Fano resonance and persistent current of a quantum ring

International Nuclear Information System (INIS)

Xiong Yongjian; Liang Xianting

2004-01-01

We investigate electron transport and persistent current of a quantum ring weakly attached to current leads. Assuming there is direct coupling (weakly or strongly) between two leads, electrons can transmit by the inter-lead coupling or tunneling through the quantum ring. The interference between the two paths yields asymmetric Fano line shape for conductance. In presence of interior magnetic flux, there is persistent current along the ring with narrow resonance peaks. The positions of the conductance resonances and the persistent current peaks correspond to the quasibound levels of the closed ring. This feature is helpful to determine the energy spectrum of the quantum ring. Our results show that the proposed setup provides a tunable Fano system

Current-driven parametric resonance in magnetic multilayers

International Nuclear Information System (INIS)

Wang, C; Seinige, H; Tsoi, M

2013-01-01

Current-induced parametric excitations were observed in point-contact spin-valve nanodevices. Point contacts were used to inject high densities of direct and microwave currents into spin valves, thus producing oscillating spin-transfer and Oersted-field torques on magnetic moments. The resulting magnetodynamics were observed electrically by measuring rectified voltage signals across the contact. In addition to the spin-torque-driven ferromagnetic resonance we observe doubled-frequency signals which correspond to the parametric excitation of magnetic moments. Numerical simulations suggest that while both spin-transfer torque and ac Oersted field contribute to the parametrically excited dynamics, the ac spin torque dominates, and dc spin torque can switch it on and off. The dc bias dependence of the parametric resonance signal enabled the mapping of instability regions characterizing the nonlinearity of the oscillation. (paper)

Modelling and analysis of the transformer current resonance in dual active bridge converters

DEFF Research Database (Denmark)

Qin, Zian; Shen, Zhan; Blaabjerg, Frede

2017-01-01

Due to the parasitic capacitances of the transformer and inductor in Dual Active Bridge (DAB) converters, resonance happens in the transformer currents. This high frequency resonant current flowing into the full bridges will worsen their soft-switching performance and thereby reduce its efficiency....... In order to study the generation mechanism of this current resonance, the impedance of the transformer and inductor with parasitic components is modelled in this digest. Then, based on the impedance model, an approach is proposed to mitigate the current resonance. Finally, both the impedance model...

Rectifier Current Control for an LLC Resonant Converter Based on a Simplified Linearized Model

OpenAIRE

Zhijian Fang; Junhua Wang; Shanxu Duan; Liangle Xiao; Guozheng Hu; Qisheng Liu

2018-01-01

In this paper, a rectifier current control for an LLC resonant converter is proposed, based on a simplified, two-order, linearized model that adds a rectifier current feedback inner loop to improve dynamic performance. Compared to the traditional large-signal model with seven resonant states, this paper utilizes a rectifier current state to represent the characteristics of the resonant states, simplifying the LLC resonant model from seven orders to two orders. Then, the rectifier current feed...

Current Mode Control for LLC Series Resonant DC-to-DC Converters

Directory of Open Access Journals (Sweden)

Jinhaeng Jang

2015-06-01

Full Text Available Conventional voltage mode control only offers limited performance for LLC series resonant DC-to-DC converters experiencing wide variations in operational conditions. When the existing voltage mode control is employed, the closed-loop performance of the converter is directly affected by unavoidable changes in power stage dynamics. Thus, a specific control design optimized at one particular operating point could become unacceptable when the operational condition is varied. This paper presents a new current mode control scheme which could consistently provide good closed-loop performance for LLC resonant converters for the entire operational range. The proposed control scheme employs an additional feedback from the current of the resonant tank network to overcome the limitation of the existing voltage mode control. The superiority of the proposed current mode control over the conventional voltage mode control is verified using an experimental 150 W LLC series resonant DC-to-DC converter.

Intrinsic current oscillations in an asymmetric triple-barrier resonant tunnelling diode

International Nuclear Information System (INIS)

Wójcik, P; Spisak, B J; Wołoszyn, M; Adamowski, J

2010-01-01

The electronic transport characteristics of an asymmetric triple-barrier resonant tunnelling diode are calculated by the time-dependent Wigner–Poisson method. The intrinsic current oscillations are found in two separate bias voltage ranges. The first one is located below the resonant current peak, and the second lies in the negative differential resistance region. We provide the explanation of the current density oscillations in these two separate bias voltage ranges based on the analysis of the self-consistent potential profiles and changes of electron density. We have shown that two different formation mechanisms are responsible for the current density oscillations in these two bias voltage ranges. In the bias voltage range below the resonant current peak in the current–voltage characteristics, the current density oscillations are caused by the coupling between quasi-bound states in the left and right quantum wells. On the other hand, the current density oscillations in the negative differential resistance region result from the coupling between quasi-bound states in the left quantum well and the quantum well formed in the region of the left contact

Linear Resonance Compressor for Stirling-Type Cryocoolers Activated by Piezoelectric Stack-Type Elements

International Nuclear Information System (INIS)

Sobol, S; Grossman, G

2015-01-01

A novel type of a PZT- based compressor operating at mechanical resonance, suitable for pneumatically-driven Stirling-type cryocoolers was developed theoretically and built practically during this research. A resonance operation at relatively low frequency was achieved by incorporating the piezo ceramics into the moving part, and by reducing the effective piezo stiffness using hydraulic amplification. The detailed concept, analytical model and the test results of the preliminary prototype were reported earlier and presented at ICC17 [2]. A fine agreement between the simulations and experiments spurred development of the current actual compressor designed to drive a miniature Pulse Tube cryocooler, particularly our MTSa model, which operates at 103 Hz and requires an average PV power of 11 W, filling pressure of 40 Bar and a pressure ratio of 1.3. The paper concentrates on design aspects and optimization of the governing parameters. The small stroke to diameter ratio (about 1:10) allows for the use of a composite diaphragm instead of a clearance-seal piston. The motivation is to create an adequate separation between the working fluid and the buffer gas of the compressor, thus preventing possible contamination in the cryocooler. Providing efficiency and power density similar to those of conventional linear compressors, the piezo compressor may serve as a good alternative for cryogenic applications requiring extreme reliability and absence of magnetic field interference. (paper)

Antiferromagnetic resonance excited by oscillating electric currents

Science.gov (United States)

Sluka, Volker

2017-12-01

In antiferromagnetic materials the order parameter exhibits resonant modes at frequencies that can be in the terahertz range, making them interesting components for spintronic devices. Here, it is shown that antiferromagnetic resonance can be excited using the inverse spin-Hall effect in a system consisting of an antiferromagnetic insulator coupled to a normal-metal waveguide. The time-dependent interplay between spin torque, ac spin accumulation, and magnetic degrees of freedom is studied. It is found that the dynamics of the antiferromagnet affects the frequency-dependent conductivity of the normal metal. Further, a comparison is made between spin-current-induced and Oersted-field-induced excitation under the condition of constant power injection.

Frequency-domain analysis of resonant-type ring magnet power supplies

International Nuclear Information System (INIS)

Kim, J.M.S.; Reiniger, K.W.

1993-01-01

For fast-cycling synchrotrons, resonant-type ring magnet power supplies are commonly used to provide a dc-biased ac excitation for the ring magnets. Up to the present, this power supply system has been analyzed using simplified analytical approximation, namely assuming the resonant frequency of the ring magnet network is fixed and equal to the accelerator frequency. This paper presents a frequency-domain analysis technique for a more accurate analysis of resonant-type ring magnet power supplies. This approach identifies that, with the variation of the resonant frequency, the operating conditions of the power supply changes quite dramatically because of the high Q value of the resonant network. The analytical results are verified, using both experimental results and simulation results

Investigation of the sideband effect for the LCL-type grid-connected inverter with high LCL resonance frequency

DEFF Research Database (Denmark)

Yang, Dongsheng; Wang, Xiongfei; Blaabjerg, Frede

2017-01-01

The LCL-type grid connected inverter has been widely used as the intelligent power interface between the distributed generation unit and the power grid. To reduce the cost and volume of the filter, it is desirable to design the LCL filter with higher resonance frequency provided that the quality...... of injected grid current is not compromised. Actually, it is the typical case for the T-type or NPC three-level inverter to design its LCL resonance frequency close to half of the switching frequency. In this case, however, the sideband effect of SPWM modulation can impose a significant impact on the system...

Stator Current Harmonic Control with Resonant Controller for Doubly Fed Induction Generator

DEFF Research Database (Denmark)

Liu, Changjin; Blaabjerg, Frede; Chen, Wenjie

2012-01-01

rotor current control loop for harmonic suppression. The overall control scheme is implemented in dq frame. Based on a mathematical model of the DFIG control system, the effects on system stability using the resonant controller, an analysis of the steady-state error, and the dynamic performance......, are discussed in this paper. Taking these effects into account, the parameters of the resonant controller can be designed and effectively damp the influence from the grid voltage harmonics. As a result, the impacts of the negative sequence fifth- and positive sequence seventh-order voltage harmonics...... harmonics, especially low-order harmonics. This paper proposes a stator current harmonic suppression method using a sixth-order resonant controller to eliminate negative sequence fifth- and positive sequence seventh-order current harmonics. A stator current harmonic control loop is added to the conventional...

Rectifier Current Control for an LLC Resonant Converter Based on a Simplified Linearized Model

Directory of Open Access Journals (Sweden)

Zhijian Fang

2018-03-01

Full Text Available In this paper, a rectifier current control for an LLC resonant converter is proposed, based on a simplified, two-order, linearized model that adds a rectifier current feedback inner loop to improve dynamic performance. Compared to the traditional large-signal model with seven resonant states, this paper utilizes a rectifier current state to represent the characteristics of the resonant states, simplifying the LLC resonant model from seven orders to two orders. Then, the rectifier current feedback inner loop is proposed to increase the control system damping, improving dynamic performance. The modeling and design methodology for the LLC resonant converter are also presented in this paper. A frequency analysis is conducted to verify the accuracy of the simplified model. Finally, a 200 W LLC resonant converter prototype is built to verify the effectiveness of the proposed control strategy. Compared to a traditional single-loop controller, the settling time and voltage droop were reduced from 10.8 ms to 8.6 ms and from 6.8 V to 4.8 V, respectively, using the proposed control strategy.

Current correlators and form factors in the resonance region

Energy Technology Data Exchange (ETDEWEB)

Rosell, I. [Departamento de Ciencias Fisicas, Matematicas y de la Computacion, Universidad CEU Cardenal Herrera, c/Sant Bartomeu 55, E-46115 Alfara del Patriarca, Valencia (Spain); IFIC, Universitat de Valencia - CSIC, Apt. Correus 22085, E-46071 Valencia (Spain)

2009-01-15

Within Resonance Chiral Theory and in the context of QCD current correlators at next-to-leading order in 1/N{sub C}, we have analyzed the two-body form factors which include resonances as a final state. The short-distance constraints have been studied. One of the main motivations is the estimation of the chiral low-energy constants at subleading order, that is, keeping full control of the renormalization scale dependence. As an application we show the resonance estimation of some coupling, L{sub 10}{sup r}({mu}{sub 0})=(-4.4{+-}0.9).10{sup -3} and C{sub 87}{sup r}({mu}{sub 0})=(3.1{+-}1.1).10{sup -5}.

Simulation of a resonant-type ring magnet power supply with multiple resonant cells and energy storage chokes

International Nuclear Information System (INIS)

Kim, J.M.S.; Blackmore, E.W.; Reiniger, K.W.

1992-01-01

For the TRIUMF KAON Factory Booster Ring, a resonant-type magnet power supply has been proposed for the dipole magnet excitation. The Booster Ring magnet power supply system based on resonant circuits, coupled with distributed energy make-up networks, is a complex system, sensitive to many system parameters. When multiple resonant cells, each with its own energy make-up network, are connected in a ring, it is very difficult to derive closed-form solutions to determine the operating conditions of the power supply system. A meaningful way to understand and analyze such a complex system is to use a simulation tool. This paper presents the analysis of operating conditions of the resonant-type ring magnet power supply with multiple resonant cells, using the circuit simulation tool, SPICE. The focus of the study is on the effect of circuit parameter variations in energy storage chokes

Eddy-current effect on resonant magnetoelectric coupling in magnetostrictive-piezoelectric laminated composites

Science.gov (United States)

Liu, Guoxi; Zhang, Chunli; Chen, Weiqiu; Dong, Shuxiang

2013-07-01

An analytical model of resonant magnetoelectric (ME) coupling in magnetostrictive (MS)-piezoelectric (PE) laminated composites in consideration of eddy-current effect in MS layer using equivalent circuit method is presented. Numerical calculations show that: (1) the eddy-current has a strong effect on ME coupling in MS-PE laminated composites at resonant frequency; and (2) the resonant ME coupling is then significantly dependent on the sizes of ME laminated composites, which were neglected in most previous theoretical analyses. The achieved results provide a theoretical guidance for the practice engineering design, manufacture, and application of ME laminated composites and devices.

Current-voltage characteristic of a resonant tunneling diode under electromagnetic radiation

Directory of Open Access Journals (Sweden)

N Hatefi Kargan

2013-09-01

Full Text Available  In this paper, current-voltage characteristic of a resonant tunneling diode under electromagnetic radiation has been calculated and compared with the results when there is no electromagnetic radiation. For calculating current -voltage characteristic, it is required to calculate the transmission coefficient of electrons from the well and barrier structures of this device. For calculating the transmission coefficient of electrons at the presence of electromagnetic radiation, Finite Difference Time Domain (FDTD method has been used and when there is no electromagnetic radiation Transfer Matrix Method (TMM and finite diffirence time domain method have been used. The results show that the presence of electromagnetic radiation causes resonant states other than principal resonant state (without presence of electromagnetic radiation to appear on the transmition coefficient curve where they are in distances from the principal peak and from each other. Also, the presence of electromagnetic radiation causes peaks other than principal peak to appear on the current-voltage characteristics of the device. Under electromagnetic radiation, the number of peaks on the current-voltage curve is smaller than the number of peaks on the current-voltage transmission coefficient. This is due to the fact that current-voltage curve is the result of integration on the energy of electrons, Thus, the sharper and low height peaks on the transmission coefficient do not appear on the current-voltage characteristic curve.

Concerning the generation of geomagnetic giant pulsations by drift-bounce resonance ring current instabilities

Directory of Open Access Journals (Sweden)

K.-H. Glassmeier

1999-03-01

Full Text Available Giant pulsations are nearly monochromatic ULF-pulsations of the Earth's magnetic field with periods of about 100 s and amplitudes of up to 40 nT. For one such event ground-magnetic observations as well as simultaneous GEOS-2 magnetic and electric field data and proton flux measurements made in the geostationary orbit have been analysed. The observations of the electromagnetic field indicate the excitation of an odd-mode type fundamental field line oscillation. A clear correlation between variations of the proton flux in the energy range 30-90 keV with the giant pulsation event observed at the ground is found. Furthermore, the proton phase space density exhibits a bump-on-the-tail signature at about 60 keV. Assuming a drift-bounce resonance instability as a possible generation mechanism, the azimuthal wave number of the pulsation wave field may be determined using a generalized resonance condition. The value determined in this way,  m = - 21 ± 4, is in accord with the value m = - 27 ± 6 determined from ground-magnetic measurements. A more detailed examination of the observed ring current plasma distribution function f shows that odd-mode type eigenoscillations are expected for the case ∂f / ∂W > 0, much as observed. This result is different from previous theoretical studies as we not only consider local gradients of the distribution function in real space, but also in velocity space. It is therefore concluded that the observed giant pulsation is the result of a drift-bounce resonance instability of the ring current plasma coupling to an odd-mode fundamental standing wave. The generation of the bump-on-the-tail distribution causing ∂f / ∂W > 0 can be explained due to velocity dispersion of protons injected into the ring current. Both this velocity dispersion and the necessary substorm activity causing the injection of protons into the nightside magnetosphere are observed.Key words. Magnetospheric physics (energetic particles , trapped

Theory and Applications of Surface Plasmon Resonance, Resonant Mirror, Resonant Waveguide Grating, and Dual Polarization Interferometry Biosensors

Directory of Open Access Journals (Sweden)

Billy W. Day

2010-11-01

Full Text Available Biosensors have been used extensively in the scientific community for several purposes, most notably to determine association and dissociation kinetics, protein-ligand, protein-protein, or nucleic acid hybridization interactions. A number of different types of biosensors are available in the field, each with real or perceived benefits over the others. This review discusses the basic theory and operational arrangements of four commercially available types of optical biosensors: surface plasmon resonance, resonant mirror, resonance waveguide grating, and dual polarization interferometry. The different applications these techniques offer are discussed from experiments and results reported in recently published literature. Additionally, recent advancements or modifications to the current techniques are also discussed.

Quasi-Resonant Full-Wave Zero-Current Switching Buck Converter Design, Simulation and Application

OpenAIRE

Yanik, G.; Isen, E.

2015-01-01

—This paper presents a full wave quasi-resonant zerocurrent switching buck converter design, simulation and application. The converter control uses with zero-current switching (ZCS) technique to decrease the switching losses. Comparing to conventional buck converter, resonant buck converter includes a resonant tank equipped with resonant inductor and capacitor. The converter is analyzed in mathematical for each subintervals. Depending on the desired input and output electrical quantities, con...

Resonant fields created by spiral electric currents in Tokamaks

International Nuclear Information System (INIS)

Fernandes, A.S.; Caldas, I.L.

1985-01-01

The influence of the resonant magnetic perturbations, created by electric currents in spirals, on the plasma confinement in a tokamak with circular section and large aspect ratio is investigated. These perturbations create magnetic islands around the rational magnetic surface which has the helicity of the helicoidal currents. The intensities of these currents are calculated in order to the magnetic islands reach the limiter or others rational surfaces, what could provoke the plasma disrupture. The electric current intensities are estimated, in two spiral sets with different helicities, which create a predominantly stocastic region among the rational magnetic surfaces with these helicities. (L.C.) [pt

Resonant geomagnetic field oscillations and Birkeland currents in the morning sector

International Nuclear Information System (INIS)

Potemra, T.A.; Zanetti, L.J.; Bythrow, P.F.; Erlandson, R.E.; Lundin, R.; Marklund, G.T.; Block, L.P.; Lindqvist, P.A.

1988-01-01

Magnetic field, electric field, and particle measurements acquired by the Viking satellite and magnetic field measurements acquired by the Active Magnetosphere Particle Tracer Explorers (AMPTE) CCE satellite have been used to study the relationship between large-scale Birkeland currents and resonant oscillations in the Earth's magnetic field. Region 1, region 2, and northward B Z (NBZ) Birkeland currents were identified with the data acquired by the Viking magnetic field instrument. Magnetic field oscillations, present in each of the 10 consecutive Viking passes studied here, have periods between 1 min. and 6 min. and amplitudes from 5 nT to 60 nT. These oscillations extend from lower L shells where they correlate with the CCCE observations up to at least the interface between the region 1 and region 2 Birkeland current system. The Viking particle observations confirm that the region 1/region 2 interface maps closely to the interface between the low-latitude boundary layer (LLBL) and the central plasma sheet (CPS). Electric and magnetic field variations are closely correlated in the region 1 Birkeland current. In the region 2 system of Birkeland currents, the northward electric and eastward magnetic field components show the same resonance oscillations with the electric field variations leading the magnetic field by approximately 90 degree. There is evidence that the amplitudes of the oscillations observed by Viking are correlated with interplanetary magnetic field (IMF) cone angle. In one case, the energy-time dispersion signature of temporal magnetosheath plasma injection into the low-latitude boundary layer was associated with the resonant oscillations. These relationships and the presence of the resonant oscillations on field lines up to the region 1/region 2 (LLBL/CPS) interface lead us to conclude that there are several features in the solar wind and the direction of the IMF that can initiate magnetospheric pulsations

Comments, with reply, on 'Parallel resonant converter with LLC-type commutation' by C. Q. Lee et al.

Science.gov (United States)

Hamill, David C.

1991-05-01

In a recent paper by Lee et al. (1989), the authors analyzed a DC-DC converter that they termed the LLC-type PRC (parallel resonant converter). Its resonant network contains three active components-two inductances and a parallel capacitance -and as a consequence the the converter might be expected to have third-order dynamics. But Lee et al. employed a matrix transformation to show that the behavior of the circuit may be represented as a state-plane trajectory, as for a second-order circuit. The purpose of this contribution is to show that the converter has a zero-frequency eigenvalue, associated with undesirable circulating DC. The second-order dynamics exhibited by the third-order converter are explained by an application of Thevenin's theorem. Some aerospace applications of the LLC-type parallel resonant converter (PRC) are discussed. In their reply, the authors show that the circulating direct current does not exist in the practical converter circuit.

Features of the effect of the parameters of resonance systems with different configurations on the current-voltage characteristics of resonant-tunneling nanostructures in a subterahertz frequency range

International Nuclear Information System (INIS)

Aleksanyan, A.A.; Volchkov, N.A.; Dravin, V.A.; Kazakov, I.P.; Karuzskij, A.L.; Murzin, V.N.; Perestoronin, A.V.; Tskhovrebov, A.M.; Shmelev, S.S.

2014-01-01

Features of the effect of a subterahertz microwave field on the current characteristics of a resonant-tunneling diode in resonance systems with different configurations have been studied. Changes in the current characteristics of the resonant-tunneling diode under variation of the electrophysical parameters of dielectric and microstrip resonators, in particular high-Q-factor superconducting microstrip resonators, have been experimentally studied and analyzed [ru

Semiclassical description of resonant tunnel effect: bifurcations and periodic orbits in the resonant current

International Nuclear Information System (INIS)

Rouben, D.C.

1997-01-01

A semiclassical method for resonant tunneling in a quantum well in the presence of a magnetic field tilted with regard to an electric field is developed. In particular a semiclassical formula is derived for the total current of electrons after the second barrier of the quantum well. The contribution of the stable and unstable orbits is studied. It appears that the parameters which describe the classical chaos in the quantum well have an important effect on the tunneling current. A numerical experiment is led, the contributions to the current of some particular orbits are evaluated and the results are compared with those given by the quantum theory. (A.C.)

Concerning the generation of geomagnetic giant pulsations by drift-bounce resonance ring current instabilities

Directory of Open Access Journals (Sweden)

K.-H. Glassmeier

Full Text Available Giant pulsations are nearly monochromatic ULF-pulsations of the Earth's magnetic field with periods of about 100 s and amplitudes of up to 40 nT. For one such event ground-magnetic observations as well as simultaneous GEOS-2 magnetic and electric field data and proton flux measurements made in the geostationary orbit have been analysed. The observations of the electromagnetic field indicate the excitation of an odd-mode type fundamental field line oscillation. A clear correlation between variations of the proton flux in the energy range 30-90 keV with the giant pulsation event observed at the ground is found. Furthermore, the proton phase space density exhibits a bump-on-the-tail signature at about 60 keV. Assuming a drift-bounce resonance instability as a possible generation mechanism, the azimuthal wave number of the pulsation wave field may be determined using a generalized resonance condition. The value determined in this way, 
m = - 21 ± 4, is in accord with the value m = - 27 ± 6 determined from ground-magnetic measurements. A more detailed examination of the observed ring current plasma distribution function f shows that odd-mode type eigenoscillations are expected for the case ∂f / ∂W > 0, much as observed. This result is different from previous theoretical studies as we not only consider local gradients of the distribution function in real space, but also in velocity space. It is therefore concluded that the observed giant pulsation is the result of a drift-bounce resonance instability of the ring current plasma coupling to an odd-mode fundamental standing wave. The generation of the bump-on-the-tail distribution causing ∂f / ∂W > 0 can be explained due to velocity dispersion of protons injected into the ring current. Both this velocity dispersion and the necessary substorm activity causing the injection of protons into the nightside magnetosphere are observed

Dependence of ion beam current on position of mobile plate tuner in multi-frequencies microwaves electron cyclotron resonance ion source

International Nuclear Information System (INIS)

Kurisu, Yosuke; Kiriyama, Ryutaro; Takenaka, Tomoya; Nozaki, Dai; Sato, Fuminobu; Kato, Yushi; Iida, Toshiyuki

2012-01-01

We are constructing a tandem-type electron cyclotron resonance ion source (ECRIS). The first stage of this can supply 2.45 GHz and 11-13 GHz microwaves to plasma chamber individually and simultaneously. We optimize the beam current I FC by the mobile plate tuner. The I FC is affected by the position of the mobile plate tuner in the chamber as like a circular cavity resonator. We aim to clarify the relation between the I FC and the ion saturation current in the ECRIS against the position of the mobile plate tuner. We obtained the result that the variation of the plasma density contributes largely to the variation of the I FC when we change the position of the mobile plate tuner.

Modeling and Analysis of Resonance in LCL-Type Grid-Connected Inverters under Different Control Schemes

Directory of Open Access Journals (Sweden)

Yanxue Yu

2017-01-01

Full Text Available As a basic building block in power systems, the three-phase voltage-source inverter (VSI connects the distributed energy to the grid. For the inductor-capacitor-inductor (LCL-filter three-phase VSI, according to different current sampling position and different reference frame, there mainly exist four control schemes. Different control schemes present different impedance characteristics in their corresponding determined frequency range. To analyze the existing resonance phenomena due to the variation of grid impedances, the sequence impedance models of LCL-type grid-connected three-phase inverters under different control schemes are presented using the harmonic linearization method. The impedance-based stability analysis approach is then applied to compare the relative stability issues due to the impedance differences at some frequencies and to choose the best control scheme and the better controller parameters regulating method for the LCL-type three-phase VSI. The simulation and experiments both validate the resonance analysis results.

Analysis and design of grid-current-feedback active damping for LCL resonance in grid-connected voltage source converters

DEFF Research Database (Denmark)

Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

2014-01-01

This paper investigates the active damping of LCL-filter resonance within single-loop grid current control of grid-connected voltage source converters. First, the basic analysis in the continuous s-domain reveals that the grid-current-feedback active damping forms a virtual impedance across...... in a digital control system. The instability induced by the negative virtual resistance, which is commonly experienced in the feedback-type active damping, can thus be avoided. A systematic design method of the highpass filter is also proposed by the help of root locus analysis in the discrete z-domain. Lastly...

Scattering-Type Surface-Plasmon-Resonance Biosensors

Science.gov (United States)

Wang, Yu; Pain, Bedabrata; Cunningham, Thomas; Seshadri, Suresh

2005-01-01

Biosensors of a proposed type would exploit scattering of light by surface plasmon resonance (SPR). Related prior biosensors exploit absorption of light by SPR. Relative to the prior SPR biosensors, the proposed SPR biosensors would offer greater sensitivity in some cases, enough sensitivity to detect bioparticles having dimensions as small as nanometers. A surface plasmon wave can be described as a light-induced collective oscillation in electron density at the interface between a metal and a dielectric. At SPR, most incident photons are either absorbed or scattered at the metal/dielectric interface and, consequently, reflected light is greatly attenuated. The resonance wavelength and angle of incidence depend upon the permittivities of the metal and dielectric. An SPR sensor of the type most widely used heretofore includes a gold film coated with a ligand a substance that binds analyte molecules. The gold film is thin enough to support evanescent-wave coupling through its thickness. The change in the effective index of refraction at the surface, and thus the change in the SPR response, increases with the number of bound analyte molecules. The device is illuminated at a fixed wavelength, and the intensity of light reflected from the gold surface opposite the ligand-coated surface is measured as a function of the angle of incidence. From these measurements, the angle of minimum reflection intensity is determined

Auroral Current and Electrodynamics Structure (ACES) Observations of Ionospheric Feedback in the Alfven Resonator

Science.gov (United States)

Cohen, Ian J.; Lessard, Marc; Lund, Eric J.; Bounds, Scott R.; Kletzing, Craig; Kaeppler, Stephen R.; Sigsbee, Kristine M.; Streltsov, Anatoly V.; Labelle, James W.; Dombrowski, Micah P.;

Current control loop design and analysis based on resonant regulators for microgrid applications

DEFF Research Database (Denmark)

Federico, de Bosio; Pastorelli, Michelle; de Sousa Ribeiro, Luiz Antonio

2015-01-01

Voltage and current control loops play an important role in the performance of microgrids employing power electronics voltage source inverters. Correct design of feedback loops is essential for the proper operation of these systems. This paper analyzes the influence of state feedback cross......-coupling in the design of resonant regulators for inner current loops in power converters operating in standalone microgrids. It is also demonstrated that the effect of state feedback cross-coupling degrades the performance of the control loops by increasing the steady-state error. Different resonant regulators...

Effect of eddy current damping on phononic band gaps generated by locally resonant periodic structures

Science.gov (United States)

Ozkaya, Efe; Yilmaz, Cetin

2017-02-01

The effect of eddy current damping on a novel locally resonant periodic structure is investigated. The frequency response characteristics are obtained by using a lumped parameter and a finite element model. In order to obtain wide band gaps at low frequencies, the periodic structure is optimized according to certain constraints, such as mass distribution in the unit cell, lower limit of the band gap, stiffness between the components in the unit cell, the size of magnets used for eddy current damping, and the number of unit cells in the periodic structure. Then, the locally resonant periodic structure with eddy current damping is manufactured and its experimental frequency response is obtained. The frequency response results obtained analytically, numerically and experimentally match quite well. The inclusion of eddy current damping to the periodic structure decreases amplitudes of resonance peaks without disturbing stop band width.

Electron paramagnetic resonance field-modulation eddy-current analysis of silver-plated graphite resonators

Science.gov (United States)

Mett, Richard R.; Anderson, James R.; Sidabras, Jason W.; Hyde, James S.

2005-09-01

Magnetic field modulation is often introduced into a cylindrical TE011 electron paramagnetic resonance (EPR) cavity through silver plating over a nonconductive substrate. The plating thickness must be many times the skin depth of the rf and smaller than the skin depth of the modulation. We derive a parameter that quantifies the modulation field penetration and find that it also depends on resonator dimensions. Design criteria based on this parameter are presented graphically. This parameter is then used to predict the behavior of eddy currents in substrates of moderate conductivity, such as graphite. The conductivity of the graphite permits improved plating uniformity and permits use of electric discharge machining (EDM) techniques to make the resonator. EDM offers precision tolerances of 0.005 mm and is suitable for small, complicated shapes that are difficult to machine by other methods. Analytic predictions of the modulation penetration are compared with the results of finite-element simulations. Simulated magnetic field modulation uniformity and penetration are shown for several elemental coils and structures including the plated graphite TE011 cavity. Fabrication and experimental testing of the structure are discussed. Spatial inhomogeneity of the modulation phase is also investigated by computer simulation. We find that the modulation phase is uniform to within 1% over the TE011 cavity. Structures of lower symmetry have increased phase nonuniformity.

Dual resonance models and their currents

International Nuclear Information System (INIS)

Johnson, E.A.

1978-01-01

It is shown how dual resonance models were rederived from the concept of a string tracing out a surface in space-time. Thus, interacting strings reproduce the dual amplitudes. A scheme for tackling the unitarity problem began to develop. As a consistent theory of hadronic processes began to be built, workers at the same time were naturally led to expect that leptons could be included with hadrons in a unified dual theory. Thus, there is a search for dual amplitudes which would describe interactions between hadrons and currents (for example, electrons), as well as interactions involving only hadrons. Such amplitudes, it is believed, will be the correct ones, describing the real world. Such amplitudes will provide valuable information concerning such things as hadronic form factors. The great difficulties in building current-amplitudes with the required properties of proper factorization on a good spectrum, duality, current algebra, and proper asymptotic behavior are described. Dual models at the present time require for consistency, an intercept value of α 0 = 1 and a dimension value of d = 26 (or d = 10). There have been speculations that the unphysical dimension may be made physical by associating the ''extra dimensions'' with certain internal degrees of freedom. However, it is desired that the theory itself, force the dimension d = 4. It is quite possible that the dimension problem and the intercept problem are tied together and that resolving either problem will resolve the other. Order by order, a new dual current is constructed that is manifestly factorizable and which appears to be valid for arbitrary space-time dimension. The fact that this current is not bound at d = 26, leads to interesting speculations on the nature of dual currents

Valley current characterization of high current density resonant tunnelling diodes for terahertz-wave applications

Science.gov (United States)

Jacobs, K. J. P.; Stevens, B. J.; Baba, R.; Wada, O.; Mukai, T.; Hogg, R. A.

2017-10-01

We report valley current characterisation of high current density InGaAs/AlAs/InP resonant tunnelling diodes (RTDs) grown by metal-organic vapour phase epitaxy (MOVPE) for THz emission, with a view to investigate the origin of the valley current and optimize device performance. By applying a dual-pass fabrication technique, we are able to measure the RTD I-V characteristic for different perimeter/area ratios, which uniquely allows us to investigate the contribution of leakage current to the valley current and its effect on the PVCR from a single device. Temperature dependent (20 - 300 K) characteristics for a device are critically analysed and the effect of temperature on the maximum extractable power (PMAX) and the negative differential conductance (NDC) of the device is investigated. By performing theoretical modelling, we are able to explore the effect of typical variations in structural composition during the growth process on the tunnelling properties of the device, and hence the device performance.

Parallel resonant converter with LLC-type commutation

Science.gov (United States)

Lee, C. Q.; Liu, Rui; Batarseh, Issa

1989-11-01

It is shown that by using a proper transformation of state variables, the third-order system of the parallel resonant converter (PRC) with LLC-type commutation can be analyzed by means of a two-dimensional state-plane diagram. A set of characteristic curves which can be used for the converter design is derived from the analysis. It is shown from these curves that the converter possesses more desirable features than the conventional PRC.

Neutron Spin Resonance in the 112-Type Iron-Based Superconductor

Science.gov (United States)

Xie, Tao; Gong, Dongliang; Ghosh, Haranath; Ghosh, Abyay; Soda, Minoru; Masuda, Takatsugu; Itoh, Shinichi; Bourdarot, Frédéric; Regnault, Louis-Pierre; Danilkin, Sergey; Li, Shiliang; Luo, Huiqian

2018-03-01

We use inelastic neutron scattering to study the low-energy spin excitations of the 112-type iron pnictide Ca0.82La0.18Fe0.96Ni0.04As2 with bulk superconductivity below Tc=22 K . A two-dimensional spin resonance mode is found around E =11 meV , where the resonance energy is almost temperature independent and linearly scales with Tc along with other iron-based superconductors. Polarized neutron analysis reveals the resonance is nearly isotropic in spin space without any L modulations. Because of the unique monoclinic structure with additional zigzag arsenic chains, the As 4 p orbitals contribute to a three-dimensional hole pocket around the Γ point and an extra electron pocket at the X point. Our results suggest that the energy and momentum distribution of the spin resonance does not directly respond to the kz dependence of the fermiology, and the spin resonance intrinsically is a spin-1 mode from singlet-triplet excitations of the Cooper pairs in the case of weak spin-orbital coupling.

Ring Current He Ion Control by Bounce Resonant ULF Waves

Science.gov (United States)

Kim, Hyomin; Gerrard, Andrew J.; Lanzerotti, Louis J.; Soto-Chavez, Rualdo; Cohen, Ross J.; Manweiler, Jerry W.

2017-12-01

Ring current energy He ion (˜65 keV to ˜520 keV) differential flux data from the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instrument aboard the Van Allan Probes spacecraft show considerable variability during quiet solar wind and geomagnetic time periods. Such variability is apparent from orbit to orbit (˜9 h) of the spacecraft and is observed to be ˜50-100% of the nominal flux. Using data from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument, also aboard the Van Allen Probes spacecraft, we identify that a dominant source of this variability is from ULF waveforms with periods of tens of seconds. These periods correspond to the bounce resonant timescales of the ring current He ions being measured by RBSPICE. A statistical survey using the particle and field data for one full spacecraft precession period (approximately 2 years) shows that the wave and He ion flux variations are generally anticorrelated, suggesting the bounce resonant pitch angle scattering process as a major component in the scattering of He ions.

Spectral response, dark current, and noise analyses in resonant tunneling quantum dot infrared photodetectors.

Science.gov (United States)

Jahromi, Hamed Dehdashti; Mahmoodi, Ali; Sheikhi, Mohammad Hossein; Zarifkar, Abbas

2016-10-20

Reduction of dark current at high-temperature operation is a great challenge in conventional quantum dot infrared photodetectors, as the rate of thermal excitations resulting in the dark current increases exponentially with temperature. A resonant tunneling barrier is the best candidate for suppression of dark current, enhancement in signal-to-noise ratio, and selective extraction of different wavelength response. In this paper, we use a physical model developed by the authors recently to design a proper resonant tunneling barrier for quantum infrared photodetectors and to study and analyze the spectral response of these devices. The calculated transmission coefficient of electrons by this model and its dependency on bias voltage are in agreement with experimental results. Furthermore, based on the calculated transmission coefficient, the dark current of a quantum dot infrared photodetector with a resonant tunneling barrier is calculated and compared with the experimental data. The validity of our model is proven through this comparison. Theoretical dark current by our model shows better agreement with the experimental data and is more accurate than the previously developed model. Moreover, noise in the device is calculated. Finally, the effect of different parameters, such as temperature, size of quantum dots, and bias voltage, on the performance of the device is simulated and studied.

Gamma-resonance Contraband Detection using a high current tandem accelerator

International Nuclear Information System (INIS)

Milton, B. F.; Beis, J.; Dale, D.; Rogers, J.; Ruegg, R.; Debiak, T.; Kamykowski, E.; Melnychuk, S.; Rathke, J.; Sredniawski, J.

1999-01-01

TRIUMF and Northrop Grumman have developed a new system for the detection of concealed explosives and drugs. This Contraband Detection System (CDS) is based on the resonant absorption by 14 N of gammas produced using 13 C(p,γ) 14 N. The chosen reaction uses protons at 1.75 MeV and the gammas have an energy of 9.17 MeV. By measuring both the resonant and the non-resonant absorption using detectors with good spatial resolution, and applying standard tomographic techniques, we are able to produce 3D images of both the nitrogen partial density and the total density. The images together may be utilized with considerable confidence to determine if small amounts of nitrogen based explosives, heroin or cocaine are present in the interrogated containers. Practical Gamma Resonant Absorption (GRA) scanning requires an intense source of protons. However this proton source must also be very stable, have low energy spread, and have good spatial definition. These demands suggested a tandem as the accelerator of choice. We have therefore constructed a 2 MeV H - tandem optimized for high current (10 mA) operation, while minimizing the overall size of the accelerator. This has required several special innovations which will be presented in the paper. We will also present initial commissioning results

Measuring ac losses in superconducting cables using a resonant circuit:Resonant current experiment (RESCUE)

DEFF Research Database (Denmark)

Däumling, Manfred; Olsen, Søren Krüger; Rasmussen, Carsten

1998-01-01

be recorded using, for example, a digital oscilloscope. The amplitude decay of the periodic voltage or current accurately reflects the power loss in the system. It consists of two components-an ohmic purely exponential one (from leads, contacts, etc.), and a nonexponential component originating from......A simple way to obtain true ac losses with a resonant circuit containing a superconductor, using the decay of the circuit current, is described. For the measurement a capacitor is short circuited with a superconducting cable. Energy in the circuit is provided by either charging up the capacitors...... with a certain voltage, or letting a de flow in the superconductor. When the oscillations are started-either by opening a switch in case a de is flowing or by closing a switch to connect the charged capacitors with the superconductor-the current (via a Rogowski coil) or the voltage on the capacitor can...

Current status of superparamagnetic iron oxide contrast agents for liver magnetic resonance imaging.

Science.gov (United States)

Wang, Yi-Xiang J

2015-12-21

Five types of superparamagnetic iron oxide (SPIO), i.e. Ferumoxides (Feridex(®) IV, Berlex Laboratories), Ferucarbotran (Resovist(®), Bayer Healthcare), Ferumoxtran-10 (AMI-227 or Code-7227, Combidex(®), AMAG Pharma; Sinerem(®), Guerbet), NC100150 (Clariscan(®), Nycomed,) and (VSOP C184, Ferropharm) have been designed and clinically tested as magnetic resonance contrast agents. However, until now Resovist(®) is current available in only a few countries. The other four agents have been stopped for further development or withdrawn from the market. Another SPIO agent Ferumoxytol (Feraheme(®)) is approved for the treatment of iron deficiency in adult chronic kidney disease patients. Ferumoxytol is comprised of iron oxide particles surrounded by a carbohydrate coat, and it is being explored as a potential imaging approach for evaluating lymph nodes and certain liver tumors.

Modeling and control of Type-2 wind turbines for sub-synchronous resonance damping

International Nuclear Information System (INIS)

Mancilla-David, Fernando; Domínguez-García, José Luis; De Prada, Mikel; Gomis-Bellmunt, Oriol; Singh, Mohit; Muljadi, Eduard

2015-01-01

Highlights: • Dynamic modeling of Type-2 wind turbines for sub-synchronous resonance studies. • Systematic design of a power system stabilizer for Type-2 wind turbines. • Assessment of Type-2 wind turbines to suppress sub-synchronous resonance events. - Abstract: The rapid increase of wind power penetration into power systems around the world has led transmission system operators to enforce stringent grid codes requiring novel functionalities from renewable energy-based power generation. For this reason, there exists a need to asses whether wind turbines (WTs) will comply with such functionalities to ensure power system stability. This paper demonstrates that Type-2 WTs may induce sub-synchronous resonance (SSR) events when connected to a series-compensated transmission line, and with proper control, they may also suppress such events. The paper presents a complete dynamic model tailored to study, via eigenanalysis, SSR events in the presence of Type-2 WTs, and a systematic procedure to design a power system stabilizer using only local and measurable signals. Results are validated through a case study based on the IEEE first benchmark model for SSR studies, as well as with transient computer simulations

Growth and characterization of high current density, high-speed InAs/AlSb resonant tunneling diodes

Science.gov (United States)

Soderstrom, J. R.; Brown, E. R.; Parker, C. D.; Mahoney, L. J.; Yao, J. Y.

1991-01-01

InAs/AlSb double-barrier resonant tunneling diodes with peak current densities up to 370,000 A/sq cm and high peak-to-valley current ratios of 3.2 at room temperature have been fabricated. The peak current density is well-explained by a stationary-state transport model with the two-band envelope function approximation. The valley current density predicted by this model is less than the experimental value by a factor that is typical of the discrepancy found in other double-barrier structures. It is concluded that threading dislocations are largely inactive in the resonant tunneling process.

Three-phase Resonant DC-link Converter

OpenAIRE

Munk-Nielsen, Stig

1997-01-01

The purpose of the project is to develop a three-phase resonant converter suitable for standard speed drives. The motivation for working with resonant converters is found in the problem of the standard converter type used today. In standard converter type Pulse Width Modulated-Voltage Source Inverter, PWM-VSI, the switches are subject to high current and voltage stress during switching, which causes losses. The fast switching of modern switches reduces switching losses. Unfortunately this pro...

Magnetic Resonance Imaging Findings of Adult-Onset Glutaric Aciduria Type

Energy Technology Data Exchange (ETDEWEB)

Sonmez, G.; Mutlu, H.; Ozturk, E.; Sildiroglu, H.O.; Keskin, A.T.; Basekim, C.C.; Kizilkaya, E. [Dept. of Radiology, GATA Haydarpasa Teaching Hospital, Istanbul (Turkey)

2007-07-15

Glutaric aciduria or glutaric acidemia type I, an autosomal recessive disease, usually presents with an acute encephalopathic crisis in young children. We report the magnetic resonance (MR) and proton MR spectroscopy (MRS) imaging findings of a previously healthy 20-year-old man who presented with recurrent headaches. Organic acids from the patient's urine contained large amounts of adipate, glutarate, and 3-hydroxyglutarate consistent with glutaric aciduria type I.

Magnetic Resonance Imaging Findings of Adult-Onset Glutaric Aciduria Type

International Nuclear Information System (INIS)

Sonmez, G.; Mutlu, H.; Ozturk, E.; Sildiroglu, H.O.; Keskin, A.T.; Basekim, C.C.; Kizilkaya, E.

2007-01-01

Glutaric aciduria or glutaric acidemia type I, an autosomal recessive disease, usually presents with an acute encephalopathic crisis in young children. We report the magnetic resonance (MR) and proton MR spectroscopy (MRS) imaging findings of a previously healthy 20-year-old man who presented with recurrent headaches. Organic acids from the patient's urine contained large amounts of adipate, glutarate, and 3-hydroxyglutarate consistent with glutaric aciduria type I

Effect of an additional magnetic field on Hanle-type absorption resonances

International Nuclear Information System (INIS)

Singh Grewal, Raghwinder; Pattabiraman, M

2014-01-01

We computationally compare Hanle-type resonances for a F g =1→F e =0 transition of the 87 RbD 2 line for magnetic field scans parallel (longitudinal scan) and perpendicular (transverse scan) to the direction of propagation of the optical field in the presence of an additional transverse magnetic field (TMF). For a linearly polarized light, the coherent population trapping (CPT) resonances split at line centre and are identical for both longitudinal and transverse scans. When the probe beam ellipticity is varied, the effect of the TMF is found to be opposite for longitudinal and transverse scans. For a longitudinal scan, the splitting observed in the CPT resonance evolves into an enhanced absorption resonance with an increase in ellipticity. For a transverse scan, the splitting vanishes at higher ellipticities. This can be understood in terms of population redistribution in the ground state sublevels and near-neighbor ground state coherences created by the TMF. We also show that the enhanced absorption signal that splits the CPT resonance strongly depends on transit time, and the CPT resonance strength depends on the excited state dephasing rate. (paper)

Effect of environment fluctuations on a Josephson current

International Nuclear Information System (INIS)

Galaktionov, A.V.

2017-01-01

Highlights: • Josephson current is influenced differently by environment fluctuations. • Two types of environment are studied: ohmic and resonant-mode one. • A crossover to a Josephson π-junction is possible for both of them. - Abstract: An influence of an electromagnetic environment on a Josephson current through a tunnel junction is studied with the aid of Ambegaokar-Eckern-Schön effective action. Two types of environment are investigated: one, characterized by a resonant mode, and an ohmic one. The crossover to a Josephson π-junction is possible for both of them. In addition the resonant-mode environment results in an increase of a Josephson current when the ratio of the doubled superconducting gap to the frequency of the mode is close to an integer number.

Millimeter-wave FEL-oscillator with a new type Bragg resonator: advantages in efficiency and selectivity

CERN Document Server

Ginzburg, N S; Kaminsky, A K; Peskov, N Yu; Sedykh, S N; Sergeev, A P

2000-01-01

An FEL-oscillator with a new type of Bragg resonator was realized on the basis of linac LIU-3000 (JINR, Dubna) (0.8 MeV/200 A/200 ns). This resonator consists of two corrugated waveguide sections having a step of phase pi between the corrugations at the point of connection. The selective properties of a resonator of this type are significantly improved in comparison with a traditional two-mirror Bragg resonator. The output power was about 50 MW at a frequency of 30.7 GHz with the optimal parameters of the resonator, which corresponds to the efficiency of 35%, which is the highest for millimeter wavelength FEL. Radiation at the fundamental mode and the two side modes with the frequencies coincided to the 'cold' microwave testing was separately observed depending on the magnetic fields of the wiggler and solenoid.

Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials.

Science.gov (United States)

Liu, Chao; Schauff, Joseph; Lee, Seokhyeong; Cho, Jeong-Hyun

2017-03-23

Terahertz (THz) split ring resonator (SRR) metamaterials (MMs) has been studied for gas, chemical, and biomolecular sensing applications because the SRR is not affected by environmental characteristics such as the temperature and pressure surrounding the resonator. Electromagnetic radiation in THz frequencies is biocompatible, which is a critical condition especially for the application of the biomolecular sensing. However, the quality factor (Q-factor) and frequency responses of traditional thin-film based split ring resonator (SRR) MMs are very low, which limits their sensitivities and selectivity as sensors. In this work, novel nanopillar-based SRR MMs, utilizing displacement current, are designed to enhance the Q-factor up to 450, which is around 45 times higher than that of traditional thin-film-based MMs. In addition to the enhanced Q-factor, the nanopillar-based MMs induce a larger frequency shifts (17 times compared to the shift obtained by the traditional thin-film based MMs). Because of the significantly enhanced Q-factors and frequency shifts as well as the property of biocompatible radiation, the THz nanopillar-based SRR are ideal MMs for the development of biomolecular sensors with high sensitivity and selectivity without inducing damage or distortion to biomaterials. A novel fabrication process has been demonstrated to build the nanopillar-based SRRs for displacement current mediated THz MMs. A two-step gold (Au) electroplating process and an atomic layer deposition (ALD) process are used to create sub-10 nm scale gaps between Au nanopillars. Since the ALD process is a conformal coating process, a uniform aluminum oxide (Al2O3) layer with nanometer-scale thickness can be achieved. By sequentially electroplating another Au thin film to fill the spaces between Al2O3 and Au, a close-packed Au-Al2O3-Au structure with nano-scale Al2O3 gaps can be fabricated. The size of the nano-gaps can be well defined by precisely controlling the deposition cycles of the

Continuum Modeling of Inductor Hysteresis and Eddy Current Loss Effects in Resonant Circuits

Energy Technology Data Exchange (ETDEWEB)

Pries, Jason L. [ORNL; Tang, Lixin [ORNL; Burress, Timothy A. [ORNL

2017-10-01

This paper presents experimental validation of a high-fidelity toroid inductor modeling technique. The aim of this research is to accurately model the instantaneous magnetization state and core losses in ferromagnetic materials. Quasi–static hysteresis effects are captured using a Preisach model. Eddy currents are included by coupling the associated quasi-static Everett function to a simple finite element model representing the inductor cross sectional area. The modeling technique is validated against the nonlinear frequency response from two different series RLC resonant circuits using inductors made of electrical steel and soft ferrite. The method is shown to accurately model shifts in resonant frequency and quality factor. The technique also successfully predicts a discontinuity in the frequency response of the ferrite inductor resonant circuit.

Three-phase Resonant DC-link Converter

DEFF Research Database (Denmark)

Munk-Nielsen, Stig

The purpose of the project is to develop a three-phase resonant converter suitable for standard speed drives. The motivation for working with resonant converters is found in the problem of the standard converter type used today. In standard converter type Pulse Width Modulated-Voltage Source...... Inverter, PWM-VSI, the switches are subject to high current and voltage stress during switching, which causes losses. The fast switching of modern switches reduces switching losses. Unfortunately this procedure increased dv/dt and the size of the input/output filters of the PWM-SVI must be increased...

Current developments with TRIUMF’s titanium-sapphire laser based resonance ionization laser ion source

Energy Technology Data Exchange (ETDEWEB)

Lassen, J., E-mail: LASSEN@triumf.ca; Li, R. [TRIUMF (Canada); Raeder, S. [GSI Helmholtzzentrum für Schwerionenforschung GmbH (Germany); Zhao, X.; Dekker, T. [TRIUMF (Canada); Heggen, H. [GSI Helmholtzzentrum für Schwerionenforschung GmbH (Germany); Kunz, P.; Levy, C. D. P.; Mostanmand, M.; Teigelhöfer, A.; Ames, F. [TRIUMF (Canada)

2017-11-15

Developments at TRIUMF’s isotope separator and accelerator (ISAC) resonance ionization laser ion source (RILIS) in the past years have concentrated on increased reliability for on-line beam delivery of radioactive isotopes to experiments, as well as increasing the number of elements available through resonance ionization and searching for ionization schemes with improved efficiency. The current status of these developments is given with a list of two step laser ionization schemes implemented recently.

Magnetic resonance neurography. Current perspectives and literature review

International Nuclear Information System (INIS)

Chhabra, Avneesh; Madhuranthakam, Ananth J.; Andreisek, Gustav

2018-01-01

Magnetic resonance neurography (also called MRN or MR neurography) refers to MR imaging dedicated to the peripheral nerves. It is a technique that enhances selective multiplanar visualisation of the peripheral nerve and pathology by encompassing a combination of two-dimensional, three-dimensional and diffusion imaging pulse sequences. Referring physicians who seek imaging techniques that can depict and diagnose peripheral nerve pathologies superior to conventional MR imaging are driving the demand for MRN. This article reviews the pathophysiology of peripheral nerves in common practice scenarios, technical considerations of MRN, current indications of MRN, normal and abnormal neuromuscular appearances, and imaging pitfalls. Finally, the emerging utility of diffusion-weighted and diffusion tensor imaging is discussed and future directions are highlighted. (orig.)

Magnetic resonance neurography. Current perspectives and literature review

Energy Technology Data Exchange (ETDEWEB)

Chhabra, Avneesh [UT Southwestern Medical Center, Radiology and Orthopedic Surgery and Musculoskeletal Radiology, Dallas, TX (United States); Johns Hopkins University, Adjunct Faculty, Baltimore, MD (United States); Madhuranthakam, Ananth J. [UT Southwestern Medical Center, Department of Radiology and Advanced Imaging Research Institute, Dallas, TX (United States); Andreisek, Gustav [University of Zurich, Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zuerich (Switzerland)

2018-02-15

Magnetic resonance neurography (also called MRN or MR neurography) refers to MR imaging dedicated to the peripheral nerves. It is a technique that enhances selective multiplanar visualisation of the peripheral nerve and pathology by encompassing a combination of two-dimensional, three-dimensional and diffusion imaging pulse sequences. Referring physicians who seek imaging techniques that can depict and diagnose peripheral nerve pathologies superior to conventional MR imaging are driving the demand for MRN. This article reviews the pathophysiology of peripheral nerves in common practice scenarios, technical considerations of MRN, current indications of MRN, normal and abnormal neuromuscular appearances, and imaging pitfalls. Finally, the emerging utility of diffusion-weighted and diffusion tensor imaging is discussed and future directions are highlighted. (orig.)

Semiclassical description of resonant tunnel effect: bifurcations and periodic orbits in the resonant current; Description semiclassique de l`effet tunnel resonant: bifurcations et orbites periodiques dans le courant resonant

Energy Technology Data Exchange (ETDEWEB)

Rouben, D C

1997-11-28

A semiclassical method for resonant tunneling in a quantum well in the presence of a magnetic field tilted with regard to an electric field is developed. In particular a semiclassical formula is derived for the total current of electrons after the second barrier of the quantum well. The contribution of the stable and unstable orbits is studied. It appears that the parameters which describe the classical chaos in the quantum well have an important effect on the tunneling current. A numerical experiment is led, the contributions to the current of some particular orbits are evaluated and the results are compared with those given by the quantum theory. (A.C.) 70 refs.

Magnetic Resonance Imaging Findings of Adult-Onset Glutaric Aciduria Type I

Energy Technology Data Exchange (ETDEWEB)

Sonmez, G.; Mutlu, H.; Ozturk, E.; Sildiroglu, H.O.; Keskin, A.T.; Basekim, C.C.; Kizilkaya, E. [Dept. of Radiology, GATA Haydarpasa Teaching Hospital, Istanbul (Turkey)

2007-07-15

Glutaric aciduria or glutaric acidemia type I, an autosomal recessive disease, usually presents with an acute encephalopathic crisis in young children. We report the magnetic resonance (MR) and proton MR spectroscopy (MRS) imaging findings of a previously healthy 20-year-old man who presented with recurrent headaches. Organic acids from the patient's urine contained large amounts of adipate, glutarate, and 3-hydroxyglutarate consistent with glutaric aciduria type I.

Optimized design of resonant controller for stator current harmonic compensation in DFIG wind turbine systems

DEFF Research Database (Denmark)

Liu, Changjin; Chen, Wenjie; Blaabjerg, Frede

2012-01-01

This paper presents an analytical method to optimize the parameters of resonant controller which is used in a Doubly-Fed Induction Generator (DFIG). In the DFIG control system, the fundamental current loop is controlled by PI-controllers, and the stator harmonic current loop is controlled...

A Novel Magnetic Resonance Imaging (MRI) Approach for Measuring Weak Electric Currents Inside the Human Brain

DEFF Research Database (Denmark)

Göksu, Cihan

of individual ohmic conductivity values may open up the possibility of creating more realistic and accurate head models, which may ameliorate the simulations and practical use of NIBS techniques. Magnetic resonance current density imaging (MRCDI) and magnetic resonance electrical impedance tomography (MREIT......Knowing the electrical conductivity and current density distribution inside the human brain will be useful in various biomedical applications, i.e. for improving the efficiency of non-invasive brain stimulation (NIBS) techniques, the accuracy of electroencephalography (EEG......) and magnetoencephalography (MEG) source localization, or localization of pathological tissues. For example, the accuracy of electric field simulations for NIBS techniques is currently reduced by assigning inaccurate ohmic conductivity values taken from literature to different brain tissues. Therefore, the knowledge...

Spin-dependent current in resonant tunneling diode with ferromagnetic GaMnN layers

International Nuclear Information System (INIS)

Tang, N.Y.

2009-01-01

The spin-polarized tunneling current through a double barrier resonant tunneling diode (RTD) with ferromagnetic GaMnN emitter/collector is investigated theoretically. Two distinct spin splitting peaks can be observed at current-voltage (I-V) characteristics at low temperature. The spin polarization decreases with the temperature due to the thermal effect of electron density of states. When charge polarization effect is considered at the heterostructure, the spin polarization is enhanced significantly. A highly spin-polarized current can be obtained depending on the polarization charge density.

Squeezing and entanglement in doubly resonant, type II, second-harmonic generation

DEFF Research Database (Denmark)

Andersen, Ulrik Lund; Buchhave, Preben

2003-01-01

We investigate, theoretically, the generation of bright and vacuum-squeezed light as well as entanglement in intracavity, type II, phase-matched second-harmonic generation. The cavity in which the crystal is embedded is resonant at the fundamental frequency but not at the second-harmonic frequenc...

Analysis of the current-voltage characteristics lineshapes of resonant tunneling diodes

International Nuclear Information System (INIS)

Rivera, P.H.; Schulz, P.A.

1996-01-01

It is discussed the influence of a two dimensional electron gas at the emitter-barrier interface on the current-voltage characteristics of a Ga As-Al Ga As double-barrier quantum well resonant tunneling diode. This effect is characterized by the modification of the space charge distribution along the structure. Within the framework of a self-consistent calculation we analyse the current-voltage characteristics of the tunneling diodes. This analysis permits us to infer different tunneling ways, related to the formation of confined states in the emitter region, and their signatures in the current-voltage characteristics. We show that varying the spacer layer, together with barrier heights, changes drastically the current density-voltage characteristics lineshapes. We compare our results with a variety of current-voltage characteristics lineshapes. We compare our results with a variety of current-voltage characteristics reported in the literature. The general trend of experimental lineshapes can be reproduced and interpreted with our model. The possibility of tunneling paths is predicted for a range that has not yet been explored experimentally. (author). 12 refs., 4 figs

Brain magnetic resonance imaging correlates of impaired cognition in patients with type 2 diabetes.

NARCIS (Netherlands)

Manschot, S.M.; Brands, A.M.; Grond, J. van der; Kessels, R.P.C.; Algra, A.; Kappelle, L.J.; Biessels, G.J.

2006-01-01

The structural correlates of impaired cognition in type 2 diabetes are unclear. The present study compared cognition and brain magnetic resonance imaging (MRI) between type 2 diabetic patients and nondiabetic control subjects and assessed the relationship between cognition and MRI findings and blood

Magnetic resonance electrical impedance tomography (MREIT): conductivity and current density imaging

International Nuclear Information System (INIS)

Seo, Jin Keun; Kwon, Ohin; Woo, Eung Je

2005-01-01

This paper reviews the latest impedance imaging technique called Magnetic Resonance Electrical Impedance Tomography (MREIT) providing information on electrical conductivity and current density distributions inside an electrically conducting domain such as the human body. The motivation for this research is explained by discussing conductivity changes related with physiological and pathological events, electromagnetic source imaging and electromagnetic stimulations. We briefly summarize the related technique of Electrical Impedance Tomography (EIT) that deals with cross-sectional image reconstructions of conductivity distributions from boundary measurements of current-voltage data. Noting that EIT suffers from the ill-posed nature of the corresponding inverse problem, we introduce MREIT as a new conductivity imaging modality providing images with better spatial resolution and accuracy. MREIT utilizes internal information on the induced magnetic field in addition to the boundary current-voltage measurements to produce three-dimensional images of conductivity and current density distributions. Mathematical theory, algorithms, and experimental methods of current MREIT research are described. With numerous potential applications in mind, future research directions in MREIT are proposed

Bipolar programmable current supply for superconducting nuclear magnetic resonance magnets

Science.gov (United States)

Koivuniemi, Jaakko; Luusalo, Reeta; Hakonen, Pertti

1998-09-01

In high resolution continuous-wave nuclear magnetic resonance (NMR) work well-reproducible, linear sweeps of current are needed. We have developed a microcontroller based programmable current supply, tested with superconducting magnets with inductance of 10 mH and 10 H. We achieved a resolution and noise of 4 ppm. The supply has an internal sweep with programmable ramping rate and a possibility for remote operation from a computer with either GPIB or RS232 interface. It is based on an 18-bit D/A converter. The maximum output current is ±10 A, the sweep rate can be set between 1 μA/s-140 mA/s, and the maximum output voltage is ±2.5 V. In work at ultralow temperatures, especially in superconducting quantum interference device NMR, all rf interference to the experiment should be avoided. One of the sources of this kind of unwanted input is the digital switching noise of fast logic devices. We discuss this problem in the context of our design.

Investigation of DC current injection effect on the microwave characteristics of HTS YBCO microstrip resonators

Energy Technology Data Exchange (ETDEWEB)

Nurgaliev, T., E-mail: timur@ie.bas.bg [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Blagoev, B.; Mateev, E.; Neshkov, L. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Strbik, V. [Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Uspenskaya, L. [Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow (Russian Federation); Nedkov, I. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Chromik, Š. [Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava (Slovakia)

2014-03-15

Highlights: • Current (spin) injection effect in LSMO/YBCO was studied by impedance measurements. • Complex impedance of YBCO increases at current injection from LSMO to YBCO at 77 K. • This increase is due to an increase of the quasiparticle conductivity of YBCO. • Injection does not significantly affect the relaxation time of the quasiparticles. - Abstract: The DC current injection effect from a ferromagnetic (FM) La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSMO) to a high temperature superconducting (HTS) Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7−x} (YBCO) thin film was investigated by the microwave surface impedance measurements in a FM/HTS structure, formed as a microstrip resonator for improving the sensitivity of the experiments. The quality factor and the resonance frequency of this structure were found to strongly depend on the current strength, injected from the LSMO electrode into the HTS microstrip electrode. The magnetic penetration depth and the quasiparticle conductivity of the HTS component were determined to increase under DC current injection process, which in all probability stimulated breaking of Cooper pairs and led to a decrease of the superfluid concentration and an increase of the normal fluid concentration without significantly affecting the relaxation time of the quasiparticles.

Resonant enhancement in leptogenesis

Science.gov (United States)

Dev, P. S. B.; Garny, M.; Klaric, J.; Millington, P.; Teresi, D.

2018-02-01

Vanilla leptogenesis within the type I seesaw framework requires the mass scale of the right-handed neutrinos to be above 109 GeV. This lower bound can be avoided if at least two of the sterile states are almost mass degenerate, which leads to an enhancement of the decay asymmetry. Leptogenesis models that can be tested in current and upcoming experiments often rely on this resonant enhancement, and a systematic and consistent description is therefore necessary for phenomenological applications. In this paper, we give an overview of different methods that have been used to study the saturation of the resonant enhancement when the mass difference becomes comparable to the characteristic width of the Majorana neutrinos. In this limit, coherent flavor transitions start to play a decisive role, and off-diagonal correlations in flavor space have to be taken into account. We compare various formalisms that have been used to describe the resonant regime and discuss under which circumstances the resonant enhancement can be captured by simplified expressions for the CP asymmetry. Finally, we briefly review some of the phenomenological aspects of resonant leptogenesis.

Microstrip Resonator for High Field MRI with Capacitor-Segmented Strip and Ground Plane

DEFF Research Database (Denmark)

Zhurbenko, Vitaliy; Boer, Vincent; Petersen, Esben Thade

2017-01-01

) segmenting stripe and ground plane of the resonator with series capacitors. The design equations for capacitors providing symmetric current distribution are derived. The performance of two types of segmented resonators are investigated experimentally. To authors’ knowledge, a microstrip resonator, where both......, strip and ground plane are capacitor-segmented, is shown here for the first time....

General formulation for magnetohydrodynamic wave propagation, fire-hose, and mirror instabilities in Harris-type current sheets

International Nuclear Information System (INIS)

Hau, L.-N.; Lai, Y.-T.

2013-01-01

Harris-type current sheets with the magnetic field model of B-vector=B x (z)x-caret+B y (z)y-caret have many important applications to space, astrophysical, and laboratory plasmas for which the temperature or pressure usually exhibits the gyrotropic form of p↔=p ∥ b-caretb-caret+p ⊥ (I↔−b-caretb-caret). Here, p ∥ and p ⊥ are, respectively, to be the pressure component along and perpendicular to the local magnetic field, b-caret=B-vector/B. This study presents the general formulation for magnetohydrodynamic (MHD) wave propagation, fire-hose, and mirror instabilities in general Harris-type current sheets. The wave equations are expressed in terms of the four MHD characteristic speeds of fast, intermediate, slow, and cusp waves, and in the local (k ∥ ,k ⊥ ,z) coordinates. Here, k ∥ and k ⊥ are, respectively, to be the wave vector along and perpendicular to the local magnetic field. The parameter regimes for the existence of discrete and resonant modes are identified, which may become unstable at the local fire-hose and mirror instability thresholds. Numerical solutions for discrete eigenmodes are shown for stable and unstable cases. The results have important implications for the anomalous heating and stability of thin current sheets.

Rotational dependence of Fermi-type resonance interactions in molecules

Science.gov (United States)

Mikhailov, Vladimir M.; Smirnov, M. A.

1997-03-01

In Pasadena, (Milliken Lab., USA, 1930) F. Rossetti has observed in Raman spectrum of carbon-dioxide molecule the full symmetric vibration of carbon dioxide appeared as the group of four near lying lines instead of the waited single line. The true interpretation of this enigmatic effect (in that time) was given by E. Fermi -- accidental degeneration of the first excited state of the full symmetric vibration in carbon dioxide. It was the first example of the event observed later in various organic molecules. This event was named as resonance Fermi. The rotational dependence of Fermi type resonance interactions in quasirigid molecules in dominant approximation can be selected in an expansion of the effective vibration-rotation Hamiltonian Hvib- roteff by the operator H(g)(Fermi) equals H30 plus (Sigma) nH3n(g). Let us consider in detail the problem of the construction of the effective vibration-rotational Hamiltonian HVR yields Heff from the point of view of various ordering schemes (grouping) of the vibrational-rotational interactions with sequential analysis of the choice of the convenient grouping adequate to the spectroscopic problem.

Detectability of Neuronal Currents in Human Brain with Magnetic Resonance Spectroscopy.

Energy Technology Data Exchange (ETDEWEB)

Jones, Howland D. T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Thomas, Edward V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Harper, Jason C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mayer, Andrew R. [Mind Research Network, Albuquerque, NM (United States); Univ. of New Mexico, Albuquerque, NM (United States); Caprihan, Arvind [Mind Research Network, Albuquerque, NM (United States); Gasparovic, Charles [Mind Research Network, Albuquerque, NM (United States); Univ. of New Mexico, Albuquerque, NM (United States); Blagoev, Krastan B. [Mind Research Network, Albuquerque, NM (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Haaland, David M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2012-09-01

Magnetic resonance spectroscopy has been used in a high-risk, high-payoff search for neuronal current (NC) signals in the free induction decay (FID) data from the visual cortex of human subjects during visual stimulation. If successful, this approach could make possible the detection of neuronal currents in the brain at high spatial and temporal resolution. Our initial experiments indicated the presence of a statistically significant change in the FID containing the NC relative to FIDs with the NC absent, and this signal was consistent with the presence of NC. Unfortunately, two follow-on experiments were not able to confirm or replicate the positive findings of the first experiment. However, even if the result from the first experiment were evidence of NC in the FID, it is clear that its effect is so small, that a true NC imaging experiment would not be possible with the current instrumentation and experimental protocol used here.

Analytical studies on pump-induced optical resonances in an M-type six-level system

International Nuclear Information System (INIS)

Ghosh, Saswata; Mandal, Swapan

2010-01-01

In the domain of semiclassical formulation and for the Doppler-free atom-field interaction, we construct the optical Bloch equations involving an M-type six-level system coupled to two pump fields and a probe field. The response of the system is probed for different pump-induced transitions in double and triple-resonance situations. In order to obtain the coherent lineshapes (absorptive and dispersive), we use the usual perturbation method for obtaining the approximate analytical solutions to these coupled optical Bloch equations for the density matrix elements. The interferences between the probability amplitudes for different energy levels (dipole allowed and dipole forbidden) are taken care of. For off-resonance pump positions, the linewidths of the three probe transitions are insensitive to the pump Rabi frequencies. On the other hand, the shifts of the three resonance peaks are extremely sensitive to the pump Rabi frequencies. However, for on-resonance pump conditions, the sensitivities of pump Rabi frequencies on the linewidths of the resonance peaks and on the shifts of the resonance peak positions are opposite to those of their off-resonance counterparts. In particular, we have shown the asymmetric and symmetric Rabi splittings under different physical conditions, for non-zero and near-zero probe detuning, respectively. The Rabi splitting under triple-resonance conditions, significantly, modifies the dispersive lineshape at the centre of the absorption line. The two- and three-photon absorptions are also reported for different off-resonant pump positions.

Effect of resonant-to-bulk electron momentum transfer on the efficiency of electron-cyclotron current-drive

International Nuclear Information System (INIS)

Matsuda, Y.; Smith, G.R.; Cohen, R.H.

1989-01-01

Efficiency of current drive by electron cyclotron waves is investigated numerically by a bounce-averaged Fokker-Planck code to ellucidate the effects of momentum transfer from resonant to bulk-electrons, finite bulk temperature relative to the energy of resonant electrons, and trapped electrons. Comparisons are made with existing theories to assess their validity and quantitative difference between theory and code results. Difference of nearly a factor of 2 was found in efficiency between some theory and code results. (author)

A Method for Eddy Current Field Measurement in Permanent Magnet Magnetic Resonance Imaging Systems

Directory of Open Access Journals (Sweden)

SONG Rui

2018-03-01

Full Text Available Magnetic resonance imaging (MRI is a widely used medical imaging technique. In MRI system, gradient magnetic fields are used to code spatial information. However, the fast-switching electric currents in the gradients coils used to generate gradient fields also induce vortex electric field, often referred as eddy current, in the surrounding metal conductors. In this paper, a method for eddy current field measurement was proposed. Based on the Faraday law of electromagnetic induction, an eddy current field measuring device was designed. Combining hardware acquisition and software processing, the eddy current field was obtained by subtracting the ideal gradient field from the magnetic field measured experimentally, whose waveform could be displayed in real time. The proposed method was verified by experimental results.

Self-excited current oscillations in a resonant tunneling diode described by a model based on the Caldeira–Leggett Hamiltonian

International Nuclear Information System (INIS)

Sakurai, Atsunori; Tanimura, Yoshitaka

2014-01-01

The quantum dissipative dynamics of a tunneling process through double barrier structures is investigated on the basis of non-perturbative and non-Markovian treatment. We employ a Caldeira–Leggett Hamiltonian with an effective potential calculated self-consistently, accounting for the electron distribution. With this Hamiltonian, we use the reduced hierarchy equations of motion in the Wigner space representation to study non-Markovian and non-perturbative thermal effects at finite temperature in a rigorous manner. We study current variation in time and the current–voltage (I–V ) relation of the resonant tunneling diode for several widths of the contact region, which consists of doped GaAs. Hysteresis and both single and double plateau-like behavior are observed in the negative differential resistance (NDR) region. While all of the current oscillations decay in time in the NDR region in the case of a strong system–bath coupling, there exist self-excited high-frequency current oscillations in some parts of the plateau in the NDR region in the case of weak coupling. We find that the effective potential in the oscillating case possesses a basin-like form on the emitter side (emitter basin) and that the current oscillation results from tunneling between the emitter basin and the quantum well in the barriers. We find two distinct types of current oscillations, with large and small oscillation amplitudes, respectively. These two types of oscillation appear differently in the Wigner space, with one exhibiting tornado-like motion and the other exhibiting a two piston engine-like motion. (paper)

Resonant converter topologies for constant-current power supplies and their applications

International Nuclear Information System (INIS)

Borage, Mangesh

2013-01-01

Power electronics, in general, and power supplies, in particular, is an important field of accelerator technology due to its widespread use, for instance in dc, ramp or pulse magnet power supplies, high voltage power supplies for electrostatic accelerators and RF amplifies, power supplies for vacuum pumps, vacuum gauges, beam diagnostic devices etc. It has been possible to meet stringent performance requirements with the continuing advancement in the field of power electronics. Resonant converters have been an active area of research in power electronics field due to variety of topologies, diverse, peculiar and useful characteristics. While the majority of the previous work on resonant converters has been directed towards developing methods of analysis and control techniques for the mentioned applications, very little has been done to explore their suitability for application as a constant-current power supply, which is either inherently required or can be advantageously applied in power supplies for various accelerator subsystems and other industrial applications such as electric arc welding, laser diode drivers, magnet illumination systems, battery charging, electrochemical processes etc.

Effect of resonant-to-bulk electron momentum transfer on the efficiency of electron-cyclotron current drive

International Nuclear Information System (INIS)

Matsuda, Y.; Smith, G.R.; Cohen, R.H.

1988-01-01

Efficiency of current drive by electron-cyclotron waves is investigated numerically by a bounce-average Fokker-Planck code to elucidate the effects of momentum transfer from resonant to bulk electrons, finite bulk temperature relative to the energy of resonant electrons, and trapped electrons. Comparisons are made with existing theories to assess their validity and quantitative difference between theory and code results. Difference of nearly a factor of 2 was found in efficiency between some theory and code results. 4 refs., 4 figs

Line shapes of atomic-candle-type Rabi resonances

International Nuclear Information System (INIS)

Coffer, J.G.; Camparo, J.C.; Sickmiller, B.; Presser, A.

2002-01-01

When atoms interact with a phase-modulated field, the probability of finding the atom in the excited-state oscillates at the second harmonic of the modulation frequency, 2ω m . The amplitude of this oscillating probability is a resonant function of the Rabi frequency Ω, and this is termed a β Rabi resonance. In this work, we examine the line shape of the β Rabi resonance both theoretically and experimentally. We find that a small-signal theory of the β-Rabi-resonance condition captures much of the line shape's character, and, in particular, that the resonance's 'line Q' (i.e., 2δΩ 1/2 /Ω) is proportional to the modulation frequency. This result can be applied to the atomic candle, where β Rabi resonances are employed to stabilize field strength. Considering our results in the context of developing an optical atomic candle, we find that a free-running diode laser's intensity noise could be improved by orders of magnitude using the atomic candle concept

Analysis on current limiting characteristics of a transformer type SFCL with two triggering current levels

International Nuclear Information System (INIS)

Lim, Sung-Hun; Ko, Seckcheol; Han, Tae-Hee

2013-01-01

Highlights: ► We suggested the transformer type SFCL with two triggering current levels. ► The short-circuit tests for the suggested SFCL was executed. ► The fault angle as the fault conditions to verify its operation was selected. ► The usefulness of the suggested SFCL was confirmed through the short-circuit test. -- Abstract: In this paper, the transformer type superconducting fault current limiter (SFCL) with two triggering current levels was suggested and its current limiting characteristics were analyzed. The structure of the suggested transformer type SFCL with two triggering current levels largely consists of two parts. One is the transformer with two magnetically coupled coils, which correspond to the primary winding and the secondary one connected with one high-T C superconducting (HTSC) element. The other is third coil, or, another secondary winding with one HTSC element, which is wound on the same iron core together with two coils. This suggested transformer type SFCL can limit the fault current by generating its limiting impedance with two different amplitudes, which are dependent on the initial amplitude of the fault current in case of the fault occurrence. To confirm the usefulness of the proposed SFCL, the current limiting tests of the SFCL according to the fault angle, one of the effective fault conditions to affect the amplitude of the initial fault current, were carried out and its effective limiting operations were discussed

Short-circuit protection of LLC resonant converter using voltages across resonant tank elements

Directory of Open Access Journals (Sweden)

Denys Igorovych Zaikin

2015-06-01

Full Text Available This paper describes two methods for the short-circuit protection of the LLC resonant converter. One of them uses the voltage across the capacitor and the other uses the voltage across the inductor of the resonant tank. These voltages can be processed (integrated or differentiated to recover the resonant tank current. The two circuits illustrated in the described methods make it possible to develop a robust LLC converter design and to avoid using lossy current measurement elements, such as a shunt resistor or current transformer. The methods also allow measuring resonant tank current without breaking high-current paths and connecting the measuring circuit in parallel with the inductor or capacitor of the resonant tank. Practical implementations of these indirect current measurements have been experimentally tested for the short-circuit protection of the 1600 W LLC converter.

Active damping of LLCL-filter resonance based on LC-trap voltage and capacitor current feedback

DEFF Research Database (Denmark)

Huang, Min; Wang, Xiongfei; Loh, Poh Chiang

2015-01-01

. In this paper, different feedback coefficients like the proportional, derivative, integral, high pass and low pass feedback coefficients of the filter capacitor current and the LC-trap circuit voltage are investigated for damping the filter resonance. Active damping methods are analyzed by using the concept...

Current ramp-up experiments in full current drive plasmas in TRIAM-1M

International Nuclear Information System (INIS)

Hanada, K.; Nakamura, K.; Hasegawa, M.; Itoh, S.; Zushi, H.; Sakamoto, M.; Jotaki, E.; Iyomasa, A.; Kawasaki, S.; Nakashima, H.; Yoshida, N.; Tokunaga, K.; Fujiwara, T.; Kulkarni, S.V.; Mitarai, O.

2004-01-01

Four types of plasma current ramp-up experiments in full non-inductively lower hybrid current driven (LHCD) plasmas were executed in TRIAM-1M: (1) current start-up by a combination of electron cyclotron resonance heating (ECRH) and LHCD, (2) tail heating by additional LHCD, (3) bulk heating by ECRH and (4) spontaneous ramp-up by a transition to enhanced current drive (ECD) mode. The time evolutions of plasma current during four types of ramp-up phase were adjusted by a simple model with two different time constants, which are a time defined by the total current diffusion time and a time constant for improving the current drive efficiency. In the case of (1) and (4), the latter time constant is significant during the current ramp-up phase. The improvement in the current drive efficiency in the ECD mode is likely to be caused by the increase in the effective refractive index along the magnetic field of the lower hybrid wave. (author)

Magnetic resonance imaging of the shoulder: Rationale and current applications

International Nuclear Information System (INIS)

Holt, R.G.; Helms, C.A.; Steinbach, L.; Neumann, C.; Munk, P.L.; Genant, H.K.

1990-01-01

Because it can demonstrate a wide range of tissue contrast with excellent resolution, magnetic resonance (MR) imaging has revolutionized imaging in many areas of the musculoskeletal system and has generated excitement among those interested in the painful shoulder. Shoulder impingement syndrome and glenohumeral instability constitute the two major categories of shoulder derangements. Correct diagnosis requires the use of appropriate pulse sequences and imaging planes, proper patient positioning, and a satisfactory surface coil. In addition the imager must have a thorough understanding of shoulder anatomy and pathology. We present a summary of the current status of MR imaging of the shoulder including technical, anatomic, and pathologic considerations and a review of the pertinent literature. (orig.)

Identification of anomalous Doppler resonance effect during current ramp down in HT-7 tokamak

Energy Technology Data Exchange (ETDEWEB)

Li Erzhong, E-mail: rzhonglee@ipp.ac.c [Institute of Plasma Physics, Chinese Academy of Science, Hefei 230031 (China); Hu Liqun; Ling Bili; Liu Yong; Ti Ang; Zhou Reijie; Lu Hongwei; Gao Xiang [Institute of Plasma Physics, Chinese Academy of Science, Hefei 230031 (China)

2010-09-21

The abrupt steep jump of electron cyclotron emission (ECE) signals during current ramp-down has been observed and explained by an anomalous Doppler resonance effect (ADR). The identifying process of ADR was presented based on the fast Fourier transform (FFT) technique. The threshold value for triggering a steep jump on ECE signals has been identified under different discharge conditions.

Grid-Current-Feedback Active Damping for LCL Resonance in Grid-Connected Voltage-Source Converters

DEFF Research Database (Denmark)

Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

2016-01-01

This paper investigates active damping of LCL-filter resonance in a grid-connected voltage-source converter with only grid-current feedback control. Basic analysis in the s-domain shows that the proposed damping technique with a negative high-pass filter along its damping path is equivalent...... of phase-lag, in turn, helps to shrink the region of nonminimum-phase behavior caused by negative virtual resistance inserted unintentionally by most digitally implemented active damping techniques. The presented high-pass-filtered active damping technique with a single grid-current feedback loop is thus...

Rare earth doped M-type hexaferrites; ferromagnetic resonance and magnetization dynamics

Directory of Open Access Journals (Sweden)

Vipul Sharma

2018-05-01

Full Text Available M-type hexagonal barium ferrites come in the category of magnetic material that plays a key role in electromagnetic wave propagation in various microwave devices. Due to their large magnetic anisotropy and large magnetization, their operating frequency exceeds above 50 GHz. Doping is a way to vary its magnetic properties to such an extent that its ferromagnetic resonance (FMR response can be tuned over a broad frequency band. We have done a complete FMR study of rare earth elements neodymium (Nd and samarium (Sm, with cobalt (Co as base, doped hexaferrite nanoparticles (NPs. X-ray diffractometry, vibrating sample magnetometer (VSM, and ferromagnetic resonance (FMR techniques were used to characterize the microstructure and magnetic properties of doped hexaferrite nanoparticles. Using proper theoretical electromagnetic models, various parameters are extracted from FMR data which play important role in designing and fabricating high-frequency microwave devices.

Autonomous control of inverter-interfaced Distributed Generation units for harmonic current filtering and resonance damping in an islanded microgrid

DEFF Research Database (Denmark)

Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

2012-01-01

Harmonic current filtering and resonance damping have become important concerns on the control of an islanded microgrids. To address these challenges, this paper proposes a control method of inverter-interfaced Distributed Generation (DG) units, which can autonomously share harmonic currents and ...

Dating by electron paramagnetic resonance

International Nuclear Information System (INIS)

Poupeau, G.; Rossi, A.M.

1984-01-01

Some natural materials behave like dosimeters in front of the ionizing particle flux coming from environmental radioactivity and the cosmic radiation. This property is used for the dating by Electron Paramagnetic Resonance (EPR). Before presenting the basic principles of the EPR analysis and the dating method which uses such a phenomenous, it is reviewed several types of application currently in course of development. (L.C.) [pt

Current-type flipped-Γ-source inverters

DEFF Research Database (Denmark)

Loh, Poh Chiang; Li, Ding; Blaabjerg, Frede

2012-01-01

are of interest since they use lesser components. Their winding turns might however become too excessive for higher demanded gains. Avoiding this usual trend, a new family of current-type flipped-Γ-source inverters are proposed, whose common gain is raised by lowering, and not increasing, the winding turns...

Low-Cost Digital Implementation of Proportional-Resonant Current Controllers for PV Inverter Applications Using Delta Operator

DEFF Research Database (Denmark)

Sera, Dezso; Kerekes, Tamas; Lungeanu, Marian

2005-01-01

the possibility of selective harmonic compensation. However, in case of digital implementation on a low-cost fixedpoint DSP, the limited computational power and the limited numerical representation precision can restrict the utilization of it. The present paper proposes a different way of digital implementation...... of the P+Resonant controller with selective harmonic compensation on a low-cost fixed-point DSP. The resonant part of the P+R has been implemented as a second order filter based on Delta operator. The current controller, together with harmonic compensation for the 3rd, 5th, and 7th harmonics has been...

Experimental characterization of cantilever-type piezoelectric generator operating at resonance for vibration energy harvesting

Energy Technology Data Exchange (ETDEWEB)

Montanini, Roberto, E-mail: rmontanini@unime.it; Quattrocchi, Antonino, E-mail: aquattrocchi@unime.it [University of Messina, Dept. of Engineering, Contrada di Dio, Messina (Italy)

2016-06-28

A cantilever-type resonant piezoelectric generator (RPG) has been designed by gluing a PZT patch working in d{sub 31} mode onto a glass fibre reinforced composite cantilever beam with a discrete mass applied on its free end. The electrical and dynamic behaviour of the RPG prototype has been investigated by carrying out laboratory tests aimed to assess the effect of definite design parameters, specifically the electric resistance load and the excitation frequency. Results showed that an optimum resistance load exists, at which power generation is maximized. Moreover, it has been showed that power generation is strongly influenced by the vibration frequency highlighting that, at resonance, output power can be increased by more than one order of magnitude. Possible applications include inertial resonant harvester for energy recovery from vibrating machines, sea waves or wind flux and self-powering of wireless sensor nodes.

Shale characteristics impact on Nuclear Magnetic Resonance (NMR fluid typing methods and correlations

Directory of Open Access Journals (Sweden)

Mohamed Mehana

2016-06-01

Full Text Available The development of shale reservoirs has brought a paradigm shift in the worldwide energy equation. This entails developing robust techniques to properly evaluate and unlock the potential of those reservoirs. The application of Nuclear Magnetic Resonance techniques in fluid typing and properties estimation is well-developed in conventional reservoirs. However, Shale reservoirs characteristics like pore size, organic matter, clay content, wettability, adsorption, and mineralogy would limit the applicability of the used interpretation methods and correlation. Some of these limitations include the inapplicability of the controlling equations that were derived assuming fast relaxation regime, the overlap of different fluids peaks and the lack of robust correlation to estimate fluid properties in shale. This study presents a state-of-the-art review of the main contributions presented on fluid typing methods and correlations in both experimental and theoretical side. The study involves Dual Tw, Dual Te, and doping agent's application, T1-T2, D-T2 and T2sec vs. T1/T2 methods. In addition, fluid properties estimation such as density, viscosity and the gas-oil ratio is discussed. This study investigates the applicability of these methods along with a study of the current fluid properties correlations and their limitations. Moreover, it recommends the appropriate method and correlation which are capable of tackling shale heterogeneity.

Meta-metallic coils and resonators: Methods for high Q-value resonant geometries

Energy Technology Data Exchange (ETDEWEB)

Mett, R. R. [Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 (United States); Department of Physics and Chemistry, Milwaukee School of Engineering, Milwaukee, Wisconsin 53202 (United States); Sidabras, J. W.; Hyde, J. S. [Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 (United States)

2016-08-15

A novel method of decreasing ohmic losses and increasing Q-value in metallic resonators at high frequencies is presented. The method overcomes the skin-depth limitation of rf current flow cross section. The method uses layers of conductive foil of thickness less than a skin depth and capacitive gaps between layers. The capacitive gaps can substantially equalize the rf current flowing in each layer, resulting in a total cross-sectional dimension for rf current flow many times larger than a skin depth. Analytic theory and finite-element simulations indicate that, for a variety of structures, the Q-value enhancement over a single thick conductor approaches the ratio of total conductor thickness to skin depth if the total number of layers is greater than one-third the square of the ratio of total conductor thickness to skin depth. The layer number requirement is due to counter-currents in each foil layer caused by the surrounding rf magnetic fields. We call structures that exhibit this type of Q-enhancement “meta-metallic.” In addition, end effects due to rf magnetic fields wrapping around the ends of the foils can substantially reduce the Q-value for some classes of structures. Foil structures with Q-values that are substantially influenced by such end effects are discussed as are five classes of structures that are not. We focus particularly on 400 MHz, which is the resonant frequency of protons at 9.4 T. Simulations at 400 MHz are shown with comparison to measurements on fabricated structures. The methods and geometries described here are general for magnetic resonance and can be used at frequencies much higher than 400 MHz.

Analysis of Current-mode Detectors For Resonance Detection In Neutron Optics Time Reversal Symmetry Experiment

Science.gov (United States)

Forbes, Grant; Noptrex Collaboration

2017-09-01

One of the most promising explanations for the observed matter-antimatter asymmetry in our universe is the search for new sources of time-reversal (T) symmetry violation. The current amount of violation seen in the kaon and B-meson systems is not sufficient to describe this asymmetry. The Neutron Optics Time Reversal Experiment Collaboration (NOPTREX) is a null test for T violation in polarized neutron transmission through a polarized 139La target. Due to the high neutron flux needed for this experiment, as well as the ability to effectively subtract background noise, a current-mode neutron detector that can resolve resonances at epithermal energies has been proposed. In order to ascertain if this detector design would meet the requirements for the eventual NOPTREX experiment, prototypical detectors were tested at the NOBORU beam at the Japan Proton Accelerator Research Complex (JPARC) facility. Resonances in In and Ta were measured and the collected data was analyzed. This presentation will describe the analysis process and the efficacy of the detectors will be discussed. Department of Energy under Contract DE-SC0008107, UGRAS Scholarship.

Magnetic resonance imaging inside cylindrical metal containers with an eddy current self-compensated method

International Nuclear Information System (INIS)

Han, Hui; Balcom, Bruce J

2011-01-01

Magnetic resonance imaging (MRI) measurements inside cylindrical metal structures have recently been proposed and form the basis for new high-pressure MRI studies. The critical problem for MRI inside cylindrical metal structures is significant eddy currents induced by the switched magnetic field gradients, which usually corrupt spatial and motion encoding without appropriate correction. In this work a so-called standard SPRITE (single point ramped imaging with T 1 enhancement) technique is applied for imaging inside cylindrical metal structures. We show that the standard SPRITE technique is fundamentally immune to large-scale eddy current effects and yields artifact-free high-quality images with no eddy current correction required. Standard SPRITE image acquisition avoids the complications involved in the measurement and compensation of eddy current effects for MRI with cylindrical metal structures. This work is a substantial advance toward the extension of MRI to new challenging systems, which are of practical importance

Dynamic Evaluation of LCL-type Grid-Connected Inverters with Different Current Feedback Control Schemes

DEFF Research Database (Denmark)

Han, Yang; Li, Zipeng; Guerrero, Josep M.

2015-01-01

typical current feedback control schemes in LCL grid-connected system are analyzed and compared systematically. Analysis in s-domain take the effect of the digital computation and modulation delay into account. The stability analysis is presented by root locus in the discrete domain, the optimal values......Proportional-resonant (PR) compensator and LCL filter becomes a better choice in grid-connected inverter system with high performance and low costs. However, the resonance phenomenon caused by LCL filter affect the system stability significantly. In this paper, the stability problem of three...

Magnetic forces and localized resonances in electron transfer through quantum rings.

Science.gov (United States)

Poniedziałek, M R; Szafran, B

2010-11-24

We study the current flow through semiconductor quantum rings. In high magnetic fields the current is usually injected into the arm of the ring preferred by classical magnetic forces. However, for narrow magnetic field intervals that appear periodically on the magnetic field scale the current is injected into the other arm of the ring. We indicate that the appearance of the anomalous-non-classical-current circulation results from Fano interference involving localized resonant states. The identification of the Fano interference is based on the comparison of the solution of the scattering problem with the results of the stabilization method. The latter employs the bound-state type calculations and allows us to extract both the energy of metastable states localized within the ring and the width of resonances by analysis of the energy spectrum of a finite size system as a function of its length. The Fano resonances involving states of anomalous current circulation become extremely narrow on both the magnetic field and energy scales. This is consistent with the orientation of the Lorentz force that tends to keep the electron within the ring and thus increases the lifetime of the electron localization within the ring. Absence of periodic Fano resonances in electron transfer probability through a quantum ring containing an elastic scatterer is also explained.

Cerebral magnetic resonance in-patient with metallic staple, yasargil type for hemostasia of intracranial aneurysm

International Nuclear Information System (INIS)

Morillo, Anibal

1993-01-01

Report of a case of magnetic resonance (MR) of the brain; done without complications in a patient with a yasargil intracranial aneurysm clip. The risks and precautions necessary for the performance of MR examinations in this type of patients are discussed

Magnetic resonance annual 1986

International Nuclear Information System (INIS)

Kressel, H.Y.

1986-01-01

This book contains papers written on magnetic resonance during 1986. Topics include: musculosketetal magnetic resonance imaging; imaging of the spine; magnetic resonance chemical shift imaging; magnetic resonance imaging in the central nervous system; comparison to computed tomography; high resolution magnetic resonance imaging using surface coils; magnetic resonance imaging of the chest; magnetic resonance imaging of the breast; magnetic resonance imaging of the liver; magnetic resonance spectroscopy of neoplasms; blood flow effects in magnetic resonance imaging; and current and potential applications of clinical sodium magnetic resonance imaging

Resonant two-photon absorption and electromagnetically induced transparency in open ladder-type atomic system.

Science.gov (United States)

Moon, Han Seb; Noh, Heung-Ryoul

2013-03-25

We have experimentally and theoretically studied resonant two-photon absorption (TPA) and electromagnetically induced transparency (EIT) in the open ladder-type atomic system of the 5S(1/2) (F = 1)-5P(3/2) (F' = 0, 1, 2)-5D(5/2) (F″ = 1, 2, 3) transitions in (87)Rb atoms. As the coupling laser intensity was increased, the resonant TPA was transformed to EIT for the 5S(1/2) (F = 1)-5P(3/2) (F' = 2)-5D(5/2) (F″ = 3) transition. The transformation of resonant TPA into EIT was numerically calculated for various coupling laser intensities, considering all the degenerate magnetic sublevels of the 5S(1/2)-5P(3/2)-5D(5/2) transition. From the numerical results, the crossover from TPA to EIT could be understood by the decomposition of the spectrum into an EIT component owing to the pure two-photon coherence and a TPA component caused by the mixed term.

Investigation of resonant Raman scattering in type II GaAs/AlAs superlattices

International Nuclear Information System (INIS)

Choi, H.

2001-01-01

As a consequence of the band alignment in GaAs/AIAs superlattices (SLs) and the indirect nature of bulk AIAs, quantum confinement can be used to engineer a Type II system. This produces an electron population in the AIAs longitudinal (X z ) or transverse (X xy ) zone-edge states, which is separated in both direct and reciprocal space from the hole population in the GaAs zone-centre (Γ) states. This thesis is an investigation of the electronic and vibrational structure of Type II GaAs/AIAs SLs using theoretical models and spectroscopic techniques, with special emphasis on Type II resonant Raman (RR) scattering. The majority of this thesis concerns short-period GaAs/AIAs SLs with X z as the lowest conduction band state. A model of the SL electronic band structure is presented, including the effects of interband Γ-X z mixing and the X-point camel's back structure. Interband mixing makes Γ-X z radiative transitions observable in photoluminescence (PL) and RR experiments. Phonon-assisted transitions from the X z state are also observed in PL experiments. Several of the participating phonon modes are unambiguously identified, in good agreement with recent reports. This thesis presents the first detailed experimental and theoretical study of Type II RR scattering from the incoming channel of the X z -related Type II bandgap. The X z - related Type II incoming RR spectra in the GaAs optic phonon region are compared with the Γ-related Type I outgoing RR spectra within several theoretical models. Thereby, the mechanisms of the Type II RR scattering, the origins of the RR lineshape and the polarisation dependence, are fully explained, clarifying the spectral features observed in the GaAs zone-centre optic phonon region. The Type II resonance also allows the observation of zone boundary (X-point) phonons from intervalley (IV) scattering. A model of the IV electron-phonon interaction involving X conduction band electrons and zone boundary phonons in Type II SLs is presented

On the Variability of Wilson Currents by Storm Type and Phase

Science.gov (United States)

Deierling, Wiebke; Kalb, Christina; Mach, Douglas; Liu, Chuntao; Peterson, Michael; Blakeslee, Richard

2014-01-01

Storm total conduction currents from electrified clouds are thought to play a major role in maintaining the potential difference between the earth's surface and the upper atmosphere within the Global Electric Circuit (GEC). However, it is not entirely known how the contributions of these currents vary by cloud type and phase of the clouds life cycle. Estimates of storm total conduction currents were obtained from data collected over two decades during multiple field campaigns involving the NASA ER-2 aircraft. In this study the variability of these currents by cloud type and lifecycle is investigated. We also compared radar derived microphysical storm properties with total storm currents to investigate whether these storm properties can be used to describe the current variability of different electrified clouds. The ultimate goal is to help improve modeling of the GEC via quantification and improved parameterization of the conduction current contribution of different cloud types.

Resonant enhancement of band-to-band tunneling in in-plane MoS2/WS2 heterojunctions

Science.gov (United States)

Kuroda, Tatsuya; Mori, Nobuya

2018-04-01

The band-to-band (BTB) tunneling current J through in-plane MoS2/WS2 heterojunctions is calculated by the nonequilibrium Green function method combined with tight-binding approximation. Types A and B of band configurations are considered. For type-A (type-B) heterojunctions, a potential notch exists (or is absent) at the heterointerface. Both type-A and type-B MoS2/WS2 heterojunctions can support a higher BTB current than MoS2 and WS2 homojunctions. For type-A heterojunctions, the resonant enhancement of J occurs resulting in a significantly higher BTB tunneling current.

Magnetic hysteresis effects in superconducting coplanar microwave resonators

Energy Technology Data Exchange (ETDEWEB)

Bothner, D.; Gaber, T.; Kemmler, M.; Gruenzweig, M.; Ferdinand, B.; Koelle, D.; Kleiner, R. [Universitaet Tuebingen (Germany); Wuensch, S.; Siegel, M. [Karlsruher Institut fuer Technologie (Germany); Mikheenko, P.; Johansen, T.H. [University of Oslo (Norway)

2013-07-01

We present experimental data regarding the impact of external magnetic fields on quality factor and resonance frequency of superconducting microwave resonators in a coplanar waveguide geometry. In particular we focus on the influence of magnetic history and show with the assistance of numerical calculations that the found hysteretic behaviour can be well understood with a highly inhomogeneous microwave current density in combination with established field penetration models for type-II superconducting thin films. Furthermore we have used magneto-optical imaging techniques to check the field distribution which we have assumed in our calculations. Finally, we demonstrate that and how the observed hysteretic behaviour can be used to optimize and tune the resonator performance for possible hybrid quantum sytems in magnetic fields.

Voltage current characteristics of type III superconductors

International Nuclear Information System (INIS)

Dorofejev, G.L.; Imenitov, A.B.; Klimenko, E.Y.

1980-01-01

An adequate description of voltage-current characteristics is important in order to understand the nature of high critical current for the electrodynamic construction of type-III superconductors and for commercial superconductor specification. Homogeneous monofilament and multifilament Nb-Ti, Nb-Zr,Nb 3 Sn wires were investigated in different ranges of magnetic field, temperature and current. The shape of the voltage-current characteristics of multifilament wires, and the parameter's dependence on temperature and magnetic field may be explained qualitatively by the longitudinal heterogeneous nature of the filaments. A method of attaining the complete specification of the wire's electro-physical properties is proposed. It includes the traditional description of a critical surface (i.e. the surface corresponding to a certain conventional effective resistivity in T,B,J-space) and a description of any increasing parameter that depends on B and T. (author)

Voltage current characteristics of type III superconductors

Energy Technology Data Exchange (ETDEWEB)

Dorofeiev, G L; Imenitov, A B; Klimenko, E Y [Gosudarstvennyi Komitet po Ispol' zovaniyu Atomnoi Ehnergii SSSR, Moscow. Inst. Atomnoi Ehnergii

1980-06-01

An adequate description of voltage-current characteristics is important in order to understand the nature of high critical current for the electrodynamic construction of type-III superconductors and for commercial superconductor specification. Homogeneous monofilament and multifilament Nb-Ti, Nb-Zr,Nb/sub 3/Sn wires were investigated in different ranges of magnetic field, temperature and current. The shape of the voltage-current characteristics of multifilament wires, and the parameter's dependence on temperature and magnetic field may be explained qualitatively by the longitudinal heterogeneous nature of the filaments. A method of attaining the complete specification of the wire's electro-physical properties is proposed. It includes the traditional description of a critical surface (i.e. the surface corresponding to a certain conventional effective resistivity in T,B,J-space) and a description of any increasing parameter that depends on B and T.

Spin resonance in the new-structure-type iron-based superconductor CaKFe4As4

International Nuclear Information System (INIS)

Iida, Kazuki; Ishikado, Motoyuki; Nagai, Yuki; Yoshida, Hiroyuki; Christianson, Andrew D.; Murai, Naoki; Kawashima, Kenji; Yoshida, Yoshiyuki; Eisaki, Hiroshi; Iyo, Akira

2017-01-01

The dynamical spin susceptibility in the new-structure-type iron-based superconductor CaKFe 4 As 4 was investigated by using a combination of inelastic neutron scattering (INS) measurements and random phase approximation (RPA) calculations. Powder INS measurements show that the spin resonance at Q res = 1.17(1) Å -1 , corresponding to the (π, π) nesting wave vector in tetragonal notation, evolves below T c . The characteristic energy of the spin resonance E res = 12.5 meV is smaller than twice the size of the superconducting gap (2Δ). The broad energy feature of the dynamical susceptibility of the spin resonance can be explained by the RPA calculations, in which the different superconducting gaps on different Fermi surfaces are taken into account. Our INS and PRA studies demonstrate that the superconducting pairing nature in CaKFe 4 As 4 is the s ± symmetry. (author)

Magnetic resonance imaging of breast implants.

Science.gov (United States)

Shah, Mala; Tanna, Neil; Margolies, Laurie

2014-12-01

Silicone breast implants have significantly evolved since their introduction half a century ago, yet implant rupture remains a common and expected complication, especially in patients with earlier-generation implants. Magnetic resonance imaging is the primary modality for assessing the integrity of silicone implants and has excellent sensitivity and specificity, and the Food and Drug Administration currently recommends periodic magnetic resonance imaging screening for silent silicone breast implant rupture. Familiarity with the types of silicone implants and potential complications is essential for the radiologist. Signs of intracapsular rupture include the noose, droplet, subcapsular line, and linguine signs. Signs of extracapsular rupture include herniation of silicone with a capsular defect and extruded silicone material. Specific sequences including water and silicone suppression are essential for distinguishing rupture from other pathologies and artifacts. Magnetic resonance imaging provides valuable information about the integrity of silicone implants and associated complications.

Acute stroke magnetic resonance imaging: current status and future perspective

International Nuclear Information System (INIS)

Kloska, Stephan P.; Wintermark, Max; Engelhorn, Tobias; Fiebach, Jochen B.

2010-01-01

Cerebral stroke is one of the most frequent causes of permanent disability or death in the western world and a major burden in healthcare system. The major portion is caused by acute ischemia due to cerebral artery occlusion by a clot. The minority of strokes is related to intracerebral hemorrhage or other sources. To limit the permanent disability in ischemic stroke patients resulting from irreversible infarction of ischemic brain tissue, major efforts were made in the last decade. To extend the time window for thrombolysis, which is the only approved therapy, several imaging parameters in computed tomography and magnetic resonance imaging (MRI) have been investigated. However, the current guidelines neglect the fact that the portion of potentially salvageable ischemic tissue (penumbra) is not dependent on the time window but the individual collateral blood flow. Within the last years, the differentiation of infarct core and penumbra with MRI using diffusion-weighted images (DWI) and perfusion imaging (PI) with parameter maps was established. Current trials transform these technical advances to a redefined patient selection based on physiological parameters determined by MRI. This review article presents the current status of MRI for acute stroke imaging. A special focus is the ischemic stroke. In dependence on the pathophysiology of cerebral ischemia, the basic principle and diagnostic value of different MRI sequences are illustrated. MRI techniques for imaging of the main differential diagnoses of ischemic stroke are mentioned. Moreover, perspectives of MRI for imaging-based acute stroke treatment as well as monitoring of restorative stroke therapy from recent trials are discussed. (orig.)

Synchrobetatron resonances

International Nuclear Information System (INIS)

1977-03-01

At the 1975 Particle Accelerator Conference it was reported that a class of resonances were observed in SPEAR II that had not appeared before in SPEAR I. While the existence of sideband resonances of the main betatron oscillation frequencies has been previously observed and analyzed, the resonances observed in SPEAR do not appear to be of the same variety. Experiments were performed at SPEAR to identify the mechanism believed to be the most likely explanation. Some of the current experimental knowledge and theoretical views on the source of these resonances are presented

CMOS compatible fabrication process of MEMS resonator for timing reference and sensing application

Science.gov (United States)

Huynh, Duc H.; Nguyen, Phuong D.; Nguyen, Thanh C.; Skafidas, Stan; Evans, Robin

2015-12-01

Frequency reference and timing control devices are ubiquitous in electronic applications. There is at least one resonator required for each of this device. Currently electromechanical resonators such as crystal resonator, ceramic resonator are the ultimate choices. This tendency will probably keep going for many more years. However, current market demands for small size, low power consumption, cheap and reliable products, has divulged many limitations of this type of resonators. They cannot be integrated into standard CMOS (Complement metaloxide- semiconductor) IC (Integrated Circuit) due to material and fabrication process incompatibility. Currently, these devices are off-chip and they require external circuitries to interface with the ICs. This configuration significantly increases the overall size and cost of the entire electronic system. In addition, extra external connection, especially at high frequency, will potentially create negative impacts on the performance of the entire system due to signal degradation and parasitic effects. Furthermore, due to off-chip packaging nature, these devices are quite expensive, particularly for high frequency and high quality factor devices. To address these issues, researchers have been intensively studying on an alternative for type of resonator by utilizing the new emerging MEMS (Micro-electro-mechanical systems) technology. Recent progress in this field has demonstrated a MEMS resonator with resonant frequency of 2.97 GHz and quality factor (measured in vacuum) of 42900. Despite this great achievement, this prototype is still far from being fully integrated into CMOS system due to incompatibility in fabrication process and its high series motional impedance. On the other hand, fully integrated MEMS resonator had been demonstrated but at lower frequency and quality factor. We propose a design and fabrication process for a low cost, high frequency and a high quality MEMS resonator, which can be integrated into a standard

Resonant tunneling with high peak to valley current ratio in SiO2/nc-Si/SiO2 multi-layers at room temperature

International Nuclear Information System (INIS)

Chen, D. Y.; Sun, Y.; He, Y. J.; Xu, L.; Xu, J.

2014-01-01

We have investigated carrier transport in SiO 2 /nc-Si/SiO 2 multi-layers by room temperature current-voltage measurements. Resonant tunneling signatures accompanied by current peaks are observed. Carrier transport in the multi-layers were analyzed by plots of ln(I/V 2 ) as a function of 1/V and ln(I) as a function of V 1/2 . Results suggest that besides films quality, nc-Si and barrier sub-layer thicknesses are important parameters that restrict carrier transport. When thicknesses are both small, direct tunneling dominates carrier transport, resonant tunneling occurs only at certain voltages and multi-resonant tunneling related current peaks can be observed but with peak to valley current ratio (PVCR) values smaller than 1.5. When barrier thickness is increased, trap-related and even high field related tunneling is excited, causing that multi-current peaks cannot be observed clearly, only one current peak with higher PVCR value of 7.7 can be observed. While if the thickness of nc-Si is large enough, quantum confinement is not so strong, a broad current peak with PVCR value as high as 60 can be measured, which may be due to small energy difference between the splitting energy levels in the quantum dots of nc-Si. Size distribution in a wide range may cause un-controllability of the peak voltages

Resonant Mode Reduction in Radiofrequency Volume Coils for Ultrahigh Field Magnetic Resonance Imaging

Directory of Open Access Journals (Sweden)

Xiaoliang Zhang

2011-07-01

Full Text Available In a multimodal volume coil, only one mode can generate homogeneous Radiofrequency (RF field for Magnetic Resonance Imaging. The existence of other modes may increase the volume coil design difficulties and potentially decreases coil performance. In this study, we introduce common-mode resonator technique to high and ultrahigh field volume coil designs to reduce the resonant mode while maintain the homogeneity of the RF field. To investigate the design method, the common-mode resonator was realized by using a microstrip line which was split along the central to become a pair of parallel transmission lines within which common-mode currents exist. Eight common-mode resonators were placed equidistantly along the circumference of a low loss dielectric cylinder to form a volume coil. Theoretical analysis and comparison between the 16-strut common-mode volume coil and a conventional 16-strut volume coil in terms of RF field homogeneity and efficiency was performed using Finite-Difference Time-Domain (FDTD method at 298.2 MHz. MR imaging experiments were performed by using a prototype of the common-mode volume coil on a whole body 7 Tesla scanner. FDTD simulation results showed the reduced number of resonant modes of the common-mode volume coil over the conventional volume coil, while the RF field homogeneity of the two type volume coils was kept at the same level. MR imaging of a water phantom and a kiwi fruit showing the feasibility of the proposed method for simplifying the volume coil design is also presented.

Sulfonylureas in type 2 diabetes mellitus: current evidence, conflicts ...

African Journals Online (AJOL)

Introduction: We sought to explore the current state of evidence on sulfonylurea therapy in type 2 diabetes mellitus (T2DM) and critically examine the recommendations of major practice guidelines,and the overall ramifications of the issues thereof in current clinical practice. Method: We searched PUBMED, MEDLINE and ...

Angular correlation experiments for the study of giant multipole resonances and currents of the second kind in atomic nuclei

International Nuclear Information System (INIS)

1986-03-01

The project dealt with angular correlation experiments for the study of giant multipole resonances and currents of the second kind in atomic nuclei. Both partial projects were worked in the period of the report. (orig.) [de

Impact of neutron resonance treatments on reactor calculation

International Nuclear Information System (INIS)

Leszczynski, F.

1988-01-01

The neutron resonance treatment on reactor calculation is one of the not completely resolved problems of reactor theory. The calculation required on design, fuel management and accident analysis of nuclear reactors contains adjust coefficients and semi-empirical values introduced on the computer codes; these values are obtained comparing calculation results with experimental values and more exact calculation results. This is made when the characteristics of the analyzed system are such that this type of comparisons are possible. The impact that one fixed resonance treatment method have on the final evaluation of physics reactor parameters, reactivity, power distribution, etc., is useful to know. In this work, the differences between calculated parameters with two different methods of resonance treatment in cell calculations are shown. It is concluded that improvements on resonance treatment are necessary for growing the reliability on core calculations results. Finally, possible improvements, easy to implement in current computer codes, are presented. (Author) [es

Isoscalar giant resonances

Energy Technology Data Exchange (ETDEWEB)

Youngblood, D. H. [Texas A and M Univ., College Station (USA). Cyclotron Inst.; Ikegami, H.; Muraoka, M. [eds.

1980-01-01

The current status of the knowledges of giant quadrupole resonance (GQR), low energy octupole resonance (LEOR), and giant monopole resonance (GMR), is described. In the lowest order of multipole resonance, both isoscalar and isovector modes can occur. The characteristics of the GQR in light nuclei are apparent in the experimental result for Mg-24. All of the isoscalar E2 strength are known in Mg-24. The Goldhaber-Teller model is preferred over the Steinwedel-Jensen model for the giant dipole resonance (GDR) transition density. A few interesting and puzzling features have been seen in Pb-208. There is some conflict between inelastic alpha and electron scatterings. About LEOR, the RPA calculation of Liu and Brown was compared to the data for 3/sup -/ strength in Ca-40, Zr-90 and Pb-208. The calculation was employed the residual interaction of the Skyrme type. The agreement in Zr-90 was excellent. The effect of quadrupole deformation on the LEOR in Sm isotopes was large. The inelastic alpha scattering data on Al-27, Ca-40, Ti-48, Ni-58, Zn-64 and 66, Zr-90, Sn-116, 118, 120 and 124, Sm-144, 148 and 154, and Pb-208 were utilized in order to identify the GMR, and the GMR parameters were obtained. The GMR exhausting a large fraction of the sum rule was apparent in the nuclei with mass larger than 90. The splitting of the GDR and the broadening of the GQR in permanently deformed nuclei were established. The splitting of GMR was seen in Sm-154. The studies with heavy ions are also described.

Flux-lock type of superconducting fault current limiters: A comprehensive review

Science.gov (United States)

Badakhshan, M.; Mousavi G., S. M.

2018-04-01

Power systems must be developed and extended to supply the continuous enhancement of demands for electrical energy. This development of systems in addition to the integration of distributed generation (DG) units to the power systems results higher capacity of system. Hence, short circuit current of network is confronted with persistent increasing. Since exploration of high temperature superconducting (HTS) materials, superconducting fault current limiters (SFCLs) have attracted a lot of attention all over the world. There are different types of SFCLs. Flux-lock type of SFCL because of its characteristics in fault current limitation is an important category of SFCLs. This paper aims to present a comprehensive review of research activities and applications of Flux-lock type of SFCLs in power systems.

Theoretical implications of the resonance anomalies in the e+-e- system

International Nuclear Information System (INIS)

Pakvasa, S.; Rajasekaran, G.; Tuan, S.F.

1975-01-01

The phenomenological properties of the recent resonance anomalies at 3.1 GeV and 3.7 GeV in e + -e - systems are confronted in a fairly systematic way with models presently known to us. These include charm-related models, neutral-intermediate-boson-type hypotheses, gauge-related models, and exotic suggestions that the resonant states may have abnormal C parity or that the electromagnetic current has a color triplet piece. We conclude that none of the schemes proposed represents a really satisfactory interpretation of the data

A Stochastic Proof of the Resonant Scattering Kernel and its Applications for Gen IV Reactors Type

International Nuclear Information System (INIS)

Becker, B.; Dagan, R.; Broeders, C.H.M.; Lohnert, G.

2008-01-01

Monte Carlo codes such as MCNP are widely accepted as almost-reference for reactor analysis. The Monte Carlo Code should therefore use as few as possible approximations in order to produce 'experimental-level' calculations. In this study we deal with one of the most problematic approximations done in MCNP in which the resonances are ignored for the secondary neutron energy distribution, namely the change of the energy and angular direction of the neutron after interaction with a heavy isotope with pronounced resonances. The endeavour of exploiting the influence of the resonances on the scattering kernel goes back to 1944 where E. Wigner and J. Wilkins developed the first temperature dependent scattering kernel. However only in 1998, the full analytical solution for the double differential resonant dependent scattering kernel was suggested by W. Rothenstein and R. Dagan. An independent stochastic approach is presented for the first time to confirm the above analytical kernel with a complete different methodology. Moreover, by manipulating in a subtle manner the scattering subroutine COLIDN of MCNP, it is proven that this very subroutine is, to some extent, inappropriate as well as the relevant explanation in the MCNP manual. The impact of this improved resonance dependent scattering kernel on diverse types of reactors, in particular for the Generation IV innovative core design HTR, is shown to be significant. (authors)

Recovery characteristics of flux-lock type superconducting fault current limiter

International Nuclear Information System (INIS)

Han, T.H.; Choi, H.S.; Lim, S.H.; Lee, N.Y.

2007-01-01

The flux-lock type superconducting fault current limiter (SFCL) has attractive characteristics that the current limiting level can be adjusted by a winding direction and the inductance ratio between two coils. We changed the winding direction and the number of coils to compare the resistive type SFCL with the flux-lock type SFCL. The initial limiting current (I ini ) and quench characteristic were dependent on the winding direction and the inductance ratio of two coils. As a winding number was increased from 21 to 42, I ini and quench characteristic were proportionally increased. In additive polarity winding, I ini was 10.2 A and the quench time (T q ) was 0.53 ms, which was faster than that of a subtractive polarity winding. The consumed energy and recovery characteristics in a superconducting element showed the same tendency. Recovery characteristics in the flux-lock type SFCL were dependent on the consumed energy of a superconducting element. The recovery time was related to a heat energy and it was represented as the consuming time of the heat energy. As the heat energy was shown in H 0.24I 2 Rt, the recovery time was shortened in the following order: a subtractive polarity winding, a resistive type and an additive polarity winding. It was known that the recovery time was proportional to a consumed energy of a superconducting element

Enhanced absorption in Au nanoparticles/a-Si:H/c-Si heterojunction solar cells exploiting Au surface plasmon resonance

Energy Technology Data Exchange (ETDEWEB)

Losurdo, Maria; Giangregorio, Maria M.; Bianco, Giuseppe V.; Sacchetti, Alberto; Capezzuto, Pio; Bruno, Giovanni [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR, via Orabona 4, 70126 Bari (Italy)

2009-10-15

Au nanoparticles (NPs)/(n-type)a-Si:H/(p-type)c-Si heterojunctions have been deposited combining plasma-enhanced chemical-vapour deposition (PECVD) with Au sputtering. We demonstrate that a density of {proportional_to}1.3 x 10{sup 11} cm{sup -2} of Au nanoparticles with an approximately 20 nm diameter deposited onto (n-type)a-Si:H/(p-type)c-Si heterojunctions enhance performance exploiting the improved absorption of light by the surface plasmon resonance of Au NPs. In particular, Au NPs/(n-type)a-Si:H/(p-type)c-Si show an enhancement of 20% in the short-circuit current, J{sub SC}, 25% in the power output, P{sub max} and 3% in the fill factor, FF, compared to heterojunctions without Au NPs. Structures have been characterized by spectroscopic ellipsometry, atomic force microscopy and current-voltage (I-V) measurements to correlate the plasmon resonance-induced enhanced absorption of light with photovoltaic performance. (author)

Auxiliary resonant DC tank converter

Science.gov (United States)

Peng, Fang Z.

2000-01-01

An auxiliary resonant dc tank (ARDCT) converter is provided for achieving soft-switching in a power converter. An ARDCT circuit is coupled directly across a dc bus to the inverter to generate a resonant dc bus voltage, including upper and lower resonant capacitors connected in series as a resonant leg, first and second dc tank capacitors connected in series as a tank leg, and an auxiliary resonant circuit comprising a series combination of a resonant inductor and a pair of auxiliary switching devices. The ARDCT circuit further includes first clamping means for holding the resonant dc bus voltage to the dc tank voltage of the tank leg, and second clamping means for clamping the resonant dc bus voltage to zero during a resonant period. The ARDCT circuit resonantly brings the dc bus voltage to zero in order to provide a zero-voltage switching opportunity for the inverter, then quickly rebounds the dc bus voltage back to the dc tank voltage after the inverter changes state. The auxiliary switching devices are turned on and off under zero-current conditions. The ARDCT circuit only absorbs ripples of the inverter dc bus current, thus having less current stress. In addition, since the ARDCT circuit is coupled in parallel with the dc power supply and the inverter for merely assisting soft-switching of the inverter without participating in real dc power transmission and power conversion, malfunction and failure of the tank circuit will not affect the functional operation of the inverter; thus a highly reliable converter system is expected.

A DC to 3-phase series-resonant converter with low harmonic distortion

NARCIS (Netherlands)

Huisman, H.; Haan, de S.W.H.

1985-01-01

A type of dc to 3-phase series-resonant converter (s.r.converter) or potentially submegawatt industrial applications is presented. The converter provides variable-frequency sine-wave currents, with low harmonic distortion at the output terminals, and with the frequency ranging from -200 through dc

Piezoelectric microelectromechanical resonant sensors for chemical and biological detection.

Science.gov (United States)

Pang, Wei; Zhao, Hongyuan; Kim, Eun Sok; Zhang, Hao; Yu, Hongyu; Hu, Xiaotang

2012-01-07

Piezoelectric microelectromechanical systems (MEMS) resonant sensors, known for their excellent mass resolution, have been studied for many applications, including DNA hybridization, protein-ligand interactions, and immunosensor development. They have also been explored for detecting antigens, organic gas, toxic ions, and explosives. Most piezoelectric MEMS resonant sensors are acoustic sensors (with specific coating layers) that enable selective and label-free detection of biological events in real time. These label-free technologies have recently garnered significant attention for their sensitive and quantitative multi-parameter analysis of biological systems. Since piezoelectric MEMS resonant sensors do more than transform analyte mass or thickness into an electrical signal (e.g., frequency and impedance), special attention must be paid to their potential beyond microweighing, such as measuring elastic and viscous properties, and several types of sensors currently under development operate at different resonant modes (i.e., thickness extensional mode, thickness shear mode, lateral extensional mode, flexural mode, etc.). In this review, we provide an overview of recent developments in micromachined resonant sensors and activities relating to biochemical interfaces for acoustic sensors.

Damping Methods for Resonances Caused by LCL-Filter-Based Current-Controlled Grid-Tied Power Inverters

DEFF Research Database (Denmark)

Wu, Weimin; Liu, Yuan; He, Yuanbin

2017-01-01

Grid-tied voltage source inverters using LCL filter have been widely adopted in distributed power generation systems (DPGSs). As high-order LCL filters contain multiple resonant frequencies, switching harmonics generated by the inverter and current harmonics generated by the active/passive loads...... innovative damping methods have been proposed. A comprehensive overview on those contributions and their classification on the inverter- and grid-side damping measures are presented. Based on the concept of the impedance-based stability analysis, all damping methods can ensure the system stability...

Unified analytical expressions for calculating resonant frequencies, transimpedances, and equivalent input noise current densities of tuned receiver front ends

DEFF Research Database (Denmark)

Liu, Qing Zhong

1992-01-01

Unified analytical expressions have been derived for calculating the resonant frequencies, transimpedance and equivalent input noise current densities of the four most widely used tuned optical receiver front ends built with FETs and p-i-n diodes. A more accurate FET model has been used to improve...

Voltage current characteristics of type III superconductors

Science.gov (United States)

Dorofejev, G. L.; Imenitov, A. B.; Klimenko, E. Yu.

1980-06-01

An adequate description of voltage-current characteristics is important in order to understand the nature of high critical current for the electrodynamic construction of type-III superconductors and for commercial superconductor specification. Homogenious monofilament and multifilament Nb-Ti, Nb-Zr, Nb 3Sn wires were investigated in different ranges of magnetic field, temperature and current. The longitudinal electric field for homogenious wires may be described by E=J ρnexp- T c/T 0+ T/T 0+ B/B 0+ J/J 0, where To, Bo, Jo are the increasing parameters, which depend weakly on B and T, of the electric field. The shape of the voltage-current characteristics of multifilament wires, and the parameter's dependence on temperature and magnetic field may be explained qualitatively by the longitudinal heterogeneous nature of the filaments. A method of attaining the complete specification of the wire's electro-physical properties is proposed. It includes the traditional description of a critical surface (ie the surface corresponding to a certain conventional effective resistivity in T, B, J - space) and a description of any increasing parameter that depends on B and T.

Quantum dot single-photon switches of resonant tunneling current for discriminating-photon-number detection.

Science.gov (United States)

Weng, Qianchun; An, Zhenghua; Zhang, Bo; Chen, Pingping; Chen, Xiaoshuang; Zhu, Ziqiang; Lu, Wei

2015-03-23

Low-noise single-photon detectors that can resolve photon numbers are used to monitor the operation of quantum gates in linear-optical quantum computation. Exactly 0, 1 or 2 photons registered in a detector should be distinguished especially in long-distance quantum communication and quantum computation. Here we demonstrate a photon-number-resolving detector based on quantum dot coupled resonant tunneling diodes (QD-cRTD). Individual quantum-dots (QDs) coupled closely with adjacent quantum well (QW) of resonant tunneling diode operate as photon-gated switches- which turn on (off) the RTD tunneling current when they trap photon-generated holes (recombine with injected electrons). Proposed electron-injecting operation fills electrons into coupled QDs which turn "photon-switches" to "OFF" state and make the detector ready for multiple-photons detection. With proper decision regions defined, 1-photon and 2-photon states are resolved in 4.2 K with excellent propabilities of accuracy of 90% and 98% respectively. Further, by identifying step-like photon responses, the photon-number-resolving capability is sustained to 77 K, making the detector a promising candidate for advanced quantum information applications where photon-number-states should be accurately distinguished.

Resonant snubber inverter

Science.gov (United States)

Lai, Jih-Sheng; Young, Sr., Robert W.; Chen, Daoshen; Scudiere, Matthew B.; Ott, Jr., George W.; White, Clifford P.; McKeever, John W.

1997-01-01

A resonant, snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the main inverter switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter.

Resonance of conductivity in UHF-range to the action of alternating current in La0.7Pb0.3MnO3 crystals

International Nuclear Information System (INIS)

Volkov, N.V.; Petrakovskij, G.A.; Sablina, K.A.

1999-01-01

The experimental results of the study on the effect of the low frequency transport current on the conductivity in UHF-range of the La 0.7 Pb 0.3 MnO 3 monocrystals are presented. In absence of the external magnetic field the UHF-conductivity response signal on the current impact has the form of the relaxation process. The peak of the amplitude resonance growth is observed in the external magnetic field in the response spectrum. The resonance response is of nonlinear character. The temperature and field dependences of the UHF-response basic parameters are in direct correlation with the magnetoresistance behaviour. The results obtained are analyzed within the frames of the oscillatory approximation. The mechanism of the phases electron separation is proposed as the possible mechanism of the current impact [ru

Development of a high-sensitivity and portable cell using Helmholtz resonance for noninvasive blood glucose-level measurement based on photoacoustic spectroscopy.

Science.gov (United States)

Tachibana, K; Okada, K; Kobayashi, R; Ishihara, Y

2016-08-01

We describe the possibility of high-sensitivity noninvasive blood glucose measurement based on photoacoustic spectroscopy (PAS). The demand for noninvasive blood glucose-level measurement has increased due to the explosive increase in diabetic patients. We have developed a noninvasive blood glucose-level measurement based on PAS. The conventional method uses a straight-type resonant cell. However, the cell volume is large, which results in a low detection sensitivity and difficult portability. In this paper, a small-sized Helmholtz-type resonant cell is proposed to improve detection sensitivity and portability by reducing the cell dead volume. First, the acoustic property of the small-sized Helmholtz-type resonant cell was evaluated by performing an experiment using a silicone rubber. As a result, the detection sensitivity of the small-sized Helmholtz-type resonant cell was approximately two times larger than that of the conventional straight-type resonant cell. In addition, the inside volume was approximately 30 times smaller. Second, the detection limits of glucose concentration were estimated by performing an experiment using glucose solutions. The experimental results showed that a glucose concentration of approximately 1% was detected by the small-sized Helmholtz-type resonant cell. Although these results on the sensitivity of blood glucose-level measurement are currently insufficient, they suggest that miniaturization of a resonance cell is effective in the application of noninvasive blood glucose-level measurement.

Three-wave interaction during electron cyclotron resonance heating and current drive

DEFF Research Database (Denmark)

Nielsen, Stefan Kragh; Jacobsen, Asger Schou; Hansen, Søren Kjer

2016-01-01

Non-linear wave-wave interactions in fusion plasmas, such as the parametric decay instability (PDI) of gyrotron radiation, can potentially hamper the use of microwave diagnostics. Here we report on anomalous scattering in the ASDEX Upgrade tokamak during electron cyclotron resonance heating...... experiments. The observations can be linked to parametric decay of the gyrotron radiation at the second harmonic upper hybrid resonance layer....

Current ramp-up experiments in full current drive plasmas on TRIAM-1M

International Nuclear Information System (INIS)

Hanada, K.; Nakamura, K.; Hasegawa, M.

2003-01-01

Four types of plasma current ramp-up experiments were executed on TRIAM-1M in full lower hybrid current drive plasmas (LHCD: 8.2GHz, up to 0.4 MW, 8 x 2 grill antenna); 1) the current start up by the combination between electron cyclotron resonance heating (ECH: 170GHz, up to 0.2 MW, O-mode launching) and LHCD at the density of ∼2x10 19 m -3 at B t =6.7T, 2) the tail heating by the additional LHCD, 3) the bulk heating by ECH, 4) the spontaneous ramp up by the transition to enhanced current drive (ECD) mode. The time evolutions of plasma current during four types of ramp-up phase were investigated and an exponential type and a tangent-hyperbolic one were observed. The time evolutions of plasma current during the tail and the bulk heating show the exponential type except the tail heating with high n parallel and it has a tangent-hyperbolic one during the ECD mode and the current start-up. A simple model with two different time constants, which are a time defined by L/R, τ L/R , and a time caused by change of the effective refractive index along the magnetic field, τ, is proposed to explain two types of the time evolution of the plasma current. The estimated τ L/R is consistent with the calculated one from the plasma parameter. It is found that τ are less than τ L/R in the cases of the tail and the bulk heating, and comparable in the cases of the ECD mode, and more than τ L/R in the cases of the plasma start-up. This indicates that the value of the effective refractive index along the magnetic field, parallel >, develops during the ECD mode and the current start-up. The value of τ depends on the RF power. The estimated is close to the expected up-shifted n parallel due to the toroidal effect and the magnetic shear. (author)

Pediatric magnetic resonance imaging

International Nuclear Information System (INIS)

Cohen, M.D.

1986-01-01

This book defines the current clinical potential of magnetic resonance imaging and focuses on direct clinical work with pediatric patients. A section dealing with the physics of magnetic resonance imaging provides an introduction to enable clinicians to utilize the machine and interpret the images. Magnetic resonance imaging is presented as an appropriate imaging modality for pediatric patients utilizing no radiation

Magnetic resonance of phase transitions

CERN Document Server

Owens, Frank J; Farach, Horacio A

1979-01-01

Magnetic Resonance of Phase Transitions shows how the effects of phase transitions are manifested in the magnetic resonance data. The book discusses the basic concepts of structural phase and magnetic resonance; various types of magnetic resonances and their underlying principles; and the radiofrequency methods of nuclear magnetic resonance. The text also describes quadrupole methods; the microwave technique of electron spin resonance; and the Mössbauer effect. Phase transitions in various systems such as fluids, liquid crystals, and crystals, including paramagnets and ferroelectrics, are also

Resonance Phenomena in Goupillaud-type Media

Science.gov (United States)

2010-10-01

layered structures (7), anisotropic elastic bodies (8), anisotropic layered crystals (9, 10), elastic plates (11, 12), periodic media (13), laminated and...sandwich plates (14), composite laminates (15), piezoelectric composites (16), locally resonant acoustic metamaterials (17, 18), and acoustic wave...bm 2 c∑ k=1 ai,k cos (nθk) + bi,k sin (nθk) ] , (20) where operation ∗ means convolution , i = 1, 2, . . .m, and n ≥ 0. The stress representation

Nonlinear resonances

CERN Document Server

Rajasekar, Shanmuganathan

2016-01-01

This introductory text presents the basic aspects and most important features of various types of resonances and anti-resonances in dynamical systems. In particular, for each resonance, it covers the theoretical concepts, illustrates them with case studies, and reviews the available information on mechanisms, characterization, numerical simulations, experimental realizations, possible quantum analogues, applications and significant advances made over the years. Resonances are one of the most fundamental phenomena exhibited by nonlinear systems and refer to specific realizations of maximum response of a system due to the ability of that system to store and transfer energy received from an external forcing source. Resonances are of particular importance in physical, engineering and biological systems - they can prove to be advantageous in many applications, while leading to instability and even disasters in others. The book is self-contained, providing the details of mathematical derivations and techniques invo...

Na+ currents in vestibular type I and type II hair cells of the embryo and adult chicken.

Science.gov (United States)

Masetto, S; Bosica, M; Correia, M J; Ottersen, O P; Zucca, G; Perin, P; Valli, P

2003-08-01

In birds, type I and type II hair cells differentiate before birth. Here we describe that chick hair cells, from the semicircular canals, begin expressing a voltage-dependent Na current (INa) from embryonic day 14 (E14) and continue to express the current up to hatching (E21). During this period, INa was present in most (31/43) type I hair cells irrespective of their position in the crista, in most type II hair cells located far from the planum semilunatum (48/63), but only occasionally in type II hair cells close to the planum semilunatum (2/35). INa activated close to -60 mV, showed fast time- and voltage-dependent activation and inactivation, and was completely, and reversibly, blocked by submicromolar concentrations of tetrodotoxin (Kd = 17 nM). One peculiar property of INa concerns its steady-state inactivation, which is complete at -60 mV (half-inactivating voltage = -96 mV). INa was found in type I and type II hair cells from the adult chicken as well, where it had similar, although possibly not identical, properties and regional distribution. Current-clamp experiments showed that INa could contribute to the voltage response provided that the cell membrane was depolarized from holding potentials more negative than -80 mV. When recruited, INa produced a significant acceleration of the cell membrane depolarization, which occasionally elicited a large rapid depolarization followed by a rapid repolarization (action-potential-like response). Possible physiological roles for INa in the embryo and adult chicken are discussed.

Experimental Investigation of 2:1 and 3:1 Internal Resonances in Nonlinear MEMS Arch Resonators

KAUST Repository

Ramini, Abdallah; Hajjaj, Amal Z.; Younis, Mohammad I.

2016-01-01

We demonstrate experimentally internal resonances in MEMS resonators. The investigation is conducted on in-plane MEMS arch resonators fabricated with a highly doped silicon. The resonators are actuated electrostatically and their stiffness are tuned by electrothermal loading by passing an electrical current though the microstructures. We show that through this tuning, the ratio of the various resonance frequencies can be varied and set at certain ratios. Particularly, we adjust the resonance frequencies of two different vibrational modes to 2:1 and 3:1. Finally, we validate the internal resonances at these ratios through frequency-response curves and FFTs.

Experimental Investigation of 2:1 and 3:1 Internal Resonances in Nonlinear MEMS Arch Resonators

KAUST Repository

Ramini, Abdallah

2016-12-05

We demonstrate experimentally internal resonances in MEMS resonators. The investigation is conducted on in-plane MEMS arch resonators fabricated with a highly doped silicon. The resonators are actuated electrostatically and their stiffness are tuned by electrothermal loading by passing an electrical current though the microstructures. We show that through this tuning, the ratio of the various resonance frequencies can be varied and set at certain ratios. Particularly, we adjust the resonance frequencies of two different vibrational modes to 2:1 and 3:1. Finally, we validate the internal resonances at these ratios through frequency-response curves and FFTs.

Resonant non-Gaussianity with equilateral properties

International Nuclear Information System (INIS)

Gwyn, Rhiannon; Rummel, Markus

2012-11-01

We discuss the effect of superimposing multiple sources of resonant non-Gaussianity, which arise for instance in models of axion inflation. The resulting sum of oscillating shape contributions can be used to ''Fourier synthesize'' different non-oscillating shapes in the bispectrum. As an example we reproduce an approximately equilateral shape from the superposition of O(10) oscillatory contributions with resonant shape. This implies a possible degeneracy between the equilateral-type non-Gaussianity typical of models with non-canonical kinetic terms, such as DBI inflation, and an equilateral-type shape arising from a superposition of resonant-type contributions in theories with canonical kinetic terms. The absence of oscillations in the 2-point function together with the structure of the resonant N-point functions, imply that detection of equilateral non-Gaussianity at a level greater than the PLANCK sensitivity of f NL ∝O(5) will rule out a resonant origin. We comment on the questions arising from possible embeddings of this idea in a string theory setting.

Magnetic resonance imaging in complete type endocardial cushion defect

International Nuclear Information System (INIS)

Li Kuncheng; Yang Xiaoping; Yao Xinyu; Yang Yunxia; Liu Yuqing; Pang Zhixian

1999-01-01

Objective: To evaluate the value and limitation of magnetic resonance imaging (MRI) in complete type endocardial cushion defect (ETECD). Methods: Eight patients (male 5, female 3) were scanned by MRI with ECG-gated spin echo (SE) and gradient echo (GE) cine techniques. The diagnosis of CTECD was made by X-ray plain film, echocardiography, X-ray right cardiac catheterization and angiocardiography, as well as MRI four patients were treated with operation. Results: Every chamber of the heart was enlarged, more serious in the right atrium and ventricle, with thickening of right ventricular wall on MRI in majority of cases. The endocardial cushion disappeared, so the four chambers of the heart were directly connected with each other, and presented a cross shape. Ventricular septal membrane defect and type I atrial septal defect were depicted also. The normal structure of mitral and tricuspid valves were not intact. There were 6 cases with pulmonary hypertension, 2 cases with Tetralogy of Fallot, 4 cases with right aorta arch and descending aorta, 1 patient with dextroverted heart and another with persistent left superior vena cava connected with coronary sinus. The cine MRI could directly depict the situation of left-right or right-left shunt at atrial and ventricular levels, and regurgitation from ventricles to atria, meanwhile the valves were depicted clearly. Conclusions: MRI can clearly demonstrate all anatomic deformation and complicated hemodynamic change of CTECD, as well as other coexistent deformations

Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

Directory of Open Access Journals (Sweden)

N. I. Polzikova

2016-05-01

Full Text Available We present the generation and detection of spin currents by using magnetoelastic resonance excitation in a magnetoelectric composite high overtone bulk acoustic wave (BAW resonator (HBAR formed by a Al-ZnO-Al-GGG-YIG-Pt structure. Transversal BAW drives magnetization oscillations in YIG film at a given resonant magnetic field, and the resonant magneto-elastic coupling establishes the spin-current generation at the Pt/YIG interface. Due to the inverse spin Hall effect (ISHE this BAW-driven spin current is converted to a dc voltage in the Pt layer. The dependence of the measured voltage both on magnetic field and frequency has a resonant character. The voltage is determined by the acoustic power in HBAR and changes its sign upon magnetic field reversal. We compare the experimentally observed amplitudes of the ISHE electrical field achieved by our method and other approaches to spin current generation that use surface acoustic waves and microwave resonators for ferromagnetic resonance excitation, with the theoretically expected values.

Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

Energy Technology Data Exchange (ETDEWEB)

Polzikova, N. I., E-mail: polz@cplire.ru; Alekseev, S. G.; Pyataikin, I. I.; Kotelyanskii, I. M.; Luzanov, V. A.; Orlov, A. P. [Kotel’nikov Institute of Radio Engineering and Electronics of Russian Academy of Sciences, Mokhovaya 11, building 7, Moscow, 125009 (Russian Federation)

2016-05-15

We present the generation and detection of spin currents by using magnetoelastic resonance excitation in a magnetoelectric composite high overtone bulk acoustic wave (BAW) resonator (HBAR) formed by a Al-ZnO-Al-GGG-YIG-Pt structure. Transversal BAW drives magnetization oscillations in YIG film at a given resonant magnetic field, and the resonant magneto-elastic coupling establishes the spin-current generation at the Pt/YIG interface. Due to the inverse spin Hall effect (ISHE) this BAW-driven spin current is converted to a dc voltage in the Pt layer. The dependence of the measured voltage both on magnetic field and frequency has a resonant character. The voltage is determined by the acoustic power in HBAR and changes its sign upon magnetic field reversal. We compare the experimentally observed amplitudes of the ISHE electrical field achieved by our method and other approaches to spin current generation that use surface acoustic waves and microwave resonators for ferromagnetic resonance excitation, with the theoretically expected values.

Resonant inverter supplied Interior Permanent Magnet (IPM) motor ...

African Journals Online (AJOL)

In this paper, rotor position in relation to the resonant frequency component current in the stator winding of DC-voltage link resonant inverter supplied Interior Permanent Magnet (IPM) motor has been developed. Six reference frames are used to relate the rotor position angle to the resonant frequency component current ...

Digital proportional multi-resonant current controller for improving grid-connected photovoltaic systems

NARCIS (Netherlands)

Almeida, de P.M.; Barbosa, P.G.; Oliveira, J.G.; Duarte, J.L.; Ribeiro, P.F.

2015-01-01

This paper presents the modelling and design steps of a digital proportional multi-resonant controller used in a grid-connected photovoltaic (PV) system. It is shown that the use of only one Proportional-Resonant (PR) compensator, tuned to the system fundamental frequency, may have its effectiveness

Ca(2+) currents and voltage responses in Type I and Type II hair cells of the chick embryo semicircular canal.

Science.gov (United States)

Masetto, Sergio; Zampini, Valeria; Zucca, Giampiero; Valli, Paolo

2005-11-01

Type I and Type II hair cells, and Type II hair cells located in different zones of the semicircular canal crista, express different patterns of voltage-dependent K channels, each one specifically shaping the hair cell receptor potential. We report here that, close to hatching, chicken embryo semicircular canal Type I and Type II hair cells express a similar voltage-dependent L-type calcium current (I(Ca)), whose main features are: activation above -60 mV, fast activation kinetics, and scarce inactivation. I(Ca) should be already active at rest in Zone 1 Type II hair cells, whose resting membrane potential was on average slightly less negative than -60 mV. Conversely, I(Ca) would not be active at rest in Type II hair cells from Zone 2 and 3, nor in Type I hair cells, since their resting membrane potential was significantly more negative than -60 mV. However, even small depolarising currents would activate I(Ca) steadily in Zone 2 and 3 Type II hair cells, but not in Type I hair cells because of the robust repolarising action of their specific array of K(+) currents. The implications of the present findings in the afferent discharge are discussed.

Myocardial Steatosis and Left Ventricular Function in Type 2 Diabetes Mellitus : Assessed with Magnetic Resonance Imaging and Spectroscopy

NARCIS (Netherlands)

Meer, Rutger Wouter van der

2008-01-01

The aim of the thesis was to provide more insight into the influence of myocardial steatosis on left ventricular function in healthy volunteers and in patients with type 2 diabetes mellitus. Therefore we developed a reproducible proton magnetic resonance (MR) spectroscopic technique with respiratory

Characterisation of eddy current signals using different types of artificial neural networks

International Nuclear Information System (INIS)

Shyamsunder, M.T.; Rajagopalan, C.; Jayakumar, T.; Kalyanasundaram, P.; Baldev Raj; Ray, K.K.

1996-01-01

Eddy current testing is one of the important techniques in nondestructive testing. Automated characterisation of eddy current signals (ECS), either in the form of lissajous patterns (figure-of-eight) or individual voltage vs. time signals is an area of growing interest. This is particularly relevant in environments where the signal-to-noise ratio (SNR) of ECS are very poor. Intelligent, timely and precise interpretation of resulting data, is the key for improving the efficiency of NDT and E. A comprehensive study has been undertaken by the authors for the characterisation of ECS having poor SNR, using three types of artificial neural networks (ANNs). The types of ANNs used in this study are [a] the error-back propagation model, [b] the binary Hopfield model and [c] the Kohonen's self-organising maps model. Eddy current signals, acquired from different types of defects such as holes and notches on stainless steel type 316 sheets were used in this study. (author)

Current limiting experiment with 600 V/100A rectification type superconducting fault current limiter; 600 V-100A kyu seiryugata chodendo genryuki no genryu shiken

Energy Technology Data Exchange (ETDEWEB)

Matsuzaki, J.; Tsurunaga, K.; Urata, M. [Toshiba Corp., Tokyo (Japan); Okuma, T.; Sato, Y.; Iwata, Y. [Tokyo Electric Power Co., Inc., Tokyo (Japan)

1999-06-07

The rectification type current limiter with the current-limiting system of the new type which combined rectifier circuits with the direct current reactor has been proposed until now, and it has succeeded in the current-limiting test by the normal conduction reactor by the 6.6kV class model vessel. Since the loss of the conductor becomes fundamentally the zero, in the same current limiter, by using superconducting wire rod, because direct current always flows in the reactor, making into low-loss becomes possible. In this report, this paper describes cut-off characteristic of 600V/100A rectification type superconductive current limiter using the metal type superconductive conductor. (NEDO)

Cell-type-dependent action potentials and voltage-gated currents in mouse fungiform taste buds.

Science.gov (United States)

Kimura, Kenji; Ohtubo, Yoshitaka; Tateno, Katsumi; Takeuchi, Keita; Kumazawa, Takashi; Yoshii, Kiyonori

2014-01-01

Taste receptor cells fire action potentials in response to taste substances to trigger non-exocytotic neurotransmitter release in type II cells and exocytotic release in type III cells. We investigated possible differences between these action potentials fired by mouse taste receptor cells using in situ whole-cell recordings, and subsequently we identified their cell types immunologically with cell-type markers, an IP3 receptor (IP3 R3) for type II cells and a SNARE protein (SNAP-25) for type III cells. Cells not immunoreactive to these antibodies were examined as non-IRCs. Here, we show that type II cells and type III cells fire action potentials using different ionic mechanisms, and that non-IRCs also fire action potentials with either of the ionic mechanisms. The width of action potentials was significantly narrower and their afterhyperpolarization was deeper in type III cells than in type II cells. Na(+) current density was similar in type II cells and type III cells, but it was significantly smaller in non-IRCs than in the others. Although outwardly rectifying current density was similar between type II cells and type III cells, tetraethylammonium (TEA) preferentially suppressed the density in type III cells and the majority of non-IRCs. Our mathematical model revealed that the shape of action potentials depended on the ratio of TEA-sensitive current density and TEA-insensitive current one. The action potentials of type II cells and type III cells under physiological conditions are discussed. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Investigation of multipactoring discharge in an H-type resonator of an ion linac

International Nuclear Information System (INIS)

Lobzev, L.D.; Mazalov, Yu.P.; Gusev, E.V.; Shulika, N.G.

1993-01-01

The study on the variation of parameters of an auto generator power supply of an ion linear accelerator which is under construction on the base of the H-type resonator with drift tube comb mounts has been made. The main attention was paid to investigating multipactor discharges. It is concluded, that presence of secondary autonomous self-oscillation circuit providing the field rise with the frequency close to operation frequency leads to the decrease of multipactor discharge intensity level, which is enough for the elimination of their harmful effect on accelerator steady-state performance. 8 refs., 3 figs

Construction of a resonant loop with the ICRF antenna for KSTAR

International Nuclear Information System (INIS)

Bae, Young Dug; Jeong, Sung Un; Yoon, Jae Sung; Hong, Bong Geon

2003-01-01

The antenna of the KSTAR ICRF heating system consists of four current straps, each of which is grounded at the center, and has two coaxial ports, one at each end. The top and bottom ports of each strap are fed by one transmitter. The two ports are connected at tee connector to form a resonant loop, and the coaxial feed line from the transmitter is connected to the tee. One resonant loop with the proto-type antenna is built at the RF test stand in KAERI. It is composed with one current strap, one tee connector and two arms connecting them. Each arm consists of a 6-inch vacuum transmission line, a vacuum feed through, a part of pressurized 9-inch coaxial line, and an adjustable phase shifter to cover wide frequency range of 25-60 MHz. Total electrical length is changeable from 45 to 51 m. Many voltage probes and directional couplers are installed to measure RF voltage of the standing wave, power flow and phase difference. Resonant and matching conditions are investigated for various frequencies

Single-channel L-type Ca2+ currents in chicken embryo semicircular canal type I and type II hair cells.

Science.gov (United States)

Zampini, Valeria; Valli, Paolo; Zucca, Giampiero; Masetto, Sergio

2006-08-01

Few data are available concerning single Ca channel properties in inner ear hair cells and particularly none in vestibular type I hair cells. By using the cell-attached configuration of the patch-clamp technique in combination with the semicircular canal crista slice preparation, we determined the elementary properties of voltage-dependent Ca channels in chicken embryo type I and type II hair cells. The pipette solutions included Bay K 8644. With 70 mM Ba(2+) in the patch pipette, Ca channel activity appeared as very brief openings at -60 mV. Ca channel properties were found to be similar in type I and type II hair cells; therefore data were pooled. The mean inward current amplitude was -1.3 +/- 0.1 (SD) pA at - 30 mV (n = 16). The average slope conductance was 21 pS (n = 20). With 5 mM Ba(2+) in the patch pipette, very brief openings were already detectable at -80 mV. The mean inward current amplitude was -0.7 +/- 0.2 pA at -40 mV (n = 9). The average slope conductance was 11 pS (n = 9). The mean open time and the open probability increased significantly with depolarization. Ca channel activity was still present and unaffected when omega-agatoxin IVA (2 microM) and omega-conotoxin GVIA (3.2 microM) were added to the pipette solution. Our results show that types I and II hair cells express L-type Ca channels with similar properties. Moreover, they suggest that in vivo Ca(2+) influx might occur at membrane voltages more negative than -60 mV.

The direct l-type resonance spectrum of CF3CCH in the vibrational state ν 10 = 2

International Nuclear Information System (INIS)

Woetzel, Ulf; Maeder, Heinrich; Harder, Hauke; Pracna, Petr; Sarka, Kamil

2005-01-01

The direct l-type resonance spectrum of CF 3 CCH in the vibrational state ν 10 = 2 has been measured by means of waveguide microwave Fourier transform spectroscopy in the range 8-26 GHz. Two types of direct l-type resonance transitions induced by the (Δk = ±2, Δl = ±2) interaction could be observed: 262 transitions following the ΔJ = 0, Δk = Δl = 2 selection rule covering values of J = 17-64 and G vertical bar k - l vertical bar from 2 to 15, and 75 transitions following the ΔJ = 0, Δk = Δl = 4 selection rule covering values of J = 44-70 and G up to 3. The strong (2, 2) resonance furthermore allowed the observation of A 1 -A 2 splittings of the k = l = ±2 states from J = 63-70. The transitions with G = 3 showed splittings due to the (4, -2) and (0, 6) interactions. The corresponding energy level systems and part of the Hamiltonian matrix are discussed. Strong perturbations due to Δ(k - l) = 3 interactions coupling the states k = ±1, l = ±2 and k = ±4, l ±2 made possible the observation of perturbation-allowed transitions with selection rule k = ±1, l =± 2 ↔ k = 0, l = ±2. Additionally, the J = 2-1 and 3-2 rotational transitions have been measured. A multiple fitting analysis has been performed in which the experimental data have been fitted using five reduced forms of the effective Hamiltonian as proposed by Sarka and Harder [J. Mol. Spectrosc. 197 (1999) 254]. Parameters up to sixth order have been determined including the axial rotational constant A for both values of vertical bar l vertical bar and the unitary equivalence of the determined parameter sets has been demonstrated

Microelectromechanical resonator and method for fabrication

Science.gov (United States)

Wittwer, Jonathan W [Albuquerque, NM; Olsson, Roy H [Albuquerque, NM

2009-11-10

A method is disclosed for the robust fabrication of a microelectromechanical (MEM) resonator. In this method, a pattern of holes is formed in the resonator mass with the position, size and number of holes in the pattern being optimized to minimize an uncertainty .DELTA.f in the resonant frequency f.sub.0 of the MEM resonator due to manufacturing process variations (e.g. edge bias). A number of different types of MEM resonators are disclosed which can be formed using this method, including capacitively transduced Lame, wineglass and extensional resonators, and piezoelectric length-extensional resonators.

PWM control of current source type six-phase inverter with improved waveforms by coupling reactor; Ketsugo reactor ni yori hakei kaizen sareta denryugata rokuso inverter no PWM seigyo

Energy Technology Data Exchange (ETDEWEB)

Inami, K.; Danjo, M.; Kondo, Y.; Yamada, M. [Niihama Technical College, Ehime (Japan); Toki, K. [Shikoku Electric Power Co., Inc., Kagawa (Japan); Heike, J. [Shikoku Instrumentation Co. Ltd., Kagawa (Japan)

1998-10-01

A PWM method has been applied to a high capacity six phase current source inverter system in order to obtain sinusoidal output voltage and current. In this system, the three-phase coupling reactor is connected between the inverter output and an induction motor used as a load. Then the reactor eliminates harmonic components included in the inverter output current except 12k {+-} 1 (k=1,2,3)th order. As a result, the distortion factor of the inverter output current decreases. But the resonant circuit is composed of the capacitance of filter capacitor and the induction motor leakage inductance. Then the resonance current is superimposed on the induction motor phase currents. To solve this problem, the optimal PWM pattern is derived, so that the resonant current becomes very small. The order of the resonant frequency component of the induction motor phase current depend on the inverter frequency. Then total inverter frequency range is divided into several areas. The optimal PWM pattern is derived in each areas. As a result, the use of each optimal PWM pattern allows us to drive the induction motor, over a wide range of speed, under the condition of small distortion factor of phase currents. 5 refs., 10 figs., 1 tab.

Scattering measurements in Tokamak type devices

International Nuclear Information System (INIS)

Matoba, Tohru

1975-03-01

Theories, experiments and proposals for light scattering in Tokamak type devices are reviewed. Thomson scattering, measuring method of the current density distribution by scattering and resonance fluorescence are summarily described. These methods may be useful for diagnosis of the fusion plasmas. The report may help planning of the measuring apparatus for the fusion plasmas in future. (auth.)

Resonant Tunneling Spin Pump

Science.gov (United States)

Ting, David Z.

2007-01-01

The resonant tunneling spin pump is a proposed semiconductor device that would generate spin-polarized electron currents. The resonant tunneling spin pump would be a purely electrical device in the sense that it would not contain any magnetic material and would not rely on an applied magnetic field. Also, unlike prior sources of spin-polarized electron currents, the proposed device would not depend on a source of circularly polarized light. The proposed semiconductor electron-spin filters would exploit the Rashba effect, which can induce energy splitting in what would otherwise be degenerate quantum states, caused by a spin-orbit interaction in conjunction with a structural-inversion asymmetry in the presence of interfacial electric fields in a semiconductor heterostructure. The magnitude of the energy split is proportional to the electron wave number. Theoretical studies have suggested the possibility of devices in which electron energy states would be split by the Rashba effect and spin-polarized currents would be extracted by resonant quantum-mechanical tunneling.

A magnetic resonance imaging study in first-episode disorganized-type patients with schizophrenia

International Nuclear Information System (INIS)

Ohnuma, Tohru; Kimura, Michihiro; Takahashi, Tadashi; Iwamoto, Norihiko; Arai, Heii

1997-01-01

Although a number of radiological studies have suggested that brains of patients suffering from schizophrenia have morphological abnormalities, the results are inconsistent. In the present study, in order to examine the brain, morphological features of homogeneous schizophrenics' brain magnetic resonance imagings (MRI) were taken, before neuroleptic treatment, from subjects suffering from disorganized-type schizophrenia, (DOS) during their first episodes. Results showed that DOS had significantly smaller indices for bilateral frontal gray matter (GM), left hippocampal formation (HF), left parahippocampal gray matter (PHGM) and left cingulate gyrus gray matter (CGM) than normal controls. These findings support the previous computed tomography (CT) and MRI studies on schizophrenic brains, although the subjects were not defined as disorganized-type, and may suggest the involvement of a neurocircuit between the bilateral frontal lobe and the left side of limbic system in the first-episode DOS group. (author). 54 refs

Resonant non-Gaussianity with equilateral properties

Energy Technology Data Exchange (ETDEWEB)

Gwyn, Rhiannon [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Potsdam (Germany); Rummel, Markus [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Westphal, Alexander [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2012-11-15

We discuss the effect of superimposing multiple sources of resonant non-Gaussianity, which arise for instance in models of axion inflation. The resulting sum of oscillating shape contributions can be used to ''Fourier synthesize'' different non-oscillating shapes in the bispectrum. As an example we reproduce an approximately equilateral shape from the superposition of O(10) oscillatory contributions with resonant shape. This implies a possible degeneracy between the equilateral-type non-Gaussianity typical of models with non-canonical kinetic terms, such as DBI inflation, and an equilateral-type shape arising from a superposition of resonant-type contributions in theories with canonical kinetic terms. The absence of oscillations in the 2-point function together with the structure of the resonant N-point functions, imply that detection of equilateral non-Gaussianity at a level greater than the PLANCK sensitivity of f{sub NL} {proportional_to}O(5) will rule out a resonant origin. We comment on the questions arising from possible embeddings of this idea in a string theory setting.

A three-phase to three-phase series-resonant power converter with optimal input current waveforms, Part II: implementation and results

NARCIS (Netherlands)

Huisman, H.

1988-01-01

For pt.I see ibid., vol.35, no.2, p.263-8 (1988). A 15 kW three-phase prototype series-resonant power converter is constructed. The converter features sinusoidal output voltage and sinusoidal input currents. The control concepts and necessary electronics, as well as the layout of the power circuit,

The theory of coherent resonance tunneling of interacting electrons

International Nuclear Information System (INIS)

Elesin, V. F.

2001-01-01

Analytical solutions of the Schrödinger equation for a two-barrier structure (resonance-tunnel diode) with open boundary conditions are found within the model of coherent tunneling of interacting electrons. Simple expressions for resonance current are derived which enable one to analyze the current-voltage characteristics, the conditions of emergence of hysteresis, and singularities of the latter depending on the parameters of resonance-tunnel diode. It is demonstrated that the hysteresis is realized if the current exceeds some critical value proportional to the square of resonance level width.

Resonance – Journal of Science Education | Indian Academy of ...

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Search. Search. Resonance – Journal of Science Education. Title. Author. Keywords. Category. Fulltext. Submit. Resonance – Journal of Science Education. Current Issue : Vol. 23, Issue 4. Current Issue Volume 23 | Issue 4. April 2018. Home · Volumes & Issues ...

Resonance tunneling of charge carriers in photoexcited type-II ZnSe/BeTe heterostructures

International Nuclear Information System (INIS)

Zaitsev, S. V.; Maksimov, A. A.; Tartakovskii, I. I.; Yakovlev, D. R.; Waag, A.

2008-01-01

In is shown that, at high densities of spatially separated electrons and holes in type-II ZnSe/BeTe heterostructures, the conditions for resonance tunneling of photoexcited holes from the ZnSe layer to the BeTe layer are attainable. Nonlinear behavior of the intensity of the photoluminescence band corresponding to spatially direct optical transitions with photoexcitation intensity is observed. Numerical calculations are carried out, and the results are in good agreement with the experimental data in a wide region of variation of the optical pumping intensity

Q-Boosted Optomechanical Resonators

Science.gov (United States)

2015-11-18

type a knob for optical Qo, where the inability to smooth etched nitride sidewall surfaces relegates OMO’s using it to Qo’s on the order of...6: Operation of an RP-OMO. As the ring resonator coupled to tapered fiber in (a) displaces by ∂r, the optical path length change produces the shift...frequency 0, B input pump laser field, tot the total optical resonator damping, ext the coupling between optical resonator and the tapered fiber

Cardiovascular magnetic resonance imaging in hypertrophic cardiomyopathy: Current state of the art.

Science.gov (United States)

Kamal, Muhammad Umar; Riaz, Irbaz Bin; Janardhanan, Rajesh

2016-01-01

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiomyopathy with a prevalence of 1:500 (0.2%) in the general population. Sudden cardiac death (SCD) is the most feared presentation of HCM. Therefore, it is essential to identify individuals at high risk in order to prevent SCD. The absence of conventional risk factors does not nullify the risk of HCM related SCD. Although echocardiography is currently the most widely used imaging modality, cardiac magnetic resonance (CMR) allows detailed characterization of the HCM phenotype, which makes it possible to differentiate HCM from other causes of left ventricular hypertrophy. CMR has the potential to further refine risk stratification. Late gadolinium enhancement (LGE) on CMR is a high-risk feature and there is emerging data to suggest that the presence of LGE should be employed as a marker for major adverse outcomes such as SCD, arrhythmias, systolic and diastolic heart failure. Hence, LGE on CMR may be considered an additional risk factor for SCD in HCM patients and should be incorporated in decision-making for implant-able cardioverter defibrillator implantation to aid primary prevention. Novel markers such as the extent of myocardial fibrosis on CMR must be accounted for comprehensive risk stratifica-tion of HCM patients. The purpose of this review is to discuss the current status and emerging role of CMR in HCM.

Resonance frequency analysis

Directory of Open Access Journals (Sweden)

Rajiv K Gupta

2011-01-01

Full Text Available Initial stability at the placement and development of osseointegration are two major issues for implant survival. Implant stability is a mechanical phenomenon which is related to the local bone quality and quantity, type of implant, and placement technique used. The application of a simple, clinically applicable, non-invasive test to assess implant stability and osseointegration is considered highly desirable. Resonance frequency analysis (RFA is one of such techniques which is most frequently used now days. The aim of this paper was to review and analyze critically the current available literature in the field of RFA, and to also discuss based on scientific evidence, the prognostic value of RFA to detect implants at risk of failure. A search was made using the PubMed database to find all the literature published on "Resonance frequency analysis for implant stability" till date. Articles discussed in vivo or in vitro studies comparing RFA with other methods of implant stability measurement and articles discussing its reliability were thoroughly reviewed and discussed. A limited number of clinical reports were found. Various studies have demonstrated the feasibility and predictability of the technique. However, most of these articles are based on retrospective data or uncontrolled cases. Randomized, prospective, parallel-armed longitudinal human trials are based on short-term results and long-term follow up are still scarce in this field. Nonetheless, from available literature, it may be concluded that RFA technique evaluates implant stability as a function of stiffness of the implant bone interface and is influenced by factors such as bone type, exposed implant height above the alveolar crest. Resonance frequency analysis could serve as a non-invasive diagnostic tool for detecting the implant stability of dental implants during the healing stages and in subsequent routine follow up care after treatment. Future studies, preferably randomized

Vector resonances at LHC Run II in composite 2HDM

Energy Technology Data Exchange (ETDEWEB)

Chiara, Stefano Di [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia); Heikinheimo, Matti; Tuominen, Kimmo [Helsinki Institute of Physics, University of Helsinki,P.O. Box 64, FI-000140, Helsinki (Finland); Department of Physics, University of Helsinki,P.O. Box 64, FI-000140, Helsinki (Finland)

2017-03-02

We consider a model where the electroweak symmetry breaking is driven by strong dynamics, resulting in an electroweak doublet scalar condensate, and transmitted to the standard model matter fields via another electroweak doublet scalar. At low energies the effective theory therefore shares features with a type-I two Higgs doublet model. However, important differences arise due to the rich composite spectrum expected to contain new vector resonances accessible at the LHC. We carry out a systematic analysis of the vector resonance signals at LHC and find that the model remains viable, but will be tightly constrained by direct searches as the projected integrated luminosity, around 200 fb{sup −1}, of the current run becomes available.

Resonance – Journal of Science Education | Indian Academy of ...

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education. Bala Iyer. Articles written in Resonance – Journal of Science Education. Volume 21 Issue 3 March 2016 pp 203-205 Editorial. Editorial · Bala Iyer · More Details Fulltext PDF. Resonance – Journal of Science Education. Current Issue : Vol. 23, Issue 4. Current ...

Stochastic resonance and coherence resonance in groundwater-dependent plant ecosystems.

Science.gov (United States)

Borgogno, Fabio; D'Odorico, Paolo; Laio, Francesco; Ridolfi, Luca

2012-01-21

Several studies have shown that non-linear deterministic dynamical systems forced by external random components can give rise to unexpectedly regular temporal behaviors. Stochastic resonance and coherence resonance, the two best known processes of this type, have been studied in a number of physical and chemical systems. Here, we explore their possible occurrence in the dynamics of groundwater-dependent plant ecosystems. To this end, we develop two eco-hydrological models, which allow us to demonstrate that stochastic and coherence resonance may emerge in the dynamics of phreatophyte vegetation, depending on their deterministic properties and the intensity of external stochastic drivers. Copyright © 2011 Elsevier Ltd. All rights reserved.

Structured exercise interventions for type 2 diabetes mellitus: Strength of current evidence

Directory of Open Access Journals (Sweden)

Mohammed Ejas Hussain

2011-07-01

Full Text Available Exercise, along with medical nutrition therapy and pharmacological interventions, is an important component in the clinical management of type 2 diabetes mellitus (T2D. Current clinical guidelines on type 2 diabetes provide no detailed information on the modalities of effective exercise intervention in the treatment of type 2 diabetes. Both endurance and resistance types of exercise seem to be equally effective in improving metabolic control in patients with type 2 diabetes. Determining the best method of providing exercise is clinically relevant to this population. This paper reviews the epidemiology of diabetes and problems of physical function associated with type 2 diabetes and discuss the benefits of exercise therapy on the parameters of glycemic control and function in type 2 diabetes patients, with special reference to Asian Indians. Based on the currently available literature, it is concluded that type 2 diabetes patients should be encouraged to participate in specifically designed exercise intervention programs. Attention should be paid to the avoidance of cardiovascular and musculoskeletal deconditioning. More clinical research is warranted to establish the efficacy of different dosages of exercise intervention in a holistic approach for type 2 diabetes subpopulations within different stages of the disease and various levels of co-morbidity.

Dihadronic and dileptonic resonances

International Nuclear Information System (INIS)

Gareev, F.A.; Barabanov, M.Yu.; Kazacha, G.S.

1997-01-01

Simple phenomenological rules are suggested for calculation of dihadron and dilepton resonance masses. A general interpretation is given for different exotic resonances in nuclear physics: Darmstadt-effect, dibaryon, dipion and other resonances. Information about the inner structure of e ± , proton, neutron, pions and so on can be obtained from the usual reactions of the type e + + e - =>γγ, e ± +γ=>e ± γ, e ± μ ± , e ± N... at low, intermediate and high energies using existing experimental devices

Microwave oscillator with 'whispering gallery' resonator

International Nuclear Information System (INIS)

Kirichenko, A.Ya.; Prokopenko, Yu.V.; Filippov, Yu.F.; Lonin, Yu.F.; Papkovich, V.G.; Ponomarev, A.G.; Prokopenko, Yu.V.; Uvarov, V.T.

2010-01-01

It was presented researches of a generation of microwave radiation into system with azimuthally periodical relativistic electron beam current that excites a high-Q quasi-optical dielectric resonator. The Eigen parameters of cylindrical Teflon resonator were determined by numerical computation. Registration of the microwave radiation realizes by a crystal set of 8-mm wavelength range. Research projects of microwave oscillators with high-Q resonators, in which 'whispering gallery' oscillations are excited by an electron flow, are presented. Multiresonator oscillators ideology is based on principles of microwave generation in klystrons with both subcritical and supercritical electron beams currents.

Ramifide resonators for cyclotrons

International Nuclear Information System (INIS)

Smirnov, Yu.V.

2000-01-01

The resonators with the conductors ramified form for cyclotrons are systematized and separated into the self-contained class - the ramified resonators for cyclotrons (Carr). The ramified resonators are compared with the quarter-wave and half-wave nonramified resonators, accomplished from the transmitting lines fragments. The CRR are classified into two types: ones with the additional structural element, switched in parallel and in series. The CRR may include several additional structural elements. The CRR calculations may be concluded by analytical methods - the method of matrix calculation or the method of telegraph equations and numerical methods - by means of the ISFEL3D, MAFIA and other programs [ru

Effects of KCNQ channel modulators on the M-type potassium current in primate retinal pigment epithelium.

Science.gov (United States)

Pattnaik, Bikash R; Hughes, Bret A

2012-03-01

Recently, we demonstrated the expression of KCNQ1, KCNQ4, and KCNQ5 transcripts in monkey retinal pigment epithelium (RPE) and showed that the M-type current in RPE cells is blocked by the specific KCNQ channel blocker XE991. Using patch-clamp electrophysiology, we investigated the pharmacological sensitivity of the M-type current in isolated monkey RPE cells to elucidate the subunit composition of the channel. Most RPE cells exhibited an M-type current with a voltage for half-maximal activation of approximately -35 mV. The M-type current activation followed a double-exponential time course and was essentially complete within 1 s. The M-type current was inhibited by micromolar concentrations of the nonselective KCNQ channel blockers linopirdine and XE991 but was relatively insensitive to block by 10 μM chromanol 293B or 135 mM tetraethylammonium (TEA), two KCNQ1 channel blockers. The M-type current was activated by 1) 10 μM retigabine, an opener of all KCNQ channels except KCNQ1, 2) 10 μM zinc pyrithione, which augments all KCNQ channels except KCNQ3, and 3) 50 μM N-ethylmaleimide, which activates KCNQ2, KCNQ4, and KCNQ5, but not KCNQ1 or KCNQ3, channels. Application of cAMP, which activates KCNQ1 and KCNQ4 channels, had no significant effect on the M-type current. Finally, diclofenac, which activates KCNQ2/3 and KCNQ4 channels but inhibits KCNQ5 channels, inhibited the M-type current in the majority of RPE cells but activated it in others. The results indicate that the M-type current in monkey RPE is likely mediated by channels encoded by KCNQ4 and KCNQ5 subunits.

Transit time for resonant tunneling

International Nuclear Information System (INIS)

Garcia Calderon, G.; Rubio, A.

1990-09-01

This work considers properties of the partial widths in one dimensional elastic resonant tunneling in order to propose a transit-time τ tr = (h/2π)/Γ n T res ) where Γ n is the elastic width and T res the transmission coefficient at resonance energy. This time is interpreted as an average over the resonance energy width. It is shown that the tunneling current density integrated across a sharp resonance is inversely proportional to τ tr . This transit time may be much larger than the values predicted by other definitions. (author). 20 refs

Disparities in current cigarette smoking prevalence by type of disability, 2009-2011.

Science.gov (United States)

Courtney-Long, Elizabeth; Stevens, Alissa; Caraballo, Ralph; Ramon, Ismaila; Armour, Brian S

2014-05-01

Smoking, the leading cause of disease and death in the United States, has been linked to a number of health conditions including cancer and cardiovascular disease. While people with a disability have been shown to be more likely to report smoking, little is known about the prevalence of smoking by type of disability, particularly for adults younger than 50 years of age. We used data from the 2009-2011 National Health Interview Survey to estimate the prevalence of smoking by type of disability and to examine the association of functional disability type and smoking among adults aged 18-49 years. Adults with a disability were more likely than adults without a disability to be current smokers (38.8% vs. 20.7%, p<0.001). Among adults with disabilities, the prevalence of smoking ranged from 32.4% (self-care difficulty) to 43.8% (cognitive limitation). When controlling for sociodemographic characteristics, having a disability was associated with statistically significantly higher odds of current smoking (adjusted odds ratio = 1.57, 95% confidence interval 1.40, 1.77). The prevalence of current smoking for adults was higher for every functional disability type than for adults without a disability. By understanding the association between smoking and disability type among adults younger than 50 years of age, resources for cessation services can be better targeted during the ages when increased time for health improvement can occur.

A Linearized Large Signal Model of an LCL-Type Resonant Converter

Directory of Open Access Journals (Sweden)

Hong-Yu Li

2015-03-01

Full Text Available In this work, an LCL-type resonant dc/dc converter with a capacitive output filter is modeled in two stages. In the first high-frequency ac stage, all ac signals are decomposed into two orthogonal vectors in a synchronous rotating d–q frame using multi-frequency modeling. In the dc stage, all dc quantities are represented by their average values with average state-space modeling. A nonlinear two-stage model is then created by means of a non-linear link. By aligning the transformer voltage on the d-axis, the nonlinear link can be eliminated, and the whole converter can be modeled by a single set of linear state-space equations. Furthermore, a feedback control scheme can be formed according to the steady-state solutions. Simulation and experimental results have proven that the resulted model is good for fast simulation and state variable estimation.

Influence of Load and Stirrer Type on Current, Temperature and ...

African Journals Online (AJOL)

Influence of Load and Stirrer Type on Current, Temperature and Revolution Per Minute ... Log in or Register to get access to full text downloads. ... Economically, small scale processor can aord to run these mixers which was estimated to ...

A Highly Robust Single-Loop Current Control Scheme for Grid-Connected Inverter with an Improved LCCL Filter Configuration

DEFF Research Database (Denmark)

Pan, Donghua; Ruan, Xinbo; Wang, Xiongfei

2018-01-01

Single-loop current control is an attractive scheme for the LCL-type grid-connected inverter due to its simplicity and low cost. However, conventional single-loop control schemes, which command either the inverter current or the grid current, are subject to the specific resonance frequency regions....... The weighted average current control, which splits the filter capacitor into two parts (in form of an LCCL filter) and commands the current flowing between these two parts, is independent of the resonance frequency, but on the other hand, it is limited by the poor sensitivity to the grid impedance variation...... and weak stability in the grid current. These limitations are comprehensively explained in this paper and then addressed by identifying that the single-loop weighted average current control is equivalent to the dual-loop grid current control with an inherent capacitor current active damping. By tuning...

Application of Long-Range Surface Plasmon Resonance for ABO Blood Typing

Directory of Open Access Journals (Sweden)

Wanida Tangkawsakul

2016-01-01

Full Text Available In this study, we demonstrate a long-range surface plasmon resonance (LR-SPR biosensor for the detection of whole cell by captured antigens A and B on the surface of red blood cells (RBCs as a model. The LR-SPR sensor chip consists of high-refractive index glass, a Cytop film layer, and a thin gold (Au film, which makes the evanescent field intensity and the penetration depth longer than conventional SPR. Therefore, the LR-SPR biosensor has improved capability for detecting large analytes, such as RBCs. The antibodies specific to blood group A and group B (Anti-A and Anti-B are covalently immobilized on a grafting self-assembled monolayer (SAM/Au surface on the biosensor. For blood typing, RBC samples can be detected by the LR-SPR biosensor through a change in the refractive index. We determined that the results of blood typing using the LR-SPR biosensor are consistent with the results obtained from the agglutination test. We obtained the lowest detection limits of 1.58 × 105 cells/ml for RBC-A and 3.83 × 105 cells/ml for RBC-B, indicating that the LR-SPR chip has a higher sensitivity than conventional SPR biosensors (3.3 × 108 cells/ml. The surface of the biosensor can be efficiently regenerated using 20 mM NaOH. In summary, as the LR-SPR technique is sensitive and has a simple experimental setup, it can easily be applied for ABO blood group typing.

Deterministic Many-Resonator W Entanglement of Nearly Arbitrary Microwave States via Attractive Bose-Hubbard Simulation

Directory of Open Access Journals (Sweden)

A. A. Gangat

2013-08-01

Full Text Available Multipartite entanglement of large numbers of physically distinct linear resonators is of both fundamental and applied interest, but there have been no feasible proposals to date for achieving it. At the same time, the Bose-Hubbard model with attractive interactions (ABH is theoretically known to have a phase transition from the superfluid phase to a highly entangled nonlocal superposition, but observation of this phase transition has remained out of experimental reach. In this theoretical work, we jointly address these two problems by (1 proposing an experimentally accessible quantum simulation of the ABH phase transition in an array of tunably coupled superconducting circuit microwave resonators and (2 incorporating the simulation into a highly scalable protocol that takes as input any microwave-resonator state with negligible occupation of number states |0⟩ and |1⟩ and nonlocally superposes it across the whole array of resonators. The large-scale multipartite entanglement produced by the protocol is of the W type, which is well known for its robustness. The protocol utilizes the ABH phase transition to generate the multipartite entanglement of all of the resonators in parallel, and is therefore deterministic and permits an increase in resonator number without any increase in protocol complexity; the number of resonators is limited instead by system characteristics such as resonator-frequency disorder and inter-resonator coupling strength. Only one local and two global controls are required for the protocol. We numerically demonstrate the protocol with realistic system parameters and estimate that current experimental capabilities can realize the protocol with high fidelity for greater than 40 resonators. Because superconducting-circuit microwave resonators are capable of interfacing with other devices and platforms such as mechanical resonators and (potentially optical fields, this proposal provides a route toward large-scale W-type

Low-temperature-compatible tunneling-current-assisted scanning microwave microscope utilizing a rigid coaxial resonator.

Science.gov (United States)

Takahashi, Hideyuki; Imai, Yoshinori; Maeda, Atsutaka

2016-06-01

We present a design for a tunneling-current-assisted scanning near-field microwave microscope. For stable operation at cryogenic temperatures, making a small and rigid microwave probe is important. Our coaxial resonator probe has a length of approximately 30 mm and can fit inside the 2-in. bore of a superconducting magnet. The probe design includes an insulating joint, which separates DC and microwave signals without degrading the quality factor. By applying the SMM to the imaging of an electrically inhomogeneous superconductor, we obtain the spatial distribution of the microwave response with a spatial resolution of approximately 200 nm. Furthermore, we present an analysis of our SMM probe based on a simple lumped-element circuit model along with the near-field microwave measurements of silicon wafers having different conductivities.

Parameter dependence of resonant spin torque magnetization reversal

International Nuclear Information System (INIS)

Fricke, L.; Serrano-Guisan, S.; Schumacher, H.W.

2012-01-01

We numerically study ultra fast resonant spin torque (ST) magnetization reversal in magnetic tunneling junctions (MTJ) driven by current pulses having a direct current (DC) and a resonant alternating current (AC) component. The precessional ST dynamics of the single domain MTJ free layer cell are modeled in the macro spin approximation. The energy efficiency, reversal time, and reversal reliability are investigated under variation of pulse parameters like direct and AC current amplitude, AC frequency and AC phase. We find a range of AC and direct current amplitudes where robust resonant ST reversal is obtained with faster switching time and reduced energy consumption per pulse compared to purely direct current ST reversal. However, for a certain range of AC and direct current amplitudes a strong dependence of the reversal properties on AC frequency and phase is found. Such regions of unreliable reversal must be avoided for ST memory applications.

Parameter dependence of resonant spin torque magnetization reversal

Science.gov (United States)

Fricke, L.; Serrano-Guisan, S.; Schumacher, H. W.

2012-04-01

We numerically study ultra fast resonant spin torque (ST) magnetization reversal in magnetic tunneling junctions (MTJ) driven by current pulses having a direct current (DC) and a resonant alternating current (AC) component. The precessional ST dynamics of the single domain MTJ free layer cell are modeled in the macro spin approximation. The energy efficiency, reversal time, and reversal reliability are investigated under variation of pulse parameters like direct and AC current amplitude, AC frequency and AC phase. We find a range of AC and direct current amplitudes where robust resonant ST reversal is obtained with faster switching time and reduced energy consumption per pulse compared to purely direct current ST reversal. However, for a certain range of AC and direct current amplitudes a strong dependence of the reversal properties on AC frequency and phase is found. Such regions of unreliable reversal must be avoided for ST memory applications.

First results with the yin-yang type electron cyclotron resonance ion source

International Nuclear Information System (INIS)

Suominen, P.; Ropponen, T.; Koivisto, H.

2007-01-01

Highly charged heavy-ion beams are often produced with Electron Cyclotron Resonance Ion Sources (ECRIS). The so-called conventional minimum-B ECRIS design includes two solenoid magnets and a multipole magnet (usually a hexapole). A minimum-B configuration can also be formed with 'yin-yang' ('baseball') type coils. Such a magnetic field configuration has been extensively tested in magnetic fusion experiments but not for the production of highly charged heavy ions. The application of the afore-mentioned coil structure to the production of multiply charged ion beams was studied. In this paper we present a design of a yin-yang type ion source known as the ARC-ECRIS and some preliminary experimental results. As a result of this work it was found that the ARC-ECRIS plasma is stable and capable of producing multiply charged ions. Many compromises were made in order to keep the costs of the prototype low. As a consequence, significant improvement can be expected in performance if the plasma size is increased and magnetic confinement is improved. At the end of this article an evolution model of the ARC-ECRIS and some future prospects are presented

Resonance Interaction of Multi-Parallel Grid-Connected Inverters with LCL Filter

DEFF Research Database (Denmark)

Lu, Minghui; Wang, Xiongfei; Loh, Poh Chiang

2017-01-01

This letter investigates the resonance characteristics and stability problem caused by the interactions of multiparallel LCL-filtered inverters. Compared to single grid-connected inverter, the multiinverter system presents a more challenging resonance issue, where the inverter interactions may...... excite multiple resonances at various frequencies. This letter proposes a modeling and analysis method based on the current separation scheme. It reveals that an interactive resonant current that circulates between the paralleled three-phase inverters may arise, depending on the current distribution...

Object-oriented magnetic resonance classes and objects, calculations and computations

CERN Document Server

Mehring, Michael

2001-01-01

This book presents, for the first time, a unified treatment of the quantum mechanisms of magnetic resonance, including both nuclear magnetic resonance (NMR) and electron spin resonance (ESR). Magnetic resonance is perhaps the most advanced type of spectroscopy and it is applied in biology, chemistry, physics, material science, and medicine. If applied in conjunction with spectroscopy, the imaging version of magnetic resonance has no counterpart in any type of experimental technique. The authors present explanations and applications from fundamental to advanced levels. Additionally, the

Design of ultrathin dual-resonant reflective polarization converter with customized bandwidths

Science.gov (United States)

Kundu, Debidas; Mohan, Akhilesh; Chakrabarty, Ajay

2017-10-01

In this paper, an ultrathin dual-resonant reflective polarization converter is proposed to obtain customized bandwidths using precise space-filling technique to its top geometry. The unit cell of the dual-resonant prototype consists of conductive square ring with two diagonally arranged slits, supported by metal-backed thin dielectric layer. It offers two narrow bands with fractional bandwidths of 3.98 and 6.65% and polarization conversion ratio (PCR) of 97.16 and 98.87% at 4.52 and 6.97 GHz, respectively. The resonances are brought in proximity to each other by changing the length of surface current paths of the two resonances. By virtue of this mechanism, two polarization converters with two different types of bandwidths are obtained. One polarization converter produces a full-width at half-maxima PCR bandwidth of 34%, whereas another polarization converter produces a 90% PCR bandwidth of 19%. All the proposed polarization converters are insensitive to wide variations of incident angle for both TE- and TM-polarized incident waves. Measured results show good agreement with the numerically simulated results.

Apamin does not inhibit human cardiac Na+ current, L-type Ca2+ current or other major K+ currents.

Directory of Open Access Journals (Sweden)

Chih-Chieh Yu

Full Text Available Apamin is commonly used as a small-conductance Ca2+-activated K+ (SK current inhibitor. However, the specificity of apamin in cardiac tissues remains unclear.To test the hypothesis that apamin does not inhibit any major cardiac ion currents.We studied human embryonic kidney (HEK 293 cells that expressed human voltage-gated Na+, K+ and Ca2+ currents and isolated rabbit ventricular myocytes. Whole-cell patch clamp techniques were used to determine ionic current densities before and after apamin administration.Ca2+ currents (CACNA1c+CACNB2b were not affected by apamin (500 nM (data are presented as median [25th percentile;75th percentile] (from -16 [-20;-10] to -17 [-19;-13] pA/pF, P = NS, but were reduced by nifedipine to -1.6 [-3.2;-1.3] pA/pF (p = 0.008. Na+ currents (SCN5A were not affected by apamin (from -261 [-282;-145] to -268 [-379;-132] pA/pF, P = NS, but were reduced by flecainide to -57 [-70;-47] pA/pF (p = 0.018. None of the major K+ currents (IKs, IKr, IK1 and Ito were inhibited by 500 nM of apamin (KCNQ1+KCNE1, from 28 [20]; [37] to 23 [18]; [32] pA/pF; KCNH2+KCNE2, from 28 [24]; [30] to 27 [24]; [29] pA/pF; KCNJ2, from -46 [-48;-40] to -46 [-51;-35] pA/pF; KCND3, from 608 [505;748] to 606 [454;684]. Apamin did not inhibit the INa or ICaL in isolated rabbit ventricular myocytes (INa, from -67 [-75;-59] to -68 [-71;-59] pA/pF; ICaL, from -16 [-17;-14] to -14 [-15;-13] pA/pF, P = NS for both.Apamin does not inhibit human cardiac Na+ currents, L-type Ca2+ currents or other major K+ currents. These findings indicate that apamin is a specific SK current inhibitor in hearts as well as in other organs.

Resonance phenomenon in classical cepheids

International Nuclear Information System (INIS)

Takeuti, Mine; Aikawa, Toshiki

1981-01-01

To investigate resonance phenomenon in classical cepheids, the non-linear radial oscillation of stars is studied based on the assumption that the non-adiabatic perturbation is expressed in terms of van der Pol's type damping. Two- and three-wave resonance in this system is applied to classical cepheids to describe their bump and double-mode behavior. The phase of bump and the depression of amplitude are explained for bump cepheids. The double-periodicity is shown by the enhancement of the third overtone in three-wave resonance. Non-linear effect on resonant period is also discussed briefly. (author)

Quantum Graphs And Their Resonance Properties

International Nuclear Information System (INIS)

Lipovsky, J.

2016-01-01

In the current review, we study the model of quantum graphs. We focus mainly on the resonance properties of quantum graphs. We define resolvent and scattering resonances and show their equivalence. We present various results on the asymptotics of the number of resolvent resonances in both non-magnetic and magnetic quantum graphs and find bounds on the coefficient by the leading term of the asymptotics. We explain methods how to find the spectral and resonance condition. Most of the notions and theorems are illustrated in examples. We show how to find resonances numerically and, in a simple example, we find trajectories of resonances in the complex plane. We discuss Fermi’s golden rule for quantum graphs and distribution of the mean intensity for the topological resonances. (author)

Impurity Resonant States p-type Doping in Wide-Band-Gap Nitrides

Science.gov (United States)

Liu, Zhiqiang; Yi, Xiaoyan; Yu, Zhiguo; Yuan, Gongdong; Liu, Yang; Wang, Junxi; Li, Jinmin; Lu, Na; Ferguson, Ian; Zhang, Yong

2016-01-01

In this work, a new strategy for achieving efficient p-type doping in high bandgap nitride semiconductors to overcome the fundamental issue of high activation energy has been proposed and investigated theoretically, and demonstrated experimentally. Specifically, in an AlxGa1-xN/GaN superlattice structure, by modulation doping of Mg in the AlxGa1-xN barriers, high concentration of holes are generated throughout the material. A hole concentration as high as 1.1 × 1018 cm-3 has been achieved, which is about one order of magnitude higher than that typically achievable by direct doping GaN. Results from first-principle calculations indicate that the coupling and hybridization between Mg 2p impurity and the host N 2p orbitals are main reasons for the generation of resonant states in the GaN wells, which further results in the high hole concentration. We expect this approach to be equally applicable for other high bandgap materials where efficient p-type doing is difficult. Furthermore, a two-carrier-species Hall-effect model is proposed to delineate and discriminate the characteristics of the bulk and 2D hole, which usually coexist in superlattice-like doping systems. The model reported here can also be used to explain the abnormal freeze-in effect observed in many previous reports.

Synchrobetatron resonances

International Nuclear Information System (INIS)

Anon.

1977-01-01

At the 1975 Particle Accelerator Conference it was reported that a class of resonances were observed in SPEAR II that had not appeared before in SPEAR I. These resonances occur when the betatron oscillation wave numbers ν/sub x/ or ν/sub y/ and the synchrotron wave number ν/sub s/ satisfy the relation (ν/sub x,y/ - mν/sub s/) = 5, with m an integer denoting the m/sup th/ satellite. The main difference between SPEAR II and SPEAR I is the value of ν/sub s/, which in SPEAR II is approximately 0.04, an order of magnitude larger than in SPEAR I. An ad hoc meeting was held at the 1975 Particle Accelerator Conference, where details of the SPEAR II results were presented and various possible mechanisms for producing these resonances were discussed. Later, experiments were performed at SPEAR to identify the mechanism believed to be the most likely explanation. Some of the current experimental knowledge and theoretical views on the source of these resonances are presented

Magnetic resonance imaging of the prostate

DEFF Research Database (Denmark)

Iversen, P; Kjaer, L; Thomsen, C

1988-01-01

Magnetic resonance imaging offers new possibilities in investigation of the prostate gland. Current results of imaging and tissue discrimination in the evaluation of prostatic disease are reviewed. Magnetic resonance imaging may be useful in the staging of carcinoma of the prostate....

Electro-Mechanical Resonance Curves

Science.gov (United States)

Greenslade, Thomas B., Jr.

2018-01-01

Recently I have been investigating the frequency response of galvanometers. These are direct-current devices used to measure small currents. By using a low-frequency function generator to supply the alternating-current signal and a stopwatch smartphone app to measure the period, I was able to take data to allow a resonance curve to be drawn. This…

Magnetic resonance imaging of the human female breast. Current status and pathologic correlations

International Nuclear Information System (INIS)

Powell, D.E.; Stelling, C.B.

1988-01-01

In the field of breast cancer, attention has focused on the problem of detection and diagnosis of the tumor in its early stages as the best means of reducing mortality. Many imaging modalities have been applied to breast cancer, including mammography, ultrasonography, computerized tomography, and thermography. More recently interest has turned to NMR or magnetic resonance (MR) imaging (as it is termed in more current usage) for the detection of breast disease and particularly carcinoma of the breast. This review discusses the present role of MR imaging in the diagnosis of breast lesions based on work from several institutions. Possible areas for future development to increase the usefulness of MR as a diagnostic modality are discussed. For those not familiar with terminology used in the field of MR, a short glossary of terms is supplied at the end of the chapter. Some general references on MR imaging are give at the end of the references for those wishing to review the subject in general

Disparities in Current Cigarette Smoking Prevalence by Type of Disability, 2009–2011

Science.gov (United States)

Stevens, Alissa; Caraballo, Ralph; Ramon, Ismaila; Armour, Brian S.

2014-01-01

Objectives Smoking, the leading cause of disease and death in the United States, has been linked to a number of health conditions including cancer and cardiovascular disease. While people with a disability have been shown to be more likely to report smoking, little is known about the prevalence of smoking by type of disability, particularly for adults younger than 50 years of age. Methods We used data from the 2009–2011 National Health Interview Survey to estimate the prevalence of smoking by type of disability and to examine the association of functional disability type and smoking among adults aged 18–49 years. Results Adults with a disability were more likely than adults without a disability to be current smokers (38.8% vs. 20.7%, pdisability was associated with statistically significantly higher odds of current smoking (adjusted odds ratio = 1.57, 95% confidence interval 1.40, 1.77). Conclusions The prevalence of current smoking for adults was higher for every functional disability type than for adults without a disability. By understanding the association between smoking and disability type among adults younger than 50 years of age, resources for cessation services can be better targeted during the ages when increased time for health improvement can occur. PMID:24791023

Modeling of Tsunami Currents in Harbors

Science.gov (United States)

Lynett, P. J.

2010-12-01

Extreme events, such as large wind waves and tsunamis, are well recognized as a damaging hazard to port and harbor facilities. Wind wave events, particularly those with long period spectral components or infragravity wave generation, can excite resonance inside harbors leading to both large vertical motions and strong currents. Tsunamis can cause great damage as well. The geometric amplification of these very long waves can create large vertical motions in the interior of a harbor. Additionally, if the tsunami is composed of a train of long waves, which it often is, resonance can be easily excited. These long wave motions create strong currents near the node locations of resonant motions, and when interacting with harbor structures such as breakwaters, can create intense turbulent rotational structures, typical in the form of large eddies or gyres. These gyres have tremendous transport potential, and have been observed to break mooring lines, and even cause ships to be trapped inside the rotation, moving helplessly with the flow until collision, grounding, or dissipation of the eddy (e.g. Okal et al., 2006). This presentation will introduce the traditional theory used to predict wave impacts on harbors, discussing both how these models are practically useful and in what types of situations require a more accurate tool. State-of-the-art numerical models will be introduced, with a focus on recent developments in Boussinesq-type modeling. The Boussinesq equations model can account the dispersive, turbulent and rotational flow properties frequently observed in nature. Also they have the ability to coupling currents and waves and can predict nonlinear wave propagation over uneven bottom from deep (or intermediate) water area to shallow water area. However, during the derivation of a 2D-horizontal equation set, some 3D flow features, such those driven by as the dispersive stresses and the effects of the unresolved small scale 3D turbulence, are excluded. Consequently

Development of a current-type PWM converter with high power factor. 1

International Nuclear Information System (INIS)

Miura, Yushi; Matsukawa, Makoto; Miyachi, Kengo; Kimura, Toyoaki

1998-01-01

A power supply system for superconducting poloidal field coils of a next generation tokamak-type fusion device can be operated on the relatively low voltage for the duration of discharge except the plasma initiation. In the case of the conventional phase-controlled thyristor converters are adopted in such a system, the input power factor would be low in average, and a reactive power fluctuation caused by the change of DC output voltage may produce serious effects on the commercial transmission line. From the above viewpoint, a current-type PWM (Pulse Width Modulation) converter, which can work with the power factor of unity for the input power, is regarded as one of the promising candidates of the converters for the power supplies of next generation fusion devices. Hence, a 100kW-class current-type PWM converter has been developed by using IGBT (Insulated Gate Bipolar Transistor) as switching devices. In this development, the basic performance has been preliminary investigated whether this converter is applicable to the power supply for the next generation fusion device. In addition, two different PWM control methods were examined whether these methods can realize a unit power factor and suppress the transient oscillation of converter input current at the same time in case that the reference of DC output current is changed rapidly. (author)

Magnetic resonance imaging of the prostate

DEFF Research Database (Denmark)

Iversen, P; Kjaer, L; Thomsen, C

1987-01-01

Magnetic resonance imaging offers new possibilities in the investigation of the prostate. The current results of imaging and tissue discrimination in the evaluation of prostatic disease are reviewed. Magnetic resonance imaging may be of value in the staging of carcinoma of the prostate....

Piezoelectric MEMS resonators

CERN Document Server

Piazza, Gianluca

2017-01-01

This book introduces piezoelectric microelectromechanical (pMEMS) resonators to a broad audience by reviewing design techniques including use of finite element modeling, testing and qualification of resonators, and fabrication and large scale manufacturing techniques to help inspire future research and entrepreneurial activities in pMEMS. The authors discuss the most exciting developments in the area of materials and devices for the making of piezoelectric MEMS resonators, and offer direct examples of the technical challenges that need to be overcome in order to commercialize these types of devices. Some of the topics covered include: Widely-used piezoelectric materials, as well as materials in which there is emerging interest Principle of operation and design approaches for the making of flexural, contour-mode, thickness-mode, and shear-mode piezoelectric resonators, and examples of practical implementation of these devices Large scale manufacturing approaches, with a focus on the practical aspects associate...

Are Participants Aware of the Type and Intensity of Transcranial Direct Current Stimulation?

Directory of Open Access Journals (Sweden)

Matthew F Tang

Full Text Available Transcranial direct current stimulation (tDCS is commonly used to alter cortical excitability but no experimental study has yet determined whether human participants are able to distinguish between the different types (anodal, cathodal, and sham of stimulation. If they can then they are not blind to experimental conditions. We determined whether participants could identify different types of stimulation (anodal, cathodal, and sham and current strengths after experiencing the sensations of stimulation during current onset and offset (which are associated with the most intense sensations in Experiment 1 and also with a prolonged period of stimulation in Experiment 2. We first familiarized participants with anodal, cathodal, and sham stimulation at both 1 and 2 mA over either primary motor or visual cortex while their sensitivity to small changes in visual stimuli was assessed. The different stimulation types were then applied for a short (Experiment 1 or extended (Experiment 2 period with participants indicating the type and strength of the stimulation on the basis of the evoked sensations. Participants were able to identify the intensity of stimulation with shorter, but not longer periods, of stimulation at better than chance levels but identification of the different stimulation types was at chance levels. This result suggests that even after exposing participants to stimulation, and ensuring they are fully aware of the existence of a sham condition, they are unable to identify the type of stimulation from transient changes in stimulation intensity or from more prolonged stimulation. Thus participants are able to identify intensity of stimulation but not the type of stimulation.

High current density M-type cathodes for vacuum electron devices

International Nuclear Information System (INIS)

Li Ji; Yu Zhiqiang; Shao Wensheng; Zhang Ke; Gao Yujuan; Yuan Haiqing; Wang Hui; Huang Kaizhi; Chen Qilue; Yan Suqiu; Cai Shaolun

2005-01-01

We investigated high current density emission capabilities of M-type cathodes used for vacuum electron devices (VEDs). The experimental results of emission and lifetime evaluating in both close-spaced diode structure and electron gun testing vehicles are given. Emission current densities measured in the diode structure at 1020 deg. C Br in the CW mode were above 10 A/cm 2 ; while in electron gun testing vehicles, emission current densities were above 8 A/cm 2 in CW mode and above 32 A/cm 2 in pulsed mode, respectively. The current density above 94 A/cm 2 has been acquired in no. 0306 electron gun vehicle while the practical temperature is 1060 deg. C Br . For a comparison some of the data from I-scandate cathodes are presented. Finally, several application examples in practical travelling wave tubes (TWTs) and multi beam klystrons (MBKs) are also reported

Characterising gas behaviour during gas-liquid co-current up-flow in packed beds using magnetic resonance imaging

OpenAIRE

Collins, James HP; Sederman, Andrew John; Gladden, Lynn Faith; Afeworki, Mobae; Kushnerick, J Douglas; Thomann, Hans

2016-01-01

Magnetic resonance (MR) imaging techniques have been used to study gas phase dynamics during co-current up-flow in a column of inner diameter 43 mm, packed with spherical non-porous elements of diameters of 1.8, 3 and 5 mm. MR measurements of gas hold-up, bubble-size distribution, and bubble-rise velocities were made as a function of flow rate and packing size. Gas and liquid flow rates were studied in the range of 20–250 cm3 s−1 and 0–200 cm3 min−1, respectively. The gas hold-up within the b...

Direct current modulation of spin-Hall-induced spin torque ferromagnetic resonance in platinum/permalloy bilayer thin films

Science.gov (United States)

Hirayama, Shigeyuki; Mitani, Seiji; Otani, YoshiChika; Kasai, Shinya

2018-06-01

We examined the spin-Hall-induced spin torque ferromagnetic resonance (ST-FMR) in platinum/permalloy bilayer thin films under bias direct current (DC). The bias DC modulated the symmetric components of the ST-FMR spectra, while no dominant modulation was found in the antisymmetric components. A detailed analysis in combination with simple model calculations clarified that the major origin of the modulation can be attributed to the DC resistance change under the precessional motion of magnetization. This effect is the second order contribution for the precession angle, even though the contribution can be comparable to the rectification voltage under some specific conditions.

Six types Monte Carlo for estimating the current unavailability of Markov system with dependent repair

International Nuclear Information System (INIS)

Xiao Gang; Li Zhizhong

2004-01-01

Based on integral equaiton describing the life-history of Markov system, six types of estimators of the current unavailability of Markov system with dependent repair are propounded. Combining with the biased sampling of state transition time of system, six types of Monte Carlo for estimating the current unavailability are given. Two numerical examples are given to deal with the variances and efficiencies of the six types of Monte Carlo methods. (authors)

Magnetic Resonance Elastography and Other Magnetic Resonance Imaging Techniques in Chronic Liver Disease: Current Status and Future Directions

Science.gov (United States)

Tan, Cher Heng; Venkatesh, Sudhakar Kundapur

2016-01-01

Recent advances in the noninvasive imaging of chronic liver disease have led to improvements in diagnosis, particularly with magnetic resonance imaging (MRI). A comprehensive evaluation of the liver may be performed with the quantification of the degree of hepatic steatosis, liver iron concentration, and liver fibrosis. In addition, MRI of the liver may be used to identify complications of cirrhosis, including portal hypertension, ascites, and the development of hepatocellular carcinoma. In this review article, we discuss the state of the art techniques in liver MRI, namely, magnetic resonance elastography, hepatobiliary phase MRI, and liver fat and iron quantification MRI. The use of these advanced techniques in the management of chronic liver diseases, including non-alcoholic fatty liver disease, will be elaborated. PMID:27563019

Resonant tunnelling from nanometre-scale silicon field emission cathodes

International Nuclear Information System (INIS)

Johnson, S.; Markwitz, A.

2005-01-01

In this paper we report the field emission properties of self-assembled silicon nanostructures formed on an n-type silicon (100) substrate by electron beam annealing. The nanostructures are square based, with an average height of 8 nm and are distributed randomly over the entire substrate surface. Following conditioning, the silicon nanostructure field emission characteristics become stable and reproducible with electron emission occurring for fields as low as 3 Vμm-1. At higher fields, a superimposed on a background current well described by conventional Fowler-Nordheim theory. These current peaks are understood to result from enhanced tunnelling through resonant states formed at the substrate-nanostructure and nanostructure-vacuum interface. (author). 13 refs., 3 figs

Development of a Direct Methanol Fuel Cell with Lightweight Disc Type Current Collectors

Directory of Open Access Journals (Sweden)

Yean-Der Kuan

2014-05-01

Full Text Available The direct methanol fuel cell (DMFC adopts methanol solution as a fuel suitable for low power portable applications. A miniature, lightweight, passive air-breathing design is therefore desired. This paper presents a novel planar disc-type DMFC with multiple cells containing a novel developed lightweight current collector at both the anode and cathode sides. The present lightweight current collector adopts FR4 Glass/Epoxy as the substrate with the current collecting areas located at the corresponding membrane electrolyte assembly (MEA areas. The current collecting areas are fabricated by sequentially coating a corrosion resistant layer and electrical conduction layer via the thermal evaporation technique. The anode current collector has carved flow channels for fuel transport and production. The cathode current collector has drilled holes for passive air breathing. In order to ensure feasibility in the present concept a 3-cell prototype DMFC module with lightweight disc type current collectors is designed and constructed. Experiments were conducted to measure the cell performance. The results show that the highest cell power output is 54.88 mW·cm−2 and successfully demonstrate the feasibility of this novel design.

Resonant acoustic radiation force optical coherence elastography

OpenAIRE

Qi, Wenjuan; Li, Rui; Ma, Teng; Li, Jiawen; Kirk Shung, K.; Zhou, Qifa; Chen, Zhongping

2013-01-01

We report on a resonant acoustic radiation force optical coherence elastography (ARF-OCE) technique that uses mechanical resonant frequency to characterize and identify tissues of different types. The linear dependency of the resonant frequency on the square root of Young's modulus was validated on silicone phantoms. Both the frequency response spectrum and the 3D imaging results from the agar phantoms with hard inclusions confirmed the feasibility of deploying the resonant frequency as a mec...

Induced Magnetic Anisotropy in Liquid Crystals Doped with Resonant Semiconductor Nanoparticles

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Vicente Marzal

2016-01-01

Full Text Available Currently, there are many efforts to improve the electrooptical properties of liquid crystals by means of doping them with different types of nanoparticles. In addition, liquid crystals may be used as active media to dynamically control other interesting phenomena, such as light scattering resonances. In this sense, mixtures of resonant nanoparticles hosted in a liquid crystal could be a potential metamaterial with interesting properties. In this work, the artificial magnetism induced in a mixture of semiconductor nanoparticles surrounded by a liquid crystal is analyzed. Effective magnetic permeability of mixtures has been obtained using the Maxwell-Garnett effective medium theory. Furthermore, permeability variations with nanoparticles size and their concentration in the liquid crystal, as well as the magnetic anisotropy, have been studied.

OPTIMIZATION OF HEMISPHERICAL RESONATOR GYROSCOPE STANDING WAVE PARAMETERS

Directory of Open Access Journals (Sweden)

Olga Sergeevna Khalyutina

2017-01-01

Full Text Available Traditionally, the problem of autonomous navigation is solved by dead reckoning navigation flight parameters (NFP of the aircraft (AC. With increasing requirements to accuracy of definition NFP improved the sensors of the prima- ry navigation information: gyroscopes and accelerometers. the gyroscopes of a new type, the so-called solid-state wave gyroscopes (SSVG are currently developed and put into practice. The work deals with the problem of increasing the accu- racy of measurements of angular velocity of the hemispherical resonator gyroscope (HRG. The reduction in the accuracy characteristics of HRG is caused by the presence of defects in the distribution of mass in the volume of its design. The syn- thesis of control system for optimal damping of the distortion parameters of the standing wave due to the influence of the mass defect resonator is adapted. The research challenge was: to examine and analytically offset the impact of the standing wave (amplitude and frequency parameters defect. Research was performed by mathematical modeling in the environment of SolidWorks Simulation for the case when the characteristics of the sensitive element of the HRG met the technological drawings of a particular type of resonator. The method of the inverse dynamics was chosen for synthesis. The research re- sults are presented in graphs the amplitude-frequency characteristics (AFC of the resonator output signal. Simulation was performed for the cases: the perfect distribution of weight; the presence of the mass defect; the presence of the mass defects are shown using the synthesized control action. Evaluating the effectiveness of the proposed control algorithm is deter- mined by the results of the resonator output signal simulation provided the perfect constructive and its performance in the presence of a mass defect in it. It is assumed that the excitation signals are standing waves in the two cases are identical in both amplitude and frequency. In this

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.

Doubly-resonant coherent excitation of HCI planar channeled in a Si crystal

International Nuclear Information System (INIS)

Nakano, Y; Masugi, S; Muranaka, T; Azuma, T; Kondo, C; Hatakeyama, A; Komaki, K; Yamazaki, Y; Takada, E; Murakami, T

2007-01-01

We investigated resonant coherent excitation of H-like Ar 17+ and He-like Ar 16+ ions planar channeled in a Si crystal under the V-type and ladder-type double resonance conditions. In both cases, we observed distinct enhancement in the ionized fraction of the transmitted ions when the double resonance conditions were satisfied. In the ladder-type configuration, the enhancement indicates that the doubly-excited 2p 2 state of He-like Ar 16+ was produced through doubly-resonant coherent excitation

Gradient-Type Magnetoelectric Current Sensor with Strong Multisource Noise Suppression.

Science.gov (United States)

Zhang, Mingji; Or, Siu Wing

2018-02-14

A novel gradient-type magnetoelectric (ME) current sensor operating in magnetic field gradient (MFG) detection and conversion mode is developed based on a pair of ME composites that have a back-to-back capacitor configuration under a baseline separation and a magnetic biasing in an electrically-shielded and mechanically-enclosed housing. The physics behind the current sensing process is the product effect of the current-induced MFG effect associated with vortex magnetic fields of current-carrying cables (i.e., MFG detection) and the MFG-induced ME effect in the ME composite pair (i.e., MFG conversion). The sensor output voltage is directly obtained from the gradient ME voltage of the ME composite pair and is calibrated against cable current to give the current sensitivity. The current sensing performance of the sensor is evaluated, both theoretically and experimentally, under multisource noises of electric fields, magnetic fields, vibrations, and thermals. The sensor combines the merits of small nonlinearity in the current-induced MFG effect with those of high sensitivity and high common-mode noise rejection rate in the MFG-induced ME effect to achieve a high current sensitivity of 0.65-12.55 mV/A in the frequency range of 10 Hz-170 kHz, a small input-output nonlinearity of <500 ppm, a small thermal drift of <0.2%/℃ in the current range of 0-20 A, and a high common-mode noise rejection rate of 17-28 dB from multisource noises.

Mode Coupling and Nonlinear Resonances of MEMS Arch Resonators for Bandpass Filters

KAUST Repository

Hajjaj, Amal Z.

2017-01-30

We experimentally demonstrate an exploitation of the nonlinear softening, hardening, and veering phenomena (near crossing), where the frequencies of two vibration modes get close to each other, to realize a bandpass filter of sharp roll off from the passband to the stopband. The concept is demonstrated based on an electrothermally tuned and electrostatically driven MEMS arch resonator operated in air. The in-plane resonator is fabricated from a silicon-on-insulator wafer with a deliberate curvature to form an arch shape. A DC current is applied through the resonator to induce heat and modulate its stiffness, and hence its resonance frequencies. We show that the first resonance frequency increases up to twice of the initial value while the third resonance frequency decreases until getting very close to the first resonance frequency. This leads to the phenomenon of veering, where both modes get coupled and exchange energy. We demonstrate that by driving both modes nonlinearly and electrostatically near the veering regime, such that the first and third modes exhibit softening and hardening behavior, respectively, sharp roll off from the passband to the stopband is achievable. We show a flat, wide, and tunable bandwidth and center frequency by controlling the electrothermal actuation voltage.

Light Scattering by a Dielectric Sphere: Perspectives on the Mie Resonances

Directory of Open Access Journals (Sweden)

Dimitrios Tzarouchis

2018-01-01

Full Text Available Light scattering by a small spherical particle, a central topic for electromagnetic scattering theory, is here considered. In this short review, some of the basic features of its resonant scattering behavior are covered. First, a general physical picture is described by a full electrodynamic perspective, the Lorenz–Mie theory. The resonant spectrum of a dielectric sphere reveals the existence of two distinctive types of polarization enhancement: the plasmonic and the dielectric resonances. The corresponding electrostatic (Rayleigh picture is analyzed and the polarizability of a homogeneous spherical inclusion is extracted. This description facilitates the identification of the first type of resonance, i.e., the localized surface plasmon (plasmonic resonance, as a function of the permittivity. Moreover, the electrostatic picture is linked with the plasmon hybridization model through the case of a step-inhomogeneous structure, i.e., a core–shell sphere. The connections between the electrostatic and electrodynamic models are reviewed in the small size limit and details on size-induced aspects, such as the dynamic depolarization and the radiation reaction on a small sphere are exposed through the newly introduced Mie–Padé approximative perspective. The applicability of this approximation is further expanded including the second type of resonances, i.e., the dielectric resonances. For this type of resonances, the Mie–Padé approximation reveals the main character of the two different cases of resonances of either magnetic or electric origin. A unified picture is therefore described encompassing both plasmonic and dielectric resonances, and the resonant conditions of all three different types are extracted as functions of the permittivity and the size of the sphere. Lastly, the directional scattering behavior of the first two dielectric resonances is exposed in a simple manner, namely the Kerker conditions for maximum forward and

Versatile resonance-tracking circuit for acoustic levitation experiments.

Science.gov (United States)

Baxter, K; Apfel, R E; Marston, P L

1978-02-01

Objects can be levitated by radiation pressure forces in an acoustic standing wave. In many circumstances it is important that the standing wave frequency remain locked on an acoustic resonance despite small changes in the resonance frequency. A self-locking oscillator circuit is described which tracks the resonance frequency by sensing the magnitude of the transducer current. The tracking principle could be applied to other resonant systems.

On and off controlled resonant dc-dc power converter

DEFF Research Database (Denmark)

2015-01-01

The present invention relates to a resonant DC-DC power converter comprising an input side circuit comprising a positive and a negative input terminal for receipt of an input voltage or current and an output side circuit comprising positive and negative output terminals for supply of a converter...... output voltage and connection to a converter load. The resonant DC-DC power converter further comprises a rectification circuit connected between an output of a resonant network and the output side circuit. The resonant network is configured for alternatingly being charged from the input voltage...... or current and discharged through the rectification circuit by a first controllable switch arrangement in accordance with a first switch control signal. A second controllable switch arrangement of the resonant DC-DC power converter is configured to select a first impedance characteristic of the resonant...

Nuclear magnetic resonance (NMR) imaging of Arnold-Chiari type I malformation with hydromyelia

International Nuclear Information System (INIS)

DeLaPaz, R.L.; Brady, T.J.; Buonanno, F.S.; New, P.F.; Kistler, J.P.; McGinnis, B.D.; Pykett, I.L.; Taveras, J.M.

1983-01-01

Saturation recovery nuclear magnetic resonance (NMR) images and metrizamide computed tomography (CT) scans were obtained in an adult patient with a clinical history suggestive of syringomyelia. Both NMR and CT studies showed low lying cerebellar tonsils. The CT study demonstrated central cavitation of the spinal cord from the midthoracic to midcervical levels but could not exclude an intramedullary soft tissue mass at the cervico-medullary junction. The NMR images in transverse, coronal, and sagittal planes demonstrated extension of an enlarged central spinal cord cerebrospinal fluid space to the cervico-medullary junction. This was felt to be strong evidence for exclusion of an intramedullary soft tissue mass and in favor of a diagnosis of Arnold-Chiari Type I malformation with hydromyelia. The noninvasive nature of spinal cord and cervico-medullary junction evaluation with NMR is emphasized

Control strategies for DC motors driving rotor dynamic systems through resonance

Science.gov (United States)

Bisoi, Alfa; Samantaray, A. K.; Bhattacharyya, Ranjan

2017-12-01

Rotor dynamic systems require considerably higher power/torque to accelerate through the structural resonance. However, most sources of mechanical power are non-ideal, i.e., they can only provide a limited amount of power. If there is insufficient power to overcome the resonance then the rotor speed may get caught at resonance and the persistent high vibrations can damage the machine. Various proposed solutions to this problem deal with modifications to the mechanical structure and active/semi-active control of structural parameters. This article proposes modification to the prime mover so that peak available power is delivered exactly at the structural resonance frequency. The limited power/non-ideal prime mover considered in this article is a direct current (DC) motor and the structural resonance happens due to forcing from an eccentric rotor disk and vibrations of a flexible weakly damped foundation. Various control strategies to modify the torque-speed characteristics of permanent magnet, shunt and series wound DC motors to promote escape through resonance are considered. Also, the characteristic curves for rotor/motor speed versus the DC supply voltage are obtained for the considered DC motor types from which the unattainable steady angular speeds and the speed jumps due to Sommerfeld effect are computed. Transient simulations are performed using bond graph models for this multi-energy domain (here, electro-mechanical) system. It is shown that a switched control permitting to switch between shunt and series DC motor configurations gives better regulation over the power delivery at the resonant frequency as well as super-critical operating speeds in the neighborhood of structural resonance.

Resonant halide perovskite nanoparticles

Science.gov (United States)

Tiguntseva, Ekaterina Y.; Ishteev, Arthur R.; Komissarenko, Filipp E.; Zuev, Dmitry A.; Ushakova, Elena V.; Milichko, Valentin A.; Nesterov-Mueller, Alexander; Makarov, Sergey V.; Zakhidov, Anvar A.

2017-09-01

The hybrid halide perovskites is a prospective material for fabrication of cost-effective optical devices. Unique perovskites properties are used for solar cells and different photonic applications. Recently, perovskite-based nanophotonics has emerged. Here, we consider perovskite like a high-refractive index dielectric material, which can be considered to be a basis for nanoparticles fabrication with Mie resonances. As a result, we fabricate and study resonant perovskite nanoparticles with different sizes. We reveal, that spherical nanoparticles show enhanced photoluminescence signal. The achieved results lay a cornerstone in the field of novel types of organic-inorganic nanophotonics devices with optical properties improved by Mie resonances.

Feedback control of persistent-current oscillation based on the atomic-clock technique

Science.gov (United States)

Yu, Deshui; Dumke, Rainer

2018-05-01

We propose a scheme of stabilizing the persistent-current Rabi oscillation based on the flux qubit-resonator-atom hybrid structure. The low-Q L C resonator weakly interacts with the flux qubit and maps the persistent-current Rabi oscillation of the flux qubit onto the intraresonator electric field. This oscillating electric field is further coupled to a Rydberg-Rydberg transition of the 87Rb atoms. The Rabi-frequency fluctuation of the flux qubit is deduced from measuring the atomic population via the fluorescence detection and stabilized by feedback controlling the external flux bias. Our numerical simulation indicates that the feedback-control method can efficiently suppress the background fluctuations in the flux qubit, especially in the low-frequency limit. This technique may be extensively applicable to different types of superconducting circuits, paving a way to long-term-coherence superconducting quantum information processing.

A Cell-to-Cell Battery Equalizer With Zero-Current Switching and Zero-Voltage Gap Based on Quasi-Resonant LC Converter and Boost Converter

DEFF Research Database (Denmark)

Shang, Yunlong; Zhang, Chenghui; Cui, Naxin

2015-01-01

these difficulties, an innovative direct cell-to-cell battery equalizer based on quasi-resonant LC converter (QRLCC) and boost DC-DC converter (BDDC) is proposed. The QRLCC is employed to gain zero-current switching (ZCS), leading to a reduction of power losses. The BDDC is employed to enhance the equalization...

Gradient-Type Magnetoelectric Current Sensor with Strong Multisource Noise Suppression

Science.gov (United States)

2018-01-01

A novel gradient-type magnetoelectric (ME) current sensor operating in magnetic field gradient (MFG) detection and conversion mode is developed based on a pair of ME composites that have a back-to-back capacitor configuration under a baseline separation and a magnetic biasing in an electrically-shielded and mechanically-enclosed housing. The physics behind the current sensing process is the product effect of the current-induced MFG effect associated with vortex magnetic fields of current-carrying cables (i.e., MFG detection) and the MFG-induced ME effect in the ME composite pair (i.e., MFG conversion). The sensor output voltage is directly obtained from the gradient ME voltage of the ME composite pair and is calibrated against cable current to give the current sensitivity. The current sensing performance of the sensor is evaluated, both theoretically and experimentally, under multisource noises of electric fields, magnetic fields, vibrations, and thermals. The sensor combines the merits of small nonlinearity in the current-induced MFG effect with those of high sensitivity and high common-mode noise rejection rate in the MFG-induced ME effect to achieve a high current sensitivity of 0.65–12.55 mV/A in the frequency range of 10 Hz–170 kHz, a small input-output nonlinearity of <500 ppm, a small thermal drift of <0.2%/℃ in the current range of 0–20 A, and a high common-mode noise rejection rate of 17–28 dB from multisource noises. PMID:29443920

Magnetic resonance imaging findings and prognosis of gastric-type mucinous adenocarcinoma (minimal deviation adenocarcinoma or adenoma malignum) of the uterine corpus: Two case reports

OpenAIRE

HINO, MAYO; YAMAGUCHI, KEN; ABIKO, KAORU; YOSHIOKA, YUMIKO; HAMANISHI, JUNZO; KONDOH, EIJI; KOSHIYAMA, MASAFUMI; BABA, TSUKASA; MATSUMURA, NORIOMI; MINAMIGUCHI, SACHIKO; KIDO, AKI; KONISHI, IKUO

2016-01-01

Our group previously documented the first, very rare case of primary gastric-type mucinous adenocarcinoma of the uterine corpus. Although this type of endometrial cancer appears to be similar to the gastric-type adenocarcinoma of the uterine cervix, its main symptoms, appearance on magnetic resonance imaging (MRI) and prognosis have not been fully elucidated due to its rarity. We herein describe an additional case of gastric-type mucinous adenocarcinoma of the endometrium and review the relev...

Shape resonances in molecular fields

International Nuclear Information System (INIS)

Dehmer, J.L.

1984-01-01

A shape resonance is a quasibound state in which a particle is temporarily trapped by a potential barrier (i.e., the shape of the potential), through which it may eventually tunnel and escape. This simple mechanism plays a prominent role in a variety of excitation processes in molecules, ranging from vibrational excitation by slow electrons to ionization of deep core levels by x-rays. Moreover, their localized nature makes shape resonances a unifying link between otherwise dissimilar circumstances. One example is the close connection between shape resonances in electron-molecule scattering and in molecular photoionization. Another is the frequent persistence of free-molecule shape resonant behavior upon adsorption on a surface or condensation into a molecular solid. The main focus of this article is a discussion of the basic properties of shape resonances in molecular fields, illustrated by the more transparent examples studied over the last ten years. Other aspects to be discussed are vibrational effects of shape resonances, connections between shape resonances in different physical settings, and examples of shape resonant behavior in more complex cases, which form current challenges in this field

Understanding and modeling Förster-type resonance energy transfer (FRET) introduction to FRET

CERN Document Server

Govorov, Alexander; Demir, Hilmi Volkan

2016-01-01

This Brief presents a historical overview of the Förster-type nonradiative energy transfer and a compilation of important progress in FRET research, starting from Förster until today, along with a summary of the current state-of-the-art. Here the objective is to provide the reader with a complete account of important milestones in FRET studies and FRET applications as well as a picture of the current status.

Quasiparticle current in superconductor-semiconductor-superconductor junctions

International Nuclear Information System (INIS)

Tartakovskij, A.V.; Fistul', M.V.

1988-01-01

It is shown that the quasiparticle current in a superconductor-semiconductor-superconductor junction may significantly increase as a result of resonant passage of the quasiparticle along particular trajectories from periodically situated localized centers. A prediction of the theory is that with increasing junction resistance there should be a change from an excessive current to a insufficient current on the current-voltage characteristics (at high voltages). The effect of transparency of the boundaries on resonance tunneling in such junctions is also investigated

Type 2 Diabetes Mellitus: A Review of Current Trends

Directory of Open Access Journals (Sweden)

Abdulfatai B. Olokoba

2012-07-01

Full Text Available Type 2 diabetes mellitus (DM is a chronic metabolic disorder in which prevalence has been increasing steadily all over the world. As a result of this trend, it is fast becoming an epidemic in some countries of the world with the number of people affected expected to double in the next decade due to increase in ageing population, thereby adding to the already existing burden for healthcare providers, especially in poorly developed countries. This review is based on a search of Medline, the Cochrane Database of Systemic Reviews, and citation lists of relevant publications. Subject heading and key words used include type 2 diabetes mellitus, prevalence, current diagnosis, and current treatment. Only articles in English were included. Screening and diagnosis is still based on World Health Organization (WHO and American Diabetes Association (ADA criteria which include both clinical and laboratory parameters. No cure has yet been found for the disease; however, treatment modalities include lifestyle modifications, treatment of obesity, oral hypoglycemic agents, and insulin sensitizers like metformin, a biguanide that reduces insulin resistance, is still the recommended first line medication especially for obese patients. Other effective medications include non-sulfonylurea secretagogues, thiazolidinediones, alpha glucosidase inhibitors, and insulin. Recent research into the pathophysiology of type 2 DM has led to the introduction of new medications like glucagon-like peptide 1 analogoues: dipeptidyl peptidase-IV inhibitors, inhibitors of the sodium-glucose cotransporter 2 and 11ß-hydroxysteroid dehydrogenase 1, insulin-releasing glucokinase activators and pancreatic-G-protein-coupled fatty-acid-receptor agonists, glucagon-receptor antagonists, metabolic inhibitors of hepatic glucose output and quick-release bromocriptine. Inhaled insulin was licensed for use in 2006 but has been withdrawn from the market because of low patronage.

Algorithm of resonance orders for the objects

Science.gov (United States)

Zhang, YongGang; Zhang, JianXue

2018-03-01

In mechanical engineering, the object resonance phenomena often occur when the external incident wave frequency is close to object of the natural frequency. Object resonance phenomena get the maximum value when the external incident frequency is equal to object the natural frequency. Experiments found that resonance intension of the object is changed, different objects resonance phenomena present different characteristics of ladders. Based on object orders resonance characteristics, the calculation method of object orders resonance is put forward in the paper, and the application for the light and sound waves on the seven order resonance characteristics by people feel, the result error is less than 1%.Visible in this paper, the method has high accuracy and usability. The calculation method reveals that some object resonance occur present order characteristic only four types, namely the first-orders resonance characteristics, third-orders characteristics, five orders characteristic, and seven orders characteristic.

Experimental results of current distribution in Rutherford-type LHC cables

CERN Document Server

Verweij, A P

2000-01-01

Current distribution among the wires of multi-strand superconducting cables is an important item for accelerator magnets. A non-uniform distribution could cause additional field distortions in the magnet bore and can as well be one of the reasons of premature quenching. Since two years electrical measurements on superconducting Rutherford-type cables are performed at CERN as part of the reception tests for the Large Hadron Collider (LHC). Cable samples of 2.4 m length are tested at currents up to 32 kA, temperatures around 1.9 and 4.3 K, and fields up to 10 T, applied perpendicularly as well as parallel to the broad face of the cable. Last year, an array of 24 Hall probes was installed in the test set-up in order to measure the self-field of the cable samples along one cable pitch. Each of the probes measures the local field generated by the current in the strands close by, and the results of the all probes reflect therefore the distribution of the strand currents. Experiments are done varying the applied fie...

Li-Po Battery Charger Based on the Constant Current/Voltage Parallel Resonant Converter Operating in ZVS

Directory of Open Access Journals (Sweden)

Alberto M. Pernía

2018-04-01

Full Text Available Battery requirements for electrical vehicles are continuously becoming more demanding in terms of energy density and reliability. Nowadays, batteries for drones must be able to supply 100 A for 15 min, not to mention the specifications required for batteries in electrical vehicles. These specifications result in more stringent specifications for battery chargers. They are required to be more efficient, flexible, and, as with any another power equipment, to have reduced size and weight. Since the parallel resonant converter can operate as a current source and as a voltage source, this paper presents a battery charger power stage for lithium ion polymer batteries, based on the above topology, operating in zero voltage switching mode, and implementing frequency and duty cycle control.

Matrix metalloproteinase-2 and its correlation with basal membrane components laminin-5 and collagen type IV in paediatric burn patients measured with Surface Plasmon Resonance Imaging (SPRI) biosensors.

Science.gov (United States)

Weremijewicz, Artur; Matuszczak, Ewa; Sankiewicz, Anna; Tylicka, Marzena; Komarowska, Marta; Tokarzewicz, Anna; Debek, Wojciech; Gorodkiewicz, Ewa; Hermanowicz, Adam

2018-01-30

The purpose of this study was the determination of matrix metalloproteinase-2 and its correlation with basal membrane components laminin-5 and collagen type IV in the blood plasma of burn patients measured with Surface Plasmon Resonance Imaging (SPRI) biosensors. 31 children scalded by hot water who were managed at the Department of Paediatric Surgery between 2014-2015, after primarily presenting with burns in 4-20% TBSA were included into the study (age 9 months up to 14 years, mean age 2,5+1 years). There were 10 girls and 21 boys. Venous blood samples were drawn 2-6h, and 12-16h after the thermal injury, and on the subsequent days 3, 5 and 7. The matrix metalloproteinase-2, collagen type IV and laminin-5 concentrations were assessed using Surface Plasmon Resonance Imaging by the investigators blinded to the other data. The MMP-2, laminin-5 and collagen type IV concentrations in the blood plasma of patients with burns, were highest 12-16h after thermal injury, the difference was statistically significant. The MMP-2, laminin-5 and collagen type IV concentrations measured 3 days, 5 days and 7 days after the thermal injury, slowly decreased over time, and on the 7th day reached the normal range, when compared with the concentration measured in controls. Current work is the first follow-up study regarding MMP-2 in burns. MMP-2, laminin-5 and collagen type IV levels were elevated early after burn injury in the plasma of studied patients, and were highest 12-16h after the injury. MMP-2, laminin-5 and collagen type IV levels were not proportional to the severity of the burn. We believe in the possibility that the gradual decrease of MMP-2, collagen type IV and laminin-5 concentrations could be connected with the process of healing, but to prove it, more investigation is needed in this area. The SPR imaging biosensor is a good diagnostic tool for determination of MMP-2, laminin-5 and collagen type IV in blood plasma of patients with burns. Copyright © 2017 Elsevier Ltd

Observation of Current Structures at Type-III ELM Onset on EAST

DEFF Research Database (Denmark)

Yan, Ning; Naulin, Volker; Xu, G.

structure. To verify the current characteristic of this structure, a mono-polar current filaments model was involved, which can reproduce same pattern commendably. Thus, current transport may dominant in transitional stage and plays an important role in the nonlinear development phase of ELM exhaustive......In far scrape-o layer (SOL), alternating negative and positive burst structures in ion saturation current were detected at the onset of each type-III edge localized mode (ELM) on EAST. Different from the fast streaming phenomenon reported previously, one subsequent positive burst structure appears...... every time in the early phase of ELM. It seems like a quick transitional stage between edge localized mode (MHD) phase and transport phase during the ELM. A pronounced sinusoidal pattern has been observed on the radial magnetic induction signal by Langmuir - magnetic probe, corresponding with almost...

Electronically excited negative ion resonant states in chloroethylenes

Energy Technology Data Exchange (ETDEWEB)

Khvostenko, O.G., E-mail: khv@mail.ru; Lukin, V.G.; Tuimedov, G.M.; Khatymova, L.Z.; Kinzyabulatov, R.R.; Tseplin, E.E.

2015-02-15

Highlights: • Several novel dissociative negative ion channels were revealed in chloroethylenes. • The electronically excited resonant states were recorded in all chloroethylenes under study. • The states were assigned to the inter-shell types, but not to the core-excited Feshbach one. - Abstract: The negative ion mass spectra of the resonant electron capture by molecules of 1,1-dichloroethylene, 1,2-dichloroethylene-cis, 1,2-dichloroethylene-trans, trichloroethylene and tetrachloroethylene have been recorded in the 0–12 eV range of the captured electron energy using static magnetic sector mass spectrometer modified for operation in the resonant electron capture regime. As a result, several novel low-intensive dissociation channels were revealed in the compounds under study. Additionally, the negative ion resonant states were recorded at approximately 3–12 eV, mostly for the first time. These resonant states were assigned to the electronically excited resonances of the inter-shell type by comparing their energies with those of the parent neutral molecules triplet and singlet electronically excited states known from the energy-loss spectra obtained by previous studies.

Soft x-ray resonant diffraction study of magnetic structure in magnetoelectric Y-type hexaferrite

Science.gov (United States)

Ueda, H.; Tanaka, Y.; Wakabayashi, Y.; Kimura, T.

2018-05-01

The effect of magnetic field on the magnetic structure associated with magnetoelectric properties in a Y-type hexaferrite, Ba1.3Sr0.7CoZnFe11AlO22, was investigated by utilizing the soft x-ray resonant diffraction technique. In this hexaferrite, the so-called alternating longitudinal conical phase is stabilized at room temperature and zero magnetic field. Below room temperature, however, this phase is transformed into the so-called transverse conical phase by applying an in-plane magnetic field (≈ 0.3 T). The transverse conical phase persists even after removing the magnetic field. The magnetoelectricity, which is magnetically-induced electric polarization, observed in the hexaferrite is discussed in terms of the temperature-dependent magnetic structure at zero field.

Multi-frequency modes in superconducting resonators: Bridging frequency gaps in off-resonant couplings

Science.gov (United States)

Andersen, Christian Kraglund; Mølmer, Klaus

2015-03-01

A SQUID inserted in a superconducting waveguide resonator imposes current and voltage boundary conditions that makes it suitable as a tuning element for the resonator modes. If such a SQUID element is subject to a periodically varying magnetic flux, the resonator modes acquire frequency side bands. We calculate the multi-frequency eigenmodes and these can couple resonantly to physical systems with different transition frequencies and this makes the resonator an efficient quantum bus for state transfer and coherent quantum operations in hybrid quantum systems. As an example of the application, we determine their coupling to transmon qubits with different frequencies and we present a bi-chromatic scheme for entanglement and gate operations. In this calculation, we obtain a maximally entangled state with a fidelity F = 95 % . Our proposal is competitive with the achievements of other entanglement-gates with superconducting devices and it may offer some advantages: (i) There is no need for additional control lines and dephasing associated with the conventional frequency tuning of qubits. (ii) When our qubits are idle, they are far detuned with respect to each other and to the resonator, and hence they are immune to cross talk and Purcell-enhanced decay.

Terahertz response of fractal meta-atoms based on concentric rectangular square resonators

Energy Technology Data Exchange (ETDEWEB)

Song, Zhiqiang; Zhao, Zhenyu, E-mail: zyzhao@shnu.edu.cn; Shi, Wangzhou [Department of Physics, Shanghai Normal University, Shanghai 200234 (China); Peng, Wei [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

2015-11-21

We investigate the terahertz electromagnetic responses of fractal meta-atoms (MAs) induced by different mode coupling mechanisms. Two types of MAs based on concentric rectangular square (CRS) resonators are presented: independent CRS (I-CRS) and junctional-CRS (J-CRS). In I-CRS, each resonator works as an independent dipole so as to result in the multiple resonance modes when the fractal level is above 1. In J-CRS, however, the generated layer is rotated by π/2 radius to the adjacent CRS in one MA. The multiple resonance modes are coupled into a single mode resonance. The fractal level increasing induces resonance modes redshift in I-CRS while blueshift in J-CRS. When the fractal level is below 4, the mode Q factor of J-CRS is in between the two modes of I-CRS; when the fractal level is 4 or above, the mode Q factor of J-CRS exceeds the two modes of I-CRS. Furthermore, the modulation depth (MD) decreases in I-CRS while it increases in J-CRS with the increase in fractal levels. The surface currents analysis reveals that the capacitive coupling of modes in I-CRS results in the modes redshift, while the conductive coupling of modes in J-CRS induces the mode blueshift. A high Q mode with large MD can be achieved via conductive coupling between the resonators of different scales in a fractal MA.

A Control Method of Current Type Matrix Converter for Plasma Control Coil Power Supply

International Nuclear Information System (INIS)

Shimada, K.; Matsukawa, M.; Kurihara, K.; Jun-ichi Itoh

2006-01-01

In exploration to a tokamak fusion reactor, the control of plasma instabilities of high β plasma such as neoclassical tearing mode (NTM), resistive wall mode (RWM) etc., is the key issue for steady-state sustainment. One of the proposed methods to avoid suppressing RWM is that AC current having a phase to work for reduction the RWM growth is generated in a coil (sector coil) equipped spirally on the plasma vacuum vessel. To stabilize RWM, precise and fast real-time feedback control of magnetic field with proper amplitude and frequency is necessary. This implies that an appropriate power supply dedicated for such an application is expected to be developed. A matrix converter as one of power supply candidates for this purpose could provide a solution The matrix converter, categorized in an AC/AC direct converter composed of nine bi-directional current switches, has a great feature that a large energy storage element is unnecessary in comparison with a standard existing AC/AC indirect converter, which is composed of an AC/DC converter and a DC/AC inverter. It is also advantageous in cost and size of its applications. Fortunately, a voltage type matrix converter has come to be available at the market recently, while a current type matrix converter, which is advantageous for fast control of the large-inductance coil current, has been unavailable. On the background above mentioned, we proposed a new current type matrix converter and its control method applicable to a power supply with fast response for suppressing plasma instabilities. Since this converter is required with high accuracy control, the gate control method is adopted to three-phase switching method using middle phase to reduce voltage and current waveforms distortion. The control system is composed of VME-bus board with DSP (Digital Signal Processor) and FPGA (Field Programmable Gate Array) for high speed calculation and control. This paper describes the control method of a current type matrix converter

Fano resonances from gradient-index metamaterials.

Science.gov (United States)

Xu, Yadong; Li, Sucheng; Hou, Bo; Chen, Huanyang

2016-01-27

Fano resonances - resonant scattering features with a characteristic asymmetric profile - have generated much interest, due to their extensive and valuable applications in chemical or biological sensors, new types of optical switches, lasers and nonlinear optics. They have been observed in a wide variety of resonant optical systems, including photonic crystals, metamaterials, metallic gratings and nanostructures. In this work, a waveguide structure is designed by employing gradient-index metamaterials, supporting strong Fano resonances with extremely sharp spectra. As the changes in the transmission spectrum originate from the interaction of guided modes from different channels, instead of resonance structures or metamolecules, the Fano resonances can be observed for both transverse electric and transverse magnetic polarizations. These findings are verified by fine agreement with analytical calculations and experimental results at microwave, as well as simulated results at near infrared frequencies.

An overview of the current status of resonance theory in reactor physics applications

International Nuclear Information System (INIS)

Hwang, R.N.

1993-01-01

The neutron resonance phenomena constitute one of the most fundamental subjects in nuclear physics as well as in reactor physics. It is the area where the concepts of nuclear interaction and the treatment of the neutronic balance in reactor lattices become intertwined. The later requires the detailed knowledge of resonance structures of many nuclide of practical interest to the development of nuclear energy. The key issue of the resonance treatment in reactor applications is directly associated with the use of the microscopic cross sections in the macroscopic reactor cells with a wide range of composition, temperature,and geometric configurations. It gives rise to the so called self-shielding effect. The accurate estimations of such a effect is essential not only in the calculation of the criticality of a reactor but also from the point of view of safety considerations. The latter manifests through the Doppler effect particularly crucial to the fast reactor development. The task of accurate treatment of the self-shielding effect, however, is by no means simple. In fact, it is perhaps the most complicated problem in neutron physics which, strictly speaking, requires the dependence of many physical variables. Two important elements of particular interest are : (1) a concise description of the resonance cross sections as a function of energy and temperature; (2) accurate estimation of the corresponding neutron flux where appropriate. These topics will be discussed from both the historical as well as the state-of-art perspectives

Principles of nuclear magnetic resonance (NMR) - current state of the art

International Nuclear Information System (INIS)

Lerski, R.A.

1985-01-01

Nuclear magnetic resonance (NMR) imaging has progressed rapidly from laboratory curiosity to commercial exploitation and clinical application in the space of only three years. The physical principles underlying the technique are described and the equipment requirements outlined. The question of optimal magnetic field strength is discussed. (author)

A superheterodyne spectrometer for electronic paramagnetic. Resonance; Spectrometre superheterodyne de resonance paramagnetique electronique

Energy Technology Data Exchange (ETDEWEB)

Laffon, J L [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1963-12-15

After a few generalities about electron paramagnetic resonance, a consideration of different experimental techniques authorises the choice of a particular type of apparatus. An EPR superheterodyne spectrometer built in the laboratory and having a novel circuit is described in detail. With this apparatus, many experimental results have been obtained and some of these are described as example. (author) [French] Apres quelques generalites sur le phenomene de resonance paramagnetique electronique, une synthese des differentes techniques experimentales, permet de fixer le choix d'un type d'appareillage. Un spectrometre de RPE superheterodyne realise en laboratoire et comportant un circuit original est expose dans le detail. Cet appareil a permis de nombreux resultats experimentaux dont quelques-uns sont decrits a titre d'exemple. (auteur)

New methodology for analytical calculation of resonance integrals in an heterogeneous medium

International Nuclear Information System (INIS)

Campos, T.P.R. de; Martinez, A.S.

1986-01-01

A new methodology for analytical calculation of Resonance Integral in a typical fuel cell is presented. The expression obtained for the Resonance Integral presents the advantage of being analytical. Its constituent terms are combinations of the well known function J(xi,β) with its partial derivatives in regard to β. This is a general expression for all types of resonance. The parameters used in this method depend on the resonance type and are obtained as a function of the parameter lambda. A simple expression, depending on resonance parameters is proposed for this variable. (Author) [pt

Parametric Resonance in a Time-Dependent Harmonic Oscillator

Directory of Open Access Journals (Sweden)

P. N. Nesterov

2013-01-01

Full Text Available In this paper, we study the phenomenon of appearance of new resonances in a timedependent harmonic oscillator under an oscillatory decreasing force. The studied equation belongs to the class of adiabatic oscillators and arises in connection with the spectral problem for the one-dimensional Schr¨odinger equation with Wigner–von Neumann type potential. We use a specially developed method for asymptotic integration of linear systems of differential equations with oscillatory decreasing coefficients. This method uses the ideas of the averaging method to simplify the initial system. Then we apply Levinson’s fundamental theorem to get the asymptotics for its solutions. Finally, we analyze the features of a parametric resonance phenomenon. The resonant frequencies of perturbation are found and the pointwise type of the parametric resonance phenomenon is established. In conclusion, we construct an example of a time-dependent harmonic oscillator (adiabatic oscillator in which the parametric resonances, mentioned in the paper, may occur.

A numerical study on the feasibility evaluation of a hybrid type superconducting fault current limiter applying thyristors

Energy Technology Data Exchange (ETDEWEB)

Nam, Seok Ho; Lee, Woo Seung; Lee, Ji Ho; Hwang, Young Jin; Ko, Tae Kuk [Yonsei University, Seoul (Korea, Republic of)

2013-12-15

Smart fault current controller (SFCC) proposed in our previous work consists of a power converter, a high temperature superconducting (HTS) DC reactor, thyristors, and a control unit [1]. SFCC can limit and control the current by adjusting firing angles of thyristors when a fault occurs. SFCC has complex structure because the HTS DC reactor generates the loss under AC. To use the DC reactor under AC, rectifier that consists of four thyristors is needed and it increases internal resistance of SFCC. For this reason, authors propose a hybrid type superconducting fault current limiter (SFCL). The hybrid type SFCL proposed in this paper consists of a non-inductive superconducting coil and two thyristors. To verify the feasibility of the proposed hybrid type SFCL, simulations about the interaction of the superconducting coil and thyristors are conducted when fault current flows in the superconducting coil. Authors expect that the hybrid type SFCL can control the magnitude of the fault current by adjusting the firing angles of thyristors after the superconducting coil limits the fault current at first peak.

A numerical study on the feasibility evaluation of a hybrid type superconducting fault current limiter applying thyristors

International Nuclear Information System (INIS)

Nam, Seok Ho; Lee, Woo Seung; Lee, Ji Ho; Hwang, Young Jin; Ko, Tae Kuk

2013-01-01

Smart fault current controller (SFCC) proposed in our previous work consists of a power converter, a high temperature superconducting (HTS) DC reactor, thyristors, and a control unit [1]. SFCC can limit and control the current by adjusting firing angles of thyristors when a fault occurs. SFCC has complex structure because the HTS DC reactor generates the loss under AC. To use the DC reactor under AC, rectifier that consists of four thyristors is needed and it increases internal resistance of SFCC. For this reason, authors propose a hybrid type superconducting fault current limiter (SFCL). The hybrid type SFCL proposed in this paper consists of a non-inductive superconducting coil and two thyristors. To verify the feasibility of the proposed hybrid type SFCL, simulations about the interaction of the superconducting coil and thyristors are conducted when fault current flows in the superconducting coil. Authors expect that the hybrid type SFCL can control the magnitude of the fault current by adjusting the firing angles of thyristors after the superconducting coil limits the fault current at first peak.

Direct imaging of neural currents using ultra-low field magnetic resonance techniques

Science.gov (United States)

Volegov, Petr L [Los Alamos, NM; Matlashov, Andrei N [Los Alamos, NM; Mosher, John C [Los Alamos, NM; Espy, Michelle A [Los Alamos, NM; Kraus, Jr., Robert H.

2009-08-11

Using resonant interactions to directly and tomographically image neural activity in the human brain using magnetic resonance imaging (MRI) techniques at ultra-low field (ULF), the present inventors have established an approach that is sensitive to magnetic field distributions local to the spin population in cortex at the Larmor frequency of the measurement field. Because the Larmor frequency can be readily manipulated (through varying B.sub.m), one can also envision using ULF-DNI to image the frequency distribution of the local fields in cortex. Such information, taken together with simultaneous acquisition of MEG and ULF-NMR signals, enables non-invasive exploration of the correlation between local fields induced by neural activity in cortex and more `distant` measures of brain activity such as MEG and EEG.

Plural three-wave resonances of space charge wave harmonics in transit section of klystron-type two-stream FEL with helical electron beam

DEFF Research Database (Denmark)

Lysenko, Alexander; Volk, Iurii; Serozhko, Anastasia

2017-01-01

We have carried out the research of plural three-wave resonances of space charge wave (SCW) harmonics in the transit section of the klystron type two-stream superheterodyne free-electron laser (TSFEL) with helical electron beam in cubic non-linear approximation. We have found out that two...

Some considerations on the current debate about typing resolution in solid organ transplantation.

Science.gov (United States)

Vogiatzi, Paraskevi

2016-01-01

The shortage of suitable organs and achieved tolerance are uncontested main concerns in transplantation. Long waiting lists for deceased donors and limited numbers of living donors are the current scenarios. Kidney grafts from living donors have better overall survival compared to cadaveric and require less aggressive immunosuppressive regimens. The human leukocyte antigen (HLA) labs have the key role to test the recipient and donors compatibility based on typing and antibody profile. The current standard molecular procedure in solid organ transplantation is low-resolution typing, at the antigen level. In this commentary, the merits of high versus low degree of typing resolution in solid organ transplantation are discussed. Critical questions and reasons to bring high-resolution typing as a routine test in health system are considered. Specifically, with the introduction of the next-generation sequencing (NGS) in HLA, the pros and cons in living donation and benefits after deceased donation are critically evaluated. NGS has the potential to improve the transplant rates and the overall graft survival. Alternative strategies to increase in demanding the number of transplants are briefly highlighted.

Neutron absorbers and detector types for spent fuel verification using the self-interrogation neutron resonance densitometry

International Nuclear Information System (INIS)

Rossa, Riccardo; Borella, Alessandro; Labeau, Pierre-Etienne; Pauly, Nicolas; Meer, Klaas van der

2015-01-01

The Self-Interrogation Neutron Resonance Densitometry (SINRD) is a passive non-destructive assay (NDA) technique that is proposed for the direct measurement of 239 Pu in a spent fuel assembly. The insertion of neutron detectors wrapped with different neutron absorbing materials, or neutron filters, in the central guide tube of a PWR fuel assembly is envisaged to measure the neutron flux in the energy region close to the 0.3 eV resonance of 239 Pu. In addition, the measurement of the fast neutron flux is foreseen. This paper is focused on the determination of the Gd and Cd neutron filters thickness to maximize the detection of neutrons within the resonance region. Moreover, several detector types are compared to identify the optimal condition and to assess the expected total neutron counts that can be obtained with the SINRD measurements. Results from Monte Carlo simulations showed that ranges between 0.1–0.3 mm and 0.5–1.0 mm ensure the optimal conditions for the Gd and Cd filters, respectively. Moreover, a 239 Pu fission chamber is better suited to measure neutrons close to the 0.3 eV resonance and it has the highest sensitivity to 239 Pu, in comparison with a 235 U fission chamber, with a 3 He proportional counter, and with a 10 B proportional counter. The use of a thin Gd filter and a thick Cd filter is suggested for the 239 Pu and 235 U fission chambers to increase the total counts achieved in a measurement, while a thick Gd filter and a thin Cd filter are envisaged for the 3 He and 10 B proportional counters to increase the sensitivity to 239 Pu. We concluded that an optimization process that takes into account measurement time, filters thickness, and detector size is needed to develop a SINRD detector that can meet the requirement for an efficient verification of spent fuel assemblies

Neutron absorbers and detector types for spent fuel verification using the self-interrogation neutron resonance densitometry

Energy Technology Data Exchange (ETDEWEB)

Rossa, Riccardo, E-mail: rrossa@sckcen.be [SCK-CEN, Belgian Nuclear Research Centre, Boeretang, 200, B2400 Mol (Belgium); Université libre de Bruxelles, Ecole polytechnique de Bruxelles, Service de Métrologie Nucléaire (CP 165/84), Avenue F.D. Roosevelt, 50, B1050 Brussels (Belgium); Borella, Alessandro, E-mail: aborella@sckcen.be [SCK-CEN, Belgian Nuclear Research Centre, Boeretang, 200, B2400 Mol (Belgium); Labeau, Pierre-Etienne, E-mail: pelabeau@ulb.ac.be [Université libre de Bruxelles, Ecole polytechnique de Bruxelles, Service de Métrologie Nucléaire (CP 165/84), Avenue F.D. Roosevelt, 50, B1050 Brussels (Belgium); Pauly, Nicolas, E-mail: nipauly@ulb.ac.be [Université libre de Bruxelles, Ecole polytechnique de Bruxelles, Service de Métrologie Nucléaire (CP 165/84), Avenue F.D. Roosevelt, 50, B1050 Brussels (Belgium); Meer, Klaas van der, E-mail: kvdmeer@sckcen.be [SCK-CEN, Belgian Nuclear Research Centre, Boeretang, 200, B2400 Mol (Belgium)

2015-08-11

The Self-Interrogation Neutron Resonance Densitometry (SINRD) is a passive non-destructive assay (NDA) technique that is proposed for the direct measurement of {sup 239}Pu in a spent fuel assembly. The insertion of neutron detectors wrapped with different neutron absorbing materials, or neutron filters, in the central guide tube of a PWR fuel assembly is envisaged to measure the neutron flux in the energy region close to the 0.3 eV resonance of {sup 239}Pu. In addition, the measurement of the fast neutron flux is foreseen. This paper is focused on the determination of the Gd and Cd neutron filters thickness to maximize the detection of neutrons within the resonance region. Moreover, several detector types are compared to identify the optimal condition and to assess the expected total neutron counts that can be obtained with the SINRD measurements. Results from Monte Carlo simulations showed that ranges between 0.1–0.3 mm and 0.5–1.0 mm ensure the optimal conditions for the Gd and Cd filters, respectively. Moreover, a {sup 239}Pu fission chamber is better suited to measure neutrons close to the 0.3 eV resonance and it has the highest sensitivity to {sup 239}Pu, in comparison with a {sup 235}U fission chamber, with a {sup 3}He proportional counter, and with a {sup 10}B proportional counter. The use of a thin Gd filter and a thick Cd filter is suggested for the {sup 239}Pu and {sup 235}U fission chambers to increase the total counts achieved in a measurement, while a thick Gd filter and a thin Cd filter are envisaged for the {sup 3}He and {sup 10}B proportional counters to increase the sensitivity to {sup 239}Pu. We concluded that an optimization process that takes into account measurement time, filters thickness, and detector size is needed to develop a SINRD detector that can meet the requirement for an efficient verification of spent fuel assemblies.

Resonant power processors. I - State plane analysis

Science.gov (United States)

Oruganti, R.; Lee, F. C.

1984-01-01

State-plane techniques in conjunction with piecewise-linear analysis is employed to study the steady-state and transient characteristics of a series resonant converter. With the direct viewing of the resonant tank energy and the device switching instants, the state portrayal provides unique insights into the complex behavior of the converter. Operation of the converter under both continuous and discontinuous current modes and at frequencies both below and above resonant frequency are discussed.

Hybrid localized waves supported by resonant anisotropic metasurfaces

DEFF Research Database (Denmark)

Bogdanov, A. A.; Yermakov, O. Y.; Ovcharenko, A. I.

2016-01-01

We study both theoretically and experimentally a new class of surface electromagnetic waves supported by resonant anisotropic metasurface. At certain frequency this type of metasurface demonstrates the topological transition from elliptical to hyperbolic regime.......We study both theoretically and experimentally a new class of surface electromagnetic waves supported by resonant anisotropic metasurface. At certain frequency this type of metasurface demonstrates the topological transition from elliptical to hyperbolic regime....

Study of the influence of chemical binding on resonant absorption and scattering of neutrons; Etude de l'influence des liaisons chimiques sur l'absorption et la diffusion des neutrons aux energies de resonance

Energy Technology Data Exchange (ETDEWEB)

Naberejnev, D G [Aix-Marseille-1 Univ., 13 - Marseille (France)

1999-02-01

At present time the problem of taking into account of the crystalline binding in the heavy nuclei resonance range is not correctly treated in nuclear data processing codes. The present work deals separately with resonant absorption and scattering of neutrons. The influence of crystalline binding is considered for both types of reactions in the harmonic crystal frame work. The harmonic crystal model is applied to the study of resonant absorption cross sections to show the inconsistency of the free gas model widely in use in reactor neutronics. The errors due to the use of the latter were found to be non negligible. These errors should be corrected by introducing a more elaborated harmonic crystal model in codes for resonances analysis and on the nuclear data processing stage. Currently the influence of crystalline binding on transfer cross section in the resonance domain is taken into account in a naive manner using the model of the free nucleus at rest in the laboratory system. In this work I present a formalism (Uncoupled Phonon Approximation) which permits to consider in more detail the crystalline structure of the nuclear fuel. This formalism shows new features in comparison with the static model. (author)

Physics of Gate Modulated Resonant Tunneling (RT)-FETs: Multi-barrier MOSFET for steep slope and high on-current

Science.gov (United States)

Afzalian, Aryan; Colinge, Jean-Pierre; Flandre, Denis

2011-05-01

A new concept of nanoscale MOSFET, the Gate Modulated Resonant Tunneling Transistor (RT-FET), is presented and modeled using 3D Non-Equilibrium Green's Function simulations enlightening the main physical mechanisms. Owing to the additional tunnel barriers and the related longitudinal confinement present in the device, the density of state is reduced in its off-state, while remaining comparable in its on-state, to that of a MOS transistor without barriers. The RT-FET thus features both a lower RT-limited off-current and a faster increase of the current with V G, i.e. an improved slope characteristic, and hence an improved Ion/ Ioff ratio. Such improvement of the slope can happen in subthreshold regime, and therefore lead to subthreshold slope below the kT/q limit. In addition, faster increase of current and improved slope occur above threshold and lead to high thermionic on-current and significant Ion/ Ioff ratio improvement, even with threshold voltage below 0.2 V and supply voltage V dd of a few hundreds of mV as critically needed for future technology nodes. Finally RT-FETs are intrinsically immune to source-drain tunneling and are therefore promising candidate for extending the roadmap below 10 nm.

Effect of quantum interference on the optical properties of a three-level V-type atomic system beyond the two-photon resonance condition

Energy Technology Data Exchange (ETDEWEB)

Mousavi, S M; Safari, L; Mahmoudi, M [Physics Department, Zanjan University, PO Box 45195-313, Zanjan (Iran, Islamic Republic of); Sahrai, M, E-mail: sahrai@tabrizu.ac.i [Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz (Iran, Islamic Republic of)

2010-08-28

The effect of quantum interference on the optical properties of a pumped-probe three-level V-type atomic system is investigated. The probe absorption, dispersion, group index and optical bistability beyond the two-photon resonance condition are discussed. It is found that the optical properties of a medium in the frequency of the probe field, in general, are phase independent. The phase dependence arises from a scattering of the coupling field into the probe field at a frequency which in general differs from the probe field frequency. It is demonstrated that beyond the two-photon resonance condition the phase sensitivity of the medium will disappear.

Cascaded resonant bridge converters

Science.gov (United States)

Stuart, Thomas A. (Inventor)

1989-01-01

A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator. The voltage of the second stage output is controlled at a relatively constant value by controlling the first stage output voltage, which is accomplished by controlling the frequency of the first stage variable frequency voltage controller in response to second stage voltage. Fault tolerance in the event of a load short circuit is provided by making the operation of the first stage variable frequency voltage controller responsive to first and second stage current limiting devices. The second stage output is connected to a rectifier bridge whose output is connected to the input of the second stage to provide good regulation of output voltage wave form at low system loads.

Jet-associated resonance spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Englert, Christoph [University of Glasgow, SUPA, School of Physics and Astronomy, Glasgow (United Kingdom); Ferretti, Gabriele [Chalmers University of Technology, Department of Physics, Goeteborg (Sweden); Spannowsky, Michael [Durham University, Department of Physics, Institute for Particle Physics Phenomenology, Durham (United Kingdom)

2017-12-15

We present a model-independent study aimed at characterising the nature of possible resonances in the jet-photon or jet-Z final state at hadron colliders. Such resonances are expected in many models of compositeness and would be a clear indication of new physics. At leading order, in the narrow width approximation, the matrix elements are parameterised by just a few constants describing the coupling of the various helicities to the resonance. We present the full structure of such amplitudes up to spin 2 and use them to simulate relevant kinematic distributions that could serve to constrain the coupling structure. This also generalises the signal generation strategy that is currently pursued by ATLAS and CMS to the most general case in the considered channels. While the determination of the P/CP properties of the interaction seems to be out of reach within this framework, there is a wealth of information to be gained about the spin of the resonance and the relative couplings of the helicities. (orig.)

Jet-associated resonance spectroscopy

Science.gov (United States)

Englert, Christoph; Ferretti, Gabriele; Spannowsky, Michael

2017-12-01

We present a model-independent study aimed at characterising the nature of possible resonances in the jet-photon or jet- Z final state at hadron colliders. Such resonances are expected in many models of compositeness and would be a clear indication of new physics. At leading order, in the narrow width approximation, the matrix elements are parameterised by just a few constants describing the coupling of the various helicities to the resonance. We present the full structure of such amplitudes up to spin 2 and use them to simulate relevant kinematic distributions that could serve to constrain the coupling structure. This also generalises the signal generation strategy that is currently pursued by ATLAS and CMS to the most general case in the considered channels. While the determination of the P/CP properties of the interaction seems to be out of reach within this framework, there is a wealth of information to be gained about the spin of the resonance and the relative couplings of the helicities.

Electron cyclotron resonance heating and current drive

Energy Technology Data Exchange (ETDEWEB)

Fidone, I.; Castejon, F.

1992-07-01

A brief summary of the theory and experiments on electron- cyclotron heating and current drive is presented. The general relativistic formulation of wave propagation and linear absorption is considered in some detail. The O-mode and the X-mode for normal and oblique propagation are investigated and illustrated by several examples. The experimental verification of the theory in T-10 and D- III-D is briefly discussed. Quasilinear evolution of the momentum distribution and related applications as, for instance, non linear wave, damping and current drive, are also considered for special cases of wave frequencies, polarization and propagation. In the concluding section we present the general formulation of the wave damping and current drive in the absence of electron trapping for arbitrary values of the wave frequency. (Author) 13 refs.

Electron - cyclotron resonance heating and current drive

International Nuclear Information System (INIS)

Fidone, I.; Castejon, F.

1992-01-01

A brief summary of the theory and experiments on electron- cyclotron heating and current drive is presented. The general relativistic formulation of wave propagation and linear absorption is considered in some detail. The O-mode and the X-mode for normal and oblique propagation are investigated and illustrated by several examples. The experimental verification of the theory in T-10 and D- III-D is briefly discussed. Quasilinear evolution of the momentum distribution and related applications as, for instance, non linear wave, damping and current drive, are also considered for special cases of wave frequencies, polarization and propagation. In the concluding section we present the general formulation of the wave damping and current drive in the absence of electron trapping for arbitrary values of the wave frequency. (Author) 13 refs

Electron-cyclotron resonance heating and current drive

International Nuclear Information System (INIS)

Filone, I.

1992-01-01

A brief summary of the theory and experiments on electron-cyclotron heating and current drive is presented. the general relativistic formulation of wave propagation and linear absorption is considered in some detail. The O-mode and the X-mode for normal and oblique propagation are investigated and illustrated by several examples. The experimental verification of the theory in T-10 and D-III-D is briefly discussed. Quasilinear evolution of the momentum distribution and related applications as, for instance, non linear wave damping and current drive, are also considered for special cases of wave frequencies, polarization and propagation. In the concluding section we present the general formulation of the wave damping and current drive in the absence of electron trapping for arbitrary values of the wave frequency. (author) 8 fig. 13 ref

Determination of the electromagnetic field in a high-Tc linear superconducting resonator

International Nuclear Information System (INIS)

Trotel, A.; Sautrot, S.; Pyee, M.

1994-01-01

In this paper, the electromagnetic field configuration in a linear SHTC resonator is described. Two areas are considered: 1) the superconducting strip, 2) the dielectric around the strip. The calculation is based on the current density given by Bowers for an infinite superconducting line. The current density in the resonator is defined by these relations and the resonance conditions. (orig.)

Optically controlled resonant tunneling in a double-barrier diode

Science.gov (United States)

Kan, S. C.; Wu, S.; Sanders, S.; Griffel, G.; Yariv, A.

1991-03-01

The resonant tunneling effect is optically enhanced in a GaAs/GaAlAs double-barrier structure that has partial lateral current confinement. The peak current increases and the valley current decreases simultaneously when the device surface is illuminated, due to the increased conductivity of the top layer of the structure. The effect of the lateral current confinement on the current-voltage characteristic of a double-barrier resonant tunneling structure was also studied. With increased lateral current confinement, the peak and valley current decrease at a different rate such that the current peak-to-valley ratio increases up to three times. The experimental results are explained by solving the electrostatic potential distribution in the structure using a simple three-layer model.

Resonance in a Cone-Topped Tube

Directory of Open Access Journals (Sweden)

Angus Cheng-Huan Chia

2011-06-01

Full Text Available The relationship between ratio of the upper opening diameter of a cone-topped cylinder to the cylinder diameter,and the ratio of the length of the air column to resonant period was examined. Plastic cones with upper openings ranging from 1.3 cm to 3.6 cm and tuning forks with frequencies ranging from 261.6 Hz to 523.3 Hz were used. The transition from a standing wave in a cylindrical column to a Helmholtz-type resonance in a resonant cavity with a narrow opening was observed.

Resonant dynamics of gravitationally bound pair of binaries: the case of 1:1 resonance

Science.gov (United States)

Breiter, Slawomir; Vokrouhlický, David

2018-04-01

The work presents a study of the 1:1 resonance case in a hierarchical quadruple stellar system of the 2+2 type. The resonance appears if orbital periods of both binaries are approximately equal. It is assumed that both periods are significantly shorter than the period of principal orbit of one binary with respect to the other. In these circumstances, the problem can be treated as three independent Kepler problems perturbed by mutual gravitational interactions. By means of canonical perturbation methods, the planar problem is reduced to a secular system with 1 degree of freedom involving a resonance angle (the difference of mean longitudes of the binaries) and its conjugate momentum (involving the ratio of orbital period in one binary to the period of principal orbit). The resonant model is supplemented with short periodic perturbations expressions, and verified by the comparison with numerical integration of the original equations of motion. Estimates of the binaries periods variations indicate that the effect is rather weak, but possibly detectible if it occurs in a moderately compact system. However, the analysis of resonance capture scenarios implies that the 1:1 resonance should be exceptional amongst the 2+2 quadruples.

Control of neoclassical tearing mode by electron cyclotron current drive and non-resonant helical field application in ITER

International Nuclear Information System (INIS)

Taniguchi, Satoshi; Yamazaki, Kozo; Oishi, Tetsutarou; Arimoto, Hideki; Shoji, Tatsuo

2010-01-01

On tokamak plasmas like ITER, it is necessary to stabilize neoclassical tearing mode (NTM) because the NTM reduces plasma temperature and fusion power output. For the analysis of stabilizing NTM in fusion plasmas, the electron cyclotron current drive (ECCD) and the non-resonant external helical field (NRHF) application are simulated using the 1.5-dimensional equilibrium/transport simulation code (TOTAL code). The 3/2 NTM is stabilized by only external helical field, but the 2/1 mode is not stabilized by only external helical field in the present model. The stabilization time becomes shorter by the combination of ECCD and NRHF than that by ECCD alone. (author)

Strongly driven electron spins using a Ku band stripline electron paramagnetic resonance resonator

Science.gov (United States)

Yap, Yung Szen; Yamamoto, Hiroshi; Tabuchi, Yutaka; Negoro, Makoto; Kagawa, Akinori; Kitagawa, Masahiro

2013-07-01

This article details our work to obtain strong excitation for electron paramagnetic resonance (EPR) experiments by improving the resonator's efficiency. The advantages and application of strong excitation are discussed. Two 17 GHz transmission-type, stripline resonators were designed, simulated and fabricated. Scattering parameter measurements were carried out and quality factor were measured to be around 160 and 85. Simulation results of the microwave's magnetic field distribution are also presented. To determine the excitation field at the sample, nutation experiments were carried out and power dependence were measured using two organic samples at room temperature. The highest recorded Rabi frequency was rated at 210 MHz with an input power of about 1 W, which corresponds to a π/2 pulse of about 1.2 ns.

A current drive by using the fast wave in frequency range higher than two timeslower hybrid resonance frequency on tokamaks

Directory of Open Access Journals (Sweden)

Kim Sun Ho

2017-01-01

Full Text Available An efficient current drive scheme in central or off-axis region is required for the steady state operation of tokamak fusion reactors. The current drive by using the fast wave in frequency range higher than two times lower hybrid resonance (w>2wlh could be such a scheme in high density, high temperature reactor-grade tokamak plasmas. First, it has relatively higher parallel electric field to the magnetic field favorable to the current generation, compared to fast waves in other frequency range. Second, it can deeply penetrate into high density plasmas compared to the slow wave in the same frequency range. Third, parasitic coupling to the slow wave can contribute also to the current drive avoiding parametric instability, thermal mode conversion and ion heating occured in the frequency range w<2wlh. In this study, the propagation boundary, accessibility, and the energy flow of the fast wave are given via cold dispersion relation and group velocity. The power absorption and current drive efficiency are discussed qualitatively through the hot dispersion relation and the polarization. Finally, those characteristics are confirmed with ray tracing code GENRAY for the KSTAR plasmas.

HTS microstrip disk resonator with an upper dielectric layer for 4GHz

International Nuclear Information System (INIS)

Yamanaka, Kazunori; Kai, Manabu; Akasegawa, Akihiko; Nakanishi, Teru

2006-01-01

We propose HTS microstrip disk resonator with an upper dielectric layer as a candidate resonator structure of HTS compact power filter for 4GHz band. The electromagnetic simulations on the upper dielectric layer examined the current distributions of the HTS resonators that had TM 11 mode resonance of about 4 GHz. By the simulations, it is evaluated that of the maximum current density near the end portion of the disk-shape pattern of the resonator with the thick upper-layered structure decreases by roughly 30-50 percent, as compared with that of the resonator without it. Then, we designed and fabricated the resonator samples with and without the upper dielectrics. The RF power measurement results indicated that the upper dielectric layer leads to an increase in handling power

Fabrication, tests, and RF control of the 50 superconducting resonators of the Saclay heavy ion linac

International Nuclear Information System (INIS)

Cauvin, B.; Coret, M.; Fouan, J.P.

1988-01-01

Two types of niobium superconducting resonators are currently in use in the linac Outer cylinder and RF ports are identical for both designs but internal structures are different full wave helix (λ) with three gaps behavior or half-wave (λ/2) with two gaps behavior. The λ structure is based on a Karlsruhe design. All cavities (34 λ and 16 λ/2) are now fabricated, tested for field, and mounted in the eight machine cryostats. Resonator characteristics are listed. Frequencies are multiples of the low energy bunching frequency (13.5 MHz). The high magnetic fields arise at the welds joining helix to can (λ/2) or half-helices together (λ)

Josephson plasma resonance in superconducting multilayers

DEFF Research Database (Denmark)

Pedersen, Niels Falsig

1999-01-01

We derive an analytical solution for the josephson plasma resonance of superconducting multilayers. This analytical solution is derived mainly for low T-c systems with magnetic coupling between the superconducting layers, but many features of our results are more general, and thus an application...... to the recently derived plasma resonance phenomena for high T-c superconductors of the BSCCO type is discussed....

Magnetic resonance annual, 1988

International Nuclear Information System (INIS)

Kressel, H.Y.

1987-01-01

This book features reviews of high-resolution MRI of the knee, MRI of the normal and ischmeic hip, MRI of the heart, and temporomandibular joint imaging, as well as thorough discussion on artifacts in magnetic resonance imaging. Contributors consider the clinical applications of gadolinium-DTPA in magnetic resonance imaging and the clinical use of partial saturation and saturation recovery sequences. Timely reports assess the current status of rapid MRI and describe a new rapid gated cine MRI technique. Also included is an analysis of cerebrospinal fluid flow effects during MRI of the central nervous system

Electrothermally Tunable Arch Resonator

KAUST Repository

Hajjaj, Amal Z.

2017-03-18

This paper demonstrates experimentally, theoretically, and numerically a wide-range tunability of electrothermally actuated microelectromechanical arch beams. The beams are made of silicon and are intentionally fabricated with some curvature as in-plane shallow arches. An electrothermal voltage is applied between the anchors of the beam generating a current that controls the axial stress caused by thermal expansion. When the electrothermal voltage increases, the compressive stress increases inside the arch beam. This leads to an increase in its curvature, thereby increasing its resonance frequencies. We show here that the first resonance frequency can increase monotonically up to twice its initial value. We show also that after some electrothermal voltage load, the third resonance frequency starts to become more sensitive to the axial thermal stress, while the first resonance frequency becomes less sensitive. These results can be used as guidelines to utilize arches as wide-range tunable resonators. Analytical results based on the nonlinear Euler Bernoulli beam theory are generated and compared with the experimental data and the results of a multi-physics finite-element model. A good agreement is found among all the results. [2016-0291

Interplay of activation kinetics and the derivative conductance determines resonance properties of neurons

Science.gov (United States)

Pena, Rodrigo F. O.; Ceballos, Cesar C.; Lima, Vinicius; Roque, Antonio C.

2018-04-01

In a neuron with hyperpolarization activated current (Ih), the correct input frequency leads to an enhancement of the output response. This behavior is known as resonance and is well described by the neuronal impedance. In a simple neuron model we derive equations for the neuron's resonance and we link its frequency and existence with the biophysical properties of Ih. For a small voltage change, the component of the ratio of current change to voltage change (d I /d V ) due to the voltage-dependent conductance change (d g /d V ) is known as derivative conductance (GhDer). We show that both GhDer and the current activation kinetics (characterized by the activation time constant τh) are mainly responsible for controlling the frequency and existence of resonance. The increment of both factors (GhDer and τh) greatly contributes to the appearance of resonance. We also demonstrate that resonance is voltage dependent due to the voltage dependence of GhDer. Our results have important implications and can be used to predict and explain resonance properties of neurons with the Ih current.

Magneto-acoustic resonance in a non-uniform current carrying plasma column

OpenAIRE

Vaclavik, J.

2017-01-01

The forced radial magneto-acoustic oscillations in a plasma column with nonuniform mass density and temperature are investigated. It turns out that the oscillations have a resonant character similar to that of the magneto-acoustic oscillations in a uniform plasma column. The properties of the axial and azimuthal components of the oscillating magnetic field are discussed in detail

Profiling of Current Transients in Capacitor Type Diamond Sensors

Science.gov (United States)

Gaubas, Eugenijus; Ceponis, Tomas; Meskauskaite, Dovile; Kazuchits, Nikolai

2015-01-01

The operational characteristics of capacitor-type detectors based on HPHT and CVD diamond have been investigated using perpendicular and parallel injection of carrier domain regimes. Simulations of the drift-diffusion current transients have been implemented by using dynamic models based on Shockley-Ramo’s theorem, under injection of localized surface domains and of bulk charge carriers. The bipolar drift-diffusion regimes have been analyzed for the photo-induced bulk domain (packet) of excess carriers. The surface charge formation and polarization effects dependent on detector biasing voltage have been revealed. The screening effects ascribed to surface charge and to dynamics of extraction of the injected bulk excess carrier domain have been separated and explained. The parameters of drift mobility of the electrons μe = 4000 cm2/Vs and holes μh = 3800 cm2/Vs have been evaluated for CVD diamond using the perpendicular profiling of currents. The coefficient of carrier ambipolar diffusion Da = 97 cm2/s and the carrier recombination lifetime τR,CVD ≌ 110 ns in CVD diamond were extracted by combining analysis of the transients of the sensor current and the microwave probed photoconductivity. The carrier trapping with inherent lifetime τR,HPHT ≌ 2 ns prevails in HPHT diamond. PMID:26061200

Method and apparatus for resonant frequency waveform modulation

Science.gov (United States)

Taubman, Matthew S [Richland, WA

2011-06-07

A resonant modulator device and process are described that provide enhanced resonant frequency waveforms to electrical devices including, e.g., laser devices. Faster, larger, and more complex modulation waveforms are obtained than can be obtained by use of conventional current controllers alone.

Theory of electrically controlled resonant tunneling spin devices

Science.gov (United States)

Ting, David Z. -Y.; Cartoixa, Xavier

2004-01-01

We report device concepts that exploit spin-orbit coupling for creating spin polarized current sources using nonmagnetic semiconductor resonant tunneling heterostructures, without external magnetic fields. The resonant interband tunneling psin filter exploits large valence band spin-orbit interaction to provide strong spin selectivity.

Analysis on fault current limiting and recovery characteristics of a flux-lock type SFCL with an isolated transformer

International Nuclear Information System (INIS)

Ko, Seckcheol; Lim, Sung-Hun; Han, Tae-Hee

2013-01-01

Highlights: ► Countermeasure to reduce the power burden of HTSC element consisting of the flux-lock type SFCL was studied. ► The power burden of HTSC element could be decreased by using the isolated transformer. ► The SFCL designed with the additive polarity winding could be confirmed to cause less power burden of the HTSC element. -- Abstract: The flux-lock type superconducting fault current limiter (SFCL) can quickly limit the fault current shortly after the short circuit occurs and recover the superconducting state after the fault removes. However, the superconducting element comprising the flux-lock type SFCL can be destructed when the high fault current passes through the SFCL. Therefore, the countermeasure to control the fault current and protect the superconducting element is required. In this paper, the flux-lock type SFCL with an isolated transformer, which consists of two parallel connected coils on an iron core and the isolated transformer connected in series with one of two coils, was proposed and the short-circuit experimental device to analyze the fault current limiting and the recovery characteristics of the flux-lock type SFCL with the isolated transformer were constructed. Through the short-circuit tests, the flux-lock type SFCL with the isolated transformer was confirmed to perform more effective fault current limiting and recovery operation compared to the flux-lock type SFCL without the isolated transformer from the viewpoint of the quench occurrence and the recovery time of the SFCL

A simple and powerful XY-Type current monitor for 30 MeV IPEN/CNEN-SP cyclotron

Energy Technology Data Exchange (ETDEWEB)

Barcellos, Henrique; Matsuda, Hylton; Sumyia, Luiz Carlos do A.; Junqueira, Fernando de C.; Costa, Osvaldo L. da, E-mail: hbolivei@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2017-11-01

A water-cooled XY-type current monitor was designed and built in the Cyclotrons Laboratory of the Nuclear and Energy Research Institute (IPEN). It is a very simple design and easily adaptable to the cyclotron beam lines. Tests were done demonstrating to be an instrument of great assistance in proton beam position along beam transport line and target port. Nowadays the XY-type current monitor has been widely used in {sup 18}F-FDG routine productions, employing irradiation system which were originally designed for productions on 18 MeV cyclotron accelerator only, however, applying the XY-type current monitor the target port may be exchanged between the 30 MeV and 18 MeV cyclotrons and the observed results are in perfect agreement with expected. (author)

Towards a beyond 1 GHz solid-state nuclear magnetic resonance: External lock operation in an external current mode for a 500 MHz nuclear magnetic resonance

International Nuclear Information System (INIS)

Takahashi, Masato; Maeda, Hideaki; Ebisawa, Yusuke; Tennmei, Konosuke; Yanagisawa, Yoshinori; Nakagome, Hideki; Hosono, Masami; Takasugi, Kenji; Hase, Takashi; Miyazaki, Takayoshi; Fujito, Teruaki; Kiyoshi, Tsukasa; Yamazaki, Toshio

2012-01-01

Achieving a higher magnetic field is important for solid-state nuclear magnetic resonance (NMR). But a conventional low temperature superconducting (LTS) magnet cannot exceed 1 GHz (23.5 T) due to the critical magnetic field. Thus, we started a project to replace the Nb 3 Sn innermost coil of an existing 920 MHz NMR (21.6 T) with a Bi-2223 high temperature superconducting (HTS) innermost coil. Unfortunately, the HTS magnet cannot be operated in persistent current mode; an external dc power supply is required to operate the NMR magnet, causing magnetic field fluctuations. These fluctuations can be stabilized by a field-frequency lock system based on an external NMR detection coil. We demonstrate here such a field-frequency lock system in a 500 MHz LTS NMR magnet operated in an external current mode. The system uses a 7 Li sample in a microcoil as external NMR detection system. The required field compensation is calculated from the frequency of the FID as measured with a frequency counter. The system detects the FID signal, determining the FID frequency, and calculates the required compensation coil current to stabilize the sample magnetic field. The magnetic field was stabilized at 0.05 ppm/3 h for magnetic field fluctuations of around 10 ppm. This method is especially effective for a magnet with large magnetic field fluctuations. The magnetic field of the compensation coil is relatively inhomogeneous in these cases and the inhomogeneity of the compensation coil can be taken into account.

Detection of cerebral atrophy in type- II diabetes mellitus by magnetic resonance imaging of brain

International Nuclear Information System (INIS)

Khan, G.; Khan, N.; Aziz, A.

2010-01-01

Background: Diabetes is a metabolic disorder that affects many systems in the body. Cerebral atrophy is one of the complications of diabetes and research is on going to find out its aetiopathological factors. The main aim of the study was to determine the frequency of cerebral atrophy in type-II diabetes mellitus using magnetic resonance imaging of the brain. Methods: One hundred diabetic patients (Random blood sugar >126 mg/dl) were recruited in this study after the informed consent from every patient. Duration of diabetes was five years and more in all the patients as determined by their glycosylated haemoglobin which was >6 in all the patients. All the patients were undergone MRI of brain using 1.5 Tesla power magnetic resonance imaging machine of Picker Company. Evan's index, a specific parameter for measurement of cerebral atrophy was calculated on MR images and was used in this study. Results: In male group the frequency of cerebral atrophy was 22 (47%) and in female group it was found to be 23 (43%). When we study the overall population the frequency was found to be 45 (45%). The results are well in concordance with the previous data published on this issue. Conclusions: Cerebral atrophy, a complication of long standing diabetes is quite frequent in our population and is well diagnosed by MRI. (author)

Study of the influence of chemical binding on resonant absorption and scattering of neutrons; Etude de l'influence des liaisons chimiques sur l'absorption et la diffusion des neutrons aux energies de resonance

Energy Technology Data Exchange (ETDEWEB)

Naberejnev, D.G. [Aix-Marseille-1 Univ., 13 - Marseille (France)

1999-02-01

At present time the problem of taking into account of the crystalline binding in the heavy nuclei resonance range is not correctly treated in nuclear data processing codes. The present work deals separately with resonant absorption and scattering of neutrons. The influence of crystalline binding is considered for both types of reactions in the harmonic crystal frame work. The harmonic crystal model is applied to the study of resonant absorption cross sections to show the inconsistency of the free gas model widely in use in reactor neutronics. The errors due to the use of the latter were found to be non negligible. These errors should be corrected by introducing a more elaborated harmonic crystal model in codes for resonances analysis and on the nuclear data processing stage. Currently the influence of crystalline binding on transfer cross section in the resonance domain is taken into account in a naive manner using the model of the free nucleus at rest in the laboratory system. In this work I present a formalism (Uncoupled Phonon Approximation) which permits to consider in more detail the crystalline structure of the nuclear fuel. This formalism shows new features in comparison with the static model. (author)

Magnetic Resonance Imaging in Aneurysmal Subarachnoid Hemorrhage: Current Evidence and Future Directions.

Science.gov (United States)

Nelson, Sarah E; Sair, Haris I; Stevens, Robert D

2018-04-09

Aneurysmal subarachnoid hemorrhage (aSAH) is associated with an unacceptably high mortality and chronic disability in survivors, underscoring a need to validate new approaches for treatment and prognosis. The use of advanced imaging, magnetic resonance imaging (MRI) in particular, could help address this gap given its versatile capacity to quantitatively evaluate and map changes in brain anatomy, physiology and functional activation. Yet there is uncertainty about the real value of brain MRI in the clinical setting of aSAH. In this review, we discuss current and emerging MRI research in aSAH. PubMed was searched from inception to June 2017, and additional studies were then chosen on the basis of relevance to the topics covered in this review. Available studies suggest that brain MRI is a feasible, safe, and valuable testing modality. MRI detects brain abnormalities associated with neurologic examination, outcomes, and aneurysm treatment and thus has the potential to increase knowledge of aSAH pathophysiology as well as to guide management and outcome prediction. Newer pulse sequences have the potential to reveal structural and physiological changes that could also improve management of aSAH. Research is needed to confirm the value of MRI-based biomarkers in clinical practice and as endpoints in clinical trials, with the goal of improving outcome for patients with aSAH.

Temporal Bell-type inequalities for two-level Rydberg atoms coupled to a high-Q resonator

International Nuclear Information System (INIS)

Huelga, S.F.; Marshall, T.W.; Santos, E.

1996-01-01

Following the strategy of showing specific quantum effects by means of the violation of a classical inequality, a pair of Bell-type inequalities is derived on the basis of certain additional assumptions, whose plausibility is discussed in detail. Such inequalities are violated by the quantum mechanical predictions for the interaction of a two-level Rydberg atom with a single mode sustained by a high-Q resonator. The experimental conditions required in order to show the existence of forbidden values, according to a hidden variables formalism, in a real experiment are analyzed for various initial field statistics. In particular, the revival dynamics expected for the interaction with a coherent field leads to classically forbidden values, which would indicate a purely quantum effect. copyright 1996 The American Physical Society

Resonators for magnetohydrodynamic waves in the solar corona: radioemission modulation effect

International Nuclear Information System (INIS)

Zajtsev, V.V.; Stepanov, A.V.

1982-01-01

Data on type 2 solar radio bursts are analyzed in the framework of a model of radio emission production by shock waves. Type 2 solar radio bursts data are shown to suggest the existence of Alfven velocity minimum at a height of the one solar radius in the corona. The domain of a low Alfven velocity is a resonator for the fast magnetosonic waves. The eigenmodes of the resonator are determined. The main mode period is about a few minutes. Fast modes in the resonator can be amplified by energetic ion beams at the Cherenkov resonance. The modulation of meter solar radio emission with a period of about a few minutes can be explained by radiowave propagation through the MHD-resonator

An LCLC resonant topology based filament power supply for 300 KeV DC accelerator

International Nuclear Information System (INIS)

Kasliwal, A.; Gauttam, V.K.; Banwari, R.; Pandit, T.G.; Thakurta, A.C.

2013-01-01

A compact, low energy dc accelerator for industrial applications requiring beam energy in the range of 100 to 300 keV is under development at Raja Ramanna Centre for Advanced Technology, Indore. The accelerator uses an indirectly heated LaB6 disc type filament of 4 mm diameter as an electron emitter which is floating at terminal voltage of the accelerator. A power supply is required to heat the filament for its full range of emission. A high frequency inverter operating at fixed frequency feeds the power to the filament through high frequency transformers and capacitive isolation column. A buck chopper controls the dc bus voltage of the inverter so as to control the terminal voltage of the filament thus controlling the beam current. This paper presents the analysis and design of the filament supply that implements a 40 kHz high order LCLC series parallel resonant inverter that utilizes the reflected capacitance of the HV transformer and capacitive isolation column as its tank circuit component. The operating characteristics and analysis of series resonant (SRC), parallel resonant (PRC) and series parallel (SPRC) resonant converters have been reported for fixed frequency operation. It has been shown that SPRC takes the advantage of both SRC and PRC curtailing their disadvantages. Hence a series parallel LCLC combination has been used as it gives the advantage of low device currents and a better load regulation. (author)

Transient currents in a molecular photo-diode

OpenAIRE

Petrov, E. G.; Leonov, V. O.; May, V.; Hänggi, P.

2012-01-01

Light-induced charge transmission through a molecular junction (molecular diode) is studied in the framework of a HOMO-LUMO model and in using a kinetic description. Expressions are presented for the sequential (hopping) and direct (tunneling) transient current components together with kinetic equations governing the time-dependent populations of the neutral and charged molecular states which participate in the current formation. Resonant and off-resonant charge transmission processes are ana...

Current Control of Grid Converters Connected with Series AC Capacitor

DEFF Research Database (Denmark)

Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

2015-01-01

The series ac capacitor has recently been used with the transformerless grid-connected converters in the distribution power grids. The capacitive characteristic of the resulting series LC filter restricts the use of conventional synchronous integral or stationary resonant current controllers. Thus...... this paper proposes a fourth-order resonant controller in the stationary frame, which guarantees a zero steady-state current tracking error for the grid converters with series LC filter. This method is then implemented in a three-phase experimental system for verification, where the current harmonics below...... the LC filter resonance frequency are effectively eliminated. Experimental results confirm the validity of the proposed current control scheme....

High-performance feedback-type active damping of LCL-filtered voltage source converters

DEFF Research Database (Denmark)

Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

2015-01-01

a generalized impedance-based model of grid current control with feedback-type active damping. Then, a controller design method based on the z-domain root contours and frequency-domain passivity theorem is proposed. It not only allows a co-design of the grid current controller and damping controller......Active damping of LCL-filter resonance based on single-state feedback control is widely used with voltage source converters. Its robustness against grid impedance variation has always been a major concern with its controller design. To deal with this issue, this paper begins by developing......, but ensures also a robust stabilization against the grid parameters variations. For illustration, the approach is applied to design three single-state feedback-damping schemes, and their damping robustness are compared under both inductive and resonant grid impedances. Experimental results validate...

Cardiac Involvement in Myotonic Dystrophy Type 2 Patients With Preserved Ejection Fraction: Detection by Cardiovascular Magnetic Resonance.

Science.gov (United States)

Schmacht, Luisa; Traber, Julius; Grieben, Ulrike; Utz, Wolfgang; Dieringer, Matthias A; Kellman, Peter; Blaszczyk, Edyta; von Knobelsdorff-Brenkenhoff, Florian; Spuler, Simone; Schulz-Menger, Jeanette

2016-07-01

Myotonic dystrophy type 2 (DM2) is a genetic disorder characterized by skeletal muscle symptoms, metabolic changes, and cardiac involvement. Histopathologic alterations of the skeletal muscle include fibrosis and fatty infiltration. The aim of this study was to investigate whether subclinical cardiac involvement in DM2 is already detectable in preserved left ventricular function by cardiovascular magnetic resonance. Twenty-seven patients (mean age, 54±10 years; 20 females) with a genetically confirmed diagnosis of DM2 were compared with 17 healthy age- and sex-matched controls using a 1.5 T magnetic resonance imaging. For myocardial tissue differentiation, T1 and T2 mapping, fat/water-separated imaging, focal fibrosis imaging (late gadolinium enhancement [LGE]), and (1)H magnetic resonance spectroscopy were performed. Extracellular volume fraction was calculated. Conduction abnormalities were diagnosed based on Groh criteria. LGE located subepicardial basal inferolateral was detectable in 22% of the patients. Extracellular volume was increased in this region and in the adjacent medial inferolateral segment (P=0.03 compared with healthy controls). In 21% of patients with DM2, fat deposits were detectable (all women). The control group showed no abnormalities. Myocardial triglycerides were not different in LGE-positive and LGE-negative subjects (P=0.47). Six patients had indicators for conduction disease (60% of LGE-positive patients and 12.5% of LGE-negative patients). In DM2, subclinical myocardial injury was already detectable in preserved left ventricular ejection fraction. Extracellular volume was also increased in regions with no focal fibrosis. Myocardial fibrosis was related to conduction abnormalities. © 2016 American Heart Association, Inc.

Integration of Resonant Coil for Wireless Power Transfer and Implantable Antenna for Signal Transfer

Directory of Open Access Journals (Sweden)

Dong-Wook Seo

2016-01-01

Full Text Available We propose the integration of the resonant coil for wireless power transfer (WPT and the implantable antenna for physiological signal transfer. The integration allows for a compact biomedical implantable system such as electrocardiogram (ECG recorder and pacemaker. While the resonant coils resonate at the frequency of 13.56 MHz for the WPT, the implantable antenna works in the medical implant communications service (MICS band of 402–405 MHz for wireless communications. They share the narrow substrate area of a bar-type shape; the coil has the current path on the outer part of the substrate and the meandered planar inverted-F antenna (PIFA occupies the inside of the coil. To verify the potentials of the proposed structure, a prototype is fabricated and tested in vitro. The power transfer efficiency (PTE of about 20% is obtained at a distance of 15 mm and the antenna gain of roughly −40 dBi is achieved.

Alfvenic resonant cavities in the solar atmosphere

International Nuclear Information System (INIS)

Hollweg, J.V.

1984-01-01

We investigate the propagation of Alfven waves in a simple medium consisting of three uniform layers; each layer is characterized by a different value for the Alfven speed, νsub(A). We show how the central layer can act as a resonant cavity under quite general conditions. If the cavity is driven externally, by an incident wave in one of the outer layers, there result resonant transmission peaks, which allow large energy fluxes to enter the cavity from outside. The transmission peaks result from the destructive interference between a wave which leaks out of the cavity, and a directly reflected wave. We show that there are two types of resonances. The first type occurs when the cavity has the largest (or smallest) of the three Alfven speeds; this situation occurs on coronal loops. The second type occurs when the cavity Alfven speed is intermediate between the other two values of νsub(A); this situation may occur on solar spicules. Significant heating of the cavity can occur if the waves are damped. We show that if the energy lost to heat greatly exceeds the energy lost by leakage out of the cavity, then the cavity heating can be independent of the damping rate. This conclusion is shown to apply to coronal resonances and to the spicule resonances. This conclusion agrees with a point made by Ionson in connection with the coronal resonances. Except for a numerical factor of order unity, we recover Ionson's expression for the coronal heating rate. However, Ionson's qualities are much too large. For solar parameters, the maximum quality is of the order of 100, but the heating is independent of the damping rate only when dissipation reduces the quality to less than about 10. (WB)

Kinetic analysis of synthetic analogues of linear-epitope peptides of glycoprotein D of herpes simplex virus type 1 by surface plasmon resonance

NARCIS (Netherlands)

Lasonder, E; Schellekens, GA; Koedijk, DGAM; Damhof, RA; WellingWester, S; Feijlbrief, M; Scheffer, AJ; Welling, GW

1996-01-01

The interaction between mAb A16 and glycoprorein D (gD) of herpes simplex virus type 1 was analyzed by studying the kinetics of binding with a surface-plasmon-resonance biosensor. mAb A16 belongs to group VII antibodies, which recognize residues 11-19 of gD. In a previous study, three critical

Adler-type sum rule, charge symmetry and neutral current in general multi-triplet model

International Nuclear Information System (INIS)

Katuya, Mituaki; Baba, Yoshimitsu; Fujii, Kanji

1975-01-01

We derive Adler-type sum rule extended to general multi-triplet model. Paying attention to roles of the colour degree of freedom, we discuss the charge symmetry property of the weak charged current and the structure functions for ν(ν - )+N→l(l - )+X, and also the structure of the neutral current. A comment is given on implications in our theory of Koike and Konuma's result on the neutral hadronic current. (auth.)

Advanced resonance self-shielding method for gray resonance treatment in lattice physics code GALAXY

International Nuclear Information System (INIS)

Koike, Hiroki; Yamaji, Kazuya; Kirimura, Kazuki; Sato, Daisuke; Matsumoto, Hideki; Yamamoto, Akio

2012-01-01

A new resonance self-shielding method based on the equivalence theory is developed for general application to the lattice physics calculations. The present scope includes commercial light water reactor (LWR) design applications which require both calculation accuracy and calculation speed. In order to develop the new method, all the calculation processes from cross-section library preparation to effective cross-section generation are reviewed and reframed by adopting the current enhanced methodologies for lattice calculations. The new method is composed of the following four key methods: (1) cross-section library generation method with a polynomial hyperbolic tangent formulation, (2) resonance self-shielding method based on the multi-term rational approximation for general lattice geometry and gray resonance absorbers, (3) spatially dependent gray resonance self-shielding method for generation of intra-pellet power profile and (4) integrated reaction rate preservation method between the multi-group and the ultra-fine-group calculations. From the various verifications and validations, applicability of the present resonance treatment is totally confirmed. As a result, the new resonance self-shielding method is established, not only by extension of a past concentrated effort in the reactor physics research field, but also by unification of newly developed unique and challenging techniques for practical application to the lattice physics calculations. (author)

Origin of strain-induced resonances in flexible terahertz metamaterials

International Nuclear Information System (INIS)

Sun Xiu-Yun; Li Xiao-Ning; Xu Hua; Liang Xian-Ting; Zheng Li-Ren; Zhang Xian-Peng; Lu Yue-Hui; Song Wei-Jie; Lee, Young-Pak; Rhee, Joo-Yull

2016-01-01

Two types of flexible terahertz metamaterials were fabricated on polyethylene naphthalate (PEN) substrates. The unit cell of one type consists of two identical split-ring resonators (SRRs) that are arranged face-to-face (i.e., FlexMetaF); the unit cell of the other type has nothing different but is arranged back-to-back (i.e., FlexMetaB). FlexMetaF and FlexMetaB illustrate the similar transmission dips under zero strain because the excitation of fundamental inductive–capacitive (LC) resonance is mainly dependent on the geometric structure of individual SRR. However, if a gradually variant strain is applied to bend FlexMetaF and FlexMetaB, the new resonant peaks appear: in the case of FlexMetaF, the peaks are located at the lower frequencies; in the case of FlexMetaB, the peaks appear at the frequencies adjacent to the LC resonance. The origin and evolution of strain-induced resonances are studied. The origin is ascribed to the detuning effect and the different responses to strain from FlexMetaF and FlexMetaB are associated with the coupling effect. These findings may improve the understanding on flexible terahertz metamaterials and benefit their applications in flexible or curved devices. (paper)

A Short-Current Control Method for Constant Frequency Current-Fed Wireless Power Transfer Systems

Directory of Open Access Journals (Sweden)

Yanling Li

2017-04-01

Full Text Available Frequency drift is a serious problem in Current-Fed Wireless Power Transfer (WPT systems. When the operating frequency is drifting from the inherent Zero Voltage Switching (ZVS frequency of resonant network, large short currents will appear and damage the switches. In this paper, an inductance-dampening method is proposed to inhibit short currents and achieve constant-frequency operation. By adding a small auxiliary series inductance in the primary resonant network, short currents are greatly attenuated to a safe level. The operation principle and steady-state analysis of the system are provided. An overlapping time self-regulating circuit is designed to guarantee ZVS running. The range of auxiliary inductances is discussed and its critical value is calculated exactly. The design methodology is described and a design example is presented. Finally, a prototype is built and the experimental results verify the proposed method.

Space charge in nanostructure resonances

Science.gov (United States)

Price, Peter J.

1996-10-01

In quantum ballistic propagation of electrons through a variety of nanostructures, resonance in the energy-dependent transmission and reflection probabilities generically is associated with (1) a quasi-level with a decay lifetime, and (2) a bulge in electron density within the structure. It can be shown that, to a good approximation, a simple formula in all cases connects the density of states for the latter to the energy dependence of the phase angles of the eigen values of the S-matrix governing the propagation. For both the Lorentzian resonances (normal or inverted) and for the Fano-type resonances, as a consequence of this eigen value formula, the space charge due to filled states over the energy range of a resonance is just equal (for each spin state) to one electron charge. The Coulomb interaction within this space charge is known to 'distort' the electrical characteristics of resonant nanostructures. In these systems, however, the exchange effect should effectively cancel the interaction between states with parallel spins, leaving only the anti-parallel spin contribution.

ECR [electron cyclotron resonance] discharges maintained by radiation in the millimeter wavelength range

International Nuclear Information System (INIS)

Bykov, Yu.V.; Golubev, S.V.; Eremeev, A.G.; Zorin, V.G.

1990-01-01

It is well known that plasmas formed by microwave breakdown of gases under electron cyclotron resonance (ECR) conditions can serve as an efficient source for ion beams. The major disadvantage of this type of source is relatively low ion beam currents which generally do not exceed 1 A (for an electron density of ∼10 12 cm -3 in the discharge). Raising the current density in the ion beams requires a higher plasma density, which can be obtained by using higher frequencies. Thus, a study has recently been made of the parameters of the plasma formed by ECR breakdown in a linear confinement system employing pulsed radiation at a frequency of 60 GHz. The maximum electron densities obtained in the experiment were 2·10 13 cm -3 at a gas pressure of 3·10 -4 torr. In this paper the authors describe some experiments on the creation of plasmas by means of quasi-cw electromagnetic radiation at a frequency of 100 GHz under electron cyclotron resonance conditions

Polarization filtering in the visible wavelength range using surface plasmon resonance and a sunflower-type photonic quasi-crystal fiber

Science.gov (United States)

Yan, Bei; Wang, Anran; Liu, Exian; Tan, Wei; Xie, Jianlan; Ge, Rui; Liu, Jianjun

2018-04-01

A novel polarization filter based on a sunflower-type photonic quasi-crystal fiber (PQF) is proposed in this paper. We also discuss different methods to tune the filter wavelength. The proposed filter can efficiently produce polarized light with visible wavelengths by using the resonance between the second-order surface plasmon polariton mode and the core mode of the PQF. The filtered wavelength can be tuned between 0.55 µm and 0.68 µm by adjusting the thickness of the gold film. When the thickness of the gold film is 25.3 nm, the resonance loss in the y-polarized direction reaches 11707 dB m‑1 for a wavelength of 0.6326 µm, and the full width at half maximum is only 5 nm. Due to the flexible design and absence of both polarization coupling and polarization dispersion, this polarization filter can be used in devices that require narrow-band filtering.

Polarization of Λ hyperons produced inclusively in v p andbar v p charged current interactions

Science.gov (United States)

Jones, G. T.; Kennedy, B. W.; O'Neale, S. W.; Böckmann, K.; Gebel, W.; Geich-Gimbel, C.; Nellen, B.; Cooper-Sarkar, A. M.; Grant, A.; Klein, H.; Morrison, D. R. O.; Schmid, P.; Wachsmuth, H.; Barnham, K. W. J.; Clayton, E. F.; Miller, D. B.; Mobayyen, M. M.; Villalobos-Baillie, O.; Aderholz, M.; Deck, L.; Schmitz, N.; Settles, R.; Wernhard, K. L.; Wittek, W.; Corrigan, G.; Myatt, G.; Radojicic, D.; Saitta, B.; Wells, J.

1985-03-01

Lambda hyperons from v p andbar v p charged current interactions have been analysed for polarization. A significant polarization is observed for Λ particles in the quasi-elastic region for both types of interactions. Part of this polarization is due to the decay of highly polarized Σ(1385) resonances. The results are compared with simple predictions of the quark parton model.

Critical power for lower hybrid current drive

International Nuclear Information System (INIS)

Assis, A.S. de; Sakanaka, P.H.; Azevedo, C.A. de; Busnardo-Neto, J.

1995-11-01

We have solved numerically the quasilinear Fokker-Planck equation which models the critical power for lower hybrid wave current drive. An exact value for the critical power necessary for current saturation, for tokamak current drive experiments, has been obtained. The nonlinear treatment presented here leads to a final profile for the parallel distribution function which is a plateau only in a part of the resonance region. This form of the distribution function is intermediate between two well known results: a plateau throughout the resonance region for the linear strong-source regime, D wave >> D coll and no plateau at all in the resonance region the linear weak-source regimen, D wave coll . The strength of the external power source and the value of the dc electric field are treated as given parameters in the integration scheme. (author). 24 refs, 6 figs

Revisiting the Characterization of the Losses in Piezoelectric Materials from Impedance Spectroscopy at Resonance

Directory of Open Access Journals (Sweden)

Amador M. González

2016-01-01

Full Text Available Electronic devices using the piezoelectric effect contain piezoelectric materials: often crystals, but in many cases poled ferroelectric ceramics (piezoceramics, polymers or composites. On the one hand, these materials exhibit non-negligible losses, not only dielectric, but also mechanical and piezoelectric. In this work, we made simulations of the effect of the three types of losses in piezoelectric materials on the impedance spectrum at the resonance. We analyze independently each type of loss and show the differences among them. On the other hand, electrical and electronic engineers include piezoelectric sensors in electrical circuits to build devices and need electrical models of the sensor element. Frequently, material scientists and engineers use different languages, and the characteristic material coefficients do not have a straightforward translation to those specific electrical circuit components. To connect both fields of study, we propose the use of accurate methods of characterization from impedance measurements at electromechanical resonance that lead to determination of all types of losses, as an alternative to current standards. We introduce a simplified equivalent circuit model with electrical parameters that account for piezoceramic losses needed for the modeling and design of industrial applications.

Revisiting the Characterization of the Losses in Piezoelectric Materials from Impedance Spectroscopy at Resonance.

Science.gov (United States)

González, Amador M; García, Álvaro; Benavente-Peces, César; Pardo, Lorena

2016-01-26

Electronic devices using the piezoelectric effect contain piezoelectric materials: often crystals, but in many cases poled ferroelectric ceramics (piezoceramics), polymers or composites. On the one hand, these materials exhibit non-negligible losses, not only dielectric, but also mechanical and piezoelectric. In this work, we made simulations of the effect of the three types of losses in piezoelectric materials on the impedance spectrum at the resonance. We analyze independently each type of loss and show the differences among them. On the other hand, electrical and electronic engineers include piezoelectric sensors in electrical circuits to build devices and need electrical models of the sensor element. Frequently, material scientists and engineers use different languages, and the characteristic material coefficients do not have a straightforward translation to those specific electrical circuit components. To connect both fields of study, we propose the use of accurate methods of characterization from impedance measurements at electromechanical resonance that lead to determination of all types of losses, as an alternative to current standards. We introduce a simplified equivalent circuit model with electrical parameters that account for piezoceramic losses needed for the modeling and design of industrial applications.

Shot noise of spin current and spin transfer torque

Science.gov (United States)

Yu, Yunjin; Zhan, Hongxin; Wan, Langhui; Wang, Bin; Wei, Yadong; Sun, Qingfeng; Wang, Jian

2013-04-01

We report the theoretical investigation of the shot noise of the spin current (Sσ) and the spin transfer torque (Sτ) for non-collinear spin polarized transport in a spin-valve device which consists of a normal scattering region connected by two ferromagnetic electrodes (MNM system). Our theory was developed using the non-equilibrium Green’s function method, and general nonlinear Sσ - V and Sτ - V relations were derived as a function of the angle θ between the magnetizations of two leads. We have applied our theory to a quantum dot system with a resonant level coupled with two ferromagnetic electrodes. It was found that, for the MNM system, the auto-correlation of the spin current is enough to characterize the fluctuation of the spin current. For a system with three ferromagnetic layers, however, both auto-correlation and cross-correlation of the spin current are needed to characterize the noise of the spin current. For a quantum dot with a resonant level, the derivative of spin torque with respect to bias voltage is proportional to sinθ when the system is far away from resonance. When the system is near resonance, the spin transfer torque becomes a non-sinusoidal function of θ. The derivative of the noise of the spin transfer torque with respect to the bias voltage Nτ behaves differently when the system is near or far away from resonance. Specifically, the differential shot noise of the spin transfer torque Nτ is a concave function of θ near resonance while it becomes a convex function of θ far away from resonance. For certain bias voltages, the period Nτ(θ) becomes π instead of 2π. For small θ, it was found that the differential shot noise of the spin transfer torque is very sensitive to the bias voltage and the other system parameters.

Tilted spin torque-driven ferromagnetic resonance in a perpendicular-analyzer magnetic trilayer

International Nuclear Information System (INIS)

Wang Rixing; He Pengbin; Liu Quanhui; Li Zaidong; Pan Anlian; Zou Bingsuo; Wang Yanguo

2010-01-01

A theoretical study is presented on the current-driven ferromagnetic resonance in the magnetic trilayers. On the basis of the Landau-Lifshitz-Gilbert-Slonczewski equation, we derive the output dc voltage for arbitrary anisotropy in the free and pinned layers by the linearization method. As an example, the resonance spectra of the tilted-polarizer and perpendicular-analyzer trilayer show that the equilibrium position, the resonant linewidth and the resonant location can be tuned by changing the magnitude and the direction of spin torque. The effective damping can be minimized through adjusting the current and the pinned-layer magnetization direction.

Resonance Transport of Graphene Nanoribbon T-Shaped Junctions

International Nuclear Information System (INIS)

Xiao-Lan, Kong; Yong-Jian, Xiong

2010-01-01

We investigate the transport properties of T-shaped junctions composed of armchair graphene nanoribbons of different widths. Three types of junction geometries are considered. The junction conductance strongly depends on the atomic features of the junction geometry. When the shoulders of the junction have zigzag type edges, sharp conductance resonances usually appear in the low energy region around the Dirac point, and a conductance gap emerges. When the shoulders of the junction have armchair type edges, the conductance resonance behavior is weakened significantly, and the metal-metal-metal junction structures show semimetallic behaviors. The contact resistance also changes notably due to the various interface geometries of the junction

Current variables, definitions and endpoints of the European Cardiovascular Magnetic Resonance Registry

Directory of Open Access Journals (Sweden)

Schwitter Juerg

2009-11-01

Full Text Available Abstract Background Cardiovascular Magnetic Resonance (CMR is increasingly used in daily clinical practice. However, little is known about its clinical utility such as image quality, safety and impact on patient management. In addition, there is limited information about the potential of CMR to acquire prognostic information. Methods The European Cardiovascular Magnetic Resonance Registry (EuroCMR Registry will consist of two parts: 1 Multicenter registry with consecutive enrolment of patients scanned in all participating European CMR centres using web based online case record forms. 2 Prospective clinical follow up of patients with suspected coronary artery disease (CAD and hypertrophic cardiomyopathy (HCM every 12 months after enrolment to assess prognostic data. Conclusion The EuroCMR Registry offers an opportunity to provide information about the clinical utility of routine CMR in a large number of cases and a diverse population. Furthermore it has the potential to gather information about the prognostic value of CMR in specific patient populations.

Evaluation of plate type fuel elements by eddy current test method

International Nuclear Information System (INIS)

Frade, Rangel Teixeira

2015-01-01

Plate type fuel elements are used in MTR research nuclear reactors. The fuel plates are manufactured by assembling a briquette containing the fissile material inserted in a frame, with metal plates in both sides of the set, to act as a cladding. This set is rolled under controlled conditions in order to obtain the fuel plate. In Brazil, this type of fuel is manufactured by IPEN and used in the IEA-R1 reactor. After fabrication of three batches of fuel plates, 24 plates, one of them is taken, in order to verify the thickness of the cladding. For this purpose, the plate is sectioned and the thickness measurements are carried out by using optical microscopy. This procedure implies in damage of the plate, with the consequent cost. Besides, the process of sample preparation for optical microscopy analysis is time consuming, it is necessary an infrastructure for handling radioactive materials and there is a generation of radioactive residues during the process. The objective of this study was verify the applicability of eddy current test method for nondestructive measurement of cladding thickness in plate type nuclear fuels, enabling the inspection of all manufactured fuel plates. For this purpose, reference standards, representative of the cladding of the fuel plates, were manufactured using thermomechanical processing conditions similar to those used for plates manufacturing. Due to no availability of fuel plates for performing the experiments, the presence of the plate’s core was simulated using materials with different electrical conductivities, fixed to the thickness reference standards. Probes of eddy current testing were designed and manufactured. They showed high sensitivity to thickness variations, being able to separate small thickness changes. The sensitivity was higher in tests performed on the reference standards and samples without the presence of the materials simulating the core. For examination of the cladding with influence of materials simulating the

On the fundamental mode of the optical resonator with toroidal mirrors

Energy Technology Data Exchange (ETDEWEB)

Serednyakov, S.S.; Vinokurov, N.A. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation)

1995-12-31

The fundamental mode of the optical resonator with the toroidal mirrors is investigated. The losses in such resonator with the on-axis holes are low in compare with the case of spherical mirrors. The use of this type of optical resonator is briefly discussed.

Resonance – Journal of Science Education | News

Indian Academy of Sciences (India)

Resonance – Journal of Science Education. Current Issue : Vol. 23, Issue 4. Current Issue Volume 23 | Issue 4. April 2018. Home · Volumes & Issues · Categories · Special Issues · Search · Editorial Board · Information for Authors · Subscription ...

Direct-Current Forced Interruption and Breaking Performance of Spiral-Type Contacts in Aero Applications

Directory of Open Access Journals (Sweden)

Wenlei Huo

2017-05-01

Full Text Available This paper analyses the transient characteristics and breaking performance of direct-current (DC forced-interruption vacuum interrupters in 270 V power-supply systems. Three stages are identified in forced interruption: the DC-arcing stage, current-commutation stage, and voltage-recovery stage. During the current-commutation stage, the reverse peak-current coefficient k, which is a key design factor, is used to calculate the rate of current at zero-crossing (di/dt. MATLAB/Simulink simulation models are established to obtain the transient characteristics influenced by the forced-commutation branch parameters and the coefficient k. To study the breaking performance of spiral-type contacts, experiments are conducted for different contact materials and arcing times for currents less than 3.5 kA. During the DC-arcing stage, a locally intensive burning arc is observed in the CuW80 contact; however, it is not observed in the CuCr50 contact. On examining the re-ignition interruption results of the CuW80 contact, the intensive burning arc is found to be positioned within a possible re-ignition region. When the arcing time is longer than 1 ms, the intensive burning arc occurs and affects the breaking performance of the spiral-type contacts. If the DC-arcing stage is prolonged, the total arcing energy increases, which leads to a lower breaking capacity.

Effect of external noise on the current response in superlattices

International Nuclear Information System (INIS)

Suqing Duan; Wu Binyi; Wang Zhigang; Zhao Xiangeng

2004-01-01

Within the single-band model and the nearest-neighbor approximation we investigate the effect of external noise on the current response driven by dc-ac field which has a fluctuating component. We find the external noise can destroy the current resonant peaks. When the strength of the external noise becomes enough large, all the current resonant peaks will completely disappear

The influence of temperature in the characterization of nuclear resonance

International Nuclear Information System (INIS)

Campos, T.P.R. de; Martinez, A.S.

1986-01-01

A detailed analysis carried out to determine the temperature effects on the selection of different types of resonance for Resonance Integral calculations is presented. The type of approximation (WR, IR or NR) to be applied to the slowing down integral of the neutron balance equation depends on the relationship between the average energy lost by the neutron and the practical width. A method to include the temperature dependence in the ratio ΔE/GAMMA sub(p) is proposed. The results allowed us to show that this dependence negligence may lead to large errors in the Resonance Integral calculation. (Author) [pt

Induced current magnetic resonance electrical impedance tomography of brain tissues based on the J-substitution algorithm: a simulation study

International Nuclear Information System (INIS)

Liu Yang; Zhu Shanan; He Bin

2009-01-01

We have investigated induced current magnetic resonance electrical impedance tomography (IC-MREIT) by means of computer simulations. The J-substitution algorithm was implemented to solve the IC-MREIT reconstruction problem. By providing physical insight into the charge accumulating on the interfaces, the convergence characteristics of the reconstruction algorithm were analyzed. The simulation results conducted on different objects were well correlated with the proposed theoretical analysis. The feasibility of IC-MREIT to reconstruct the conductivity distribution of head-brain tissues was also examined in computer simulations using a multi-compartment realistic head model. The present simulation results suggest that IC-MREIT may have the potential to become a useful conductivity imaging technique.

Mixed frequency excitation of an electrostatically actuated resonator

KAUST Repository

Ramini, Abdallah

2015-04-24

We investigate experimentally and theoretically the dynamics of a capacitive resonator under mixed frequency excitation of two AC harmonic signals. The resonator is composed of a proof mass suspended by two cantilever beams. Experimental measurements are conducted using a laser Doppler vibrometer to reveal the interesting dynamics of the system when subjected to two-source excitation. A nonlinear single-degree-of-freedom model is used for the theoretical investigation. The results reveal combination resonances of additive and subtractive type, which are shown to be promising to increase the bandwidth of the resonator near primary resonance frequency. Our results also demonstrate the ability to shift the combination resonances to much lower or much higher frequency ranges. We also demonstrate the dynamic pull-in instability under mixed frequency excitation. © 2015 Springer-Verlag Berlin Heidelberg

Current Mode Control for LLC Series Resonant DC-to-DC Converters

OpenAIRE

Jinhaeng Jang; Syam Kumar Pidaparthy; Byungcho Choi

2015-01-01

Conventional voltage mode control only offers limited performance for LLC series resonant DC-to-DC converters experiencing wide variations in operational conditions. When the existing voltage mode control is employed, the closed-loop performance of the converter is directly affected by unavoidable changes in power stage dynamics. Thus, a specific control design optimized at one particular operating point could become unacceptable when the operational condition is varied. This paper presents a...

Description of the resonance treatment in WIMS-AECL

Energy Technology Data Exchange (ETDEWEB)

Donnelly, J V

1993-05-01

The Stamm`ler resonance treatment as applied within the WIMS-AECL lattice cell code is described. The validation work demonstrating the accuracy of the resonance treatment is reviewed and indicates that the methods used will be accurate for the current range of application within AECL. (author). 22 refs., 6 tabs.

Multiple endocrine neoplasia type 2: achievements and current challenges

Directory of Open Access Journals (Sweden)

Andreas Machens

2012-01-01

Full Text Available Incremental advances in medical technology, such as the development of sensitive hormonal assays for routine clinical care, are the drivers of medical progress. This principle is exemplified by the creation of the concept of multiple endocrine neoplasia type 2, encompassing medullary thyroid cancer, pheochromocytoma, and primary hyperparathyroidism, which did not emerge before the early 1960s. This review sets out to highlight key achievements, such as joint biochemical and DNA-based screening of individuals at risk of developing multiple endocrine neoplasia type 2, before casting a spotlight on current challenges which include: (i ill-defined upper limits of calcitonin assays for infants and young children, rendering it difficult to implement the biochemical part of the integrated DNA-based/biochemical concept; (ii our increasingly mobile society in which different service providers are caring for one individual at various stages in the disease process. With familial relationships disintegrating as a result of geographic dispersion, information about the history of the origin family may become sketchy or just unavailable. This is when DNA-based gene tests come into play, confirming or excluding an individual's genetic predisposition to multiple endocrine neoplasia type 2 even before there is any biochemical or clinical evidence of the disease. However, the unrivaled molecular genetic progress in multiple endocrine neoplasia type 2 does not come without a price. Screening may uncover unknown gene sequence variants representing either harmless polymorphisms or pathogenic mutations. In this setting, functional characterization of mutant cells in vitro may generate helpful ancillary evidence with regard to the pathogenicity of gene variants in comparison with established mutations.

Magnetic resonance imaging of the fetal brain.

Science.gov (United States)

Tee, L Mf; Kan, E Yl; Cheung, J Cy; Leung, W C

2016-06-01

This review covers the recent literature on fetal brain magnetic resonance imaging, with emphasis on techniques, advances, common indications, and safety. We conducted a search of MEDLINE for articles published after 2010. The search terms used were "(fetal OR foetal OR fetus OR foetus) AND (MR OR MRI OR [magnetic resonance]) AND (brain OR cerebral)". Consensus statements from major authorities were also included. As a result, 44 relevant articles were included and formed the basis of this review. One major challenge is fetal motion that is largely overcome by ultra-fast sequences. Currently, single-shot fast spin-echo T2-weighted imaging remains the mainstay for motion resistance and anatomical delineation. Recently, a snap-shot inversion recovery sequence has enabled robust T1-weighted images to be obtained, which is previously a challenge for standard gradient-echo acquisitions. Fetal diffusion-weighted imaging, diffusion tensor imaging, and magnetic resonance spectroscopy are also being developed. With multiplanar capabilities, superior contrast resolution and field of view, magnetic resonance imaging does not have the limitations of sonography, and can provide additional important information. Common indications include ventriculomegaly, callosum and posterior fossa abnormalities, and twin complications. There are safety concerns about magnetic resonance-induced heating and acoustic damage but current literature showed no conclusive evidence of deleterious fetal effects. The American College of Radiology guideline states that pregnant patients can be accepted to undergo magnetic resonance imaging at any stage of pregnancy if risk-benefit ratio to patients warrants that the study be performed. Magnetic resonance imaging of the fetal brain is a safe and powerful adjunct to sonography in prenatal diagnosis. It can provide additional information that aids clinical management, prognostication, and counselling.

Suppression of large edge localized modes with edge resonant magnetic fields in high confinement DIII-D plasmas

International Nuclear Information System (INIS)

Thomas, P.R.; Becoulet, M.; Evans, T.E.; Osborne, T.H.; Groebner, R.J.; Jackson, G.L.; Haye, R.J. La; Schaffer, M.J.; West, W.P.; Moyer, R.A.; Rhodes, T.L.; Rudakov, D.L.; Watkins, J.G.; Boedo, J.A.; Doyle, E.J.; Wang, G.; Zeng, L.; Fenstermacher, M.E.; Groth, M.; Lasnier, C.J.; Finken, K.H.; Harris, J.H.; Pretty, D.G.; Masuzaki, S.; Ohyabu, N.; Reimerdes, H.; Wade, M.R.

2005-01-01

Large divertor heat pulses due to Type-I edge localized modes (ELMs) have been eliminated reproducibly in DIII-D with small dc currents driven in a simple magnetic perturbation coil. The current required to eliminate all but a few isolated Type-I ELMs, during a coil pulse, is less than 0.4% of plasma current. Modelling shows that the perturbation fields resonate with plasma flux surfaces across most of the pedestal region (0.9 ≤ N ≤ 1.0), when q95 = 3.7±0.2 creating small remnant magnetic islands surrounded by weakly stochastic field lines. The stored energy, N , H-mode quality factor and global energy confinement time are unaltered by the magnetic perturbation. At high collisionality (ν* ∼0.5-1), there is no obvious effect of the perturbation on the edge profiles and yet ELMs are suppressed, nearly completely, for up to 9τ E . At low collisionality (ν* <0.1), there is a density pump-out and complete ELM suppression, reminiscent of the DIIID QH- mode. Other differences, specifically in the resonance condition and the magnetic fluctuations, suggest that different mechanisms are at play in the different collisionality regimes. In addition to a description and interpretation of the DIIID data, the application of this method to ELM control on other machines, such as JET and ITER will be discussed. (author)

Loss mechanisms in superconducting thin film microwave resonators

Energy Technology Data Exchange (ETDEWEB)

Goetz, Jan, E-mail: jan.goetz@wmi.badw.de; Haeberlein, Max; Wulschner, Friedrich; Zollitsch, Christoph W.; Meier, Sebastian; Fischer, Michael; Fedorov, Kirill G.; Menzel, Edwin P. [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching (Germany); Physik-Department, Technische Universität München, 85748 Garching (Germany); Deppe, Frank; Eder, Peter; Xie, Edwar; Gross, Rudolf, E-mail: rudolf.gross@wmi.badw.de [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching (Germany); Physik-Department, Technische Universität München, 85748 Garching (Germany); Nanosystems Initiative Munich (NIM), Schellingstraße 4, 80799 München (Germany); Marx, Achim [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching (Germany)

2016-01-07

We present a systematic analysis of the internal losses of superconducting coplanar waveguide microwave resonators based on niobium thin films on silicon substrates. In particular, we investigate losses introduced by Nb/Al interfaces in the center conductor, which is important for experiments where Al based Josephson junctions are integrated into Nb based circuits. We find that these interfaces can be a strong source for two-level state (TLS) losses, when the interfaces are not positioned at current nodes of the resonator. In addition to TLS losses, for resonators including Al, quasiparticle losses become relevant above 200 mK. Finally, we investigate how losses generated by eddy currents in conductive material on the backside of the substrate can be minimized by using thick enough substrates or metals with high conductivity on the substrate backside.

MSW-resonant fermion mixing during reheating

Science.gov (United States)

Kanai, Tsuneto; Tsujikawa, Shinji

2003-10-01

We study the dynamics of reheating in which an inflaton field couples two flavor fermions through Yukawa-couplings. When two fermions have a mixing term with a constant coupling, we show that the Mikheyev-Smirnov-Wolfenstein (MSW)-type resonance emerges due to a time-dependent background in addition to the standard fermion creation via parametric resonance. This MSW resonance not only alters the number densities of fermions generated by a preheating process but also can lead to the larger energy transfer from the inflaton to fermions. Our mechanism can provide additional source terms for the creation of superheavy fermions which may be relevant for the leptogenesis scenario.

MSW-resonant fermion mixing during reheating

International Nuclear Information System (INIS)

Kanai, Tsuneto; Tsujikawa, Shinji

2003-01-01

We study the dynamics of reheating in which an inflaton field couples two flavor fermions through Yukawa-couplings. When two fermions have a mixing term with a constant coupling, we show that the Mikheyev-Smirnov-Wolfenstein (MSW)-type resonance emerges due to a time-dependent background in addition to the standard fermion creation via parametric resonance. This MSW resonance not only alters the number densities of fermions generated by a preheating process but also can lead to the larger energy transfer from the inflaton to fermions. Our mechanism can provide additional source terms for the creation of superheavy fermions which may be relevant for the leptogenesis scenario

Robust Two Degrees-of-freedom Single-current Control Strategy for LCL-type Grid-Connected DG System under Grid-Frequency Fluctuation and Grid-impedance Variation

DEFF Research Database (Denmark)

Zhou, Leming; Chen, Yandong; Luo, An

2016-01-01

-of-freedom single-current control (RTDOF-SCC) strategy is proposed, which mainly includes the synchronous reference frame quasi-proportional-integral (SRFQPI) control and robust grid-current-feedback active damping (RGCFAD) control. The proposed SRFQPI control can compensate the local-loads reactive power......, and regulate the instantaneous grid current without steady-state error regardless of the fundamental frequency fluctuation. Simultaneously, the proposed RGCFAD control effectively damps the LCL-resonance peak regardless of the grid-impedance variation, and further improves both transient and steady...

Magnetic resonance visualization of conductive structures by sequence-triggered direct currents and spin-echo phase imaging

Energy Technology Data Exchange (ETDEWEB)

Eibofner, Frank; Wojtczyk, Hanne; Graf, Hansjörg, E-mail: hansjoerg.graf@med.uni-tuebingen.de, E-mail: drGraf@t-online.de [Section on Experimental Radiology, University Hospital Tübingen, Tübingen D-72076 (Germany); Clasen, Stephan [Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen D-72076 (Germany)

2014-06-15

Purpose: Instrument visualization in interventional magnetic resonance imaging (MRI) is commonly performed via susceptibility artifacts. Unfortunately, this approach suffers from limited conspicuity in inhomogeneous tissue and disturbed spatial encoding. Also, susceptibility artifacts are controllable only by sequence parameters. This work presents the basics of a new visualization method overcoming such problems by applying sequence-triggered direct current (DC) pulses in spin-echo (SE) imaging. SE phase images allow for background free current path localization. Methods: Application of a sequence-triggered DC pulse in SE imaging, e.g., during a time period between radiofrequency excitation and refocusing, results in transient field inhomogeneities. Dependent on the additional z-magnetic field from the DC, a phase offset results despite the refocusing pulse. False spatial encoding is avoided by DC application during periods when read-out or slice-encoding gradients are inactive. A water phantom containing a brass conductor (water equivalent susceptibility) and a titanium needle (serving as susceptibility source) was used to demonstrate the feasibility. Artifact dependence on current strength and orientation was examined. Results: Without DC, the brass conductor was only visible due to its water displacement. The titanium needle showed typical susceptibility artifacts. Applying triggered DC pulses, the phase offset of spins near the conductor appeared. Because SE phase images are homogenous also in regions of persistent field inhomogeneities, the position of the conductor could be determined with high reliability. Artifact characteristic could be easily controlled by amperage leaving sequence parameters unchanged. For an angle of 30° between current and static field visualization was still possible. Conclusions: SE phase images display the position of a conductor carrying pulsed DC free from artifacts caused by persistent field inhomogeneities. Magnitude and phase

Resonant Tunneling in Gated Vertical One- dimensional Structures

Science.gov (United States)

Kolagunta, V. R.; Janes, D. B.; Melloch, M. R.; Webb, K. J.

1997-03-01

Vertical sub-micron transistors incorporating resonant tunneling multiple quantum well heterostructures are interesting in applications for both multi-valued logic devices and the study of quantization effects in vertical quasi- one-, zero- dimensional structures. Earlier we have demonstrated room temperature pinch-off of the resonant peak in sub-micron vertical resonant tunneling transistors structures using a self-aligned sidewall gating technique ( V.R. Kolagunta et. al., Applied Physics Lett., 69), 374(1996). In this paper we present the study of gating effects in vertical multiple quantum well resonant tunneling transistors. Multiple well quasi-1-D sidewall gated transistors with mesa dimensions of L_x=0.5-0.9μm and L_y=10-40μm were fabricated. The quantum heterostructure in these devices consists of two non-symmetric (180 ÅÅi-GaAs wells separated from each other and from the top and bottom n^+ GaAs/contacts region using Al_0.3Ga_0.7As tunneling barriers. Room temperature pinch-off of the multiple resonant peaks similar to that reported in the case of single well devices is observed in these devices^1. Current-voltage characteristics at liquid nitrogen temperatures show splitting of the resonant peaks into sub-bands with increasing negative gate bias indicative of quasi- 1-D confinement. Room-temperature and low-temperature current-voltage measurements shall be presented and discussed.

Direct-current-like Phase Space Manipulation Using Chirped Alternating Current Fields

International Nuclear Information System (INIS)

Schmit, P.F.; Fisch, N.J.

2010-01-01

Waves in plasmas can accelerate particles that are resonant with the wave. A dc electric field also accelerates particles, but without a resonance discrimination, which makes the acceleration mechanism profoundly different. Whereas wave-particle acceleration mechanisms have been widely discussed in the literature, this work discusses the direct analogy between wave acceleration and dc field acceleration in a particular parameter regime explored in previous works. Apart from the academic interest of this correspondence, there may be practical advantages in using waves to mimic dc electric fields, for example, in driving plasma current with high efficiency.

Compact Dual-Band Zeroth-Order Resonance Antenna

International Nuclear Information System (INIS)

Xu He-Xiu; Wang Guang-Ming; Gong Jian-Qiang

2012-01-01

A novel microstrip zeroth-order resonator (ZOR) antenna and its equivalent circuit model are exploited with two zeroth-order resonances. It is constructed based on a resonant-type composite right/left handed transmission line (CRLH TL) using a Wunderlich-shaped extended complementary single split ring resonator pair (W-ECSSRRP) and a series capacitive gap. The gap either can be utilized for double negative (DNG) ZOR antenna or be removed to engineer a simplified elision-negative ZOR (ENG) antenna. For verification, a DNG ZOR antenna sample is fabricated and measured. Numerical and experimental results agree well with each other, indicating that the omnidirectional radiations occur at two frequency bands which are accounted for by two shunt branches in the circuit model. The size of the antenna is 49% more compact than its previous counterpart. The superiority of W-ECSSRRP over CSSRRP lies in the lower fundamental resonance of the antenna by 38.2% and the introduction of a higher zeroth-order resonance. (fundamental areas of phenomenology(including applications))

Influence of the whispering-gallery mode resonators shape on its inertial movement sensitivity

Science.gov (United States)

Filatov, Yuri V.; Kukaev, Alexander S.; Shalymov, Egor V.; Venediktov, Vladimir Yu.

2018-01-01

The optical whispering-gallery mode (WGM) resonators are axially symmetrical resonators with smooth edges, supporting the existence of the WGMs by the total internal reflection on the surface of the resonator. As of today, various types of such resonators have been developed, namely the ball shaped, tor shaped, bottle shaped, disk shaped, etc. The movement of WGM resonators in inertial space causes the changes in their shape. The result is a spectral shift of the WGMs. Optical methods allow to register this shift with high precision. It can be used in particular for the measurement of angular velocities in inertial orientation and navigation systems. However, different types of resonators react to the movement in different manners. In addition, their sensitivity to movement can be changed when changing the geometric parameters of these resonators. The work is devoted to investigation of these aspects.

Magnetic Resonance Imaging (MRI) -- Head

Medline Plus

Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) - ...

Vanishing chiral couplings in the large-NC resonance theory

International Nuclear Information System (INIS)

Portoles, Jorge; Rosell, Ignasi; Ruiz-Femenia, Pedro

2007-01-01

The construction of a resonance theory involving hadrons requires implementing the information from higher scales into the couplings of the effective Lagrangian. We consider the large-N C chiral resonance theory incorporating scalars and pseudoscalars, and we find that, by imposing LO short-distance constraints on form factors of QCD currents constructed within this theory, the chiral low-energy constants satisfy resonance saturation at NLO in the 1/N C expansion

Surface current double-heterogeneous multilayer multicell methodology

International Nuclear Information System (INIS)

Stepanek, J.; Segev, M.

1991-01-01

A surface current methodology is developed to respond to the need for treating the various levels of material heterogeneity in a double-heterogeneous multilayer multicell in processing neutron multigroup cross sections in the resonance as well as thermal energy range. First, the basic surface cosine current transport equations to calculate the energy-dependent neutron flux spatial distribution in the multilayered multicell are formulated. Slab, spherical and cylindrical geometries, as well as square and hexagonal lattices and pebble-bed configurations with white or reflective cell boundary conditions, are considered. Second, starting from the surface cosine-current formulation, a two-zone three-layer multicell formalism for reduction of heterogeneous flux expressions to equivalent homogeneous flux expression for table method was developed. This formalism allows an infinite, as well as a limited, number of second-heterogeneity cells within a partial first-heterogeneity cell layer to be considered. Also, the number of the first-and second-heterogeneity cell types is quite general. The 'outer' (right side) as well as 'inner' (left side) Dancoff probabilities can be calculated for any particular layer. An accurate, efficient, and compact interpolation procedure is developed to calculate the basic collision probabilities. These are transmission and escape probabilities for shells in slab, cylindrical, and spherical geometries, as well as Dancoff probabilities for cylinders in square and hexagonal lattices. The use of the interpolation procedure is exemplified in a multilayer multicell approximation for the Dancoff probability, enabling a routine evaluation of the equivalence-based shielded resonance integral in highly complex lattices of slab, cylindrical, or spherical cells. (author) 1 fig., 2 tabs., 10 refs

Polarization of Λ hyperons produced inclusively in νp and anti νp charged current interactions

International Nuclear Information System (INIS)

Jones, G.T.; Kennedy, B.W.; O'Neale, S.W.; Barnham, K.W.J.; Clayton, E.F.; Miller, D.B.; Mobayyen, M.M.; Villalobos-Baillie, O.; Corrigan, G.; Myatt, G.; Radojicic, D.; Saitta, B.; Wells, J.; Aderholz, M.; Deck, L.; Schmitz, N.; Settles, R.; Wernhard, K.L.; Wittek, W.

1985-01-01

Lambda hyperons from νp and anti np charged current interactions have been analysed for polarization. A significant polarization is observed for Λ particles in the quasi-elastic region for both types of interactions. Part of this polarization is due to the decay of highly polarized Σ(1385) resonances. The results are compared with simple predictions of the quark parton model. (orig.)

Polarization of Λ hyperons produced inclusively in νp and anti νp charged current interactions

International Nuclear Information System (INIS)

Jones, G.T.; Kennedy, B.W.; O'Neale, S.W.; Barnham, K.W.J.; Clayton, E.F.; Miller, D.B.; Mobayyen, M.M.; Villalobos-Baillie, O.; Corrigan, G.; Myatt, G.; Radojicic, D.; Saitta, B.; Wells, J.

1985-01-01

Lambda hyperons from νp charged current interactions have been analysed for polarization. A significant polarization is observed for Λ particles in the quasi-elastic region for both types of interactions. Part of this polarization is due to the decay of highly polarized phi(1,385) resonances. The results are compared with simple predictions of the quark parton model. (orig.)

Magnetic Resonance Neurography Visualizes Abnormalities in Sciatic and Tibial Nerves in Patients With Type 1 Diabetes and Neuropathy.

Science.gov (United States)

Vaeggemose, Michael; Pham, Mirko; Ringgaard, Steffen; Tankisi, Hatice; Ejskjaer, Niels; Heiland, Sabine; Poulsen, Per L; Andersen, Henning

2017-07-01

This study evaluates whether diffusion tensor imaging magnetic resonance neurography (DTI-MRN), T2 relaxation time, and proton spin density can detect and grade neuropathic abnormalities in patients with type 1 diabetes. Patients with type 1 diabetes ( n = 49) were included-11 with severe polyneuropathy (sDPN), 13 with mild polyneuropathy (mDPN), and 25 without polyneuropathy (nDPN)-along with 30 healthy control subjects (HCs). Clinical examinations, nerve conduction studies, and vibratory perception thresholds determined the presence and severity of DPN. DTI-MRN covered proximal (sciatic nerve) and distal (tibial nerve) nerve segments of the lower extremity. Fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) were calculated, as were T2 relaxation time and proton spin density obtained from DTI-MRN. All magnetic resonance findings were related to the presence and severity of neuropathy. FA of the sciatic and tibial nerves was lowest in the sDPN group. Corresponding with this, proximal and distal ADCs were highest in patients with sDPN compared with patients with mDPN and nDPN, as well as the HCs. DTI-MRN correlated closely with the severity of neuropathy, demonstrating strong associations with sciatic and tibial nerve findings. Quantitative group differences in proton spin density were also significant, but less pronounced than those for DTI-MRN. In conclusion, DTI-MRN enables detection in peripheral nerves of abnormalities related to DPN, more so than proton spin density or T2 relaxation time. These abnormalities are likely to reflect pathology in sciatic and tibial nerve fibers. © 2017 by the American Diabetes Association.

Performance investigation of stochastic resonance in bistable systems with time-delayed feedback and three types of asymmetries

Science.gov (United States)

Liu, Jian; Wang, Youguo

2018-03-01

The simultaneous influence of potential asymmetries and time-delayed feedback on stochastic resonance (SR) subject to both periodic force and additive Gaussian white noise is investigated by using two-state theory and small-delay approximation, where three types of asymmetries include well-depth, well-width, and both well-depth and well-width asymmetries, respectively. The asymmetric types and time-delayed feedback determine the behaviors of SR, especially output signal-to-noise ratio (SNR) peaks, optimal additive noise intensity and feedback intensity. Moreover, the largest SNR in asymmetric SR is found to be relatively larger than symmetric one in some cases, whereas in other cases the symmetric SR is superior to asymmetric one, which is of dependence on time delay and feedback intensity. In addition, the SR with well-width asymmetry can suppress stronger noise than that with well-depth asymmetry under the action of same time delay, which is beneficial to weak signal detection.

Complicated Fermi-type vibronic resonance: Untangling of the single-site quasi-line fluorescence excitation spectra of a methylated dibenzoporphin

International Nuclear Information System (INIS)

Arabei, S.M.; Kuzmitsky, V.A.; Solovyov, K.N.

2008-01-01

The quasi-line low-temperature (4.2 K) fluorescence excitation spectra of 2,3,12,13-tetramethyldibenzo[g,q]porphin introduced into an n-octane matrix have been measured in the range of the S 2 0 electronic transition at selective fluorescence monitoring for the two main types of impurity centers (sites). A characteristic feature of these spectra is that a conglomerate of quasi-lines - a structured complex band - is observed instead of one 0-0 quasi-line of the S 2 0 transition. In this band, the intensity distributions for the two main sites considerably differ from each other. The occurrence of such conglomerates is interpreted as a result of nonadiabatic vibrational-electronic interaction between the vibronic S 2 and S 1 states (the complex vibronic analogue of the Fermi resonance). The frequencies and intensities of individual transitions determined from the deconvolution of complex conglomerates are used as the initial data for solving the inverse spectroscopic problem: the determination of the unperturbed electronic and vibrational levels of states involved in the resonance and the vibronic-interaction matrix elements between them. This problem is solved with a method developed previously. The experimental results and their analysis are compared to the analogous data obtained earlier for meso-tetraazaporphin and meso-tetrapropylporphin. The energy intervals between the S 2 and S 1 electronic levels (ΔE S 2 S 1 ) of the two main types of impurity centers formed by molecules of a given porphyrin in the crystal matrix are found to significantly differ from each other, the values of this difference (δΔE S 2 S 1 ) being considerably greater for tetramethyldibenzoporphin, δΔE S 2 S 1 =228cm -1 , than for the two other porphyrins. At the same time, the energies of the unperturbed vibrational states of the S 1 electronic level participating in the resonance are very close to each other for these two sites

Citalopram inhibits L-type calcium channel current in rat cardiomyocytes in culture

Czech Academy of Sciences Publication Activity Database

Hamplová-Peichlová, J.; Krůšek, Jan; Paclt, I.; Slavíček, J.; Lisá, Věra; Vyskočil, František

2002-01-01

Roč. 51, č. 3 (2002), s. 317-321 ISSN 0862-8408 R&D Projects: GA AV ČR IAA7011902; GA ČR GA305/02/1333 Institutional research plan: CEZ:AV0Z5011922 Keywords : citalopram * amitriptyline * L-type calcium channel current Subject RIV: ED - Physiology Impact factor: 0.984, year: 2002

Children's (Pediatric) Magnetic Resonance Imaging

Medline Plus

Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician Resources Professions Site Index A-Z Children’s (Pediatric) Magnetic Resonance ...

The effects of 3:1 resonances in stellar pulsations

International Nuclear Information System (INIS)

Moskalik, P.; Buchler, J.R.

1989-01-01

The effects of a 3:1 resonance are studied and compared to those of a 2:1 resonance. When the growth rate of the higher frequency mode is negative it is shown that a 3:1 resonance affects the pulsation in a very similar fashion to a 2:1 resonance. In fact, it may be very difficult to discriminate in observational data between these two types of coupling. On the other hand, when the higher frequency mode is linearly unstable a 3:1 resonance, contrary to a 2:1 case, is unable to saturate the instability in the absence of nonresonant coupling terms. Astrophysical applications are discussed. 19 refs

Wideband MEMS Resonator Using Multifrequency Excitation

KAUST Repository

Jaber, Nizar; Ramini, Abdallah; Al Hennawi, Qais M.; Younis, Mohammad I.

2016-01-01

We demonstrate the excitation of combination resonances of additive and subtractive types and their exploitations to realize a large bandwidth micro-machined resonator of large amplitude even at higher harmonic modes of vibrations. The investigation is conducted on a Microelectromechanical systems (MEMS) clamped-clamped microbeam fabricated using polyimide as a structural layer coated with nickel from top and chromium and gold layers from bottom. The microbeam is excited by a two-source harmonic excitation, where the first frequency source is swept around the targeted resonance (first or third mode of vibration) while the second source frequency is kept fixed. We report for the first time a large bandwidth and large amplitude response near the higher order modes of vibration. Also, we show that by properly tuning the frequency and amplitude of the excitation force, the frequency bandwidth of the resonator is controlled.

Wideband MEMS Resonator Using Multifrequency Excitation

KAUST Repository

Jaber, Nizar

2016-03-09

We demonstrate the excitation of combination resonances of additive and subtractive types and their exploitations to realize a large bandwidth micro-machined resonator of large amplitude even at higher harmonic modes of vibrations. The investigation is conducted on a Microelectromechanical systems (MEMS) clamped-clamped microbeam fabricated using polyimide as a structural layer coated with nickel from top and chromium and gold layers from bottom. The microbeam is excited by a two-source harmonic excitation, where the first frequency source is swept around the targeted resonance (first or third mode of vibration) while the second source frequency is kept fixed. We report for the first time a large bandwidth and large amplitude response near the higher order modes of vibration. Also, we show that by properly tuning the frequency and amplitude of the excitation force, the frequency bandwidth of the resonator is controlled.

Quantum resonances in a single plaquette of Josephson junctions: excitations of Rabi oscillations

OpenAIRE

Fistul, M. V.

2001-01-01

We present a theoretical study of a quantum regime of the resistive (whirling) state of dc driven anisotropic single plaquette containing three small Josephson junctions. The current-voltage characteristics of such a system display resonant steps that are due to the resonant interaction between the time dependent Josephson current and the excited electromagnetic oscillations (EOs). The voltage positions of the resonances are determined by the quantum interband transitions of EOs. We show that...

Special resonances in two- and three-cluster systems

International Nuclear Information System (INIS)

Orlowski, M.

1979-01-01

In the framework of Schmid's N-cluster theory the resonance theory of Wildermuth-Benoehr is extended to three clusters. This three-cluster resonance model is solved in a mathematically exact formalism. The main topic of this formalism is the asymptotic behaviour of the full three-body-resolvent in the differential directions of the six-dimensional position space of the Jacobi coordinates. The scattering amplitudes and cross sections in all two-body channels and breakup are explicitly presented. Furthermore a very illustrative kinematical three-body model, the so called 'three-body-neb', is developed. Special regards in this connection are devoted to the analysis of possible interference possibilities of the main three-body-resonance with other resonance types of the three-body model. In a further section the Pauli-resonances are studied i) in the Wildermuth resonating group theory, ii) in Schmid's simulation models. It is shown under which circumstances Pauli-resonances may be positive energy bound states. (orig./HSI) [de

Fault Ride-through Capability Enhancement of Voltage Source Converter-High Voltage Direct Current Systems with Bridge Type Fault Current Limiters

Directory of Open Access Journals (Sweden)

Md Shafiul Alam

2017-11-01

Full Text Available This paper proposes the use of bridge type fault current limiters (BFCLs as a potential solution to reduce the impact of fault disturbance on voltage source converter-based high voltage DC (VSC-HVDC systems. Since VSC-HVDC systems are vulnerable to faults, it is essential to enhance the fault ride-through (FRT capability with auxiliary control devices like BFCLs. BFCL controllers have been developed to limit the fault current during the inception of system disturbances. Real and reactive power controllers for the VSC-HVDC have been developed based on current control mode. DC link voltage control has been achieved by a feedback mechanism such that net power exchange with DC link capacitor is zero. A grid-connected VSC-HVDC system and a wind farm integrated VSC-HVDC system along with the proposed BFCL and associated controllers have been implemented in a real time digital simulator (RTDS. Symmetrical three phase as well as different types of unsymmetrical faults have been applied in the systems in order to show the effectiveness of the proposed BFCL solution. DC link voltage fluctuation, machine speed and active power oscillation have been greatly suppressed with the proposed BFCL. Another significant feature of this work is that the performance of the proposed BFCL in VSC-HVDC systems is compared to that of series dynamic braking resistor (SDBR. Comparative results show that the proposed BFCL is superior over SDBR in limiting fault current as well as improving system fault ride through (FRT capability.

Open Resonator for Summation of Powers in Sub-Terahertz and Terahertz Frequencies

Science.gov (United States)

Kuz'michev, I. K.; Yeryomka, V. D.; May, A. V.; Troshchilo, A. S.

2017-03-01

Purpose: Study of excitation features for the first higher axialasymmetric type oscillations in an open resonator connected into the waveguide transmission line. Design/methodology/approach: To determine the efficiency of higher oscillation excitation in the resonator by using the highest wave of a rectangular waveguide, the coefficient of the antenna surface utilization is used. The coefficient of reflection from the open resonator is determined by the known method of summation of the partial coefficients of reflection from the resonant system. Findings: The excitation efficiency of the first higher axial asymmetric type TEM10q oscillations in an open resonator connected into the waveguide transmission line, using the TE20 type wave, is considered. The research efforts were made with accounting for the electromagnetic field vector nature. It is shown that for certain sizes of exciting coupler the excitation efficiency of the working excitation is equal to 0.867. Besides, this resonant system has a single frequency response within a wide band of frequencies. Due to this, it can be applied for summation of powers for individual sources of oscillations. Since this resonant system allows separating the matching functions as to the field and coupling, it is possible to provide any prescribed coupling of sources with a resonant volume. For this purpose, one- dimensional diffraction gratings (E-polarization) are used. Conclusions: With the matched excitation of axially asymmetric modes of oscillations the resonant system has an angular and frequency spectrum selection that is of great practical importance for powers summation. By application of one- dimensional diffraction gratings (E-polarization), located in apertures of coupling elements, the active elements can be matched with the resonant volume.

Current limiting characteristics of transformer type SFCL with coupled secondary windings according to its winding direction

Energy Technology Data Exchange (ETDEWEB)

Lim, Sung Hun [Dept. of Electrical Engineering, Soongsil University, Seoul (Korea, Republic of); Han, Tae Hee [Dept. of Aero Materials Engineering, Jungwon University, Goesan (Korea, Republic of)

2017-06-15

In this paper, the current limiting characteristics of the transformer type superconducting fault current limiter (SFCL) with the two coupled secondary windings due to its winding direction were analyzed. To analyze the dependence of transient fault current limiting characteristics on the winding direction of the additional secondary winding, the fault current limiting tests of the SFCL with an additional secondary winding, wound as subtractive polarity winding and additive polarity winding, were carried out. The time interval of quench occurrence between two superconducting elements comprising the transformer type SFCL with the additional secondary winding was confirmed to be affected by the winding direction of the additional secondary winding. In case of the subtractive polarity winding of the additional secondary winding, the time interval of the quench occurrence in two superconducting elements was shorter than the case of the additive polarity winding.

Current limiting characteristics of transformer type SFCL with coupled secondary windings according to its winding direction

International Nuclear Information System (INIS)

Lim, Sung Hun; Han, Tae Hee

2017-01-01

In this paper, the current limiting characteristics of the transformer type superconducting fault current limiter (SFCL) with the two coupled secondary windings due to its winding direction were analyzed. To analyze the dependence of transient fault current limiting characteristics on the winding direction of the additional secondary winding, the fault current limiting tests of the SFCL with an additional secondary winding, wound as subtractive polarity winding and additive polarity winding, were carried out. The time interval of quench occurrence between two superconducting elements comprising the transformer type SFCL with the additional secondary winding was confirmed to be affected by the winding direction of the additional secondary winding. In case of the subtractive polarity winding of the additional secondary winding, the time interval of the quench occurrence in two superconducting elements was shorter than the case of the additive polarity winding

A novel method of flat YBCO rings development for shield-type superconducting fault current limiters fabrication

International Nuclear Information System (INIS)

Hekmati, Arsalan; Hosseini, Mehdi; Vakilian, Mehdi; Fardmanesh, Mehdi

2012-01-01

A method has been proposed for flat YBCO ring Fabrication. A prototype SFCL with proposed design has been fabricated using the rings. J c characteristics of the rings are measured using an innovative method. The application of flat superconductor rings has been investigated in the structure of inductive shield-type high temperature superconducting fault current limiters, HT c -SFCL. A laboratory scale inductive shield-type HT c -SFCL has been designed and fabricated using flat superconductor rings. The fabrication process has been fully presented. YBCO powder has been used for the fabrication of superconductor rings. This fabrication process, being quite innovative, is introduced completely. The method of the trapped field measurement has been used for the critical current density measurement of the fabricated superconductor rings. The device with nominal current of 2 A was tested in a 30 V circuit. The SFCL successfully limited the fault currents of up to 10 times the nominal current to an approximately fixed value of 3 A. The voltage-current characteristic of the fabricated prototype has also been obtained and has shown compatibility with the fault current limitation results.

Overview of current multiparametric magnetic resonance imaging approach in the diagnosis and staging of prostate cancer

Directory of Open Access Journals (Sweden)

Hasan Aydın

2015-04-01

Full Text Available This article is primarily based on the utility and validity of multiparametric magnetic resonance imaging in the diagnosis and staging of prostate gland tumors. Multiparametric magnetic resonance imaging is an emerging, useful approach for evaluating and detecting prostate cancers. It also aids in the management of a tumor and improve the care and follow-up of patients.

An application of coherence resonances in molecular transition identification

International Nuclear Information System (INIS)

Alekseev, V.A.; Salomaa, R.

1978-01-01

In Λ-type three level configurations having long lived lower levels extremely sharp two photon resonances occur. We want to draw attention to the use of these resonances for distinguishing the hyperfine splitting of lower and upper set of levels of molecular transitions. A new feature in the theoretical model is that the saturator and probe beams are coupled to both transitions rendering possible the appearance of interference between the resonances. (author)

Coherent and incoherent processes in resonant photoemission

Energy Technology Data Exchange (ETDEWEB)

Magnuson, M.; Karis, O.; Weinelt, M. [Uppsala Univ. (Sweden)] [and others

1997-04-01

In this contribution the authors present the distinction between coherent and incoherent processes in resonant photoemission. As a first step they determine whether an autoionization process is photoemission-like or Auger-like. The discussion is based on measurements for a weakly bonded adsorption system, Ar/Pt(111). This type of system is well adapted to investigate these effects since it yields distinctly shifted spectral features depending on the nature of the process. After this, the question of resonance photoemission in metallic systems is addressed. This is done in connection with measurements at the 2p edges for Ni metal. Ni has been one of the prototype systems for resonant photoemission. The resonances have been discussed in connection with the strong correlation and d-band localization effects in this system. Based on the results some general comments about the appearance of resonant effects in metallic systems are made.

Shot noise of spin current and spin transfer torque

International Nuclear Information System (INIS)

Yu Yunjin; Zhan Hongxin; Wan Langhui; Wang Bin; Wei Yadong; Sun Qingfeng; Wang Jian

2013-01-01

We report the theoretical investigation of the shot noise of the spin current (S σ ) and the spin transfer torque (S τ ) for non-collinear spin polarized transport in a spin-valve device which consists of a normal scattering region connected by two ferromagnetic electrodes (MNM system). Our theory was developed using the non-equilibrium Green’s function method, and general nonlinear S σ − V and S τ − V relations were derived as a function of the angle θ between the magnetizations of two leads. We have applied our theory to a quantum dot system with a resonant level coupled with two ferromagnetic electrodes. It was found that, for the MNM system, the auto-correlation of the spin current is enough to characterize the fluctuation of the spin current. For a system with three ferromagnetic layers, however, both auto-correlation and cross-correlation of the spin current are needed to characterize the noise of the spin current. For a quantum dot with a resonant level, the derivative of spin torque with respect to bias voltage is proportional to sinθ when the system is far away from resonance. When the system is near resonance, the spin transfer torque becomes a non-sinusoidal function of θ. The derivative of the noise of the spin transfer torque with respect to the bias voltage N τ behaves differently when the system is near or far away from resonance. Specifically, the differential shot noise of the spin transfer torque N τ is a concave function of θ near resonance while it becomes a convex function of θ far away from resonance. For certain bias voltages, the period N τ (θ) becomes π instead of 2π. For small θ, it was found that the differential shot noise of the spin transfer torque is very sensitive to the bias voltage and the other system parameters. (paper)

Electrothermally Tunable Bridge Resonator

KAUST Repository

Hajjaj, Amal Z.; Alcheikh, Nouha; Ramini, Abdallah; Hafiz, Md Abdullah Al; Younis, Mohammad I.

2016-01-01

This paper demonstrates experimentally, theoretically, and numerically a wide-range tunability of an in-plane clamped-clamped microbeam, bridge, and resonator compressed by a force due to electrothermal actuation. We demonstrate that a single resonator can be operated at a wide range of frequencies. The microbeam is actuated electrothermally, by passing a DC current through it. We show that when increasing the electrothermal voltage, the compressive stress inside the microbeam increases, which leads eventually to its buckling. Before buckling, the fundamental frequency decreases until it drops to very low values, almost to zero. After buckling, the fundamental frequency increases, which is shown to be as high as twice the original resonance frequency. Analytical results based on the Galerkin discretization of the Euler Bernoulli beam theory are generated and compared to the experimental data and to simulation results of a multi-physics finite-element model. A good agreement is found among all the results.

Electrothermally Tunable Bridge Resonator

KAUST Repository

Hajjaj, Amal Z.

2016-12-05

This paper demonstrates experimentally, theoretically, and numerically a wide-range tunability of an in-plane clamped-clamped microbeam, bridge, and resonator compressed by a force due to electrothermal actuation. We demonstrate that a single resonator can be operated at a wide range of frequencies. The microbeam is actuated electrothermally, by passing a DC current through it. We show that when increasing the electrothermal voltage, the compressive stress inside the microbeam increases, which leads eventually to its buckling. Before buckling, the fundamental frequency decreases until it drops to very low values, almost to zero. After buckling, the fundamental frequency increases, which is shown to be as high as twice the original resonance frequency. Analytical results based on the Galerkin discretization of the Euler Bernoulli beam theory are generated and compared to the experimental data and to simulation results of a multi-physics finite-element model. A good agreement is found among all the results.

Series resonant converter with auxiliary winding turns: analysis, design and implementation

Science.gov (United States)

Lin, Bor-Ren

2018-05-01

Conventional series resonant converters have researched and applied for high-efficiency power units due to the benefit of its low switching losses. The main problems of series resonant converters are wide frequency variation and high circulating current. Thus, resonant converter is limited at narrow input voltage range and large input capacitor is normally adopted in commercial power units to provide the minimum hold-up time requirement when AC power is off. To overcome these problems, the resonant converter with auxiliary secondary windings are presented in this paper to achieve high voltage gain at low input voltage case such as hold-up time duration when utility power is off. Since the high voltage gain is used at low input voltage cased, the frequency variation of the proposed converter compared to the conventional resonant converter is reduced. Compared to conventional resonant converter, the hold-up time in the proposed converter is more than 40ms. The larger magnetising inductance of transformer is used to reduce the circulating current losses. Finally, a laboratory prototype is constructed and experiments are provided to verify the converter performance.

Analysis of JET LCHD/ICRH synergy experiments in terms of relativistic current drive theory

Energy Technology Data Exchange (ETDEWEB)

Start, D F.H.; Baranov, Y; Brusati, M; Ekedahl, A; Froissard, P; Gormezano, C; Jacquinot, J; Paquin, L; Rimini, F G [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Cox, M; Gardner, C; O` Brien, M R [UKAEA Culham Lab., Abingdon (United Kingdom); Di Vita, A [Ansaldo SpA, Genoa (Italy)

1994-07-01

The present analysis shows that the observed efficiency of current drive with synergy between LHCD and ICRH is in good agreement with the relativistic theory of Karney and Fisch for Landau damped waves. The predicted power absorption from the fast wave by the electron tail is within 30% of the measured value. In the presence of significant fast electron diffusion within a slowing down time it would be possible to produce central current drive using multiple ICRF resonances even when the LHCD deposition is at half radius, as in an ITER type device. (authors). 4 refs., 6 figs.

Analysis of JET LCHD/ICRH synergy experiments in terms of relativistic current drive theory

International Nuclear Information System (INIS)

Start, D.F.H.; Baranov, Y.; Brusati, M.; Ekedahl, A.; Froissard, P.; Gormezano, C.; Jacquinot, J.; Paquin, L.; Rimini, F.G.; Di Vita, A.

1994-01-01

The present analysis shows that the observed efficiency of current drive with synergy between LHCD and ICRH is in good agreement with the relativistic theory of Karney and Fisch for Landau damped waves. The predicted power absorption from the fast wave by the electron tail is within 30% of the measured value. In the presence of significant fast electron diffusion within a slowing down time it would be possible to produce central current drive using multiple ICRF resonances even when the LHCD deposition is at half radius, as in an ITER type device. (authors). 4 refs., 6 figs

Can magnetic resonance imaging differentiate undifferentiated arthritis?

DEFF Research Database (Denmark)

Østergaard, Mikkel; Duer, Anne; Hørslev-Petersen, K

2005-01-01

A high sensitivity for the detection of inflammatory and destructive changes in inflammatory joint diseases makes magnetic resonance imaging potentially useful for assigning specific diagnoses, such as rheumatoid arthritis and psoriatic arthritis in arthritides, that remain undifferentiated after...... conventional clinical, biochemical and radiographic examinations. With recent data as the starting point, the present paper describes the current knowledge on magnetic resonance imaging in the differential diagnosis of undifferentiated arthritis....

Dopamine Neurons Change the Type of Excitability in Response to Stimuli

Science.gov (United States)

Gutkin, Boris S.; Lapish, Christopher C.; Kuznetsov, Alexey

2016-01-01

The dynamics of neuronal excitability determine the neuron’s response to stimuli, its synchronization and resonance properties and, ultimately, the computations it performs in the brain. We investigated the dynamical mechanisms underlying the excitability type of dopamine (DA) neurons, using a conductance-based biophysical model, and its regulation by intrinsic and synaptic currents. Calibrating the model to reproduce low frequency tonic firing results in N-methyl-D-aspartate (NMDA) excitation balanced by γ-Aminobutyric acid (GABA)-mediated inhibition and leads to type I excitable behavior characterized by a continuous decrease in firing frequency in response to hyperpolarizing currents. Furthermore, we analyzed how excitability type of the DA neuron model is influenced by changes in the intrinsic current composition. A subthreshold sodium current is necessary for a continuous frequency decrease during application of a negative current, and the low-frequency “balanced” state during simultaneous activation of NMDA and GABA receptors. Blocking this current switches the neuron to type II characterized by the abrupt onset of repetitive firing. Enhancing the anomalous rectifier Ih current also switches the excitability to type II. Key characteristics of synaptic conductances that may be observed in vivo also change the type of excitability: a depolarized γ-Aminobutyric acid receptor (GABAR) reversal potential or co-activation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) leads to an abrupt frequency drop to zero, which is typical for type II excitability. Coactivation of N-methyl-D-aspartate receptors (NMDARs) together with AMPARs and GABARs shifts the type I/II boundary toward more hyperpolarized GABAR reversal potentials. To better understand how altering each of the aforementioned currents leads to changes in excitability profile of DA neuron, we provide a thorough dynamical analysis. Collectively, these results imply that type I

Circular polarization in a non-magnetic resonant tunneling device

Directory of Open Access Journals (Sweden)

Airey Robert

2011-01-01

Full Text Available Abstract We have investigated the polarization-resolved photoluminescence (PL in an asymmetric n-type GaAs/AlAs/GaAlAs resonant tunneling diode under magnetic field parallel to the tunnel current. The quantum well (QW PL presents strong circular polarization (values up to -70% at 19 T. The optical emission from GaAs contact layers shows evidence of highly spin-polarized two-dimensional electron and hole gases which affects the spin polarization of carriers in the QW. However, the circular polarization degree in the QW also depends on various other parameters, including the g-factors of the different layers, the density of carriers along the structure, and the Zeeman and Rashba effects.

Resonance – Journal of Science Education | News

Indian Academy of Sciences (India)

Keywords. Scalars; four-vectors; lorentz transformation; special relativity. ... Resonance – Journal of Science Education. Current Issue : Vol. 23, Issue 4. Current Issue Volume 23 | Issue 4. April 2018. Home · Volumes & Issues · Categories · Special Issues · Search · Editorial Board · Information for Authors · Subscription ...

Electrostatically actuated torsional resonant sensors and switches

KAUST Repository

Younis, Mohammad I.

2016-12-29

Embodiments in accordance of a torsional resonant sensor disclosure is configured to actuate a beam structure using electrostatic actuation with an AC harmonic load (e.g., AC and DC voltage sources) that is activated upon detecting a particular agent having a mass above a predefined level. In various embodiments, the beam structure may be different types of resonant structures that is at least partially coated or layered with a selective material.

Resonator coupled Josephson junctions; parametric excitations and mutual locking

DEFF Research Database (Denmark)

Jensen, H. Dalsgaard; Larsen, A.; Mygind, Jesper

1991-01-01

Self-pumped parametric excitations and mutual locking in systems of Josephson tunnel junctions coupled to multimode resonators are reported. For the very large values of the coupling parameter, obtained with small Nb-Al2O3-Nb junctions integrated in superconducting microstrip resonators, the DC I......-V characteristic shows an equidistant series of current steps generated by subharmonic pumping of the fundamental resonator mode. This is confirmed by measurement of frequency and linewidth of the emitted Josephson radiation...

Power flow analysis and optimal locations of resistive type superconducting fault current limiters.

Science.gov (United States)

Zhang, Xiuchang; Ruiz, Harold S; Geng, Jianzhao; Shen, Boyang; Fu, Lin; Zhang, Heng; Coombs, Tim A

2016-01-01

Based on conventional approaches for the integration of resistive-type superconducting fault current limiters (SFCLs) on electric distribution networks, SFCL models largely rely on the insertion of a step or exponential resistance that is determined by a predefined quenching time. In this paper, we expand the scope of the aforementioned models by considering the actual behaviour of an SFCL in terms of the temperature dynamic power-law dependence between the electrical field and the current density, characteristic of high temperature superconductors. Our results are compared to the step-resistance models for the sake of discussion and clarity of the conclusions. Both SFCL models were integrated into a power system model built based on the UK power standard, to study the impact of these protection strategies on the performance of the overall electricity network. As a representative renewable energy source, a 90 MVA wind farm was considered for the simulations. Three fault conditions were simulated, and the figures for the fault current reduction predicted by both fault current limiting models have been compared in terms of multiple current measuring points and allocation strategies. Consequently, we have shown that the incorporation of the E - J characteristics and thermal properties of the superconductor at the simulation level of electric power systems, is crucial for estimations of reliability and determining the optimal locations of resistive type SFCLs in distributed power networks. Our results may help decision making by distribution network operators regarding investment and promotion of SFCL technologies, as it is possible to determine the maximum number of SFCLs necessary to protect against different fault conditions at multiple locations.

Internal resonances in periodically modulated long Josephson junctions

DEFF Research Database (Denmark)

Larsen, Britt Hvolbæk; Mygind, Jesper; Ustinov, Alexey V.

1995-01-01

Current-voltage (I-V) characteristics of long Josephson junctions with a periodic lattice of localized inhomogeneities are studied. The interaction between the moving fluxons and the inhomogeneities causes resonant steps in the IV-curve. Some of these steps are due to a synchronization to resonant...... Fiske modes in the sub-junctions formed between the inhomogeneities. The voltage positions of the resonant steps oscillate as function of the applied magnetic field with a period corresponding to the inclusion of one magnetic flux quantum, Φ0=h/2e, per sub-junction. A qualitative explanation that takes...

Characterization of complementary electric field coupled resonant surfaces

Science.gov (United States)

Hand, Thomas H.; Gollub, Jonah; Sajuyigbe, Soji; Smith, David R.; Cummer, Steven A.

2008-11-01

We present angle-resolved free-space transmission and reflection measurements of a surface composed of complementary electric inductive-capacitive (CELC) resonators. By measuring the reflection and transmission coefficients of a CELC surface with different polarizations and particle orientations, we show that the CELC only responds to in-plane magnetic fields. This confirms the Babinet particle duality between the CELC and its complement, the electric field coupled LC resonator. Characterization of the CELC structure serves to expand the current library of resonant elements metamaterial designers can draw upon to make unique materials and surfaces.

Application of Resonant Converter in Ozone Generator Model

Directory of Open Access Journals (Sweden)

Mochammad Facta

2008-04-01

Full Text Available Ozone is one of the favorable oxidant to use in home appliance and industry as disinfectant for food processing, food storage, odor abatement, groundwater remediation, and drinking water purification. The common and previous technical method for generating ozone uses a high voltage and low frequency. This kind of method has disadvantage of energy efficiency, size and weight. This paper proposed the use power electronics in the inverter resonant circuit to produce alternating current with high frequency. The basic RLC resonance circuit is used for early study to determine resonance frequency for inverter. As the result, the ozone chamber terminal voltage had been achieved for initiation by using resonance frequency.

Application of MO-type gapless flange to beam duct for high-current accelerators

International Nuclear Information System (INIS)

Suetsugu, Y.; Shirai, M.; Ohtsuka, M.

2004-01-01

The MO-type flange, which can provide a gapless connection between flanges, was studied experimentally aiming to apply it to the beam duct for high-current accelerators. The test flange showed a good vacuum sealing property, although the aperture had a complicated shape, that is, the combination of a circular beam duct and a rectangular antechamber. The structural analysis well reproduced the observed deformation of flange, and utilized to optimize the structure. The MO-type flange is a promising one for the connection flange of the beam duct for future accelerators. (author)

Lithographed Superconducting Resonator Development for Next-Generation Frequency Multiplexing Readout of Transition-Edge Sensors

Science.gov (United States)

Faramarzi, F.; De Haan, T.; Kusaka, A.; Lee, A.; Neuhauser, B.; Plambeck, R.; Raum, C.; Suzuki, A.; Westbrook, B.

2018-03-01

Ground-based cosmic microwave background (CMB) experiments are undergoing a period of exponential growth. Current experiments are observing with 1000-10,000 detectors, and the next-generation experiment (CMB stage 4) is proposing to deploy approximately 500,000 detectors. This order of magnitude increase in detector count will require a new approach for readout electronics. We have developed superconducting resonators for next-generation frequency-domain multiplexing (fMUX) readout architecture. Our goal is to reduce the physical size of resonators, such that resonators and detectors can eventually be integrated on a single wafer. To reduce the size of these resonators, we have designed spiral inductors and interdigitated capacitors that resonate around 10-100 MHz, an order of magnitude higher frequency compared to current fMUX readout systems. The higher frequency leads to a wider bandwidth and would enable higher multiplexing factor than the current ˜ 50 detectors per readout channel. We will report on the simulation, fabrication method, characterization technique, and measurement of quality factor of these resonators.

Self-consistent modelling of resonant tunnelling structures

DEFF Research Database (Denmark)

Fiig, T.; Jauho, A.P.

1992-01-01

We report a comprehensive study of the effects of self-consistency on the I-V-characteristics of resonant tunnelling structures. The calculational method is based on a simultaneous solution of the effective-mass Schrödinger equation and the Poisson equation, and the current is evaluated...... applied voltages and carrier densities at the emitter-barrier interface. We include the two-dimensional accumulation layer charge and the quantum well charge in our self-consistent scheme. We discuss the evaluation of the current contribution originating from the two-dimensional accumulation layer charges......, and our qualitative estimates seem consistent with recent experimental studies. The intrinsic bistability of resonant tunnelling diodes is analyzed within several different approximation schemes....

Magnetic Resonance Imaging (MRI) -- Head

Medline Plus

Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician ... Magnetic resonance imaging (MRI) is a noninvasive medical test that physicians use to diagnose medical conditions. MRI ...

Children's (Pediatric) Magnetic Resonance Imaging

Medline Plus

Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician ... Magnetic resonance imaging (MRI) is a noninvasive medical test that physicians use to diagnose medical conditions. MRI ...

Power requirements for electron cyclotron current drive and ion cyclotron resonance heating for sawtooth control in ITER

Science.gov (United States)

Chapman, I. T.; Graves, J. P.; Sauter, O.; Zucca, C.; Asunta, O.; Buttery, R. J.; Coda, S.; Goodman, T.; Igochine, V.; Johnson, T.; Jucker, M.; La Haye, R. J.; Lennholm, M.; Contributors, JET-EFDA

2013-06-01

13 MW of electron cyclotron current drive (ECCD) power deposited inside the q = 1 surface is likely to reduce the sawtooth period in ITER baseline scenario below the level empirically predicted to trigger neoclassical tearing modes (NTMs). However, since the ECCD control scheme is solely predicated upon changing the local magnetic shear, it is prudent to plan to use a complementary scheme which directly decreases the potential energy of the kink mode in order to reduce the sawtooth period. In the event that the natural sawtooth period is longer than expected, due to enhanced α particle stabilization for instance, this ancillary sawtooth control can be provided from >10MW of ion cyclotron resonance heating (ICRH) power with a resonance just inside the q = 1 surface. Both ECCD and ICRH control schemes would benefit greatly from active feedback of the deposition with respect to the rational surface. If the q = 1 surface can be maintained closer to the magnetic axis, the efficacy of ECCD and ICRH schemes significantly increases, the negative effect on the fusion gain is reduced, and off-axis negative-ion neutral beam injection (NNBI) can also be considered for sawtooth control. Consequently, schemes to reduce the q = 1 radius are highly desirable, such as early heating to delay the current penetration and, of course, active sawtooth destabilization to mediate small frequent sawteeth and retain a small q = 1 radius. Finally, there remains a residual risk that the ECCD + ICRH control actuators cannot keep the sawtooth period below the threshold for triggering NTMs (since this is derived only from empirical scaling and the control modelling has numerous caveats). If this is the case, a secondary control scheme of sawtooth stabilization via ECCD + ICRH + NNBI, interspersed with deliberate triggering of a crash through auxiliary power reduction and simultaneous pre-emptive NTM control by off-axis ECCD has been considered, permitting long transient periods with high fusion

Nonlinear phenomena at cyclotron resonance

International Nuclear Information System (INIS)

Subbarao, D.; Uma, R.

1986-01-01

Finite amplitude electromagnetic waves in a magnetoplasma which typically occur in situations as in present day wave heating, current drives and other schemes in magnetically confined fusion systems, can show qualitatively different absorption and emission characteristics around resonant frequencies of the plasma because of anharmonicity. Linear wave plasma coupling as well as weak nonlinear effects such as parametric instabilities generally overlook this important effect even though the thresholds for the two phenomena as shown here are comparable. Though the effects described here are relevant to a host of nonlinear resonance effects in fusion plasmas, the authors mainly limit themselves to ECRH

Computer aided design of Langasite resonant cantilevers: analytical models and simulations

Science.gov (United States)

Tellier, C. R.; Leblois, T. G.; Durand, S.

2010-05-01

Analytical models for the piezoelectric excitation and for the wet micromachining of resonant cantilevers are proposed. Firstly, computations of metrological performances of micro-resonators allow us to select special cuts and special alignment of the cantilevers. Secondly the self-elaborated simulator TENSOSIM based on the kinematic and tensorial model furnishes etching shapes of cantilevers. As the result the number of selected cuts is reduced. Finally the simulator COMSOL® is used to evaluate the influence of final etching shape on metrological performances and especially on the resonance frequency. Changes in frequency are evaluated and deviating behaviours of structures with less favourable built-ins are tested showing that the X cut is the best cut for LGS resonant cantilevers vibrating in flexural modes (type 1 and type 2) or in torsion mode.

Nanoscale constrictions in superconducting coplanar waveguide resonators

Energy Technology Data Exchange (ETDEWEB)

Jenkins, Mark David; Naether, Uta; Ciria, Miguel; Zueco, David; Luis, Fernando, E-mail: fluis@unizar.es [Instituto de Ciencia de Materiales de Aragón, CSIC—Universidad de Zaragoza, 50009 Zaragoza (Spain); Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza (Spain); Sesé, Javier [Instituto de Nanociencia de Aragón, Universidad de Zaragoza, E-50009 Zaragoza (Spain); Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza (Spain); Atkinson, James; Barco, Enrique del [Department of Physics, University of Central Florida, Orlando, Florida 32816 (United States); Sánchez-Azqueta, Carlos [Dpto. de Ingeniería Electrónica y Telecomunicaciones, Universidad de Zaragoza, 50009 Zaragoza (Spain); Majer, Johannes [Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, 1020 Vienna (Austria)

2014-10-20

We report on the design, fabrication, and characterization of superconducting coplanar waveguide resonators with nanoscopic constrictions. By reducing the size of the center line down to 50 nm, the radio frequency currents are concentrated and the magnetic field in its vicinity is increased. The device characteristics are only slightly modified by the constrictions, with changes in resonance frequency lower than 1% and internal quality factors of the same order of magnitude as the original ones. These devices could enable the achievement of higher couplings to small magnetic samples or even to single molecular spins and have applications in circuit quantum electrodynamics, quantum computing, and electron paramagnetic resonance.

Electron paramagnetic resonance study on n-type electron-irradiated 3C-SiC

Energy Technology Data Exchange (ETDEWEB)

Carlsson, P; Rabia, K; Son, N T; Janzen, E [Department of Physics, Chemistry and Biology, Linkoeping University, SE-581 83 Linkoeping (Sweden); Ohshima, T; Morishita, N; Itoh, H [Japan Atomic Energy Research Institute, Takasaki 370-1292 (Japan); Isoya, J [University of Tsukuba, Tsukuba 305-8550 (Japan)], E-mail: paca@ifm.liu.se

2008-03-15

Electron Paramagnetic Resonance (EPR) was used to study defects in n-type 3C-SiC films irradiated by 3-MeV electrons at room temperature with a dose of 2x10{sup 18} cm{sup -2}. After electron irradiation, two new EPR spectra with an effective spin S = 1, labeled L5 and L6, were observed. The L5 center has C{sub 3v} symmetry with g = 2.004 and a fine-structure parameter D = 436.5x10{sup -4} cm{sup -1}. The L5 spectrum was only detected under light illumination and it could not be detected after annealing at {approx}550{sup 0}C. The principal z-axis of the D tensor is parallel to the <111>-directions, indicating the location of spins along the Si-C bonds. Judging from the symmetry and the fact that the signal was detected under illumination in n-type material, the L5 center may be related to the divacancy in the neutral charge state. The L6 center has a C{sub 2v}-symmetry with an isotropic g-value of g = 2.003 and the fine structure parameters D = 547.7x10{sup -4} cm{sup -1} and E = 56.2x10{sup -4} cm{sup -1}. The L6 center disappeared after annealing at a rather low temperature ({approx}200 deg. C), which is substantially lower than the known annealing temperatures for vacancy-related defects in 3C-SiC. This highly mobile defect may be related to carbon interstitials.

Bradykinin induced a positive chronotropic effect via stimulation of T- and L-type calcium currents in heart cells.

Science.gov (United States)

El-Bizri, Nesrine; Bkaily, Ghassan; Wang, Shimin; Jacques, Danielle; Regoli, Domenico; D'Orléans-Juste, Pedro; Sukarieh, Rami

2003-03-01

Using Fluo-3 calcium dye confocal microscopy and spontaneously contracting embryonic chick heart cells, bradykinin (10(-10) M) was found to induce positive chronotropic effects by increasing the frequency of the transient increase of cytosolic and nuclear free Ca2+. Pretreatment of the cells with either B1 or B2 receptor antagonists (R126 and R817, respectively) completely prevented bradykinin (BK) induced positive chronotropic effects on spontaneously contracting single heart cells. Using the whole-cell voltage clamp technique and ionic substitution to separate the different ionic current species, our results showed that BK (10(-6) M) had no effect on fast Na+ inward current and delayed outward potassium current. However, both L- and T-type Ca2+ currents were found to be increased by BK in a dose-dependent manner (10(-10)-10(-7) M). The effects of BK on T- and L-type Ca2+ currents were partially blocked by the B1 receptor antagonist [Leu8]des-Arg9-BK (R592) (10(-7) M) and completely reversed by the B2 receptor antagonist D-Arg[Hyp3,D-Phe7,Leu8]BK (R-588) (10(-7) M) or pretreatment with pertussis toxin (PTX). These results demonstrate that BK induced a positive chronotropic effect via stimulation of T- and L-type Ca2+ currents in heart cells mainly via stimulation of B2 receptor coupled to PTX-sensitive G-proteins. The increase of both types of Ca2+ current by BK in heart cells may explain the positive inotropic and chronotropic effects of this hormone.

Fast response double series resonant high-voltage DC-DC converter

International Nuclear Information System (INIS)

Lee, S S; Iqbal, S; Kamarol, M

2012-01-01

In this paper, a novel double series resonant high-voltage dc-dc converter with dual-mode pulse frequency modulation (PFM) control scheme is proposed. The proposed topology consists of two series resonant tanks and hence two resonant currents flow in each switching period. Moreover, it consists of two high-voltage transformer with the leakage inductances are absorbed as resonant inductor in the series resonant tanks. The secondary output of both transformers are rectified and mixed before supplying to load. In the resonant mode operation, the series resonant tanks are energized alternately by controlling two Insulated Gate Bipolar Transistor (IGBT) switches with pulse frequency modulation (PFM). This topology operates in discontinuous conduction mode (DCM) with all IGBT switches operating in zero current switching (ZCS) condition and hence no switching loss occurs. To achieve fast rise in output voltage, a dual-mode PFM control during start-up of the converter is proposed. In this operation, the inverter is started at a high switching frequency and as the output voltage reaches 90% of the target value, the switching frequency is reduced to a value which corresponds to the target output voltage. This can effectively reduce the rise time of the output voltage and prevent overshoot. Experimental results collected from a 100-W laboratory prototype are presented to verify the effectiveness of the proposed system.

A comparison of lattice parameters for CANDU-type lattices obtained using MCNP, WIMS, and WIMS with resonance reaction rates from MCNP

International Nuclear Information System (INIS)

Craig, D.S.

1989-03-01

The Monte Carlo code MCNP was used to check the accuracy of the WIMS calculation of the resolved resonance capture rate in CANDU-type lattices. Reactivities, relative conversion ratios, and fast fission factors are compared with experiments. Values of ρ 28 and reaction rates for U-238 are given as a function of position in the fuel bundle. A check was made on the correction made in WIMS to allow for endcaps on the fuel bundles. (26 refs)

Optimal trajectory control of a series-resonant inverter with a non-linear resonant inductor

NARCIS (Netherlands)

Huisman, H.; Baskurt, F.; Bouloukos, A; Baars, N.H.; Lomonova, E.A.

2017-01-01

ies-Resonant (SR) converters have been used as building blocks for DC-AC and DC-DC power converters for at least half a century. Applications were first found in induction heating [1], where generating a substantial AC current at moderately high frequency was required by the application. Later, the

Quantum resonances in a single plaquette of Josephson junctions: excitations of Rabi oscillations

Science.gov (United States)

Fistul, M. V.

2002-03-01

We present a theoretical study of a quantum regime of the resistive (whirling) state of dc driven anisotropic single plaquette containing small Josephson junctions. The current-voltage characteristics of such systems display resonant steps that are due to the resonant interaction between the time dependent Josephson current and the excited electromagnetic oscillations (EOs). The voltage positions of the resonances are determined by the quantum interband transitions of EOs. We show that in the quantum regime as the system is driven on the resonance, coherent Rabi oscillations between the quantum levels of EOs occur. At variance with the classical regime the magnitude and the width of resonances are determined by the frequency of Rabi oscillations that in turn, depends in a peculiar manner on an externally applied magnetic field and the parameters of the system.

Pituitary adenylate cyclase activating polypeptide reduces A-type K+ currents and caspase activity in cultured adult mouse olfactory neurons.

Science.gov (United States)

Han, P; Lucero, M T

2005-01-01

Pituitary adenylate cyclase activating polypeptide has been shown to reduce apoptosis in neonatal cerebellar and olfactory receptor neurons, however the underlying mechanisms have not been elucidated. In addition, the neuroprotective effects of pituitary adenylate cyclase activating polypeptide have not been examined in adult tissues. To study the effects of pituitary adenylate cyclase activating polypeptide on neurons in apoptosis, we measured caspase activation in adult olfactory receptor neurons in vitro. Interestingly, we found that the protective effects of pituitary adenylate cyclase activating polypeptide were related to the absence of a 4-aminopyridine (IC50=144 microM) sensitive rapidly inactivating potassium current often referred to as A-type current. In the presence of 40 nM pituitary adenylate cyclase activating polypeptide 38, both A-type current and activated caspases were significantly reduced. A-type current reduction by pituitary adenylate cyclase activating polypeptide was blocked by inhibiting the phospholipase C pathway, but not the adenylyl cyclase pathway. Our observation that 5 mM 4-aminopyridine mimicked the caspase inhibiting effects of pituitary adenylate cyclase activating polypeptide indicates that A-type current is involved in apoptosis. This work contributes to our growing understanding that potassium currents are involved with the activation of caspases to affect the balance between cell life and death.

Frequency Preference Response to Oscillatory Inputs in Two-dimensional Neural Models: A Geometric Approach to Subthreshold Amplitude and Phase Resonance.

Science.gov (United States)

Rotstein, Horacio G

2014-01-01

We investigate the dynamic mechanisms of generation of subthreshold and phase resonance in two-dimensional linear and linearized biophysical (conductance-based) models, and we extend our analysis to account for the effect of simple, but not necessarily weak, types of nonlinearities. Subthreshold resonance refers to the ability of neurons to exhibit a peak in their voltage amplitude response to oscillatory input currents at a preferred non-zero (resonant) frequency. Phase-resonance refers to the ability of neurons to exhibit a zero-phase (or zero-phase-shift) response to oscillatory input currents at a non-zero (phase-resonant) frequency. We adapt the classical phase-plane analysis approach to account for the dynamic effects of oscillatory inputs and develop a tool, the envelope-plane diagrams, that captures the role that conductances and time scales play in amplifying the voltage response at the resonant frequency band as compared to smaller and larger frequencies. We use envelope-plane diagrams in our analysis. We explain why the resonance phenomena do not necessarily arise from the presence of imaginary eigenvalues at rest, but rather they emerge from the interplay of the intrinsic and input time scales. We further explain why an increase in the time-scale separation causes an amplification of the voltage response in addition to shifting the resonant and phase-resonant frequencies. This is of fundamental importance for neural models since neurons typically exhibit a strong separation of time scales. We extend this approach to explain the effects of nonlinearities on both resonance and phase-resonance. We demonstrate that nonlinearities in the voltage equation cause amplifications of the voltage response and shifts in the resonant and phase-resonant frequencies that are not predicted by the corresponding linearized model. The differences between the nonlinear response and the linear prediction increase with increasing levels of the time scale separation between

Cardiac effects of 3 months treatment of acromegaly evaluated by magnetic resonance imaging and B-type natriuretic peptides

DEFF Research Database (Denmark)

Andreassen, Mikkel; Faber, Jens; Kjær, Andreas

2010-01-01

Long-term treatment of acromegaly prevents aggravation and reverses associated heart disease. A previous study has shown a temporary increase in serum levels of the N-terminal fraction of pro B-type natriuretic peptide (NT-proBNP) suggesting an initial decline in cardiac function when treatment...... of acromegaly is initiated. This was a three months prospective study investigating short-term cardiac effects of treatment in acromegalic patients. Cardiac function was evaluated by the gold standard method cardiac magnetic resonance imaging (CMRI) and circulating levels of B-type natriuretic peptides (BNP......) (95% CI 3-14), P = 0.007) and an increase in levels of BNP (median (ranges) 7 (0.58-286) vs. 20 (1-489) pg/mL, P = 0.033) and of NT-proBNP (63 (20-1004) vs. 80 (20-3391) pg/mL, P = 0.027). Assessed by the highly sensitive and precise CMRI method, 3 months treatment of acromegaly resulted...

Compact type-I coil planet centrifuge for counter-current chromatography.

Science.gov (United States)

Yang, Yi; Gu, Dongyu; Liu, Yongqiang; Aisa, Haji Akber; Ito, Yoichiro

2010-02-19

A compact type-I coil planet centrifuge has been developed for performing counter-current chromatography. It has a revolution radius of 10 cm and a column holder height of 5 cm compared with 37 and 50 cm in the original prototype, respectively. The reduction in the revolution radius and column length permits application of higher revolution speed and more stable balancing of the rotor which leads us to learn more about its performance and the future potential of type-I coil planet centrifuge. The chromatographic performance of this apparatus was evaluated in terms of retention of the stationary phase (S(f)), peak resolution (R(s)), theoretical plate (N) and peak retention time (t(R)). The results of the experiment indicated that increasing the revolution speed slightly improved both the retention of the stationary phase and the peak resolution while the separation time is remarkably shortened to yield an excellent peak resolution at a revolution speed of 800 rpm. With a 12 ml capacity coiled column, DNP-DL-glu, DNP-beta-ala and DNP-l-ala were resolved at R(s) of 2.75 and 2.16 within 90 min at a flow rate of 0.4 ml/min. We believe that the compact type-I coil planet centrifuge has a high analytical potential. Published by Elsevier B.V.

Initial leakage current paths in the vertical-type GaN-on-GaN Schottky barrier diodes

Science.gov (United States)

Sang, Liwen; Ren, Bing; Sumiya, Masatomo; Liao, Meiyong; Koide, Yasuo; Tanaka, Atsushi; Cho, Yujin; Harada, Yoshitomo; Nabatame, Toshihide; Sekiguchi, Takashi; Usami, Shigeyoshi; Honda, Yoshio; Amano, Hiroshi

2017-09-01

Electrical characteristics of leakage current paths in vertical-type n-GaN Schottky barrier diodes (SBDs) on free-standing GaN substrates are investigated by using photon emission microscopy (PEM). The PEM mapping shows that the initial failure of the SBD devices at low voltages is due to the leakage current paths from polygonal pits in the GaN epilayers. It is observed that these polygonal pits originate from carbon impurity accumulation to the dislocations with a screw-type component by microstructure analysis. For the SBD without polygonal pits, no initial failure is observed and the first leakage appeals at the edge of electrodes as a result of electric field concentration. The mechanism of leakage at pits is explained in terms of trap assisted tunneling through fitting current-voltage characteristics.

Orbital Resonances in the Vinti Solution

Science.gov (United States)

Zurita, L. D.

As space becomes more congested, contested, and competitive, high-accuracy orbital predictions become critical for space operations. Current orbit propagators use the two-body solution with perturbations added, which have significant error growth when numerically integrated for long time periods. The Vinti Solution is a more accurate model than the two-body problem because it also accounts for the equatorial bulge of the Earth. Unfortunately, the Vinti solution contains small divisors near orbital resonances in the perturbative terms of the Hamiltonian, which lead to inaccurate orbital predictions. One approach to avoid the small divisors is to apply transformation theory, which is presented in this research. The methodology of this research is to identify the perturbative terms of the Vinti Solution, perform a coordinate transformation, and derive the new equations of motion for the Vinti system near orbital resonances. An analysis of these equations of motion offers insight into the dynamics found near orbital resonances. The analysis in this research focuses on the 2:1 resonance, which includes the Global Positioning System. The phase portrait of a nominal Global Positioning System satellite orbit is found to contain a libration region and a chaotic region. Further analysis shows that the dynamics of the 2:1 resonance affects orbits with semi-major axes ranging from -5.0 to +5.4 kilometers from an exactly 2:1 resonant orbit. Truth orbits of seven Global Positioning System satellites are produced for 10 years. Two of the satellites are found to be outside of the resonance region and three are found to be influenced by the libration dynamics of the resonance. The final satellite is found to be influenced by the chaotic dynamics of the resonance. This research provides a method of avoiding the small divisors found in the perturbative terms of the Vinti Solution near orbital resonances.

Adult onset glycogen storage disease type II (adult onset Pompe disease): report and magnetic resonance images of two cases

International Nuclear Information System (INIS)

Del Gaizo, Andrew; Banerjee, Sima; Terk, Michael

2009-01-01

Glycogen storage disease type II (GSDII), also referred to as Pompe disease or acid maltase deficiency, is a rare inherited condition caused by a deficiency in acid alpha-glucosidase (GAA) enzyme activity. The condition is often classified by age of presentation, with infantile and late onset variants (Laforet et al. J Neurology 55:1122-8, 2000). Late onset tends to present with progressive proximal muscle weakness and respiratory insufficiency (Winkel et al. J Neurology 252:875-84, 2005). We report two cases of biopsy confirmed adult onset GSDII, along with key Magnetic Resonance (MR) images. (orig.)

Analysis and development of fourth order LCLC resonant based capacitor charging power supply for pulse power applications.

Science.gov (United States)

Naresh, P; Hitesh, C; Patel, A; Kolge, T; Sharma, Archana; Mittal, K C

2013-08-01

A fourth order (LCLC) resonant converter based capacitor charging power supply (CCPS) is designed and developed for pulse power applications. Resonant converters are preferred t utilize soft switching techniques such as zero current switching (ZCS) and zero voltage switching (ZVS). An attempt has been made to overcome the disadvantages in 2nd and 3rd resonant converter topologies; hence a fourth order resonant topology is used in this paper for CCPS application. In this paper a novel fourth order LCLC based resonant converter has been explored and mathematical analysis carried out to calculate load independent constant current. This topology provides load independent constant current at switching frequency (fs) equal to resonant frequency (fr). By changing switching condition (on time and dead time) this topology has both soft switching techniques such as ZCS and ZVS for better switching action to improve the converter efficiency. This novel technique has special features such as low peak current through switches, DC blocking for transformer, utilizing transformer leakage inductance as resonant component. A prototype has been developed and tested successfully to charge a 100 μF capacitor to 200 V.

Time-domain, nuclear-resonant, forward scattering: the classical approach

International Nuclear Information System (INIS)

Hoy, G.R.

1997-01-01

This paper deals with the interaction of electromagnetic radiation with matter assuming the matter to have nuclear transitions in resonance with incident electromagnetic radiation. The source of the radiation is taken to be of two types; natural radioactive gamma decay and synchrotron radiation. Numerical examples using 57 Fe are given for the two types of source radiation. Calculated results are contrasted for the two cases. Electromagnetic radiation produced by recoil-free gamma-ray emission has essentially the natural linewidth. Electromagnetic radiation from a synchrotron, even with the best monochromators available, has a relatively broad-band spectrum, essentially constant for these considerations. Polarization effects are considered. In general, the nuclear-resonant medium changes the polarization of the input radiation on traversing the medium. Calculations are presented to illustrate that synchrotron radiation studies using nuclear-resonant forward scattering have the potential for making high-precision measurements of hyperfine fields and recoilless fractions. An interesting aspect of nuclear-resonant forward scattering, relative to possible gamma-ray laser development, is the so-called 'speed-up' effect

Giant resonances in free atoms and in clusters

International Nuclear Information System (INIS)

Brechignac, C.; Connerade, J.P.

1994-01-01

A review of recent developments in the study of giant resonances in free atoms and in clusters is presented, with particular emphasis on the transition from free atoms to atoms in the condensed phase. Giant resonances in alkali and related metallic clusters due to the excitation of closed shells of delocalized electrons are also reviewed and the relation between different types of collective oscillations is discussed. (author)

Highly Tunable Electrothermally Actuated Arch Resonator

KAUST Repository

Hajjaj, Amal Z.

2016-12-05

This paper demonstrates experimentally, theoretically, and numerically a wide-range tunability of electrothermally actuated MEMS arch beams. The beams are made of silicon and are intentionally fabricated with some curvature as in-plane shallow arches. Analytical results based on the Galerkin discretization of the Euler Bernoulli beam theory are generated and compared to the experimental data and results of a multi-physics finite-element model. A good agreement is found among all the results. The electrothermal voltage is applied between the anchors of the clamped-clamped MEMS arch beam, generating a current that passes through the MEMS arch beam and controls its axial stress caused by thermal expansion. When the electrothermal voltage increases, the compressive stress increases inside the arch beam. This leads to increase in its curvature, thereby increases the resonance frequencies of the structure. We show here that the first resonance frequency can increase up to twice its initial value. We show also that after some electro-thermal voltage load, the third resonance frequency starts to become more sensitive to the axial thermal stress, while the first resonance frequency becomes less sensitive. These results can be used as guidelines to utilize arches as wide-range tunable resonators.

Apodized coupled resonator waveguides.

Science.gov (United States)

Capmany, J; Muñoz, P; Domenech, J D; Muriel, M A

2007-08-06

In this paper we propose analyse the apodisation or windowing of the coupling coefficients in the unit cells of coupled resonator waveguide devices (CROWs) as a means to reduce the level of secondary sidelobes in the bandpass characteristic of their transfer functions. This technique is regularly employed in the design of digital filters and has been applied as well in the design of other photonic devices such as corrugated waveguide filters and fiber Bragg gratings. The apodisation of both Type-I and Type-II structures is discussed for several windowing functions.

Study of iron solubility in aluminium and SAP-type materials by the method of nuclear gamma resonance

International Nuclear Information System (INIS)

Nechaev, Yu.S.; Edigarov, V.S.; Pustov, Yu.A.

1979-01-01

Presented are the results of studying equilibrium solubility of iron (FeAl 3 ) in aluminium crystals with a conventional density of dislocations (rhosub(perpendicular) approximately 10 6 cm -2 ), and in crystals of the SAP type with rhosub(perpendicular) approximately 10 9 cm -2 . The method of gamma-resonance spectroscopy, chemical analysis were used as well as measurements of residual electric resistivity. Changes in entropy and enthalpy are determined while dissolving a FeAl 3 mole in aluminium lattice. The analysis of the data obtained allows one to suppose the presence of regions with high local concentrations of iron atoms near dislocations, the atoms being in two different states which provide respectively a doublet and a singlet in the Moessbauer spectrum

Microelectromechanical filter formed from parallel-connected lattice networks of contour-mode resonators

Science.gov (United States)

Wojciechowski, Kenneth E; Olsson, III, Roy H; Ziaei-Moayyed, Maryam

2013-07-30

A microelectromechanical (MEM) filter is disclosed which has a plurality of lattice networks formed on a substrate and electrically connected together in parallel. Each lattice network has a series resonant frequency and a shunt resonant frequency provided by one or more contour-mode resonators in the lattice network. Different types of contour-mode resonators including single input, single output resonators, differential resonators, balun resonators, and ring resonators can be used in MEM filter. The MEM filter can have a center frequency in the range of 10 MHz-10 GHz, with a filter bandwidth of up to about 1% when all of the lattice networks have the same series resonant frequency and the same shunt resonant frequency. The filter bandwidth can be increased up to about 5% by using unique series and shunt resonant frequencies for the lattice networks.

Forces of vortice trapping and critical current in type II superconductors

International Nuclear Information System (INIS)

Bormio, C.

1985-12-01

The vortice-centers interactions of trapping in type II superconductor materials were studied by two theories: thermodynamic (Hampshire-Taylor) and microscopic (Larkin - Ovchinnikov). The study was applied to NbTi with composition of 50% weight of Ti. They are commercial cables containing 361 filaments with final diameter of 0.35 mm for the wire and 9.2 μm foi filaments. The material presents high deformation rate in area and high density of dislocations. These defects actuate as centers of trapping. Variations in themomechanical treatments of superconductor cables modify the interaction mechanisms. The specific mechanism for each treatment type was identified. Measurements of critical current density in function of magnetic field in the range from 1 to 7 Tesla were done, which the usual superconductor parameters as upper critical field and Ginzburg - Landau (Kappa-k) parameter are estimated from literature data. (M.C.K.) [pt

Pierce-type dispersion relation for an intense relativistic electron beam interacting with a slow-wave structure

International Nuclear Information System (INIS)

Chen, C.

1994-01-01

A Pierce-type dispersion relation is derived for the interaction of an intense relativistic electron beam with a cylindrical slow-wave structure of arbitrary corrugation depth. It is shown that near a resonance, the Pierce parameter can be expressed in terms of the vacuum dispersion function and the beam current. The dispersion relation is valid in both the low-current (Compton) regime and the high-current (Raman) regime. The dispersion characteristics of the interaction, such as the linear instability growth rate and bandwidth, are analyzed for both regimes

High-resolution imaging of the spine in young infants with a loop-gap resonator remote current return coil

International Nuclear Information System (INIS)

Ball, W.S.; Prenger, E.C.; Auringer, S.T.

1989-01-01

MR imaging of the young child's spin requires proper selection of surface coils and pulse sequences that optimize resolution. The authors report the use in the infant spine of a new coil design in combination with specialized pulse sequences, such as fat suppression. Thirty children underwent spine MR imaging with a loop-gap resonator remote current return (RCR) coil. Spin-echo T1-weighted, T2-weighted, and T1-weighted fat-suppression pulse sequences were performed on a 1.5-T imager. Twelve patients had normal studies, 14 had spinal dysraphism, two had drop metastases, and two had paravertebral masses. Twelve initial patients had comparison images obtained with a 5-inch general-purpose surface coil. Similar pulse sequences were used for each coil. Image were compared diagnostically and for resolution based on the ability to discriminate small intrathecal structures

Magnetic resonance imaging reveals altered distribution of hepatic fat in children with type 1 diabetes compared to controls.

Science.gov (United States)

Regnell, Simon E; Peterson, Pernilla; Trinh, Lena; Broberg, Per; Leander, Peter; Lernmark, Åke; Månsson, Sven; Elding Larsson, Helena

2015-08-01

Children with type 1 diabetes have been identified as a risk group for non-alcoholic fatty liver disease (NAFLD). The aim was to compare total hepatic fat fraction and fat distribution across Couinaud segments in children with type 1 diabetes and controls and the relation of hepatic fat to plasma and anthropometric parameters. Hepatic fat fraction and fat distribution across Couinaud segments were measured with magnetic resonance imaging (MRI) in 22 children with type 1 diabetes and 32 controls. Blood tests and anthropometric data were collected. No children had NAFLD. Children with type 1 diabetes had a slightly lower hepatic fat fraction (median 1.3%) than controls (median 1.8%), and their fat had a different segmental distribution. The fat fraction of segment V was the most representative of the liver as a whole. An incidental finding was that diabetes patients treated with multiple daily injections of insulin (MDI) had a fat distribution more similar to controls than patients with continuous subcutaneous insulin infusion (CSII). In children with type 1 diabetes, NAFLD may be less common than recent studies have suggested. Children with type 1 diabetes may have a lower fat fraction and a different fat distribution in the liver than controls. Diabetes treatment with MDI or CSII may affect liver fat, but this needs to be confirmed in a larger sample of patients. The heterogeneity of hepatic fat infiltration may affect results when liver biopsy is used for diagnosing fatty liver. Copyright © 2015 Elsevier Inc. All rights reserved.

Nonlinear dynamics in micromechanical and nanomechanical resonators and oscillators

Science.gov (United States)

Dunn, Tyler

In recent years, the study of nonlinear dynamics in microelectromechanical and nanoelectromechanical systems (MEMS and NEMS) has attracted considerable attention, motivated by both fundamental and practical interests. One example is the phenomenon of stochastic resonance. Previous measurements have established the presence of this counterintuitive effect in NEMS, showing that certain amounts of white noise can effectively amplify weak switching signals in nanomechanical memory elements and switches. However, other types of noise, particularly noises with 1/falpha spectra, also bear relevance in these and many other systems. At a more fundamental level, the role which noise color plays in stochastic resonance remains an open question in the field. To these ends, this work presents systematic measurements of stochastic resonance in a nanomechanical resonator using 1/f alpha and Ornstein-Uhlenbeck noise types. All of the studied noise spectra induce stochastic resonance, proving that colored noise can also be beneficial; however, stronger noise correlations suppress the effect, decreasing the maximum signal-to-noise ratio and increasing the optimal noise intensity. Evidence suggests that 1/falpha noise spectra with increasing noise color lead to increasingly asymmetric switching, reducing the achievable amplification. Another manifestly nonlinear effect anticipated in these systems is modal coupling. Measurements presented here demonstrate interactions between various mode types on a wide scale, providing the first reported observations of coupling in bulk longitudinal modes of MEMS. As a result of anharmonic elastic effects, each mode shifts in frequency by an amount proportional to the squared displacement (or energy) of a coupled mode. Since all resonator modes couple in this manner, these effects enable nonlinear measurement of energy and mechanical nonlinear signal processing across a wide range of frequencies. Finally, while these experiments address nonlinear

Coil-type Fano Resonances: a Plasmonic Approach to Magnetic Sub-diffraction Confinement

KAUST Repository

Panaro, Simone

2015-05-10

Matrices of nanodisk trimers are introduced as plasmonic platforms for the generation of localized magnetic hot-spots. In Fano resonance condition, the optical magnetic fields can be squeezed in sub-wavelength regions, opening promising scenarios for spintronics.

Coil-type Fano Resonances: a Plasmonic Approach to Magnetic Sub-diffraction Confinement

KAUST Repository

Panaro, Simone; Nazir, Adnan; Zaccaria, Remo Proietti; Liberale, Carlo; De Angelis, Francesco; Toma, Andrea

2015-01-01

Matrices of nanodisk trimers are introduced as plasmonic platforms for the generation of localized magnetic hot-spots. In Fano resonance condition, the optical magnetic fields can be squeezed in sub-wavelength regions, opening promising scenarios for spintronics.

Resonant activation in 2D and 3D systems driven by multi-variate Lévy noise

International Nuclear Information System (INIS)

Szczepaniec, Krzysztof; Dybiec, Bartłomiej

2014-01-01

Resonant activation is one of the classical effects demonstrating the constructive role of noise. In resonant activation, the cooperative action of a barrier modulation process and noise lead to the optimal escape kinetics as measured by the mean first passage time. Resonant activation has been observed in versatile systems for various types of barrier modulation process and noise type. Here, we show that resonant activation is also observed in 2D and 3D systems driven by bi-variate and tri-variate α-stable noise. The strength of resonant activation is sensitive to the exact value of the noise parameters. In particular, the decrease in the stability index α results in the disappearance of the resonant activation. (paper)