BTO occurs when it changes from a tetragonal (anisotropic) crystal structure to a cubic (isotropic) structure. This change suggests that optical second harmonic generation (SHG) is a good measurement technique for monitoring the phase transition of the BTO half of the nanofibers. We designed and prepared a temperature dependent SHG experiment on magnetically aligned fibers in transmission with the possibility to investigate the polarization dependence of the signal. We also prepared interdigital electrodes on glass for the future study of the fibers in an external electric field.

  16. Transient global amnesia: increased signal intensity in the right hippocampus on diffusion-weighted magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, M.; Sakamoto, S.; Ishii, K. [Division of Neuroimaging Research, Hyogo Institute for Aging Brain and Cognitive Disorders (Japan); Imamura, T.; Kazui, H.; Mori, E. [Division of Clinical Neurosciences, Hyogo Institute for Aging Brain and Cognitive Disorders, Hyogo (Japan)

    2002-03-01

    We report on a patient with pure transient global amnesia (TGA) whose magnetic resonance imaging (MRI) demonstrated a small region of increased signal intensity in the right hippocampus on diffusion-weighted imaging (DWI). DWI was sensitive and useful for evaluating the early stage of TGA and might help to explain the pathophysiology of TGA. (orig.)

  17. Transient global amnesia: increased signal intensity in the right hippocampus on diffusion-weighted magnetic resonance imaging

    International Nuclear Information System (INIS)

    Matsui, M.; Sakamoto, S.; Ishii, K.; Imamura, T.; Kazui, H.; Mori, E.

    2002-01-01

    We report on a patient with pure transient global amnesia (TGA) whose magnetic resonance imaging (MRI) demonstrated a small region of increased signal intensity in the right hippocampus on diffusion-weighted imaging (DWI). DWI was sensitive and useful for evaluating the early stage of TGA and might help to explain the pathophysiology of TGA. (orig.)

  18. A simulation study on the variation of virtual NMR signals by winding, bobbin, spacer error of HTS magnet

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jun Seong; Lee, Woo Seung; Kim, Jin Sub; Song, Seung Hyun; Nam, Seok Ho; Jeon, Hae Ryong; Beak, Geon Woo; Ko, Tae Kuk [Yonsei University, Seoul (Korea, Republic of)

    2016-09-15

    Recently, production technique and property of the High-Temperature Superconductor (HTS) tape have been improved. Thus, the study on applying an HTS magnet to the high magnetic field application is rapidly increased. A Nuclear Magnetic Resonance (NMR) spectrometer requires high magnitude and homogeneous of central magnetic field. However, the HTS magnet has fabrication errors because shape of HTS is tape and HTS magnet is manufactured by winding HTS tape to the bobbin. The fabrication errors are winding error, bobbin diameter error, spacer thickness error and so on. The winding error occurs when HTS tape is departed from the arranged position on the bobbin. The bobbin diameter and spacer thickness error occur since the diameter of bobbin and spacer are inaccurate. These errors lead magnitude and homogeneity of central magnetic field to be different from its ideal design. The purpose of this paper is to investigate the effect of winding error, bobbin diameter error and spacer thickness error on the central field and field homogeneity of HTS magnet using the virtual NMR signals in MATLAB simulation.

  19. Moderate plasma treatment enhances the quality of optically detected magnetic resonance signals of nitrogen-vacancy centres in nanodiamonds

    Science.gov (United States)

    Sotoma, Shingo; Igarashi, Ryuji; Shirakawa, Masahiro

    2016-05-01

    We demonstrate that a moderate plasma treatment increases the quality of optically detected magnetic resonance (ODMR) signals from negatively charged nitrogen-vacancy centres in nanodiamonds (NDs). We measured the statistics of the ODMR spectra of 50-nm-size NDs before and after plasma treatment. We then evaluated each ODMR spectrum in terms of fluorescence and ODMR intensities, line width and signal-to-noise (SN) ratio. Our results showed that plasma treatment for more than 10 min contributes to higher-quality ODMR signals, i.e. signals that are brighter, stronger, sharper and have a higher SN ratio. We showed that such signal improvement is due to alteration of the surface chemical states of the NDs by the plasma treatment. Our study contributes to the advancement of biosensing applications using ODMR of NDs.

  20. The influence of bias magnetization of nanoparticles on GMR sensor signal and sensitivity for the ultra-low concentration detection

    Science.gov (United States)

    Zhang, Yang; Xu, Jie; Cao, Derang; Li, Qiang; Zhao, Guoxia; Sun, Nian X.; Li, Shandong

    2018-05-01

    In the broad research of the GMR bio-sensing technology, it is vital to explore appropriate magnetic labels and its influences on the detection signal. In this work, four kinds of ferrite particles of γ-Fe2O3, CoFe2O4, NiFe2O4 and NiZnFe2O4 were prepared through calcining the Dimethyl Formamide (DMF) solution of the transition metal nitrates [Fe(NO3)3 and X(NO3)2, X = Co, Ni, Zn] to study the effect of magnetic properties on detection signals using a DC in-plane measuring method. It was revealed that for four particles, the output voltage differences |ΔV| between with and without magnetic particles exhibit log-linear functions of the particles concentrations x in the range from 0.1 to 10 ng/mL. A very low limitation of detection (LOD) of 0.1 ng/mL for all the samples was obtained, which is two orders smaller than that in the previous work. Moreover, the change of output voltage difference at the LOD (|ΔVlim|) is proportional to the magnetization at bias field (bias magnetization, Mbias), which indicates that larger Mbias leads to a lower LOD. This work provides a useful guidance in selecting or preparing magnetic labels to enhance the sensitivity of GMR biosensors.