Energy Technology Data Exchange (ETDEWEB)
Zhang, Pei
2013-02-15
Higher order modes (HOM) are electromagnetic resonant fields. They can be excited by an electron beam entering an accelerating cavity, and constitute a component of the wakefield. This wakefield has the potential to dilute the beam quality and, in the worst case, result in a beam-break-up instability. It is therefore important to ensure that these fields are well suppressed by extracting energy through special couplers. In addition, the effect of the transverse wakefield can be reduced by aligning the beam on the cavity axis. This is due to their strength depending on the transverse offset of the excitation beam. For suitably small offsets the dominant components of the transverse wakefield are dipole modes, with a linear dependence on the transverse offset of the excitation bunch. This fact enables the transverse beam position inside the cavity to be determined by measuring the dipole modes extracted from the couplers, similar to a cavity beam position monitor (BPM), but requires no additional vacuum instrumentation. At the FLASH facility in DESY, 1.3 GHz (known as TESLA) and 3.9 GHz (third harmonic) cavities are installed. Wakefields in 3.9 GHz cavities are significantly larger than in the 1.3 GHz cavities. It is therefore important to mitigate the adverse effects of HOMs to the beam by aligning the beam on the electric axis of the cavities. This alignment requires an accurate beam position diagnostics inside the 3.9 GHz cavities. It is this aspect that is focused on in this thesis. Although the principle of beam diagnostics with HOM has been demonstrated on 1.3 GHz cavities, the realization in 3.9 GHz cavities is considerably more challenging. This is due to the dense HOM spectrum and the relatively strong coupling of most HOMs amongst the four cavities in the third harmonic cryo-module. A comprehensive series of simulations and HOM spectra measurements have been performed in order to study the modal band structure of the 3.9 GHz cavities. The dependencies of
Higher Order Modes in Third Harmonic Cavities for XFEL/FLASH
Energy Technology Data Exchange (ETDEWEB)
Shinton, I.R.R.; /Manchester U. /Cockcroft Inst. Accel. Sci. Tech.; Baboi, N.; /DESY; Eddy, N.; /Fermilab; Flisgen, T.; Glock, H.W.; /Rostock U.; Jones, R.M.; Juntong, N.; /Manchester U. /DESY; Khabiboulline, T.N.; /Fermilab; van Rienen, U; /Rostock U.; Zhang, P.; /Manchester U. /DESY /Cockcroft Inst. Accel. Sci. Tech.
2010-06-01
We analyse higher order modes in the 3.9 GHz bunch shaping cavities recently installed in the FLASH facility at DESY. We report on recent experimental results on the frequency spectrum from probe based measurements made at CMTB at DESY. These are compared to those predicted by finite difference and finite element computer codes. This study is focused mainly on the dipole component of the multi-pole expansion of the wakefield. The modes are readily identifiable as single-cavity modes provided the frequencies of these modes are below the cut-off of the inter-connecting beam pipes. The modes above cut-off are coupled to the 4 cavities and are distinct from single cavity modes.
Zhang, P; Baboi, Nicoleta
2012-01-01
Higher order modes (HOM) are electromagnetic resonant fields. They can be excited by an electron beam entering an accelerating cavity, and constitute a component of the wakefield. This wakefield has the potential to dilute the beam quality and, in the worst case, result in a beam-break-up instability. It is therefore important to ensure that these fields are well suppressed by extracting energy through special couplers. In addition, the effect of the transverse wakefield can be reduced by aligning the beam on the cavity axis. This is due to their strength depending on the transverse offset of the excitation beam. For suitably small offsets the dominant components of the transverse wakefield are dipole modes, with a linear dependence on the transverse offset of the excitation bunch. This fact enables the transverse beam position inside the cavity to be determined by measuring the dipole modes extracted from the couplers, similar to a cavity beam position monitor (BPM), but requires no additional vacuum instrum...
Energy Technology Data Exchange (ETDEWEB)
Zhang, Pei [Manchester Univ. (United Kingdom); Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Baboi, Nicoleta [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Jones, Roger M. [The Cockcroft Institute, Daresbury (United Kingdom)
2012-06-15
An electron beam entering an accelerating cavity excites a wakefield. This wakefield can be decomposed into a series of multi-poles or modes. The dominant component of the transverse wakefield is dipole. This report summarizes the higher order mode (HOM) signals of the third harmonic cavities of FLASH measured at various stages: transmission measurements in the single cavity test stand at Fermilab, at CMTB (Cryo- Module Test Bench) and at FLASH, and beam-excited measurements at FLASH. Modes in the first two dipole bands and the fifth dipole band have been identified using a global Lorentzian fit technique. The beam-pipe modes at approximately 4 GHz and some modes in the fifth dipole band have been observed as localized modes, while the first two dipole bands, containing some strong coupling cavity modes, propagate. This report also presents the dependence of the localized dipole modes on the transverse beam position. Linear dependence for various modes has been observed. This makes them suitable for beam position diagnostics. These modes, together with some propagating, strong coupling modes, have been considered in the design of a dedicated electronics for beam diagnostics with HOMs for the third harmonic cavities.
Zhang, P; Jones, R M
2012-01-01
An electron beam entering an accelerating cavity excites a wakefield. This wakefield can be decomposed into a series of multi-poles or modes. The dominant component of the transverse wakefield is dipole. This report summarizes the higher order mode (HOM) signals of the third harmonic cavities of FLASH measured at various stages: transmission measurements in the single cavity test stand at Fermilab, at CMTB (Cryo-Module Test Bench) and at FLASH, and beam-excited measurements at FLASH. Modes in the first two dipole bands and the fifth dipole band have been identified using a global Lorentzian fit technique. The beam-pipe modes at approximately 4 GHz and some modes in the fifth dipole band have been observed as localized modes, while the first two dipole bands, containing some strong coupling cavity modes, propagate. This report also presents the dependence of the localized dipole modes on the transverse beam position. Linear dependence for various modes has been observed. This makes them suitable for beam posit...
Lifetime increase using passive harmonic cavities in synchrotron light sources
Directory of Open Access Journals (Sweden)
J. M. Byrd
2001-03-01
Full Text Available Harmonic cavities have been used in storage rings to increase beam lifetime and Landau damping by lengthening the bunch. The need for lifetime increase is particularly great in the present generation of low to medium energy synchrotron light sources where the small transverse beam sizes lead to relatively short lifetimes from large-angle intrabeam (Touschek scattering. We review the beam dynamics of harmonic radio-frequency systems and discuss optimization of the beam lifetime using passive harmonic cavities.
Effects of the Passive Harmonic Cavity on the Beam Bunch
Chang Lung Hai; Wang, Chaoen; Yeh, Meng-Shu
2005-01-01
In this paper, we present a computer tracking code, which can investigate the bunch length, energy spread and the critical current of Robinson instability under the influence of the passive harmonic cavity. The effects of the radiation damping, quantum excitation and the beam loading of the harmonic cavity are included in the computation. The calculated result shows that the beam has a constant energy spread and blows up as the beam current increases from below to over the threshold current of the Robinson instability. It also indicates that the shunt impedance of the harmonic cavity is critical for whether the harmonic cavity can reach the designed goal, a stable and lengthening beam at the design beam current.
Energy Technology Data Exchange (ETDEWEB)
Zhang, P. [Cockcroft Inst. Accel. Sci. Tech.; Baboi, N. [DESY; Eddy, N. [Fermilab; Fellenz, B. [Fermilab; Jones, R. M. [Cockcroft Inst. Accel. Sci. Tech.; Lorbeer, B. [DESY; Wamsat, T. [DESY; Wendt, M. [Fermilab
2012-08-01
Beam-excited higher order modes (HOM) in accelerating cavities contain transverse beam position information. Previous studies have narrowed down three modal options for beam position diagnostics in the third harmonic 3.9 GHz cavities at FLASH. Localized modes in the beam pipes at approximately 4.1 GHz and in the fifth cavity dipole band at approximately 9 GHz were found, that can provide a local measurement of the beam position. In contrast, propagating modes in the first and second dipole bands between 4.2 and 5.5 GHz can reach a better resolution. All the options were assessed with a specially designed test electronics built by Fermilab. The aim is to define a mode or spectral region suitable for the HOM electronics. Two data analysis techniques are used and compared in extracting beam position information from the dipole HOMs: direct linear regression and singular value decomposition. Current experiments suggest a resolution of 50 {\\mu}m accuracy in predicting local beam position using modes in the fifth dipole band, and a global resolution of 20 {\\mu}m over the complete module. Based on these results we decided to build a HOM electronics for the second dipole band and the fifth dipole band, so that we will have both high resolution measurements for the whole module, and localized measurements for individual cavity. The prototype electronics is being built by Fermilab and planned to be tested in FLASH by the end of 2012.
Energy Technology Data Exchange (ETDEWEB)
Zhang, P. [Manchester Univ. (United Kingdom); Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Baboi, N.; Lorbeer, B.; Wamsat, T. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Eddy, N.; Fellenz, B.; Wendt, M. [Fermi National Accelerator Lab., Batavia, IL (United States); Jones, R.M. [Manchester Univ. (United Kingdom); The Cockcroft Institute, Daresbury (United Kingdom)
2012-08-15
Beam-excited higher order modes (HOM) in accelerating cavities contain transverse beam position information. Previous studies have narrowed down three modal options for beam position diagnostics in the third harmonic 3.9 GHz cavities at FLASH. Localized modes in the beam pipes at approximately 4.1 GHz and in the fifth cavity dipole band at approximately 9 GHz were found, that can provide a local measurement of the beam position. In contrast, propagating modes in the first and second dipole bands between 4.2 and 5.5 GHz can reach a better resolution. All the options were assessed with a specially designed test electronics built by Fermilab. The aim is to de ne a mode or spectral region suitable for the HOM electronics. Two data analysis techniques are used and compared in extracting beam position information from the dipole HOMs: direct linear regression and singular value decomposition. Current experiments suggest a resolution of 50 m accuracy in predicting local beam position using modes in the fifth dipole band, and a global resolution of 20 m over the complete module. Based on these results we decided to build a HOM electronics for the second dipole band and the fifth dipole band, so that we will have both high resolution measurements for the whole module, and localized measurements for individual cavity. The prototype electronics is being built by Fermilab and planned to be tested in FLASH by the end of 2012.
Zhang, P; Eddy, N; Fellenz, B; Jones, R M; Lorbeer, B; Wamsat, T; Wendt, M
2012-01-01
Beam-excited higher order modes (HOM) in accelerating cavities contain transverse beam position information. Previous studies have narrowed down three modal options for beam position diagnostics in the third harmonic 3.9 GHz cavities at FLASH. Localized modes in the beam pipes at approximately 4.1 GHz and in the fifth cavity dipole band at approximately 9 GHz were found, that can provide a local measurement of the beam position. In contrast, propagating modes in the first and second dipole bands between 4.2 and 5.5 GHz can reach a better resolution. All the options were assessed with a specially designed test electronics built by Fermilab. The aim is to define a mode or spectral region suitable for the HOM electronics. Two data analysis techniques are used and compared in extracting beam position information from the dipole HOMs: direct linear regression and singular value decomposition. Current experiments suggest a resolution of 50 micron accuracy in predicting local beam position using modes in the fifth d...
Energy Technology Data Exchange (ETDEWEB)
Zhang, Pei [Manchester Univ. (United Kingdom). School of Physics and Astronomy; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Baboi, Nicoleta [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Jones, Roger M. [Manchester Univ. (United Kingdom). School of Physics and Astronomy; The Cockcroft Institute, Daresbury, Warrington (United Kingdom)
2012-06-15
The third harmonic nine-cell cavity (3.9 GHz) for FLASH and the European XFEL has been investigated using simulations performed with the computer code CST Microwave Studio registered. The band structure of monopole, dipole, quadrupole and sextupole modes for an ideal cavity has been studied. The higher order modes for the nine-cell structure are compared with that of the cavity mid-cell. The R/Q of these eigenmodes are calculated.
Harmonically resonant cavity as a bunch-length monitor
Directory of Open Access Journals (Sweden)
B. Roberts
2016-05-01
Full Text Available A compact, harmonically resonant cavity with fundamental resonant frequency 1497 MHz was used to evaluate the temporal characteristics of electron bunches produced by a 130 kV dc high voltage spin-polarized photoelectron source at the Continuous Electron Beam Accelerator Facility (CEBAF photoinjector, delivered at 249.5 and 499 MHz repetition rates and ranging in width from 45 to 150 picoseconds (FWHM. A cavity antenna attached directly to a sampling oscilloscope detected the electron bunches as they passed through the cavity bore with a sensitivity of ∼1 mV/μA. The oscilloscope waveforms are a superposition of the harmonic modes excited by the beam, with each cavity mode representing a term of the Fourier series of the electron bunch train. Relatively straightforward post-processing of the waveforms provided a near-real time representation of the electron bunches revealing bunch-length and the relative phasing of interleaved beams. The noninvasive measurements from the harmonically resonant cavity were compared to measurements obtained using an invasive RF-deflector-cavity technique and to predictions from particle tracking simulations.
Calculation of RF Properties of the Third Harmonic Cavity
Rothemund, K; Van Rienen, U
2004-01-01
Recently a third harmonic structure has been proposed for the injector of the TTF-FEL to avoid nonlinear distortions in the longitudinal phase space. This structure, consists of four nine cell TESLA-like cavities. For the use of this structure in combination with the TTF-FEL it might be interesting to investigate higher order modes (HOM) in the structure and their effect on the beam dynamics. The complexity of the structure, four nine cell cavities assembled with four input couplers and eight HOM-couplers, results in an extremely high numerical effort for full 3D modelling. Therefor Coupled S-Parameter Calculation (CSC) [1] has been applied. This method is based on the scattering parameter description of the rf components found with field solving codes or analytically for components of special symmetry. This paper presents the results of the calculation of rf properties (e.g. scattering parameters, Q-values) of the complete four times nine cell structure equipped with all input- and HOM-couplers.
Resonance widths in open microwave cavities studied by harmonic inversion.
Kuhl, U; Höhmann, R; Main, J; Stöckmann, H-J
2008-06-27
From the measurement of a reflection spectrum of an open microwave cavity, the poles of the scattering matrix in the complex plane have been determined. The resonances have been extracted by means of the harmonic inversion method. By this, it became possible to resolve the resonances in a regime where the linewidths exceed the mean level spacing up to a factor of 10, a value inaccessible in experiments up to now. The obtained experimental distributions of linewidths were found to be in perfect agreement with predictions from random matrix theory when wall absorption and fluctuations caused by couplings to additional channels are considered.
Resonance widths in open microwave cavities studied by harmonic inversion
Kuhl, U.; Hoehmann, R.; Main, J; Stoeckmann, H. -J.
2007-01-01
From the measurement of a reflection spectrum of an open microwave cavity the poles of the scattering matrix in the complex plane have been determined. The resonances have been extracted by means of the harmonic inversion method. By this it became possible to resolve the resonances in a regime where the line widths exceed the mean level spacing up to a factor of 10, a value inaccessible in experiments up to now. The obtained experimental distributions of line widths were found to be in perfec...
Third harmonic cavity design and RF measurements for the Frascati DAΦNE collider
Directory of Open Access Journals (Sweden)
David Alesini
2004-09-01
Full Text Available Third harmonic passive RF cavities have been proposed for installation in both rings of the DAΦNE factory collider to improve the Touschek lifetime and to increase the Landau damping. This paper illustrates the design of the harmonic cavities. The main requirements were to obtain a relatively low R/Q factor and a quality factor Q as high as possible to satisfy beam dynamics requirements and to damp all the higher order mode (HOM to a harmless level in order to avoid multibunch instabilities. A spherical shape of the cavity central body has been chosen as an optimum compromise between a high Q resonator and a low R/Q factor. HOM suppression has been provided by a ferrite ring damper designed for the superconducting cavities of the high energy ring of the KEK-B factory. The design and electromagnetic properties of the resonant modes have been studied with MAFIA and HFSS codes. Cavities have been made of aluminum and the RF measurements have been performed to characterize them. The measurements are in a good agreement with numerical simulations results, demonstrating a satisfactory HOM damping.
Unlocking higher harmonics in atomic force microscopy with gentle interactions
Directory of Open Access Journals (Sweden)
Sergio Santos
2014-03-01
Full Text Available In dynamic atomic force microscopy, nanoscale properties are encoded in the higher harmonics. Nevertheless, when gentle interactions and minimal invasiveness are required, these harmonics are typically undetectable. Here, we propose to externally drive an arbitrary number of exact higher harmonics above the noise level. In this way, multiple contrast channels that are sensitive to compositional variations are made accessible. Numerical integration of the equation of motion shows that the external introduction of exact harmonic frequencies does not compromise the fundamental frequency. Thermal fluctuations are also considered within the detection bandwidth of interest and discussed in terms of higher-harmonic phase contrast in the presence and absence of an external excitation of higher harmonics. Higher harmonic phase shifts further provide the means to directly decouple the true topography from that induced by compositional heterogeneity.
Tiltrotor Vibration Reduction Through Higher Harmonic Control
Nixon, Mark W.; Kvaternik, Raymond G.; Settle, T. Ben
1997-01-01
The results of a joint NASA/Army/Bell Helicopter Textron wind-tunnel test to assess the potential of higher harmonic control (HHC) for reducing vibrations in tiltrotor aircraft operating in the airplane mode of flight, and to evaluate the effectiveness of a Bell-developed HHC algorithm called MAVSS (Multipoint Adaptive Vibration Suppression System) are presented. The test was conducted in the Langley Transonic Dynamics Tunnel using an unpowered 1/5-scale semispan aeroelastic model of the V-22 which was modified to incorporate an HHC system employing both the rotor swashplate and the wing flaperon. The effectiveness of the swashplate and the flaperon acting either singly or in combination in reducing IP and 3P wing vibrations over a wide range of tunnel airspeeds and rotor rotational speeds was demonstrated. The MAVSS algorithm was found to be robust to variations in tunnel airspeed and rotor speed, requiring only occasional on-line recalculations of the system transfer matrix. HHC had only a small (usually beneficial) effect on blade loads but increased pitch link loads by 25%. No degradation in aeroelastic stability was noted for any of the conditions tested.
Aeroelastic simulation of higher harmonic control
Robinson, Lawson H.; Friedmann, Peretz P.
1994-01-01
This report describes the development of an aeroelastic analysis of a helicopter rotor and its application to the simulation of helicopter vibration reduction through higher harmonic control (HHC). An improved finite-state, time-domain model of unsteady aerodynamics is developed to capture high frequency aerodynamic effects. An improved trim procedure is implemented which accounts for flap, lead-lag, and torsional deformations of the blade. The effect of unsteady aerodynamics is studied and it is found that its impact on blade aeroelastic stability and low frequency response is small, but it has a significant influence on rotor hub vibrations. Several different HHC algorithms are implemented on a hingeless rotor and their effectiveness in reducing hub vibratory shears is compared. All the controllers are found to be quite effective, but very differing HHC inputs are required depending on the aerodynamic model used. Effects of HHC on rotor stability and power requirements are found to be quite small. Simulations of roughly equivalent articulated and hingeless rotors are carried out, and it is found that hingeless rotors can require considerably larger HHC inputs to reduce vibratory shears. This implies that the practical implementation of HHC on hingeless rotors might be considerably more difficult than on articulated rotors.
Higher Harmonic Control for Tiltrotor Vibration Reduction
Nixon, Mark W.; Kvaternik, Raymond G.; Settle, T. Ben
1997-01-01
The results of a joint NASA/Army/Bell Helicopter Textron wind-tunnel test to assess the potential of higher harmonic control (HHC) for reducing vibrations in tiltrotor aircraft operating in the airplane mode of flight, and to evaluate the effectiveness of a Bell-developed HHC algorithm called MAVSS (Multipoint Adaptive Vibration Suppression System) are presented. The test was conducted in the Langley Transonic Dynamics Tunnel using an unpowered 1/5- scale semispan aeroelastic model of the V-22 which was modified to incorporate an HHC system employing both the rotor swashplate and the wing flaperon. The effectiveness of the swashplate and the flaperon acting either singly or in combination in reducing 1P and 3P wing vibrations over a wide range of tunnel airspeeds and rotor rotational speeds was demonstrated. The MAVSS algorithm was found to be robust to variations in tunnel airspeed and rotor speed, requiring only occasion-al on-line recalculations of the system transfer matrix.
Linearization of the longitudinal phase space without higher harmonic field
Directory of Open Access Journals (Sweden)
Benno Zeitler
2015-12-01
Full Text Available Accelerator applications like free-electron lasers, time-resolved electron diffraction, and advanced accelerator concepts like plasma acceleration desire bunches of ever shorter longitudinal extent. However, apart from space charge repulsion, the internal bunch structure and its development along the beam line can limit the achievable compression due to nonlinear phase space correlations. In order to improve such a limited longitudinal focus, a correction by properly linearizing the phase space is required. At large scale facilities like Flash at Desy or the European Xfel, a higher harmonic cavity is installed for this purpose. In this paper, another method is described and evaluated: Expanding the beam after the electron source enables a higher order correction of the longitudinal focus by a subsequent accelerating cavity which is operated at the same frequency as the electron gun. The elaboration of this idea presented here is based on a ballistic bunching scheme, but can be extended to bunch compression based on magnetic chicanes. The core of this article is an analytic model describing this approach, which is verified by simulations, predicting possible bunch length below 1 fs at low bunch charge. Minimizing the energy spread down to σ_{E}/E<10^{-5} while keeping the bunch long is another interesting possibility, which finds applications, e.g., in time resolved transmission electron microscopy concepts.
Generation of higher harmonic internal waves by oscillating spheroids
Shmakova, Natalia; Ermanyuk, Evgeny; Flór, Jan-Bert
2017-11-01
Oscillating bodies in stratified fluids may emit higher harmonics in addition to fundamental waves. In the present experimental study, we consider higher harmonics of an internal wave field generated by a horizontally oscillating spheroid in a linearly stratified fluid for moderate to high oscillation amplitudes, i.e., scaled oscillation amplitude A /a ≥0.5 , with a the minor radius of the spheroid. Three different spheroid shapes are tested. The results are discussed in the context of the different theories on the generation of higher harmonics. Higher harmonics are observed at the intersections of fundamental wave beams, and at the critical points of the topography where the topographic slope equals the wave slope. The velocity amplitudes of the fundamental, second, and third harmonic waves grow respectively linearly, quadratically, and with the third power of the scaled oscillation amplitude A /a . Though these amplitudes are generally higher when the object's slope is larger, the increase in amplitude above and below the axisymmetric oscillating objects is found to be due to the effect of focusing. In order to discern the relative importance of the harmonics to the fundamental wave, the horizontal structure of the wave amplitude is measured. The results suggest that the n th harmonic of the internal wave field is associated with a radiation diagram corresponding to a multipole of order 2n, with 2 n directions of propagation.
A 0.4-THz Second Harmonic Gyrotron with Quasi-Optical Confocal Cavity
Guan, Xiaotong; Fu, Wenjie; Yan, Yang
2017-12-01
Mode density is very relevant for harmonic gyrotron cavity. Theoretical investigations suggest that quasi-optical confocal waveguide performs low mode density and good mode-selective character. By selecting the appropriate mode and optimizing the cavity parameters, the quasi-optical confocal cavity is suitable for high-harmonic terahertz gyrotron without mode competition. In order to verify the theoretical analysis, a 0.4-THz second harmonic gyrotron has been designed and experimented. Driven by a 40-kV, 4.75-A electron beam and 7.51-T magnetic field, the gyrotron prototype could generate 6.44 kW of output power at 395.35 GHz, which corresponds to an electron efficiency of 3.4%. There is no mode competition between the second harmonic and fundamental observed in the experiments.
Higher-order Kerr effect and harmonic cascading in gases
Bache, Morten; Eilenberger, Falk; Minardi, Stefano
2012-01-01
The higher-order Kerr effect (HOKE) has recently been advocated to explain measurements of the saturation of the nonlinear refractive index in gases. Here we show that cascaded third-harmonic generation results in an effective fifth-order nonlinearity that is negative and significant. Higher-order harmonic cascading will also occur from the HOKE, and the cascading contributions may significantly modify the observed nonlinear index change. At lower wavelengths, cascading increases the HOKE sat...
Khripunov, Sergey; Kobtsev, Sergey; Radnatarov, Daba
2016-01-20
This work presents for the first time to the best of our knowledge a comparative efficiency analysis among various techniques of extra-cavity second harmonic generation (SHG) of continuous-wave single-frequency radiation in nonperiodically poled nonlinear crystals within a broad range of power levels. Efficiency of nonlinear radiation transformation at powers from 1 W to 10 kW was studied in three different configurations: with an external power-enhancement cavity and without the cavity in the case of single and double radiation pass through a nonlinear crystal. It is demonstrated that at power levels exceeding 1 kW, the efficiencies of methods with and without external power-enhancement cavities become comparable, whereas at even higher powers, SHG by a single or double pass through a nonlinear crystal becomes preferable because of the relatively high efficiency of nonlinear transformation and fairly simple implementation.
Optical bistabilities of higher harmonics: Inhomogeneous and transverse effects
Energy Technology Data Exchange (ETDEWEB)
Hassan, S.S., E-mail: Shoukryhassan@hotmail.com [Department of Mathematics, College of Science, University of Bahrain, P.O. Box 32038 (Bahrain); Manchester Metropolitan University, Dept. of Computing, Maths. and Digital Technology, Manchester M1 5GD (United Kingdom); Sharaby, Y.A., E-mail: Yasser_Sharaby@hotmail.com [Department of Physics, Faculty of Science, Suez Canal University, Suez (Egypt); Ali, M.F.M., E-mail: dr.mona.fathy@hotmail.com [Department of Mathematics: Faculty of Science, Ain Shams University, Cairo (Egypt); Joshi, A., E-mail: ajoshi@eiu.edu [Department of Physics, Eastern Illinois University, Charleston, IL 61920 (United States)
2012-10-15
The steady state behavior of optical bistable system in a ring cavity with transverse field variations and inhomogeneousely broadened two-level atoms is investigated outside the rotating wave approximation (RWA). Analytical and numerical investigation is presented for different cases of transverse field variations with Lorentzian or Gaussian line widths. When both (transverse and inhomogeneous) features taken into account, the first harmonic output field component outside the RWA exhibits a one-way switching down processes (butterfly OB) or reversed (clockwise) OB behavior, depending on the atomic linewidth shape.
Higher-order Kerr effect and harmonic cascading in gases
DEFF Research Database (Denmark)
Bache, Morten; Eilenberger, Falk; Minardi, Stefano
2012-01-01
The higher-order Kerr effect (HOKE) has recently been advocated to explain measurements of the saturation of the nonlinear refractive index in gases. Here we show that cascaded third-harmonic generation results in an effective fifth-order nonlinearity that is negative and significant. Higher......-order harmonic cascading will also occur from the HOKE, and the cascading contributions may significantly modify the observed nonlinear index change. At lower wavelengths, cascading increases the HOKE saturation intensity, while for longer wavelengths cascading will decrease the HOKE saturation intensity....
Higher-order Kerr effect and harmonic cascading in gases.
Bache, Morten; Eilenberger, Falk; Minardi, Stefano
2012-11-15
The higher-order Kerr effect (HOKE) has recently been advocated to explain measurements of the saturation of the nonlinear refractive index in gases. Here we show that cascaded third-harmonic generation results in an effective fifth-order nonlinearity that is negative and significant. Higher-order harmonic cascading will also occur from the HOKE, and the cascading contributions may significantly modify the observed nonlinear index change. At lower wavelengths, cascading increases the HOKE saturation intensity, while for longer wavelengths cascading will decrease the HOKE saturation intensity.
Modeling of higher harmonics formation in medical ultrasound systems
DEFF Research Database (Denmark)
Taylor, Louise Kold; Schlaikjer, Malene; Jensen, Jørgen Arendt
2002-01-01
The pressure eld emitted from multi-element medical ultrasound transducers can be simulated with Field II in the linear regime. By expanding this program's application to the nonlinear regime, beamforming schemes can be studied under strong focusing and high pressure levels as well, providing...... of the approach is demonstrated by comparing results from simulations and measurements from a convex array transducer. The new simulation tool is capable of simulating the formation of higher harmonics in water on the acoustical axis. The generation of nonlinear higher harmonic components can be predicted...
Higher Order Modes for Beam Diagnostics in Third Harmonic 3.9 GHz Accelerating Modules
Baboi, N; Flisgen, T; Glock, H-W; Jones, R M; Shinton, I R R; Zhang, P
2011-01-01
An international team is currently investigating the best way to use Higher Order Modes (HOM) for beam diagnostics in 3.9 GHz cavities. HOMs are excited by charged particles when passing through an accelerating structure. Third harmonic cavities working at 3.9 GHz have been installed in FLASH to linearize the bunch energy profile. A proof-of-principle of using HOMs for beam monitoring has been made at FLASH in the TESLA 1.3 GHz cavities. Since the wakefields generated in the 3.9 GHz cavities are significantly larger, their impact on the beam should be carefully minimized. Therefore our target is to monitor HOMs and minimize them by aligning the beam on the cavity axis. The difficulty is that, in comparison to the 1.3 GHz cavities, the HOM-spectrum is dense, making it difficult to identify individual modes. Also, most modes propagate through the whole cryomodule containing several cavities, making it difficult to measure local beam properties. In this paper the options for the HOM-based beam position monitors ...
Electron-bunch lengthening on higher-harmonic oscillations in storage-ring free-electron lasers.
Sei, Norihiro; Ogawa, Hiroshi; Okuda, Shuichi
2017-09-01
The influence of higher-harmonic free-electron laser (FEL) oscillations on an electron beam have been studied by measuring its bunch length at the NIJI-IV storage ring. The bunch length and the lifetime of the electron beam were measured, and were observed to have become longer owing to harmonic lasing, which is in accord with the increase of the FEL gain. It was demonstrated that the saturated FEL power could be described by the theory of bunch heating, even for the harmonic lasing. Cavity-length detuning curves were measured for the harmonic lasing, and it was found that the width of the detuning curve was proportional to a parameter that depended on the bunch length. These experimental results will be useful for developing compact resonator-type FELs by using higher harmonics in the extreme-ultraviolet and the X-ray regions.
Design of a higher harmonic RF system for the Advanced Light Source
Byrd, J M; De Santis, S; Kosta, S; Lo, C C; Plate, D; Rimmer, R A; Franks, M
2000-01-01
We report on the design and fabrication of a third harmonic radiofrequency (RF) system for the Advanced Light Source (ALS) to be used for lengthening the bunch and increasing the Touschek-dominated beam lifetime. We plan to install five single-cell 1.5 GHz copper RF cavities in one-half of an ALS straight section with a predicted increase in the lifetime by a factor of 3. Each RF cell is designed to sustain a maximum voltage of 125 kV with a power dissipation of 5 kW. We present measurements made on an aluminum cavity model characterizing the RF properties of cavity such as the cavity R/Q and higher-order modes (HOMs). In particular, resonances in the cavity tuners were studied in order to avoid heating of the tuner bellows. Initial measurements of the copper cavities indicate a Q value of 21 000, resulting in a shunt impedance of 1.69 M OMEGA per cell
A Suppression Method of Higher Harmonics Resonance in Distribution System
Sugimura, Shouji; Naitoh, Tadashi; Toyama, Atsushi; Ohta, Fumihiko
There are many PWM control apparatuses, which are higher harmonics current sources, in distribution systems. And higher harmonics causes over current by parallel resonance. To avoid the over current, it is necessary to suppress the resonance. In this paper, a new suppression method, which uses the effect of source connected point in resonance circuit, is proposed. Firstly it shows that the optimal point, which gives a minimum current amplification degree, is orthogonal to static condenser voltage. And then, using eigenvector of state equation, the participation factor is defined. When the participation factor is zero, the orthogonal condition is introduced. Therefore the optimal point is given by using with the participation factor. Finally, adopting numerical examination, it is known that multiple optimal points usually exist. Therefore, we can choose the advantageous point as a source connected node.
A Prediction Method of Higher Harmonics Resonance in Distribution System
Ikeda, Yuji; Toyama, Atushi; Takeda, Keiki; Naitoh, Tadashi; Masaki, Kazuyuki
There are many PWM control apparatuses, which are higher harmonics current sources, in distribution systems. And higher harmonics causes over current by parallel resonance. To avoid the over current, it is necessary to predict frequency characteristics of resonance. In this paper, a new prediction method is proposed. Firstly the line model, in which frequency characteristics of line inductance and resistance are taken account, are approximated by R-L parallel circuits. And then, using eigen value and eigenvector, the problem is decomposed to each eigen mode problem. Moreover, to get a bird's-eye view of phenomenon, a variable separate type approximate is introduced. Finally a new index matrix, which gives the distribution of over current, is introduced.
Application of higher harmonic control to hingeless rotor systems
Nguyen, Khanh; Chopra, Inderjit
1990-01-01
A comprehensive analytical formulation has been dveloped to predict the vibratory hub loads of a helicopter rotor system in forward flight. The analysis is used to calculate the optimal higher harmonic control inputs and associated actuator power required to minimize these hub loads. The present formulation is based on a finite element method in space and time. A nonlinear time domain, unsteady aerodynamic model is used to obtain the airloads, and the rotor induced inflow is calculated using a nonuniform inflow model. Predicted vibratory hub loads are correlated with experimental data obtained from a scaled model rotor. Results of a parametric study on a hingeless rotor show that blade flap, lag and torsion vibration characteristics, offset of blade center of mass from elastic axis, offset of elastic axis from quarter-chord axis, and blade thrust greatly affect the higher harmonic control actuator power requirement.
Silicon photonic crystal cavity enhanced second-harmonic generation from monolayer WSe2
Fryett, Taylor K; Zheng, Jiajiu; Liu, Chang-Hua; Xu, Xiaodong; Majumdar, Arka
2016-01-01
Nano-resonator integrated with two-dimensional materials (e.g. transition metal dichalcogenides) have recently emerged as a promising nano-optoelectronic platform. Here we demonstrate resonatorenhanced second-harmonic generation (SHG) in tungsten diselenide using a silicon photonic crystal cavity. By pumping the device with the ultrafast laser pulses near the cavity mode at the telecommunication wavelength, we observe a near visible SHG with a narrow linewidth and near unity linear polarization, originated from the coupling of the pump photon to the cavity mode. The observed SHG is enhanced by factor of ~200 compared to a bare monolayer on silicon. Our results imply the efficacy of cavity integrated monolayer materials for nonlinear optics and the potential of building a silicon-compatible second-order nonlinear integrated photonic platform.
Zhang, P; Jones, R M; Shinton, I R R; Flisgen, T; Glock, H W
2012-01-01
We investigate the feasibility of beam position diagnostics using Higher Order Mode (HOM) signals excited by an electron beam in the third harmonic 3.9 GHz superconducting accelerating cavities at FLASH. After careful theoretical and experimental assessment of the HOM spectrum, three modal choices have been narrowed down to fulfill different diagnostics requirements. These are localized dipole beam-pipe modes, trapped cavity modes from the fifth dipole band and propagating modes from the first two dipole bands. These modes are treated with various data analysis techniques: modal identification, direct linear regression (DLR) and singular value decomposition (SVD). Promising options for beam diagnostics are found from all three modal choices. This constitutes the first prediction, subsequently confirmed by experiments, of trapped HOMs in third harmonic cavities, and also the first direct comparison of DLR and SVD in the analysis of HOM-based beam diagnostics.
Simulation of electromagnetic scattering through the E-XFEL third harmonic cavity module
Joshi, N.Y; Shiliang, L; Baboi, N
2017-01-01
The European XFEL (E-XFEL) is being fabricated in Hamburg to serve as an X-ray Free Electron Laser light source. The electron beam will be accelerated through linacs consisting of 1.3GHz superconducting cavities along a length of 2.1km. In addition, third harmonic cavities will improve the quality of the beam by line arising the ﬁeld proﬁle and hence reducing the energy spread. There are eight 3.9GHz cavities within a single module AH1 of E-XFEL. The beam-excited electromagnetic(EM) ﬁeld in these cavities can be decomposed into a series of eigenmodes. These modes are, in general, not cut-oﬀ between one cavity and the next, as they are able to couple to each other through out the module. Here for the ﬁrst time, we evaluate components of the scattering matrix for module AH1. This is a computation ally expensive system, and hence we employ a Generalized Scattering Matrix(GSM)technique to allow rapid computation with reduced memory requirements. Veriﬁcation is provided on reduced structures, which are...
Energy Technology Data Exchange (ETDEWEB)
Li, Y. M. [Peking University, Beijing (China); Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Liu, Kexin [Peking University, Beijing (China); Geng, Rongli [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
2014-02-01
Multipacting (MP) in higher-order-mode (HOM) couplers of the International Linear Collider (ILC) baseline cavity and the Continuous Electron Beam Accelerator Facility (CEBAF) 12 GeV upgrade cavity is studied by using the ACE3P suites, developed by the Advanced Computations Department at SLAC. For the ILC cavity HOM coupler, the simulation results show that resonant trajectories exist in three zones, corresponding to an accelerating gradient range of 0.6-1.6 MV/m, 21-34 MV/m, 32-35 MV/m, and > 40MV/m, respectively. For the CEBAF 12 GeV upgrade cavity HOM coupler, resonant trajectories exist in one zone, corresponding to an accelerating gradient range of 6-13 MV/m. Potential implications of these MP barriers are discussed in the context of future high energy pulsed as well as medium energy continuous wave (CW) accelerators based on superconducting radio frequency cavities. Frequency scaling of MP's predicted in HOM couplers of the ILC, CBEAF upgrade, SNS and FLASH third harmonic cavity is given and found to be in good agreement with the analytical result based on the parallel plate model.
In vivo optical virtual biopsy of human oral cavity with harmonic generation microscopy
Tsai, M.-R.; Chen, S.-Y.; Shieh, D.-B.; Lou, P.-J.; Sun, C.-K.
2010-02-01
Oral cancer ranked number four in both cancer incident and mortality in Taiwanese male population. Early disease diagnosis and staging is essential for its clinical success. However, most patients were diagnosed in their late disease stage as ideal prescreening procedures are yet to be developed especially when dealing with a large surface of precancerous lesions. Therefore, how to detect and confirm the diagnosis of these early stage lesions are of significant clinical value. Harmonic generation process naturally occurred in biological molecules and requires no energy deposition to the target molecule. Thus harmonic generation microscopy (HGM) could potentially serve as a noninvasive tool for screening of human oral mucosal diseases. The in vivo optical biopsy of human oral cavity with HGM could be achieved with high spatial resolution to resolve dynamic physiological process in the oral mucosal tissue with equal or superior quality but devoid of complicated physical biopsy procedures. The second harmonic generation (SHG) provide significant image contrast for biomolecules with repetitive structures such as the collagen fibers in the lamina propria and the mitotic spindles in dividing cells. The cell morphology in the epithelial layer, blood vessels and blood cells flow through the capillaries can be revealed by third harmonic generation (THG) signals. Tissue transparent technology was used to increase the optical penetration of the tissue. In conclusion, this report demonstrates the first in vivo optical virtual biopsy of human oral mucosa using HGM and revealed a promising future for its clinical application for noninvasive in vivo diseases diagnosis.
A Massively Parallel Solver for the Mechanical Harmonic Analysis of Accelerator Cavities
Energy Technology Data Exchange (ETDEWEB)
Kononenko, O. [SLAC National Accelerator Lab., Menlo Park, CA (United States)
2015-02-17
ACE3P is a 3D massively parallel simulation suite that developed at SLAC National Accelerator Laboratory that can perform coupled electromagnetic, thermal and mechanical study. Effectively utilizing supercomputer resources, ACE3P has become a key simulation tool for particle accelerator R and D. A new frequency domain solver to perform mechanical harmonic response analysis of accelerator components is developed within the existing parallel framework. This solver is designed to determine the frequency response of the mechanical system to external harmonic excitations for time-efficient accurate analysis of the large-scale problems. Coupled with the ACE3P electromagnetic modules, this capability complements a set of multi-physics tools for a comprehensive study of microphonics in superconducting accelerating cavities in order to understand the RF response and feedback requirements for the operational reliability of a particle accelerator. (auth)
Accurate, explicit formulae for higher harmonic force spectroscopy by frequency modulation-AFM
Kfir Kuchuk; Uri Sivan
2015-01-01
Summary The nonlinear interaction between an AFM tip and a sample gives rise to oscillations of the cantilever at integral multiples (harmonics) of the fundamental resonance frequency. The higher order harmonics have long been recognized to hold invaluable information on short range interactions but their utilization has thus far been relatively limited due to theoretical and experimental complexities. In particular, existing approximations of the interaction force in terms of higher harmonic...
Calculation of asymptotic and RMS kicks due to higher order modes in the 3.9-GHz cavity
Energy Technology Data Exchange (ETDEWEB)
Bellantoni, L.; /Fermilab; Edwards, H.; /Fermilab /DESY; Wanzenberg, R.; /DESY
2008-03-01
FLASH plans to use a 'third harmonic' (3.9 GHz) superconducting cavity to compensate nonlinear distortions of the longitudinal phase space due to the sinusoidal curvature of the cavity voltage of the TESLA 1.3 GHz cavities. Higher order modes (HOMs) in the 3.9 GHz have a significant impact on the dynamics of the electron bunches in a long bunch train. Kicks due to dipole modes can be enhanced along the bunch train depending on the frequency and Q-value of the modes. The enhancement factor for a constant beam offset with respect to the cavity has been calculated. A simple Monte Carlo model of these effects, allowing for scatter in HOM frequencies due to manufacturing variances, has also been implemented and results for both FLASH and for an XFEL-like configuration are presented.
Accurate, explicit formulae for higher harmonic force spectroscopy by frequency modulation-AFM
Directory of Open Access Journals (Sweden)
Kfir Kuchuk
2015-01-01
Full Text Available The nonlinear interaction between an AFM tip and a sample gives rise to oscillations of the cantilever at integral multiples (harmonics of the fundamental resonance frequency. The higher order harmonics have long been recognized to hold invaluable information on short range interactions but their utilization has thus far been relatively limited due to theoretical and experimental complexities. In particular, existing approximations of the interaction force in terms of higher harmonic amplitudes generally require simultaneous measurements of multiple harmonics to achieve satisfactory accuracy. In the present letter we address the mathematical challenge and derive accurate, explicit formulae for both conservative and dissipative forces in terms of an arbitrary single harmonic. Additionally, we show that in frequency modulation-AFM (FM-AFM each harmonic carries complete information on the force, obviating the need for multi-harmonic analysis. Finally, we show that higher harmonics may indeed be used to reconstruct short range forces more accurately than the fundamental harmonic when the oscillation amplitude is small compared with the interaction range.
Accurate, explicit formulae for higher harmonic force spectroscopy by frequency modulation-AFM.
Kuchuk, Kfir; Sivan, Uri
2015-01-01
The nonlinear interaction between an AFM tip and a sample gives rise to oscillations of the cantilever at integral multiples (harmonics) of the fundamental resonance frequency. The higher order harmonics have long been recognized to hold invaluable information on short range interactions but their utilization has thus far been relatively limited due to theoretical and experimental complexities. In particular, existing approximations of the interaction force in terms of higher harmonic amplitudes generally require simultaneous measurements of multiple harmonics to achieve satisfactory accuracy. In the present letter we address the mathematical challenge and derive accurate, explicit formulae for both conservative and dissipative forces in terms of an arbitrary single harmonic. Additionally, we show that in frequency modulation-AFM (FM-AFM) each harmonic carries complete information on the force, obviating the need for multi-harmonic analysis. Finally, we show that higher harmonics may indeed be used to reconstruct short range forces more accurately than the fundamental harmonic when the oscillation amplitude is small compared with the interaction range.
Zhang, P; Jones, R M; Flisgen, T; Van Rienen, U; Shinton, I R R
2013-01-01
Higher order mode (HOM) beam position monitors (BPM) are being developed for the 3.9 GHz third harmonic superconducting accelerating cavities at FLASH. The transverse beam position in a cavity can be determined utilizing beam-excited HOMs based on dipole components. The existing couplers used for HOM suppression provide necessary signals. The diagnostics principle is similar to a cavity BPM, but requires no additional vacuum instruments on the linac. The challenges of HOM-BPM for 3.9 GHz cavities lie in the dense HOM spectrum arising from the coupling of the majority HOMs amongst the four cavities in the cryo-module ACC39. HOMs with particularly promising diagnostics features were evaluated using a spectrum analyzer and custom-built test electronics with various data analysis techniques, data reduction was focused on. After careful theoretical and experimental assessment of the HOM spectrum, multi-cavity modes in the region of 5 GHz were chosen to provide a global position over the complete module with superi...
Generation of higher order Gauss-Laguerre modes in single-pass 2nd harmonic generation
DEFF Research Database (Denmark)
Buchhave, Preben; Tidemand-Lichtenberg, Peter
2008-01-01
We present a realistic method for dynamic simulation of the development of higher order modes in second harmonic generation. The deformation of the wave fronts due to the nonlinear interaction is expressed by expansion in higher order Gauss-Laguerre modes....
Energy Technology Data Exchange (ETDEWEB)
Tripodi, P.; Di Gioacchino, D.; Celani, F.; Spallone, A. [INFN, Frascati (Italy). Laboratori Nazionali di Frascati; Shi, D. [Rhodes Hall, Univ. of Cincinnati (United States). Dept. of Material Science and Eng.
1997-03-01
They measured the first and higher components of ac susceptibilities of melted YBCO samples before and after hydrogenation by {mu}s pulsed electrolysis. First component was measured versus temperature at fixed frequency while higher harmonics were measured versus frequencies at fixed temperature near critical temperature. All measurements were performed at fixed amplitude of ac magnetic field and zero dc magnetic field. The frequency and temperature behaviour of the harmonic components before and after hydrogenation gave us information on possible dynamic losses in comparison to the flux pinning mechanism.
Effect of localized microstructural evolution on higher harmonic generation of guided wave modes
Choi, Gloria; Liu, Yang; Yao, Xiaochu; Lissenden, Cliff J.
2015-03-01
Higher harmonic generation of ultrasonic waves has the potential to be used to detect precursors to macroscale damage of phenomenon like fatigue due to microstructural evolution contributing to nonlinear material behavior. Aluminum plates having various plastic zone sizes were plastically deformed to different levels. The fundamental shear horizontal mode was then generated in the plate samples via a magnetostrictive transducer. After propagating through the plastic zone the primary wave mode (SH0) and its third harmonic (sh0) were received by a second transducer. Results of a parallel numerical study using the S1-s2 Lamb mode pair, where sensitivity to changes in third order elastic constants were investigated, are described within the context of the experimental results. Specimens used within both studies are geometrically similar and have double edge notches for dog bone samples that introduce localized plastic deformation. Through both studies, the size of the plastic zone with respect to the propagation distance and damage intensity influence the higher harmonics.
Energy Technology Data Exchange (ETDEWEB)
Goldstein, J.C.; Warren, R.W.; Newnam, B.E.
1990-01-01
We study, using numerical simulation methods, the design requirements for the electron beam, wiggler, and optical resonator of an extreme-ultraviolet (XUV, 100 nm {ge} {lambda} {ge} 10 nm) free-electron laser oscillator operating on a higher harmonic. Our previous theoretical studies of an XUV FEL oscillator have assumed operation at the fundamental wavelength. Higher harmonic operation is attractive because the energy of the electrons can be reduced, thus reducing the cost of the linac. A further reduction in beam energy is possible with the use of short-period wigglers: in the present work, we use the expected properties of pulsed-wire wigglers. Operation of an FEL oscillator on the third harmonic has been experimentally demonstrated at Stanford University and Los Alamos, and this mode of operation may also be both possible and desirable for an XUV device. 12 refs., 2 tabs.
Higher Harmonics Resonance Suppression in Distribution System using with Damping Resistance
Sugawara, Takabumi; Naitoh, Tadashi; Takeda, Keiki; Toyama, Atsushi
There are many PWM control apparatuses, which are higher harmonics current sources, in distribution systems. And higher harmonics causes over current by parallel resonance. To avoid the over current, it is necessary to suppress the resonance. In this paper, a new suppression method, which inserts a damping resistance in resonance circuit, is proposed. Firstly using the participation factor of state equation and condenser capacitance, the condenser current is defined. And, the damping resistance position becomes the maximum current condenser. Then, to determine the damping resistance value, a natural frequency characteristic to current amplification degree is introduced using with eigen value. Finally, adopting numerical examination, it is known that the damping resistance is effective in any case. Moreover, the hybrid method of the damping resistance and the optimal harmonic source point method is more effective in multi resonance circuits problem.
Measurement of mixed higher order flow harmonics in PbPb collisions
CMS Collaboration
2017-01-01
The mixed higher order flow harmonics and nonlinear response coefficients of charged particles are measured for the first time as a function of $p_{\\rm{T}}$ and centrality in PbPb collisions at $\\sqrt{s_{NN}} = 2.76~\\mathrm{TeV}$ and $5.02~\\mathrm{TeV}$ with the CMS detector. The results are obtained using the scalar product method, and cover a $p_{\\rm{T}}$ range from $0.3~\\mathrm{GeV}/c$ to $8.0~\\mathrm{GeV}/c$, pseudorapidity $|\\eta| < 2.4$, and a centrality range of $0-60\\%$. At $5.02~\\mathrm{TeV}$, results for mixed harmonics are compared to the matching higher order flow harmonics from two-particle correlations, which measure $v_n$ values with respect to the $n$-th order event plane. It is observed that the nonlinear response coefficients of the odd harmonics are larger than the even harmonics ones. The results are compared with hydrodynamic predictions with different shear viscosity to entropy density ratios and different initial conditions.
Nazhan, Salam; Ghassemlooy, Zabih; Busawon, Krishna
2016-04-01
In this paper, selective optical feedback is used to investigate the nonlinearity behaviours of a vertical cavity surface emitting laser (VCSEL) with the modulation signal. A single mode VCSEL with both parallel and orthogonal optical feedback (OF) signals modulated at 1 MHz frequency over a range of modulation depth is investigated. We also investigate the nonlinear characteristics of the orthogonal polarization modes XP and YP of the VCSEL by changing the injection current and temperature. The results show an enhancement in the harmonic distortions (HDs) of both XP and YP modes with parallel OF, and the total suppression of HDs with orthogonal OF. We show that for the VCSEL with orthogonal OF, the second and third harmonic components of the XP and YP modes decrease and reach the noise floor level of the output power spectrum. Additionally, peaks of second and third harmonic components change radically when varying the bias current and temperature. The results reveal that orthogonal OF can be employed as a new tool to improve the linear dynamic range and to control the nonlinear characteristics of the VCSEL, thus making these devices a promising optical source in present and future optical communication applications.
Higher harmonics of azimuthal anisotropy in relativistic heavy ion collisions in HYDJET++ model
Bravina, L V; Eyyubova, G. Kh.; Korotkikh, V.L.; Lokhtin, I.P.; Malinina, L.V.; Petrushanko, S.V.; Snigirev, A.M.; Zabrodin, E.E.
2014-01-01
The LHC data on azimuthal anisotropy harmonics from PbPb collisions at center-of-mass energy 2.76 TeV per nucleon pair are analyzed and interpreted in the framework of the HYDJET++ model. The cross-talk of elliptic $v_2$ and triangular $v_3$ flow in the model generates both even and odd harmonics of higher order. Comparison with the experimental data shows that this mechanism is able to reproduce the $p_{\\rm T}$ and centrality dependencies of quadrangular flow $v_4$, and also the basic trends for pentagonal $v_5$ and hexagonal $v_6$ flows.
Application of higher harmonic blade feathering on the OH-6A helicopter for vibration reduction
Straub, F. K.; Byrns, E. V., Jr.
1986-01-01
The design, implementation, and flight test results of higher harmonic blade feathering for vibration reduction on the OH-6A helicopter are described. The higher harmonic control (HHC) system superimposes fourth harmonic inputs upon the stationary swashplate. These inputs are transformed into 3P, 4P and 5P blade feathering angles. This results in modified blade loads and reduced fuselage vibrations. The primary elements of this adaptive vibration suppression system are: (1) acceleration transducers sensing the vibratory response of the fuselage; (2) a higher harmonic blade pitch actuator system; (3) a flightworthy microcomputer, incorporating the algorithm for reducing vibrations, and (4) a signal conditioning system, interfacing between the sensors, the microcomputer and the HHC actuators. The program consisted of three distinct phases. First, the HHC system was designed and implemented on the MDHC OH-6A helicopter. Then, the open loop, or manual controlled, flight tests were performed, and finally, the closed loop adaptive control system was tested. In 1983, one portion of the closed loop testing was performed, and in 1984, additional closed loop tests were conducted with improved software. With the HHC system engaged, the 4P pilot seat vibration levels were significantly lower than the baseline ON-6A levels. Moreover, the system did not adversely affect blade loads or helicopter performance. In conclusion, this successful proof of concept project demonstrated HHC to be a viable vibration suppression mechanism.
Higher Order Mode (HOM) Impedance and Damping Study for the LHC Capture Cavity
Linnecar, Trevor Paul R; Tückmantel, Joachim; CERN. Geneva. SPS and LHC Division
2001-01-01
To investigate the higher order mode, HOM, damping in the LHC 200MHz ACN cavity when using four HOM couplers, simulations have been done by both 3-D frequency domain and time domain methods. These simulations have previously been used in other studies of HOM damped cavities and shown to be effective by comparing measurement and simulation results[1] [2]. Using these methods the impedance spectrum of the HOM modes in the cavity before and after damping has been obtained. From this, detailed information about the HOM coupler's contribution to HOM damping can be obtained. The distribution and magnitude of some potentially dangerous HOM modes in the ACN cavity have been found.
Higher-order harmonics coupling in different free-electron laser codes
Giannessi, L.; Freund, H. P.; Musumeci, P.; Reiche, S.
2008-08-01
The capability for simulation of the dynamics of a free-electron laser including the higher-order harmonics in linear undulators exists in several existing codes as MEDUSA [H.P. Freund, S.G. Biedron, and S.V. Milton, IEEE J. Quantum Electron. 27 (2000) 243; H.P. Freund, Phys. Rev. ST-AB 8 (2005) 110701] and PERSEO [L. Giannessi, Overview of Perseo, a system for simulating FEL dynamics in Mathcad, , in: Proceedings of FEL 2006 Conference, BESSY, Berlin, Germany, 2006, p. 91], and has been recently implemented in GENESIS 1.3 [See ]. MEDUSA and GENESIS also include the dynamics of even harmonics induced by the coupling through the betatron motion. In addition MEDUSA, which is based on a non-wiggler averaged model, is capable of simulating the generation of even harmonics in the transversally cold beam regime, i.e. when the even harmonic coupling arises from non-linear effects associated with longitudinal particle dynamics and not to a finite beam emittance. In this paper a comparison between the predictions of the codes in different conditions is given.
Compendium of eigenmodes in third harmonic cavities for FLASH and the XFEL
Energy Technology Data Exchange (ETDEWEB)
Shinton, Ian Reginald Roy; Juntong, Nawin [Cockcroft Institute, Warrington, Cheshire (United Kingdom); Manchester Univ. (United Kingdom)
2012-04-15
The resonant modes in the 9-cell 3.9 GHz bunch shaping cavity designed by FERMILAB in collaboration with DESY and installed in FLASH at DESY were calculated up to the range of 10 GHz in terms of the band structure of this design. The modal nature of this structure has previously been investigated by various parties. We have extended this work to include a modal pictorial dictionary in which the nature of the modes can be readily identified as well as the R/Q's for each of the modes. Below 10 GHz only monopole, dipole, quadrupole and sextupole bands exist for this particular structure. Herein we only consider the modal patterns of the bands themselves and have not included the beampipe modes in the pictorial dictionary. In addition to the finite element simulations we also utilise a capacitive-inductive circuit model to achieve a rapid characterisation of the cavity. (orig.)
Higher harmonic emission by a relativistic electron beam in a longitudinal magnetic wiggler
Davidson, Ronald C.; McMullin, Wayne A.
1982-10-01
The classical limit of the Einstein-coefficient method is used in the low-gain regime to calculate the stimulated emission from a tenuous relativistic electron beam propagating in the combined solenoidal and longitudinal wiggler fields (B0+δB k0z)e^z produced near the axis of a multiple-mirror (undulator) field configuration. Emission is found to occur at all harmonics of the wiggler wave number k0 with Doppler upshifted output frequency given by ω=(lk0Vb+ωcb)(1+Vbc)γ2b(1+γ2bV2⊥c2), where l>=1. The emission is compared to the low-gain cyclotron maser with δB=0 and to the low-gain free-electron laser (operating at higher harmonics) utilizing a transverse linearly polarized wiggler field.
Jasbeer, Hadiya; Williams, Robert J; Kitzler, Ondrej; McKay, Aaron; Mildren, Richard P
2018-01-22
We report a high power quasi-continuous-wave (QCW) 620 nm laser from an external cavity diamond Raman laser utilizing intracavity frequency doubling in lithium triborate. Output power of 30 W for durations of 0.25 ms at 15% conversion efficiency was achieved with a beam quality factor M2 = 1.1 from a free-running Nd:YAG pump laser of M2 = 1.5. The critical design parameters that affect conversion efficiency and power were analysed with the aid of an analytical model. By adaptation to other pump technologies, the diamond approach provides a novel pathway towards high brightness CW beam generation in the visible and ultraviolet regions.
Woldegiorgis, Emnet Tadesse
2013-01-01
There have been various higher education policy reforms at regional level to overcome the challenges and impacts of globalization in the current knowledge based global economy. Universities have already been involved in various internationalization processes establishing both bilateral and multilateral cooperations across borders. Through various…
Higher order modes HOMs in coupled cavities of the FLASH module ACC39
Shinton, I R R; Li, Z; Zhang, P
2011-01-01
We analyse the higher order modes (HOM’s) in the 3.9GHz bunch shaping cavities installed in the FLASH facility at DESY. A suite of finite element computer codes (including HFSS and ACE3P) and globalised scattering matrix calculations (GSM) are used to investigate the modes in these cavities. This study is primarily focused on the dipole component of the multiband expansion of the wakefield, with the emphasis being on the development of a HOM-based BPM system for ACC39. Coupled inter-cavity modes are simulated together with a limited band of trapped modes.
AUTHOR|(CDS)2075492; Buzio, Marco; Köster, Oliver; Russenschuck, Stephan; Severino, Giordana
2016-01-01
A method is proposed for calibrating the radius of a rotating coil sensor by relaxing the metrological constraints on alignment and field errors of the reference quadrupole. A coil radius calibration considering a roll-angle misalignment of the measurement bench, the magnet, and the motor-drive unit is analyzed. Then, the error arising from higher-order harmonic field imperfections in the reference quadrupole is assessed. The method is validated by numerical field computation for both the higher-order harmonic errors and the roll-angle misalignment. Finally, an experimental proof-of-principle demonstration is car-ried out in a calibration magnet with sextupole harmonic.
Mozart K.448 and epileptiform discharges: effect of ratio of lower to higher harmonics.
Lin, Lung-Chang; Lee, Wei-Te; Wu, Hui-Chuan; Tsai, Chin-Lin; Wei, Ruey-Chang; Jong, Yuh-Jyh; Yang, Rei-Cheng
2010-05-01
Certain music has been shown to improve mental function, leading to what is known as the Mozart effect. This study measured the impact of Mozart's Sonata for two pianos in D major, K.448, on different epileptic foci of epileptiform discharge in Taiwanese children (n=58) with seizure disorders and investigated the characteristics of the musical stimulus presented that resulted in epileptiform discharge reduction. We examined the relationship between the number of discharges with the foci of epileptiform discharge (n=6), sleep state, gender, and mentality. A continuous electroencephalogram was recorded before, during and after exposure to Mozart's Sonata for two pianos in D major, K.448 (piano K.448), and the frequencies of discharges were compared. The study was repeated a week later using digitally computerized string version of the same musical stimulus (string K.448), in patients who responded to piano K.448 with the largest reduction in interictal discharges (n=11). Interictal discharges were reduced in most (81.0%) patients and varied greatly (33.10+/-28.33%) as they listened to the piano K.448 (more fundamental tones and lower harmonics). Patients with generalized or central discharge showed the most improvement. In most patients (76.1%), the decrease in epileptiform discharges continued after the music ended. The state of wakefulness, gender and mentality did not affect the results. Although the string K.448 had a larger number of higher harmonics in the spectrogram analysis, the discharges were not reduced at all when listening to this music. These results suggest that listening to Mozart K.448 for two pianos reduced epileptiform discharges in children with epilepsy. This study suggests that it is possible to reduce the number of epileptiform discharges in some patients by optimizing the fundamental tones and minimizing the higher frequency harmonics. Copyright 2010 Elsevier B.V. All rights reserved.
The Higher-Order Mode Dampers of the 400 MHz Superconducting LHC Cavities
Häbel, E; Gerigk, F; Zhao, Z T
1997-01-01
The accelerating system of the LHC consists of two structures per beam, each composed of four superconducting single-cell cavities. Their higher-order modes have to be damped sufficiently in order to prevent coupled-bunch instabilities and to limit parasitic mode losses. The first two higher-order modes do not propagate into the beam tubes between the cells. However, strong damping can be obtained with a special dipole mode coupler resonant at both modes. Because of the restricted space, a compact design is used. The other higher-order modes propagate and form coupled modes with unequal field distributions. They are damped by broadband couplers positioned on either side of each cavity cell. We present the design of the higher-order mode couplers together with measurements on a real cavity.
Løkberg, O J; Pedersen, H M; Valø, H; Wang, G
1994-08-01
We separately measure the higher harmonics vibration patterns of a periodic vibrating object by using time-average TV holography and phase modulation. During measurements the frequency of the phase modulation is adjusted to each harmonic component while the excitation of the object is set low enough to record all components on the linear part of the fringe function. Using acoustical phase stepping and calibration of the fringe function, we compute the amplitude and phase distributions of the frequency component. We measure components up to the 65th harmonic by using square-wave excitation.
Azimuthal correlations and mixed higher order flow harmonics from CMS at the LHC
Stojanovic, Milan
2017-01-01
Two-particle correlations measurements of $v_{n}$ (n=2-4) in 8.16 TeV pPb collisions, and event-by-event correlations of different $v_{n}$ measured using symmetric cumulants in 13 TeV pp, 5.02 and 8.16TeV pPb and 5.02 TeV PbPb collisions at the LHC. These new results give important insights to the origin of collectivity observed in small collision systems. Additionally, using the scalar product method and the method of two-particle correlations, the mixed higher order flow harmonics and extracted nonlinear response coefficients of charged particles are measured for the first time as a function of $p_{T}$ and centrality in 2.76 and 5.02 TeV PbPb collisions. The obtained results are compared with different theoretical predictions.
Effects of higher harmonic control on rotor performance and control loads
Nguyen, Khanh; Chopra, Inderjit
1990-01-01
An analytical study, based on an advanced Higher Harmonic Control (HHC) analysis for helicopter rotor systems, is carried out to investigate HHC application for rotor performance enhancement. The effects of HHC on stall characteristics of rotor and blade pitch-link loads when the system is configured to suppress vibration are also examined. For vibration control, simulated results indicate that HHC may promote early blade stall. Effects of blade torsion frequencies on HHC performance are moderate, and torsionally stiff blades require less actuator power than torsionally soft blades. For rotor performance improvement, a 3 to 5 percent reduction in rotor shaft power can be achieved with 2 deg of two-per-rev blade pitch control.
Kobayashi, T.; Ida, K.; Inagaki, S.; Tsuchiya, H.; Tamura, N.; Choe, G. H.; Yun, G. S.; Park, H. K.; Ko, W. H.; Evans, T. E.; Austin, M. E.; Shafer, M. W.; Ono, M.; López-bruna, D.; Ochando, M. A.; Estrada, T.; Hidalgo, C.; Moon, C.; Igami, H.; Yoshimura, Y.; Tsujimura, T. Ii.; Itoh, S.-I.; Itoh, K.
2017-07-01
In this contribution we analyze modulation electron cyclotron resonance heating (MECH) experiment and discuss higher harmonic frequency dependence of transport coefficients. We use the bidirectional heat pulse propagation method, in which both inward propagating heat pulse and outward propagating heat pulse are analyzed at a radial range, in order to distinguish frequency dependence of transport coefficients due to hysteresis from that due to other reasons, such as radially dependent transport coefficients, a finite damping term, or boundary effects. The method is applied to MECH experiments performed in various helical and tokamak devices, i.e. Large Helical Device (LHD), TJ-II, Korea Superconducting Tokamak Advanced Research (KSTAR), and Doublet III-D (DIII-D) with different plasma conditions. The frequency dependence of transport coefficients are clearly observed, showing a possibility of existence of transport hysteresis in flux-gradient relation.
Xiao, B P; Ben-Zv, I; Burt, Graeme Campbell; Calaga, Rama; Capatina, Ofelia; Hall, B; Jones, T; Skaritka, J; Verdú-Andrés, S; Wu, Q
2015-01-01
A Double Quarter Wave Crab Cavity (DQWCC) was designed for the Large Hadron Collider (LHC) luminosity upgrade. A compact Higher Order Mode (HOM) filter with wide stop band at the deflecting mode is developed for this cavity. Multi-physics finite element simulation results are presented. The integration of this design to the cavity cryomodule is described.
Directory of Open Access Journals (Sweden)
Hasanova L. H.
2017-12-01
Full Text Available Nowadays permanent magnet synchronous machines those frequency-controlled from stator side with frequency inverters made on the basis of power transistors or fully controlled thyristors, are widely used as motors and generators. In future they are also promising a good application in transport, including marine. Modern frequency inverters are equipped with a control system based on sine-shaped pulse width modulation. While shaping the voltage in the output of the inverter, in addition to the fundamental harmonic, higher harmonic components are also included in the voltage shape, which certainly affect the operating parameters of the generator (electromagnetic torque, power, currents. To determine this effect the modeling and investigation technique of higher harmonic voltages in the "electric network – frequency converter – synchronous machine with permanent magnets" system has been developed. The proposed equations of a frequency-controlled permanent magnet synchronous machine allow relatively simply reproduce the harmonic composition of the voltage in the output of a frequency inverter equipped with the control system based on a sinusoidal pulse width modulation. The developed research technique can be used for inverters with any number and composition of voltage harmonic components feeding a stator winding of a permanent magnet synchronous machine. On a particular case, the efficiency of the research technique of the higher harmonics influence on the operating parameters of the generator has been demonstrated. At the same time, the study has been carried out taking into account the shape of the voltage curve feeding the windings of the synchronous machine containing in addition to the fundamental harmonic the 8, 10, 11, 13, 14 and 16-th harmonic components, and the rated active power of the synchronous machine has been equal to 1 500 kW.
Higher harmonic control analysis for vibration reduction of helicopter rotor systems
Nguyen, Khanh Q.
1994-01-01
An advanced higher harmonic control (HHC) analysis has been developed and applied to investigate its effect on vibration reduction levels, blade and control system fatigue loads, rotor performance, and power requirements of servo-actuators. The analysis is based on a finite element method in space and time. A nonlinear time domain unsteady aerodynamic model, based on the indicial response formulation, is used to calculate the airloads. The rotor induced inflow is computed using a free wake model. The vehicle trim controls and blade steady responses are solved as one coupled solution using a modified Newton method. A linear frequency-domain quasi-steady transfer matrix is used to relate the harmonics of the vibratory hub loads to the harmonics of the HHC inputs. Optimal HHC is calculated from the minimization of the vibratory hub loads expressed in term of a quadratic performance index. Predicted vibratory hub shears are correlated with wind tunnel data. The fixed-gain HHC controller suppresses completely the vibratory hub shears for most of steady or quasi-steady flight conditions. HHC actuator amplitudes and power increase significantly at high forward speeds (above 100 knots). Due to the applied HHC, the blade torsional stresses and control loads are increased substantially. For flight conditions where the blades are stalled considerably, the HHC input-output model is quite nonlinear. For such cases, the adaptive-gain controller is effective in suppressing vibratory hub loads, even though HHC may actually increase stall areas on the rotor disk. The fixed-gain controller performs poorly for such flight conditions. Comparison study of different rotor systems indicates that a soft-inplane hingeless rotor requires less actuator power at high speeds (above 130 knots) than an articulated rotor, and a stiff-inplane hingeless rotor generally requires more actuator power than an articulated or a soft-inplane hingeless rotor. Parametric studies for a hingeless rotor
Double Quarter Wave Crab Cavity Field Profile Analysis and Higher Order Mode Characterization
Energy Technology Data Exchange (ETDEWEB)
Marques, Carlos [Brookhaven National Lab. (BNL), Upton, NY (United States). Accelerator R and D Div.; Stony Brook Univ., NY (United States). Physics and Astronomy Dept.; Xiao, B. P. [Brookhaven National Lab. (BNL), Upton, NY (United States). Accelerator R and D Div.; Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Accelerator R and D Div.; Stony Brook Univ., NY (United States). Physics and Astronomy Dept.
2014-06-01
The Large Hadron Collider (LHC) is underway for a major upgrade to increase its luminosity by an order of magnitude beyond its original design specifications. This novel machine configuration known as the High Luminosity LHC (HL-LHC) will rely on various innovative technologies including very compact and ultra-precise superconducting crab cavities for beam rotation. A double quarter wave crab cavity (DQWCC) has been designed at Brookhaven National Laboratory for the HL-LHC. This cavity as well as the structural support components were fabricated and assembled at Niowave. The field profile of the crabbing mode for the DQWCC was investigated using a phase shift bead pulling technique and compared with simulated results to ensure proper operation or discover discrepancies from modeled results and/or variation in fabrication tolerances. Higher-Order Mode (HOM) characterization was also performed and correlated with simulations.
Emittance growth, debunching and integrated luminosity in the LHC with a higher harmonic RF system
Mertens, T
2011-01-01
Beam dynamics with a double RF system has been considered in several references. Recently the idea of adding a secondary RF system has resurfaced due to heating effects in the beam screens of the LHC that are caused by the high particle densities in the bunch centres with a Gaussian longitudinal profile. It is well known that one can change the longitudinal bunch profile from a Gaussian profile like the pink curve in Figure 1 into a plateau shape like the blue curve in Figure 1 reducing the particle density in the bunch centres. Here we study the evolution of a bunch with such a longitudinal plateau like shape under the influence of IBS in a double RF system and how adding a secondary RF system in the LHC influences debunching losses and integrated luminosity. The simulations presented here are done with the particle tracking code that was used to study IBS effects in the 2010 ion fills. The results of our simulations indicate that installing a secondary higher harmonic RF system in the LHC would significantl...
Higher harmonic anisotropic flow of identified particles in Pb-Pb collisions with the ALICE detector
INSPIRE-00416653
2016-01-01
Anisotropic flow plays a crucial role in establishing the equation of state of the Quark Gluon Plasma. The results at RHIC and LHC have demonstrated that the matter created in heavy-ion collisions behaves as a nearly perfect fluid reflected in the low value of the shear viscosity over entropy density ratio ($\\eta/s$). The higher flow harmonics are particularly sensitive to the value of $\\eta/s$ in hydrodynamic calculations. In this analysis, we present the first ALICE results on the $p_{\\mathrm{T}}$ differential $v_{2}$, $v_{3}$ and $v_{4}$ for $\\pi^{\\pm}$, $\\mathrm{K}^{\\pm}$, p($\\bar p$) from the high statistics 2011 heavy-ion run. We investigate how these $v_{n}$ coefficients evolve with particle mass and centrality for the 0--1\\% and 20--30\\% centrality ranges. These new measurements aim at differentiating between models that use different initial conditions, constraining further the value of $\\eta/s$ and allowing to decouple the influence of the late hadronic stage from the hydrodynamic evolution of the s...
Marx-Glowna, Berit; Schulze, Kai S; Uschmann, Ingo; Kämpfer, Tino; Weber, Günter; Hahn, Christoph; Wille, Hans Christian; Schlage, Kai; Röhlsberger, Ralf; Förster, Eckhart; Stöhlker, Thomas; Paulus, Gerhard G
2015-09-01
The spectrum of the undulator radiation of beamline P01 at Petra III has been measured after passing a multiple reflection channel-cut polarimeter. Odd and even harmonics up to the 15th order, as well as Compton peaks which were produced by the high harmonics in the spectrum, could been measured. These additional contributions can have a tremendous influence on the performance of the polarimeter and have to be taken into account for further polarimeter designs.
Chen, Chiun-Fan; Bikson, Marom; Chou, Li-Wei; Shan, Chunlei; Khadka, Niranjan; Chen, Wen-Shiang; Fregni, Felipe
2017-03-03
It is well established that electrical-stimulation frequency is crucial to determining the scale of induced neuromodulation, particularly when attempting to modulate corticospinal excitability. However, the modulatory effects of stimulation frequency are not only determined by its absolute value but also by other parameters such as power at harmonics. The stimulus pulse shape further influences parameters such as excitation threshold and fiber selectivity. The explicit role of the power in these harmonics in determining the outcome of stimulation has not previously been analyzed. In this study, we adopted an animal model of peripheral electrical stimulation that includes an amplitude-adapted pulse train which induces force enhancements with a corticospinal contribution. We report that the electrical-stimulation-induced force enhancements were correlated with the amplitude of stimulation power harmonics during the amplitude-adapted pulse train. In an exploratory analysis, different levels of correlation were observed between force enhancement and power harmonics of 20-80 Hz (r = 0.4247, p = 0.0243), 100-180 Hz (r = 0.5894, p = 0.0001), 200-280 Hz (r = 0.7002, p power harmonics. This is a pilot, but important first demonstration that power at high order harmonics in the frequency spectrum of electrical stimulation pulses may contribute to neuromodulation, thus warrant explicit attention in therapy design and analysis.
Combining Cavity for RF Power Sources Higher Power Testing and Further Simulation
Wooldridge, Emma; Rogers, James H P
2005-01-01
A combining cavity for RF power sources has been investigated previously reported in EPAC'04 using computer simulations in CSTs' Microwave Studio© and by building a low power model out of aluminium. The model has now been tested at higher power in a number different configurations and compared with earlier results. This paper discusses the results of the higher power test and options for a combiner that can be used at the high power required for particle accelerators. It discusses further design and future modelling.
Two-Photon Ionization of He through a Superposition of Higher Harmonics.
Papadogiannis, N A; Nikolopoulos, L A A; Charalambidis, D; Tsakiris, G D; Tzallas, P; Witte, K
2003-04-04
We present experimental results and theoretical analysis of two-photon ionization of He by a superposition of the 7th to the 13th harmonic of a Ti:sapphire laser. Solving the time-dependent Schrödinger equation for He in a coherent polychromatic field, the He+ yield is calculated. From this yield the number of He+ ions produced has been estimated and found in reasonable agreement with its measured value. The present results establish the feasibility of a second-order autocorrelation measurement of superposition of harmonics, and thus they represent the precursor towards the direct temporal characterization of attosecond pulse trains.
Vinokurova, T. Yu.; Dobryagina, O. A.; Shagurina, E. S.; Shuin, V. A.
2015-01-01
Protections based by higher harmonics absolute measurements the zero sequence currents of the protected object connections against single-phase earth faults in resonant grounded cable networks of medium voltage industrial and urban energy supply systems have been widely applied in Russia since the late 60s of the 20th century. However, some operational problems connected with sufficient selectivity and sensitivity of these protection devices appeared with time. Sensitivity and selectivity of ...
Khripunov, Sergey; Radnatarov, Daba; Kobtsev, Sergey; Skorkin, Aleksey
2014-03-24
This work for the first time proposes and studies a method of frequency doubling of CW non-single-frequency fibre lasers with a high-Q resonator partially coupled to the fibre laser cavity. The proposed new approach resulted in the following parameters: laser's maximal output power 880 mW at 536 nm when pumped with 6.2 W at 976 nm, wavelength tuneability range 521-545 nm with the output power at the extreme ends of this range 420 and 220 mW correspondingly. The proposed configuration allows efficient non-linear transformation of both CW and pulsed radiation in a partially coupled enhancement cavity.
Local modes analysis of a rotating marine ship propeller with higher order harmonic elements
Feng, Chen; Yong, Chen; Hongxing, Hua
2016-09-01
An annular harmonic finite element for the computation of the local modes of a pretwisted ship propeller is developed. The elements take into account both the gyroscopic effect and centrifugal stiffening of the propeller blades. The displacement field is expressed by a truncated Fourier series along the angle and by polynomial shape functions in the radial direction. As an example, the dynamic behaviour, i.e. the nature frequency and local modes, of a ship propeller is studied, and compared with ANSYS, both of which have good consistency.
Amin, Muhammad Ruhul
2012-08-10
In this paper, a planar metallic nanostructure design, which supports two distinct Fano resonances in its extinction cross-section spectrum under normally incident and linearly polarized electromagnetic field, is proposed. The proposed design involves a circular disk embedding an elongated cavity; shifting and rotating the cavity break the symmetry of the structure with respect to the incident field and induce higher order plasmon modes. As a result, Fano resonances are generated in the visible spectrum due to the destructive interference between the sub-radiant higher order modes and super-radiant the dipolar mode. The Fano resonances can be tuned by varying the cavity\\'s width and the rotation angle. An RLC circuit, which is mathematically equivalent to a mass-spring oscillator, is proposed to model the optical response of the nanostructure design.
Energy Technology Data Exchange (ETDEWEB)
Kawashima, Y.; Blednykh, A.; Cupolo, J.; Davidsaver, M.; Holub, B.; Ma, H.; Oliva, J.; Rose, J.; Sikora, R.; Yeddulla, M.
2011-03-28
The booster synchrotron for NSLS-II will include a 7-cell PETRA cavity, which was manufactured for the PETRA-II project at DESY. The cavity fundamental frequency operates at 500 MHz. In order to verify the impedances of the fundamental and higher-order modes (HOM), which were calculated by computer code, we measured the magnitude of the electromagnetic field of the fundamental acceleration mode and HOM using the bead-pull method. To keep the cavity body temperature constant, we used a chiller system to supply cooling water at 20 degrees C. The bead-pull measurement was automated with a computer. We encountered some issues during the measurement process due to the difficulty in measuring the electromagnetic field magnitude in a multi-cell cavity. We describe the method and apparatus for the field measurement, and the obtained results.
Superconducting accelerator cavity with a heat affected zone having a higher RRR
Energy Technology Data Exchange (ETDEWEB)
Brawley, John (Grafton, VA); Phillips, H. Lawrence (Hayes, VA)
2000-01-01
An improved method for welding accelerator cavities without the need for time consuming and expensive faying surface treatments comprising electron beam welding such cavities in a vacuum welding chamber within a vacuum envelope and using the following welding parameters: a beam voltage of between about 45 KV and 55 KV; a beam current between about 38 ma and 47 ma; a weld speed of about 15 cm/min; and a sharp focus and a rhombic raster of between about 9 KHz and 10 Khz. A welded cavity made according to the method of the present invention is also described.
Higher-order mode-based cavity misalignment measurements at the free-electron laser FLASH
Hellert, Thorsten; Baboi, Nicoleta; Shi, Liangliang
2017-12-01
At the Free-Electron Laser in Hamburg (FLASH) and the European X-Ray Free-Electron Laser, superconducting TeV-energy superconducting linear accelerator (TESLA)-type cavities are used for the acceleration of electron bunches, generating intense free-electron laser (FEL) beams. A long rf pulse structure allows one to accelerate long bunch trains, which considerably increases the efficiency of the machine. However, intrabunch-train variations of rf parameters and misalignments of rf structures induce significant trajectory variations that may decrease the FEL performance. The accelerating cavities are housed inside cryomodules, which restricts the ability for direct alignment measurements. In order to determine the transverse cavity position, we use a method based on beam-excited dipole modes in the cavities. We have developed an efficient measurement and signal processing routine and present its application to multiple accelerating modules at FLASH. The measured rms cavity offset agrees with the specification of the TESLA modules. For the first time, the tilt of a TESLA cavity inside a cryomodule is measured. The preliminary result agrees well with the ratio between the offset and angle dependence of the dipole mode which we calculated with eigenmode simulations.
DEFF Research Database (Denmark)
Jensen, Ole Bjarlin; Holm, J.; Sumpf, B.
2007-01-01
We have constructed a blue laser source consisting of a single-frequency tapered diode laser with external cavity feedback that is frequency doubled by a quasi-phase matched KTP (PPKTP) in a bowtie ring cavity and extract more than 360 mW of power at 405 nm. The conversion efficiency from fundame...... fundamental laser power to second harmonic power is 35 %, while it is 64 % from coupled fundamental power to extracted blue light. Thermal effects and gray tracking set an upper limit on the amount of generated blue light....
Extreme nonlinear optics in a femtosecond enhancement cavity.
Allison, T K; Cingöz, A; Yost, D C; Ye, J
2011-10-28
Intrinsic to the process of high-order harmonic generation is the creation of plasma and the resulting spatiotemporal distortions of the driving laser pulse. Inside a high-finesse cavity where the driver pulse and gas medium are reused, this can lead to optical bistability of the cavity-plasma system, accumulated self-phase modulation of the intracavity pulse, and coupling to higher-order cavity modes. We present an experimental and theoretical study of these effects and discuss their implications for power scaling of intracavity high-order harmonic generation and extreme ultraviolet frequency combs.
Tuo, Shengquan
2017-01-01
The mixed higher-order flow harmonics and nonlinear response coefficients of charged particles are presented as a function of $p_{\\rm{T}}$ and centrality in PbPb collisions at $\\sqrt{s_{NN}}$ = 2.76 TeV and 5.02 TeV with the CMS detector. The results are obtained using the scalar product method, and cover a $p_{\\rm{T}}$ range from 0.3 GeV/c to 8.0 GeV/c, pseudorapidity $\\vert\\eta\\vert <$ 2.4, and a centrality range of 0-60$\\%$. The mixed harmonic results at 5.02 TeV are compared to the matching higher-order flow harmonics from two-particle correlations, which measure $v_n$ values with respect to the $n$-th order event plane. It is observed that the nonlinear response coefficients of the odd harmonics are larger than the even harmonics ones. The results are compared with hydrodynamic predictions using different shear viscosity to entropy density ratios and different initial conditions.
Energy Technology Data Exchange (ETDEWEB)
Belendez, A [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Pascual, C [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fernandez, E [Departamento de Optica, FarmacologIa y AnatomIa, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Neipp, C [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Belendez, T [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)
2008-02-15
A modified He's homotopy perturbation method is used to calculate higher-order analytical approximate solutions to the relativistic and Duffing-harmonic oscillators. The He's homotopy perturbation method is modified by truncating the infinite series corresponding to the first-order approximate solution before introducing this solution in the second-order linear differential equation, and so on. We find this modified homotopy perturbation method works very well for the whole range of initial amplitudes, and the excellent agreement of the approximate frequencies and periodic solutions with the exact ones has been demonstrated and discussed. The approximate formulae obtained show excellent agreement with the exact solutions, and are valid for small as well as large amplitudes of oscillation, including the limiting cases of amplitude approaching zero and infinity. For the relativistic oscillator, only one iteration leads to high accuracy of the solutions with a maximal relative error for the approximate frequency of less than 1.6% for small and large values of oscillation amplitude, while this relative error is 0.65% for two iterations with two harmonics and as low as 0.18% when three harmonics are considered in the second approximation. For the Duffing-harmonic oscillator the relative error is as low as 0.078% when the second approximation is considered. Comparison of the result obtained using this method with those obtained by the harmonic balance methods reveals that the former is very effective and convenient.
Ganeev, Rashid A
2014-01-01
Preface; Why plasma harmonics? A very brief introduction Early stage of plasma harmonic studies - hopes and frustrations New developments in plasma harmonics studies: first successes Improvements of plasma harmonics; Theoretical basics of plasma harmonics; Basics of HHG Harmonic generation in fullerenes using few-cycle pulsesVarious approaches for description of observed peculiarities of resonant enhancement of a single harmonic in laser plasmaTwo-colour pump resonance-induced enhancement of odd and even harmonics from a tin plasmaCalculations of single harmonic generation from Mn plasma;Low-o
Design of a 50 MW, 34 GHz second harmonic coaxial gyroklystron for advanced accelerators
Energy Technology Data Exchange (ETDEWEB)
Arjona, M.R.; Lawson, W.
1999-07-01
At the University of Maryland, the authors have been investigating the feasibility of using gyroklystrons and gyroklystrons as drivers for linear colliders and advanced accelerators for a number of years. The most recent experimental tube achieved a peak power of about 80 MW at 8.57 GHz with 32% efficiency and over 30 dB gain with a three-cavity first harmonic circuit. The current experimental effort is devoted to producing about 100 MW of peak power at 17.14 GHz with a second-harmonic three-cavity tube. Some schemes for advanced linear colliders with center-of-mass energies of 5 TeV or more expect to require higher frequency sources, perhaps near 35 GHz or 91 GHz. A design study at 95 GHz indicated that peak powers near 7 MW were possible. In this design study, they present the simulated operating characteristics of a four cavity 34 GHz second-harmonic gyroklystron tube which is capable of producing about 60 MW of peak power with an efficiency of about 40% and a gain above 50 dB. The electron gun is a single-anode magnetron injection gun. The input cavity is a TE{sub 011} cavity which is driven at 17 GHz. The remainder of the cavities are TE{sub 021} cavities which interact near the second harmonic of the cyclotron frequency. The gain cavity and the output cavities are at twice the drive frequency, but the penultimate cavity is detuned to enhance efficiency. All cavities are abrupt-transition cavities. Both systems are derived from scaled versions of the 17 GHz tube. In this paper, they present detailed designs and performance predictions for both the electron gun and the microwave circuit.
Energy Technology Data Exchange (ETDEWEB)
Chatrchyan, Serguei; et al.,
2014-04-01
Measurements are presented by the CMS Collaboration at the Large Hadron Collider (LHC) of the higher-order harmonic coefficients that describe the azimuthal anisotropy of charged particles emitted in sqrt(s[NN]) = 2.76 TeV PbPb collisions. Expressed in terms of the Fourier components of the azimuthal distribution, the n = 3-6 harmonic coefficients are presented for charged particles as a function of their transverse momentum (0.3 < pt < 8.0 GeV), collision centrality (0-70%), and pseudorapidity (abs(eta) < 2.0). The data are analyzed using the event plane, multiparticle cumulant, and Lee-Yang zeros methods, which provide different sensitivities to initial-state fluctuations. Taken together with earlier LHC measurements of elliptic flow (n = 2), the results on higher-order harmonic coefficients develop a more complete picture of the collective motion in high-energy heavy-ion collisions and shed light on the properties of the produced medium.
Chatrchyan, Serguei; Sirunyan, Albert M; Tumasyan, Armen; Adam, Wolfgang; Bergauer, Thomas; Dragicevic, Marko; Erö, Janos; Fabjan, Christian; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Hartl, Christian; Hörmann, Natascha; Hrubec, Josef; Jeitler, Manfred; Kiesenhofer, Wolfgang; Knünz, Valentin; Krammer, Manfred; Krätschmer, Ilse; Liko, Dietrich; Mikulec, Ivan; Rabady, Dinyar; Rahbaran, Babak; Rohringer, Herbert; Schöfbeck, Robert; Strauss, Josef; Taurok, Anton; Treberer-Treberspurg, Wolfgang; Waltenberger, Wolfgang; Wulz, Claudia-Elisabeth; Mossolov, Vladimir; Shumeiko, Nikolai; Suarez Gonzalez, Juan; Alderweireldt, Sara; Bansal, Monika; Bansal, Sunil; Cornelis, Tom; De Wolf, Eddi A; Janssen, Xavier; Knutsson, Albert; Luyckx, Sten; Mucibello, Luca; Ochesanu, Silvia; Roland, Benoit; Rougny, Romain; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Van Spilbeeck, Alex; Blekman, Freya; Blyweert, Stijn; D'Hondt, Jorgen; Heracleous, Natalie; Kalogeropoulos, Alexis; Keaveney, James; Kim, Tae Jeong; Lowette, Steven; Maes, Michael; Olbrechts, Annik; Strom, Derek; Tavernier, Stefaan; Van Doninck, Walter; Van Mulders, Petra; Van Onsem, Gerrit Patrick; Villella, Ilaria; Caillol, Cécile; Clerbaux, Barbara; De Lentdecker, Gilles; Favart, Laurent; Gay, Arnaud; Hreus, Tomas; Léonard, Alexandre; Marage, Pierre Edouard; Mohammadi, Abdollah; Perniè, Luca; Reis, Thomas; Seva, Tomislav; Thomas, Laurent; Vander Velde, Catherine; Vanlaer, Pascal; Wang, Jian; Adler, Volker; Beernaert, Kelly; Benucci, Leonardo; Cimmino, Anna; Costantini, Silvia; Dildick, Sven; Garcia, Guillaume; Klein, Benjamin; Lellouch, Jérémie; Mccartin, Joseph; Ocampo Rios, Alberto Andres; Ryckbosch, Dirk; Sigamani, Michael; Strobbe, Nadja; Thyssen, Filip; Tytgat, Michael; Walsh, Sinead; Yazgan, Efe; Zaganidis, Nicolas; Basegmez, Suzan; Beluffi, Camille; Bruno, Giacomo; Castello, Roberto; Caudron, Adrien; Ceard, Ludivine; Da Silveira, Gustavo Gil; Delaere, Christophe; Du Pree, Tristan; Favart, Denis; Forthomme, Laurent; Giammanco, Andrea; Hollar, Jonathan; Jez, Pavel; Komm, Matthias; Lemaitre, Vincent; Liao, Junhui; Militaru, Otilia; Nuttens, Claude; Pagano, Davide; Pin, Arnaud; Piotrzkowski, Krzysztof; Popov, Andrey; Quertenmont, Loic; Selvaggi, Michele; Vidal Marono, Miguel; Vizan Garcia, Jesus Manuel; Beliy, Nikita; Caebergs, Thierry; Daubie, Evelyne; Hammad, Gregory Habib; Alves, Gilvan; Correa Martins Junior, Marcos; Martins, Thiago; Pol, Maria Elena; Henrique Gomes E Souza, Moacyr; Aldá Júnior, Walter Luiz; Carvalho, Wagner; Chinellato, Jose; Custódio, Analu; Melo Da Costa, Eliza; De Jesus Damiao, Dilson; De Oliveira Martins, Carley; Fonseca De Souza, Sandro; Malbouisson, Helena; Malek, Magdalena; Matos Figueiredo, Diego; Mundim, Luiz; Nogima, Helio; Prado Da Silva, Wanda Lucia; Santaolalla, Javier; Santoro, Alberto; Sznajder, Andre; Tonelli Manganote, Edmilson José; Vilela Pereira, Antonio; Bernardes, Cesar Augusto; De Almeida Dias, Flavia; Tomei, Thiago; De Moraes Gregores, Eduardo; Lagana, Caio; Mercadante, Pedro G; Novaes, Sergio F; Padula, Sandra; Genchev, Vladimir; Iaydjiev, Plamen; Marinov, Andrey; Piperov, Stefan; Rodozov, Mircho; Sultanov, Georgi; Vutova, Mariana; Dimitrov, Anton; Glushkov, Ivan; Hadjiiska, Roumyana; Kozhuharov, Venelin; Litov, Leander; Pavlov, Borislav; Petkov, Peicho; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Chen, Mingshui; Du, Ran; Jiang, Chun-Hua; Liang, Dong; Liang, Song; Meng, Xiangwei; Plestina, Roko; Tao, Junquan; Wang, Xianyou; Wang, Zheng; Asawatangtrakuldee, Chayanit; Ban, Yong; Guo, Yifei; Li, Wenbo; Liu, Shuai; Mao, Yajun; Qian, Si-Jin; Teng, Haiyun; Wang, Dayong; Zhang, Linlin; Zou, Wei; Avila, Carlos; Carrillo Montoya, Camilo Andres; Chaparro Sierra, Luisa Fernanda; Florez, Carlos; Gomez, Juan Pablo; Gomez Moreno, Bernardo; Sanabria, Juan Carlos; Godinovic, Nikola; Lelas, Damir; Polic, Dunja; Puljak, Ivica; Antunovic, Zeljko; Kovac, Marko; Brigljevic, Vuko; Kadija, Kreso; Luetic, Jelena; Mekterovic, Darko; Morovic, Srecko; Tikvica, Lucija; Attikis, Alexandros; Mavromanolakis, Georgios; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Finger, Miroslav; Finger Jr, Michael; Abdelalim, Ahmed Ali; Assran, Yasser; Elgammal, Sherif; Ellithi Kamel, Ali; Mahmoud, Mohammed; Radi, Amr; Kadastik, Mario; Müntel, Mait; Murumaa, Marion; Raidal, Martti; Rebane, Liis; Tiko, Andres; Eerola, Paula; Fedi, Giacomo; Voutilainen, Mikko; Härkönen, Jaakko; Karimäki, Veikko; Kinnunen, Ritva; Kortelainen, Matti J; Lampén, Tapio; Lassila-Perini, Kati; Lehti, Sami; Lindén, Tomas; Luukka, Panja-Riina; Mäenpää, Teppo; Peltola, Timo; Tuominen, Eija; Tuominiemi, Jorma; Tuovinen, Esa; Wendland, Lauri; Tuuva, Tuure; Besancon, Marc; Couderc, Fabrice; Dejardin, Marc; Denegri, Daniel; Fabbro, Bernard; Faure, Jean-Louis; Ferri, Federico; Ganjour, Serguei; Givernaud, Alain; Gras, Philippe; Hamel de Monchenault, Gautier; Jarry, Patrick; Locci, Elizabeth; Malcles, Julie; Nayak, Aruna; Rander, John; Rosowsky, André; Titov, Maksym; Baffioni, Stephanie; Beaudette, Florian; Busson, Philippe; Charlot, Claude; Daci, Nadir; Dahms, Torsten; Dalchenko, Mykhailo; Dobrzynski, Ludwik; Florent, Alice; Granier de Cassagnac, Raphael; Haguenauer, Maurice; Miné, Philippe; Mironov, Camelia; Naranjo, Ivo Nicolas; Nguyen, Matthew; Ochando, Christophe; Paganini, Pascal; Sabes, David; Salerno, Roberto; Sirois, Yves; Veelken, Christian; Yilmaz, Yetkin; Zabi, Alexandre; Agram, Jean-Laurent; Andrea, Jeremy; Bloch, Daniel; Brom, Jean-Marie; Chabert, Eric Christian; Collard, Caroline; Conte, Eric; Drouhin, Frédéric; Fontaine, Jean-Charles; Gelé, Denis; Goerlach, Ulrich; Goetzmann, Christophe; Juillot, Pierre; Le Bihan, Anne-Catherine; Van Hove, Pierre; Gadrat, Sébastien; Beauceron, Stephanie; Beaupere, Nicolas; Boudoul, Gaelle; Brochet, Sébastien; Chasserat, Julien; Chierici, Roberto; Contardo, Didier; Depasse, Pierre; El Mamouni, Houmani; Fan, Jiawei; Fay, Jean; Gascon, Susan; Gouzevitch, Maxime; Ille, Bernard; Kurca, Tibor; Lethuillier, Morgan; Mirabito, Laurent; Perries, Stephane; Ruiz Alvarez, José David; Sgandurra, Louis; Sordini, Viola; Vander Donckt, Muriel; Verdier, Patrice; Viret, Sébastien; Xiao, Hong; Tsamalaidze, Zviad; Autermann, Christian; Beranek, Sarah; Bontenackels, Michael; Calpas, Betty; Edelhoff, Matthias; Feld, Lutz; Hindrichs, Otto; Klein, Katja; Ostapchuk, Andrey; Perieanu, Adrian; Raupach, Frank; Sammet, Jan; Schael, Stefan; Sprenger, Daniel; Weber, Hendrik; Wittmer, Bruno; Zhukov, Valery; Ata, Metin; Caudron, Julien; Dietz-Laursonn, Erik; Duchardt, Deborah; Erdmann, Martin; Fischer, Robert; Güth, Andreas; Hebbeker, Thomas; Heidemann, Carsten; Hoepfner, Kerstin; Klingebiel, Dennis; Knutzen, Simon; Kreuzer, Peter; Merschmeyer, Markus; Meyer, Arnd; Olschewski, Mark; Padeken, Klaas; Papacz, Paul; Pieta, Holger; Reithler, Hans; Schmitz, Stefan Antonius; Sonnenschein, Lars; Teyssier, Daniel; Thüer, Sebastian; Weber, Martin; Cherepanov, Vladimir; Erdogan, Yusuf; Flügge, Günter; Geenen, Heiko; Geisler, Matthias; Haj Ahmad, Wael; Hoehle, Felix; Kargoll, Bastian; Kress, Thomas; Kuessel, Yvonne; Lingemann, Joschka; Nowack, Andreas; Nugent, Ian Michael; Perchalla, Lars; Pooth, Oliver; Stahl, Achim; Asin, Ivan; Bartosik, Nazar; Behr, Joerg; Behrenhoff, Wolf; Behrens, Ulf; Bell, Alan James; Bergholz, Matthias; Bethani, Agni; Borras, Kerstin; Burgmeier, Armin; Cakir, Altan; Calligaris, Luigi; Campbell, Alan; Choudhury, Somnath; Costanza, Francesco; Diez Pardos, Carmen; Dooling, Samantha; Dorland, Tyler; Eckerlin, Guenter; Eckstein, Doris; Eichhorn, Thomas; Flucke, Gero; Geiser, Achim; Grebenyuk, Anastasia; Gunnellini, Paolo; Habib, Shiraz; Hauk, Johannes; Hellwig, Gregor; Hempel, Maria; Horton, Dean; Jung, Hannes; Kasemann, Matthias; Katsas, Panagiotis; Kleinwort, Claus; Krämer, Mira; Krücker, Dirk; Lange, Wolfgang; Leonard, Jessica; Lipka, Katerina; Lohmann, Wolfgang; Lutz, Benjamin; Mankel, Rainer; Marfin, Ihar; Melzer-Pellmann, Isabell-Alissandra; Meyer, Andreas Bernhard; Mnich, Joachim; Mussgiller, Andreas; Naumann-Emme, Sebastian; Novgorodova, Olga; Nowak, Friederike; Perrey, Hanno; Petrukhin, Alexey; Pitzl, Daniel; Placakyte, Ringaile; Raspereza, Alexei; Ribeiro Cipriano, Pedro M; Riedl, Caroline; Ron, Elias; Sahin, Mehmet Özgür; Salfeld-Nebgen, Jakob; Schmidt, Ringo; Schoerner-Sadenius, Thomas; Schröder, Matthias; Stein, Matthias; Vargas Trevino, Andrea Del Rocio; Walsh, Roberval; Wissing, Christoph; Aldaya Martin, Maria; Blobel, Volker; Enderle, Holger; Erfle, Joachim; Garutti, Erika; Görner, Martin; Gosselink, Martijn; Haller, Johannes; Goebel, Kristin; Höing, Rebekka Sophie; Kirschenmann, Henning; Klanner, Robert; Kogler, Roman; Lange, Jörn; Marchesini, Ivan; Ott, Jochen; Peiffer, Thomas; Pietsch, Niklas; Rathjens, Denis; Sander, Christian; Schettler, Hannes; Schleper, Peter; Schlieckau, Eike; Schmidt, Alexander; Seidel, Markus; Sibille, Jennifer; Sola, Valentina; Stadie, Hartmut; Steinbrück, Georg; Troendle, Daniel; Usai, Emanuele; Vanelderen, Lukas; Barth, Christian; Baus, Colin; Berger, Joram; Böser, Christian; Butz, Erik; Chwalek, Thorsten; De Boer, Wim; Descroix, Alexis; Dierlamm, Alexander; Feindt, Michael; Guthoff, Moritz; Hartmann, Frank; Hauth, Thomas; Held, Hauke; Hoffmann, Karl-Heinz; Husemann, Ulrich; Katkov, Igor; Kornmayer, Andreas; Kuznetsova, Ekaterina; Lobelle Pardo, Patricia; Martschei, Daniel; Mozer, Matthias Ulrich; Müller, Thomas; Niegel, Martin; Nürnberg, Andreas; Oberst, Oliver; Quast, Gunter; Rabbertz, Klaus; Ratnikov, Fedor; Röcker, Steffen; Schilling, Frank-Peter; Schott, Gregory; Simonis, Hans-Jürgen; Stober, Fred-Markus Helmut; Ulrich, Ralf; Wagner-Kuhr, Jeannine; Wayand, Stefan; Weiler, Thomas; Wolf, Roger; Zeise, Manuel; Anagnostou, Georgios; Daskalakis, Georgios; Geralis, Theodoros; Kesisoglou, Stilianos; Kyriakis, Aristotelis; Loukas, Demetrios; Markou, Athanasios; Markou, Christos; Ntomari, Eleni; Topsis-giotis, Iasonas; Gouskos, Loukas; Panagiotou, Apostolos; Saoulidou, Niki; Stiliaris, Efstathios; Aslanoglou, Xenofon; Evangelou, Ioannis; Flouris, Giannis; Foudas, Costas; Kokkas, Panagiotis; Manthos, Nikolaos; Papadopoulos, Ioannis; Paradas, Evangelos; Bencze, Gyorgy; Hajdu, Csaba; Hidas, Pàl; Horvath, Dezso; Sikler, Ferenc; Veszpremi, Viktor; Vesztergombi, Gyorgy; Zsigmond, Anna Julia; Beni, Noemi; Czellar, Sandor; Molnar, Jozsef; Palinkas, Jozsef; Szillasi, Zoltan; Karancsi, János; Raics, Peter; Trocsanyi, Zoltan Laszlo; Ujvari, Balazs; Swain, Sanjay Kumar; Beri, Suman Bala; Bhatnagar, Vipin; Dhingra, Nitish; Gupta, Ruchi; Kaur, Manjit; Mehta, Manuk Zubin; Mittal, Monika; Nishu, Nishu; Sharma, Archana; Singh, Jasbir; Kumar, Ashok; Kumar, Arun; Ahuja, Sudha; Bhardwaj, Ashutosh; Choudhary, Brajesh C; Kumar, Ajay; Malhotra, Shivali; Naimuddin, Md; Ranjan, Kirti; Saxena, Pooja; Sharma, Varun; Shivpuri, Ram Krishen; Banerjee, Sunanda; Bhattacharya, Satyaki; Chatterjee, Kalyanmoy; Dutta, Suchandra; Gomber, Bhawna; Jain, Sandhya; Jain, Shilpi; Khurana, Raman; Modak, Atanu; Mukherjee, Swagata; Roy, Debarati; Sarkar, Subir; Sharan, Manoj; Singh, Anil; Abdulsalam, Abdulla; Dutta, Dipanwita; Kailas, Swaminathan; Kumar, Vineet; Mohanty, Ajit Kumar; Pant, Lalit Mohan; Shukla, Prashant; Topkar, Anita; Aziz, Tariq; Chatterjee, Rajdeep Mohan; Ganguly, Sanmay; Ghosh, Saranya; Guchait, Monoranjan; Gurtu, Atul; Kole, Gouranga; Kumar, Sanjeev; Maity, Manas; Majumder, Gobinda; Mazumdar, Kajari; Mohanty, Gagan Bihari; Parida, Bibhuti; Sudhakar, Katta; Wickramage, Nadeesha; Banerjee, Sudeshna; Dugad, Shashikant; Arfaei, Hessamaddin; Bakhshiansohi, Hamed; Behnamian, Hadi; Etesami, Seyed Mohsen; Fahim, Ali; Jafari, Abideh; Khakzad, Mohsen; Mohammadi Najafabadi, Mojtaba; Naseri, Mohsen; Paktinat Mehdiabadi, Saeid; Safarzadeh, Batool; Zeinali, Maryam; Grunewald, Martin; Abbrescia, Marcello; Barbone, Lucia; Calabria, Cesare; Chhibra, Simranjit Singh; Colaleo, Anna; Creanza, Donato; De Filippis, Nicola; De Palma, Mauro; Fiore, Luigi; Iaselli, Giuseppe; Maggi, Giorgio; Maggi, Marcello; Marangelli, Bartolomeo; My, Salvatore; Nuzzo, Salvatore; Pacifico, Nicola; Pompili, Alexis; Pugliese, Gabriella; Radogna, Raffaella; Selvaggi, Giovanna; Silvestris, Lucia; Singh, Gurpreet; Venditti, Rosamaria; Verwilligen, Piet; Zito, Giuseppe; Abbiendi, Giovanni; Benvenuti, Alberto; Bonacorsi, Daniele; Braibant-Giacomelli, Sylvie; Brigliadori, Luca; Campanini, Renato; Capiluppi, Paolo; Castro, Andrea; Cavallo, Francesca Romana; Codispoti, Giuseppe; Cuffiani, Marco; Dallavalle, Gaetano-Marco; Fabbri, Fabrizio; Fanfani, Alessandra; Fasanella, Daniele; Giacomelli, Paolo; Grandi, Claudio; Guiducci, Luigi; Marcellini, Stefano; Masetti, Gianni; Meneghelli, Marco; Montanari, Alessandro; Navarria, Francesco; Odorici, Fabrizio; Perrotta, Andrea; Primavera, Federica; Rossi, Antonio; Rovelli, Tiziano; Siroli, Gian Piero; Tosi, Nicolò; Travaglini, Riccardo; Albergo, Sebastiano; Cappello, Gigi; Chiorboli, Massimiliano; Costa, Salvatore; Giordano, Ferdinando; Potenza, Renato; Tricomi, Alessia; Tuve, Cristina; Barbagli, Giuseppe; Ciulli, Vitaliano; Civinini, Carlo; D'Alessandro, Raffaello; Focardi, Ettore; Gallo, Elisabetta; Gonzi, Sandro; Gori, Valentina; Lenzi, Piergiulio; Meschini, Marco; Paoletti, Simone; Sguazzoni, Giacomo; Tropiano, Antonio; Benussi, Luigi; Bianco, Stefano; Fabbri, Franco; Piccolo, Davide; Fabbricatore, Pasquale; Ferretti, Roberta; Ferro, Fabrizio; Lo Vetere, Maurizio; Musenich, Riccardo; Robutti, Enrico; Tosi, Silvano; Benaglia, Andrea; Dinardo, Mauro Emanuele; Fiorendi, Sara; Gennai, Simone; Ghezzi, Alessio; Govoni, Pietro; Lucchini, Marco Toliman; Malvezzi, Sandra; Manzoni, Riccardo Andrea; Martelli, Arabella; Menasce, Dario; Moroni, Luigi; Paganoni, Marco; Pedrini, Daniele; Ragazzi, Stefano; Redaelli, Nicola; Tabarelli de Fatis, Tommaso; Buontempo, Salvatore; Cavallo, Nicola; Fabozzi, Francesco; Iorio, Alberto Orso Maria; Lista, Luca; Meola, Sabino; Merola, Mario; Paolucci, Pierluigi; Azzi, Patrizia; Bacchetta, Nicola; Biasotto, Massimo; Bisello, Dario; Branca, Antonio; Carlin, Roberto; Checchia, Paolo; Dorigo, Tommaso; Dosselli, Umberto; Galanti, Mario; Gasparini, Fabrizio; Gasparini, Ugo; Giubilato, Piero; Gozzelino, Andrea; Kanishchev, Konstantin; Lacaprara, Stefano; Lazzizzera, Ignazio; Margoni, Martino; Meneguzzo, Anna Teresa; Pazzini, Jacopo; Pozzobon, Nicola; Ronchese, Paolo; Simonetto, Franco; Torassa, Ezio; Tosi, Mia; Vanini, Sara; Ventura, Sandro; Zotto, Pierluigi; Zucchetta, Alberto; Zumerle, Gianni; Gabusi, Michele; Ratti, Sergio P; Riccardi, Cristina; Vitulo, Paolo; Biasini, Maurizio; Bilei, Gian Mario; Fanò, Livio; Lariccia, Paolo; Mantovani, Giancarlo; Menichelli, Mauro; Nappi, Aniello; Romeo, Francesco; Saha, Anirban; Santocchia, Attilio; Spiezia, Aniello; Androsov, Konstantin; Azzurri, Paolo; Bagliesi, Giuseppe; Bernardini, Jacopo; Boccali, Tommaso; Broccolo, Giuseppe; Castaldi, Rino; Ciocci, Maria Agnese; Dell'Orso, Roberto; Fiori, Francesco; Foà, Lorenzo; Giassi, Alessandro; Grippo, Maria Teresa; Kraan, Aafke; Ligabue, Franco; Lomtadze, Teimuraz; Martini, Luca; Messineo, Alberto; Moon, Chang-Seong; Palla, Fabrizio; Rizzi, Andrea; Savoy-Navarro, Aurore; Serban, Alin Titus; Spagnolo, Paolo; Squillacioti, Paola; Tenchini, Roberto; Tonelli, Guido; Venturi, Andrea; Verdini, Piero Giorgio; Vernieri, Caterina; Barone, Luciano; Cavallari, Francesca; Del Re, Daniele; Diemoz, Marcella; Grassi, Marco; Jorda, Clara; Longo, Egidio; Margaroli, Fabrizio; Meridiani, Paolo; Micheli, Francesco; Nourbakhsh, Shervin; Organtini, Giovanni; Paramatti, Riccardo; Rahatlou, Shahram; Rovelli, Chiara; Soffi, Livia; Traczyk, Piotr; Amapane, Nicola; Arcidiacono, Roberta; Argiro, Stefano; Arneodo, Michele; Bellan, Riccardo; Biino, Cristina; Cartiglia, Nicolo; Casasso, Stefano; Costa, Marco; Degano, Alessandro; Demaria, Natale; Mariotti, Chiara; Maselli, Silvia; Migliore, Ernesto; Monaco, Vincenzo; Musich, Marco; Obertino, Maria Margherita; Ortona, Giacomo; Pacher, Luca; Pastrone, Nadia; Pelliccioni, Mario; Potenza, Alberto; Romero, Alessandra; Ruspa, Marta; Sacchi, Roberto; Solano, Ada; Staiano, Amedeo; Tamponi, Umberto; Belforte, Stefano; Candelise, Vieri; Casarsa, Massimo; Cossutti, Fabio; Della Ricca, Giuseppe; Gobbo, Benigno; La Licata, Chiara; Marone, Matteo; Montanino, Damiana; Penzo, Aldo; Schizzi, Andrea; Umer, Tomo; Zanetti, Anna; Chang, Sunghyun; Kim, Tae Yeon; Nam, Soon-Kwon; Kim, Dong Hee; Kim, Gui Nyun; Kim, Ji Eun; Kong, Dae Jung; Lee, Sangeun; Oh, Young Do; Park, Hyangkyu; Son, Dong-Chul; Kim, Jae Yool; Kim, Zero Jaeho; Song, Sanghyeon; Choi, Suyong; Gyun, Dooyeon; Hong, Byung-Sik; Jo, Mihee; Kim, Hyunchul; Kim, Yongsun; Lee, Kyong Sei; Park, Sung Keun; Roh, Youn; Choi, Minkyoo; Kim, Ji Hyun; Park, Chawon; Park, Inkyu; Park, Sangnam; Ryu, Geonmo; Choi, Young-Il; Choi, Young Kyu; Goh, Junghwan; Kim, Min Suk; Kwon, Eunhyang; Lee, Byounghoon; Lee, Jongseok; Lee, Sungeun; Seo, Hyunkwan; Yu, Intae; Juodagalvis, Andrius; Castilla-Valdez, Heriberto; De La Cruz-Burelo, Eduard; Heredia-de La Cruz, Ivan; Lopez-Fernandez, Ricardo; Martínez-Ortega, Jorge; Sánchez Hernández, Alberto; Villasenor-Cendejas, Luis Manuel; Carrillo Moreno, Salvador; Vazquez Valencia, Fabiola; Salazar Ibarguen, Humberto Antonio; Casimiro Linares, Edgar; Morelos Pineda, Antonio; Krofcheck, David; Butler, Philip H; Doesburg, Robert; Reucroft, Steve; Silverwood, Hamish; Ahmad, Muhammad; Asghar, Muhammad Irfan; Butt, Jamila; Hoorani, Hafeez R; Khalid, Shoaib; Khan, Wajid Ali; Khurshid, Taimoor; Qazi, Shamona; Shah, Mehar Ali; Shoaib, Muhammad; Bialkowska, Helena; Bluj, Michal; Boimska, Bożena; Frueboes, Tomasz; Górski, Maciej; Kazana, Malgorzata; Nawrocki, Krzysztof; Romanowska-Rybinska, Katarzyna; Szleper, Michal; Wrochna, Grzegorz; Zalewski, Piotr; Brona, Grzegorz; Bunkowski, Karol; Cwiok, Mikolaj; Dominik, Wojciech; Doroba, Krzysztof; Kalinowski, Artur; Konecki, Marcin; Krolikowski, Jan; Misiura, Maciej; Wolszczak, Weronika; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Faccioli, Pietro; Ferreira Parracho, Pedro Guilherme; Gallinaro, Michele; Nguyen, Federico; Rodrigues Antunes, Joao; Seixas, Joao; Varela, Joao; Vischia, Pietro; Afanasiev, Serguei; Bunin, Pavel; Gavrilenko, Mikhail; Golutvin, Igor; Gorbunov, Ilya; Kamenev, Alexey; Karjavin, Vladimir; Konoplyanikov, Viktor; Lanev, Alexander; Malakhov, Alexander; Matveev, Viktor; Moisenz, Petr; Palichik, Vladimir; Perelygin, Victor; Shmatov, Sergey; Skatchkov, Nikolai; Smirnov, Vitaly; Zarubin, Anatoli; Golovtsov, Victor; Ivanov, Yury; Kim, Victor; Levchenko, Petr; Murzin, Victor; Oreshkin, Vadim; Smirnov, Igor; Sulimov, Valentin; Uvarov, Lev; Vavilov, Sergey; Vorobyev, Alexey; Vorobyev, Andrey; Andreev, Yuri; Dermenev, Alexander; Gninenko, Sergei; Golubev, Nikolai; Kirsanov, Mikhail; Krasnikov, Nikolai; Pashenkov, Anatoli; Tlisov, Danila; Toropin, Alexander; Epshteyn, Vladimir; Gavrilov, Vladimir; Lychkovskaya, Natalia; Popov, Vladimir; Safronov, Grigory; Semenov, Sergey; Spiridonov, Alexander; Stolin, Viatcheslav; Vlasov, Evgueni; Zhokin, Alexander; Andreev, Vladimir; Azarkin, Maksim; Dremin, Igor; Kirakosyan, Martin; Leonidov, Andrey; Mesyats, Gennady; Rusakov, Sergey V; Vinogradov, Alexey; Belyaev, Andrey; Boos, Edouard; Ershov, Alexander; Gribushin, Andrey; Klyukhin, Vyacheslav; Kodolova, Olga; Korotkikh, Vladimir; Lokhtin, Igor; Markina, Anastasia; Obraztsov, Stepan; Petrushanko, Sergey; Savrin, Viktor; Snigirev, Alexander; Vardanyan, Irina; Azhgirey, Igor; Bayshev, Igor; Bitioukov, Sergei; Kachanov, Vassili; Kalinin, Alexey; Konstantinov, Dmitri; Krychkine, Victor; Petrov, Vladimir; Ryutin, Roman; Sobol, Andrei; Tourtchanovitch, Leonid; Troshin, Sergey; Tyurin, Nikolay; Uzunian, Andrey; Volkov, Alexey; Adzic, Petar; Djordjevic, Milos; Ekmedzic, Marko; Milosevic, Jovan; Aguilar-Benitez, Manuel; Alcaraz Maestre, Juan; Battilana, Carlo; Calvo, Enrique; Cerrada, Marcos; Chamizo Llatas, Maria; Colino, Nicanor; De La Cruz, Begona; Delgado Peris, Antonio; Domínguez Vázquez, Daniel; Fernandez Bedoya, Cristina; Fernández Ramos, Juan Pablo; Ferrando, Antonio; Flix, Jose; Fouz, Maria Cruz; Garcia-Abia, Pablo; Gonzalez Lopez, Oscar; Goy Lopez, Silvia; Hernandez, Jose M; Josa, Maria Isabel; Merino, Gonzalo; Navarro De Martino, Eduardo; Puerta Pelayo, Jesus; Quintario Olmeda, Adrián; Redondo, Ignacio; Romero, Luciano; Senghi Soares, Mara; Willmott, Carlos; Albajar, Carmen; de Trocóniz, Jorge F; Brun, Hugues; Cuevas, Javier; Fernandez Menendez, Javier; Folgueras, Santiago; Gonzalez Caballero, Isidro; Lloret Iglesias, Lara; Brochero Cifuentes, Javier Andres; Cabrillo, Iban Jose; Calderon, Alicia; Chuang, Shan-Huei; Duarte Campderros, Jordi; Fernandez, Marcos; Gomez, Gervasio; Gonzalez Sanchez, Javier; Graziano, Alberto; Lopez Virto, Amparo; Marco, Jesus; Marco, Rafael; Martinez Rivero, Celso; Matorras, Francisco; Munoz Sanchez, Francisca Javiela; Piedra Gomez, Jonatan; Rodrigo, Teresa; Rodríguez-Marrero, Ana Yaiza; Ruiz-Jimeno, Alberto; Scodellaro, Luca; Vila, Ivan; Vilar Cortabitarte, Rocio; Abbaneo, Duccio; Auffray, Etiennette; Auzinger, Georg; Bachtis, Michail; Baillon, Paul; Ball, Austin; Barney, David; Bendavid, Joshua; Benhabib, Lamia; Benitez, Jose F; Bernet, Colin; Bianchi, Giovanni; Bloch, Philippe; Bocci, Andrea; Bonato, Alessio; Bondu, Olivier; Botta, Cristina; Breuker, Horst; Camporesi, Tiziano; Cerminara, Gianluca; Christiansen, Tim; Coarasa Perez, Jose Antonio; Colafranceschi, Stefano; D'Alfonso, Mariarosaria; D'Enterria, David; Dabrowski, Anne; David Tinoco Mendes, Andre; De Guio, Federico; De Roeck, Albert; De Visscher, Simon; Di Guida, Salvatore; Dobson, Marc; Dupont-Sagorin, Niels; Elliott-Peisert, Anna; Eugster, Jürg; Franzoni, Giovanni; Funk, Wolfgang; Giffels, Manuel; Gigi, Dominique; Gill, Karl; Girone, Maria; Giunta, Marina; Glege, Frank; Gomez-Reino Garrido, Robert; Gowdy, Stephen; Guida, Roberto; Hammer, Josef; Hansen, Magnus; Harris, Philip; Hinzmann, Andreas; Innocente, Vincenzo; Janot, Patrick; Karavakis, Edward; Kousouris, Konstantinos; Krajczar, Krisztian; Lecoq, Paul; Lee, Yen-Jie; Lourenco, Carlos; Magini, Nicolo; Malgeri, Luca; Mannelli, Marcello; Masetti, Lorenzo; Meijers, Frans; Mersi, Stefano; Meschi, Emilio; 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Swanson, Joshua
2014-04-11
Measurements are presented by the CMS Collaboration at the Large Hadron Collider (LHC) of the higher-order harmonic coefficients that describe the azimuthal anisotropy of charged particles emitted in $\\sqrt{s_{NN}}$ = 2.76 TeV PbPb collisions. Expressed in terms of the Fourier components of the azimuthal distribution, the n = 3-6 harmonic coefficients are presented for charged particles as a function of their transverse momentum ($0.3 \\lt p_T \\lt 8.0$ GeV/c), collision centrality (0-70%), and pseudorapidity (abs(eta) $\\lt$ 2.0). The data are analyzed using the event plane, multi-particle cumulant, and Lee-Yang zeros methods, which provide different sensitivities to initial state fluctuations. Taken together with earlier LHC measurements of elliptic flow (n=2), the results on higher-order harmonic coefficients develop a more complete picture of the collective motion in high-energy heavy-ion collisions and shed light on the properties of the produced medium.
Three-dimensional simulations of harmonic radiation and harmonic lasing
Energy Technology Data Exchange (ETDEWEB)
Schmitt, M.J.; McVey, B.D.
1990-01-01
Characteristics of the harmonic emission from free-electron lasers (FELs) are examined in the spontaneous, coherent-spontaneous and stimulated emission regimes. The radiation at both odd and even harmonic frequencies is treated for electron beams with finite emittance and energy spread. In the spontaneous emission regime, the transverse radiation patterns including the transverse frequency dependences, are given. How this expression is modified to include energy spread and emittance is described. In the coherent-spontaneous emission and stimulated emission regimes, the interaction of the radiation fields with the electrons must be treated self-consistently. Here, a single-frequency distributed transverse source function for each electron is used in the harmonic version of the 3-D code FELEX to model the harmonic radiation. The code has recently been modified to simultaneously model the fundamental and harmonic interactions for multiple-pass oscillator simulations. These modifications facilitate the examination of FELs under various operating conditions. When the FEL is lasing at the fundamental, the evolution of the harmonic fields can be examined. This evolution is unique in the sense that the electron beam radiates at the harmonic frequencies in the presence of the harmonic radiation circulating in the cavity. As a result, enhancements of the harmonic emission can be observed. Finally, harmonic lasing can occur in cases where there is sufficient gain to overcome cavity losses and lasing at the fundamental can be suppressed. The characteristics and efficiency of these interactions are explored. 11 refs., 9 figs.
Energy Technology Data Exchange (ETDEWEB)
Zhang, P.; Baboi, N.; Jones, R.M.; Eddy, N.
2012-11-01
Beam-excited higher order modes (HOMs) can provide remote diagnostics information of the beam position and cavity misalignment. In this paper we report on recent studies on the resolution with specially selected series of modes with custom-built electronics. This constitutes the first report of measurements of these cavities in which we obtained a resolution of 20 micron in beam offset. Details of the setup of the electronics and HOM measurements are provided.
Slenders, Eli; vandeVen, Martin; Hooyberghs, Jef; Ameloot, Marcel
2015-07-15
We present a general analytical model for the intensity fluctuation autocorrelation function for second and third harmonic generating point scatterers. Expressions are derived for a stationary laser beam and for scanning beam configurations for specific correlation methodologies. We discuss free translational diffusion in both three and two dimensions. At low particle concentrations, the expressions for fluorescence are retrieved, while at high particle concentrations a rescaling of the function parameters is required for a stationary illumination beam, provided that the phase shift per unit length of the beam equals zero.
Energy Technology Data Exchange (ETDEWEB)
Toyoshima, Akio; Kikuchi, Takashi; Tanaka, Hirokazu [KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Mase, Kazuhiko, E-mail: mase@post.kek.jp; Amemiya, Kenta [KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); SOKENDAI (The Graduate University for Advanced Studies), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)
2015-09-26
Carbon contamination of a chromium-coated mirror was removed by exposure to oxygen activated with non-monochromated synchrotron radiation. Higher-order harmonics of the chromium-coated mirror are much smaller than those of a gold-coated mirror in the carbon K-edge region. Carbon-free chromium-coated optics are ideal in the carbon K-edge region (280–330 eV) because the reflectivity of first-order light is larger than that of gold-coated optics while the second-order harmonics (560–660 eV) are significantly suppressed by chromium L-edge and oxygen K-edge absorption. Here, chromium-, gold- and nickel-coated mirrors have been adopted in the vacuum ultraviolet and soft X-ray branch beamline BL-13B at the Photon Factory in Tsukuba, Japan. Carbon contamination on the chromium-coated mirror was almost completely removed by exposure to oxygen at a pressure of 8 × 10{sup −2} Pa for 1 h under irradiation of non-monochromated synchrotron radiation. The pressure in the chamber recovered to the order of 10{sup −7} Pa within a few hours. The reflectivity of the chromium-coated mirror of the second-order harmonics in the carbon K-edge region (560–660 eV) was found to be a factor of 0.1–0.48 smaller than that of the gold-coated mirror.
Brazhnikov, D. V.; Novokreshchenov, A. S.
2017-04-01
The effect of a double structure of saturated absorption resonance in the field of counterpropagating light waves interacting with an atomic gas is studied. The experimental observation of this effect was first reported in 2011 in a work by our colleagues at the P.N. Lebedev Physical Institute of the Russian Academy of Sciences (Laboratory of Frequency Standards). The essence of the effect lies in the fact that, on exciting an open dipole transition, another, narrower, resonance of an opposite sign can be observed at the center of the ordinary saturated absorption resonance. A theoretical analysis of this effect has also been performed in this work in terms of a simple spectroscopic model of an atom with two nondegenerate energy levels without taking into account higher spatial harmonics of atomic polarization and polarizations of light waves (scalar model). The present work is devoted to the development of a theory of the formation of a central narrow resonance for the example of a real F g = 1 → F e = 1 atomic transition and to the study of its main characteristics (amplitude, width, contrast, and amplitude-to-width ratio). In addition, the theoretical results obtained without taking into account the influence of higher spatial harmonics and with inclusion of the influence of first higher harmonics are compared. This comparison shows that their influence on the parameters of the new nonlinear resonance is strong even in moderately intense light fields ( R γ, where R is the Rabi frequency). The results of this study can be of interest for quantum metrology, as well as for many experiments in which the laser-radiation frequency is stabilized by the saturated absorption resonance on open dipole transitions in atoms and molecules.
Blanco, Esteban
2016-01-01
A superconducting 800 MHz second harmonic RF system is one of the considered options as a Landau damping mechanism for HiLumi LHC. The Higher Order Mode (HOM) coupler designs require tight manufacturing tolerances in order to operate at the design specifications. The project consists of defining the mechanical tolerances for the different components of both the probe-type and hook-type HOM coupler. With the use of electromagnetic field simulation software it is possible to identify the critical components of the HOM coupler and to quantify their respective tolerances. The obtained results are discussed in this paper.
Directory of Open Access Journals (Sweden)
Manuel Kasper
2016-05-01
Full Text Available We developed an impedance quartz crystal microbalance (QCM approach with the ability to simultaneously record mass changes and calibrated energy dissipation with high sensitivity using an impedance analyzer. This impedance QCM measures frequency shifts and resistance changes of sensing quartz crystals very stable, accurately, and calibrated, thus yielding quantitative information on mass changes and dissipation. Resistance changes below 0.3 Ω were measured with corresponding dissipation values of 0.01 µU (micro dissipation units. The broadband impedance capabilities allow measurements between 20 Hz and 120 MHz including higher harmonic modes of up to 11th order for a 10 MHz fundamental resonance frequency quartz crystal. We demonstrate the adsorbed mass, calibrated resistance, and quantitative dissipation measurements on two biological systems including the high affinity based avidin-biotin interaction and nano-assemblies of polyelectrolyte layers. The binding affinity of a protein-antibody interaction was determined. The impedance QCM is a versatile and simple method for accurate and calibrated resistance and dissipation measurements with broadband measurement capabilities for higher harmonics measurements.
Weavers, Paul T; Tao, Shengzhen; Trzasko, Joshua D; Shu, Yunhong; Tryggestad, Erik J; Gunter, Jeffrey L; McGee, Kiaran P; Litwiller, Daniel V; Hwang, Ken-Pin; Bernstein, Matt A
2017-05-01
Spatial position accuracy in magnetic resonance imaging (MRI) is an important concern for a variety of applications, including radiation therapy planning, surgical planning, and longitudinal studies of morphologic changes to study neurodegenerative diseases. Spatial accuracy is strongly influenced by gradient linearity. This work presents a method for characterizing the gradient non-linearity fields on a per-system basis, and using this information to provide improved and higher-order (9th vs. 5th) spherical harmonic coefficients for better spatial accuracy in MRI. A large fiducial phantom containing 5229 water-filled spheres in a grid pattern is scanned with the MR system, and the positions all the fiducials are measured and compared to the corresponding ground truth fiducial positions as reported from a computed tomography (CT) scan of the object. Systematic errors from off-resonance (i.e., B0) effects are minimized with the use of increased receiver bandwidth (±125kHz) and two acquisitions with reversed readout gradient polarity. The spherical harmonic coefficients are estimated using an iterative process, and can be subsequently used to correct for gradient non-linearity. Test-retest stability was assessed with five repeated measurements on a single scanner, and cross-scanner variation on four different, identically-configured 3T wide-bore systems. A decrease in the root-mean-square error (RMSE) over a 50cm diameter spherical volume from 1.80mm to 0.77mm is reported here in the case of replacing the vendor's standard 5th order spherical harmonic coefficients with custom fitted 9th order coefficients, and from 1.5mm to 1mm by extending custom fitted 5th order correction to the 9th order. Minimum RMSE varied between scanners, but was stable with repeated measurements in the same scanner. The results suggest that the proposed methods may be used on a per-system basis to more accurately calibrate MR gradient non-linearity coefficients when compared to vendor
Energy Technology Data Exchange (ETDEWEB)
Eliazar, Iddo, E-mail: eliazar@post.tau.ac.il
2017-05-15
The exponential, the normal, and the Poisson statistical laws are of major importance due to their universality. Harmonic statistics are as universal as the three aforementioned laws, but yet they fall short in their ‘public relations’ for the following reason: the full scope of harmonic statistics cannot be described in terms of a statistical law. In this paper we describe harmonic statistics, in their full scope, via an object termed harmonic Poisson process: a Poisson process, over the positive half-line, with a harmonic intensity. The paper reviews the harmonic Poisson process, investigates its properties, and presents the connections of this object to an assortment of topics: uniform statistics, scale invariance, random multiplicative perturbations, Pareto and inverse-Pareto statistics, exponential growth and exponential decay, power-law renormalization, convergence and domains of attraction, the Langevin equation, diffusions, Benford’s law, and 1/f noise. - Highlights: • Harmonic statistics are described and reviewed in detail. • Connections to various statistical laws are established. • Connections to perturbation, renormalization and dynamics are established.
Investigation of an Ultrafast Harmonic Resonant RF Kicker
Energy Technology Data Exchange (ETDEWEB)
Huang, Yulu [Univ. of Chinese Academy of Sciences (CAS), Beijing (China)
2016-10-01
square pulse, and get a Flat-Top waveform which will give a uniform kick over the bunch length of the kicked electron bunches, thus the transverse emittance of these kicked electron bunches can be maintained. By using two identical kickers with the betatron phase advance of 180 degree or its odd multiples, the residual kick voltage wave slopes at the unkicked bunch position will be totally cancelled out. Flat-Top waveform combined with two kicker scheme, the transverse emittance of the cooling electron bunches will be conserved during the whole injection, recirculation, and ejection processes. In the cavity design part, firstly, the cavity geometry is optimized to get high transverse shunt impedance thus less than 100 W of RF losses on the cavity wall can be achieved for all these 10 harmonic modes. To support all these 10 harmonic modes, group of four QWRs are adopted with the mode distribution of 5:3:1:1. In the multi-frequency cavities such as the five-mode-cavity and the three-mode-cavity, tunings are required to achieve the design frequencies for each mode. Slight segments of taper design on the inner conductor help to get the frequencies to be exactly on the odd harmonic modes. Stub tuners equal to the number of resonant modes are inserted to the outer conductor wall to compensate the frequency shifts due manufacturing errors and other perturbations during the operation such as the change of the cavity temperature. Single loop couple is designed for all harmonic modes in each cavity. By adjusting its loop size, position and rotation, it is possible to get the fundamental mode critical coupled and other higher harmonic modes slightly over coupled. A broadband circulator will be considered for absorbing the reflected power. Finally in this part, multipole field components due to the asymmetric cylindrical structure around the beam axis of the cavity as well as the beam-induced higher order mode (HOM) issues will be analyzed and discussed in this thesis. A half
SEVENTH HARMONIC 20 GHz CO-GENERATOR
Energy Technology Data Exchange (ETDEWEB)
Hirshfield, Jay L
2014-04-08
To satisfy the need for multi-MW rf sources in frequency ranges where commercial sources do not exist, a study was undertaken on a class of devices based on gyro-harmonic frequency multiplication. This mechanism relies upon adding energy in gyrating motion to a linear electron beam that traverses a rotating-mode TE111-mode drive cavity in a dc magnetic field. The beam then drifts along the magnetic field into a second cavity, operating in the TEn11-mode tuned to the nth harmonic of the drive cavity. Studies of this configuration have been carried out for 2 < n < 7. Results are given for multi-MW, efficient operation of a 7th harmonic device operating at 20 GHz, and a 2nd harmonic device operating at 22.4 GHz.
Directory of Open Access Journals (Sweden)
Farhad A. Namin
2016-08-01
Full Text Available A rigorous method for obtaining the diffraction patterns of quasicrystals is presented. Diffraction patterns are an essential analytical tool in the study of quasicrystals, since they can be used to determine their photonic resonances. Previous methods for approximating the diffraction patterns of quasicrystals have relied on evaluating the Fourier transform of finite-sized super-lattices. Our approach, on the other hand, is exact in the sense that it is based on a technique that embeds quasicrystals into higher dimensional periodic hyper-lattices, thereby completely capturing the properties of the infinite structure. The periodicity of the unit cell in the higher dimensional space can be exploited to obtain the Fourier series expansion in closed-form of the corresponding atomic surfaces. The utility of the method is demonstrated by applying it to one-dimensional Fibonacci and two-dimensional Penrose quasicrystals. The results are verified by comparing them to those obtained by using the conventional super-lattice method. It is shown that the conventional super-cell approach can lead to inaccurate results due to the continuous nature of the Fourier transform, since quasicrystals have a discrete spectrum, whereas the approach introduced in this paper generates discrete Fourier harmonics. Furthermore, the conventional approach requires very large super-cells and high-resolution sampling of the reciprocal space in order to produce accurate results leading to a very large computational burden, whereas the proposed method generates accurate results with a relatively small number of terms. Finally, we propose how this approach can be generalized from the vertex model, which assumes identical particles at all vertices, to a more realistic case where the quasicrystal is composed of different atoms.
Wamsat, T
2014-01-01
converter RTMs (5GHz and 9GHz) and a third RTM with two phase locked loop synthesizers on board for LO generation. Presently the 5GHz and the PLL RTMs are under construction. The first measurements with these cards will be presented.
Harmonic ratcheting for fast acceleration
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N. Cook
2014-04-01
Full Text Available A major challenge in the design of rf cavities for the acceleration of medium-energy charged ions is the need to rapidly sweep the radio frequency over a large range. From low-power medical synchrotrons to high-power accelerator driven subcritical reactor systems, and from fixed focus alternating gradient accelerators to rapid cycling synchrotrons, there is a strong need for more efficient, and faster, acceleration of protons and light ions in the semirelativistic range of hundreds of MeV/u. A conventional way to achieve a large, rapid frequency sweep (perhaps over a range of a factor of 6 is to use custom-designed ferrite-loaded cavities. Ferrite rings enable the precise tuning of the resonant frequency of a cavity, through the control of the incremental permeability that is possible by introducing a pseudoconstant azimuthal magnetic field. However, rapid changes over large permeability ranges incur anomalous behavior such as the “Q-loss” and “f-dot” loss phenomena that limit performance while requiring high bias currents. Notwithstanding the incomplete understanding of these phenomena, they can be ameliorated by introducing a “harmonic ratcheting” acceleration scheme in which two or more rf cavities take turns accelerating the beam—one turns on when the other turns off, at different harmonics—so that the radio frequency can be constrained to remain in a smaller range. Harmonic ratcheting also has straightforward performance advantages, depending on the particular parameter set at hand. In some typical cases it is possible to halve the length of the cavities, or to double the effective gap voltage, or to double the repetition rate. This paper discusses and quantifies the advantages of harmonic ratcheting in general. Simulation results for the particular case of a rapid cycling medical synchrotron ratcheting from harmonic number 9 to 2 show that stability and performance criteria are met even when realistic engineering details
Quantum frequency doubling based on tripartite entanglement with cavities
Juan, Guo; Zhi-Feng, Wei; Su-Ying, Zhang
2016-02-01
We analyze the entanglement characteristics of three harmonic modes, which are the output fields from three cavities with an input tripartite entangled state at fundamental frequency. The entanglement properties of the input beams can be maintained after their frequencies have been up-converted by the process of second harmonic generation. We have calculated the parametric dependences of the correlation spectrum on the initial squeezing factor, the pump power, the transmission coefficient, and the normalized analysis frequency of cavity. The numerical results provide references to choose proper experimental parameters for designing the experiment. The frequency conversion of the multipartite entangled state can also be applied to a quantum communication network. Project supported by the National Natural Science Foundation of China (Grant No. 91430109), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20111401110004), and the Natural Science Foundation of Shanxi Province, China (Grant No. 2014011005-3).
Coherent harmonic production using a two-section undulator FEL
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Jaroszynski, D.A. [Commissariat a l`Energie, Bruyeres-le-Chatel (France); Prazeres, R.; Glotin, F. [Centre Universitaire Paris-Sud (France)] [and others
1995-12-31
We present measurements and a theoretical analysis of a new method of generating harmonic radiation in a free-electron laser oscillator with a two section undulator in a single optical cavity. To produce coherent harmonic radiation the undulator is arranged so that the downstream undulator section resonance frequency matches a harmonic of the upstream undulator. Both the fundamental and the harmonic optical fields evolve in the same optical cavity and are coupled out with different extraction fractions using a hole in one of the cavity mirrors. We present measurements that show that the optical power at the second and third harmonic can be enhanced by more than an order of magnitude in this fundamental/harmonic configuration. We compare the production of harmonic radiation of a two sectioned fundamental/harmonic undulator with that produced from a FEL operating at its highest efficiency with a step-tapered undulator, where the bunching at the end of the first section is very large. We examine, the dependence of the harmonic power on the intracavity power by adjusting the optical cavity desynchronism, {delta}L. We also examine the evolution of the fundamental and harmonic powers as a function of cavity roundtrip number to evaluate the importance of the small signal gain at the harmonic. We compare our measurements with predictions of a multi-electron numerical model that follows the evolution of fundamental and harmonic power to saturation. This fundamental/harmonic mode, of operation of the FEL may have useful applications in the production of coherent X-ray and VUV radiation, a spectral range where high reflectivity optical cavity mirrors are difficult or impossible to manufacture.
Indian Academy of Sciences (India)
Harish-Chandra, Gelfand and several other mathematicians and physicists, group-theoretic harmonic analysis is a flourishing industry today paving the way to new developments in the con- text of noncompact Lie groups as well as quantum groups. Since B(n, z) = zn the expansion (3) suggests a link between Fourier series.
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 10. Harmonic Analysis Fourier Series and Beyond. K R Parthasarathy. Book Review Volume 1 Issue 10 October 1996 pp 87-91. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/001/10/0087-0091 ...
Bennett, Charles L [Livermore, CA
2009-10-20
A high efficiency harmonic engine based on a resonantly reciprocating piston expander that extracts work from heat and pressurizes working fluid in a reciprocating piston compressor. The engine preferably includes harmonic oscillator valves capable of oscillating at a resonant frequency for controlling the flow of working fluid into and out of the expander, and also preferably includes a shunt line connecting an expansion chamber of the expander to a buffer chamber of the expander for minimizing pressure variations in the fluidic circuit of the engine. The engine is especially designed to operate with very high temperature input to the expander and very low temperature input to the compressor, to produce very high thermal conversion efficiency.
Lee, Chong-Yong; Bullock, John P; Kennedy, Gareth F; Bond, Alan M
2010-09-23
Large-amplitude ac voltammograms contain a wealth of kinetic information concerning electrode processes and can provide unique mechanistic insights compared to other techniques. This paper describes the effects homogeneous chemical processes have on ac voltammetry in general and provides experimental examples using two well-known chemical systems: one simple and one complex. Oxidation of [Cp*Fe(CO)(2)](2) (Cp* = η(5)-pentamethylcyclopentadienyl) in noncoordinating media is a reversible one-electron process; in the presence of nucleophiles, however, the resulting ligand-induced disproportionation changes the process to a multiple step regeneration. The chemical kinetic parameters of the regeneration mechanism were discerned via analysis of the third and higher harmonics of Fourier-transformed ac voltammetry data. Comparison of experimental data to digital simulations provides clear evidence that the reaction proceeds via a rapid pre-equilibrium between the electrogenerated monocation and the coordinating ligand; simultaneous fitting of the first nine harmonics indicates that k(f) = 7500 M(-1) s(-1) and k(r) = 100 s(-1), and that the unimolecular decomposition of the corresponding intermediate occurs with a rate constant of 2.2 s(-1). The rapid cis(+) → trans(+) isomerization of the electrogenerated cis-[W(CO)(2)(dpe)(2)](+), where dpe = 1,2-diphenylphosphinoethane, was examined to illustrate the effects of a simpler EC mechanism on the higher harmonics; a rate constant of 280 s(-1) was determined. These results not only shed new light on the chemistry of these systems, but provide a clear demonstration that the higher harmonics of ac voltammetry provide mechanistic insights into coupled homogeneous processes far more detailed than those that are readily accessible with dc techniques.
Bennett, Charles L.; Sewall, Noel; Boroa, Carl
2014-08-19
An engine based on a reciprocating piston engine that extracts work from pressurized working fluid. The engine includes a harmonic oscillator inlet valve capable of oscillating at a resonant frequency for controlling the flow of working fluid into of the engine. In particular, the inlet valve includes an inlet valve head and a spring arranged together as a harmonic oscillator so that the inlet valve head is moveable from an unbiased equilibrium position to a biased closed position occluding an inlet. Upon releasing the inlet valve the inlet valve head undergoes a single oscillation past the equilibrium positio to a maximum open position and returns to a biased return position close to the closed position to choke the flow and produce a pressure drop across the inlet valve causing the inlet valve to close. Protrusions carried either by the inlet valve head or piston head are used to bump open the inlet valve from the closed position and initiate the single oscillation of the inlet valve head, and protrusions carried either by the outlet valve head or piston head are used to close the outlet valve ahead of the bump opening of the inlet valve.
Helson, Henry
2010-01-01
This second edition has been enlarged and considerably rewritten. Among the new topics are infinite product spaces with applications to probability, disintegration of measures on product spaces, positive definite functions on the line, and additional information about Weyl's theorems on equidistribution. Topics that have continued from the first edition include Minkowski's theorem, measures with bounded powers, idempotent measures, spectral sets of bounded functions and a theorem of Szego, and the Wiener Tauberian theorem. Readers of the book should have studied the Lebesgue integral, the elementary theory of analytic and harmonic functions, and the basic theory of Banach spaces. The treatment is classical and as simple as possible. This is an instructional book, not a treatise. Mathematics students interested in analysis will find here what they need to know about Fourier analysis. Physicists and others can use the book as a reference for more advanced topics.
Studies of higher-order flow harmonics in PbPb collisions at 2.76 TeV with CMS
Tuo, Shengquan
2012-01-01
High-order Fourier harmonics ($v_n$, $n > 2$) in the azimuthal distributions of charged particles produced in PbPb collisions at a nucleon-nucleon centre-of-mass energy $\\sqrt{s_{_{NN}}}$ = 2.76 TeV are presented. The $v_n$ coefficients are studied using the event-plane method and a Fourier decomposition analysis of the two particle correlations in various collision centrality, $p_{T}$ and $\\eta$ ranges. A unique measurement of $v_n$ in the ultra-central collisions (UCC) is performed using the long-range component of the two particle correlations. These data provide strong constraints on the theoretical models of the initial condition in heavy ion collisions and the transport properties of the produced medium.
Phononic High Harmonic Generation
Ganesan, Adarsh; Do, Cuong; Seshia, Ashwin A.
2016-01-01
This paper reports the first experimental evidence for phononic low-order to high-order harmonic conversion leading to high harmonic generation. Similar to parametric resonance, phononic high harmonic generation is also mediated by a threshold dependent instability of a driven phonon mode. Once the threshold for instability is met, a cascade of harmonic generation processes is triggered. Firstly, the up-conversion of first harmonic phonons into second harmonic phonons is established. Subseque...
Directory of Open Access Journals (Sweden)
Piotr FOLĘGA
2014-03-01
Full Text Available The variety of types and sizes currently in production harmonic drive is a problem in their rational choice. Properly selected harmonic drive must meet certain requirements during operation, and achieve the anticipated service life. The paper discusses the problems associated with the selection of the harmonic drive. It also presents the algorithm correct choice of harmonic drive. The main objective of this study was to develop a computer program that allows the correct choice of harmonic drive by developed algorithm.
Harmonic polynomials, hyperspherical harmonics, and atomic spectra
Avery, John Scales
2010-01-01
The properties of monomials, homogeneous polynomials and harmonic polynomials in d-dimensional spaces are discussed. The properties are shown to lead to formulas for the canonical decomposition of homogeneous polynomials and formulas for harmonic projection. Many important properties of spherical harmonics, Gegenbauer polynomials and hyperspherical harmonics follow from these formulas. Harmonic projection also provides alternative ways of treating angular momentum and generalised angular momentum. Several powerful theorems for angular integration and hyperangular integration can be derived in this way. These purely mathematical considerations have important physical applications because hyperspherical harmonics are related to Coulomb Sturmians through the Fock projection, and because both Sturmians and generalised Sturmians have shown themselves to be extremely useful in the quantum theory of atoms and molecules.
On the inside of the cavity there is a layer of niobium. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment.
Energy Technology Data Exchange (ETDEWEB)
Perez, Israel, E-mail: iperez@mda.cinvestav.m [Applied Physics Department, Cinvestav Unidad Merida, Km 6 Ant., Carretera a Progreso, A.P. 73, C.P. 97310, Merida, Yucatan (Mexico); Sosa, Victor [Applied Physics Department, Cinvestav Unidad Merida, Km 6 Ant., Carretera a Progreso, A.P. 73, C.P. 97310, Merida, Yucatan (Mexico); Gamboa, Fidel, E-mail: ffgamboa@mda.cinvestav.m [Applied Physics Department, Cinvestav Unidad Merida, Km 6 Ant., Carretera a Progreso, A.P. 73, C.P. 97310, Merida, Yucatan (Mexico); Physics of Materials Department, Centro de Investigacion en Materiales Avanzados, S.C. (CIMAV) Ave. Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua (Mexico)
2010-12-01
We have applied the mutual inductive method to study higher-order harmonics of complex ac susceptibility {chi}{sub n}={chi}{sub n}{sup '}-i{chi}{sub n}{sup ''} for YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} thin films as function of the temperature and the applied magnetic field. The experimental results were compared with analytical and numerical results obtained from the Ishida-Mazaki model and the solution of the integral equation for the current density, respectively. Both models allow us to reproduce the main experimental features, however, as n increases the numerical model shows notable discrepancies. This failure can be attributed to the current-voltage characteristics. Also this investigation yields the activation energy U{sub c} and the critical current density J{sub c} both at T = 0 for two samples.
Superconducting TESLA cavities
Aune, B.; Bandelmann, R.; Bloess, D.; Bonin, B.; Bosotti, A.; Champion, M.; Crawford, C.; Deppe, G.; Dwersteg, B.; Edwards, D. A.; Edwards, H. T.; Ferrario, M.; Fouaidy, M.; Gall, P.-D.; Gamp, A.; Gössel, A.; Graber, J.; Hubert, D.; Hüning, M.; Juillard, M.; Junquera, T.; Kaiser, H.; Kreps, G.; Kuchnir, M.; Lange, R.; Leenen, M.; Liepe, M.; Lilje, L.; Matheisen, A.; Möller, W.-D.; Mosnier, A.; Padamsee, H.; Pagani, C.; Pekeler, M.; Peters, H.-B.; Peters, O.; Proch, D.; Rehlich, K.; Reschke, D.; Safa, H.; Schilcher, T.; Schmüser, P.; Sekutowicz, J.; Simrock, S.; Singer, W.; Tigner, M.; Trines, D.; Twarowski, K.; Weichert, G.; Weisend, J.; Wojtkiewicz, J.; Wolff, S.; Zapfe, K.
2000-09-01
The conceptional design of the proposed linear electron-positron collider TESLA is based on 9-cell 1.3 GHz superconducting niobium cavities with an accelerating gradient of Eacc>=25 MV/m at a quality factor Q0>=5×109. The design goal for the cavities of the TESLA Test Facility (TTF) linac was set to the more moderate value of Eacc>=15 MV/m. In a first series of 27 industrially produced TTF cavities the average gradient at Q0 = 5×109 was measured to be 20.1+/-6.2 MV/m, excluding a few cavities suffering from serious fabrication or material defects. In the second production of 24 TTF cavities, additional quality control measures were introduced, in particular, an eddy-current scan to eliminate niobium sheets with foreign material inclusions and stringent prescriptions for carrying out the electron-beam welds. The average gradient of these cavities at Q0 = 5×109 amounts to 25.0+/-3.2 MV/m with the exception of one cavity suffering from a weld defect. Hence only a moderate improvement in production and preparation techniques will be needed to meet the ambitious TESLA goal with an adequate safety margin. In this paper we present a detailed description of the design, fabrication, and preparation of the TESLA Test Facility cavities and their associated components and report on cavity performance in test cryostats and with electron beam in the TTF linac. The ongoing research and development towards higher gradients is briefly addressed.
1988-01-01
The pulse of a particle accelerator. 128 of these radio frequency cavities were positioned around CERN's 27-kilometre LEP ring to accelerate electrons and positrons. The acceleration was produced by microwave electric oscillations at 352 MHz. The electrons and positrons were grouped into bunches, like beads on a string, and the copper sphere at the top stored the microwave energy between the passage of individual bunches. This made for valuable energy savings as it reduced the heat generated in the cavity.
1995-01-01
Engineers work in a clean room on one of the superconducting cavities for the upgrade to the LEP accelerator, known as LEP-2. The use of superconductors allow higher electric fields to be produced so that higher beam energies can be reached.
Harmonic Morphisms Projecting Harmonic Functions to Harmonic Functions
Mustafa, M. T.
2012-01-01
For Riemannian manifolds $M$ and $N$ , admitting a submersion $\\varphi $ with compact fibres, we introduce the projection of a function via its decomposition intohorizontal and vertical components. By comparing the Laplacians on $M$ and $N$ , we determine conditions under which a harmonic function on $U={\\varphi }^{-1}(V)\\subset M$ projects down, via its horizontal component, to a harmonic function on $V\\subset N$ .
Heemink, Arnold; de Jong, B.; Prins, Harrie
1991-01-01
In this paper we describe a new approach to the harmonic analysis of the tide. For a number of reasons the harmonic constants are not really constant but vary slowly in time. Therefore, we introduce a narrow-band noise process to model the time-varying behaviour of these harmonic parameters.
TAX HARMONIZATION VERSUS FISCAL COMPETITION
Directory of Open Access Journals (Sweden)
Florin Alexandru MACSIM
2016-12-01
Full Text Available Recent years have brought into discussion once again subjects like tax harmonization and fiscal competition. Every time the European Union tends to take a step forward critics enter the scene and give contrary arguments to European integration. Through this article we have offered our readers a compelling view over the “battle” between tax harmonization and fiscal competition. While tax harmonization has key advantages as less costs regarding public revenues, leads to higher degree of integration and allows the usage of fiscal transfers between regions, fiscal competition is no less and presents key advantages as high reductions in tax rates and opens a large path for new investments, especially FDI. Choosing tax harmonization or fiscal competition depends on a multitude of variables, of circumstances, the decision of choosing one path or the other being ultimately influenced by the view of central and local authorities. Our analysis indicates that if we refer to a group of countries that are a part of a monetary union or that form a federation, tax harmonization seems to be the best path to choose. Moving the analysis to a group of regions that aren’t taking any kind of correlated actions or that have not signed any major treaties regarding monetary or fiscal policies, the optimal solution is fiscal competition.
Axler, Sheldon; Ramey, Wade
2013-01-01
This is a book about harmonic functions in Euclidean space. Readers with a background in real and complex analysis at the beginning graduate level will feel comfortable with the material presented here. The authors have taken unusual care to motivate concepts and simplify proofs. Topics include: basic properties of harmonic functions, Poisson integrals, the Kelvin transform, spherical harmonics, harmonic Hardy spaces, harmonic Bergman spaces, the decomposition theorem, Laurent expansions, isolated singularities, and the Dirichlet problem. The new edition contains a completely rewritten chapter on spherical harmonics, a new section on extensions of Bocher's Theorem, new exercises and proofs, as well as revisions throughout to improve the text. A unique software package-designed by the authors and available by e-mail - supplements the text for readers who wish to explore harmonic function theory on a computer.
Redesign of the End Group in the 3.9 GHz LCLS-II Cavity
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Lunin, Andrei [Fermilab; Gonin, Ivan [Fermilab; Khabiboulline, Timergali [Fermilab; Solyak, Nikolay [Fermilab
2017-05-01
Development and production of Linac Coherent Light Source II (LCLS-II) is underway. The central part of LCLS-II is a continuous wave superconducting RF (CW SCRF) electron linac. The 3.9 GHz third harmonic cavity similar to the XFEL design will be used in LCLS-II for linearizing the longitudinal beam profile*. The initial design of the 3.9 GHz cavity developed for XFEL project has a large, 40 mm, beam pipe aperture for better higher-order mode (HOM) damping. It is resulted in dipole HOMs with frequencies nearby the operating mode, which causes difficulties with HOM coupler notch filter tuning. The CW linac operation requires an extra caution in the design of the HOM coupler in order to prevent its possible overheating. In this paper we present the modified 3.9 GHz cavity End Group for meeting the LCLS-II requirements
Control of ring lasers by means of coupled cavities
DEFF Research Database (Denmark)
Abitan, Haim; Andersen, Ulrik Lund; Skettrup, Torben
2000-01-01
different configurations we can control the out-coupling from the ring laser thereby influencing the threshold and the circulating power in the different ring cavities. This may be used to obtain the best balance between the passive losses and a nonlinear loss such as e.g. conversion to the second harmonic......Summary form only. Coupling of optical cavities offers a means of controlling the properties of one cavity (e.g. a laser) by making adjustments to another, external cavity. In this contribution we consider a unidirectional ring laser (bow-tie laser) coupled to an external ring cavity. Using...
Multi-Mode Cavity Accelerator Structure
Energy Technology Data Exchange (ETDEWEB)
Jiang, Yong [Yale Univ., New Haven, CT (United States); Hirshfield, Jay Leonard [Omega-P R& D, Inc., New Haven, CT (United States)
2016-11-10
This project aimed to develop a prototype for a novel accelerator structure comprising coupled cavities that are tuned to support modes with harmonically-related eigenfrequencies, with the goal of reaching an acceleration gradient >200 MeV/m and a breakdown rate <10^{-7}/pulse/meter. Phase I involved computations, design, and preliminary engineering of a prototype multi-harmonic cavity accelerator structure; plus tests of a bimodal cavity. A computational procedure was used to design an optimized profile for a bimodal cavity with high shunt impedance and low surface fields to maximize the reduction in temperature rise ΔT. This cavity supports the TM010 mode and its 2nd harmonic TM011 mode. Its fundamental frequency is at 12 GHz, to benchmark against the empirical criteria proposed within the worldwide High Gradient collaboration for X-band copper structures; namely, a surface electric field E_{sur}^{max}< 260 MV/m and pulsed surface heating ΔT^{max}< 56 °K. With optimized geometry, amplitude and relative phase of the two modes, reductions are found in surface pulsed heating, modified Poynting vector, and total RF power—as compared with operation at the same acceleration gradient using only the fundamental mode.
Plasmonic-cavity model for radiating nano-rod antennas
DEFF Research Database (Denmark)
Peng, Liang; Mortensen, N. Asger
2014-01-01
In this paper, we propose the analytical solution of nano-rod antennas utilizing a cylindrical harmonics expansion. By treating the metallic nano-rods as plasmonic cavities, we derive closed-form expressions for both the internal and the radiated fields, as well as the resonant condition and the ......In this paper, we propose the analytical solution of nano-rod antennas utilizing a cylindrical harmonics expansion. By treating the metallic nano-rods as plasmonic cavities, we derive closed-form expressions for both the internal and the radiated fields, as well as the resonant condition...... and the radiation efficiency. With our theoretical model, we show that besides the plasmonic resonances, efficient radiation takes advantage of (a) rendering a large value of the rods' radius and (b) a central-fed profile, through which the radiation efficiency can reach up to 70% and even higher in a wide...... frequency band. Our theoretical expressions and conclusions are general and pave the way for engineering and further optimization of optical antenna systems and their radiation patterns....
Soft-x-ray harmonic comb from relativistic electron spikes.
Pirozhkov, A S; Kando, M; Esirkepov, T Zh; Gallegos, P; Ahmed, H; Ragozin, E N; Faenov, A Ya; Pikuz, T A; Kawachi, T; Sagisaka, A; Koga, J K; Coury, M; Green, J; Foster, P; Brenner, C; Dromey, B; Symes, D R; Mori, M; Kawase, K; Kameshima, T; Fukuda, Y; Chen, L; Daito, I; Ogura, K; Hayashi, Y; Kotaki, H; Kiriyama, H; Okada, H; Nishimori, N; Imazono, T; Kondo, K; Kimura, T; Tajima, T; Daido, H; Rajeev, P; McKenna, P; Borghesi, M; Neely, D; Kato, Y; Bulanov, S V
2012-03-30
We demonstrate a new high-order harmonic generation mechanism reaching the "water window" spectral region in experiments with multiterawatt femtosecond lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving μJ/sr pulses. Harmonics are collectively emitted by an oscillating electron spike formed at the joint of the boundaries of a cavity and bow wave created by a relativistically self-focusing laser in underdense plasma. The spike sharpness and stability are explained by catastrophe theory. The mechanism is corroborated by particle-in-cell simulations.
A Survey of Coronal Cavity Density Profiles
Fuller, J.; Gibson, S. E.
2009-08-01
Coronal cavities are common features of the solar corona that appear as darkened regions at the base of coronal helmet streamers in coronagraph images. Their darkened appearance indicates that they are regions of lowered density embedded within the comparatively higher density helmet streamer. Despite interfering projection effects of the surrounding helmet streamer (which we refer to as the cavity rim), Fuller et al. have shown that under certain conditions it is possible to use a Van de Hulst inversion of white-light polarized brightness (pB) data to calculate the electron density of both the cavity and cavity rim plasma. In this article, we apply minor modifications to the methods of Fuller et al. in order to improve the accuracy and versatility of the inversion process, and use the new methods to calculate density profiles for both the cavity and cavity rim in 24 cavity systems. We also examine trends in cavity morphology and how departures from the model geometry affect our density calculations. The density calculations reveal that in all 24 cases the cavity plasma has a flatter density profile than the plasma of the cavity rim, meaning that the cavity has a larger density depletion at low altitudes than it does at high altitudes. We find that the mean cavity density is over four times greater than that of a coronal hole at an altitude of 1.2 R sun and that every cavity in the sample is over twice as dense as a coronal hole at this altitude. Furthermore, we find that different cavity systems near solar maximum span a greater range in density at 1.2 R sun than do cavity systems near solar minimum, with a slight trend toward higher densities for systems nearer to solar maximum. Finally, we found no significant correlation of cavity density properties with cavity height—indeed, cavities show remarkably similar density depletions—except for the two smallest cavities that show significantly greater depletion.
High-harmonic generation in amorphous solids.
You, Yong Sing; Yin, Yanchun; Wu, Yi; Chew, Andrew; Ren, Xiaoming; Zhuang, Fengjiang; Gholam-Mirzaei, Shima; Chini, Michael; Chang, Zenghu; Ghimire, Shambhu
2017-09-28
High-harmonic generation in isolated atoms and molecules has been widely utilized in extreme ultraviolet photonics and attosecond pulse metrology. Recently, high-harmonic generation has been observed in solids, which could lead to important applications such as all-optical methods to image valance charge density and reconstruct electronic band structures, as well as compact extreme ultraviolet light sources. So far these studies are confined to crystalline solids; therefore, decoupling the respective roles of long-range periodicity and high density has been challenging. Here we report the observation of high-harmonic generation from amorphous fused silica. We decouple the role of long-range periodicity by comparing harmonics generated from fused silica and crystalline quartz, which contain the same atomic constituents but differ in long-range periodicity. Our results advance current understanding of the strong-field processes leading to high-harmonic generation in solids with implications for the development of robust and compact extreme ultraviolet light sources.Although higher harmonic generation from solids has become of interest in many fields, its observation is typically limited to crystalline solids. Here, the authors demonstrate that higher harmonics can be generated from amorphous solids.
Cavity-mirror degradation in the deep-UV FEL
Energy Technology Data Exchange (ETDEWEB)
Yamada, K.; Yamazaki, T.; Sei, N. [Electrotechnical Lab., Ibaraki (Japan)] [and others
1995-12-31
It is known that the degradation of dielectric multilayer mirrors used in short wavelength free-electron lasers (FELs) is caused by the carbon contamination on the mirror surface and the defects inside the dielectrics. We reported last year that the degraded dielectric multilayer mirrors can be repaired with both surface treatment by RF-induced oxygen plasma and thermal annealing. However, such a mirror degradation is still one of the most critical issues in the deep ultraviolet (UV) FELs, because the fundamental undulator radiation resonating in the laser cavity, the intensity of which is much higher than that of higher harmonics, can be sufficiently energetic to cause the mirror degradation through photochemical reactions. We are investigating the mirror degradation mainly in the deep UV region down to 240 nm. The experimental results will be shown. The mirror degradation mechanism will be discussed.
Measuring Spherical Harmonic Coefficients on a Sphere
Energy Technology Data Exchange (ETDEWEB)
Pollaine, S; Haan, S W
2003-05-16
The eigenfunctions of Rayleigh-Taylor modes on a spherical capsule are the spherical harmonics Y{sub l,m} These can be measured by measuring the surface perturbations along great circles and fitting them to the first few modes by a procedure described in this article. For higher mode numbers, it is more convenient to average the Fourier power spectra along the great circles, and then transform them to spherical harmonic modes by an algorithm derived here.
Theory and technology for superconducting cavities
Lengeler, Herbert
1993-01-01
The course will address Physicist and Engineers who are newcomers in the field of accelerators and accelerating cavities. The elements of RF-Superconductivity will be presented with special relevance to accelerating cavities. The present ststus of achievable accelerating fields and RF losses will be given and their link to the special technologies for cavity fabrication and surface treatments will be stressed. Cavity auxiliaries like main couplers, higher order mode couplers and frequency tuners will be described.
Characteristics of pulse width for an enhanced second harmonic generation
Zhang, Yun; Hyodo, Masaharu; Okada-Shudo, Yoshiko; Zhu, Yun; Wang, Xiaoyang; Zhu, Yong; Wang, Guiling; Chen, Chuangtian; Watanabe, Shuntaro; Watanabe, Masayoshi
2017-03-01
Temporal characteristics of a cavity enhancement second harmonic (SH) generation for picosecond laser pulse are investigated. We experimentally measured pulse width changes that were indued by group velocity mismatching (GVM), SH process, and enhancement cavity. It indicates that the generated pulse width is a combined effect of the GVM and SH process. Meanwhile, the effect of the enhancement cavity can be avoided by controlling its free spectrum range. A interferometric autocorrelator with a KBBF-PCD as nonlinear crystal is also composed and this extends the measurement light wavelength below 410 nm.
Mechanical Properties of Niobium Cavities
Energy Technology Data Exchange (ETDEWEB)
Ciovati, Gianluigi [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Dhakal, Pashupati [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Matalevich, Joseph R. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Myneni, Ganapati Rao [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
2015-09-01
The mechanical stability of bulk Nb cavity is an important aspect to be considered in relation to cavity material, geometry and treatments. Mechanical properties of Nb are typically obtained from uniaxial tensile tests of small samples. In this contribution we report the results of measurements of the resonant frequency and local strain along the contour of single-cell cavities made of ingot and fine-grain Nb of different purity subjected to increasing uniform differential pressure, up to 6 atm. Measurements have been done on cavities subjected to different heat treatments. Good agreement between finite element analysis simulations and experimental data in the elastic regime was obtained with a single set of values of Young’s modulus and Poisson’s ratio. The experimental results indicate that the yield strength of medium-purity ingot Nb cavities is higher than that of fine-grain, high-purity Nb.
Technical tasks in superconducting cavities
Energy Technology Data Exchange (ETDEWEB)
Saito, Kenji [High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan)
1997-11-01
The feature of superconducting rf cavities is an extremely small surface resistance on the wall. It brings a large energy saving in the operation, even those are cooled with liquid helium. That also makes possible to operate themselves in a higher field gradient comparing to normal conducting cavities, and brings to make accelerators compact. These merits are very important for the future accelerator engineering which is planed at JAERI for the neutron material science and nuclear waste transmutation. This machine is a high intensity proton linac and uses sc cavities in the medium and high {beta} sections. In this paper, starting R and D of proton superconducting cavities, several important technical points which come from the small surface resistance of sc cavities, are present to succeed it and also differences between the medium and high - {beta} structures are discussed. (author)
W.H. van Boom (Willem)
2009-01-01
textabstractThis paper presents a review of the literature on comparative tort law and economics. It pays special attention to the economics arguments against and in favour of harmonization of tort law in Europe.
Chen, Shigao; Kinnick, Randall R; Greenleaf, James F; Fatemi, Mostafa
2007-07-01
Vibro-acoustography is an imaging method that uses the radiation force of two interfering ultrasound beams of slightly different frequency to probe an object. An image is made using the acoustic emission resulted from the object vibration at the difference frequency. In this paper, the feasibility of imaging objects at twice the difference frequency (harmonic acoustic emission) is studied. Several possible origins of harmonic acoustic emission are explored. As an example, it is shown that microbubbles close to resonance can produce significant harmonic acoustic emission due to its high nonlinearity. Experiments demonstrate that, compared to the fundamental acoustic emission, harmonic acoustic emission greatly improves the contrast between microbubbles and other objects in vibro-acoustography (an improvement of 17-23 dB in these experiments). Applications of this technique include imaging the nonlinearity of the object and selective detection of microbubbles for perfusion imaging. The impact of microbubble destruction during the imaging process also is discussed.
RF Design of Normal Conducting 704 MHz and 2.1 GHz Cavities for LEReC Linac
Energy Technology Data Exchange (ETDEWEB)
Xiao, Binping [Brookhaven Natl. Lab.; Belomestnykh, Sergey [SUNY, Stony Brook; Ben-Zvi, Ilan [RIKEN BNL; Blaskiewicz, Michael [RIKEN BNL; Brennan, Joseph [RIKEN BNL; Brutus, Jean Clifford [RIKEN BNL; Fedotov, Alexei [RIKEN BNL; Hahn, Harald [Brookhaven; McIntyre, Gary [RIKEN BNL; Pai, Chien [RIKEN BNL; Smith, Kevin [RIKEN BNL; Tuozzolo, Joseph [RIKEN BNL; Veshcherevich, Vadim [Cornell U., CLASSE; Wu, Qiong [RIKEN BNL; Xin, Tianmu [RIKEN BNL; Xu, Wencan [RIKEN BNL; Zaltsman, Alex [RIKEN BNL
2016-06-01
To improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, the Low Energy RHIC electron Cooler (LEReC) is currently under development at BNL. Two normal conducting cavities, a single cell 704 MHz cavity and a 3 cell 2.1 GHz third harmonic cavity, will be used in LEReC for energy spread correction. Currently these two cavities are under fabrication. In this paper we report the RF design of these two cavities.
Resonant second harmonic generation in a gallium nitride two-dimensional photonic crystal on silicon
Energy Technology Data Exchange (ETDEWEB)
Zeng, Y.; Roland, I.; Checoury, X.; Han, Z.; El Kurdi, M.; Sauvage, S.; Boucaud, P., E-mail: philippe.boucaud@ief.u-psud.fr [Institut d' Electronique Fondamentale, CNRS - Univ. Paris Sud 11, Bâtiment 220, F-91405 Orsay (France); Gayral, B. [Univ. Grenoble Alpes, INAC-SP2M, CEA-CNRS group Nanophysique et Semiconducteurs, F-38000 Grenoble (France); CEA, INAC-SP2M, CEA-CNRS group Nanophysique et Semiconducteurs, F-38000 Grenoble (France); Brimont, C.; Guillet, T. [Université Montpellier 2, Laboratoire Charles Coulomb UMR 5221, F-34905 Montpellier (France); Mexis, M.; Semond, F. [CRHEA-CNRS, Rue Bernard Grégory, F-06560 Valbonne (France)
2015-02-23
We demonstrate second harmonic generation in a gallium nitride photonic crystal cavity embedded in a two-dimensional free-standing photonic crystal platform on silicon. The photonic crystal nanocavity is optically pumped with a continuous-wave laser at telecom wavelengths in the transparency window of the nitride material. The harmonic generation is evidenced by the spectral range of the emitted signal, the quadratic power dependence vs. input power, and the spectral dependence of second harmonic signal. The harmonic emission pattern is correlated to the harmonic polarization generated by the second-order nonlinear susceptibilities χ{sub zxx}{sup (2)}, χ{sub zyy}{sup (2)} and the electric fields of the fundamental cavity mode.
DEFF Research Database (Denmark)
Nielsen, Jesper Kjær; Jensen, Tobias Lindstrøm; Jensen, Jesper Rindom
2017-01-01
The harmonic chirp signal model has only very recently been in- troduced for modelling approximately periodic signals with a time- varying fundamental frequency. A number of estimators for the pa- rameters of this model have already been proposed, but they are ei- ther inaccurate, non-robust to n......The harmonic chirp signal model has only very recently been in- troduced for modelling approximately periodic signals with a time- varying fundamental frequency. A number of estimators for the pa- rameters of this model have already been proposed, but they are ei- ther inaccurate, non......-robust to noise, or very computationally inten- sive. In this paper, we propose a fast algorithm for the harmonic chirp summation method which has been demonstrated in the liter- ature to be accurate and robust to noise. The proposed algorithm is orders of magnitudes faster than previous algorithms which is also...
Bennett, Charles L.
2016-03-22
A reciprocating-piston uniflow engine includes a harmonic oscillator inlet valve capable of oscillating at a resonant frequency for controlling the flow of working fluid into the engine. In particular, the inlet valve includes an inlet valve head and a spring arranged together as a harmonic oscillator so that the inlet valve head is moveable from an unbiased equilibrium position to a biased closed position occluding an inlet. When released, the inlet valve head undergoes a single oscillation past the equilibrium position to a maximum open position and returns to a biased return position close to the closed position to choke the flow and produce a pressure drop across the inlet valve causing the inlet valve to close. In other embodiments, the harmonic oscillator arrangement of the inlet valve enables the uniflow engine to be reversibly operated as a uniflow compressor.
Second harmonic generation imaging
2013-01-01
Second-harmonic generation (SHG) microscopy has shown great promise for imaging live cells and tissues, with applications in basic science, medical research, and tissue engineering. Second Harmonic Generation Imaging offers a complete guide to this optical modality, from basic principles, instrumentation, methods, and image analysis to biomedical applications. The book features contributions by experts in second-harmonic imaging, including many pioneering researchers in the field. Written for researchers at all levels, it takes an in-depth look at the current state of the art and possibilities of SHG microscopy. Organized into three sections, the book: Provides an introduction to the physics of the process, step-by-step instructions on how to build an SHG microscope, and comparisons with related imaging techniques Gives an overview of the capabilities of SHG microscopy for imaging tissues and cells—including cell membranes, muscle, collagen in tissues, and microtubules in live cells—by summarizing experi...
Neck dissection with harmonic scalpel and electrocautery? A randomised study.
Verma, Roshan K; Mathiazhagan, Arulalan; Panda, Naresh K
2017-10-01
Is the use of harmonic scalpel for neck dissection useful? Literature search did not show a single, prospective, randomised control trial. We intended to study the role of harmonic scalpel in neck dissection and compare it with conventional electrocautery technique for oral cavity carcinoma. 40 patients undergoing selective neck dissection for primary oral cavity malignancy were enrolled in this study. The harmonic scalpel (HS) group consisted of 20 patients, and the electrocautery technique (ET) group comprised of 20 patients. The following variables were examined: intraoperative blood loss, operative time, number of ligatures used, postoperative drain, and postoperative hospital stay. Intraoperative blood loss was found to be significantly reduced in harmonic scalpel group as compared to electrocautery group. However, we found no difference in other parameters like operative time, postop drain, postoperative hospital stay and number of ligatures used between both groups. Harmonic scalpel for neck dissection is associated with significantly lesser intraoperative blood loss as compared to electrocautery. There is no effect on operative time and postoperative hospital stay in both groups. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
General Criterion for Harmonicity
Proesmans, Karel; Vandebroek, Hans; Van den Broeck, Christian
2017-10-01
Inspired by Kubo-Anderson Markov processes, we introduce a new class of transfer matrices whose largest eigenvalue is determined by a simple explicit algebraic equation. Applications include the free energy calculation for various equilibrium systems and a general criterion for perfect harmonicity, i.e., a free energy that is exactly quadratic in the external field. As an illustration, we construct a "perfect spring," namely, a polymer with non-Gaussian, exponentially distributed subunits which, nevertheless, remains harmonic until it is fully stretched. This surprising discovery is confirmed by Monte Carlo and Langevin simulations.
Harmonic arbitrary waveform generator
Energy Technology Data Exchange (ETDEWEB)
Roberts, Brock Franklin
2017-11-28
High frequency arbitrary waveforms have applications in radar, communications, medical imaging, therapy, electronic warfare, and charged particle acceleration and control. State of the art arbitrary waveform generators are limited in the frequency they can operate by the speed of the Digital to Analog converters that directly create their arbitrary waveforms. The architecture of the Harmonic Arbitrary Waveform Generator allows the phase and amplitude of the high frequency content of waveforms to be controlled without taxing the Digital to Analog converters that control them. The Harmonic Arbitrary Waveform Generator converts a high frequency input, into a precision, adjustable, high frequency arbitrary waveform.
Quantum harmonically kicked environments
Custódio, M. S.; Strunz, W. T.; Beims, M. W.
2017-11-01
In this work we derive a generalized map which describes the time evolution of a quantum system coupled to a quantum environment composed by a finite number of free particles kicked harmonically at periodic times. Dissipation is introduced via the interaction between system and environment, which is switched on and off simultaneously at regular time intervals. The dynamics of the environmental particles occurs along rotated ellipsis in phase space and can be described by unrotated harmonic oscillators with a new frequency which depends on the kicking time. With the definition of a thermal bath we show that our quantum kicked environment induces an unusual fluctuation-dissipation relation.
Booster Double Harmonic Setup Notes
Energy Technology Data Exchange (ETDEWEB)
Gardner, C. J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.
2015-02-17
The motivation behind implementing a booster double harmonic include the reduced transverse space charge force from a reduced peak beam current and reduced momentum spread of the beam, both of which can be achieved from flattening the RF bucket. RF capture and acceleration of polarized protons (PP) is first set up in the single harmonic mode with RF harmonic h=1. Once capture and acceleration have been set up in the single harmonic mode, the second harmonic system is brought on and programmed to operate in concert with the single harmonic system.
Segmented trapped vortex cavity
Grammel, Jr., Leonard Paul (Inventor); Pennekamp, David Lance (Inventor); Winslow, Jr., Ralph Henry (Inventor)
2010-01-01
An annular trapped vortex cavity assembly segment comprising includes a cavity forward wall, a cavity aft wall, and a cavity radially outer wall there between defining a cavity segment therein. A cavity opening extends between the forward and aft walls at a radially inner end of the assembly segment. Radially spaced apart pluralities of air injection first and second holes extend through the forward and aft walls respectively. The segment may include first and second expansion joint features at distal first and second ends respectively of the segment. The segment may include a forward subcomponent including the cavity forward wall attached to an aft subcomponent including the cavity aft wall. The forward and aft subcomponents include forward and aft portions of the cavity radially outer wall respectively. A ring of the segments may be circumferentially disposed about an axis to form an annular segmented vortex cavity assembly.
Harmonic Intravascular Ultrasound
M.E. Frijlink (Martijn)
2006-01-01
textabstractMedical ultrasound is a popular imaging modality in cardiology. Harmonic Imaging is a technique that has been shown to increase the image quality of diagnostic ultrasound at frequencies below 10 MHz. However, Intravascular Ultrasound, which is a technique to acoustically investigate
Harmonic Orientation of Pulse Width Modulation Technique in Multilevel Inverters
Urmila Bandaru; Subba D Rayudu
2011-01-01
The Multilevel Inverter topology gives the advantages of usage in high power and high voltage application with reduced harmonic distortion without a transformer. This paper presents a comparative study of orientation of higher ordered harmonics with increase in switching frequency around the frequency modulation index of nine level diode clamped inverter for different Switching frequency Multicarrier Pulse width Modulation.
Calaga, R; Burt, G; Ratti, A
2015-01-01
The HL-LHC upgrade will use deflecting (or crab) cavities to compensate for geometric luminosity loss at low β* and non-zero crossing angle. A local scheme with crab cavity pairs across the IPs is used employing compact crab cavities at 400 MHz. Design of the cavities, the cryomodules and the RF system is well advanced. The LHC crab cavities will be validated initially with proton beam in the SPS.
Young children's harmonic perception.
Costa-Giomi, Eugenia
2003-11-01
Harmony and tonality are two of the most difficult elements for young children to perceive and manipulate and are seldom taught in the schools until the end of early childhood. Children's gradual harmonic and tonal development has been attributed to their cumulative exposure to Western tonal music and their increasing experiential knowledge of its rules and principles. Two questions that are relevant to this problem are: (1) Can focused and systematic teaching accelerate the learning of the harmonic/tonal principles that seem to occur in an implicit way throughout childhood? (2) Are there cognitive constraints that make it difficult for young children to perceive and/or manipulate certain harmonic and tonal principles? A series of studies specifically addressed the first question and suggested some possible answers to the second one. Results showed that harmonic instruction has limited effects on children's perception of harmony and indicated that the drastic improvement in the perception of implied harmony noted approximately at age 9 is due to development rather than instruction. I propose that young children's difficulty in perceiving implied harmony stems from their attention behaviors. Older children have less memory constraints and more strategies to direct their attention to the relevant cues of the stimulus. Younger children focus their attention on the melody, if present in the stimulus, and specifically on its concrete elements such as rhythm, pitch, and contour rather than its abstract elements such as harmony and key. The inference of the abstract harmonic organization of a melody required in the perception of implied harmony is thus an elusive task for the young child.
Harmonic Patterns in Forex Trading
Nemček, Sebastian
2013-01-01
This diploma thesis is committed to examination of validity of Harmonic Patterns in Forex trading. Scott Carney described existing and introduced new Harmonic Patterns in 1999 in his book Harmonic Trader. These patterns use the Fibonacci principle to analyze price action and to provide both bullish and bearish trading signals. The goal of this thesis is to find out whether harmonic trading strategy on selected pairs is profitable in FX market, which patterns are the most profitable and what i...
Harmonic analysis of Doubly Fed Induction Generators
DEFF Research Database (Denmark)
Lindholm, Morten; Rasmussen, Tonny Wederberg
2003-01-01
This paper gives an overview of the frequency spectrum of the stator and rotor currents in a doubly fed induction generator (DFIG) used in wind power applications. The paper also presents a method to eliminate higher harmonics and interharmonics in the DFIG stator current. The method is implemented...
Recursive Harmonic Numbers and Binomial Coefficients
Maw, Aung Phone; Kyaw, Aung
2017-01-01
We define recursive harmonic numbers as a generalization of harmonic numbers. The table of recursive harmonic numbers, which is like Pascal's triangle, is constructed. A formula for recursive harmonic numbers containing binomial coefficients is also presented.
Principles of harmonic analysis
Deitmar, Anton
2014-01-01
This book offers a complete and streamlined treatment of the central principles of abelian harmonic analysis: Pontryagin duality, the Plancherel theorem and the Poisson summation formula, as well as their respective generalizations to non-abelian groups, including the Selberg trace formula. The principles are then applied to spectral analysis of Heisenberg manifolds and Riemann surfaces. This new edition contains a new chapter on p-adic and adelic groups, as well as a complementary section on direct and projective limits. Many of the supporting proofs have been revised and refined. The book is an excellent resource for graduate students who wish to learn and understand harmonic analysis and for researchers seeking to apply it.
Observing the Unobservable? Modeling Coronal Cavity Densities
Fuller, J.; Gibson, S. E.; de Toma, G.; Fan, Y.
2008-05-01
Prominence cavities in coronal helmet streamers are readily detectable in white-light coronagraph images, yet their interpretation may be complicated by projection effects. In order to determine a cavity's density structure, it is essential to quantify the contribution of noncavity features along the line of sight. We model the coronal cavity as an axisymmetric torus that encircles the Sun at constant latitude and fit it to observations of a white-light cavity observed by the Mauna Loa Solar Observatory (MLSO) MK4 coronagraph from 2006 January 25 to 30. We demonstrate that spurious noncavity contributions (including departures from axisymmetry) are minimal enough to be incorporated in a density analysis as conservatively estimated uncertainties in the data. We calculate a radial density profile for cavity material and for the surrounding helmet streamer (which we refer to as the "cavity rim") and find that the cavity density is depleted by a maximum of 40% compared to the surrounding helmet streamer at low altitudes (1.18 R⊙) but is consistently higher (double or more) than in coronal holes. We also find that the relative density depletion between cavity and surrounding helmet decreases as a function of height. We show that both increased temperature in the cavity relative to the surrounding helmet streamer and a magnetic flux rope configuration might lead to such a flattened density profile. Finally, our model provides general observational guidelines that can be used to determine when a cavity is sufficiently unobstructed to be a good candidate for plasma diagnostics.
Harmonics in transmission power systems
DEFF Research Database (Denmark)
Wiechowski, Wojciech Tomasz
Some time ago, Energinet.dk, the Transmission System Operator of the 150 kV and 400 kV transmission network in Denmark, had experienced operational malfunctions of some of the measuring and protection equipment. Also an overloading of a harmonic filter has been reported, and therefore, a need...... to perform more detailed harmonic studies emerged. Since the transmission network has a complex structure and its impedance varies with frequency in a nonlinear fashion, such harmonic study would require a detailed computer model of the network. Consequently, a PhD project proposal titled "Harmonics......, provided that background harmonic distortion, and the network configuration, are not changing during the measurement. It is shown that switching of a shunt linear power system component can result in variation of the harmonic levels that can be measured and used to verify the harmonic model of the network...
Harmonic and geometric analysis
Citti, Giovanna; Pérez, Carlos; Sarti, Alessandro; Zhong, Xiao
2015-01-01
This book presents an expanded version of four series of lectures delivered by the authors at the CRM. Harmonic analysis, understood in a broad sense, has a very wide interplay with partial differential equations and in particular with the theory of quasiconformal mappings and its applications. Some areas in which real analysis has been extremely influential are PDE's and geometric analysis. Their foundations and subsequent developments made extensive use of the Calderón–Zygmund theory, especially the Lp inequalities for Calderón–Zygmund operators (Beurling transform and Riesz transform, among others) and the theory of Muckenhoupt weights. The first chapter is an application of harmonic analysis and the Heisenberg group to understanding human vision, while the second and third chapters cover some of the main topics on linear and multilinear harmonic analysis. The last serves as a comprehensive introduction to a deep result from De Giorgi, Moser and Nash on the regularity of elliptic partial differen...
Rebuild of Capture Cavity 1 at Fermilab
Energy Technology Data Exchange (ETDEWEB)
Harms, E. [Fermilab; Arkan, T. [Fermilab; Borissov, E. [Fermilab; Dhanaraj, N. [Fermilab; Hocker, A. [Fermilab; Orlov, Y. [Fermilab; Peterson, T. [Fermilab; Premo, K. [Fermilab
2014-01-01
The front end of the proposed Advanced Superconducting Test Accelerator at Fermilab employs two single cavity cryomodules, known as 'Capture Cavity 1' and 'Capture Cavity 2', for the first stage of acceleration. Capture Cavity 1 was previously used as the accelerating structure for the A0 Photoinjector to a peak energy of ~14 MeV. In its new location a gradient of ~25 MV/m is required. This has necessitated a major rebuild of the cryomodule including replacement of the cavity with a higher gradient one. Retrofitting the cavity and making upgrades to the module required significant redesign. The design choices and their rationale, summary of the rebuild, and early test results are presented.
Transfer functions of US transducers for harmonic imaging and bubble respons
van Neer, Paul L.M.J.; Matte, Guillaume; Sijl, J.; Borsboom, Jerome M.G.; de Jong, N.
2007-01-01
Current medical diagnostic echo systems are mostly using harmonic imaging. This means that a fundamental frequency (e.g., 2 MHz) is transmitted and the reflected and scattered higher harmonics (e.g., 4 and 6 MHz), produced by nonlinear propagation, are recorded. The signal level of these harmonics
Harmonic sums and polylogarithms generated by cyclotomic polynomials
Energy Technology Data Exchange (ETDEWEB)
Ablinger, Jakob; Schneider, Carsten [Johannes Kepler Univ., Linz (Austria). Research Inst. for Symbolic Computation; Bluemlein, Johannes [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2011-05-15
The computation of Feynman integrals in massive higher order perturbative calculations in renormalizable Quantum Field Theories requires extensions of multiply nested harmonic sums, which can be generated as real representations by Mellin transforms of Poincare-iterated integrals including denominators of higher cyclotomic polynomials. We derive the cyclotomic harmonic polylogarithms and harmonic sums and study their algebraic and structural relations. The analytic continuation of cyclotomic harmonic sums to complex values of N is performed using analytic representations. We also consider special values of the cyclotomic harmonic polylogarithms at argument x=1, resp., for the cyclotomic harmonic sums at N{yields}{infinity}, which are related to colored multiple zeta values, deriving various of their relations, based on the stuffle and shuffle algebras and three multiple argument relations. We also consider infinite generalized nested harmonic sums at roots of unity which are related to the infinite cyclotomic harmonic sums. Basis representations are derived for weight w=1,2 sums up to cyclotomy l=20. (orig.)
Parvini, T. S.; Tehranchi, M. M.; Hamidi, S. M.
2017-07-01
An effective method is proposed to design finite one-dimensional photonic crystal cavities (PhCCs) as robust high-efficient frequency converter. For this purpose, we consider two groups of PhCCs which are constructed by stacking m nonlinear (LiNbO3) and n linear (air) layers with variable thicknesses. In the first group, the number of linear layers is less than the nonlinear layers by one and in the second group by two. The conversion efficiency is calculated as a function of the arrangement and thicknesses of the linear and nonlinear layers by benefiting from nonlinear transfer matrix method. Our numerical simulations show that for each group of PhCCs, there is a structural formula by which the configurations with the highest efficiency can be constructed for any values of m and n (i.e. any number of layers). The efficient configurations are equivalent to Fabry-Pérot cavities that depend on the relationship between m and n and the mirrors in two sides of these cavities can be periodic or nonperiodic. The conversion efficiencies of these designed PhCCs are more than 5 orders of magnitude higher than the perfect ones which satisfy photonic bandgap edge and quasi-phase matching. Moreover, the results reveal that conversion efficiencies of Fabry-Pérot cavities with non-periodic mirrors are one order of magnitude higher than those with periodic mirrors. The major physical mechanisms of the enhancement are quasi-phase matching effect, cavity effect induced by dispersive mirrors, and double resonance for the pump and the harmonic fields in defect state. We believe that this method is very beneficial to the design of high-efficient compact optical frequency converters.
A radiofrequency (RF) cavity is a metallic chamber that contains an electromagnetic field. Its primary purpose is to accelerate charged particles. RF cavities can be structured like beads on a string, where the beads are the cavities and the string is the beam pipe of a particle accelerator, through which particles travel in a vacuum.
Gamp, A
2011-01-01
We begin by giving a description of the rf generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, rf feedback, and feed-forward are described. Examples of digital rf phase and amplitude control for the special case of superconducting cavities are also given. Finally, a dedicated phase loop for damping synchrotron oscillations is discussed.
Energy Technology Data Exchange (ETDEWEB)
Ganeev, R A [Ophthalmology and Advanced Laser Medical Center, Saitama Medical University, Saitama 350-0495 (Japan)
2015-09-30
We discuss the emergence of interest in the high-order harmonic generation (HHG) of ultrashort pulses propagated through laser-produced plasmas. It is shown that, during the last few years, substantial amendments of plasma HHG allowed in some cases the characteristics of gas HHG to be surpassed. The attractiveness of a new approach in coherent extreme ultraviolet radiation generation is demonstrated, which can also be used as a tool for laser-ablation-induced HHG spectroscopy of a giant class of solids. We present general ideas and prospects for this relatively new field of nonlinear optics. (review)
Harmonic analysis and applications
Heil, Christopher
2007-01-01
This self-contained volume in honor of John J. Benedetto covers a wide range of topics in harmonic analysis and related areas. These include weighted-norm inequalities, frame theory, wavelet theory, time-frequency analysis, and sampling theory. The chapters are clustered by topic to provide authoritative expositions that will be of lasting interest. The original papers collected are written by prominent researchers and professionals in the field. The book pays tribute to John J. Benedetto's achievements and expresses an appreciation for the mathematical and personal inspiration he has given to
Injector Cavities Fabrication, Vertical Test Performance and Primary Cryomodule Design
Energy Technology Data Exchange (ETDEWEB)
Wang, Haipeng [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Cheng, Guangfeng [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Clemens, William [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Davis, G [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Macha, Kurt [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Overton, Roland [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Spell, D. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
2015-09-01
After the electromagnetic design and the mechanical design of a β=0.6, 2-cell elliptical SRF cavity, the cavity has been fabricated. Then both 2-cell and 7-cell cavities have been bench tuned to the target values of frequency, coupling external Q and field flatness. After buffer chemistry polishing (BCP) and high pressure rinses (HPR), Vertical 2K cavity test results have been satisfied the specifications and ready for the string assembly. We will report the cavity performance including Lorenz Force Detuning (LFD) and Higher Order Modes (HOM) damping data. Its integration with cavity tuners to the cryomodule design will be reported.
Novel Geometries for the LHC CRAB Cavity
Hall, Ben
2010-01-01
In 2017 the LHC is envisioned to increase its luminosity via an upgrade. This upgrade is likely to require a large crossing angle hence a crab cavity is required to align the bunches prior to collision. There are two possible schemes for crab cavity implementation, global and local. In a global crab cavity the crab cavity is far from the IP and the bunch rotates back and forward as it traverses around the accelerator in a closed orbit. For this scheme a two-cell elliptical squashed cavity at 800 MHz is preferred. To avoid any potential beam instabilities all the parasitic modes of the cavities must be damped strongly, however crab cavities have lower order and same order modes in addition to the usual higher order modes and hence a novel damping scheme must be used to provide sufficient damping of these modes. In the local scheme two crab cavities are placed at each side of the IP two start and stop rotation of the bunches. This would require crab cavities much smaller transversely than in the global scheme b...
DEFF Research Database (Denmark)
Lodahl, P.; Saffman, M.
1999-01-01
fundamental field, and its coupling to a pair of nondegenerate parametric fields. The parametric fields are driven by the nonresonant second-harmonic field. Analysis indicates the existence of transverse instability of the pump field alone, as well as the possibility of simultaneous instability of the pump......We theoretically investigate the generation of spatial patterns in intracavity second-harmonic generation. We consider a cavity with planar mirrors that is resonant at the fundamental frequency, but not at the second-harmonic frequency. A mean-field model is derived that describes the resonant...
Harmonic Series Meets Fibonacci Sequence
Chen, Hongwei; Kennedy, Chris
2012-01-01
The terms of a conditionally convergent series may be rearranged to converge to any prescribed real value. What if the harmonic series is grouped into Fibonacci length blocks? Or the harmonic series is arranged in alternating Fibonacci length blocks? Or rearranged and alternated into separate blocks of even and odd terms of Fibonacci length?
The LHC superconducting cavities
Boussard, Daniel; Häbel, E; Kindermann, H P; Losito, R; Marque, S; Rödel, V; Stirbet, M
1999-01-01
The LHC RF system, which must handle high intensity (0.5 A d.c.) beams, makes use of superconducting single-cell cavities, best suited to minimizing the effects of periodic transient beam loading. There will be eight cavities per beam, each capable of delivering 2 MV (5 MV/m accelerating field) at 400 MHz. The cavities themselves are now being manufactured by industry, using niobium-on-copper technology which gives full satisfaction at LEP. A cavity unit includes a helium tank (4.5 K operating temperature) built around a cavity cell, RF and HOM couplers and a mechanical tuner, all housed in a modular cryostat. Four-unit modules are ultimately foreseen for the LHC (two per beam), while at present a prototype version with two complete units is being extensively tested. In addition to a detailed description of the cavity and its ancillary equipment, the first test results of the prototype will be reported.
Directory of Open Access Journals (Sweden)
Zimmermann, Elise
2009-06-01
Full Text Available Introduction: The myopericytomas represent about 1% of the vascular tumors, is relatively common in the region of head and neck, 25% of the cases, and uncommon in the nasal and paranasal cavities. Objective: To describe one case of myopericytoma in nasal cavity. Case Report: We present a case of an adult patient, of the female sex, with complaints of nasal obstruction, pain in the nasal cavities region and eventual epistaxis in the right nasal cavity, which present an angiomatous and easily bleeding, non-pulsatile mass occupying all the right nasal cavity. Final Considerations: The myopericytomas are uncommon vascular tumors, rarely located in the nasal cavity and in the paranasal sinuses. They must be included in the differential diagnosis of the well delimited, vascular and slow growth masses upon computed tomography.
Long term dynamics of the high luminosity Large Hadron Collider with crab cavities
Barranco García, J.; De Maria, R.; Grudiev, A.; Tomás García, R.; Appleby, R. B.; Brett, D. R.
2016-10-01
The High Luminosity upgrade of the Large Hadron Collider (HL-LHC) aims to achieve an integrated luminosity of 200 - 300 fb-1 per year, including the contribution from the upgrade of the injector chain. For the HL-LHC the larger crossing angle together with a smaller beta function at the collision point would result in more than 70% luminosity loss due to the incomplete geometric overlap of colliding bunches. To recover head-on collisions at the high-luminosity particle-physics detectors ATLAS and CMS and benefit from the very low β* provided by the Achromatic Telescopic Squeezing (ATS) optics, a local crab cavity scheme provides transverse kicks to the proton bunches. The tight space constraints at the location of these cavities leads to designs which are axially non-symmetric, giving rise to high order multipoles components of the main deflecting mode and, since these kicks are harmonic in time, we expand them in a series of multipoles in a similar fashion as is done for static field magnets. In this work we calculate, for the first time, the higher order multipoles and their impact on beam dynamics for three different crab cavity prototypes. Different approaches to calculate the multipoles are presented. Furthermore, we perform the first calculation of their impact on the long term stability of the machine using the concept of dynamic aperture.
Long term dynamics of the high luminosity Large Hadron Collider with crab cavities
Directory of Open Access Journals (Sweden)
J. Barranco García
2016-10-01
Full Text Available The High Luminosity upgrade of the Large Hadron Collider (HL-LHC aims to achieve an integrated luminosity of 200–300 fb^{-1} per year, including the contribution from the upgrade of the injector chain. For the HL-LHC the larger crossing angle together with a smaller beta function at the collision point would result in more than 70% luminosity loss due to the incomplete geometric overlap of colliding bunches. To recover head-on collisions at the high-luminosity particle-physics detectors ATLAS and CMS and benefit from the very low β^{*} provided by the Achromatic Telescopic Squeezing (ATS optics, a local crab cavity scheme provides transverse kicks to the proton bunches. The tight space constraints at the location of these cavities leads to designs which are axially non-symmetric, giving rise to high order multipoles components of the main deflecting mode and, since these kicks are harmonic in time, we expand them in a series of multipoles in a similar fashion as is done for static field magnets. In this work we calculate, for the first time, the higher order multipoles and their impact on beam dynamics for three different crab cavity prototypes. Different approaches to calculate the multipoles are presented. Furthermore, we perform the first calculation of their impact on the long term stability of the machine using the concept of dynamic aperture.
Physics of tissue harmonic imaging by ultrasound
Jing, Yuan
Tissue Harmonic Imaging (THI) is an imaging modality that is currently deployed on diagnostic ultrasound scanners. In THI the amplitude of the ultrasonic pulse that is used to probe the tissue is large enough that the pulse undergoes nonlinear distortion as it propagates into the tissue. One result of the distortion is that as the pulse propagates energy is shifted from the fundamental frequency of the source pulse into its higher harmonics. These harmonics will scatter off objects in the tissue and images formed from the scattered higher harmonics are considered to have superior quality to the images formed from the fundamental frequency. Processes that have been suggested as possibly responsible for the improved imaging in THI include: (1) reduced sensitivity to reverberation, (2) reduced sensitivity to aberration, and (3) reduction in side lobes. By using a combination of controlled experiments and numerical simulations, these three reasons have been investigated. A single element transducer and a clinical ultrasound scanner with a phased array transducer were used to image a commercial tissue-mimicking phantom with calibrated targets. The higher image quality achieved with THI was quantified in terms of spatial resolution and "clutter" signals. A three-dimensional model of the forward propagation of nonlinear sound beams in media with arbitrary spatial properties (a generalized KZK equation) was developed. A time-domain code for solving the KZK equation was validated with measurements of the acoustic field generated by the single element transducer and the phased array transducer. The code was used to investigate the impact of aberration using tissue-like media with three-dimensional variations in all acoustic properties. The three-dimensional maps of tissue properties were derived from the datasets available through the Visible Female project. The experiments and simulations demonstrated that second harmonic imaging (1) suffers less clutter associated with
Directory of Open Access Journals (Sweden)
Mamatha T
2011-11-01
Full Text Available Objectives: Knowledge of the shape and dimensions of the glenoid are important in the design and fitting of glenoid components for total shoulder arthroplasty. An understanding of variations in normal anatomy of the glenoid is essential while evaluating pathological conditions like osseous Bankart lesions and osteochondral defects. Methods: This study was done on 202 dry, unpaired adult human scapulae of unknown sex belonging to the south Indian population. Three glenoid diameters were measured, the superior-inferior diameter, anterior-posterior diameter of the lower half and the anterior-posterior diameter of the upper half of the glenoid. Based on a notch present on the anterior glenoid rim, variations in the shape of the glenoid cavity were classified as inverted comma shaped, pear shaped and oval. Results: The average superior-inferior diameter on right and the left sides were 33.67±2.82mm and 33.92±2.87mm respectively. The average anterior-posterior diameter of the lower half of the right glenoid was 23.35±2.04mm and that of the left was 23.02±2.30mm. The mean diameter of the upper half of the right glenoid was 16.27±2.01mm and that of the left was 15.77±1.96mm. Conclusion: The dimensions of the glenoid observed in the present study were lesser than those recorded in the studies done on other populations. This fact may be taken into consideration while designing glenoid prostheses for the south Indian population. The current study recorded a higher percentage of glenoid cavities having the glenoid notch as compared to earlier studies. While evaluating defects/lesions of the glenoid, this fact could be useful.
Multi-MW 22.8 GHz Harmonic Multiplier - RF Power Source for High-Gradient Accelerator R&D
Energy Technology Data Exchange (ETDEWEB)
Jay L. Hirshfield
2012-07-26
Electrodynamic and particle simulation studies have been carried out to optimize design of a two-cavity harmonic frequency multiplier, in which a linear electron beam is energized by rotating fields near cyclotron resonance in a TE111 cavity in a uniform magnetic field, and in which the beam then radiates coherently at the nth harmonic into a TEn11 output cavity. Examples are worked out in detail for 7th and 2nd harmonic converters, showing RF-to-RF conversion efficiencies of 45% and 88%, respectively at 19.992 GHz (K-band) and 5.712 GHz (C-band), for a drive frequency of 2.856 GHz. Details are shown of RF infrastructure (S-band klystron, modulator) and harmonic converter components (drive cavity, output cavities, electron beam source and modulator, beam collector) for the two harmonic converters to be tested. Details are also given for the two-frequency (S- and C-band) coherent multi-MW test stand for RF breakdown and RF gun studies.
Optically measuring interior cavities
Stone, Gary Franklin
2008-12-21
A method of measuring the three-dimensional volume or perimeter shape of an interior cavity includes the steps of collecting a first optical slice of data that represents a partial volume or perimeter shape of the interior cavity, collecting additional optical slices of data that represents a partial volume or perimeter shape of the interior cavity, and combining the first optical slice of data and the additional optical slices of data to calculate of the three-dimensional volume or perimeter shape of the interior cavity.
Quantum description of radiative decay in optical cavities
Oppermann, J.; Straubel, J.; Słowik, K.; Rockstuhl, C.
2018-01-01
We derive the quantum mechanical description of light-matter interactions in optical cavities characterized solely by radiative decay. Unique to radiative decay is the conservation of photon number and coherence, in stark contrast to absorptive losses. This prohibits the description of such cavities by traditional means, e.g., coupling it to a bath of harmonic oscillators into which energy is dissipated. Here, we propose a description of cavities with radiative decay by introducing cavity and noise operators in terms of scattering modes. A multimode input-output formalism to predict measurable far field quantities arises naturally. We apply our general model to the special case of the single excitation regime. We find dynamics reminiscent of the dissipative Jaynes-Cummings model, but with vanishing backaction and a rich temporal and spectral structure of the output modes.
Proposed Cavity for Reduced Slip-Stacking Loss
Energy Technology Data Exchange (ETDEWEB)
Eldred, J. [Indiana U.; Zwaska, R. [Fermilab
2015-06-01
This paper employs a novel dynamical mechanism to improve the performance of slip-stacking. Slip-stacking in an accumulation technique used at Fermilab since 2004 which nearly double the proton intensity. During slip-stacking, the Recycler or the Main Injector stores two particles beams that spatially overlap but have different momenta. The two particle beams are longitudinally focused by two 53 MHz 100 kV RF cavities with a small frequency difference between them. We propose an additional 106 MHz 20 kV RF cavity, with a frequency at the double the average of the upper and lower main RF frequencies. In simulation, we find the proposed RF cavity significantly enhances the stable bucket area and reduces slip-stacking losses under reasonable injection scenarios. We quantify and map the stability of the parameter space for any accelerator implementing slip-stacking with the addition of a harmonic RF cavity.
Bessel-Gauss beam enhancement cavities for high-intensity applications.
Putnam, William P; Schimpf, Damian N; Abram, Gilberto; Kärtner, Franz X
2012-10-22
We introduce Bessel-Gauss beam enhancement cavities that may circumvent the major obstacles to more efficient cavity-enhanced high-field physics such as high-harmonic generation. The basic properties of Bessel-Gauss beams are reviewed and their transformation properties through simple optical systems (consisting of spherical and conical elements) are presented. A general Bessel-Gauss cavity design strategy is outlined, and a particular geometry, the confocal Bessel-Gauss cavity, is analyzed in detail. We numerically simulate the confocal Bessel-Gauss cavity and present an example cavity with 300 MHz repetition rate supporting an effective waist of 33 μm at the focus and an intensity ratio from the focus to the cavity mirror surfaces of 1.5 × 10(4).
Energy Technology Data Exchange (ETDEWEB)
Caliebe, D.; Arp, O.; Piel, A. [Institut fuer Experimentelle und Angewandte Physik, Christian-Albrechts-Universitaet, Kiel (Germany)
2011-07-15
The penetration of a dusty plasma by fast charged projectiles is studied under microgravity conditions. The mass and charge of the projectiles are larger than those of the target particles. A projectile generates a dust-free cavity in its wake, whose shape strongly depends on the projectile velocity. The faster the projectile the more elongated becomes the cavity while its cross-section decreases. The opening time of the cavity is found independent of the projectile velocity. For supersonic projectiles, the dynamics of the cavity can be decomposed into an initial impulse and a subsequent elastic response that can be modeled by a damped harmonic oscillator.
Double and triple-harmonic RF buckets and their use for bunch squeezing in AGS
Energy Technology Data Exchange (ETDEWEB)
Gardner, C. J. [Brookhaven National Lab. (BNL), Upton, NY (United States)
2016-08-24
For the past several years we have merged bunches in AGS in order to achieve the desired intensity per bunch prior to injection into RHIC. The merging is done on a flat porch at or above AGS injection energy. Because the merges involve the reduction of the RF harmonic number by a factor of 2 (for a 2 to 1 merge) and then a factor of 3 (for a 3 to 1 merge), one requires RF frequencies 6hf_{s}, 3hf_{s}, 2hf_{s} and hf_{s}, where f_{s} is the revolution frequency on the porch and h = 4 is the fundamental harmonic number. The standard AGS RF cavities cannot operate at the lowest frequencies 2hf_{s} and hf_{s}; these are provided by two modified cavities. Upon completion of the merges, the bunches are sitting in harmonic h buckets. In order to be accelerated they need to be squeezed into harmonic 3h buckets. This is accomplished by producing a double-harmonic bucket in which harmonics h and 2h act in concert, and then a triple-harmonic bucket in which harmonics h, 2h, and 3h act in concert. Simulations have shown that the squeeze presents an acceptance bottleneck which limits the longitudinal emittance that can be put into the harmonic 3h bucket. In this note the areas of the double and triple-harmonic buckets are calculated explicitly, and it is shown that these go through a minimum as the RF voltages are raised to the desired values. Several RF voltage ranges are examined, and the acceptance bottleneck is determined for each of these. Finally, the acceptance bottleneck for Au77+ bunches in AGS is calculated for several RF voltage ranges. The main result is that the RF voltages for the low-frequency harmonic h and 2h cavities both must be at least 22 kV in order to achieve an acceptance of 0:6 eV s per nucleon. If the harmonic h and 2h voltages are 15 and 22 kV, respectively, then the acceptance is reduced to 0:548 eV s per nucleon.
DEFF Research Database (Denmark)
Bache, Morten; Lodahl, Peter; Mamaev, Alexander V.
2002-01-01
We predict and experimentally observe temporal self-pulsing in singly resonant intracavity second-harmonic generation under conditions of simultaneous parametric oscillation. The threshold for self-pulsing as a function of cavity tuning and phase mismatch are found from analysis of a three-compon...
Two-pass-internal second-harmonic generation using a prism coupler.
Gonzalez, D. G.; Nieh, S. T. K.; Steier, W. H.
1973-01-01
A dispersive quartz prism is used to couple the total second harmonic generated in both directions by an internal cavity frequency doubler. The study shows that the dispersion of air and mirror reflection phase shifts can be compensated for by a slight nonphase match condition in the doubler.
A Primer on the Physical Principles of Tissue Harmonic Imaging.
Anvari, Arash; Forsberg, Flemming; Samir, Anthony E
2015-01-01
Tissue harmonic imaging (THI) is a routinely used component of diagnostic ultrasonography (US). In this method, higher-frequency harmonic waves produced by nonlinear fundamental US wave propagation are used to generate images that contain fewer artifacts than those seen on conventional fundamental wave US tissue imaging. Harmonic frequencies are integer multiples of the fundamental frequency. The majority of current clinical US systems use second harmonic echoes for THI image formation. Image processing techniques (ie, bandwidth receive filtering, pulse inversion, side-by-side phase cancellation, and pulse-coded harmonics) are used to eliminate the fundamental frequency echoes, and the remaining harmonic frequency data are used to generate the diagnostic image. Advantages of THI include improved signal-to-noise ratio and reduced artifacts produced by side lobes, grating lobes, and reverberation. THI has been accepted in US practice, and variations of the technology are available on most US systems typically used for diagnostic imaging in radiologic practice. Differential THI is a further improvement that combines the advantages of THI, including superior tissue definition and reduced speckle artifact, with the greater penetration of lower frequency US, which permits high-quality harmonic imaging at greater depth than could previously be performed with conventional THI. (©)RSNA, 2015.
Harmonic Tracking of Acoustic Radiation Force Induced Displacements
Doherty, Joshua R.; Dahl, Jeremy J.; Trahey, Gregg E.
2014-01-01
Ultrasound-based elasticity imaging methods rely upon accurate estimates of tissue deformation to characterize the mechanical properties of soft tissues. These methods are corrupted by clutter, which can bias and/or increase variance in displacement estimates. Harmonic imaging methods are routinely used for clutter suppression and improved image quality in conventional B-mode ultrasound, but have not been utilized in ultrasound-based elasticity imaging methods. We introduce a novel, fully-sampled pulse inversion harmonic method for tracking tissue displacements that corrects the loss in temporal sampling frequency associated with conventional pulse inversion techniques. The method is implemented with Acoustic Radiation Force Impulse (ARFI) imaging to monitor the displacements induced by an impulsive acoustic radiation force excitation. Custom pulse sequences were implemented on a diagnostic ultrasound scanner to collect spatially-matched fundamental and harmonic information within a single acquisition. B-mode and ARFI images created from fundamental data collected at 4 MHz and 8 MHz are compared with 8 MHz harmonic images created using a bandpass filter approach and the fully sampled pulse inversion method. In homogeneous, tissue-mimicking phantoms, where no visible clutter was observed, there was little difference in the axial displacements, estimated jitter, and normalized cross-correlation among the fundamental and harmonic tracking methods. The similarity of the lower and higher frequency methods suggests that any improvement due to the increased frequency of the harmonic components is negligible. The harmonic tracking methods demonstrated a marked improvement in B-mode and ARFI image quality of in vivo carotid arteries. Improved feature detection and decreased variance in estimated displacements were observed in the arterial walls of harmonic ARFI images, especially in the pulse inversion harmonic ARFI images. Within the lumen, the harmonic tracking methods
Harmonic tracking of acoustic radiation force-induced displacements.
Doherty, Joshua R; Dahl, Jeremy J; Trahey, Gregg E
2013-11-01
Ultrasound-based elasticity imaging methods rely upon accurate estimates of tissue deformation to characterize the mechanical properties of soft tissues. These methods are corrupted by clutter, which can bias and/or increase variance in displacement estimates. Harmonic imaging methods are routinely used for clutter suppression and improved image quality in conventional B-mode ultrasound, but have not been utilized in ultrasound-based elasticity imaging methods. We introduce a novel, fully-sampled pulse-inversion harmonic method for tracking tissue displacements that corrects the loss in temporal sampling frequency associated with conventional pulse-inversion techniques. The method is implemented with acoustic radiation force impulse (ARFI) imaging to monitor the displacements induced by an impulsive acoustic radiation force excitation. Custom pulse sequences were implemented on a diagnostic ultrasound scanner to collect spatially-matched fundamental and harmonic information within a single acquisition. B-mode and ARFI images created from fundamental data collected at 4 MHz and 8 MHz are compared with 8-MHz harmonic images created using a band-pass filter approach and the fully sampled pulse-inversion method. In homogeneous, tissue-mimicking phantoms, where no visible clutter was observed, there was little difference in the axial displacements, estimated jitter, and normalized cross-correlation among the fundamental and harmonic tracking methods. The similarity of the lower- and higher-frequency methods suggests that any improvement resulting from the increased frequency of the harmonic components is negligible. The harmonic tracking methods demonstrated a marked improvement in B-mode and ARFI image quality of in vivo carotid arteries. Improved feature detection and decreased variance in estimated displacements were observed in the arterial walls of harmonic ARFI images, especially in the pulse-inversion harmonic ARFI images. Within the lumen, the harmonic tracking
Superconducting cavities for LEP
CERN PhotoLab
1983-01-01
Above: a 350 MHz superconducting accelerating cavity in niobium of the type envisaged for accelerating electrons and positrons in later phases of LEP. Below: a small 1 GHz cavity used for investigating the surface problems of superconducting niobium. Albert Insomby stays on the right. See Annual Report 1983 p. 51.
Bernard, Philippe
1999-01-01
It was 20 years ago when the research and development programme for LEP superconducting cavities was initiated. It lasted about 10 years. Today, my aim is not to tell you in great detail about the many innovations made thanks to our research, but I would like to point out some milestones in the development of superconducting cavities where Emilio's influence was particularly important.
CERN PhotoLab
1980-01-01
One of the SPS acceleration cavities (200 MHz, travelling wave structure). On the ceiling one sees the coaxial transmission line which feeds the power from the amplifier, located in a surface building above, to the upstream end of the cavity. See 7603195 for more details, 7411032 for the travelling wave structure, and also 8104138, 8302397.
CERN PhotoLab
1981-01-01
One of the SPS accelerating cavities (200 MHz, travelling wave structure). The power that is fed into the upstream end of the cavity is extracted at the downstream end and sent into a dump load. See 7603195 for more details, 7411032 for the travelling wave structure, and also 8011289, 8302397.
Spatial mode discrimination using second harmonic generation
DEFF Research Database (Denmark)
Delaubert, Vincent; Lassen, Mikael Østergaard; Pulford, David
2007-01-01
-Kleinmann analysis, taking into account the full description of the multi-mode field inside the nonlinear crystal in a type I phase-maching condition. The good agreement between experiments and theory shows that the effect is well understood and that we have reliable models required for the design of novel photonics......Second harmonic generation can be used as a technique for controlling the spatial mode structure of optical beams. We demonstrate experimentally the generation of higher order spatial modes, and that it is possible to use nonlinear phase matching as a predictable and robust technique...... for the conversion of transverse electric modes of the second harmonic output. For a given TEMn0 pump mode the output mode can be altered continuously by adjusting the laser wavelength, the focusing of the pump or the temperature of the nonlinear medium. We make quantitative comparisons with a generalized Boyd...
LHC Crab Cavity Coupler Test Boxes
Mitchell, James; Burt, Graeme; Calaga, Rama; Macpherson, Alick; Montesinos, Eric; Silva, Subashini; Tutte, Adam; Xiao, Binping
2016-01-01
The LHC double quarter wave (DQW) crab cavities have two different types of Higher Order Mode (HOM) couplers in addition to a fundamental power coupler (FPC). The FPC requires conditioning, so to achieve this we have designed a radio-frequency (RF) quarter wave resonator to provide high transmission between two opposing FPCs. For the HOM couplers we must ensure that the stop-band filter is positioned at the cavity frequency and that peak transmission occurs at the same frequencies as the strongest HOMs. We have designed two test boxes which preserve the cavity spectral response in order to test the couplers.
Power quality issues current harmonics
Mikkili, Suresh
2015-01-01
Power Quality Issues: Current Harmonics provides solutions for the mitigation of power quality problems related to harmonics. Focusing on active power filters (APFs) due to their excellent harmonic and reactive power compensation in two-wire (single phase), three-wire (three-phase without neutral), and four-wire (three-phase with neutral) AC power networks with nonlinear loads, the text:Introduces the APF technology, describing various APF configurations and offering guidelines for the selection of APFs for specific application considerationsCompares shunt active filter (SHAF) control strategi
Tooth structure and fracture strength of cavities
DEFF Research Database (Denmark)
Mondelli, José; Sene, Fábio; Ramos, Renata Pereira
2007-01-01
a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed by two-way ANOVA and Tukey test (alpha= 0.05). 1/4-inlay cavities had higher percent mean mass loss (9.71%) than composite resin cavities with the same width (7.07%). 1/3-inlay preparations also produced higher percent mean...... mass loss (13.91%) than composite resin preparations with the same width (10.02%). 1/2-inlay cavities had 21.34% of mass loss versus 16.19% for the 1/2-composite resin cavities. Fracture strength means (in kgf) were: GI = 187.65; GII = 143.62; GIII = 74.10; GIV = 164.22; GV = 101.92; GVI = 50...
Alternative Approaches for HOM Damped Cavities
Riemann, B.; Neumann, A.; Weis, T
2012-01-01
In this paper, we present two different ideas that may be useful for design and simulation of superconducting radio frequency cavities. To obtain longitudinal and transverse voltages resp. shunt impedances in cavities without rotational symmetry, one or two integration paths are often used to get an approximate difference relation for the transverse voltage of higher order modes HOMs . The presented approach uses a multipole decomposition that is valid in vicinity of the central a...
Practical Solutions for Harmonics Problems Produced in the Distribution Networks
Directory of Open Access Journals (Sweden)
A. F. Zobaa
2006-03-01
Full Text Available Harmonic distortion on the power system is a modern concern due to the technological advances in silicon technology as it presents an increased non-linear loading of the power system. The effects of harmonics are well known: customers could experience major production losses due to the loss of supply as an example, on the other hand, harmonic load currents cause the utility to supply a higher real energy input then the actual real power needed to maintain a plant’s production at a certain level. The utility carries the extra transmission losses due to the harmonic currents. Different solutions will be reviewed as concepts for solving certain types of problems related to power quality. Both theoretical and a case study are presented.
Nonlinear wave chaos: statistics of second harmonic fields
Zhou, Min; Ott, Edward; Antonsen, Thomas M.; Anlage, Steven M.
2017-10-01
Concepts from the field of wave chaos have been shown to successfully predict the statistical properties of linear electromagnetic fields in electrically large enclosures. The Random Coupling Model (RCM) describes these properties by incorporating both universal features described by Random Matrix Theory and the system-specific features of particular system realizations. In an effort to extend this approach to the nonlinear domain, we add an active nonlinear frequency-doubling circuit to an otherwise linear wave chaotic system, and we measure the statistical properties of the resulting second harmonic fields. We develop an RCM-based model of this system as two linear chaotic cavities coupled by means of a nonlinear transfer function. The harmonic field strengths are predicted to be the product of two statistical quantities and the nonlinearity characteristics. Statistical results from measurement-based calculation, RCM-based simulation, and direct experimental measurements are compared and show good agreement over many decades of power.
Introduction to abstract harmonic analysis
Loomis, Lynn H
2011-01-01
Written by a prominent figure in the field of harmonic analysis, this classic monograph is geared toward advanced undergraduates and graduate students and focuses on methods related to Gelfand's theory of Banach algebra. 1953 edition.
Tissue Harmonic Synthetic Aperture Imaging
DEFF Research Database (Denmark)
Rasmussen, Joachim
The main purpose of this PhD project is to develop an ultrasonic method for tissue harmonic synthetic aperture imaging. The motivation is to advance the field of synthetic aperture imaging in ultrasound, which has shown great potentials in the clinic. Suggestions for synthetic aperture tissue...... system complexity compared to conventional synthetic aperture techniques. In this project, SASB is sought combined with a pulse inversion technique for 2nd harmonic tissue harmonic imaging. The advantages in tissue harmonic imaging (THI) are expected to further improve the image quality of SASB....... The first part of the scientific contribution investigates an implementation of pulse inversion for THI on the experimental ultrasound system SARUS. The technique is initially implemented for linear array transducers and then expanded for convex array transducers. The technique is evaluated based on spatial...
Harmonic structures and intrinsic torsion
DEFF Research Database (Denmark)
Conti, Diego; Madsen, Thomas Bruun
We discuss the construction of 8-manifolds with harmonic Sp(2)Sp(1)-structures. In particular, we find 10 new examples of nilmanifolds that admit a closed 4-form Omega whose stabiliser is Sp(2)Sp(1). Our constructions entail the notion of SO(4)-structures on 7-manifolds. We present a thorough inv...... investigation of the intrinsic torsion of such structures; in addition to the construction of harmonic structures, this analysis leads to explicit Lie group examples with invariant intrinsic torsion....
1979-01-01
This picture shows one of the 2 new cavities installed in 1978-1979. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also increased: to the first 2 MW plant a second 2 MW plant was added and by end 1979 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412016X, 7412017X, 7411048X
1975-01-01
The picture shows one of the two initially installed cavities. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also gradually increased: by end 1980 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412017X, 7411048X, 7505074.
Status of a high gradient CH - cavity
Energy Technology Data Exchange (ETDEWEB)
Almomani, Ali; Ratzinger, Ulrich [IAP, Frankfurt Universitaet (Germany)
2015-07-01
This pulsed linac activity aims on compact designs and on a considerable increase of the voltage gain per meter. A high gradient CH-cavity operated at 325 MHz was developed at IAP-Frankfurt. The mean effective accelerating field for this cavity is expected well above 10 MV/m at β=0.164. This cavity is developed within a funded project. The results might influence the rebuilt of the UNILAC - Alvarez section, aiming to achieve the beam intensities specified for the GSI-FAIR project (15 mA U{sup 28+}). Another motivation is the development of an efficient pulsed ion accelerator for significantly higher energies like 60 AMeV. The new GSI 3 MW Thales klystron test stand will be used for the cavity RF power tests. Detailed studies on two different types of copper plating are performed with this cavity. Additionally, operating of normal conducting cavities at cryogenic temperatures are discussed for the case of very short RF pulses. The first measurement results for this cavity are presented.
General Lp-harmonic Blaschke bodies
Indian Academy of Sciences (India)
Lutwak introduced the harmonic Blaschke combination and the harmonic Blaschke body of a star body. Further, Feng and Wang introduced the concept of the -harmonic Blaschke body of a star body. In this paper, we define the notion of general -harmonic Blaschke bodies and establish some of its properties.
General Lp-harmonic Blaschke bodies
Indian Academy of Sciences (India)
Abstract. Lutwak introduced the harmonic Blaschke combination and the harmonic. Blaschke body of a star body. Further, Feng and Wang introduced the concept of the L p- harmonic Blaschke body of a star body. In this paper, we define the notion of general. L p-harmonic Blaschke bodies and establish some of its ...
Hydroforming of elliptical cavities
Directory of Open Access Journals (Sweden)
W. Singer
2015-02-01
Full Text Available Activities of the past several years in developing the technique of forming seamless (weldless cavity cells by hydroforming are summarized. An overview of the technique developed at DESY for the fabrication of single cells and multicells of the TESLA cavity shape is given and the major rf results are presented. The forming is performed by expanding a seamless tube with internal water pressure while simultaneously swaging it axially. Prior to the expansion the tube is necked at the iris area and at the ends. Tube radii and axial displacements are computer controlled during the forming process in accordance with results of finite element method simulations for necking and expansion using the experimentally obtained strain-stress relationship of tube material. In cooperation with industry different methods of niobium seamless tube production have been explored. The most appropriate and successful method is a combination of spinning or deep drawing with flow forming. Several single-cell niobium cavities of the 1.3 GHz TESLA shape were produced by hydroforming. They reached accelerating gradients E_{acc} up to 35 MV/m after buffered chemical polishing (BCP and up to 42 MV/m after electropolishing (EP. More recent work concentrated on fabrication and testing of multicell and nine-cell cavities. Several seamless two- and three-cell units were explored. Accelerating gradients E_{acc} of 30–35 MV/m were measured after BCP and E_{acc} up to 40 MV/m were reached after EP. Nine-cell niobium cavities combining three three-cell units were completed at the company E. Zanon. These cavities reached accelerating gradients of E_{acc}=30–35 MV/m. One cavity is successfully integrated in an XFEL cryomodule and is used in the operation of the FLASH linear accelerator at DESY. Additionally the fabrication of bimetallic single-cell and multicell NbCu cavities by hydroforming was successfully developed. Several NbCu clad single-cell and
1974-01-01
The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. A power of up to 790 kW can be supplied to each giving a total accelerating voltage of about 8 MV. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities.
Cavity-enhanced spectroscopies
van Zee, Roger
2003-01-01
""Cavity-Enhanced Spectroscopy"" discusses the use of optical resonators and lasers to make sensitive spectroscopic measurements. This volume is written by the researcchers who pioneered these methods. The book reviews both the theory and practice behind these spectroscopic tools and discusses the scientific discoveries uncovered by these techniques. It begins with a chapter on the use of optical resonators for frequency stabilization of lasers, which is followed by in-depth chapters discussing cavity ring-down spectroscopy, frequency-modulated, cavity-enhanced spectroscopy, intracavity spectr
Commutation effect of Adjustable Speed Drives due to installation of active harmonic filters
DEFF Research Database (Denmark)
Asiminoaei, Lucian; Kalaschnikow, Sergej; Hansen, Steffan
2011-01-01
The success of designing an industrial installation with Active Filters depends on how precise the load profile of the application is known, because this determines the amount of harmonic currents to be compensated. However, once the Active Filter is added to the installation, the harmonic currents...... may increase due to changes in the commutation behavior of diode rectifier converters. The change of natural commutation determines higher harmonics currents of the diode rectifiers and therefore higher harmonic loading of the Active Filter in the installation. This paper presents a method to estimate...
Prony Analysis for Power System Transient Harmonics
Directory of Open Access Journals (Sweden)
David Cartes
2007-01-01
Full Text Available Proliferation of nonlinear loads in power systems has increased harmonic pollution and deteriorated power quality. Not required to have prior knowledge of existing harmonics, Prony analysis detects frequencies, magnitudes, phases, and especially damping factors of exponential decaying or growing transient harmonics. In this paper, Prony analysis is implemented to supervise power system transient harmonics, or time-varying harmonics. Further, to improve power quality when transient harmonics appear, the dominant harmonics identified from Prony analysis are used as the harmonic reference for harmonic selective active filters. Simulation results of two test systems during transformer energizing and induction motor starting confirm the effectiveness of the Prony analysis in supervising and canceling power system transient harmonics.
Validation of phantom-based harmonization for patient harmonization.
Panetta, Joseph V; Daube-Witherspoon, Margaret E; Karp, Joel S
2017-07-01
To improve the precision of multicenter clinical trials, several efforts are underway to determine scanner-specific parameters for harmonization using standardized phantom measurements. The goal of this study was to test the correspondence between quantification in phantom and patient images and validate the use of phantoms for harmonization of patient images. The National Electrical Manufacturers' Association image quality phantom with hot spheres was scanned on two time-of-flight PET scanners. Whole-body [18 F]-fluorodeoxyglucose (FDG)-PET scans were acquired of subjects on the same systems. List-mode events from spheres (diam.: 10-28 mm) measured in air on each scanner were embedded into the phantom and subject list-mode data from each scanner to create lesions with known uptake with respect to the local background in the phantom and each subject's liver and lung regions, as a proxy to characterize true lesion quantification. Images were analyzed using the contrast recovery coefficient (CRC) typically used in phantom studies and serving as a surrogate for the standardized uptake value used clinically. Postreconstruction filtering (resolution recovery and Gaussian smoothing) was applied to determine if the effect on the phantom images translates equivalently to subject images. Three postfiltering strategies were selected to harmonize the CRCmean or CRCmax values between the two scanners based on the phantom measurements and then applied to the subject images. Both the average CRCmean and CRCmax values for lesions embedded in the lung and liver in four subjects (BMI range 25-38) agreed to within 5% with the CRC values for lesions embedded in the phantom for all lesion sizes. In addition, the relative changes in CRCmean and CRCmax resulting from the application of the postfilters on the subject and phantom images were consistent within measurement uncertainty. Further, the root mean squared percent difference (RMSpd ) between CRC values on the two scanners
Dental Sealants Prevent Cavities
... RSS VitalSigns RSS Error processing SSI file Dental Sealants Prevent Cavities Effective protection for children Language: English ( ... Problem About 7 million low-income children need sealants. What are sealants? Sealants are thin coatings painted ...
This is an accelerating cavity from LEP, with a layer of niobium on the inside. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment. These challenging requirements pushed European industry to new achievements. 256 of these cavities are now used in LEP to double the energy of the particle beams.
CERN PhotoLab
1983-01-01
View towards the downstream end of one of the SPS accelerating cavities (200 MHz, travelling wave structure). See 7603195 and 8011289 for more details, 7411032 for the travelling wave structure, and also 8104138.
CERN PhotoLab
1976-01-01
The SPS started up with 2 accelerating cavities (each consisting of 5 tank sections) in LSS3. They have a 200 MHz travelling wave structure (see 7411032 and 7802190) and 750 kW of power is fed to each of the cavities from a 1 MW tetrode power amplifier, located in a surface building above, via a coaxial transmission line. Clemens Zettler, builder of the SPS RF system, is standing at the side of one of the cavities. In 1978 and 1979 another 2 cavities were added and entered service in 1980. These were part of the intensity improvement programme and served well for the new role of the SPS as proton-antiproton collider. See also 7411032, 8011289, 8104138, 8302397.
National Research Council Canada - National Science Library
Cengiz, Murat İnanç; Cengiz, Seda; Wang, Hom-Lay
2012-01-01
While initially the oral cavity was considered to be mainly a source of various bacteria, their toxins and antigens, recent studies showed that it may also be a location of oxidative stress and periodontal inflammation...
DEFF Research Database (Denmark)
Chung, Il-Sug; Mørk, Jesper
2010-01-01
A new hybrid vertical cavity laser structure for silicon photonics is suggested and numerically investigated. It incorporates a silicon subwavelength grating as a mirror and a lateral output coupler to a silicon ridge waveguide.......A new hybrid vertical cavity laser structure for silicon photonics is suggested and numerically investigated. It incorporates a silicon subwavelength grating as a mirror and a lateral output coupler to a silicon ridge waveguide....
The Superconducting TESLA Cavities
Aune, B.; Bloess, D.; Bonin, B.; Bosotti, A.; Champion, M.; Crawford, C.; Deppe, G.; Dwersteg, B.; Edwards, D.A.; Edwards, H.T.; Ferrario, M.; Fouaidy, M.; Gall, P-D.; Gamp, A.; Gössel, A.; Graber, J.; Hubert, D.; Hüning, M.; Juillard, M.; Junquera, T.; Kaiser, H.; Kreps, G.; Kuchnir, M.; Lange, R.; Leenen, M.; Liepe, M.; Lilje, L.; Matheisen, A.; Möller, W-D.; Mosnier, A.; Padamsee, H.; Pagani, C.; Pekeler, M.; Peters, H-B.; Peters, O.; Proch, D.; Rehlich, K.; Reschke, D.; Safa, H.; Schilcher, T.; Schmüser, P.; Sekutowicz, J.; Simrock, S.; Singer, W.; Tigner, M.; Trines, D.; Twarowski, K.; Weichert, G.; Weisend, J.; Wojtkiewicz, J.; Wolff, S.; Zapfe, K.
2000-01-01
The conceptional design of the proposed linear electron-positron colliderTESLA is based on 9-cell 1.3 GHz superconducting niobium cavities with anaccelerating gradient of Eacc >= 25 MV/m at a quality factor Q0 > 5E+9. Thedesign goal for the cavities of the TESLA Test Facility (TTF) linac was set tothe more moderate value of Eacc >= 15 MV/m. In a first series of 27industrially produced TTF cavities the average gradient at Q0 = 5E+9 wasmeasured to be 20.1 +- 6.2 MV/m, excluding a few cavities suffering fromserious fabrication or material defects. In the second production of 24 TTFcavities additional quality control measures were introduced, in particular aneddy-current scan to eliminate niobium sheets with foreign material inclusionsand stringent prescriptions for carrying out the electron-beam welds. Theaverage gradient of these cavities at Q0 = 5E+9 amounts to 25.0 +- 3.2 MV/mwith the exception of one cavity suffering from a weld defect. Hence only amoderate improvement in production and preparation technique...
Benusiglio, Adrien; Clanet, Christophe
2012-01-01
We present a fluid dynamics video on cavities created by explosions of firecrackers at the water free surface. We use three types of firecrackers containing 1, 1.3 and 5 g of flash powder. The firecrackers are held with their center at the surface of water in a cubic meter pool. The movies are recorded from the side with a high-speed video camera. Without confinement the explosion produces an hemispherical cavity. Right after the explosion this cavity grows isotropically, the bottom then stops while the sides continue to expand. In the next phase the bottom of the cavity accelerates backwards to the surface. During this phase the convergence of the flow creates a central jet that rises above the free surface. In the last part of the video the explosion is confined in a vertical open tube made of glass and of centimetric diameter. The explosion creates a cylindrical cavity that develops towards the free end of the tube. Depending on the charge, the cavity can either stop inside the tube or at its exit, but nev...
High-Energy Ion Linacs Based on Spoke Cavities
Shephard, K W; Ostromov, P N
2003-01-01
The applicability of superconducting TEM-class spoke cavities to high-energy ion linacs is discussed, and detailed designs for two TEM-class, triple-spoke-loaded superconducting niobium resonant cavities are presented. The 345 MHz cavities have a velocity range of 0.4
Multimode Directional Coupler for Utilization of Harmonic Frequencies from TWTAs
Simmons, Rainee N.; Wintucky, Edwin G.
2013-01-01
A novel waveguide multimode directional coupler (MDC) intended for the measurement and potential utilization of the second and higher order harmonic frequencies from high-power traveling wave tube amplifiers (TWTAs) has been successfully designed, fabricated, and tested. The design is based on the characteristic multiple propagation modes of the electrical and magnetic field components of electromagnetic waves in a rectangular waveguide. The purpose was to create a rugged, easily constructed, more efficient waveguide- based MDC for extraction and exploitation of the second harmonic signal from the RF output of high-power TWTs used for space communications. The application would be a satellitebased beacon source needed for Qband and V/W-band atmospheric propagation studies. The MDC could function as a CW narrow-band source or as a wideband source for study of atmospheric group delay effects on highdata- rate links. The MDC is fabricated from two sections of waveguide - a primary one for the fundamental frequency and a secondary waveguide for the second harmonic - that are joined together such that the second harmonic higher order modes are selectively coupled via precision- machined slots for propagation in the secondary waveguide. In the TWTA output waveguide port, both the fundamental and the second harmonic signals are present. These signals propagate in the output waveguide as the dominant and higher order modes, respectively. By including an appropriate mode selective waveguide directional coupler, such as the MDC presented here at the output of the TWTA, the power at the second harmonic can be sampled and amplified to the power level needed for atmospheric propagation studies. The important conclusions from the preliminary test results for the multimode directional coupler are: (1) the second harmonic (Ka-band) can be measured and effectively separated from the fundamental (Ku-band) with no coupling of the latter, (2) power losses in the fundamental frequency
Glass devices for efficient second harmonic generation
DEFF Research Database (Denmark)
Fage-Pedersen, Jacob; Jacobsen, Rune Shim; Kristensen, Martin
2005-01-01
We show here that quasi-phase matched (QPM) planar nonlinear devices of high quality can be fabricated by means of periodic poling of the glass. The devices, used for second-harmonic generation (SHG), have accurately-controlled centre wavelengths, and the normalised conversion efficiencies...... are approximately one order of magnitude higher than what has previously been reported for periodically poled glass. In conclusion, we have demonstrated that high-quality nonlinear QPM devices can be fabricated in glass-on-silicon. The technology is easily adaptable to any desired wavelength (e.g. 1550 nm) and can...
Directory of Open Access Journals (Sweden)
Fumihiko Tamura
2008-07-01
Full Text Available The dual-harmonic operation, in which the accelerating cavities are driven by the superposition of the fundamental and the second harmonic rf voltage, is useful for acceleration of the ultrahigh intensity proton beam in the rapid cycling synchrotron (RCS of Japan Proton Accelerator Research Complex (J-PARC. However, the precise and fast voltage control of the harmonics is necessary to realize the dual-harmonic acceleration. We developed the dual-harmonic auto voltage control system for the J-PARC RCS. We describe details of the design and the implementation. Various tests of the system are performed with the RCS rf system. Also, a preliminary beam test has been done. We report the test results.
The analysis of harmonic generation coefficients in the ablative Rayleigh-Taylor instability
Lu, Yan; Fan, Zhengfeng; Lu, Xinpei; Ye, Wenhua; Zou, Changlin; Zhang, Ziyun; Zhang, Wen
2017-10-01
In this research, we use the numerical simulation method to investigate the generation coefficients of the first three harmonics and the zeroth harmonic in the Ablative Rayleigh-Taylor Instability. It is shown that the interface shifts to the low temperature side during the ablation process. In consideration of the third-order perturbation theory, the first three harmonic amplitudes of the weakly nonlinear regime are calculated and then the harmonic generation coefficients are obtained by curve fitting. The simulation results show that the harmonic generation coefficients changed with time and wavelength. Using the higher-order perturbation theory, we find that more and more harmonics are generated in the later weakly nonlinear stage, which is caused by the negative feedback of the later higher harmonics. Furthermore, extending the third-order theory to the fifth-order theory, we find that the second and the third harmonics coefficients linearly depend on the wavelength, while the feedback coefficients are almost constant. Further analysis also shows that when the fifth-order theory is considered, the normalized effective amplitudes of second and third harmonics can reach about 25%-40%, which are only 15%-25% in the frame of the previous third-order theory. Therefore, the third order perturbation theory is needed to be modified by the higher-order theory when ηL reaches about 20% of the perturbation wavelength.
HARMONIZED EUROPE OR EUROPEAN HARMONY?
Directory of Open Access Journals (Sweden)
Cosmin Marinescu
2007-07-01
Full Text Available Recent evolutions in Europe raise questions on the viability of the present economic and social model that defines the European construction project. In this paper, the author will try to explain the viability of institutional European model that sticks between free market mechanisms and protectionism. The main challenge for the EU is about the possibility to bring together the institutional convergence and the welfare for all Europeans. This is the result of the view, still dominant, of European politics elite, according to which institutional harmonization is the solution of a more dynamic and prosper Europe. But, economic realities convince us that, more and more, a harmonized, standardized Europe is not necessarily identical with a Europe of harmony and social cooperation. If „development through integration” seems to be harmonization through „institutional transplant”, how could then be the European model one sufficiently wide open to market, which creates the prosperity so long waited for by new member countries?
Cluster size dependence of high-order harmonic generation
Tao, Y.; Hagmeijer, R.; Bastiaens, H. M. J.; Goh, S. J.; van der Slot, P. J. M.; Biedron, S. G.; Milton, S. V.; Boller, K.-J.
2017-08-01
We investigate high-order harmonic generation (HHG) from noble gas clusters in a supersonic gas jet. To identify the contribution of harmonic generation from clusters versus that from gas monomers, we measure the high-order harmonic output over a broad range of the total atomic number density in the jet (from 3×1016 to 3 × 1018 {{cm}}-3) at two different reservoir temperatures (303 and 363 K). For the first time in the evaluation of the harmonic yield in such measurements, the variation of the liquid mass fraction, g, versus pressure and temperature is taken into consideration, which we determine, reliably and consistently, to be below 20% within our range of experimental parameters. By comparing the measured harmonic yield from a thin jet with the calculated corresponding yield from monomers alone, we find an increased emission of the harmonics when the average cluster size is less than 3000. Using g, under the assumption that the emission from monomers and clusters add up coherently, we calculate the ratio of the average single-atom response of an atom within a cluster to that of a monomer and find an enhancement of around 100 for very small average cluster size (∼200). We do not find any dependence of the cut-off frequency on the composition of the cluster jet. This implies that HHG in clusters is based on electrons that return to their parent ions and not to neighboring ions in the cluster. To fully employ the enhanced average single-atom response found for small average cluster sizes (∼200), the nozzle producing the cluster jet must provide a large liquid mass fraction at these small cluster sizes for increasing the harmonic yield. Moreover, cluster jets may allow for quasi-phase matching, as the higher mass of clusters allows for a higher density contrast in spatially structuring the nonlinear medium.
Cavity Enhanced Absorption Spectroscopy using a Prism Cavity and Supercontinuum Source
Lehmann, Kevin K.; Johnston, Paul S.
2010-03-01
The multiplex advantage of current cavity enhanced spectrometers is limited by the limited high reflectivity bandwidth of the dielectric mirrors used to construct the high finesse cavity. We report on our development of a spectrometer that uses Brewster's angle retroreflectors that is excited with supercontinuum radiation generated by a 1.06 μm pumped photonic crystal fiber, which covers the 500-1800 nm spectral range. Recent progress will be discussed including modeling of the prism cavity losses, alternative prism materials for use in the UV and mid-IR, and a new higher power source pumped by a mode-locked laser.
Elements of abstract harmonic analysis
Bachman, George
2013-01-01
Elements of Abstract Harmonic Analysis provides an introduction to the fundamental concepts and basic theorems of abstract harmonic analysis. In order to give a reasonably complete and self-contained introduction to the subject, most of the proofs have been presented in great detail thereby making the development understandable to a very wide audience. Exercises have been supplied at the end of each chapter. Some of these are meant to extend the theory slightly while others should serve to test the reader's understanding of the material presented. The first chapter and part of the second give
Harmonic functions with varying coefficients
Directory of Open Access Journals (Sweden)
Jacek Dziok
2016-05-01
Full Text Available Abstract Complex-valued harmonic functions that are univalent and sense preserving in the open unit disk can be written in the form f = h + g ‾ $f=h+\\overline{g}$ , where h and g are analytic. In this paper we investigate some classes of univalent harmonic functions with varying coefficients related to Janowski functions. By using the extreme points theory we obtain necessary and sufficient convolution conditions, coefficients estimates, distortion theorems, and integral mean inequalities for these classes of functions. The radii of starlikeness and convexity for these classes are also determined.
Optimal Selective Harmonic Control for Power Harmonics Mitigation
DEFF Research Database (Denmark)
Zhou, Keliang; Yang, Yongheng; Blaabjerg, Frede
2015-01-01
of power harmonics. The proposed optimal SHC is of hybrid structure: all recursive SHC modules with weighted gains are connected in parallel. It bridges the real “nk+-m order RC” and the complex “parallel structure RC”. Compared to other IMP based control solutions, it offers an optimal trade-off among...
The CEBAF Separator Cavity Resonance Control System
Wissmann, Mark J; Hovater, Curt; Plawski, Tomasz
2005-01-01
The CEBAF energy upgrade from 6 GeV to 12GeV will increase the range of beam energies available to the experimental halls. RF deflection cavities (separators) are used to direct the electron beam to the three experimental halls. Consequently with the increase in RF separator cavity gradient needed for the higher energies, RF power will also increase requiring the cavities to have active resonance control. At the 6 GeV energy, the cavities are tuned mechanically and then stabilized with Low Conductivity Water (LCW), which is maintained at constant temperature of 95o Fahrenheit. This is no longer feasible and an active resonance control system, that controls both water temperature and flow has been built. The system uses a commercial PLC with embedded PID controls to control water temperature and flow to the cavities. The system allows the operator to remotely adjust temperature/flow and consequently cavity resonance for the full range of beam energies. Ultimately closed loop control will be maintained by monit...
Probabilistic Harmonic Modeling of Wind Power Plants
DEFF Research Database (Denmark)
Guest, Emerson; Jensen, Kim H.; Rasmussen, Tonny Wederberg
2017-01-01
A probabilistic sequence domain (SD) harmonic model of a grid-connected voltage-source converter is used to estimate harmonic emissions in a wind power plant (WPP) comprised of Type-IV wind turbines. The SD representation naturally partitioned converter generated voltage harmonics into those...... with deterministic phase and those with probabilistic phase. A case study performed on a string of ten 3MW, Type-IV wind turbines implemented in PSCAD was used to verify the probabilistic SD harmonic model. The probabilistic SD harmonic model can be employed in the planning phase of WPP projects to assess harmonic...
Second and third harmonic measurements at the linac coherent light source
Directory of Open Access Journals (Sweden)
D. Ratner
2011-06-01
Full Text Available The linac coherent light source (LCLS is a self-amplified spontaneous emission (SASE free-electron laser (FEL operating at fundamental photon energies from 0.5 to 10 keV. Characterization of the higher harmonics present in the FEL beam is important to users, for whom harder x rays can either extend the useful operating wavelength range or increase experimental backgrounds. We present measurements of the power in both the second and third harmonics, and compare the results to expectations from simulations. We also present studies of the transport of harmonics to the users, and the harmonic power as a function of electron beam quality.
Banking Audit - Towards a Higher Degree of Harmonization
Directory of Open Access Journals (Sweden)
Adela Socol
2016-11-01
Full Text Available In the last decade, the role and nature of the statutory audit of credit institutions have became controversial, on the base of reconsidering the importance of audit of credit institutions in prevention, detection and managing of the financial crisis. The aim of the study is critical analysis of key aspects regarding the contemporary banking audit, with an emphasis on aspects that affect the quality of banking audit (normative, procedural and organisational aspects of banking audit, the “auditable” character of some banking elements etc. and on the tipology of audit reports of credit institutions (Audit Report to the General Meeting of Shareholders, Additional Report to the Audit Committee of the credit institution, Reports to banking supervisors and Transparency report of auditor. The paper analyses for 27 European states the way in which banking auditors report on the conformity of the credit institution with organisational regulatory rules, regulatory requirements, financial reports to supervisors or special reports to supervisors. The conclusions bring to the foreground major normative changes in the area of the European credit institutions, through reforming strategies of banking audit, through a gradual and an inscreasingly restrictive progress of audit activities and of independence requirements, rotation of auditors, reporting and transparency of credit institutions.
Flow shapes and higher harmonics in anisotropic transverse collective flow
Energy Technology Data Exchange (ETDEWEB)
Argintaru, Danut; Baban, Valerica [Constanta Maritime University, Faculty of Navigation and Naval Transport, Constanta (Romania); Besliu, Calin; Jipa, Alexandru; Grossu, Valeriu [University of Bucharest, Faculty of Physics, Bucharest (Romania); Esanu, Tiberiu; Cherciu, Madalin [Institute of Space Sciences Bucharest-Magurele, Bucharest (Romania)
2017-01-15
In this paper we show that by using a jet-finder algorithm (the Anti-k{sub T} one) on UrQMD/C simulated (Au+Au at 4, 10 and 15A GeV) collisions, we can identify different flow shape structures (single flow stream events, two flow streams events, three flow streams events, etc.) and order the bulk of events in equivalence flow shape classes. Considering these flow streams as the main directions of anisotropic transverse flow, we show that the Fourier coefficients v{sub n} of anisotropic flow are better emphasized when we analyze the different event flow shape classes than when the events are mixed. Also, if we do not know the real orientation of the reaction plane, we can use as reference the Flow stream 1 - the main particle flow stream - orientation (Ψ{sub Flowstream} {sub 1}) to highlight the initial shape of the participant nuclear matter in a central to peripheral collision, and the orientation of the participant plane of order n. (orig.)
Studies of harmonic generation in free electron lasers
Energy Technology Data Exchange (ETDEWEB)
Goldammer, K.
2007-11-12
Nonlinear harmonic generation is one of the most interesting aspects of Free Electron Lasers under study today. It provides for coherent, high intensity radiation at higher harmonics of the FEL resonant frequency. The sources, numerical simulation and applications of harmonic radiation in cascaded High Gain Harmonic Generation FELs were the subject of this thesis. Harmonic emission in FELs originates from harmonic microbunching of the particles and the particular electron trajectory during FEL interaction. Numerical FEL simulation codes model these analytical equations and predict the performance of Free Electron Lasers with good accuracy. This thesis has relied heavily upon the FEL simulation code Genesis 1.3 which has been upgraded in the framework of this thesis to compute harmonic generation in a self-consistent manner. Tests against analytical predictions suggest that the harmonic power levels as well as harmonic gain lengths are simulated correctly. A benchmark with the FEL simulation code GINGER yields excellent agreement of the harmonic saturation length and saturation power. The new version of the simulation code Genesis was also tested against measurements from the VUV-FEL FLASH at DESY. The spectral power distributions of fundamental and third harmonic radiation were recorded at 25.9 nm and 8.6 nm, respectively. The relative bandwidths (FWHM) were in the range of 2 % for both the fundamental as well as the third harmonic, which was accurately reproduced by time-dependent simulations with Genesis. The new code was also used to propose and evaluate a new design for the BESSY Soft X-Ray FEL, a cascaded High Gain Harmonic Generation FEL proposed by BESSY in Berlin. The original design for the BESSY High Energy FEL line requires four HGHG stages to convert the initial seed laser wavelength of 297.5 nm down to 1.24 nm. A new scheme is proposed that makes use of fifth harmonic radiation from the first stage and reduces the number of HGHG stages to three. It
A Broadband and High Gradient RF Cavity for a Compact Proton Synchrotron
Fang, Z; Averboukh, I I; Kijima, Y; Nagayama, T
2002-01-01
A broadband and high gradient RF cavity has been designed for a compact proton synchrotron, which has been approved to develop for radiation therapy, (2000), (2001) and (1999). A maximal high peak voltage of about 20 kV will be applied in the cavity, including the fundamental from 1.7 MHz to 15 MHz, and the second and possibly third harmonics. The design principle of the wideband cavity without tuning system by using high-permeability magnetic alloy (FINEMET) cores is described. Some calculation results will be presented. And a prototype will be developed and tested. (5 refs).
Comparison of high order modes damping techniques for 800 MHz single cell superconducting cavities
Shashkov, Ya V; Zobov, M M
2014-01-01
Currently, applications of 800 MHz harmonic cavities in both bunch lengthening and shortening regimes are under consideration and discussion in the framework of the High Luminosity LHC project. In this paper we study electromagnetic characteristics of high order modes (HOM) for a single cell 800 MHz superconducting cavity and arrays of such cavities connected by drifts tubes. Different techniques for the HOM damping such as beam pipe grooves, coaxial-notch loads, fluted beam pipes etc. are investigated and compared. The influence of the sizes and geometry of the drift tubes on the HOM damping is analyzed.
Eisenbrey, John R; Shaw, Colette M; Lyshchik, Andrej; Machado, Priscilla; Lallas, Costas D; Trabulsi, Edouard J; Merton, Daniel A; Fox, Traci B; Liu, Ji-Bin; Brown, Daniel B; Forsberg, Flemming
2015-07-01
The objective of this study was to evaluate and compare contrast-enhanced subharmonic and harmonic ultrasound as tools for characterizing solid renal masses and monitoring their response to cryoablation therapy. Sixteen patients undergoing percutaneous ablation of a renal mass provided informed consent to undergo ultrasound examinations the morning before and approximately 4 months after cryoablation. Ultrasound contrast parameters during pretreatment imaging were compared to biopsy results obtained during ablation (n = 13). Posttreatment changes were evaluated by a radiologist and compared to contrast-enhanced magnetic resonance imaging (MRI)/computed tomography (CT) follow-up. All masses initially showed heterogeneous enhancement with both subharmonic and harmonic ultrasound. Early contrast washout in the mass relative to the cortex was observed in 6 of 9 malignant and 0 of 4 benign lesions in subharmonic mode and 8 of 9 malignant and 1 of 4 benign lesions in harmonic imaging. In cases where the lesion was adequately visualized at follow-up (n = 12), subharmonic and harmonic ultrasound showed accuracies of 83% and 75%, respectively, in predicting treatment outcome. Although harmonic imaging showed less overall error, no significant differences (P > .29) in ablation cavity volumes were observed between MRI/CT and either contrast-imaging mode. Subharmonic and harmonic contrast-enhanced ultrasound may be a safe and accurate imaging alternative for characterizing renal masses and evaluating their response to cryoablation therapy. Although subharmonic imaging was more accurate in detecting effective cryoablation, harmonic imaging was superior in quantifying ablation cavity volumes. Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.
Generation of single-frequency tunable green light in a coupled ring tapered diode laser cavity
DEFF Research Database (Denmark)
Jensen, Ole Bjarlin; Petersen, Paul Michael
2013-01-01
We report the realization of a tapered diode laser operated in a coupled ring cavity that significantly improves the coherence properties of the tapered laser and efficiently generates tunable light at the second harmonic frequency. The tapered diode laser is tunable with single-frequency output...
RF cavities of CESAR (2 MeV electron storage ring).
Service Photo; CERN PhotoLab
1968-01-01
RF cavity. There were 2 identical ones: one for stacking (accumulation) procedures; the other for scanning with "empty buckets" (measurement of beam density distribution). Both were operated at h=2 (2nd harmonic of the revolution frequency), i.e. at around 24.4 MHz. Voltage, frequency and phase were programmed with analogue circuits.
CESAR, 2 MeV electron storage ring; construction period; RF cavity.
Service Photo; CERN PhotoLab
1962-01-01
RF cavity. There were 2 identical ones: one for stacking (accumulation) procedures; the other for scanning with "empty buckets" (measurement of beam density distribution). Both were operated at h=2 (2nd harmonic of the revolution frequency), i.e. at around 24.4 MHz. Voltage, frequency and phase were programmed with analogue circuits.
Experimental investigation of cavity flows
Energy Technology Data Exchange (ETDEWEB)
Loeland, Tore
1998-12-31
This thesis uses LDV (Laser Doppler Velocimetry), PIV (Particle Image Velocimetry) and Laser Sheet flow Visualisation to study flow inside three different cavity configurations. For sloping cavities, the vortex structure inside the cavities is found to depend upon the flow direction past the cavity. The shape of the downstream corner is a key factor in destroying the boundary layer flow entering the cavity. The experimental results agree well with numerical simulations of the same geometrical configurations. The results of the investigations are used to find the influence of the cavity flow on the accuracy of the ultrasonic flowmeter. A method to compensate for the cavity velocities is suggested. It is found that the relative deviation caused by the cavity velocities depend linearly on the pipe flow. It appears that the flow inside the cavities should not be neglected as done in the draft for the ISO technical report on ultrasonic flowmeters. 58 refs., 147 figs., 2 tabs.
Sums of Generalized Harmonic Series
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 9. Sums of Generalized Harmonic Series: For Kids from Five to Fifteen. Zurab Silagadze. General Article Volume 20 Issue 9 September 2015 pp 822-843 ... Keywords. Riemann zeta function; integral representation; Basel problem.
Tides and tidal harmonics at Umbharat, Gujarat
Digital Repository Service at National Institute of Oceanography (India)
Suryanarayana, A.; Swamy, G.N.
A part of the data on tides recorded at Machiwada near Umbharat, Gulf of Cambay during April 1978 was subjected to harmonic analysis following the Admiralty procedure. The general tidal characteristics and the value of four major harmonic...
Detection of Harmonic Occurring using Kalman Filtering
DEFF Research Database (Denmark)
Hussain, Dil Muhammad Akbar; Shoro, Ghulam Mustafa; Imran, Raja Muhammed
2014-01-01
As long as the load to a power system is linear which has been the case before 80's, typically no harmonics are produced. However, the modern power electronic equipment for controlled power consumption produces harmonic disturbances, these devices/equipment possess nonlinear voltage/current chara...... using Kalman filter. This may be very useful for example to quickly switching on certain filters based on the harmonic present. We are using a unique technique to detect the occurrence of harmonics....
Nye, Kyle; Eslam-Panah, Azar
2016-11-01
Root canal treatment involves the removal of infected tissue inside the tooth's canal system and filling the space with a dense sealing agent to prevent further infection. A good root canal treatment happens when the canals are filled homogeneously and tightly down to the root apex. Such a tooth is able to provide valuable service for an entire lifetime. However, there are some examples of poorly performed root canals where the anterior and posterior routes are not filled completely. Small packets of air can be trapped in narrow access cavities when restoring with resin composites. Such teeth can cause trouble even after many years and lead the conditions like acute bone infection or abscesses. In this study, the filling of dead-end conical cavities with various liquids is reported. The first case studies included conical cavity models with different angles and lengths to visualize the filling process. In this investigation, the rate and completeness at which a variety of liquids fill the cavity were observed to find ideal conditions for the process. Then, a 3D printed model of the scaled representation of a molar with prepared post spaces was used to simulate the root canal treatment. The results of this study can be used to gain a better understanding of the restoration for endodontically treated teeth.
CERN PhotoLab
1983-01-01
See photo 8302397: View from the downstream end of one of the SPS accelerating cavities (200 MHz, travelling wave structure). See 7603195 and 8011289 for more details, 7411032 for the travelling wave structure, and also 8104138. Giacomo Primadei stands on the left.
... sharp pain when eating or drinking something sweet, hot or cold Visible holes or pits in your teeth Brown, black or white staining on any surface of a tooth Pain when you bite down When to see a dentist You may not be aware that a cavity is forming. That's why it's important to have regular dental ...
Niobium superconducting cavity
CERN PhotoLab
1980-01-01
This 5-cell superconducting cavity, made from bulk-Nb, stems from the period of general studies, not all directed towards direct use at LEP. This one is dimensioned for 1.5 GHz, the frequency used at CEBAF and also studied at Saclay (LEP RF was 352.2 MHz). See also 7908227, 8007354, 8209255, 8210054, 8312339.
Additive Manufactured Superconducting Cavities
Holland, Eric; Rosen, Yaniv; Woolleet, Nathan; Materise, Nicholas; Voisin, Thomas; Wang, Morris; Mireles, Jorge; Carosi, Gianpaolo; Dubois, Jonathan
Superconducting radio frequency cavities provide an ultra-low dissipative environment, which has enabled fundamental investigations in quantum mechanics, materials properties, and the search for new particles in and beyond the standard model. However, resonator designs are constrained by limitations in conventional machining techniques. For example, current through a seam is a limiting factor in performance for many waveguide cavities. Development of highly reproducible methods for metallic parts through additive manufacturing, referred to colloquially as 3D printing\\x9D, opens the possibility for novel cavity designs which cannot be implemented through conventional methods. We present preliminary investigations of superconducting cavities made through a selective laser melting process, which compacts a granular powder via a high-power laser according to a digitally defined geometry. Initial work suggests that assuming a loss model and numerically optimizing a geometry to minimize dissipation results in modest improvements in device performance. Furthermore, a subset of titanium alloys, particularly, a titanium, aluminum, vanadium alloy (Ti - 6Al - 4V) exhibits properties indicative of a high kinetic inductance material. This work is supported by LDRD 16-SI-004.
Cavities and atomic packing in protein structures and interfaces.
Directory of Open Access Journals (Sweden)
Shrihari Sonavane
2008-09-01
Full Text Available A comparative analysis of cavities enclosed in a tertiary structure of proteins and interfaces formed by the interaction of two protein subunits in obligate and non-obligate categories (represented by homodimeric molecules and heterocomplexes, respectively is presented. The total volume of cavities increases with the size of the protein (or the interface, though the exact relationship may vary in different cases. Likewise, for individual cavities also there is quantitative dependence of the volume on the number of atoms (or residues lining the cavity. The larger cavities tend to be less spherical, solvated, and the interfaces are enriched in these. On average 15 A(3 of cavity volume is found to accommodate single water, with another 40-45 A(3 needed for each additional solvent molecule. Polar atoms/residues have a higher propensity to line solvated cavities. Relative to the frequency of occurrence in the whole structure (or interface, residues in beta-strands are found more often lining the cavities, and those in turn and loop the least. Any depression in one chain not complemented by a protrusion in the other results in a cavity in the protein-protein interface. Through the use of the Voronoi volume, the packing of residues involved in protein-protein interaction has been compared to that in the protein interior. For a comparable number of atoms the interface has about twice the number of cavities relative to the tertiary structure.
Application of potential harmonic expansion method to BEC ...
Indian Academy of Sciences (India)
We adopt the potential harmonics expansion method for an ab initio solution of the many-body system in a Bose condensate containing interacting bosons. Unlike commonly adopted mean-field theories, our method is capable of handling two-body correlation properly. We disregard three- and higher-body correlations.
Effective harmonic oscillator description of anharmonic molecular ...
Indian Academy of Sciences (India)
Administrator
Abstract. The validity of an effective harmonic oscillator approximation for anharmonic molecular vibrations is tested and compared with vibrational self consistent field and vibrational configurational interaction results. The effective harmonic oscillator is constructed variationally, by taking the trial wave function as a harmonic ...
Third Harmonic Imaging using a Pulse Inversion
DEFF Research Database (Denmark)
Rasmussen, Joachim; Du, Yigang; Jensen, Jørgen Arendt
2011-01-01
The pulse inversion (PI) technique can be utilized to separate and enhance harmonic components of a waveform for tissue harmonic imaging. While most ultrasound systems can perform pulse inversion, only few image the 3rd harmonic component. PI pulse subtraction can isolate and enhance the 3rd...
Harmonic Detection at Initialization With Kalman Filter
DEFF Research Database (Denmark)
Hussain, Dil Muhammad Akbar; Imran, Raja Muhammad; Shoro, Ghulam Mustafa
2014-01-01
the affect of harmonics on the supply. For the detection of these harmonics various techniques are available and one of that technique is the Kalman filter. In this paper we investigate that what are the consequences when harmonic detection system based on Kalman Filtering is initialized...
Application of exponential homotopy algorithm in the inverter harmonic elimination
Zhang, Li
2017-02-01
Eliminating harmonic pollution and improving power factor are the quite important task in the field of power electronics. From the mathematical point of view, harmonic elimination problems can be translated into nonlinear equations. But it is difficult to directly solve the nonlinear equations because of complexity. For this reason, exponential homotopy method is proposed based on homotopy method in this paper. It has focused on built up homotopy equations by modifying the singularities of Jacobian matrix, and on this basis homotopy equations are transformed into the differential initial value problems. Numerical results show that the new exponential homotopy method has higher precision than other algorithms, and the singularity is improved.
The first operation of 56 MHz SRF cavity in RHIC
Energy Technology Data Exchange (ETDEWEB)
Wu, Q. [Brookhaven National Lab. (BNL), Upton, NY (United States); Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Blaskiewicz, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); DeSanto, L. [Brookhaven National Lab. (BNL), Upton, NY (United States); Goldberg, D. [Brookhaven National Lab. (BNL), Upton, NY (United States); Harvey, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Hayes, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); McIntyre, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Mernick, K. [Brookhaven National Lab. (BNL), Upton, NY (United States); Orfin, P. [Brookhaven National Lab. (BNL), Upton, NY (United States); Seberg, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Severino, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Smith, K. [Brookhaven National Lab. (BNL), Upton, NY (United States); Than, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zaltsman, A. [Brookhaven National Lab. (BNL), Upton, NY (United States)
2015-05-03
A 56 MHz superconducting RF cavity has been designed, fabricated and installed in the Relativistic Heavy Ion Collider (RHIC). The cavity operates at 4.4 K with a “quiet helium source” to isolate the cavity from environmental acoustic noise. The cavity is a beam driven quarter wave resonator. It is detuned and damped during injection and acceleration cycles and is brought to operation only at store energy. For a first test operation, the cavity voltage was stabilized at 300 kV with full beam current. Within both Au + Au and asymmetrical Au + He3 collisions, luminosity improvement was detected from direct measurement, and the hourglass effect was reduced. One higher order mode (HOM) coupler was installed on the cavity. We report in this paper on our measurement of a broadband HOM spectrum excited by the Au beam.
Single-cell LEP-type cavity on measurement stand
CERN PhotoLab
1982-01-01
A single-cell cavity, made of copper, with tapered connectors for impedance measurements. It was used as a model of LEP-type superconducting cavities, to investigate impedance and higher-order modes and operated at around 600 MHz (the LEP acceleration frequency was 352.2 MHz). See 8202500.
How to get more collisions at the LHC / crab cavities
2017-01-01
(short version) HL-LHC crab cavity engineer Ofelia Capatin, HL-LHC RF system leader Rama Calaga and HL-LHC project leader Lucio Rossiexplain how the introduction of the new Crab Cavities will enable higher luminosities at the HL-LHC.
I. Badran; A. L. Mahmood; M. T. Lazim
2008-01-01
n integral-cycle triggering mode of voltage control, subharmonic as well as higher order harmonic components are generated in the load voltage waveforms of a three-phase system. These harmonic components are found to be unbalanced in phase displacement. The correction of the unbalanced phase displacement angles of a particular subharmonic or higher order harmonic for this type of triggering is investigated to solve the limitation of use of this important type of control as a drive and many ot...
Entanglement of a two-atom system driven by the quantum vacuum in arbitrary cavity size
Energy Technology Data Exchange (ETDEWEB)
Flores-Hidalgo, G., E-mail: gfloreshidalgo@unifei.edu.br [Instituto de Física e Química, Universidade Federal de Itajubá, 37500-903, Itajubá, MG (Brazil); Rojas, M., E-mail: moises.leyva@dfi.ufla.br [Departamento de Física, Universidade Federal de Lavras, CP 3037, 37200-000, Lavras, MG (Brazil); Rojas, Onofre, E-mail: ors@dfi.ufla.br [Departamento de Física, Universidade Federal de Lavras, CP 3037, 37200-000, Lavras, MG (Brazil)
2017-05-10
We study the entanglement dynamics of two distinguishable atoms confined into a cavity and interacting with a quantum vacuum field. As a simplified model for this system, we consider two harmonic oscillators linearly coupled to a massless scalar field which are inside a spherical cavity of radius R. Through the concurrence, the entanglement dynamics for the two-atom system is discussed for a range of initial states composed of a superposition of atomic states. Our results reveal how the entanglement of the two atoms behaves through the time evolution, in a precise way, for arbitrary cavity size and for arbitrary coupling constant. All our computations are analytical and only the final step is numerical. - Highlights: • Entanglement time evolution in arbitrary cavity size is considered. • In free space concurrence approaches a fixed value at large time. • For finite cavity, concurrence behaves almost as a periodic function of time.
The Local Stellar Velocity Field via Vector Spherical Harmonics
Makarov, V. V.; Murphy, D. W.
2007-01-01
We analyze the local field of stellar tangential velocities for a sample of 42,339 nonbinary Hipparcos stars with accurate parallaxes, using a vector spherical harmonic formalism.We derive simple relations between the parameters of the classical linear model (Ogorodnikov-Milne) of the local systemic field and low-degree terms of the general vector harmonic decomposition. Taking advantage of these relationships, we determine the solar velocity with respect to the local stars of (V(sub X), V(sub Y), V(sub Z)) = (10.5, 18.5, 7.3) +/- 0.1 km s(exp -1) not for the asymmetric drift with respect to the local standard of rest. If only stars more distant than 100 pc are considered, the peculiar solar motion is (V(sub X), V(sub Y), V(sub Z)) = (9.9, 15.6, 6.9) +/- 0.2 km s(exp -1). The adverse effects of harmonic leakage, which occurs between the reflex solar motion represented by the three electric vector harmonics in the velocity space and higher degree harmonics in the proper-motion space, are eliminated in our analysis by direct subtraction of the reflex solar velocity in its tangential components for each star...
Superconducting cavity material for the European XFEL
Singer, W.; Singer, X.; Brinkmann, A.; Iversen, J.; Matheisen, A.; Navitski, A.; Tamashevich, Y.; Michelato, P.; Monaco, L.
2015-08-01
Analysis of the strategy for superconducting cavity material procurement and quality management is done on the basis of the experience with the cavity production for the European x-ray free electron laser (EXFEL) facility. An adjustment of the material specification to EXFEL requirements, procurement of material, quality control (QC), documentation, and shipment to cavity producers have been worked out and carried out by DESY. A multistep process of qualification of the material suppliers included detailed material testing, single- and nine-cell cavity fabrication, and cryogenic radiofrequency tests. Production of about 25 000 semi-finished parts of high purity niobium and niobium-titanium alloy in a period of three years has been divided finally between companies Heraeus, Tokyo Denkai, Ningxia OTIC, and PLANSEE. Consideration of large-grain (LG) material as a possible option for the EXFEL has resulted in the production of one cryogenic module consisting of seven (out of eight) LG cavities. LG materials fulfilled the EXFEL requirements and showed even 25% to 30% higher unloaded quality factor. A possible shortage of the required quantity of LG material on the market led, however, to the choice of conventional fine-grain (FG) material. Eddy-current scanning (ECS) has been applied as an additional QC tool for the niobium sheets and contributed significantly to the material qualification and sorting. Two percent of the sheets have been rejected, which potentially could affect up to one-third of the cavities. The main imperfections and defects in the rejected sheets have been analyzed. Samples containing foreign material inclusions have been extracted from the sheets and electrochemically polished. Some inclusions remained even after 150 μm surface layer removal. Indications of foreign material inclusions have been found in the industrially fabricated and treated cavities and a deeper analysis of the defects has been performed.
Static harmonization of dynamically harmonized Fourier transform ion cyclotron resonance cell.
Zhdanova, Ekaterina; Kostyukevich, Yury; Nikolaev, Eugene
2017-08-01
Static harmonization in the Fourier transform ion cyclotron resonance cell improves the resolving power of the cell and prevents dephasing of the ion cloud in the case of any trajectory of the charged particle, not necessarily axisymmetric cyclotron (as opposed to dynamic harmonization). We reveal that the Fourier transform ion cyclotron resonance cell with dynamic harmonization (paracell) is proved to be statically harmonized. The volume of the statically harmonized potential distribution increases with an increase in the number of trap segments.
Changeability of Oral Cavity Environment
Surdacka, Anna; Strzyka?a, Krystyna; Rydzewska, Anna
2007-01-01
Objectives In dentistry, the results of in vivo studies on drugs, dental fillings or prostheses are routinely evaluated based on selected oral cavity environment parameters at specific time points. Such evaluation may be confounded by ongoing changes in the oral cavity environment induced by diet, drug use, stress and other factors. The study aimed to confirm oral cavity environment changeability. Methods 24 healthy individuals aged 20?30 had their oral cavity environment prepared by having p...
Data harmonization and model performance
The Joint Committee on Urban Storm Drainage of the International Association for Hydraulic Research (IAHR) and International Association on Water Pollution Research and Control (IAWPRC) was formed in 1982. The current committee members are (no more than two from a country): B. C. Yen, Chairman (USA); P. Harremoes, Vice Chairman (Denmark); R. K. Price, Secretary (UK); P. J. Colyer (UK), M. Desbordes (France), W. C. Huber (USA), K. Krauth (FRG), A. Sjoberg (Sweden), and T. Sueishi (Japan).The IAHR/IAWPRC Joint Committee is forming a Task Group on Data Harmonization and Model Performance. One objective is to promote international urban drainage data harmonization for easy data and information exchange. Another objective is to publicize available models and data internationally. Comments and suggestions concerning the formation and charge of the Task Group are welcome and should be sent to: B. C. Yen, Dept. of Civil Engineering, Univ. of Illinois, 208 N. Romine St., Urbana, IL 61801.
Optimization of photonic crystal cavities
DEFF Research Database (Denmark)
Wang, Fengwen; Sigmund, Ole
2017-01-01
We present optimization of photonic crystal cavities. The optimization problem is formulated to maximize the Purcell factor of a photonic crystal cavity. Both topology optimization and air-hole-based shape optimization are utilized for the design process. Numerical results demonstrate...... that the Purcell factor of the photonic crystal cavity can be significantly improved through optimization....
Simulation of a high harmonic gyrotron with axis-encircling beam and permanent magnet
S.P.SABCHEVSKI; IDEHARA, T; Ogawa, I.; M.GLYAVIN; Ohashi , K.
2002-01-01
A compute code for simulation of beam-field interaction in a resonant cavity of a gyrotron has been developed. It is based on a self-consistent, time-independent, single-mode physical model. The code has been applied to the analysis of the electrodynamical system of a novel high-harmonic gyrotron physical model and the use of the numerical experiment are presented and discussed.
Enhanced Method for Cavity Impedance Calculations
Energy Technology Data Exchange (ETDEWEB)
Frank Marhauser, Robert Rimmer, Kai Tian, Haipeng Wang
2009-05-01
With the proposal of medium to high average current accelerator facilities the demand for cavities with extremely low Higher Order Mode (HOM) impedances is increasing. Modern numerical tools are still under development to more thoroughly predict impedances that need to take into account complex absorbing boundaries and lossy materials. With the usually large problem size it is preferable to utilize massive parallel computing when applicable and available. Apart from such computational issues, we have developed methods using available computer resources to enhance the information that can be extracted from a cavities? wakefield computed in time domain. In particular this is helpful for a careful assessment of the extracted RF power and the mitigation of potential beam break-up or emittance diluting effects, a figure of merit for the cavity performance. The method is described as well as an example of its implementation.
Properties of a cusp diamagnetic cavity boundary
Directory of Open Access Journals (Sweden)
B. M. Walsh
2008-11-01
Full Text Available While crossing through the high-altitude dayside cusp on 29 September 1978 and again on 30 October 1978, the ISEE-1 spacecraft observed enhanced energetic particle flux and a depressed and turbulent magnetic field, the signature characteristics of a cusp diamagnetic cavity. As ISEE-1 approached the cavity during each event, a boundary sounding technique was used to measure properties of an emitting boundary. Sounding over multiple energy channels reveals an energy dependent boundary with lower energy particles filling a larger cavity than higher energy particles. Relative motion of the boundary as well as boundary orientation are also measured. The two cusp events were measured at different locations and during different geomagnetic and solar wind conditions; however, they show similar results.
Properties of a cusp diamagnetic cavity boundary
Walsh, B. M.; Fritz, T. A.; Chen, J.
2008-11-01
While crossing through the high-altitude dayside cusp on 29 September 1978 and again on 30 October 1978, the ISEE-1 spacecraft observed enhanced energetic particle flux and a depressed and turbulent magnetic field, the signature characteristics of a cusp diamagnetic cavity. As ISEE-1 approached the cavity during each event, a boundary sounding technique was used to measure properties of an emitting boundary. Sounding over multiple energy channels reveals an energy dependent boundary with lower energy particles filling a larger cavity than higher energy particles. Relative motion of the boundary as well as boundary orientation are also measured. The two cusp events were measured at different locations and during different geomagnetic and solar wind conditions; however, they show similar results.
Harmonic vibrations of multispan beams
DEFF Research Database (Denmark)
Dyrbye, Claes
1996-01-01
Free and forced harmonic vibrations of multispan beams are determined by a method which implies 1 equation regardless of the configuration. The necessary formulas are given in the paper. For beams with simple supports and the same length of all (n) spans, there is a rather big difference between...... the n´th and the (n+1)´th eigenfrequency. The reason for this phenomenon is explained.Keywords: Vibrations, Eigenfrequencies, Beams....
Representation Discovery using Harmonic Analysis
Mahadevan, Sridhar
2008-01-01
Representations are at the heart of artificial intelligence (AI). This book is devoted to the problem of representation discovery: how can an intelligent system construct representations from its experience? Representation discovery re-parameterizes the state space - prior to the application of information retrieval, machine learning, or optimization techniques - facilitating later inference processes by constructing new task-specific bases adapted to the state space geometry. This book presents a general approach to representation discovery using the framework of harmonic analysis, in particu
Renormalization for free harmonic oscillators
Sonoda, H.
2013-01-01
We introduce a model of free harmonic oscillators that requires renormalization. The model is similar to but simpler than the soluble Lee model. We introduce two concrete examples: the first, resembling the three dimensional $\\phi^4$ theory, needs only mass renormalization, and the second, resembling the four dimensional $\\phi^4$ theory and the Lee model, needs additional renormalization of a coupling and a wave function.
Shen, Che-Chou; Wang, Hui-Ting
2013-03-01
The presence of tissue harmonic generation during acoustic propagation is one major limitation in nonlinear detection of microbubble contrast agents. However, conventional solutions for tissue harmonic suppression are not applicable in dual-frequency (DF) harmonic imaging. In DF harmonic imaging, the second harmonic signal at second harmonic (2f(0)) frequency and the inter-modulation harmonic signal at fundamental (f(0)) frequency are simultaneously generated for imaging and both need to be suppressed to improve contrast-to-tissue ratio (CTR). In this study, a novel phase-coded pulse sequence is developed to accomplish DF tissue harmonic suppression. Phase-coded pulse sequence utilizes multiple firings with equidistant transmit phase for harmonic cancellation in the sum of respective echoes. For the f(0) transmit component, the transmit phase comes from the equidistant set of {-2π/3, 0, 2π/3} to suppress the second harmonic signal at 2f(0) frequency. Moreover, in order to provide the inter-modulation harmonic suppression at f(0) frequency, the 2f(0) transmit phase has to be particularly manipulated for the corresponding f(0) transmit phase. The proposed three-pulse sequence can remove not only the second-order harmonic signal but also other higher-order counterparts at both f(0) and 2f(0) frequencies. Measurements were performed at f(0) equal to 2.25 MHz and using hydrophone in water and contrast agents in tissue phantom. Experimental results indicate that the sequence reduces the tissue harmonic magnitude by about 20 dB along the entire axial depths and the corresponding CTR improves at both frequencies. In DF harmonic imaging, the proposed phase-coded sequence can effectively remove the tissue harmonic background at both f(0) and 2f(0) frequencies for improvement of contrast detection. Copyright © 2012 Elsevier B.V. All rights reserved.
Digital Cavity Resonance Monitor, alternative method of measuring cavity microphonics
Energy Technology Data Exchange (ETDEWEB)
Tomasz Plawski; G. Davis; Hai Dong; J. Hovater; John Musson; Thomas Powers
2005-09-20
As is well known, mechanical vibration or microphonics in a cryomodule causes the cavity resonance frequency to change at the vibration frequency. One way to measure the cavity microphonics is to drive the cavity with a Phase Locked Loop. Measurement of the instantaneous frequency or PLL error signal provides information about the cavity microphonic frequencies. Although the PLL error signal is available directly, precision frequency measurements require additional instrumentation, a Cavity Resonance Monitor (CRM). The analog version of such a device has been successfully used for several cavity tests [1]. In this paper we present a prototype of a Digital Cavity Resonance Monitor designed and built in the last year. The hardware of this instrument consists of an RF downconverter, digital quadrature demodulator and digital processor motherboard (Altera FPGA). The motherboard processes received data and computes frequency changes with a resolution of 0.2 Hz, with a 3 kHz output bandwidth.
Colloquium: cavity optomechanics
2011-01-01
Monday 14 November 2011, 17:00 Ecole de Physique, Auditoire Stueckelberg Université de Genève Cavity optomechanics: controlling micro mechanical oscillators with laser light Prof. Tobias Kippenberg EPFL, Lausanne Laser light can be used to cool and to control trapped ions, atoms and molecules at the quantum level. This has lead to spectacular advances such as the most precise atomic clocks. An outstanding frontier is the control with lasers of nano- and micro-mechancial systems. Recent advances in cavity optomechanics have allowed such elementary control for the first time, enabling mechanical systems to be ground state cooled leading to readout with quantum limited sensitivity and permitting to explore new device concepts resulting from radiation pressure.
Cavity enhanced atomic magnetometry.
Crepaz, Herbert; Ley, Li Yuan; Dumke, Rainer
2015-10-20
Atom sensing based on Faraday rotation is an indispensable method for precision measurements, universally suitable for both hot and cold atomic systems. Here we demonstrate an all-optical magnetometer where the optical cell for Faraday rotation spectroscopy is augmented with a low finesse cavity. Unlike in previous experiments, where specifically designed multipass cells had been employed, our scheme allows to use conventional, spherical vapour cells. Spherical shaped cells have the advantage that they can be effectively coated inside with a spin relaxation suppressing layer providing long spin coherence times without addition of a buffer gas. Cavity enhancement shows in an increase in optical polarization rotation and sensitivity compared to single-pass configurations.
Cavity enhanced atomic magnetometry
Crepaz, Herbert; Dumke, Rainer
2015-01-01
Atom sensing based on Faraday rotation is an indispensable method for precision measurements, universally suitable for both hot and cold atomic systems. Here we demonstrate an all-optical magnetometer where the optical cell for Faraday rotation spectroscopy is augmented with a low finesse cavity. Unlike in previous experiments, where specifically designed multipass cells had been employed, our scheme allows to use conventional, spherical vapour cells. Spherical shaped cells have the advantage that they can be effectively coated inside with a spin relaxation suppressing layer providing long spin coherence times without addition of a buffer gas. Cavity enhancement shows in an increase in optical polarization rotation and sensitivity compared to single-pass configurations.
Input Harmonic Analysis on the Slim DC-Link Drive Using Harmonic State Space Model
DEFF Research Database (Denmark)
Yang, Feng; Kwon, Jun Bum; Wang, Xiongfei
2017-01-01
variation according to the switching instant, the harmonics at the steady-state condition, as well as the coupling between the multiple harmonic impedances. By using this model, the impaction on the harmonics performance by the film capacitor and the grid inductance is derived. Simulation and experimental......The harmonic performance of the slim dc-link adjustable speed drives has shown good performance in some studies but poor in some others. The contradiction indicates that a feasible theoretical analysis is still lacking to characterize the harmonic distortion for the slim dc-link drive. Considering...... the shortcomings of the present harmonic analysis methods, such as the time-domain simulation, or the Fourier analysis, this paper proposes a Harmonic State Space model to study the harmonics performance for this type of drive. In this study, this model is utilized to describe the behavior of the harmonic...
Harmonic generation in the generalized Sagdeev pseudopotential
Akbari-Moghanjoughi, M.
2017-09-01
In this paper, we study the nonlinear harmonic generation effect in different oscillator models. For weakly nonlinear systems, we use the generalized forced Korteweg de Vries Burgers (KdVB) and modified KdVB (mKdVB) models in order to classify three fundamentally different harmonic structures in a nonlinear dynamical system. The first is called the internal harmonic structure which exists due to the self oscillation of the system in the absence of dissipation effect and is shown to follow either relations of nf or (2n - 1)f depending on the symmetry of oscillator potential in which n is an integer number and f is the fundamental frequency which is exactly obtained for the Helmholtz oscillator. The second structure is the resonant harmonics which appears in the presence of damping and follows the harmonic structure nf0 in which f0 is the linear resonance frequency. Finally, the last harmonic structure appears in the presence of dissipation and external periodic forcing effects which we call the external harmonic pattern. It is shown that the external harmonic pattern, in which f1 is the driving frequency, always follows the nf1 rule regardless of the potential symmetry. We then extend our analysis to study the harmonic generation in the fully nonlinear generalized Sagdeev potential for real plasmas with isothermal and adiabatic ion fluids and investigate the effects of different plasma parameters such as the fractional ion temperature and normalized ion acoustic speed on all three kinds of harmonic generation.
Harmonic states for the free particle
Energy Technology Data Exchange (ETDEWEB)
Guerrero, J [Departamento de Matematica Aplicada, Universidad de Murcia, Campus de Espinardo, 30100 Murcia (Spain); Lopez-Ruiz, F F; Aldaya, V; Cossio, F, E-mail: juguerre@um.es, E-mail: flopez@iaa.es, E-mail: valdaya@iaa.es, E-mail: focossiop@gmail.com [Instituto de Astrofisica de Andalucia, CSIC, Apartado Postal 3004, 18080 Granada (Spain)
2011-11-04
Different families of states, which are solutions of the time-dependent free Schroedinger equation, are imported from the harmonic oscillator using the quantum Arnold transformation introduced in Aldaya et al (2011 J. Phys. A: Math. Theor.44 065302). Among them, infinite series of states are given that are normalizable, expand the whole space of solutions, are spatially multi-localized and are eigenstates of a suitably defined number operator. Associated with these states new sets of coherent and squeezed states for the free particle are defined representing traveling, squeezed, multi-localized wave packets. These states are also constructed in higher dimensions, leading to the quantum mechanical version of the Hermite-Gauss and Laguerre-Gauss states of paraxial wave optics. Some applications of these new families of states and procedures to experimentally realize and manipulate them are outlined. (paper)
Coherent states for the relativistic harmonic oscillator
Aldaya, Victor; Guerrero, J.
1995-01-01
Recently we have obtained, on the basis of a group approach to quantization, a Bargmann-Fock-like realization of the Relativistic Harmonic Oscillator as well as a generalized Bargmann transform relating fock wave functions and a set of relativistic Hermite polynomials. Nevertheless, the relativistic creation and annihilation operators satisfy typical relativistic commutation relations of the Lie product (vector-z, vector-z(sup dagger)) approximately equals Energy (an SL(2,R) algebra). Here we find higher-order polarization operators on the SL(2,R) group, providing canonical creation and annihilation operators satisfying the Lie product (vector-a, vector-a(sup dagger)) = identity vector 1, the eigenstates of which are 'true' coherent states.
Exact diagonalization of the D-dimensional spatially confined quantum harmonic oscillator
Directory of Open Access Journals (Sweden)
Kunle Adegoke
2016-01-01
Full Text Available In the existing literature various numerical techniques have been developed to quantize the confined harmonic oscillator in higher dimensions. In obtaining the energy eigenvalues, such methods often involve indirect approaches such as searching for the roots of hypergeometric functions or numerically solving a differential equation. In this paper, however, we derive an explicit matrix representation for the Hamiltonian of a confined quantum harmonic oscillator in higher dimensions, thus facilitating direct diagonalization.
DEFF Research Database (Denmark)
Lascu, C.; Asiminoaei, L.; Boldea, I.
2009-01-01
different. It emerges that the fourth one has superior behavior and robustness and can stably work at higher frequencies than the others. Theoretical findings and analysis are supported by comparative experimental results on a 7-kVA laboratory setup. The highest harmonic frequency that can be stably...... to achieve zero phase shift and unity gain in the closed-loop transfer function for selected harmonics. The complete current controller is the superposition of all individual harmonic controllers and may be implemented in various reference frames. The analysis is focused on the comparison of harmonic...... and total closed-loop transfer functions for each controller. Analytical similarities and differences between schemes in terms of frequency response characteristics are emphasized. It is concluded that three of them have identical harmonic behavior despite the fact that their implementation is significantly...
Tunable passively harmonic mode-locked Yb-doped fiber laser with Lyot-Sagnac filter.
Li, Ming; Zou, Xin; Wu, Jian; Shi, Jindan; Qiu, Jifang; Hong, Xiaobin
2015-10-10
A novel passively harmonic mode-locked dissipative soliton Yb-doped fiber laser with all normal dispersion is proposed and experimentally demonstrated based on a semiconductor saturable absorption mirror and tunable Lyot-Sagnac filter. By only tuning the bandwidth of the filter at fixed pump power, the repetition rate of 9.87 to 167.8 MHz (corresponding to 17th-order harmonic) is obtained. This is the highest repetition rate and harmonic order for a passively harmonic mode-locked dissipative soliton Yb-doped fiber laser with all-normal dispersion to the best of our knowledge. The signal-to-noise ratio and super-mode suppression ratio for all harmonic orders are higher than 65 and 35 dB, respectively, which shows the high stability of the fiber laser.
Cai, Jiandong; Wang, Michael Yu; Zhang, Li
2015-12-01
In multifrequency atomic force microscopy (AFM), probe's characteristic of assigning resonance frequencies to integer harmonics results in a remarkable improvement of detection sensitivity at specific harmonic components. The selection criterion of harmonic order is based on its amplitude's sensitivity on material properties, e.g., elasticity. Previous studies on designing harmonic probe are unable to provide a large design capability along with maintaining the structural integrity. Herein, we propose a harmonic probe with step cross section, in which it has variable width in top and bottom steps, while the middle step in cross section is kept constant. Higher order resonance frequencies are tailored to be integer times of fundamental resonance frequency. The probe design is implemented within a structural optimization framework. The optimally designed probe is micromachined using focused ion beam milling technique, and then measured with an AFM. The measurement results agree well with our resonance frequency assignment requirement.
The Harmonics of Kansei Images
DEFF Research Database (Denmark)
Su, Jianning; Restrepo-Giraldo, John Dairo
2008-01-01
Delivering the right product experience, which is a user’s reflection of a combination of functionality, usage, cost and appearance, is a key factor for product acquisition and commercial success. Establishing and representing the relation between a product’s shape and the perceived aesthetic...... sensibility it elicits on a person (kansei), is a key factor in the design of tools to support designers in delivering the right product’s appearance. This paper presents an approach to mathematically represent a product’s kansei based on the frequency signature (harmonics) of a shape. This mathematical...
Making space for harmonic oscillators
Energy Technology Data Exchange (ETDEWEB)
Michelotti, Leo; /Fermilab
2004-11-01
If we restrict the number of harmonic oscillator energy eigenstates to some finite value, N, then the discrete spectrum of the corresponding position operator comprise the roots of the Hermite polynomial H{sub N+1}. Its range is just large enough to accommodate classical motion at high energy. A negative energy term must be added to the Hamiltonian which affects only the last eigenstate, |N>, suggesting it is concentrated at the extrema of this finite ''space''. Calculations support a conjecture that, in the limit of large N, the global distribution of points approaches the differential form for classical action.
1983-01-01
In each ISR ring the radiofrequency cavities were installed in one 9 m long straight section. The RF system of the ISR had the main purpose to stack buckets of particles (most of the time protons)coming from the CPS and also to accelerate the stacked beam. The installed RF power per ring was 18 kW giving a peak accelerating voltage of 20 kV. The system had a very fine regulation feature allowing to lower the voltage down to 75 V in a smooth and well controlled fashion.
Zhuo, G-Y; Lee, H; Hsu, K-J; Huttunen, M J; Kauranen, M; Lin, Y-Y; Chu, S-W
2014-03-01
Chirality is one of the most fundamental and essential structural properties of biological molecules. Many important biological molecules including amino acids and polysaccharides are intrinsically chiral. Conventionally, chiral species can be distinguished by interaction with circularly polarized light, and circular dichroism is one of the best-known approaches for chirality detection. As a linear optical process, circular dichroism suffers from very low signal contrast and lack of spatial resolution in the axial direction. It has been demonstrated that by incorporating nonlinear interaction with circularly polarized excitation, second-harmonic generation circular dichroism can provide much higher signal contrast. However, previous circular dichroism and second-harmonic generation circular dichroism studies are mostly limited to probe chiralities at surfaces and interfaces. It is known that second-harmonic generation, as a second-order nonlinear optical effect, provides excellent optical sectioning capability when combined with a laser-scanning microscope. In this work, we combine the axial resolving power of second-harmonic generation and chiral sensitivity of second-harmonic generation circular dichroism to realize three-dimensional chiral detection in biological tissues. Within the point spread function of a tight focus, second-harmonic generation circular dichroism could arise from the macroscopic supramolecular packing as well as the microscopic intramolecular chirality, so our aim is to clarify the origins of second-harmonic generation circular dichroism response in complicated three-dimensional biological systems. The sample we use is starch granules whose second-harmonic generation-active molecules are amylopectin with both microscopic chirality due to its helical structure and macroscopic chirality due to its crystallized packing. We found that in a starch granule, the second-harmonic generation for right-handed circularly polarized excitation is
Harmonic focus in thyroidectomy for substernal goiter
DEFF Research Database (Denmark)
Hahn, Christoffer Holst; Trolle, Waldemar; Sørensen, Christian Hjort
2015-01-01
OBJECTIVES: No previous prospective study has evaluated harmonic scalpel in thyroidectomy for substernal goiter. The objective of this study was to evaluate the use of harmonic scalpel (FOCUS shear, Ethicon Endo-Surgery) in thyroidectomy for substernal goiter for blood loss, operative time...... and 121 patients had harmonic scalpel thyroidectomy. RESULTS: The use of harmonic scalpel was associated with significant reduction in intraoperative blood loss (50 vs. 100mL, p=0.001), postoperative haemorrhage (4% vs. 12%, p=0.03) and length of hospital stay (2 vs. 3 days, p=0.001). The mean operative...... time was significantly longer in the harmonic group. CONCLUSION: Harmonic scalpel is a safe tool for thyroidectomy for substernal goiter. Its utilisation is associated with reduced blood loss, lower incidence of postoperative haemorrhage and shorter hospital stay....
Yang, Yi; Ng, Ching-Tai; Kotousov, Andrei; Sohn, Hoon; Lim, Hyung Jin
2018-01-01
This paper presents experimental and theoretical analyses of the second harmonic generation due to non-linear interaction of Lamb waves with a fatigue crack. Three-dimensional (3D) finite element (FE) simulations and experimental studies are carried out to provide physical insight into the mechanism of second harmonic generation. The results demonstrate that the 3D FE simulations can provide a reasonable prediction on the second harmonic generated due to the contact nonlinearity at the fatigue crack. The effect of the wave modes on the second harmonic generation is also investigated in detail. It is found that the magnitude of the second harmonic induced by the interaction of the fundamental symmetric mode (S0) of Lamb wave with the fatigue crack is much higher than that by the fundamental anti-symmetric mode (A0) of Lamb wave. In addition, a series of parametric studies using 3D FE simulations are conducted to investigate the effect of the fatigue crack length to incident wave wavelength ratio, and the influence of the excitation frequency on the second harmonic generation. The outcomes show that the magnitude and directivity pattern of the generated second harmonic depend on the fatigue crack length to incident wave wavelength ratio as well as the ratio of S0 to A0 incident Lamb wave amplitude. In summary, the findings of this study can further advance the use of second harmonic generation in damage detection.
Recognition of transposed melodies: Effects of pitch distance and harmonic distance.
Kleinsmith, Abigail L; Neill, W Trammell
2017-11-27
People easily recognize a familiar melody in a previously unheard key, but they also retain some key-specific information. Does the recognition of a transposed melody depend on either pitch distance or harmonic distance from the initially learned instances? Previous research has shown a stronger effect of pitch closeness than of harmonic similarity, but did not directly test for an additional effect of the latter variable. In the present experiment, we familiarized participants with a simple eight-note melody in two different keys (C and D) and then tested their ability to discriminate the target melody from foils in other keys. The transpositions included were to the keys of C# (close in pitch height, but harmonically distant), G (more distant in pitch, but harmonically close), and F# (more distant in pitch and harmonically distant). Across participants, the transpositions to F# and G were either higher or lower than the initially trained melodies, so that their average pitch distances from C and D were equated. A signal detection theory analysis confirmed that discriminability (d') was better for targets and foils that were close in pitch distance to the studied exemplars. Harmonic similarity had no effect on discriminability, but it did affect response bias (c), in that harmonic similarity to the studied exemplars increased both hits and false alarms. Thus, both pitch distance and harmonic distance affect the recognition of transposed melodies, but with dissociable effects on discrimination and response bias.
Efficient third harmonic generation in photonic nanowires
Broderick, N.G.R.; Lohe, M. A.; Lee, T; Shaaram, Afshar V.; Monro, T.M.
2013-01-01
In a photonic nanowire the strong optical confinement allows for the phase matching of nonlinear interactions that would not normally be phase matched, while the large longitudinal component of the electric field serves to further enhance the effective nonlinearity. Thus such waveguides are good choices for studying nonlinear effects such as third harmonic generation. In this paper we analyse third harmonic generation analytically and present the criteria for optimal harmonic generation. In a...
Harmonics Monitoring Survey on LED Lamps
Abdelrahman Ahmed Akila; Kamelia Youssef; Ibrahim Yassin
2017-01-01
Light Emitting Diode (LED) lamps are being increasingly used in many applications. These LED lamps operate using a driver, which is a switching device. Hence, LED lamps will be a source of harmonics in the power system. These harmonics if not well treated, may cause severe performance and operational problems. In this paper, harmonics (amplitude and phase angles) generated by both LED lamps and conventional fluorescent lamps will be studied practically. Then they will be analyzed and evaluate...
Introduction to classical and quantum harmonic oscillators
Bloch, Sylvan C
2013-01-01
From conch shells to lasers . harmonic oscillators, the timeless scientific phenomenon As intriguing to Galileo as they are to scientists today, harmonic oscillators have provided a simple and compelling paradigm for understanding the complexities that underlie some of nature's and mankind's most fascinating creations. From early string and wind instruments fashioned from bows and seashells to the intense precision of lasers, harmonic oscillators have existed in various forms, as objects of beauty and scientific use. And harmonic oscillation has endured as one of science's most fascinating con
Effects of harmonic roving on pitch discrimination
DEFF Research Database (Denmark)
Santurette, Sébastien; de Kérangal, Mathilde le Gal; Joshi, Suyash Narendra
2015-01-01
to impair pitch discrimination performance. Fundamental-frequency difference limens (F0DLs) were obtained in normal-hearing listeners with and without musical training for complex tones filtered between 1.5 and 3.5 kHz with F0s of 300 Hz (resolved harmonics) and 75 Hz (unresolved harmonics). The harmonicity...... of the tone complexes was varied by systematically roving the frequency of individual harmonics, which was taken from a Gaussian distribution centered on the nominal frequency in every stimulus presentation. The amount of roving was determined by the standard deviation of this distribution, which varied...
Effect of undulator harmonics field on free-electron laser harmonic generation
Directory of Open Access Journals (Sweden)
Qika Jia
2011-06-01
Full Text Available The harmonics field effect of a planar undulator on free-electron laser (FEL harmonic generation has been analyzed. For both the linear case and the nonlinear case, the harmonic fraction of the radiation can be characterized by the coupling coefficients. The modification of the coupling coefficients is given when the third harmonics magnetic field component exists, thus the enhancement of the harmonic radiation can be predicted. The numerical results show that with the third harmonics magnetic field component that has the opposite sign to the fundamental, the intensity of third-harmonic radiation can be increased distinctly for both the small signal gain and the nonlinear harmonic generation. The increase is larger for the smaller undulator deflecting parameter.
Directory of Open Access Journals (Sweden)
Gisele Alborghetti Nai
2011-06-01
Full Text Available Mycetoma is a pathological process in which eumycotic (fungal or actinomycotic causative agents from exogenous source produce grains. It is a localized chronic and deforming infectious disease of subcutaneous tissue, skin and bones. We report the first case of eumycetoma of the oral cavity in world literature. CASE REPORT: A 43-year-old male patient, complaining of swelling and fistula in the hard palate. On examination, swelling of the anterior and middle hard palate, with fistula draining a dark liquid was observed. The panoramic radiograph showed extensive radiolucent area involving the region of teeth 21-26 and the computerized tomography showed communication with the nasal cavity, suggesting the diagnosis of periapical cyst. Surgery was performed to remove the lesion. Histopathological examination revealed purulent material with characteristic grain. Gram staining for bacteria was negative and Grocott-Gomori staining for the detection of fungi was positive, concluding the diagnosis of eumycetoma. The patient was treated with ketoconazole for nine months, and was considered cured at the end of treatment. CONCLUSION: Histopathological examination, using histochemical staining, and direct microscopic grains examination can provide the distinction between eumycetoma and actinomycetoma accurately.
A New RF System for the CEBAF Normal Conducting Cavities
Energy Technology Data Exchange (ETDEWEB)
Curt Hovater; Hai Dong; Alicia Hofler; George Lahti; John Musson; Tomasz Plawski
2004-08-01
The CEBAF Accelerator at Jefferson Lab is a 6 GeV five pass electron accelerator consisting of two superconducting linacs joined by independent magnetic transport arcs. CEBAF also has numerous normal conducting cavities for beam conditioning in the injector and for RF extraction to the experimental halls. The RF systems that presently control these cavities are becoming expensive to maintain, therefore a replacement RF control system is now being developed. For the new RF system, cavity field control is maintained digitally using an FPGA which contains the feedback algorithm. The system incorporates digital down conversion, using quadrature under-sampling at an IF frequency of 70 MHz. The VXI bus-crate was chosen as the operating platform because of its excellent RFI/EMI properties and its compatibility with the EPICS control system. The normal conducting cavities operate at both the 1497 MHz accelerating frequency and the sub-harmonic frequency of 499 MHz. To accommodate this, the ne w design will use different receiver-transmitter daughter cards for each frequency. This paper discusses the development of the new RF system and reports on initial results.
Water clusters in nonpolar cavities
Vaitheeswaran, Subramanian; Yin, Hao; Rasaiah, Jayendran C.; Hummer, Gerhard
2004-01-01
We explore the structure and thermodynamics of water clusters confined in nonpolar cavities. By calculating the grand-canonical partition function term by term, we show that small nonpolar cavities can be filled at equilibrium with highly structured water clusters. The structural and thermodynamic properties of these encapsulated water clusters are similar to those observed experimentally in the gas phase. Water filling is highly sensitive to the size of the cavity and the strength of the int...
Vowel harmonic amplitude differences in persons with vocal nodules.
Radish Kumar, B; Bhat, Jayashree S; Mukhi, Payal
2011-09-01
Spectrum is a fast Fourier transform-generated power spectrum extracted from the speech sample. It is reported to provide a quantitative acoustic index of the degree of glottal abduction and adduction in voices perceived to be breathy or pressed. In the present study, it was hypothesized that there would be abnormal reduction of higher harmonic amplitudes relative to the amplitude of the first harmonics in the subjects with vocal nodules and hence the present study was carried out. One hundred twenty participants were divided into clinical group and control group. They were instructed to phonate /a/ at their most comfortable pitch and loudness. Fourier transformation of the recorded acoustic signal was first performed to create a spectrum. Amplitudes were measured for the first and second harmonics (H1 and H2) as well as the harmonics at the first, second, and third formants (A1, A2, and A3) using the Computerized Speech Science Lab (Kay Pentax, Lincoln, NJ). There was a significant difference between the means of two groups for all the parameters, such as H1-H2, H1-A1, H1-A2, and H1-A3 at PVoice Foundation. Published by Mosby, Inc. All rights reserved.
Cluster size dependence of high-order harmonic generation
Tao, Y; Bastiaens, H M J; van der Slot, P J M; Biedron, S G; Milton, S V; Boller, K -J
2016-01-01
We investigate high-order harmonic generation (HHG) from noble gas clusters in a supersonic gas jet. To identify the contribution of harmonic generation from clusters versus that from gas monomers, we measure the high-order harmonic output over a broad range of the total atomic number density in the jet (from 3x10^{16} cm^{-3} to 3x10^{18} cm^{-3}) at two different reservoir temperatures (303 K and 363 K). For the first time in the evaluation of the harmonic yield in such measurements, the variation of the liquid mass fraction, g, versus pressure and temperature is taken into consideration, which we determine, reliably and consistently, to be below 20% within our range of experimental parameters. Based on measurements with a thin jet where significant variations in reabsorption and the phase matching conditions can be neglected, we conclude that atoms in the form of small clusters (average cluster size < 1000 atoms) provide the same higher-order nonlinear response as single-atoms. This implies that HHG in ...
Dewetting Transitions in Protein Cavities *
Young, Tom; Hua, Lan; Huang, Xuhui; Abel, Robert; Friesner, Richard; Berne, B. J.
2010-01-01
In a previous analysis of the solvation of protein active sites, a drying transition was observed in the narrow hydrophobic binding cavity of Cox-2. With the use of a crude metric that often seems able to discriminate those protein cavities that dry from those that do not, we made an extensive search of the pdb, and identified five other proteins that, in molecular dynamics simulations, undergo drying transitions in their active sites. Because such cavities need not desolvate before binding hydrophobic ligands they often exhibit very large binding affinities. This paper gives evidence that drying in protein cavities is not unique to Cox-2. PMID:20225258
Cavity coalescence in superplastic deformation
Energy Technology Data Exchange (ETDEWEB)
Stowell, M.J.; Livesey, D.W.; Ridley, N.
1984-01-01
An analysis of the probability distribution function of particles randomly dispersed in a solid has been applied to cavitation during superplastic deformation and a method of predicting cavity coalescence developed. Cavity size distribution data were obtained from two microduplex nickel-silver alloys deformed superplastically to various extents at elevated temperature, and compared to theoretical predictions. Excellent agreement occurred for small void sizes but the model underestimated the number of voids in the largest size groups. It is argued that the discrepancy results from a combination of effects due to non-random cavity distributions and to enhanced growth rates and incomplete spheroidization of the largest cavities.
Experimental investigation on the pressure characteristics of cavity closure region
Wang, Yadong; Yuan, Xulong; Zhang, Yuwen
2012-12-01
The most complicated component in cavitating flow and pressure distribution is the flow in the cavity closure line. The cavitating flow and pressure distribution provide critical aspects of flow field details in the region. The integral of pressure results of the hydrodynamic forces, indicate domination in the design of a supercavitating vehicle. An experiment was performed in a water tunnel to investigate the pressure characteristics of the cavity closure region. Ventilation methods were employed to generate artificial cavity, and the ventilation rate was adjusted accordingly to obtain the desired cavity length. An array of pressure transducers was laid down the cavity closure line to capture pressure distribution in this region. The experimental results show that there is a pressure peak in the cavity closure region, and the rise rate of pressure in space tends to be higher in the upwind side when the flow is non-axisymmetric. The transient pressure variations during the cavity formation procedure were also present. The method of measurement in this paper can be referenced by engineers. The result helps to study the flow pattern of cavity closure region, and it can also be used to analyze the formation of supercavitating vehicle hydrodynamics.
Wall compliance and violin cavity modes.
Bissinger, George
2003-03-01
Violin corpus wall compliance, which has a substantial effect on cavity mode frequencies, was added to Shaw's two-degree-of-freedom (2DOF) network model for A0 ("main air") and A1 (lowest length mode included in "main wood") cavity modes. The 2DOF model predicts a V(-0.25) volume dependence for A0 for rigid violin-shaped cavities, to which a semiempirical compliance correction term, V(-x(c)) (optimization parameter x(c)) consistent with cavity acoustical compliance and violin-based scaling was added. Optimizing x(c) over A0 and A1 frequencies measured for a Hutchins-Schelleng violin octet yielded x(c) approximately 0.08. This markedly improved A0 and A1 frequency predictions to within approximately +/- 10% of experiment over a range of about 4.5:1 in length, 10:1 in f-hole area, 3:1 in top plate thickness, and 128:1 in volume. Compliance is a plausible explanation for A1 falling close to the "main wood" resonance, not increasingly higher for the larger instruments, which were scaled successively shorter compared to the violin for ergonomic and practical reasons. Similarly incorporating compliance for A2 and A4 (lowest lower-/upper-bout modes, respectively) improves frequency predictions within +/-20% over the octet.
Electron motion enhanced high harmonic generation in xenon clusters
Li, Na; Bai, Ya; Peng, Peng; Li, Ruxin; Xu, Zhizhan
2016-01-01
Atomic clusters presents an isolated system that models the bulk materials whose mechanism of HHG remains uncertain, and a promising medium to produce HHG beyond the limited conversion efficiency for gaseous atoms. Here we reveal that the oscillation of collective electron motion within clusters develops after the interaction of intense laser fields, and it significantly enhances the harmonic dipole and increases the quantum phase of the harmonics. Experimentally, the phase matching conditions of HHG from nanometer xenon clusters and atoms are distinguished, which confirms the enhanced internal field that was proposed theoretically a decade ago. The separation of HHG from atoms and clusters allows the determination of the amplitude of the HHG for clusters to be 5 orders higher, corresponding to 4 times higher conversion efficiency for atomic response. The finding provides an insight on the HHG mechanism of bulk materials and a means by which an efficient coherent X-ray source can be developed.
Boonengering, J.M.; Gloster, L.A.W.; Veer, van der W.E.; McKinnie, I.T.; King, T.A.; Hogervorst, W.
1995-01-01
A new coupled-cavity design for single-longitudinal-mode operation of an optical parametric oscillator (OPO) is presented. The OPO is based on a beta-BaB2O4 crystal and is pumped by the third harmonic of a Nd:YAG laser. With this design, we achieved single-longitudinal-mode operation of the OPO with
Dorney, Kevin M.; Ellis, Jennifer L.; Hernández-García, Carlos; Hickstein, Daniel D.; Mancuso, Christopher A.; Brooks, Nathan; Fan, Tingting; Fan, Guangyu; Zusin, Dmitriy; Gentry, Christian; Grychtol, Patrik; Kapteyn, Henry C.; Murnane, Margaret M.
2017-08-01
High harmonics driven by two-color counterrotating circularly polarized laser fields are a unique source of bright, circularly polarized, extreme ultraviolet, and soft x-ray beams, where the individual harmonics themselves are completely circularly polarized. Here, we demonstrate the ability to preferentially select either the right or left circularly polarized harmonics simply by adjusting the relative intensity ratio of the bichromatic circularly polarized driving laser field. In the frequency domain, this significantly enhances the harmonic orders that rotate in the same direction as the higher-intensity driving laser. In the time domain, this helicity-dependent enhancement corresponds to control over the polarization of the resulting attosecond waveforms. This helicity control enables the generation of circularly polarized high harmonics with a user-defined polarization of the underlying attosecond bursts. In the future, this technique should allow for the production of bright highly elliptical harmonic supercontinua as well as the generation of isolated elliptically polarized attosecond pulses.
DEFF Research Database (Denmark)
2016-01-01
The present invention provides a vertical cavity laser comprising a grating layer comprising an in-plane grating, the grating layer having a first side and having a second side opposite the first side and comprising a contiguous core grating region having a grating structure, wherein an index......, an index of refraction of the second low-index layer or air being less than 2; and a thickness of the cap layer and a thickness of the grating layer, and a pitch and a duty cycle of the grating structure are selected to obtain a resonance having a free-space resonance wavelength in the interval 300 nm to 3...... microns, the cap layer comprises an active region configured to generate or absorb photons at the free-space resonance wavelength by stimulated emission or absorption when a sufficient forward or reverse bias voltage is applied across the active region, a thickness of the first low-index layer is less...
Skidmore, Jonathan; Doyle, Hugo; Tully, Brett; Betney, Matthew; Foster, Peta; Ringrose, Tim; Ramasamy, Rohan; Parkin, James; Edwards, Tom; Hawker, Nicholas
2016-10-01
Results from the experimental investigation of cavity collapse driven by a strong planar shock (>6km/s) are presented. Data from high speed framing cameras, laser backlit diagnostics and time-resolved pyromety are used to validate the results of hydrodynamic front-tracking simulations. As a code validation exercise, a 2-stage light gas gun was used to accelerate a 1g Polycarbonate projectile to velocities exceeding 6km/s; impact with a PMMA target containing a gas filled void results in the formation of a strong shockwave with pressures exceeding 1Mbar. The subsequent phenomena associated with the collapse of the void and excitation of the inert gas fill are recorded and compared to simulated data. Variation of the mass density and atomic number of the gas fill is used to alter the plasma parameters furthering the extent of the code validation.
Use of extended laser plasma for generation of high-order harmonics of picosecond duration
Energy Technology Data Exchange (ETDEWEB)
Ganeev, R A; Boltaev, G S; Reyimbaev, Sh; Sherniyozov, Kh; Usmanov, T [Institute of Ion-Plasma and Laser Technologies, Uzbekistan Academy of Sciences, Akademgorodok, Tashkent 100125 (Uzbekistan)
2015-07-31
We report the results of experimental investigations on the generation of picosecond radiation harmonics in extended laser plasma produced on the surface of different metal targets. The effect of plasma length, heating pulse duration and delay between the heating and transformable pulses on the efficiency of conversion to higher harmonics is studied. The λ = 1064 nm radiation conversion to a short-wavelength (down to 50 nm, 21st harmonic) range in extended plasma of several metals is demonstrated. (interaction of laser radiation with matter. laser plasma)
Single Cavity Trapped Vortex Combustor Dynamics – Part-2: Simulations
Directory of Open Access Journals (Sweden)
Atul Singhal
2011-03-01
Full Text Available The first part described a versatile TVC test rig capable of a continuously variable length-to-depth ratio (L/D of the cavity and optical access through quartz plates provided on three sides for visualization. Flame stabilization in the single cavity TVC was successfully achieved with methane as fuel and the range of flow conditions for stable operation were identified. From these, a few cases were selected for detailed experimentation, the results of which were presented in part-1. The results indicated that reducing L/D ratio and increasing cavity-air velocity favour stable combustion. In the present paper, numerical simulations are performed to ascertain reasons for some of the trends. The predicted temperatures at the exit showed reasonably good agreement with measured values. The experiments are also performed for different flow conditions to ascertain stability limits of the combustor. Insight from these set of experiments along with simulations has highlighted the importance of air and fuel injection strategies in the cavity. It was observed in the experiments that for certain cases involving moderate cavity-air velocity, the flame tend to blowout whereas at higher and lower cavity-air velocities, the flame was observed to be stable. This observation could be explained based on understanding obtained from simulations. From a mixing and combustion efficiency standpoint, it is desirable to have a cavity vortex that is anti-clockwise. However, natural tendency for flow over a cavity is to form a vortex that is clockwise. The tendency to blowout at higher inlet flow velocities is thought to be because of these two opposing effects. This basic understating of cavity flow dynamics can be used for further design improvements in future to improve flame stability at higher inlet flow velocities.
The Harmonic Organization of Auditory Cortex
Directory of Open Access Journals (Sweden)
Xiaoqin eWang
2013-12-01
Full Text Available A fundamental structure of sounds encountered in the natural environment is the harmonicity. Harmonicity is an essential component of music found in all cultures. It is also a unique feature of vocal communication sounds such as human speech and animal vocalizations. Harmonics in sounds are produced by a variety of acoustic generators and reflectors in the natural environment, including vocal apparatuses of humans and animal species as well as music instruments of many types. We live in an acoustic world full of harmonicity. Given the widespread existence of the harmonicity in many aspects of the hearing environment, it is natural to expect that it be reflected in the evolution and development of the auditory systems of both humans and animals, in particular the auditory cortex. Recent neuroimaging and neurophysiology experiments have identified regions of non-primary auditory cortex in humans and non-human primates that have selective responses to harmonic pitches. Accumulating evidence has also shown that neurons in many regions of the auditory cortex exhibit characteristic responses to harmonically related frequencies beyond the range of pitch. Together, these findings suggest that a fundamental organizational principle of auditory cortex is based on the harmonicity. Such an organization likely plays an important role in music processing by the brain. It may also form the basis of the preference for particular classes of music and voice sounds.
Practical Tools to Foster Harmonic Understanding
Johnson, Erik
2013-01-01
Among the elements required to develop a comprehensive understanding of music is students' ability to perceive, recognize, and label the harmonies they hear. Harmonic dictation is among the strategies that teachers have traditionally chosen to help students develop harmonic awareness. However, the highly idiosyncratic ways that students approach…
Harmonic manifolds with minimal horospheres are flat
Indian Academy of Sciences (India)
MS received 28 May 2013; revised 12 November 2013 ... The known examples of harmonic manifolds include flat ... periodic functions. Finally, using the characteristic property of an almost periodic function we prove that M is Ricci flat. In view of this, it is natural to ask: Can one affirm that harmonic manifolds with mini-.
Harmonic dynamical behaviour of thallous halides
Indian Academy of Sciences (India)
Harmonic dynamical behaviour of thallous halides (TlCl and TlBr) have been studied using the ... that the incorporation of van der Waals interactions is essential for the complete harmonic dynamical behaviour of .... long-range coupling coefficients to the long-wavelength limit q → 0, the expression for zone centre optical ...
Effective harmonic oscillator description of anharmonic molecular ...
Indian Academy of Sciences (India)
... a harmonic oscillator eigenfunction with the centroid and width parameter as variational paraeters. It is found that the effective harmonic oscillator approximation provides a description of the anharmonic eigenstates very similar to the vibrational self consistent field results. Coriolis coupling is also included in these studies.
Sunspots and Their Simple Harmonic Motion
Ribeiro, C. I.
2013-01-01
In this paper an example of a simple harmonic motion, the apparent motion of sunspots due to the Sun's rotation, is described, which can be used to teach this subject to high-school students. Using real images of the Sun, students can calculate the star's rotation period with the simple harmonic motion mathematical expression.
determination of determination of total harmonic distortion
African Journals Online (AJOL)
eobe
Harmonic Distortion (THD) of the Distribution lines in the 33kV distri. Harmonic Distortion (THD) of the Distribution lines in the 33kV distribution network of Island Business District, bution network of Island Business District,. Eko Electricity Distribution Plc, taken. Eko Electricity Distribution Plc, taken as a case study using a set ...
Achieving sustainable development through tax harmonization ...
African Journals Online (AJOL)
Using Nigeria as a case study, this article examines the efficacy of tax harmonization as an option for the achievement of two objectives: the integration of a developing country with other economies, and its sustainable development. It highlights the nexus between tax harmonization – a tax policy option – and sustainable ...
Harmonic Phase Response of Nonlinear Radar Targets
2015-10-01
ARL-TR-7513 ● OCT 2015 US Army Research Laboratory Harmonic Phase Response of Nonlinear Radar Targets by Sean F McGowan, Dr...Laboratory Harmonic Phase Response of Nonlinear Radar Targets by Sean F McGowan and Kelly D Sherbondy Sensors and Electron Devices Directorate...
The harmonic organization of auditory cortex
Wang, Xiaoqin
2013-01-01
A fundamental structure of sounds encountered in the natural environment is the harmonicity. Harmonicity is an essential component of music found in all cultures. It is also a unique feature of vocal communication sounds such as human speech and animal vocalizations. Harmonics in sounds are produced by a variety of acoustic generators and reflectors in the natural environment, including vocal apparatuses of humans and animal species as well as music instruments of many types. We live in an acoustic world full of harmonicity. Given the widespread existence of the harmonicity in many aspects of the hearing environment, it is natural to expect that it be reflected in the evolution and development of the auditory systems of both humans and animals, in particular the auditory cortex. Recent neuroimaging and neurophysiology experiments have identified regions of non-primary auditory cortex in humans and non-human primates that have selective responses to harmonic pitches. Accumulating evidence has also shown that neurons in many regions of the auditory cortex exhibit characteristic responses to harmonically related frequencies beyond the range of pitch. Together, these findings suggest that a fundamental organizational principle of auditory cortex is based on the harmonicity. Such an organization likely plays an important role in music processing by the brain. It may also form the basis of the preference for particular classes of music and voice sounds. PMID:24381544
Uniformly locally univalent harmonic map- pings
Indian Academy of Sciences (India)
63
Uniformly locally univalent harmonic map- pings. Saminathan Ponnusamy, Jinjing Qiao. ∗ and Xiantao Wang. Abstract. The primary aim of this paper is to characterize the uniformly locally univalent harmonic mappings in the unit disk. Then, we obtain sharp distortion, growth and covering theorems for one parameter fam-.
Hyperspherical Harmonics and Their Physical Applications
DEFF Research Database (Denmark)
Avery, James Emil; Avery, John Scales
Hyperspherical harmonics are extremely useful in nuclear physics and reactive scattering theory. However, their use has been confined to specialists with very strong backgrounds in mathematics. This book aims to change the theory of hyperspherical harmonics from an esoteric field, mastered...
Pairwise harmonics for shape analysis
Zheng, Youyi
2013-07-01
This paper introduces a simple yet effective shape analysis mechanism for geometry processing. Unlike traditional shape analysis techniques which compute descriptors per surface point up to certain neighborhoods, we introduce a shape analysis framework in which the descriptors are based on pairs of surface points. Such a pairwise analysis approach leads to a new class of shape descriptors that are more global, discriminative, and can effectively capture the variations in the underlying geometry. Specifically, we introduce new shape descriptors based on the isocurves of harmonic functions whose global maximum and minimum occur at the point pair. We show that these shape descriptors can infer shape structures and consistently lead to simpler and more efficient algorithms than the state-of-the-art methods for three applications: intrinsic reflectional symmetry axis computation, matching shape extremities, and simultaneous surface segmentation and skeletonization. © 2012 IEEE.
Harmonic Interaction Analysis in Grid Connected Converter using Harmonic State Space (HSS) Modeling
DEFF Research Database (Denmark)
Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth
2015-01-01
An increasing number of power electronics based Distributed Generation (DG) systems and loads generate coupled harmonic as well as non-characteristic harmonic with each other. Several methods like impedance based analysis, which is derived from conventional small signal- and average...... during the modeling process. This paper investigates grid connected converter by means of Harmonic State Space (HSS) small signal model, which is modeled from Linear Time varying Periodically (LTP) system. Further, a grid connected converter harmonic matrix is investigated to analyze the harmonic...
Frequency Tuning for a DQW Crab Cavity
Verdú-Andrés, Silvia; Ben-Zvi, Ilan; Calaga, Rama; Capatina, Ofelia; Leuxe, Raphael; Skaritka, John; Wu, Qiong; Xiao, Binping; Zanoni, Carlo
2016-01-01
The nominal operating frequency for the HL-LHC crab cavities is 400.79 MHz within a bandwidth of ±60kHz. Attaining the required cavity tune implies a good understanding of all the processes that influence the cavity frequency from the moment when the cavity parts are being fabricated until the cavity is installed and under operation. Different tuning options will be available for the DQW crab cavity of LHC. This paper details the different steps in the cavity fabrication and preparation that may introduce a shift in the cavity frequency and introduces the different tuning methods foreseen to bring the cavity frequency to meet the specifications.
Survey of Saturn electrostatic cyclotron harmonic wave intensity
Menietti, J. D.; Averkamp, T. F.; Kurth, W. S.; Ye, S.-Y.; Gurnett, D. A.; Cecconi, B.
2017-08-01
We conduct a survey of electrostatic electron cyclotron harmonic (ECH) emissions observed at Saturn by the radio and plasma wave science investigation on board the Cassini spacecraft. These emissions are known to be effective at interacting with electrons in the terrestrial inner magnetosphere, producing electron scattering into the loss cone and acceleration (cf. Horne and Thorne, 2000; Thorne et al., 2010). At Saturn ECH emission occurs with high probability and at strong intensity near the magnetic equator, outside the Enceladus torus in the range 5 < L < 10. Inside the inner boundary of the torus, ECH emissions are also observed near the equator and at higher latitude. Intensity levels of ECH emission are comparable to those observed at Earth, higher than Saturn chorus and Z-mode emission, and are likely to scatter electrons into the loss cone as at Earth. ECH waves are particularly intense and extend to higher harmonics within some plasma injection regions. We present results for a survey of over 8 years of Saturn data for fundamental and up to three harmonics of fce, the electron cyclotron frequency.
Harmonics Monitoring Survey on LED Lamps
Directory of Open Access Journals (Sweden)
Abdelrahman Ahmed Akila
2017-03-01
Full Text Available Light Emitting Diode (LED lamps are being increasingly used in many applications. These LED lamps operate using a driver, which is a switching device. Hence, LED lamps will be a source of harmonics in the power system. These harmonics if not well treated, may cause severe performance and operational problems. In this paper, harmonics (amplitude and phase angles generated by both LED lamps and conventional fluorescent lamps will be studied practically. Then they will be analyzed and evaluated. Compared to each other harmonics generated by both LED and conventional florescent lamps, self mitigation may occur based on the phase angle of these harmonics. All data will be measured using power analyzer and will be done on a sample of actual lamps.
High orbital angular momentum harmonic generation
Vieira, J; Alves, E P; Fonseca, R A; Mendonça, J T; Bingham, R; Norreys, P; Silva, L O
2016-01-01
We identify and explore a high orbital angular momentum (OAM) harmonics generation and amplification mechanism that manipulates the OAM independently of any other laser property, by preserving the initial laser wavelength, through stimulated Raman backscattering in a plasma. The high OAM harmonics spectra can extend at least up to the limiting value imposed by the paraxial approximation. We show with theory and particle-in-cell simulations that the orders of the OAM harmonics can be tuned according to a selection rule that depends on the initial OAM of the interacting waves. We illustrate the high OAM harmonics generation in a plasma using several examples including the generation of prime OAM harmonics. The process can also be realised in any nonlinear optical Kerr media supporting three-wave interactions.
Harmonic Generation by Microwave-frequency Microplasma
Parsons, Stephen; Hoskinson, Alan; Hopwood, Jeffrey
2013-09-01
A microplasma may operate as a nonlinear circuit element and generate power at the harmonics of the drive frequency. As an example, microplasma is sustained using 1 W of power at 1.3 GHz in a small discharge gap formed in a split-ring resonator. A probe extends into the microplasma and extracts the 3rd harmonic power through a tuned resonator at 3.9 GHz. The experimental data show that this non-optimized system produces a +38 dB increase in 3rd harmonic power in the presence of a microplasma. Two origins of nonlinearity are described: the harmonic conduction current due to electron collection by microelectrodes, and the harmonic displacement current due to the voltage-dependent sheath capacitance. PIC-MC simulations suggest that the microplasma nonlinearity may also be exploited at frequencies of 100 GHz. Support was provided by the DARPA Microscale Plasma Devices program under award FA9550-12-1-0006.
Second-harmonic generation microscopy of collagen-bearing structures
Vanbel, Maarten K.; Callewaert, Tom; Verbiest, Thierry
2014-05-01
Nonlinear optical phenomena cover a broad research area. The emphasis is mostly on the generation of higher harmonics to be used in laser designs or on the characterization capabilities of nonlinear optics. The latter ability of nonlinear optics is important when combined with a microscope to detect simultaneously multiphoton fluorescence and second-harmonic generation. Submicron size features can then be investigated separately and information on their structure can be revealed by second-harmonic generation. For example, the point group symmetry can be determined in situ and in vivo in complex media. Moreover, nonlinear optical microscopy has several additional advantages: the generation and detection of nonlinear signals is intrinsically confocal and degradation, if present, only occurs at a localized places in the structure. In biological structures, multiphoton fluorescence and second-harmonic generation do not necessarily occur in the same type of the structure. This can be exploited to visualize different structures in one sample by simultaneous detection of two-photon fluorescence and second-harmonic generation. Also, the incident beam can be tuned to fit in the biological window of biological structures, which gives second-harmonic generation microscopy a significant advantage over linear microscopy due to absorbance issues in the visible wavelength range. We exploit these advantages to characterize collagen-bearing biological structures. Collagen is the dominant structural protein in connective tissue in mammals. Being the most abundant protein in the mammal clade, it is essential for the very existence of it. Collagen is a protein with a very strict quaternary structure. The most simple Ramachandran model states that an amino-acid sequence of Glycine-prolin-hydroxyprolin leads to a right-handed helical structure. The inherent stability is such that a sole helix cannot exist for a prolonged period of time, it will therefore combine with 2 near identical
Heat and mass transfer in porous cavity: Assisting flow
Energy Technology Data Exchange (ETDEWEB)
Badruddin, Irfan Anjum [Dept. of Mechanical Engineering, University of Malaya, Kuala Lumpur, 50603 (Malaysia); Quadir, G. A. [School of Mechatronic Engineering, University Malaysia Perlis, Pauh Putra, 02600 Arau, Perlis (Malaysia)
2016-06-08
In this paper, investigation of heat and mass transfer in a porous cavity is carried out. The governing partial differential equations are non-dimensionalised and solved using finite element method. The left vertical surface of the cavity is maintained at constant temperature and concentration which are higher than the ambient temperature and concentration applied at right vertical surface. The top and bottom walls of the cavity are adiabatic. Heat transfer is assumed to take place by natural convection and radiation. The investigation is carried out for assisting flow when buoyancy and gravity force act in same direction.
Wakefield calculation for superconducting TM110 cavity without azimuthal symmetry
Energy Technology Data Exchange (ETDEWEB)
Bellantoni, Leo; /Fermilab; Burt, Graeme; /Lancaster U.
2006-08-01
The 3.9GHz TM{sub 110} mode deflecting cavity developed at FNAL has many applications, including use as a longitudinal bunch profile diagnostic, and as a crab cavity candidate for the ILC. These applications involve beams with substantial time structure. For the 13-cell version intended for the bunch profile application, long-range wakes have been evaluated in the frequency domain and short-range wakes have been evaluated in the time domain. Higher-order interactions of the main field in the cavity with the beam have also been parameterized. Pedagogic derivations are included as appendices.
Metzger, Bernd; Gui, Lili; Fuchs, Jaco; Floess, Dominik; Hentschel, Mario; Giessen, Harald
2015-06-10
We perform second harmonic spectroscopy of aluminum nanoantenna arrays that exhibit plasmonic resonances at the second harmonic wavelength between 450 and 570 nm by focusing sub-30 fs laser pulses tunable from 900 to 1140 nm onto the nanoantenna arrays. We find that a plasmonic resonance at the second harmonic wavelength boosts the overall nonlinear process by more than an order of magnitude. In particular, in the measurement the resonant second harmonic polarization component is a factor of about 70 stronger when compared to the perpendicular off-resonant second harmonic polarization. Furthermore, the maximum of the second harmonic conversion efficiency is found to be slightly blue-shifted with respect to the peak of the linear optical far-field spectrum. This fact can be understood from a simple model that accounts for the almost off-resonant absorption at the fundamental wavelength and the resonant emission process at the second harmonic.
High order harmonic generation in rare gases
Energy Technology Data Exchange (ETDEWEB)
Budil, Kimberly Susan [Univ. of California, Davis, CA (United States)
1994-05-01
The process of high order harmonic generation in atomic gases has shown great promise as a method of generating extremely short wavelength radiation, extending far into the extreme ultraviolet (XUV). The process is conceptually simple. A very intense laser pulse (I ~10^{13}-10^{14} W/cm^{2}) is focused into a dense (~10^{17} particles/cm^{3}) atomic medium, causing the atoms to become polarized. These atomic dipoles are then coherently driven by the laser field and begin to radiate at odd harmonics of the laser field. This dissertation is a study of both the physical mechanism of harmonic generation as well as its development as a source of coherent XUV radiation. Recently, a semiclassical theory has been proposed which provides a simple, intuitive description of harmonic generation. In this picture the process is treated in two steps. The atom ionizes via tunneling after which its classical motion in the laser field is studied. Electron trajectories which return to the vicinity of the nucleus may recombine and emit a harmonic photon, while those which do not return will ionize. An experiment was performed to test the validity of this model wherein the trajectory of the electron as it orbits the nucleus or ion core is perturbed by driving the process with elliptically, rather than linearly, polarized laser radiation. The semiclassical theory predicts a rapid turn-off of harmonic production as the ellipticity of the driving field is increased. This decrease in harmonic production is observed experimentally and a simple quantum mechanical theory is used to model the data. The second major focus of this work was on development of the harmonic "source". A series of experiments were performed examining the spatial profiles of the harmonics. The quality of the spatial profile is crucial if the harmonics are to be used as the source for experiments, particularly if they must be refocused.
Yermachenko, VM; Karle, RA; Petrovskiy, VN; Protsenko, ED
The influence of intracavity second harmonic generation on the mode competition in a double-mode diode-pumped Nd:YAG laser is studied theoretically and experimentally. Various configurations of the optical cavity with II-type phase-matching frequency-doubling crystals are considered. The conditions
Structural relations of harmonic sums and Mellin transforms up to weight w=5
Energy Technology Data Exchange (ETDEWEB)
Bluemlein, Johannes
2009-01-15
We derive the structural relations between the Mellin transforms of weighted Nielsen integrals emerging in the calculation of massless or massive single-scale quantities in QED and QCD, such as anomalous dimensions and Wilson coefficients, and other hard scattering cross sections depending on a single scale. The set of all multiple harmonic sums up to weight five cover the sums needed in the calculation of the 3-loop anomalous dimensions. The relations extend the set resulting from the quasi-shuffle product between harmonic sums studied earlier. Unlike the shuffle relations, they depend on the value of the quantities considered. Up to weight w=5, 242 nested harmonic sums contribute. In the present physical applications it is sufficient to consider the sub-set of harmonic sums not containing an index i=-1, which consists out of 69 sums. The algebraic relations reduce this set to 30 sums. Due to the structural relations a final reduction of the number of harmonic sums to 15 basic functions is obtained. These functions can be represented in terms of factorial series, supplemented by harmonic sums which are algebraically reducible. Complete analytic representations are given for these 15 meromorphic functions in the complex plane deriving their asymptotic- and recursion relations. A general outline is presented on the way nested harmonic sums and multiple zeta values emerge in higher order calculations of zero- and single scale quantities. (orig.)
Electrodynamical Light Trapping Using Whispering-Gallery Resonances in Hyperbolic Cavities
Directory of Open Access Journals (Sweden)
Chihhui Wu
2014-04-01
Full Text Available We theoretically study spherical cavities composed of hyperbolic metamaterials with indefinite permittivity tensors. Such cavities are capable of electrodynamically confining fields with deep subwavelength cavity sizes. The supported resonant modes are analogous to the whispering-gallery modes found in dielectric microcavities with much larger physical sizes. Because of the nature of electrodynamical confinement, these hyperbolic metamaterial cavities exhibit quality factors higher than predicted in the electrostatic limit. In addition, confining electromagnetic fields into the small cavities results in an extremely high photonic local density of states.
HOM Couplers for CERN SPL Cavities
Papke, Kai; Van Rienen, U
2013-01-01
Higher-Order-Modes (HOMs) may affect beam stability and refrigeration requirements of superconducting proton linacs such as the SPL, which is studied at CERN as the driver for future neutrino facilities. In order to limit beam-induced HOM effects, CERN considers the use of HOM couplers on the cut-off tubes of the 5-cell superconducting cavities. These couplers consist of resonant antennas shaped as loops or probes, which are designed to couple to modes of a specific frequency range. In this paper the design process is presented and a comparison is made between various design options for the medium and high-beta SPL cavities, both operating at 704.4 MHz. The RF characteristics and thermal behaviour of the various designs are discussed.
Field stabilization of Alvarez-type cavities
Directory of Open Access Journals (Sweden)
X. Du
2017-03-01
Full Text Available Alvarez-type cavities are commonly used to reliably accelerate high quality hadron beams. Optimization of their longitudinal field homogeneity is usually accomplished by post-couplers, i.e., additional rods being integrated into the cavity. This paper instead proposes to use the stems that keep the drift tubes for that purpose. As their individual azimuthal orientations do not change the cavity’s undisturbed operational mode, they comprise a set of free parameters that can be used to modify higher mode field patterns. The latter have significant impact on the robustness of the operational mode with respect to eventual perturbations. Several optimized stem configurations are presented and benchmarked against each other. The path to obtain these configurations is paved analytically and worked out in detail through simulations. It is shown also by measurements that the method provides for flat field distributions and very low field tilt sensitivities without insertion of post-couplers.
Tailored semiconductors for high-harmonic optoelectronics.
Sivis, Murat; Taucer, Marco; Vampa, Giulio; Johnston, Kyle; Staudte, André; Naumov, Andrei Yu; Villeneuve, D M; Ropers, Claus; Corkum, P B
2017-07-21
The advent of high-harmonic generation in gases 30 years ago set the foundation for attosecond science and facilitated ultrafast spectroscopy in atoms, molecules, and solids. We explore high-harmonic generation in the solid state by means of nanostructured and ion-implanted semiconductors. We use wavelength-selective microscopic imaging to map enhanced harmonic emission and show that the generation medium and the driving field can be locally tailored in solids by modifying the chemical composition and morphology. This enables the control of high-harmonic technology within precisely engineered solid targets. We demonstrate customized high-harmonic wave fields with wavelengths down to 225 nanometers (ninth-harmonic order of 2-micrometer laser pulses) and present an integrated Fresnel zone plate target in silicon, which leads to diffraction-limited self-focusing of the generated harmonics down to 1-micrometer spot sizes. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.
Nonlocal Intracranial Cavity Extraction
Manjón, José V.; Eskildsen, Simon F.; Coupé, Pierrick; Romero, José E.; Collins, D. Louis; Robles, Montserrat
2014-01-01
Automatic and accurate methods to estimate normalized regional brain volumes from MRI data are valuable tools which may help to obtain an objective diagnosis and followup of many neurological diseases. To estimate such regional brain volumes, the intracranial cavity volume (ICV) is often used for normalization. However, the high variability of brain shape and size due to normal intersubject variability, normal changes occurring over the lifespan, and abnormal changes due to disease makes the ICV estimation problem challenging. In this paper, we present a new approach to perform ICV extraction based on the use of a library of prelabeled brain images to capture the large variability of brain shapes. To this end, an improved nonlocal label fusion scheme based on BEaST technique is proposed to increase the accuracy of the ICV estimation. The proposed method is compared with recent state-of-the-art methods and the results demonstrate an improved performance both in terms of accuracy and reproducibility while maintaining a reduced computational burden. PMID:25328511
Frequency-feedback cavity enhanced spectrometer
Hovde, David Christian; Gomez, Anthony
2015-08-18
A spectrometer comprising an optical cavity, a light source capable of producing light at one or more wavelengths transmitted by the cavity and with the light directed at the cavity, a detector and optics positioned to collect light transmitted by the cavity, feedback electronics causing oscillation of amplitude of the optical signal on the detector at a frequency that depends on cavity losses, and a sensor measuring the oscillation frequency to determine the cavity losses.
Third-order-harmonic generation in coherently spinning molecules
Prost, E.; Zhang, H.; Hertz, E.; Billard, F.; Lavorel, B.; Bejot, P.; Zyss, Joseph; Averbukh, Ilya Sh.; Faucher, O.
2017-10-01
The rotational Doppler effect occurs when circularly polarized light interacts with a rotating anisotropic material. It is manifested by the appearance of a spectral shift ensuing from the transfer of angular momentum and energy between radiation and matter. Recently, we reported terahertz-range rotational Doppler shifts produced in third-order nonlinear optical conversion [O. Faucher et al., Phys. Rev. A 94, 051402(R) (2016), 10.1103/PhysRevA.94.051402]. The experiment was performed in an ensemble of coherently spinning molecules prepared by a short laser pulse exhibiting a twisted linear polarization. The present work provides an extensive analysis of the rotational Doppler effect in third-order-harmonic generation from spinning linear molecules. The underlying physics is investigated both experimentally and theoretically. The implication of the rotational Doppler effect in higher-order processes like high-order-harmonic generation is discussed.
Harmonic Aspects of Offshore Wind Farms
DEFF Research Database (Denmark)
Kocewiak, Lukasz Hubert; Bak, Claus Leth; Hjerrild, Jesper
2010-01-01
This paper presents the aim, the work and the findings of a PhD project entitled "Harmonics in Large Offshore Wind Farms". It focuses on the importance of harmonic analysis in order to obtain a better performance of future wind farms. The topic is investigated by the PhD project at Aalborg...... University (AAU) and DONG Energy. The objective of the project is to improve and understand the nature of harmonic emission and propagation in wind farms (WFs), based on available information, measurement data and simulation tools. The aim of the project is to obtain validated models and analysis methods...... of offshore wind farm (OWF) systems....
Selective harmonic control for power converters
DEFF Research Database (Denmark)
Zhou, Keliang; Yang, Yongheng; Blaabjerg, Frede
2014-01-01
This paper proposes an Internal Model Principle (IMP) based Selective Harmonic Controller (SHC) for power converters. The proposed SHC offers an optimal control solution for power converters to mitigate power harmonics. It makes a good trade-off among cost, complexity and performance. It has high...... accuracy and fast transient response, and it is cost-effective, easy for real-time implementation, and compatible for design rules-of-thumb. An application on a three-phase PWM converter has confirmed the effectiveness of the proposed control scheme in terms of harmonic mitigation....
Harmonic Distortion in CMOS Current Mirrors
DEFF Research Database (Denmark)
Bruun, Erik
1998-01-01
One of the origins of harmonic distortion in CMOS current mirrors is the inevitable mismatch between the MOS transistors involved. In this paper we examine both single current mirrors and complementary class AB current mirrors and develop an analytical model for the mismatch induced harmonic...... distortion. This analytical model is verified through simulations and is used for a discussion of the impact of mismatch on harmonic distortion properties of CMOS current mirrors. It is found that distortion levels somewhat below 1% can be attained by carefully matching the mirror transistors but ultra low...
Double Harmonic Transmission (D.H.T.
Directory of Open Access Journals (Sweden)
Sava Ianici
2006-10-01
Full Text Available The paper presents the construction and functioning of a new type of harmonic drive named double harmonic transmission (D.H.T.. In the second part of this paper is presented the dynamic analysis of the double harmonic transmission, which is based on the results of the experimental researches on the D.H.T. This study of the stress status and the forces distribution is necessary for to determine the durability on the portant elements of the D.H.T.
Effects of harmonic roving on pitch discrimination
DEFF Research Database (Denmark)
Santurette, Sébastien; de Kérangal, Mathilde le Gal; Joshi, Suyash Narendra
2015-01-01
external noise in the physical stimulus (Lu and Dosher, 2008). The present study used this approach to attempt to quantify the “internal noise” involved in pitch coding of harmonic complex tones by estimating the amount of harmonic roving required to impair pitch discrimination performance. It remains...... performance may help clarify pitch coding mechanisms. As training on frequency discrimination tasks has been found to result in a reduction of internal noise (Jones et al., 2013), it was also investigated whether the effect of harmonic roving varied with musical training...
Simulation of Second Harmonic Ultrasound Fields
DEFF Research Database (Denmark)
Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt
2010-01-01
, and the fundamental pressure is calculated by Field II. The second harmonic pressure in k-space along the propagating direction is calculated as an auto-convolution of the fundamental pressure multiplied by an exponential propagating coefficient. In this case, the second harmonic pressure can be calculated using ASA...... for any plane parallel to the initial plane. In the focal plane (elevation-lateral) at 60 mm from the transducer surface, calculated by ASA, the RMS errors for the fundamental component are 2.66% referred to Field II and 4.28% referred to Abersim. For the second harmonic component, the RMS error is 0...
Some aspects of harmonic time series analysis
2012-01-01
Ph.D. Harmonic time series are often used to describe the periodic nature of a time series, for example the periodic nature of a variable star’s observed light curve. Statistical methods for determining the number of harmonic components to include in harmonic time series are limited. In this thesis a stepwise bootstrap procedure based on a F-type statistic is suggested. The performance of the stepwise procedure is compared to that of Schwartz’s Bayesian Criterion (SBC) and a procedure base...
Shi, Deyong; Song, Wenyan; Wang, Yuhang; Wang, Yanhua
2017-08-01
In this work, the effects of cavity flameholder configurations on flameholding and performances of kerosene fueled scramjet combustor were studied experimentally and numerically. For experiments, a directly connected ground facility was used and clean high enthalpy air, with a total temperature of 800 K and a total pressure of 800 Kpa, was provided by an electricity resistance heater. To investigate the effects of cavity configurations on flameholding capacity and reacting-flow characteristics, three different flameholders, one single cavity flameholder and two tandem cavity flameholders, were used in experiments. For the two combustors with tandem cavity flameholders, the location and configurations of its up-stream cavity were same with the single cavity flameholder, and the length-to-depth ratios for down-stream cavities were 9 and 11 respectively. The experimental results showed that stabilize kerosene combustion were achieved for combustor with tandem cavity flameholders mounted, and none for that with single cavity flameholder. The none-reacting and reacting flows of combustor models with tandem cavity flameholders were compared and studied with numerical and experimental results. The results showed that higher combustion efficiencies and pressure recovery ratios were achieved for the combustor with down-stream cavity length-to-depth ratio of 9.
Transferring a cavity field entangled state in cavity QED
Energy Technology Data Exchange (ETDEWEB)
Ye Liu [Anhui Key Laboratory of Information Material and Devices, School of Physics and Material Science, Anhui University, Hefei 230039 (China); Guo Guangcan [Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026 (China)
2005-08-01
We propose a scheme for transferring an entanglement of zero- and one-photon states from one cavity to another. The scheme, which has 100% success probability, is mainly based on a two-mode cavity dispersively interacting with a three-level atom in the {lambda} configuration and does not involve Bell-state measurement. This scheme can also be used to teleport an unknown atomic state.
X-ray FEL based on harmonics generation and electron beam outcoupling
Energy Technology Data Exchange (ETDEWEB)
Litvinenko, V.N.; Burnham, B. [Duke Univ., Durham, NC (United States)
1995-12-31
Electron beam outcoupling was suggested by N. A. Vinokurov as a method of optics independent outcoupling for high power FELs. The bunching of the electron beam is provided in a master oscillator. The prebunched electron beam then radiates coherently into an additional wiggler called the radiator. The electron beam is turned by an achromatic bend into this wiggler and its radiation propagates with a small angle with respect to the OK-4 optical axis. Thus, the radiation will pass around the mirror of the master oscillator optical cavity and can then be utilized. This scheme is perfectly suited for harmonic generation if the radiator wiggler is tuned on one of the master oscillator wavelength harmonics. This system is reminiscent of a klystron operating on a harmonic of the reference frequency. In this paper we present the theory of this device, its spectral and spatial characteristics of radiation, the optimization of the master oscillator, the achromatic bend and bunching for harmonic generation, and influence of beam parameters (energy spread, emittance, etc.) on generated power. Examples of possible storage ring and linac driven systems are discussed.
Yu, Youbin; Wang, HuaiJun; Zhao, Junwei; Ji, Fengmin; Wang, Yajuan
2016-08-01
Three-colour continuous-variable entanglement produced by single-pass cascaded quasi-phase-matching fourth harmonic generation is investigated. The fourth harmonic can be generated through cascaded double-frequency processes in a quasiperiodic optical superlattice by using quasi-phase-matching technology. The conversion dynamics of the cascaded double-frequency processes is studied using quantum stochastic methods. The nature of the entanglement is discussed by applying a necessary and sufficient criterion for continuous-variable entanglement. Strong three-colour entanglement among the fundamental, second-, and fourth-harmonic beams with a double frequency interval can be produced without an optical oscillator cavity. This is experimentally feasible and has potential applications in quantum communication and computation networks.
Hexagon Wilson Loop OPE and Harmonic Polylogarithms
Papathanasiou, Georgios
2013-01-01
A recent, integrability-based conjecture in the framework of the Wilson loop OPE for N=4 SYM theory, predicts the leading OPE contribution for the hexagon MHV remainder function and NMHV ratio function to all loops, in integral form. We prove that these integrals evaluate to a particular basis of harmonic polylogarithms, at any order in the weak coupling expansion. The proof constitutes an algorithm for the direct computation of the integrals, which we employ in order to obtain the full (N)MHV OPE contribution in question up to 6 loops, and certain parts of it up to 12 loops. We attach computer-readable files with our results, as well as an algorithm implementation which may be readily used to generate higher-loop corrections. The feasibility of obtaining the explicit kinematical dependence of the first term in the OPE in principle at arbitrary loop order, offers promise for the suitability of this approach as a non-perturbative description of Wilson loops/scattering amplitudes.
Nanoantenna harmonic sensor: theoretical analysis of contactless detection of molecules with light.
Farhat, Mohamed; Cheng, Mark M C; Le, Khai Q; Chen, Pai-Yen
2015-10-16
The nonlinear harmonic sensor is a popular wireless sensor and radiofrequency identification (RFID) technique, which allows high-performance sensing in a severe interference/clutter background by transmitting a radio wave and detecting its modulated higher-order harmonics. Here we introduce the concept and design of optical harmonic tags based on nonlinear nanoantennas that can contactlessly detect electronic (e.g. electron affinity) and optical (e.g. relative permittivity) characteristics of molecules. By using a dual-resonance gold-molecule-silver nanodipole antenna within the quantum mechanical realm, the spectral form of the second-harmonic scattering can sensitively reveal the physical properties of molecules, paving a new route towards optical molecular sensors and optical identification (OPID) of biological, genetic, and medical events for the 'Internet of Nano-Things'.
High-order harmonic generation using a high-repetition-rate turnkey laser
Lorek, Eleonora; Heyl, Christoph Michael; Carlström, Stefanos; Paleček, David; Zigmantas, Donatas; Mauritsson, Johan
2014-01-01
We generate high-order harmonics at high pulse repetition rates using a turnkey laser. High-order harmonics at 400 kHz are observed when argon is used as target gas. In neon we achieve generation of photons with energies exceeding 90 eV ($\\sim$13 nm) at 20 kHz. We measure a photon flux of 4.4$\\cdot10^{10}$ photons per second per harmonic in argon at 100 kHz. Many experiments employing high-order harmonics would benefit from higher repetition rates, and the user-friendly operation opens up for applications of coherent extreme ultra-violet pulses in new research areas.
Generation of µW level plateau harmonics at high repetition rate.
Hädrich, S; Krebs, M; Rothhardt, J; Carstens, H; Demmler, S; Limpert, J; Tünnermann, A
2011-09-26
The process of high harmonic generation allows for coherent transfer of infrared laser light to the extreme ultraviolet spectral range opening a variety of applications. The low conversion efficiency of this process calls for optimization or higher repetition rate intense ultrashort pulse lasers. Here we present state-of-the-art fiber laser systems for the generation of high harmonics up to 1 MHz repetition rate. We perform measurements of the average power with a calibrated spectrometer and achieved µW harmonics between 45 nm and 61 nm (H23-H17) at a repetition rate of 50 kHz. Additionally, we show the potential for few-cycle pulses at high average power and repetition rate that may enable water-window harmonics at unprecedented repetition rate. © 2011 Optical Society of America
Localized, Non-Harmonic Active Flap Motions for Low Frequency In-Plane Rotor Noise Reduction
Sim, Ben W.; Potsdam, Mark; Kitaplioglu, Cahit; LeMasurier, Philip; Lorber, Peter; Andrews, Joseph
2012-01-01
A first-of-its-kind demonstration of the use of localized, non-harmonic active flap motions, for suppressing low frequency, in-plane rotor noise, is reported in this paper. Operational feasibility is verified via testing of the full-scale AATD/Sikorsky/UTRC active flap demonstration rotor in the NFAC's 40- by 80-Foot anechoic wind tunnel. Effectiveness of using localized, non-harmonic active flap motions are compared to conventional four-per-rev harmonic flap motions, and also active flap motions derived from closed-loop acoustics implementations. All three approaches resulted in approximately the same noise reductions over an in-plane three-by-three microphone array installed forward and near in-plane of the rotor in the nearfield. It is also reported that using an active flap in this localized, non-harmonic manner, resulted in no more that 2% rotor performance penalty, but had the tendency to incur higher hub vibration levels.
Nanoantenna harmonic sensor: theoretical analysis of contactless detection of molecules with light
Farhat, Mohamed
2015-09-25
The nonlinear harmonic sensor is a popular wireless sensor and radiofrequency identification (RFID) technique, which allows high-performance sensing in a severe interference/clutter background by transmitting a radio wave and detecting its modulated higher-order harmonics. Here we introduce the concept and design of optical harmonic tags based on nonlinear nanoantennas that can contactlessly detect electronic (e.g. electron affinity) and optical (e.g. relative permittivity) characteristics of molecules. By using a dual-resonance gold-molecule–silver nanodipole antenna within the quantum mechanical realm, the spectral form of the second-harmonic scattering can sensitively reveal the physical properties of molecules, paving a new route towards optical molecular sensors and optical identification (OPID) of biological, genetic, and medical events for the \\'Internet of Nano-Things\\'.
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 frequency....... A simple model for the process using semiclassical theory is derived, and quadrature-squeezing spectra of the involved fundamental fields are deduced. The analysis shows that vacuum squeezing reminiscent of subthreshold optical parametric oscillator squeezing is present and, in the ideal case, perfect....... Under slight modifications of the operational conditions, the system is shown to produce efficient bright, squeezed light. Furthermore, we investigate the degree of polarization squeezing and find that three Stokes parameters can be squeezed simultaneously. Finally, we gauge the process for possible...
SRF Cavity Fabrication and Materials
Singer, W
2014-07-17
The technological and metallurgical requirements of material for highgradient superconducting cavities are described. High-purity niobium, as the preferred metal for the fabrication of superconducting accelerating cavities, should meet exact specifications. The content of interstitial impurities such as oxygen, nitrogen, and carbon must be below 10μg/g. The hydrogen content should be kept below 2μg/g to prevent degradation of the Q-value under certain cool-down conditions. The material should be free of flaws (foreign material inclusions or cracks and laminations) that can initiate a thermal breakdown. Defects may be detected by quality control methods such as eddy current scanning and identified by a number of special methods. Conventional and alternative cavity fabrication methods are reviewed. Conventionally, niobium cavities are fabricated from sheet niobium by the formation of half-cells by deep drawing, followed by trim machining and Electron-Beam Welding (EBW). The welding of half-cells is a delicate...
Niobium LEP 2 accelerating cavities
An accelerating cavity from LEP. This could be cut open to show the layer of niobium on the inside. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment. These challenging requirements pushed European industry to new achievements. 256 of these cavities were used in an upgrade of the LEP accelerator to double the energy of the particle beams.
Optical re-injection in cavity-enhanced absorption spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Leen, J. Brian, E-mail: b.leen@lgrinc.com; O’Keefe, Anthony [Los Gatos Research, 67 E. Evelyn Avenue, Suite 3, Mountain View, California 94041 (United States)
2014-09-15
Non-mode-matched cavity-enhanced absorption spectrometry (e.g., cavity ringdown spectroscopy and integrated cavity output spectroscopy) is commonly used for the ultrasensitive detection of trace gases. These techniques are attractive for their simplicity and robustness, but their performance may be limited by the reflection of light from the front mirror and the resulting low optical transmission. Although this low transmitted power can sometimes be overcome with higher power lasers and lower noise detectors (e.g., in the near-infrared), many regimes exist where the available light intensity or photodetector sensitivity limits instrument performance (e.g., in the mid-infrared). In this article, we describe a method of repeatedly re-injecting light reflected off the front mirror of the optical cavity to boost the cavity's circulating power and deliver more light to the photodetector and thus increase the signal-to-noise ratio of the absorption measurement. We model and experimentally demonstrate the method's performance using off-axis cavity ringdown spectroscopy (OA-CRDS) with a broadly tunable external cavity quantum cascade laser. The power coupled through the cavity to the detector is increased by a factor of 22.5. The cavity loss is measured with a precision of 2 × 10{sup −10} cm{sup −1}/√(Hz;) an increase of 12 times over the standard off-axis configuration without reinjection and comparable to the best reported sensitivities in the mid-infrared. Finally, the re-injected CRDS system is used to measure the spectrum of several volatile organic compounds, demonstrating the improved ability to resolve weakly absorbing spectroscopic features.
Wang, Yazhou; Li, Jianfeng; Zhang, Entao; Mo, Kundong; Wang, Yanyan; Liu, Fei; Zhou, Xiaojun; Liu, Yong
2017-07-24
Coexistence of harmonic mode-locking (HML) and noise-like pulse (NLP) were experimentally observed in a dual-wavelength mode-locked Tm-doped fiber laser for the first time. The coexistence patterns were self-started and maintained within a wide pump range by appropriately setting the intra-cavity polarization state. The HML was obtained at 1955.3 nm with a varied repetition rate range from 324 MHz to 1.138 GHz which benefits from the dispersion compensation, while the NLP observing at 1983.2 nm can operate at either fundamental repetition rate of 4.765 MHz or second harmonic state. Experimental investigations show that the coexistence patterns are caused by the wavelength-dependent phase delay of the mode-locked fiber cavity. Moreover, dual-wavelength NLP was also observed for the first time at 2 μm spectral region by changing the intra-cavity polarization state.
Dispersion-enhanced third-harmonic microscopy
Stock, Christian; Zlatanov, Kaloyan; Halfmann, Thomas
2017-06-01
We demonstrate strong enhancements of signal yield and image contrast in third-harmonic microscopy by appropriate choice of driving laser wavelength to modulate the phase-matching conditions of the conversion process by dispersion control. Tuning the laser wavelength in the range of 1010 - 1350 nm at samples containing interfaces with water and glass, we obtained large signal enhancements up to a factor of 19, and improvements in the image contrast by an order of magnitude. The effect is most pronounced at interfaces with media of small and/or not too different nonlinear optical susceptibilities, e.g., as it is the case in typical samples in harmonic microscopy. Beyond the demonstration of this new variant of third-harmonic microscopy, our findings are also of relevance to a proper choice of laser systems for harmonic microscopy setups.
Developing Castable Metal Harmonic Drives Project
National Aeronautics and Space Administration — This effort utilizes the high elastic strain limit and net-shaped processing of metallic glasses to fabricate low-cost harmonic drives that outperform steel. ...
Challenges and Opportunities for Harmonizing Research Methodology
DEFF Research Database (Denmark)
van Hees, V. T.; Thaler-Kall, K.; Wolf, K. H.
2016-01-01
Objectives: Raw accelerometry is increasingly being used in physical activity research, but diversity in sensor design, attachment and signal processing challenges the comparability of research results. Therefore, efforts are needed to harmonize the methodology. In this article we reflect on how...... increased methodological harmonization may be achieved. Methods: The authors of this work convened for a two-day workshop (March 2014) themed on methodological harmonization of raw accelerometry. The discussions at the workshop were used as a basis for this review. Results: Key stakeholders were identified...... algorithms which are pitched as "ready for implementation" should be shared with the community to facilitate replication and ongoing evaluation by independent groups, and v) A dynamic interaction between method stakeholders should be encouraged to facilitate a well-informed harmonization process. Conclusions...
Improved Efficiency Type II Second Harmonic Generation
Barnes, Norman P.; Walsh, Brian M.; Reichle, Donald J., Jr.
2009-01-01
Second harmonic efficiency is limited by lateral and temporal separation of the ordinary and extraordinary components of the fundamental. A mode locked dual beam laser demonstrated these effects and a novel method to minimize them.
Multiculturalism, Europhilia and harmonization: harmony or disharmony?
Directory of Open Access Journals (Sweden)
Ruth Sefton-Green
2010-11-01
Full Text Available This paper examines the difficulties of reconciling the values promoted by multiculturalism with the objectives of harmonization. In the event of conflict, examples from English and French law show that harmonization of private law rules does not always achieve its aim of approximating national laws but, on the contrary, often backfires. The question of whether and why these divergences produce Europhile or Eurosceptic positions amongst Member States is addressed. It appears that when maximum harmonisation clashes with multiculturalism this can lead to legal nationalism, whereas minimum harmonization has less negative effects and can stimulate legal experimentation. It is suggested that harmonization requires a mutual listening and learning process in order to accommodate the multiculturalism of Member States and enable Europhilia to flourish in the European Union.
Reduction of Harmonics by 18-Pulse Rectifier
Directory of Open Access Journals (Sweden)
Stanislav Kocman
2008-01-01
Full Text Available Operation of such electrical devices as data processing and electronics devices, adjustable speed drives or uninterruptible power supply can cause problems by generating harmonic currents into the network, from which they are supplied. Effects of these harmonic currents are various, they can get worse the quality of supply voltage in the network or to have negative influences on devices connected to this network. There are various technical solutions for reduction of harmonics. One of them is using of multi-pulse rectifiers, whereas the 18-pulse rectifier in the structure of adjustable speed drive is briefly presented in this paper including some results of its behaviour. The examined experimental measurements confirmed its very good efficiency in the harmonic mitigation.
Perturbative High Harmonic Wave Front Control.
Li, Zhengyan; Brown, Graham; Ko, Dong Hyuk; Kong, Fanqi; Arissian, Ladan; Corkum, P B
2017-01-20
We pattern the wave front of a high harmonic beam by intersecting the intense driving laser pulse that generates the high harmonic with a weak control pulse. To illustrate the potential of wave-front control, we imprint a Fresnel zone plate pattern on a harmonic beam, causing the harmonics to focus and defocus. The quality of the focus that we achieve is measured using the spectral wave-front optical reconstruction by diffraction method. We will show that it is possible to enhance the peak intensity by orders of magnitude without a physical optical element in the path of the extreme ultraviolet (XUV) beam. Through perturbative wave-front control, XUV beams can be created with a flexibility approaching what technology allows for visible and infrared light.
On conformal supergravity and harmonic superspace
Energy Technology Data Exchange (ETDEWEB)
Butter, Daniel [Nikhef Theory Group,Science Park 105, 1098 XG Amsterdam (Netherlands)
2016-03-16
This paper describes a fully covariant approach to harmonic superspace. It is based on the conformal superspace description of conformal supergravity and involves extending the supermanifold M{sup 4|8} by the tangent bundle of ℂP{sup 1}. The resulting superspace M{sup 4|8}×TℂP{sup 1} can be identified in a certain gauge with the conventional harmonic superspace M{sup 4|8}×S{sup 2}. This approach not only makes the connection to projective superspace transparent, but simplifies calculations in harmonic superspace significantly by eliminating the need to deal directly with supergravity prepotentials. As an application of the covariant approach, we derive from harmonic superspace the full component action for the sigma model of a hyperkähler cone coupled to conformal supergravity. Further applications are also sketched.
LEP Radio Frequency Copper Cavity
The pulse of a particle accelerator. 128 of these radio frequency cavities were positioned around CERN's 27-kilometre LEP ring to accelerate electrons and positrons. The acceleration was produced by microwave electric oscillations at 352 MHz. The electrons and positrons were grouped into bunches, like beads on a string, and the copper sphere at the top stored the microwave energy between the passage of individual bunches. This made for valuable energy savings as it reduced the heat generated in the cavity.
Single and Coupled Nanobeam Cavities
DEFF Research Database (Denmark)
Ivinskaya, Aliaksandra; Lavrinenko, Andrei; Shyroki, Dzmitry M.
2013-01-01
of photonic crystal filters. The second part focuses on some aspects of photonic crystals fabrication and relevant applications, such as nitrogen defect technology in diamond, silicon nitride free standing membranes, photonic crystals structures in silicon, photonic crystals for optical sensing....... for analysis and design of photonic crystal devices, such as 2D ring resonators for filters, single and coupled nanobeam cavities, birefringence in photonic crystal cavities, threshold analysis in photonic crystal lasers, gap solitons in photonic crystals, novel photonic atolls, dynamic characteristics...
Energy Technology Data Exchange (ETDEWEB)
Schneidmiller, E.A.; Yurkov, M.V.
2012-05-15
Harmonic lasing in a free electron laser with a planar undulator (under the condition that the fundamental frequency is suppressed) might be a cheap and efficient way of extension of wavelength ranges of existing and planned X-ray FEL facilities. Contrary to nonlinear harmonic generation, harmonic lasing can provide much more intense, stable, and narrow-band FEL beam which is easier to handle due to the suppressed fundamental frequency. In this paper we perform a parametrization of the solution of the eigenvalue equation for lasing at odd harmonics, and present an explicit expression for FEL gain length, taking into account all essential effects. We propose and discuss methods for suppression of the fundamental harmonic. We also suggest a combined use of harmonic lasing and lasing at the retuned fundamental wavelength in order to reduce bandwidth and to increase brilliance of X-ray beam at saturation. Considering 3rd harmonic lasing as a practical example, we come to the conclusion that it is much more robust than usually thought, and can be widely used in the existing or planned X-ray FEL facilities. In particular, LCLS after a minor modification can lase to saturation at the 3rd harmonic up to the photon energy of 25-30 keV providing multi-gigawatt power level and narrow bandwidth. As for the European XFEL, harmonic lasing would allow to extend operating range (ultimately up to 100 keV), to reduce FEL bandwidth and to increase brilliance, to enable two-color operation for pump-probe experiments, and to provide more flexible operation at different electron energies. Similar improvements can be realized in other X-ray FEL facilities with gap-tunable undulators like FLASH II, SACLA, LCLS II, etc. Harmonic lasing can be an attractive option for compact X-ray FELs (driven by electron beams with a relatively low energy), allowing the use of the standard undulator technology instead of small-gap in-vacuum devices. Finally, in this paper we discover that in a part of the
Fractal harmonic law and waterproof/dustproof
Directory of Open Access Journals (Sweden)
Kong Hai-Yan
2014-01-01
Full Text Available The fractal harmonic law admits that the friction between the pure water and the moving surface is the minimum when fractal dimensions of water in Angstrom scale are equal to fractal dimensions of the moving surface in micro scale. In the paper, the fractal harmonic law is applied to demonstrate the mechanism of waterproof/ dustproof. The waterproof phenomenon of goose feathers and lotus leaves is illustrated to verify our results and experimental results agree well with our theoretical analysis.
Harmonic algebraic curves and noncrossing partitions
Martin, Jeremy; Savitt, David; Singer, Ted
2005-01-01
Motivated by Gauss's first proof of the Fundamental Theorem of Algebra, we study the topology of harmonic algebraic curves. By the maximum principle, a harmonic curve has no bounded components; its topology is determined by the combinatorial data of a noncrossing matching. Similarly, every complex polynomial gives rise to a related combinatorial object that we call a basketball, consisting of a pair of noncrossing matchings satisfying one additional constraint. We prove that every noncrossing...
Harmonic distortion in microwave photonic filters.
Rius, Manuel; Mora, José; Bolea, Mario; Capmany, José
2012-04-09
We present a theoretical and experimental analysis of nonlinear microwave photonic filters. Far from the conventional condition of low modulation index commonly used to neglect high-order terms, we have analyzed the harmonic distortion involved in microwave photonic structures with periodic and non-periodic frequency responses. We show that it is possible to design microwave photonic filters with reduced harmonic distortion and high linearity even under large signal operation.
Harmonic Oscillator SUSY Partners and Evolution Loops
Directory of Open Access Journals (Sweden)
David J. Fernández
2012-07-01
Full Text Available Supersymmetric quantum mechanics is a powerful tool for generating exactly solvable potentials departing from a given initial one. If applied to the harmonic oscillator, a family of Hamiltonians ruled by polynomial Heisenberg algebras is obtained. In this paper it will be shown that the SUSY partner Hamiltonians of the harmonic oscillator can produce evolution loops. The corresponding geometric phases will be as well studied.
TOTAL HARMONIC DISTORTION ANALYSIS OF MATRIX CONVERTER
K. Kandan; Senthilkumar,K.; Dhivya, K.
2016-01-01
This paper deals with the validation and design analysis of Matrix converter for variable frequency using mathematical equations. The analysis was done using Venturini modulation algorithm. The PI controller is used for Matrix converter to reduce Total Harmonic Distortion (THD) in the output current. The comparative study is done for open loop and closed loop PI compensation in MATLAB-Simulink. Furthermore, the output waveforms are produced with significant reduction in the Total Harmonic Dis...
A new awakening for accelerator cavities
Katarina Anthony
2013-01-01
Imagine: an accelerator unbound by length; one that can bring a beam up to the TeV level in just a few hundred metres. Sounds like a dream? Perhaps not for long. At CERN’s Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE), physicists may soon be working to bring this contemporary fairy-tale to life. The AWAKE experiment in the CNGS facility. Wherever you find a modern linear particle accelerator, you’ll find with it a lengthy series of RF accelerating cavities. Although based on technology first developed over half a century ago, RF cavities have dominated the accelerating world since their inception. However, new developments in plasma accelerator systems may soon be bringing a new player into the game. By harnessing the power of wakefields generated by beams in plasma cells, physicists may be able to produce accelerator gradients of many GV/m – hundreds of times higher than those achieved in current RF cavities. “Plasma wakef...
Harmonic focus in thyroidectomy for substernal goiter.
Hahn, Christoffer Holst; Trolle, Waldemar; Sørensen, Christian Hjort
2015-08-01
No previous prospective study has evaluated harmonic scalpel in thyroidectomy for substernal goiter. The objective of this study was to evaluate the use of harmonic scalpel (FOCUS shear, Ethicon Endo-Surgery) in thyroidectomy for substernal goiter for blood loss, operative time, hospital stay and complications. Prospective non-randomised study of 242 consecutive patients with substernal goiter out of 2258 patients (11%) who underwent thyroidectomy. A total of 121 patients had thyroidectomy performed with bipolar electrocoagulation and knot-tying techniques and 121 patients had harmonic scalpel thyroidectomy. The use of harmonic scalpel was associated with significant reduction in intraoperative blood loss (50 vs. 100mL, p=0.001), postoperative haemorrhage (4% vs. 12%, p=0.03) and length of hospital stay (2 vs. 3 days, p=0.001). The mean operative time was significantly longer in the harmonic group. Harmonic scalpel is a safe tool for thyroidectomy for substernal goiter. Its utilisation is associated with reduced blood loss, lower incidence of postoperative haemorrhage and shorter hospital stay. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
High harmonic generation from axial chiral molecules.
Wang, Dian; Zhu, Xiaosong; Liu, Xi; Li, Liang; Zhang, Xiaofan; Lan, Pengfei; Lu, Peixiang
2017-09-18
Axial chiral molecules, whose stereogenic element is an axis rather than a chiral center, have attracted widespread interest due to their important application, such as asymmetric synthesis and chirality transfer. We investigate high harmonic generation from axial chiral molecules with bichromatic counterrotating circularly polarized laser fields. High harmonic generation from three typical molecules: (Sa)-3-chloropropa-1,2-dien-1-ol, propadiene, and (Ra)-2,3-pentadiene is simulated with time-dependent density-functional theory and strong field approximation. We found that harmonic spectra for 3D oriented axial chiral molecules exhibit obvious circular dichroism. However, the circular dichroism of High harmonic generation from an achiral molecule is much trivial. Moreover, the dichroism of high harmonic generation still exists when axial chiral molecules are 1D oriented,such as (Sa) -3-chloropropa-1,2-dien-1-ol. For a special form of axial chiral molecules with the formula abC=C=Cab (a, b are different substituents), like (Ra)-2,3-pentadiene, the dichroism discriminations disappear when the molecules are only in 1D orientation. The circular dichroism of high harmonic generation from axial chiral molecules is well explained by the trajectory analysis based on the semiclassical three-step mechanism.
Detecting the harmonics of oscillations with time-variable frequencies
Sheppard, L. W.; Stefanovska, A.; McClintock, P. V. E.
2011-01-01
A method is introduced for the spectral analysis of complex noisy signals containing several frequency components. It enables components that are independent to be distinguished from the harmonics of nonsinusoidal oscillatory processes of lower frequency. The method is based on mutual information and surrogate testing combined with the wavelet transform, and it is applicable to relatively short time series containing frequencies that are time variable. Where the fundamental frequency and harmonics of a process can be identified, the characteristic shape of the corresponding oscillation can be determined, enabling adaptive filtering to remove other components and nonoscillatory noise from the signal. Thus the total bandwidth of the signal can be correctly partitioned and the power associated with each component then can be quantified more accurately. The method is first demonstrated on numerical examples. It is then used to identify the higher harmonics of oscillations in human skin blood flow, both spontaneous and associated with periodic iontophoresis of a vasodilatory agent. The method should be equally relevant to all situations where signals of comparable complexity are encountered, including applications in astrophysics, engineering, and electrical circuits, as well as in other areas of physiology and biology.
Formants and musical harmonics matching in Brazilian lied
Raposo de Medeiros, Beatriz
2004-05-01
This paper reports a comparison of the formant patterns of speech and singing. Measurements of the first three formants were made on the stable portion of the vowels. The main finding of the study is an acoustic effect that can be described as the matching of the vowel formants to the harmonics of the sung note (A flat, 420 Hz). For example, for the vowel [a], F1 generally matched with the second harmonic (840 Hz) and F2 with the third harmonic. This finding is complementary to that of Sundberg (1977) according to which the higher the fundamental frequency of the musical note, e.g., 700 Hz, the more the mandible is lowered causing the elevation of the first formant of the sung vowel. As Sundberg himself named this phenomenon, there is a matching between the first formant and the phonation frequency, causing an increase in the sound energy. The present study establishes that the matching affects not only F1 but also F2 and F3. This finding will be discussed in connection with other manoeuvres (e.g., tongue movements) used by singers.
Observation of redshifting and harmonic radiation in inverse Compton scattering
Sakai, Y.; Pogorelsky, I.; Williams, O.; O'Shea, F.; Barber, S.; Gadjev, I.; Duris, J.; Musumeci, P.; Fedurin, M.; Korostyshevsky, A.; Malone, B.; Swinson, C.; Stenby, G.; Kusche, K.; Babzien, M.; Montemagno, M.; Jacob, P.; Zhong, Z.; Polyanskiy, M.; Yakimenko, V.; Rosenzweig, J.
2015-06-01
Inverse Compton scattering of laser photons by ultrarelativistic electron beam provides polarized x- to γ -ray pulses due to the Doppler blueshifting. Nonlinear electrodynamics in the relativistically intense linearly polarized laser field changes the radiation kinetics established during the Compton interaction. These are due to the induced figure-8 motion, which introduces an overall redshift in the radiation spectrum, with the concomitant emission of higher order harmonics. To experimentally analyze the strong field physics associated with the nonlinear electron-laser interaction, clear modifications to the angular and wavelength distributions of x rays are observed. The relativistic photon wave field is provided by the ps CO2 laser of peak normalized vector potential of 0.5 laser [M. Babzien et al., Phys. Rev. Lett. 96, 054802 (2006)]. The angular spectral characteristics are revealed using K -, L -edge, and high energy attenuation filters. The observation indicates existence of the electrons' longitudinal motion through frequency redshifting understood as the mass shift effect. Thus, the 3rd harmonic radiation has been observed containing on-axis x-ray component that is directly associated with the induced figure-8 motion. These are further supported by an initial evidence of off-axis 2nd harmonic radiation produced in a circularly polarized laser wave field. Total x-ray photon number per pulse, scattered by 65 MeV electron beam of 0.3 nC, at the interaction point is measured to be approximately 109 .
Fighting African Capital Flight: Empirics on Benchmarking Policy Harmonization
Directory of Open Access Journals (Sweden)
Simplice A. Asongu
2014-06-01
Full Text Available With earthshaking and heartbreaking trends in African capital flight provided by a new database, this paper complements existing literature by answering some key policy questions on the feasibility of and timeframe for policy harmonization in the battle against the economic scourge. The goal of the paper is to study beta-convergence of capital flight across a set of 37 African countries in the period 1980-2010 and to discuss the policy implications. Three main findings are established. (1 African countries with low capital flight rates are catching-up their counterparts with higher rates, implying the feasibility ofpolicy harmonization towards fighting capital flight. (2 Petroleum-exporting and conflict-affected countries significantly play out in absolute and conditional convergences respectively. (3 Regardless of fundamental characteristics, a genuine timeframe for harmonizing policies is within a horizon of 6 to 13 years. Inother words, full (100% convergence within the specifiedhorizon is an indication that policies and regulations can be enforced without distinction of nationality or locality.
High-order harmonic generation in laser plasma: Recent achievements
Ganeev, R. A.
2012-07-01
Recent studies of high-order harmonic generation of laser radiation in laser-produced plasma show new attractive developments in this field. Those include generation of extended harmonics in plasma plumes, new approaches in application of two-color pump, generation of extremely broadened harmonics, further developments in harmonic generation in clusters (fullerenes, carbon nanotubes, in-situ produced nanoparticles), destructive interference of harmonics from different emitters, resonance-induced enhancement of harmonics, applications of high pulse repetition rate lasers for the enhancement of average power of generating harmonics, observation of quantum path signatures, etc. We review some of these recent developments.
Semi-automatic segmentation of femur based on harmonic barrier.
Zou, Zheng; Liao, Sheng-Hui; Luo, San-Ding; Liu, Qing; Liu, Shi-Jian
2017-05-01
Segmentation of the femur from the hip joint in computed tomography (CT) is an important preliminary step in hip surgery planning and simulation. However, this is a time-consuming and challenging task due to the weak boundary, the varying topology of the hip joint, and the extremely narrow or blurred space between the femoral head and the acetabulum. To address these problems, this study proposed a semi-automatic segmentation framework based on harmonic fields for accurate segmentation. The proposed method comprises three steps. First, with high-level information provided by the user, shape information provided by neighboring slices as well as the statistical information in the mask, a region selection method is proposed to effectively locate joint space for the harmonic field. Second, incorporated with an improved gradient, the harmonic field is used to adaptively extract a curve as the barrier that separates the femoral head from the acetabulum accurately. Third, a divide and conquer segmentation strategy based on the harmonic barrier is used to combine the femoral head part and body part as the final segmentation result. We have tested 40 hips with considerately narrow or disappeared joint spaces. The experimental results are evaluated based on Jaccard, Dice, directional cut discrepancy (DCD) and receiver operating characteristic (ROC), and we achieve the higher Jaccard of 84.02%, Dice of 85.96%, area under curve (AUC) of 89.3%, and the lower error with DCD of 0.52mm. The effective ratio of our method is 79.1% even for cases with severe malformation. The results show that our method performs best in terms of effectiveness and accuracy on the whole data set. The proposed method is efficient to segment femurs with narrow joint space. The accurate segmentation results can assist the physicians for osteoarthritis diagnosis in future. Copyright © 2017 Elsevier B.V. All rights reserved.
Entanglement of a two-atom system driven by the quantum vacuum in arbitrary cavity size
Flores-Hidalgo, G.; Rojas, M.; Rojas, Onofre
2017-05-01
We study the entanglement dynamics of two distinguishable atoms confined into a cavity and interacting with a quantum vacuum field. As a simplified model for this system, we consider two harmonic oscillators linearly coupled to a massless scalar field which are inside a spherical cavity of radius R. Through the concurrence, the entanglement dynamics for the two-atom system is discussed for a range of initial states composed of a superposition of atomic states. Our results reveal how the entanglement of the two atoms behaves through the time evolution, in a precise way, for arbitrary cavity size and for arbitrary coupling constant. All our computations are analytical and only the final step is numerical.
Fabrication of elliptical SRF cavities
Singer, W.
2017-03-01
The technological and metallurgical requirements of material for high-gradient superconducting cavities are described. High-purity niobium, as the preferred metal for the fabrication of superconducting accelerating cavities, should meet exact specifications. The content of interstitial impurities such as oxygen, nitrogen, and carbon must be below 10 μg g-1. The hydrogen content should be kept below 2 μg g-1 to prevent degradation of the quality factor (Q-value) under certain cool-down conditions. The material should be free of flaws (foreign material inclusions or cracks and laminations) that can initiate a thermal breakdown. Traditional and alternative cavity mechanical fabrication methods are reviewed. Conventionally, niobium cavities are fabricated from sheet niobium by the formation of half-cells by deep drawing, followed by trim machining and electron beam welding. The welding of half-cells is a delicate procedure, requiring intermediate cleaning steps and a careful choice of weld parameters to achieve full penetration of the joints. A challenge for a welded construction is the tight mechanical and electrical tolerances. These can be maintained by a combination of mechanical and radio-frequency measurements on half-cells and by careful tracking of weld shrinkage. The main aspects of quality assurance and quality management are mentioned. The experiences of 800 cavities produced for the European XFEL are presented. Another cavity fabrication approach is slicing discs from the ingot and producing cavities by deep drawing and electron beam welding. Accelerating gradients at the level of 35-45 MV m-1 can be achieved by applying electrochemical polishing treatment. The single-crystal option (grain boundary free) is discussed. It seems that in this case, high performance can be achieved by a simplified treatment procedure. Fabrication of the elliptical resonators from a seamless pipe as an alternative is briefly described. This technology has yielded good
Mirror-smooth surfaces and repair of defects in superconducting RF cavities by mechanical polishing
Energy Technology Data Exchange (ETDEWEB)
Cooper, C. A. [Fermilab; Cooley, L. D. [Fermilab
2012-11-22
Mechanical techniques for polishing the inside surface of niobium superconducting radio-frequency (SRF) cavities have been systematically explored. By extending known techniques to fine polishing, mirror-like finishes were produced, with <15 nm RMS (root mean square) roughness over 1 mm2 scan area. This is an order of magnitude less than the typical roughness produced by the electropolishing of niobium cavities. The extended mechanical polishing (XMP) process was applied to several SRF cavities which exhibited equator defects that caused quench at <20 MV m-1 and were not improved by further electropolishing. Cavity optical inspection equipment verified the complete removal of these defects, and minor acid processing, which dulled the mirror finish, restored performance of the defective cells to the high gradients and quality factors measured for adjacent cells when tested with other harmonics. This innate repair feature of XMP could be used to increase manufacturing yield. Excellent superconducting properties resulted after initial process optimization, with quality factor Q of 3 × 1010 and accelerating gradient of 43 MV m-1 being attained for a single-cell TESLA cavity, which are both close to practical limits. Several repaired nine-cell cavities also attained Q > 8 × 109 at 35 MV m-1, which is the specification for the International Linear Collider. Future optimization of the process and pathways for eliminating requirements for acid processing are also discussed.
Cryogenic Test of a Proof-of-Principle Superconducting RF-Dipole Deflecting and Crabbing Cavity
De Silva, S U; Delayen, Jean Roger
2013-01-01
Recent applications in need of compact low-frequency deflecting and crabbing cavities have initiated the design and development of new superconducting structures operating at high gradients with low losses. Previously, TM$_{110}$ -type deflecting and crabbing cavities were developed and have also been operated successfully. However, these geometries are not favorable designs for low operating frequencies. The superconducting rf-dipole cavity is the first compact deflecting and crabbing geometry that has demonstrated high gradients and high shunt impedance. Since the fundamental operating mode is the lowest mode and is widely separated from the nearest higher order mode, the rf-dipole design is an attractive geometry for effective damping of the higher order modes in high current applications. A 400 MHz rf-dipole cavity was designed, fabricated, and tested as a proof-of-principle cavity. The cavity achieved high operating gradients, and the multipacting levels were easily processed and did not reoccur.
Vierling, Kerri T.; Lorenz, Teresa J.; Cunningham, Patrick; Potterf, Kelsi
2017-11-01
Tree cavities provide critical roosting and breeding sites for multiple species, and thermal environments in these cavities are important to understand. Our objectives were to (1) describe thermal characteristics in cavities between June 3 and August 9, 2014, and (2) investigate the environmental factors that influence cavity temperatures. We placed iButtons in 84 different cavities in ponderosa pine (Pinus ponderosa) forests in central Washington, and took hourly measurements for at least 8 days in each cavity. Temperatures above 40 °C are generally lethal to developing avian embryos, and 18% of the cavities had internal temperatures of ≥ 40 °C for at least 1 h of each day. We modeled daily maximum cavity temperature, the amplitude of daily cavity temperatures, and the difference between the mean internal cavity and mean ambient temperatures as a function of several environmental variables. These variables included canopy cover, tree diameter at cavity height, cavity volume, entrance area, the hardness of the cavity body, the hardness of the cavity sill (which is the wood below the cavity entrance which forms the barrier between the cavity and the external environment), and sill width. Ambient temperature had the largest effect size for maximum cavity temperature and amplitude. Larger trees with harder sills may provide more thermally stable cavity environments, and decayed sills were positively associated with maximum cavity temperatures. Summer temperatures are projected to increase in this region, and additional research is needed to determine how the thermal environments of cavities will influence species occupancy, breeding, and survival.
Red-cockaded woodpecker nest-cavity selection: relationships with cavity age and resin production
Richard N. Conner; Daniel Saenz; D. Craig Rudolph; William G. Ross; David L. Kulhavy
1998-01-01
The authors evaluated selection of nest sites by male red-cockaded woodpeckers (Picoides borealis) in Texas relative to the age of the cavity when only cavities excavated by the woodpeckers were available and when both naturally excavated cavities and artificial cavities were available. They also evaluated nest-cavity selection relative to the ability of naturally...
Liu, Hang; Feng, Liqiang
2017-09-01
Electron-nuclear dynamics of molecular high-order harmonic generation from H2+ and its isotopes has been theoretically investigated beyond the Born-Oppenheimer approximations. The results show that (i) due to the different ionisation probabilities and the harmonic emission times, the intensities of the harmonics from H2+ and its isotopes are very sensitive to the initial vibrational state, the pulse duration, and the pulse intensity. (ii) Due to the nonadiabatic effects in molecular high-order harmonic generation, the red-shifts of the harmonics can be found in the lower pulse intensity. With the increase of the pulse intensity, the harmonics are from the red-shifts to the blue-shifts. Moreover, as the pulse duration increases, the blue-shifts of the harmonics can be enhanced. As the initial vibrational state increases, the red-shifts of the harmonics can be decreased, whereas the blue-shifts of the harmonics can be enhanced. However, the shifts of the harmonics are decreased as the nuclear mass increases. (iii) Due to the coupled electron-nuclear dynamics in molecules, the spatial symmetry of the system is broken. As a result, non-odd harmonics can be generated at the larger internuclear distance. With the increase of the initial vibrational state or the nuclear mass, the generation of the non-odd harmonics can be enhanced and reduced, respectively. As the pulse duration or the pulse intensity increase, the generation of the non-odd harmonics can be enhanced. However, the intensities of the non-odd harmonics are decreased when using the longer pulse duration with the much higher laser intensity.
Spectral pattern, harmonic relations, and the perceptual grouping of low-numbered components.
Roberts, Brian; Brunstrom, Jeffrey M
2003-10-01
Mistuning a harmonic increases its salience and produces an exaggerated change in its pitch. The effects on component grouping of spectral pattern, global pitch, and local harmonicity were explored using these phenomena. Stimuli were either harmonic (F0 = 200 Hz) or frequency shifted by 25% of F0. Component 1 or 2 was replaced by one of a set of sinusoidal probes in the same spectral region. Listeners either matched the probe pitch by adjusting the frequency of a pure tone (experiments 1 and 3) or matched the probe loudness by adjusting the level of a tone of identical frequency (experiment 2). Probe positions corresponding to greatest perceptual fusion were estimated from the variations in pitch shift and loudness across frequency. Both measures gave similar estimates. For harmonic stimuli, fusion was greatest at harmonic values. For shifted stimuli, fusion was greatest close to the suboctave (225 Hz) and the frequency (450 Hz) of component 2. The latter value moved downwards to near 433 Hz (2:3 ratio with component 3) when component 1 was removed. Together, these results indicate that the lowest component of a shifted complex is grouped by local harmonicity, whereas the higher components are grouped by common spectral spacing. Global pitch did not influence component grouping.
Stochastic electrodynamics simulations for collective atom response in optical cavities
Lee, Mark D.; Jenkins, Stewart D.; Bronstein, Yael; Ruostekoski, Janne
2017-08-01
We study the collective optical response of an atomic ensemble confined within a single-mode optical cavity by stochastic electrodynamics simulations that include the effects of atomic position correlations, internal level structure, and spatial variations in cavity coupling strength and atom density. In the limit of low light intensity, the simulations exactly reproduce the full quantum field-theoretical description for cold stationary atoms and at higher light intensities we introduce semiclassical approximations to atomic saturation that we compare with the exact solution in the case of two atoms. We find that collective subradiant modes of the atoms, with very narrow linewidths, can be coupled to the cavity field by spatial variation of the atomic transition frequency and resolved at low intensities, and show that they can be specifically driven by tailored transverse pumping beams. We show that the cavity optical response, in particular both the subradiant mode profile and the resonance shift of the cavity mode, can be used as a diagnostic tool for the position correlations of the atoms and hence the atomic quantum many-body phase. The quantum effects are found to be most prominent close to the narrow subradiant mode resonances at high light intensities. Although an optical cavity can generally strongly enhance quantum fluctuations via light confinement, we show that the semiclassical approximation to the stochastic electrodynamics model provides at least a qualitative agreement with the exact optical response outside the subradiant mode resonances even in the presence of significant saturation of the atoms.
An Experimental Microwave Cavity Alkali Metal Plasma Source
Case, A.; Noonan, W. A.; Skiff, F. N.
1997-11-01
A new experimental source for singly ionized alkali metal plasma is presented. This source extends the work of Asmussen et al. al.(J. Asmussen, R. Mallavarpu, J. R. Hamann, H. C. Park Proc. IEEE), 62, 109 (1974)on microwave cavity gas discharges to include Alkali Metals in an effort to provide a simple and inexpensive source of Barium plasma for spectroscopic investigation of plasma phenomena. The source consists of a cylindrical microwave cavity resonant in the TM_112 mode. Barium is vaporized in a specially designed oven and the vapor passed into the cavity through a small opening in one end. The cavity length is adjusted with a moveable plunger so as to maintain the plasma-cavity system in resonance with the 2.45 GHz magnetron feeding power into the cavity. By avoiding plasma resonances, unnecessary heating of the plasma is avoided. The plasma is magnetized (field strength 80-120 Gauss) and the plasma flows along the field lines through a mesh in the plunger and out into the experimental region of the vacuum chamber. This source design holds considerable promise for extension to higher magnetic field strengths.
Low-frequency approximation for high-order harmonic generation by a bicircular laser field
Milošević, D. B.
2018-01-01
We present low-frequency approximation (LFA) for high-order harmonic generation (HHG) process. LFA represents the lowest-order term of an expansion of the final-state interaction matrix element in powers of the laser-field frequency ω . In this approximation the plane-wave recombination matrix element which appears in the strong-field approximation is replaced by the exact laser-free recombination matrix element calculated for the laser-field dressed electron momenta. First, we have shown that the HHG spectra obtained using the LFA agree with those obtained solving the time-dependent Schrödinger equation. Next, we have applied this LFA to calculate the HHG rate for inert gases exposed to a bicircular field. The bicircular field, which consists of two coplanar counter-rotating fields having different frequencies (usually ω and 2 ω ), is presently an important subject of scientific research since it enables efficient generation of circularly polarized high-order harmonics (coherent soft x rays). Analyzing the photorecombination matrix element we have found that the HHG rate can efficiently be calculated using the angular momentum basis with the states oriented in the direction of the bicircular field components. Our numerical results show that the HHG rate for atoms having p ground state, for higher high-order harmonic energies, is larger for circularly polarized harmonics having the helicity -1 . For lower energies the harmonics having helicity +1 prevails. The transition between these two harmonic energy regions can appear near the Cooper minimum, which, in the case of Ar atoms, makes the selection of high-order harmonics having the same helicity much easier. This is important for applications (for example, for generation of attosecond pulse trains of circularly polarized harmonics).
Infrasonic harmonic tremor and degassing bursts from Halema'uma'u Crater, Kilauea Volcano, Hawaii
Fee, David; Garcés, Milton; Patrick, Matt; Chouet, Bernard; Dawson, Phil; Swanson, Donald A.
2010-01-01
The formation, evolution, collapse, and subsequent resurrection of a vent within Halema'uma'u Crater, Kilauea Volcano, produced energetic and varied degassing signals recorded by a nearby infrasound array between 2008 and early 2009. After 25 years of quiescence, a vent-clearing explosive burst on 19 March 2008 produced a clear, complex acoustic signal. Near-continuous harmonic infrasonic tremor followed this burst until 4 December 2008, when a period of decreased degassing occurred. The tremor spectra suggest volume oscillation and reverberation of a shallow gas-filled cavity beneath the vent. The dominant tremor peak can be sustained through Helmholtz oscillations of the cavity, while the secondary tremor peak and overtones are interpreted assuming acoustic resonance. The dominant tremor frequency matches the oscillation frequency of the gas emanating from the vent observed by video. Tremor spectra and power are also correlated with cavity geometry and dynamics, with the cavity depth estimated at ~219 m and volume ~3 x 106 m3 in November 2008. Over 21 varied degassing bursts were observed with extended burst durations and frequency content consistent with a transient release of gas exciting the cavity into resonance. Correlation of infrasound with seismicity suggests an open system connecting the atmosphere to the seismic excitation process at depth. Numerous degassing bursts produced very long period (0.03-0.1 Hz) infrasound, the first recorded at Kilauea, indicative of long-duration atmospheric accelerations. Kilauea infrasound appears controlled by the exsolution of gas from the magma, and the interaction of this gas with the conduits and cavities confining it.
Regulatory harmonization of the Saskatchewan uranium mines
Energy Technology Data Exchange (ETDEWEB)
Forbes, R. [Canadian Nuclear Safety Commission, Ottawa, Ontario (Canada); Moulding, T. [Saskatchewan Environment, Saskatchewan (Canada); Alderman, G. [Saskatchewan Labour, Saskatchewan (Canada)
2006-07-01
The uranium mining industry in Saskatchewan produces approximately 30% of the world's production of uranium. The industry is regulated by federal and provincial regulators. The Canadian Nuclear Safety Commission is the principal federal regulator. The principal Saskatchewan provincial regulators are Saskatchewan Environment for provincial environmental regulations and Saskatchewan Labour for occupational health and safety regulations. In the past, mine and mill operators have requested harmonization in areas such as inspections and reporting requirements from the regulators. On February 14, 2003, Saskatchewan Environment, Saskatchewan Labour and the Canadian Nuclear Safety Commission signed a historical agreement for federal/provincial co-operation called the Canadian Nuclear Safety Commission - Saskatchewan Administrative Agreement for the Regulation of Health, Safety and the Environment at Saskatchewan Uranium Mines and Mills. This initiative responds to a recommendation made by the Joint Federal-Provincial Panel on Uranium Mining Developments in Northern Saskatchewan in 1997 and lays the groundwork to co-ordinate and harmonize their respective regulatory regimes. The implementation of the Agreement has been very successful. This paper will address the content of the Agreement including the commitments, the deliverables and the expectations for a harmonized compliance program, harmonized reporting, and the review of harmonized assessment and licensing processes as well as possible referencing of Saskatchewan Environment and Saskatchewan Labour regulations in the Nuclear Safety and Control Act. The management and implementation process will also be discussed including the schedule, stakeholder communication, the results to date and the lessons learned. (author)
Microwave harmonic generation and nonlinearity in microplasmas
Gregório, José; Parsons, Stephen; Hopwood, Jeffrey
2016-06-01
Nonlinearities in microplasmas excited by microwaves are described both experimentally and through a 2D fluid model. A split-ring resonator generates a microplasma in a 150 μm discharge gap at 1 GHz. Nonlinearity generates both radiated and conducted harmonics which are measured from 0.2-760 Torr (Ar) for power levels between 0.5 and 3 W. Asymmetric electrode configurations produce the highest 3rd harmonic power (>10 mW) at an optimal pressure of the order of 0.3 Torr. The microplasma is also demonstrated as a mixer. The experimental results are explained with the aid of a fluid model of the microplasma. The model shows that the smaller electrode in an asymmetric device is forced to attain a large microwave potential that strongly modulates the sheath thickness and the local electron energy. The voltage-dependent sheath width gives rises to a nonlinear sheath capacitance as well as short pulses of hot electron flux to the electrode. The modeled 3rd harmonic current is converted to an extractable harmonic power by a microwave circuit model. Using this technique the modeled and measured harmonic production of the microplasma are found to compare favorably.
Cavity QED with atomic mirrors
Chang, D. E.; Jiang, L.; Gorshkov, A. V.; Kimble, H. J.
2012-06-01
A promising approach to merge atomic systems with scalable photonics has emerged recently, which consists of trapping cold atoms near tapered nanofibers. Here, we describe a novel technique to achieve strong, coherent coupling between a single atom and photon in such a system. Our approach makes use of collective enhancement effects, which allow a lattice of atoms to form a high-finesse cavity within the fiber. We show that a specially designated ‘impurity’ atom within the cavity can experience strongly enhanced interactions with single photons in the fiber. Under realistic conditions, a ‘strong coupling’ regime can be reached, wherein it becomes feasible to observe vacuum Rabi oscillations between the excited impurity atom and a single cavity quantum. This technique can form the basis for a scalable quantum information network using atom-nanofiber systems.
Spectra of electron pair under harmonic and Debye potential
Energy Technology Data Exchange (ETDEWEB)
Munjal, D. [Department of Physics and Astrophysics, University of Delhi (India); Department of Physics, Swami Shraddhanand College, University of Delhi (India); Prasad, V. [Department of Physics, Swami Shraddhanand College, University of Delhi (India)
2017-02-15
Two electron systems confined by harmonic potential is known as harmonium. Such a system has been studied for many reasons in the literature. In this work we study harmonium under Debye potential. We use higher order finite difference method for the solution of Schrodinger equation. Complete energy spectrum of harmonium and harmonium under Debye potential is studied. Debye screening length shows considerable effect on the energy levels and the radial matrix elements. The results are analysed in the light of existing results and the comparison with available results shows remarkable agreement. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Quantum harmonic oscillator: an elementary derivation of the energy spectrum
Borghi, Riccardo
2017-03-01
An elementary treatment of the quantum harmonic oscillator is proposed. No previous knowledge of linear differential equation theory or Fourier analysis are required, but rather only a few basics of elementary calculus. The pivotal role in our analysis is played by the sole particle localization constraint, which implies square integrability of stationary-state wavefunctions. The oscillator ground-state characterization is then achieved in a way that could be grasped, in principle, even by first-year undergraduates. A very elementary approach to build up and to characterize all higher-level energy eigenstates completes our analysis.
Tamura, Fumihiko; Ohmori, Chihiro; Yamamoto, Masanobu; Yoshii, Masahito; Schnase, Alexander; Nomura, Masahiro; Toda, Makoto; Shimada, Taihei; Hasegawa, Katsushi; Hara, Keigo
2013-05-01
Beam loading compensation is a key for acceleration of a high intensity proton beam in the main ring (MR) of the Japan Proton Accelerator Research Complex (J-PARC). Magnetic alloy loaded rf cavities with a Q value of 22 are used to achieve high accelerating voltages without a tuning bias loop. The cavity is driven by a single harmonic (h=9) rf signal while the cavity frequency response also covers the neighbor harmonics (h=8,10). Therefore the wake voltage induced by the high intensity beam consists of the three harmonics, h=8,9,10. The beam loading of neighbor harmonics is the source of periodic transient effects and a possible source of coupled bunch instabilities. In the article, we analyze the wake voltage induced by the high intensity beam. We employ the rf feedforward method to compensate the beam loading of these three harmonics (h=8,9,10). The full-digital multiharmonic feedforward system was developed for the MR. We describe the system architecture and the commissioning methodology of the feedforward patterns. The commissioning of the feedforward system has been performed by using high intensity beams with 1.0×1014 proteins per pulse. The impedance seen by the beam is successfully reduced and the longitudinal oscillations due to the beam loading are reduced. By the beam loading compensation, stable high power beam operation is achieved. We also report the reduction of the momentum loss during the debunching process for the slow extraction by the feedforward.
Directory of Open Access Journals (Sweden)
P. Pierini
2017-04-01
Full Text Available We report the experience of the production, processing and qualification testing of the superconducting radio frequency cavities at 3.9 GHz for the third harmonic system at the European XFEL (EXFEL injector. The rf structure concept, originally developed for the FLASH FEL facility, was adapted to the new interfaces provided by the EXFEL design and the cavities were procured from a qualified vendor, delivered ready for the testing at the INFN infrastructure. A total of 23 cavities, three prototypes and two batches of 10, have been realized and tested up to specifications.
Coeliac cavity ultrasonic diagnosis apparatus
Energy Technology Data Exchange (ETDEWEB)
Ando, O.; Suwaki, T.
1983-07-05
A coeliac cavity ultrasonic diagnosis apparatus is disclosed which includes an ultrasonic transducer or scanner portion adapted to be inserted into a coeliac cavity to effect a sector scan of an ultrasonic beam to produce an ultrasonic image of internal tissues and in which the ultrasonic oscillator on the one hand and an ultrasonic reflecting mirror and rotary disc on the other hand are relatively rotated so as to effect the sector scan of the ultrasonic beam and the rotary angle of the rotary disc is detected so as to obtain a deflecting angle of the ultrasonic beam and a display on a cathode ray tube of a precise ultrasonic picture image.
Cavity Solitons in VCSEL Devices
Directory of Open Access Journals (Sweden)
S. Barbay
2011-01-01
Full Text Available We review advances on the experimental study of cavity solitons in VCSELs in the past decade. We emphasize on the design and fabrication of electrically or optically pumped broad-area VCSELs used for CSs formation and review different experimental configurations. Potential applications of CSs in the field of photonics are discussed, in particular the use of CSs for all-optical processing of information and for VCSELs characterization. Prospects on self-localization studies based on vertical cavity devices involving new physical mechanisms are also given.
Sterility of the uterine cavity
DEFF Research Database (Denmark)
Møller, Birger R.; Kristiansen, Frank V.; Thorsen, Poul
1995-01-01
In a prospective open study the sterility of the uterine cavity was evaluated in 99 women admitted for hysterectomy. The indications for hysterectomy were in most cases persistent irregular vaginal bleeding and fibromyomas of the uterus. Samples for both aerobic and anaerobic bacteria, Chlamydia...... trachomatis, yeasts and viruses were taken preoperatively from the apex of the vagina and cervical os. Immediately after hysterectomy the uterus was opened under sterile conditions and samples obtained from the isthmus and fundus of the uterine cavity for microbiological examination. Wet smears were taken...
Relativistic harmonics for turbulent wakefield diagnostics
Kuramitsu, Yasuhiro; Chen, Shih-Hung
2017-06-01
The propagation properties of relativistic harmonics excited in a plasma with an intense laser pulse is investigated theoretically and numerically. Focusing on the frequency separation, a cold electron fluid model in two spatial dimension is discussed to obtain the harmonic amplitude. The theoretical predictions are verified by performing particle-in-cell simulations in two spatial dimensions. When the laser amplitude is large, the strong ponderomotive force expels the electrons, creating a large amplitude density structures associated with the wakefield. The harmonics propagate obliquely with respect to the laser propagation direction, which is well represented by the structure of the high density layer resulting from the transverse poderomotive force. We also discuss a possible experimental setup to observe the density structures relevant to wakefield.
Optical Third-Harmonic Generation in Graphene
Directory of Open Access Journals (Sweden)
Sung-Young Hong
2013-06-01
Full Text Available We report strong third-harmonic generation in monolayer graphene grown by chemical vapor deposition and transferred to an amorphous silica (glass substrate; the photon energy is in three-photon resonance with the exciton-shifted van Hove singularity at the M point of graphene. The polarization selection rules are derived and experimentally verified. In addition, our polarization- and azimuthal-rotation-dependent third-harmonic-generation measurements reveal in-plane isotropy as well as anisotropy between the in-plane and out-of-plane nonlinear optical responses of graphene. Since the third-harmonic signal exceeds that from bulk glass by more than 2 orders of magnitude, the signal contrast permits background-free scanning of graphene and provides insight into the structural properties of graphene.
Does high harmonic generation conserve angular momentum?
Fleischer, Avner; Diskin, Tzvi; Sidorenko, Pavel; Cohen, Oren
2013-01-01
High harmonic generation (HHG) is a unique and useful process in which infrared or visible radiation is frequency up converted into the extreme ultraviolet and x ray spectral regions. As a parametric process, high harmonic generation should conserve the radiation energy, momentum and angular momentum. Indeed, conservation of energy and momentum have been demonstrated. Angular momentum of optical beams can be divided into two components: orbital and spin (polarization). Orbital angular momentum is assumed to be conserved and recently observed deviations were attributed to propagation effects. On the other hand, conservation of spin angular momentum has thus far never been studied, neither experimentally nor theoretically. Here, we present the first study on the role of spin angular momentum in extreme nonlinear optics by experimentally generating high harmonics of bi chromatic elliptically polarized pump beams that interact with isotropic media. While observing that the selection rules qualitatively correspond...
Intense Harmonic Emissions Observed in Saturn's Ionosphere
Sulaiman, A. H.; Kurth, W. S.; Persoon, A. M.; Menietti, J. D.; Farrell, W. M.; Ye, S.-Y.; Hospodarsky, G. B.; Gurnett, D. A.; Hadid, L. Z.
2017-12-01
The Cassini spacecraft's first Grand Finale orbit was carried out in April 2017. This set of 22 orbits had an inclination of 63° with a periapsis grazing Saturn's ionosphere, thus providing unprecedented coverage and proximity to the planet. Cassini's Radio and Plasma Wave Science instrument repeatedly detected intense electrostatic waves and their harmonics near closest approach in the dayside equatorial topside ionosphere. The fundamental modes were found to both scale and trend best with the H+ plasma or lower hybrid frequencies, depending on the plasma composition considered. The fine-structured harmonics are unlike previous observations, which scale with cyclotron frequencies. We explore their generation mechanism and show strong evidence of their association with whistler mode waves, consistent with theory. The possibility of Cassini's presence in the ionosphere influencing the resonance and harmonics is discussed. Given their link to the lower hybrid frequency, these emissions may offer clues to constraining Saturn's ionospheric properties.
Harmonic and complex analysis in several variables
Krantz, Steven G
2017-01-01
Authored by a ranking authority in harmonic analysis of several complex variables, this book embodies a state-of-the-art entrée at the intersection of two important fields of research: complex analysis and harmonic analysis. Written with the graduate student in mind, it is assumed that the reader has familiarity with the basics of complex analysis of one and several complex variables as well as with real and functional analysis. The monograph is largely self-contained and develops the harmonic analysis of several complex variables from the first principles. The text includes copious examples, explanations, an exhaustive bibliography for further reading, and figures that illustrate the geometric nature of the subject. Each chapter ends with an exercise set. Additionally, each chapter begins with a prologue, introducing the reader to the subject matter that follows; capsules presented in each section give perspective and a spirited launch to the segment; preludes help put ideas into context. Mathematicians and...
[Use of Harmonic blade in face lifting].
Firmin, F; Vincent, P-L
2017-10-01
Rapid recovery and return to social activities are what every patient wishes when considering to undergo a face lifting procedure. In our practice, the use of the Harmonic scalpel in order to achieve this goal has greatly improved the postoperative period. We have performed 920 face lifting procedures exclusively using the Harmonic scalpel from 2001 to May 2017. A retrospective chart review was performed. Mean operative time was 110minutes for facelift involving SMAS plication only, and 180minutes for facelift involving SMAS plication with the addition of submental approach for anterior platysma plasty. Return to normal social life was achieved on the 8th postoperative day for the majority of cases. The use of the Harmonic scalpel, once properly integrated in the face lifting procedure, significantly reduces postoperative ecchymosis and oedema and allows a prompt return to normal social life. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
High harmonic phase in molecular nitrogen
Energy Technology Data Exchange (ETDEWEB)
McFarland, Brian K.
2009-10-17
Electronic structure in atoms and molecules modulates the amplitude and phase of high harmonic generation (HHG). We report measurements of the high harmonic spectral amplitude and phase in N{sub 2}. The phase is measured interferometrically by beating the N{sub 2} harmonics with those of an Ar reference oscillator in a gas mixture. A rapid phase shift of 0.2{pi} is observed in the vicinity of the HHG spectral minimum, where a shift of {pi} had been presumed [J. Itatani et al., Nature 432, 867 (2004)]. We compare the phase measurements to a simulation of the HHG recombination step in N{sub 2} that is based on a simple interference model. The results of the simulation suggest that modifications beyond the simple interference model are needed to explain HHG spectra in molecules.
The harmonic oscillator and nuclear physics
Rowe, D. J.
1993-01-01
The three-dimensional harmonic oscillator plays a central role in nuclear physics. It provides the underlying structure of the independent-particle shell model and gives rise to the dynamical group structures on which models of nuclear collective motion are based. It is shown that the three-dimensional harmonic oscillator features a rich variety of coherent states, including vibrations of the monopole, dipole, and quadrupole types, and rotations of the rigid flow, vortex flow, and irrotational flow types. Nuclear collective states exhibit all of these flows. It is also shown that the coherent state representations, which have their origins in applications to the dynamical groups of the simple harmonic oscillator, can be extended to vector coherent state representations with a much wider range of applicability. As a result, coherent state theory and vector coherent state theory become powerful tools in the application of algebraic methods in physics.
Magnesium Diboride thin Films, multilayers, and coatings for SRF cavities
Energy Technology Data Exchange (ETDEWEB)
Xi, Xiaoxing [Temple Univ., Philadelphia, PA (United States)
2017-08-17
Superconducting radio frequency (SRF) cavities currently use low-temperature superconductor niobium, and the Nb SRF cavities have approached the performance levels predicted theoretically. Compared to Nb, MgB_{2} becomes superconducting at a much higher temperature and promises a better RF performance in terms of higher quality factor Q and higher acceleration capability. An MgB_{2} SRF technology can significantly reduce the operating costs of particle accelerators when these potentials are realized. This project aimed to advance the development of an MgB_{2} SRF technology. It had two main objectives: (1) materials issues of MgB_{2} thin films and multilayers related to their applications in SRF cavities; and (2) coating single-cell cavities for testing at RF frequencies. The key technical thrust of the project is the deposition of high quality clean MgB_{2} films and coatings by the hybrid physical-chemical vapor deposition (HPCVD) technique, which was developed in my group. We have achieved technical progress in each of the two areas. For the first objective, we have confirmed that MgB_{2} thin film coatings can be used to effectively enhance the vortex penetration field of an SRF cavity. A vortex is a normal region in the shape of spaghetti that threads through a superconductor. Its existence is due to an applied magnetic field that is greater than a so-called lower critical field, H_{c1}. Once a vortex enters the superconductor, its movement leads to loss. This has been shown to be the reason for an SRF cavity to break down. Thus, enhancing the magnetic field for a vortex to enter the superconductor that forms the SRF cavity has be a goal of intense research. To this end, Gurevich proposed that a coating of thin superconductor layer can impede the vortex entrance. In this project, we have done two important experiment to test this concept. One, we showed that the enhancement of H_{c1} can be
Harmonic analysis and the theory of probability
Bochner, Salomon
2005-01-01
Nineteenth-century studies of harmonic analysis were closely linked with the work of Joseph Fourier on the theory of heat and with that of P. S. Laplace on probability. During the 1920s, the Fourier transform developed into one of the most effective tools of modern probabilistic research; conversely, the demands of the probability theory stimulated further research into harmonic analysis.Mathematician Salomon Bochner wrote a pair of landmark books on the subject in the 1930s and 40s. In this volume, originally published in 1955, he adopts a more probabilistic view and emphasizes stochastic pro
Fullerenes: The attractive medium for harmonic generation
Ganeev, R. A.
2011-01-01
We review the results of systematic experimental studies of high-order harmonic generation (HHG) in C60-rich laser-produced plasma under different plasma conditions and laser parameters. The morphology of fullerene clusters before and after ablation is analyzed to define the optimal conditions of excitation of C60-containing targets. The enhancement of HHG efficiency in C60-rich plasmas by using the two-color pump technique is discussed. The conversion efficiency for the odd and even harmonics in the vicinity of surface plasmon resonance of the C60-containing plasma (40-70 nm) was estimated to be in the range of 10-4.
Music of the heavens Kepler's harmonic astronomy
Stephenson, Bruce
2014-01-01
Valued today for its development of the third law of planetary motion, Harmonice mundi (1619) was intended by Kepler to expand on ancient efforts to discern a Creator's plan for the planetary system--an arrangement thought to be based on harmonic relationships. Challenging critics who characterize Kepler's theories of harmonic astronomy as ""mystical,"" Bruce Stephenson offers the first thorough technical analysis of the music the astronomer thought the heavens made, and the logic that led him to find musical patterns in his data. In so doing, Stephenson illuminates crucial aspects of Kepler'
Honeycomb optical lattices with harmonic confinement
DEFF Research Database (Denmark)
Jacobsen, Jens Kusk Block; Nygaard, Nicolai
2010-01-01
We consider the fate of the Dirac points in the spectrum of a honeycomb optical lattice in the presence of a harmonic confining potential. By numerically solving the tight binding model, we calculate the density of states and find that the energy dependence can be understood from analytical...... arguments. In addition, we show that the density of states of the harmonically trapped lattice system can be understood by application of a local density approximation based on the density of states in the homogeneous lattice. The Dirac points are found to survive locally in the trap as evidenced...
Nonlinear harmonic generation in distributed optical klystrons
Freund, H P
2001-01-01
A distributed optical klystron has the potential for dramatically shortening the total interaction length in high-gain free-electron lasers (INP 77-59, Novosibirsk, 1977; Nucl. Instr. and Meth. A 304 (1991) 463) in comparison to a single-wiggler-segment configuration. This shortening can be even more dramatic if a nonlinear harmonic generation mechanism is used to reach the desired wavelength. An example operating at a 4.5(angstrom) fundamental and a 1.5(angstrom) harmonic is discussed.
Directory of Open Access Journals (Sweden)
M. J. Kosch
2005-07-01
Full Text Available High-power high-frequency radio waves beamed into the ionosphere cause plasma turbulence, which can accelerate electrons. These electrons collide with the F-layer neutral oxygen causing artificial optical emissions identical to natural aurora. Pumping at electron gyro-harmonic frequencies has special significance as many phenomena change their character. In particular, artificial optical emissions become strongly reduced for the third and higher gyro-harmonics. The High frequency Active Auroral Research Program (HAARP facility is unique in that it can select a frequency near the second gyro-harmonic. On 25 February 2004, HAARP was operated near the third and passed through the second gyro-harmonic for the first time in a weakening ionosphere. Two novel observations are: firstly, a strong enhancement of the artificial optical emission intensity near the second gyro-harmonic, which is opposite to higher gyro-harmonics; secondly, the optical enhancement maximum occurs for frequencies just above the second gyro-harmonic. We provide the first experimental evidence for these effects, which have been predicted theoretically. In addition, irregular optical structures were created when the pump frequency was above the ionospheric critical frequency.
Keywords. Active experiments – Auroral ionosphere – Wave-particle interactions
Probabilistic Aspects of Harmonic Emission of Large Offshore Wind Farms
DEFF Research Database (Denmark)
Jensen, Christian Flytkjær; Bak, Claus Leth; Kocewiak, Lukasz Hubert
2011-01-01
of the harmonic emission. The simulated harmonic distortion at the PCC is compared to measurement. This reveals some diffi-culties regarding harmonic load flow studies. The harmonic background distortion in the grid to where the wind farm is connected must be included in the study. Furthermore, a very detailed......In this article, a new probabilistic method of as-sessment of harmonic emission of large offshore wind farms is presented. Based on measurements from the British wind farm Burbo Banks, probability density functions are estimated for the dominating low order harmonic currents injected by a single...
Schram, Frederick R.
1997-01-01
Review of and commentary on: Body Cavities: Function and Phylogeny, edited by G. Lanzavecchia, R. Valvassori, and M.D. Candia Carnevali. Mucchi Editore/Modena, 1995, 280 pp., ISBN 88-7000-259-4. “The time has come”, the Walrus said, “To talk of many things: Of shoes – and ships – and sealing wax –
DEFF Research Database (Denmark)
2010-01-01
The present invention provides a light source (2) for light circuits on a silicon platform (3). A vertical laser cavity is formed by a gain region (101) arranged between a top mirror (4) and a bottom grating-mirror (12) in a grating region (11) in a silicon layer (10) on a substrate. A waveguide...
Directory of Open Access Journals (Sweden)
A. V. Kudryavtsev
2016-09-01
Full Text Available The transfer matrix method has been widely used to calculate wave propagation through the layered structures consisting entirely of either linear or nonlinear optical materials. In the present work, we develop the transfer matrix method for structures consisting of alternating layers of linear and nonlinear optical materials. The result is presented in a form that allows one to directly substitute the values of material constants, refractive index and absorption coefficient, into the expressions describing the second harmonic generation (SHG field. The model is applied to the calculation of second harmonic (SH field generated in nano-thin layers of transition metal dichalcogenides exfoliated on top of silicon oxide/silicon Fabry-Perot cavity. These structures are intensively studied both in view of their unique properties and perspective applications. A good agreement between experimental and numerical results can be achieved by small modification of optical constants, which may arise in an experiment due to a strong electric field of an incident focused pump laser beam. By considering the SHG effect, this paper completes the series of works describing the role of Fabry-Perot cavity in different optical effects (optical reflection, photoluminescence and Raman scattering in 2D semiconductors that is extremely important for characterization of these unique materials.
Papadogiannis, N A; Nersisyan, G; Goulielmakis, E; Rakitzis, T P; Hertz, E; Charalambidis, D; Tsakiris, G D; Witte, K
2002-09-01
By use of a transmission-grating-based Michelson interferometer, second-order interferometric as well as intensity autocorrelation traces of the third harmonic of a Ti:sapphire 50-fs laser beam produced in Ar have been measured. The duration of the harmonic is found to be that expected from lowest-order perturbation theory. At this wavelength, the performance of the interferometer with respect to pulse-front distortion and dispersion is found to be satisfactory. This result is a first step toward the use of the interferometer for the temporal characterization of higher harmonics or harmonic superposition forming attosecond pulse trains.
Seismic resonances of acoustic cavities
Schneider, F. M.; Esterhazy, S.; Perugia, I.; Bokelmann, G.
2016-12-01
The goal of an On-Site Inspection (OSI) is to clarify at a possible testsite whether a member state of the Comprehensive nuclear Test Ban Treaty (CTBT)has violated its rules by conducting a underground nuclear test. Compared toatmospheric and underwater tests underground nuclear explosions are the mostdifficult to detect.One primary structural target for the field team during an OSI is the detectionof an underground cavity, created by underground nuclear explosions. Theapplication of seismic-resonances of the cavity for its detection has beenproposed in the CTBT by mentioning "resonance seismometry" as possibletechnique during OSIs. We modeled the interaction of a seismic wave-field withan underground cavity by a sphere filled with an acoustic medium surrounded byan elastic full space. For this setting the solution of the seismic wave-fieldcan be computed analytically. Using this approach the appearance of acousticresonances can be predicted in the theoretical calculations. Resonance peaksappear in the spectrum derived for the elastic domain surrounding the acousticcavity, which scale in width with the density of the acoustic medium. For lowdensities in the acoustic medium as for an gas-filled cavity, the spectralpeaks become very narrow and therefore hard to resolve. The resonancefrequencies, however can be correlated to the discrete set of eigenmodes of theacoustic cavity and can thus be predicted if the dimension of the cavity isknown. Origin of the resonance peaks are internal reverberations of wavescoupling in the acoustic domain and causing an echoing signal that couples outto the elastic domain again. In the gas-filled case the amplitudes in timedomain are very low.Beside theoretical considerations we seek to find real data examples fromsimilar settings. As example we analyze a 3D active seismic data set fromFelsőpetény, Hungary that has been conducted between 2012 and 2014 on behalf ofthe CTBTO. In the subsurface of this area a former clay mine is
Numerical and Experimental Study of the Q Factor of High-Q Micropillar Cavities
DEFF Research Database (Denmark)
Gregersen, Niels; Reitzenstein, S.; Kistner, C.
2010-01-01
Micropillar cavities are potential candidates for high-efficiency single-photon sources and are testbeds for cavity quantum electrodynamics experiments. In both applications a high quality (Q) factor is desired. It was recently shown that the Q of high-Q semiconductor micropillar cavities exhibit...... to the effective reflectivity of the fundamental mode arising from coupling to scattering channels involving higher-order cavity modes and propagating Bloch modes in the distributed Bragg reflectors (DBRs). We show how these weak contributions lead to strong variations of the Q factor, and we relate the average...
Harmonic Interaction Analysis in Grid-connected Converter using Harmonic State Space (HSS) Modeling
DEFF Research Database (Denmark)
Kwon, Jun Bum; Wang, Xiongfei; Blaabjerg, Frede
2017-01-01
. Furthermore, a harmonic matrix of the grid-connected converter is developed to analyze the harmonic interaction at the steady-state behavior. Besides, the frequency-domain results are compared with time-domain simulation results by using HSS modeling to verify the theoretical analysis. Experimental results...... research about the harmonic interaction. However, it is found that the Linear Time Invariant (LTI) based model analysis makes it difficult to analyze these phenomena because of the time-varying properties of the power electronic based systems. This paper investigates grid-connected converter by using...
Operation of the 56 MHz superconducting RF cavity in RHIC during run 14
Energy Technology Data Exchange (ETDEWEB)
Wu, Q. [Brookhaven National Lab. (BNL), Upton, NY (United States); Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Blaskiewicz, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Hayes, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Mernick, K. [Brookhaven National Lab. (BNL), Upton, NY (United States); Severino, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Smith, K. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zaltsman, A. [Brookhaven National Lab. (BNL), Upton, NY (United States)
2015-09-11
A 56 MHz superconducting RF cavity was designed and installed in the Relativistic Heavy Ion Collider (RHIC). It is the first superconducting quarter wave resonator (QWR) operating in a high-energy storage ring. We discuss herein the cavity operation with Au+Au collisions, and with asymmetrical Au+He3 collisions. The cavity is a storage cavity, meaning that it becomes active only at the energy of experiment, after the acceleration cycle is completed. With the cavity at 300 kV, an improvement in luminosity was detected from direct measurements, and the bunch length has been reduced. The uniqueness of the QWR demands an innovative design of the higher order mode dampers with high-pass filters, and a distinctive fundamental mode damper that enables the cavity to be bypassed during the acceleration stage.
Transient Beam Loading Effects in Gas-filled RF Cavities for a Muon Collider
Energy Technology Data Exchange (ETDEWEB)
Chung, M. [Fermilab; Tollestrup, A. [Fermilab; Yonehara, K. [Fermilab; Freemire, B. [IIT, Chicago
2013-06-01
A gas-filled RF cavity can be an effective solution for the development of a compact muon ionization cooling channel. One possible problem expected in this type of cavity is the dissipation of significant RF power through the beam-induced plasmas accumulated inside the cavity (plasma loading). In addition, for the higher muon beam intensity, the effects of the beam itself on the cavity accelerating mode are non-negligible (beam loading). These beam- cavity interactions induce a transient phase which may be very harmful to the beam quality [1]. In this study, we estimate the transient voltage in a gas-filled RF cavity with both the plasma and conventional beam loading and discuss their compensation methods.
Pumarola Suñé, J; Espias Gómez, A; Canalda Sahli, C
1989-01-01
We have compared the microbiological activity of the following cavity liners: Life, Dycal II, Calcipulpe, Pure calcium hydroxide and Cavitec; against five different bacterial strains: Veillonella parvula, Bacteroides fragilis, Peptococcus s.p., Staphylococcus aureus, and Streptococcus beta hemolytic: The results demonstrate the higher antimicrobial activity of the manufactured cavity liners with calcium hydroxide base in comparison with the pure calcium hydroxide.
Intra-cavity decomposition of a dual-directional laser beam
CSIR Research Space (South Africa)
Naidoo, Darryl
2011-01-01
Full Text Available A method of decomposing a dual-directional laser beam into a forward propagating field and a backward propagating field for an apertured plano-concave cavity is presented. An intra-cavity aperture is a simple method of laser beam shaping as higher...
Multimode nanobeam cavities for nonlinear optics: high quality resonances separated by an octave.
Buckley, Sonia; Radulaski, Marina; Zhang, Jingyuan Linda; Petykiewicz, Jan; Biermann, Klaus; Vučković, Jelena
2014-11-03
We demonstrate the design, fabrication and characterization of nanobeam cavities with multiple higher order modes. Designs with two high Q modes with frequency separations of an octave are introduced, and we fabricate such cavities exhibiting resonances with wavelength separations of up to 740 nm.
Nasal cavity of the farmed african catfish Clarias gariepinus ...
African Journals Online (AJOL)
Higher magnification revealed that these filaments were lined by olfactory neuroepithelium containing tall ciliated simple columnar cells, supporting cells occasional mucous cells. The roof of the cavity was lined by bi-stratified cuboidal caudally to low cuboidal cells rostrally. This histology suggests an organ actively involved ...
Factors associated with lip and oral cavity cancer.
Ribeiro, Isabella Lima Arrais; de Medeiros, Júlia Julliêta; Rodrigues, Larycia Vicente; Valença, Ana Maria Gondim; Lima Neto, Eufrásio de Andrade
2015-01-01
This study aimed to identify factors associated with the occurrence of primary cancer of the lip and oral cavity regions compared to other types of head and neck cancers according to demographic, socioeconomic data and lifestyle, in Brazil, from 2000 to 2011. A study was conducted using Hospital Cancer Records (Instituto Nacional do Câncer), from 2000 to 2011, totaling 23,153 cases. Data were analyzed by binary logistic regression (response category: primary cancers located in the lip and oral cavity; comparison category; other types of primary cancer in the head and neck, which does not affect the lip and oral cavity) at a significance level α = 5%. The study showed factors associated with higher incidence of cancer in the lip and oral cavity: being of advanced age (OR = 1.16), not having a family history of cancer (OR = 2.38), alcohol consumption (OR = 1.17); former tobacco use (OR = 1.51) or current tobacco use (OR = 1.65); having a previous diagnosis of cancer without treatment (OR =1.66). Being female (OR = 0.92), having completed basic (OR = 0.71) and higher (OR = 0.46) education and having previous diagnosis of cancer with treatment (OR = 0.74) constituted factors associated with lower prevalence of cancer of the lip and oral cavity. Age, absence of family history of cancer, smoking habits and alcohol consumption, and previous diagnosis of cancer without treatment were associated with a higher incidence of cancer of the lip and oral cavity.
Factors associated with lip and oral cavity cancer
Directory of Open Access Journals (Sweden)
Isabella Lima Arrais Ribeiro
2015-09-01
Full Text Available PURPOSE: This study aimed to identify factors associated with the occurrence of primary cancer of the lip and oral cavity regions compared to other types of head and neck cancers according to demographic, socioeconomic data and lifestyle, in Brazil, from 2000 to 2011.METHODS: A study was conducted using Hospital Cancer Records (Instituto Nacional do Câncer, from 2000 to 2011, totaling 23,153 cases. Data were analyzed by binary logistic regression (response category: primary cancers located in the lip and oral cavity; comparison category; other types of primary cancer in the head and neck, which does not affect the lip and oral cavity at a significance level α = 5%.RESULTS: The study showed factors associated with higher incidence of cancer in the lip and oral cavity: being of advanced age (OR = 1.16, not having a family history of cancer (OR = 2.38, alcohol consumption (OR = 1.17; former tobacco use (OR = 1.51 or current tobacco use (OR = 1.65; having a previous diagnosis of cancer without treatment (OR =1.66. Being female (OR = 0.92, having completed basic (OR = 0.71 and higher (OR = 0.46 education and having previous diagnosis of cancer with treatment (OR = 0.74 constituted factors associated with lower prevalence of cancer of the lip and oral cavity.CONCLUSION: Age, absence of family history of cancer, smoking habits and alcohol consumption, and previous diagnosis of cancer without treatment were associated with a higher incidence of cancer of the lip and oral cavity.
Directory of Open Access Journals (Sweden)
Mohamed Sabry Mohamed
2017-03-01
Full Text Available We report on nonlinear frequency conversion from the telecom range via second harmonic generation (SHG and third harmonic generation (THG in suspended gallium nitride slab photonic crystal (PhC cavities on silicon, under continuous-wave resonant excitation. Optimized two-dimensional PhC cavities with augmented far-field coupling have been characterized with quality factors as high as 4.4 × 104, approaching the computed theoretical values. The strong enhancement in light confinement has enabled efficient SHG, achieving a normalized conversion efficiency of 2.4 × 10−3 W−1, as well as simultaneous THG. SHG emission power of up to 0.74 nW has been detected without saturation. The results herein validate the suitability of gallium nitride for integrated nonlinear optical processing.
Mohamed, Mohamed Sabry; Carlin, Jean-François; Minkov, Momchil; Gerace, Dario; Savona, Vincenzo; Grandjean, Nicolas; Galli, Matteo; Houdré, Romuald
2016-01-01
We report on nonlinear frequency conversion from the telecom range via second harmonic generation (SHG) and third harmonic generation (THG) in suspended gallium nitride slab photonic crystal (PhC) cavities on silicon, under continuous-wave resonant excitation. Optimized two-dimensional PhC cavities with augmented far-field coupling have been characterized with quality factors as high as 4.4$\\times10^{4}$, approaching the computed theoretical values. The strong enhancement in light confinement has enabled efficient SHG, achieving normalized conversion efficiency of 2.4$\\times10^{-3}$ $W^{-1}$, as well as simultaneous THG. SHG emission power of up to 0.74 nW has been detected without saturation. The results herein validate the suitability of gallium nitride for integrated nonlinear optical processing.
Godiksen, R. H.; Aunsborg, T. S.; Kristensen, P. K.; Pedersen, K.
2017-11-01
Unintentionally doped and semi-insulating Fe-doped GaN crystals grown by hydride vapor phase epitaxy have been investigated with two-photon photoluminescence and second-harmonic generation spectroscopy to reveal doping effects on the nonlinear optical properties and thus indirectly on crystal properties. Like for linear luminescence, it is found that Fe doping strongly reduces nonlinear luminescence. Recording of second-harmonic generation spectra in transmission probing bulk properties shows no significant difference between doped and un-doped crystals. Reflected second-harmonic generation probing 50-100 nm at the surface, on the other hand, shows significantly lower signal from the doped sample. Secondary ion mass spectroscopy shows that the Fe concentration is higher at the surface than in the bulk of the doped crystal. It is suggested that this causes higher defect density and degraded order in the surface region, thus reducing the second-harmonic signal.
Hyperbolic Harmonic Mapping for Surface Registration.
Shi, Rui; Zeng, Wei; Su, Zhengyu; Jiang, Jian; Damasio, Hanna; Lu, Zhonglin; Wang, Yalin; Yau, Shing-Tung; Gu, Xianfeng
2017-05-01
Automatic computation of surface correspondence via harmonic map is an active research field in computer vision, computer graphics and computational geometry. It may help document and understand physical and biological phenomena and also has broad applications in biometrics, medical imaging and motion capture industries. Although numerous studies have been devoted to harmonic map research, limited progress has been made to compute a diffeomorphic harmonic map on general topology surfaces with landmark constraints. This work conquers this problem by changing the Riemannian metric on the target surface to a hyperbolic metric so that the harmonic mapping is guaranteed to be a diffeomorphism under landmark constraints. The computational algorithms are based on Ricci flow and nonlinear heat diffusion methods. The approach is general and robust. We employ our algorithm to study the constrained surface registration problem which applies to both computer vision and medical imaging applications. Experimental results demonstrate that, by changing the Riemannian metric, the registrations are always diffeomorphic and achieve relatively high performance when evaluated with some popular surface registration evaluation standards.
SOME THEOREMS ON HARMONIC RENEWAL MEASURES
STAM, AJ
1991-01-01
The harmonic renewal measure nu for the random walk S(n) is defined by nu(A) = SIGMA-n = 1 infinity n-1 P(S(n) is-an-element-of A). The paper gives weak asymptotic relations as x --> infinity for nu([0,x]) under weak conditions.
Psychoacoustic Approaches for Harmonic Music Mixing
Directory of Open Access Journals (Sweden)
Roman B. Gebhardt
2016-05-01
Full Text Available The practice of harmonic mixing is a technique used by DJs for the beat-synchronous and harmonic alignment of two or more pieces of music. In this paper, we present a new harmonic mixing method based on psychoacoustic principles. Unlike existing commercial DJ-mixing software, which determines compatible matches between songs via key estimation and harmonic relationships in the circle of fifths, our approach is built around the measurement of musical consonance. Given two tracks, we first extract a set of partials using a sinusoidal model and average this information over sixteenth note temporal frames. By scaling the partials of one track over ±6 semitones (in 1/8th semitone steps, we determine the pitch-shift that maximizes the consonance of the resulting mix. For this, we measure the consonance between all combinations of dyads within each frame according to psychoacoustic models of roughness and pitch commonality. To evaluate our method, we conducted a listening test where short musical excerpts were mixed together under different pitch shifts and rated according to consonance and pleasantness. Results demonstrate that sensory roughness computed from a small number of partials in each of the musical audio signals constitutes a reliable indicator to yield maximum perceptual consonance and pleasantness ratings by musically-trained listeners.
ACCOUNTING HARMONIZATION AND HISTORICAL COST ACCOUNTING
Directory of Open Access Journals (Sweden)
Valentin Gabriel CRISTEA
2017-05-01
Full Text Available There is a huge interest in accounting harmonization and historical costs accounting, in what they offer us. In this article, different valuation models are discussed. Although one notices the movement from historical cost accounting to fair value accounting, each one has its advantages.
Modelling the harmonized tertiary Institutions Salary Structure ...
African Journals Online (AJOL)
This paper analyses the Harmonized Tertiary Institution Salary Structure (HATISS IV) used in Nigeria. The irregularities in the structure are highlighted. A model that assumes a polynomial trend for the zero step salary, and exponential trend for the incremental rates, is suggested for the regularization of the structure.
Information cloning of harmonic oscillator coherent states
Indian Academy of Sciences (India)
Abstract. We show that in the case of unknown harmonic oscillator coherent states it is possible to achieve what we call perfect information cloning. By this we mean that it is still possible to make arbitrary number of copies of a state which has exactly the same information content as the original unknown coherent state.
Hyperchaotic circuit with damped harmonic oscillators
DEFF Research Database (Denmark)
Lindberg, Erik; Murali, K.; Tamasevicius, A.
2001-01-01
A simple fourth-order hyperchaotic circuit with damped harmonic oscillators is described. ANP3 and PSpice simulations including an eigenvalue study of the linearized Jacobian are presented together with a hardware implementation. The circuit contains two inductors with series resistance, two ideal...
Information cloning of harmonic oscillator coherent states
Indian Academy of Sciences (India)
We show that in the case of unknown harmonic oscillator coherent statesit is possible to achieve what we call perfect information cloning. By this we mean that it is still possible to make arbitrary number of copies of a state which has exactly the same information content as the original unknown coherent state. By making use ...
Collective excitations of harmonically trapped ideal gases
Van Schaeybroeck, B.; Lazarides, A.
2009-01-01
We theoretically study the collective excitations of an ideal gas confined in an isotropic harmonic trap. We give an exact solution to the Boltzmann-Vlasov equation; as expected for a single-component system, the associated mode frequencies are integer multiples of the trapping frequency. We show
Optical second harmonic generation from Wannier excitons
DEFF Research Database (Denmark)
Pedersen, Thomas Garm; Cornean, Horia
2007-01-01
, a simplified three-band Wannier exciton model of cubic semiconductors is applied and a closed form expression for the complex second harmonic response function including broadening is derived. Our calculated spectra are found to be in excellent agreement with the measured response near the band edge...
Harmonic Scalpel versus Monopolar Electrocauterization in Cholecystectomy.
Liao, Guanqun; Wen, Shunqian; Xie, Xueyi; Wu, Qing
2016-01-01
Laparoscopic cholecystectomy (LC) using surgical electrocautery is considered to be the gold standard procedure for the treatment of uncomplicated cholecystitis and cholelithiasis. The objective of the current study was to evaluate the effectiveness and safety of the Harmonic scalpel, an advanced laparoscopic technique associated with less thermal damage in LC, when compared to electrocautery. From October 2010 through June 2013, a total of 198 patients were randomly allocated to LC with a Harmonic scalpel (experimental group, 117 patients) or conventional monopolar electrocautery (control group, 81 patients). The main outcome measures were operative time, blood loss, conversion to laparotomy, postoperative hospital stay, post-LC pain, and cost effectiveness. The 2 groups were comparable with respect to baseline patient characteristics. When compared to conventional monopolar electrocautery, there were no significant reductions in the operative time, bleeding, frequency of conversion to laparotomy, and duration of postoperative recovery with the Harmonic scalpel (P > .05 for all). Laparoscopic cholecystectomy using conventional monopolar electrocautery is as effective and safe as that with the Harmonic scalpel, for treating uncomplicated cholecystitis and cholelithiasis.
Virial expansion coefficients in the harmonic approximation
DEFF Research Database (Denmark)
R. Armstrong, J.; Zinner, Nikolaj Thomas; V. Fedorov, D.
2012-01-01
The virial expansion method is applied within a harmonic approximation to an interacting N-body system of identical fermions. We compute the canonical partition functions for two and three particles to get the two lowest orders in the expansion. The energy spectrum is carefully interpolated...
Shedding new light on Gaussian harmonic analysis
Teuwen, J.J.B.
2016-01-01
This dissertation consists out of two rather disjoint parts. One part concerns some results on Gaussian harmonic analysis and the other on an optimization problem in optics. In the first part we study the Ornstein–Uhlenbeck process with respect to the Gaussian measure. We focus on two areas. One is
Sobolev spaces associated to the harmonic oscillator
Indian Academy of Sciences (India)
2Departamento de Matemática, Facultad de Ciencias, Universidad Autónoma de. Madrid, Spain. E-mail: bbongio@math.unl.edu.ar; joseluis.torrea@uam.es. MS received 27 September 2005. Abstract. We define the Hermite–Sobolev spaces naturally associated to the harmonic oscillator H = − + |x|2. Structural properties ...
Thirring model partition functions and harmonic differentials
Freedman, D. Z.; Pilch, K.
1988-10-01
The partition function of the Thirring model on a Riemann surface is calculated using the representation of the model as a fermion interacting with an auxiliary vector potential. The Hodge decomposition of the potential is used and the integral over the harmonic forms is shown to reproduce exactly the soliton sum in the bosonic version of the theory.
Stages of Lip and Oral Cavity Cancer
... Head and Neck Cancer Patient Hypopharyngeal Cancer Treatment Laryngeal Cancer Treatment Lip & Oral Cavity Treatment Metastatic Squamous Neck ... Oropharyngeal Cancer Screening Health Professional Hypopharyngeal Cancer Treatment Laryngeal Cancer Treatment Lip & Oral Cavity Treatment Metastatic Squamous Neck ...
Correlations of electromagnetic fields in chaotic cavities
Eckhardt, B; Kühl, T; Stöckmann, H J
1999-01-01
We consider the fluctuations of electromagnetic fields in chaotic microwave cavities. We calculate the transversal and longitudinal correlation function based on a random wave assumption and compare the predictions with measurements on two- and three-dimensional microwave cavities.
Nonequilibrium dressing in a cavity with a movable reflecting mirror
Armata, Federico; Kim, M. S.; Butera, Salvatore; Rizzuto, Lucia; Passante, Roberto
2017-08-01
We consider a movable mirror coupled to a one-dimensional massless scalar field in a cavity. Both the field and the mirror's mechanical degrees of freedom are described quantum mechanically, and they can interact with each other via the radiation pressure operator. We investigate the dynamical evolution of mirror and field starting from a nonequilibrium initial state, and their local interaction which brings the system to a stationary configuration for long times. This allows us to study the time-dependent dressing process of the movable mirror interacting with the field, and its dynamics leading to a local equilibrium dressed configuration. Also, in order to explore the effect of the radiation pressure on both sides of the movable mirror, we generalize the effective field-mirror Hamiltonian and previous results to the case of two cavities sharing the same mobile boundary. This leads us to address, in the appropriate limit, the dynamical dressing problem of a single mobile wall, bounded by a harmonic potential, in the vacuum space.
3D multiphysics modeling of superconducting cavities with a massively parallel simulation suite
Directory of Open Access Journals (Sweden)
Oleksiy Kononenko
2017-10-01
Full Text Available Radiofrequency cavities based on superconducting technology are widely used in particle accelerators for various applications. The cavities usually have high quality factors and hence narrow bandwidths, so the field stability is sensitive to detuning from the Lorentz force and external loads, including vibrations and helium pressure variations. If not properly controlled, the detuning can result in a serious performance degradation of a superconducting accelerator, so an understanding of the underlying detuning mechanisms can be very helpful. Recent advances in the simulation suite ace3p have enabled realistic multiphysics characterization of such complex accelerator systems on supercomputers. In this paper, we present the new capabilities in ace3p for large-scale 3D multiphysics modeling of superconducting cavities, in particular, a parallel eigensolver for determining mechanical resonances, a parallel harmonic response solver to calculate the response of a cavity to external vibrations, and a numerical procedure to decompose mechanical loads, such as from the Lorentz force or piezoactuators, into the corresponding mechanical modes. These capabilities have been used to do an extensive rf-mechanical analysis of dressed TESLA-type superconducting cavities. The simulation results and their implications for the operational stability of the Linac Coherent Light Source-II are discussed.
Technical notes. Spherical harmonics approximations of neutron transport
Energy Technology Data Exchange (ETDEWEB)
Demeny, A.; Dede, K.M.; Erdei, K.
1976-12-01
A double-range spherical harmonics approximation obtained by expanding the angular flux separately in the two regions combined with the conventional single-range spherical harmonics is found to give superior description of neutron transport.
Voltage harmonic elimination with RLC based interface smoothing filter
Chandrasekaran, K.; Ramachandaramurthy, V. K.
2015-04-01
A method is proposed for designing a Dynamic Voltage Restorer (DVR) with RLC interface smoothing filter. The RLC filter connected between the IGBT based Voltage Source Inverter (VSI) is attempted to eliminate voltage harmonics in the busbar voltage and switching harmonics from VSI by producing a PWM controlled harmonic voltage. In this method, the DVR or series active filter produces PWM voltage that cancels the existing harmonic voltage due to any harmonic voltage source. The proposed method is valid for any distorted busbar voltage. The operating VSI handles no active power but only harmonic power. The DVR is able to suppress the lower order switching harmonics generated by the IGBT based VSI. Good dynamic and transient results obtained. The Total Harmonic Distortion (THD) is minimized to zero at the sensitive load end. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of RLC filter. Simulated results are presented.
Hail, Procrustes! Harmonized accounting standards as a Procrustean bed
Stecher, J.; Suijs, J.P.M.
2012-01-01
This article finds that the use of a harmonized accounting standard, such as the International Financial Reporting Standards, increases the information available to markets only if institutional differences across countries using the harmonized standard are insignificant. In all other cases,
Sequence Domain Harmonic Modeling of Type-IV Wind Turbines
DEFF Research Database (Denmark)
Guest, Emerson; Jensen, Kim Høj; Rasmussen, Tonny Wederberg
2017-01-01
A sequence domain (SD) harmonic model of a gridconnected voltage-source converter is developed for decoupling converter generated voltage harmonics from voltage harmonics in the external grid. The modeling procedure includes a derivation of the baseband frequency response for regular......-sampled pulsewidth modulation and an analysis of converter generated voltage harmonics due to compensated dead-time. The decoupling capabilities of the proposed the SD harmonic model are verified through a power quality (PQ) assessment of a 3MW Type-IV wind turbine. The assessment shows that the magnitude and phase...... of low-order odd converter generated voltage harmonics are dependent on the converter operating point and the phase of the fundamental component of converter current respectively. The SD harmonic model can be used to make PQ assessments of Type-IV wind turbines or incorporated into harmonic load flows...
An economical wireless cavity-nest viewer
Daniel P. Huebner; Sarah R. Hurteau
2007-01-01
Inspection of cavity nests and nest boxes is often required during studies of cavity-nesting birds, and fiberscopes and pole-mounted video cameras are sometimes used for such inspection. However, the cost of these systems may be prohibitive for some potential users. We describe a user-built, wireless cavity viewer that can be used to access cavities as high as 15 m and...
Prototype storage cavity for LEP accelerating RF
CERN PhotoLab
1980-01-01
The principle of an RF storage cavity was demonstrated with this prototype, working at 500 MHz. Ian Wilso seems to hold it in his hands. The storage cavities had 4 portholes, 1 each for: RF feed; tuning; connection to the accelerating cavity; vacuum pump. The final storage cavities were larger, to suit the lower LEP accelerating frequency of 352.2 MHz. See also 8002294, 8006510X, 8109346, 8407619X, and Annual Report 1980, p.115.
Cavity QED experiments with ion Coulomb crystals
DEFF Research Database (Denmark)
Herskind, Peter Fønss; Dantan, Aurélien; Marler, Joan
2009-01-01
Cavity QED experimental results demonstrating collective strong coupling between ensembles of atomic ions cooled into Coulomb crystals and optical cavity fields have been achieved. Collective Zeeman coherence times of milliseconds have furthermore been obtained.......Cavity QED experimental results demonstrating collective strong coupling between ensembles of atomic ions cooled into Coulomb crystals and optical cavity fields have been achieved. Collective Zeeman coherence times of milliseconds have furthermore been obtained....
Li, Kexuan; Guoyu, Heyang; Tian, Jinrong; Song, Yanrong
2016-11-01
The high energy noise-like pulses (NLPs) were experimentally investigated in a passively mode-locked erbium-doped fiber laser with a long ring cavity by using nonlinear polarization rotation technique. Large net normal group-velocity dispersion of the cavity is estimated as high as 6.46 ps2, which is beneficial to formation of high-energy pulses. With the total pump power of 970 mW (the pump powers of forward pump and backward pump are set at the value of 455 mW and 515 mW, respectively), a stable ultrahigh energy rectangular-shape pulse emission with the pulse duration of 35 ns was observed. The energy of square packet with a fundamental repetition rate of 141.6 kHz is as high as 840 nJ. The signal-to-noise is higher than 60 dB in RF spectrum. The feature of NLPs is confirmed by the coherent spike of autocorrelation trace. When the pump power is beyond 970 mW, the mode locking operation with fundamental repetition rate cannot be achieved despite of the large range variation of polarization controller (PC) settings. However, the forthorder harmonic mode locking can be observed, the square pulse packet duration still remains at ˜ 35 ns. The experimental results demonstrated that the ultrahigh energy NLPs is only realized at the condition of special physical parameters and it is restricted by the number and intensity of ultra short pulses within the envelope to some extent.
Cavity Enhanced Velocity Modulation Spectroscopy
Siller, Brian; Mills, Andrew; Porambo, Michael; McCall, Benjamin
2010-11-01
Over the past several decades, velocity modulation spectroscopy has been used to study dozens of molecular ions of astronomical importance. This technique has been so productive because it provides the advantage of ion-neutral discrimination, which is critically important when interfering neutral molecules are many orders of magnitude more abundant, and when combined with heterodyne techniques, its sensitivity can approach the shot noise limit. Traditionally, velocity modulation experiments have utilized unidirectional multipass White cells to achieve up to about 8 passes through a positive column discharge cell. But by positioning the cell within an optical cavity, it is possible to obtain an effective path length orders of magnitude longer than was previously possible. We have demonstrated this novel technique using a Ti:Sapp laser in the near-IR to observe rovibronic transitions of N2+. By demodulating at twice the modulation frequency, 2nd derivative-like lineshapes are observed for ions that are velocity-modulated, while Gaussian lineshapes are observed for excited neutral that are concentration-modulated. The signals for N2+ and N2+* have been observed to be 78° out of phase with one another, so ion-neutral discrimination is retained. And due to the laser power enhancement and geometry of the optical cavity, Doppler-free saturation spectroscopy is now possible. Observed Lamb dips have widths of 50 MHz, and when combined with calibration by an optical frequency comb, this allows for determination of line centers to within 1 MHz. In our original demonstration of this technique, our sensitivity was limited by noise in the laser-cavity lock. Since then, we have integrated Noise Immune Cavity Enhanced Optical Heterodyne Molecular Spectroscopy (NICE-OHMS) by adding sidebands to the laser at an exact multiple of the cavity free spectral range, and demodulating at the sideband frequency before sending the signal to a lock-in amplifier for demodulating at twice the
Neural Representation of Harmonic Complex Tones in Primary Auditory Cortex of the Awake Monkey
Micheyl, Christophe; Steinschneider, Mitchell
2013-01-01
Many natural sounds are periodic and consist of frequencies (harmonics) that are integer multiples of a common fundamental frequency (F0). Such harmonic complex tones (HCTs) evoke a pitch corresponding to their F0, which plays a key role in the perception of speech and music. “Pitch-selective” neurons have been identified in non-primary auditory cortex of marmoset monkeys. Noninvasive studies point to a putative “pitch center” located in a homologous cortical region in humans. It remains unclear whether there is sufficient spectral and temporal information available at the level of primary auditory cortex (A1) to enable reliable pitch extraction in non-primary auditory cortex. Here we evaluated multiunit responses to HCTs in A1 of awake macaques using a stimulus design employed in auditory nerve studies of pitch encoding. The F0 of the HCTs was varied in small increments, such that harmonics of the HCTs fell either on the peak or on the sides of the neuronal pure tone tuning functions. Resultant response-amplitude-versus-harmonic-number functions (“rate-place profiles”) displayed a periodic pattern reflecting the neuronal representation of individual HCT harmonics. Consistent with psychoacoustic findings in humans, lower harmonics were better resolved in rate-place profiles than higher harmonics. Lower F0s were also temporally represented by neuronal phase-locking to the periodic waveform of the HCTs. Findings indicate that population responses in A1 contain sufficient spectral and temporal information for extracting the pitch of HCTs by neurons in downstream cortical areas that receive their input from A1. PMID:23785145
A novel speech processing algorithm based on harmonicity cues in cochlear implant
Wang, Jian; Chen, Yousheng; Zhang, Zongping; Chen, Yan; Zhang, Weifeng
2017-08-01
This paper proposed a novel speech processing algorithm in cochlear implant, which used harmonicity cues to enhance tonal information in Mandarin Chinese speech recognition. The input speech was filtered by a 4-channel band-pass filter bank. The frequency ranges for the four bands were: 300-621, 621-1285, 1285-2657, and 2657-5499 Hz. In each pass band, temporal envelope and periodicity cues (TEPCs) below 400 Hz were extracted by full wave rectification and low-pass filtering. The TEPCs were modulated by a sinusoidal carrier, the frequency of which was fundamental frequency (F0) and its harmonics most close to the center frequency of each band. Signals from each band were combined together to obtain an output speech. Mandarin tone, word, and sentence recognition in quiet listening conditions were tested for the extensively used continuous interleaved sampling (CIS) strategy and the novel F0-harmonic algorithm. Results found that the F0-harmonic algorithm performed consistently better than CIS strategy in Mandarin tone, word, and sentence recognition. In addition, sentence recognition rate was higher than word recognition rate, as a result of contextual information in the sentence. Moreover, tone 3 and 4 performed better than tone 1 and tone 2, due to the easily identified features of the former. In conclusion, the F0-harmonic algorithm could enhance tonal information in cochlear implant speech processing due to the use of harmonicity cues, thereby improving Mandarin tone, word, and sentence recognition. Further study will focus on the test of the F0-harmonic algorithm in noisy listening conditions.
Diagram of a LEP superconducting cavity
1991-01-01
This diagram gives a schematic representation of the superconducting radio-frequency cavities at LEP. Liquid helium is used to cool the cavity to 4.5 degrees above absolute zero so that very high electric fields can be produced, increasing the operating energy of the accelerator. Superconducting cavities were used only in the LEP-2 phase of the accelerator, from 1996 to 2000.
The evolution of harmonic Indian musical drums: A mathematical perspective
Gaudet, Samuel; Gauthier, Claude; Léger, Sophie
2006-03-01
We explain using mathematics how harmonic musical drums were discovered by Indian artisans and musicians more than 2000 years ago. To this end, we introduce a harmonic error function which measures the quality of the harmonic relationship and degeneracy of the first modes of vibration of a centrally symmetric loaded membrane. We explain that although the tabla configuration found by the ancient Indians is the most natural one, other configurations exist and some are harmonically superior to the classical one.
Gu, Xiaodong; Nakahama, Masanori; Matsutani, Akihiro; Ahmed, Moustafa; Bakry, Ahmed; Koyama, Fumio
2015-08-01
An 850-nm-band transverse-coupled-cavity vertical-cavity surface-emitting laser (VCSEL) is demonstrated for the first time, showing a 3 dB modulation bandwidth of over 30 GHz, which is the record for VCSELs. The transverse-coupled cavity is formed by making lithography-defined, battledore-shaped mesas. The coupling strength can be increased by reducing the absorption loss in a passive feedback cavity. Further increase in the coupling strength and/or mode selection via current injection into the feedback cavity shows the possibility of overclocking the device by optical equalization. Large-signal measurement shows eye-opening at 40 Gb/s. After the coupled mode is stabilized, higher bitrate modulation can be expected.
Calibrating the sensing-coil radius by feed-down from a harmonic reference
Arpaia, Pasquale; Koster, Oliver; Russenschuck, Stephan; Severino, Giordana
2015-01-01
a harmonic field error of higher order is present in the calibration magnet. This also yields a calibration whena sextupole magnet is used, for example, when an insitu calibration is required. The proposed calibration method has been validated by simulations with the
Physics design of APT linac with normal conducting rf cavities
Energy Technology Data Exchange (ETDEWEB)
Nath, S.; Billen, J.H.; Stovall, J.E.; Takeda, Harunori; Young, L.M.
1996-09-01
The accelerator based production of tritium calls for a high-power, cw proton linac. Previous designs for such a linac use a radiofrequency quadrupole (RFQ), followed by a drift-tube linac (DTL) to an intermediate energy and a coupled-cavity linc (CCL) to the final energy. The Los Alamos design uses a high-energy (6.7 MeV) RFQ followed by the newly developed coupled-cavity drift-tube linac (CCDTL) and a CCL. This design accommodates external electromagnetic quadrupole lenses which provide a strong uniform focusing lattice from the end of the RFQ to the end of the CCL. The cell lengths in linacs of traditional design are typically graded as a function of particle velocity. By making groups of cells symmetric in both the CCDTL and CCL, the cavity design as well as mechanical design and fabrication is simplified without compromising the performance. At higher energies, there are some advantages of using superconducting rf cavities. Currently, such schemes are under vigorous study. This paper describes the linac design based on normal conducting cavities and presents simulation results.
Energy Technology Data Exchange (ETDEWEB)
Kroll, N.
2005-04-08
In this paper the authors describe the determination of the properties of the above referenced cavities with particular emphasis on the damping of the higher order modes (HOM). Because mode frequency spectra were determined for a large number of shorted waveguide lengths, rather complete analyses are possible. Phase frequency plots have proved to be an invaluable aid in sorting out overlapping resonances and separating cavity resonances from waveguide resonances. Algorithms for the determination of the parameters of several resonances simultaneously have been developed. Determinations of Q from multiresonance analyses are compared to those from single resonance analyses, and the changes are typically found to be small.
A Many-Atom Cavity QED System with Homogeneous Atom-Cavity Coupling
Lee, Jongmin; Teper, Igor; Hosten, Onur; Kasevich, Mark A
2013-01-01
We demonstrate a many-atom-cavity system with a high-finesse dual-wavelength standing wave cavity in which all participating rubidium atoms are nearly identically coupled to a 780-nm cavity mode. This homogeneous coupling is enforced by a one-dimensional optical lattice formed by the field of a 1560-nm cavity mode.
Richard N. Conner; Daniel Saenz; D. Craig Rudolph; Richard R. Schaefer
2002-01-01
Rates of cavity excavation by Red-cockaded Woodpeckers (Picoides borealis) were examined from 1983 to 1999 on the Angelina National Forest in east Texas. We compared the rare of natural cavity excavation between 1983 and 1990 (before artificial cavities were available) with the rate of cavity excavation between 1992 and 1993, a period when...