High harmonic terahertz confocal gyrotron with nonuniform electron beam
Energy Technology Data Exchange (ETDEWEB)
Fu, Wenjie; Guan, Xiaotong; Yan, Yang [THz Research Center, School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)
2016-01-15
The harmonic confocal gyrotron with nonuniform electron beam is proposed in this paper in order to develop compact and high power terahertz radiation source. A 0.56 THz third harmonic confocal gyrotron with a dual arc section nonuniform electron beam has been designed and investigated. The studies show that confocal cavity has extremely low mode density, and has great advantage to operate at high harmonic. Nonuniform electron beam is an approach to improve output power and interaction efficiency of confocal gyrotron. A dual arc beam magnetron injection gun for designed confocal gyrotron has been developed and presented in this paper.
Khutoryan, Eduard M.; Idehara, Toshitaka; Melnikova, Maria M.; Ryskin, Nikita M.; Dumbrajs, Olgierd
2017-07-01
Effect of delayed reflection on operation of a second-harmonic terahertz (THz)-band gyrotron is studied. Theoretical analyses, numerical calculations, and experimental observations for the 0.394-THz Fukui University (FU) and continuous wave (CW) IIB gyrotron are presented. The reflections decrease starting current and expand frequency tunability range owing to excitation of high-order axial modes. They also increase frequency stability, i.e., reduce frequency change due to variation of the magnetic field. In addition, the reflections strongly affect mode competition causing suppress of the second-harmonic mode by the fundamental one and vice versa or, in the case of cooperative mode interaction, mutual power increase.
Design of a second cyclotron harmonic gyrotron oscillator with photonic band-gap cavity
Energy Technology Data Exchange (ETDEWEB)
Liu Gaofeng; Chen Xiaoan; Tang Changjian, E-mail: angelchen765@163.com [College of Physical Science and Technology of Sichuan University, Chengdu 610065 (China)
2011-07-27
A photonic band-gap cavity (PBGC) gyrotron with a frequency of about 98 GHz is designed. Theoretical analyses and numerical calculations are made for the PBGC operating at fundamental and second cyclotron harmonic with a TE{sub 34} waveguide mode to demonstrate the beam-wave interaction. The results show that mode competition is successfully eliminated in the PBGC using mode selectivity and choosing the appropriate operating parameters. As a result, the second harmonic PBGC gyrotron operating at TE{sub 34} mode achieves a higher output efficiency than that of the fundamental. It is also demonstrated that, in the case of the chosen parameters for TE{sub 34} waveguide mode, the use of PBG structure in the second harmonic gyrotron brings about not only a lower operating B-field but also a weaker mode competition. The results show that the high-order electromagnetic mode can be developed to interact with the high cyclotron harmonic using the selectivity of the PBGC, which gives an encouraging outlook for the development of high-harmonic gyrotrons.
A 0.33-THz second-harmonic frequency-tunable gyrotron
Zheng-Di, Li; Chao-Hai, Du; Xiang-Bo, Qi; Li, Luo; Pu-Kun, Liu
2016-02-01
Dynamics of the axial mode transition process in a 0.33-THz second-harmonic gyrotron is investigated to reveal the physical mechanism of realizing broadband frequency tuning in an open cavity circuit. A new interaction mechanism about propagating waves, featured by wave competition and wave cooperation, is presented and provides a new insight into the beam-wave interaction. The two different features revealed in the two different operation regions of low-order axial modes (LOAMs) and high-order axial modes (HOAMs) respectively determine the characteristic of the overall performance of the device essentially. The device performance is obtained by the simulation based on the time-domain nonlinear theory and shows that using a 12-kV/150-mA electron beam and TE-3,4 mode, the second harmonic gyrotron can generate terahertz radiations with frequency-tuning ranges of about 0.85 GHz and 0.60 GHz via magnetic field and beam voltage tuning, respectively. Additionally, some non-stationary phenomena in the mode startup process are also analyzed. The investigation in this paper presents guidance for future developing high-performance frequency-tunable gyrotrons toward terahertz applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 61471007, 61531002, 61522101, and 11275206) and the Seeding Grant for Medicine and Information Science of Peking University, China (Grant No. 2014-MI-01).
A double-beam magnetron-injection gun for third-harmonic continuous wave 1-THz gyrotron
Energy Technology Data Exchange (ETDEWEB)
Glyavin, M. [Faculty of Radiophysics, N. I. Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod 603950 (Russian Federation); Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS), Nizhny Novgorod 603600 (Russian Federation); Research Center for Development of Far Infrared Region, University of Fukui (FIR FU), Fukui-shi 910-8507 (Japan); Manuilov, V. [Faculty of Radiophysics, N. I. Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod 603950 (Russian Federation); Research Center for Development of Far Infrared Region, University of Fukui (FIR FU), Fukui-shi 910-8507 (Japan); Idehara, T. [Research Center for Development of Far Infrared Region, University of Fukui (FIR FU), Fukui-shi 910-8507 (Japan)
2013-12-15
The concept of a continuous wave 1-kW/1-THz gyrotron operated at the third cyclotron harmonic of the transverse electric TE{sub 9,7} operating mode has been developed. To suppress the mode competition effects in a terahertz gyrotron, we propose a scheme with two generating helical electron beams (HEBs) formed in a double-beam triode magnetron-injection gun (MIG), where both emitters of the electron beams are located on a common cathode of the conventional MIG. An optimal geometry of the MIG electrodes is found. It is shown that in a proposed scheme two HEBs having close pitch factors and a moderate velocity spread can be formed. This makes them suitable for high-efficiency single-mode generation in the high frequency gyrotron at high harmonic.
Glyavin, M. Yu.; Zavolskiy, N. A.; Sedov, A. S.; Nusinovich, G. S.
2013-03-01
For a long time, the gyrotrons were primarily developed for electron cyclotron heating and current drive of plasmas in controlled fusion reactors where a multi-megawatt, quasi-continuous millimeter-wave power is required. In addition to this important application, there are other applications (and their number increases with time) which do not require a very high power level, but such issues as the ability to operate at low voltages and have compact devices are very important. For example, gyrotrons are of interest for a dynamic nuclear polarization, which improves the sensitivity of the nuclear magnetic resonance spectroscopy. In this paper, some issues important for operation of gyrotrons driven by low-voltage electron beams are analyzed. An emphasis is made on the efficiency of low-voltage gyrotron operation at the fundamental and higher cyclotron harmonics. These efficiencies calculated with the account for ohmic losses were, first, determined in the framework of the generalized gyrotron theory based on the cold-cavity approximation. Then, more accurate, self-consistent calculations for the fundamental and second harmonic low-voltage sub-THz gyrotron designs were carried out. Results of these calculations are presented and discussed. It is shown that operation of the fundamental and second harmonic gyrotrons with noticeable efficiencies is possible even at voltages as low as 5-10 kV. Even the third harmonic gyrotrons can operate at voltages about 15 kV, albeit with rather low efficiency (1%-2% in the submillimeter wavelength region).
Study on the Before Cavity Interaction in a Second Harmonic Gyrotron Using 3D CFDTD PIC Simulations
Lin, M. C.; Illy, S.; Thumm, M.; Jelonnek, J.
2016-10-01
A computational study on before cavity interaction (BCI) in a 28 GHz second harmonic (SH) gryotron for industrial applications has been performed using a 3-D conformal finite-difference time-domain (CFDTD) particle-in-cell (PIC) method. On the contrary to the after cavity interaction (ACI), i.e. beam wave interaction in the non-linear uptaper after the cavity, which has been widely investigated, the BCI, i.e. beam wave interaction in the non-linear downtaper before the cavity connected to the beam tunnel with an entrance, is less noticed and discussed. Usually the BCI might be considered easy to be eliminated. However, this is not always the case. As the SH gyrotron had been designed for SH TE12 mode operation, the first harmonic (FH) plays the main competition. In the 3-D CFDTD PIC simulations, a port boundary has been employed for the gyro-beam entrance of the gyrotron cavity instead of a metallic short one which is not reflecting a realistic situation as an FH backward wave oscillation (BWO) is competing with the desired SH generation. A numerical instability has been found and identified as a failure of the entrance port boundary caused by an evanescent wave or mode conversion. This indicates the entrance and downtaper are not fully cut-off for some oscillations. A further study shows that the undesired oscillation is the FH TE11 BWO mode concentrated around the beam tunnel entrance and downtaper. A mitigation strategy has been found to suppress this undesired BCI and avoid possible damage to the gun region.
Yeh, Y. S.; Kao, W. J.; Li, L. J.; Guo, Y. W.
2017-01-01
The harmonic multiplying operation in a gyrotron traveling-wave amplifier (gyro-TWA) permits magnetic field reduction and frequency multiplication. This study presents a comparative analysis of fourth-harmonic multiplying gyro-TWAs with three schemes of operation. An improved mode-selective circuit using circular waveguides with various radii provides the rejection points within the range of operating frequencies to suppress the competing modes of gyro-TWAs. The simulated results reveal that gyro-TWAs are the most susceptible to the fundamental-harmonic TE11 competing mode, regardless of the operating scheme, and that the mode-selective circuit can provide an attenuation of more than 20 dB to suppress the competing modes. The amplification of the waves in a gyro-TWA depends on the lengths of the sections, and the simulated results show that the gain increases for all schemes, as the length of the lossy section or the length of the copper section increases. All schemes exhibit nearly the same saturated output powers and bandwidths; however, the saturated gain of the scheme at a high frequency multiplication ratio is less than that of the scheme at a low frequency multiplication ratio. Extensive numerical calculations of power and gain scaling are conducted for all schemes.
W波段三次谐波回旋管实验研究%Experimental study on W-band third-harmonic gyrotron
Institute of Scientific and Technical Information of China (English)
孙迪敏; 胡鹏; 马国武; 陈洪斌; 孟凡宝; 陈怀璧
2013-01-01
It is the first time that the W-band,third harmonic gyrotron radiation is observed in China.The operation mode of the third harmonic gyrotron is TE61.The magnetic field is 1.2 T and the frequency is 94.86 GHz.When beam current changes from 1.6 A to 4.4 A,keeping the anode voltage 45 kV,the third harmonic radiation can be observed.The largest output power is 4.9 kW,and the efficiency is about 3％.%国内首次成功进行W波段三次谐波回旋管实验.回旋管工作模式为TE61,磁场1.2T,采用拍频法测定工作频率为94.86 GHz.电子束电压为45 kV时,电流1.6～4.4A范围内都观测到了三次谐波振荡信号.采用焦热计测定最大输出功率4.9 kW,效率约3％.
三次谐波光子带隙谐振腔回旋管%Third-Harmonic of Photonic-Band-Gap Cavity Gyrotron
Institute of Scientific and Technical Information of China (English)
夏玉玺; 唐昌建
2011-01-01
Effective coupling of interaction between high-order electromagnetic mode gyrotron oscillator and high-effective electron cyclotron mode is achieved through the analysis of mode selection function of the photonic band gap cavity（PBGC）.After band characteristics of the PBGC are investigated,TE34-mode is set as working mode and the mode competition is suppressed successfully.The concept of equivalent radius of PBGC gyrotron is established,self-consistent nonlinear theory and related computer simulation program are completed.Studies have shown that TE34-mode can interact with third electronic cyclotron harmonics effectively,the coupling frequency of which is 130.5GHz,and meanwhile it reduces the required magnetic field greatly.The parameters are optimized when many physical factors are taken into account,and a third-harmonic PBGC gyrotron oscillator with voltage 430KV,current 35A,output power 1.75MW and interaction efficiency 11.5% are obtained consequently.%分析了光子晶体谐振腔（PBGC）的模式选择功能,实现PBGC回旋管振荡器高阶电磁模与高次电子回旋模的有效耦合。通过对PBGC禁带特性的分析,定出了工作模式TE34模,并成功抑制了模式竞争。文中建立了PBGC回旋管的等效半径的概念,完成了自洽非线性理论和相关的计算机数值模拟程序。研究发现TE34模能有效地与电子的3次回旋谐波相互作用,其耦合频率为130.5GHz,并极大地降低了对工作磁场的要求。在考虑诸多物理因素影响的情况下,对该3次谐波PBGC回旋管振荡器进行了参数优化研究,得到了参数为：电压430kV、
Cascaded third harmonic generation in hybrid graphene-semiconductor waveguides
Smirnova, Daria A
2015-01-01
We study cascaded harmonic generation of hybrid surface plasmons in integrated planar waveguides composed of a graphene layer and a doped-semiconductor slab. We derive a comprehensive model of cascaded third harmonic generation through phase-matched nonlinear interaction of fundamental, second harmonic and third harmonic plasmonic modes supported by the structure. We show that hybrid graphene-semiconductor waveguides can simultaneously phase-match these three interacting harmonics, increasing the total third-harmonic output by a factor of 5 compared to the non-cascaded regime.
A 0.52THz third harmonic little-orbit gyrotron%小回旋三次谐波0.52THz回旋管
Institute of Scientific and Technical Information of China (English)
袁学松; 马春燕; 韩煜; 鄢扬
2012-01-01
A third harmonic little-orbit gyrotron oscillator is investigated theoretically in order to develop high power and efficiency terahertz (THz) radiation sources. Mode competition with different electron-beam parameters have been investigated in a 0.52 THz third harmonic TE37 mode gyrotron oscillator, which can generate 3.7kW of RF power at resonant magnetic field 6.98T. In addition, a high magnetic compression ratio magnetron injection gun (MIG) with 65 kV/2. 5 A has been developed. PIC simulation results show that the velocity ratio of electron beam is 1.24, the average beam radius in the cavity is 0.35 mm. The spread of perpendicular and parallel velocities are 6.1% and 6.6% , respectively.%为了发展大功率高效率太赫兹辐射源,对小回旋电子注激励三次谐波太赫兹电子回旋脉塞进行了研究,分析了不同参数情况下的模式竞争.研究结果表明,采用近轴小回旋电子注能够实现三次谐波单模振荡.在此基础上设计了一只0.52 THz、TE37模三次谐波回旋管,数值计算表明,该回旋管在工作磁场为6.98 T下输出功率可以达到3.7 kW.对产生近轴小回旋电子注的高磁压缩比磁控注入式电子光学系统进行的粒子模拟研究结果表明,该电子枪能够产生满足实验要求的65 kV/2.5 A,横纵速度比为1.24,引导中心半径0.35 mm的小回旋电子注,其纵向速度离散6.6％,横向速度离散6.1％.
Design cusp electron gun for of 0.6 THz 3rd-harmonic large orbit gyrotron%0.6THz三次谐波大回旋电子枪设计
Institute of Scientific and Technical Information of China (English)
马春燕; 胡强; 袁学松; 韩煜; 鄢扬
2012-01-01
Large orbit axis-encircling electron beams can provide improved coupling and mode selectivity in a high harmonic terahertz gyrotron. For developing a 0. 6 THz 3rd-harmonic large orbit gyrotron, a cusp gun with a beam voltage of 55 kV and a beam current of 1 A has been designed based on a comparatively simple Pierce-type electron gun and cusp magnetic field. The optimized result shows that the velocity ratio, axial velocity spread and transverse velocity spread are 1. 53, 7. 10% and 3. 39% , respectively.%基于会切磁场的理论模型,采用粒子模拟软件对0.6 THz三次谐波的太赫兹回旋管所需的大回旋电子光学系统进行研究.文中通过大量的模拟计算,分析讨论了不同参数对电子注的横向速度离散、纵向速度离散及横纵速度比的影响,优化了电子光学系统的性能参量,得到符合设计要求且具有工程实际应用的电子枪,该电子枪能够产生55 kV,1A,横向速度离散为3.39％、纵向速度离散为7.10％、横纵速度比为1.53的大回旋电子注.
Application of Hybrid Functions for Solving Duffing-Harmonic Oscillator
Directory of Open Access Journals (Sweden)
Mohammad Heydari
2014-01-01
Full Text Available A numerical method for finding the solution of Duffing-harmonic oscillator is proposed. The approach is based on hybrid functions approximation. The properties of hybrid functions that consist of block-pulse and Chebyshev cardinal functions are discussed. The associated operational matrices of integration and product are then utilized to reduce the solution of a strongly nonlinear oscillator to the solution of a system of algebraic equations. The method is easy to implement and computationally very attractive. The results are compared with the exact solution and results from several recently published methods, and the comparisons showed proper accuracy of this method.
Second harmonic generation spectroscopy on hybrid plasmonic/dielectric nanoantennas
Institute of Scientific and Technical Information of China (English)
Heiko Linnenbank; Yevgen Grynko; Jens F(o)rstner; Stefan Linden
2016-01-01
Plasmonic nanoantennas provide unprecedented opportunities to concentrate light fields in subwavelength-sized volumes.By placing a nonlinear dielectric nanoparticle in such a hot spot,one can hope to take advantage of beth the field enhancement provided by nanoantennas and the large,nonlinear optical susceptibility of dielectric nanoparticles.To test this concept,we combine gold gap nanoantennas with second-order,nonlinear zinc sulfide nanoparticles,and perform second harmonic generation (SHG) spectroscopy onthe combined hybrid dielectric/plasmonic nanoantennas as well as on the individual constituents.We find that SHG from the bare gold nanoantennas,even though it should be forbidden due to symmetry reasons,is several orders of magnitude larger than that of the bare zinc sulfide nanoparticles.Even stronger second harmonic signals are generated by the hybrid dielectric/plasmonic nanoantennas.Control experiments with nanoantennas containing linear lanthanum fluoride nanoparticles reveal;however,that the increased SHG efficiency of the hybrid dielectric/plasmonic nanoantennas does not depend on the nonlinear optical susceptibility of the dielectric nanoparticles but is an effect of the modification of the dielectric environment.The combination of a hybrid dielectric/plasmonic nanoantenna,which is only resonant for the incoming pump light field,with a second nanoantenna,which is resonant for the generated second harmonic light,allows for a further increase in the efficiency of SHG.As the second nanoantenna mediates the coupling of the second harmonic light to the far field,this double-resonant approach also provides us with control over the polarization of the generated light.
Hybrid genetic algorithm approach for selective harmonic control
Energy Technology Data Exchange (ETDEWEB)
Dahidah, Mohamed S.A. [Faculty of Engineering, Multimedia University, 63100, Jalan Multimedia-Cyberjaya, Selangor (Malaysia); Agelidis, Vassilios G. [School of Electrical and Information Engineering, The University of Sydney, NSW (Australia); Rao, Machavaram V. [Faculty of Engineering and Technology, Multimedia University, 75450, Jalan Ayer Keroh Lama-Melaka (Malaysia)
2008-02-15
The paper presents an optimal solution for a selective harmonic elimination pulse width modulated (SHE-PWM) technique suitable for a high power inverter used in constant frequency utility applications. The main challenge of solving the associated non-linear equations, which are transcendental in nature and, therefore, have multiple solutions, is the convergence, and therefore, an initial point selected considerably close to the exact solution is required. The paper discusses an efficient hybrid real coded genetic algorithm (HRCGA) that reduces significantly the computational burden, resulting in fast convergence. An objective function describing a measure of the effectiveness of eliminating selected orders of harmonics while controlling the fundamental, namely a weighted total harmonic distortion (WTHD) is derived, and a comparison of different operating points is reported. It is observed that the method was able to find the optimal solution for a modulation index that is higher than unity. The theoretical considerations reported in this paper are verified through simulation and experimentally on a low power laboratory prototype. (author)
Enhanced Harmonic Up-Conversion Using a Hybrid HGHG-EEHG Scheme
Energy Technology Data Exchange (ETDEWEB)
Marksteiner, Quinn R. [Los Alamos National Laboratory; Bishofberger, Kip A. [Los Alamos National Laboratory; Carlsten, Bruce E. [Los Alamos National Laboratory; Freund, Henry P. [Los Alamos National Laboratory; Yampolsky, Nikolai A. [Los Alamos National Laboratory
2012-04-30
We introduce a novel harmonic generation scheme which can be used, for a given desired harmonic, to achieve higher bunching factors, weaker chicanes, and/or less final energy spread than can be achieved using Echo-Enabled Harmonic Generation. This scheme only requires a single laser with relatively low power, and is a hybrid of High-Gain Harmonic Generation and EEHG. We present a design of this scheme applied to the Next Generation Light Source (NGLS).
Hartwell, G. J.; Knowlton, S. F.; Ennis, D. A.; Maurer, D. A.; Bigelow, T.
2016-10-01
The Compact Toroidal Hybrid (CTH) is an l = 2 , m = 5 torsatron/tokamak hybrid (R0 = 0.75 m, ap 0.2 m, and | B | supplement the existing 15 kW klystron system operating at the fundamental frequency; the latter will be used to initially generate the plasma. Ray-tracing calculations that guide the selection of launching position, antenna focal length, and beam-steering characteristics of the ECRH have been performed with the TRAVIS code [ 1 ] . The calculated absorption is up to 95.7% for vertically propagating rays, however, the absorption is more sensitive to magnetic field variations than for a side launch where the field gradient is tokamak-like. The design of the waveguide path and components for the top-launch scenario will be presented. This work is supported by U.S. Department of Energy Grant No. DE-FG02-00ER54610.
Soviet Development of Gyrotrons
1986-05-01
Relationship Type of Device Remarks V, - Vc, anomalous Doppler Capable of 100 percent efficiency, CRM but more cumbersome than Cheren- kov devices V...authors; and discusses inlividual Soviet reseaLc- groups, the basic organizational units responAiLle for the CRM and gyrotron research and development. The...maintained a cCnEistEnt iecord of significant achievements; it has managed to overcome the systenic yeaxness of the Soviet R&C systeg in teimg atle to
Refinement of Enhanced Speech Using Hybrid-Median Filter and Harmonic Regeneration Approach
Institute of Scientific and Technical Information of China (English)
Ching-Ta Lu; Jun-Hong Shen; Kun-Fu Tseng; Chih-Tsung Chen
2014-01-01
This study proposes a post-processor to improve the harmonic structure of a vowel in an enhanced speech, enabling the speech quality to be improved. Initially, a speech enhancement algorithm is employed to reduce the background noise for a noisy speech. Hence the enhanced speech is post-processed by a hybrid-median filter to reduce the musical effect of residual noise. Since the harmonic spectra are impacted by background noise and a speech enhancement process, the quality of a vowel is deteriorated. A harmonic regenerated method is developed to improve the quality of post-processed speech. Experimental results show that the proposed method can improve the quality of post-processed speech by adequately regenerating harmonic spectra.
Gyrotron oscillators for fusion heating
Energy Technology Data Exchange (ETDEWEB)
Jory, H.; Evans, S.; Felch, K.; Shively, J.; Spang, S.
1982-01-01
Recent experiments have been performed to determine the ultimate power capability of a 28 GHz 200 kW CW gyrotron design. A power output of 342 kW CW was measured in these tests with an efficiency of 37%. Progress in the development of 60 GHz 200 kW pulsed and CW gyrotrons is discussed. An output of 200 kW with 100 msec pulse length has been achieved with the pulsed design.
Harmonic estimation in a power system using a novel hybrid Least Squares-Adaline algorithm
Energy Technology Data Exchange (ETDEWEB)
Joorabian, M.; Mortazavi, S.S.; Khayyami, A.A. [Electrical Engineering Department, Shahid Chamran University, Ahwaz, 61355 (Iran)
2009-01-15
Nowadays many algorithms have been proposed for harmonic estimation in a power system. Most of them deal with this estimation as a totally nonlinear problem. Consequently, these methods either converge slowly, like GA algorithm [U. Qidwai, M. Bettayeb, GA based nonlinear harmonic estimation, IEEE Trans. Power Delivery (December) 1998], or need accurate parameter adjustment to track dynamic and abrupt changes of harmonics amplitudes, like adaptive Kalman filter (KF) [Steven Liu, An adaptive Kalman filter for dynamic estimation of harmonic signals, in: 8th International Conference On Harmonics and Quality of Power, ICHQP'98, Athens, Greece, October 14-16, 1998]. In this paper a novel hybrid approach, based on the decomposition of the problem into a linear and a nonlinear problem, is proposed. A linear estimator, i.e., Least Squares (LS), which is simple, fast and does not need any parameter tuning to follow harmonics amplitude changes, is used for amplitude estimation and an adaptive linear combiner called 'Adaline', which is very fast and very simple is used to estimate phases of harmonics. An improvement in convergence and processing time is achieved using this algorithm. Moreover, better performance in online tracking of dynamic and abrupt changes of signals is the result of applying this method. (author)
Widely tunable second-harmonic generation in a chalcogenide-tellurite hybrid optical fiber.
Cheng, Tonglei; Gao, Weiqing; Kawashima, Hiroyasu; Deng, Dinghuan; Liao, Meisong; Matsumoto, Morio; Misumi, Takashi; Suzuki, Takenobu; Ohishi, Yasutake
2014-04-01
When a chalcogenide-tellurite hybrid optical fiber with a high refractive index difference Δn=0.24 is pumped by an optical parametric oscillator with a pump wavelength from 1700 to 3000 nm, widely tunable second-harmonic generation (SHG) from 850 to 1502 nm is obtained. The observation of SHG is primarily due to the surface nonlinearity polarization at the core-cladding interface and the second-harmonic signal remains stable at the maximal level throughout the laser pulse irradiation.
Plane gyroklinotron at first and third harmonics of cyclotron frequency
Energy Technology Data Exchange (ETDEWEB)
Kurayev, A.A.; Lukashonok, D.V.; Sinitsyn, A.K., E-mail: kurayev@bsuir.by, E-mail: timka86@gmail.com [Belarusian State University of Informatics and Radioelectronics, Minsk (Belarus)
2011-07-01
The results of gyroklinotron's parameters optimization for efficiency at f = 100 GHz with interaction on first and third harmonics of the cyclotron frequency are presented. The predicted electron gyroklinotron's efficiency reaches 70% on first harmonic and 40% on third harmonic. This is more than in usual gyrotron. Besides in contrast to usual gyrotron the width electron beam on radius of guiding centers of electron orbits in gyroklinotron may considerable exceed working wave length {lambda}. This allows to use in it considerable more power of electron beams EB then in usual gyrotron. (author)
On the origin of third harmonic light from hybrid metal-dielectric nanoantennas
de Ceglia, Domenico; Vincenti, Maria Antonietta; Scalora, Michael
2016-11-01
Near field amplification of electric fields magnifies the nonlinear optical signals generated in the metal volume of plasmonic nanoantennas, as well as in the surrounding media. We investigate the third harmonic light emitted by a hybrid nanoantenna composed of two metallic rods separated by a small gap filled with a dielectric. Despite the large cubic nonlinear susceptibility of metals, the presence of a hot spot in the antenna’s gap may easily transform weaker dielectric nonlinearities into the dominant source of third harmonic light. This has led to diverse and sometimes opposite interpretations of the nature of the nonlinear response, which are further complicated by the limited knowledge of the intrinsic nonlinear susceptibilities of the constituent materials. Here, a quantitative description of third harmonic generation is provided as a function of the ratio between the dielectric and the metal nonlinear susceptibilities in a hybrid metal-dielectric nanoantenna. We find a spectral discriminator that allows us to determine the origin of third harmonic light unambiguously.
Plasmon assisted enhanced second-harmonic generation in single hybrid Au/ZnS nanowires
Jassim, Nadia M.; Wang, Kai; Han, Xiaobo; Long, Hua; Wang, Bing; Lu, Peixiang
2017-02-01
We demonstrate the enhanced second-harmonic generation (SHG) in single ZnS nanowires (NWs) attached with gold nanoparticles (Au NPs). The hybrid Au/ZnS NWs with different densities of the attached Au NPs were prepared by a simple solution impregnation method. By comparing with bare ZnS NWs, ∼1.3, ∼6.6, ∼7 and ∼2 times enhancement of SH intensity was achieved in the hybrid Au/ZnS NWs with low, moderate, high and ultrahigh densities of the attached Au NPs, respectively. The enhanced SHG in the hybrid Au/ZnS NWs is attributed to the strong local-fields from the Au cluster under the near-resonant condition, which is supported by the related dark-field scattering spectra. This hybrid Au/ZnS NWs provide a simple platform for enhancing nonlinear optical responses, which have potential applications in nano-probing and nano-sensing.
Operation and control of high power Gyrotrons for ECRH systems in SST-1 and Aditya
Energy Technology Data Exchange (ETDEWEB)
Shukla, B.K., E-mail: shukla@ipr.res.in; Bora, D.; Jha, R.; Patel, Jatin; Patel, Harshida; Babu, Rajan; Dhorajiya, Pragnesh; Dalakoti, Shefali; Purohit, Dharmesh
2016-11-15
Highlights: • Operation and control of high power Gyrotrons. • Data acquisition and control (DAQ) for Gyrotron system. • Ignitron based crowbar protection. • VME and PXI based systems. - Abstract: The Electron Cyclotron Resonance Heating (ECRH) system is an important heating system for the reliable start-up of tokamak. The 42 GHz and 82.6 GHz ECRH systems are used in tokamaks SST-1 and Aditya to carry out ECRH related experiments. The Gyrotrons are high power microwave tubes used as a source for ECRH systems. The Gyrotron is a delicate microwave tube, which deliver megawatt level power at very high voltage ∼40–50 kV with the current requirement ∼10 A–50 A. The Gyrotrons are associated with the subsystems like: High voltage power supplies (Beam voltage and anode voltage), dedicated crowbar system, magnet, filament and ion pump power supplies, cooling, interlocks and a dedicated data acquisition & control (DAC) system. There are two levels of interlocks used for the protection of Gyrotron: fast interlocks (arcing, beam over current, dI/dt, anode voltage and anode over current etc.) operate within 10 μs and slow interlocks (cooling, filament, silence of Gyrotron, ion pump and magnet currents) operate within 100 ms. Two Gyrotrons (42 GHz/500 kW/500 ms and 82.6 GHz/200 kW/1000 s) have been commissioned on dummy load for full parameters. The 42 GHz ECRH system has been integrated with SST-1 & Aditya tokamak and various experiments have been carried out related to ECRH assisted breakdown and start-up of tokamak at fundamental and second harmonic. These Gyrotrons are operated with VME based data acquisition and control (DAC) system. The DAC system is capable to acquire 64 digital and 32 analog signals. The system is used to monitor & acquire the data and also used for slow interlocks for the protection of Gyrotron. The data acquired from the system are stored online on VME system and after the shot stored in a file in binary format. The MDSPlus, a set of
Shunt hybrid active power filter for harmonic mitigation: A practical design approach
Indian Academy of Sciences (India)
Unnikrishnan A K; Chandira Sekaran E; Subhash Joshi T G; Manju A S; Aby Joseph
2015-06-01
The increasing importance of Power Quality problems has been responsible for several improvements in Active Power Filter (APF) typologies in the last decade. The increased cost and switching losses make a pure shunt APF economically impractical for high power applications. In higher power levels shunt Hybrid Active Power Filter (HAPF) has been reported to be a useful approach to eliminate current harmonics caused by nonlinear loads. This paper presents a control strategy and design criteria for transformer-less shunt HAPF with special attention to the integration of series passive filter. The paper also compares the performance improvement of passive harmonic filter when modified as shunt HAPF. Experimental results obtained verify the viability and effectiveness of the proposed design criteria and control algorithm.
Energy Technology Data Exchange (ETDEWEB)
Leißner, Till [NanoSYD, Mads Clausen Institute, University of Southern Denmark, Alsion 2, 6400 Sønderborg (Denmark); Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense (Denmark); Kostiučenko, Oksana; Rubahn, Horst-Günter; Fiutowski, Jacek, E-mail: fiutowski@mci.sdu.dk [NanoSYD, Mads Clausen Institute, University of Southern Denmark, Alsion 2, 6400 Sønderborg (Denmark); Brewer, Jonathan R. [Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense (Denmark)
2015-12-21
In this letter we show that the optical response of organic nanofibers, grown from functionalized para-quaterphenylene molecules, can be controlled by forming organic-plasmonic hybrid systems. The interaction between nanofibers and supporting regular arrays of nanostructures leads to a strongly enhanced second harmonic response. At the same time, the fluorescence lifetime of the nanofibers is reduced from 0.32 ns for unstructured gold films to 0.22 ns for gold nanosquare arrays, demonstrating efficient organic–plasmonic interaction. To study the origin of these effects, we applied two-photon laser scanning microscopy and fluorescence lifetime imaging microscopy. These findings provide an effective approach for plasmon-enhanced second-harmonic generation at the nanoscale, which is attractive for nanophotonic circuitry.
Directory of Open Access Journals (Sweden)
Santosh Kumar Singh
2017-06-01
Full Text Available This paper presents a new hybrid method based on Gravity Search Algorithm (GSA and Recursive Least Square (RLS, known as GSA-RLS, to solve the harmonic estimation problems in the case of time varying power signals in presence of different noises. GSA is based on the Newton’s law of gravity and mass interactions. In the proposed method, the searcher agents are a collection of masses that interact with each other using Newton’s laws of gravity and motion. The basic GSA algorithm strategy is combined with RLS algorithm sequentially in an adaptive way to update the unknown parameters (weights of the harmonic signal. Simulation and practical validation are made with the experimentation of the proposed algorithm with real time data obtained from a heavy paper industry. A comparative performance of the proposed algorithm is evaluated with other recently reported algorithms like, Differential Evolution (DE, Particle Swarm Optimization (PSO, Bacteria Foraging Optimization (BFO, Fuzzy-BFO (F-BFO hybridized with Least Square (LS and BFO hybridized with RLS algorithm, which reveals that the proposed GSA-RLS algorithm is the best in terms of accuracy, convergence and computational time.
Gyrotron development at KIT: FULGOR test facility and gyrotron concepts for DEMO
Energy Technology Data Exchange (ETDEWEB)
Schmid, M., E-mail: martin.schmid@kit.edu [Institute for Pulsed Power and Microwave Technology (IHM), Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Franck, J.; Kalaria, P.; Avramidis, K.A.; Gantenbein, G.; Illy, S. [Institute for Pulsed Power and Microwave Technology (IHM), Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Jelonnek, J. [Institute for Pulsed Power and Microwave Technology (IHM), Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Institute of High Frequency Techniques and Electronics (IHE), Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Pagonakis, I. Gr.; Rzesnicki, T. [Institute for Pulsed Power and Microwave Technology (IHM), Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Thumm, M. [Institute for Pulsed Power and Microwave Technology (IHM), Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Institute of High Frequency Techniques and Electronics (IHE), Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany)
2015-10-15
Highlights: • Substantial extension of the KIT gyrotron test facility FULGOR has started. • FULGOR will be able to test gyrotrons with continuous RF output power up to 4 MW. • Design of 240 GHz gyrotrons for efficient electron cyclotron current drive is progressing. • Output power of 240 GHz gyrotrons with conventional cavity up to 830 kW, with coaxial cavity up to 2 MW is feasible. • Multi-frequency operation with gyrotrons is also possible (170–267 GHz). - Abstract: At the Karlsruhe Institute of Technology (KIT), theoretical and experimental foundations for the development of future gyrotrons for fusion applications are being laid down. This includes the construction of the new Fusion Long Pulse Gyrotron Laboratory (FULGOR) test facility as well as physical design studies towards DEMO-compatible gyrotrons. Initially FULGOR will comprise of a 10 MW CW power supply, a 5 MW water cooling system (upgradeable to 10 MW), a superconducting 10 T magnet, one or two 2 MW ECRH test loads and a new control and data acquisition system for all these elements. The test facility will then be equipped to test the conventional 1 MW or coaxial 2 MW gyrotrons for DEMO, currently under design, as well as possible upgraded gyrotrons for W7-X and ITER. The design of the new high voltage DC power supply (HVDCPS) is flexible enough to handle gyrotrons with 4 MW CW output power (conceivably up to 170 GHz), but also test gyrotrons with higher frequencies (>250 GHz) which, due to physical limitations in the gyrotron design, will require less power but have more stringent demands on voltage stability.
Excitation of ion-cyclotron harmonic waves in lower-hybrid heating
Villalon, E.
1981-06-01
The parametric excitation of ion-cyclotron waves by a lower-hybrid pump field is studied in the assumption that the magnitude of the pump is constant. The spatial amplification factor is given as a function of the wavenumber mismatch as produced by the plasma density gradient, and of the linear damping rates of the excited ion-cyclotron and sideband waves. The analysis is applied to plasma edge parameters relevant to the JFT2 heating experiment. It is found that ion-cyclotron harmonic modes are excited depending on pump frequency and plasma density. These modes are shown to have finite damping rates. The parallel refractive indices n1z of the excited sideband fields are found to be always larger than that of the driven pump field. Transition to quasi-mode decay occurs either by decreasing the pump frequency or by increasing the applied RF-power.
Hybrid simplified spherical harmonics with diffusion equation for light propagation in tissues
Chen, Xueli; Sun, Fangfang; Yang, Defu; Ren, Shenghan; Zhang, Qian; Liang, Jimin
2015-08-01
Aiming at the limitations of the simplified spherical harmonics approximation (SPN) and diffusion equation (DE) in describing the light propagation in tissues, a hybrid simplified spherical harmonics with diffusion equation (HSDE) based diffuse light transport model is proposed. In the HSDE model, the living body is first segmented into several major organs, and then the organs are divided into high scattering tissues and other tissues. DE and SPN are employed to describe the light propagation in these two kinds of tissues respectively, which are finally coupled using the established boundary coupling condition. The HSDE model makes full use of the advantages of SPN and DE, and abandons their disadvantages, so that it can provide a perfect balance between accuracy and computation time. Using the finite element method, the HSDE is solved for light flux density map on body surface. The accuracy and efficiency of the HSDE are validated with both regular geometries and digital mouse model based simulations. Corresponding results reveal that a comparable accuracy and much less computation time are achieved compared with the SPN model as well as a much better accuracy compared with the DE one.
New hybrid active power filter for harmonic current suppression and reactive power compensation
Biricik, Samet; Cemal Ozerdem, Ozgur; Redif, Soydan; Sezai Dincer, Mustafa
2016-08-01
In the case of undistorted and balanced grid voltages, low ratio shunt active power filters (APFs) can give unity power factors and achieve current harmonic cancellation. However, this is not possible when source voltages are distorted and unbalanced. In this study, the cost-effective hybrid active power filter (HAPF) topology for satisfying the requirements of harmonic current suppression and non-active power compensation for industry is presented. An effective strategy is developed to observe the effect of the placement of power capacitors and LC filters with the shunt APF. A new method for alleviating the negative effects of a nonideal grid voltage is proposed that uses a self-tuning filter algorithm with instantaneous reactive power theory. The real-time control of the studied system was achieved with a field-programmable gate array (FPGA) architecture, which was developed using the OPAL-RT system. The performance result of the proposed HAPF system is tested and presented under nonideal supply voltage conditions.
Ishifuji, Miki; Mitsuishi, Masaya; Miyashita, Tokuji
2006-07-01
Effective utilization of coupled surface plasmon resonance from gold nanoparticles was demonstrated experimentally for optoelectronic applications based on second-order nonlinear optics. Hybrid polymer nanoassemblies were constructed by manipulating gold nanoparticle arrays with nonlinear optical active polymer nanosheets to investigate the second harmonic generation. The gold nanoparticle arrays were assembled on heterodeposited polymer nanosheets. The second harmonic light intensity was enhanced by a factor of 8. The observed enhancement was attributed to coupling of surface plasmons between two adjacent gold nanoparticles, thereby enhancing the surface electromagnetic field around the nanoparticles at the fundamental light wavelength (1064nm).
Directory of Open Access Journals (Sweden)
Ashraf M. Mohy Eldin
2013-08-01
Full Text Available This paper proposes a hybrid approach for co-channel speech segregation. HMM (hidden Markov model is used to track the pitches of 2 talkers. The resulting pitch tracks are then enriched with the prominent pitch. The enriched tracks are correctly grouped using pitch continuity. Medium frame harmonics are used to extract the second pitch for frames with only one pitch deduced using the previous steps. Finally, the pitch tracks are input to CASA (computational auditory scene analysis to segregate the mixed speech. The center frequency range of the gamma tone filter banks is maximized to reduce the overlap between the channels filtered for better segregation. Experiments were conducted using this hybrid approach on the speech separation challenge database and compared to the single (non-hybrid approaches, i.e. signal processing and CASA. Results show that using the hybrid approach outperforms the single approaches.
Recent result of gyrotron operation in NIFS
Directory of Open Access Journals (Sweden)
Ito Satoshi
2015-01-01
Full Text Available In the last Large Helical Device (LHD experimental campaign, a 154GHz gyrotron which had been conditioned to generate 1 MW/2 s, 0.5 MW/CW was installed for LHD experiments. Four high power gyrotrons (three-77 GHz/1~1.5 MW and one-154 GHz/1 MW and a CW gyrotron (84 GHz/0.2 MW are ready. Our experiment requires high energy and various injection patterns for Electron Cyclotron Resonance Heating (ECRH. Higher individual injection power and various injection patterns, we developed a power enhancement method by stepped anode acceleration voltage control and operated the gyrotron in the hard excitation region. These operations were realized by a remote controlled waveform generator. However the oscillation map of high power or long pulse operation in the hard excitation region were limited because in order to achieve the hard excitation region by the anode voltage control one must pass through the high anode current phase within a time short enough that the anode or the anode power supply is not overloaded. This limitation becomes more critical when the gyrotron beam current is increased in order to increase the output power. In the long pulse operation it was impossible to reach the hard excitation region in a low beam current (<10A.
Recent result of gyrotron operation in NIFS
Ito, Satoshi; Shimozuma, Takashi; Yoshimura, Yasuo; Igami, Hiroe; Takahashi, Hiromi; Nishiura, Masaki; Kobayashi, Sakuji; Mizuno, Yoshinori; Okada, Kota; Kubo, Shin
2015-03-01
In the last Large Helical Device (LHD) experimental campaign, a 154GHz gyrotron which had been conditioned to generate 1 MW/2 s, 0.5 MW/CW was installed for LHD experiments. Four high power gyrotrons (three-77 GHz/1~1.5 MW and one-154 GHz/1 MW) and a CW gyrotron (84 GHz/0.2 MW) are ready. Our experiment requires high energy and various injection patterns for Electron Cyclotron Resonance Heating (ECRH). Higher individual injection power and various injection patterns, we developed a power enhancement method by stepped anode acceleration voltage control and operated the gyrotron in the hard excitation region. These operations were realized by a remote controlled waveform generator. However the oscillation map of high power or long pulse operation in the hard excitation region were limited because in order to achieve the hard excitation region by the anode voltage control one must pass through the high anode current phase within a time short enough that the anode or the anode power supply is not overloaded. This limitation becomes more critical when the gyrotron beam current is increased in order to increase the output power. In the long pulse operation it was impossible to reach the hard excitation region in a low beam current (<10A).
Megawatt, 330 Hz PRF tunable gyrotron experiments
Spark, S. N.; Cross, A. W.; Phelps, A. D. R.; Ronald, K.
1994-12-01
Repetitively pulsed and cw gyrotrons have hitherto used thermionic cathodes, whereas cold cathode gyrotrons have normally operated as ‘single shot’ devices. The novel results presented here show that cold cathode gyrotrons can be successfully pulsed repetitively. A tunable gyrotron with a pulse repetition frequency (PRF) of 150Hz is demonstrated. This system developed >4MW mm-wave output pulses at 100GHz. The gyrotron is based on a two-electrode configuration comprising a field-immersed, field emission, cold cathode and a shaped anode cavity. A superconducting magnet was used to produce the homogeneous intra-cavity magnetic field and a cable pulser was used to drive the electron beam. This pulser produced up to a (200±20)kV pulse with 10ns rise time, a 100ns flat top, a 10ns decay with a characteristic impedance of 200Ω. The energy storage capacity of the cable pulser was 35J. The charging unit limited the maximum PRF to 330Hz. Due to spark gap switching limitations 330Hz was only obtainable in 5 to 10 pulse bursts. For substantial periods of the order of 30 seconds, 100Hz PRF was achieved over an oscillating range of 28 to 100GHz and 150Hz PRF was achieved at 80GHz. No degradation effects on the mm-wave output pulse was evident due to diode recovery time throughout this series of results. A subsequent conclusion is that the diode recovery time in our cold cathode gyrotron is less than 3ms.
A study of a simple gyrotron equation
Energy Technology Data Exchange (ETDEWEB)
Goetz, Markus [Max-Planck-Institut fuer Plasmaphysik, EURATOM-Association, D-85748 Garching (Germany); Meyer-Spasche, Rita [Max-Planck-Institut fuer Plasmaphysik, EURATOM-Association, D-85748 Garching (Germany); Weitzner, Harold [New York University, Courant Institute of Mathematical Sciences, New York, NY 10012 (United States)
2007-03-02
A simple standard equation for the evolution of the electrons and electromagnetic fields in a gyrotron cavity is studied. A number of mathematical properties are shown: existence and uniqueness of solutions for a limited axial extent and existence and uniqueness for all axial lengths in one case of particular interest. A Poynting theorem is obtained directly from the model and the Hamiltonian character of the electron motion is demonstrated. The start-up and final state in the gyrotron cavity are also examined. The efficiency of energy flux transfer from the electron beam to the wave is estimated.
Azam, Md Shafiul; Gibbs-Davis, Julianne M
2013-09-03
The immobilization of oligonucleotide sequences onto glass supports is central to the field of biodiagnostics and molecular biology with the widespread use of DNA microarrays. However, the influence of confinement on the behavior of DNA immobilized on silica is not well understood owing to the difficulties associated with monitoring this buried interface. Second harmonic generation (SHG) is an inherently surface specific technique making it well suited to observe processes at insulator interfaces like silica. Using a universal 3-nitropyrolle nucleotide as an SHG-active label, we monitored the hybridization rate and thermal dissociation of a 15-mer of DNA immobilized at the silica/aqueous interface. The immobilized DNA exhibits hybridization rates on the minute time scale, which is much slower than hybridization kinetics in solution but on par with hybridization behavior observed at electrochemical interfaces. In contrast, the thermal dissociation temperature of the DNA immobilized on silica is on average 12 °C lower than the analogous duplex in solution, which is more significant than that observed on other surfaces like gold. We attribute the destabilizing affect of silica to its negatively charged surface at neutral pH that repels the hybridizing complementary DNA.
Directory of Open Access Journals (Sweden)
T. Demirdelen
2016-10-01
Full Text Available In recent years, shunt hybrid active power filters are being increasingly considered as a viable alternative to both passive filters and active power filters for compensating harmonics. In literature, their applications are restricted to balanced systems and low voltage applications and therefore not for industrial applications. This paper investigates the performance of a modular cascaded multilevel inverter based Shunt Hybrid Active Power Filter (SHAPF for reactive power compensation and selective harmonics elimination under distorted/unbalanced grid voltage conditions in medium voltage levels. In the proposed control method, reactive power compensation is achieved successfully with a perceptible amount and the performance results of harmonic compensation are satisfactory. Theoretical analysis and simulation results are obtained from an actual industrial network model in PSCAD. The simulation results are presented for a proposed system in order to demonstrate that the harmonic compensation performance meets the IEEE-519 standard.
Particle simulation of a ka-band gyrotron traveling wave amplifier
Energy Technology Data Exchange (ETDEWEB)
Xu Shouxi; Liu Pukun; Zhang Shichang; Du Chaohai; Xue Qianzhong; Geng Zhihui; Su Yinong [Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, P.O. Box 2652, Beijing 100190 (China)
2011-08-15
The design of a ka-band gyrotron traveling wave (gyro-TWT) amplifier is presented. The gyro-TWT amplifier with a severed structure operates in the fundamental harmonic TE{sub 01} circular electric mode. The beam-wave interaction is studied by using a particle-in-cell (PIC) code. The simulations predict that the amplifier can produce an output peak power of over 155 kW, 22% efficiency, 23 dB gain, and a 3 dB bandwidth of 2 GHz for a 70 kV, 10 A electron beam with an axial velocity spread {Delta}v{sub z}/v{sub z}=5%.
A review on the sub-THz/THz gyrotrons
Kumar, Nitin; Singh, Udaybir; Bera, Anirban; Sinha, A. K.
2016-05-01
A review on the sub-THz/THz gyrotrons is performed in this manuscript. The present development status of gyrotrons can be divided into three streams for the sake of better understanding: 1. low frequency (industrial applications, 2. very high power (1 MW or more), medium frequency (100-200 GHz) gyrotrons for plasma fusion applications, 3. low power (few tens of watt to kW), high frequency (>200 GHz) gyrotrons for various innovative applications. In this manuscript, the third stream of gyrotron development is reviewed. In last few decades several innovative applications are searched in sub-THz/THz band where the gyrotrons could be used as an efficient source of RF radiation. The applications of sub-THz/THz gyrotrons including the futuristic scope of the device are also discussed in this article. Further, several criticalities arise in the design and development when the gyrotron operation shifts toward the high frequency band. Various such design and technological challenges are also discussed here. Finally the development status of sub-THz/THz gyrotrons as per the use in various scientific and technological applications is also discussed.
Theory and Modeling of High-Power Gyrotrons
Energy Technology Data Exchange (ETDEWEB)
Nusinovich, Gregory Semeon [Univ. of Maryland, College Park, MD (United States)
2016-04-29
This report summarized results of the work performed at the Institute for Research in Electronics and Applied Physics of the University of Maryland (College Park, MD) in the framework of the DOE Grant “Theory and Modeling of High-Power Gyrotrons”. The report covers the work performed in 2011-2014. The research work was performed in three directions: - possibilities of stable gyrotron operation in very high-order modes offering the output power exceeding 1 MW level in long-pulse/continuous-wave regimes, - effect of small imperfections in gyrotron fabrication and alignment on the gyrotron efficiency and operation, - some issues in physics of beam-wave interaction in gyrotrons.
Scaling Calculations for a Relativistic Gyrotron.
2014-09-26
a relativistic gyrotron. The results of calculations are given in Section 3. The non- linear , slow-time-scale equations of motion used for these...corresponds to a cylindrical resonator and a thin annular electron beam ;, " with the beam radius chosen to coincide with a maximum of the resonator...entering the cavity. A tractable set of non- linear equations based on a slow-time-scale formulation developed previously was used. For this
Continuously tunable, split-cavity gyrotrons
Brand, G. F.; Gross, M.
1985-12-01
Attention is given to a gyrotron cavity configuration which is split in halves longitudinally, to allow any frequency lying between the fixed cavity resonance to be assessed by mechanically changing the separation of the two halves. Experimental results are presented which demonstrate that the rate-of-change in resonant frequency with separation is greatest if the minor axis of the cavity cross section is the one undergoing change. Excellent agreement with theory is noted for these results.
Innovation on high-power long-pulse gyrotrons
Litvak, Alexander; Sakamoto, Keishi; Thumm, Manfred
2011-12-01
Progress in the worldwide development of high-power gyrotrons for magnetic confinement fusion plasma applications is described. After technology breakthroughs in research on gyrotron components in the 1990s, significant progress has been achieved in the last decade, in particular, in the field of long-pulse and continuous wave (CW) gyrotrons for a wide range of frequencies. At present, the development of 1 MW-class CW gyrotrons has been very successful; these are applicable for self-ignition experiments on fusion plasmas and their confinement in the tokamak ITER, for long-pulse confinement experiments in the stellarator Wendelstein 7-X (W7-X) and for EC H&CD in the future tokamak JT-60SA. For this progress in the field of high-power long-pulse gyrotrons, innovations such as the realization of high-efficiency stable oscillation in very high order cavity modes, the use of single-stage depressed collectors for energy recovery, highly efficient internal quasi-optical mode converters and synthetic diamond windows have essentially contributed. The total tube efficiencies are around 50% and the purity of the fundamental Gaussian output mode is 97% and higher. In addition, activities for advanced gyrotrons, e.g. a 2 MW gyrotron using a coaxial cavity, multi-frequency 1 MW gyrotrons and power modulation technology, have made progress.
Cancellation of neutral current harmonics by using a four-branch star hybrid filter
DEFF Research Database (Denmark)
Blaabjerg, Frede; Rodriguez, Pedro; Candela, I.
2008-01-01
with two independent and simultaneous resonance frequencies, i.e., one for positive-/negative-sequence and another one for zero-sequence components. The FBS filter topology can work either as a passive filter, when only passive components are employed, or as a hybrid filter, when its performance...
DEFF Research Database (Denmark)
Leißner, Till; Kostiučenko, Oksana; Brewer, Jonathan R.
2015-01-01
In this letter we show that the optical response of organic nanofibers, grown from functionalized para-quaterphenylene molecules, can be controlled by forming organic-plasmonic hybrid systems. The interaction between nanofibers and supporting regular arrays of nanostructures leads to a strongly...
Up to 400 GHz burst-mode pulse generation from a hybrid harmonic mode-locked Er-doped fibre laser
Wang, Sheng-Min; Lai, Yinchieh
2017-02-01
By inserting a birefringence filter with FSR = 100 GHz inside a hybrid mode-locked Er-doped fibre laser, we successfully generate ps to sub-ps optical burst pulses with the intra-burst pulse rate up to 400 GHz. Multiplication of the intra-burst pulse rate is attributed to a new effect analogous to rational harmonic mode-locking, which occurs due to the relative alignment of the cavity harmonic frequencies, the external phase modulation induced frequencies, and the filter-selected frequencies.
DEFF Research Database (Denmark)
Lee, Tzung-Lin; Wang, Yen-Ching; Li, Jian-Cheng
2015-01-01
-tuned passive filter and an active filter in series connection, both dc voltage and kVA rating of the active filter are dramatically decreased compared with the pure shunt active filter. In real application, this feature is very attractive since the active power filter with fully power electronics is very...... expensive. A reasonable trade-off between filtering performances and cost is to use the hybrid active filter. Design consideration are presented and experimental results are provided to validate effectiveness of the proposed method. Furthermore, this paper discusses filtering performances on line impedance...
Plasmon-enhanced second-harmonic generation from hybrid ZnO-covered silver-bowl array
Yang, Mingming; Shen, Shaoxin; Wang, Xiangjie; Yu, Binbin; Huang, Shengli; Xu, Die; Hu, Jiawen; Yang, Zhilin
2016-06-01
High-efficient, plasmon-enhanced nonlinear phenomena based on hybrid nanostructures, which combine nonlinear dielectrics with plasmonic metals, are of fundamental importance for various applications ranging from all-optical switching to imaging or bio-sensing. However, the high loss of the excitation energy in nanostructures and the poor spatial overlap between the plasmon enhancement and the bulk of nonlinear materials largely limit the operation of plasmon-enhanced nonlinear effects, resulting in low nonlinear conversion efficiency. Here, we design and fabricate a ZnO-covered, 2D silver-bowl array, which can serve as an efficient platform for plasmon-enhanced second-harmonic generation (PESHG). Validated by experiments and simulations, we demonstrate that the high spatial overlap between the near-field enhancement and the ZnO film plays the key role for this nanostructure-based PESHG process. The enhancement mainly originates from the fundamental wavelength-derived plasmon resonance, providing an enhancement factor of approximately 33 times. These results achieved pave the way for future applications, which require localized light sources at nanoscale.
Effect of ion compensation of the beam space charge on gyrotron operation
Energy Technology Data Exchange (ETDEWEB)
Fokin, A. P.; Glyavin, M. Yu. [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Nusinovich, G. S. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742-3511 (United States)
2015-04-15
In gyrotrons, the coherent radiation of electromagnetic waves takes place when the cyclotron resonance condition between the wave frequency and the electron cyclotron frequency or its harmonic holds. The voltage depression caused by the beam space charge field changes the relativistic cyclotron frequency and, hence, can play an important role in the beam-wave interaction process. In long pulse and continuous-wave regimes, the beam space charge field can be partially compensated by the ions, which appear due to the beam impact ionization of neutral molecules of residual gases in the interaction space. In the present paper, the role of this ion compensation of the beam space charge on the interaction efficiency is analyzed. We also analyze the effect of the electron velocity spread on the limiting currents and discuss some effects restricting the ion-to-beam electron density ratio in the saturation stage. It is shown that the effect of the ion compensation on the voltage depression caused by the beam space charge field can cause significant changes in the efficiency of gyrotron operation and, in some cases, even result in the break of oscillations.
Gyrotrons for magnetic fusion applications at 110 GHz and 170 GHz
Directory of Open Access Journals (Sweden)
Cahalan P.
2012-09-01
Full Text Available Two megawatt-class gyrotrons at frequencies of 110 GHz and 170 GHz have recently been fabricated at CPI. The 110 GHz gyrotron is designed to produce 1.2 MW of output power for 10-second pulses, and will be used for electron cyclotron heating and current drive on the DIII-D tokamak at General Atomics. This gyrotron has completed factory testing and has been delivered to General Atomics for installation and additional testing. The 170 GHz gyrotron, though specified as a 500 kW CW system, has been designed with the goal of generating up to 1 MW CW. Oak Ridge National Laboratory will use this gyrotron in ITER ECH transmission line testing. This gyrotron has been fabricated and is awaiting factory testing, Design features of each gyrotron are described, and test data for the 110 GHz gyrotron are presented.
Systematic Observation of Time-Dependent Phenomena in the RF Output Spectrum of High Power Gyrotrons
Directory of Open Access Journals (Sweden)
Kern Stefan
2012-09-01
Full Text Available At IHM/KIT, high power gyrotrons with conventional cavity (e.g. 1 MW CW at 140 GHz for the stellarator Wendelstein 7-X and coaxial cavity (2 MW shortpulse at 170 GHz for ITER for fusion applications are being developed and verified experimentally. Especially with respect to the problem of parasitic RF oscillations in the beam tunnel of some W7-X tubes, investigations of the gyrotron RF output spectrum have proved to be a valuable source of diagnostic information. Signs of transient effects in millisecond pulses, like frequency switching or intermittent low-frequency modulation, have indicated that truly time-dependent measurements with high frequency resolution and dynamic range could give deeper insight into these phenomena. In this paper, an improved measurement system is presented, which employs a fast oscilloscope as receiver. Shorttime Fourier transform (STFT is applied to the time-domain signal, yielding time-variant spectra with frequency resolutions only limited by acquisition length and STFT segmentation choice. Typical reasonable resolutions are in the range of 100 kHz to 10 MHz with a currently memory-limited maximum acquisition length of 4 ms. A key feature of the system consists in the unambiguity of frequency measurement: The system receives through two parallel channels, each using a harmonic mixer (h = 9 – 12 to convert the signal from RF millimeter wave frequencies (full D-Band, 110 – 170 GHz to IF (0 – 3 GHz. For each IF output signal of each individual mixer, injection side and receiving harmonic are initially not known. Using accordingly determined LO frequencies, this information is retrieved from the redundancy of the channels, yielding unambiguously reconstructed RF spectra with a total span of twice the usable receiver IF bandwidth, up to ≈ 6 GHz in our case. Using the system, which is still being improved continuously, various transient effects like cavity mode switching, parasitic oscillation frequency variation
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
Further studies of a simple gyrotron equation: nonlinear theory
Energy Technology Data Exchange (ETDEWEB)
Shi Meixuan, E-mail: meixuan@cims.nyu.ed [Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, NY 10012-1185 (United States)
2010-11-05
A nonlinear version of a standard system of gyrotron model equations is studied using asymptotic analysis and variational methods. The condition for obtaining a high-amplitude wave is achieved in the study. A simple method for obtaining the patterns and amplitude of the wave based on the given free-space wave-number pattern is shown.
DEFF Research Database (Denmark)
Luo, Zhaoxu; Su, Mei; Yang, Jian;
2016-01-01
in stationary reference frame, which only compensates the 6k+1 harmonics (e.g. -5, +7, -11, +13) in three-phase systems and reduces the time delay to T0/6 . So compared with the earlier reduced delay time repetitive controllers, the robustness and transient performance is further improved, the waste of control...
A novel vacuum window for megawatt gyrotrons
Haldeman, George Stephenson
2001-08-01
This thesis describes a new microwave output window for megawatt power level, 110 GHz gyrotrons. The window uses two spherically polished sapphire elements separated by a nearly uniform gap of about 1 mm. Pressurized, microwave transparent coolant flows through this gap and across the transmitting aperture, removing absorbed energy at the element face. The design differs from previous face- cooled windows because the sapphire elements have a modestly curved dome, rather than flat shape. This curved shape increases the element's capability to withstand coolant pressures without significantly increasing stresses from differential heating. Consequently, window power can be increased either through enhanced, high pressure cooling or by using thinner elements with reduced microwave absorption. A model was developed to predict window power capability as a function of design geometry. This model predicted an increase from 0.5 to 2.1 MW when flat elements were changed to curved. Both designs used full size, 100mm clear apertures, but the curved elements with 214 mm curvature radii were 1.3 rather than 1.75 mm thick. The model was also used to design a half size prototype experiment. This 50 mm clear aperture system used 60 mm OD x 0.47 mm thick x 107 mm surface radius elements. An initial piece was fabricated and statically tested to a pressure of 1.1 MPa well above the 0.5 MPa analytically predicted to be required for megawatt operation. The complete window structure was then fabricated, including instrumentation to simulate microwave heating and to measure induced temperatures and strains. Test results demonstrated an equivalent continuous Gaussian beam power capability of 700 kW using a coolant flow of 1.1 lps. Scaling from this measurement, fall size boiling limited power is expected to be 1.1 MW for a Gaussian microwave intensity profile, or 2.3 MW for a shaped profile typical of previous flat, face-cooled designs. (Copies available exclusively from MIT Libraries, Rm
Recent Tests on 117.5 GHz and 170 GHz Gyrotrons
Directory of Open Access Journals (Sweden)
Felch K.
2015-01-01
Full Text Available Two megawatt-class gyrotrons at frequencies of 117.5 GHz and 170 GHz have recently been fabricated and tested at CPI. The 117.5 GHz gyrotron was designed to produce up to 1.8 MW for 10-second pulses, and will be used for electron cyclotron heating and current drive on the DIII-D tokamak at General Atomics. The 170 GHz gyrotron is specified as a 500 kW CW system, but has been designed with the goal of generating up to 1 MW CW. Oak Ridge National Laboratory will use the gyrotron in ITER ECH transmission line testing.
DEFF Research Database (Denmark)
Liu, Yuan; Wu, Weimin; He, Yuanbin
2016-01-01
A high-order (LCL or LLCL) power filter with a small grid-side inductor is becoming more preferred for a grid-tied inverter due to less total inductance and reduced costs. In a microgrid, the background harmonic voltage (BHV) may distort the injected currents of the grid-tied inverters. In order......-current-feedback AD. Based on this, a single-loop current control with a hybrid damper is proposed for a single-phase LCLor LLCL-filter-based grid-tied inverter. A step-by-step design of the controller method is also introduced in detail. Experiments on a 2-kW prototype fully demonstrate the strong robustness...
Further studies of a simple gyrotron equation: linear theory
Energy Technology Data Exchange (ETDEWEB)
Weitzner, Harold [New York University, Courant Institute of Mathematical Sciences New York, NY 10012 (United States)
2009-07-03
A linearized version of a standard system of gyrotron model equations is studied. The linearization allows the inclusion of some effects of particle bunching. The normal modes of the linearized system are given. It is shown that bunching effects couple incoming and outgoing waves. The waves near resonance duplicate well-known results. Without bunching and with a simple background profile function integral representations of solutions are given and discussed.
Photonic-Band-Gap Traveling-Wave Gyrotron Amplifier
Nanni, E. A.; Lewis, S. M.; Shapiro, M. A.; Griffin, R. G.; Temkin, R. J.
2014-01-01
We report the experimental demonstration of a gyrotron traveling-wave-tube amplifier at 250 GHz that uses a photonic band gap (PBG) interaction circuit. The gyrotron amplifier achieved a peak small signal gain of 38 dB and 45 W output power at 247.7 GHz with an instantaneous −3 dB bandwidth of 0.4 GHz. The amplifier can be tuned for operation from 245–256 GHz. The widest instantaneous −3 dB bandwidth of 4.5 GHz centered at 253.25 GHz was observed with a gain of 24 dB. The PBG circuit provides stability from oscillations by supporting the propagation of transverse electric (TE) modes in a narrow range of frequencies, allowing for the confinement of the operating TE03-like mode while rejecting the excitation of oscillations at nearby frequencies. This experiment achieved the highest frequency of operation for a gyrotron amplifier; at present, there are no other amplifiers in this frequency range that are capable of producing either high gain or high output power. This result represents the highest gain observed above 94 GHz and the highest output power achieved above 140 GHz by any conventional-voltage vacuum electron device based amplifier. PMID:24476286
Investigations and advanced concepts on gyrotron interaction modeling and simulations
Avramidis, K. A.
2015-12-01
In gyrotron theory, the interaction between the electron beam and the high frequency electromagnetic field is commonly modeled using the slow variables approach. The slow variables are quantities that vary slowly in time in comparison to the electron cyclotron frequency. They represent the electron momentum and the high frequency field of the resonant TE modes in the gyrotron cavity. For their definition, some reference frequencies need to be introduced. These include the so-called averaging frequency, used to define the slow variable corresponding to the electron momentum, and the carrier frequencies, used to define the slow variables corresponding to the field envelopes of the modes. From the mathematical point of view, the choice of the reference frequencies is, to some extent, arbitrary. However, from the numerical point of view, there are arguments that point toward specific choices, in the sense that these choices are advantageous in terms of simulation speed and accuracy. In this paper, the typical monochromatic gyrotron operation is considered, and the numerical integration of the interaction equations is performed by the trajectory approach, since it is the fastest, and therefore it is the one that is most commonly used. The influence of the choice of the reference frequencies on the interaction simulations is studied using theoretical arguments, as well as numerical simulations. From these investigations, appropriate choices for the values of the reference frequencies are identified. In addition, novel, advanced concepts for the definitions of these frequencies are addressed, and their benefits are demonstrated numerically.
Gao, Weiwei; Wang, Lin; Li, Heting
2017-03-01
In this paper we design a simultaneous three bunch length operating mode at the HLS-II (Hefei Light Source II) storage ring by installing two harmonic cavities and minimizing the momentum compaction factor. The short bunches (2.6 mm) presented in this work will meet the requirement of coherent millimeter-wave and sub-THz radiation experiments, while the long bunches (20 mm) will efficiently increase the total beam current. Therefore, this multiple-bunch-length operating mode allows present synchrotron users and coherent millimeter-wave users (or sub THz users) to carry out their experiments simultaneously. Since the relatively low energy characteristic of HLS-II we achieve the multiple-bunch-length operating mode without multicell superconducting RF cavities, which is technically feasible.
Bratman, V. L.; Savilov, A. V.; Chang, T. H.
2016-02-01
Large ohmic losses in the cavities of terahertz gyrotrons may lead to the overlapping of the axial mode spectra. In a number of gyrotron experiments, this effect has been used to provide a fairly broadband frequency tuning by changing appropriately the operating magnetic field and/or accelerating voltage of the gyrotron. Similar to the systems with nonfixed axial structure of the RF electromagnetic field and low diffraction quality, which are due to weak reflections of the operating wave from the collector end of the electrodynamic system, this changing leads to a monotonic change in the axial index of the operating wave and transition from the gyrotron regime to the gyro-BWO regime. According to a theoretical comparison of these two methods performed on the basis of generalization of self-consistent gyrotron equations with allowance for variations in the axial electron momenta, low-reflection systems can provide a higher efficiency and monotonicity of the frequency tuning.
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
Spectral estimation method is an effective method in the case of parameter estimation of sinusoid signal in noises.It always applies cross-spectral estimation theory and high-order self-spectral estimation methods up to now.Yule-Walker equation based on cross-fourth-order cumulant is developed and Pisarenko method is provided in this paper.Simulation results show that the method is effective to retrieve sinusoid signal frequencies from hybrid colored noises and has good performance.
Institute of Scientific and Technical Information of China (English)
王建勋; 刘会金; 韩丰收; 王占雷
2012-01-01
To detect interharmonics whose frequencies are near to those of harmonics and fundamental harmonic, a hybrid time-frequency domain method is proposed to analyze harmonics and interharmonics. Firstly, the detection of harmonics and fundamental harmonic in time-domain is performed by parallel enhanced phase-locked loop (PLL) structure, in which the main PLL is used to measure fundamental component signal with higher amplitude and the measured fundamental component is input to parallel sub-PLL structure to segregate harmonic components; then in frequency-domain the post-segregation signals, in which only interharmonics are contained, are analyzed by interpolated fast Fourier transformation (IFFT), thus accurate parameters of interharmonics whose frequencies are near to those of harmonics and fundamental harmonic can be attained when the spectral leakage of harmonics and fundamental harmonic are excluded. An online monitoring platform of harmonics and fundamental harmonic based on the proposed method is implemented by Lab VIEW software, and both results from experiments and simulation show that the proposed method is effective.%为了检测靠近基波和谐波的间谐波,提出了一种时频混合方法来分析谐波和间谐波.首先在时域上通过并联的加强锁相环结构进行基波与谐波检测,该结构通过主锁相环测量幅值较大的基频分量,并将测得的基频输入到并行的子锁相环结构以完成对各谐波分量的分离;然后在频域上对分离所得的只含间谐波的信号使用插值快速傅里叶变换的方法进行分析,能在排除基波与谐波频谱泄漏影响的情况下得到靠近基波和谐波的间谐波的精确参数.在LabVIEW上实现了基于所提方法的谐波、间谐波在线监测平台,仿真和实验证明了所提方法的有效性.
Observation of harmonic gyro-backward-wave oscillation in a 100 GHz CARM oscillator experiment
McCowan, Robert B.; Sullivan, Carol A.; Gold, Steven H.; Fliflet, Arne W.
1991-02-01
A cyclotron autoresonance maser (CARM) oscillator experiment is reported, using a 600 keV, 200 A electron beam, and a whispering gallery-mode rippled-wall Bragg cavity. This device was designed to produce tens of megawatts of radiation at 100 GHz from a CARM interaction, but instead has produced only moderate powers (tens of kWs) in fundamental gyrotron modes near 35 GHz, in third-harmonic-gyro-BWO modes, and possible third-harmonic gyrotron modes at frequencies near the expected CARM frequency, with no discernable CARM radiation. The lack of observable CARM radiation is attributed to excessive ripple on the voltage waveform and to mode competition. Calculations of the spectrum and growth rate of the backward-wave oscillations are consistent with the experimental observation.
High power 303 GHz gyrotron for CTS in LHD
Yamaguchi, Y.; Kasa, J.; Saito, T.; Tatematsu, Y.; Kotera, M.; Kubo, S.; Shimozuma, T.; Tanaka, K.; Nishiura, M.
2015-10-01
A high-power pulsed gyrotron is under development for 300 GHz-band collective Thomson scattering (CTS) diagnostics in the Large Helical Device (LHD). High-density plasmas in the LHD require a probe wave with power exceeding 100 kW in the sub-terahertz region to obtain sufficient signal intensity and large scattering angles. At the same time, the frequency bandwidth should be less than several tens of megahertz to protect the CTS receiver using a notch filter against stray radiations. Moreover, duty cycles of ~ 10% are desired for the time domain analysis of the CTS spectrum. At present, a 77 GHz gyrotron for electron cyclotron heating is used as a CTS wave source in the LHD. However, the use of such a low-frequency wave suffers from refraction, cutoff and absorption at the electron cyclotron resonance layer. Additionally, the signal detection is severely affected by background noise from electron cyclotron emission. To resolve those problems, high-power gyrotrons in the 300 GHz range have been developed. In this frequency range, avoiding mode competition is critical to realizing high-power and stable oscillation. A moderately over-moded cavity was investigated to isolate a desired mode from neighbouring modes. After successful tests with a prototype tube, the practical one was constructed with a cavity for TE22,2 operation mode, a triode electron gun forming intense laminar electron beams, and an internal mode convertor. We have experimentally confirmed single mode oscillation of the TE22,2 mode at the frequency of 303.3 GHz. The spectrum peak is sufficiently narrow. The output power of 290 kW has been obtained at the moment.
Rapid frequency step-switching in submillimeter wave gyrotrons (Gyrotrons FU III and FU IV)
Idehara, T.; Shimizu, Y; Ogawa, I.; Tatsukawa, T.; BRAND, G.F.
1999-01-01
The rapid frequency step-switching between two nearby cyclotron fundamental modes achieved by switching beam energy is analyzed by a computer simulation and demonstrated experimentally. More dramatic frequency switching between a fundamental mode and a second harmonic mode is analyzed and demonstrated experimentally.
Effects of electron-cyclotron instabilities on gyrotron beam quality
Energy Technology Data Exchange (ETDEWEB)
Jost, G.; Tran, T.M.; Appert, K. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP); Wuethrich, S. [CRAY Research, PATP/PSE, EPFL, Lausanne (Switzerland)
1996-02-01
A two-dimensional PIC code aimed at the investigation of electron-cyclotron beam instabilities in gyrotrons and their effects on the beam quality is presented. The code is based on recently developed techniques for handling charge conservation and open boundaries. It has been implemented on the massively parallel computer CRAY T3D. First results show an electromagnetic backward instability periodically growing and decaying to energy levels close to those obtained from the electrostatic Bernstein wave instability. On the average, the resulting beam degradation is 3 to 4 times larger than that predicted by electrostatic models. (author) 8 figs., 14 refs.
Eliazar, Iddo
2017-05-01
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.
140 GHz gyrotron development program. Quarterly report No. 4, January-March 1985
Energy Technology Data Exchange (ETDEWEB)
Felch, K.L.; Bier, R.E.; Craig, L.J.; Fox, L.J.; Hu, G.; Huey, H.E.; Ives, R.L.; Jory, H.R.; Lopez, N.C.; Reysner, P.I.
1986-01-01
The objective of this program is to develop a gyrotron oscillator capable of producing 100 kW CW at 140 GHz. Further analysis of the electron guns, interaction cavity, and beam tunnel designs for the first two experimental tubes, Experimental Tube 1 and preprototype Tube 1, is presented. A window deflection tester has been built and initial deflection test results are given. The first 140 GHz gyrotron magnet has successfully passed the major points in the acceptance test. The detailed results of the magnet acceptance test are discussed. Progress concerning the fabrication of 149 GHz gyrotron components, diagnostics, and protective devices, as well as the status of Experimental Tube 1, are summarized.
Gusakov, E. Z.; Popov, A. Yu
2017-02-01
The nonlinear saturation of low-power-threshold two-upper-hybrid (UH)-plasmon parametric decay instability (PDI) of an extraordinary pump wave-excited in the presence of a nonmonotonous density profile is analyzed in detail. It is shown that the primary absolute PDI enhancing the UH wave fluctuations from the thermal noise level, which was analyzed in linear approximation in Popov and Gusakov (2015 Plasma Phys. Control. Fusion 57 025022), is saturated due to a secondary low-threshold decay of the daughter UH wave. The secondary decay leads to excitation of the secondary UH wave, downshifted in frequency and also trapped in the vicinity of the local maximum of the density profile, and the ion Bernstein wave. A set of equations describing the primary and secondary decays and accounting for the finite pump-beam width is derived and solved numerically. The results of numerical modeling are shown to be in agreement with an analytical estimation of the growth rates of both the primary and secondary parametric decays and of the saturation level. The anomalous absorption of the pump wave due to the two plasmon PDI is estimated at a level of 6% for the plasma density profile considered in the paper.
Application of Fusion Gyrotrons to Enhanced Geothermal Systems (EGS)
Woskov, P.; Einstein, H.; Oglesby, K.
2013-10-01
The potential size of geothermal energy resources is second only to fusion energy. Advances are needed in drilling technology and heat reservoir formation to realize this potential. Millimeter-wave (MMW) gyrotrons and related technologies developed for fusion energy research could contribute to enabling EGS. Directed MMW energy can be used to advance rock penetration capabilities, borehole casing, and fracking. MMWs are ideally suited because they can penetrate through small particulate extraction plumes, can be efficiently guided long distances in borehole dimensions, and continuous megawatt sources are commercially available. Laboratory experiments with a 10 kW, 28 GHz CPI gyrotron have shown that granite rock can be fractured and melted with power intensities of about 1 kW/cm2 and minute exposure times. Observed melted rock MMW emissivity and estimated thermodynamics suggest that penetrating hot, hard crystalline rock formations may be economic with fusion research developed MMW sources. Supported by USDOE, Office of Energy Efficiency and Renewable Energy and Impact Technologies, LLC.
A Two Frequency 1.5 MW Gyrotron Experiment
Tax, David; Guss, William; Shapiro, Michael; Temkin, Richard; Rock, Ben; Vernon, Ronald; Neilson, Jeffrey
2012-10-01
Megawatt gyrotrons are an important microwave source for electron cyclotron heating and current drive (ECH/ECCD) in fusion plasmas due to their ability to produce megawatts of power at millimeter wave frequencies. The MIT gyrotron operates nominally at 96 kV and 40 A with 3 μs pulses and has previously demonstrated 1.5 MW of output power with > 50 % efficiency at 110 GHz with a depressed collector. A new cavity has been designed for 1.5 MW operation at two distinct frequencies: 110 GHz in the TE22,6 mode and 124.5 GHz in the TE24,7 mode. A new internal mode converter (IMC) consisting of a dimpled wall launcher and four smooth curved mirrors has also been designed and was optimized for both modes. Simulations of the IMC indicate that > 98 % Gaussian beam content could be achieved for each mode. Cold test results for the components will be presented as well as the current status of the hot test experiment.
Long-Term Operating Experience with High-Power Gyrotron Oscillators
Felch, Kevin
2005-10-01
High-power, megawatt-class gyrotron oscillators have now been used in electron cyclotron heating (ECH) experiments for several years. The long periods of sustained operation have provided important information about the design limits that had initially been placed on the key elements of the gyrotron. In particular, observations made on recent 110 GHz, 1 MW gyrotrons used in ECH experiments on DIII-D at General Atomics indicate that several of the important components of the device, including the electron guns, interaction cavities and diamond output windows, have performed quite well, while analyses of the electron beam collectors on some of the devices indicate that design limits have often been exceeded. Observations made on these gyrotrons will be summarized and plans to address problem areas will be discussed.
Hochman, J. M.; Gilgenbach, R. M.; Jaynes, R. L.; Rintamaki, J. I.; Luginsland, J. W.; Lau, Y. Y.; Spencer, T. A.
1996-11-01
Experiments utilize large and small orbit e-beam gyrotron devices in a rectangular-cross-section (RCS) gyrotron. This device is being explored to examine polarization control. Other research issues include pulse shortening, and mode competition. MELBA generates electron beams with parameters of: -800kV, 1-10kA diode current, and 0.5-1.0 μ sec pulselengths. The small orbit gyrotron device is converted to a large orbit experiment by running MELBA's annular electron beam through a magnetic cusp. Initial experiments showed an increase in beam alpha (V_perp/V_par) of a factor of ~ 4 between small and large orbit devices. Experimental results from the RCS gyrotron will be compared for large-orbit and small-orbit electron beams. Beam transport data and frequency measurements will be presented. Computer modeling utilizing the MAGIC and E-gun codes will be shown.
Ion Compensation for Space Charge in the Helical Electron Beams of Gyrotrons
Manuilov, V. N.; Semenov, V. E.
2016-06-01
We solve analytically the problem about ion compensation for the space charge of a helical electron beam in a gyrotron operated in the long-pulse regime. Elementary processes, which take place during ionization of residual gas in the tube under typical pressures of 10-6-10-7 mm Hg, are considered. It is shown that distribution of the space charge is affected mainly by the electrons of the initial beam and slow-moving ions produced by ionization of the residual gas. Steady-state density of ions in the operating space of the gyrotron after the end of the transitional processes is found, as well as the electron density profile in the channel of electron beam transportation. The results obtained allow us to evaluate the pitch-factor variations caused by partial compensations for the potential "sagging" in the gyrotron cavity, thus being useful for analysis of starting currents, efficiency, and mode competition in high-power gyrotrons.
Design of an electronically tunable millimeter wave Gyrotron Backward Wave Oscillator
Energy Technology Data Exchange (ETDEWEB)
Caplan, M.
1987-01-01
A non-linear self-consistent computer simulation code is used to analyze the saturated output of the Gyrotron Backward Wave Oscillator (Gyro BWO) which can be used as a tunable driver for a 250 GHz FEL amplifier. Simulations show that the Gyrotron BWO using a Pierce/Wiggler gun configuration can produce at least 10 kW of microwave power over the range 249 GHz to 265 GHz by varying beam voltage alone.
Design of an electronically tunable millimeter wave Gyrotron Backward Wave Oscillator
Energy Technology Data Exchange (ETDEWEB)
Caplan, M.
1987-01-01
A non-linear self-consistent computer simulation code is used to analyze the saturated output of the Gyrotron Backward Wave Oscillator (Gyro BWO) which can be used as a tunable driver for a 250 GHz FEL amplifier. Simulations show that the Gyrotron BWO using a Pierce/Wiggler gun configuration can produce at least 10 kW of microwave power over the range 249 GHz to 265 GHz by varying beam voltage alone.
Cold test of cylindrical open resonator for 42 GHz, 200 kW gyrotron
Indian Academy of Sciences (India)
Vivek Yadav; Sudeep Sharan; Hasina Khatun; Nitin Kumar; M K Alaria; B Jha; S C Deorani; A K Sinha; P K Jain
2013-12-01
This paper presents experimental results for cold testing of a gyrotron open resonator. Experiments were carried out to measure resonant frequency and their particular quality factor for TE mode at the frequency 42 GHz. The perturbation technique was used to determine the axial, radial and azimuthal electric field profile for identification of TE031 mode at operating frequency 42 GHz. The good agreement between experimental results and theoretical studies was found. The results verify the design and fabrication of the specific gyrotron cavity.
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.
Damyanova, M.; Sabchevski, S.; Zhelyazkov, I.; Vasileva, E.; Balabanova, E.; Dankov, P.; Malinov, P.
2016-10-01
As the most powerful CW sources of coherent radiation in the sub-terahertz to terahertz frequency range the gyrotrons have demonstrated a remarkable potential for numerous novel and prospective applications in the fundamental physical research and the technologies. Among them are powerful gyrotrons for electron cyclotron resonance heating (ECRH) and current drive (ECCD) of magnetically confined plasma in various reactors for controlled thermonuclear fusion (e.g., tokamaks and most notably ITER), high-frequency gyrotrons for sub-terahertz spectroscopy (for example NMR-DNP, XDMR, study of the hyperfine structure of positronium, etc.), gyrotrons for thermal processing and so on. Modelling and simulation are indispensable tools for numerical studies, computer-aided design (CAD) and optimization of such sophisticated vacuum tubes (fast-wave devices) operating on a physical principle known as electron cyclotron resonance maser (ECRM) instability. During the recent years, our research team has been involved in the development of physical models and problem-oriented software packages for numerical analysis and CAD of different gyrotrons in the framework of a broad international collaboration. In this paper we present the current status of our simulation tools (GYROSIM and GYREOSS packages) and illustrate their functionality by results of numerical experiments carried out recently. Finally, we provide an outlook on the envisaged further development of the computer codes and the computational modules belonging to these packages and specialized to different subsystems of the gyrotrons.
Optimization of operation of a three-electrode gyrotron with the use of a flow-type calorimeter
Energy Technology Data Exchange (ETDEWEB)
Kharchev, Nikolay K.; Batanov, German M.; Kolik, Leonid V.; Malakhov, Dmitrii V.; Petrov, Aleksandr Ye.; Sarksyan, Karen A.; Skvortsova, Nina N.; Stepakhin, Vladimir D. [Prokhorov General Physics Institute, Vavilova ul. 38, Moscow 119991 (Russian Federation); Belousov, Vladimir I. [Institute of Applied Physics, Ul' yanova ul. 46, Nizhnii Novgorod 603950 (Russian Federation); Malygin, Sergei A.; Tai, Yevgenii M. [GYCOM Company, Ul' yanova ul. 46, Nizhnii Novgorod 603155 (Russian Federation)
2013-01-15
Results are presented for measurements of microwave power of the Borets-75/0.8 gyrotron with recovery of residual electron energy, which were performed by a flow-type calorimeter. This gyrotron is a part of the ECR plasma heating complex put into operation in 2010 at the L-2M stellarator. The new calorimeter is capable of measuring microwave power up to 0.5 MW. Monitoring of the microwave power makes it possible to control the parameters of the gyrotron power supply unit (its voltage and current) and the magnetic field of the cryomagnet in order to optimize the gyrotron operation and arrive at maximum efficiency.
Millimeter-wave gyrotron traveling-wave tube amplifiers
Du, Chao-Hai
2014-01-01
A gyrotron traveling-wave amplifier (gyro-TWT) with the high-power and broad-band capabilities is considered as a turn-on key for next generation high-resolution radar. The book presents comprehensive theory, methods, and physics related to gyro-TWT. The most challenging problem of instability competition has been for the first time addressed in a focused and systematic way, and reported via concise states and vivid pictures. The book is likely to meet the interest of researchers and engineers in radar and microwave technology, who would like to study the gyro-TWTs and to promote its application in millimeter-wave radars. Chao-Hai Du is a research professor, and Pu-Kun Liu is a full professor, at Peking University, Beijing, P. R. China.
Glyavin, M. Yu.; Morozkin, M. V.; Tsvetkov, A. I.; Lubyako, L. V.; Golubiatnikov, G. Yu.; Kuftin, A. N.; Zapevalov, V. E.; V. Kholoptsev, V.; Eremeev, A. G.; Sedov, A. S.; Malygin, V. I.; Chirkov, A. V.; Fokin, A. P.; Sokolov, E. V.; Denisov, G. G.
2016-02-01
We study experimentally the automated microwave complex for microwave spectroscopy and diagnostics of various media, which was developed at the Institute of Applied Physics of the Russian Academy of Sciences in cooperation with GYCOM Ltd. on the basis of a gyrotron with a frequency of 263 GHz and operated at the first gyrofrequency harmonic. In the process of the experiments, a controllable output power of 0 .1 -1 kW was achieved with an efficiency of up to 17 % in the continuous-wave generation regime. The measured radiation spectrum with a relative width of about 10 -6 and the frequency values measured at various parameters of the device are presented. The results of measuring the parameters of the wave beam, which was formed by a built-in quasioptical converter, as well as the data obtained by measuring the heat loss in the cavity and the vacuum output window are analyzed.
Optimal Selective Harmonic Control for Power Harmonics Mitigation
DEFF Research Database (Denmark)
Zhou, Keliang; Yang, Yongheng; Blaabjerg, Frede
2015-01-01
the cost, the complexity and the performance: high accuracy, fast transient response, easy-implementation, cost-effective, and also easy-to-design. The analysis and synthesis of the optimal SHC system are addressed. The proposed SHC offers power convert-ers a tailor-made optimal control solution......This paper proposes an Internal Model Principle (IMP) based optimal Selective Harmonic Controller (SHC) for power converters to mitigate power harmonics. According to the harmonics distribution caused by power converters, a universal recursive SHC module is developed to deal with a featured group...... 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...
Development of dual frequency gyrotron and high power test of EC components
Directory of Open Access Journals (Sweden)
Sakamoto K.
2012-09-01
Full Text Available In JAEA, development of high-power long-pulse gyrotrons is underway. The output power of the gyrotron was applied for high-power long-pulse tests of the transmission line (TL and the equatorial launcher (EL mock up for ITER. The feature of design in the dual frequency gyrotron is the simultaneously satisfying the matching of both frequencies at a window and the same radiation angle at an internal mode convertor for both frequencies. The dual frequency gyrotron was developed and high power operations at 170 GHz and 137 GHz were carried out. The 170 GHz high power experiment of 40 m length ITER relevant TL was carried out and transmission efficiency and mode purity change caused by long pulse operation were measured. The mock-up model of EL was also tested using 170 GHz gyrotron. The power transmission through the quasi-optical beam line in EL was demonstrated using the full scale mock up model. Furthermore, the high power test results of the transmission components will be summarized.
Energy Technology Data Exchange (ETDEWEB)
Jory, H.; Felch, K.; Hess, C.; Huey, H.; Jongewaard, E.; Neilson, J.; Pendleton, R.; Tsirulnikov, M. (Varian Associates, Inc., Palo Alto, CA (USA))
1990-09-17
To address the electron cyclotron heating requirements of planned fusion experiments such as the International Thermonuclear Experimental Reactor (ITER) and the Compact Ignition Tokamak (CIT), Varian is developing gyrotrons at frequencies ranging from 100--300 GHz with output power capabilities up to 1 MW CW. Experimental gyrotrons have been built at frequencies between 100--140 GHz, and a study program has addressed the critical elements of designing 280--300 GHz gyrotrons capable of generating CW power levels up to 1 MW. Initial test vehicles at 140 GHz have utilized TE{sub 15,2,1} interaction cavities, and have been designed to generate short-pulse (up to 20 ms) power levels of 1 MW and up to 400 kW CW. Recently, short-pulse power levels of 1040 kW at 38% efficiency have been obtained and average powers of 200 kW have been achieved. Long-pulse operation has been extended to pulse durations of 0.5 seconds at power levels of 400 kW. Gyrotron oscillators capable of generating output powers of 500 kW CW at a frequency of 110 GHz have recently been designed and a prototype is currently being tested. Design work for a 1 MW CW gyrotron at 110 GHz, is in progress. The 1 MW CW tube will employ an output coupling approach where the microwave output is separated from the microwave output. 15 refs., 10 figs., 3 tabs.
Plasma scattering measurement using a submillimeter wave gyrotron as a radiation source
Energy Technology Data Exchange (ETDEWEB)
Ogawa, I.; Idehara, T.; Itakura, Y.; Myodo, M. [Fukui Univ., Research Center for Development of Far-Infrared Region (Japan); Hori, T. [National Institute of Information and Communications Technology, Basic and Advanced Research Division, Nukui-Kita, Koganei (Japan); Hatae, T. [Japan Atomic Energy Research Institute, Mukoyama, Naka (Japan)
2004-07-01
Plasma scattering measurement is an effective technique to observe low frequency density fluctuations excited in plasma. The spatial and wave number resolutions and the S/N ratio of measurement depend on the wavelength range, the size and the intensity of a probe beam. A well-collimated, submillimeter wave beam is suitable for improving the spatial and wave number resolutions. Application of high frequency gyrotron is effective in improving the S/N ratio of the measurement because of its capacity to deliver high power. Unlike the molecular vapor lasers, the gyrotrons generate diverging beam of radiation with TE{sub mn} mode structure. It is therefore necessary to convert the output radiation into a Gaussian beam. A quasi-optical antenna is a suitable element for the conversion system under consideration since it is applicable to several TE{sub 0n} and TE{sub 1n} modes. In order to apply the gyrotron to plasma scattering measurement, we have stabilized the output (P = 110 W, f = 354 GHz) of gyrotron up to the level ({delta}P/P < 1 %, {delta}f< 10 kHz). The gyrotron output can be stabilized by decreasing the fluctuation of the cathode potential. (authors)
Energy Technology Data Exchange (ETDEWEB)
Glyavin, M. Yu., E-mail: glyavin@appl.sci-nnov.ru; Denisov, G. G.; Zapevalov, V. E. [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Gycom Ltd., Nizhny Novgorod (Russian Federation); Chirkov, A. V.; Fokin, A. P.; Kholoptsev, V. V.; Kuftin, A. N.; Luchinin, A. G.; Golubyatnikov, G. Yu.; Malygin, V. I.; Morozkin, M. V.; Manuilov, V. N.; Proyavin, M. D.; Sedov, A. S.; Tsvetkov, A. I. [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Sokolov, E. V.; Tai, E. M. [Gycom Ltd., Nizhny Novgorod (Russian Federation)
2015-05-15
A 263 GHz continuous-wave (CW) gyrotron was developed at the IAP RAS for future applications as a microwave power source in Dynamic Nuclear Polarization / Nuclear magnetic resonance (DNP/NMR) spectrometers. A new experimental facility with a computerized control was built to test this and subsequent gyrotrons. We obtained the maximum CW power up to 1 kW in the 15 kV/0.4 A operation regime. The power about 10 W, which is sufficient for many spectroscopic applications, was realized in the low current 14 kV/0.02 A regime. The possibility of frequency tuning by variation of the coolant temperature about 4 MHz/1 °C was demonstrated. The spectral width of the gyrotron radiation was about 10{sup −6}.
Design and operation of 140 GHz gyrotron oscillators for power levels up to 1 MW CW
Energy Technology Data Exchange (ETDEWEB)
Jory, H.; Bier, R.; Craig, L.J.; Felch, K.; Ives, L.; Lopez, N.; Spang, S.
1986-12-01
Varian has designed and tested 140 GHz gyrotron oscillators that have generated output powers of 100 kW CW and 200 kW for 1 ms pulses. Upcoming tubes will be designed to operate at power levels of 200 kW CW and ultimately up to 1 MW CW. The important design considerations which are addressed in the higher power tubes include the design of the electron gun, interaction circuit, and output window. These issues will be discussed and the results of the earlier 140 GHz gyrotron work at Varian will be summarized.
Gyrotrons for High-Power Terahertz Science and Technology at FIR UF
Idehara, Toshitaka
2016-01-01
In this paper, we present the recent progress in the development of a series of gyrotrons at FIR UF that have opened the road to many novel applications in the high-power Terahertz science and technology. The current status of the research in this actively developing field is illustrated by the most representative examples in which the developed gyrotrons are used as powerful and frequency tunable sources of coherent radiation operating in a CW regime. Among them are high-precision spectroscopic techniques (most notably DNP-NMR, ESR, XDMR, and studies of the hyperfine splitting of the energy levels of positronium), treatment and characterization of advanced materials, new medical technologies.
Bennett, Charles L.
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.
A Fully-Sealed Carbon-Nanotube Cold-Cathode Terahertz Gyrotron
Yuan, Xuesong; Zhu, Weiwei; Zhang, Yu; Xu, Ningsheng; Yan, Yang; Wu, Jianqiang; Shen, Yan; Chen, Jun; She, Juncong; Deng, Shaozhi
2016-09-01
Gigahertz to terahertz radiation sources based on cold-cathode vacuum electron technology are pursued, because its unique characteristics of instant switch-on and power saving are important to military and space applications. Gigahertz gyrotron was reported using carbon nanotube (CNT) cold-cathode. It is reported here in first time that a fully-sealed CNT cold-cathode 0.22 THz-gyrotron is realized, typically with output power of 500 mW. To achieve this, we have studied mechanisms responsible for CNTs growth on curved shape metal surface, field emission from the sidewall of a CNT, and crystallized interface junction between CNT and substrate material. We have obtained uniform growth of CNTs on and direct growth from cone-cylinder stainless-steel electrode surface, and field emission from both tips and sidewalls of CNTs. It is essential for the success of a CNT terahertz gyrotron to have such high quality, high emitting performance CNTs. Also, we have developed a magnetic injection electron gun using CNT cold-cathode to exploit the advantages of such a conventional gun design, so that a large area emitting surface is utilized to deliver large current for electron beam. The results indicate that higher output power and higher radiation frequency terahertz gyrotron may be made using CNT cold-cathode electron gun.
Efficient Low-Voltage Operation of a CW Gyrotron Oscillator at 233 GHz.
Hornstein, Melissa K; Bajaj, Vikram S; Griffin, Robert G; Temkin, Richard J
2007-02-01
The gyrotron oscillator is a source of high average power millimeter-wave through terahertz radiation. In this paper, we report low beam power and high-efficiency operation of a tunable gyrotron oscillator at 233 GHz. The low-voltage operating mode provides a path to further miniaturization of the gyrotron through reduction in the size of the electron gun, power supply, collector, and cooling system, which will benefit industrial and scientific applications requiring portability. Detailed studies of low-voltage operation in the TE(2) (,) (3) (,) (1) mode reveal that the mode can be excited with less than 7 W of beam power at 3.5 kV. During CW operation with 3.5-kV beam voltage and 50-mA beam current, the gyrotron generates 12 W of RF power at 233.2 GHz. The EGUN electron optics code describes the low-voltage operation of the electron gun. Using gun-operating parameters derived from EGUN simulations, we show that a linear theory adequately predicts the low experimental starting currents.
Development program for a 200 kW, cw gyrotron. Final report
Energy Technology Data Exchange (ETDEWEB)
DeHope, W.J.; Ferguson, P.E.; Hart, S.L.; Matranga, V.A.; Sandoval, J.J.; Schmitt, M.J.; Tancredi, J.J.; Wozniak, M.A.
1984-02-01
Development of a millimeter-wave device to produce 200 kW of continuous wave power at 60 GHz is described. The device, a gyrotron oscillator, is intended for electron-cyclotron heating of fusion plasmas. The design philosophy is herein discussed and experimental results, both diagnostic and long pulse, are given.
Phononic High Harmonic Generation
Ganesan, Adarsh; 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. Subsequently, the down-conversion of second harmonic phonons into first harmonic phonons and conversion of first and second harmonic phonons into third harmonic phonons occur. On the similar lines, an eventual conversion of third harmonic phonons to high orders is also observed to commence. This surprising physical pathway for phononic low-order to high-order harmonic conversion may find general relevance to other physical systems.
Energy Technology Data Exchange (ETDEWEB)
Singh, Ashutosh, E-mail: asingh.rs.ece@iitbhu.ac.in [Faculty of Physical Sciences, Institute of Natural Sciences and Humanities, Shri Ramswaroop Memorial University, Lucknow-Deva Road, Uttar Pradesh 225003 (India); Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Jain, P. K. [Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)
2015-09-15
In this paper, the effects of electron beam parameters and velocity spread on the RF behavior of a metallic photonic band gap (PBG) cavity gyrotron operating at 35 GHz with TE{sub 041}–like mode have been theoretically demonstrated. PBG cavity is used here to achieve a single mode operation of the overmoded cavity. The nonlinear time-dependent multimode analysis has been used to observe the beam-wave interaction behavior of the PBG cavity gyrotron, and a commercially available PIC code “CST Particle Studio” has been reconfigured to obtain 3D simulation results in order to validate the analytical values. The output power for this typical PBG gyrotron has been obtained ∼108 kW with ∼15.5% efficiency in a well confined TE{sub 041}–like mode, while all other competing modes have significantly low values of power output. The output power and efficiency of a gyrotron depend highly on the electron beam parameters and velocity spread. The influence of several electron beam parameters, e.g., beam voltage, beam current, beam velocity pitch factor, and DC magnetic field, on the PBG gyrotron operations has been investigated. This study would be helpful in optimising the electron beam parameters and estimating accurate RF output power of the high frequency PBG cavity based gyrotron oscillators.
Status of the development of the EU 170 GHz/1 MW/CW gyrotron
Energy Technology Data Exchange (ETDEWEB)
Pagonakis, Ioannis Gr., E-mail: ioannis.pagonakis@kit.edu [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Albajar, Ferran [The European Joint Undertaking for ITER and The Development of Fusion Energy, Barcelona (Spain); Alberti, Stefano [École Polytechnique Fédérale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), Lausanne (Switzerland); Avramidis, Konstantinos [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Bonicelli, Tullio [The European Joint Undertaking for ITER and The Development of Fusion Energy, Barcelona (Spain); Braunmueller, Falk [École Polytechnique Fédérale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), Lausanne (Switzerland); Bruschi, Alex [Plasma Physics Institute, National Research Council of Italy, Milano (Italy); Chelis, Ioannis [School of Electrical and Computer Engineering, National Technical University of Athens (Greece); Cismondi, Fabio [The European Joint Undertaking for ITER and The Development of Fusion Energy, Barcelona (Spain); Gantenbein, Gerd [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Hermann, Virgile [Thales Electron Devices (TED), Vélizy-Villacoublay (France); Hesch, Klaus [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Hogge, Jean-Philippe [École Polytechnique Fédérale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), Lausanne (Switzerland); Jelonnek, John; Jin, Jianbo; Illy, Stefan [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Ioannidis, Zisis C. [Faculty of Physics, National and Kapodistrian University of Athens (Greece); Kobarg, Thorsten [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); and others
2015-10-15
The progress in the development of the European 170 GHz, 1 MW/CW gyrotron for electron cyclotron heating & current drive (ECH&CD) on ITER is reported. A continuous wave (CW) prototype is being manufactured by Thales Electron Devices (TED), France, while a short-pulse (SP) prototype gyrotron is in parallel under manufacture at Karlsruhe Institute of Technology (KIT), with the purpose of validating the design of the CW industrial prototype components. The fabrication of most of the sub-assemblies of the SP prototype has been completed. In a first step, an existing magnetron injection gun (MIG) available at KIT was used. Despite this non-ideal configuration, the experiments provided a validation of the design, substantiated by an excellent agreement with numerical simulations. The tube, operated without a depressed collector, is able to produce more than 1 MW of output power with efficiency in excess of 30%, as expected, and compatible with the ITER requirements.
Development and simulation of RF components for high power millimeter wave gyrotrons
Energy Technology Data Exchange (ETDEWEB)
Pereyaslavets, M.; Sato, M.; Shimozuma, T.; Takita, Y.; Idei, H.; Kubo, S.; Ohkubo, K.; Hayashi, K.
1996-11-01
To test gyrotron RF components, efficient low-power generators for rotating high-order modes of high purity are necessary. Designs of generators for the TE{sub 15,3} mode at 84 GHz and for the TE{sub 31,8} mode at 168 GHz are presented and some preliminary test results are discussed. In addition, Toshiba gyrotron cavities at 168 GHz were analyzed for leakage of RF power in the beam tunnel. To decrease RF power leakage, the declination angle of the cut-off cavity cross section has to be decreased. A TE{sub 15,3} waveguide nonlinear uptaper is analyzed at 84 GHz as well as 168 GHz uptapers. Since the calculated conversion losses are slightly higher than designed value, an optimization of those uptapers may be required. (author)
太赫兹回旋管研究进展%Development of Terahertz Gyrotrons
Institute of Scientific and Technical Information of China (English)
鄢扬; 傅文杰
2013-01-01
回旋管是一种基于电子回旋谐振受激辐射的快波器件,是目前太赫兹波段输出功率和效率最高的重要器件,本文给出了目前国内外太赫兹回旋管技术的发展状况,分析了太赫兹回旋管的特点和应用前景.%Gyrotrons are fast-wave vacuum electron devices based on the stimulated radiation, of electron cyclotron resonance. They are able to deliver powerful radiation in terahertz frequency bands with high efficiency. In this paper, the current status and development of terahertz gyrotrons are reviewed, the characteristics and prospective applications are discussed.
Gyrotrons for High-Power Terahertz Science and Technology at FIR UF
Idehara, Toshitaka; Sabchevski, Svilen Petrov
2016-10-01
In this review paper, we present the recent progress in the development of a series of gyrotrons at the Research Center for Development of Far-Infrared Region, University of Fukui, that have opened the road to many novel applications in the high-power terahertz science and technology. The current status of the research in this actively developing field is illustrated by the most representative examples in which the developed gyrotrons are used as powerful and frequency-tunable sources of coherent radiation operating in a continuous-wave regime. Among them are high-precision spectroscopic techniques (most notably dynamic nuclear polarization-nuclear magnetic resonance, electron spin resonance, X-ray detected magnetic resonance, and studies of the hyperfine splitting of the energy levels of positronium), treatment and characterization of advanced materials, and new medical technologies.
Damyanova, M.; Sabchevski, S.; Zhelyazkov, I.; Vasileva, E.; Balabanova, E.; Dankov, P.; Malinov, P.
2016-05-01
Powerful gyrotrons are necessary as sources of strong microwaves for electron cyclotron resonance heating (ECRH) and electron cyclotron current drive (ECCD) of magnetically confined plasmas in various reactors (most notably ITER) for controlled thermonuclear fusion. Adequate physical models and efficient problem-oriented software packages are essential tools for numerical studies, analysis, optimization and computer-aided design (CAD) of such high-performance gyrotrons operating in a CW mode and delivering output power of the order of 1-2 MW. In this report we present the current status of our simulation tools (physical models, numerical codes, pre- and post-processing programs, etc.) as well as the computational infrastructure on which they are being developed, maintained and executed.
Gyrotrons for High-Power Terahertz Science and Technology at FIR UF
Idehara, Toshitaka; Sabchevski, Svilen Petrov
2017-01-01
In this review paper, we present the recent progress in the development of a series of gyrotrons at the Research Center for Development of Far-Infrared Region, University of Fukui, that have opened the road to many novel applications in the high-power terahertz science and technology. The current status of the research in this actively developing field is illustrated by the most representative examples in which the developed gyrotrons are used as powerful and frequency-tunable sources of coherent radiation operating in a continuous-wave regime. Among them are high-precision spectroscopic techniques (most notably dynamic nuclear polarization-nuclear magnetic resonance, electron spin resonance, X-ray detected magnetic resonance, and studies of the hyperfine splitting of the energy levels of positronium), treatment and characterization of advanced materials, and new medical technologies.
Upgrade of a 30 kV/10 mA anode power supply for triode type gyrotron
Energy Technology Data Exchange (ETDEWEB)
Siravo, Ugo, E-mail: ugo.siravo@epfl.ch; Alberti, Stefano; Dubray, Jérémie; Fasel, Damien; Hogge, Jean-Philippe; Marlétaz, Blaise; Marmillod, Philippe; Perez, Albert; Silva, Miguel
2015-10-15
Highlights: • Triode type gyrotron is fed by 3 power supplies: the main, an anode PS(APS) and a heater. • This paper presents the upgrade of 3APS, supplied in 1999, that never fulfilled the specs. • The new working principle is very efficient, easy to implement, for a minimal cost. • Upgraded APS provides extended modulation capabilities, no overshoot and lowerripple. • This upgrade will allow exploring new operation regimes for the 3 TCV X3 gyrotrons. - The RF power of a gyrotron with a triode type magnetron-injection-gun (MIG) can be directly controlled via the voltage applied between its anode and its cathode. Hence, the performance of this type of gyrotron relies directly on the possibilities offered by the power supply controlling the anode to cathode voltage. For a system of gyrotrons connected to the same main high-voltage power supply, with a triode MIG one has the additional advantage of independently controlling each individual gyrotron. This paper presents the modifications brought to the three existing 30 kV/10 mA anode power supplies connected to the 500 kW/118 GHz/2s X3 gyrotrons operated on the TCV Tokamak. The new working principle based on phase-shift modulation (PSM) is described in detail. Experimental results obtained on dummy load are compared to simulations performed during the design phase. With respect to the initial working principle, the modulation frequency capability has been increased by a factor 10 reaching more than 5 kHz, whereas the output voltage ripple as well as the overshoot/undershoot have been significantly reduced.
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.
Experimental Study Of A 1.5-mw, 110-ghz Gyrotron Oscillator
Anderson, J P
2005-01-01
This thesis reports the design, construction and testing of a 1.5 MW, 110 GHz gyrotron oscillator. This high power microwave tube has been proposed as the next evolutionary step for gyrotrons used to provide electron cyclotron heating required in fusion devices. A short pulse gyrotron based on the industrial tube design was built at MIT for experimental studies. The experiments are the first demonstration of such high powers at 110 GHz. Using a 96 kV, 40 A electron beam, over 1.4 MW was axially extracted in the design (TE22,6) mode in 3 μs pulses, corresponding to a microwave efficiency of 37%. The beam alpha, the ratio of transverse to axial velocity in the electron beam, was measured with a probe. At the high efficiency operating point the beam alpha was measured as 1.33. This value of alpha is less than the design value of 1.4, possibly accounting for the slightly reduced experimental efficiency. The output power and efficiency, as a function of magnetic field, beam voltage, and beam current, are in...
Batanov, German M.; Borzosekov, Valentin D.; Golberg, Dmitri; Iskhakova, Ludmila D.; Kolik, Leonid V.; Konchekov, Evgeny M.; Kharchev, Nikolai K.; Letunov, Alexander A.; Malakhov, Dmitry V.; Milovich, Filipp O.; Obraztsova, Ekaterina A.; Petrov, Alexander E.; Ryabikina, Irina G.; Sarksian, Karen A.; Stepakhin, Vladimir D.; Skvortsova, Nina N.
2016-01-01
We introduce an approach toward the synthesis of micro- and nanostructures under nonequilibrium microwave discharges within metal-dielectric powder mixtures induced by powerful microwave gyrotron radiation. A new plasma-chemical reactor capable of sustaining a discharge regime with an afterglow phase of an order of magnitude longer than the gyrotron pulse duration was constructed for these experiments. In the nonequilibrium conditions of such a discharge, plasma-induced exothermic chemical reactions leading to the synthesis of various compounds were initiated. The synthesized structures were deposited on the reactor walls and on the impurity particles within the reactor. This method was tested under gyrotron-initiated discharges within various metal-dielectric powder mixtures of titanium-boron, molybdenum-boron, titanium-silicon-boron, molybdenum-boron nitride, molybdenum-tungsten-boron nitride, and so on. Depending on the powder mixture composition, reactor atmosphere, and other parameters, micro- and nanosized particles of boron nitride, titanium diboride, molybdenum boride, titanium boride, molybdenum, and molybdenum oxide, were synthesized, detected, and analyzed.
Shunt Active Filter in Damping Harmonics Propagation
Directory of Open Access Journals (Sweden)
BERBAOUI, B.
2010-08-01
Full Text Available This paper deals with a hybrid shunt active power filter applied on 500 kV HVDC, after a description of the causes and effects harmonic pollution which may damage equipments and interrupt electric power customers service; in this paper we present the deferent solutions of this problem among one has to study the two most recent types of filtering: passive and hybrid filter. The hybrid filter consists of active filter connected in shunt with passive filter. The hybrid shunt active filter proposed is based on three levels PWM inverter and characterized by detecting the harmonic current flowing into the passive filter and controlled by notch algorithm. This structure has been applied on a test HVDC power system, is presented as a technical solution makes it possible to eliminate the disadvantages from passive filtering, and also economic price of active filtering part. The simulation results justified the effectiveness of this type of filter face of the classic passive filter.
Laser second harmonic generation in a magnetoplasma assisted by an electrostatic wave
Tyagi, Yachna; Tripathi, Deepak; Walia, Keshav
2017-04-01
A laser produced plasma, and an electrostatic wave, helps to generate a strong harmonic radiation. The electrostatic wave assists k matching and contributes to non-linear coupling. In the case of the Bernstein wave assisted second harmonic, the frequency of the second harmonic is shifted from the laser second harmonic by electron cyclotron frequency. The lower hybrid wave (LHW) assisted second harmonic has frequency slightly shifted from the laser second harmonic. The upper hybrid wave (UHW) assisted second harmonic has frequency shifted by an amount ω that lies between max( ω c , ω p ) and ω U H . At a 0 = 0.1 and n ω , k → / n0 0 = 0.1, the normalized amplitude value the of electrostatic wave assisted second harmonic is quite high near the upper hybrid resonance. The effect of increasing ω c / ω p increases the max value of normalized amplitude.
Energy Technology Data Exchange (ETDEWEB)
Wang, He, E-mail: wangh@swip.ac.cn; Rao, Jun; Huang, Mei; Zhou, Jun; Wang, Chao; Kang, Zihua; Wang, Mingwei; Feng, Kun; Chen, Gangyu; Lu, Bo; Wang, Jieqiong
2015-12-15
Highlights: • A test stand for the test of gyrotron is introduced. • Test results show that the output power of gyrotron has a close relation to the high voltage, magnet current and heater power. • The measurement method of operation frequency and output power of gyrotron is introduced. - Abstract: To obtain the optimum operation status of gyrotrons, it is necessary to commissioning the gyrotrons before EC wave injected into plasma for ECRH system on HL-2A tokamak. A test stand has been set up for conditioning the 0.5 MW/68 GHz/1.0 s gyrotrons. The specific test results of gyrotrons are described and discussed in this paper, which include measuring the beam profile by using burn paper at the outlet of MOU and calorimetric dummy load, testing the maximum output power and pulse width on dummy load and getting the dependence between output power and magnetic field current, filament power and high voltage powers. Meanwhile, the operation frequency of gyrotron is also measured in the test.
Frequency Adaptive Selective Harmonic Control for Grid-Connected Inverters
DEFF Research Database (Denmark)
Yang, Yongheng; Zhou, Keliang; Wang, Huai
2015-01-01
SHC scheme consists of multiple parallel recursive (nk±m)-order (k = 0, 1, 2, . . ., and m ≤ n/2) harmonic control modules with independent control gains, which can be optimally weighted in accordance with the harmonic distribution. The hybrid SHC thus offers an optimal trade-off among cost...
Experimental Research on a 1.5 MW, 110 GHz Gyrotron with a Smooth Mirror Internal Mode Converter
Tax, D. S.; Mastovsky, I.; Shapiro, M. A.; Temkin, R. J.; Torrezan, A. C.
2010-11-01
Megawatt gyrotrons are important for electron cyclotron heating (ECH) of fusion plasmas, including ITER. These gyrotrons should operate with high efficiency to reduce the prime power required and to ensure good reliability. The gyrotron efficiency is affected both by the physical principles that govern the device and the performance of components like the internal mode converter (IMC), which must convert the electromagnetic cavity mode into a Gaussian beam. An IMC consisting of a helically-cut launcher and three smooth curved mirrors, which is less susceptible to alignment errors than an IMC using mirrors with phase correcting surfaces, was recently tested on a 1.5 MW, 110 GHz, 3μs pulsed gyrotron operating in the TE22,6 mode, and an output beam with 95.8 ± 0.5 % Gaussian beam content was measured in both hot and cold tests. We are also examining the issue of mode competition in the gyrotron, which can limit the achievable output power and efficiency. The sequence of competing modes excited during the rise time of the voltage pulse has been measured and results are compared with the numerical simulation code MAGY. These results should provide a good test of the accuracy of the code.
500-fold enhancement of in situ 13C liquid state NMR using gyrotron-driven temperature-jump DNP
Yoon, Dongyoung; Soundararajan, Murari; Caspers, Christian; Braunmueller, Falk; Genoud, Jérémy; Alberti, Stefano; Ansermet, Jean-Philippe
2016-09-01
A 550-fold increase in the liquid state 13C NMR signal of a 50 μL sample was obtained by first hyperpolarizing the sample at 20 K using a gyrotron (260 GHz), then, switching its frequency in order to apply 100 W for 1.5 s so as to melt the sample, finally, turning off the gyrotron to acquire the 13C NMR signal. The sample stays in its NMR resonator, so the sequence can be repeated with rapid cooling as the entire cryostat stays cold. DNP and thawing of the sample are performed only by the switchable and tunable gyrotron without external devices. Rapid transition from DNP to thawing in one second time scale was necessary especially in order to enhance liquid 1H NMR signal.
General -Harmonic Blaschke Bodies
Indian Academy of Sciences (India)
Yibin Feng; Weidong Wang
2014-02-01
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. In particular, we obtain the extreme values concerning the volume and the -dual geominimal surface area of this new notion.
170 GHz回旋管电子枪的设计%Design of the magnetron injection gun for 170 GHz gyrotron
Institute of Scientific and Technical Information of China (English)
曾旭; 王峨锋; 刘本田; 李志良; 冯进军
2013-01-01
A 170 GHz gryotron is an ideal power source for the Electron Cyclotron Resonance Heating (ECRH) in the plasma fusion. The required output power from a single gyrotron tube at 170 GHz operating frequency for ECRH application is 1 MW or more. For generating the high output power,a Magnetron Injection Gun(MIG) which can provide the electron beam with large enough transverse energy for interacting with the transverse filed of the electromagnetic wave is designed. Ideal parameters of the double-anode MIG are obtained according to the adiabatic compression theory and the correlative simulation software. The designed MIG can provide the necessary beams for the 170 GHz fundamental harmonic gyrotron under 80 kV of voltage and 40 A of current with the guidance center radius of 8.27 mm and the pitch factor of 1.5.% 170 GHz回旋管是等离子体核聚变中电子回旋谐振加热的理想功率源，在功率上要求具有1 MW以上的输出功率。要产生这么大的输出功率，就需要具有足够大横向能量的电子注与高频场的横向电场进行互作用，因此要对电子枪进行专门的设计。利用绝热压缩理论及相关的仿真软件对双阳极磁控注入电子枪进行了设计，得到了较好的电子注参数。所设计的电子枪能在工作电压80 kV、工作电流40 A 的条件下为170 GHz 基波回旋管提供所需的回旋电子注，其引导中心半径为8.27 mm，横纵速度比1.5。
Design of the all solid high-voltage power supply for a gyrotron body
Energy Technology Data Exchange (ETDEWEB)
Rao, Yihua [School of Mathematics and Physics, University of South China, Hengyang, 421001 (China); Chen, Wenguang, E-mail: 430000485393@usc.edu.cn [School of Electrical Engineering, University of South China, Hengyang, 421001 (China); Hu, Bo [School of Electrical Engineering, University of South China, Hengyang, 421001 (China); Rao, Jun; Huang, Mei; Kang, Zihua; Feng, Kun [Southwestern Institute of Physics, Chengdu, 610041 (China); Huang, Jiaqi [School of Electrical Engineering, University of South China, Hengyang, 421001 (China)
2017-04-15
Highlights: • Completed design of all solid-state high-voltage power supply for gyrotron body on HL-2M ECRH. • Consist of 58 PSM modules and one BUCK module, controlled by DSP system. • Fabricated full voltage 35 kV, 200 mA BPS and tested in dummy load. • The BPS can operate in three modes: single pulse mode, multi-pulse modulation mode and the six-level preset mode. - Abstract: Gyrotron plays an important role in the research of electron cyclotron resonance heating (ECRH) on Tokomak. The high-frequency switched power supply technology and pulse step modulation (PSM) technology are used in the development of the all solid high-voltage body power supply (BPS) for 1 MW/105 GHz Gyrotron on ECRH system. Firstly, the basic structure of the BPS and its control system are introduced. Secondly, the software control algorithm of voltage stabilization and modulate method are developed. Finally, the design is verified by the experiments. The experimental results of the single pulse mode, the multi-pulse modulation mode and the six-level preset mode, are shown. The output voltage of the power supply can reach 35 kV and the current at about 200 mA, which are adjustable in the full range. The maximum modulation frequency can reach 1 kHz and the front edge of the pulse can be adjust from 0 to 3 ms and the accuracy of the output voltage is less than 100 V. The results show that the control method is feasible and can be applied to other high power microwave sources.
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.
Design of a system for conversion of gyrotron output into a gaussian beam
Energy Technology Data Exchange (ETDEWEB)
Ogawa, I. [Faculty of Engineering, Fukui Univ., Fukui (Japan); Idehara, T.; Sabchevski, S.; Glyavin, M.; Mitsudo, S. [Research Center for Development of Far-Infrared Region, Fukui Univ., Fukui (Japan); Sato, M.; Kawahata, K. [National Inst. for Fusion Science, Toki, Gifu (Japan); Brand, G.F. [School of Physics, Univ. of Sydney, NSW (Australia)
2000-03-01
A quasi-optical system consisting of a quasi-optical antenna, two ellipsoidal mirrors and a filter to block sidelobes can convert four TE{sub 1n} mode outputs of the Gyrotron FU IVA into gaussian-like beams with waist size of 16.3 mm. This system can convert three TE{sub 0n} mode outputs into bigaussian-like beams with waist size of 23.5 mm in width and 16.4 mm in length. (author)
Test of a two-dimensionally focusing quasi-optical antenna using a gyrotron
Energy Technology Data Exchange (ETDEWEB)
Idehara, T.; Tatsukawa, T.; Brand, G.F.; Fekete, P.W.; Moore, K.J.
1989-05-01
A quasi-optical antenna having one elliptical reflector and one parabolic reflector has been built for millimeter wave scattering measurements on the TORTUS tokamak plasma at the University of Sydney. This letter reports the first demonstration of the properties of such an antenna using a gyrotron millimeter wave source. Its advantages are (1) good two-dimensional focusing (along the major radius and the toroidal directions) and (2) easy movement of the focus across the diameter of the plasma by changing the orientation of the parabolic reflector.
Coupler for coupling gyrotron whispering gallery mode RF into HE11 waveguide
Neilson, Jeffrey M
2015-02-24
A cylindrical waveguide with a mode converter transforms a whispering gallery mode from a gyrotron cylindrical waveguide with a helical cut launch edge to a quasi-Gaussian beam suitable for conveyance through a corrugated waveguide. This quasi-Gaussian beam is radiated away from the waveguide using a spiral cut launch edge, which is in close proximity to a first mode converting reflector. The first mode converting reflector is coupled to a second mode converting reflector which provides an output free-space HE11 mode wave suitable for direct coupling into a corrugated waveguide. The radiated beam produced at the output of the second mode converting reflector is substantially circular.
Institute of Scientific and Technical Information of China (English)
毛力; 刘兴阳; 沈明明
2011-01-01
In view of the advantages and disadvantages of K-harmonic means (KHM) and simulated annealing particle swarm optimization (SAPSO), a hybrid clustering algorithm combining KHM and SAPSO (KHM-SAPSO) was presented in this paper. With KHM, the particle swarm was divided into several sub-groups. Each particle iteratively updated its location based on its individual extreme value and the global extreme value of the sub-group it belonged to. With simulated annealing technique, the algorithm prevented premature convergence and improved the calculation accuracy. Using the databases of Iris, Zoo, Wine and Image Segmentation, and taking F-measure as a measure to evaluate the clustering effect, this paper qualified the new hybrid algorithm. Our experimental results indicated that the new algorithm significantly improved the clustering effectiveness by avoiding being trapped in local optimum, enhanced the global search capability while achieved faster convergence rate. This algorithm is adopted by an aquaculture water quality analysis system of a freshwater breeding base in Wuxi, which is running effectively.%针对K-调和均值和模拟退火粒子群聚类算法的优缺点,提出了1种融合K-调和均值和模拟退火粒子群的混合聚类算法.首先通过K-调和均值方法将粒子群分成若干个子群,每个粒子根据其个体极值和所在子种群的全局极值来更新位置.同时引入模拟退火思想,抑制了早期收敛,提高了计算精度.本文使用Iris、Zoo、Wine和Image Segmentation,4个数据库,以F-measure为评价聚类效果的标准,对混合聚类算法进行了验证.研究发现,该混合聚类算法可以有效地避免陷入局部最优,在保证收敛速度的同时增强了算法的全局搜索能力,明显改善了聚类效果.该算法目前已用于无锡一淡水养殖基地的水产健康养殖水质分析系统,运行效果良好.
Damyanova, M.; Sabchevski, S.; Zhelyazkov, I.; Vasileva, E.; Balabanova, E.; Dankov, P.; Malinov, P.
2016-03-01
Gyrotrons are the most powerful sources of coherent CW (continuous wave) radiation in the frequency range situated between the long-wavelength edge of the infrared light (far-infrared region) and the microwaves, i.e., in the region of the electromagnetic spectrum which is usually called the THz-gap (or T-gap), since the output power of other devices (e.g., solid-state oscillators) operating in this interval is by several orders of magnitude lower. In the recent years, the unique capabilities of the sub-THz and THz gyrotrons have opened the road to many novel and future prospective applications in various physical studies and advanced high-power terahertz technologies. In this paper, we present the current status and functionality of the problem-oriented software packages (most notably GYROSIM and GYREOSS) used for numerical studies, computer-aided design (CAD) and optimization of gyrotrons for diverse applications. They consist of a hierarchy of codes specialized to modelling and simulation of different subsystems of the gyrotrons (EOS, resonant cavity, etc.) and are based on adequate physical models, efficient numerical methods and algorithms.
Operation experiences of the super conducting magnet for a gyrotron of the JT-60U ECH system
Energy Technology Data Exchange (ETDEWEB)
Igarashi, Koichi; Seki, Masami; Shimono, Mitsugu; Terakado, Masayuki; Ishii, Kazuhiro; Takahashi, Masami [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment
2003-03-01
The JT-60U electron cyclotron heating (ECH) system can heat plasmas locally and drive a plasma current with four 1 MW-5 sec gyrotrons. The super conducting magnets (SCM) are required for oscillation of the gyrotron at a working frequency of 110 GHz. The SCM provides a high magnetic field of 4.5T at the cavity inside the gyrotron. This SCM system is characterized by 1) operation without liquid Helium owing to a 4K-refrigerator applied to the magnetic coils, 2) easy maintenance. Operational experiences about the SCM system through a long term experiment for a high power gyrotron are very valuable. According to those operational experiences, it is clarified the 4K-refrigerator should be renewed in order to keep low temperature of the SCM. It is also found that 200 hours or less are required for the super conducting condition (<5K) after long stopping time of the refrigerator up to 150 hours. This is useful information for making a plan about ECH experiments. (author)
Design of the Collective Thomson scattering (CTS) system by using 170-GHz gyrotron in the KSTAR
Park, Min; Kim, Sun-Ho; Kim, Sung-Kyu; Lee, Kyu-Dong; Wang, Son-Jong
2014-10-01
The physics of energetic ions is one of the primary subjects to be understood toward the realization of a nuclear fusion power plant. Collective Thomson scattering (CTS) offers the possibility to diagnose the fast ions and the alpha particles in burning plasmas. Spatially- and temporally-resolved one-dimensional velocity distributions of the fast ions can be obtained from the scattered radiation with fewer geometric constraints by utilizing millimeter waves from a high-power gyrotron as a probe beam. We studied the feasibility of CTS fast-ion measurements in the KSTAR by calculating the spectral density functions. Based on that, we suggest a design for the CTS system that uses the currently-operating 170-GHz gyrotron for electron cyclotron heating (ECH) and electron cyclotron current drive (ECCD) in the KSTAR. The CTS system is presented as two subsystems: the antenna system and the heterodyne receiver system. The design procedure for an off-axis ellipsoidal mirror is described, and the CTS system requirements are discussed.
High current multicharged metal ion source using high power gyrotron heating of vacuum arc plasma.
Vodopyanov, A V; Golubev, S V; Khizhnyak, V I; Mansfeld, D A; Nikolaev, A G; Oks, E M; Savkin, K P; Vizir, A V; Yushkov, G Yu
2008-02-01
A high current, multi charged, metal ion source using electron heating of vacuum arc plasma by high power gyrotron radiation has been developed. The plasma is confined in a simple mirror trap with peak magnetic field in the plug up to 2.5 T, mirror ratio of 3-5, and length variable from 15 to 20 cm. Plasma formed by a cathodic vacuum arc is injected into the trap either (i) axially using a compact vacuum arc plasma gun located on axis outside the mirror trap region or (ii) radially using four plasma guns surrounding the trap at midplane. Microwave heating of the mirror-confined, vacuum arc plasma is accomplished by gyrotron microwave radiation of frequency 75 GHz, power up to 200 kW, and pulse duration up to 150 micros, leading to additional stripping of metal ions by electron impact. Pulsed beams of platinum ions with charge state up to 10+, a mean charge state over 6+, and total (all charge states) beam current of a few hundred milliamperes have been formed.
Beam-wave interaction behavior of a 35 GHz metal PBG cavity gyrotron
Energy Technology Data Exchange (ETDEWEB)
Singh, Ashutosh, E-mail: asingh.rs.ece@iitbhu.ac.in [Faculty of Physical Sciences, Institute of Natural Sciences and Humanities Shri Ramswaroop Memorial University, Lucknow-Deva Road, Uttar Pradesh-225003 (India); Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi-221005 (India); Jain, P. K. [Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi-221005 (India)
2014-09-15
The RF behavior of a 35 GHz photonic band gap (PBG) cavity gyrotron operating in TE{sub 041}-like mode has been presented to demonstrate its single mode operation capability. In this PBG cavity gyrotron, the conventional tapered cylindrical cavity is replaced by a metal PBG cavity as its RF interaction structure. The beam-wave interaction behavior has been explored using time dependent multimode nonlinear analysis as well as through 3D PIC simulation. Metal PBG cavity is treated here similar to that of a conventional cylindrical cavity for the desired mode confinement. The applied DC magnetic field profile has been considered uniform along the PBG cavity length both in analysis as well as in simulation. Electrons energy and phase along the interaction length of the PBG cavity facilitates bunching mechanism as well as energy transfer phenomena from the electron beam to the RF field. The RF output power for the TE{sub 041}-like design mode as well as nearby competing modes have been estimated and found above to 100 kW in TE{sub 041}-like mode with ∼15% efficiency. Results obtained from the analysis and the PIC simulation are found in agreement within 8% variation, and also it supports the single mode operation, as the PBG cavity does not switch into other parasitic modes in considerably large range of varying DC magnetic field, contrary to the conventional cylindrical cavity interaction structure.
Conceptual designs of E × B multistage depressed collectors for gyrotrons
Wu, Chuanren; Pagonakis, Ioannis Gr.; Gantenbein, Gerd; Illy, Stefan; Thumm, Manfred; Jelonnek, John
2017-04-01
Multistage depressed collectors are challenges for high-power, high-frequency fusion gyrotrons. Two concepts exist in the literature: (1) unwinding the spent electron beam cyclotron motion utilizing non-adiabatic transitions of magnetic fields and (2) sorting and collecting the electrons using the E × B drift. To facilitate the collection by the drift, the hollow electron beam can be transformed to one or more thin beams before applying the sorting. There are many approaches, which can transform the hollow electron beam to thin beams; among them, two approaches similar to the tilted electric field collectors of traveling wave tubes are conceptually studied in this paper: the first one transforms the hollow circular electron beam to an elongated elliptic beam, and then the thin elliptic beam is collected by the E × B drift; the second one splits an elliptic or a circular electron beam into two arc-shaped sheet beams; these two parts are collected individually. The functionality of these concepts is proven by CST simulations. A model of a three-stage collector for a 170 GHz, 1 MW gyrotron using the latter approach shows 76% collector efficiency while taking secondary electrons and realistic electron beam characteristics into account.
The 5.8 T Cryogen-Free Gyrotron Superconducting Magnet System on HL-2A
Xia, Donghui; Huang, Mei; Zhou, Jun; Bai, Xingyu; Zheng, Tieliu; Rao, Jun; Zhuang, Ge
2014-04-01
A 5.8 T cryogen-free superconducting magnet (SCM) system with a warm bore hole of 160 mm in diameter, used for gyrotrons operating in the frequency range from 68 GHz to 140 GHz, is installed on the site of the HL-2A tokamak. The SCM consists of two separate solenoidal magnetic coils connected in series, a 4.2 K Gifford-McMahon (GM) refrigerator, a compressor, a coil power supply and two temperature monitors. The performance, test and preliminary experimental results of this SCM system are described in this paper. The magnetic field distribution was measured along the axis, and a dummy tube was used for adjusting the magnet system. Finally, the magnet was used for the operation of a 68 GHz/500 kW gyrotron, which is part of an electron cyclotron resonance heating (ECRH) system. With an additional auxiliary coil and after adjusting the magnet system, a maximum output power for the ECRH system of up to 400 kW was achieved.
Covariant harmonic oscillators and coupled harmonic oscillators
Han, Daesoo; Kim, Young S.; Noz, Marilyn E.
1995-01-01
It is shown that the system of two coupled harmonic oscillators shares the basic symmetry properties with the covariant harmonic oscillator formalism which provides a concise description of the basic features of relativistic hadronic features observed in high-energy laboratories. It is shown also that the coupled oscillator system has the SL(4,r) symmetry in classical mechanics, while the present formulation of quantum mechanics can accommodate only the Sp(4,r) portion of the SL(4,r) symmetry. The possible role of the SL(4,r) symmetry in quantum mechanics is discussed.
Hybrid undulator numerical optimization
Energy Technology Data Exchange (ETDEWEB)
Hairetdinov, A.H. [Kurchatov Institute, Moscow (Russian Federation); Zukov, A.A. [Solid State Physics Institute, Chernogolovka (Russian Federation)
1995-12-31
3D properties of the hybrid undulator scheme arc studied numerically using PANDIRA code. It is shown that there exist two well defined sets of undulator parameters which provide either maximum on-axis field amplitude or minimal higher harmonics amplitude of the basic undulator field. Thus the alternative between higher field amplitude or pure sinusoidal field exists. The behavior of the undulator field amplitude and harmonics structure for a large set of (undulator gap)/(undulator wavelength) values is demonstrated.
DFIG Harmonic Current Controlling with the Grid Low Harmonic Voltage
Directory of Open Access Journals (Sweden)
Huan Wang
2014-01-01
Full Text Available This study presents a vector control strategy based on stator harmonic current closed-loop, it adds individually the control loop about of each stator harmonic current to restrain the stator harmonic current, in order to meet the THD criteria. The control strategy of restraining the harmonic current presents the design of the stator harmonic current restrains the current controller. It influences the rotor voltage of the stator harmonic current restraining strategies.
Institute of Scientific and Technical Information of China (English)
G. Yu. YUSHKOV; K. P. SAVKIN; A. G. NIKOLAEV; E. M. OKS; A.V. VODOPYANOV; I. V. IZOTOV; D. A. MANSFELD
2011-01-01
A new method for the generation of high charged state metal ion beams is developed. This method is based on microwave heating of vacuum arc plasma in a magnetic trap under electron cyclotron resonance （ECR） conditions. Two gyrotrons for plasma heating were used, which were with the following parameters. The first is with a wave frequency of 37.5 GHz, a pulse duration of 1 ms and power of 100 kW, another is with 75 GHz, 0.15 ms and 400 kW. Two different magnetic traps were considered for vacuum arc plasma confinement. The first one is a simple mirror trap. Such system was already investigated and could provide high charge state ions. The second trap was with a cusp magnetic field configuration with native ＂minimum-B＂ field structure. Two different ways of metal plasma injection into the magnetic trap were used. The first one is an axial injection from an arc source located out of the trap, and the second is a radial injection from four arc sources mounted at the center of the trap. Both traps provide up to 200 eMA of ion beam current for platinum ions with highest charge state 10＋. Ion beams were successfully extracted from the plasma and accelerated by a voltage of up to 20 kV.
Velocity-space tomography of fusion plasmas by collective Thomson scattering of gyrotron radiation
DEFF Research Database (Denmark)
Salewski, Mirko; Jacobsen, A.S.; Jensen, Thomas;
2016-01-01
We propose a diagnostic capable of measuring 2D fast-ion velocity distribution functions 푓2퐷푣 in the MeV-range in magnetized fusion plasmas. Today velocity-space tomography based on fast-ion D훼 spectroscopy is regularly used to measure 푓2퐷푣 for ion energies below 100 keV. Unfortunately, the signal......-tonoise ratio becomes fairly low for MeV-range ions. Ions at any energy can be detected well by collective Thomson scattering of mm-wave radiation from a high-power gyrotron. We demonstrate how collective Thomson scattering can be used to measure 푓2퐷푣 in the MeV-range in reactor relevant plasmas...
Kalaria, P. C.; Avramidis, K. A.; Franck, J.; Gantenbein, G.; Illy, S.; Pagonakis, I. Gr.; Thumm, M.; Jelonnek, J.
2016-09-01
High frequency (>230 GHz) megawatt-class gyrotrons are planned as RF sources for electron cyclotron resonance heating and current drive in DEMOnstration fusion power plants (DEMOs). In this paper, for the first time, a feasibility study of a 236 GHz DEMO gyrotron is presented by considering all relevant design goals and the possible technical limitations. A mode-selection procedure is proposed in order to satisfy the multi-frequency and frequency-step tunability requirements. An effective systematic design approach for the optimal design of a gradually tapered cavity is presented. The RF-behavior of the proposed cavity is verified rigorously, supporting 920 kW of stable output power with an interaction efficiency of 36% including the considerations of realistic beam parameters.
Kumar, Anil; Kumar, Nitin; Singh, Udaybir; Khatun, Hasina; Vyas, V.; Sinha, A. K.
2012-04-01
In this paper thermal and structural analysis for 170 GHz, 1 MW gyrotron interaction cavity and the effect of structural deformation on beam wave interaction is presented. Finite element analysis codes ANSYS has been used for the thermal and structural analysis. Electromagnetic simulator-MAGIC, a Particle-in-Cell (PIC) code, has been used to carry out the effect of the radial expansion of the interaction cavity on beam wave interaction. The change in output power and resonant frequency for operating mode TE34,10 due to thermal expansion is 10 kW and 0.07 GHz, respectively. These values are under the tolerance limit of power and frequency of the gyrotron. The major variation is found in the power growth stability time.
Thumm, M K
2002-01-01
The possible applications of high-power millimeter (mm) and sub-mm waves from free-electron masers (FEMs) and gyro-devices span a wide range of technologies. The plasma physics community has already taken advantage of recent advances in applying high-power mm waves generated by long pulse or continuous wave (CW) gyrotron oscillators and short pulse very high-power FEMs in the areas of RF-plasma production, heating, non-inductive current drive, plasma stabilization and active plasma diagnostics for magnetic confinement thermonuclear fusion research, such as electron cyclotron resonance heating (28-170 GHz), electron cyclotron current drive , collective Thomson scattering , microwave transmission and heat-wave propagation experiments. Continuously frequency tunable FEMs could widen these fields of applications. Another important application of CW gyrotrons is industrial materials processing, e.g. sintering of high-performance functional and structural nanostructured ceramics. Sub-mm wave sources are employed in...
Energy Technology Data Exchange (ETDEWEB)
Hohmann, Manuel [Physikalisches Institut, Universitaet Tartu (Estonia)
2016-07-01
Tensor harmonics are a useful mathematical tool for finding solutions to differential equations which transform under a particular representation of the rotation group SO(3). In order to make use of this tool also in the setting of Finsler geometry, where the objects of relevance are d-tensors instead of tensors, we construct a set of d-tensor harmonics for both SO(3) and SO(4) symmetries and show how these can be used for calculations in Finsler geometry and gravity.
A New Harmonic Current Forecasting Method for HAPF of Micro-grid
Directory of Open Access Journals (Sweden)
LI Sheng-qing
2013-04-01
Full Text Available There are a lot of power quality problems such as a large number of harmonic, caused by quickly changing diverse types of loads and power resources in micro-grid. This paper proposed a hybrid active power filte (HAPF harmonic current prediction method based on the hybrid intelligent prediction model of Empirical Mode Decomposition (EMD and Intrinsic Mode Regression (SVR. This method Combine the EMD method and SVR module, First, the harmonic current is decomposed into every harmonic current using EMD method; Then using different kernel function in SVR module to predict different times harmonic currents at the next time; Finally, the predicted value of each harmonic weighted summation. Simulation results show that, this method can be well to improve the prediction performance.
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...
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.
Towards the optimization of the thermal–hydraulic performance of gyrotron collectors
Energy Technology Data Exchange (ETDEWEB)
Savoldi, Laura; Bertani, Cristina [Dipartimento Energia, Politecnico di Torino, 10129 Torino (Italy); Cau, Francesca; Cismondi, Fabio [F4E, Barcelona (Spain); Gantenbein, Gerd; Illy, Stefan [Karlsruhe Institute of Technology (KIT), Institute for Pulsed Power and Microwave Technology (IHM), Kaiserstr. 12, 76131 Karlsruhe (Germany); Monni, Grazia [Dipartimento Energia, Politecnico di Torino, 10129 Torino (Italy); Rozier, Yoann [Thales Electron Devices, 78141 Vélizy-Villacoublay (France); Zanino, Roberto, E-mail: roberto.zanino@polito.it [Dipartimento Energia, Politecnico di Torino, 10129 Torino (Italy)
2015-11-15
Different configurations of water-cooled Cu collector for gyrotrons are investigated using the StarCCM + CFD code, aimed at optimizing its thermal–hydraulic (TH) performance. Although the current collectors show a good performance, the collector can be subjected to transient heat loads, due to the spent electron beam, of up to several tens of MW/m{sup 2}, and there is an interest to increase the gyrotron output power in the future. Furthermore, an optimized cooling will lead to improved reliability and lifetime of the collector. Starting from a hypervapotron (HV)-like collector, characterized by 100+ deep rectangular cavities with aspect ratio (AR) = 3, we present in the first part of the paper a single-cavity steady-state parametric analysis of the effect of AR on the heat exhaust capabilities. The investigation is then extended to other collector designs, including circumferential ribs and dimples, in order to assess the options for further improvements of the TH performance. The peak Cu temperature is computed by the code and its minimization is the target of the present optimization exercise. A self-consistent estimate of the heat transfer coefficient between collector and coolant is also obtained, which could be useful for fatigue and lifetime assessments. In the second part of the paper the most promising collector geometries identified in the first part are analyzed in the case of a transient heat load (vertical sweeping), first at the level of a single spatial period of the collector structure, then at the full-collector level. The results of the TH transient analysis are compared with both the results of the first part and with the transient purely thermal analysis of the full collector, showing for all geometries considered in this study a room for cooling efficiency improvement with respect to the HV-like design with AR = 3, at least in the operating conditions considered for this study (V ∼ 4 m/s, almost 100 °C sub-cooling).
Energy Technology Data Exchange (ETDEWEB)
Savoldi, Laura; Bertani, Cristina [Dipartimento Energia, Politecnico di Torino (Italy); Cau, Francesca; Cismondi, Fabio [Fusion for Energy, Barcelona (Spain); Gantenbein, Gerd; Illy, Stefan [KIT, Karlsruhe (Germany); Monni, Grazia [Dipartimento Energia, Politecnico di Torino (Italy); Zanino, Roberto, E-mail: roberto.zanino@polito.it [Dipartimento Energia, Politecnico di Torino (Italy)
2015-11-15
The present gyrotron designs for EC plasma heating in nuclear fusion reactors require the safe exhaust of a power comparable to that injected into the plasma, in order to keep the maximum temperature below the acceptable value of 300 °C. In this paper, the commercial computational fluid dynamics (CFD) software STAR-CCM+{sup ®} is used to analyze the thermal performance of the annular copper collector of a 1 MW ITER gyrotron, equipped with a hypervapotron structure made of annular fins with rectangular cavities of aspect ratio (depth/width) = 3, cooled by highly subcooled (90–100 °C) pressurized water flowing at ∼4 m/s. It is assumed that the simple vertical sweeping strategy is used to reduce the very high peak heat flux on the collector (up to 30 MW/m{sup 2} transient, 5 MW/m{sup 2} time average), due to the spent electron beam. The 2D steady-state conjugate heat transfer problem is solved assuming azimuthal symmetry and accounting for 2-phase flow. The single-cavity flow and heat transfer problem is considered first, to optimize the mesh and the selection of the turbulence model. For the operating conditions considered in this paper, the full collector (100+ cavities) solution shows that boiling occurs only in a limited number of cavities close to the peaks of the heat flux, with the vapor remaining trapped in the bottom of the cavities, i.e. no full hypervapotron regime should be achieved in these operating conditions. The steady-state analysis allows the numerical evaluation of the heat transfer coefficients between Cu and water; these are then used as input for the simplified, purely thermal (solid only) analysis of the actual transient problem for the full collector. The results of the simplified model, which allows a huge reduction of the computational effort, are successfully benchmarked against those of a comprehensive thermal–hydraulic simulation. The computed peak Cu temperature is below the acceptable limit under the steady-state (time averaged
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.
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 arte
Gluck, P.; Krakower, Zeev
2010-01-01
We present a unit comprising theory, simulation and experiment for a body oscillating on a vertical spring, in which the simultaneous use of a force probe and an ultrasonic range finder enables one to explore quantitatively and understand many aspects of simple and damped harmonic motions. (Contains 14 figures.)
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 arte
Harmonization versus Mutual Recognition
DEFF Research Database (Denmark)
Jørgensen, Jan Guldager; Schröder, Philipp
with the opportunity to start export sales. In contrast, harmonization, in particular the prospect that one’s own national (but not the foreign) standard becomes the only globally accepted standard, opens the foreign market without balancing entry at home. We study these scenarios in a reduced form lobby game with two...
Institute of Scientific and Technical Information of China (English)
ZHAOZhen-gang
2005-01-01
We have constructed the positive definite metric matrixes for the bounded domains of Rn and proved an inequality which is about the Jacobi matrix of a harmonic mapping on a bounded domain of Rn and the metric matrix of the same bounded domain.
Harmonics in transmission power systems
DEFF Research Database (Denmark)
Wiechowski, Wojciech Tomasz
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....... It is concluded that since some background harmonic distortion is practically always present in the network, a method based on variation of harmonic values must be used. The incremental values of harmonic distortion will allow to verify the harmonic model, despite the existence of background harmonic distortion...... GPS-synchronized OMICRON CMC256 units. Two such units are installed at 400 kV substations at both ends of the disconnected line and a third unit is located at a substation in a distance of 80 km. Time domain "snap-shot" measurements of three-phase voltages and currents are synchronously taken for some...
Ginzburg, N. S.; Zotova, I. V.; Sergeev, A. S.; Zaslavsky, V. Yu.; Zheleznov, I. V.; Samsonov, S. V.; Mishakin, S. V.
2015-11-01
A time-domain self consistent theory of a gyrotron traveling wave tube with a helically corrugated operating waveguide has been developed. Based on this model, the process of short pulse amplification was studied in regimes of grazing and intersection of the dispersion curves of the electromagnetic wave and the electron beam. In the first case, the possibility of amplification without pulse form distortion was demonstrated for the pulse spectrum width of the order of the gain bandwidth. In the second case, when the electrons' axial velocity was smaller than the wave's group velocity, it was shown that the slippage of the incident signal with respect to the electron beam provides feeding of the signal by "fresh" electrons without initial modulation. As a result, the amplitude of the output pulse can exceed the amplitude of its saturated value for the case of the grazing regime, and, for optimal parameters, the peak output power can be even larger than the kinetic power of the electron beam.
Intense high-frequency gyrotron-based microwave beams for material processing
Energy Technology Data Exchange (ETDEWEB)
Hardek, T.W.; Cooke, W.D.; Katz, J.D.; Perry, W.L.; Rees, D.E.
1997-03-01
Microwave processing of materials has traditionally utilized frequencies in the 0.915 and 2.45 GHz regions. Microwave power sources are readily available at these frequencies but the relatively long wavelengths can present challenges in uniformly heating materials. An additional difficulty is the poor coupling of ceramic based materials to the microwave energy. Los Alamos National Laboratory scientists, working in conjunction with the National Center for Manufacturing Sciences (NCMS), have assembled a high-frequency demonstration processing facility utilizing gyrotron based RF sources. The facility is primarily intended to demonstrate the unique features available at frequencies as high as 84 GHz. The authors can readily provide quasi-optical, 37 GHz beams at continuous wave (CW) power levels in the 10 kW range. They have also provided beams at 84 GHz at 10 kW CW power levels. They are presently preparing a facility to demonstrate the sintering of ceramics at 30 GHz. This paper presents an overview of the present demonstration processing facility and describes some of the features they have available now and will have available in the near future.
Gyrotron-driven high current ECR ion source for boron-neutron capture therapy neutron generator
Skalyga, V.; Izotov, I.; Golubev, S.; Razin, S.; Sidorov, A.; Maslennikova, A.; Volovecky, A.; Kalvas, T.; Koivisto, H.; Tarvainen, O.
2014-12-01
Boron-neutron capture therapy (BNCT) is a perspective treatment method for radiation resistant tumors. Unfortunately its development is strongly held back by a several physical and medical problems. Neutron sources for BNCT currently are limited to nuclear reactors and accelerators. For wide spread of BNCT investigations more compact and cheap neutron source would be much more preferable. In present paper an approach for compact D-D neutron generator creation based on a high current ECR ion source is suggested. Results on dense proton beams production are presented. A possibility of ion beams formation with current density up to 600 mA/cm2 is demonstrated. Estimations based on obtained experimental results show that neutron target bombarded by such deuteron beams would theoretically yield a neutron flux density up to 6·1010 cm-2/s. Thus, neutron generator based on a high-current deuteron ECR source with a powerful plasma heating by gyrotron radiation could fulfill the BNCT requirements significantly lower price, smaller size and ease of operation in comparison with existing reactors and accelerators.
Energy Technology Data Exchange (ETDEWEB)
Ginzburg, N. S., E-mail: ginzburg@appl.sci-nnov.ru; Zaslavsky, V. Yu. [Institute of Applied Physics of the Russian Academy of Sciences, 46 Ul' yanov Str., 603950 Nizhny Novgorod (Russian Federation); Nizhny Novgorod State University, 23 Gagarin Ave., 603950 Nizhny Novgorod (Russian Federation); Zotova, I. V.; Sergeev, A. S.; Zheleznov, I. V.; Samsonov, S. V.; Mishakin, S. V. [Institute of Applied Physics of the Russian Academy of Sciences, 46 Ul' yanov Str., 603950 Nizhny Novgorod (Russian Federation)
2015-11-15
A time-domain self consistent theory of a gyrotron traveling wave tube with a helically corrugated operating waveguide has been developed. Based on this model, the process of short pulse amplification was studied in regimes of grazing and intersection of the dispersion curves of the electromagnetic wave and the electron beam. In the first case, the possibility of amplification without pulse form distortion was demonstrated for the pulse spectrum width of the order of the gain bandwidth. In the second case, when the electrons' axial velocity was smaller than the wave's group velocity, it was shown that the slippage of the incident signal with respect to the electron beam provides feeding of the signal by “fresh” electrons without initial modulation. As a result, the amplitude of the output pulse can exceed the amplitude of its saturated value for the case of the grazing regime, and, for optimal parameters, the peak output power can be even larger than the kinetic power of the electron beam.
Experimental results of the 140 GHz, 1 MW long-pulse gyrotron for W7-X
Koppenburg, K.; Arnold, A.; Borie, E.; Dammertz, G.; Giguet, E.; Heidinger, R.; Illy, S.; Kuntze, M.; Le Cloarec, G.; Legrand, F.; Leonhardt, W.; Lievin, C.; Neffe, G.; Piosczyk, B.; Schmid, M.; Thumm, M.
2003-02-01
Gyrotrons at high frequency with high output power are mainly developed for microwave heating and current drive in plasmas for thermonuclear fusion. For the stellarator Wendelstein 7-X now under construction at IPP Greifswald, Germany, a 10 MW ECRH system is foreseen. A 1 MW, 140 GHz long-pulse gyrotron has been designed and a pre-prototype (Maquette) has been constructed and tested in an European collaboration between FZK Karlsruhe, CRPP Lausanne, IPF Suttgart, IPP Greifswald, CEA Cadarache and TED Vélizy [1]. The cylindrical cavity is designed for operating in the TE28,8 mode. It is a standard tapered cavity with linear input downtaper and a non-linear uptaper. The diameter of the cylindrical part is 40.96 mm. The transitions between tapers and straight section are smoothly rounded to avoid mode conversion. The TE28,8-cavity mode is transformed to a Gaussian TEM0,0 output mode by a mode converter consisting of a rippled-wall waveguide launcher followed by a three mirror system. The output window uses a single, edge cooled CVD-diamond disk with an outer diameter of 106 mm, a window aperture of 88 mm and a thickness of 1.8 mm corresponding to four half wavelengths. The collector is at ground potential, and a depression voltage for energy recovery can be applied to the cavity and to the first two mirrors. Additional normal-conducting coils are employed to the collector in order to produce an axial magnetic field for sweeping the electron beam with a frequency of 7 Hz. A temperature limited magnetron injection gun without intermediate anode ( diode type ) is used. In short pulse operation at the design current of 40 A an output power of 1 MW could be achieved for an accelerating voltage of 82 kV without depression voltage and with a depression voltage of 25 kV an output power of 1.15 MW at an accelerating voltage of 84 kV has been measured. For these values an efficiency of 49% was obtained. At constant accelerating voltages, the output power did not change up to
Gyrotron-driven high current ECR ion source for boron-neutron capture therapy neutron generator
Energy Technology Data Exchange (ETDEWEB)
Skalyga, V., E-mail: skalyga.vadim@gmail.com [Institute of Applied Physics, RAS, 46 Ul’yanova st., 603950 Nizhny Novgorod (Russian Federation); Lobachevsky State University of Nizhny Novgorod (UNN), 23 Gagarina st., 603950 Nizhny Novgorod (Russian Federation); Izotov, I.; Golubev, S.; Razin, S. [Institute of Applied Physics, RAS, 46 Ul’yanova st., 603950 Nizhny Novgorod (Russian Federation); Sidorov, A. [Institute of Applied Physics, RAS, 46 Ul’yanova st., 603950 Nizhny Novgorod (Russian Federation); Lobachevsky State University of Nizhny Novgorod (UNN), 23 Gagarina st., 603950 Nizhny Novgorod (Russian Federation); Maslennikova, A. [Lobachevsky State University of Nizhny Novgorod (UNN), 23 Gagarina st., 603950 Nizhny Novgorod (Russian Federation); Nizhny Novgorod State Medical Academy, 10/1 Minina Sq., 603005 Nizhny Novgorod (Russian Federation); Volovecky, A. [Lobachevsky State University of Nizhny Novgorod (UNN), 23 Gagarina st., 603950 Nizhny Novgorod (Russian Federation); Kalvas, T.; Koivisto, H.; Tarvainen, O. [University of Jyvaskyla, Department of Physics, PO Box 35 (YFL), 40500 Jyväskylä (Finland)
2014-12-21
Boron-neutron capture therapy (BNCT) is a perspective treatment method for radiation resistant tumors. Unfortunately its development is strongly held back by a several physical and medical problems. Neutron sources for BNCT currently are limited to nuclear reactors and accelerators. For wide spread of BNCT investigations more compact and cheap neutron source would be much more preferable. In present paper an approach for compact D–D neutron generator creation based on a high current ECR ion source is suggested. Results on dense proton beams production are presented. A possibility of ion beams formation with current density up to 600 mA/cm{sup 2} is demonstrated. Estimations based on obtained experimental results show that neutron target bombarded by such deuteron beams would theoretically yield a neutron flux density up to 6·10{sup 10} cm{sup −2}/s. Thus, neutron generator based on a high-current deuteron ECR source with a powerful plasma heating by gyrotron radiation could fulfill the BNCT requirements significantly lower price, smaller size and ease of operation in comparison with existing reactors and accelerators.
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.
Second harmonic optical coherence tomography
Jiang,Yi; Tomov, Ivan; Wang, Yimin; Chen, Zhongping
2004-01-01
Second harmonic optical coherence tomography, which uses coherence gating of second-order nonlinear optical response of biological tissues for imaging, is described and demonstrated. Femtosecond laser pulses were used to excite second harmonic waves from collagen harvested from rat tail tendon and a reference nonlinear crystal. Second harmonic interference fringe signals were detected and used for image construction. Because of the strong dependence of second harmonic generation on molecular ...
Third harmonic generation of high power far infrared radiation in semiconductors
Energy Technology Data Exchange (ETDEWEB)
Urban, M. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)
1996-04-01
We investigated the third harmonic generation of high power infrared radiation in doped semiconductors with emphasis on the conversion efficiency. The third harmonic generation effect is based on the nonlinear response of the conduction band electrons in the semiconductor with respect to the electric field of the incident electromagnetic wave. Because this work is directed towards a proposed application in fusion plasma diagnostics, the experimental requirements for the radiation source at the fundamental frequency are roughly given as follows: a wavelength of the radiation at the fundamental frequency in the order of 1 mm and an incident power greater than 1 MW. The most important experiments of this work were performed using the high power far infrared laser of the CRPP. With this laser a new laser line was discovered, which fits exactly the source specifications given above: the wavelength is 676 {mu}m and the maximum power is up to 2 MW. Additional experiments were carried out using a 496 {mu}m laser and a 140 GHz (2.1 mm) gyrotron. The main experimental progress with respect to previous work in this field is, in addition to the use of a very high power laser, the possibility of an absolute calibration of the detectors for the far infrared radiation and the availability of a new type of detector with a very fast response. This detector made it possible to measure the power at the fundamental as well as the third harmonic frequency with full temporal resolution of the fluctuations during the laser pulse. Therefore the power dependence of the third harmonic generation efficiency could be measured directly. The materials investigated were InSb as an example of a narrow gap semiconductor and Si as standard material. The main results are: narrow gap semiconductors indeed have a highly nonlinear electronic response, but the narrow band gap leads at the same time to a low power threshold for internal breakdown, which is due to impact ionization. figs., tabs., refs.
Glyavin, M. Yu.; Kuntsevich, A. D.; Manuilov, V. N.
2015-01-01
We present the results of based on the PIC method numerical simulation of the dynamic processes of trapping of electrons into the adiabatic trap of a technological gyrotron for different configurations of the electric and magnetic fields in the electron beam formation region. The electrode geometry providing a low reflection coefficient of the magnetic mirror to suppress oscillatory modes in the space-charge cloud and ensure the stability of the electron beam with a high fraction of oscillatory energy in such a system has been found.
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.
Harmonization versus Mutual Recognition
DEFF Research Database (Denmark)
Jørgensen, Jan Guldager; Schröder, Philipp
The present paper examines trade liberalization driven by the coordination of product standards. For oligopolistic firms situated in separate markets that are initially sheltered by national standards, mutual recognition of standards implies entry and reduced profits at home paired......, harmonized standards may fail to harvest the full pro-competitive effects from trade liberalization compared to mutual recognition; moreover, the issue is most pronounced in markets featuring price competition....
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...
Development of Mode Conversion Waveguides at KIT
Directory of Open Access Journals (Sweden)
Jin Jianbo
2015-01-01
Full Text Available The development of mode conversion waveguides (launchers for high power gyrotrons has gone through three stages at KIT. Formerly, harmonically deformed launchers have been used in the series gyrotrons developed for the stellarator W7-X. In 2009, a numerical method for the analysis and synthesis of mirror-line launchers was developed at KIT. Such a launcher with adapted mode-converting mirrors for a 2 MW TE34,19-mode, 170GHz coaxial-cavity gyrotron has been designed and tested, and also a mirror-line launcher for the 1MW EU ITER gyrotron has been designed. Recently, based on the Helmholtz-Kirchhoff integral theorem, a novel numerical method for the synthesis of hybrid-type gyrotron launchers has been developed. As an example, TE32,9 mode launchers operating at 170GHz that have been designed using the three different methods are being compared.
Neutron generator for BNCT based on high current ECR ion source with gyrotron plasma heating.
Skalyga, V; Izotov, I; Golubev, S; Razin, S; Sidorov, A; Maslennikova, A; Volovecky, A; Kalvas, T; Koivisto, H; Tarvainen, O
2015-12-01
BNCT development nowadays is constrained by a progress in neutron sources design. Creation of a cheap and compact intense neutron source would significantly simplify trial treatments avoiding use of expensive and complicated nuclear reactors and accelerators. D-D or D-T neutron generator is one of alternative types of such sources for. A so-called high current quasi-gasdynamic ECR ion source with plasma heating by millimeter wave gyrotron radiation is suggested to be used in a scheme of D-D neutron generator in the present work. Ion source of that type was developed in the Institute of Applied Physics of Russian Academy of Sciences (Nizhny Novgorod, Russia). It can produce deuteron ion beams with current density up to 700-800 mA/cm(2). Generation of the neutron flux with density at the level of 7-8·10(10) s(-1) cm(-2) at the target surface could be obtained in case of TiD2 target bombardment with deuteron beam accelerated to 100 keV. Estimations show that it is enough for formation of epithermal neutron flux with density higher than 10(9) s(-1) cm(-2) suitable for BNCT. Important advantage of described approach is absence of Tritium in the scheme. First experiments performed in pulsed regime with 300 mA, 45 kV deuteron beam directed to D2O target demonstrated 10(9) s(-1) neutron flux. This value corresponds to theoretical estimations and proofs prospects of neutron generator development based on high current quasi-gasdynamic ECR ion source.
DEFF Research Database (Denmark)
Stock, Andreas; Neudorfer, Jonathan; Riedlinger, Marc;
2012-01-01
Fast design codes for the simulation of the particle–field interaction in the interior of gyrotron resonators are available. They procure their rapidity by making strong physical simplifications and approximations, which are not known to be valid for many variations of the geometry and the operat...
Bernstein wave aided laser third harmonic generation in a plasma
Tyagi, Yachna; Tripathi, Deepak; Kumar, Ashok
2016-09-01
The process of Bernstein wave aided resonant third harmonic generation of laser in a magnetized plasma is investigated. The extra-ordinary mode (X-mode) laser of frequency ω 0 and wave number k → 0 , travelling across the magnetic field in a plasma, exerts a second harmonic ponderomotive force on the electrons imparting them an oscillatory velocity v → 2 ω0 , 2 k → 0 . This velocity beats with the density perturbation due to the Bernstein wave to produce a density perturbation at cyclotron frequency shifted second harmonic. The density perturbation couples with the oscillatory velocity v → ω0 , k → 0 of X-mode of the laser to produce the cyclotron frequency shifted third harmonic current density leading to harmonic radiation. The phase matching condition for the up shifted frequency is satisfied when the Bernstein wave is nearly counter-propagating to the laser. As the transverse wave number of the Bernstein wave is large, it is effective in the phase matched third harmonic generation, when the laser frequency is not too far from the upper hybrid frequency.
Energy Technology Data Exchange (ETDEWEB)
Thumm, Manfred E-mail: manfred.thumm@ihm.fzk.de
2002-05-01
The possible applications of high-power millimeter (mm) and sub-mm waves from free-electron masers (FEMs) and gyro-devices span a wide range of technologies. The plasma physics community has already taken advantage of recent advances in applying high-power mm waves generated by long pulse or continuous wave (CW) gyrotron oscillators and short pulse very high-power FEMs in the areas of RF-plasma production, heating, non-inductive current drive, plasma stabilization and active plasma diagnostics for magnetic confinement thermonuclear fusion research, such as electron cyclotron resonance heating (28-170 GHz), electron cyclotron current drive , collective Thomson scattering , microwave transmission and heat-wave propagation experiments. Continuously frequency tunable FEMs could widen these fields of applications. Another important application of CW gyrotrons is industrial materials processing, e.g. sintering of high-performance functional and structural nanostructured ceramics. Sub-mm wave sources are employed in high-frequency broadband electron paramagnetic resonance and other types of spectroscopy. Future applications which await the development of novel high-power FEM amplifiers and gyro-amplifiers include high-resolution radar ranging and imaging in atmospheric and planetary science as well as deep-space and specialized satellite communications and RF drivers for next-generation high-gradient linear accelerators (supercolliders). The present paper reviews the state-of-the-art and future prospects of these recent applications of gyro-devices and FEMs and compares their specific advantages.
Towards automated biomedical ontology harmonization.
Uribe, Gustavo A; Lopez, Diego M; Blobel, Bernd
2014-01-01
The use of biomedical ontologies is increasing, especially in the context of health systems interoperability. Ontologies are key pieces to understand the semantics of information exchanged. However, given the diversity of biomedical ontologies, it is essential to develop tools that support harmonization processes amongst them. Several algorithms and tools are proposed by computer scientist for partially supporting ontology harmonization. However, these tools face several problems, especially in the biomedical domain where ontologies are large and complex. In the harmonization process, matching is a basic task. This paper explains the different ontology harmonization processes, analyzes existing matching tools, and proposes a prototype of an ontology harmonization service. The results demonstrate that there are many open issues in the field of biomedical ontology harmonization, such as: overcoming structural discrepancies between ontologies; the lack of semantic algorithms to automate the process; the low matching efficiency of existing algorithms; and the use of domain and top level ontologies in the matching process.
Harmonic space and quaternionic manifolds
Galperin, A; Ogievetsky, O V
1994-01-01
We find a principle of harmonic analyticity underlying the quaternionic (quaternion-K\\"ahler) geometry and solve the differential constraints which define this geometry. To this end the original $4n$-dimensional quaternionic manifold is extended to a bi-harmonic space. The latter includes additional harmonic coordinates associated with both the tangent local $Sp(1)$ group and an extra rigid $SU(2)$ group rotating the complex structures. Then the constraints can be rewritten as integrability conditions for the existence of an analytic subspace in the bi-harmonic space and solved in terms of two unconstrained potentials on the analytic subspace. Geometrically, the potentials have the meaning of vielbeins associated with the harmonic coordinates. We also establish a one-to-one correspondence between the quaternionic spaces and off-shell $N=2$ supersymmetric sigma-models coupled to $N=2$ supergravity. The general $N=2$ sigma-model Lagrangian when written in the harmonic superspace is composed of the quaternionic ...
Next generation data harmonization
Armstrong, Chandler; Brown, Ryan M.; Chaves, Jillian; Czerniejewski, Adam; Del Vecchio, Justin; Perkins, Timothy K.; Rudnicki, Ron; Tauer, Greg
2015-05-01
Analysts are presented with a never ending stream of data sources. Often, subsets of data sources to solve problems are easily identified but the process to align data sets is time consuming. However, many semantic technologies do allow for fast harmonization of data to overcome these problems. These include ontologies that serve as alignment targets, visual tools and natural language processing that generate semantic graphs in terms of the ontologies, and analytics that leverage these graphs. This research reviews a developed prototype that employs all these approaches to perform analysis across disparate data sources documenting violent, extremist events.
Second harmonic generation microscopy
DEFF Research Database (Denmark)
Brüggemann, Dagmar Adeline; Brewer, Jonathan R.; Risbo, Jens
2010-01-01
Myofibers and collagen show non-linear optical properties enabling imaging using second harmonic generation (SHG) microscopy. The technique is evaluated for use as a tool for real-time studies of thermally induced changes in thin samples of unfixed and unstained pork. The forward and the backward......-temperature endotherm peak observable in the differential scanning calorimetry (DSC) thermograms. DSC analysis of epimysium, the connective tissue layer that enfold skeletal muscles, produces one large endotherm starting at 57 °C and peaking at 59.5 °C. SHG microscopy of collagen fibers reveals a variability of thermal...
Computing with Harmonic Functions
Axler, Sheldon
2015-01-01
This document is the manual for a free Mathematica package for computing with harmonic functions. This package allows the user to make calculations that would take a prohibitive amount of time if done without a computer. For example, the Poisson integral of any polynomial can be computed exactly. This software can find exact solutions to Dirichlet, Neumann, and biDirichlet problems in R^n with polynomial data on balls, ellipsoids, and annular regions. It can also find bases for spaces of sphe...
Directory of Open Access Journals (Sweden)
M. A. Navascués
2013-01-01
Full Text Available This paper tackles the construction of fractal maps on the unit sphere. The functions defined are a generalization of the classical spherical harmonics. The methodology used involves an iterated function system and a linear and bounded operator of functions on the sphere. For a suitable choice of the coefficients of the system, one obtains classical maps on the sphere. The different values of the system parameters provide Bessel sequences, frames, and Riesz fractal bases for the Lebesgue space of the square integrable functions on the sphere. The Laplace series expansion is generalized to a sum in terms of the new fractal mappings.
Mahmoudian, A.; Scales, W. A.; Bernhardt, P. A.; Samimi, A.; Kendall, E.; Ruohoniemi, J. M.; Isham, B.; Vega-Cancel, O.; Bordikar, M.
2013-03-01
Stimulated electromagnetic emissions (SEEs) are secondary radiation produced during active space experiments in which the ionosphere is actively heated with high power high frequency (HF) ground-based radio transmitters. Recently, there has been significant interest in ion gyro-harmonic structuring the SEE spectrum due to the potential for new diagnostic information available such as electron acceleration and creation of artificial ionization layers. These relatively recently discovered gyro-harmonic spectral features have almost exclusively been studied when the transmitting frequency is near the second electron gyro-harmonic frequency. The first extensive systematic experimental investigations of the possibility of these spectral features for third electron gyro-harmonic heating are provided here. Discrete spectral features shifted from the transmit frequency ordered by harmonics of the ion gyro-frequency were observed for third electron gyro-harmonic heating for the first time at a recent campaign at the High Frequency Active Auroral Research Program (HAARP) facility. These features were also closely correlated with a broader band feature at a larger frequency shift from the transmit frequency known as the downshifted peak (DP). The power threshold of these spectral features was measured, as well as their behavior with heater beam angle, and proximity of the transmit frequency to the third electron gyro-harmonic frequency. Comparisons were also made with similar spectral features observed during second electron gyro-harmonic heating during the same campaign. A theoretical model is provided that interprets these spectral features as resulting from parametric decay instabilities in which the pump field ultimately decays into high frequency upper hybrid/electron Bernstein and low frequency neutralized ion Bernstein IB and/or obliquely propagating ion acoustic waves at the upper hybrid interaction altitude. Coordinated optical and SEE observations were carried out
A Dual-Beam Irradiation Facility for a Novel Hybrid Cancer Therapy
Sabchevski, Svilen; Ishiyama, Shintaro; Miyoshi, Norio; Tatsukawa, Toshiaki
2012-01-01
In this paper we present the main ideas and discuss both the feasibility and the conceptual design of a novel hybrid technique and equipment for an experimental cancer therapy based on the simultaneous and/or sequential application of two beams, namely a beam of neutrons and a CW (continuous wave) or intermittent sub-terahertz wave beam produced by a gyrotron for treatment of cancerous tumors. The main simulation tools for the development of the computer aided design (CAD) of the prospective experimental facility for clinical trials and study of such new medical technology are briefly reviewed. Some tasks for a further continuation of this feasibility analysis are formulated as well.
DSP Control of Line Hybrid Active Filter
DEFF Research Database (Denmark)
Dan, Stan George; Benjamin, Doniga Daniel; Magureanu, R.;
2005-01-01
Active Power Filters have been intensively explored in the past decade. Hybrid active filters inherit the efficiency of passive filters and the improved performance of active filters, and thus constitute a viable improved approach for harmonic compensation. In this paper a parallel hybrid filter ...
60 GHz gyrotron development program. Final report, April 1979-June 1984
Energy Technology Data Exchange (ETDEWEB)
Shively, J.F.; Bier, R.E.; Caplan, M.; Cheng, M.K.; Choi, E.; Conner, C.C.; Craig, L.J.; Evans, S.J.; Evers, S.J.; Felch, K.L.
1986-01-01
The original objective of this program was to develop a microwave amplifier or oscillator capable of producing 200 kW CW power output at 110 GHz. The use of cyclotron resonance interaction was pursued, and the design phases of this effort are discussed. Later, however, the program's objective was changed to develop a family of oscillators capable of producing 200 kw of peak output power at 60 GHz. Gyrotron behavior studies were performed at 28 GHz to obtain generic design information as quickly as possible. The first experimental device at 60 GHz produced over 200 kw of peak power at a pulse duration of 20 ..mu..s. Heating problems and mode interference were encountered. The second experimental tube incorporated an optimized gun location but also suffered from mode interference. The third experimental tube included modifications that reduced mode interference. It demonstrated 200 kw of peak output at 100 ms pulse duration. The fourth experimental tube, which used an older rf circuit design but in a CW configuration, produced 71.5 kW CW. The fifth experimental tube incorporated a thinner double-disc output window which improved window bandwidth and reduced window loss. This tube also incorporated modifications to the drift tunnel and cavity coupling, which had proven successful in the third experimental pulse tube tests. It produced 123 kW of CW output power at 60 GHz rf load coolant boiling and tube window failure terminated the tests. A new waterload was designed and constructed, and alternative window designs were explored. A secondary task of developing a 56 GHz CW tube produced in excess of 100 kW CW at this alternate frequency. Testing of the sixth experimental tube resulted in operation at CW output power in the range of 200 to 206 kW for an hour. Output mode purity of the seventh experimental tube was measured at 95% TE/sub 02/. The tube was operated for about forty-five minutes with CW power output over 200 kW.
On The Harmonic Oscillator Group
Lopez, Raquel M; Vega-Guzman, Jose M
2011-01-01
We discuss the maximum kinematical invariance group of the quantum harmonic oscillator from a view point of the Ermakov-type system. The invariance group of generalized driven harmonic oscillator is shown to be isomorphic to the corresponding Schroedinger group of the free particle.
EXTENSIONS OF EULER HARMONIC SUMS
Directory of Open Access Journals (Sweden)
Djurdje Cvijović
2012-10-01
Full Text Available Three new closed-form summation formulae involving harmonic numbers are established using simple arguments and they are very general extensions of Euler’s famous harmonic sum identity. Some illustrative special cases as well as immediate consequences of the main results are also considered.
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?
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...... harmonic techniques have been made, but none of these methods have so far been applicable for in-vivo imaging. The basis of this project is a synthetic aperture technique known as synthetic aperture sequential beamforming (SASB). The technique utilizes a two step beamforming approach to drastically reduce...
High harmonics focusing undulator
Energy Technology Data Exchange (ETDEWEB)
Varfolomeev, A.A.; Hairetdinov, A.H.; Smirnov, A.V.; Khlebnikov, A.S. [Kurchatov Institute, Moscow (Russian Federation)
1995-12-31
It was shown in our previous work that there exist a possibility to enhance significantly the {open_quote}natural{close_quote} focusing properties of the hybrid undulator. Here we analyze the actual undulator configurations which could provide such field structure. Numerical simulations using 2D code PANDIRA were carried out and the enhanced focusing properties of the undulator were demonstrated. The obtained results provide the solution for the beam transport in a very long (short wavelength) undulator schemes.
Study on the After Cavity Interaction in a 140 GHz Gyrotron Using 3D CFDTD PIC Simulations
Lin, M. C.; Illy, S.; Avramidis, K.; Thumm, M.; Jelonnek, J.
2016-10-01
A computational study on after cavity interaction (ACI) in a 140 GHz gryotron for fusion research has been performed using a 3-D conformal finite-difference time-domain (CFDTD) particle-in-cell (PIC) method. The ACI, i.e. beam wave interaction in the non-linear uptaper after the cavity has attracted a lot of attention and been widely investigated in recent years. In a dynamic ACI, a TE mode is excited by the electron beam at the same frequency as in the cavity, and the same mode is also interacting with the spent electron beam at a different frequency in the non-linear uptaper after the cavity while in a static ACI, a mode interacts with the beam both at the cavity and at the uptaper, but at the same frequency. A previous study on the dynamic ACI on a 140 GHz gyrotron has concluded that more advanced numerical simulations such as particle-in-cell (PIC) modeling should be employed to study or confirm the dynamic ACI in addition to using trajectory codes. In this work, we use a 3-D full wave time domain simulation based on the CFDTD PIC method to include the rippled-wall launcher of the quasi-optical output coupler into the simulations which breaks the axial symmetry of the original model employing a symmetric one. A preliminary simulation result has confirmed the dynamic ACI effect in this 140 GHz gyrotron in good agreement with the former study. A realistic launcher will be included in the model for studying the dynamic ACI and compared with the homogenous one.
Harmonics Mitigation Using Active Power Filter
Directory of Open Access Journals (Sweden)
Sourabh Gupta
2013-06-01
Full Text Available This paper is proposed to reconsider the development of active power filter (APF technologies that are routinely utilized to mitigate harmonics in utility power lines. This reconsider can furthermore be considered as a “tutorial-type paper” as it provides a holistic coverage of the APF technologies by omitting the tedious details, but without losing the major essence of the subject matter. It is wanted that by this approach, it would be likely to lure more power engineering readers to be involved in this important and growing area. The discussion starts with a short overview of harmonic distortion difficulties and their impacts on electric power and powered value. The operation of common APF topologies, namely the shunt, sequence and hybrid APFs are recounted in minutia. This is followed by a reconsider on different types of reference pointer estimation extraction methods. In specific, the application of the p-q and elongation p-q theorems to extract the quotation pointers are elaborated, as they are the most commonly discovered in practical APF systems eventually, an overview of the APF command schemes is provided. A short consideration on the APF-solar photovoltaic scheme is furthermore granted. At the end of the paper, important references are cited to aid readers who are interested to discover the subject in larger detail.
FROM THE HARMONIZATION NEED TO THE SPONTANEOUS ACCOUNTING HARMONIZATION
2009-01-01
The issue of international accounting harmonization has achieved, mainly within the last decade, a significant dimension in the field of international accounting research. The main determinant factor for this state of the art is the process aiming at redu
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
Lattice harmonics expansion revisited
Kontrym-Sznajd, G.; Holas, A.
2017-04-01
The main subject of the work is to provide the most effective way of determining the expansion of some quantities into orthogonal polynomials, when these quantities are known only along some limited number of sampling directions. By comparing the commonly used Houston method with the method based on the orthogonality relation, some relationships, which define the applicability and correctness of these methods, are demonstrated. They are verified for various sets of sampling directions applicable for expanding quantities having the full symmetry of the Brillouin zone of cubic and non-cubic lattices. All results clearly show that the Houston method is always better than the orthogonality-relation one. For the cubic symmetry we present a few sets of special directions (SDs) showing how their construction and, next, a proper application depend on the choice of various sets of lattice harmonics. SDs are important mainly for experimentalists who want to reconstruct anisotropic quantities from their measurements, performed at a limited number of sampling directions.
Crane, Edward; Volkov, Stanislav; Wade, Andrew; Waters, Robert
2009-01-01
We study a generalized Polya urn model with two types of ball. If the drawn ball is red it is replaced together with a black ball, but if the drawn ball is black it is replaced and a red ball is thrown out of the urn. When only black balls remain, the roles of the colours are swapped and the process restarts. We prove that the resulting Markov chain is transient but that if we throw out a ball every time the colours swap, the process is positive-recurrent. We show that the embedded process obtained by observing the number of balls in the urn at the swapping times has a scaling limit that is essentially the square of a Bessel diffusion. We consider an oriented percolation model naturally associated with the urn process, and obtain detailed information about its structure, showing that the open subgraph is an infinite tree with a single end. We also study a natural continuous-time embedding of the urn process that demonstrates the relation to the simple harmonic oscillator; in this setting our transience result...
Explaining the harmonic sequence paradox.
Schmidt, Ulrich; Zimper, Alexander
2012-05-01
According to the harmonic sequence paradox, an expected utility decision maker's willingness to pay for a gamble whose expected payoffs evolve according to the harmonic series is finite if and only if his marginal utility of additional income becomes zero for rather low payoff levels. Since the assumption of zero marginal utility is implausible for finite payoff levels, expected utility theory - as well as its standard generalizations such as cumulative prospect theory - are apparently unable to explain a finite willingness to pay. This paper presents first an experimental study of the harmonic sequence paradox. Additionally, it demonstrates that the theoretical argument of the harmonic sequence paradox only applies to time-patient decision makers, whereas the paradox is easily avoided if time-impatience is introduced.
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.
Pythagorean Triples from Harmonic Sequences.
DiDomenico, Angelo S.; Tanner, Randy J.
2001-01-01
Shows how all primitive Pythagorean triples can be generated from harmonic sequences. Use inductive and deductive reasoning to explore how Pythagorean triples are connected with another area of mathematics. (KHR)
Morrey spaces in harmonic analysis
David R. Adams; Xiao, Jie
2012-01-01
Through a geometric capacitary analysis based on space dualities, this paper addresses several fundamental aspects of functional analysis and potential theory for the Morrey spaces in harmonic analysis over the Euclidean spaces.
Morrey spaces in harmonic analysis
Adams, David R.; Xiao, Jie
2012-10-01
Through a geometric capacitary analysis based on space dualities, this paper addresses several fundamental aspects of functional analysis and potential theory for the Morrey spaces in harmonic analysis over the Euclidean spaces.
Echo-Enabled Harmonic Generation
Energy Technology Data Exchange (ETDEWEB)
Stupakov, Gennady; /SLAC
2012-06-28
A recently proposed concept of the Echo-Enabled Harmonic Generation (EEHG) FEL uses two laser modulators in combination with two dispersion sections to generate a high-harmonic density modulation in a relativistic beam. This seeding technique holds promise of a one-stage soft x-ray FEL that radiates not only transversely but also longitudinally coherent pulses. Currently, an experimental verification of the concept is being conducted at the SLAC National Accelerator Laboratory aimed at the demonstration of the EEHG.
Echo-Enabled Harmonic Generation
Energy Technology Data Exchange (ETDEWEB)
Stupakov, Gennady; /SLAC
2012-06-28
A recently proposed concept of the Echo-Enabled Harmonic Generation (EEHG) FEL uses two laser modulators in combination with two dispersion sections to generate a high-harmonic density modulation in a relativistic beam. This seeding technique holds promise of a one-stage soft x-ray FEL that radiates not only transversely but also longitudinally coherent pulses. Currently, an experimental verification of the concept is being conducted at the SLAC National Accelerator Laboratory aimed at the demonstration of the EEHG.
Foliated stochastic calculus: Harmonic measures
Catuogno, Pedro J; Ruffino, Paulo R
2010-01-01
In this article we present an intrinsec construction of foliated Brownian motion via stochastic calculus adapted to foliation. The stochastic approach together with a proposed foliated vector calculus provide a natural method to work on harmonic measures. Other results include a decomposition of the Laplacian in terms of the foliated and basic Laplacians, a characterization of totally invariant measures and a differential equation for the density of harmonic measures.
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....
Harmonic Current Predictors for Wind Turbines
Directory of Open Access Journals (Sweden)
Shun-Yu Chan
2013-03-01
Full Text Available The harmonic impact caused by wind turbines should be carefully investigated before wind turbines are interconnected. However, the harmonic currents of wind turbines are not easily predicted due to the variations of wind speed. If the harmonic current outputs can be predicted accurately, the harmonic impact of wind turbines and wind farms for power grids can be analyzed efficiently. Therefore, this paper analyzes the harmonic current characteristics of wind turbines and investigates the feasibility of developing harmonic current predictors. Field measurement, data sorting, and analysis are conducted for wind turbines. Two harmonic current predictors are proposed based on the measured harmonic data. One is the Auto-Regressive and Moving Average (ARMA-based harmonic current predictor, which can be used for real-time prediction. The other is the stochastic harmonic current predictor considering the probability density distributions of harmonic currents. It uses the measured harmonic data to establish the probability density distributions of harmonic currents at different wind speeds, and then uses them to implement a long-term harmonic current prediction. Test results use the measured data to validate the forecast ability of these two harmonic current predictors. The ARMA-based predictor obtains poor performance on some harmonic orders due to the stochastic characteristics of harmonic current caused by the variations of wind speed. Relatively, the prediction results of stochastic harmonic current predictor show that the harmonic currents of a wind turbine in long-term operation can be effectively analyzed by the established probability density distributions. Therefore, the proposed stochastic harmonic current predictor is helpful in predicting and analyzing the possible harmonic problems during the operation of wind turbines and wind farms.
Spherical harmonics in texture analysis
Schaeben, Helmut; van den Boogaart, K. Gerald
2003-07-01
The objective of this contribution is to emphasize the fundamental role of spherical harmonics in constructive approximation on the sphere in general and in texture analysis in particular. The specific purpose is to present some methods of texture analysis and pole-to-orientation probability density inversion in a unifying approach, i.e. to show that the classic harmonic method, the pole density component fit method initially introduced as a distinct alternative, and the spherical wavelet method for high-resolution texture analysis share a common mathematical basis provided by spherical harmonics. Since pole probability density functions and orientation probability density functions are probability density functions defined on the sphere Ω3⊂ R3 or hypersphere Ω4⊂ R4, respectively, they belong at least to the space of measurable and integrable functions L1( Ωd), d=3, 4, respectively. Therefore, first a basic and simplified method to derive real symmetrized spherical harmonics with the mathematical property of providing a representation of rotations or orientations, respectively, is presented. Then, standard orientation or pole probability density functions, respectively, are introduced by summation processes of harmonic series expansions of L1( Ωd) functions, thus avoiding resorting to intuition and heuristics. Eventually, it is shown how a rearrangement of the harmonics leads quite canonically to spherical wavelets, which provide a method for high-resolution texture analysis. This unified point of view clarifies how these methods, e.g. standard functions, apply to texture analysis of EBSD orientation measurements.
Prony Analysis for Power System Transient Harmonics
Directory of Open Access Journals (Sweden)
Qi Li
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
Harmonic morphisms and subharmonic functions
Directory of Open Access Journals (Sweden)
Gabjin Yun
2005-03-01
Full Text Available Let M be a complete Riemannian manifold and N a complete noncompact Riemannian manifold. Let ÃÂ•:MÃ¢Â†Â’N be a surjective harmonic morphism. We prove that if N admits a subharmonic function with finite Dirichlet integral which is not harmonic, and ÃÂ• has finite energy, then ÃÂ• is a constant map. Similarly, if f is a subharmonic function on N which is not harmonic and such that |df| is bounded, and if Ã¢ÂˆÂ«M|dÃÂ•|<Ã¢ÂˆÂž, then ÃÂ• is a constant map. We also show that if Nm(mÃ¢Â‰Â¥3 has at least two ends of infinite volume satisfying the Sobolev inequality or positivity of the first eigenvalue of the Laplacian, then there are no nonconstant surjective harmonic morphisms with finite energy. For p-harmonic morphisms, similar results hold.
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.
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.......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...
Energy Technology Data Exchange (ETDEWEB)
Ros, A.; Fernandez, A.; Tolkachev, A.; Catalan, G.
2006-07-01
The TJ-II ECRH heating system consists of two gyrotrons, which can deliver a maximum power of 300 kW at a frequency of 53.2 GHz. Another 28 GHz gyrotron is going to be used in the Bernstein waves heating system. In order to get the required frequency, the gyrotrons need and homogeneous magnetic field of several tesla, which is generated by a superconducting coil field by a current source. This document describes the current source control as well as the high precision ammeters control. These ammeters measure the current in the superconducting coils. The user interface and the programming of the control system are described. The communication between devices is also explained. (author) 9 Refs.
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.
Harmonic morphisms and bicomplex numbers
Baird, Paul
2009-01-01
We use functions of a bicomplex variable to unify the existing constructions of harmonic morphisms from a 3-dimensional Euclidean or pseudo-Euclidean space to a Riemannian or Lorentzian surface. This is done by using the notion of complex-harmonic morphism between complex Riemannian manifolds and showing how these are given by bicomplex-holomorphic functions when the codomain is one-bicomplex dimensional. Interesting compactifications involving bicomplex manifolds are given. By taking real slices, we recover well-known compactifications for the three possible real cases.
The Obstacle Problem for the -Harmonic Equation
Directory of Open Access Journals (Sweden)
Bao Gejun
2010-01-01
Full Text Available Firstly, we define an order for differential forms. Secondly, we also define the supersolution and subsolution of the -harmonic equation and the obstacle problems for differential forms which satisfy the -harmonic equation, and we obtain the relations between the solutions to -harmonic equation and the solution to the obstacle problem of the -harmonic equation. Finally, as an application of the obstacle problem, we prove the existence and uniqueness of the solution to the -harmonic equation on a bounded domain with a smooth boundary , where the -harmonic equation satisfies where is any given differential form which belongs to .
Third Harmonic Imaging using a Pulse Inversion
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 component for imaging on any ultrasound system capable of PI. PI was used to perform 3rd harmonic Bmode scans of a water-filled wire phantom on an experimental ultrasound system. The 3rd harmonic...
FROM THE HARMONIZATION NEED TO THE SPONTANEOUS ACCOUNTING HARMONIZATION
Directory of Open Access Journals (Sweden)
Matis Dumitru
2009-05-01
Full Text Available The issue of international accounting harmonization has achieved, mainly within the last decade, a significant dimension in the field of international accounting research. The main determinant factor for this state of the art is the process aiming at redu
Energy Technology Data Exchange (ETDEWEB)
Stock, Andreas
2013-04-26
Within this thesis a parallelized, transient, three-dimensional, high-order discontinuous Galerkin Particle-in-Cell solver is developed and used to simulate the resonant cavity of a gyrotron. The high-order discontinuous Galerkin approach - a Finite-Element type method - provides a fast and efficient algorithm to numerically solve Maxwell's equations used within this thesis. Besides its outstanding dissipation and dispersion properties, the discontinuous Galerkin approach easily allows for using unstructured grids, as required to simulate complex-shaped engineering devices. The discontinuous Galerkin approach approximates a wavelength with significantly less degrees of freedom compared to other methods, e.g. Finite Difference methods. Furthermore, the parallelization capabilities of the discontinuous Galerkin framework are excellent due to the very local dependencies between the elements. These properties are essential for the efficient numerical treatment of the Vlasov-Maxwell system with the Particle-in-Cell method. This system describes the self-consistent interaction of charged particles and the electromagnetic field. As central application within this thesis gyrotron resonators are simulated with the discontinuous Galerkin Particle-in-Cell method on high-performance-computers. The gyrotron is a high-power millimeter wave source, used for the electron cyclotron resonance heating of magnetically confined fusion plasma, e.g. in the Wendelstein 7-X experimental fusion-reactor. Compared to state-of-the-art simulation tools used for the design of gyrotron resonators the Particle-in-Cell method does not use any significant physically simplifications w.r.t. the modelling of the particle-field-interaction, the geometry and the wave-spectrum. Hence, it is the method of choice for validation of current simulation tools being restricted by these simplifications. So far, the Particle-in-Cell method was restricted to be used for demonstration calculations only, because
DEFF Research Database (Denmark)
Wei, Feng; Sun, Kai; Guan, Yajuan;
2015-01-01
being adopted for abstracting the fundamental components of grid voltage. The injected fundamental power is controlled through droop controller, and a hybrid voltage controller of GF-VCI with PI and R regulators in rotary frame is adopted for improving of the tracking capability of the grid harmonic...
A Stable 0.2-THz Coaxial-Waveguide Gyrotron Traveling-Wave-Tube Amplifier with Distributed Losses
Hung, C. L.; Yeh, Y. S.; Chang, T. H.; Fang, R. S.
2016-08-01
For high-power operation, a THz gyrotron traveling-wave-tube (gyro-TWT) amplifier must operate in a high-order waveguide mode to enlarge the transverse dimension of an interaction waveguide. However, a gyro-TWT amplifier operating in a high-order waveguide mode is susceptible to spurious oscillations. To improve the device stability, in this study, we investigate the possibility of using a coaxial waveguide with distributed losses as the interaction structure. For the same required attenuation, all threatening oscillating modes can be suppressed using different combinations of losses of inner and outer cylinders. This provides flexibility in designing distributed losses when considering the ohmic loading of the interaction structure. We predict that the 0.2-THz gyro-TWT can stably produce a peak power of 14 kW with an efficiency of 23 %, a 3-dB bandwidth of 3.5 GHz, and a saturated gain of 50 dB for a 20-kV 3-A electron beam with a 5 % velocity spread and 1.0 velocity ratio.
Image composition with color harmonization
Institute of Scientific and Technical Information of China (English)
Congde Wang; Rong Zhang; Fan Deng
2009-01-01
Image matting and color transfer are combined to achieve image composition.Firstly,digital matting is used to pull out the region of interest.Secondly,taking color harmonization into account,color transfer techniques are introduced in pasting the region onto the target image.Experimental results show that the proposed approach generates visually plea.sing composite images.
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...
Third harmonic measurement in printed electronics
Samano, A; Xu, Y.; Harrison, D.; Hunt, C; Wickham, M; Thomas, O.
2014-01-01
The purpose of this research paper is to investigate the defects detecting technique in printed electronics by the third harmonic measurements. Various types of defects were introduced on the samples and the third harmonic signal was measured using a component linearity tester (Radiometer CLT1). The relationship between the defects in the printed samples and the third harmonic signal and the third harmonic ratio was identified.
Local field enhanced second-harmonic response of organic nanofibers
DEFF Research Database (Denmark)
Leißner, Till; Kostiučenko, Oksana; Fiutowski, Jacek
Organic CNHP4 nanofibers showing a strong second-harmonic (SH) response have been successfully implemented as active components in a metal-organic hybrid system. Using nondestructive roll-on transfer technique nanofibers were transferred from the growing mica substrates onto electron......-beam lithography-defined regular arrays of gold, titanium and silicon oxide. As shown in a femtosecond laser scanning microscopy study the fiber-substrate interplay leads (only) on gold to a significantly enhanced SH signal. We suggest that this effect is driven by the local field enhancement i.e. the excitation...
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 functions of superprocesses and conditioned superprocesses’
Institute of Scientific and Technical Information of China (English)
赵学雷
1996-01-01
The harmonic functions for superprocesses are defined by applying the martingale property. Under a general condition, a classification theorem of harmonic functions for homogeneous superprocesses is obtained in terms of the solutions to a measure functional equation. The conditioned superdiffusions in a regular domain by Doob’s harmonic transform are defined and investigated.
Harmonic oscillator: an analysis via Fourier series
de Castro, A S
2013-01-01
The Fourier series method is used to solve the homogeneous equation governing the motion of the harmonic oscillator. It is shown that the general solution to the problem can be found in a surprisingly simple way for the case of the simple harmonic oscillator. It is also shown that the damped harmonic oscillator is susceptible to the analysis.
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
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...... 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...
Second-Harmonic and Third-Harmonic Generations in the Thue-Morse Dielectric Superlattice
Institute of Scientific and Technical Information of China (English)
蔡祥宝
2002-01-01
Theoretical work on the optical properties of the one-dimensional dielectric superlattice is extended. 3Byv means of a transfer matrix method, the second-harmonic and third-harmonic generations in a one-dimensional tinite Thue Morse dielectric superlattice are analysed. The electric field amplitude variables of the second-harmonic and third-harmonic can be expressed by the formula of matrices. Taking advantage of numerical procedure, we discuss the dependence of the second-harmonic and third-harmonic on the fundamental wavelength and the field amplitude variables of the fundamental wave. High conversion efficiency of the third-harmonic can be obtained at some special fundamental wavelength.
Energy Technology Data Exchange (ETDEWEB)
Neilson, Jeffrey M.
2017-07-25
A cylindrical waveguide with a mode converter transforms a whispering gallery mode from a gyrotron cylindrical waveguide with a helical cut launch edge to a quasi-Gaussian beam suitable for conveyance through a corrugated waveguide. This quasi-Gaussian beam is radiated away from the waveguide using a spiral cut launch edge, which is in close proximity to a first mode converting reflector. The first mode converting reflector is coupled to a second mode converting reflector which provides an output free-space HE11 mode wave suitable for direct coupling into a corrugated waveguide. The radiated beam produced at the output of the second mode converting reflector is substantially circular.
Lorentz Harmonics, Squeeze Harmonics and Their Physical Applications
Directory of Open Access Journals (Sweden)
Marilyn E. Noz
2011-02-01
Full Text Available Among the symmetries in physics, the rotation symmetry is most familiar to us. It is known that the spherical harmonics serve useful purposes when the world is rotated. Squeeze transformations are also becoming more prominent in physics, particularly in optical sciences and in high-energy physics. As can be seen from Dirac’s light-cone coordinate system, Lorentz boosts are squeeze transformations. Thus the squeeze transformation is one of the fundamental transformations in Einstein’s Lorentz-covariant world. It is possible to define a complete set of orthonormal functions defined for one Lorentz frame. It is shown that the same set can be used for other Lorentz frames. Transformation properties are discussed. Physical applications are discussed in both optics and high-energy physics. It is shown that the Lorentz harmonics provide the mathematical basis for squeezed states of light. It is shown also that the same set of harmonics can be used for understanding Lorentz-boosted hadrons in high-energy physics. It is thus possible to transmit physics from one branch of physics to the other branch using the mathematical basis common to them.
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......Most power electronic equipment these days generate harmonic disturbances, these devices hold nonlinear voltage/current characteristic. The harmonics generated can potentially be harmful to the consumer supply. Typically, filters are integrated at the power source or utility location to filter out...
Exact propagators in harmonic superspace
Kuzenko, Sergei M.
2004-10-01
Within the background field formulation in harmonic superspace for quantum N = 2 super-Yang-Mills theories, the propagators of the matter, gauge and ghost superfields possess a complicated dependence on the SU(2) harmonic variables via the background vector multiplet. This dependence is shown to simplify drastically in the case of an on-shell vector multiplet. For a covariantly constant background vector multiplet, we exactly compute all the propagators. In conjunction with the covariant multi-loop scheme developed in arxiv:hep-th/0302205, these results provide an efficient (manifestly N = 2 supersymmetric) technical setup for computing multi-loop quantum corrections to effective actions in N = 2 supersymmetric gauge theories, including the N = 4 super-Yang-Mills theory.
Exact propagators in harmonic superspace
Kuzenko, S M
2004-01-01
Within the background field formulation in harmonic superspace for quantum N = 2 super Yang-Mills theories, the propagators of the matter, gauge and ghost superfields possess a complicated dependence on the SU(2) harmonic variables via the background vector multiplet. This dependence is shown to simplify drastically in the case of an on-shell vector multiplet. For a covariantly constant background vector multiplet, we exactly compute all the propagators. In conjunction with the covariant multi-loop scheme developed in hep-th/0302205, these results provide an efficient (manifestly N = 2 supersymmetric) technical setup for computing multi-loop quantum corrections to effective actions in N = 2 supersymmetric gauge theories, including the N = 4 super Yang-Mills theory.
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......./current characteristic. These harmonics are not to be allowed to grow beyond a certain limit to avoid any grave consequence to the customer’s main supply. Filters can be implemented at the power source or utility location to eliminate these harmonics. In this paper we detect the instance at which these harmonics occur...
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....
Harmonic ratcheting for fast acceleration
Cook, N.; Brennan, J. M.; Peggs, S.
2014-04-01
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 are taken into consideration.
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
Harmonic Lattice Dynamics of Germanium
Energy Technology Data Exchange (ETDEWEB)
Nelin, G.
1974-07-01
The phonon dispersion relations of the DELTA-, LAMBDA-, and SIGMA-directions of germanium at 80 K are analysed in terms of current harmonic lattice dynamical models. On the basis of this experience, a new model is proposed which gives a unified account of the strong points of the previous models. The principal elements of the presented theory are quasiparticle bond charges combined with a valence force field.
Page, P R
2003-01-01
We review the status of hybrid baryons. The only known way to study hybrids rigorously is via excited adiabatic potentials. Hybrids can be modelled by both the bag and flux-tube models. The low-lying hybrid baryon is N 1/2^+ with a mass of 1.5-1.8 GeV. Hybrid baryons can be produced in the glue-rich processes of diffractive gamma N and pi N production, Psi decays and p pbar annihilation.
Properties of Fermion Spherical Harmonics
Hunter, G; Hunter, Geoffrey; Emami-Razavi, Mohsen
2005-01-01
The Fermion Spherical harmonics [$Y_\\ell^{m}(\\theta,\\phi)$ for half-odd-integer $\\ell$ and $m$ - presented in a previous paper] are shown to have the same eigenfunction properties as the well-known Boson Spherical Harmonics [$Y_\\ell^{m}(\\theta,\\phi)$ for integer $\\ell$ and $m$]. The Fermion functions are shown to differ from the Boson functions in so far as the ladder operators $M_+$ ($M_-$) that ascend (descend) the sequence of harmonics over the values of $m$ for a given value of $\\ell$, do not produce the expected result {\\em in just one case}: when the value of $m$ changes from $\\pm{1/2}$ to $\\mp{1/2}$; i.e. when $m$ changes sign; in all other cases the ladder operators produce the usually expected result including anihilation when a ladder operator attempts to take $m$ outside the range: $-\\ell\\le m\\le +\\ell$. The unexpected result in the one case does not invalidate this scalar coordinate representation of spin angular momentum, because the eigenfunction property is essential for a valid quantum mechani...
Molecular Simulations using Spherical Harmonics
Institute of Scientific and Technical Information of China (English)
CAI, Wen-Sheng; XU, Jia-Wei; SHAO, Xue-Guang; MAIGRET, Bernard
2003-01-01
Computer-aided drug design is to develop a chemical that binds to a target macromolecule known to play a key role in a disease state. In recognition of ligands by their protein receptors,molecular surfaces are often used because they represent the interacting part of molecules and they should reflex the complementarity between ligand and receptor. However, assessing the surface complementarity by searching all relative position of two surfaces is often computationally expensive. The complementarity of lobe-hole is very important in protein-ligand interactions. Spherical harmonic models based on expansions of spherical harmonic functions were used as a fingerprint to approximate the binding cavity and the ligand, respectively. This defines a new way to identify the complementarity between lobes and holes. The advantage of this method is that two spherical harmonic surfaces to be compared can be defined separately. This method can be used as a filter to eliminate candidates among a large number of conformations, and it will speed up the docking procedure. Therefore, it is possible to select complementary ligands or complementary conformations of a ligand and the macromoleeules, by comparing their fingerprints previously stored in a database.
The Application of Spherical Harmonics for Describing a Cube-Shape Particle
Directory of Open Access Journals (Sweden)
Urtė Radvilaitė
2015-03-01
Full Text Available The paper disccusses various models for discrete element methods of modelling particle shapes. The multi-sphere method is most frequently used, though a polyhedral approach and a hybrid sphero-polyhedral model can also be introduced. All above mentioned methods precisely approximate particle shapes, and difficulties in modelling contact between particles arise. Thus, there is a need to have an universal method that gives the analytical expression of the shape. For this purpose, spherical harmonics have been introduced. The article presents the concept of the spherical harmonics model and experimental results describing the cube-shape particle.
Measurement and Analysis Harmonics Using DSP
Energy Technology Data Exchange (ETDEWEB)
Lee, Sang Ik; Yoo, Jae Geun; Jeon, Jonog Chay [Korea Electrical Safety Corporation (Korea)
2002-07-01
Limitation countermeasure on harmonics occurred by power conversion installation. motor speed control equipment, and so on of power system is very important problem, and first of all, accuracy harmonics analysis in system is required for appropriate limitation counterplan. Analysis and judgement on power system harmonic by measurement are needed because analysis by mathematical model generally used for these harmonic analysis, if nonlinear ingredient is included in system, is not relatively correct. So, in this paper, system to measure and analyze harmonic by installing it in a power system, using DSP(Digital Signal Processor), is designed and developed, Also, it's performance is verified by installing it in the system that harmonics occurred. (author). 5 refs., 10 figs.
High-harmonic spectroscopy of aligned molecules
Yun, Hyeok; Yun, Sang Jae; Lee, Gae Hwang; Nam, Chang Hee
2017-01-01
High harmonics emitted from aligned molecules driven by intense femtosecond laser pulses provide the opportunity to explore the structural information of molecules. The field-free molecular alignment technique is an expedient tool for investigating the structural characteristics of linear molecules. The underlying physics of field-free alignment, showing the characteristic revival structure specific to molecular species, is clearly explained from the quantum-phase analysis of molecular rotational states. The anisotropic nature of molecules is shown from the harmonic polarization measurement performed with spatial interferometry. The multi-orbital characteristics of molecules are investigated using high-harmonic spectroscopy, applied to molecules of N2 and CO2. In the latter case the two-dimensional high-harmonic spectroscopy, implemented using a two-color laser field, is applied to distinguish harmonics from different orbitals. Molecular high-harmonic spectroscopy will open a new route to investigate ultrafast dynamics of molecules.
Anomalous Dissipative Quantum Harmonic Oscillator
Institute of Scientific and Technical Information of China (English)
CHEN Dian-Yong; BAI Zhan-Wu; DONG Yu-Bing
2008-01-01
We investigate the low-temperature statistical properties of a harmonic oscillator coupled to a heat bath, where the low-frequency spectrum vanishes. We obtain the exact result of the zero point energy. Due to the low frequency shortage of environmental oscillators' spectral density, the coordinate and momentum correlation functions decay as r-4and r-6 respectively at zero temperature, where T is the correlation time. The low-temperature behavior of the mean energy does not violate the third law of thermodynamics, but differs largely from the Ohmic spectrum case.
Excited Sessile Drops Perform Harmonically
Chang, Chun-Ti; Steen, Paul H
2013-01-01
In our fluid dynamics video, we demonstrate our method of visualizing and identifying various mode shapes of mechanically oscillated sessile drops. By placing metal mesh under an oscillating drop and projecting light from below, the drop's shape is visualized by the visually deformed mesh pattern seen in the top view. The observed modes are subsequently identified by their number of layers and sectors. An alternative identification associates them with spherical harmonics, as demonstrated in the tutorial. Clips of various observed modes are presented, followed by a 10-second quiz of mode identification.
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.
Quantizing the damped harmonic oscillator
Energy Technology Data Exchange (ETDEWEB)
Latimer, D C [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)
2005-03-04
We consider the Fermi quantization of the classical damped harmonic oscillator (dho). In past work on the subject, authors double the phase space of the dho in order to close the system at each moment in time. For an infinite-dimensional phase space, this method requires one to construct a representation of the CAR algebra for each time. We show that the unitary dilation of the contraction semigroup governing the dynamics of the system is a logical extension of the doubling procedure, and it allows one to avoid the mathematical difficulties encountered with the previous method.
Killing vector fields and harmonic superfield theories
Energy Technology Data Exchange (ETDEWEB)
Groeger, Josua, E-mail: groegerj@mathematik.hu-berlin.de [Humboldt-Universität zu Berlin, Institut für Mathematik, Rudower Chaussee 25, 12489 Berlin (Germany)
2014-09-15
The harmonic action functional allows a natural generalisation to semi-Riemannian supergeometry, also referred to as harmonic, which resembles the supersymmetric sigma models studied in high energy physics. We show that Killing vector fields are infinitesimal supersymmetries of this harmonic action and prove three different Noether theorems in this context. En passant, we provide a homogeneous treatment of five characterisations of Killing vector fields on semi-Riemannian supermanifolds, thus filling a gap in the literature.
Polarization-fan high-order harmonics
Fleischer, Avner; Bordo, Eliyahu; Kfir, Ofer; Sidorenko, Pavel; Cohen, Oren
2017-02-01
We predict high-order harmonics in which the polarization within the spectral bandwidth of each harmonic varies with frequency continuously and significantly. For example, the interaction of counter-rotating circularly-polarized bichromatic drivers having close central frequencies with isotropic gas leads to the emission of polarization-fan harmonics where each harmonic in the spectrum has the following property: it is nearly circularly-polarized in one tail of the harmonic peak, linear in the center of the peak and nearly circular with the opposite helicity in the opposite tail. Also, we show that polarization-fan high harmonics with modulated ellipticity are obtained when elliptical drivers are used. Polarization-fan harmonics are obtained as a result of multiple (at least two) head-on recollisions of electrons with their parent ions occurring from different angles in a two-dimensional plane. The use of bichromatic drivers with close central frequencies largely preserves the single-cycle, single-atom and macroscopic physics of ‘ordinary’ high harmonic generation, where both the driver and high harmonics are linearly polarized. Thus, it should offer several attracting features, including (i) a direct route for extending the maximal photon energy of observed helical high harmonics to keV by using bichromatic drivers only in the mid-IR region and (ii) utilizing phase matching methods that were developed for ‘ordinary’ high harmonic generation driven by quasi-monochromatic pulses (e.g. pressure tuning phase matching). These polarization-fan harmonics may be utilized for exploring non-repetitive ultrafast chiral phenomena, e.g. dynamics of magnetic domains, in a single shot.
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
Harmonic functions on groups and Fourier algebras
Chu, Cho-Ho
2002-01-01
This research monograph introduces some new aspects to the theory of harmonic functions and related topics. The authors study the analytic algebraic structures of the space of bounded harmonic functions on locally compact groups and its non-commutative analogue, the space of harmonic functionals on Fourier algebras. Both spaces are shown to be the range of a contractive projection on a von Neumann algebra and therefore admit Jordan algebraic structures. This provides a natural setting to apply recent results from non-associative analysis, semigroups and Fourier algebras. Topics discussed include Poisson representations, Poisson spaces, quotients of Fourier algebras and the Murray-von Neumann classification of harmonic functionals.
Second-harmonic optical coherence tomography
Jiang, Yi; Tomov, Ivan; Wang, Yimin; Chen, Zhongping
2004-05-01
Second-harmonic optical coherence tomography, which uses coherence gating of second-order nonlinear optical responses of biological tissues for imaging, is described and demonstrated. Femtosecond laser pulses were used to excite second-harmonic waves from collagen harvested from rat tail tendon and a reference nonlinear crystal. Second-harmonic interference fringe signals were detected and used for image construction. Because of the strong dependence of second-harmonic generation on molecular and tissue structures, this technique imparts contrast and resolution enhancement to conventional optical coherence tomography.
Harmonic Retrieval in Colored ARMA Noise
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
We propose a new approach to harmonic retrieval in colored ARMA noise. A suitable filter is first used to remove all the sharp power spectrum peaks of the noisy observed process, then some kinds of cross correlation is employed to identify the noise characteristics. After filtering the noisy observed process with the identified noise characteristics again, SVD-TLS method can be applied to retrieve the harmonics. The proposed approach can be used to retrieve real-valued harmonic signals in colored ARMA noise with no restrictions on the phase coupling of harmonics and the distribution of the noise. Simulation examples show its effectiveness.
Effects of harmonic roving on pitch discrimination
DEFF Research Database (Denmark)
Santurette, Sébastien; de Kérangal, Mathilde le Gal; Joshi, Suyash Narendra
2015-01-01
Performance in pitch discrimination tasks is limited by variability intrinsic to listeners which may arise from peripheral auditory coding limitations or more central noise sources. The present study aimed at quantifying such “internal noise” by estimating the amount of harmonic roving required...... 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...
Harmonization of European track quality
Directory of Open Access Journals (Sweden)
Popović Zdenka
2014-01-01
Full Text Available This paper deals with characterisation of track geometry, track measuring and recording system, as well as geometric quality levels. The legal framework and state of the art in the field of harmonization of track geometry technical regulation in the Republic of Serbia were presented. In particular, the paper discusses the European standard EN 13848 Series (Parts 1-6. Principal track geometric parameters were analyzed according to EN 13848-1. Track geometric quality levels were examined according to EN 13848-5. The evaluation of track geometry quality according to prEN 13848-6 was analyzed as well. The objective of creation of the European standard EN 13848 Series (Parts 1-6 was defining a unique approach for the evaluation of track geometry quality of various European railway infrastructures. The Institute for Standardization of Serbia has adopted and published five of six parts of this standard. This paper is a part of an effort to harmonize the Serbian railway technical regulations with those of the European Union. .
Observation of a Hybrid Spin Resonance
Bai, M.; Allgower, C.; Ahrens, L.; Alessi, J.; Brown, K.; Bunce, G.; Cameron, P.; Chu, C. M.; Courant, E. D.; Glenn, J. W.; Huang, H.; Jeon, D.; Kponou, A. E.; Krueger, K.; Luccio, A.; Makdisi, Y. I.; Lee, S. Y.; Ratner, L.; Reece, K.; Roser, T.; Spinka, H.; Syphers, M. J.; Tsoupas, N.; Underwood, D. G.; van Asselt, W.; Williams, N.; Yokosawa, A.
2000-02-01
A new type of spin depolarization resonance has been observed at the Brookhaven Alternating Gradient Synchrotron (AGS). This spin resonance is identified as a strong closed-orbit sideband around the dominant intrinsic spin resonance. The strength of the resonance was proportional to the 9th harmonic component of the horizontal closed orbit and proportional to the vertical betatron oscillation amplitude. This ``hybrid'' spin resonance cannot be overcome by the partial snake at the AGS, but it can be corrected by the harmonic orbit correctors.
Energy Technology Data Exchange (ETDEWEB)
West, J.G.W. [Electrical Machines (United Kingdom)
1997-07-01
The reasons for adopting hybrid vehicles result mainly from the lack of adequate range from electric vehicles at an acceptable cost. Hybrids can offer significant improvements in emissions and fuel economy. Series and parallel hybrids are compared. A combination of series and parallel operation would be the ideal. This can be obtained using a planetary gearbox as a power split device allowing a small generator to transfer power to the propulsion motor giving the effect of a CVT. It allows the engine to run at semi-constant speed giving better fuel economy and reduced emissions. Hybrid car developments are described that show the wide range of possible hybrid systems. (author)
Reduction of multiple harmonic sums and harmonic polylogarithms
Energy Technology Data Exchange (ETDEWEB)
Bluemlein, J. [DESY, Deutsches Elektronen Synchrotron, DESY, Platanenallee 6, D-15735 Zeuthen (Germany)]. E-mail: johannes.blumlein@desy.de
2004-11-21
The alternating and non-alternating harmonic sums and other algebraic objects of the same equivalence class are connected by algebraic relations which are induced by the product of these quantities and which depend on their index class rather than on their value. We show how to find a basis of the associated algebra. The length of the basis l is found to be =<1/d, where d is the depth of the sums considered and is given by the 2nd Witt formula. It can be also determined by counting the Lyndon words of the respective index set. The relations derived can be used to simplify results of higher-order calculations in QED and QCD.
Reduction of multiple harmonic sums and harmonic polylogarithms
Blümlein, J.
2004-11-01
The alternating and non-alternating harmonic sums and other algebraic objects of the same equivalence class are connected by algebraic relations which are induced by the product of these quantities and which depend on their index class rather than on their value. We show how to find a basis of the associated algebra. The length of the basis l is found to be ⩽1/d, where d is the depth of the sums considered and is given by the 2nd Witt formula. It can be also determined by counting the Lyndon words of the respective index set. The relations derived can be used to simplify results of higher-order calculations in QED and QCD.
REAL TIME GA AND ANN BASED SELECTIVE HARMONIC ELIMINATION IN 9 LEVEL UPS INVERTER
Directory of Open Access Journals (Sweden)
E. Anandha Banu
2016-07-01
Full Text Available High quality power is very much critical and essential for medical, research and industrial applications to bring good quality results with accurate evaluation. Hence all the sensitive equipments and critical loads need to be provided with high quality and reliable power, where Uninterruptible Power Supplies (UPS are mainly used to supply reliable power to these loads. Inverter is the main component of a UPS. In the recent times, by the advanced usage of semiconductor devices and non linear loads, harmonics are unavoidable. So the actual challenge for UPS is, under a non linear condition of load, it has to maintain a high quality sinusoidal output voltage. In this paper, the inverter of UPS is replaced by a nine level cascaded H bridge multilevel inverter with equal DC sources and harmonics can be eliminated by the optimal selection of switching angle by using Selective Harmonic Elimination Pulse Width Modulation (SHE-PWM technique along with a hybrid technique to optimize and minimize the Total Harmonic Distortion(THD. The proposed hybrid technique utilizes the Genetic Algorithm (GA and Neural Network (NN. The switching angles are calculated offline using Genetic Algorithm. Then the NN is trained by these switching angles and the real time switching angles are found out by Neural Network. The proposed technique is tested over a nine level cascaded H-bridge inverter and the resultant fundamental and harmonic voltages are analysed. Then, simulation is carried out in Matlab/Simulink environment and the results indicate that the switching angles obtained using this method results in efficient harmonic minimization.
The harmonized INFOGEST in vitro digestion method
Egger, Lotti; Ménard, Olivia; Delgado-Andrade, Cristina; Alvito, Paula; Assunção, Ricardo; Balance, Simon; Barberá, Reyes; Brodkorb, Andre; Cattenoz, Thomas; Clemente, Alfonso; Comi, Irene; Dupont, Didier; Garcia-Llatas, Guadalupe; Lagarda, María Jesús; Feunteun, Le Steven; Janssen Duijghuijsen, Lonneke; Karakaya, Sibel; Lesmes, Uri; Mackie, Alan R.; Martins, Carla; Meynier, Anne; Miralles, Beatriz; Murray, B.S.; Pihlanto, Anne; Picariello, Gianluca; Santos, C.N.; Simsek, Sebnem; Recio, Isidra; Rigby, Neil; Rioux, Laurie Eve; Stoffers, Helena; Tavares, Ana; Tavares, Lucelia; Turgeon, Sylvie; Ulleberg, E.K.; Vegarud, G.E.; Vergères, Guy; Portmann, Reto
2016-01-01
Within the active field of in vitro digestion in food research, the COST Action INFOGEST aimed to harmonize in vitro protocols simulating human digestion on the basis of physiologically inferred conditions. A harmonized static in vitro digestion (IVD) method was recently published as a primary
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.
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.
Some Interval 2-Tuple Linguistic Harmonic Mean Operators and Their Application in Material Selection
Directory of Open Access Journals (Sweden)
Meng-Meng Shan
2016-01-01
Full Text Available We investigate the multiple attribute group material selection problems in which the attribute values take the form of interval 2-tuple linguistic information. Firstly, some operational laws and possibility degree of interval 2-tuple linguistic variables are introduced. Then, we develop some interval 2-tuple linguistic aggregation operators called interval 2-tuple hybrid harmonic mean (ITHHM operator, induced interval 2-tuple ordered weighted harmonic mean (I-ITOWHM operator, and induced interval 2-tuple hybrid harmonic mean (I-ITHHM operator and study some desirable properties of the I-ITOWHM operator. In particular, all these operators can be reduced to aggregate 2-tuple linguistic variables. Based on the I-ITHHM and the ITWHM (interval 2-tuple weighted harmonic mean operators, an approach to multiple attribute group decision-making with interval 2-tuple linguistic information is proposed. Finally, a practical application to material selection problem is given to verify the developed approach and to demonstrate its practicality and effectiveness.
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.
Libsharp - spherical harmonic transforms revisited
Reinecke, Martin
2013-01-01
We present libsharp, a code library for spherical harmonic transforms (SHTs), which evolved from the libpsht library, addressing several of its shortcomings, such as adding MPI support for distributed memory systems and SHTs of fields with arbitrary spin, but also supporting new developments in CPU instruction sets like the Advanced Vector Extensions (AVX) or fused multiply-accumulate (FMA) instructions. The library is implemented in portable C99 and provides an interface that can be easily accessed from other programming languages such as C++, Fortran, Python etc. Generally, libsharp's performance is at least on par with that of its predecessor; however, significant improvements were made to the algorithms for scalar SHTs, which are roughly twice as fast when using the same CPU capabilities. The library is available at http://sourceforge.net/projects/libsharp/ under the terms of the GNU General Public License.
High Orbital Angular Momentum Harmonic Generation
Vieira, J.; Trines, R. M. G. M.; Alves, E. P.; Fonseca, R. A.; Mendonça, J. T.; Bingham, R.; Norreys, P.; Silva, L. O.
2016-12-01
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 realized in any nonlinear optical Kerr media supporting three-wave interactions.
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.
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.
Power Factor Correction to Mitigate Harmonic Distortion
Kochetkov, Gary
Many direct current (DC) devices must receive their power from the alternating current (AC) grid. Rectifiers use diodes to create DC for these devices. Due to diodes' non-linear nature however, harmonics are created and these travel back into the grid. A significant presence of harmonics causes component heating and possible malfunction. A harmonic mitigation procedure is needed. With the correct usage of transistors, the current drawn by a rectifier can be manipulated to remove almost all harmonics. This process is called power factor correction (PFC), and formally acts to reduce the total harmonic distortion (THD) of the current. To investigate this, a three phase active rectifier was computer simulated and a controller was designed to provide switching signals for the transistors. Finally, the device was constructed in the laboratory to drive a DC motor, verifying its operating principle outside of the idealities of simulation.
Harmonics mitigation on industrial loads using series and parallel ...
African Journals Online (AJOL)
This work compared the use of series and parallel resonant harmonic filters in suppressing harmonics using Simulink ... From the analysis, series resonant filter mitigated the total harmonic distortion from 30.080% to 3.460%. ... Article Metrics.
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.
Aripin, Haji; Mitsudo, Seitaro; Sudiana, I. Nyoman; Tani, Shinji; Sako, Katsuhide; Fujii, Yutaka; Saito, Teruo; Idehara, Toshitaka; Sabchevski, Sliven
2011-06-01
In this paper, we present and discuss experimental results from a microwave sintering of a silica-glass ceramic, produced from a silica xerogel extracted from a sago waste ash. As a radiation source for the microwave heating a sub-millimeter wave gyrotron (Gyrotron FU CW I) with an output frequency of 300 GHz has been used. The powders of silica xerogel have been dry pressed and then sintered at temperatures ranging from 300°C to 1500°C. The influence of the sintering temperature on the technological properties such as porosity and bulk density was studied in detail. Furthermore, X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy have been used in order to study the structure of the produced silica glass-ceramics. It has been found that the silica xerogel crystallizes at a temperature of 800°C, which is about 200°C lower than the one observed in the conventional process. The silica xerogel samples sintered by their irradiation with a sub-millimeter wave at 900°C for 18 minutes are fully crystallized into a silica glass-ceramic with a density of about 2.2 g/cm3 and cristobalite as a major crystalline phase. The results obtained in this study allow one to conclude that the microwave sintering with sub-millimeter waves is an appropriate technological process for production of silica glass-ceramics from a silica xerogel and is characterized with such advantages as shorter times of the thermal cycle, lower sintering temperatures and higher quality of the final product.
Energy Technology Data Exchange (ETDEWEB)
Akshanov, B.S.; Pyatov, V.N.; Sebko, V.P.; Tyupa, V.I.
1975-01-01
In an analysis of the effect of a transverse magnetic field on the parameters of a trap using a combination of the second and third harmonics of a helical field, an averaging method is used to calculate the parameters of a hybrid (l = 2 plus l = 3) stellarator magnetic trap in a homogeneous, external, transverse magnetic field B/sub perpendicular/. The stabilizing effect of the second harmonic of the magnetic field on the configuration is discussed.
Field measurement and analysis of harmonic levels
Energy Technology Data Exchange (ETDEWEB)
Karunakara, K.; Muthu Kumar, E.; Rajesh Kumar, O.; Nambudiri, P.V.V.; Srinivasan, K.N. [Central Power Research Institute, Bangalore (India)
1999-07-01
The level of harmonics on the transmission and distribution network is rising over the years, due to the rapid development and usage of electronic and semiconductor devices in the industries, as these devices produce harmonic currents. As the harmonic currents produced by these devices are unproductive and affect the ideal sinusoidal waveshapes, these have to be limited to a tolerable limit at the Point of Common Coupling (PCC). Before setting a tolerable limit on harmonics it is necessary to know the level of harmonics already present in the system, so that the limits suggested are comprehensive and practicable. To have a fair idea about the current and voltage harmonics on the Indian system, Central Power Research Institute (CPRI) has carried out a lot of measurements both on the distribution network and transmission network over the past 13 years. This paper discusses the harmonic measurements carried out by CPRI on different loads and voltage levels on the Indian network. The methodology adopted for measurement and results are also discussed in this paper. (author)
Intravascular ultrasound tissue harmonic imaging in vivo.
Frijlink, Martijn E; Goertz, David E; van Damme, Luc C A; Krams, Rob; van der Steen, Antonius F W
2006-10-01
Tissue harmonic imaging (THI) has been shown to increase image quality of medical ultrasound in the frequency range from 2 to 10 MHz and might, therefore, also be used to improve image quality in intravascular ultrasound (IVUS). In this study we constructed a prototype IVUS system that could operate in both fundamental frequency and second harmonic imaging modes. This system uses a conventional, continuously rotating, single-element IVUS catheter and was operated in fundamental 20 MHz, fundamental 40 MHz, and harmonic 40 MHz modes (transmit 20 MHz, receive 40 MHz). Hydrophone beam characterization measurements demonstrated the build-up of a second harmonic signal as a function of increasing pressure. Imaging experiments were conducted in both a tissue-mimicking phantom and in an atherosclerotic animal model in vivo. Acquisitions of fundamental 20 and 40 MHz and second harmonic acquisitions resulted in cross sections of the phantom and a rabbit aorta. The harmonic results of the imaging experiments showed the feasibility of intravascular THI with a conventional IVUS catheter both in a phantom and in vivo. The harmonic acquisitions also showed the potential of THI to reduce image artifacts compared to fundamental imaging.
Schneidmiller, E A
2012-01-01
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...
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...... of offshore wind farm (OWF) systems....... 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...
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.
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...... distortion is not achievable with CMOS current mirrors...
Asymptotic porosity of planar harmonic measure
Graczyk, Jacek; Świaţek, Grzegorz
2013-04-01
We study the distribution of harmonic measure on connected Julia sets of unicritical polynomials. Harmonic measure on a full compact set in ℂ is always concentrated on a set which is porous for a positive density of scales. We prove that there is a topologically generic set {A} in the boundary of the Mandelbrot set such that for every cin {A}, β>0, and λ∈(0,1), the corresponding Julia set is a full compact set with harmonic measure concentrated on a set which is not β-porous in scale λ n for n from a set with positive density amongst natural numbers.
Harmonic analysis of a cruise ship network
Energy Technology Data Exchange (ETDEWEB)
Guerin, P.; Miegeville, L. [GE44, France (France); Sahnouni, K. [Chantiers de l' Atlantique (France)
2000-07-01
The number and the power rating of equipment using power electronics have been increasing on board of the ships for many years. At present, the harmonic disturbance must be taken into account from the design stage in order to ensure the smooth running of the installation. This paper presents a harmonic analysis of the electrical distribution system of a cruise ship. The comparison between the evaluated and the real harmonic levels allows us to discuss about the interest and the limits of the estimates. (authors)
Harmonic Oscillators and Elementary Particles
Sobouti, Y
2016-01-01
Two dynamical systems with same symmetry should have features in common, and as far as their shared symmetry is concerned, one may represent the other. The three light quark constituents of the hadrons, a) have an approximate flavor SU(3) symmetry, b) have an exact color SU(3) symmetry, and c) as spin 1/2 particles, have a Lorentz SO(3,1) symmetry. So does a 3D harmonic oscillator. a) Its Hamiltonian has the SU(3) symmetry, breakable if the 3 fundamental modes of oscillation are not identical. b) The 3 directions of oscillation have the permutation symmetry. This enables one to create three copies of unbreakable SU(3) symmetry for each mode of the oscillation, and mimic the color of the elementary particles. And c) The Lagrangian of the 3D oscillator has the SO(3,1) symmetry. This can be employed to accommodate the spin of the particles. In this paper we draw up a one-to-one correspondence between the eigen modes of the Poisson bracket operator of the 3D oscillator and the flavor multiplets of the particles, ...
Harmonization of immunotoxicology study guidelines
Institute of Scientific and Technical Information of China (English)
NakaK
2002-01-01
Guidance for immunotoxicology studies has been intensively discussed.The European Medicnes Evaluation Agency published the draft guidance on immunotoxicity on December 16,1999 and finalized it on July 27,2000.In the meantime,the US Food and Drug Administration (FDA) published the draft guidance on May 11,2001.The Japanese Ministry of Health,Labor and Welfare and the Japan Pharmaceutical Manufactures Association submitted their interim draft guidance to the International Conference of Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use(ICH) for discussion of Decemeber 20,2001.The approaches are taken in these(draft) guidance documents.A major difference among the guidance of the three regions is that only the EU guidance requires some immune function tests for all new medicinal products.The informal expert working proup meeting held in the ICH on February 7,2002 resched the conchusion that the guidelines should be eventually hamonized after collecting more data.A scientific session on immunotoxicity testing will be included in the ICH6,Osake,November 2003.
High-order harmonics with frequency-varying polarization within each harmonic
Fleischer, Avner; Sidorenko, Pavel; Cohen, Oren
2014-01-01
We predict high-order harmonics in which the polarization within the spectral bandwidth of each harmonic varies continuously and significantly. For example, the interaction of counter-rotating circularly-polarized bichromatic drivers having close central frequencies with isotropic gas leads to the emission of polarization-fan harmonics which are nearly circularly-polarized in one tail of the harmonic peak, linear in the center of the peak and nearly circular with the opposite helicity in the opposite tail. Polarization fan harmonics are obtained as a result of multiple (at least two) head-on recollisions of electrons with their parent ions occurring from different angles. The process can be phase-matched using standard methods (e.g. pressure tuning phase matching) and maintains the single-atom polarization property through propagation. These polarization-fan harmonics may be used for exploring non-repetitive ultrafast chiral phenomena, e.g. dynamics of magnetic domains, in a single shot
Cavity-Enhanced Third Harmonic Generation
Institute of Scientific and Technical Information of China (English)
YANG Xiao-Xue; WU Ying
2005-01-01
We derive the analytical expression of microcavity-enhanced factor for third harmonic generation in terms of detunings, linewidths, and the Purcell factors of the relevant microcavity modes. It is suitable for microcavities with any dimensions and arbitrary geometric shapes.
On conformal supergravity and harmonic superspace
Butter, Daniel
2015-01-01
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^{4|8} by the tangent bundle of CP^1. The resulting superspace M^{4|8} x TCP^1 can be identified in a certain gauge with the conventional harmonic superspace M^{4|8} x S^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 hyperkahler cone coupled to conformal supergravity. Further applications are also sketched.
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. ...
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.
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.
Terahertz optics: Terahertz-driven harmonics
Kim, K. Y.; You, Y. S.
2014-02-01
Researchers have demonstrated high-harmonic generation using strong terahertz pulses in a bulk solid without damaging it. The mechanism underpinning such an extreme nonlinearity also generates coherent electromagnetic radiation covering the terahertz, infrared and optical regions.
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.
Stable Stationary Harmonic Maps to Spheres
Institute of Scientific and Technical Information of China (English)
Fang Hua LIN; Chang You WANG
2006-01-01
For k ≥ 3, we establish new estimate on Hausdorff dimensions of the singular set of stable-stationary harmonic maps to the sphere Sk. We show that the singular set of stable-stationary harmonic maps from B5 to S3 is the union of finitely many isolated singular points and finitely many Holder continuous curves. We also discuss the minimization problem among continuous maps from Bn to S2.
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.
Structural relations between nested harmonic sums
Energy Technology Data Exchange (ETDEWEB)
Bluemlein, J.
2008-07-15
We describe the structural relations between nested harmonic sums emerging in the description of physical single scale quantities up to the 3-loop level in renormalizable gauge field theories. These are weight w=6 harmonic sums. We identify universal basic functions which allow to describe a large class of physical quantities and derive their complex analysis. For the 3-loop QCD Wilson coefficients 35 basic functions are required, whereas a subset of 15 describes the 3-loop anomalous dimensions. (orig.)
Index calculation by means of harmonic expansion
Imamura, Yosuke
2015-01-01
We review derivation of superconformal indices by means of supersymmetric localization and spherical harmonic expansion for 3d N=2, 4d N=1, and 6d N=(1,0) supersymmetric gauge theories. We demonstrate calculation of indices for vector multiplets in each dimensions by analysing energy eigenmodes in S^pxR. For the 6d index we consider the perturbative contribution only. We put focus on technical details of harmonic expansion rather than physical applications.
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.
Hybrid VAR compensator with improved efficiency
Directory of Open Access Journals (Sweden)
V. V. Burlaka
2015-03-01
Full Text Available In modern electrical networks thyristor-switched capacitors (TSC are most used devices for VAR compensation. These devices don’t contain rotating parts and mechanical contacts, provide a stepwise control of reactive power and no generation of harmonics to the network. However, with the help of TSC it’s not possible to ensure smooth control of reactive power and capacitor banks (CB are exposed to the negative impact of higher harmonic components of the network voltage. Hybrid VAR compensator don’t have such drawbacks. It consists of active filter (AF and capacitor bank with discrete regulation. The main drawback of such systems is the necessity of accessing all six terminals of CB, while most of them are manufactured with three terminals, internally delta-connected. In the article, the topology and control system of hybrid VAR compensator free from beforementioned drawback, is proposed. The control system provides operating modes of overcompensation or undercompensation reactive power. VAR distribution regulator performs redistribution of reactive power between active filter and capacitor banks with the condition to minimize active filter’s power. Scheme of the hybrid VAR compensator, which includes a three-phase three-terminal delta-connected capacitor banks, is shown. Proposed approach allows to provide smooth control of reactive power, isolate the capacitor bank from harmonic currents and use a more effective low-voltage power components
1985-04-15
perpendicular to a magnetic field tics, radar, and far-infrared astronomy. One wit ’ loss in a collisionless plasma.4 It is * such mechanism is the...16 I -3.218 B13 B16 B17 B18 I Big 0.1283 x 10- 9.623 I 0.1558 x 10- 11 -0.1431 x 10- ! 0.8756 x 10 - 20 64 Eq.(4.25), the corresponding...10- 1 -0.8546 x 10- 3 I B 15 B16 B17 I Big Big -0.8612 x 10’u j -. 1283 x 10 0.4692 x 10’ " -0.7586 x 10 0.4973 x 10- We may conclude that for
Harmonic moment dynamics in Laplacian growth.
Leshchiner, Alexander; Thrasher, Matthew; Mineev-Weinstein, Mark B; Swinney, Harry L
2010-01-01
Harmonic moments are integrals of integer powers of z=x+iy over a domain. Here, the domain is an exterior of a bubble of air growing in an oil layer between two horizontal closely spaced plates. Harmonic moments are a natural basis for such Laplacian growth phenomena because, unlike other representations, these moments linearize the zero surface tension problem [S. Richardson, J. Fluid Mech. 56, 609 (1972)], so that all moments except the lowest one (the area of the bubble) are conserved in time. In our experiments, we directly determine the harmonic moments and show that for nonzero surface tension, all moments (except the lowest one) decay in time rather than exhibiting the divergences of other representations. Further, we derive an expression that relates the derivative of the k(th) harmonic moment M(k) to measurable quantities (surface tension, viscosity, the distance between the plates, and a line integral over the contour encompassing the growing bubble). The laboratory observations are in good accord with the expression we derive for dM(k)/dt , which is proportional to the surface tension; thus in the zero surface tension limit, the moments (above k=0) are all conserved, in accord with Richardson's theory. In addition, from the measurements of the time evolution of the harmonic moments we obtain a value for the surface tension that is within 20% of the accepted value. In conclusion, our analysis and laboratory observations demonstrate that an interface dynamics description in terms of harmonic moments is physically realizable and robust.
2013-01-01
The main goal of this book is to provide a state of the art of hybrid metaheuristics. The book provides a complete background that enables readers to design and implement hybrid metaheuristics to solve complex optimization problems (continuous/discrete, mono-objective/multi-objective, optimization under uncertainty) in a diverse range of application domains. Readers learn to solve large scale problems quickly and efficiently combining metaheuristics with complementary metaheuristics, mathematical programming, constraint programming and machine learning. Numerous real-world examples of problems and solutions demonstrate how hybrid metaheuristics are applied in such fields as networks, logistics and transportation, bio-medical, engineering design, scheduling.
A Hybridized Centroid Technique for 3D Molodensky-Badekas ...
African Journals Online (AJOL)
Richannan
two new hybrid centroid techniques known as the harmonic-quadratic mean and arithmetic- ... was subsequently involved in triangulation nets with other trigonometric ..... The functional relation that is used to compute the TLS solution is given by ..... mathematical models is an approximation of reality, hence it is worth noting ...
Shen, Che-Chou; Shi, Tai-Yu
2011-07-01
Ultrasound tissue harmonic signal generally provides superior image quality as compared to the linear signal. However, since the generation of the tissue harmonic signal is based on finite amplitude distortion of the propagating waveform, the penetration and the sensitivity in tissue harmonic imaging are markedly limited because of the low signal-to-noise ratio (SNR). The method of third harmonic (3f(0)) transmit phasing can improve the tissue harmonic SNR by transmitting at both the fundamental (2.25MHz) and the 3f(0) (6.75MHz) frequencies to achieve mutual enhancement between the frequency-sum and the frequency-difference components of the second harmonic signal. To further increase the SNR without excessive transmit pressure, coded excitation can be incorporated in 3f(0) transmit phasing to boost the tissue harmonic generation. Our analyses indicate that the phase-encoded Golay excitation is suitable in 3f(0) transmit phasing due to its superior transmit bandwidth efficiency. The resultant frequency-sum and frequency-difference components of tissue harmonic signal can be simultaneously Golay-encoded for SNR improvement. The increase of the main-lobe signal with the Golay excitation in 3f(0) transmit phasing are consistent between the tissue harmonic measurements and the simulations. B-mode images of the speckle generating phantom also demonstrate the increases of tissue harmonic SNR for about 11dB without noticeable compression artifacts. For tissue harmonic imaging in combination with the 3f(0) transmit phasing method, the Golay excitation can provide further SNR improvement. Meanwhile, the axial resolution can be effectively restored by pulse compression while the lateral resolution remains unchanged. Copyright © 2010 Elsevier B.V. All rights reserved.
Cetorelli, Nicola
2014-01-01
I introduce the concept of hybrid intermediaries: financial conglomerates that control a multiplicity of entity types active in the "assembly line" process of modern financial intermediation, a system that has become known as shadow banking. The complex bank holding companies of today are the best example of hybrid intermediaries, but I argue that financial firms from the "nonbank" space can just as easily evolve into conglomerates with similar organizational structure, thus acquiring the cap...
CSIR Research Space (South Africa)
Jacob John, Maya
2009-04-01
Full Text Available effect was observed for the elongation at break of the hybrid composites. The impact strength of the hybrid composites increased with the addition of glass fibres. The tensile and impact properties of thermoplastic natural rubber reinforced short... panels made from conventional structural materials. Figure 3 illustrates the performance of cellular biocomposite panels against conventional systems used for building and residential construction, namely a pre- cast pre-stressed hollow core concrete...
Modified ADALINE algorithm for harmonic estimation and selective harmonic elimination in inverters
Vasumathi, B.; Moorthi, S.
2011-11-01
In digital signal processing, algorithms are very well developed for the estimation of harmonic components. In power electronic applications, an objective like fast response of a system is of primary importance. An effective method for the estimation of instantaneous harmonic components, along with conventional harmonic elimination technique, is presented in this article. The primary function is to eliminate undesirable higher harmonic components from the selected signal (current or voltage) and it requires only the knowledge of the frequency of the component to be eliminated. A signal processing technique using modified ADALINE algorithm has been proposed for harmonic estimation. The proposed method stays effective as it converges to a minimum error and brings out a finer estimation. A conventional control based on pulse width modulation for selective harmonic elimination is used to eliminate harmonic components after its estimation. This method can be applied to a wide range of equipment. The validity of the proposed method to estimate and eliminate voltage harmonics is proved with a dc/ac inverter as a simulation example. Then, the results are compared with existing ADALINE algorithm for illustrating its effectiveness.
Cross-border Intra-group Hybrid Finance and International Taxation
Eberhartinger, Eva; Pummerer, Erich; Göritzer, Andreas
2010-01-01
In intra-group finance hybrid instruments allow for tailor-made form of finance. Hence hybrid finance is often used for international tax planning in multinational groups. Due to a lack of international tax harmonization or tax coordination qualification conflict can arise. A specific hybrid instrument is classified as debt in one country, and as equity in the other country. This may lead to double taxation. In the reverse case, double non-taxation can arise. Against this legal background one...
Stoelinga, Christophe; Heo, Inseok; Long, Glenis; Lee, Jungmee; Lutfi, Robert; Chang, An-Chieh
2015-12-01
The human auditory system has a remarkable ability to "hear out" a wanted sound (target) in the background of unwanted sounds. One important property of sound which helps us hear-out the target is inharmonicity. When a single harmonic component of a harmonic complex is slightly mistuned, that component is heard to separate from the rest. At high harmonic numbers, where components are unresolved, the harmonic segregation effect is thought to result from detection of modulation of the time envelope (roughness cue) resulting from the mistuning. Neurophysiological research provides evidence that such envelope modulations are represented early in the auditory system, at the level of the auditory nerve. When the mistuned harmonic is a low harmonic, where components are resolved, the harmonic segregation is attributed to more centrally-located auditory processes, leading harmonic components to form a perceptual group heard separately from the mistuned component. Here we consider an alternative explanation that attributes the harmonic segregation to detection of modulation when both high and low harmonic numbers are mistuned. Specifically, we evaluate the possibility that distortion products in the cochlea generated by the mistuned component introduce detectable beating patterns for both high and low harmonic numbers. Distortion product otoacoustic emissions (DPOAEs) were measured using 3, 7, or 12-tone harmonic complexes with a fundamental frequency (F0) of 200 or 400 Hz. One of two harmonic components was mistuned at each F0: one when harmonics are expected to be resulted and the other from unresolved harmonics. Many non-harmonic DPOAEs are present whenever a harmonic component is mistuned. These non-harmonic DPOAEs are often separated by the amount of the mistuning (ΔF). This small frequency difference will generate a slow beating pattern at ΔF, because this beating is only present when a harmonic component is mistuned, it could provide a cue for behavioral detection
Nonlinear harmonics in the high-gain harmonic generation (HGHG) experiment
Biedron, S G; Milton, S V; Yu, L H; Wang, X J
2001-01-01
We have previously performed rigorous analyses of the nonlinear harmonics in self-amplified spontaneous emission (SASE) free-electron lasers (FELs) using a 3D simulation code. To date, we have presented only preliminary results of these higher harmonics resulting in the high-gain harmonic generation (HGHG) process. A single-pass, high-gain FEL experiment based on the HGHG theory is underway at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL) in collaboration with the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). Using the above experiment's design parameters, the specific case of the harmonic output from the HGHG experiment will be examined using a 3D simulation code. The sensitivity of nonlinear harmonic output for this HGHG experiment as functions of emittance, energy spread, and peak current in both cases, and for the dispersive section strength and input seed power in the HGHG case, will be presented.
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-model, are in...... behavior interaction and dynamic transfer procedure. Frequency domain as well as time domain simulation results are represented by means of HSS modeling to verify the theoretical analysis. Experimental results are also included to validate the method....... 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...
High-harmonic spectroscopy of molecular isomers
Energy Technology Data Exchange (ETDEWEB)
Wong, M. C. H.; Brichta, J.-P.; Bhardwaj, V. R. [Department of Physics, University of Ottawa, 150 Louis-Pasteur, Ottawa, Ontario, K1N 6N5 (Canada); Spanner, M.; Patchkovskii, S. [National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6 (Canada)
2011-11-15
We demonstrate that high-order-harmonic generation (HHG) spectroscopy can be used to probe stereoisomers of randomly oriented 1,2-dichloroethylene (C{sub 2}H{sub 2}Cl{sub 2}) and 2-butene (C{sub 4}H{sub 8}). The high-harmonic spectra of these isomers are distinguishable over a range of laser intensities and wavelengths. Time-dependent numerical calculations of angle-dependent ionization yields for 1,2-dichloroethylene suggest that the harmonic spectra of molecular isomers reflect differences in their strong-field ionization. The subcycle ionization yields for the cis isomer are an order of magnitude higher than those for the trans isomer. The sensitivity in discrimination of the harmonic spectra of cis- and trans- isomers is greater than 8 and 5 for 1,2-dichloroethylene and 2-butene, respectively. We show that HHG spectroscopy cannot differentiate the harmonic spectra of the two enantiomers of the chiral molecule propylene oxide (C{sub 3}H{sub 6}O).
Thomson scattering diagnostic on the Compact Toroidal Hybrid Experiment
Traverso, Peter; Maurer, D. A.; Ennis, D. A.; Hartwell, G. J.
2016-10-01
A Thomson scattering system is being commissioned for the non-axisymmetric plasmas of the Compact Toroidal Hybrid (CTH), a five-field period current-carrying torsatron. The system takes a single point measurement at the magnetic axis to both calibrate the two- color soft x-ray Te system and serve as an additional diagnostic for the V3FIT 3D equilibrium reconstruction code. A single point measurement will reduce the uncertainty in the reconstructed peak pressure by an order of magnitude for both current-carrying plasmas and future gyrotron-heated stellarator plasmas. The beam, generated by a frequency doubled Continuum 2 J, Nd:YaG laser, is passed vertically through an entrance Brewster window and a two-aperture optical baffle system to minimize stray light. The beam line propagates 8 m to the CTH device mid-plane with the beam diameter < 3 mm inside the plasma volume. Thomson scattered light is collected by two adjacent f/2 plano-convex condenser lenses and focused onto a custom fiber bundle. The fiber is then re-bundled and routed to a Holospec f/1.8 spectrograph to collect the red-shifted scattered light from 535-565 nm. The system has been designed to measure plasmas with core Te of 100 to 200 eV and densities of 5 ×1018 to 5 ×1019 m-3. Work supported by USDOE Grant DE-FG02-00ER54610.
Generation of high harmonics from silicon
Vampa, Giulio; Thiré, Nicolas; Schmidt, Bruno E; Légaré, Francois; Klug, Dennis D; Corkum, Paul B
2016-01-01
We generate high-order harmonics of a mid-infrared laser from a silicon single crystal and find their origin in the recollision of coherently accelerated electrons with their holes, analogously to the atomic and molecular case, and to ZnO [Vampa et al., Nature 522, 462-464 (2015)], a direct bandgap material. Therefore indirect bandgap materials are shown to sustain the recollision process as well as direct bandgap materials. Furthermore, we find that the generation is perturbed with electric fields as low as 30 V/$\\mu$m, equal to the DC damage threshold. Our results extend high-harmonic spectroscopy to the most technologically relevant material, and open the possibility to integrate high harmonics with conventional electronics.
Coded excitation for ultrasound tissue harmonic imaging.
Song, Jaehee; Kim, Sangwon; Sohn, Hak-Yeol; Song, Tai-Kyong; Yoo, Yang Mo
2010-05-01
Coded excitation can improve the signal-to-noise ratio (SNR) in ultrasound tissue harmonic imaging (THI). However, it could suffer from the increased sidelobe artifact caused by incomplete pulse compression due to the spectral overlap between the fundamental and harmonic components of ultrasound signal after nonlinear propagation in tissues. In this paper, three coded tissue harmonic imaging (CTHI) techniques based on bandpass filtering, power modulation and pulse inversion (i.e., CTHI-BF, CTHI-PM, and CTHI-PI) were evaluated by measuring the peak range sidelobe level (PRSL) with varying frequency bandwidths. From simulation and in vitro studies, the CTHI-PI outperforms the CTHI-BF and CTHI-PM methods in terms of the PRSL, e.g., -43.5dB vs. -24.8dB and -23.0dB, respectively. Copyright 2010 Elsevier B.V. All rights reserved.
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.
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...
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.
Microscopic optical buffering in a harmonic potential
Sumetsky, M
2015-01-01
In the early days of quantum mechanics, Schr\\"odinger noticed that oscillations of a wave packet in a one-dimensional harmonic potential well are periodic and, in contrast to those in anharmonic potential wells, do not experience distortion over time. This original idea did not find applications up to now since an exact one-dimensional harmonic resonator does not exist in nature and has not been created artificially. However, an optical pulse propagating in a bottle microresonator (a dielectric cylinder with a nanoscale-high bump of the effective radius) can exactly imitate a quantum wave packet in the harmonic potential. Here, we propose a tuneable microresonator that can trap an optical pulse completely, hold it as long as the material losses permit, and release it without distortion. This result suggests the solution of the long standing problem of creating a microscopic optical buffer, the key element of the future optical signal processing devices.
Robust Speech Recognition Using a Harmonic Model
Institute of Scientific and Technical Information of China (English)
许超; 曹志刚
2004-01-01
Automatic speech recognition under conditions of a noisy environment remains a challenging problem. Traditionally, methods focused on noise structure, such as spectral subtraction, have been employed to address this problem, and thus the performance of such methods depends on the accuracy in noise estimation. In this paper, an alternative method, using a harmonic-based spectral reconstruction algorithm, is proposed for the enhancement of robust automatic speech recognition. Neither noise estimation nor noise-model training are required in the proposed approach. A spectral subtraction integrated autocorrelation function is proposed to determine the pitch for the harmonic model. Recognition results show that the harmonic-based spectral reconstruction approach outperforms spectral subtraction in the middle- and low-signal noise ratio (SNR) ranges. The advantage of the proposed method is more manifest for non-stationary noise, as the algorithm does not require an assumption of stationary noise.
Spherical harmonics, invariant theory and Maxwell's poles
Dowker, J S
2008-01-01
I discuss the relation between harmonic polynomials and invariant theory and show that homogeneous, harmonic polynomials correspond to ternary forms that are apolar to a base conic (the absolute). The calculation of Schlesinger that replaces such a form by a polarised binary form is reviewed. It is suggested that Sylvester's theorem on the uniqueness of Maxwell's pole expression for harmonics is renamed the Clebsch-Sylvester theorem. The relation between certain constructs in invariant theory and angular momentum theory is enlarged upon and I resurrect the Joos--Weinberg matrices. Hilbert's projection operators are considered and their generalisations by Story and Elliott are related to similar, more recent constructions in group theory and quantum mechanics, the ternary case being equivalent to SU(3).
Quantum dynamics of the damped harmonic oscillator
Philbin, T G
2012-01-01
The quantum theory of the damped harmonic oscillator has been a subject of continual investigation since the 1930s. The obstacle to quantization created by the dissipation of energy is usually dealt with by including a discrete set of additional harmonic oscillators as a reservoir. But a discrete reservoir cannot directly yield dynamics such as Ohmic damping (proportional to velocity) of the oscillator of interest. By using a continuum of oscillators as a reservoir, we canonically quantize the harmonic oscillator with Ohmic damping and also with general damping behaviour. The dynamics of a damped oscillator is determined by an arbitrary effective susceptibility that obeys Kramers-Kronig relations. This approach offers an alternative description of nano-mechanical oscillators and opto-mechanical systems.
Theory of harmonic dissipation in disordered solids
Damart, T.; Tanguy, A.; Rodney, D.
2017-02-01
Mechanical spectroscopy, i.e., cyclic deformations at varying frequencies, is used theoretically and numerically to compute dissipation in model glasses. From a normal mode analysis, we show that in the high-frequency terahertz regime where dissipation is harmonic, the quality factor (or loss angle) can be expressed analytically. This expression is validated through nonequilibrium molecular dynamics simulations applied to a model of amorphous silica (SiO2). Dissipation is shown to arise from nonaffine relaxations triggered by the applied strain through the excitation of vibrational eigenmodes that act as damped harmonic oscillators. We discuss an asymmetry vector field, which encodes the information about the structural origin of dissipation computed by mechanical spectroscopy. In the particular case of silica, we find that the motion of oxygen atoms, which induce a deformation of the Si-O-Si bonds, is the main contributor to harmonic energy dissipation.
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...
RESEARCH ON THE INTERNATIONAL ACCOUNTING HARMONIZATION PROCESS
Directory of Open Access Journals (Sweden)
Tatiana Danescu
2016-12-01
Full Text Available During the last decades, the need of harmonization of the financial reporting frameworks has become more acute, mostly because the capital markets are not restricted anymore by country borders and capital movement has outlined the phenomenon of globalization and internationalism. A significant step in harmonizing the financial reporting was done in the process of normalization through different sets of rules and principles, recognized and applied in many states are the International Financial Reporting Standards (IFRS. The process of international recognition of these standards continues along with conceptual development which is based on epistemological research on specific markets, industries, economies open to international capital flows. In this context it becomes of interest to identify and understand generally accepted and applied accounting elements which carry forward the accounting harmonization process along with factors and circumstances that create diversity in nationally applied financial reporting frameworks.
Simulation of Second Harmonic Ultrasound Fields
DEFF Research Database (Denmark)
Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt
2010-01-01
A non-linear ultrasound imaging simulation software should be capable of simulating the non-linear fields for any kind of transducer, focusing, apodization, and attenuation. At present, a major issue is the overlong simulation time of the non-linear software. An Angular Spectrum Approach (ASA......) using a quasi-linear approximation for solving the Westervelt equation can simulate the second harmonic pressure at any distance. Therefore, it shortens the execution time compared with the operator splitting method. The purpose of this paper is to implement the monochromatic solution for the second......, 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...
Tian, Jun; Chen, Qiaofu; Zhang, Yuqi
2012-12-01
In this article, the PWM inverter works as a controlled fundamental current source in the single phase series hybrid active power filter (APF) based on fundamental magnetic flux compensation (FMFC). The series transformer can exhibit the self-impedance of primary winding to harmonic current, which forces harmonic current to flow into passive power filter. With the influence of harmonic current, the voltage of primary winding of transformer is a harmonic voltage, which makes the inverter output currents have a certain harmonic component, and it degrades the filtering characteristics. On the basis of PWM inverter, the mathematical model of series hybrid APF is established, and the filtering characteristics of single phase APF are analysed in detail. Three methods are gained to improve filtering characteristics: reasonably designing the inverter output filter inductance, increasing series transformer ratio and adopting voltage feed-forward control. Experimental results show that the proposed APF has greater validity.
Current drive with combined electron cyclotron wave and high harmonic fast wave in tokamak plasmas
Li, J. C.; Gong, X. Y.; Dong, J. Q.; Wang, J.; Zhang, N.; Zheng, P. W.; Yin, C. Y.
2016-12-01
The current driven by combined electron cyclotron wave (ECW) and high harmonic fast wave is investigated using the GENRAY/CQL3D package. It is shown that no significant synergetic current is found in a range of cases with a combined ECW and fast wave (FW). This result is consistent with a previous study [Harvey et al., in Proceedings of IAEA TCM on Fast Wave Current Drive in Reactor Scale Tokamaks (Synergy and Complimentarily with LHCD and ECRH), Arles, France, IAEA, Vienna, 1991]. However, a positive synergy effect does appear with the FW in the lower hybrid range of frequencies. This positive synergy effect can be explained using a picture of the electron distribution function induced by the ECW and a very high harmonic fast wave (helicon). The dependence of the synergy effect on the radial position of the power deposition, the wave power, the wave frequency, and the parallel refractive index is also analyzed, both numerically and physically.
Ueda, Keisuke; Matsuki, Yoh; Fujiwara, Toshimichi; Tatematsu, Yoshinori; Ogawa, Isamu; Idehara, Toshitaka
2016-09-01
A 394-GHz gyrotron, FU CW GII, has been designed at the University of Fukui, Japan, for dynamic nuclear polarization (DNP)-enhanced solid-state nuclear magnetic resonance (SSNMR) experiments at 600-MHz 1H resonant frequency. After installation at the Institute for Protein Research (IPR), Osaka University, Japan, a PID feedback control system was equipped to regulate the electron gun heater current for stabilization of the electron beam current, which ultimately achieved stabilization of output power when operating in continuous wave (CW) mode. During exploration to further optimize operating conditions, a continuous tuning bandwidth of approximately 1 GHz was observed by varying the operating voltage at a fixed magnetic field. In the frequency range required for positive DNP enhancement, the output power was improved by increasing the magnetic field and the operating voltage from their initial operational settings. In addition, fine tuning of output frequency by varying the cavity cooling water temperature was demonstrated. These operating conditions and ancillary enhancements are expected to contribute to further enhancement of SSNMR signal.
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
Harmonic Cavity Performance for NSLS-II
Blednykh, Alexei; Podobedov, Boris; Rose, James; Towne, Nathan A; Wang, Jiunn-Ming
2005-01-01
NSLS-II is a 3 GeV ultra-high brightness storage ring that is planned to succeed the present NSLS rings at Brookhaven. Ultra-low emittance bunch combined with a short bunch length results in the Touschek lifetime of only a few hours, which strongly advocates including harmonic RF in the baseline design of NSLS-II. This paper describes the required harmonic RF parameters, trade-offs between the possible choices and the expected system performance, including the implications on lifetime and instabilities.
Perturbative Semiclassical Trace Formulae for Harmonic Oscillators
DEFF Research Database (Denmark)
Møller-Andersen, Jakob; Ögren, Magnus
2015-01-01
In this article we extend previous semiclassical studies by including more general perturbative potentials of the harmonic oscillator in arbitrary spatial dimensions. Our starting point is a radial harmonic potential with an arbitrary even monomial perturbation, which we use to study the resulting...... U(D) to O(D) symmetry breaking. We derive the gross structure of the semiclassical spectrum from periodic orbit theory, in the form of a perturbative (ħ → 0) trace formula. We then show how to apply the results to even-order polynomial potentials, possibly including mean-field terms. We have drawn...
Geometric Models of the Relativistic Harmonic Oscillator
Cotaescu, I I
1997-01-01
A family of relativistic geometric models is defined as a generalization of the actual anti-de Sitter (1+1) model of the relativistic harmonic oscillator. It is shown that all these models lead to the usual harmonic oscillator in the non-relativistic limit, even though their relativistic behavior is quite different. Among quantum models we find a set of models with countable energy spectra, and another one having only a finite number of energy levels and in addition a continuous spectrum.
Harmonic Inverse FEL Interaction at 800nm
Sears, C M S; Siemann, R; Spencer, J E
2005-01-01
The inverse Free Electron Laser (IFEL) interaction has recently been proposed and demonstrated as a premodulator for High Gain Harmonic Generation (HGHG) experiments. These experiments utilized the fundamental of the interaction between the laser field and electron bunch. In the current experiment, we explore the higher order resonances of the IFEL interaction from a 3 period, 1.8 centimeter wavelength undulator with a picosecond, 0.25 mJ/pulse laser at 800nm. The resonances are observed by adjusting the gap of the undulator while keeping the beam energy constant. The harmonic IFEL can add flexibility to HGHG FEL design.
Reconstruction of harmonic signals based on bispectrum
Institute of Scientific and Technical Information of China (English)
FAN Yangyu; SUN Jincai; LI Pingan; XU Jiadong; SHANG Jiuhao
2000-01-01
A method for accurate reconstruction of the harmonic signals from bispectrum is presented. Based on the analysis of the measured harmonic signal, a sinusoid signal with 0phase, 1-amplitude and half of the fundamental frequency combines with the measured signal to form a combined signal, and then the bispectrum analysis is carried out to reconstruct the phase and the amplitude of the measured signal accurately. Without the zero-phase assumption of the fundamental component, using the new method eliminates the phase shifting between the calculated Fourier phase and the true Fourier phase in the existing signal retrieval methods based on bispectrum. The simulation results show the effectiveness of the new method.
Fast algorithms for spherical harmonic expansions, III
Tygert, Mark
2009-01-01
We accelerate the computation of spherical harmonic transforms, using what is known as the butterfly scheme. This provides a convenient alternative to the approach taken in the second paper from this series on "Fast algorithms for spherical harmonic expansions." The requisite precomputations become manageable when organized as a "depth-first traversal" of the program's control-flow graph, rather than as the perhaps more natural "breadth-first traversal" that processes one-by-one each level of the multilevel procedure. We illustrate the results via several numerical examples.
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'
Artificial Neural Network in Harmonic Reduction of STATCOM
Institute of Scientific and Technical Information of China (English)
Li Hongmei; Li Zhenran; Zheng Peiying
2005-01-01
To eliminate harmonic pollution incurred from the static synchronous compensator(STATCOM), a method of applying artificial neural network is presented. When PWM wave is formed based on the harmonic suppression theory, a concave is set on certain angle of the square wave to suppress unnecessary harmonics, by timely and on-line determining the chopping angle corresponding to respective harmonics through artificial neural network, i.e. by setting the position of concave to eliminate corresponding harmonics, the harmonic component on output voltage of the inverter can be improved. To conclude through computer simulation test, the perfect control effect has been proved.
Metzger, Bernd; Hentschel, Mario; Schumacher, Thorsten; Lippitz, Markus; Ye, Xingchen; Murray, Christopher B; Knabe, Bastian; Buse, Karsten; Giessen, Harald
2014-05-14
We incorporate dielectric indium tin oxide nanocrystals into the hot-spot of gold nanogap-antennas and perform third harmonic spectroscopy on these hybrid nanostructure arrays. The combined system shows a 2-fold increase of the radiated third harmonic intensity when compared to bare gold antennas. In order to identify the origin of the enhanced nonlinear response we perform finite element simulations of the nanostructures, which are in excellent agreement with our measurements. We find that the third harmonic signal enhancement is mainly related to changes in the linear optical properties of the plasmonic antenna resonances when the ITO nanocrystals are incorporated. Furthermore, the dominant source of the third harmonic is found to be located in the gold volume of the plasmonic antennas.
Perfusion harmonic imaging of the human brain
Metzler, Volker H.; Seidel, Guenter; Wiesmann, Martin; Meyer, Karsten; Aach, Til
2003-05-01
The fast visualisation of cerebral microcirculation supports diagnosis of acute cerebrovascular diseases. However, the commonly used CT/MRI-based methods are time consuming and, moreover, costly. Therefore we propose an alternative approach to brain perfusion imaging by means of ultrasonography. In spite of the low signal/noise-ratio of transcranial ultrasound and the high impedance of the skull, flow images of cerebral blood flow can be derived by capturing the kinetics of appropriate contrast agents by harmonic ultrasound image sequences. In this paper we propose three different methods for human brain perfusion imaging, each of which yielding flow images indicating the status of the patient's cerebral microcirculation by visualising local flow parameters. Bolus harmonic imaging (BHI) displays the flow kinetics of bolus injections, while replenishment (RHI) and diminution harmonic imaging (DHI) compute flow characteristics from contrast agent continuous infusions. RHI measures the contrast agents kinetics in the influx phase and DHI displays the diminution kinetics of the contrast agent acquired from the decay phase. In clinical studies, BHI- and RHI-parameter images were found to represent comprehensive and reproducible distributions of physiological cerebral blood flow. For DHI it is shown, that bubble destruction and hence perfusion phenomena principally can be displayed. Generally, perfusion harmonic imaging enables reliable and fast bedside imaging of human brain perfusion. Due to its cost efficiency it complements cerebrovascular diagnostics by established CT/MRI-based methods.
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 ...
determination of determination of total harmonic distortion
African Journals Online (AJOL)
eobe
Harmonic Distortion (THD) of the Distribution lines in the 33kV distri .... guidelines based on industrial distribution system design. IEEE 519-1992 defines ..... studies and also reviewed issues related to the concept. The results of power flow and ...
Sobolev Spaces Associated to the Harmonic Oscillator
Indian Academy of Sciences (India)
B Bongioanni; J L Torrea
2006-08-01
We define the Hermite-Sobolev spaces naturally associated to the harmonic oscillator $H= - + |x|^2$. Structural properties, relations with the classical Sobolev spaces, boundedness of operators and almost everywhere convergence of solutions of the Schrödinger equation are also considered.
Spatial mode discrimination using second harmonic generation
DEFF Research Database (Denmark)
Delaubert, Vincent; Lassen, Mikael Østergaard; Pulford, David
2007-01-01
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 conv...
The Berry Phase for Simple Harmonic Oscillators
Suslov, Sergei K
2011-01-01
We evaluate the Berry phase for a "missing" family of the square integrable wavefunctions for the linear harmonic oscillator, which cannot be derived by the separation of variables. It is obtained by the action of the maximal kinematical invariance group on the standard solutions. An explicit simple formula for the phase is found by integration with the help of a computer algebra system.
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
Harmonic generation with multiple wiggler schemes
Energy Technology Data Exchange (ETDEWEB)
Bonifacio, R.; De Salvo, L.; Pierini, P. [Universita degli Studi, Milano (Italy)
1995-02-01
In this paper the authors give a simple theoretical description of the basic physics of the single pass high gain free electron laser (FEL), describing in some detail the FEL bunching properties and the harmonic generation technique with a multiple-wiggler scheme or a high gain optical klystron configuration.
Regularity of harmonic maps with the potential
Institute of Scientific and Technical Information of China (English)
CHU; Yuming
2006-01-01
The aim of this work is to prove the partial regularity of the harmonic maps with potential. The main difficulty caused by the potential is how to find the equation satisfied by the scaling function. Under the assumption on the potential we can obtain the equation, however, for a general potential, even if it is smooth, the partial regularity is still open.
Parameter estimation of harmonic polluting industrial loads
Energy Technology Data Exchange (ETDEWEB)
Maza-Ortega, J.M.; Gomez-Exposito, A.; Trigo-Garcia, J.L.; Burgos-Payan, M. [University of Sevilla, Sevilla (Spain). Department of Electrical Engineering
2005-12-01
This paper develops a methodology for the estimation of relevant parameters characterizing harmonic polluting industrial loads through a set of measurements acquired at the point of common coupling. The proposed method is capable of obtaining an accurate load model in absence of detailed information about its internal structure and composition. (author)
Transducer for harmonic intravascular ultrasound imaging
Vos, Hendrik J.; Frijlink, Martijn E.; Droog, E.J.; Goertz, David E.; Blacquiere, Gerrit; Gisolf, Anton; de Jong, N.; van der Steen, Antonius F.W.
2005-01-01
A recent study has shown the feasibility of tissue harmonic imaging (THI) using an intravascular ultrasound (IVUS) transducer. This correspondence describes the design, fabrication, and characterization of a THI-optimized piezoelectric transducer with oval aperture of 0.75 mm by 1 mm. The transducer
Feasibility of 3D harmonic contrast imaging
Voormolen, M.M.; Bouakaz, A.; Krenning, B.J.; Lancée, C.; ten Cate, F.; de Jong, N.
2004-01-01
Improved endocardial border delineation with the application of contrast agents should allow for less complex and faster tracing algorithms for left ventricular volume analysis. We developed a fast rotating phased array transducer for 3D imaging of the heart with harmonic capabilities making it
Toeplitz operators on harmonic Bergman spaces
Choe, Boo Rim; Lee, Young Joo; Na, Kyunguk
2004-01-01
We study Toeplitz operators on the harmonic Bergman spaces on bounded smooth domains. Two classes of symbols are considered; one is the class of positive symbols and the other is the class of uniformly continuous symbols. For positive symbols, boundedness, compactness, and membership in the Schatten classes are characterized. For uniformly continuous symbols, the essential spectra are described.
Local Dynamics in an Infinite Harmonic Chain
Directory of Open Access Journals (Sweden)
M. Howard Lee
2016-04-01
Full Text Available By the method of recurrence relations, the time evolution in a local variable in a harmonic chain is obtained. In particular, the autocorrelation function is obtained analytically. Using this result, a number of important dynamical quantities are obtained, including the memory function of the generalized Langevin equation. Also studied are the ergodicity and chaos in a local dynamical variable.
The Harmonic Oscillator–A Simplified Approach
Directory of Open Access Journals (Sweden)
L. R. Ganesan
2008-01-01
Full Text Available Among the early problems in quantum chemistry, the one dimensional harmonic oscillator problem is an important one, providing a valuable exercise in the study of quantum mechanical methods. There are several approaches to this problem, the time honoured infinite series method, the ladder operator method etc. A method which is much shorter, mathematically simpler is presented here.
Coherent control of High-harmonic generation
Barreaux, J.L.P.
2012-01-01
High-harmonic generation (HHG) is a non-linear optical process that can convert laser light with standard wavelengths, such as infrared light, into coherent radiation at much shorter wavelengths in the XUV (extreme ultraviolet) or soft X-ray regime. As opposed to low-order nonlinear frequency
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.
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.
Large- quantum chromodynamics and harmonic sums
Indian Academy of Sciences (India)
Eduardo De Rafael
2012-06-01
In the large- limit of QCD, two-point functions of local operators become harmonic sums. I review some properties which follow from this fact and which are relevant for phenomenological applications. This has led us to consider a class of analytic number theory functions as toy models of large- QCD which also is discussed.
Harmonic cascade FEL designs for LUX
Energy Technology Data Exchange (ETDEWEB)
Penn, G.; Reinsch, M.; Wurtele, J.; Corlett, J.N.; Fawley, W.M.; Zholents, A.; Wan, W.
2004-07-16
LUX is a design concept for an ultrafast X-ray science facility, based on an electron beam accelerated to GeV energies in are circulating linac. Included in the design are short duration (200 fs or shorter FWHM) light sources using multiple stages of higher harmonic generation, seeded by a 200-250 nm laser of similar duration. This laser modulates the energy of a group of electrons within the electron bunch; this section of the electron bunch then produces radiation at a higher harmonic after entering a second, differently tuned undulator. Repeated stages in a cascade yield increasing photon energies up to 1 keV. Most of the undulators in the cascade operate in the low-gain FEL regime. Harmonic cascades have been designed for each pass of the recirculating linac up to a final electron beam energy of 3.1 GeV. For a given cascade, the photon energy can be selected over a wide range by varying the seed laser frequency and the field strength in the undulators. We present simulation results using the codes GENESIS and GINGER, as well as the results of analytical models which predict FEL performance. We discuss lattice considerations pertinent for harmonic cascade FELs, as well as sensitivity studies and requirements on the electron beam.
Spatial mode discrimination using second harmonic generation
DEFF Research Database (Denmark)
Delaubert, Vincent; Lassen, Mikael Østergaard; Pulford, David
2007-01-01
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 conv...
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...
FPGA Techniques Based New Hybrid Modulation Strategies for Voltage Source Inverters
Sudha, L. U.; J. Baskaran; Elankurisil, S. A.
2015-01-01
This paper corroborates three different hybrid modulation strategies suitable for single-phase voltage source inverter. The proposed method is formulated using fundamental switching and carrier based pulse width modulation methods. The main tale of this proposed method is to optimize a specific performance criterion, such as minimization of the total harmonic distortion (THD), lower order harmonics, switching losses, and heat losses. The proposed method is articulated using fundamental switch...
The harmonics detection method based on neural network applied ...
African Journals Online (AJOL)
user
Keywords: Artificial Neural Networks (ANN), p-q theory, (SAPF), Harmonics, Total Harmonic Distortion. 1. ... Recently, some methods based on artificial intelligence have been applied In order to improve ..... The effect is the reduction of.
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
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...... turbine. The degree and type of dependence between the harmonic emission and the operating point of a single turbine is established. A model of Burbo Banks, suitable for harmonic load flow studies, is created in DIgSILENT Power Factory along with a DPL-script that deals with the probabilistic issues...... 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...
Estimates on Bloch constants for planar harmonic mappings
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
The Bloch constants for quasiregular harmonic mappings and open planar harmonic mappings are considered. Better estimates are obtained. The results, presented in this paper, improve the one made by Chen et al. and Grigoryan.
Harmonic Damping in DG-Penetrated Distribution Network
DEFF Research Database (Denmark)
Lu, Jinghang; Savaghebi, Mehdi; Guerrero, Josep M.
2016-01-01
Grid background harmonics may be amplified, propagate through a long distribution feeder and even lead to power system instability. In this paper, harmonic propagation issue is investigated and mitigation of the harmonics is analyzed by using transmission line theory which has already been applied...... in power systems. It is demonstrated that a specific harmonic will not be amplified if the feeder’s length is less than one quarter of the harmonic wavelength meanwhile the terminal impedance is less than characteristic impedance. Besides, three scenarios will be considered in accordance...... with the relationship between the feeder’s length and harmonic wavelength. Harmonic suppression control strategies will be respectively designed considering 5th and 7th harmonics coexisting in the distribution line. Finally, a simulation study has been performed to verify the theoretical analysis and demonstrate...
harmonics mitigation on industrial loads using series and parallel ...
African Journals Online (AJOL)
user
This work compared the use of series and parallel resonant harmonic filters in suppressing harmonics ... industrial applications high technology devices related to communication .... magnification is large because of high circuit Q-factor or.
Product of Toeplitz Operators on the Harmonic Dirichlet Space
Institute of Scientific and Technical Information of China (English)
Lian Kuo ZHAO
2012-01-01
In this paper,we study Toeplitz operators with harmonic symbols on the harmonic Dirichlet space,and show that the product of two Toeplitz operators is another Toeplitz operator only if one factor is constant.
Strongly Dispersive Transient Bragg Grating for High Harmonics
Energy Technology Data Exchange (ETDEWEB)
Farrell, J.; Spector, L.S.; /SLAC, PULSE /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.; Gaarde, M.B.; /SLAC, PULSE /Louisiana State U.; McFarland, B.K.; Bucksbaum, P.H.; Guhr, Markus; /SLAC, PULSE /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.
2010-06-04
We create a transient Bragg grating in a high harmonic generation medium using two counterpropagating pulses. The Bragg grating disperses the harmonics in angle and can diffract a large bandwidth with temporal resolution limited only by the source size.
A multi-band shunt hybrid active ﬁlter with reduced sensor count
Indian Academy of Sciences (India)
S Surendra Kumar; Partha Sarathi Sensarma
2008-10-01
A Shunt Hybrid Active Filter (SHAF) is an attractive option for realizing low-cost harmonic compensation solutions. This paper proposes a SHAF with multiple harmonic compensation capability using a single Voltage Source Inverter and reduced sensor count. This strategy is apt for harmonic ﬁltering solutions where low cost is the exclusive priority. In this paper, a new estimation approach is proposed to obviate requirement of a large number of sensors. Multiple Synchronous Reference Frames (MSRF) and low pass ﬁlters are used to measure 5th and 7th harmonic components separately from load as well as ﬁlter currents. Individual current controllers are designed for the 5th and 7th harmonic currents. Control is realized in the synchronously rotating, orthogonal (dq) reference frame. Performance of the controller is validated through simulation, using realistic plant and controller models. Experimental results are provided to corroborate the analytical and simulation results.
Deterministic and Stochastic Study of Wind Farm Harmonic Currents
DEFF Research Database (Denmark)
Sainz, Luis; Mesas, Juan Jose; Teodorescu, Remus;
2010-01-01
Wind farm harmonic emissions are a well-known power quality problem, but little data based on actual wind farm measurements are available in literature. In this paper, harmonic emissions of an 18 MW wind farm are investigated using extensive measurements, and the deterministic and stochastic...... characterization of wind farm harmonic currents is analyzed. Specific issues addressed in the paper include the harmonic variation with the wind farm operating point and the random characteristics of their magnitude and phase angle....
RHIC susceptibility to variations in systematic magnetic harmonic errors
Energy Technology Data Exchange (ETDEWEB)
Dell, G.F.; Peggs, S.; Pilat, F.; Satogata, T.; Tepikian, S.; Trbojevic, D.; Wei, J.
1994-08-01
Results of a study to determine the sensitivity of tune to uncertainties of the systematic magnetic harmonic errors in the 8 cm dipoles of RHIC are reported. Tolerances specified to the manufacturer for tooling and fabrication can result in systematic harmonics different from the expected values. Limits on the range of systematic harmonics have been established from magnet calculations, and the impact on tune from such harmonics has been established.
The current issues of internal control and internal audit harmonization
Синюгіна, Наталія Вікторівна
2013-01-01
The relevance of topics related to a harmonization of internal control and internal audit system of internal financial control is being proved. It is high lightened the essence of harmonization period by reviewing existing thoughts on this object, a concept of 'harmonization of internal control and internal audit", and provided reasonably practical recommendations to ensure such harmonization in the modern world. The scientific impact of this research is to clarify the concept of "harmonizati...
Lipschitz spaces and bounded mean oscillation of harmonic mappings
Chen, Sh; Vuorinen, M; Wang, X
2012-01-01
In this paper, we first study the bounded mean oscillation of planar harmonic mappings, then a relationship between Lipschitz-type spaces and equivalent modulus of real harmonic mappings is established. At last, we obtain sharp estimates on Lipschitz number of planar harmonic mappings in terms of bounded mean oscillation norm, which shows that the harmonic Bloch space is isomorphic to $BMO_{2}$ as a Banach space.
Second-Harmonic Generation of Bessel Beams in Lossy Media
Institute of Scientific and Technical Information of China (English)
丁德胜; 许坚毅; 王耀俊
2002-01-01
We present a further analysis for the second-harmonic generation of Bessel beams in lossy media. The emphasis is put on the effect of absorption to the radial pattern of the second-harmonic beam. It is shown that within the absorption length of the second harmonic, the Bessel second-harmonic beam approaches limited diffraction in the radial direction and behaves as in the case of lossless media.
A Designated Harmonic Suppression Technology for Sampled SPWM
Institute of Scientific and Technical Information of China (English)
YANG Ping
2005-01-01
Sampled SPWM is an excellent VVVF method of motor speed control, meanwhile the harmonic components of the output wave impairs its applications in practice. A designated harmonic suppression technology is presented for sampled SPWM, which is an improved algorithm for the harmonic suppression in high voltage and high frequency spectrum. As the technology is applied in whole speed adjusting range, the voltage can be conveniently controlled and high frequency harmonic of SP WM is also improved.
Eliasson, B.; Speirs, D. C.; Daldorff, L. K. S.
2016-09-01
A theoretical study is presented of the electrostatic electron cyclotron instability involving Bernstein modes in a magnetized plasma. The presence of a tenuous thermal ring distribution in a Maxwellian plasma decreases the frequency of the upper hybrid branch of the electron Bernstein mode until it merges with the nearest lower branch with a resulting instability. The instability occurs when the upper hybrid frequency is somewhat above the third, fourth, and higher electron cyclotron harmonics, and gives rise to a narrow spectrum of waves around the electron cyclotron harmonic nearest to the upper hybrid frequency. For a tenuous cold ring distribution together with a Maxwellian distribution an instability can take place also near the second electron cyclotron harmonic. Noise-free Vlasov simulations are used to assess the theoretical linear growth-rates and frequency spectra, and to study the nonlinear evolution of the instability. The relevance of the results to laboratory and ionospheric heating experiments is discussed.
A Look at Damped Harmonic Oscillators through the Phase Plane
Daneshbod, Yousef; Latulippe, Joe
2011-01-01
Damped harmonic oscillations appear naturally in many applications involving mechanical and electrical systems as well as in biological systems. Most students are introduced to harmonic motion in an elementary ordinary differential equation (ODE) course. Solutions to ODEs that describe simple harmonic motion are usually found by investigating the…
Harmonic Mitigation Methods in Large Offshore Wind Power Plants
DEFF Research Database (Denmark)
Kocewiak, Łukasz Hubert; Chaudhary, Sanjay; Hesselbæk, Bo
2013-01-01
Various sources of harmonic problems in large wind power plants (WPPs) and optimized harmonic mitigation methods are presented in this paper. The harmonic problems such as sources of harmonic emission and amplification as well as harmonic stability are identified. Also modern preventive and remed......Various sources of harmonic problems in large wind power plants (WPPs) and optimized harmonic mitigation methods are presented in this paper. The harmonic problems such as sources of harmonic emission and amplification as well as harmonic stability are identified. Also modern preventive...... and remedial harmonic mitigation methods in terms of passive and active filtering are described. It is shown that WPP components such as long HVAC cables and park transformers can introduce significant low-frequency resonances which can affect wind turbine control system operation and overall WPP stability...... as well as amplification of harmonic distortion. It is underlined that there is a potential in terms of active filtering in modern grid-side converters in e.g. wind turbines, STATCOMs or HVDC stations utilized in modern large WPPs. It is also emphasized that the grid-side converter controller should...
Harmonic calculation software for industrial applications with ASDs
DEFF Research Database (Denmark)
Blaabjerg, Frede; Asiminoaei, Lucian; Hansen, Steffan
2007-01-01
This article describes the evaluation of new harmonic calculation software. By using a combination of a prestored database and new interpolation techniques the software can provide the harmonic data on real applications of a very fast speed. The harmonic results obtained with this software have a...
The harmonic force field and absolute infrared intensities of diacetylene
Koops, Th.; Visser, T.; Smit, W.M.A.
1984-01-01
The frequencies, harmonic force field and absolute IR intensities for C4H2 and C4D2 are reported. The experimental harmonized frequencies obey the Teller—Redlich product rule very well. An approximate harmonic force field was obtained from a refinement procedure in which the starting values are adj
Twenty-Four Tuba Harmonics Using a Single Pipe Length
Holmes, Bud; Ruiz, Michael J.
2017-01-01
Harmonics arise naturally from the resonances in strings and pipes. A video demonstration (Ruiz 2016 "YouTube: Tuba Harmonics" (https://youtu.be/souhEzOP9c4)) is provided where a tubist (coauthor Holmes) produces a phenomenal 24 harmonics using a single tuba pipe length by controlling the buzz of his lips. The frequencies of the…
Harmonic Calculation Software for Industrial Applications with Adjustable Speed Drives
DEFF Research Database (Denmark)
Asiminoaei, Lucian; Hansen, S.; Blaabjerg, Frede
2005-01-01
This paper describes the evaluation of a new harmonic software. By using a combination of a pre-stored database and new interpolation techniques the software can very fast provide the harmonic data on real applications. The harmonic results obtained with this software have acceptable precision even...
Double-Undulator Fel for Governing by the Harmonics Generation
Tulupov, A. V.
1993-01-01
Generation of harmonics in the double-undulator FEL based on the additional cyclotron resonance is considered. It is shown that efficient control of harmonics generation is feasible. Only one selected harmonic is generated while the others are suppressed. This effect takes place under a small value
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe
2012-01-01
This paper proposes a harmonic impedance synthesis technique for voltage-controlled distributed generation inverters in order to damp harmonic voltage distortion on a distribution network. The approach employs a multiloop control scheme, where a selective harmonic load current feedforward loop ba...
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe
2012-01-01
This paper proposes a harmonic impedance synthesis technique for voltage-controlled distributed generation inverter in order to damp harmonic voltage distortion on a distribution network. The approach employs a multiloop control scheme, where a selective load harmonic current feedforward loop bas...
Exploring chemical reaction mechanisms through harmonic Fourier beads path optimization.
Khavrutskii, Ilja V; Smith, Jason B; Wallqvist, Anders
2013-10-28
Here, we apply the harmonic Fourier beads (HFB) path optimization method to study chemical reactions involving covalent bond breaking and forming on quantum mechanical (QM) and hybrid QM∕molecular mechanical (QM∕MM) potential energy surfaces. To improve efficiency of the path optimization on such computationally demanding potentials, we combined HFB with conjugate gradient (CG) optimization. The combined CG-HFB method was used to study two biologically relevant reactions, namely, L- to D-alanine amino acid inversion and alcohol acylation by amides. The optimized paths revealed several unexpected reaction steps in the gas phase. For example, on the B3LYP∕6-31G(d,p) potential, we found that alanine inversion proceeded via previously unknown intermediates, 2-iminopropane-1,1-diol and 3-amino-3-methyloxiran-2-ol. The CG-HFB method accurately located transition states, aiding in the interpretation of complex reaction mechanisms. Thus, on the B3LYP∕6-31G(d,p) potential, the gas phase activation barriers for the inversion and acylation reactions were 50.5 and 39.9 kcal∕mol, respectively. These barriers determine the spontaneous loss of amino acid chirality and cleavage of peptide bonds in proteins. We conclude that the combined CG-HFB method further advances QM and QM∕MM studies of reaction mechanisms.
Hybrid microelectronic technology
Moran, P.
Various areas of hybrid microelectronic technology are discussed. The topics addressed include: basic thick film processing, thick film pastes and substrates, add-on components and attachment methods, thin film processing, and design of thick film hybrid circuits. Also considered are: packaging hybrid circuits, automating the production of hybrid circuits, application of hybrid techniques, customer's view of hybrid technology, and quality control and assurance in hybrid circuit production.
Addition theorems for spin spherical harmonics: II. Results
Energy Technology Data Exchange (ETDEWEB)
Bouzas, Antonio O, E-mail: abouzas@mda.cinvestav.mx [Departamento de Fisica Aplicada, CINVESTAV-IPN, Carretera Antigua a Progreso Km. 6, Apdo. Postal 73 ' Cordemex' , Merida 97310, Yucatan (Mexico)
2011-04-22
Based on the results of part I (2011 J. Phys. A: Math. Theor. 44 165301), we obtain the general form of the addition theorem for spin spherical harmonics and give explicit results in the cases involving one spin-s' and one spin-s spherical harmonics with s', s = 1/2, 1, 3/2, and |s' - s| = 0, 1. We also obtain a fully general addition theorem for one scalar and one tensor spherical harmonic of arbitrary rank. A variety of bilocal sums of ordinary and spin spherical harmonics are given in explicit form, including a general explicit expression for bilocal spherical harmonics.
Twenty-four tuba harmonics using a single pipe length
Holmes, Bud; Ruiz, Michael J.
2017-03-01
Harmonics arise naturally from the resonances in strings and pipes. A video demonstration (Ruiz 2016 YouTube: Tuba Harmonics (https://youtu.be/souhEzOP9c4)) is provided where a tubist (coauthor Holmes) produces a phenomenal 24 harmonics using a single tuba pipe length by controlling the buzz of his lips. The frequencies of the harmonics, measured with the free software program Audacity, fall excellently on a linear fit using a spreadsheet. The skillful musical production of so many harmonics with a fixed pipe length is an extraordinary illustration of physics.
Harmonics in large offshore wind farms
DEFF Research Database (Denmark)
Kocewiak, Lukasz Hubert
harmonic origin and observe short-term variation. Non-parametric spectrum estimation is successfully applied to interpolated signals adjusted according to the varying power system frequency. Different data processing techniques are presented and applied depending on the signal (i.e. stationary or non...... suitable data processing methods. Before any of the above aspects could be seriously taken into consideration, a reliable and robust measurement system is needed. This is achieved by carefully designing the hardware and the software layers of the measurement system. It is explained in the report...... that it is of great importance to know the nature of generated harmonics in large offshore wind farms in order to apply the most suitable data processing technique. Time-frequency analysis based on multiresolution wavelet transform is used in order to perform time-frequency domain analysis helpful to distinguish...
Super/subradiant second harmonic generation
Koganov, Gennady A.; Shuker, Reuben
2017-04-01
A scheme for active second harmonics generation is suggested. The system comprises N three-level atoms in ladder configuration, situated into a resonant cavity. The system generates the field whose frequency is twice the frequency of the pumping laser, and the field phase is locked to the phase of the pumping field. It is found that the system can lase in either superradiant or subradiant regime, depending on the number of atoms N. When N passes some critical value the transition from the super to subradiance occurs in a phase-transition-like manner. Stability study of the steady state supports this conclusion. For experimental realization of the super/subradiant second harmonics generation we propose semiconductor quantum well structures, superconducting quantum circuits, and evanescently coupled waveguides in which equally spaced levels relevant to this study exist.
Coulomb time delays in high harmonic generation
Smirnova, Olga
2016-01-01
Measuring the time it takes to remove an electron from an atom or molecule during photoionization using newly developed attosecond spectroscopies has been a focus of many recent experiments. However, the outcome of such measurement depends on measurement protocols and specific observables available in each particular experiment. One of such protocols relies on high harmonic generation. First, we derive rigorous and general expressions for ionization and recombination times in high harmonic generation experiments. We show that these times are different from, but related to ionization times measured in photo-electron spectroscopy, i.e. using attosecond streak camera, RABBITT and atto-clock methods. Second, we use the Analytical R-Matrix theory (ARM) to calculate these times and compare them with experimental values.
A remark on infinity harmonic functions
Directory of Open Access Journals (Sweden)
Michael G. Crandall
2001-01-01
Full Text Available A real-valued function $u$ is said to be {it infinity harmonic} if it solves the nonlinear degenerate elliptic equation $-sum_{i,j=1}^nu_{x_1}u_{x_j}u_{x_ix_j}=0$ in the viscosity sense. This is equivalent to the requirement that $u$ enjoys comparison with cones, an elementary notion explained below. Perhaps the primary open problem concerning infinity harmonic functions is to determine whether or not they are continuously differentiable. Results in this note reduce the problem of whether or not a function $u$ which enjoys comparison with cones has a derivative at a point $x_0$ in its domain to determining whether or not maximum points of $u$ relative to spheres centered at $x_0$ have a limiting direction as the radius shrinks to zero.
Harmonic oscillator model for the helium atom
Carlsen, Martin
2015-01-01
A harmonic oscillator model in four dimensions is presented for the helium atom to estimate the distance to the inner and outer electron from the nucleus, the angle between electrons and the energy levels. The method is algebraic and is not based on the choice of correct trial wave function. Three harmonic oscillators and thus three quantum numbers are sufficient to describe the two-electron system. We derive a simple formula for the energy in the general case and in the special case of the Wannier Ridge. For a set of quantum numbers the distance to the electrons and the angle between the electrons are uniquely determined as the intersection between three surfaces. We show that the excited states converge either towards ionization thresholds or towards extreme parallel or antiparallel states and provide an estimate of the ground state energy.
Coulomb time delays in high harmonic generation
Torlina, Lisa; Smirnova, Olga
2017-02-01
Measuring the time it takes to remove an electron from an atom or molecule during photoionization has been the focus of a number of recent experiments using newly developed attosecond spectroscopies. The interpretation of such measurements, however, depends critically on the measurement protocol and the specific observables available in each experiment. One such protocol relies on high harmonic generation. In this paper, we derive rigorous and general expressions for ionisation and recombination times in high harmonic generation experiments. We show that these times are different from, but related to, ionisation times measured in photoelectron spectroscopy: that is, those obtained using the attosecond streak camera, RABBITT and attoclock methods. We then proceed to use the analytical R-matrix theory to calculate these times and compare them with experimental values.
Harmonic beam splitter design and fabrication
Institute of Scientific and Technical Information of China (English)
Xiaofeng Ma(马小凤); Yingjian Wang(王英剑); Zhengxiu Fan(范正修); Jianda Shao(邵建达)
2004-01-01
Two problems of half-wave hole and high ripples in the transmittance region for a harmonic beam splitter had been pointed out and analyzed. Based on the application of a half-wavelength control and a new admittance matching methods, a harmonic beam splitter was designed and fabricated. The former method eliminated the half-wave hole fundamentally, and the latter smoothed high ripples in the transmittance region effectively. The matching stack consisted of a symmetrically periodic structure and provided a complete matching at the desired wavelength, i.e., both conditions for the equivalent admittance and phase thickness were fulfilled. Furthermore, both the theoretical and the tested curves had been given, and a good agreement between them was obtained.
Harmonic dynamical behaviour of thallous halides
Indian Academy of Sciences (India)
Sarvesh K Tiwari; L J Shukla; K S Upadhyaya
2010-05-01
Harmonic dynamical behaviour of thallous halides (TlCl and TlBr) have been studied using the new van der Waals three-body force shell model (VTSM), which incorporates the effects of the van der Waals interaction along with long-range Coulomb interactions, three-body interactions and short-range second neighbour interactions in the framework of rigid shell model (RSM). Phonon dispersion curves (PDC), variations of Debye temperature with absolute temperature and phonon density of state (PDS) curves have been reported for thallous halides using VTSM. Comparison of experimental values with those of VTSM and TSM are also reported in the paper and a good agreement between experimental and VTSM values has been found, from which it may be inferred that the incorporation of van der Waals interactions is essential for the complete harmonic dynamical behaviour of thallous halides.
Quantum Harmonic Oscillator Algebra and Link Invariants
Gómez, C
1991-01-01
The $q$--deformation $U_q (h_4)$ of the harmonic oscillator algebra is defined and proved to be a Ribbon Hopf algebra.Associated with this Hopf algebra we define an infinite dimensional braid group representation on the Hilbert space of the harmonic oscillator, and an extended Yang--Baxter system in the sense of Turaev. The corresponding link invariant is computed in some particular cases and coincides with the inverse of the Alexander--Conway polynomial. The $R$ matrix of $U_q (h_4)$ can be interpreted as defining a baxterization of the intertwiners for semicyclic representations of $SU(2)_q$ at $q=e^{2 \\pi i/N}$ in the $N \\rightarrow \\infty$ limit.Finally we define new multicolored braid group representations and study their relation to the multivariable Alexander--Conway polynomial.
Effects of harmonic roving on pitch discrimination
DEFF Research Database (Denmark)
Santurette, Sébastien; de Kérangal, Mathilde le Gal; Joshi, Suyash Narendra
2015-01-01
Performance in pitch discrimination tasks is limited by variability intrinsic to listeners which may arise from peripheral auditory coding limitations or more central noise sources. Perceptual limitations may be characterized by measuring an observer’s change in performance when introducting...... 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...... a matter of debate whether pitch perception of natural complex sounds mostly relies on either spectral excitation-based information or temporal periodicity information. Comparing the way internal noise affects the internal representations of such information to how it affects pitch discrimination...
Harmonics in a Wind Power Plant: Preprint
Energy Technology Data Exchange (ETDEWEB)
Preciado, V.; Madrigal, M.; Muljadi, E.; Gevorgian, V.
2015-04-02
Wind power generation has been growing at a very fast pace for the past decade, and its influence and impact on the electric power grid is significant. As in a conventional power plant, a wind power plant (WPP) must ensure that the quality of the power being delivered to the grid is excellent. At the same time, the wind turbine should be able to operate immune to small disturbances coming from the grid. Harmonics are one of the more common power quality issues presented by large WPPs because of the high switching frequency of the power converters and the possible nonlinear behavior from electric machines (generator, transformer, reactors) within a power plant. This paper presents a summary of the most important issues related to harmonics in WPPs and discusses practical experiences with actual Type 1 and Type 3 wind turbines in two WPPs.
Considering the Harmonic Sequence “Paradox”
Directory of Open Access Journals (Sweden)
Robert Vivian
2011-06-01
Full Text Available Blavatskyy (2006 formulated a game of chance based on the harmonic series which, he suggests, leads to a St Petersburg type of paradox. In view of the importance of the St Petersburg game in decision theory, any game which leads to a St Petersburg game type paradox is of interest. Blavatskyy’s game is re-examined in this article to conclude that it does not lead to a St Petersburg type paradox.
Rectification Efficiency of Two Harmonically Coupled Particles
Institute of Scientific and Technical Information of China (English)
SUN Lian-Xiu
2009-01-01
@@ Transportation properties of two harmonically coupled particles moving in a flashing or rocking ratchet potential are investigated in terms of Langevin simulation. The efficiency for rectification of non-equilibrium fluctuation is calculated by using a new definition. The results show that both the average current and efficiency of two coupled particles in the flashing ratchet are larger than that of a single particle and these quantities are non-monotonous functions of the potential remaining time.
Interpolating Spherical Harmonics for Computing Antenna Patterns
2011-07-01
the specific radon-transform algorithms of ISAR. 28 References [1] Arfken , George [1970] Mathematical Methods for Physicists, second edi- tion...approximation methods . Section 2 sets out two antenna patterns to be tested in the spline algorithm. Section 3 reviews the spherical harmonic functions Y mn...number of samples on the sphere [12]. This compressed sensing result will not reduce the method of moment computations. All the current must be
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...... on a 40 kW laboratory model connected to the utility-grid, where the DFIG is supplied by a back-to-back 3-level NPC-converter....
Curvature and bubble convergence of harmonic maps
Kokarev, Gerasim
2010-01-01
We explore geometric aspects of bubble convergence for harmonic maps. More precisely, we show that the formation of bubbles is characterised by the local excess of curvature on the target manifold. We give a universal estimate for curvature concentration masses at each bubble point and show that there is no curvature loss in the necks. Our principal hypothesis is that the target manifold is Kaehler.
Rotating field transformers eliminate rectifier harmonics
Energy Technology Data Exchange (ETDEWEB)
Pastor, C.E. [Westinghouse Motor Co., Round Rock, TX (United States); Buckle, K.A. [Univ. of South Florida, Tampa, FL (United States); Luce, J.W. [Luce (John W.), Tampa, FL (United States)
1995-10-01
The rotating field transformer is a static device that has the same magnetic field as a three phase motor. When used to feed diode rectifiers, it converts ac to dc with low ripple on the output voltage and remarkably low current distortion on the input. Filters are not needed. This is a timely development because it is an economical and very effective solution to the growing problem of power system harmonics.
Harmonic Resonances in Wind Power Plants
DEFF Research Database (Denmark)
Fernandez, Francisco Daniel Freijedo; Chaudhary, Sanjay; Teodorescu, Remus
2015-01-01
converters. Subsequently, pros and cons of frequency and time domain analysis methods are outlined. The next sections are devoted to mitigation methods implemented in the power electronics converters. From the wind turbine perspective, different techniques to enhance the robustness of the controller...... are analyzed. Subsequently, the suitability for active damping of harmonics using STATCOM devices is assessed, with focus both on control techniques and power converter technologies....
Fischer decomposition in symplectic harmonic analysis
Brackx, Fred; De Schepper, Hennie; Eelbode, David; Lávička, Roman; Soucek, Vladimir
2014-01-01
In the framework of quaternionic Clifford analysis in Euclidean space , which constitutes a refinement of Euclidean and Hermitian Clifford analysis, the Fischer decomposition of the space of complex valued polynomials is obtained in terms of spaces of so-called (adjoint) symplectic spherical harmonics, which are irreducible modules for the symplectic group Sp. Its Howe dual partner is determined to be sl(2, C) circle plus sl(2, C) = so(4, C).
Unitary representations and harmonic analysis an introduction
Sugiura, M
1990-01-01
The principal aim of this book is to give an introduction to harmonic analysis and the theory of unitary representations of Lie groups. The second edition has been brought up to date with a number of textual changes in each of the five chapters, a new appendix on Fatou''s theorem has been added in connection with the limits of discrete series, and the bibliography has been tripled in length.
Food legislation and its harmonization in Russia.
Shamtsyan, Mark
2014-08-01
Bringing Russian legislation into compliance with international norms and standards is necessary after its accession to the World Trade Organization. Harmonization of food legislation and of sanitary and phytosanitary measures are among the problems that had to be solved first. Many Russian food and trade regulations had been changed or are still in the process of being reformed, largely owing to a policy of integration pursued by the Customs Union of Russia, Belarus and Kazakhstan. However, as a member of the Eurasian Economic Community, Russia is also engaged not only in harmonization throughout the Customs Union but also Kirgizstan and Tajikistan, and Armenia, Moldova and Ukraine as observer countries. Russia also continues to coordinate policy reforms closely with the European Union, its primary trade partner, ultimately bringing Russian food and sanitary norms closer to international standards (e.g. Codex). Today, all participants in the Russian food production chain, processing and sale of foods have to deal with growing numbers of security standards. Many organizations are certified under several schemes, which leads to unnecessary costs. Harmonization of standards has helped promote solutions in the domestic market as well as import-export of foods and raw materials for production. Priorities have included food safety for human health, consumer protection, removal of hazardous and/or adulterated products and increased competition within the domestic food market as well as mutual recognition of certification in bilateral and multilateral (inter)national agreements. © 2013 Society of Chemical Industry.
Harmonics of circadian gene transcription in mammals.
Directory of Open Access Journals (Sweden)
Michael E Hughes
2009-04-01
Full Text Available The circadian clock is a molecular and cellular oscillator found in most mammalian tissues that regulates rhythmic physiology and behavior. Numerous investigations have addressed the contribution of circadian rhythmicity to cellular, organ, and organismal physiology. We recently developed a method to look at transcriptional oscillations with unprecedented precision and accuracy using high-density time sampling. Here, we report a comparison of oscillating transcription from mouse liver, NIH3T3, and U2OS cells. Several surprising observations resulted from this study, including a 100-fold difference in the number of cycling transcripts in autonomous cellular models of the oscillator versus tissues harvested from intact mice. Strikingly, we found two clusters of genes that cycle at the second and third harmonic of circadian rhythmicity in liver, but not cultured cells. Validation experiments show that 12-hour oscillatory transcripts occur in several other peripheral tissues as well including heart, kidney, and lungs. These harmonics are lost ex vivo, as well as under restricted feeding conditions. Taken in sum, these studies illustrate the importance of time sampling with respect to multiple testing, suggest caution in use of autonomous cellular models to study clock output, and demonstrate the existence of harmonics of circadian gene expression in the mouse.
Harmonics of circadian gene transcription in mammals.
Hughes, Michael E; DiTacchio, Luciano; Hayes, Kevin R; Vollmers, Christopher; Pulivarthy, S; Baggs, Julie E; Panda, Satchidananda; Hogenesch, John B
2009-04-01
The circadian clock is a molecular and cellular oscillator found in most mammalian tissues that regulates rhythmic physiology and behavior. Numerous investigations have addressed the contribution of circadian rhythmicity to cellular, organ, and organismal physiology. We recently developed a method to look at transcriptional oscillations with unprecedented precision and accuracy using high-density time sampling. Here, we report a comparison of oscillating transcription from mouse liver, NIH3T3, and U2OS cells. Several surprising observations resulted from this study, including a 100-fold difference in the number of cycling transcripts in autonomous cellular models of the oscillator versus tissues harvested from intact mice. Strikingly, we found two clusters of genes that cycle at the second and third harmonic of circadian rhythmicity in liver, but not cultured cells. Validation experiments show that 12-hour oscillatory transcripts occur in several other peripheral tissues as well including heart, kidney, and lungs. These harmonics are lost ex vivo, as well as under restricted feeding conditions. Taken in sum, these studies illustrate the importance of time sampling with respect to multiple testing, suggest caution in use of autonomous cellular models to study clock output, and demonstrate the existence of harmonics of circadian gene expression in the mouse.
Means of Harmonization in Religious Discourse
Directory of Open Access Journals (Sweden)
Irina Ščukina
2012-12-01
Full Text Available Means of harmonization of religious discourse are considered by studying communicational behaviour (verbal and nonverbal between the religion institution and believers. The following factors defining specificity of realization of harmonization in Orthodox and other religious texts are taken into account: the communication channel between the author and the reader, a defining speech genre, the command of language (communication code, and extra-linguistic factors. It is shown that sharing the general social, historical and national experience, as well as a lexical overlapping of actors on both sides of the communication channel are the deciding elements of the harmonization process. The analysis also shows that usage of rational argumentation is more likely to lead to harmonisation in comparison to other rhetoric tools (i. e. affective ones or story-telling. Rational and unemotional sermonic discourse is perceived as a sign of respect (namely, for the listener's intelligence. Another successful and much-applied way seems to be evoking a feeling of equality, unity and/or identity between clerics and their flocks.
A possible upgrade of FLASH for harmonic lasing down to 1.3 nm
Schneidmiller, E A
2012-01-01
We propose the 3rd harmonic lasing in a new FLASH undulator as a way to produce intense, narrow-band, and stable SASE radiation down to 1.3 nm with the present accelerator energy of 1.25 GeV. To provide optimal conditions for harmonic lasing, we suggest to suppress the fundamental with the help of a special set of phase shifters. We rely on the standard technology of gap-tunable planar hybrid undulators, and choose the period of 2.3 cm and the minimum gap of 0.9 cm; total length of the undulator system is 34.5 m. With the help of numerical simulations we demonstrate that the 3rd harmonic lasing at 1.3 nm provides peak power at a gigawatt level and the narrow intrinsic bandwidth, 0.1% (FWHM). Pulse duration can be controlled in the range of a few tens of femtoseconds, and the peak brilliance reaches the value of 10^31 photons/(s mrad^2 mm^2 0.1%BW). With the given undulator design, a standard option of lasing at the fundamental wavelength to saturation is possible through the entire water window and at longer ...
Energy Technology Data Exchange (ETDEWEB)
Breuer, G D; Chow, J H; Lindh, C B; Miller, N W; Numrich, F H; Price, W W; Turner, A E; Whitney, R R
1982-09-01
Improved methods are needed to characterize ac system harmonic behavior for ac filter design for HVDC systems. The purpose of this General Electric Company RP1138 research is to evaluate the present filter design practice and to investigate methods for calculating system harmonic impedances. An overview of ac filter design for HVDC systems and a survey of literature related to filter design have been performed. Two methods for calculating system harmonic impedances have been investigated. In the measurement method, an instrumentation system for measuring system voltage and current has been assembled. Different schemes of using the measurements to calculate system harmonic impedances have been studied. In the analytical method, a procedure to include various operating conditions has been proposed. Computer programs for both methods have been prepared, and the results of the measurement and analytical methods analyzed. A conclusion of the project is that the measurement and analytical methods both provided reasonable results. There are correlations between the measured and analytical results for most harmonics, although there are discrepancies between the assumptions used in the two methods. A sensitivity approach has been proposed to further correlate the results. From the results of the analysis, it is recommended that both methods should be tested further. For the measurement method, more testing should be done to cover different system operating conditions. In the analytical method, more detailed models for representing system components should be studied. In addition, alternative statistical and sensitivity approaches should be attempted.
Energy Technology Data Exchange (ETDEWEB)
Breuer, G D; Chow, J H; Lindh, C B; Miller, N W; Numrich, F H; Price, W W; Turner, A E; Whitney, R R
1982-09-01
Improved methods are needed to characterize ac system harmonic behavior for ac filter design for HVDC systems. The purpose of this General Electric Company RP1138 research is to evaluate the present filter design practice and to investigate methods for calculating system harmonic impedances. An overview of ac filter design for HVDC systems and a survey of literature related to filter design have been performed. Two methods for calculating system harmonic impedances have been investigated. In the measurement method, an instrumentation system for measuring system voltage and current has been assembled. Different schemes of using the measurements to calculate system harmonic impedances have been studied. In the analytical method, a procedure to include various operating conditions has been proposed. Computer programs for both methods have been prepared, and the results of the measurement and analytical methods analyzed. A conclusion of the project is that the measurement and analytical methods both provided reasonable results. There are correlations between the measured and analytical results for most harmonics, although there are discrepancies between the assumptions used in the two methods. A sensitivity approach has been proposed to further correlate the results. From the results of the analysis, it is recommended that both methods should be tested further. For the measurement method, more testing should be done to cover different system operating conditions. In the analytical method, more detailed models for representing system components should be studied. In addition, alternative statistical and sensitivity approaches should be attempted.
Harmonic balance approach to the periodic solutions of the (an)harmonic relativistic oscillator
Energy Technology Data Exchange (ETDEWEB)
Belendez, Augusto [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es; Pascual, Carolina [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)
2007-11-19
The first-order harmonic balance method via the first Fourier coefficient is used to construct two approximate frequency-amplitude relations for the relativistic oscillator for which the nonlinearity (anharmonicity) is a relativistic effect due to the time line dilation along the world line. Making a change of variable, a new nonlinear differential equation is obtained and two procedures are used to approximately solve this differential equation. In the first the differential equation is rewritten in a form that does not contain a square-root expression, while in the second the differential equation is solved directly. The approximate frequency obtained using the second procedure is more accurate than the frequency obtained with the first due to the fact that, in the second procedure, application of the harmonic balance method produces an infinite set of harmonics, while in the first procedure only two harmonics are produced. Both approximate frequencies are valid for the complete range of oscillation amplitudes, and excellent agreement of the approximate frequencies with the exact one are demonstrated and discussed. The discrepancy between the first-order approximate frequency obtained by means of the second procedure and the exact frequency never exceeds 1.6%. We also obtained the approximate frequency by applying the second-order harmonic balance method and in this case the relative error is as low 0.31% for all the range of values of amplitude of oscillation A.
Hybrid ultrasound imaging techniques (fusion imaging).
Sandulescu, Daniela Larisa; Dumitrescu, Daniela; Rogoveanu, Ion; Saftoiu, Adrian
2011-01-07
Visualization of tumor angiogenesis can facilitate non-invasive evaluation of tumor vascular characteristics to supplement the conventional diagnostic imaging goals of depicting tumor location, size, and morphology. Hybrid imaging techniques combine anatomic [ultrasound, computed tomography (CT), and/or magnetic resonance imaging (MRI)] and molecular (single photon emission CT and positron emission tomography) imaging modalities. One example is real-time virtual sonography, which combines ultrasound (grayscale, colour Doppler, or dynamic contrast harmonic imaging) with contrast-enhanced CT/MRI. The benefits of fusion imaging include an increased diagnostic confidence, direct comparison of the lesions using different imaging modalities, more precise monitoring of interventional procedures, and reduced radiation exposure.
Hybrid compensation arrangement in dispersed generation systems
DEFF Research Database (Denmark)
Chen, Zhe; Blaabjerg, Frede; Pedersen, John Kim
2005-01-01
This paper presents a hybrid compensation system consisting of an active filter and distributed passive filters. In the system, each individual passive filter is connected to a distortion source and designed to eliminate main harmonics and supply reactive power for the distortion source, while...... are performed for a power system including the dispersed generation units connected into the system through power electronic converters and diode rectifier loads, which produce the distorted waveforms. The simulation results have demonstrated that good compensation effects can be achieved by using the combined...
Handschuh, Robert F. (Inventor); Roberts, Gary D. (Inventor)
2016-01-01
A hybrid gear consisting of metallic outer rim with gear teeth and metallic hub in combination with a composite lay up between the shaft interface (hub) and gear tooth rim is described. The composite lay-up lightens the gear member while having similar torque carrying capability and it attenuates the impact loading driven noise/vibration that is typical in gear systems. The gear has the same operational capability with respect to shaft speed, torque, and temperature as an all-metallic gear as used in aerospace gear design.
DEFF Research Database (Denmark)
has turned out as a major focus of European education and training policies and certainly is a crucial principle underlying the European Qualifications Framework (EQF). In this context, «hybrid qualifications» (HQ) may be seen as an interesting approach to tackle these challenges as they serve «two...... masters», i.e. by producing skills for the labour market and enabling individuals to progress more or less directly to higher education. The specific focus of this book is placed on conditions, structures and processes which help to combine VET with qualifications leading into higher education...
Wu, Guang; Dong, Zuomin
2017-09-01
Hybrid electric vehicles are widely accepted as a promising short to mid-term technical solution due to noticeably improved efficiency and lower emissions at competitive costs. In recent years, various hybrid powertrain systems were proposed and implemented based on different types of conventional transmission. Power-split system, including Toyota Hybrid System and Ford Hybrid System, are well-known examples. However, their relatively low torque capacity, and the drive of alternative and more advanced designs encouraged other innovative hybrid system designs. In this work, a new type of hybrid powertrain system based hybridized automated manual transmission (HAMT) is proposed. By using the concept of torque gap filler (TGF), this new hybrid powertrain type has the potential to overcome issue of torque gap during gearshift. The HAMT design (patent pending) is described in details, from gear layout and design of gear ratios (EV mode and HEV mode) to torque paths at different gears. As an analytical tool, mutli-body model of vehicle equipped with this HAMT was built to analyze powertrain dynamics at various steady and transient modes. A gearshift was decomposed and analyzed based basic modes. Furthermore, a Simulink-SimDriveline hybrid vehicle model was built for the new transmission, driveline and vehicle modular. Control strategy has also been built to harmonically coordinate different powertrain components to realize TGF function. A vehicle launch simulation test has been completed under 30% of accelerator pedal position to reveal details during gearshift. Simulation results showed that this HAMT can eliminate most torque gap that has been persistent issue of traditional AMT, improving both drivability and performance. This work demonstrated a new type of transmission that features high torque capacity, high efficiency and improved drivability.
Imaging parameters on third harmonic transmit phasing for tissue harmonic generation.
Shen, Che-Chou; Wang, Yu-Chun; Yeh, Chih-Kuang
2008-06-01
In third harmonic (3f0) transmit phasing, transmit waveforms comprising fundamental (f0) signal and 3f0 signal are used to generate both frequency-sum and frequency-difference components for manipulation of tissue harmonic amplitude. Nevertheless, the acoustic propagation of 3f0 transmit signal suffers from more severe attenuation and phase aberration than the f0 signal and hence degrades the performance of 3f0 transmit phasing. Besides, 3f0 transmit parameters such as aperture size and signal bandwidth are also influential in 3f0 transmit phasing. In this study, extensive simulations were performed to investigate the effects of these imaging parameters. Results indicate that the harmonic enhancement and suppression in 3f0 transmit phasing are compromised when the magnitude of frequency-difference component decreases in the presence of tissue attenuation and phase aberration. To compensate for the reduced frequency-difference component, a higher 3f0 transmit amplitude can be used. When the transmit parameters are concerned, a smaller 3f0 transmit aperture can provide more axially uniform harmonic enhancement and more effective suppression of harmonic amplitude. In addition, the spectral leakage signal also interferes with tissue harmonics and degrades the efficacy of 3f0 transmit phasing. Our results suggest that, in the method of 3f0 transmit phasing, the transmit amplitude, phase and aperture size of 3f0 signal should remain adjustable for optimization of clinical performance. Besides, multipulse sequences such as pulse inversion are also favorable for leakage removal in 3f0 transmit phasing.
Second Harmonic Generation in Scanning Probe Microscopy for Edge Localization
Institute of Scientific and Technical Information of China (English)
HU Xiao-Gen; LI Yu-He; LIN Hao-Shan; WANG Dong-Sheng; QI Xin
2011-01-01
We present an approach of second harmonic generation for edge localization of nano-scale defects measurement,based on the impact of the oscillating tip on the sample that induces higher harmonics of the excitation frequency.The harmonic signals of tip motion are measured by the heterodyne interferornetry. The edge amplitude ratio for the edge characterization can be calculated by a mechanics model and the threshold of edge localization is experimentally determined by second harmonic profiles. This approach has been successfully utilized to measure the pitch of a standard sample. The results show that the second harmonic is sensitive to locating the edge of nano-scale defects with high accuracy.%@@ We present an approach of second harmonic generation for edge localization of nano-scale defects measurement,based on the impact of the oscillating tip on the sample that induces higher harmonics of the excitation frequency.The harmonic signals of tip motion are measured by the heterodyne interferometry.The edge amplitude ratio for the edge characterization can be calculated by a mechanics model and the threshold of edge localization is experimentally determined by second harmonic profiles.This approach has been successfully utilized to measure the pitch of a standard sample.The results show that the second harmonic is sensitive to locating the edge of nano-scale defects with high accuracy.
Influence of Harmonics in Laboratory due to Nonlinear Loads
Directory of Open Access Journals (Sweden)
Risnidar Chan
2012-03-01
Full Text Available This research was focused on the customer’s side of the meter which is the effect of harmonics on a laboratory in Electrical System Engineering School at K.Wai Perlis. Harmonic currents in equipments can cause them to experience overheating and increased losses, while harmonic voltage produces magnetic fields rotating at a speed corresponding to the harmonic frequency. This also results in equipments heating, mechanical vibrations and noise, reduced efficiency, reduced life, and voltage stress on insulation of equipment windings. The loads in this research are computers, Compact Fluorescent Lamps CFLs, Air Conditions and printers,which all of the loads are harmonic significant The instrument to measure and monitoring is Fluke 435 Power Quality Analyzer. With the operation of varying nonlinear loads, the injected harmonic current magnitudes and phase angles vary in a random way. This research offers the advantage of providing the utility a wealth of information on the effects of harmonics in their equipments. This will subsequently make them aware of the causes of increased cost and reduced efficiency that may be experienced by using these equipments. This paper describes the investigation cost of harmonic effect as THD, and harmonic energy losses cost. Keywords: harmonics, nonlinear loads, Energy losses cost, THD.
The sheath effect on the floating harmonic method
Energy Technology Data Exchange (ETDEWEB)
Lee, Jaewon; Kim, Kyung-Hyun; Chung, Chin-Wook, E-mail: joykang@hanyang.ac.kr [Department of Electrical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)
2015-12-15
The floating harmonic method biases sinusoidal voltage to a probe sheath, and as its response, harmonic currents can be obtained. These currents can be used to determine the plasma parameters. However, different shapes of probes have different shapes of sheaths that can affect the diagnostic results. However, no research has been done on the sheath effect on the floating harmonic method. Therefore, we investigate the effect of the sheath during floating harmonic diagnostics by comparing cylindrical and planar probes. While the sinusoidal voltages were applied to a probe, because the sheath oscillated, the time variant ion current and their harmonic currents were added to the electron harmonic currents. In the floating harmonic method, the harmonic currents are composed of only the electron harmonic currents. Therefore, the ion harmonic currents affect the diagnostic results. In particular, the electron temperature obtained by the small probe tip was higher than that of the large probe tip. This effect was exacerbated when the ratio of the probe tip radius to the sheath length was smaller.
Toward Rigorous Data Harmonization in Cancer Epidemiology Research: One Approach.
Rolland, Betsy; Reid, Suzanna; Stelling, Deanna; Warnick, Greg; Thornquist, Mark; Feng, Ziding; Potter, John D
2015-12-15
Cancer epidemiologists have a long history of combining data sets in pooled analyses, often harmonizing heterogeneous data from multiple studies into 1 large data set. Although there are useful websites on data harmonization with recommendations and support, there is little research on best practices in data harmonization; each project conducts harmonization according to its own internal standards. The field would be greatly served by charting the process of data harmonization to enhance the quality of the harmonized data. Here, we describe the data harmonization process utilized at the Fred Hutchinson Cancer Research Center (Seattle, Washington) by the coordinating centers of several research projects. We describe a 6-step harmonization process, including: 1) identification of questions the harmonized data set is required to answer; 2) identification of high-level data concepts to answer those questions; 3) assessment of data availability for data concepts; 4) development of common data elements for each data concept; 5) mapping and transformation of individual data points to common data elements; and 6) quality-control procedures. Our aim here is not to claim a "correct" way of doing data harmonization but to encourage others to describe their processes in order that we can begin to create rigorous approaches. We also propose a research agenda around this issue. © The Author 2015. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Coherent harmonic production using a two-section undulator FEL
Energy Technology Data Exchange (ETDEWEB)
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.
DEFF Research Database (Denmark)
Braüner, Torben
2011-01-01
Intuitionistic hybrid logic is hybrid modal logic over an intuitionistic logic basis instead of a classical logical basis. In this short paper we introduce intuitionistic hybrid logic and we give a survey of work in the area.......Intuitionistic hybrid logic is hybrid modal logic over an intuitionistic logic basis instead of a classical logical basis. In this short paper we introduce intuitionistic hybrid logic and we give a survey of work in the area....
Continuity Controlled Hybrid Automata
Bergstra, J. A.; Middelburg, C.A.
2004-01-01
We investigate the connections between the process algebra for hybrid systems of Bergstra and Middelburg and the formalism of hybrid automata of Henzinger et al. We give interpretations of hybrid automata in the process algebra for hybrid systems and compare them with the standard interpretation of hybrid automata as timed transition systems. We also relate the synchronized product operator on hybrid automata to the parallel composition operator of the process algebra. It turns out that the f...
Algal Supply System Design - Harmonized Version
Energy Technology Data Exchange (ETDEWEB)
Jared Abodeely; Daniel Stevens; Allison Ray; Debor
2013-03-01
The objective of this design report is to provide an assessment of current technologies used for production, dewatering, and converting microalgae cultivated in open-pond systems to biofuel. The original draft design was created in 2011 and has subsequently been brought into agreement with the DOE harmonized model. The design report extends beyond this harmonized model to discuss some of the challenges with assessing algal production systems, including the ability to (1) quickly assess alternative algal production system designs, (2) assess spatial and temporal variability, and (3) perform large-scale assessments considering multiple scenarios for thousands of potential sites. The Algae Logistics Model (ALM) was developed to address each of these limitations of current modeling efforts to enable assessment of the economic feasibility of algal production systems across the United States. The (ALM) enables (1) dynamic assessments using spatiotemporal conditions, (2) exploration of algal production system design configurations, (3) investigation of algal production system operating assumptions, and (4) trade-off assessments with technology decisions and operating assumptions. The report discusses results from the ALM, which is used to assess the baseline design determined by harmonization efforts between U.S. DOE national laboratories. Productivity and resource assessment data is provided by coupling the ALM with the Biomass Assessment Tool developed at PNNL. This high-fidelity data is dynamically passed to the ALM and used to help better understand the impacts of spatial and temporal constraints on algal production systems by providing a cost for producing extracted algal lipids annually for each potential site.
IDENTIFICATION OF HARMONIC SOURCES IN DEREGULATED POWER SECTOR
Directory of Open Access Journals (Sweden)
KRITI VAID,
2011-03-01
Full Text Available In this paper identification of origin of harmonic source in deregulated power sector has been carried out. Critical impedance method (CIM for detection of harmonic disturbances caused between utility and source side has already been reported in literature. The method is based on direction of reactive power flow in the power system when there is the presence of harmonic load. Taking the CIM as the base method harmonic sources are identified in deregulated power sector. Due to unavailability of practical data simulation approach has been adopted. A five bus system model with two Generation ompanies (GENCOS has been simulated for power transfer from GENCO to the considered five bus system. Harmonic current is injected into the system by using a three phase diode rectifier. The results obtainedusing the CIM clearly identifies whether the harmonic source is present in GENCO side or the load side.
The Obstacle Problem for the A-Harmonic Equation
Directory of Open Access Journals (Sweden)
Zhenhua Cao
2010-01-01
Full Text Available Firstly, we define an order for differential forms. Secondly, we also define the supersolution and subsolution of the A-harmonic equation and the obstacle problems for differential forms which satisfy the A-harmonic equation, and we obtain the relations between the solutions to A-harmonic equation and the solution to the obstacle problem of the A-harmonic equation. Finally, as an application of the obstacle problem, we prove the existence and uniqueness of the solution to the A-harmonic equation on a bounded domain Ω with a smooth boundary ∂Ω, where the A-harmonic equation satisfies d⋆A(x,du=0,x∈Ω; u=ρ,x∈∂Ω, where ρ is any given differential form which belongs to W1,p(Ω,Λl-1.
Relationships between Harmonic Characteristics and Different Types of Voltage Source
Directory of Open Access Journals (Sweden)
Yusniati Yusniati
2012-06-01
Full Text Available This paper discusses about harmonic characteristics due to different types of voltage sources. Usually, the voltage source is sinusoidal. But in actual condition the load that receive voltage sources through the elements where the output voltage of element as input to the load is not pure sinusoidal, for example voltage source at (PCC between transformer and linear load and nonlinear load. This research has been done with Schhafner Power Quality Analyzer and PM300 Power Quality Analyzer, was focused to all harmonic characteristics as power, voltage, current, power factor (p.f., Harmonic Distortion, and harmonic energy losses cost. The load is Induction Motor with Adjustable Speed Drive (ASD because the Induction Motor with Adjustable Speed Drive (ASD is one of electronic device causes harmonics. The voltage sources in this research are sine wave, square wave and harmonic order combinations of 3rd, 5th and 7th which can create from Schhafner Power Quality Analyzer.
Second-harmonic imaging of semiconductor quantum dots
DEFF Research Database (Denmark)
Østergaard, John Erland; Bozhevolnyi, Sergey I.; Pedersen, Kjeld;
2000-01-01
Resonant second-harmonic generation is observed at room temperature in reflection from self-assembled InAlGaAs quantum dots grown on a GaAs (001) substrate. The detected second-harmonic signal peaks at a pump wavelength of similar to 885 nm corresponding to the quantum-dot photoluminescence maximum....... In addition, the second-harmonic spectrum exhibits another smaller but well-pronounced peak at 765 nm not found in the linear experiments. We attribute this peak to the generation of second-harmonic radiation in the AlGaAs spacer layer enhanced by the local symmetry at the quantum-dot interface. We further...... observe that second-harmonic images of the quantum-dot surface structure show wavelength-dependent spatial variations. Imaging at different wavelength is used to demonstrate second-harmonic generation from the semiconductor quantum dots. (C) 2000 American Institute of Physics....
APF for harmonic voltage resonance suppression in distribution system
DEFF Research Database (Denmark)
Sun, Xiaofeng; Zeng, Jian; Chen, Zhe
2010-01-01
Traditional active power filter (APF) can prevent harmonic current from injecting into power system, but can not damp harmonic propagation in distribution system whereas voltage detection can do. This paper proposes a compound control method of APF based on detection of load current and harmonic...... voltage at the point of installation. In addition, based on the relationship between the rated volt-ampere of APF and the load volt-ampere, the conductance value could automatic adjustment. The objective of the shunt active filter is not only to compensate the harmonic but also to damp the harmonic. When...... the rated volt-ampere is limit, the harmonic compensation is prior considered. Computer simulation and experiment result are performed to verify the validity and effectiveness of the shunt active filter equipped with the compound control. © 2010 IEEE....
Intense harmonics generation with customized photon frequency and optical vortex
Zhang, Xiaomei; Shen, Baifei; Shi, Yin; Zhang, Lingang; Ji, Liangliang; Wang, Xiaofeng; Xu, Zhizhan; Tajima, Toshiki
2016-08-01
An optical vortex with orbital angular momentum (OAM) enriches the light and matter interaction process, and helps reveal unexpected information in relativistic nonlinear optics. A scheme is proposed for the first time to explore the origin of photons in the generated harmonics, and produce relativistic intense harmonics with expected frequency and an optical vortex. When two counter-propagating Laguerre-Gaussian laser pulses impinge on a solid thin foil and interact with each other, the contribution of each input pulse in producing harmonics can be distinguished with the help of angular momentum conservation of photons, which is almost impossible for harmonic generation without an optical vortex. The generation of tunable, intense vortex harmonics with different photon topological charge is predicted based on the theoretical analysis and three-dimensional particle-in-cell simulations. Inheriting the properties of OAM and harmonics, the obtained intense vortex beam can be applied in a wide range of fields, including atom or molecule control and manipulation.
Relationships between Harmonic Characteristics and Different Types of Voltage Source
Directory of Open Access Journals (Sweden)
Syafruddin H
2012-06-01
Full Text Available This paper discusses about harmonic characteristics due to different types of voltage sources. Usually, the voltage source is sinusoidal. But in actual condition the load that receive voltage sources through the elements where the output voltage of element as input to the load is not pure sinusoidal, for example voltage source at (PCC between transformer and linear load and nonlinear load. This research has been done with Schhafner Power Quality Analyzer and PM300 Power Quality Analyzer, was focused to all harmonic characteristics as power, voltage, current, power factor (p.f., Harmonic Distortion, and harmonic energy losses cost. The load is Induction Motor with Adjustable Speed Drive (ASD because the Induction Motor with Adjustable Speed Drive (ASD is one of electronic device causes harmonics. The voltage sources in this research are sine wave, square wave and harmonic order combinations of 3rd, 5th and 7th which can create from Schhafner Power Quality Analyzer.
High-order harmonic generation from the dressed autoionizing states
Fareed, M. A.; Strelkov, V. V.; Thiré, N.; Mondal, S.; Schmidt, B. E.; Légaré, F.; Ozaki, T.
2017-07-01
In high-order harmonic generation, resonant harmonics (RH) are sources of intense, coherent extreme-ultraviolet radiation. However, intensity enhancement of RH only occurs for a single harmonic order, making it challenging to generate short attosecond pulses. Moreover, the mechanism involved behind such RH was circumstantial, because of the lack of direct experimental proofs. Here, we demonstrate the exact quantum paths that electron follows for RH generation using tin, showing that it involves not only the autoionizing state, but also a harmonic generation from dressed-AIS that appears as two coherent satellite harmonics at frequencies +/-2Ω from the RH (Ω represents laser frequency). Our observations of harmonic emission from dressed states open the possibilities of generating intense and broadband attosecond pulses, thus contributing to future applications in attosecond science, as well as the perspective of studying the femtosecond and attosecond dynamics of autoionizing states.
On harmonic operation of Shanghai deep UV free electron laser
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
By choosing parameters in the modulator,the dispersive section and the seed laser,the spatial bunching of the electron beam can be correlated to then-th harmonic of ther adiator radiation,instead of the fundamental radiation in conventional high-gain harmonic generation(HGHG).Thus,the radiator undulator is operated at high harmonic mode.In this paper,the possibility of harmonic operation of Shanghai deep ultraviolet(SDUV)free electron laser (FEL)is studied.Discussions on the principle of harmonic operation,the simulation code development,the simulation results.and the proposed experimental procedure for verification of harmonic operation at the SDUV FEL are also presented.
Gain of harmonic generation in high gain free electron laser
Institute of Scientific and Technical Information of China (English)
DENG Hai-Xiao; DAI Zhi-Min
2008-01-01
In a planar undulator employed free electron laser(FEL),each harmonic radiation starts from linear amplification and ends with nonlinear harmonic interactions of the lower nonlinear harmonics and the fundamental radiation.In this paper,we investigate the harmonic generation based on the dispersion relation driven from the coupled Maxwell-Vlasov equations,taking into account the effects due to energy spread,emittance,betatron oscillation of electron beam as well as diffraction guiding of the radiation field.A 3D universal scaling function for gain of the linear harmonic generation and a 1D universal scaling function for gain of the nonlinear harmonic generation are presented,which promise rapid computation in FEL design and optimization.The analytical approaches have been validated by 3D simulation results in large range.
On the harmonic index of graph operations
Directory of Open Access Journals (Sweden)
B. Shwetha Shetty
2015-12-01
Full Text Available The harmonic index of a connected graph G , denoted by H(G , is defined as H(G=∑ uv∈E(G 2d u +d v where d v is the degree of a vertex v in G. In this paper, expressions for the Harary indices of the join, corona product, Cartesian product, composition and symmetric difference of graphs are derived.
On the harmonic index of graph operations
B. Shwetha Shetty; V. Lokesha; Ranjini, P.S.
2015-01-01
The harmonic index of a connected graph G , denoted by H(G) , is defined as H(G)=∑ uv∈E(G) 2d u +d v where d v is the degree of a vertex v in G. In this paper, expressions for the Harary indices of the join, corona product, Cartesian product, composition and symmetric difference of graphs are derived.
Power quality and harmonic instrumentation selection
Energy Technology Data Exchange (ETDEWEB)
Stebbins, W.L.; Golden, P.
1996-05-01
The proliferation of adjustable speed drive (ASD) systems in commercial and industrial settings has prompted a new awareness of the impact of harmonics and other power quality (PQ) concerns. The PQ issues have a direct bearing on the reliability of these systems and the ability to perform the desired tasks in an interruption free manner. Details presented include identifying power quality problems, selecting the proper type of monitoring instruments, and interpretation of data. Included are typical instrument specifications and cost. Additionally the advent of artificial intelligence tools for PQ analysis and the resulting impact on providing solutions is described.
Contrast-enhanced harmonic endoscopic ultrasound
DEFF Research Database (Denmark)
Săftoiu, A; Dietrich, C F; Vilmann, P
2012-01-01
Second-generation intravenous blood-pool ultrasound contrast agents are increasingly used in endoscopic ultrasound (EUS) for characterization of microvascularization, differential diagnosis of benign and malignant focal lesions, and improving staging and guidance of therapeutic procedures. Although...... contrast-enhanced harmonic EUS based on a very low mechanical index (0.08 - 0.12). Quantification techniques based on dynamic contrast-enhanced ultrasound have been recommended for perfusion imaging and monitoring of anti-angiogenic treatment, mainly based on time-intensity curve analysis. Most...
Information cloning of harmonic oscillator coherent states
Indian Academy of Sciences (India)
N D Hari Dass; Pradeep Ganesh
2002-08-01
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 of this perfect information cloning it would be possible to estimate the original state through measurements and make arbitrary number of copies of the estimator. We deﬁne the notion of a measurement ﬁdelity and calculate it for our case as well as for the Gaussian cloners.
Perturbing rational harmonic functions by poles
Sète, Olivier; Liesen, Jörg
2014-01-01
We study how adding certain poles to rational harmonic functions of the form $R(z)-\\bar{z}$, with $R(z)$ rational and of degree $d\\geq 2$, affects the number of zeros of the resulting functions. Our results are motivated by and generalize a construction of Rhie derived in the context of gravitational microlensing (ArXiv e-print 2003). Of particular interest is the construction and the behavior of rational functions $R(z)$ that are {\\em extremal} in the sense that $R(z)-\\bar{z}$ has the maximal possible number of $5(d-1)$ zeros.
Harmonic Vibrational Analysis in Delocalized Internal Coordinates.
Jensen, Frank; Palmer, David S
2011-01-11
It is shown that a principal component analysis of a large set of internal coordinates can be used to define a nonredundant set of delocalized internal coordinates suitable for the calculation of harmonic vibrational normal modes. The selection of internal coordinates and the principal component analysis provide large degrees of freedom in extracting a nonredundant set of coordinates, and thus influence how the vibrational normal modes are described. It is shown that long-range coordinates may be especially suitable for describing low-frequency global deformation modes in proteins.
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...
Harmonic and Monogenic Potentials in Euclidean Halfspace
Brackx, F.; De Bie, H.; De Schepper, H.
2011-09-01
In the framework of Clifford analysis a chain of harmonic and monogenic potentials is constructed in the upper half of Euclidean space Rm+1. Their distributional limits at the boundary are computed, obtaining in this way well-known distributions in Rm such as the Dirac distribution, the Hilbert kernel, the square root of the negative Laplace operator, and the like. It is shown how each of those potentials may be recovered from an adjacent kernel in the chain by an appropriate convolution with such a distributional limit.
Directory of Open Access Journals (Sweden)
A. Esposito
2016-07-01
Full Text Available We propose a new interpretation of the neutral and charged X,Z exotic hadron resonances. Hybridized-tetraquarks are neither purely compact tetraquark states nor bound or loosely bound molecules but rather a manifestation of the interplay between the two. While meson molecules need a negative or zero binding energy, its counterpart for h-tetraquarks is required to be positive. The formation mechanism of this new class of hadrons is inspired by that of Feshbach metastable states in atomic physics. The recent claim of an exotic resonance in the Bs0π± channel by the D0 Collaboration and the negative result presented subsequently by the LHCb Collaboration are understood in this scheme, together with a considerable portion of available data on X,Z particles. Considerations on a state with the same quantum numbers as the X(5568 are also made.
Esposito, A.; Polosa, A.D.
2016-01-01
We propose a new interpretation of the neutral and charged X, Z exotic hadron resonances. Hybridized-tetraquarks are neither purely compact tetraquark states nor bound or loosely bound molecules. The latter would require a negative or zero binding energy whose counterpart in h-tetraquarks is a positive quantity. The formation mechanism of this new class of hadrons is inspired by that of Feshbach metastable states in atomic physics. The recent claim of an exotic resonance in the Bs pi+- channel by the D0 collaboration and the negative result presented subsequently by the LHCb collaboration are understood in this scheme, together with a considerable portion of available data on X, Z particles. Considerations on a state with the same quantum numbers as the X(5568) are also made.
Improvement of Power Quality Using a Hybrid Interline UPQC
Directory of Open Access Journals (Sweden)
M.K.Elango
2014-05-01
Full Text Available This paper proposed the reduced rating star connected transformer based interline unified power quality conditioner. This work comprises of unified power quality conditioner connected between the two feeders, star connected transformer and LC filter. This hybrid approach significantly improves the performance of UPQC under unbalance source voltage condition. The UPQC adopted to compensate current and voltage-quality problems of sensitive loads and suppressing the load current harmonics under distorted supply conditions. The series converter control strategy is based on the fuzzy-logic controller. The extensive simulation results have carried out in MATLAB/Simulink environment power system blockset toolboxes. From the results it has shown that hybrid interline UPQC achieves superior capability of mitigating the effects of voltage sag/swell and suppressing the load current harmonics, phase current harmonics and neutral current under distorted supply conditions. To validate the results produced by the proposed method, it is compared with the conventional UPQC method and better results obtained from the hybrid approach.
Properties of the Third Harmonic of the SASE FEL Radiation
Saldin, E L; Schneidmiller, E
2005-01-01
Recent theoretical and experimental studies have shown that SASE FEL with a planar undulator holds a potential for generation of relatively strong coherent radiation at the third harmonic of the fundamental frequency. Here we present detailed study of the nonlinear harmonic generation in SASE FEL obtained with time-dependent FEL simulation code FAST. Using similarity techniques we present universal dependencies for temporal, spectral, and statistical properties of the third harmonic radiation from SASE FEL.
Relativistic surface-plasmon enhanced harmonic generation from gratings
Fedeli, Luca; Cantono, Giada; Macchi, Andrea
2016-01-01
The role of relativistic surface plasmons (SPs) in high order harmonic emission from laser-irradiated grating targets has been investigated by means of particle-in-cell simulations. SP excitation drives a strong enhancement of the intensity of harmonics, particularly in the direction close to the surface tangent. The SP-driven enhancement overlaps with the angular separation of harmonics generated by the grating, which is beneficial for applications requiring monochromatic XUV pulses.
Illuminating Molecular Symmetries with Bicircular High-Order-Harmonic Generation
Reich, Daniel M
2016-01-01
We present a complete theory of bicircular high-order-harmonic emission from N-fold rotationally symmetric molecules. Using a rotating frame of reference we predict the complete structure of the high-order-harmonic spectra for arbitrary driving frequency ratios and show how molecular symmetries can be directly identified from the harmonic signal. Our findings reveal that a characteristic fingerprint of rotational molecular symmetries can be universally observed in the ultrafast response of molecules to strong bicircular fields.
Harmonic maps of finite uniton number into $G_2$
Correia, N
2010-01-01
We establish explicit formulae for canonical factorizations of extended solutions corresponding to harmonic maps of finite uniton number into the exceptional Lie group $G_2$ in terms of the Grassmannian model for the group of based algebraic loops in $G_2$. A description of the ``Frenet frame data" for such harmonic maps is given. In particular, we show that harmonic spheres into $G_2$ correspond to solutions of certain algebraic systems of quadratic and cubic equations.
High-Order Harmonic Generation in the Ionization Process
Institute of Scientific and Technical Information of China (English)
CHEN Jing; CHEN Shi-Gang; LIU Jie
2000-01-01
Based on the nonperturbative quantum electrodynamics scattering theory for multiphoton ionization developed recently, high-order harmonic generated in the ionization process is discussed. The influence of the Coulomb potential is treated as a perturbation in the expansion of the transition matrix. It is deduced that the harmonic photons are emitted in the resonant process during ionization and the width of the harmonic peaks is just the ionization rate of the atom.
Virial Theorem for a Class of Quantum Nonlinear Harmonic Oscillators
Institute of Scientific and Technical Information of China (English)
王雪红; 郭军义; 李艳
2012-01-01
In this paper,the Virial Theorem based on a class of quantum nonlinear harmonic oscillators is presented.This relationship has to do with parameter λ and ?/?λ,where the λ is a real number.When λ=0,the nonlinear harmonic oscillator naturally reduces to the usual quantum linear harmonic oscillator,and the Virial Theorem also reduces to the usual Virial Theorem.
Directory of Open Access Journals (Sweden)
Andreica Horia Tudor
2010-12-01
Full Text Available The new configuration of the international economic relations which are in a general globalization process determined by the international capital circulation requires the compatibility and comparison of the information provided by the financial statements. The investors and the entrepreneurs wish to understand and to be able to compare the entities financial situation and performances, no matter the juridical and accounting system which are subdued to by their localization. The differences between the important variety of the accounting systems were identified long time ago and since then there have been efforts made in order to conceive a economic financial reporting structure, accessible to the entire accounting world. Therefore, there is the need of normalization, harmonization, and convergence in accounting. Our intention in the current paper is to bring again into discussion the problem of accounting harmonization, emphasizing a few aspects which in the Romanian context we consider to be controversial and which require some clarifications. This paper represents a brief review of the evolution of the accounting harmonization in Romania, analyzing the difficult moments and mainly it is focused on the conceptual understanding of the concepts of harmonization, convergence, and conformity in the Romanian accounting. Our approach is not an exhaustive one, but it has as objective to reflect on the importance of the stages of accounting modernization in Romania. In the last part of this paper, the conclusions that we reached after study, are presented synthetically, as well as the continuation of the approach initiated in other papers.
A Harmonic Impedance Measurement System for Reduction of Harmonics in the Electricity Grid
Heskes, P.J.M.; Myrzik, J.M.A.; Kling, W.L.
2009-01-01
This paper describes the development of a Complex Harmonic Impedance Measurement system, called the CHIME-system. This system performs on-line impedance measurements in the electricity grid and will be designed for implementation in Digital Signal Processor (DSP) control systems of grid-connected el
Chiou, See-Ying; Forsberg, Flemming; Fox, Traci B; Needleman, Laurence
2007-11-01
The purpose of this study was to compare fundamental gray scale sonography, tissue harmonic imaging (THI), and differential tissue harmonic imaging (DTHI) for depicting normal and abnormal livers. The in vitro lateral resolution of DTHI, THI, and sonography was assessed in a phantom. Sagittal and transverse images of right and left hepatic lobes of 5 volunteers and 20 patients and images of 27 liver lesions were also acquired. Three independent blinded readers scored all randomized images for noise, detail resolution, image quality, and margin (for lesions) on a 7-point scale. Next, images from the same location obtained with all 3 modes were compared blindly side by side and rated by all readers. Contrast-to-noise ratios were calculated for the lesions, and the depth of penetration (centimeters) was determined for all images. In vitro, the lateral resolution of DTHI was significantly better than fundamental sonography (P = .009) and showed a trend toward significance versus THI (P = .06). In the far field, DTHI performed better than both modes (P images were scored, and for all parameters, DTHI and THI did better than sonography (P tissue harmonic imaging scored significantly higher than THI with regard to detail resolution and image quality (P Tissue harmonic imaging and DTHI do better than fundamental sonography for hepatic imaging, with DTHI being rated the best of the 3 techniques.
Indian Academy of Sciences (India)
Rajarshi Chakrabarti
2009-04-01
Based on a Hamiltonian description we present a rigorous derivation of the transient state work fluctuation theorem and the Jarzynski equality for a classical harmonic oscillator linearly coupled to a harmonic heat bath, which is dragged by an external agent. Coupling with the bath makes the dynamics dissipative. Since we do not assume anything about the spectral nature of the harmonic bath the derivation is not restricted only to the Ohmic bath, rather it is more general, for a non-Ohmic bath. We also derive expressions of the average work done and the variance of the work done in terms of the two-time correlation function of the fluctuations of the position of the harmonic oscillator. In the case of an Ohmic bath, we use these relations to evaluate the average work done and the variance of the work done analytically and verify the transient state work fluctuation theorem quantitatively. Actually these relations have far-reaching consequences. They can be used to numerically evaluate the average work done and the variance of the work done in the case of a non-Ohmic bath when analytical evaluation is not possible.
Comparative Analysis of Instruments Measuring Time Varying Harmonics
Belchior, Fernando Nunes; Ribeiro, Paulo Fernando; Carvalho, Frederico Marques
2016-08-01
This paper aims to evaluate the performance of commercial class A and class S power quality (PQ) instruments when measuring time-varying harmonics. By using a high precision programmable voltage and current source, two meters from different manufacturers are analyzed and compared. Three-phase voltage signals are applied to PQ instruments, considering 3 situations of time-varying harmonic distortions, whose harmonic distortion values are in accordance with typical values found in power systems. This work is relevant considering that international standardization documents do not pay much attention to this aspect of harmonic distortion.
Higher Harmonics Generation in Tapping Mode Atomic Force Microscope
Institute of Scientific and Technical Information of China (English)
LI Yuan; QIAN Jian-Qiang
2009-01-01
The contribution of higher harmonics to the movement of a micro rectangular cantilever in tapping mode AFM is investigated. The dependence between the phase lag of the higher harmonic components and tip-sample separation are found to be an order of magnitude higher than the base one, reflecting an increasing sensitivity to local variations of surface properties compared to the normal phase signal.The strong correlation between the higher harmonic amplitude and average sample deformation implies that the higher harmonic amplitude can be taken to monitor the tapping force or as feedback variable to fulfill a constant repulsive force mode.
Image Formation in Second-Harmonic Near-Field Microscopy
DEFF Research Database (Denmark)
Bozhevolnyi, Sergey I.; Lozovski, Valeri Z.; Pedersen, Kjeld
1999-01-01
A macroscopic self-consistent approach that enables one to rigorously describe image formation in scanning near-field optical second-harmonic generation microscopy is developed. The self-consistent second-harmonic field is determined by taking into account both the linear and nonlinear contributi......A macroscopic self-consistent approach that enables one to rigorously describe image formation in scanning near-field optical second-harmonic generation microscopy is developed. The self-consistent second-harmonic field is determined by taking into account both the linear and nonlinear...
Role of Excited States In High-order Harmonic Generation
Beaulieu, S.; Camp, S.; Descamps, D.; Comby, A.; Wanie, V.; Petit, S.; Légaré, F.; Schafer, K. J.; Gaarde, M. B.; Catoire, F.; Mairesse, Y.
2016-11-01
We investigate the role of excited states in high-order harmonic generation by studying the spectral, spatial, and temporal characteristics of the radiation produced near the ionization threshold of argon by few-cycle laser pulses. We show that the population of excited states can lead either to direct extreme ultraviolet emission through free induction decay or to the generation of high-order harmonics through ionization from these states and recombination to the ground state. By using the attosecond lighthouse technique, we demonstrate that the high-harmonic emission from excited states is temporally delayed by a few femtoseconds compared to the usual harmonics, leading to a strong nonadiabatic spectral redshift.
The location of critical points of analytic and harmonic functions
Walsh, J L
1950-01-01
This book is concerned with the critical points of analytic and harmonic functions. A critical point of an analytic function means a zero of its derivative, and a critical point of a harmonic function means a point where both partial derivatives vanish. The analytic functions considered are largely polynomials, rational functions, and certain periodic, entire, and meromorphic functions. The harmonic functions considered are largely Green's functions, harmonic measures, and various linear combinations of them. The interest in these functions centers around the approximate location of their crit
Tissue Characterization on Ultrasound Harmonic Signals using Nakagami Statistics
Lin, Fanglue; Cristea, Anca; Cachard, Christian; Basset, Olivier
Quantitative ultrasound (QUS) imaging provides a way to characterize biological tissue. The QUS estimates can be obtained from the envelope statistics. Previous studies are mainly based on the whole backscattered signals analysis. However, the ultrasound propagation is a nonlinear process and the harmonic signals can therefore reveal the nonlinear nature of a biological medium. The present study investigates the statistics of harmonic signal envelopes to relate the distribution parameters to the nonlinear coefficients. The main results demonstrate that the distributions exhibit a different behavior for fundamental and harmonic signals and that media with different nonlinearities can be distinguished, when using Nakagami statistics on the harmonic signal envelopes.
ON REGULARITY THEOREMS FOR LINEARLY INVARIANT FAMILIES OF HARMONIC FUNCTIONS
Directory of Open Access Journals (Sweden)
E. G. Ganenkova
2015-05-01
Full Text Available The classical theorem of growth regularity in the class S of analytic and univalent in the unit disc ∆ functions ƒ describes the growth character of different functionals of ƒ Є S and z Є ∆ as z tends to δ∆. Earlier the authors proved the theorems of growth and decrease regularity for harmonic and sense-preserving in ∆ functions which generalized the classical result for the class S. In the presented paper we establish new properties of harmonic sense-preserving functions, connected with the regularity theorems. The effects both common for analytic and harmonic case and specific for harmonic functions are displayed.
Effective harmonic oscillator description of anharmonic molecular vibrations
Indian Academy of Sciences (India)
Tapta Kanchan Roy; M Durga Prasad
2009-09-01
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 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.
Goos-Hänchen shifts in harmonic generation from metals.
Yallapragada, V J; Gopal, Achanta Venu; Agarwal, G S
2013-05-06
We present the first calculation of the Goos-Hänchen shifts in the context of the nonlinear generation of fields. We specifically concentrate on shifts of second harmonic generated at metallic surfaces. At metallic surfaces the second harmonic primarily arises from discontinuities of the field at surfaces which not only result in large harmonic generation but also in significant Goos-Hänchen shifts of the generated second harmonic. Our results can be extended to other shifts like angular shifts and Fedorov-Imbert shifts.
High-order harmonic generation from eld-distorted orbitals
DEFF Research Database (Denmark)
Spiewanowski, Maciek; Etches, Adam; Madsen, Lars Bojer
We investigate the eect on high-order harmonic generation of the distortion of molecular orbitals by the driving laser eld. Calculations for high-order harmonic generation including orbital distortion are performed for N2 (high polarizability). Our results allow us to suggest that field-distortio......We investigate the eect on high-order harmonic generation of the distortion of molecular orbitals by the driving laser eld. Calculations for high-order harmonic generation including orbital distortion are performed for N2 (high polarizability). Our results allow us to suggest that field...
Analysing harmonic motions with an iPhone’s magnetometer
Yavuz, Ahmet; Kağan Temiz, Burak
2016-05-01
In this paper, we propose an experiment for analysing harmonic motion using an iPhone’s (or iPad’s) magnetometer. This experiment consists of the detection of magnetic field variations obtained from an iPhone’s magnetometer sensor. A graph of harmonic motion is directly displayed on the iPhone’s screen using the Sensor Kinetics application. Data from this application was analysed with Eureqa software to establish the equation of the harmonic motion. Analyses show that the use of an iPhone’s magnetometer to analyse harmonic motion is a practical and effective method for small oscillations and frequencies less than 15-20 Hz.
Microgrid Reactive and Harmonic Power Sharing Using Enhanced Virtual Impedance
DEFF Research Database (Denmark)
He, Jinwei; Wei Li, Yun; Guerrero, Josep M.
2013-01-01
To address the load sharing problem in islanding microgrids, this paper proposes an improved approach which regulates the distributed generation (DG) unit interfacing virtual impedance at fundamental and selected harmonic frequencies. In contrast to the conventional virtual impedance control where...... feeder impedances can be properly compensated, resulting in accurate reactive and harmonic power sharing at the same time. In addition, this paper shows that the microgrid PCC harmonic voltages can be mitigated by reducing the magnitude of DG unit equivalent harmonic impedance. Finally, an improved...
Optimization Issues in a Harmonic Cascade FEL
De Ninno, G
2005-01-01
Presently there is significant interest by multiple groups (e.g. BNL, ELETTRA, LBNL, BESSY, MIT) to reach short output wavelengths via a harmonic cascade FEL using an external seed laser. In a multistage device, there are a number of "free" parameters such as the nominal power of the input seed, the lengths of the individual modulator and radiator undulators, the strengths (i.e. the R56's) of the dispersive sections, the choice of the actual harmonic numbers to reach a given wavelength, etc., whose optimization is a non-trivial exercise. In particular, one can choose whether to operate predominantly in the "high gain" regime such as was proposed by Yu [1] in which case each radiator undulator is many gain lengths long or, alternatively, in the "low gain" regime in which case all undulators (except possibly the last radiator) are a couple gain lengths or less long and the output from each radiator essentially corresponds to coherent spontaneous emission from a pre-bunched beam. With particular emphasis upon th...
Tissue harmonic synthetic aperture ultrasound imaging.
Hemmsen, Martin Christian; Rasmussen, Joachim Hee; Jensen, Jørgen Arendt
2014-10-01
Synthetic aperture sequential beamforming (SASB) and tissue harmonic imaging (THI) are combined to improve the image quality of medical ultrasound imaging. The technique is evaluated in a comparative study against dynamic receive focusing (DRF). The objective is to investigate if SASB combined with THI improves the image quality compared to DRF-THI. The major benefit of SASB is a reduced bandwidth between the probe and processing unit. A BK Medical 2202 Ultraview ultrasound scanner was used to acquire beamformed RF data for offline evaluation. The acquisition was made interleaved between methods, and data were recorded with and without pulse inversion for tissue harmonic imaging. Data were acquired using a Sound Technology 192 element convex array transducer from both a wire phantom and a tissue mimicking phantom to investigate spatial resolution and penetration. In vivo scans were also performed for a visual comparison. The spatial resolution for SASB-THI is on average 19% better than DRI-THI, and the investigation of penetration showed equally good signal-to-noise ratio. In vivo B-mode scans were made and compared. The comparison showed that SASB-THI reduces the artifact and noise interference and improves image contrast and spatial resolution.
Dark-Matter Harmonics Beyond Annual Modulation
Lee, Samuel K; Safdi, Benjamin R
2013-01-01
The count rate at dark-matter direct-detection experiments should modulate annually due to the motion of the Earth around the Sun. We show that higher-frequency modulations, including daily modulation, are also present and in some cases are nearly as strong as the annual modulation. These higher-order modes are particularly relevant if (i) the dark matter is light, O(10) GeV, (ii) the scattering is inelastic, or (iii) velocity substructure is present; for these cases, the higher-frequency modes are potentially observable at current and ton-scale detectors. We derive simple expressions for the harmonic modes as functions of the astrophysical and geophysical parameters describing the Earth's orbit, using an updated expression for the Earth's velocity that corrects a common error in the literature. For an isotropic halo velocity distribution, certain ratios of the modes are approximately constant as a function of nuclear recoil energy. Anisotropic distributions can also leave observable features in the harmonic ...
Ricci flow coupled with harmonic map flow
Müller, Reto
2009-01-01
We investigate a new geometric flow which consists of a coupled system of the Ricci flow on a closed manifold M with the harmonic map flow of a map phi from M to some closed target manifold N with a (possibly time-dependent) positive coupling constant alpha. This system can be interpreted as the gradient flow of an energy functional F_alpha which is a modification of Perelman's energy F for the Ricci flow, including the Dirichlet energy for the map phi. Surprisingly, the coupled system may be less singular than the Ricci flow or the harmonic map flow alone. In particular, we can always rule out energy concentration of phi a-priori - without any assumptions on the curvature of the target manifold N - by choosing alpha large enough. Moreover, if alpha is bounded away from zero it suffices to bound the curvature of (M,g(t)) to also obtain control of phi and all its derivatives - a result which is clearly not true for alpha = 0. Besides these new phenomena, the flow shares many good properties with the Ricci flow...
Second Harmonic Light Scattering from Macromolecules: Collagen.
Roth, Shmuel
In this work we present the theory and practice of optical second harmonic generation (SHG) as applied to rat-tail tendon collagen. Our work is the first quantitative application of SHG to biological systems. The angular dependence of SHG is found to display a sharp, intense, forward peak superimposed on a broad background. The sharp peak is shown to imply long-range polar order, while the broad background corresponds to that predicted for the random "up"/"down" array of collagen fibrils seen with the electron microscope. The dependence of fibril diameter distribution on age and state of hydration is measured. Our experiments also reveal information concerning the structure of the fibrils and their arrangement in the tendon. The degree of polar order, the coherence length of tendon for harmonic generation and the absolute magnitude of the nonlinear susceptibility of the collagen fibril are also determined. The biological significance of these findings and the many advantages of SHG for the structural study of biological macromolecules and tissues are discussed.
Holliday, Ezekiel S. (Inventor)
2014-01-01
Vibrations at harmonic frequencies are reduced by injecting harmonic balancing signals into the armature of a linear motor/alternator coupled to a Stirling machine. The vibrations are sensed to provide a signal representing the mechanical vibrations. A harmonic balancing signal is generated for selected harmonics of the operating frequency by processing the sensed vibration signal with adaptive filter algorithms of adaptive filters for each harmonic. Reference inputs for each harmonic are applied to the adaptive filter algorithms at the frequency of the selected harmonic. The harmonic balancing signals for all of the harmonics are summed with a principal control signal. The harmonic balancing signals modify the principal electrical drive voltage and drive the motor/alternator with a drive voltage component in opposition to the vibration at each harmonic.
DEFF Research Database (Denmark)
Bahman, Amir Sajjad; Blaabjerg, Frede
2013-01-01
A hybrid asymmetric 2-cell 9-level inverter is analysed and compared with two conventional multilevel inverters: the 9-level cascaded H-bridge and the 3-level diode clamped inverter, when used to drive an induction motor of 4.16kV/500kVA. In this analysis, Total Harmonic Distortion (THD), First...
Solar energy in double-pack? Hybrid collectors; Sonne im Doppelpack? Hybridkollektoren
Energy Technology Data Exchange (ETDEWEB)
Anon.
2012-07-01
The scarce roof space could be utilized more efficient by means of modules which supply electricity as well as thermal energy for the generation of hot water or heating processes. Nethertheless, these solar modules do not harmonize optimally. Thus, the so-called hybrid technology prevails only hesitantly.
Flexible Microgrid Power Quality Enhancement Using Adaptive Hybrid Voltage and Current Controller
DEFF Research Database (Denmark)
He, Jinwei; Li, Yun Wei; Blaabjerg, Frede
2014-01-01
To accomplish superior harmonic compensation performance using distributed generation (DG) unit power electronics interfaces, an adaptive hybrid voltage and current controlled method (HCM) is proposed in this paper. It shows that the proposed adaptive HCM can reduce the numbers of low-pass/bandpa...
Continuity Controlled Hybrid Automata
Bergstra, J.A.; Middelburg, C.A.
2004-01-01
We investigate the connections between the process algebra for hybrid systems of Bergstra and Middelburg and the formalism of hybrid automata of Henzinger et al. We give interpretations of hybrid automata in the process algebra for hybrid systems and compare them with the standard interpretation of
Continuity controlled Hybrid Automata
Bergstra, J.A.; Middelburg, C.A.
2008-01-01
We investigate the connections between the process algebra for hybrid systems of Bergstra and Middelburg and the formalism of hybrid automata of Henzinger et al. We give interpretations of hybrid automata in the process algebra for hybrid systems and compare them with the standard interpretation of
FPGA techniques based new hybrid modulation strategies for voltage source inverters.
Sudha, L U; Baskaran, J; Elankurisil, S A
2015-01-01
This paper corroborates three different hybrid modulation strategies suitable for single-phase voltage source inverter. The proposed method is formulated using fundamental switching and carrier based pulse width modulation methods. The main tale of this proposed method is to optimize a specific performance criterion, such as minimization of the total harmonic distortion (THD), lower order harmonics, switching losses, and heat losses. The proposed method is articulated using fundamental switching and carrier based pulse width modulation methods. Thus, the harmonic pollution in the power system will be reduced and the power quality will be augmented with better harmonic profile for a target fundamental output voltage. The proposed modulation strategies are simulated in MATLAB r2010a and implemented in a Xilinx spartan 3E-500 FG 320 FPGA processor. The feasibility of these modulation strategies is authenticated through simulation and experimental results.
170 GHz兆瓦级同轴回旋振荡管的分析计算%Analysis and calculation of a 170 GHz megawatt-level coaxial gyrotron
Institute of Scientific and Technical Information of China (English)
覃觅觅; 罗勇; 杨阔; 黄勇
2014-01-01
回旋管是最有希望应用于正在实施的国际热核实验反应堆计划的微波源器件,然而研究设计符合要求的回旋管还存在很多困难需要解决.对170 GHz兆瓦级光滑同轴回旋管的注-波互作用进行了研究.选取模式谱相对稀疏的TE31,12作为工作模式,利用Matlab编制源程序,计算了同轴回旋管的注-波耦合系数、起振电流.在考虑电子速度零散、腔壁电阻率和单模近似的基础上,对光滑同轴谐振腔的优化设计和注-波互作用进行了仿真,给出了磁场、电压、电流和内导体倾角等参量与回旋管效率的关系.结果表明,电压和磁场对回旋管效率影响较大,电子速度零散对回旋管效率影响较小,因而可降低电子枪的设计要求.此外,优化内导体倾角和同轴谐振腔结构参数可提高注-波互作用效率,降低电子速度零散对互作用效率的影响,获得了约50%的电子效率及1.7 MW输出功率.%Gyrotrons are the most promising microwave source devices that can be used in the International Thermonuclear Experimental Reactor, but there are many diffculties to be solved in study and design of gyrotrons to meet the require-ments. In this paper, the beam-wave interactions of a 170 GHz megawatt-level smooth-wall coaxial gyrotron are studied numerically. In order to attain high effciency and stable radiation, TE31,12 mode that lies in a relative sparse spectrum is selected as the operating mode, and the beam-wave coupling coeffcient and start oscillation current are calculated by a set of source codes developed by Matlab. Taking into account the electronic velocity spread and cavity wall resistivity, and based on a single-mode approximation, the optimization design and simulation of beam-wave interaction of a 170 GHz megawatt smooth-wall coaxial gyrotron have been fulfilled. The relationships between effciency and magnetic field, and the voltage, current, taper angle of insert, and other parameters are
Razin, S.; Zorin, V.; Izotov, I.; Sidorov, A.; Skalyga, V.
2014-02-01
We present experimental results on measuring the emittance of short-pulsed (≤100 μs) high-current (80-100 mA) ion beams of heavy gases (Nitrogen, Argon) formed from a dense plasma of an ECR source of multiply charged ions (MCI) with quasi-gas-dynamic mode of plasma confinement in a magnetic trap of simple mirror configuration. The discharge was created by a high-power (90 kW) pulsed radiation of a 37.5-GHz gyrotron. The normalized emittance of generated ion beams of 100 mA current was (1.2-1.3) π mm mrad (70% of ions in the beams). Comparing these results with those obtained using a cusp magnetic trap, it was concluded that the structure of the trap magnetic field lines does not exert a decisive influence on the emittance of ion beams in the gas-dynamic ECR source of MCI.
Proposal of a resonant controller for a three phase four wire grid-connected shunt hybrid filter
DEFF Research Database (Denmark)
Candela, J. I.; Rodriguez, P.; Luna, A.
2009-01-01
of the system. In addition a new hybrid filter topology, that permits to cancel out the homopolar harmonics, is presented in this paper. The good performance of this new topology as well as the proposed controller will be evaluated by means of simulations and experimental results.......This paper present a three-phase four wire hybrid filter able to perform a selective cancellation of harmonic currents based on resonant controllers. As it will be shown in this work, this kind of control permits to enhance the bandwidth of the filter controller, without hindering the stability...
Harmonic factors in the perception of tonal melodies
Povel, D.J.L.; Jansen, E.L.
2002-01-01
By common assumption, the first step in processing a tonal melody consists in setting up the appropriate metrical and harmonic frames required for the mental representation of the sequence of tones. Focusing on the generation of a harmonic frame, this study aims (a) to discover the factors that faci
Spectral inverse problem for q-deformed harmonic oscillator
Indian Academy of Sciences (India)
P K Bera; J Datta
2006-12-01
The supersymmetric quantization condition is used to study the wave functions of SWKB equivalent -deformed harmonic oscillator which are obtained by using only the knowledge of bound-state spectra of -deformed harmonic oscillator. We have also studied the nonuniqueness of the obtained interactions by this spectral inverse method.
A Law and Economics View on Harmonization of Procedural Law
L.T. Visscher (Louis)
2010-01-01
textabstractAbstract Even though there exists an extensive Law and Economics literature on the topics of procedural law and harmonization of law, very little has been written on harmonization of procedural law as such. In this paper I first provide a brief overview of the economic approach to legal
Use of dominant harmonic active filters in high power applications
Cheng, Po-Tai
The application of power electronics equipment is increasing rapidly. It is estimated that 60% of electrical power will be processed by power electronics equipment by year 2000. These equipments typically require rectifiers for AC-DC power conversion. Due to their nonlinear nature, most rectifiers draw harmonic current from the utility grid. The harmonic current causes higher energy losses, and may excite resonance conditions in the utility grid. Harmonic standards such as IEEE 519 and IEC 1000-3-2 have been proposed to regulate the harmonic current and voltage levels. This work is to develop a dominant harmonic active filter (DHAF) to realize a cost-effective active filtering solution for nonlinear loads in the range of megawatt and above. The DHAF system achieves harmonic isolation at dominant harmonic frequencies, e.g. the 5th and 7th. This approach allows use of low switching frequency and small rating active filter inverters (1%--2% of the load MVA rating) for implementation. Review of conventional passive filters and various active filters based on high bandwidth PWM inverters is provided. The control theory of the DHAF system is presented. Comparison of the DHAF system and other dominant harmonic filtering approach is provided. Simulation results and laboratory prototype test results are presented to validate the effectiveness of the proposed DHAF system.
A REMARK ON THE QUASI-HARMONIC SPHERES
Institute of Scientific and Technical Information of China (English)
XuDeliang; ZhouChunqin
2002-01-01
Several theorems on the finiteness of energy for quasi-harmonic spheres are proved,some counter-examples which state that the energy of quasi-harmonic sphere may be infinite are given. The results support some conditions of a question posed by Lin Fanghua and Wang Changyou.
Interpretation of Plateau in High-Harmonic Generation
Institute of Scientific and Technical Information of China (English)
程太旺; 李晓峰; 敖淑艳; 傅盘铭
2003-01-01
The plateau in high-harmonic generation is investigated in the frequency domain. Probability density of an electron in an electromagnetic field is obtained through analysing the quantized-field Volkov state. The plateau of high-harmonic generation reflects the spectral density of the electron at the location of nucleus after abovethreshold ionization.
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.)
Analysing Harmonic Motions with an iPhone's Magnetometer
Yavuz, Ahmet; Temiz, Burak Kagan
2016-01-01
In this paper, we propose an experiment for analysing harmonic motion using an iPhone's (or iPad's) magnetometer. This experiment consists of the detection of magnetic field variations obtained from an iPhone's magnetometer sensor. A graph of harmonic motion is directly displayed on the iPhone's screen using the "Sensor Kinetics"…