The design of an ECRH system for JET-EP

DEFF Research Database (Denmark)

Verhoeven, A.G.A.; Bongers, W.A.; Elzendoorn, B.S.Q.

2003-01-01

An electron cyclotron resonance heating (ECRH) system has been designed for JET in the framework of the JET enhanced performance project (JET-EP) under the European fusion development agreement. Due to financial constraints it has been decided not to implement this project. Nevertheless, the design...

The design of an ECRH system for JET-EP

NARCIS (Netherlands)

Verhoeven, A. G. A.; Bongers, W. A.; Elzendoorn, B. S. Q.; Graswinckel, M.; Hellingman, P.; Kooijman, W.; Kruijt, O. G.; Maagdenberg, J.; Ronden, D.; Stakenborg, J.; Sterk, A. B.; Tichler, J.; Alberti, S.; Goodman, T.; Henderson, M.; Hoekzema, J. A.; Oosterbeek, J. W.; Fernandez, A.; Likin, K.; Bruschi, A.; Cirant, S.; Novaks, S.; Piosczyk, B.; Thumm, M.; Bindslev, H.; Kaye, A.; Fleming, C.; Zohm, H.

2003-01-01

An electron cyclotron resonance heating (ECRH) system has been designed for JET in the framework of the JET enhanced performance project (JET-EP) under the European fusion development agreement. Due to financial constraints it has been decided not to implement this project. Nevertheless, the design

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

39GHz ECRH system for breakdown studies on the TCA tokamak

International Nuclear Information System (INIS)

Pochelon, A.; Goodman, T.; Whaley, D.; Tran, M.Q.; Reinhard, D.; Perrenoud, A.; Joedicke, B.; Mathews, H.G.; Kasparek, W.; Thumm, M.

1990-01-01

The design construction and first operation of a 39GHz ECRH system (300 kW, 100 ms) for low loop-voltage breakdown and startup-assist experiments on the TCA tokamak is described. (author) 5 refs., 6 figs., 1 tab

ECRH and W7-X: An intriguing pair

Science.gov (United States)

Erckmann, V.; Braune, H.; Gantenbein, G.; Jelonnek, J.; Kasparek, W.; Laqua, H. P.; Lechte, C.; Marushchenko, N. B.; Michel, G.; Plaum, B.; Thumm, M.; Weissgerber, M.; Wolf, R.; W7-X ECRH Teams

2014-02-01

The construction of the W7-X basic machine is almost completed and the device is approaching the commissioning phase. W7-X operation will be supported by ECRH working at 140 GHz in 2nd harmonic X- or O-mode with 10 MW cw power. Presently the activities at W7-X concentrate on the implementation of wall-armour, in-vessel components and diagnostics. The ECRH-system is in stand by with 5 out of 10 gyrotrons operational. The status of both, the W7-X device and the ECRH system is reported. Further R&D activities concentrate on extending the launching capability for sophisticated confinement investigations with remote steering launchers in a poloidal plane with weak magnetic field gradient.

Diffusive and convective transport modelling from analysis of ECRH-stimulated electron heat wave propagation. [ECRH (Electron Cyclotron Resonance Heating)

Energy Technology Data Exchange (ETDEWEB)

Erckmann, V; Gasparino, U; Giannone, L. (Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)) (and others)

1992-01-01

ECRH power modulation experiments in toroidal devices offer the chance to analyze the electron heat transport more conclusively: the electron heat wave propagation can be observed by ECE (or SX) leading to radial profiles of electron temperature modulation amplitude and time delay (phase shift). Taking also the stationary power balance into account, the local electron heat transport can be modelled by a combination of diffusive and convective transport terms. This method is applied to ECRH discharges in the W7-AS stellarator (B=2.5T, R=2m, a[<=]18 cm) where the ECRH power deposition is highly localized. In W7-AS, the T[sub e] modulation profiles measured by a high resolution ECE system are the basis for the local transport analysis. As experimental errors limit the separation of diffusive and convective terms in the electron heat transport for central power deposition, also ECRH power modulation experiments with off-axis deposition and inward heat wave propagation were performed (with 70 GHz o-mode as well as with 140 GHz x-mode for increased absorption). Because collisional electron-ion coupling and radiative losses are only small, low density ECRH discharges are best candidates for estimating the electron heat flux from power balance. (author) 2 refs., 3 figs.

Study of impurity transport in HL-2A ECRH L-mode plasmas with radially different ECRH power depositions

Science.gov (United States)

Cui, Z. Y.; Zhang, K.; Morita, S.; Ji, X. Q.; Ding, X. T.; Xu, Y.; Sun, P.; Gao, J. M.; Dong, C. F.; Zheng, D. L.; Li, Y. G.; Jiang, M.; Li, D.; Zhong, W. L.; Liu, Yi; Dong, Y. B.; Song, S. D.; Yu, L. M.; Shi, Z. B.; Fu, B. Z.; Lu, P.; Huang, M.; Yuan, B. S.; Yang, Q. W.; Duan, X. R.

2018-05-01

In HL-2A, an inverse sawtooth oscillation is observed with a long-lasting m/n  =  1/1 mode during ECRH phase with power deposition inside sawtooth inversion radius (inner-deposited ECRH), while a normal sawtooth instead appears when the ECRH power is deposited outside sawtooth inversion radius (outer-deposited ECRH). Aluminum is then injected as a trace impurity with laser blow-off (LBO) method into the inner- and outer-deposited ECRH phases of HL-2A discharges to investigate the effect of ECRH on impurity transport. Temporal behavior of soft x-ray (SXR) array signals is analyzed with a 1D impurity transport code, and radial structures of impurity transport coefficients are obtained. The result shows that the radial transport of Al ions is strongly enhanced during the inner-deposited ECRH phase. In particular, an outward convection velocity is developed with positive values of 0  ⩽  V(ρ)  ⩽  3.8 m s-1 in ρ  ⩽  0.5, while the convection velocity is inward in ρ  ⩾  0.6. In the outer-deposited ECRH discharge, on the other hand, the convection velocity takes a big negative value in ρ  ⩽  0.4 and close to zero at ρ ~ 0.6. In ohmic discharges, an inward V(ρ) always appears in the whole plasma radii and gradually increases toward the plasma edge (-3.2 m s-1 at ρ  =  1). The simulation result also indicates that centrally-peaked Al ion density profiles presented in the outer-deposited ECRH discharge can be flattened by the inner-deposited ECRH. Modification of impurity transport is discussed in the presence of long-lasting m/n  =  1/1 MHD mode.

Design and testing of data analysis tool for ECRH systems in labview

International Nuclear Information System (INIS)

Patel, Jatinkumar; Patel, H.; Purohit, D.; Rajanbabu, N.; Mistry, H.; Shukla, B.K.

2017-01-01

Electron Cyclotron Resonance Heating (ECRH) is one of the essential RF heating sub systems used for pre-ionization and current drive experiments in SST1. In SST-1, Gyrotron based two ECRH systems are installed. 42 GHz gyrotron system capable of delivering 500kW RF power for 500ms and the 82.6 GHz gyrotron capable of delivering 200kW continuously for 1000 second. VME based Data acquisition and control (DAC) system is installed with the gyrotron systems and is under operation with SST-1. This paper explains the basic features of PXI DAC and the data analysis tool designed in labview 2014 and the problems faced during design and testing of different lengths of data plot. It has various features of plotting data in different categories i.e. plotting of fast acquisition signals data to decide the sequence of gyrotron interlocks happened during the gyrotron operations, conversion of main binary file into 32 .text files and all the 32 analog signals data plot in a single plot, auto update of selected important signals plot at the end of the shot

PXIe based data acquisition and control system for ECRH systems on SST-1 and Aditya tokamak

Energy Technology Data Exchange (ETDEWEB)

Patel, Jatinkumar J., E-mail: jatin@ipr.res.in [Institute for Plasma Research, Bhat, Gandhinagar (India); Shukla, B.K.; Rajanbabu, N.; Patel, H.; Dhorajiya, P.; Purohit, D. [Institute for Plasma Research, Bhat, Gandhinagar (India); Mankadiya, K. [Optimized Solutions Pvt. Ltd (India)

2016-11-15

Highlights: • Data Aquisition and control system (DAQ). • PXIe hardware–(PXI–PCI bus extension for Instrumention Express). • RHVPS–Regulated High Voltage Power supply. • SST1–Steady state superconducting tokamak. - Abstract: In Steady State Superconducting (SST-1) tokamak, various RF heating sub-systems are used for plasma heating experiments. In SST-1, Two Electron Cyclotron Resonance Heating (ECRH) systems have been installed for pre-ionization, heating and current drive experiments. The 42 GHz gyrotron based ECRH system is installed and in operation with SST-1 plasma experiments. The 82.6 GHz gyrotron delivers 200 kW CW power (1000 s) while the 42 GHz gyrotron delivers 500 kW power for 500 ms duration. Each gyrotron system consists of various auxiliary power supplies, the crowbar unit and the water cooling system. The PXIe (PCI bus extension for Instrumentation Express)bus based DAC (Data Acquisition and Control) system has been designed, developed and under implementation for safe and reliable operation of the gyrotron. The Control and Monitoring Software applications have been developed using NI LabView 2014 software with real time support on windows platform.

PXIe based data acquisition and control system for ECRH systems on SST-1 and Aditya tokamak

International Nuclear Information System (INIS)

Patel, Jatinkumar J.; Shukla, B.K.; Rajanbabu, N.; Patel, H.; Dhorajiya, P.; Purohit, D.; Mankadiya, K.

2016-01-01

Highlights: • Data Aquisition and control system (DAQ). • PXIe hardware–(PXI–PCI bus extension for Instrumention Express). • RHVPS–Regulated High Voltage Power supply. • SST1–Steady state superconducting tokamak. - Abstract: In Steady State Superconducting (SST-1) tokamak, various RF heating sub-systems are used for plasma heating experiments. In SST-1, Two Electron Cyclotron Resonance Heating (ECRH) systems have been installed for pre-ionization, heating and current drive experiments. The 42 GHz gyrotron based ECRH system is installed and in operation with SST-1 plasma experiments. The 82.6 GHz gyrotron delivers 200 kW CW power (1000 s) while the 42 GHz gyrotron delivers 500 kW power for 500 ms duration. Each gyrotron system consists of various auxiliary power supplies, the crowbar unit and the water cooling system. The PXIe (PCI bus extension for Instrumentation Express)bus based DAC (Data Acquisition and Control) system has been designed, developed and under implementation for safe and reliable operation of the gyrotron. The Control and Monitoring Software applications have been developed using NI LabView 2014 software with real time support on windows platform.

ECRH-assisted start-up in ITER

International Nuclear Information System (INIS)

Lloyd, B.; Carolan, P.G.; Warrick, C.D.

1996-07-01

In ITER, the electric field applied for ionisation and to ramp up the plasma current may be limited to ∼ 0.3 V/m. In this case, based on established theories of the avalanche process, it is shown that ohmic breakdown in ITER is only possible over a narrow range of pressure and magnetic error field. Therefore, ECRH may be necessary to provide robust and reliable start-up. ECRH can ensure prompt breakdown over a wide range of prefill pressure and error field and can also give control over the initial time and location of breakdown. For ECRH-assisted start-up in ITER, the power and pulse length requirements are essentially determined by the need to ensure burnthrough, i.e. complete ionisation of hydrogen and the transition to high ionisation states of impurities. A 0-D code (with inclusion of some 1-D effects) has been developed to analyse burnthrough in ITER. The 0-D simulations indicate that control of the deuterium density is the key factor for ensuring successful start-up in ITER, where the effects of neutral screening and dynamic fuelling by the ex-plasma volume are also crucial. It is concluded that without ECRH, successful start-up will only be possible over a very restricted range of parameters but 3MW of absorbed ECRH power will ensure reasonably robust start-up for a broad range of conditions with beryllium impurity. In the case of carbon impurity, even with an absorbed ECRH power of 5MW one may be restricted to low prefill pressure and/or low carbon concentration for successful start-up. (Author)

Charging system of ECRH high-voltage power supply and its control system

International Nuclear Information System (INIS)

Hu Guofu; Ding Tonghai; Liu Baohua; Jiang Shufang

2003-01-01

High-voltage power supply (HVPS) of Electron Cyclotron Resonance Heating (ECRH) for HT-7 and HT-7U is presently being constructed. The high voltage (100 kV) energy of HVPS is stored in the capacitor banks, and they can power one or two gyrotrons. All the operation of the charging system will be done by the control system, where the field signals are interfaced to programmable logic controller (PLC). The use of PLC not only simplifies the control system, but also enhances the reliability. The software written by using configuration software installed in the master computer allows for remote and multiple operator control, and the status and data information is also remotely available

Description of the heliac TJ-II and its ECRH system

International Nuclear Information System (INIS)

Perea, A.; Martin, R.; Alvarez Rivas, J.L.

1986-01-01

This paper describes the main engineering aspects of the flexible heliac TJ-II, as well as the ECRH scheme that will be used for initial operation. Previous papers have described the physics of the device

Intermediate Frequency Digital Receiver Based on Multi-FPGA System

Directory of Open Access Journals (Sweden)

Chengchang Zhang

2016-01-01

Full Text Available Aiming at high-cost, large-size, and inflexibility problems of traditional analog intermediate frequency receiver in the aerospace telemetry, tracking, and command (TTC system, we have proposed a new intermediate frequency (IF digital receiver based on Multi-FPGA system in this paper. Digital beam forming (DBF is realized by coordinated rotation digital computer (CORDIC algorithm. An experimental prototype has been developed on a compact Multi-FPGA system with three FPGAs to receive 16 channels of IF digital signals. Our experimental results show that our proposed scheme is able to provide a great convenience for the design of IF digital receiver, which offers a valuable reference for real-time, low power, high density, and small size receiver design.

Monitoring millimeter wave stray radiation during ECRH operation at ASDEX Upgrade

Science.gov (United States)

Schubert, M.; Honecker, F.; Monaco, F.; Schmid-Lorch, D.; Schütz, H.; Stober, J.; Wagner, D.

2012-09-01

Due to imperfection of the single path absorption, ECRH at ASDEX Upgrade (AUG) is always accompanied by stray radiation in the vacuum vessel. New ECRH scenarios with O2 and X3 heating schemes extend the operational space, but they have also the potential to increase the level of stray radiation. There are hazards for invessel components. Damage on electric cables has already been encountered. It is therefore necessary to monitor and control the ECRH with respect to the stray radiation level. At AUG a system of Sniffer antennas equipped with microwave detection diodes is installed. The system is part of the ECRH interlock circuit. We notice, however, that during plasma operation the variations of the Sniffer antenna signal are very large. In laboratory measurements we see variations of up to 20 dB in the directional sensitivity and we conclude that an interference pattern is formed inside the copper sphere of the antenna. When ECRH is in plasma operation at AUG, the plasma is acting as a phase and mode mixer for the millimeter waves and thus the interference pattern inside the sphere changes with the characteristic time of the plasma dynamics. In order to overcome the difficulty of a calibrated measurement of the average stray radiation level, we installed bolometer and pyroelectric detectors, which intrinsically average over interference structures due to their large active area. The bolometer provides a robust calibration but with moderate temporal resolution. The pyroelectric detector provides high sensitivity and a good temporal resolution, but it raises issues of possible signal drifts in long pulses.

Monitoring millimeter wave stray radiation during ECRH operation at ASDEX Upgrade

Directory of Open Access Journals (Sweden)

Wagner D.

2012-09-01

Full Text Available Due to imperfection of the single path absorption, ECRH at ASDEX Upgrade (AUG is always accompanied by stray radiation in the vacuum vessel. New ECRH scenarios with O2 and X3 heating schemes extend the operational space, but they have also the potential to increase the level of stray radiation. There are hazards for invessel components. Damage on electric cables has already been encountered. It is therefore necessary to monitor and control the ECRH with respect to the stray radiation level. At AUG a system of Sniffer antennas equipped with microwave detection diodes is installed. The system is part of the ECRH interlock circuit. We notice, however, that during plasma operation the variations of the Sniffer antenna signal are very large. In laboratory measurements we see variations of up to 20 dB in the directional sensitivity and we conclude that an interference pattern is formed inside the copper sphere of the antenna. When ECRH is in plasma operation at AUG, the plasma is acting as a phase and mode mixer for the millimeter waves and thus the interference pattern inside the sphere changes with the characteristic time of the plasma dynamics. In order to overcome the difficulty of a calibrated measurement of the average stray radiation level, we installed bolometer and pyroelectric detectors, which intrinsically average over interference structures due to their large active area. The bolometer provides a robust calibration but with moderate temporal resolution. The pyroelectric detector provides high sensitivity and a good temporal resolution, but it raises issues of possible signal drifts in long pulses.

Multi-frequency excitation

KAUST Repository

Younis, Mohammad I.

2016-03-10

Embodiments of multi-frequency excitation are described. In various embodiments, a natural frequency of a device may be determined. In turn, a first voltage amplitude and first fixed frequency of a first source of excitation can be selected for the device based on the natural frequency. Additionally, a second voltage amplitude of a second source of excitation can be selected for the device, and the first and second sources of excitation can be applied to the device. After applying the first and second sources of excitation, a frequency of the second source of excitation can be swept. Using the methods of multi- frequency excitation described herein, new operating frequencies, operating frequency ranges, resonance frequencies, resonance frequency ranges, and/or resonance responses can be achieved for devices and systems.

Progress of high power and long pulse ECRH system in EAST

International Nuclear Information System (INIS)

Wang, Xiaojie; Liu, Fukun; Shan, Jiafang; Xu, Handong; DajunWu; Li, Bo; Wei, Wei; Zhang, Jian; Huang, Yiyun; Tang, Yunying; Xu, Weiye; Hu, Huaichuan; Wang, Jian; Xu, Li; Zhang, Liyuan; Feng, Jianqiang

2015-01-01

Highlights: • The design and the status of the 140 GHz/4 MW/1000 s ECRH system on EAST tokamak is described in detail. • Two of the four gyrotrons are tested in factory. • The transmission line and the equatorial launcher for the first 2 MW system are ready for installation. • Series tests have been carried out for the most critical elements for the real-time launcher. • The auxiliary system includes the water cooling system, the HVPS system, the vacuum system have been installed and tested. - Abstract: In accordance with the long pulse objectives of the Experimental Advanced Superconducting Tokamak (EAST), an electron cyclotron resonance heating (ECRH) system with the feature of 4 MW power for a pulse length up to 1000 s at 140 GHz, using second harmonic of the extraordinary mode (X2) is presently under construction at the institute of plasma physics, Chinese academy of sciences (ASIPP). The missions of the system are to provide central heating, current drive, plasma profile tailoring and control of magneto-hydrodynamic (MHD) instabilities. The continuous wave (CW) power is transmitted from the gyrotrons to EAST via low-loss evacuated waveguide transmission lines. Considering the diverse applications of the EC system, the front steering launcher is designed to inject four individually steered beams across nearly the entire plasma cross section. The beam's launch angles can be continuously varied with the optimized scanning range of over 30° in poloidal direction and ±25° in toroidal, as well as the polarization will be adjusted during the discharge by the orientations of a pair of polarizers in the transmission line to maintain the highest absorption for different operational scenarios. The commissioning of the first 2 MW system will be commenced in the end of 2014.

ECRH launching scenario in FFHR-d1

Science.gov (United States)

Yanagihara, Kota; Kubo, Shin; Shimozuma, Takashi; Yoshimura, Yasuo; Igami, Hiroe; Takahashi, Hiromi; Tsujimura, Tohru; Makino, Ryohhei

2016-10-01

ECRH is promising as a principal heating system in a prototype helical reactor FFHR-d1 where the heating power of 80 MW is required to bring the plasma parameter to break even condition. To generate the plasma and bring it to ignition condition in FFHR-d1, it is effective to heat the under/over-dense plasma with normal ECRH or Electron Bernstein Wave (EBW). Normal ECRH is well established but heating via EBW need sophisticated injection control. EBW can be excited via the O(ordinary)-X(extraordinary)-B(EBW) mode conversion process by launching the ordinary wave from the low field side to plasma cut-off layer with optimum injection angle, and the range of injection angle to get high OXB mode conversion rate is called OXB mode conversion window. Since the window position can change as the plasma parameter, it is necessary to optimize the injection angle so as to aim the window in response to the plasma parameters. Candidates of antenna positions are determined by optimum injection points on the plasma facing wall calculated by the injection angle. Given such picked up area, detailed analysis using ray-tracing calculations and engineering antenna design will be performed.

Real time control of plasmas and ECRH systems on TCV

NARCIS (Netherlands)

Paley, J.I.; Felici, F.; Berrino, J.; Coda, S.; Cruz, N.; Duval, B.P.; Goodman, T.P.; Martin, Y.; Moret, J.-M.; Piras, F.; Rodrigues, A.P.; Santos, B.; Varandas, C.A.F.

2008-01-01

Developments in the real time control hardware on TCV paired with the flexibility of plasma shaping and ECRH actuators are opening many opportunities to perform real time experiments and develop algorithms and methods for fusion applications. The ability to control MHD instabilities is particularly

Recent experiments with ECRH/ECCD in T-10

International Nuclear Information System (INIS)

Kislov, D.A.

2001-01-01

Experiments with ECRH performed during 1998-2000 are presented. An operating regime with an edge transport barrier, interpreted as the H-mode, has been studied with both on-axis and off-axis ECRH. Experimental data imply formation of an internal transport barrier simultaneously with the external transport barrier in the case of off-axis ECRH. Strong evolution of plasma potential in the regions of the external and internal transport barriers has been observed using Heavy Ion Beam Probe diagnostics. The mode of improved confinement with peaked density profiles and increased ion temperature has been observed after pellet injection into ECRH heated plasmas. Experimental study of q(r) profile control by ECCD has been performed. Instabilities, identified as the neoclassical tearing modes, have been found to limit beta in the regimes with a high fraction of bootstrap current. The dependence of the critical β on the q(r) profile has been observed. A systematic study of plasma turbulence has been started using Correlation Reflectometry diagnostics. (author)

Quasi-optical techniques for ECRH

International Nuclear Information System (INIS)

Andenaerde, K.; Beyer, J.; Vernon, R.

1985-01-01

The status of research at Wisconsin on quasi-optical launchers for ECRH is presented. Wengenroth's mode transducing antenna has been investigated theoretically. Agreement with experiment using TE 01 excitation is excellent, and the theory has been expanded to include TE 02 and TE 03 excitation as well. A system incorporating such and similar mode transducing antennas with a Cassegrain system will combine the output of various gyrotrons. A device to test this and similar concepts is being built and has been preliminarily tested for mode purity

Negative-feedback control system of the high voltage power supply for ECRH

International Nuclear Information System (INIS)

Ding Tonghai; Liu Baohua; Jiang Shufang

2001-01-01

A kind of high accuracy negative high voltage power supply (HVPS) was introduced. The serial feedback was regulated according to the character of the high power tetrode and a new kind of integrator with preset value, which solved the key technological problem of the HVPS that the ECRH system required a voltage of -80 kV, a pulse width of 10 - 100 ms and a precision of 99.7%. The result using a PSPICE code simulation has shown that the method is practical

An ITER-relevant evacuated waveguide transmission system for the JET-EP ECRH project

International Nuclear Information System (INIS)

Henderson, M.A.; Alberti, S.; Bird, J.

2003-01-01

An over-moded evacuated waveguide line was chosen for use in the transmission system for the proposed JET-enhanced performance project (JET-EP) electron cyclotron resonance heating (ECRH) system. A comparison between the quasi-optical, atmospheric waveguide and evacuated waveguide systems was performed for the project with a strong emphasis placed on the technical and financial aspects. The evacuated waveguide line was chosen as the optimal system in light of the above criteria. The system includes six lines of 63.5mm wave guide for transmitting 6.0 MW(10 s) at 113.3 GHz from the gyrotrons to the launching antenna. The designed lines are on average 72m in length and consist of nine mitre bends, for an estimated transmission efficiency of ∼90%. Each line is designed to include an evacuated switch leading to a calorimetric load, two dc breaks, two gate valves, one pump out tee, a power monitor mitre bend and a double-disc CVD window near the torus. The location of waveguide support is positioned to minimize the power converted to higher-order modes from waveguide sagging and misalignment. The two gate valves and CVD window are designed to be used as tritium barriers at the torus and between the J1T and J1D buildings. The last leg of the waveguide leading to the torus has to be designed to accommodate the torus movement during disruptions and thermal cycles. All lines are also designed to be compatible with the ITER ECRH system operating at 170 GHz. (author)

ECRH experiments in an extended power regime on the large helical device

International Nuclear Information System (INIS)

Shimozuma, T.; Kubo, S.; Idei, H.; LHD Experimental Group

2003-01-01

The Large Helical Device (LHD) is the largest Heliotron-type device (L 2, m = 10) The magnetic field for plasma confinement is produced by a pair of helical coils and three pairs of poloidal coils. The magnetic configuration can be adjusted by these external coils. These coils are all superconducting coils and enable steady state operation. The major and the minor radii of the produced plasmas are typically 3.6 m and 0.6 m, respectively. Plasma experiments in LHD have been proceeded since 1998. A lot of diagnostic devices have been installed to make precise plasma measurement spatially and temporally. Heating power reaches 9 MW for Neutral Beam Injection (NBI), 2.7 MW for Ion Cyclotron Range of Frequency heating (ICRF) and 1.8 MW for Electron Cyclotron Resonance Heating (ECRH). Achieved plasma parameters have been improved in each experimental campaign. In the latest experimental campaign, some improvements of the ECRH system led to interesting results related to the electron physics, such as the attainment of over 10 keV electron temperature and the improvement of core confinement in low collisionality regime. This paper reports the improvement of the ECRH system in the latest campaign and some experimental results related to the local electron heating in an extended power regime. In the Section 2 we will describe the improvements of the ECRH system for experiments in higher power region. Using this system, localized ECRH with high power density was performed. Experimental results obtained will be given in Section 3. The final section will be devoted to the following conclusions. In the latest experimental campaign, seven gyrotron systems were operable. One transmission line which was evacuated in whole system was installed in addition to the six existed 88.9 mm lines in atmospheric pressure. This line allows to transmit over 500 kW power. Flexible experiments could be performed by the inward shift of a scanning range of the existed antennas and by an installation

Fast polarizers installation for ECRH and ECE in TCV

NARCIS (Netherlands)

Silva, M.; Goodman, T.P.; Felici, F.; Porte, L.

2011-01-01

We report on the installation of fast polarizers for ECRH injection and ECE diagnostics, in the TCV tokamak. The main goal is to change the polarization during a plasma shot and react to changing conditions such as: plasma current and position, ECRH injection angles as well as ECE oblique

Diffusive and convective transport modelling from analysis of ECRH-stimulated electron heat wave propagation

International Nuclear Information System (INIS)

Erckmann, V.; Gasparino, U.; Giannone, L.

1992-01-01

ECRH power modulation experiments in toroidal devices offer the chance to analyze the electron heat transport more conclusively: the electron heat wave propagation can be observed by ECE (or SX) leading to radial profiles of electron temperature modulation amplitude and time delay (phase shift). Taking also the stationary power balance into account, the local electron heat transport can be modelled by a combination of diffusive and convective transport terms. This method is applied to ECRH discharges in the W7-AS stellarator (B=2.5T, R=2m, a≤18 cm) where the ECRH power deposition is highly localized. In W7-AS, the T e modulation profiles measured by a high resolution ECE system are the basis for the local transport analysis. As experimental errors limit the separation of diffusive and convective terms in the electron heat transport for central power deposition, also ECRH power modulation experiments with off-axis deposition and inward heat wave propagation were performed (with 70 GHz o-mode as well as with 140 GHz x-mode for increased absorption). Because collisional electron-ion coupling and radiative losses are only small, low density ECRH discharges are best candidates for estimating the electron heat flux from power balance. (author) 2 refs., 3 figs

First results from protective ECRH diagnostics for Wendelstein 7-X

Science.gov (United States)

Marsen, S.; Corre, Y.; Laqua, H. P.; Moncada, V.; Moseev, D.; Niemann, H.; Preynas, M.; Stange, T.; The W7-X Team

2017-08-01

Wendelstein 7-X (W7-X) is a steady state capable optimised stellarator. The main heating system is electron cyclotron resonance heating (ECRH) operating at 140 GHz providing up to 9 MW microwave power. The power is launched into the machine by front steerable quasi-optical launchers in X- or O-mode. While in X-mode the first pass absorption is 99%, it is only 40... 70% in O-mode. O2-mode heating is forseen for high density operation above the X2 cutoff density of 1.2\\centerdot {{10}20} m-3. A set of diagnostics has been developed to protect the machine from non absorbed ECRH power which can easily damage in vessel components. The non absorbed power hitting the inner wall is measured by waveguides embedded in the first wall (ECA diagnostic). In order to prevent the inner wall from overheating or arcing, a near-infra red sensitive video diagnostic with a dynamic range of 450...1200 °C was integrated in the ECRH launchers. Thermal calculations for the carbon tiles predict a temperature increase above the detection threshold for scenarios of plasma start-up failure or poor absorption on a time scale of 50 ms. However, the temperature increase measured by an IR camera in experiments with failed break down, i.e. no ECRH absorption for up to 50 ms, was only Δ T≈ 70{{~}\\circ} C. In discharges with ≈ 5% transmission the measured temperature increase was comparable. The stray radiation level inside the machine is measured by so called sniffer probes resembling microwave diode detectors which were designed to collect all radiation approaching the probing surface independent of incident angle and polarization. Five sniffer probes are installed at different toroidal positions. They were integrated in the ECRH interlock system. During the first operational phase of W7-X this was the only available plasma interlock system. The signal quality proofed to be high enough for a reliable termination in case of poor absorption. After a breakdown phase of 10 ms, the sniffer

Effect of ECRH and resonant magnetic fields on formation of magnetic islands in the T-10 tokamak plasma

Science.gov (United States)

Shestakov, E. A.; Savrukhin, P. V.

2017-10-01

Experiments in the T-10 tokamak demonstrated possibility of controlling the plasma current during disruption instability using the electron cyclotron resonance heating (ECRH) and the controlled operation of the ohmic current-holding system. Quasistable plasma discharge with repeating sawtooth oscillations can be restored after energy quench using auxiliary ECRH power when PEC / POH > 2-5. The external magnetic field generation system consisted of eight saddle coils that were arranged symmetrically relative to the equatorial plane of the torus outside of the vacuum vessel of the T-10 tokamak to study the possible resonant magnetic field effects on the rotation frequency of magnetic islands. The saddle coils power supply system is based on four thyristor converters with a total power of 300 kW. The power supply control system is based on Siemens S7 controllers. As shown by preliminary experiments, the interaction efficiency of external magnetic fields with plasma depends on the plasma magnetic configuration. Optimal conditions for slowing the rotation of magnetic islands were determined. Additionally, the direction of the error magnetic field in the T-10 tokamak was determined, and the threshold value of the external magnetic field was determined.

ECRH [electron-cyclotron resonance heating]-heated distributions in thermal-barrier tandem mirrors

International Nuclear Information System (INIS)

Cohen, R.H.; LoDestro, L.L.

1987-01-01

The distribution function is calculated for electrons subjected to strong electron-cyclotron resonance heating (ECRH) at the plug and barrier in a tandem-mirror thermal-barrier cell. When ECRH diffusion locally dominates over collisions and a boundary condition (associated with electrons passing to the center cell) imposes variations on the distribution function rapid compared to the variation of the ECRH and collisional diffusion coefficients, the kinetic equation can be reduced approximately to Laplace's equation. For the typical case where velocity space is divided into distinct regions in which plug and barrier ECRH dominate, the solution in each region can be expressed in terms of the plasma dispersion function or exponential integrals, according to whether the passing electrons are dominated by collisions or ECRH, respectively. The analytic results agree well with Fokker-Planck code results, in terms of both velocity-space structure and values of moments. 10 refs., 4 figs

ECRH and electron heat transport in tokamaks

International Nuclear Information System (INIS)

Zou, X.L.; Giruzzi, G.; Dumont, R.J.

2003-01-01

It has been observed during the ECRH experiments in tokamaks that the shape of the electron temperature profile in stationary regimes is not very sensitive to the ECRH power deposition i.e. the temperature profile remains peaked at the center even though the ECRH power deposition is off-axis. Various models have been invoked for the interpretation of this profile resilience phenomenon: the inward heat pinch, the critical temperature gradient, the Self-Organized Criticality, etc. Except the pinch effect, all of these models need a specific form of the diffusivity in the heat transport equation. In this work, our approach is to solve a simplified time-dependent heat transport equation analytically in cylindrical geometry. The features of this analytical solution are analyzed, in particular the relationship between the temperature profile resilience and the Eigenmode of the physical system with respect to the heat transport phenomenon. Finally, applications of this analytical solution for the determination of the transport coefficient and the polarization of the EC waves are presented. It has been shown that the solution of the simplified transport equation in a finite cylinder is a Fourier-Bessel series. This series represents in fact a decomposition of the heat source in Eigenmode, which are characterized by the Bessel functions of order 0. The physical interpretation of the Eigenmodes is the following: when the heat source is given by a Bessel function of order 0, the temperature profile has exactly the same form as the source at every time. At the beginning of the power injection, the effectiveness of the temperature response is the same for each Eigenmode, and the response in temperature, having the same form as the source, is local. Conversely, in the later phase of the evolution, the effectiveness of the temperature response for each Eigenmode is different: the higher the order, the lower the effectiveness. In this case the response in temperature appears as

Studies of the disruption prevention by ECRH at plasma current rise stage in limiter discharges

International Nuclear Information System (INIS)

Alikaev, V.V.; Borshegovskij, A.A.; Chistyakov, V.V.

1999-01-01

Studies of disruption prevention by means of ECRH in T-10 at the plasma current rise phase in limiter discharges with circular plasma cross-section were performed. Reliable disruption prevention by ECRH at HF power (P HF ) min level equal to 20% of ohmic heating power P OH was demonstrated. m/n=2/1 mode MHD-activity developed before disruption (with characteristic time ∼120 ms) can be considered as disruption precursor and can be used in a feedback system. (author)

ECRH Studies on Tokamak Plasmas.

Science.gov (United States)

1980-10-10

r.I*cru.Dtrtibution uUnliited 300 Unicorn Pork Drive Woburn, Massachusetts 04801 ECRH STUDIES ON TOKAMAK PLASMAS JAYCOR Project No. 6183 Final Report...up techniques now in use or being suggested, include growing the plasma from a small minor radius or applying a negative voltage spike immediately

A multi-frequency electrical impedance tomography system for real-time 2D and 3D imaging

Science.gov (United States)

Yang, Yunjie; Jia, Jiabin

2017-08-01

This paper presents the design and evaluation of a configurable, fast multi-frequency Electrical Impedance Tomography (mfEIT) system for real-time 2D and 3D imaging, particularly for biomedical imaging. The system integrates 32 electrode interfaces and the current frequency ranges from 10 kHz to 1 MHz. The system incorporates the following novel features. First, a fully adjustable multi-frequency current source with current monitoring function is designed. Second, a flexible switching scheme is developed for arbitrary sensing configuration and a semi-parallel data acquisition architecture is implemented for high-frame-rate data acquisition. Furthermore, multi-frequency digital quadrature demodulation is accomplished in a high-capacity Field Programmable Gate Array. At last, a 3D imaging software, visual tomography, is developed for real-time 2D and 3D image reconstruction, data analysis, and visualization. The mfEIT system is systematically tested and evaluated from the aspects of signal to noise ratio (SNR), frame rate, and 2D and 3D multi-frequency phantom imaging. The highest SNR is 82.82 dB on a 16-electrode sensor. The frame rate is up to 546 fps at serial mode and 1014 fps at semi-parallel mode. The evaluation results indicate that the presented mfEIT system is a powerful tool for real-time 2D and 3D imaging.

Multi-frequency exciting and spectrogram-based ECT method

CERN Document Server

Chady, T

2000-01-01

The purpose of this paper is to experimentally demonstrate advantages of a multi-frequency ECT system. In this system, a precise crack imaging was achieved by using spectrograms obtained from an eddy-current probe multi-frequency response. A complex signal containing selected sinusoidal components was used as an excitation. The results of measurements for various test specimens are presented.

Actuator management for ECRH at ASDEX Upgrade

Energy Technology Data Exchange (ETDEWEB)

Rapson, Christopher J., E-mail: chris.rapson@ipp.mpg.de; Reich, Matthias; Stober, Joerg; Treutterer, Wolfgang

2015-10-15

Highlights: • Real-time actuator management algorithm developed for ECRH at ASDEX Upgrade. • First use of a control hierarchy in a fusion experiment. • Cost function evaluates optimal combination of all gyrotrons to all possible targets. • Considers many factors e.g. mirror movement, power available, presence and mode number of NTMs. • Configurable, robust algorithm is ready for online testing. - Abstract: Automated actuator management will be necessary on long pulse fusion experiments to adjust to unforeseen plasma events and unpredictable actuator availability. However, as a control problem, actuator management is underdeveloped in the fusion community. This contribution proposes an algorithm based on a control hierarchy and a cost function to optimally allocate scarce actuator resources to various objectives in real-time. Details are given on the development and offline testing which have been completed ready for deployment at ASDEX Upgrade. Electron Cyclotron Resonance Heating (ECRH) is particularly relevant for actuator management due to its localised deposition which can flexibly target specific regions of the plasma for different effects such as non-inductive current drive, impurity regulation, control of MHD modes and of course heating. A further motivation is that automated actuator management will simplify the setup of ECRH, in keeping with the long term goal of integrating MHD control as a routine part of ASDEX Upgrade experiments.

Actuator management for ECRH at ASDEX Upgrade

International Nuclear Information System (INIS)

Rapson, Christopher J.; Reich, Matthias; Stober, Joerg; Treutterer, Wolfgang

2015-01-01

Highlights: • Real-time actuator management algorithm developed for ECRH at ASDEX Upgrade. • First use of a control hierarchy in a fusion experiment. • Cost function evaluates optimal combination of all gyrotrons to all possible targets. • Considers many factors e.g. mirror movement, power available, presence and mode number of NTMs. • Configurable, robust algorithm is ready for online testing. - Abstract: Automated actuator management will be necessary on long pulse fusion experiments to adjust to unforeseen plasma events and unpredictable actuator availability. However, as a control problem, actuator management is underdeveloped in the fusion community. This contribution proposes an algorithm based on a control hierarchy and a cost function to optimally allocate scarce actuator resources to various objectives in real-time. Details are given on the development and offline testing which have been completed ready for deployment at ASDEX Upgrade. Electron Cyclotron Resonance Heating (ECRH) is particularly relevant for actuator management due to its localised deposition which can flexibly target specific regions of the plasma for different effects such as non-inductive current drive, impurity regulation, control of MHD modes and of course heating. A further motivation is that automated actuator management will simplify the setup of ECRH, in keeping with the long term goal of integrating MHD control as a routine part of ASDEX Upgrade experiments.

Wall conditioning by ECRH discharges and He-GDC in the limiter phase of Wendelstein 7-X

Science.gov (United States)

Wauters, T.; Brakel, R.; Brezinsek, S.; Dinklage, A.; Goriaev, A.; Laqua, H. P.; Marsen, S.; Moseev, D.; Stange, T.; Schlisio, G.; Pedersen, T. Sunn; Volzke, O.; Wenzel, U.; the W7-X Team

2018-06-01

Wendelstein 7-X (W7-X) relies on wall conditioning to control the density and the impurity content of the plasma. Wall conditioning in the first operation campaign of W7-X consisted of baking at 150 °C during 1 week prior to operation, glow discharge conditioning (GDC) in helium (He) and electron cyclotron resonance heating (ECRH) discharges. Additionally, the usage of He-GDC was limited to avoid sputtering and migration of metallic plasma facing components. This presented a unique opportunity for studying the applicability of ECRH discharges for initial wall conditioning on a stellarator, albeit in the carbon limiter configuration. A single envelope curve is observed in the normalised outgassing data that takes into account all ECRH discharges. This illustrates that the majority of discharges operates at the limits of a radiative collapse. Hydrogen recycling dominated the fuelling of ECRH discharges throughout while CO outgassing was found strongest at the start of the campaign. A reduction of recycling was observed throughout the campaign. Temporarily depleting the walls from H and impurities was possible by He-GDC. It was shown that the recycling coefficient in -ECRH plasmas could be reduced and the pulse duration significantly extended by He-’recovery’ ECRH plasmas. Good wall conditions were defined by normalised outgassing values below mbar kJ‑1. In absence of -GDC, more than 311 cumulated discharge seconds of ECRH discharges are needed for obtaining lasting low outgassing levels. A release model with two trapping reservoirs could reproduce the normalised outgassing trend, including ECRH and GDC plasma wall interactions.

[European Community Respiratory Health Survey in Adults (ECRHS)].

Science.gov (United States)

Heinrich, J; Richter, K; Frye, C; Meyer, I; Wölke, G; Wjst, M; Nowak, D; Magnussen, H; Wichmann, H E

2002-05-01

The European Community Respiratory Health Survey (ECRHS) was the first study to assess the geographical variation in asthma, allergy, and allergic sensitization in adults using the same instruments and definitions. The database of the ECRHS includes information from approximately 140 000 individuals aged 20 - 44 years from 22 countries. The aim of this review is to summarize the results of the ECRHS and to present the specific contribution of the German centers in Hamburg and Erfurt. The prevalence ranged from 2.0 - 11.9 % for asthma, 9.5 - 40.9 % for allergic rhinitis, 4.0 - 32.0 % for wheeze, 3.4 - 27.9 % for bronchial hyperreactivity, and 16.2 - 44.5 % for allergic sensitisation against common aeroallergens. Although the prevalence of these atopic disorders were found to be consistently higher for the Hamburg center compared to the Erfurt center, strong regional differences in the prevalences were also found within several other European countries. Overall Europe, the lowest prevalences were seen in the Eastern and Middle European countries with the center Erfurt, followed by the Mediterranean region. The highest prevalences were reported for all English speaking centers. Strong geographic variation was reported for medication for asthma. Asthma seems to be undertreated in several countries. Environmental exposures and in particular indoor factors, and exposures at the workplace are playing a major role for asthma in adulthood. Furthermore, protective effects on atopy were found for exposures to pets (dogs) and a large number of siblings in early childhood. In conclusion, the ECRHS has shown that the prevalence of asthma varies widely. The fact that the geographical pattern is consistent with the distribution of atopy and bronchial responsiveness supports the conclusion that the geographical variations in the prevalence of asthma are true and likely due to environmental factors.

Segmented frequency-domain fluorescence lifetime measurements: minimizing the effects of photobleaching within a multi-component system.

Science.gov (United States)

Marwani, Hadi M; Lowry, Mark; Keating, Patrick; Warner, Isiah M; Cook, Robert L

2007-11-01

This study introduces a newly developed frequency segmentation and recombination method for frequency-domain fluorescence lifetime measurements to address the effects of changing fractional contributions over time and minimize the effects of photobleaching within multi-component systems. Frequency segmentation and recombination experiments were evaluated using a two component system consisting of fluorescein and rhodamine B. Comparison of experimental data collected in traditional and segmented fashion with simulated data, generated using different changing fractional contributions, demonstrated the validity of the technique. Frequency segmentation and recombination was also applied to a more complex system consisting of pyrene with Suwannee River fulvic acid reference and was shown to improve recovered lifetimes and fractional intensity contributions. It was observed that photobleaching in both systems led to errors in recovered lifetimes which can complicate the interpretation of lifetime results. Results showed clear evidence that the frequency segmentation and recombination method reduced errors resulting from a changing fractional contribution in a multi-component system, and allowed photobleaching issues to be addressed by commercially available instrumentation.

Multi-frequency excitation

KAUST Repository

Younis, Mohammad I.

2016-01-01

Embodiments of multi-frequency excitation are described. In various embodiments, a natural frequency of a device may be determined. In turn, a first voltage amplitude and first fixed frequency of a first source of excitation can be selected

From profile to sawtooth control: developing feedback control using ECRH/ECCD systems on the TCV tokamak

International Nuclear Information System (INIS)

Paley, J I; Felici, F; Coda, S; Goodman, T P

2009-01-01

Real time control of heating systems is essential to maximize plasma performance and avoid or neutralize instabilities under changing plasma conditions. Several feedback control algorithms have been developed on the Tokamak a Configuration Variable (TCV) tokamak that use the electron cyclotron (ECRH/ECCD) system to control a wide range of plasma properties, including the plasma current, shape, profiles as well as the sawtooth instability. Controllers have been developed to obtain sawteeth of a pre-determined period, to maximize the sawtooth period using an extremum seeking control algorithm and finally to provide simultaneous control of the plasma emission profile peak and width using multiple independent EC actuators.

A new treatment of the heat transport equation with a transport barrier and applications to ECRH experiments in Tore Supra

Energy Technology Data Exchange (ETDEWEB)

Zou, X.L.; Giruzzi, A.G.; Bouquey, F.; Clary, J.; Darbos, C.; Lennholm, M.; Magne, R.; Segui, J.L. [CEA Cadarache, Dept. de Recherches sur la Fusion Controlee, 13 - Saint-Paul-lez-Durance (France); Clemencon, A. [MIT, Electrochemical Energy Laboratory, Cambridge, MA (United States); Guivarch, C. [Ecole Nationale des Ponts et Chaussees, 77 - Marne-la-Vallee (France)

2004-07-01

An exact analytical solution of the electron heat diffusion equation in a cylinder has been found with a step-like diffusion coefficient, plus a monomial increase in the radial direction and a constant damping term. This model is sufficiently general to describe heat diffusion in the presence of a critical gradient threshold or a transport barrier, superimposed to the usual trend of increasing heat diffusivity from the plasma core to the edge. This type of representation allows us to see some well-known properties of heat transport phenomena in a different light. For instance, it has been shown that the contributions of the Eigenmodes to the time dependent solution grow at speeds that depend on the Eigenmode order i.e. at the beginning of the heating phase all the Eigenmodes are equally involved, whereas at the end only the lower order ones are left. This implies, e.g., that high frequency modulation experiments provide a characterization of transport phenomena that is intrinsically different with respect to power balance analysis of a stationary phase. It is particularly useful to analyse power switch on/off events and whenever high frequency modulations are not technically feasible. Low-frequency (1-2 Hz) ECRH modulation experiments have been performed on Tore Supra. A large jump (a factor of 8) in the heat diffusivity has been clearly identified at the ECRH power deposition layer. The amplitude and phase of several harmonics of the Fourier transform of the modulated temperature, as well as the time evolution of the modulated temperature have been reproduced by the analytical solution. The jump is found to be much weaker at lower ECRH power (one gyrotron)

First ECRH modulation experiments in Tore Supra

International Nuclear Information System (INIS)

Zou, X.L.; Artaud, J. F.; Bouquey, F.; Clary, J.; Darbos, C.; Giruzzi, G.; Lennholm, M.; Magne, R.; Segui, J.L.

2003-01-01

The modulation of Electron Cyclotron Resonance Heating (ECRH) is a powerful tool to investigate the crucial problem of heat transport in tokamaks. This method consists in producing perturbations in the electron temperature by means of highly localised electron heating. By studying the propagation of the heat pulse associated with such perturbations, it is possible to determine both the heat transport coefficient and, as a by-product, the ECRH power deposition. In this work, three methods have been used for electron transport analysis: i) the well-known FFT method; ii) an analytical method, consisting in the simulation of the temperature modulation by an analytical solution of the heat transport equation in cylindrical geometry; iii) the power balance method with the profile analysis. The three methods are applied to the analysis of recent experiments performed on Tore Supra, and their advantages and drawbacks are discussed. (authors)

A Frequency Control Approach for Hybrid Power System Using Multi-Objective Optimization

Directory of Open Access Journals (Sweden)

Mohammed Elsayed Lotfy

2017-01-01

Full Text Available A hybrid power system uses many wind turbine generators (WTG and solar photovoltaics (PV in isolated small areas. However, the output power of these renewable sources is not constant and can diverge quickly, which has a serious effect on system frequency and the continuity of demand supply. In order to solve this problem, this paper presents a new frequency control scheme for a hybrid power system to ensure supplying a high-quality power in isolated areas. The proposed power system consists of a WTG, PV, aqua-electrolyzer (AE, fuel cell (FC, battery energy storage system (BESS, flywheel (FW and diesel engine generator (DEG. Furthermore, plug-in hybrid electric vehicles (EVs are implemented at the customer side. A full-order observer is utilized to estimate the supply error. Then, the estimated supply error is considered in a frequency domain. The high-frequency component is reduced by BESS and FW; while the low-frequency component of supply error is mitigated using FC, EV and DEG. Two PI controllers are implemented in the proposed system to control the system frequency and reduce the supply error. The epsilon multi-objective genetic algorithm ( ε -MOGA is applied to optimize the controllers’ parameters. The performance of the proposed control scheme is compared with that of recent well-established techniques, such as a PID controller tuned by the quasi-oppositional harmony search algorithm (QOHSA. The effectiveness and robustness of the hybrid power system are investigated under various operating conditions.

A Proposal on Low Frequency AC Transmission as a Multi-Terminal Transmission System

Directory of Open Access Journals (Sweden)

Achara Pichetjamroen

2016-08-01

Full Text Available This paper is focused on the discussion and comparison of characteristics and behavior of three low frequency ac (LFAC transmission system configurations operating under the same control scheme and conditions to identify the most promising operation system for LFAC. Merits of LFAC over high voltage direct current (HVDC are mentioned first. By changing power flow direction without auxiliary switches in multi-terminal application and easiness of short circuit protection are explained. The three configurations of LFACs are described and applied by the control scheme with the aid of the tool of the PSCAD/EMTDC software to consider the behavior of each LFAC system on line frequency and low frequency sides. For two-phase system, no fluctuation occurs on the line frequency side, which is the advantage over single-phase system. Furthermore, current rating on thyristor devices during operation and number of devices that used in each type of LFAC are calculated and compared. These results can lead to determine the most suitable transmission system for the LFAC system operation.

TeraSCREEN: multi-frequency multi-mode Terahertz screening for border checks

Science.gov (United States)

Alexander, Naomi E.; Alderman, Byron; Allona, Fernando; Frijlink, Peter; Gonzalo, Ramón; Hägelen, Manfred; Ibáñez, Asier; Krozer, Viktor; Langford, Marian L.; Limiti, Ernesto; Platt, Duncan; Schikora, Marek; Wang, Hui; Weber, Marc Andree

2014-06-01

The challenge for any security screening system is to identify potentially harmful objects such as weapons and explosives concealed under clothing. Classical border and security checkpoints are no longer capable of fulfilling the demands of today's ever growing security requirements, especially with respect to the high throughput generally required which entails a high detection rate of threat material and a low false alarm rate. TeraSCREEN proposes to develop an innovative concept of multi-frequency multi-mode Terahertz and millimeter-wave detection with new automatic detection and classification functionalities. The system developed will demonstrate, at a live control point, the safe automatic detection and classification of objects concealed under clothing, whilst respecting privacy and increasing current throughput rates. This innovative screening system will combine multi-frequency, multi-mode images taken by passive and active subsystems which will scan the subjects and obtain complementary spatial and spectral information, thus allowing for automatic threat recognition. The TeraSCREEN project, which will run from 2013 to 2016, has received funding from the European Union's Seventh Framework Programme under the Security Call. This paper will describe the project objectives and approach.

Design of multi-frequency CW radars

CERN Document Server

Jankiraman, Mohinder

2007-01-01

This book deals with the basic theory for design and analysis of Low Probability of Intercept (LPI) radar systems. The design of one such multi-frequency high resolution LPI radar, PANDORA, is covered.

Turbulence suppression in discharges with off-axis ECRH on the T-10 tokamak device

International Nuclear Information System (INIS)

Shelukhin, D.A.; Vershkov, V.A.; Razumova, K.A.

2005-01-01

A transient steep electron temperature gradient has been observed in T-10 tokamak plasmas at ρ=0.25 immediately after off-axis electron cyclotron resonance heating (ECRH) switch-off. The turbulence characteristics were investigated in these discharges by means of correlation reflectometry. It was found that the density fluctuation amplitude was two times lower than the ohmic level in a narrow region near ρ=0.25 after ECRH switch-off. The poloidal coherence of fluctuations is also decreased in this region. The suppression of quasi-coherent oscillations has been observed in discharges during the time when the strong temperature gradient exists. Measurements of turbulent poloidal rotation showed no velocity shear after ECRH switch-off. Analysis of the linear growth rates of instabilities shows that the ion temperature gradient (ITG) mode is unstable at ρ ∼ 0.25 during the whole discharge. A possible explanation for the observed phenomena is the rational surface density decrease near q=1 due to q profile transient flattening after off-axis ECRH switch-off. (author)

Progress of the ECRH Upper Launcher design for ITER

International Nuclear Information System (INIS)

Strauss, D.; Aiello, G.; Bruschi, A.; Chavan, R.; Farina, D.; Figini, L.; Gagliardi, M.; Garcia, V.; Goodman, T.P.; Grossetti, G.; Heemskerk, C.; Henderson, M.A.; Kasparek, W.; Krause, A.; Landis, J.-D.; Meier, A.; Moro, A.; Platania, P.; Plaum, B.; Poli, E.

2014-01-01

The design of the ITER ECRH system provides 20 MW millimeter wave power for central plasma heating and MHD stabilization. The system consists of an array of 24 gyrotrons with power supplies coupled to a set of transmission lines guiding the beams to the four upper and the equatorial launcher. The front steering upper launcher design described herein has passed successfully the preliminary design review, and it is presently in the final design stage. The launcher consists of a millimeter wave system and steering mechanism with neutron shielding integrated into an upper port plug with the plasma facing blanket shield module (in-vessel) and a set of ex-vessel waveguides connecting the launcher to the transmission lines. Part of the transmission lines are the ultra-low loss CVD torus diamond windows and a shutter valve, a miter bend section and the feedthroughs integrated in the plug closure plate. These components are connected by corrugated waveguides and form together the first confinement system (FCS). In-vessel, the millimeter-wave system includes a quasi-optical beam propagation system including four mirror sets and a front steering mirror. The millimeter wave system is integrated into a specifically optimized upper port plug providing structural stability to withstand plasma disruption forces and the high heat load from the plasma side with a dedicated blanket shield module. A recent update in the ITER interface definition has resulted in the recession of the upper port plug first wall panels, which is now integrated into the design. Apart from the millimeter wave system the upper port plug houses also a set of shield blocks which provide neutron shielding. An overview of the actual ITER ECRH Upper Launcher is given together with some highlights of the design

System Description and First Application of an FPGA-Based Simultaneous Multi-Frequency Electrical Impedance Tomography

Directory of Open Access Journals (Sweden)

Susana Aguiar Santos

2016-07-01

Full Text Available A new prototype of a multi-frequency electrical impedance tomography system is presented. The system uses a field-programmable gate array as a main controller and is configured to measure at different frequencies simultaneously through a composite waveform. Both real and imaginary components of the data are computed for each frequency and sent to the personal computer over an ethernet connection, where both time-difference imaging and frequency-difference imaging are reconstructed and visualized. The system has been tested for both time-difference and frequency-difference imaging for diverse sets of frequency pairs in a resistive/capacitive test unit and in self-experiments. To our knowledge, this is the first work that shows preliminary frequency-difference images of in-vivo experiments. Results of time-difference imaging were compared with simulation results and shown that the new prototype performs well at all frequencies in the tested range of 60 kHz–960 kHz. For frequency-difference images, further development of algorithms and an improved normalization process is required to correctly reconstruct and interpreted the resulting images.

System Description and First Application of an FPGA-Based Simultaneous Multi-Frequency Electrical Impedance Tomography

Science.gov (United States)

Aguiar Santos, Susana; Robens, Anne; Boehm, Anna; Leonhardt, Steffen; Teichmann, Daniel

2016-01-01

A new prototype of a multi-frequency electrical impedance tomography system is presented. The system uses a field-programmable gate array as a main controller and is configured to measure at different frequencies simultaneously through a composite waveform. Both real and imaginary components of the data are computed for each frequency and sent to the personal computer over an ethernet connection, where both time-difference imaging and frequency-difference imaging are reconstructed and visualized. The system has been tested for both time-difference and frequency-difference imaging for diverse sets of frequency pairs in a resistive/capacitive test unit and in self-experiments. To our knowledge, this is the first work that shows preliminary frequency-difference images of in-vivo experiments. Results of time-difference imaging were compared with simulation results and shown that the new prototype performs well at all frequencies in the tested range of 60 kHz–960 kHz. For frequency-difference images, further development of algorithms and an improved normalization process is required to correctly reconstruct and interpreted the resulting images. PMID:27463715

A fractional-N frequency synthesizer-based multi-standard I/Q carrier generation system in 0.13 μm CMOS

International Nuclear Information System (INIS)

Lou Wenfeng; Geng Zhiqing; Feng Peng; Wu Nanjian

2011-01-01

This paper proposes a sigma-delta fractional-N frequency synthesizer-based multi-standard I/Q carrier generation system. With reasonable frequency planning, the system can be used in multi-standard wireless communication applications (GSM, WCDMA, GPRS, TD-SCDMA, WLAN (802.11a/b/g)). The implementation is achieved by a 0.13 μm RF CMOS process. The measured results demonstrate that three quadrature VCOs (QVCO) continuously cover the frequency from 3.1 to 6.1 GHz (65.2%), and through the successive divide-by-2 prescalers to achieve the frequency from 0.75 to 6.1 GHz continuously. The chip was fully integrated with the exception of an off-chip filter. The entire chip area is only 3.78 mm 2 , and the system consumes a 21.7 mA - 1.2 V supply without output buffers. The lock-in time of the PLL frequency synthesizer is less than 4 μs over the entire frequency range with a direct frequency presetting technique and the auxiliary non-volatile memory (NVM) can store the digital configuration signal of the system, including presetting signals to avoid the calibration process case by case. (semiconductor integrated circuits)

A fractional-N frequency synthesizer-based multi-standard I/Q carrier generation system in 0.13 {mu}m CMOS

Energy Technology Data Exchange (ETDEWEB)

Lou Wenfeng; Geng Zhiqing; Feng Peng; Wu Nanjian, E-mail: nanjian@semi.ac.cn [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

2011-06-15

This paper proposes a sigma-delta fractional-N frequency synthesizer-based multi-standard I/Q carrier generation system. With reasonable frequency planning, the system can be used in multi-standard wireless communication applications (GSM, WCDMA, GPRS, TD-SCDMA, WLAN (802.11a/b/g)). The implementation is achieved by a 0.13 {mu}m RF CMOS process. The measured results demonstrate that three quadrature VCOs (QVCO) continuously cover the frequency from 3.1 to 6.1 GHz (65.2%), and through the successive divide-by-2 prescalers to achieve the frequency from 0.75 to 6.1 GHz continuously. The chip was fully integrated with the exception of an off-chip filter. The entire chip area is only 3.78 mm{sup 2}, and the system consumes a 21.7 mA - 1.2 V supply without output buffers. The lock-in time of the PLL frequency synthesizer is less than 4 {mu}s over the entire frequency range with a direct frequency presetting technique and the auxiliary non-volatile memory (NVM) can store the digital configuration signal of the system, including presetting signals to avoid the calibration process case by case. (semiconductor integrated circuits)

ECRH experiments in ASDEX Upgrade

International Nuclear Information System (INIS)

Leuterer, F.; Guenter, S.; Hobirk, J.; Kirov, K.; Ryter, F.; Wolf, R.; Zohm, H.; Gantenbein, G.

2001-01-01

In ASDEX Upgrade ECRH and ECCD with a power of up to 2 MW has been used. With counter ECCD in discharges with an internal transport barrier we achieved an electron temperature of ≅13 keV. In low density ohmic plasmas we obtained an rf driven current of ≅80% both in co- and counter directions. Neoclassical tearing modes have been completly stabilised by driving a current on the resonant q-surface. Electron heat transport has been studied in standard L- and H-mode plasmas and can be described by a dependence on a critical electron temperature gradient

Parametric dependencies of the experimental tungsten transport coefficients in ICRH and ECRH assisted ASDEX Upgrade H-modes

Science.gov (United States)

Sertoli, M.; Angioni, C.; Odstrcil, T.; ASDEX Upgrade Team; Eurofusion MST1 Team

2017-11-01

The profiles of the W transport coefficients have been experimentally calculated for a large database of identical ASDEX Upgrade H-mode discharges where only the radio-frequency (RF) power characteristics have been varied [Angioni et al., Nucl. Fusion 57, 056015 (2017)]. Central ion cyclotron resonance heating (ICRH) in the minority heating scheme has been compared with central and off-axis electron cyclotron resonance heating (ECRH), using both localized and broad heat deposition profiles. The transport coefficients have been calculated applying the gradient-flux relation to the evolution of the intrinsic W density in-between sawtooth cycles as measured using the soft X-ray diagnostic. For both ICRH and ECRH, the major player in reducing the central W density peaking is found to be the reduction of inward pinch and, in the case of ECRH, the rise of an outward convection. The impurity convection increases, from negative to positive, almost linearly with RF-power, while no appreciable changes are observed in the diffusion coefficient, which remains roughly at neoclassical levels independent of RF power or background plasma conditions. The ratio vW/DW is consistent with the equilibrium ∇ n W / n W prior to the sawtooth crash, corroborating the separate estimates of diffusion and convection. These experimental findings are slightly different from previous results obtained analysing the evolution of impurity injections over many sawtooth cycles. Modelling performed using the drift-kinetic code NEO and the gyro-kinetic code GKW (assuming axisymmetry) overestimates the diffusion coefficient and underestimates the experimental positive convection. This is a further indication that magneto-hydrodynamic/neoclassical models accounting for 3D effects may be needed to characterize impurity transport in sawtoothing tokamak plasmas.

Development of a Millimeter-Wave Beam Position and Profile Monitor for Transmission Efficiency Improvement in an ECRH System

Directory of Open Access Journals (Sweden)

Shimozuma T.

2015-01-01

Full Text Available In a high power Electron Cyclotron Resonance Heating (ECRH system, a long-distance and low-loss transmission system is required to realize effective heating of nuclear fusion-relevant plasmas. A millimeter-wave beam position and profile monitor, which can be used in a high-power, evacuated, and cooled transmission line, is proposed, designed, manufactured, and tested. The beam monitor consists of a reflector, Peltier-device array and a heat-sink. It was tested using simulated electric heater power or gyrotron output power. The data obtained from the monitor were well agreed with the heat source position and profile. The methods of data analysis and mode-content analysis of a propagating millimeter-wave in the corrugated wave-guide are proposed.

Impact of ECRH launcher flexibility on NTM stabilization and advanced scenarios in large toroidal configurations as JET plasmas

International Nuclear Information System (INIS)

Nowak, S.; Bruschi, A.; Ramponi, G.; Cirant, S.; Lazzaro, E.; Verhoeven, A.G.A.; Zohm, H.

2003-01-01

A beam-tracing code is used for extensive beam-tracing, ECCD and ECRH profile calculations in ideal JET-like plasmas with the main aim of specifying such crucial parameters for the ECRH launcher as the poloidal and toroidal steering ranges, the permitted error in the various launching angles and the optimal shape of the last mirrors reflecting surfaces. In order to be fusion-relevant, the calculations are performed on ideal target plasmas and equilibrium configurations scaled from real JET shots, selected by the JET-EP ECRH Physics Integration Project. The launching scheme is fully compliant with a launcher designed under the geometric constraints of JET, which consists of 6 to 8 beams arranged in pairs, with four end mirrors steerable both in the poloidal and in the toroidal directions. It is shown that with this arrangement all launching configurations requested by the physics goals of ECRH in a JET-like device are feasible. (authors)

Design of current source for multi-frequency simultaneous electrical impedance tomography

Science.gov (United States)

Han, Bing; Xu, Yanbin; Dong, Feng

2017-09-01

Multi-frequency electrical impedance tomography has been evolving from the frequency-sweep approach to the multi-frequency simultaneous measurement technique which can reduce measuring time and will be increasingly attractive for time-varying biological applications. The accuracy and stability of the current source are the key factors determining the quality of the image reconstruction. This article presents a field programmable gate array-based current source for a multi-frequency simultaneous electrical impedance tomography system. A novel current source circuit was realized by combining the classic current mirror based on the feedback amplifier AD844 with a differential topology. The optimal phase offsets of harmonic sinusoids were obtained through the crest factor analysis. The output characteristics of this current source were evaluated by simulation and actual measurement. The results include the following: (1) the output impedance was compared with one of the Howland pump circuit in simulation, showing comparable performance at low frequencies. However, the proposed current source makes lower demands for resistor tolerance but performs even better at high frequencies. (2) The output impedance in actual measurement below 200 kHz is above 1.3 MΩ and can reach 250 KΩ up to 1 MHz. (3) An experiment based on a biological RC model has been implemented. The mean error for the demodulated impedance amplitude and phase are 0.192% and 0.139°, respectively. Therefore, the proposed current source is wideband, biocompatible, and high precision, which demonstrates great potential to work as a sub-system in the multi-frequency electrical impedance tomography system.

Selective injection locking of a multi-mode semiconductor laser to a multi-frequency reference beam

Science.gov (United States)

Pramod, Mysore Srinivas; Yang, Tao; Pandey, Kanhaiya; Giudici, Massimo; Wilkowski, David

2014-07-01

Injection locking is a well known and commonly used method for coherent light amplification. Usually injection locking is obtained on a single-mode laser injected by a single-frequency seeding beam. In this work we show that selective injection locking of a single-frequency may also be achieved on a multi-mode semiconductor laser injected by a multi-frequency seeding beam, if the slave laser provides sufficient frequency filtering. This selective injection locking condition depends critically on the frequency detuning between the free-running slave emission frequency and each injected frequency component. Stable selective injection locking to a set of three seeding components separated by 1.2 GHz is obtained. This system provides an amplification up to 37 dB of each component. This result suggests that, using distinct slave lasers for each frequency line, a set of mutually coherent high-power radiation modes can be tuned in the GHz frequency domain.

Particle Transport in ECRH Plasmas of the TJ-II; Transporte de Particulas en Plasmas ECRH del TJ-II

Energy Technology Data Exchange (ETDEWEB)

Vargas, V. I.; Lopez-Bruna, D.; Estrada, T.; Guasp, J.; Reynolds, J. M.; Velasco, J. L.; Herranz, J.

2007-07-01

We present a systematic study of particle transport in ECRH plasmas of TJ-II with different densities. The goal is to fi nd particle confinement time and electron diffusivity dependence with line-averaged density. The experimental information consists of electron temperature profiles, T{sub e} (Thomson Scattering TS) and electron density, n{sub e}, (TS and reflectometry) and measured puffing data in stationary discharges. The profile of the electron source, Se, was obtained by the 3D Monte-Carlo code EIRENE. The analysis of particle balance has been done by linking the results of the code EIRENE with the results of a model that reproduces ECRH plasmas in stationary conditions. In the range of densities studied (0.58 {<=}n{sub e}> (10{sup 1}9m{sup -}3) {<=}0.80) there are two regions of confinement separated by a threshold density, {approx}0.65 10{sup 1}9m{sup -}3. Below this threshold density the particle confinement time is low, and vice versa. This is reflected in the effective diffusivity, D{sub e}, which in the range of validity of this study, 0.5 <{rho}<0.9 being {rho} normalized plasma radius, decreased significantly above the threshold density. The profiles of D{sub e} are flat for {>=}0,63(10{sup 1}9m{sup -}3). (Author) 35 refs.

Cellular computational generalized neuron network for frequency situational intelligence in a multi-machine power system.

Science.gov (United States)

Wei, Yawei; Venayagamoorthy, Ganesh Kumar

2017-09-01

To prevent large interconnected power system from a cascading failure, brownout or even blackout, grid operators require access to faster than real-time information to make appropriate just-in-time control decisions. However, the communication and computational system limitations of currently used supervisory control and data acquisition (SCADA) system can only deliver delayed information. However, the deployment of synchrophasor measurement devices makes it possible to capture and visualize, in near-real-time, grid operational data with extra granularity. In this paper, a cellular computational network (CCN) approach for frequency situational intelligence (FSI) in a power system is presented. The distributed and scalable computing unit of the CCN framework makes it particularly flexible for customization for a particular set of prediction requirements. Two soft-computing algorithms have been implemented in the CCN framework: a cellular generalized neuron network (CCGNN) and a cellular multi-layer perceptron network (CCMLPN), for purposes of providing multi-timescale frequency predictions, ranging from 16.67 ms to 2 s. These two developed CCGNN and CCMLPN systems were then implemented on two different scales of power systems, one of which installed a large photovoltaic plant. A real-time power system simulator at weather station within the Real-Time Power and Intelligent Systems (RTPIS) laboratory at Clemson, SC, was then used to derive typical FSI results. Copyright © 2017 Elsevier Ltd. All rights reserved.

Recent ECRH results in ASDEX upgrade

International Nuclear Information System (INIS)

Leuterer, F.; Dux, R.; Gantenbein, G.

2003-01-01

This paper provides an overview on recent experimental results obtained in ASDEX Upgrade using electron cyclotron heating and current drive. The following topics are covered: determination of the power deposition profile, modulated power deposition, studies of the electron heat transport via power balance and heat wave analysis and a comparison with turbulent transport theory, generation of an internal transport barrier for the electron heat flux, impact of electron cyclotron resonance heating (ECRH) on particle and impurity transport, and studies related to neoclassical tearing modes and to sawteeth. (author)

Validation of a multi-frequency electrical impedance tomography (mfEIT) system KHU Mark1: impedance spectroscopy and time-difference imaging

International Nuclear Information System (INIS)

Oh, Tong In; Koo, Hwan; Lee, Kyung Heon; Kim, Sang Min; Woo, Eung Je; Lee, Jeehyun; Kim, Sung Wan; Seo, Jin Keun

2008-01-01

Validation and interpretation of reconstructed images using a multi-frequency electrical impedance tomography (mfEIT) requires a conductivity phantom including imaging objects with known complex conductivity (σ + iωε) spectra. We describe imaging experiments using the recently developed mfEIT system called the KHU Mark1 with the frequency range of 10 Hz to 500 kHz. Using a bio-impedance spectroscopy (BIS) system, we first measured complex conductivity spectra of different imaging objects including saline, agar, polyacrylamide, TX151, animal hide gelatin, banana and cucumber. Based on an analysis of how conductivity and permittivity affect measured complex boundary voltages, we suggested a new complex version of a multi-frequency time-difference image reconstruction algorithm. Imaging experiments were conducted to produce time-difference images of the objects at multiple frequencies using the proposed algorithm. Images of a conductor (stainless steel) and an insulator (acrylic plastic) were used to set a common scale bar to display all images. Comparing reconstructed time-difference images at multiple frequencies with measured complex conductivity spectra, we found that they showed an overall similarity in terms of changes in complex conductivity values with respect to frequency. However, primarily due to the limitation of the difference imaging algorithm, we suggest that multi-frequency time-difference images must be interpreted in terms of relative contrast changes with respect to frequency. We propose further imaging studies using biological tissues of known complex conductivity spectra and using human subjects to find clinical applications of the mfEIT system

Operations space diagram for ECRH and ECCD

DEFF Research Database (Denmark)

Bindslev, H.

2004-01-01

at the design phase. At the operations phase it may also prove useful in setting up experimental scenarios by showing operational possibilities, avoiding the need for survey type ray-tracing at the initial planning stages. The diagram may also serve the purpose of communicating operational possibilities to non......A Clemmov-Mullaly-Allis (CMA) type diagram, the ECW-CMA diagram, for representing the operational possibilities of electron cyclotron heating and current drive (ECRH/ECCD) systems for fusion plasmas is presented. In this diagram, with normalized density and normalized magnetic field coordinates......, the parameter range in which it is possible to achieve a given task (e.g. O-mode current drive for stabilizing a neoclassical tearing mode) appears as a region. With also the Greenwald density limit shown, this diagram condenses the information on operational possibilities, facilitating the overview required...

The 3 MW ECRH/ECCD transmission and launching system on TORE SUPRA

International Nuclear Information System (INIS)

Lennholm, M.; Agarici, G.; Berger-By, G.; Bosia, P.; Bouquey, F.; Clary, J.; Darbos, C.; Giruzzi, G.; Jung, M.; Magne, R.; Roux, D.; Petit, T.; Segui, J.L.; Zou, X.L.

2003-01-01

The ECRH experiment on TORE SUPRA is designed to inject up to 3 MW of power at 118 GHz using an antenna consisting of six fixed spherical mirrors and three mobile steering mirrors. The position of the mobile mirrors can be varied in real time using two stepper motors for each mobile mirror. In addition to controlling the injection angle, the position of the mobile mirrors also affects the polarisation of the injected wave. Accurate formulae to compute, in real time, the stepper motor positions required to obtain the desired beam injection angles have been derived. Formulae to determine the effect on the wave polarisation, of the actual mobile mirror positions have also been determined. These formulae have been verified by precise laser measurements and by comparison of power deposition calculations and experimental results. (authors)

Particle Transport in ECRH Plasmas of the TJ-II

International Nuclear Information System (INIS)

Vargas, V. I.; Lopez-Bruna, D.; Estrada, T.; Guasp, J.; Reynolds, J. M.; Velasco, J. L.; Herranz, J.

2007-01-01

We present a systematic study of particle transport in ECRH plasmas of TJ-II with different densities. The goal is to fi nd particle confinement time and electron diffusivity dependence with line-averaged density. The experimental information consists of electron temperature profiles, T e (Thomson Scattering TS) and electron density, n e , (TS and reflectometry) and measured puffing data in stationary discharges. The profile of the electron source, Se, was obtained by the 3D Monte-Carlo code EIRENE. The analysis of particle balance has been done by linking the results of the code EIRENE with the results of a model that reproduces ECRH plasmas in stationary conditions. In the range of densities studied (0.58 ≤n e > (10 1 9m - 3) ≤0.80) there are two regions of confinement separated by a threshold density, e > ∼0.65 10 1 9m - 3. Below this threshold density the particle confinement time is low, and vice versa. This is reflected in the effective diffusivity, D e , which in the range of validity of this study, 0.5 e are flat for ≥0,63(10 1 9m - 3). (Author) 35 refs

Multi-frequency electrical impedance tomography as a non-invasive tool to characterize and monitor crop root systems

Science.gov (United States)

Weigand, Maximilian; Kemna, Andreas

2017-02-01

A better understanding of root-soil interactions and associated processes is essential in achieving progress in crop breeding and management, prompting the need for high-resolution and non-destructive characterization methods. To date, such methods are still lacking or restricted by technical constraints, in particular the charactization and monitoring of root growth and function in the field. A promising technique in this respect is electrical impedance tomography (EIT), which utilizes low-frequency (response in alternating electric-current fields due to electrical double layers which form at cell membranes. This double layer is directly related to the electrical surface properties of the membrane, which in turn are influenced by nutrient dynamics (fluxes and concentrations on both sides of the membranes). Therefore, it can be assumed that the electrical polarization properties of roots are inherently related to ion uptake and translocation processes in the root systems. We hereby propose broadband (mHz to hundreds of Hz) multi-frequency EIT as a non-invasive methodological approach for the monitoring and physiological, i.e., functional, characterization of crop root systems. The approach combines the spatial-resolution capability of an imaging method with the diagnostic potential of electrical-impedance spectroscopy. The capability of multi-frequency EIT to characterize and monitor crop root systems was investigated in a rhizotron laboratory experiment, in which the root system of oilseed plants was monitored in a water-filled rhizotron, that is, in a nutrient-deprived environment. We found a low-frequency polarization response of the root system, which enabled the successful delineation of its spatial extension. The magnitude of the overall polarization response decreased along with the physiological decay of the root system due to the stress situation. Spectral polarization parameters, as derived from a pixel-based Debye decomposition analysis of the multi-frequency

Description of the Fokker-Plank code used to model ECRH of the Constance 2 plasma

International Nuclear Information System (INIS)

Mauel, M.E.

1982-01-01

The time-dependent Fokker-Plank code which is used to model the development of the electron velocity distribution during ECRH of the Constance 2 mirror-confined plasma is described in this report. The ECRH is modeled by the bounce-averaged quasilinear theory derived by Mauel. The effect of collisions are found by taking the appropriate gradients of the Rosenbluth potentials, and the electron distribution is advanced in time by using a modified alternating direction implicit (ADI) technique as explained by Killeen and Marx. The program was written in LISP to be run in the MACSYMA environment of the MACSYMA Consortium's PDP-10 computer

Multi-pulse frequency shifted (MPFS) multiple access modulation for ultra wideband

Science.gov (United States)

Nekoogar, Faranak [San Ramon, CA; Dowla, Farid U [Castro Valley, CA

2012-01-24

The multi-pulse frequency shifted technique uses mutually orthogonal short duration pulses o transmit and receive information in a UWB multiuser communication system. The multiuser system uses the same pulse shape with different frequencies for the reference and data for each user. Different users have a different pulse shape (mutually orthogonal to each other) and different transmit and reference frequencies. At the receiver, the reference pulse is frequency shifted to match the data pulse and a correlation scheme followed by a hard decision block detects the data.

Operations space diagram for ECRH and ECCD

International Nuclear Information System (INIS)

Bindslev, Henrik

2004-01-01

A Clemmov-Mullaly-Allis (CMA) type diagram, the ECW-CMA diagram, for representing the operational possibilities of electron cyclotron heating and current drive (ECRH/ECCD) systems for fusion plasmas is presented. In this diagram, with normalized density and normalized magnetic field coordinates, the parameter range in which it is possible to achieve a given task (e.g. O-mode current drive for stabilizing a neoclassical tearing mode) appears as a region. With also the Greenwald density limit shown, this diagram condenses the information on operational possibilities, facilitating the overview required at the design phase. At the operations phase it may also prove useful in setting up experimental scenarios by showing operational possibilities, avoiding the need for survey type ray-tracing at the initial planning stages. The diagram may also serve the purpose of communicating operational possibilities to non-experts. JET and ITER like plasmas are used, but the method is generic. (author)

Experimental evidence and theory for the interaction of superthermal electrons with the MHD modes during ECRH

International Nuclear Information System (INIS)

Lazaros, Avrilios

2000-01-01

The interaction of ECRH with the m/n=2/1 tearing mode, which was observed in toroidal plasmas, is attributed to the superthermal electrons which are produced on the EC resonance by the ECRH. Superthermal electrons diffusing across the q=2 surface, exchange power with the m/n=2/1 MHD mode which is either suppressed or enhanced. When the EC resonance is outside the rational surface, the mode is always suppressed. When the EC resonance is inside the rational surface, modes with large amplitude are enhanced while modes with small amplitude are suppressed. (author)

Adaptive control strategy for ECRH negative high-voltage power supply based on CMAC neural network

International Nuclear Information System (INIS)

Luo Xiaoping; Du Pengying; Du Shaowu

2011-01-01

In order to solve the problem that the negative high-voltage power supply in an electron cyclotron resonance heating (ECRH) system can not satisfy the requirements because of the nonlinearity and sensitivity, the direct inverse model control strategy was proposed by using cerebellar model articulation controller(CMAC) for better control, and experiments were carried out to study the system performances with CMAC tracing dynamic signals. The results show that this strategy is strong in self-learning and self-adaptation and easy to be realized. (authors)

An Adaptive Model Predictive Load Frequency Control Method for Multi-Area Interconnected Power Systems with Photovoltaic Generations

Directory of Open Access Journals (Sweden)

Guo-Qiang Zeng

2017-11-01

Full Text Available As the penetration level of renewable distributed generations such as wind turbine generator and photovoltaic stations increases, the load frequency control issue of a multi-area interconnected power system becomes more challenging. This paper presents an adaptive model predictive load frequency control method for a multi-area interconnected power system with photovoltaic generation by considering some nonlinear features such as a dead band for governor and generation rate constraint for steam turbine. The dynamic characteristic of this system is formulated as a discrete-time state space model firstly. Then, the predictive dynamic model is obtained by introducing an expanded state vector, and rolling optimization of control signal is implemented based on a cost function by minimizing the weighted sum of square predicted errors and square future control values. The simulation results on a typical two-area power system consisting of photovoltaic and thermal generator have demonstrated the superiority of the proposed model predictive control method to these state-of-the-art control techniques such as firefly algorithm, genetic algorithm, and population extremal optimization-based proportional-integral control methods in cases of normal conditions, load disturbance and parameters uncertainty.

Design status of the ITER ECRH upper launcher mm-wave system

Energy Technology Data Exchange (ETDEWEB)

Landis, J.-D. [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), Association Euratom-Confederation Suisse, 1015 Lausanne (Switzerland)], E-mail: jean-daniel.landis@epfl.ch; Chavan, R.; Bertizzolo, R.; Collazos, A.; Dolizy, F.; Felici, F.; Sanchez, F. [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), Association Euratom-Confederation Suisse, 1015 Lausanne (Switzerland); Henderson, M. [ITER, Organization, Cadarache Centre, Saint Paul Lez Durance (France)

2009-06-15

The purpose of the ITER electron cyclotron resonance heating (ECRH) upper launcher (UL), or antennae will be to provide localised current drive by accurately directing mm-wave beams up to 2MW, out of the four allocated upper port plugs, at chosen rational magnetic flux surfaces in order to stabilise neoclassical tearing modes (NTMs). This paper will present an overview of the UL, with emphasis on the mm-wave components. The mm-wave layout includes corrugated waveguide sections and a quasi-optical path with both focusing mirrors and plane steering mirrors. One of the essential components of the UL is the Steering Mechanism Assembly (SMA), providing variable poloidal injection angles fulfilling high deposition accuracy requirements at the plasma location. The Actuator principle and rotor bearings are frictionless and backlash free, avoiding tribological difficulties such as stickslip and seizure. The underlying working principle is the use of mechanically compliant structures. Validation and proof testing of the steering principle is achieved with an uncooled first prototype demonstrator. A second prototype is currently being manufactured, comprising the functionalities needed for the ITER compatible system such as water cooling and high power mm-wave compatibility. In order to perform the fatigue tests of the actuator bellows, a test facility has been built, under ITER-like vacuum and temperature working conditions. Results of the cyclic fatigue tests are compared to the various manufacturer standards and codes, combining stress and strain controlled material fatigue properties.

ECRH-assisted plasma start-up with toroidally inclined launch: multi-machine comparison and perspectives for ITER

International Nuclear Information System (INIS)

Stober, J.; Hobirk, J.; Lunt, T.; Jackson, G.L.; Hyatt, A.W.; Luce, T.; Ascasibar, E.; Cappa, A.; Bae, Y.-S.; Joung, M.; Bucalossi, J.; Casper, T.; Gribov, Y.; Cho, M.-H.; Jeong, J.-H.; Namkung, W.; Park, S.-I.; Granucci, G.; Hanada, K.; Ide, S.

2011-01-01

Electron cyclotron resonance heating (ECRH)-assisted plasma breakdown is foreseen with full and half magnetic field in ITER. As reported earlier, the corresponding O1- and X2-schemes have been successfully used to assist pre-ionization and breakdown in present-day devices. This contribution reports on common experiments studying the effect of toroidal inclination of the ECR beam, which is ≥20 0 in ITER. All devices could demonstrate successful breakdown assistance for this case also, although in some experiments the necessary power was almost a factor of 2 higher compared with perpendicular launch. Differences between the devices with regard to the required power and vertical field are discussed and analysed. In contrast to most of these experiments, ITER will build up loop voltage prior to the formation of the field null due to the strong shielding by the vessel. Possible consequences of this difference are discussed.

Evaluation of cephalogram using multi-objective frequency processing

Energy Technology Data Exchange (ETDEWEB)

Hagiwara, Sakae; Takizawa, Tsutomu; Osako, Miho; Kaneda, Takashi; Kasai, Kazutaka [Nihon Univ., Chiba (Japan). School of Dentistry at Matsudo

2002-12-01

A diagnosis with cephalogram is important for orthodontic treatment. Recently, computed radiography (CR) has been performed to the cephalogram. However, evaluation of multi-objective frequency processing (MFP) for cephalograms has been received little attention. The purpose of this study was to evaluate the cephalogram using MFP CR. At first, 450 lateral cephalograms were made, from 50 orthodontic patients, with 9 possible spatial frequency parameter combinations and a contrast scale held fixed in images processing. For each film, the clarity of radiographic images were estimated and scored with respect to landmark identification (total 26 points, 20 points of hard tissue and 6 points of soft tissue). A specific combination of spatial frequency scales (multi-frequency balance types (MRB) F-type, multi-frequency enhancement (MRE) 8) was proved to be adequate to achieve the optimal image quality in the cephalogram. (author)

Evaluation of cephalogram using multi-objective frequency processing

International Nuclear Information System (INIS)

Hagiwara, Sakae; Takizawa, Tsutomu; Osako, Miho; Kaneda, Takashi; Kasai, Kazutaka

2002-01-01

A diagnosis with cephalogram is important for orthodontic treatment. Recently, computed radiography (CR) has been performed to the cephalogram. However, evaluation of multi-objective frequency processing (MFP) for cephalograms has been received little attention. The purpose of this study was to evaluate the cephalogram using MFP CR. At first, 450 lateral cephalograms were made, from 50 orthodontic patients, with 9 possible spatial frequency parameter combinations and a contrast scale held fixed in images processing. For each film, the clarity of radiographic images were estimated and scored with respect to landmark identification (total 26 points, 20 points of hard tissue and 6 points of soft tissue). A specific combination of spatial frequency scales (multi-frequency balance types (MRB) F-type, multi-frequency enhancement (MRE) 8) was proved to be adequate to achieve the optimal image quality in the cephalogram. (author)

Robust and efficient multi-frequency temporal phase unwrapping: optimal fringe frequency and pattern sequence selection.

Science.gov (United States)

Zhang, Minliang; Chen, Qian; Tao, Tianyang; Feng, Shijie; Hu, Yan; Li, Hui; Zuo, Chao

2017-08-21

Temporal phase unwrapping (TPU) is an essential algorithm in fringe projection profilometry (FPP), especially when measuring complex objects with discontinuities and isolated surfaces. Among others, the multi-frequency TPU has been proven to be the most reliable algorithm in the presence of noise. For a practical FPP system, in order to achieve an accurate, efficient, and reliable measurement, one needs to make wise choices about three key experimental parameters: the highest fringe frequency, the phase-shifting steps, and the fringe pattern sequence. However, there was very little research on how to optimize these parameters quantitatively, especially considering all three aspects from a theoretical and analytical perspective simultaneously. In this work, we propose a new scheme to determine simultaneously the optimal fringe frequency, phase-shifting steps and pattern sequence under multi-frequency TPU, robustly achieving high accuracy measurement by a minimum number of fringe frames. Firstly, noise models regarding phase-shifting algorithms as well as 3-D coordinates are established under a projector defocusing condition, which leads to the optimal highest fringe frequency for a FPP system. Then, a new concept termed frequency-to-frame ratio (FFR) that evaluates the magnitude of the contribution of each frame for TPU is defined, on which an optimal phase-shifting combination scheme is proposed. Finally, a judgment criterion is established, which can be used to judge whether the ratio between adjacent fringe frequencies is conducive to stably and efficiently unwrapping the phase. The proposed method provides a simple and effective theoretical framework to improve the accuracy, efficiency, and robustness of a practical FPP system in actual measurement conditions. The correctness of the derived models as well as the validity of the proposed schemes have been verified through extensive simulations and experiments. Based on a normal monocular 3-D FPP hardware system

Experimental Electron Heat Diffusion in TJ-II ECRH Plasmas

Energy Technology Data Exchange (ETDEWEB)

Vargas, V.I.; Lopez-Bruna, D.; Herranz, J.; Castejon, F.

2006-07-01

Interpretative transport has been used to revisit the global scalings of TJ-II ECRH plasmas from a local perspective. Density, rotational transform and ERCH power scans were analysed based upon Thomson Scattering data (electron density and temperature) in steady state discharges. A simple formula to obtain the thermal conductivity, assuming pure diffusion and negligible convective heat fluxes was used in a set of 161 discharges. All the analysis was performed with the ASTRA transport shell. The density scan indicates that inside n=0,4 there is no significant change of e with density in the range studied (0.4 (1019m-3) 1.0), while in 0,5 <0,8 approximately, e decreases with density. In the rotational transform scan it is found that the values of e when a low order rational of the rotational transform is present locally seem to be smaller for the corresponding range, although it is apparent a general beneficial effect of the corresponding change in magnetic structure. Finally, in the ECRH power scan, e is found to have an overall increment in 0,2

Experimental Electron Heat Diffusion in TJ-II ECRH Plasmas

International Nuclear Information System (INIS)

Vargas, V.I.; Lopez-Bruna, D.; Herranz, J.; Castejon, F.

2006-01-01

Interpretative transport has been used to revisit the global scalings of TJ-II ECRH plasmas from a local perspective. Density, rotational transform and ERCH power scans were analysed based upon Thomson Scattering data (electron density and temperature) in steady state discharges. A simple formula to obtain the thermal conductivity, assuming pure diffusion and negligible convective heat fluxes was used in a set of 161 discharges. All the analysis was performed with the ASTRA transport shell. The density scan indicates that inside n=0,4 there is no significant change of e with density in the range studied (0.4 (1019m-3) 1.0), while in 0,5 <0,8 approximately, e decreases with density. In the rotational transform scan it is found that the values of e when a low order rational of the rotational transform is present locally seem to be smaller for the corresponding range, although it is apparent a general beneficial effect of the corresponding change in magnetic structure. Finally, in the ECRH power scan, e is found to have an overall increment in 0,2< n0,6 when QECH increases from 200 to 400 kW, although it is less significant in the density gradient region (n 0,7). (Author) 22 refs

The calculation and simulation of the ECRH HV power supply for the HL-2A tokamak

International Nuclear Information System (INIS)

Mao Xiaohui; Li Qing; Xuan Weimin; Yao Lieying

2006-01-01

In order to satisfy the requirement of ECRH, the ECRH HV power supply (ECHV-HVPS) on the base of high voltage pulse modulation has been designed. The filter inductance in the ECHV-HVPS is much smaller than the voltage regulation power supply. Modulations are adopted in the power supply, so the short time of the leading edge and lagging edge of the pulse is achieved. The main circuit of the ECHV-HVPS is showed. The equivalent resistance and the transient response of the PS are calculated and analyzed using MATLAB, and experiment results are given. (authors)

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.

Development of multi-frequency ESR system for high-pressure measurements up to 2.5 GPa

Science.gov (United States)

Sakurai, T.; Fujimoto, K.; Matsui, R.; Kawasaki, K.; Okubo, S.; Ohta, H.; Matsubayashi, K.; Uwatoko, Y.; Tanaka, H.

2015-10-01

A new piston-cylinder pressure cell for electron spin resonance (ESR) has been developed. The pressure cell consists of a double-layer hybrid-type cylinder with internal components made of the ZrO2-based ceramics. It can generate a pressure of 2 GPa repeatedly and reaches a maximum pressure of around 2.5 GPa. A high-pressure ESR system using a cryogen-free superconducting magnet up 10 T has also been developed for this hybrid-type pressure cell. The frequency region is from 50 GHz to 400 GHz. This is the first time a pressure above 2 GPa has been achieved in multi-frequency ESR system using a piston-cylinder pressure cell. We demonstrate its potential by showing the results of the high-pressure ESR of the S = 1 system with the single ion anisotropy NiSnCl6 · 6H2O and the S = 1 / 2 quantum spin system CsCuCl3. We performed ESR measurements of these systems above 2 GPa successfully.

Feedback control of tearing modes through ECRH with launcher mirror steering and power modulation using a line-of-sight ECE diagnostic

NARCIS (Netherlands)

Hennen, B.A.; Westerhof, E.; Nuij, P.W.J.M.; Ayten, B.; Baar, de M.R.; Bongers, W.A.; Bürger, A.; Lazzari, De D.; Oosterbeek, J.W.; Thoen, D.J.; Steinbuch, M.

2010-01-01

A demonstration of real-time feedback control for autonomous tracking and stabilization of m/n = 2/1 tearing modes in a tokamak using Electron Cyclotron Resonance Heating and Current Drive (ECRH/ECCD) is reported. The prototype system on TEXTOR combines in the same sight-line an Electron Cyclotron

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

Science.gov (United States)

Andersen, Christian Kraglund; Mølmer, Klaus

2015-03-01

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

Role of ECRH in potential formation for tandem mirrors

International Nuclear Information System (INIS)

Rognlien, T.D.; Matsuda, Y.; Stewart, J.J.

1985-01-01

The axial ion plugging potential in a tandem mirror is produced by electron cyclotron resonance heating (ECRH) applied at two locations in the end mirror cell. A second harmonic (ω = 2ω/sub c/) resonance is used near the midplane to generate hot electrons which yield an electron potential barrier between center cell electrons and electrons outboard of the end cell midplane. The latter group of electrons is then heated at the fundamental resonance (ω = ω/sub c/) on the outboard side of the magnetic well which drives an ion confining potential. Fokker-Planck and Monte Carlo calculations show that such a configuration is achievable, and the scaling obeys a rather simple set of equations. Another aspect of this configuration is the experimental observation that the fundamental heating drives the overall potential of the device relative to the wall to approx. 1 kV. An analytic model predicts this behavior for very strong ECRH. Results are given a numerical study of electron confinement in a mirror cell owing to fundamental heating as the level of the rf electric field, E/sub rf/, is increased. For the second part of the paper, we show that moderate levels of uniformly distributed rf fields, called cavity fields, can result in very hot (>250 keV) tails in the electron distribution as seen in the TMX-U experiment

Resonant-frequency discharge in a multi-cell radio frequency cavity

International Nuclear Information System (INIS)

Popović, S.; Upadhyay, J.; Nikolić, M.; Vušković, L.; Mammosser, J.

2014-01-01

We are reporting experimental results on a microwave discharge operating at resonant frequency in a multi-cell radio frequency (RF) accelerator cavity. Although the discharge operated at room temperature, the setup was constructed so that it could be used for plasma generation and processing in fully assembled active superconducting radio-frequency cryo-module. This discharge offers a mechanism for removal of a variety of contaminants, organic or oxide layers, and residual particulates from the interior surface of RF cavities through the interaction of plasma-generated radicals with the cavity walls. We describe resonant RF breakdown conditions and address the issues related to resonant detuning due to sustained multi-cell cavity plasma. We have determined breakdown conditions in the cavity, which was acting as a plasma vessel with distorted cylindrical geometry. We discuss the spectroscopic data taken during plasma removal of contaminants and use them to evaluate plasma parameters, characterize the process, and estimate the volatile contaminant product removal

Resonant-frequency discharge in a multi-cell radio frequency cavity

Energy Technology Data Exchange (ETDEWEB)

Popovic, S; Upadhyay, J; Mammosser, J; Nikolic, M; Vuskovic, L

2014-11-07

We are reporting experimental results on microwave discharge operating at resonant frequency in a multi-cell radio frequency (RF) accelerator cavity. Although the discharge operated at room temperature, the setup was constructed so that it could be used for plasma generation and processing in fully assembled active superconducting radio-frequency (SRF) cryomodule (in situ operation). This discharge offers an efficient mechanism for removal of a variety of contaminants, organic or oxide layers, and residual particulates from the interior surface of RF cavities through the interaction of plasma-generated radicals with the cavity walls. We describe resonant RF breakdown conditions and address the problems related to generation and sustaining the multi-cell cavity plasma, which are breakdown and resonant detuning. We have determined breakdown conditions in the cavity, which was acting as a plasma vessel with distorted cylindrical geometry. We discuss the spectroscopic data taken during plasma removal of contaminants and use them to evaluate plasma parameters, characterize the process, and estimate the volatile contaminant product removal.

Frequency Selection for Multi-frequency Acoustic Measurement of Suspended Sediment

Science.gov (United States)

Chen, X.; HO, H.; Fu, X.

2017-12-01

Multi-frequency acoustic measurement of suspended sediment has found successful applications in marine and fluvial environments. Difficult challenges remain in regard to improving its effectiveness and efficiency when applied to high concentrations and wide size distributions in rivers. We performed a multi-frequency acoustic scattering experiment in a cylindrical tank with a suspension of natural sands. The sands range from 50 to 600 μm in diameter with a lognormal size distribution. The bulk concentration of suspended sediment varied from 1.0 to 12.0 g/L. We found that the commonly used linear relationship between the intensity of acoustic backscatter and suspended sediment concentration holds only at sufficiently low concentrations, for instance below 3.0 g/L. It fails at a critical value of concentration that depends on measurement frequency and the distance between the transducer and the target point. Instead, an exponential relationship was found to work satisfactorily throughout the entire range of concentration. The coefficient and exponent of the exponential function changed, however, with the measuring frequency and distance. Considering the increased complexity of inverting the concentration values when an exponential relationship prevails, we further analyzed the relationship between measurement error and measuring frequency. It was also found that the inversion error may be effectively controlled within 5% if the frequency is properly set. Compared with concentration, grain size was found to heavily affect the selection of optimum frequency. A regression relationship for optimum frequency versus grain size was developed based on the experimental results.

MULTI-TEMPORAL AND MULTI-SENSOR IMAGE MATCHING BASED ON LOCAL FREQUENCY INFORMATION

Directory of Open Access Journals (Sweden)

X. Liu

2012-08-01

Full Text Available Image Matching is often one of the first tasks in many Photogrammetry and Remote Sensing applications. This paper presents an efficient approach to automated multi-temporal and multi-sensor image matching based on local frequency information. Two new independent image representations, Local Average Phase (LAP and Local Weighted Amplitude (LWA, are presented to emphasize the common scene information, while suppressing the non-common illumination and sensor-dependent information. In order to get the two representations, local frequency information is firstly obtained from Log-Gabor wavelet transformation, which is similar to that of the human visual system; then the outputs of odd and even symmetric filters are used to construct the LAP and LWA. The LAP and LWA emphasize on the phase and amplitude information respectively. As these two representations are both derivative-free and threshold-free, they are robust to noise and can keep as much of the image details as possible. A new Compositional Similarity Measure (CSM is also presented to combine the LAP and LWA with the same weight for measuring the similarity of multi-temporal and multi-sensor images. The CSM can make the LAP and LWA compensate for each other and can make full use of the amplitude and phase of local frequency information. In many image matching applications, the template is usually selected without consideration of its matching robustness and accuracy. In order to overcome this problem, a local best matching point detection is presented to detect the best matching template. In the detection method, we employ self-similarity analysis to identify the template with the highest matching robustness and accuracy. Experimental results using some real images and simulation images demonstrate that the presented approach is effective for matching image pairs with significant scene and illumination changes and that it has advantages over other state-of-the-art approaches, which include: the

Experimental investigation of the ECRH stray radiation during the start-up phase in Wendelstein 7-X

Science.gov (United States)

Moseev, Dmitry; Laqua, Heinrich; Marsen, Stefan; Stange, Torsten; Braune, Harald; Erckmann, Volker; Gellert, Florian; Oosterbeek, Johann Wilhelm; Wenzel, Uwe

2017-07-01

Electron cyclotron resonance heating (ECRH) is the main heating mechanism in the Wendelstein 7-X stellarator (W7-X). W7-X is equipped with five absolutely calibrated sniffer probes that are installed in each of the five modules of the device. The sniffer probes monitor energy flux of unabsorbed ECRH radiation in the device and interlocks are fed with the sniffer probe signals. The stray radiation level in the device changes significantly during the start-up phase: plasma is a strong microwave absorber and during its formation the stray radiation level in sniffer probes reduces by more than 95%. In this paper, we discuss the influence of neutral gas pressure and gyrotron power on plasma breakdown processes.

Heavy ion beam probe investigations of plasma potential in ECRH and NBI in the TJ-II stellarator

International Nuclear Information System (INIS)

Melnikov, A.V.; Eliseev, L.; Perfilov, S.V.; Chmyga, A.A.; Dreval, N.; Khrebtov, S.M.; Komarov, A.D.; Kozachok, A.S.; Krupnik, L.; Alonso, A.; Pablos, J.L. de; Cappa, A.; Fernandez, A.; Fuentes, C.; Hidalgo, C.; Liniers, M.; Pedrosa, M.A.

2005-01-01

Direct measurements of electric potential and its fluctuations are of a primary importance in magnetic confinement systems. The Heavy Ion Beam Probe (HIBP) diagnostic is used in TJ-2 stellarator to study directly plasma electric potential profiles with spatial (up to 1cm) and temporal (up to 10 ∝s) resolution. The singly charged heavy ions Cs + with energies up to 125 keV are used to probe the plasma column from the edge to the core. Both ECRH and NBI heated plasmas (P ECRH = 200 - 400kW, P NBI = 400kW, E NBI = 28 kV) were studied. The significant improvement in the HIBP beam control system and the acquisition electronics leads us to increase the possibilities of the diagnostic. The most crucial one is the extension of the signal dynamic range, which allows us to have the reliable profiles from the plasma center to the plasma edge both in the high and low field side regions. Low density ECRH (n = 0.5-1.1.10 13 cm -3 ) plasmas in TJ-2 are characterised by core positive plasma potential of order of 500 - 1000 V and positive electric fields up to 50 V/cm. Edge radial electric fields remain positive at low densities and became negative at the threshold density that depends of plasma configuration. NBI plasmas are characterized by negative electric potential in the full plasma column and negative radial electric fields (in the range of 10 - 40 V/cm). The density rise during the NBI phase is accompanied by the decay of core plasma potential. When density is getting the level of n ∼ 2.0.10 13 cm -3 , the potential stops its evolution and remains constant. The evolution of plasma potential near density limit is under investigation. These observations, reported in different magnetic configurations, show the clear link between plasma potential and plasma density. (author)

Tightly-Coupled Integration of Multi-GNSS Single-Frequency RTK and MEMS-IMU for Enhanced Positioning Performance.

Science.gov (United States)

Li, Tuan; Zhang, Hongping; Niu, Xiaoji; Gao, Zhouzheng

2017-10-27

Dual-frequency Global Positioning System (GPS) Real-time Kinematics (RTK) has been proven in the past few years to be a reliable and efficient technique to obtain high accuracy positioning. However, there are still challenges for GPS single-frequency RTK, such as low reliability and ambiguity resolution (AR) success rate, especially in kinematic environments. Recently, multi-Global Navigation Satellite System (multi-GNSS) has been applied to enhance the RTK performance in terms of availability and reliability of AR. In order to further enhance the multi-GNSS single-frequency RTK performance in terms of reliability, continuity and accuracy, a low-cost micro-electro-mechanical system (MEMS) inertial measurement unit (IMU) is adopted in this contribution. We tightly integrate the single-frequency GPS/BeiDou/GLONASS and MEMS-IMU through the extended Kalman filter (EKF), which directly fuses the ambiguity-fixed double-differenced (DD) carrier phase observables and IMU data. A field vehicular test was carried out to evaluate the impacts of the multi-GNSS and IMU on the AR and positioning performance in different system configurations. Test results indicate that the empirical success rate of single-epoch AR for the tightly-coupled single-frequency multi-GNSS RTK/INS integration is over 99% even at an elevation cut-off angle of 40°, and the corresponding position time series is much more stable in comparison with the GPS solution. Besides, GNSS outage simulations show that continuous positioning with certain accuracy is possible due to the INS bridging capability when GNSS positioning is not available.

HIGHER MODE FREQUENCY EFFECTS ON RESONANCE IN MACHINERY, STRUCTURES, AND PIPE SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

Leishear, R.

2010-05-02

The complexities of resonance in multi-degree of freedom systems (multi-DOF) may be clarified using graphic presentations. Multi-DOF systems represent actual systems, such as beams or springs, where multiple, higher order, natural frequencies occur. Resonance occurs when a cyclic load is applied to a structure, and the frequency of the applied load equals one of the natural frequencies. Both equations and graphic presentations are available in the literature for single degree of freedom (SDOF) systems, which describe the response of spring-mass-damper systems to harmonically applied, or cyclic, loads. Loads may be forces, moments, or forced displacements applied to one end of a structure. Multi-DOF systems are typically described only by equations in the literature, and while equations certainly permit a case by case analysis for specific conditions, graphs provide an overall comprehension not gleaned from single equations. In fact, this collection of graphed equations provides novel results, which describe the interactions between multiple natural frequencies, as well as a comprehensive description of increased vibrations near resonance.

Multi-Band Multi-Tone Tunable Millimeter-Wave Frequency Synthesizer For Satellite Beacon Transmitter

Science.gov (United States)

Simons, Rainee N.; Wintucky, Edwin G.

2016-01-01

This paper presents the design and test results of a multi-band multi-tone tunable millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a satellite beacon transmitter for radio wave propagation studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). In addition, the architecture for a compact beacon transmitter, which includes the multi-tone synthesizer, polarizer, horn antenna, and power/control electronics, has been investigated for a notional space-to-ground radio wave propagation experiment payload on a small satellite. The above studies would enable the design of robust high throughput multi-Gbps data rate future space-to-ground satellite communication links.

Plasma dynamics with second and third-harmonic ECRH and access to quasi-stationary ELM-free H-mode on TCV

International Nuclear Information System (INIS)

Porte, L.; Coda, S.; Alberti, S.; Arnoux, G.; Blanchard, P.; Bortolon, A.; Fasoli, A.; Goodman, T.P.; Klimanov, Y.; Martin, Y.; Maslov, M.; Scarabosio, A.; Weisen, H.

2007-01-01

Intense electron cyclotron resonance heating (ECRH) and electron cyclotron current drive (ECCD) are employed on the Tokamak a Configuration Variable (TCV) both in second- and third-harmonic X-mode (X2 and X3). The plasma behaviour under such conditions is driven largely by the electron dynamics, motivating extensive studies of the heating and relaxation phenomena governing both the thermal and suprathermal electron populations. In particular, the dynamics of suprathermal electrons are intimately tied to the physics of X2 ECCD. ECRH is also a useful tool for manipulating the electron distribution function in both physical and velocity space. Fundamental studies of the energetic electron dynamics have been performed using periodic, low-duty-cycle bursts of ECRH, with negligible average power injection, and with electron cyclotron emission (ECE). The characteristic times of the dynamical evolution are clearly revealed. Suprathermal electrons have also been shown to affect the absorption of X3 radiation. Thermal electrons play a crucial role in high density plasmas where indirect ion heating can be achieved through ion-electron collisions. In recent experiments ∼ 1.35 MW of vertically launched X3 ECRH was coupled to a diverted ELMy H-mode plasma. In cases where ≥ 1.1 MW of ECRH power was coupled, the discharge was able to transition into a quasi-stationary ELM-free H-mode regime. These H-modes operated at β N ∼ 2, n-bar e /n G approx. 0.25 and had high energy confinement, H IPB98(y,2) up to ∼ 1.6. Despite being purely electron heated and having no net particle source these discharges maintained a density peaking factor (n e,o /(n e ) ∼ 1.6). They also exhibited spontaneous toroidal momentum production in the co-current direction. The momentum production is due to a transport process as there is no external momentum input. This process supports little or no radial gradient of the toroidal velocity

A fast switch, combiner and narrow-band filter for high-power millimetre wave beams

Science.gov (United States)

Kasparek, W.; Petelin, M. I.; Shchegolkov, D. Yu; Erckmann, V.; Plaum, B.; Bruschi, A.; ECRH Groups at IPP Greifswald; Karlsruhe, FZK; Stuttgart, IPF

2008-05-01

A fast directional switch (FADIS) is described, which allows controlled switching of high-power microwaves between two outputs. A possible application could be synchronous stabilization of neoclassical tearing modes (NTMs). Generally, the device can be used to share the installed EC power between different types of launchers or different applications (e.g. in ITER, midplane/upper launcher). The switching is performed electronically without moving parts by a small frequency-shift keying of the gyrotron (some tens of megahertz), and a narrow-band diplexer. The device can be operated as a beam combiner also, which offers attractive transmission perspectives in multi-megawatt ECRH systems. In addition, these diplexers are useful for plasma diagnostic systems employing high-power sources due to their filter characteristics. The principle and the design of a four-port quasi-optical resonator diplexer is presented. Low-power measurements of switching contrast, mode purity and efficiency show good agreement with theory. Preliminary frequency modulation characteristics of gyrotrons are shown, and first results from high-power switching experiments using the ECRH system for W7-X are presented.

A fast switch, combiner and narrow-band filter for high-power millimetre wave beams

International Nuclear Information System (INIS)

Kasparek, W.; Plaum, B.; Petelin, M.I.; Shchegolkov, D.Yu; Erckmann, V.; Bruschi, A.

2008-01-01

A fast directional switch (FADIS) is described, which allows controlled switching of high-power microwaves between two outputs. A possible application could be synchronous stabilization of neoclassical tearing modes (NTMs). Generally, the device can be used to share the installed EC power between different types of launchers or different applications (e.g. in ITER, midplane/upper launcher). The switching is performed electronically without moving parts by a small frequency-shift keying of the gyrotron (some tens of megahertz), and a narrow-band diplexer. The device can be operated as a beam combiner also, which offers attractive transmission perspectives in multi-megawatt ECRH systems. In addition, these diplexers are useful for plasma diagnostic systems employing high-power sources due to their filter characteristics. The principle and the design of a four-port quasi-optical resonator diplexer is presented. Low-power measurements of switching contrast, mode purity and efficiency show good agreement with theory. Preliminary frequency modulation characteristics of gyrotrons are shown, and first results from high-power switching experiments using the ECRH system for W7-X are presented

Numerical investigation of the inertial cavitation threshold under multi-frequency ultrasound.

Science.gov (United States)

Suo, Dingjie; Govind, Bala; Zhang, Shengqi; Jing, Yun

2018-03-01

Through the introduction of multi-frequency sonication in High Intensity Focused Ultrasound (HIFU), enhancement of efficiency has been noted in several applications including thrombolysis, tissue ablation, sonochemistry, and sonoluminescence. One key experimental observation is that multi-frequency ultrasound can help lower the inertial cavitation threshold, thereby improving the power efficiency. However, this has not been well corroborated by the theory. In this paper, a numerical investigation on the inertial cavitation threshold of microbubbles (MBs) under multi-frequency ultrasound irradiation is conducted. The relationships between the cavitation threshold and MB size at various frequencies and in different media are investigated. The results of single-, dual and triple frequency sonication show reduced inertial cavitation thresholds by introducing additional frequencies which is consistent with previous experimental work. In addition, no significant difference is observed between dual frequency sonication with various frequency differences. This study, not only reaffirms the benefit of using multi-frequency ultrasound for various applications, but also provides a possible route for optimizing ultrasound excitations for initiating inertial cavitation. Copyright © 2017 Elsevier B.V. All rights reserved.

Evolution of the transport coefficients for the transient processes after ECRH switch-on/off in the T-10 tokamak

International Nuclear Information System (INIS)

Andreev, V.F.; Danilov, A.V.; Dnestrovskij, Yu.N.; Ossipenko, M.V.; Razumova, K.A.; Sushkov, A.V.

2005-01-01

A study of the transient processes after ECRH switch-on/off in the T-10 tokamak shows that an electron ITB appears near the q∼3/2 resonance surface in regimes with suppressed sawtooth oscillations. When the gradient of the electron temperature in the plasma centre after additional on-axis ECRH exceeds some critical value, the electron ITB is weakened and the heat flux spreads from the heating region to the plasma periphery practically instantly. This looks like a jump of the heat flux through the entire plasma region. Therefore, to describe the electron heat transport in a tokamak plasma after the ECRH switch-on/off, three different physical processes should be taken into account: a) the transient process of plasma heating inside the region bounded by the temporal electron ITB; b) the weakening of the electron ITB accompanied by the heat efflux to the plasma periphery during hundreds of microseconds; c) the consequent diffusive evolution of the electron temperature profile with the conservation of the relative electron temperature gradient ∇T/T. (author)

Nonlinear and self-consistent treatment of ECRH

Energy Technology Data Exchange (ETDEWEB)

Tsironis, C.; Vlahos, L.

2005-07-01

A self-consistent formulation for the nonlinear interaction of electromagnetic waves with relativistic magnetized electrons is applied for the description of the ECRH. In general, electron-cyclotron absorption is the result of resonances between the cyclotron harmonics and the Doppler-shifted waver frequency. The resonant interaction results to an intense wave-particle energy exchange and an electron acceleration, and for that reason it is widely applied in fusion experiments for plasma heating and current drive. The linear theory, for the wave absorption, as well as the quasilinear theory for the electron distribution function, are the most frequently-used tools for the study of wave-particle interactions. However, in many cases the validity of these theories is violated, namely cases where nonlinear effects, like, e. g. particle trapping in the wave field, are dominant in the particle phase-space. Our model consists of electrons streaming and gyrating in a tokamak plasma slab, which is finite in the directions perpendicular to the main magnetic field. The particles interact with an electromagnetic electron-cyclotron wave of the ordinary (O-) or the extraordinary (X-) mode. A set of nonlinear and relativistic equations is derived, which take into account the effects of the charged particle motions on the wave. These consist of the equations of motion for the plasma electrons in the slab, as well as the wave equation in terms of the vector potential. The effect of the electron motions on the temporal evolution of the wave is reflected in the current density source term. (Author)

Nonlinear and self-consistent treatment of ECRH

International Nuclear Information System (INIS)

Tsironis, C.; Vlahos, L.

2005-01-01

A self-consistent formulation for the nonlinear interaction of electromagnetic waves with relativistic magnetized electrons is applied for the description of the ECRH. In general, electron-cyclotron absorption is the result of resonances between the cyclotron harmonics and the Doppler-shifted waver frequency. The resonant interaction results to an intense wave-particle energy exchange and an electron acceleration, and for that reason it is widely applied in fusion experiments for plasma heating and current drive. The linear theory, for the wave absorption, as well as the quasilinear theory for the electron distribution function, are the most frequently-used tools for the study of wave-particle interactions. However, in many cases the validity of these theories is violated, namely cases where nonlinear effects, like, e. g. particle trapping in the wave field, are dominant in the particle phase-space. Our model consists of electrons streaming and gyrating in a tokamak plasma slab, which is finite in the directions perpendicular to the main magnetic field. The particles interact with an electromagnetic electron-cyclotron wave of the ordinary (O-) or the extraordinary (X-) mode. A set of nonlinear and relativistic equations is derived, which take into account the effects of the charged particle motions on the wave. These consist of the equations of motion for the plasma electrons in the slab, as well as the wave equation in terms of the vector potential. The effect of the electron motions on the temporal evolution of the wave is reflected in the current density source term. (Author)

ECRH and ECCD scenarios for W7-X

Directory of Open Access Journals (Sweden)

Laqua H.P.

2012-09-01

Full Text Available The main ECRH scenarios for the W7-X Stellarator are described. Both X2 (low and moderate densities and O2 scenarios (high density have been studied. Since O2 scenario cannot be realized without pre-heating, transition from X2 to O2 scenarios has been discussed. Due to a lack of Ohmic transformer, only ECCD is available for compensating the bootstrap current and for controlling the edge rotational transform value. The efficiency of ECCD for all main scenarios has been estimated. All simulations have been performed by a 1D transport code coupled self-consistently with ray-tracing code.

Conditioning of TJ-II Stellarator during the ECRH Plasmas Period; Acondicionamiento del Stellarator TJ-II durante la Etapa de Plasmas ECRH

Energy Technology Data Exchange (ETDEWEB)

Tafalla, D.; Tabares, F.L.

2001-07-01

The TJ-II stellarator has been conditioned by glow discharge (GD) during the first campaigns of operation, working only with ECR heating and all metal walls. The application of a He GD during the overnight period before the operation has been required in order to obtain reproducible discharges. However, the density control of the ECRH discharges was not possible because of the He implanted on the wall during GS. An short Ar GD({<=}30 min) applied before the operation allows desorbes part of the implanted He. By applying this procedure (HeGD+ArGD), reproducible and density controlled plasmas have been achieved in H{sub 2} and He. (Author) 20 refs.

PM 2.5 and NO 2 assessment in 21 European study centres of ECRHS II: annual means and seasonal differences

Science.gov (United States)

Hazenkamp-von Arx, Marianne E.; Götschi, Thomas; Ackermann-Liebrich, Ursula; Bono, Roberto; Burney, Peter; Cyrys, Josef; Jarvis, Deborah; Lillienberg, Linnea; Luczynska, Christina; Maldonado, Jose A.; Jaén, Angeles; de Marco, Roberto; Mi, Yahong; Modig, Lars; Bayer-Oglesby, Lucy; Payo, Felix; Soon, Argo; Sunyer, Jordi; Villani, Simona; Weyler, Joost; Künzli, Nino

The follow-up of cohorts of adults from more than 20 European centres of the former ECRHS I (1989-1992) investigates long-term effects of exposure to ambient air pollution on respiratory health, in particular asthma and change of pulmonary function. Since PM 2.5 is not routinely monitored in Europe, we measured PM 2.5 concentrations in 21 participating centres to estimate 'background' exposure in these cities. Winter (November-February), summer (May-August) and annual mean (all months) values of PM 2.5 were determined from measuring periods between June 2000 and November 2001. Sampling was conducted for 7 days per month for a year. Annual and winter mean concentrations of PM 2.5 vary substantially being lowest in Iceland and highest in centres in Northern Italy. Annual mean concentrations ranged from 3.7 to 44.9 μg m -3, winter mean concentrations from 4.8 to 69.2 μg m -3, and summer mean concentrations from 3.3 to 23.1 μg m -3. Seasonal variability occurred but did not follow the same pattern across all centres. Therefore, ranking of centres varied from summer to winter. Simultaneously, NO 2 concentrations were measured using passive sampling tubes. Annual mean NO 2 concentrations range from 4.9 to 72.1 μg m -3 with similar seasonal variations across centres and constant ranking of centres between seasons. The correlation between annual NO 2 and PM 2.5 concentrations is fair (Spearman correlation coefficient rs=0.75), but when considered as monthly means the correlation is far less consistent and varies substantially between centres. The range of PM 2.5 mass concentrations obtained in ECRHS II is larger than in other current cohort studies on long-term effects of air pollution. This substantial variation in PM 2.5 exposure will improve statistical power in future multi-level health analyses and to some degree may compensate for the lack of information on within-city variability. Seasonal means may be used to indicate potential differences in the toxicity

Frequency division multiplexed multi-color fluorescence microscope system

Science.gov (United States)

Le, Vu Nam; Yang, Huai Dong; Zhang, Si Chun; Zhang, Xin Rong; Jin, Guo Fan

2017-10-01

Grayscale camera can only obtain gray scale image of object, while the multicolor imaging technology can obtain the color information to distinguish the sample structures which have the same shapes but in different colors. In fluorescence microscopy, the current method of multicolor imaging are flawed. Problem of these method is affecting the efficiency of fluorescence imaging, reducing the sampling rate of CCD etc. In this paper, we propose a novel multiple color fluorescence microscopy imaging method which based on the Frequency division multiplexing (FDM) technology, by modulating the excitation lights and demodulating the fluorescence signal in frequency domain. This method uses periodic functions with different frequency to modulate amplitude of each excitation lights, and then combine these beams for illumination in a fluorescence microscopy imaging system. The imaging system will detect a multicolor fluorescence image by a grayscale camera. During the data processing, the signal obtained by each pixel of the camera will be processed with discrete Fourier transform, decomposed by color in the frequency domain and then used inverse discrete Fourier transform. After using this process for signals from all of the pixels, monochrome images of each color on the image plane can be obtained and multicolor image is also acquired. Based on this method, this paper has constructed and set up a two-color fluorescence microscope system with two excitation wavelengths of 488 nm and 639 nm. By using this system to observe the linearly movement of two kinds of fluorescent microspheres, after the data processing, we obtain a two-color fluorescence dynamic video which is consistent with the original image. This experiment shows that the dynamic phenomenon of multicolor fluorescent biological samples can be generally observed by this method. Compared with the current methods, this method can obtain the image signals of each color at the same time, and the color video's frame

Non-contact multi-frequency magnetic induction spectroscopy system for industrial-scale bio-impedance measurement

International Nuclear Information System (INIS)

O'Toole, M D; Marsh, L A; Davidson, J L; Tan, Y M; Armitage, D W; Peyton, A J

2015-01-01

Biological tissues have a complex impedance, or bio-impedance, profile which changes with respect to frequency. This is caused by dispersion mechanisms which govern how the electromagnetic field interacts with the tissue at the cellular and molecular level. Measuring the bio-impedance spectra of a biological sample can potentially provide insight into the sample’s properties and its cellular structure. This has obvious applications in the medical, pharmaceutical and food-based industrial domains. However, measuring the bio-impedance spectra non-destructively and in a way which is practical at an industrial scale presents substantial challenges. The low conductivity of the sample requires a highly sensitive instrument, while the demands of industrial-scale operation require a fast high-throughput sensor of rugged design. In this paper, we describe a multi-frequency magnetic induction spectroscopy (MIS) system suitable for industrial-scale, non-contact, spectroscopic bio-impedance measurement over a bandwidth of 156 kHz–2.5 MHz. The system sensitivity and performance are investigated using calibration and known reference samples. It is shown to yield rapid and consistently sensitive results with good long-term stability. The system is then used to obtain conductivity spectra of a number of biological test samples, including yeast suspensions of varying concentration and a range of agricultural produce, such as apples, pears, nectarines, kiwis, potatoes, oranges and tomatoes. (paper)

Transmission lines and launching systems for ECRH on the garching stellarators W VIIa and W VII-AS

International Nuclear Information System (INIS)

Thumm, M.; Janzen, G.; Mueller, G.; Schueller, P.G.; Wilhelm, R.; Erckmann, V.

1983-01-01

The transmission lines and launching systems for non ohmic plasma production and heating by ECR-waves at 28 GHz (200 kW, 40 ms) and 70 GHz (200 kW, 100 ms) in the Garching Wendelstein Stellarator W VIIa and at 70 GHz (800 kW, cw) in the future Advanced Stellarator W VII-AS are described. The ECRH systems meet the requirements for neutral gas breakdown (R-wave), heating of a cold plasma (X-mode) and heating of a warm plasma (0-mode) in a combined way. Periodically modulated wall mode converters (sinusoidal m=0 radius modulation, a 0 =31.75 mm at 28 GHz, a 0 =13.9 mm at 70 GHz) convert the circular electric TE/sub on/ gyrotron output mode mixture (mainly TE 02 mode) into a pure TE 01 wave which is used for the long distance transmission in smooth overmoded waveguides (I.D. = 63.5 mm). At the converter inputs the phases between the TE/sub on/ modes are matched by phase shifters. The measured conversion efficiency for characteristic mode mixtures (TE 02 /TE 01 /TE 03 ) at 28 GHz is about 98 %. For the geometrical and electrical matching of different waveguide diameters waveguide tapers with approximate Tschebycheff mode-conversion responses are used

Multivariable predictive control considering time delay for load-frequency control in multi-area power systems

Directory of Open Access Journals (Sweden)

Daniar Sabah

2016-12-01

Full Text Available In this paper, a multivariable model based predictive control (MPC is proposed for the solution of load frequency control (LFC in a multi-area interconnected power system. The proposed controller is designed to consider time delay, generation rate constraint and multivariable nature of the LFC system, simultaneously. A new formulation of the MPC is presented to compensate time delay. The generation rate constraint is considered by employing a constrained MPC and economic allocation of the generation is further guaranteed by an innovative modification in the predictive control objective function. The effectiveness of proposed scheme is verified through time-based simulations on the standard 39-bus test system and the responses are then compared with the proportional-integral controller. The evaluation of the results reveals that the proposed control scheme offers satisfactory performance with fast responses.

Study on LOOP and SBO Frequency for Multi-Unit PSA

Energy Technology Data Exchange (ETDEWEB)

Jin, Kyung Ho; Heo, Gyun Young [Kyunghee University, Yongin (Korea, Republic of)

2016-05-15

In conventional single unit PSA, it was assumed that all accidents or events are independent and the risk of only one unit has been evaluated. In other words, the possibility that simultaneous events occur on multiple units was excluded because it was assumed that the probability of concurrent events were extremely low. After Fukushima accidents, however, it was found that external hazards such as tsunami may impact on multiple units; that means, for the sake of proper mitigation the risk of accidents in shared SSCs should be reevaluated. New risk metrics to improve conventional CDF (Core Damage frequency) based on reactor-year is needed to perform MUPSA (Multi-Unit Probabilistic Safety Assessment). IAEA suggested SCDF (Site CDF) as a risk metrics for MUPSA. The frequency based on reactor-year was converted to the frequency based on site-year. In addition, shared SSCs were modeled in single unit PSA as if those units have independent shared SSCs. Therefore, the risk of shared SSCs should be reevaluated. In this paper, the frequency of LOOP (Loss of Offsite Power), which is typically a multi-unit event, was evaluated and the frequency of SBO (Station Blackout) depending on LOOP frequency and emergency power systems such as EDG (Emergency Diesel Generator) and AAC (Alternate AC), that can mitigate SBO events, was modeled. This paper describes how to calculate LOOP and SBO frequency from the simple example for two-unit site with shared AAC. The events impacting on multiple units, which were excluded in conventional PSA, should be considered for MUPSA.

Orthogonal Multi-Carrier DS-CDMA with Frequency-Domain Equalization

Science.gov (United States)

Tanaka, Ken; Tomeba, Hiromichi; Adachi, Fumiyuki

Orthogonal multi-carrier direct sequence code division multiple access (orthogonal MC DS-CDMA) is a combination of orthogonal frequency division multiplexing (OFDM) and time-domain spreading, while multi-carrier code division multiple access (MC-CDMA) is a combination of OFDM and frequency-domain spreading. In MC-CDMA, a good bit error rate (BER) performance can be achieved by using frequency-domain equalization (FDE), since the frequency diversity gain is obtained. On the other hand, the conventional orthogonal MC DS-CDMA fails to achieve any frequency diversity gain. In this paper, we propose a new orthogonal MC DS-CDMA that can obtain the frequency diversity gain by applying FDE. The conditional BER analysis is presented. The theoretical average BER performance in a frequency-selective Rayleigh fading channel is evaluated by the Monte-Carlo numerical computation method using the derived conditional BER and is confirmed by computer simulation of the orthogonal MC DS-CDMA signal transmission.

Studies of the disruption prevention by ECRH at plasma current rise stage in limiter discharges/Possibility of an internal transport barrier producing under dominating electron transport in the T-10 tokamak

International Nuclear Information System (INIS)

Alikaev, V.V.; Borshegovskij, A.A.; Chistyakov, V.V.

2001-01-01

'Studies of the Disruption Prevention by ECRH at Plasma Current Rise Stage in Limiter Discharges' - Studies of disruption prevention by means of ECRH in T-10 at the plasma current rise phase in limiter discharges with circular plasma cross-section were performed. Reliable disruption prevention by ECRH at HF power (P HF ) min level equal to 20% of ohmic heating power P OH was demonstrated. m/n=2/1 mode MHD-activity developed before disruption (with characteristic time ∼ 120 ms) can be considered as disruption precursor and can be used in a feedback system. 'Possibility of an Internal Transport Barrier Producing under Dominating Electron Transport in the T-10 Tokamak' - The reversed shear experiments were carried out on T-10 at the HF power up to 1MW. The reversed shear in the core was produced by on-axis ECCD in direction opposite to the plasma current. There are no obvious signs of Internal Transport Barriers formation under condition when high-k turbulence determines the electron transport. (author)

FOM-Rijnhuizen contributions to IAEA technical committee meeting on ECE and ECRH, seventh joint workshop on ECE and ECRH (EC-7), Hefei, P.R. China, 8-11 May 1989

International Nuclear Information System (INIS)

1989-09-01

This report contains five contributions all being in INIS-scope, entitled respectivel: Measurements on Waveguide Components for ECRH on RTP; Electron Cyclotron Resonance heating on RTP; Electron Cyclotron Heating of High Density JET H-Mode Discharges; Electron Cyclotron Current Drive and m=2 Mode Stabilization in NET; A Double-heterodyne ECE Radiometer for the measurement of Small Temperature Fluctuations on RTP. (author). 37 refs.; 30 figs.; 5 tabs

Local effects of ECRH on argon transport at ASDEX upgrade

International Nuclear Information System (INIS)

Sertoli, Marco

2010-01-01

Future deuterium-tritium magnetically confined fusion power plants will most probably rely an high-Z Plasma Facing Components (PFCs) such as tungsten. This choice is determined by the necessity of low erosion of the first wall materials (to guarantee a long lifetime of the wall components) and by the need to avoid the too high tritium wall retention of typical carbon based PFCs. The experience gathered at the ASDEX Upgrade (AUG) tokamak has demonstrated the possibility of reliable and high performance plasma operation with a full tungsten-coated first wall. The observed accumulation of tungsten which can lead to excessive radiation losses is mitigated with the use of Electron Cyclotron Resonance Heating (ECRH). Although this impurity control method is routinely performed at AUG, the underlying physics principles are still not clear. This thesis aims an providing further knowledge an the effects of ECRH an the transport of impurities inside the core plasma. The transport of argon has been therefore investigated in-depth in purely ECR heated L-mode (low-confinement) discharges. Studies an impurity transport in centrally ECR heated nitrogen-seeded H-mode (high-confinement) discharges have also been performed. To this scope, a new crystal X-ray spectrometer of the Johann type has been installed an AUG for argon concentration and ion temperature measurements. New methods for the experimental determination of the total argon density through the integrated use of this diagnostic and of the Soft X-Ray (SXR) diode arrays have been developed. This gives the possibility of evaluating the full profiles of the argon transport coefficients from the linear flux-gradient dependency of local argon density. In comparison to classical χ 2 -minimization methods, the approach proposed here delivers transport coefficients intrinsically independent of the modelling of periodic relaxation mechanisms such as those Lied to sawtooth MHD (Magneto-Hydro-Dynamic) activity. Moreover, the good

Parametric assessments on hydrogenic species transport in CVD-diamond vacuum windows used in ITER ECRH

Energy Technology Data Exchange (ETDEWEB)

Moreno, C.; Sedano, L.A.; Fernandez, A. [EURATOM-CIEMAT Association, Madrid (Spain)

2007-07-01

Insulators used as H and CD and Diagnostic vacuum windows (VW) in ITER may become modified by surface intake and bulk transport of hydrogenic species. VW, operating under severe radiation levels, have a primary safety role as tritium confinement barriers. Ionizing radiation enhances the (H') uptake and release at surfaces and diffusion rates in the bulk. Radiation damage modifies the material's bulk trapped inventories by increasing steady state trapping centre concentrations. An experimental programme is ongoing at CIEMAT, to quantify radiation effects on H transport characteristics and also the possible impact on the VW. The reference material for ECRH VW is CVD diamond. As a parallel activity, parametric transport assessments are being made in order to obtain a wide evaluation of permeation fluxes, ranges, and soluted/trapped inventories in CVD diamond. Transport models have been developed based on extended capabilities of finite differences integrator tool TMAP7. Special attention is paid to radiation parameters defining inputs acting on transport magnitudes. These inputs have been analysed by using ionizing/damage radiation transport tools such as MCNPX/SRIM. VW operational scenarios are discussed with special attention being paid to the ITER design assumptions for the values of H-species source terms (neutrals and implanted) in the ECRH system. The available material transport database with and without radiation is discussed and taken as reference for this parametric exercise. Permeation fluxes through base materials are shown to be below DRG limits established for ITER. (orig.)

Experiments on electron temperature profile resilience in FTU tokamak with continuous and modulated ECRH

International Nuclear Information System (INIS)

Cirant, S.

2002-01-01

Experiments performed on FTU tokamak, aiming at validation of physics-based transport models of the electron temperature profile resilience, are presented. ECRH is used to probe transport features, both in steady-state and in response to perturbations, while ECCD and LHCD are used for current density profile shaping. Observed confinement behaviour shows agreement with a critical temperature gradient length modelling. Central, low gradient plasma is characterized by low stiffness and low electron thermal diffusivity. Strong stiffness and high conduction are found in the confinement region. Resilience is experimentally characterized by an index of the resistance of the profile to adapt its shape to localized ECRH, while the diffusivity and its low-high transition are measured both by power balance and heat pulse propagation analysis. A particular attention is given to the investigation of the transition layer between low-high diffusivity and low-high stiffness regions. A dependence of LTc on magnetic shear, similar to what found in Tore Supra, and consistent with ETG based anomalous transport, is found. (author)

Multi-stage fuzzy load frequency control using PSO

International Nuclear Information System (INIS)

Shayeghi, H.; Jalili, A.; Shayanfar, H.A.

2008-01-01

In this paper, a particle swarm optimization (PSO) based multi-stage fuzzy (PSOMSF) controller is proposed for solution of the load frequency control (LFC) problem in a restructured power system that operate under deregulation based on the bilateral policy scheme. In this strategy the control is tuned on line from the knowledge base and fuzzy inference, which request fewer sources and has two rule base sets. In the proposed method, for achieving the desired level of robust performance, exact tuning of membership functions is very important. Thus, to reduce the design effort and find a better fuzzy system control, membership functions are designed automatically by PSO algorithm, that has a strong ability to find the most optimistic results. The motivation for using the PSO technique is to reduce fuzzy system effort and take large parametric uncertainties into account. This newly developed control strategy combines the advantage of PSO and fuzzy system control techniques and leads to a flexible controller with simple stricture that is easy to implement. The proposed PSO based MSF (PSOMSF) controller is tested on a three-area restructured power system under different operating conditions and contract variations. The results of the proposed PSOMSF controller are compared with genetic algorithm based multi-stage fuzzy (GAMSF) control through some performance indices to illustrate its robust performance for a wide range of system parameters and load changes

Multi-stage fuzzy load frequency control using PSO

Energy Technology Data Exchange (ETDEWEB)

Shayeghi, H. [Technical Engineering Department, University of Mohaghegh Ardabili, Ardabil (Iran); Jalili, A. [Islamic Azad University, Ardabil Branch, Ardabil (Iran); Shayanfar, H.A. [Center of Excellence for Power Automation and Operation, Electrical Engineering Department, Iran University of Science and Technology, Tehran (Iran)

2008-10-15

In this paper, a particle swarm optimization (PSO) based multi-stage fuzzy (PSOMSF) controller is proposed for solution of the load frequency control (LFC) problem in a restructured power system that operate under deregulation based on the bilateral policy scheme. In this strategy the control is tuned on line from the knowledge base and fuzzy inference, which request fewer sources and has two rule base sets. In the proposed method, for achieving the desired level of robust performance, exact tuning of membership functions is very important. Thus, to reduce the design effort and find a better fuzzy system control, membership functions are designed automatically by PSO algorithm, that has a strong ability to find the most optimistic results. The motivation for using the PSO technique is to reduce fuzzy system effort and take large parametric uncertainties into account. This newly developed control strategy combines the advantage of PSO and fuzzy system control techniques and leads to a flexible controller with simple stricture that is easy to implement. The proposed PSO based MSF (PSOMSF) controller is tested on a three-area restructured power system under different operating conditions and contract variations. The results of the proposed PSOMSF controller are compared with genetic algorithm based multi-stage fuzzy (GAMSF) control through some performance indices to illustrate its robust performance for a wide range of system parameters and load changes. (author)

Multiple optical code-label processing using multi-wavelength frequency comb generator and multi-port optical spectrum synthesizer.

Science.gov (United States)

Moritsuka, Fumi; Wada, Naoya; Sakamoto, Takahide; Kawanishi, Tetsuya; Komai, Yuki; Anzai, Shimako; Izutsu, Masayuki; Kodate, Kashiko

2007-06-11

In optical packet switching (OPS) and optical code division multiple access (OCDMA) systems, label generation and processing are key technologies. Recently, several label processors have been proposed and demonstrated. However, in order to recognize N different labels, N separate devices are required. Here, we propose and experimentally demonstrate a large-scale, multiple optical code (OC)-label generation and processing technology based on multi-port, a fully tunable optical spectrum synthesizer (OSS) and a multi-wavelength electro-optic frequency comb generator. The OSS can generate 80 different OC-labels simultaneously and can perform 80-parallel matched filtering. We also demonstrated its application to OCDMA.

Startup experience with the MFTF-B ECRH 100 kV dc power supply

International Nuclear Information System (INIS)

Bishop, S.R.; Goodman, R.A.; Wilson, J.H.

1983-01-01

One of the 24 Accel dc Power Supplies (ADCPS) originally intended for the Mirror Fusion Test Facility (MFTF-B) Neutral Beam Power Supply (NBPS) System has been converted to provide negative polarity output at 90 kV with a load current of 64 A dc. The load duty cycle is a pulse of 30-seconds duration with a pulse repetition period of five minutes. A new control system has been built which will serve as a prototype for the MFTF-B ADCPS controls, and a test setup was built which will be used to test the ADCPS. The Electron Cyclotron Resonance Heating (ECRH) dc Power Supply (DCPS) has been tested under both no-load and dummy-load conditions, under remote control, without notable problems. Test results indicate that the power supply should be reliable and safe to operate, and will meet the load duty requirements

Startup experience with the MFTF-B ECRH 100 kV dc power supply

International Nuclear Information System (INIS)

Bishop, S.R.; Goodman, R.A.; Wilson, J.H.

1983-01-01

One of the 24 Accel DC Power Supplies (ADCPS) originally intended for the Mirror Fusion Test Facility (MFTF-B) Neutral Beam Power Supply (NBPS) System has been converted to provide negative polarity output at 90 kV with a load current of 64 A dc. The load duty cycle is a pulse of 30-seconds duration with a pulse repetition period of five minutes. A new control system has been built which will serve as a prototype for the MFTF-B ADCPS controls, and a test setup was built which will be used to test the ADCPS. The Electron Cyclotron Resonance Heating (ECRH) DC Power Supply (DCPS) has been tested under both no-load and dummy-load conditions, under remote control, without notable problems. Test results indicate that the power supply should be reliable and safe to operate, and will meet the load duty requirements

Multi-frequency GNSS robust carrier tracking for ionospheric scintillation mitigation

Science.gov (United States)

Vilà-Valls, Jordi; Closas, Pau; Curran, James T.

2017-10-01

Ionospheric scintillation is the physical phenomena affecting radio waves propagating from the space through the ionosphere to earth. The signal distortion induced by scintillation can pose a major threat to some GNSS application. Scintillation is one of the more challenging propagation scenarios, particularly affecting high-precision GNSS receivers which require high quality carrier phase measurements; and safety critical applications which have strict accuracy, availability and integrity requirements. Under ionospheric scintillation conditions, GNSS signals are affected by fast amplitude and phase variations, which can compromise the receiver synchronization. To take into account the underlying correlation among different frequency bands, we propose a new multivariate autoregressive model (MAR) for the multi-frequency ionospheric scintillation process. Multi-frequency GNSS observations and the scintillation MAR are modeled in state-space, allowing independent tracking of both line-of-sight phase variations and complex gain scintillation components. The resulting joint synchronization and scintillation mitigation problem is solved using a robust nonlinear Kalman filter, validated using real multi-frequency scintillation data with encouraging results.

Multi-Band (K- Q- and E-Band) Multi-Tone Millimeter-Wave Frequency Synthesizer for Radio Wave Propagation Studies

Science.gov (United States)

Simons, Rainee N.; Wintucky, Edwin G.

2014-01-01

This paper presents the design and test results of a multi-band multi-tone millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a space-borne transmitter for radio wave atmospheric studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). These studies would enable the design of robust multi-Gbps data rate space-to-ground satellite communication links. Lastly, the architecture for a compact multi-tone beacon transmitter, which includes a high frequency synthesizer, a polarizer, and a conical horn antenna, has been investigated for a notional CubeSat based space-to-ground radio wave propagation experiment.

Remote Control System of the TJ-II Microwave Transmission Lines Mirrors

International Nuclear Information System (INIS)

Lopez Sanchez, A.; Fernandez, A.; Cappa, A.; Gama, J. de la; Olivares, J.; Garcia, R.; Chamorro, M.

2007-01-01

The ECRH system of the TJ-II stellarator has two gyrotrons, which deliver a maximum power of 300 kW each at a frequency of 53.2 GHz. Another 28 GHz gyrotron will be used to heat the plasma by electron Bernstein waves (EBWH). The microwave power is transmitted from the gyrotrons to the vacuum chamber by two quasi-optical transmission lines for ECRH and a corrugated waveguide for EBWH. All transmission lines have an internal movable mirror inside the vacuum chamber to focus the beam and to be able to change the launching angle. The control of the beam polarization is very important and the lines have two corrugated mirrors, which actuate as polarizers. In this report the control system of the position of these three internal mirrors and the polarizers of the EBWH transmission line is described. (Author) 20 refs

Operational characteristics of the VEC radio-frequency system

Energy Technology Data Exchange (ETDEWEB)

Khemka, P K; Basu Mallik, D N; Bhattacharya, D S; Mukherjee, A K; Mukherjee, B; Ramamurthy, S S [Bhabha Atomic Research Centre, Bombay (India). Variable Energy Cyclotron Project

1979-01-01

The operating characteristics of the 400 kW rf system of the VEC, based on the RCA 6949 oscillator tube, and covering a frequency range of 5.5 to 16.5 MHz, are described. The frequency stability of the system is measured to be 1 part in 10/sup 5/, and a dee voltage of 40 kV at 8 MHz has been achieved. The results of experimental adjustments of ratio capacitor for proper excitation and appropriate fixed dee voltage over the entire frequency range are discussed. An analysis of the multi-pactoring encountered during beam trials is presented.

Operational characteristics of the VEC radio frequency system

International Nuclear Information System (INIS)

Khemka, P.K.; Basu Mallik, D.N.; Bhattacharya, D.S.; Mukherjee, A.K.; Mukherjee, B.; Ramamurthy, S.S.

1979-01-01

The operating characteristics of the 400 KW RF system of the VEC, based on the RCA 6949 oscillator tube, and covering a frequency range of 5.5 to 16.5 MHZ, are described. The frequency stability of the system is measured to be 1 part in 10 5 , and a dee voltage of 40 kV at 8 MHZ has been achieved. The results of experimental adjustments of ratio capacitor for proper excitation and appropriate fixed dee voltage over the entire frequency range are discussed. An analysis of the multi-pactoring encountered during beam trials is presented. (auth.)

Quantum system driven by incoherent a.c fields: Multi-crossing Landau Zener dynamics

Energy Technology Data Exchange (ETDEWEB)

Jipdi, M.N., E-mail: jmichaelnicky@yahoo.fr; Fai, L.C.; Tchoffo, M.

2016-10-23

The paper investigates the multi-crossing dynamics of a Landau–Zener (LZ) system driven by two sinusoidal a.c fields applying the Dynamic Matrix approach (DMA). The system is shown to follow one-crossing and multi-crossing dynamics for low and high frequency regime respectively. It is shown that in low frequency regime, the resonance phenomenon occurs and leads to the decoupling of basis states; the effective gap vanishes and then the complete blockage of the system. For high frequency, the system achieves multi-crossing dynamics with two fictitious crossings; the system models a Landau–Zener–Stückelberg (LZS) interferometer with critical parameters that tailor probabilities. The system is then shown to depend only on the phase that permits the easiest control with possible application in implementing logic gates.

A multi-frequency approach to free electron lasers driven by short electron bunches

International Nuclear Information System (INIS)

Piovella, Nicola

1997-01-01

A multi-frequency model for free electron lasers (FELs), based on the Fourier decomposition of the radiation field coupled with the beam electrons, is discussed. We show that the multi-frequency approach allows for an accurate description of the evolution of the radiation spectrum, also when the FEL is driven by short electron bunches, of arbitrary longitudinal profile. We derive from the multi-frequency model, by averaging over one radiation period, the usual FEL equations modelling the slippage between radiation and particles and describing the super-radiant regime in high-gain FELs. As an example of application of the multi-frequency model, we discuss the coherent spontaneous emission (CSE) from short electron bunches

Multi-variable systems in nuclear power plant

International Nuclear Information System (INIS)

Collins, G.B.; Howell, J.

1982-01-01

Nuclear power plant are complex multi-variable dynamically interactive systems which employ many facets of systems and control theory in their analysis and design. Whole plant mathematical models must be developed and validated and in addition to their obvious role in control system synthesis and design, they are also widely used for operational constraint and plant malfunction analysis. The need for and scope of an integrated power plant control system is discussed and, as a specific example, the design of an integrated feedwater regulator is reviewed. The multi-variable frequency response analysis employed in the design is described in detail. (author)

Development of over 1 MW and multi-frequency gyrotrons for fusion

International Nuclear Information System (INIS)

Imai, T.; Kariya, T.; Minami, R.; Numakura, T.; Kato, T.; Endo, Y.; Ichimura, M.; Eguchi, T.; Mitsunaka, Y.; Shimozuma, T.; Kubo, S.; Takahashi, H.; Yoshimura, Y.; Igami, H.; Ito, S.; Mutoh, T.; Sakamoto, Keishi; Idei, H.; Zushi, H.; Nagasaki, K.; Sano, F.; Ono, M.

2014-10-01

The development of wide frequency range from 14 to 300 GHz of high power mega-watt gyrotron for fusion is in progress in University of Tsukuba. The strong development activity was carried out in collaboration with JAEA, NIFS, TETD and universities. Over-1 MW dual frequency gyrotron of new frequency range (14 – 35 GHz), where the reduction of diffraction loss and cathode optimization are quite important, has been developed for EC/EBW H and CD for GAMMA 10/PDX, QUEST, Heliotron J and NSTX-U. Output power of 1.25 MW at 28 GHz and estimated oscillation power of 1.2 MW at 35.45 GHz from the same tube have been achieved with the cathode angle improvement and two frequency window. This is the first demonstration of the over 1 MW dual-frequency operations in lower frequency, which contributes to the technology of wide band multi-frequency/multi-MW tube. The output power of 600 kW for 2 s at 28 GHz is also demonstrated. It is applied to the QUEST and has resulted higher EC-driven current than ever. As for higher frequency range, in the joint program of NIFS and Tsukuba for LHD ECH gyrotrons, a new frequency of 154 GHz has been successfully developed with a TE 28,8 cavity, which delivered 1.16 MW for 1 s and the total power of 4.4 MW to LHD plasma with other three 77 GHz tubes, which extended the LHD plasma to high T e region. All these gyrotron performances are new records in each frequency range. The sub-THz gyrotron development is also just begun in collaboration with JAEA for Demo-Reactor ECH system. (author)

Investigation of the possibility of exceeding the Greenwald density limit during ECRH in T-10

International Nuclear Information System (INIS)

Alikaev, V.V.; Borshchegovskii, A.A.; Volkov, V.V.; Dremin, M.M.; Esipchuk, Yu.V.; Kakurin, A.M.; Kirneva, N.A.; Kislov, A.Ya.; Kislov, D.A.; Klimanov, I.V.; Kochin, V.A.; Krupin, V.A.; Krylov, S.V.; Myalton, T.B.; Novikov, A.Yu.; Notkin, G.E.; Pavlov, Yu.D.; Piterskii, V.V.; Poznyak, V.I.; Roi, I.N.

2000-01-01

In T-10 experiments, attempts were made to significantly exceed the Greenwald limit n-bar Gr during high-power (P ab = 750 kW) electron-cyclotron resonance heating (ECRH) and gas puffing. Formally, the density limit (n-bar e ) lim exceeding the Greenwald limit ((n-bar) e ) lim /n-bar Gr = 1.8) was achieved for q L = 8.2. However, as q L decreased, the ratio (n-bar e ) lim /n-bar Gr also decreased, approaching unity at q L ≅ 3. It was suggested that the 'current radius' (i.e., the radius of the magnetic surface enclosing the bulk of the plasma current I p ), rather than the limiter radius, was the parameter governing the value of (n-bar e ) lim . In the ECRH experiments, no substantial degradation of plasma confinement was observed up to n-bar e ∼ 0.9(n-bar e ) lim regardless of the ratio (n(bar sign) e ) lim /n-bar Gr . In different scenarios of the density growth up to (n-bar e ) lim , two types of disruptions related to the density limit were observed

Multi-frequency GNSS robust carrier tracking for ionospheric scintillation mitigation

Directory of Open Access Journals (Sweden)

Vilà-Valls Jordi

2017-01-01

Full Text Available Ionospheric scintillation is the physical phenomena affecting radio waves propagating from the space through the ionosphere to earth. The signal distortion induced by scintillation can pose a major threat to some GNSS application. Scintillation is one of the more challenging propagation scenarios, particularly affecting high-precision GNSS receivers which require high quality carrier phase measurements; and safety critical applications which have strict accuracy, availability and integrity requirements. Under ionospheric scintillation conditions, GNSS signals are affected by fast amplitude and phase variations, which can compromise the receiver synchronization. To take into account the underlying correlation among different frequency bands, we propose a new multivariate autoregressive model (MAR for the multi-frequency ionospheric scintillation process. Multi-frequency GNSS observations and the scintillation MAR are modeled in state-space, allowing independent tracking of both line-of-sight phase variations and complex gain scintillation components. The resulting joint synchronization and scintillation mitigation problem is solved using a robust nonlinear Kalman filter, validated using real multi-frequency scintillation data with encouraging results.

Progress on the ITER ECRH upper launcher steering mirror identification and control

International Nuclear Information System (INIS)

Collazos, Andres; Bertizzolo, Robert; Chavan, Rene; Dolizy, Frederic; Felici, Federico; Henderson, Mark A.; Landis, Jean-Daniel; Sanchez, Francisco

2009-01-01

The main objective of the ITER ECRH upper launcher (UL) is to control magnetohydrodynamic activity, in particular neoclassical tearing modes (NTMs), by driving several MW of EC current near the q = 1, 3/2, 2 flux surfaces, where NTMs are expected to occur. The steering of the EC power is done by the steering mechanism assembly (SMA) that comprises a reflecting mirror and a frictionless and backlash free pneumo-mechanical system actuated with pressurised helium gas. The control requirements for this component in terms of steering accuracy and speed are reviewed. With respect to these requirements, the performance of the first SMA prototype is assessed in a mock up of the UL pneumatic configuration. The expected design characteristics of the SMA have been verified and an overall satisfactory performance has been assessed. Furthermore, the main challenges for the future work, such as the pressure and angular position control, have been identified.

Conditioning of TJ-II Stellarator during the ECRH Plasmas Period

International Nuclear Information System (INIS)

Tafalla, D.; Tabares, F. L.

2001-01-01

The TJ-II stellarator has been conditioned by glow discharge (GD) during the first campaigns of operation, working only with ECR heating and all metal walls. The application of a He GD during the overnight period before the operation has been required in order to obtain reproducible discharges. However, the density control of the ECRH discharges was not possible because of the He implanted on the wall during GS. An short Ar GD(≤30 min) applied before the operation allows desorbes part of the implanted He. By applying this procedure (HeGD+ArGD), reproducible and density controlled plasmas have been achieved in H 2 and He. (Author) 20 refs

Simultaneous multi-band channel sounding at mm-Wave frequencies

DEFF Research Database (Denmark)

Müller, Robert; Häfner, Stephan; Dupleich, Diego

2016-01-01

The vision of multi Gbit/s data rates in future mobile networks requires the change to millimeter wave (mm-Wave) frequencies for increasing bandwidth. As a consequence, new technologies have to be deployed to tackle the drawbacks of higher frequency bands, e.g. increased path loss. Development an...

Development of a novel fast frequency modulation scheme for the JET multi-channel reflectometer

International Nuclear Information System (INIS)

Deliyanakis, N.

1999-10-01

A novel frequency modulation scheme has been developed for the multi-channel reflectometer used to measure density profiles and density fluctuations on the JET tokamak. This reflectometer normally uses slow frequency sweeping, combined with fixed-frequency operation, to measure the group delay, as well as plasma fluctuations, at 10 different microwave frequencies. The novel scheme uses continuous frequency modulation on a time-scale much faster than that of plasma fluctuations, the main aim being to make the group delay measurement more robust against plasma fluctuations. This paper discusses the theoretical background of the scheme, gives a detailed description of the system, and presents results from plasma measurements. (author)

Advanced Optics for the Remote Steering ITER ECRH Upper Launcher

International Nuclear Information System (INIS)

Bruschi, A; Cirant, S; Moro, A; Platania, P; Sozzi, C

2005-01-01

The optics of the ECRH Upper Launcher in ITER based on the Remote Steering concept needs special attention, since any focussing element in front of the waveguide has combined effects on the range of steering angles achievable and the beam width in the plasma region. The effects are studied in detail for a setup composed by 8 beams per port (three ports), for a spherical and a hyperbolic mirror surface. Gaussian beam analysis is compared to beam pattern calculations with the optical physics code GRASP, in order to verify the validity of gaussian optics approximation. The standard description with simply astigmatic beams, not adequate in more complex systems as the proposed two-mirror set-up, requires approximations, which are compared with the generalized astigmatic beam description. The ohmic losses at the end mirrors and the related localized heating due to the very large power density cause deformations that depends on the design of the cooling circuit. The distortion of the beam shape has been evaluated in a realistic case of mirror cooling with a small-channel system. The quantification of the effect depends on the precise evaluation ohmic losses and their enhancement in the long term due to the surface deterioration

Some recent multi-frequency electron paramagnetic resonance results on systems relevant for dosimetry and dating.

Science.gov (United States)

Callens, F; Vanhaelewyn, G; Matthys, P

2002-04-01

Electron Paramagnetic Resonance (EPR) applications like e.g. EPR dosimetry and dating, are usually performed at X-band frequencies because of practical reasons (cost, sample size, etc.). However, it is increasingly recognized that the radiation-induced EPR signals are strongly composite, what might affect dose/age estimates. A few recent examples from both the dosimetry and dating field, illustrating the problems, will be presented. The involved spectra are mainly due to carbonate-derived radicals (CO2-, CO3(3-), etc.). Measurements at higher microwave frequencies are often recommended to improve the insight into the spectra and/or the practical signal quantification. Recent results at Q- and W-band frequencies will show that a multi-frequency approach indeed opens many interesting perspectives in this field but also that each frequency may have specific (dis)advantages depending on the EPR probe and application involved. The discussion will concern carbonate-containing apatite single crystals, shells, modern and fossil tooth enamel.

On-electrode autonomous current generator for multi-frequency EIT

International Nuclear Information System (INIS)

Jivet, I; Dragoi, B

2008-01-01

The paper presents an autonomous programmable current generator module for multi-frequency EIT systems. The module incorporates all stages from the sine wave generation with frequency and amplitude tuning, D/A converter and filter, a high output resistance voltage-to-current converter to the associated digital communication and control. The paper presents in depth the original digital quadrature signal generator and the output current generator with a high resistance. The other main blocks of the design use current practice specifications, since recent technological solutions proposed in the literature were found appropriate. The proposed signal generator circuit, characterized by a very low complexity, is analyzed in its capacity to produce multiple accurate signals up to 1 MHz in frequency. The precision output current source uses a modified current conveyor of type CCII with a high output resistance and low distortion. The output current frequency spectrum and linearity parameters obtained in the simulations are also described. The simulation results indicate a good linearity and high output resistance with an acceptable output voltage swing. The calculated performance parameters are validated with simulations, and future work for the prototype fabrication of the IC is outlined

Complex Susceptibility Measurement Using Multi-frequency Slingram EMI Instrument

OpenAIRE

Simon , François Xavier; Tabbagh , Alain; Thiesson , Julien; Donati , J.C.; Sarris , A.

2014-01-01

International audience; Complex magnetic susceptibility is a well-known property both theoretically and experimentally. To achieve this measurement, different ways have been tested, like TDEM or multi-frequential measurement on soil sample. In this study we carry out the measurements by the use of a multi-frequential EMI Slingram instrument to collect data quickly and in-situ. The use of multi-frequency data is also a way to correct effects of the conductivity on the in-phase component and ef...

Coupled analysis of multi-impact energy harvesting from low-frequency wind induced vibrations

Science.gov (United States)

Zhu, Jin; Zhang, Wei

2015-04-01

Energy need from off-grid locations has been critical for effective real-time monitoring and control to ensure structural safety and reliability. To harvest energy from ambient environments, the piezoelectric-based energy-harvesting system has been proven very efficient to convert high frequency vibrations into usable electrical energy. However, due to the low frequency nature of the vibrations of civil infrastructures, such as those induced from vehicle impacts, wind, and waves, the application of a traditional piezoelectric-based energy-harvesting system is greatly restrained since the output power drops dramatically with the reduction of vibration frequencies. This paper focuses on the coupled analysis of a proposed piezoelectric multi-impact wind-energy-harvesting device that can effectively up-convert low frequency wind-induced vibrations into high frequency ones. The device consists of an H-shape beam and four bimorph piezoelectric cantilever beams. The H-shape beam, which can be easily triggered to vibrate at a low wind speed, is originated from the first Tacoma Narrows Bridge, which failed at wind speeds of 18.8 m s-1 in 1940. The multi-impact mechanism between the H-shape beam and the bimorph piezoelectric cantilever beams is incorporated to improve the harvesting performance at lower frequencies. During the multi-impact process, a series of sequential impacts between the H-shape beam and the cantilever beams can trigger high frequency vibrations of the cantilever beams and result in high output power with a considerably high efficiency. In the coupled analysis, the coupled structural, aerodynamic, and electrical equations are solved to obtain the dynamic response and the power output of the proposed harvesting device. A parametric study for several parameters in the coupled analysis framework is carried out including the external resistance, wind speed, and the configuration of the H-shape beam. The average harvested power for the piezoelectric cantilever

Extension of high T{sub e} regime with upgraded electron cyclotron resonance heating system in the Large Helical Device

Energy Technology Data Exchange (ETDEWEB)

Takahashi, H., E-mail: takahashi.hiromi@LHD.nifs.ac.jp; Shimozuma, T.; Kubo, S.; Yoshimura, Y.; Igami, H.; Ito, S.; Kobayashi, S.; Mizuno, Y.; Okada, K.; Mutoh, T.; Nagaoka, K.; Osakabe, M.; Yamada, I.; Nakano, H.; Yokoyama, M.; Ido, T.; Shimizu, A.; Seki, R.; Ida, K.; Yoshinuma, M. [National Institute for Fusion Science, Toki 509-5292 (Japan); and others

2014-06-15

Enhancement of the output power per gyrotron has been planned in the Large Helical Device (LHD). Three 77-GHz gyrotrons with an output power of more than 1 MW have been operated. In addition, a high power gyrotron with the frequency of 154 GHz (1 MW/5 s, 0.5 MW/CW) was newly installed in 2012, and the total injection power of Electron cyclotron resonance heating (ECRH) reached 4.6 MW. The operational regime of ECRH plasma on the LHD has been extended due to the upgraded ECRH system such as the central electron temperature of 13.5 keV with the line-averaged electron density n{sub e-fir} = 1 × 10{sup 19} m{sup −3}. The electron thermal confinement clearly improved inside the electron internal transport barrier, and the electron thermal diffusivity reached neoclassical level. The global energy confinement time increased with increase of n{sub e-fir}. The plasma stored energy of 530 kJ with n{sub e-fir} = 3.2 × 10{sup 19} m{sup −3}, which is 1.7 times larger than the previous record in the ECRH plasma in the LHD, has been successfully achieved.

Multi-beam synchronous measurement based on PSD phase detection using frequency-domain multiplexing

Science.gov (United States)

Duan, Ying; Qin, Lan; Xue, Lian; Xi, Feng; Mao, Jiubing

2013-10-01

According to the principle of centroid measurement, position-sensitive detectors (PSD) are commonly used for micro displacement detection. However, single-beam detection method cannot satisfy such tasks as multi-dimension position measurement, three dimension vision reconstruction, and robot precision positioning, which require synchronous measurement of multiple light beams. Consequently, we designed PSD phase detection method using frequency-domain multiplexing for synchronous detection of multiple modulated light beams. Compared to previous PSD amplitude detection method, the phase detection method using FDM has advantages of simplified measuring system, low cost, high capability of resistance to light interference as well as improved resolution. The feasibility of multi-beam synchronous measurement based on PSD phase detection using FDM was validated by multi-beam measuring experiments. The maximum non-linearity error of the multi-beam synchronous measurement is 6.62%.

An Online Q-learning Based Multi-Agent LFC for a Multi-Area Multi-Source Power System Including Distributed Energy Resources

Directory of Open Access Journals (Sweden)

H. Shayeghi

2017-12-01

Full Text Available This paper presents an online two-stage Q-learning based multi-agent (MA controller for load frequency control (LFC in an interconnected multi-area multi-source power system integrated with distributed energy resources (DERs. The proposed control strategy consists of two stages. The first stage is employed a PID controller which its parameters are designed using sine cosine optimization (SCO algorithm and are fixed. The second one is a reinforcement learning (RL based supplementary controller that has a flexible structure and improves the output of the first stage adaptively based on the system dynamical behavior. Due to the use of RL paradigm integrated with PID controller in this strategy, it is called RL-PID controller. The primary motivation for the integration of RL technique with PID controller is to make the existing local controllers in the industry compatible to reduce the control efforts and system costs. This novel control strategy combines the advantages of the PID controller with adaptive behavior of MA to achieve the desired level of robust performance under different kind of uncertainties caused by stochastically power generation of DERs, plant operational condition changes, and physical nonlinearities of the system. The suggested decentralized controller is composed of the autonomous intelligent agents, who learn the optimal control policy from interaction with the system. These agents update their knowledge about the system dynamics continuously to achieve a good frequency oscillation damping under various severe disturbances without any knowledge of them. It leads to an adaptive control structure to solve LFC problem in the multi-source power system with stochastic DERs. The results of RL-PID controller in comparison to the traditional PID and fuzzy-PID controllers is verified in a multi-area power system integrated with DERs through some performance indices.

Frequency position modulation using multi-spectral projections

Science.gov (United States)

Goodman, Joel; Bertoncini, Crystal; Moore, Michael; Nousain, Bryan; Cowart, Gregory

2012-10-01

In this paper we present an approach to harness multi-spectral projections (MSPs) to carefully shape and locate tones in the spectrum, enabling a new and robust modulation in which a signal's discrete frequency support is used to represent symbols. This method, called Frequency Position Modulation (FPM), is an innovative extension to MT-FSK and OFDM and can be non-uniformly spread over many GHz of instantaneous bandwidth (IBW), resulting in a communications system that is difficult to intercept and jam. The FPM symbols are recovered using adaptive projections that in part employ an analog polynomial nonlinearity paired with an analog-to-digital converter (ADC) sampling at a rate at that is only a fraction of the IBW of the signal. MSPs also facilitate using commercial of-the-shelf (COTS) ADCs with uniform-sampling, standing in sharp contrast to random linear projections by random sampling, which requires a full Nyquist rate sample-and-hold. Our novel communication system concept provides an order of magnitude improvement in processing gain over conventional LPI/LPD communications (e.g., FH- or DS-CDMA) and facilitates the ability to operate in interference laden environments where conventional compressed sensing receivers would fail. We quantitatively analyze the bit error rate (BER) and processing gain (PG) for a maximum likelihood based FPM demodulator and demonstrate its performance in interference laden conditions.

Single and multi-frequency impedance characterization of symmetric activated carbon single capacitor cells

Directory of Open Access Journals (Sweden)

Suzana Sopčić

2018-05-01

Full Text Available Electrochemical impedance spectroscopy (EIS technique is used for characterization of single cell symmetric capacitors having different mass loadings of activated carbon (AC. Relevant values of charge storage capacitance (CT and internal resistance (ESR were evaluated by the single frequency and multi-frequency analyses of measured impedance spectra. Curve fittings were based on the non-ideal R-C model that takes into account the parasitic inductance, contributions from electrode materials/contacts and the effects of AC porosity. Higher CT and lower ESR values were obtained not only for the cell with higher mass of AC, but also using the single vs. multi-frequency approach. Lower CT and higher values of ESR that are generally obtained using the multi-frequency method and curve fittings should be related to the not ideal capacitive response of porous AC material and too high frequency chosen in applying the single frequency analysis.

Dynamics of Microbeams under Multi-Frequency Excitations

KAUST Repository

Ibrahim, Alwathiqbellah

2017-01-24

This paper presents an investigation of the dynamics of microbeams under multiple harmonic electrostatic excitation frequencies. First, the response of a cantilever microbeam to two alternating current (AC) source excitation is examined. We show by simulations the response of the microbeam at primary resonance (near the fundamental natural frequency) and at secondary resonances (near half, superharmonic, and twice, subharmonic, the fundamental natural frequency). A multimode Galerkin method combined with the Euler-Bernoulli beam equation, accounting for the nonlinear electrostatic force, has been used to develop a reduced order model. The response of the cantilever microbeam to three AC source excitation is also investigated and shown as a promising technique to enhance the bandwidth of resonators. Finally, an experimental study of a clamped-clamped microbeam is conducted, demonstrating the multi-frequency excitation resonances using two, three, and four AC sources.

Dynamics of Microbeams under Multi-Frequency Excitations

KAUST Repository

Ibrahim, Alwathiqbellah; Jaber, Nizar; Chandran, Akhil; Thirupathi, Maloth; Younis, Mohammad I.

2017-01-01

This paper presents an investigation of the dynamics of microbeams under multiple harmonic electrostatic excitation frequencies. First, the response of a cantilever microbeam to two alternating current (AC) source excitation is examined. We show by simulations the response of the microbeam at primary resonance (near the fundamental natural frequency) and at secondary resonances (near half, superharmonic, and twice, subharmonic, the fundamental natural frequency). A multimode Galerkin method combined with the Euler-Bernoulli beam equation, accounting for the nonlinear electrostatic force, has been used to develop a reduced order model. The response of the cantilever microbeam to three AC source excitation is also investigated and shown as a promising technique to enhance the bandwidth of resonators. Finally, an experimental study of a clamped-clamped microbeam is conducted, demonstrating the multi-frequency excitation resonances using two, three, and four AC sources.

Multi-User Interference Cancellation Scheme(s) for Muliple Carrier Frequency Offset Compensation in Uplink OFDMA

DEFF Research Database (Denmark)

Nguyen, Huan Cong; Carvalho, Elisabeth De; Prasad, Ramjee

2006-01-01

(ICI) and degrade the system performance considerably. In this paper, we propose a novel Multi-User Interference (MUI) cancellation scheme for uplink OFDMA, which utilizes multiple OFDM-demodulators architecture to correct and then compensate the negative effects of multiple CFOs at the receiver's side......We consider the uplink of an Orthogonal Frequency Division Multiple Access (OFDMA)-based system, where each Mobile Station (MS) experiences a different Carrier Frequency Offset (CFO). Uncorrected CFO destroy the orthogonality among subcarriers, which could cause severe Inter-Carrier Interference...

A 3D tunable and multi-frequency graphene plasmonic cloak

KAUST Repository

Farhat, Mohamed

2013-01-01

We demonstrate the possibility of cloaking three-dimensional objects at multi-frequencies in the far-infrared part of the spectrum. The proposed cloaking mechanism exploits graphene layers wrapped around the object to be concealed. Graphene layers are doped via a variable external voltage difference permitting continuous tuning of the cloaking frequencies. Particularly, two configurations are investigated: (i) Only one graphene layer is used to suppress the scattering from a dielectric sphere. (ii) Several of these layers biased at different gate voltages are used to achieve a multi-frequency cloak. These frequencies can be set independently. The proposed cloak\\'s functionality is verified by near- and far-field computations. By considering geometry and material parameters that are realizable by practical experiments, we contribute to the development of graphene based plasmonic applications that may find use in disruptive photonic technologies. © 2013 Optical Society of America.

Effect of inter-tissue inductive coupling on multi-frequency imaging of intracranial hemorrhage by magnetic induction tomography

Science.gov (United States)

Xiao, Zhili; Tan, Chao; Dong, Feng

2017-08-01

Magnetic induction tomography (MIT) is a promising technique for continuous monitoring of intracranial hemorrhage due to its contactless nature, low cost and capacity to penetrate the high-resistivity skull. The inter-tissue inductive coupling increases with frequency, which may lead to errors in multi-frequency imaging at high frequency. The effect of inter-tissue inductive coupling was investigated to improve the multi-frequency imaging of hemorrhage. An analytical model of inter-tissue inductive coupling based on the equivalent circuit was established. A set of new multi-frequency decomposition equations separating the phase shift of hemorrhage from other brain tissues was derived by employing the coupling information to improve the multi-frequency imaging of intracranial hemorrhage. The decomposition error and imaging error are both decreased after considering the inter-tissue inductive coupling information. The study reveals that the introduction of inter-tissue inductive coupling can reduce the errors of multi-frequency imaging, promoting the development of intracranial hemorrhage monitoring by multi-frequency MIT.

Removal of Optically Thick Clouds from Multi-Spectral Satellite Images Using Multi-Frequency SAR Data

Directory of Open Access Journals (Sweden)

Robert Eckardt

2013-06-01

Full Text Available This study presents a method for the reconstruction of pixels contaminated by optical thick clouds in multi-spectral Landsat images using multi-frequency SAR data. A number of reconstruction techniques have already been proposed in the scientific literature. However, all of the existing techniques have certain limitations. In order to overcome these limitations, we expose the Closest Spectral Fit (CSF method proposed by Meng et al. to a new, synergistic approach using optical and SAR data. Therefore, the term Closest Feature Vector (CFV is introduced. The technique facilitates an elegant way to avoid radiometric distortions in the course of image reconstruction. Furthermore the cloud cover removal is independent from underlying land cover types and assumptions on seasonality, etc. The methodology is applied to mono-temporal, multi-frequency SAR data from TerraSAR-X (X-Band, ERS (C-Band and ALOS Palsar (L-Band. This represents a way of thinking about Radar data not as foreign, but as additional data source in multi-spectral remote sensing. For the assessment of the image restoration performance, an experimental framework is established and a statistical evaluation protocol is designed. The results show the potential of a synergistic usage of multi-spectral and SAR data to overcome the loss of data due to cloud cover.

A strategy for determination of test intervals of k-out-of-n multi-channel systems

International Nuclear Information System (INIS)

Cho, S.; Jiang, J.

2007-01-01

State space models for determination of the optimal test frequencies for k-out-of-n multi channel systems are developed in this paper. The analytic solutions for the optimal surveillance test frequencies are derived using the Markov process technique. The solutions show that an optimal test frequency which maximizes the target probability can be determined by decomposing the system states to 3 states based on the system configuration and success criteria. Examples of quantification of the state probabilities and the optimal test frequencies of a three-channel system and a four-channel system with different success criteria are presented. The strategy for finding the optimal test frequency developed in this paper can generally be applicable to any k-out-of-n multi-channel standby systems that involve complex testing schemes. (author)

Inverse scattering problems with multi-frequencies

International Nuclear Information System (INIS)

Bao, Gang; Li, Peijun; Lin, Junshan; Triki, Faouzi

2015-01-01

This paper is concerned with computational approaches and mathematical analysis for solving inverse scattering problems in the frequency domain. The problems arise in a diverse set of scientific areas with significant industrial, medical, and military applications. In addition to nonlinearity, there are two common difficulties associated with the inverse problems: ill-posedness and limited resolution (diffraction limit). Due to the diffraction limit, for a given frequency, only a low spatial frequency part of the desired parameter can be observed from measurements in the far field. The main idea developed here is that if the reconstruction is restricted to only the observable part, then the inversion will become stable. The challenging task is how to design stable numerical methods for solving these inverse scattering problems inspired by the diffraction limit. Recently, novel recursive linearization based algorithms have been presented in an attempt to answer the above question. These methods require multi-frequency scattering data and proceed via a continuation procedure with respect to the frequency from low to high. The objective of this paper is to give a brief review of these methods, their error estimates, and the related mathematical analysis. More attention is paid to the inverse medium and inverse source problems. Numerical experiments are included to illustrate the effectiveness of these methods. (topical review)

Effect of randomness on multi-frequency aeroelastic responses resolved by Unsteady Adaptive Stochastic Finite Elements

International Nuclear Information System (INIS)

Witteveen, Jeroen A.S.; Bijl, Hester

2009-01-01

The Unsteady Adaptive Stochastic Finite Elements (UASFE) method resolves the effect of randomness in numerical simulations of single-mode aeroelastic responses with a constant accuracy in time for a constant number of samples. In this paper, the UASFE framework is extended to multi-frequency responses and continuous structures by employing a wavelet decomposition pre-processing step to decompose the sampled multi-frequency signals into single-frequency components. The effect of the randomness on the multi-frequency response is then obtained by summing the results of the UASFE interpolation at constant phase for the different frequency components. Results for multi-frequency responses and continuous structures show a three orders of magnitude reduction of computational costs compared to crude Monte Carlo simulations in a harmonically forced oscillator, a flutter panel problem, and the three-dimensional transonic AGARD 445.6 wing aeroelastic benchmark subject to random fields and random parameters with various probability distributions.

A Versatile and Reproducible Multi-Frequency Electrical Impedance Tomography System

Directory of Open Access Journals (Sweden)

James Avery

2017-01-01

Full Text Available A highly versatile Electrical Impedance Tomography (EIT system, nicknamed the ScouseTom, has been developed. The system allows control over current amplitude, frequency, number of electrodes, injection protocol and data processing. Current is injected using a Keithley 6221 current source, and voltages are recorded with a 24-bit EEG system with minimum bandwidth of 3.2 kHz. Custom PCBs interface with a PC to control the measurement process, electrode addressing and triggering of external stimuli. The performance of the system was characterised using resistor phantoms to represent human scalp recordings, with an SNR of 77.5 dB, stable across a four hour recording and 20 Hz to 20 kHz. In studies of both haeomorrhage using scalp electrodes, and evoked activity using epicortical electrode mats in rats, it was possible to reconstruct images matching established literature at known areas of onset. Data collected using scalp electrode in humans matched known tissue impedance spectra and was stable over frequency. The experimental procedure is software controlled and is readily adaptable to new paradigms. Where possible, commercial or open-source components were used, to minimise the complexity in reproduction. The hardware designs and software for the system have been released under an open source licence, encouraging contributions and allowing for rapid replication.

The Front Steering Launcher Design for the ITER ECRH Upper Port

International Nuclear Information System (INIS)

Henderson, M A; Chavan, R; Heidinger, R; Nikkola, P; Ramponi, G; Saibene, G; Sanchez, F; Sauter, O; Serikov, A; Zohm, H

2005-01-01

The ECRH ITER upper port antenna's role is to stabilize the neoclassical tearing mode (NTM) on either the q = 2 or 3/2 rational flux surfaces, which requires a narrow current deposition profile (j CD ) over a wide range along the resonance surfaces. The width of j CD should be equivalent to the marginal island width to fully stabilise the NTM. Two antenna concepts are under consideration for the upper port launcher: front steering (FS) and remote steering (RS). The FS launcher decouples the steering and focusing aspects using a two mirror system (one focusing and one steering), achieving a wider steering range and higher current density for NTM stabilisation than required by ITER, offering a threefold increase in NTM stabilization efficiency over the RS launcher. The improved physics performance has motivated the further design study of the FS launcher aiming toward a build to print launcher. The present design is compatible with ≥2.0 MW CW operation and 8 beams per port plug. A frictionless backlashfree system is envisioned for the steering mechanism. An overview of the launcher design, the calculated physics performance and the possibility of using the upper port launcher for extended physics applications (beyond NTM stabilisation) are discussed

Parallel Computational Intelligence-Based Multi-Camera Surveillance System

Directory of Open Access Journals (Sweden)

Sergio Orts-Escolano

2014-04-01

Full Text Available In this work, we present a multi-camera surveillance system based on the use of self-organizing neural networks to represent events on video. The system processes several tasks in parallel using GPUs (graphic processor units. It addresses multiple vision tasks at various levels, such as segmentation, representation or characterization, analysis and monitoring of the movement. These features allow the construction of a robust representation of the environment and interpret the behavior of mobile agents in the scene. It is also necessary to integrate the vision module into a global system that operates in a complex environment by receiving images from multiple acquisition devices at video frequency. Offering relevant information to higher level systems, monitoring and making decisions in real time, it must accomplish a set of requirements, such as: time constraints, high availability, robustness, high processing speed and re-configurability. We have built a system able to represent and analyze the motion in video acquired by a multi-camera network and to process multi-source data in parallel on a multi-GPU architecture.

Multi-frequency eddy current testing method

International Nuclear Information System (INIS)

Levy, R.; Gallet, G.

1980-01-01

Monitoring by multi-frequency eddy currents has been used since 1975 in French nuclear stations; this method applies perfectly to examinations in non-irradiated surroundings. The restrictions connected with operations in controlled zones (radioactivity) have led to the development of a delayed analysis device which in no way changes the principle of the method, but allows greater flexibility of use by reducing the volume of equipment needed and by limiting the intervention of personnel to a strict minimum [fr

Single- and multi-frequency detection of surface displacements via scanning probe microscopy.

Science.gov (United States)

Romanyuk, Konstantin; Luchkin, Sergey Yu; Ivanov, Maxim; Kalinin, Arseny; Kholkin, Andrei L

2015-02-01

Piezoresponse force microscopy (PFM) provides a novel opportunity to detect picometer-level displacements induced by an electric field applied through a conducting tip of an atomic force microscope (AFM). Recently, it was discovered that superb vertical sensitivity provided by PFM is high enough to monitor electric-field-induced ionic displacements in solids, the technique being referred to as electrochemical strain microscopy (ESM). ESM has been implemented only in multi-frequency detection modes such as dual AC resonance tracking (DART) and band excitation, where the response is recorded within a finite frequency range, typically around the first contact resonance. In this paper, we analyze and compare signal-to-noise ratios of the conventional single-frequency method with multi-frequency regimes of measuring surface displacements. Single-frequency detection ESM is demonstrated using a commercial AFM.

Study on a High-frequency Multi-GNSS Real-time Precise Clock Estimation Algorithm and Application in GNSS Augment System

Directory of Open Access Journals (Sweden)

CHEN Liang

2017-05-01

Full Text Available GNSS satellite-based differential augment system is based on real-time orbit and clock augment message. The multi-GNSS real-time precise clock error estimation model is studied, and then the parameters estimated in traditional un-difference model are optimized and a high-efficient real-time clock simplified model is proposed and realized. The real-time orbit data processing based on PANDA is also analyzed. The results indicate that the real-time orbit radial accuracy of GPS, BeiDou MEO and Galileo is 1~5 cm, and the radial accuracy of the BeiDou GEO/IGSO satellite is about 10 cm. It is found that the optimized real-time clock simplified model is more efficient in one epoch than un-difference model and can be applied to high-frequency (such as 1 Hz updating of real-time clock augment message. The results show that the real-time clock error obtained by this model is absolute value and there is no constant bias. Based on the real-time orbit, the GPS real-time clock precision of the simplified model is about 0.24 ns, BeiDou GEO is about 0.50 ns, IGSO/MEO is about 0.22 ns and Galileo is about 0.32 ns. Using the multi-GNSS real-time data stream in GFZ, a multi-GNSS real-time augment prototype system is built and the real-time augment message is being broadcasted on the Internet. The real-time PPP centimeter-level service and meter-level navigation service based on pseudorange are realized based on this prototype system.

POD and PPP with multi-frequency processing

Science.gov (United States)

Roldán, Pedro; Navarro, Pedro; Rodríguez, Daniel; Rodríguez, Irma

2017-04-01

to use a-priori information based on ionospheric models, on external estimations and on the expected behavior of the ionosphere. The inter-frequency biases appear because the delay of the signal inside the transmitter and the receiver strongly depends on its frequency. However, it is possible to include constraints in the estimator regarding these delays, assuming small variations over time. By using different types of combinations, all the available information from GNSS systems can be included in the processing. This is especially interesting for the case of Galileo satellites, which transmit in several frequencies, and the GPS IIF satellites, which transmit in L5 in addition to the traditional L1 and L2. Several experiments have been performed, to assess the improvement on performance of POD and PPP when using all the constellations and all the available frequencies for each constellation. This paper describes the new approach of multi-frequency processing, including the estimation of biases and ionospheric delays impacting on GNSS observations, and presents the results of the performed experimentation activities to assess the benefits in POD and PPP algorithms.

Effect of antiferromagnetic interfacial coupling on spin-wave resonance frequency of multi-layer film

Energy Technology Data Exchange (ETDEWEB)

Qiu, Rong-ke, E-mail: rkqiu@163.com; Cai, Wei

2017-08-15

Highlights: • A quantum approach is developed to study the SWR of a bicomponent multi-layer films. • The comparison of the SWR in films with FM and AFM interfacial coupling has been made. • The present results show the method to enhance and adjust the SWR frequency of films. - Abstract: We investigate the spin-wave resonance (SWR) frequency in a bicomponent bilayer and triple-layer films with antiferromagnetic or ferromagnetic interfacial couplings, as function of interfacial coupling, surface anisotropy, interface anisotropy, thickness and external magnetic field, using the linear spin-wave approximation and Green’s function technique. The microwave properties for multi-layer magnetic film with antiferromagnetic interfacial coupling is different from those for multi-layer magnetic film with ferromagnetic interfacial coupling. For the bilayer film with antiferromagnetic interfacial couplings, as the lower (upper) surface anisotropy increases, only the SWR frequencies of the odd (even) number modes increase. The lower (upper) surface anisotropy does not affect the SWR frequencies of the even (odd) number modes{sub .} For the multi-layer film with antiferromagnetic interfacial coupling, the SWR frequency of modes m = 1, 3 and 4 decreases while that of mode m = 2 increases with increasing thickness of the film within a proper parameter region. The present results could be useful in enhancing our fundamental understanding and show the method to enhance and adjust the SWR frequency of bicomponent multi-layer magnetic films with antiferromagnetic or ferromagnetic interfacial coupling.

Damage detection in multi-span beams based on the analysis of frequency changes

International Nuclear Information System (INIS)

Gillich, G R; Ntakpe, J L; Praisach, Z I; Mimis, M C; Abdel Wahab, M

2017-01-01

Crack identification in multi-span beams is performed to determine whether the structure is healthy or not. Among all crack identification methods, these based on measured natural frequency changes present the advantage of simplicity and easy to use in practical engineering. To accurately identify the cracks characteristics for multi-span beam structure, a mathematical model is established, which can predict frequency changes for any boundary conditions, the intermediate supports being hinges. This relation is based on the modal strain energy concept. Since frequency changes are relative small, to obtain natural frequencies with high resolution, a signal processing algorithm based on superposing of numerous spectra is also proposed, which overcomes the disadvantage of Fast Fourier Transform in the aspect of frequency resolution. Based on above-mentioned mathematical model and signal processing algorithm, the method of identifying cracks on multi-span beams is presented. To verify the accuracy of this identification method, experimental examples are conducted on a two-span structure. The results demonstrate that the method proposed in this paper can accurately identify the crack position and depth. (paper)

Multi frequency excited MEMS cantilever beam resonator for Mixer-Filter applications

KAUST Repository

Chandran, Akhil A.

2016-09-15

Wireless communication uses Radio Frequency waves to transfer information from one point to another. The modern RF front end devices are implementing MEMS in their designs so as to exploit the inherent properties of MEMS devices, such as its low mass, low power consumption, and small size. Among the components in the RF transceivers, band pass filters and mixers play a vital role in achieving the optimum RF performance. And this paper aims at utilizing an electrostatically actuated micro cantilever beam resonator\\'s nonlinear frequency mixing property to realize a Mixer-Filter configuration through multi-frequency excitation. The paper studies about the statics and dynamics of the device. Simulations are carried out to study the added benefits of multi frequency excitation. The modelling of the cantilever beam has been done using a Reduced Order Model of the Euler-Bernoulli\\'s beam equation by implementing the Galerkin discretization. The device is shown to be able to down-convert signals from 960 MHz of frequency to an intermediate frequency around 50 MHz and 70 MHz in Phase 1 and 2, respectively. The simulation showed promising results to take the project to the next level. © 2016 IEEE.

Multi frequency excited MEMS cantilever beam resonator for Mixer-Filter applications

KAUST Repository

Chandran, Akhil A.; Younis, Mohammad I.

2016-01-01

Wireless communication uses Radio Frequency waves to transfer information from one point to another. The modern RF front end devices are implementing MEMS in their designs so as to exploit the inherent properties of MEMS devices, such as its low mass, low power consumption, and small size. Among the components in the RF transceivers, band pass filters and mixers play a vital role in achieving the optimum RF performance. And this paper aims at utilizing an electrostatically actuated micro cantilever beam resonator's nonlinear frequency mixing property to realize a Mixer-Filter configuration through multi-frequency excitation. The paper studies about the statics and dynamics of the device. Simulations are carried out to study the added benefits of multi frequency excitation. The modelling of the cantilever beam has been done using a Reduced Order Model of the Euler-Bernoulli's beam equation by implementing the Galerkin discretization. The device is shown to be able to down-convert signals from 960 MHz of frequency to an intermediate frequency around 50 MHz and 70 MHz in Phase 1 and 2, respectively. The simulation showed promising results to take the project to the next level. © 2016 IEEE.

FREQUENCY REDISTRIBUTION OF POLARIZED LIGHT IN THE Λ-TYPE MULTI-TERM POLARIZED ATOM

Energy Technology Data Exchange (ETDEWEB)

Casini, R. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Sainz, R. Manso [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

2016-06-20

We study the effects of Rayleigh and Raman scattering on the formation of polarized spectral lines in a Λ-type multi-term atom. We fully take into account the partial redistribution of frequency and the presence of atomic polarization in the lower states of the atomic model. Problems that can be modeled with this formalism include, for example, the formation of the Ca ii H–K and IR triplet, the analogous system of Ba ii, and the Ly β –H α system of hydrogenic ions.

Correction of electrode modelling errors in multi-frequency EIT imaging.

Science.gov (United States)

Jehl, Markus; Holder, David

2016-06-01

The differentiation of haemorrhagic from ischaemic stroke using electrical impedance tomography (EIT) requires measurements at multiple frequencies, since the general lack of healthy measurements on the same patient excludes time-difference imaging methods. It has previously been shown that the inaccurate modelling of electrodes constitutes one of the largest sources of image artefacts in non-linear multi-frequency EIT applications. To address this issue, we augmented the conductivity Jacobian matrix with a Jacobian matrix with respect to electrode movement. Using this new algorithm, simulated ischaemic and haemorrhagic strokes in a realistic head model were reconstructed for varying degrees of electrode position errors. The simultaneous recovery of conductivity spectra and electrode positions removed most artefacts caused by inaccurately modelled electrodes. Reconstructions were stable for electrode position errors of up to 1.5 mm standard deviation along both surface dimensions. We conclude that this method can be used for electrode model correction in multi-frequency EIT.

The status of the QUIJOTE multi-frequency instrument

Science.gov (United States)

Hoyland, R. J.; Aguiar-González, M.; Aja, B.; Ariño, J.; Artal, E.; Barreiro, R. B.; Blackhurst, E. J.; Cagigas, J.; Cano de Diego, J. L.; Casas, F. J.; Davis, R. J.; Dickinson, C.; Arriaga, B. E.; Fernandez-Cobos, R.; de la Fuente, L.; Génova-Santos, R.; Gómez, A.; Gomez, C.; Gómez-Reñasco, F.; Grainge, K.; Harper, S.; Herran, D.; Herreros, J. M.; Herrera, G. A.; Hobson, M. P.; Lasenby, A. N.; Lopez-Caniego, M.; López-Caraballo, C.; Maffei, B.; Martinez-Gonzalez, E.; McCulloch, M.; Melhuish, S.; Mediavilla, A.; Murga, G.; Ortiz, D.; Piccirillo, L.; Pisano, G.; Rebolo-López, R.; Rubiño-Martin, J. A.; Ruiz, J. Luis; Sanchez de la Rosa, V.; Sanquirce, R.; Vega-Moreno, A.; Vielva, P.; Viera-Curbelo, T.; Villa, E.; Vizcargüenaga, A.; Watson, R. A.

2012-09-01

The QUIJOTE-CMB project has been described in previous publications. Here we present the current status of the QUIJOTE multi-frequency instrument (MFI) with five separate polarimeters (providing 5 independent sky pixels): two which operate at 10-14 GHz, two which operate at 16-20 GHz, and a central polarimeter at 30 GHz. The optical arrangement includes 5 conical corrugated feedhorns staring into a dual reflector crossed-draconian system, which provides optimal cross-polarization properties (designed to be switch out various systematics. The detection system provides optimum sensitivity through 2 correlated and 2 total power channels. The system is calibrated using bright polarized celestial sources and through a secondary calibration source and antenna. The acquisition system, telescope control and housekeeping are all linked through a real-time gigabit Ethernet network. All communication, power and helium gas are passed through a central rotary joint. The time stamp is synchronized to a GPS time signal. The acquisition software is based on PLCs written in Beckhoffs TwinCat and ethercat. The user interface is written in LABVIEW. The status of the QUIJOTE MFI will be presented including pre-commissioning results and laboratory testing.

Low power fast settling multi-standard current reusing CMOS fractional-N frequency synthesizer

Institute of Scientific and Technical Information of China (English)

Lou Wenfeng; Feng Peng; Wang Haiyong; Wu Nanjian

2012-01-01

A low power fast settling multi-standard CMOS fractional-N frequency synthesizer is proposed.The current reusing and frequency presetting techniques are adopted to realize the low power fast settling multi-standard fractional-N frequency synthesizer.An auxiliary non-volatile memory (NVM) is embedded to avoid the repetitive calibration process and to save power in practical application.This PLL is implemented in a 0.18μm technology.The frequency range is 0.3 to 2.54 GHz and the settling time is less than 5μs over the entire frequency range.The LC-VCO with the stacked divide-by-2 has a good figure of merit of-193.5 dBc/Hz.The measured phase noise of frequency synthesizer is about -115 dBc/Hz at 1 MHz offset when the carrier frequency is 2.4 GHz and the reference spurs are less than -52 dBc.The whole frequency synthesizer consumes only 4.35 mA @ 1.8 V.

Multi-frequency response from a designed array of micromechanical cantilevers fabricated using a focused ion beam

International Nuclear Information System (INIS)

Ghatnekar-Nilsson, S; Graham, J; Hull, R; Montelius, L

2006-01-01

We demonstrate arrays of cantilevers with different lengths, fabricated by focused ion beam milling. The arrays of oscillators generate a spectrum of different resonant frequencies, where each frequency correlates to the corresponding individual cantilever. The frequency response from all the cantilevers is collected from a single measurement under the same environment and conditions for the entire array. The mass response of the system generated the same Δf/f 0 for the cantilevers, within 0.1% accuracy. We denote the method MFSAC: multi-frequency signal analysis from an array of cantilevers. The simultaneous detection of several frequencies in one spectrum has great benefits in mass sensor applications, offering the possibility for true label-free detection

Anomalous phenomena in ECRH experiments at toroidal devices and low-threshold parametric decay instabilities

Directory of Open Access Journals (Sweden)

Saveliev A.N.

2012-09-01

Full Text Available In the paper the possibility of total 3D trapping of electron Bernstein (EB waves in the tokamak equatorial plane in the vicinity of the local density maximum produced by electron pump-out-effect is demonstrated. Thresholds and growth rates of the associated absolute (temporally growing parametric decay instability (PDI leading to anomalous absorption is predicted in the range of less than 100 kW. Its possible role in explanation of ion acceleration observed in ECRH experiments as well as in redistribution of the deposited power is discussed.

Multi-frequency accelerating strategy for the contrast source inversion method of ultrasound waveform tomography using pulse data

Science.gov (United States)

Lin, Hongxiang; Azuma, Takashi; Qu, Xiaolei; Takagi, Shu

2017-03-01

In this work, we construct a multi-frequency accelerating strategy for the contrast source inversion (CSI) method using pulse data in the time domain. CSI is a frequency-domain inversion method for ultrasound waveform tomography that does not require the forward solver through the process of reconstruction. Several prior researches show that the CSI method has a good performance of convergence and accuracy in the low-center-frequency situation. In contrast, utilizing the high-center-frequency data leads to a high-resolution reconstruction but slow convergence on large numbers of grid. Our objective is to take full advantage of all low frequency components from pulse data with the high-center-frequency data measured by the diagnostic device. First we process the raw data in the frequency domain. Then multi-frequency accelerating strategy helps restart CSI in the current frequency using the last iteration result obtained from the lower frequency component. The merit of multi- frequency accelerating strategy is that computational burden decreases at the first few iterations. Because the low frequency component of dataset computes on the coarse grid with assuming a fixed number of points per wavelength. In the numerical test, the pulse data were generated by the K-wave simulator and have been processed to meet the computation of the CSI method. We investigate the performance of the multi-frequency and single-frequency reconstructions and conclude that the multi-frequency accelerating strategy significantly enhances the quality of the reconstructed image and simultaneously reduces the average computational time for any iteration step.

Extension of the ECRH operational space with O2 and X3 heating schemes to control tungsten accumulation in ASDEX Upgrade

Science.gov (United States)

Höhnle, H.; Stober, J.; Herrmann, A.; Kasparek, W.; Leuterer, F.; Monaco, F.; Neu, R.; Schmid-Lorch, D.; Schütz, H.; Schweinzer, J.; Stroth, U.; Wagner, D.; Vorbrugg, S.; Wolfrum, E.; ASDEX Upgrade Team

2011-08-01

ASDEX Upgrade has been operated with tungsten-coated plasma-facing components for several years. H-mode operation with good confinement has been demonstrated. Nevertheless, purely neutral beam injection-heated H-modes with reduced gas puff, moderate heating power or/and increased triangularity tend to accumulate tungsten, followed by a radiative collapse. Under these conditions, central electron heating with electron cyclotron resonance heating (ECRH), usually in X2 polarization, changes the impurity transport in the plasma centre, reducing the central tungsten concentration and, in many cases, stabilizing the plasma. In order to extend the applicability of central ECRH to a wider range of magnetic field and plasma current additional ECRH schemes with reduced single-pass absorption have been implemented: X3 heating allows us to reduce the magnetic field by 30%, such that the first H-modes with an ITER-like value of the safety factor of q95 = 3 could be run in the tungsten-coated device. O2 heating increases the cutoff density by a factor of 2 allowing higher currents and triangularities to be addressed. For both schemes, scenarios have been developed to cope with the associated reduced absorption. In the case of central X3 heating, the X2 resonance lies close to the pedestal top at the high-field side of the plasma, serving as a beam dump. For O2, holographic mirrors have been developed which guarantee a second pass through the plasma centre. The beam position on these reflectors is controlled by fast thermocouples. Stray-radiation protection has been implemented using sniffer probes.

Extension of the ECRH operational space with O2 and X3 heating schemes to control tungsten accumulation in ASDEX Upgrade

International Nuclear Information System (INIS)

Hoehnle, H.; Kasparek, W.; Stroth, U.; Stober, J.; Herrmann, A.; Leuterer, F.; Monaco, F.; Neu, R.; Schmid-Lorch, D.; Schuetz, H.; Schweinzer, J.; Wagner, D.; Vorbrugg, S.; Wolfrum, E.

2011-01-01

ASDEX Upgrade has been operated with tungsten-coated plasma-facing components for several years. H-mode operation with good confinement has been demonstrated. Nevertheless, purely neutral beam injection-heated H-modes with reduced gas puff, moderate heating power or/and increased triangularity tend to accumulate tungsten, followed by a radiative collapse. Under these conditions, central electron heating with electron cyclotron resonance heating (ECRH), usually in X2 polarization, changes the impurity transport in the plasma centre, reducing the central tungsten concentration and, in many cases, stabilizing the plasma. In order to extend the applicability of central ECRH to a wider range of magnetic field and plasma current additional ECRH schemes with reduced single-pass absorption have been implemented: X3 heating allows us to reduce the magnetic field by 30%, such that the first H-modes with an ITER-like value of the safety factor of q 95 = 3 could be run in the tungsten-coated device. O2 heating increases the cutoff density by a factor of 2 allowing higher currents and triangularities to be addressed. For both schemes, scenarios have been developed to cope with the associated reduced absorption. In the case of central X3 heating, the X2 resonance lies close to the pedestal top at the high-field side of the plasma, serving as a beam dump. For O2, holographic mirrors have been developed which guarantee a second pass through the plasma centre. The beam position on these reflectors is controlled by fast thermocouples. Stray-radiation protection has been implemented using sniffer probes.

Multi-frequency direct sampling method in inverse scattering problem

Science.gov (United States)

Kang, Sangwoo; Lambert, Marc; Park, Won-Kwang

2017-10-01

We consider the direct sampling method (DSM) for the two-dimensional inverse scattering problem. Although DSM is fast, stable, and effective, some phenomena remain unexplained by the existing results. We show that the imaging function of the direct sampling method can be expressed by a Bessel function of order zero. We also clarify the previously unexplained imaging phenomena and suggest multi-frequency DSM to overcome traditional DSM. Our method is evaluated in simulation studies using both single and multiple frequencies.

Influence of high energy electrons on ECRH in LHD

Directory of Open Access Journals (Sweden)

Ogasawara S.

2012-09-01

Full Text Available The central bulk electron temperature of more than 20 keV is achieved in LHD as a result of increasing the injection power and the lowering the electron density near 2 × 1018 m−3. Such collision-less regime is important from the aspect of the neoclassical transport and also the potential structure formation. The presences of appreciable amount of high energy electrons are indicated from hard X-ray PHA, and the discrepancy between the stored energy and kinetic energy estimated from Thomson scattering. ECE spectrum are also sensitive to the presence of high energy electrons and discussed by solving the radiation transfer equation. The ECRH power absorption to the bulk and the high energy electrons are dramatically affected by the acceleration and the confinement of high energy electrons. The heating mechanisms and the acceleration process of high energy electrons are discussed by comparing the experimental results and the ray tracing calculation under assumed various density and mean energy of high energy electrons.

Frequency locking of a field-widened Michelson interferometer based on optimal multi-harmonics heterodyning.

Science.gov (United States)

Cheng, Zhongtao; Liu, Dong; Zhou, Yudi; Yang, Yongying; Luo, Jing; Zhang, Yupeng; Shen, Yibing; Liu, Chong; Bai, Jian; Wang, Kaiwei; Su, Lin; Yang, Liming

2016-09-01

A general resonant frequency locking scheme for a field-widened Michelson interferometer (FWMI), which is intended as a spectral discriminator in a high-spectral-resolution lidar, is proposed based on optimal multi-harmonics heterodyning. By transferring the energy of a reference laser to multi-harmonics of different orders generated by optimal electro-optic phase modulation, the heterodyne signal of these multi-harmonics through the FWMI can reveal the resonant frequency drift of the interferometer very sensitively within a large frequency range. This approach can overcome the locking difficulty induced by the low finesse of the FWMI, thus contributing to excellent locking accuracy and lock acquisition range without any constraint on the interferometer itself. The theoretical and experimental results are presented to verify the performance of this scheme.

Multi-frequency acoustic metasurface for extraordinary reflection and sound focusing

Directory of Open Access Journals (Sweden)

Yi-Fan Zhu

2016-12-01

Full Text Available We theoretically and numerically present the design of multi-frequency acoustic metasurfaces (MFAMs with simple structure that can work not only at fundamental frequency, but also at their harmonic frequencies, which breaks the single frequency limitation in conventional resonance-based acoustic metasurfaces. The phase matched condition for achromatic manipulation is discussed. We demonstrate achromatic extraordinary reflection and sound focusing at 1700Hz, 3400Hz, and 5100Hz, that is, they have the same reflection direction and the same focusing position. This significant feature may pave the way to new type of acoustic metasurface, and will also extend acoustic metasurface applications to strongly nonlinear source cases.

Low power fast settling multi-standard current reusing CMOS fractional-N frequency synthesizer

International Nuclear Information System (INIS)

Lou Wenfeng; Feng Peng; Wang Haiyong; Wu Nanjian

2012-01-01

A low power fast settling multi-standard CMOS fractional-N frequency synthesizer is proposed. The current reusing and frequency presetting techniques are adopted to realize the low power fast settling multi-standard fractional-N frequency synthesizer. An auxiliary non-volatile memory (NVM) is embedded to avoid the repetitive calibration process and to save power in practical application. This PLL is implemented in a 0.18 μm technology. The frequency range is 0.3 to 2.54 GHz and the settling time is less than 5 μs over the entire frequency range. The LC-VCO with the stacked divide-by-2 has a good figure of merit of −193.5 dBc/Hz. The measured phase noise of frequency synthesizer is about −115 dBc/Hz at 1 MHz offset when the carrier frequency is 2.4 GHz and the reference spurs are less than −52 dBc. The whole frequency synthesizer consumes only 4.35 mA and 1.8 V. (semiconductor integrated circuits)

Remote Control System of the TJ-II Microwave Transmission Lines Mirrors; Sistema de Control Remoto de los Espejos de las Lineas de Transmision de Microondas del TJ-II

Energy Technology Data Exchange (ETDEWEB)

Lopez Sanchez, A.; Fernandez, A.; Cappa, A.; Gama, J. de la; Olivares, J.; Garcia, R.; Chamorro, M.

2007-09-27

The ECRH system of the TJ-II stellarator has two gyrotrons, which deliver a maximum power of 300 kW each at a frequency of 53.2 GHz. Another 28 GHz gyrotron will be used to heat the plasma by electron Bernstein waves (EBWH). The microwave power is transmitted from the gyrotrons to the vacuum chamber by two quasi-optical transmission lines for ECRH and a corrugated waveguide for EBWH. All transmission lines have an internal movable mirror inside the vacuum chamber to focus the beam and to be able to change the launching angle. The control of the beam polarization is very important and the lines have two corrugated mirrors, which actuate as polarizers. In this report the control system of the position of these three internal mirrors and the polarizers of the EBWH transmission line is described. (Author) 20 refs.

Radio frequency heating of fusion plasms

International Nuclear Information System (INIS)

Swanson, D.G.

1983-01-01

The electron cyclotron range of frequencies has been used successfully for plasma heating perhaps longer than any other RF plasma heating scheme and is generally well understood. The problem has always been that the strong magnetic field required for fusion devices puts the electron cyclotron frequency so high that it is at or above the high power technology limit. The development of high power gyrotrons (> 200 kW) in recent years with steadily rising frequency limits, however, has brought about a renaissance of interest in ECRH as relativistic electron energies well in excess of those required for fusion have been obtained. The relativistic electron ring stabilization of the Elmo Bumpy Torus (EBT), which was achieved with ECRF, only at one point made the EBT the most promising new fusion concept of the last decade. The results also made clear that the physical understanding of the heating processes in this frequency range, so long neglected because of the technology limitation, are not fully understood so that more basic physics is necessary before ECRF can reach the potential that technology now seems to allow

Multi-frequencies ECT algorithms to remove sodium noise in ISI of ferromagnetic SG tubes of FBR

International Nuclear Information System (INIS)

Mihalache, Ovidiu

2012-01-01

The paper presents developments and application of multi-frequency eddy current to be used during In-Service Inspection (ISI) of ferromagnetic steam generator (SG) tubes of Fast Breeder Reactors (FBR). Signal enhancement by means of multi-frequency ECT techniques are validated through 3D simulations of both signals and noise due to sodium forms around SG tube or SP. The purpose of such algorithms is to remove from ECT signal the electromagnetic noise resulting from sodium accumulated outside of SG tubes after SG vessel draining. Finite element method (FEM) simulations are used to analyse different sodium build-up scenarios observed experimentally, and to determine optimal multi-frequency ECT algorithms to suppress the most efficiently sodium noise. Also a new 'window multi-frequency' algorithm is applied and validated using 3-dimensional FEM simulations of SP and sodium forms. (author)

A 3D tunable and multi-frequency graphene plasmonic cloak

KAUST Repository

Farhat, Mohamed; Rockstuhl, Carsten; Bagci, Hakan

2013-01-01

We demonstrate the possibility of cloaking three-dimensional objects at multi-frequencies in the far-infrared part of the spectrum. The proposed cloaking mechanism exploits graphene layers wrapped around the object to be concealed. Graphene layers

Position control of ECRH launcher mirrors by laser speckle sensor

International Nuclear Information System (INIS)

Michelsen, Poul K.; Bindslev, Henrik; Hansen, Rene Skov; Hanson, Steen G.

2003-01-01

The planned ECRH system for JET included several fixed and steerable mirrors some of which should have been fixed to the building structure and some to the JET vessel structure. A similar system may be anticipated for ITER and for other fusion devices in the future. In order to have high reproducibility of the ECRH beam direction, it is necessary to know the exact positions of the mirrors. This is not a trivial problem because of thermal expansion of the vessel structures and of the launcher itself and of its support structure, the mechanical load on mirrors and support structures, and the accessibility to the various mirrors. We suggest to use a combination of infrared diagnostic of beam spot positions and a new technique published recently, which is based on a non-contact laser speckle sensor for measuring one- and two-dimensional angular displacement. The method is based on Fourier transforming the scattered field from a single laser beam that illuminates the target. The angular distribution of the light field at the target is linearly mapped onto an array image sensor placed in the Fourier plane. Measuring the displacement of this so-called speckle pattern facilitates the determination of the mirror orientation. Transverse target movement can be measured by observing the speckle movement in the image plane of the object. No special surface treatment is required for surfaces having irregularities of the order of or larger than the wavelength of the incident light. For the JET ECRH launcher it is mainly for the last mirror pointing towards the plasma where the technique may be useful. This mirror has to be steerable in order to reflect the microwave beam in the correct direction towards the plasma. Maximum performance of the microwave heating requires that the beam hits this mirror at its centre and that the mirror is turned in the correct angle. Inaccuracies in the positioning of the pull rods for controlling the mirror turning and thermal effects makes it

Vibration and acoustic frequency spectra for industrial process modeling using selective fusion multi-condition samples and multi-source features

Science.gov (United States)

Tang, Jian; Qiao, Junfei; Wu, ZhiWei; Chai, Tianyou; Zhang, Jian; Yu, Wen

2018-01-01

Frequency spectral data of mechanical vibration and acoustic signals relate to difficult-to-measure production quality and quantity parameters of complex industrial processes. A selective ensemble (SEN) algorithm can be used to build a soft sensor model of these process parameters by fusing valued information selectively from different perspectives. However, a combination of several optimized ensemble sub-models with SEN cannot guarantee the best prediction model. In this study, we use several techniques to construct mechanical vibration and acoustic frequency spectra of a data-driven industrial process parameter model based on selective fusion multi-condition samples and multi-source features. Multi-layer SEN (MLSEN) strategy is used to simulate the domain expert cognitive process. Genetic algorithm and kernel partial least squares are used to construct the inside-layer SEN sub-model based on each mechanical vibration and acoustic frequency spectral feature subset. Branch-and-bound and adaptive weighted fusion algorithms are integrated to select and combine outputs of the inside-layer SEN sub-models. Then, the outside-layer SEN is constructed. Thus, "sub-sampling training examples"-based and "manipulating input features"-based ensemble construction methods are integrated, thereby realizing the selective information fusion process based on multi-condition history samples and multi-source input features. This novel approach is applied to a laboratory-scale ball mill grinding process. A comparison with other methods indicates that the proposed MLSEN approach effectively models mechanical vibration and acoustic signals.

Sparse frequencies data inversion and the role of multi-scattered energy

KAUST Repository

Alkhalifah, Tariq Ali

2017-05-26

In trying to extract a broad spectrum of model wavenumbers from the data, necessary to build a plausible model of the Earth, we are, in theory, bounded at the high end by the diffraction resolution limit, which is proportional to the highest usable frequency in the data. At the low end, and courtesy of our multi-dimensional acquisition, the principles behind diffraction tomography theoretically extend our range to zero-wavenumbers, mainly provided by transmissions like diving waves. Within certain regions of the subsurface (i.e. deep), we face the prospective of having a model wavenumber gap in representing the velocity. Here, I demonstrate that inverting for multi scattered energy, we can recover additional wavenumbers not provided by single scattering gradients, that may feed the high and low ends of the model wavenumber spectrum, as well as help us fill in the infamous intermediate wavenumber gap. Thus, I outline a scenario in which we acquire dedicated sparse frequency data, allowing for more time to inject more energy of those frequencies at a reduced cost. Such additional energy is necessary to the recording of more multi-scattered events. The objective of this new paradigm is a high resolution model of the Earth.

Analysis of a multi-frequency electromagnetic imaging functional for thin, crack-like electromagnetic inclusions

OpenAIRE

Park, Won-Kwang

2012-01-01

Recently, a non-iterative multi-frequency subspace migration imaging algorithm was developed based on an asymptotic expansion formula for thin, curve-like electromagnetic inclusions and the structure of singular vectors in the Multi-Static Response (MSR) matrix. The present study examines the structure of subspace migration imaging functional and proposes an improved imaging functional weighted by the frequency. We identify the relationship between the imaging functional and Bessel functions ...

Use of multi-frequency, multi-polarization, multi-angle airborne radars for class discrimination in a southern temperature forest

Science.gov (United States)

Mehta, N. C.

1984-01-01

The utility of radar scatterometers for discrimination and characterization of natural vegetation was investigated. Backscatter measurements were acquired with airborne multi-frequency, multi-polarization, multi-angle radar scatterometers over a test site in a southern temperate forest. Separability between ground cover classes was studied using a two-class separability measure. Very good separability is achieved between most classes. Longer wavelength is useful in separating trees from non-tree classes, while shorter wavelength and cross polarization are helpful for discrimination among tree classes. Using the maximum likelihood classifier, 50% overall classification accuracy is achieved using a single, short-wavelength scatterometer channel. Addition of multiple incidence angles and another radar band improves classification accuracy by 20% and 50%, respectively, over the single channel accuracy. Incorporation of a third radar band seems redundant for vegetation classification. Vertical transmit polarization is critically important for all classes.

The O-X-B mode conversion scheme for ECRH of a high-density Tokamak plasma

DEFF Research Database (Denmark)

Hansen, F. R.; Lynov, Jens-Peter; Michelsen, Poul

1985-01-01

A method to apply electron cyclotron resonance heating (ECRH) to a Tokamak plasma with central density higher than the critical density for cut-off of the ordinary mode (O-mode) has been investigated. This method involves two mode conversions, from an O-mode via an extraordinary mode (X......-mode) into an electron Bernstein mode (B-mode). Radial profiles for the power deposition and the wave-drive current due to the B-waves are calculated for realistic antenna radiation patterns with parameters corresponding to the Danish DANTE Tokamak and to Princeton's PLT....

Multi-frequency complex network from time series for uncovering oil-water flow structure.

Science.gov (United States)

Gao, Zhong-Ke; Yang, Yu-Xuan; Fang, Peng-Cheng; Jin, Ning-De; Xia, Cheng-Yi; Hu, Li-Dan

2015-02-04

Uncovering complex oil-water flow structure represents a challenge in diverse scientific disciplines. This challenge stimulates us to develop a new distributed conductance sensor for measuring local flow signals at different positions and then propose a novel approach based on multi-frequency complex network to uncover the flow structures from experimental multivariate measurements. In particular, based on the Fast Fourier transform, we demonstrate how to derive multi-frequency complex network from multivariate time series. We construct complex networks at different frequencies and then detect community structures. Our results indicate that the community structures faithfully represent the structural features of oil-water flow patterns. Furthermore, we investigate the network statistic at different frequencies for each derived network and find that the frequency clustering coefficient enables to uncover the evolution of flow patterns and yield deep insights into the formation of flow structures. Current results present a first step towards a network visualization of complex flow patterns from a community structure perspective.

Power system low frequency oscillation monitoring and analysis based on multi-signal online identification

Institute of Scientific and Technical Information of China (English)

无

2010-01-01

The advance in the wide-area measurement system (WAMS) is driving the power system to the trend of wide-area monitoring and control.The Prony method is usually used for low frequency oscillation online identification.However,the identified amplitude and phase information is not sufficiently used.In this paper,the amplitude is adopted to detect the occurrence of the oscillation and to obtain the mode observability of the sites.The phase is adopted to identify the oscillation generator grouping and to obtain the mode shapes.The time varying characteristics of low frequency oscillations are studied.The behaviors and the characters of low frequency oscillations are displayed by dynamic visual techniques.Demonstrations on the "11.9" low frequency oscillation of the Guizhou Power Grid substantiate the feasibility and the validation of the proposed methods.

A near infra-red video system as a protective diagnostic for electron cyclotron resonance heating operation in the Wendelstein 7-X stellarator

Energy Technology Data Exchange (ETDEWEB)

Preynas, M.; Laqua, H. P.; Marsen, S.; Reintrog, A. [Max-Planck-Institut für Plasmaphysik (IPP), D-17491 Greifswald (Germany); Corre, Y.; Moncada, V.; Travere, J.-M. [IRFM, CEA-Cadarache, 13108 Saint Paul lez Durance Cedex (France)

2015-11-15

The Wendelstein 7-X stellarator is a large nuclear fusion device based at Max-Planck-Institut für Plasmaphysik in Greifswald in Germany. The main plasma heating system for steady state operation in W7-X is electron cyclotron resonance heating (ECRH). During operation, part of plama facing components will be directly heated by the non-absorbed power of 1 MW rf beams of ECRH. In order to avoid damages of such components made of graphite tiles during the first operational phase, a near infra-red video system has been developed as a protective diagnostic for safe and secure ECRH operation. Both the mechanical design housing the camera and the optical system are very flexible and respect the requirements of steady state operation. The full system including data acquisition and control system has been successfully tested in the vacuum vessel, including on-line visualization and data storage of the four cameras equipping the ECRH equatorial launchers of W7-X.

Decentralized model predictive based load frequency control in an interconnected power system

Energy Technology Data Exchange (ETDEWEB)

Mohamed, T.H., E-mail: tarekhie@yahoo.co [High Institute of Energy, South Valley University (Egypt); Bevrani, H., E-mail: bevrani@ieee.or [Dept. of Electrical Engineering and Computer Science, University of Kurdistan (Iran, Islamic Republic of); Hassan, A.A., E-mail: aahsn@yahoo.co [Faculty of Engineering, Dept. of Electrical Engineering, Minia University, Minia (Egypt); Hiyama, T., E-mail: hiyama@cs.kumamoto-u.ac.j [Dept. of Electrical Engineering and Computer Science, Kumamoto University, Kumamoto (Japan)

2011-02-15

This paper presents a new load frequency control (LFC) design using the model predictive control (MPC) technique in a multi-area power system. The MPC technique has been designed such that the effect of the uncertainty due to governor and turbine parameters variation and load disturbance is reduced. Each local area controller is designed independently such that stability of the overall closed-loop system is guaranteed. A frequency response model of multi-area power system is introduced, and physical constraints of the governors and turbines are considered. The model was employed in the MPC structures. Digital simulations for both two and three-area power systems are provided to validate the effectiveness of the proposed scheme. The results show that, with the proposed MPC technique, the overall closed-loop system performance demonstrated robustness in the face of uncertainties due to governors and turbines parameters variation and loads disturbances. A performance comparison between the proposed controller and a classical integral control scheme is carried out confirming the superiority of the proposed MPC technique.

Decentralized model predictive based load frequency control in an interconnected power system

International Nuclear Information System (INIS)

Mohamed, T.H.; Bevrani, H.; Hassan, A.A.; Hiyama, T.

2011-01-01

This paper presents a new load frequency control (LFC) design using the model predictive control (MPC) technique in a multi-area power system. The MPC technique has been designed such that the effect of the uncertainty due to governor and turbine parameters variation and load disturbance is reduced. Each local area controller is designed independently such that stability of the overall closed-loop system is guaranteed. A frequency response model of multi-area power system is introduced, and physical constraints of the governors and turbines are considered. The model was employed in the MPC structures. Digital simulations for both two and three-area power systems are provided to validate the effectiveness of the proposed scheme. The results show that, with the proposed MPC technique, the overall closed-loop system performance demonstrated robustness in the face of uncertainties due to governors and turbines parameters variation and loads disturbances. A performance comparison between the proposed controller and a classical integral control scheme is carried out confirming the superiority of the proposed MPC technique.

REMOTE CONTROLLING OF AN AGRICULTURAL PUMP SYSTEM BASED ON THE DUAL TONE MULTI-FREQUENCY (DTMF TECHNIQUE

Directory of Open Access Journals (Sweden)

BEZA N. GETU

2015-10-01

Full Text Available In modern days, as a result of advances in technology, human beings are interested to remotely control different systems and applications. In this work, telephone signalling technique using Dual Tone Multi-Frequency (DTMF signalling, is used to control switching of electrical loads such as agricultural pumps located in remote areas. A DTMF tone command sent from a transmitting fixed or mobile phone terminal will be used to SWITCH ON/OFF the motors used to pump water for agricultural fields. A processing electronic system at the receiving side is designed to interpret the tone commands and sends an appropriate signal to the motor driving circuit to complete the pump switching states. In the design methodology, it is possible to control several water pumps distributed in a certain agricultural site, however, in this work we considered four pumps and the paper presents the complete electronic design and simulation results at the different stages of the design. The electronic design is based on discrete passive and active electronic components and the system is tested and simulated using Multism program. The results of the simulation show that the design is capable of controlling the switching state of the motors. For a certain DTMF command, it is possible to switch ON/OFF a specific motor pump or all of the four motors.

Bubble dynamics under acoustic excitation with multiple frequencies

International Nuclear Information System (INIS)

Zhang, Y N; Zhang, Y N; Li, S C

2015-01-01

Because of its magnificent mechanical and chemical effects, acoustic cavitation plays an important role in a broad range of biomedical, chemical and mechanical engineering problems. Particularly, irradiation of the multiple frequency acoustic wave could enhance the effects of cavitation. The advantages of employment of multi-frequency ultrasonic field include decreasing the cavitation thresholds, promoting cavitation nuclei generation, increasing the mass transfer and improving energy efficiency. Therefore, multi-frequency ultrasonic systems are employed in a variety of applications, e.g., to enhance the intensity of sonoluminenscence, to increase efficiency of sonochemical reaction, to improve the accuracy of ultrasound imaging and the efficiency of tissue ablation. Compared to single-frequency systems, a lot of new features of bubble dynamics exist in multi-frequency systems, such as special properties of oscillating bubbles, unique resonances in the bubble response curves, and unusual chaotic behaviours. In present paper, the underlying mechanisms of the cavitation effects under multi-frequency acoustical excitation are also briefly introduced

Multi-carrier transmission for hybrid radio frequency with optical wireless communications

Science.gov (United States)

Wang, Gang; Chen, Genshe; Shen, Dan; Pham, Khanh; Blasch, Erik; Nguyen, Tien M.

2015-05-01

Radio frequency (RF) wireless communication is reaching its capacity to support large data rate transmissions due to hardware constraints (e.g., silicon processes), software strategies (e.g., information theory), and consumer desire for timely large file exchanges (e.g., big data and mobile cloud computing). A high transmission rate performance must keep pace with the generated huge volumes of data for real-time processing. Integrated RF and optical wireless communications (RF/OWC) could be the next generation transmission technology to satisfy both the increased data rate exchange and the communications constraints. However, with the promising benefits of RF/OWC, challenges remain to fully develop hybrid RF with wireless optical communications such as uniform waveform design for information transmission and detection. In this paper, an orthogonal frequency division multiplexing (OFDM) transmission scheme, which widely employed in RF communications, is developed for optical communications. The traditional high peak-to-average power ratio (PAPR) in OFDM is reduced to improve system performance. The proposed multi-carrier waveform is evaluated with a frequency-selective fading channel. The results demonstrate that bit error rate (BER) performance of our proposed optical OFDM transmission technique outperforms the traditional OWC on-off keying (OOK) transmission scheme.

Multi-frequency Defect Selective Imaging via Nonlinear Ultrasound

Science.gov (United States)

Solodov, Igor; Busse, Gerd

The concept of defect-selective ultrasonic nonlinear imaging is based on visualization of strongly nonlinear inclusions in the form of localized cracked defects. For intense excitation, the ultrasonic response of defects is affected by mechanical constraint between their fragments that makes their vibrations extremely nonlinear. The cracked flaws, therefore, efficiently generate multiple new frequencies, which can be used as a nonlinear "tag" to detect and image them. In this paper, the methodologies of nonlinear scanning laser vibrometry (NSLV) and nonlinear air-coupled emission (NACE) are applied for nonlinear imaging of various defects in hi-tech and constructional materials. A broad database obtained demonstrates evident advantages of the nonlinear approach over its linear counterpart. The higher-order nonlinear frequencies provide increase in signal-to-noise ratio and enhance the contrast of imaging. Unlike conventional ultrasonic instruments, the nonlinear approach yields abundant multi-frequency information on defect location. The application of image recognition and processing algorithms is described and shown to improve reliability and quality of ultrasonic imaging.

Summary of ECRH experimental session (S3)

International Nuclear Information System (INIS)

Riviere, A.C.

1980-01-01

ECRH has been successful in heating several tokamaks but not more than 200 kW has been used in any experiment so far. The absorption efficiency is in qualitative agreement with theory but it is not accurately known and, in most cases, the polarisation of the heating wave is not well defined, either due to the effect of wall scattering or due to the character of the wave that is launched. Experiments in FT-1 show an improvement in absorption efficiency when the X-mode is launched from the high field rather than low field side thus avoiding the evanescent layer. In ISX-B the measured absorption (60% +- 15%) during heating is consistent with that expected theoretically (75%) for the assumed mixture of O and X-mode. More or less complete absorption is observed in the large hot plasma in T-10 at the second harmonic, again as expected. In these experiments there is no evidence for generation of new impurities or run-away electrons during heating. However a 15% decrease in electron density is observed in ISX-B. The reason for this is not clear but may be due either to a direct effect of the heating wave on particle transport or to a change in the flux of neutrals at the boundary of the plasma. (author)

[Study on spectral gain characterization of FWM processes with multi-frequency pumps in photonic crystal fiber].

Science.gov (United States)

Hui, Zhan-Qiang

2011-10-01

Spectral gain induced by four-wave-mixing with multi-frequency pump was investigated by exploiting the data signal and continue lights co-propagation in dispersion flattened high nonlinear photonic crystal fiber (PCF). The effects of wavelength drift of pump lights, polarization state of orthogonal or parallel of pump lights, polarization mismatch of signal light versus orthogonal pump lights, total power of signal and probe light on the spectrum gain were analyzed. The results show that good FWM gain effects with multi-frequency pump can be obtained in 36.4 nm wavelength range when power ratio of pump to probe light is appropriate and with identical polarization. Furthermore, the gain of FWM with multi-frequency pump is very sensitive to polarization fluctuation and the different idle waves obtain different gain with the variation in signal polarization state. Moreover, the impact of pump numbers was investigated. The obtained results would be helpful for further research on ultrahigh-speed all optical signal processing devices exploiting the FWM with multi-frequency pump in PCF for future photonics network.

Digital frequency offset-locked He–Ne laser system with high beat frequency stability, narrow optical linewidth and optical fibre output

Science.gov (United States)

Sternkopf, Christian; Manske, Eberhard

2018-06-01

We report on the enhancement of a previously-presented heterodyne laser source on the basis of two phase-locked loop (PLL) frequency coupled internal-mirror He–Ne lasers. Our new system consists of two digitally controlled He–Ne lasers with slightly different wavelengths, and offers high-frequency stability and very narrow optical linewidth. The digitally controlled system has been realized by using a FPGA controller and transconductance amplifiers. The light of both lasers was coupled into separate fibres for heterodyne interferometer applications. To enhance the laser performance we observed the sensitivity of both laser tubes to electromagnetic noise from various laser power supplies and frequency control systems. Furthermore, we describe how the linewidth of a frequency-controlled He–Ne laser can be reduced during precise frequency stabilisation. The digitally controlled laser source reaches a standard beat frequency deviation of less than 20 Hz (with 1 s gate time) and a spectral full width at half maximum (FWHM) of the beat signal less than 3 kHz. The laser source has enough optical output power to serve a fibre-coupled multi axis heterodyne interferometer. The system can be adjusted to output beat frequencies in the range of 0.1 MHz–20 MHz.

Multi-frequency time-difference complex conductivity imaging of canine and human lungs using the KHU Mark1 EIT system

International Nuclear Information System (INIS)

Kuen, Jihyeon; Woo, Eung Je; Seo, Jin Keun

2009-01-01

We evaluated the performance of the lately developed electrical impedance tomography (EIT) system KHU Mark1 through time-difference imaging experiments of canine and human lungs. We derived a multi-frequency time-difference EIT (mftdEIT) image reconstruction algorithm based on the concept of the equivalent homogeneous complex conductivity. Imaging experiments were carried out at three different frequencies of 10, 50 and 100 kHz with three different postures of right lateral, sitting (or prone) and left lateral positions. For three normal canine subjects, we controlled the ventilation using a ventilator at three tidal volumes of 100, 150 and 200 ml. Three human subjects were asked to breath spontaneously at a normal tidal volume. Real- and imaginary-part images of the canine and human lungs were reconstructed at three frequencies and three postures. Images showed different stages of breathing cycles and we could interpret them based on the understanding of the proposed mftdEIT image reconstruction algorithm. Time series of images were further analyzed by using the functional EIT (fEIT) method. Images of human subjects showed the gravity effect on air distribution in two lungs. In the canine subjects, the morphological change seems to dominate the gravity effect. We could also observe that two different types of ventilation should have affected the results. The KHU Mark1 EIT system is expected to provide reliable mftdEIT images of the human lungs. In terms of the image reconstruction algorithm, it would be worthwhile including the effects of three-dimensional current flows inside the human thorax. We suggest clinical trials of the KHU Mark1 for pulmonary applications

Multi-frequency time-difference complex conductivity imaging of canine and human lungs using the KHU Mark1 EIT system.

Science.gov (United States)

Kuen, Jihyeon; Woo, Eung Je; Seo, Jin Keun

2009-06-01

We evaluated the performance of the lately developed electrical impedance tomography (EIT) system KHU Mark1 through time-difference imaging experiments of canine and human lungs. We derived a multi-frequency time-difference EIT (mftdEIT) image reconstruction algorithm based on the concept of the equivalent homogeneous complex conductivity. Imaging experiments were carried out at three different frequencies of 10, 50 and 100 kHz with three different postures of right lateral, sitting (or prone) and left lateral positions. For three normal canine subjects, we controlled the ventilation using a ventilator at three tidal volumes of 100, 150 and 200 ml. Three human subjects were asked to breath spontaneously at a normal tidal volume. Real- and imaginary-part images of the canine and human lungs were reconstructed at three frequencies and three postures. Images showed different stages of breathing cycles and we could interpret them based on the understanding of the proposed mftdEIT image reconstruction algorithm. Time series of images were further analyzed by using the functional EIT (fEIT) method. Images of human subjects showed the gravity effect on air distribution in two lungs. In the canine subjects, the morphological change seems to dominate the gravity effect. We could also observe that two different types of ventilation should have affected the results. The KHU Mark1 EIT system is expected to provide reliable mftdEIT images of the human lungs. In terms of the image reconstruction algorithm, it would be worthwhile including the effects of three-dimensional current flows inside the human thorax. We suggest clinical trials of the KHU Mark1 for pulmonary applications.

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

NARCIS (Netherlands)

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

2015-01-01

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

Experiments on hot-electron ECRH in the Tandem Mirror Experiment-Upgrade

International Nuclear Information System (INIS)

Stallard, B.W.

1983-01-01

Experiments have begun on the Tandem Mirror Experiment Upgrade (TMX-U) using electron-cyclotron resonant heating (ECRH) to generate the hot electron populations required for thermal barrier operation (Energy E/sub eh/ approx. 50 keV, density n/sub eh/ 12 , and hot-to-cold fraction n/sub eh/n approx. 0.9). For this operation, rf power produced by 28-GHz gyrotrons is injected with extraordinary mode polarization at both fundamental and second harmonic locations. Our initial experiments, which concentrated on startup of the hot electrons, were carried out at low density ( 12 cm - 3 ) where Fokker-Planck calculations predict high heating efficiency when the electron temperature (T/sub e/) is low. Under these conditions, we produced substantial hot electron populations (diamagnetic energy > 400 J, E/sub eh/ in the range of 15 to 50 keV, and n/sub eh//n > 0.5)

Sparse frequencies data inversion and the role of multi-scattered energy

KAUST Repository

Alkhalifah, Tariq Ali

2017-01-01

time to inject more energy of those frequencies at a reduced cost. Such additional energy is necessary to the recording of more multi-scattered events. The objective of this new paradigm is a high resolution model of the Earth.

Angle-of-arrival-based gesture recognition using ultrasonic multi-frequency signals

KAUST Repository

Chen, Hui; Ballal, Tarig; Saad, Mohamed; Al-Naffouri, Tareq Y.

2017-01-01

transducer. The 2-D angles of the moving hand are estimated using multi-frequency signals captured by a fixed receiver array. A simple redundant dictionary matching classifier is designed to recognize gestures representing the numbers from `0' to `9

Progress of the 10 MW ECRH System for W7-X

International Nuclear Information System (INIS)

Michel, G.; Brand, P.; Dammertz, G.

2003-01-01

The electron cyclotron resonance heating system for the W7-X stellarator is a joint effort of the Max-Planck-Institut fuer Plasmaphysik in Greifswald, the Institut fuer Plasmaforschung Stuttgart and the Forschungszentrum Karlsruhe under the supervision of the latter. Currently it is being constructed at the Greifswald branch of IPP. It will consist of 10 gyrotrons (each with 1 MW 140 GHz in the CW regime) and a quasi optical multi-beam transmission line. W7-X gyrotron candidates are being developed separately in Western Europe and the USA. The prototype phase of the gyrotrons is almost over and significant results have been achieved. The manufacturing of the transmission line is ongoing. An overview over the system including data acquisition and control issues will be given and the current status of the construction will be presented. (authors)

The DECMU: a digital device for delayed analysis of multi-frequency eddy current signals

International Nuclear Information System (INIS)

Pigeon, Michel.

1981-08-01

A delayed data analysis system has been realized by the CEA and Intercontrole for in-service inspection of steam generators of nuclear plants by multifrequency eddy current testing. This device allows, out of the plant, adjustment during switching of the probes, graph recording and analysis for defect signal qualification. The equipment contains an analog mixing device, as IC3FA multi-frequency appartus, but has in addition a memory allowing data cycling and signal isolation for adjustment or analysis [fr

Successful application of frequency-domain airborne electromagnetic system with a grounded electric source

Science.gov (United States)

Kang, L.; Lin, J.; Liu, C.; Zhou, H.; Ren, T.; Yao, Y.

2017-12-01

A new frequency-domain AEM system with a grounded electric source, which was called ground-airborne frequency-domain electromagnetic (GAFEM) system, was proposed to extend penetration depth without compromising the resolution and detection efficiency. In GAFEM system, an electric source was placed on the ground to enlarge the strength of response signals. UVA was chosen as aircraft to reduce interaction noise and improve its ability to adapt to complex terrain. Multi-source and multi-frequency emission method has been researched and applied to improve the efficiency of GAFEM system. 2n pseudorandom sequence was introduced as transmitting waveform, to ensure resolution and detection efficiency. Inversion-procedure based on full-space apparent resistivity formula was built to realize GAFEM method and extend the survey area to non-far field. Based on GAFEM system, two application was conducted in Changchun, China, to map the deep conductive structure. As shown in the results of this exploration, GAFEM system shows its effectiveness to conductive structure, obtaining a depth of about 1km with a source-receiver distance of over 6km. And it shows the same level of resolution with CSAMT method with an over 10 times of efficiency. This extended a range of important applications where the terrain is too complex to be accessed or large penetration depth is required in a large survey area.

Dynamical Consensus Algorithm for Second-Order Multi-Agent Systems Subjected to Communication Delay

International Nuclear Information System (INIS)

Liu Chenglin; Liu Fei

2013-01-01

To solve the dynamical consensus problem of second-order multi-agent systems with communication delay, delay-dependent compensations are added into the normal asynchronously-coupled consensus algorithm so as to make the agents achieve a dynamical consensus. Based on frequency-domain analysis, sufficient conditions are gained for second-order multi-agent systems with communication delay under leaderless and leader-following consensus algorithms respectively. Simulation illustrates the correctness of the results. (interdisciplinary physics and related areas of science and technology)

Multi-frequency bioimpedance in equine muscle assessment

International Nuclear Information System (INIS)

Harrison, Adrian Paul; Elbrønd, Vibeke Sødring; Riis-Olesen, Kiwa; Bartels, Else Marie

2015-01-01

Multi-frequency BIA (mfBIA) equipment has been shown to be a non-invasive and reliable method to assess a muscle as a whole or at fibre level. In the equine world this may be the future method of assessment of training condition or of muscle injury. The aim of this study was to test if mfBIA reliably can be used to assess the condition of a horse’s muscles in connection with health assessment, injury and both training and re-training. mfBIA measurements was carried out on 10 ‘hobby’ horses and 5 selected cases with known anamnesis. Impedance, resistance, reactance, phase angle, centre frequency, membrane capacitance and both extracellular and intracellular resistance were measured. Platinum electrodes in connection with a conductance paste were used to accommodate the typical BIA frequencies and to facilitate accurate measurements. Use of mfBIA data to look into the effects of myofascial release treatment was also demonstrated. Our findings indicate that mfBIA provides a non-invasive, easily measurable and very precise assessment of the state of muscles in horses. This study also shows the potential of mfBIA as a diagnostic tool as well as a tool to monitor effects of treatment e.g. myofascial release therapy and metabolic diseases, respectively. (paper)

Electron velocity-space diffusion in a micro-unstable ECRH [electron cyclotron resonance heated] mirror plasma

International Nuclear Information System (INIS)

Hokin, S.A.

1987-09-01

An experimental study of the velocity-space diffusion of electrons in an electron cyclotron resonance heated (ECRH) mirror plasma, in the presence of micro-unstable whistler rf emission, is presented. It is found that the dominant loss mechanism for hot electrons is endloss produced by rf diffusion into the mirror loss cone. In a standard case with 4.5 kW of ECRH power, this loss limits the stored energy to 120 J with an energy confinement time of 40 ms. The energy confinement time associated with collisional scattering is 350 ms in this case. Whistler microinstability rf produces up to 25% of the rf-induced loss. The hot electron temperature is not limited by loss of adiabaticity, but by rf-induced loss of high energy electrons, and decreases with increasing rf power in strong diffusion regimes. Collisional loss is in agreement with standard scattering theory. No super-adiabatic effects are clearly seen. Experiments in which the vacuum chamber walls are lined with microwave absorber reveal that single pass absorption is limited to less than 60%, whereas experiments with reflecting walls exhibit up to 90% absorption. Stronger diffusion is seen in the latter, with a hot electron heating rate which is twice that of the absorber experiments. This increase in diffusion can be produced by two distinct aspects of wall-reflected rf: the broader spatial rf profile, which enlarges the resonant region in velocity space, or a reduction in super-adiabatic effects due to randomization of the electron gyrophase. Since no other aspects of super-adiabaticity are observed, the first mechanism appears more likely. 39 refs., 54 figs

Fast convergent frequency-domain MIMO equalizer for few-mode fiber communication systems

Science.gov (United States)

He, Xuan; Weng, Yi; Wang, Junyi; Pan, Z.

2018-02-01

Space division multiplexing using few-mode fibers has been extensively explored to sustain the continuous traffic growth. In few-mode fiber optical systems, both spatial and polarization modes are exploited to transmit parallel channels, thus increasing the overall capacity. However, signals on spatial channels inevitably suffer from the intrinsic inter-modal coupling and large accumulated differential mode group delay (DMGD), which causes spatial modes de-multiplex even harder. Many research articles have demonstrated that frequency domain adaptive multi-input multi-output (MIMO) equalizer can effectively compensate the DMGD and demultiplex the spatial channels with digital signal processing (DSP). However, the large accumulated DMGD usually requires a large number of training blocks for the initial convergence of adaptive MIMO equalizers, which will decrease the overall system efficiency and even degrade the equalizer performance in fast-changing optical channels. Least mean square (LMS) algorithm is always used in MIMO equalization to dynamically demultiplex the spatial signals. We have proposed to use signal power spectral density (PSD) dependent method and noise PSD directed method to improve the convergence speed of adaptive frequency domain LMS algorithm. We also proposed frequency domain recursive least square (RLS) algorithm to further increase the convergence speed of MIMO equalizer at cost of greater hardware complexity. In this paper, we will compare the hardware complexity and convergence speed of signal PSD dependent and noise power directed algorithms against the conventional frequency domain LMS algorithm. In our numerical study of a three-mode 112 Gbit/s PDM-QPSK optical system with 3000 km transmission, the noise PSD directed and signal PSD dependent methods could improve the convergence speed by 48.3% and 36.1% respectively, at cost of 17.2% and 10.7% higher hardware complexity. We will also compare the frequency domain RLS algorithm against

Fusion plasma theory Task II: ECRH and transport modeling in tandem mirrors and divertor physics. Final report, January 1-December 31, 1985

International Nuclear Information System (INIS)

Emmert, G.A.

1985-07-01

The research reported here focuses on: (1) the coupling of an ECRH ray tracing and absorption code to a tandem mirror transport code in order to self-consistently model the temporal and spatial evolution of the plasma, and (2) the further development of semi-analytical models for plasma flow in divertors and pumped limiters. 5 refs., 1 fig

CRPP's Evacuated Waveguide Proposal for JET-EP ECRH Transmission Line

International Nuclear Information System (INIS)

Henderson, M. A.; Alberti, S.; Goodman, T. P.; Hogge, J.-P.; Porte, L.; Tran, M. Q.

2002-01-01

The goal of this document is to provide a detailed description of the preliminary design and technical information of a proposed evacuated transmission lines for JET . EP ECRH system. Three waveguide diameters (31.75mm, 45mm and 63.5mm) were studied and compared to the base design of the 87mm waveguide/quasi.optical proposal (WG87-QO). This report concentrates on only the 45mm waveguide diameter (WG45). This size represents an optimization between the flexibility of the smaller diameter and the low loss of the larger. For simplicity only the WG45 will be compared with the WG87-QO, but the other diameters (31.75 and 63.5 mm) should be kept under consideration for a final evacuated waveguide line. The characteristics of the 63.5 mm waveguide system can be found in the report which was distributed in September. After an introduction of the history and motivation for this study a general overview of the proposal is presented. Sections 4 and 5 describe the elements to be used in the proposed line including the overall transmission losses for the line. Section 6 offers a cost comparison of the two proposaIs. The 7th section is a brief description of an alternative launcher design using the waveguide inserted into the launcher port. The 8th section describes the ca1ibration and conditioning process to be performed after the line is insta1led and how the torus displacements wi1l be handled. The 9th section describes the proposed schedule for purchasing and insta1lation of the waveguide lines. Sections II and 12 include a conclusion and summary of the proposal. (author)

A Novel Tunable Multi-Frequency Hybrid Vibration Energy Harvester Using Piezoelectric and Electromagnetic Conversion Mechanisms

Directory of Open Access Journals (Sweden)

Zhenlong Xu

2016-01-01

Full Text Available This paper presents a novel tunable multi-frequency hybrid energy harvester (HEH. It consists of a piezoelectric energy harvester (PEH and an electromagnetic energy harvester (EMEH, which are coupled with magnetic interaction. An electromechanical coupling model was developed and numerically simulated. The effects of magnetic force, mass ratio, stiffness ratio, and mechanical damping ratios on the output power were investigated. A prototype was fabricated and characterized by experiments. The measured first peak power increases by 16.7% and 833.3% compared with that of the multi-frequency EMEH and the multi-frequency PEH, respectively. It is 2.36 times more than the combined output power of the linear PEH and linear EMEH at 22.6 Hz. The half-power bandwidth for the first peak power is also broadened. Numerical results agree well with the experimental data. It is indicated that magnetic interaction can tune the resonant frequencies. Both magnetic coupling configuration and hybrid conversion mechanism contribute to enhancing the output power and widening the operation bandwidth. The magnitude and direction of magnetic force have significant effects on the performance of the HEH. This proposed HEH is an effective approach to improve the generating performance of the micro-scale energy harvesting devices in low-frequency range.

Extrapolation of the Dutch 1 MW tunable free electron maser to a 5 MW ECRH source

International Nuclear Information System (INIS)

Caplan, M.; Nelson, S.; Kamin, G.; Antonsen, T. Levush, B.; Urbanus, W.; Tulupov, A.

1995-01-01

A Free Electron Maser (FEM) is now under construction at the FOM Institute (Rijnhuizen) Netherlands with the goal of producing 1 MW long pulse to CW microwave output in the range 130 GHz to 250 GHz with wall plug efficiencies of 50% (Verhoeven, et al EC-9 Conference). An extrapolated version of this device is proposed which by scaling up the beam current, would produce microwave power levels of up to 5 MW CW in order to reduce the cost per watt and increase the power per module, thus providing the fusion community with a practical ECRH source

A novel approach to study effects of asymmetric stiffness on parametric instabilities of multi-rotor-system

Science.gov (United States)

Jain, Anuj Kumar; Rastogi, Vikas; Agrawal, Atul Kumar

2018-01-01

The main focus of this paper is to study effects of asymmetric stiffness on parametric instabilities of multi-rotor-system through extended Lagrangian formalism, where symmetries are broken in terms of the rotor stiffness. The complete insight of dynamic behaviour of multi-rotor-system with asymmetries is evaluated through extension of Lagrangian equation with a case study. In this work, a dynamic mathematical model of a multi-rotor-system through a novel approach of extension of Lagrangian mechanics is developed, where the system is having asymmetries due to varying stiffness. The amplitude and the natural frequency of the rotor are obtained analytically through the proposed methodology. The bond graph modeling technique is used for modeling the asymmetric rotor. Symbol-shakti® software is used for the simulation of the model. The effects of the stiffness of multi-rotor-system on amplitude and frequencies are studied using numerical simulation. Simulation results show a considerable agreement with the theoretical results obtained through extended Lagrangian formalism. It is further shown that amplitude of the rotor increases inversely the stiffness of the rotor up to a certain limit, which is also affirmed theoretically.

Experimental modal analysis of fractal-inspired multi-frequency structures for piezoelectric energy converters

International Nuclear Information System (INIS)

Castagnetti, D

2012-01-01

An important issue in the field of energy harvesting through piezoelectric materials is the design of simple and efficient structures which are multi-frequency in the ambient vibration range. This paper deals with the experimental assessment of four fractal-inspired multi-frequency structures for piezoelectric energy harvesting. These structures, thin plates of square shape, were proposed in a previous work by the author and their modal response numerically analysed. The present work has two aims. First, to assess the modal response of these structures through an experimental investigation. Second, to evaluate, through computational simulation, the performance of a piezoelectric converter relying on one of these fractal-inspired structures. The four fractal-inspired structures are examined in the range between 0 and 100 Hz, with regard to both eigenfrequencies and eigenmodes. In the same frequency range, the modal response and power output of the piezoelectric converter are investigated. (paper)

Stochastic resonance in multi-stable coupled systems driven by two driving signals

Science.gov (United States)

Xu, Pengfei; Jin, Yanfei

2018-02-01

The stochastic resonance (SR) in multi-stable coupled systems subjected to Gaussian white noises and two different driving signals is investigated in this paper. Using the adiabatic approximation and the perturbation method, the coupled systems with four-well potential are transformed into the master equations and the amplitude of the response is obtained. The signal-to-noise ratio (SNR) is calculated numerically to demonstrate the occurrence of SR. For the case of two driving signals with different amplitudes, the interwell resonance between two wells S1 and S3 emerges for strong coupling. The SR can appear in the subsystem with weaker signal amplitude or even without driving signal with the help of coupling. For the case of two driving signals with different frequencies, the effects of SR in two subsystems driven by high and low frequency signals are both weakened with an increase in coupling strength. The stochastic multi-resonance phenomenon is observed in the subsystem subjected to the low frequency signal. Moreover, an effective scheme for phase suppressing SR is proposed by using a relative phase between two driving signals.

Robust multi-model control of an autonomous wind power system

Energy Technology Data Exchange (ETDEWEB)

Cutululis, Nicolas Antonio; Hansen, Anca Daniela; Soerensen, Poul [Risoe National Lab., Wind Energy Dept., Roskilde (Denmark); Ceanga, Emil [' Dunarea de Jos' Univ., Faculty of Electrical Engineering, Galati (Romania)

2006-07-01

This article presents a robust multi-model control structure for a wind power system that uses a variable speed wind turbine (VSWT) driving a permanent magnet synchronous generator (PMSG) connected to a local grid. The control problem consists in maximizing the energy captured from the wind for varying wind speeds. The VSWT-PMSG linearized model analysis reveals the resonant nature of its dynamic at points on the optimal regimes characteristic (ORC). The natural frequency of the system and the damping factor are strongly dependent on the operating point on the ORC. Under these circumstances a robust multi-model control structure is designed. The simulation results prove the viability of the proposed control structure. (Author)

Robust multi-model control of an autonomous wind power system

Science.gov (United States)

Cutululis, Nicolas Antonio; Ceanga, Emil; Hansen, Anca Daniela; Sørensen, Poul

2006-09-01

This article presents a robust multi-model control structure for a wind power system that uses a variable speed wind turbine (VSWT) driving a permanent magnet synchronous generator (PMSG) connected to a local grid. The control problem consists in maximizing the energy captured from the wind for varying wind speeds. The VSWT-PMSG linearized model analysis reveals the resonant nature of its dynamic at points on the optimal regimes characteristic (ORC). The natural frequency of the system and the damping factor are strongly dependent on the operating point on the ORC. Under these circumstances a robust multi-model control structure is designed. The simulation results prove the viability of the proposed control structure. Copyright

Controlling the optical bistability beyond the multi-photon resonance condition in a three-level closed-loop atomic system

International Nuclear Information System (INIS)

Mahmoudi, Mohammad; Nozari, Narges; Vafafard, Azar; Sahrai, Mostafa

2012-01-01

We investigate the optical bistability behavior of a three-level closed-loop atomic system beyond the multi-photon resonance condition. Using the Floquet decomposition, we solve the time-dependent equations of motion, beyond the multi-photon resonance condition. By identifying the different scattering processes contributing to the medium response, it is shown that in general the optical bistability behavior of the system is not phase-dependent. The phase dependence is due to the scattering of the driving and coupling fields into the probe field at a frequency, which, in general, differs from the probe field frequency. - Highlights: → We investigate optical bistability of a three-level closed-loop atomic system, beyond the multi-photon resonance condition. → By applying Floquet decomposition to the equation of motion, the different scattering processes contributing to the medium response are determined. → It is shown that the phase dependence of optical bistability arises from the scattering of the driving and coupling fields into the probe field frequency.

Optimization of measurement methods for a multi-frequency electromagnetic field from mobile phone base station using broadband EMF meter

Directory of Open Access Journals (Sweden)

Paweł Bieńkowski

2015-10-01

Full Text Available Background: This paper presents the characteristics of the mobile phone base station (BS as an electromagnetic field (EMF source. The most common system configurations with their construction are described. The parameters of radiated EMF in the context of the access to methods and other parameters of the radio transmission are discussed. Attention was also paid to antennas that are used in this technology. Material and Methods: The influence of individual components of a multi-frequency EMF, most commonly found in the BS surroundings, on the resultant EMF strength value indicated by popular broadband EMF meters was analyzed. The examples of metrological characteristics of the most common EMF probes and 2 measurement scenarios of the multisystem base station, with and without microwave relays, are shown. Results: The presented method for measuring the multi-frequency EMF using 2 broadband probes allows for the significant minimization of measurement uncertainty. Equations and formulas that can be used to calculate the actual EMF intensity from multi-frequency sources are shown. They have been verified in the laboratory conditions on a specific standard setup as well as in real conditions in a survey of the existing base station with microwave relays. Conclusions: Presented measurement methodology of multi-frequency EMF from BS with microwave relays, validated both in laboratory and real conditions. It has been proven that the described measurement methodology is the optimal approach to the evaluation of EMF exposure in BS surrounding. Alternative approaches with much greater uncertainty (precaution method or more complex measuring procedure (sources exclusion method are also presented. Med Pr 2015;66(5:701–712

[Optimization of measurement methods for a multi-frequency electromagnetic field from mobile phone base station using broadband EMF meter].

Science.gov (United States)

Bieńkowski, Paweł; Cała, Paweł; Zubrzak, Bartłomiej

2015-01-01

This paper presents the characteristics of the mobile phone base station (BS) as an electromagnetic field (EMF) source. The most common system configurations with their construction are described. The parameters of radiated EMF in the context of the access to methods and other parameters of the radio transmission are discussed. Attention was also paid to antennas that are used in this technology. The influence of individual components of a multi-frequency EMF, most commonly found in the BS surroundings, on the resultant EMF strength value indicated by popular broadband EMF meters was analyzed. The examples of metrological characteristics of the most common EMF probes and 2 measurement scenarios of the multisystem base station, with and without microwave relays, are shown. The presented method for measuring the multi-frequency EMF using 2 broadband probes allows for the significant minimization of measurement uncertainty. Equations and formulas that can be used to calculate the actual EMF intensity from multi-frequency sources are shown. They have been verified in the laboratory conditions on a specific standard setup as well as in real conditions in a survey of the existing base station with microwave relays. Presented measurement methodology of multi-frequency EMF from BS with microwave relays, validated both in laboratory and real conditions. It has been proven that the described measurement methodology is the optimal approach to the evaluation of EMF exposure in BS surrounding. Alternative approaches with much greater uncertainty (precaution method) or more complex measuring procedure (sources exclusion method) are also presented). This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Ultra high vacuum compatible microwave beam launcher for ECRH in SST - 1

International Nuclear Information System (INIS)

Shukla, B.K.; Sathyanarayana, K.; Biswas, P.; Pragnesh, D.; Bora, D.

2005-01-01

Microwave beam launcher for Electron Cyclotron Resonance Heating (ECRH) system is used to focus the microwave beam at plasma center of SST -1. The beam launcher consists of an ultra high vacuum (UHV) compatible mirror box with two mirrors mounted in it. One mirror is focusing mirror while other one is a plane mirror. The total volume of the launcher is ∼ 60000 cc and the total surface area exposed to UHV is around ∼ 1.0x10 4 cm 2 . The mirrors are cooled with water for high power and long pulse operation. UHV compatible SS hoses provide flexible cooling connection to the mirrors. Flexible cooling connection helps in adjustment and steering of the mirrors. SS hoses are welded at both the ends and this is necessary to avoid any flange connection inside ultra high vacuum. The system has been tested for UHV compatibility. The leak rate is checked with helium leak detector and found better than l x 10 -9 mbar.lt/s. The system has been baked to 150 deg C for ∼14 hours and the ultimate vacuum achieved with turbomolecular pump (TMP) is ∼ 5x10 -9 mbar. The mirror assembly is tested for leak in pressurized condition using a sniffer probe. The mirrors of the launcher along with the welded bellow are pressurized with helium gas up to a water equivalent pressure of ∼3kg/cm 2 . No increase in the background (∼-10 -6 mbar.lt/s) of the sniffer probes has been observed during the test. The plane mirror is connected with two UHV linear motion feedthroughs with suitable hinges and smooth movement is checked in vacuum. (author)

Design of a remote steering antenna for ECRH heating in the stellarator Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

Plaum, B., E-mail: plaum@igvp.uni-stuttgart.de [Institut für Grenzflächenverfahrenstechnik und Plasmatechnologie (IGVP), Univ. Stuttgart, Pfaffenwaldring 31, D-70569 Stuttgart (Germany); Lechte, C.; Kasparek, W.; Gaiser, S.; Zeitler, A. [Institut für Grenzflächenverfahrenstechnik und Plasmatechnologie (IGVP), Univ. Stuttgart, Pfaffenwaldring 31, D-70569 Stuttgart (Germany); Erckmann, V. [Max-Planck-Institut für Plasmaphysik, EURATOM-IPP, D-17491 Greifswald (Germany); Weißgerber, M. [Max-Planck-Institut für Plasmaphysik, EURATOM-IPP, D-85748 Garching (Germany); Bechtold, A. [NTG Neue Technologie GmbH & Co KG, D-63571 Gelnhausen (Germany); Busch, M.; Szcepaniak, B. [Galvano-T electroplating-electroforming GmbH, D-51570 Windeck-Rosbach (Germany)

2015-10-15

Highlights: • We report about the design activities for the remote steering antennas for the stellarator W7-X. • The integration into the W7-X system and the manufacturing procedure are described. • Simulations and loss measurements for the waveguide walls were done and are in good agreement. • A method for extending the steering range is presented. • A mechanical deformation analysis showed that the deformation is not critical for the beam quality. - Abstract: For the ECRH heating system of the stellarator Wendelstein 7-X, two remote steering antennas are developed and manufactured. The principle of remote steering antennas is based on the imaging characteristics of corrugated rectangular waveguides, which is well understood and can accurately be simulated. Several details, however, require deeper investigation. The antenna needs a miter-bend and a 24 mm gap. The positions of these elements need to be chosen carefully to reduce losses and stray radiation. The antennas are manufactured from copper by electroforming. This allows to integrate all components, including the corrugated inner walls and the cooling channels, in one vacuum-tight piece. This paper reviews the design process of the remote steering antennas for W7-X as well as technological issues and experimental results from test pieces.

A Novel Secondary Control for Microgrid Based on Synergetic Control of Multi-Agent System

Directory of Open Access Journals (Sweden)

Zhiwen Yu

2016-03-01

Full Text Available In power systems, the secondary control is a very useful way to restore the system frequency and voltage to the rated value. This paper tries to propose a secondary frequency and voltage control of islanded microgrids based on the distributed synergetic control of multi-agent systems. In the proposed control, since each distributed generation only requires its own information and that of the neighbors, the secondary control is fully distributed. The system is more reliable because the central controller and complex communication network are reduced in the distributed structure. Based on multi-agent systems, the dynamic model is established, and distributed synergetic control algorithms are given to design the secondary control of the islanded microgrid. Meanwhile, the system has globally asymptotic stability under the proposed control, which is proved by the direct Lyapunov method. Simulation results about a test microgrid are given to verify the effectiveness of the proposed control.

Measurement of anisotropic soft X-ray emission during radio-frequency current drive in the JFT-2M tokamak

International Nuclear Information System (INIS)

Kawashima, Hisato; Matoba, Tohru; Hoshino, Katsumichi; Kawakami, Tomohide; Yamamoto, Takumi; Hasegawa, Mitsuru; Fuchs, Gerhard; Uesugi, Yoshihiko.

1994-01-01

A new vertical soft X-ray pulse height analyzer (PHA) system and a tangential PHA system were used to measure the anisotropy of soft X-ray emission during lower-hybrid current drive (LHCD) and also during current drive by the combination of LHCD and electron cyclotron resonance heating (ECRH) in the JFT-2M tokamak. The strong soft X-ray emission was measured in the parallel forward direction during LHCD. When ECRH was applied during LHCD, the perpendicular emission was enhanced. The high-energy electron velocity distribution was evaluated by comparing the measured and calculated X-ray spectra. The distribution form was consistent with the theoretical prediction based on the electron Landau damping of lower-hybrid waves and the electron cyclotron damping of electron cyclotron waves for reasonable energy ranges. (author)

Symplicity multi-electrode radiofrequency renal denervation system feasibility study.

Science.gov (United States)

Whitbourn, Robert; Harding, Scott A; Walton, Antony

2015-05-01

The aim of this study was to test the safety and performance of the Symplicity™ multi-electrode radio-frequency renal denervation system which was designed to reduce procedure time during renal denervation. The multi-electrode radiofrequency renal denervation system feasibility study is a prospective, non-randomised, open label, feasibility study that enrolled 50 subjects with hypertension. The study utilises a new renal denervation catheter which contains an array of four electrodes mounted in a helical configuration at 90 degrees from each other to deliver radiofrequency energy simultaneously to all four renal artery quadrants for 60 seconds. The protocol specified one renal denervation treatment towards the distal end of each main renal artery with radiofrequency energy delivered for 60 seconds per treatment. Total treatment time for both renal arteries was two minutes. The 12-month change in office systolic blood pressure (SBP) and 24-hour SBP was -19.2±25.2 mmHg, prenal artery stenosis or hypertensive emergencies occurred. The Symplicity multi-electrode radiofrequency renal denervation system was associated with a significant reduction in SBP at 12 months and minimal complications whilst it also reduced procedure time. NCT01699529.

Frequency-domain and time-domain methods for feedback nonlinear systems and applications to chaos control

International Nuclear Information System (INIS)

Duan Zhisheng; Wang Jinzhi; Yang Ying; Huang Lin

2009-01-01

This paper surveys frequency-domain and time-domain methods for feedback nonlinear systems and their possible applications to chaos control, coupled systems and complex dynamical networks. The absolute stability of Lur'e systems with single equilibrium and global properties of a class of pendulum-like systems with multi-equilibria are discussed. Time-domain and frequency-domain criteria for the convergence of solutions are presented. Some latest results on analysis and control of nonlinear systems with multiple equilibria and applications to chaos control are reviewed. Finally, new chaotic oscillating phenomena are shown in a pendulum-like system and a new nonlinear system with an attraction/repulsion function.

Flattened optical frequency-locked multi-carrier generation by cascading one DML and one phase modulator driven by different RF frequency clocks

International Nuclear Information System (INIS)

Li, Xinying; Yu, Jianjun; Zhang, Junwen; Chi, Nan

2013-01-01

We propose a novel scheme for flattened optical frequency-locked multi-carrier generation based on one directly modulated laser (DML) and one phase modulator (PM) in cascade driven by different sinusoidal radio-frequency (RF) clocks. We experimentally demonstrate that when the clock frequencies for the cascaded DML and the PM are respectively 12.5 GHz and 25 GHz, over 24 optical subcarriers can be generated with 12.5-GHz frequency spacing and amplitude fluctuation less than 3 dB. Furthermore, the number of generated optical subcarriers can be further increased when we increase the driving power for the DML. (letter)

Modeling Multi-Level Systems

CERN Document Server

Iordache, Octavian

2011-01-01

This book is devoted to modeling of multi-level complex systems, a challenging domain for engineers, researchers and entrepreneurs, confronted with the transition from learning and adaptability to evolvability and autonomy for technologies, devices and problem solving methods. Chapter 1 introduces the multi-scale and multi-level systems and highlights their presence in different domains of science and technology. Methodologies as, random systems, non-Archimedean analysis, category theory and specific techniques as model categorification and integrative closure, are presented in chapter 2. Chapters 3 and 4 describe polystochastic models, PSM, and their developments. Categorical formulation of integrative closure offers the general PSM framework which serves as a flexible guideline for a large variety of multi-level modeling problems. Focusing on chemical engineering, pharmaceutical and environmental case studies, the chapters 5 to 8 analyze mixing, turbulent dispersion and entropy production for multi-scale sy...

Simultaneous reconstruction of permittivity and conductivity using multi-frequency admittance measurement in electrical capacitance tomography

International Nuclear Information System (INIS)

Zhang, Maomao; Soleimani, Manuchehr

2016-01-01

Electrical capacitance tomography (ECT) is an imaging method mainly capable of reconstructing dielectric permittivity. Generally, the reactance part of complex admittance is measured in a selected frequency. This paper presents for the first time an in depth and systematic analysis of complex admittance data for simultaneous reconstruction of both electrical conductivity and dielectric permittivity. A complex-valued forward model, Jacobian matrix and inverse solution are developed in the time harmonic excitation mode to allow for multi-frequency measurements. Realistic noise models are used to evaluate the performance of complex admittance ECT in a range of excitation frequencies. This paper demonstrates far greater potential for ECT as a versatile imaging tool through novel analysis of complex admittance imaging using a dual conductivity permittivity inversion method. The paper demonstrates that various classes of contactless capacitance based measurement devices can be analysed through complex multi-frequency ECT. (paper)

Computational imaging with multi-camera time-of-flight systems

KAUST Repository

Shrestha, Shikhar

2016-07-11

Depth cameras are a ubiquitous technology used in a wide range of applications, including robotic and machine vision, human computer interaction, autonomous vehicles as well as augmented and virtual reality. In this paper, we explore the design and applications of phased multi-camera time-of-flight (ToF) systems. We develop a reproducible hardware system that allows for the exposure times and waveforms of up to three cameras to be synchronized. Using this system, we analyze waveform interference between multiple light sources in ToF applications and propose simple solutions to this problem. Building on the concept of orthogonal frequency design, we demonstrate state-of-the-art results for instantaneous radial velocity capture via Doppler time-of-flight imaging and we explore new directions for optically probing global illumination, for example by de-scattering dynamic scenes and by non-line-of-sight motion detection via frequency gating. © 2016 ACM.

Leakage based precoding for multi-user MIMO-OFDM systems

KAUST Repository

Sadek, Mirette

2011-08-01

In downlink multi-user multiple-input multiple-output (MIMO) transmissions, several precoding schemes have been proposed to decrease interference among users. Notable among these precoding schemes is one that uses the signal-to-leakage-plus-noise ratio (SLNR) as an optimization criterion. In this paper, leveraging the efficiency of the SLNR optimization, we generalize this precoding scheme to MIMO orthogonal frequency division multiplexing (OFDM) multi-user systems where the OFDM is used to overcome the inter-symbol- interference (ISI) introduced by multipath channels. We also introduce a channel compensation technique that reconstructs the channel at the transmitter for every time instant given a significantly lower channel feedback rate by the receiver. © 2006 IEEE.

Thrombolysis using multi-frequency high intensity focused ultrasound at MHz range: an in vitro study

International Nuclear Information System (INIS)

Suo, Dingjie; Guo, Sijia; Jiang, Xiaoning; Jing, Yun; Lin, Weili

2015-01-01

High intensity focused ultrasound (HIFU) based thrombolysis has emerged as a promising drug-free treatment approach for ischemic stroke. The large amount of acoustic power required by this approach, however, poses a critical challenge to the future clinical translation. In this study, multi-frequency acoustic waves at MHz range (near 1.5 MHz) were introduced as HIFU excitations to reduce the required power for treatment as well as the treatment time. In vitro bovine blood clots weighing around 150 mg were treated by single-frequency and multi-frequency HIFU. The pulse length was 2 ms for all experiments except the ones where the duty cycle was changed. It was found that dual-frequency thrombolysis efficiency was statistically better than single-frequency under the same acoustic power and excitation condition. When varying the acoustic power but fixing the duty cycle at 5%, it was found that dual-frequency ultrasound can save almost 30% power in order to achieve the same thrombolysis efficiency. In the experiment where the duty cycle was increased from 0.5% to 10%, it was shown that dual-frequency ultrasound can achieve the same thrombolysis efficiency with only half of the duty cycle of single-frequency. Dual-frequency ultrasound could also accelerate the thrombolysis by a factor of 2–4 as demonstrated in this study. No significant differences were found between dual-frequencies with different frequency differences (0.025, 0.05, and 0.1 MHz) and between dual-frequency and triple-frequency. The measured cavitation doses of dual-frequency and triple-frequency excitations were at about the same level but both were significantly higher than that of single-frequency. (paper)

Galvanically Decoupled Current Source Modules for Multi-Channel Bioimpedance Measurement Systems

Directory of Open Access Journals (Sweden)

Roman Kusche

2017-10-01

Full Text Available Bioimpedance measurements have become a useful technique in the past several years in biomedical engineering. Especially, multi-channel measurements facilitate new imaging and patient monitoring techniques. While most instrumentation research has focused on signal acquisition and signal processing, this work proposes the design of an excitation current source module that can be easily implemented in existing or upcoming bioimpedance measurement systems. It is galvanically isolated to enable simultaneous multi-channel bioimpedance measurements with a very low channel-coupling. The system is based on a microcontroller in combination with a voltage-controlled current source circuit. It generates selectable sinusoidal excitation signals between 0.12 and 1.5 mA in a frequency range from 12 to 250 kHz, whereas the voltage compliance range is ±3.2 V. The coupling factor between two current sources, experimentally galvanically connected with each other, is measured to be less than −48 dB over the entire intended frequency range. Finally, suggestions for developments in the future are made.

Multi-Frequency Databases for AGN Investigation—Results and Perspectives

Energy Technology Data Exchange (ETDEWEB)

La Mura, Giovanni [Department of Physics and Astronomy, University of Padua, Padua (Italy); Berton, Marco [Department of Physics and Astronomy, University of Padua, Padua (Italy); Astronomical Observatory of Brera, National Institute for Astrophysics, Milan (Italy); Chen, Sina; Ciroi, Stefano [Department of Physics and Astronomy, University of Padua, Padua (Italy); Congiu, Enrico [Department of Physics and Astronomy, University of Padua, Padua (Italy); Astronomical Observatory of Brera, National Institute for Astrophysics, Milan (Italy); Cracco, Valentina; Frezzato, Michele; Rafanelli, Piero, E-mail: giovanni.lamura@unipd.it [Department of Physics and Astronomy, University of Padua, Padua (Italy)

2017-10-17

Active Galactic Nuclei (AGNs) are characterized by emission of radiation over more than 10 orders of magnitude in frequency. Therefore, the execution of extensive surveys of the sky, with different types of detectors, is providing the attractive possibility to identify and to investigate the properties of AGNs on very large statistical samples. Thanks to the large spectroscopic surveys that allow detailed investigation of many of these sources, we have the opportunity to place new constraints on the nature and evolution of AGNs and to investigate their relations with the host systems. In this contribution we present the results that can be obtained by using a new interactive catalog that we developed to investigate the range of AGN spectral energy distributions (SEDs). We present simple SED models based on data collected in the catalog and discuss their relations with optical spectra obtained by follow up observations. We compare our findings with the expectations based on the AGN Unification Model, and we discuss the perspectives of multi-wavelength approaches to address AGN related processes such as black hole accretion and acceleration of relativistic jets.

Improvement of Frequency Fluctuations in Microgrids Using an Optimized Fuzzy P-PID Controller by Modified Multi Objective Gravitational Search Algorithm

Directory of Open Access Journals (Sweden)

H. Shayeghi

2016-12-01

Full Text Available Microgrids is an new opportunity to reduce the total costs of power generation and supply the energy demands through small-scale power plants such as wind sources, photo voltaic panels, battery banks, fuel cells, etc. Like any power system in micro grid (MG, an unexpected faults or load shifting leads to frequency oscillations. Hence, this paper employs an adaptive fuzzy P-PID controller for frequency control of microgrid and a modified multi objective Chaotic Gravitational Search Algorithm (CGSA in order to find out the optimal setting parameters of the proposed controller. To provide a robust controller design, two non-commensurable objective functions are formulated based on eigenvalues-domain and time-domain and multi objective CGSA algorithm is used to solve them. Moreover, a fuzzy decision method is applied to extract the best and optimal Pareto fronts. The proposed controller is carried out on a MG system under different loading conditions with wind turbine generators, photovoltaic system, flywheel energy, battery storages, diesel generator and electrolyzer. The simulation results revealed that the proposed controller is more stable in comparison with the classical and other types of fuzzy controller.

Multi-LED parallel transmission for long distance underwater VLC system with one SPAD receiver

Science.gov (United States)

Wang, Chao; Yu, Hong-Yi; Zhu, Yi-Jun; Wang, Tao; Ji, Ya-Wei

2018-03-01

In this paper, a multiple light emitting diode (LED) chips parallel transmission (Multi-LED-PT) scheme for underwater visible light communication system with one photon-counting single photon avalanche diode (SPAD) receiver is proposed. As the lamp always consists of multi-LED chips, the data rate could be improved when we drive these multi-LED chips parallel by using the interleaver-division-multiplexing technique. For each chip, the on-off-keying modulation is used to reduce the influence of clipping. Then a serial successive interference cancellation detection algorithm based on ideal Poisson photon-counting channel by the SPAD is proposed. Finally, compared to the SPAD-based direct current-biased optical orthogonal frequency division multiplexing system, the proposed Multi-LED-PT system could improve the error-rate performance and anti-nonlinearity performance significantly under the effects of absorption, scattering and weak turbulence-induced channel fading together.

Three-dimensional ground penetrating radar imaging using multi-frequency diffraction tomography

Energy Technology Data Exchange (ETDEWEB)

Mast, J.E.; Johansson, E.M. [Lawrence Livermore National Lab., CA (United States)

1994-11-15

In this talk we present results from a three-dimensional image reconstruction algorithm for impulse radar operating in monostatic pule-echo mode. The application of interest to us is the nondestructive evaluation of civil structures such as bridge decks. We use a multi-frequency diffraction tomography imaging technique in which coherent backward propagations of the received reflected wavefield form a spatial image of the scattering interfaces within the region of interest. This imaging technique provides high-resolution range and azimuthal visualization of the subsurface region. We incorporate the ability to image in planarly layered conductive media and apply the algorithm to experimental data from an offset radar system in which the radar antenna is not directly coupled to the surface of the region. We present a rendering in three-dimensions of the resulting image data which provides high-detail visualization.

Timing system for multi-bunch/multi-train operation at ATF

International Nuclear Information System (INIS)

Naito, T.; Hayano, H.; Urakawa, J.; Imai, T.

2000-01-01

A timing system has been constructed for multi-bunch/multi-train operation at KEK-ATF. The linac accelerates 20 bunches of multi-bunch with 2.8 ns spacing. The Damping Ring stores up to 5 trains of multi-bunch. The timing system is required to provide flexible operation mode and bucket selection. A personal computer is used for manipulating the timing. The performance of kicker magnets at the injection/extruction is key issue for multi-train operation. The hardware and the test results are presented. (author)

Broadcast Communication by System Frequency Modulation

DEFF Research Database (Denmark)

Douglass, Philip James; You, Shi; Heussen, Kai

2012-01-01

Load controllers available today can measure AC system frequency and react to frequency deviations. A system operator can communicate to frequency sensitive loads by changing the set-points of the system’s dispatchable frequency regulation resources. Explicitly signaling system state by generating...... off-nominal system frequency values is a novel narrowband broadcast communications channel between system operators and frequency sensitive distributed energy resources (FS-DER). The feasibility of the proposed system is evaluated on an existing island power system in Denmark. This study shows...... that within standard frequency quality constraints, 4 distinct symbols are feasible on the island. However, the overarching imperative of system stability prevents the symbols from having arbitrary meanings. Higher frequency values must translate into greater consumption from loads, and vice versa. Within...

Low Frequency Turbulence as the Source of High Frequency Waves in Multi-Component Space Plasmas

Science.gov (United States)

Khazanov, George V.; Krivorutsky, Emmanuel N.; Uritsky, Vadim M.

2011-01-01

Space plasmas support a wide variety of waves, and wave-particle interactions as well as wavewave interactions are of crucial importance to magnetospheric and ionospheric plasma behavior. High frequency wave turbulence generation by the low frequency (LF) turbulence is restricted by two interconnected requirements: the turbulence should be strong enough and/or the coherent wave trains should have the appropriate length. These requirements are strongly relaxed in the multi-component plasmas, due to the heavy ions large drift velocity in the field of LF wave. The excitation of lower hybrid waves (LHWs), in particular, is a widely discussed mechanism of interaction between plasma species in space and is one of the unresolved questions of magnetospheric multi-ion plasmas. It is demonstrated that large-amplitude Alfven waves, in particular those associated with LF turbulence, may generate LHW s in the auroral zone and ring current region and in some cases (particularly in the inner magnetosphere) this serves as the Alfven wave saturation mechanism. We also argue that the described scenario can playa vital role in various parts of the outer magnetosphere featuring strong LF turbulence accompanied by LHW activity. Using the data from THEMIS spacecraft, we validate the conditions for such cross-scale coupling in the near-Earth "flow-braking" magnetotail region during the passage of sharp injection/dipolarization fronts, as well as in the turbulent outflow region of the midtail reconnection site.

Investigation of power and frequency for 3D conformal MRI-controlled transurethral ultrasound therapy with a dual frequency multi-element transducer.

Science.gov (United States)

N'djin, William Apoutou; Burtnyk, Mathieu; Bronskill, Michael; Chopra, Rajiv

2012-01-01

Transurethral ultrasound therapy uses real-time magnetic resonance (MR) temperature feedback to enable the 3D control of thermal therapy accurately in a region within the prostate. Previous canine studies showed the feasibility of this method in vivo. The aim of this study was to reduce the procedure time, while maintaining targeting accuracy, by investigating new combinations of treatment parameters. Simulations and validation experiments in gel phantoms were used, with a collection of nine 3D realistic target prostate boundaries obtained from previous preclinical studies, where multi-slice MR images were acquired with the transurethral device in place. Acoustic power and rotation rate were varied based on temperature feedback at the prostate boundary. Maximum acoustic power and rotation rate were optimised interdependently, as a function of prostate radius and transducer operating frequency. The concept of dual frequency transducers was studied, using the fundamental frequency or the third harmonic component depending on the prostate radius. Numerical modelling enabled assessment of the effects of several acoustic parameters on treatment outcomes. The range of treatable prostate radii extended with increasing power, and tended to narrow with decreasing frequency. Reducing the frequency from 8 MHz to 4 MHz or increasing the surface acoustic power from 10 to 20 W/cm(2) led to treatment times shorter by up to 50% under appropriate conditions. A dual frequency configuration of 4/12 MHz with 20 W/cm(2) ultrasound intensity exposure can treat entire prostates up to 40 cm(3) in volume within 30 min. The interdependence between power and frequency may, however, require integrating multi-parametric functions in the controller for future optimisations.

Angle-of-arrival-based gesture recognition using ultrasonic multi-frequency signals

KAUST Repository

Chen, Hui

2017-11-02

Hand gestures are tools for conveying information, expressing emotion, interacting with electronic devices or even serving disabled people as a second language. A gesture can be recognized by capturing the movement of the hand, in real time, and classifying the collected data. Several commercial products such as Microsoft Kinect, Leap Motion Sensor, Synertial Gloves and HTC Vive have been released and new solutions have been proposed by researchers to handle this task. These systems are mainly based on optical measurements, inertial measurements, ultrasound signals and radio signals. This paper proposes an ultrasonic-based gesture recognition system using AOA (Angle of Arrival) information of ultrasonic signals emitted from a wearable ultrasound transducer. The 2-D angles of the moving hand are estimated using multi-frequency signals captured by a fixed receiver array. A simple redundant dictionary matching classifier is designed to recognize gestures representing the numbers from `0\\' to `9\\' and compared with a neural network classifier. Average classification accuracies of 95.5% and 94.4% are obtained, respectively, using the two classification methods.

Multi-frequency bioimpedance in human muscle assessment

DEFF Research Database (Denmark)

Bartels, Else Marie; Sørensen, Emma Rudbæk; Harrison, Adrian Paul

2015-01-01

Bioimpedance analysis (BIA) is a well-known and tested method for body mass and muscular health assessment. Multi-frequency BIA (mfBIA) equipment now makes it possible to assess a particular muscle as a whole, as well as looking at a muscle at the fiber level. The aim of this study was to test...... healthy human control subjects and three selected cases were examined to demonstrate the extent to which this method may be used clinically, and in relation to training in sport. The electrode setup is shown to affect the mfBIA parameters recorded. Our recommendation is the use of noble metal electrodes......, contracted state, and cell transport/metabolic activity, which relate to muscle performance. Our findings indicate that mfBIA provides a noninvasive, easily measurable and very precise momentary assessment of skeletal muscles....

Microwave measurement test results of circular waveguide components for electron cyclotron resonant heating (ECRH) of the Tandem Mirror Experiment-Upgrade (TMX-U)

International Nuclear Information System (INIS)

Williams, C.W.; Rubert, R.R.; Coffield, F.E.; Felker, B.; Stallard, B.W.; Taska, J.

1983-01-01

Development of high-power components for electron cyclotron resonant heating (ECRH) applications requires extensive testing. In this paper we describe the high-power testing of various circular waveguide components designed for application on the Tandem Mirror Experiment-Upgrade (TMX-U). These include a 2.5-in. vacuum valve, polarizing reflectors, directional couplers, mode converters, and flexible waveguides. All of these components were tested to 200 kW power level with 40-ms pulses. Cold tests were used to determine field distribution. The techniques used in these tests are illustrated. The new high-power test facility at Lawrence Livermore National Laboratory (LLNL) is described and test procedures are discussed. We discuss the following test results: efficiency at high power of mode converters, comparison of high power vs low power for waveguide components, and full power tests of the waveguide system. We also explain the reasons behind selection of these systems for use on TMX-U

Robust fault detection for the dynamics of high-speed train with multi-source finite frequency interference.

Science.gov (United States)

Bai, Weiqi; Dong, Hairong; Yao, Xiuming; Ning, Bin

2018-04-01

This paper proposes a composite fault detection scheme for the dynamics of high-speed train (HST), using an unknown input observer-like (UIO-like) fault detection filter, in the presence of wind gust and operating noises which are modeled as disturbance generated by exogenous system and unknown multi-source disturbance within finite frequency domain. Using system input and system output measurements, the fault detection filter is designed to generate the needed residual signals. In order to decouple disturbance from residual signals without truncating the influence of faults, this paper proposes a method to partition the disturbance into two parts. One subset of the disturbance does not appear in residual dynamics, and the influence of the other subset is constrained by H ∞ performance index in a finite frequency domain. A set of detection subspaces are defined, and every different fault is assigned to its own detection subspace to guarantee the residual signals are diagonally affected promptly by the faults. Simulations are conducted to demonstrate the effectiveness and merits of the proposed method. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Active Participation of Air Conditioners in Power System Frequency Control Considering Users’ Thermal Comfort

Directory of Open Access Journals (Sweden)

Rongxiang Zhang

2015-09-01

Full Text Available Air conditioners have great potential to participate in power system frequency control. This paper proposes a control strategy to facilitate the active participation of air conditioners. For each air conditioner, a decentralized control law is designed to adjust its temperature set point in response to the system frequency deviation. The decentralized control law accounts for the user’s thermal comfort that is evaluated by a fuzzy algorithm. The aggregation of air conditioners’ response is conducted by using the Monte Carlo simulation method. A structure preserving model is applied to the multi-bus power system, in which air conditioners are aggregated at certain load buses. An inner-outer iteration scheme is adopted to solve power system dynamics. An experiment is conducted on a test air conditioner to examine the performance of the proposed decentralized control law. Simulation results on a test power system verify the effectiveness of the proposed strategy for air conditioners participating in frequency control.

Hierarchical energy and frequency security pricing in a smart microgrid: An equilibrium-inspired epsilon constraint based multi-objective decision making approach

International Nuclear Information System (INIS)

Rezaei, Navid; Kalantar, Mohsen

2015-01-01

Highlights: • Proposing a multi-objective security pricing mechanism for islanded microgrids. • Generating Pareto points using epsilon constraint methodology. • Best compromise solution using a novel decision making approach. • An equilibrium-inspired technique is used as an efficient decision making method. • Stochastic management of hierarchical reserves in a droop controlled microgrid. - Abstract: The present paper formulates a frequency security constrained energy management system for an islanded microgrid. Static and dynamic securities of the microgrids have been modeled in depth based on droop control paradigm. The derived frequency dependent modeling is incorporated into a multi-objective energy management system. Microgrid central controller is in charge to determine optimal prices of energy and frequency security such that technical, economic and environmental targets are satisfied simultaneously. The associated prices are extracted based on calculating related Lagrange multipliers corresponding to providing the microgrid hourly energy and reserve requirements. Besides, to generate optimal Pareto solutions of the proposed multi-objective framework augmented epsilon constraint method is applied. Moreover, a novel methodology on the basis of Nash equilibrium strategy is devised and employed to select the best compromise solution from the generated Pareto front. Comprehensive analysis tool is implemented in a typical test microgrid and executed over a 24 h scheduling time horizon. The energy, primary and secondary frequency control reserves have been scheduled appropriately in three different case-studies which are defined based on the microgrid various operational policies. The optimization results verify that the operational policies adopted by means of the microgrid central controller have direct impacts on determined energy and security prices. The illustrative implementations can give the microgrid central controller an insight view to provide

Multi-objective optimization of linear multi-state multiple sliding window system

International Nuclear Information System (INIS)

Konak, Abdullah; Kulturel-Konak, Sadan; Levitin, Gregory

2012-01-01

This paper considers the optimal element sequencing in a linear multi-state multiple sliding window system that consists of n linearly ordered multi-state elements. Each multi-state element can have different states: from complete failure up to perfect functioning. A performance rate is associated with each state. The failure of type i in the system occurs if for any i (1≤i≤I) the cumulative performance of any r i consecutive elements is lower than w i . The element sequence strongly affects the probability of any type of system failure. The sequence that minimizes the probability of certain type of failure can provide high probability of other types of failures. Therefore the optimization problem for the multiple sliding window system is essentially multi-objective. The paper formulates and solves the multi-objective optimization problem for the multiple sliding window systems. A multi-objective Genetic Algorithm is used as the optimization engine. Illustrative examples are presented.

Magnetic Shear and Transport in ECRH Discharges of the TJ-II under Ohmic Induction

Energy Technology Data Exchange (ETDEWEB)

Lopez-Bruna, D.; Castejon, F.; Romero, J. A.; Estrada, T.; Medina, F.; Ochando, M.; Lopez-Fraguas, A.; Ascasibar, E.; Herranz, J.; Sanchez, E.; Luna, E. de la; Pastor, I.

2006-07-01

TJ-II is ha heliac type stellarator characterised by high, but almost constant, vacuum rotational transform throughout the confining volume. In ECRH plasmas, moderate induced ohmic currents (negligible heating and modification of the magnetic field nodules) are enough to disregard the bootstrap contribution, which allows us performing a fair calculation of the evolution of the rotational transform. We use the loop voltage diagnostic to estimate the plasma electrical conductivity. Then the evolution of the rotational transform and shear is related to changes in the profiles of electron and thermal diffusivities: negative shear correlates with decreasing diffusivities in the region of steepest density gradient; transport increases toward zero shear but the achieved positive values are too small to draw conclusions. The radial sweeping of lowest order rational magnetic surfaces does not determine the observed trends in transport. (Author)43 refs.

Magnetic Shear and Transport in ECRH Discharges of the TJ-II under Ohmic Induction

International Nuclear Information System (INIS)

Lopez-Bruna, D.; Castejon, F.; Romero, J. A.; Estrada, T.; Medina, F.; Ochando, M.; Lopez-Fraguas, A.; Ascasibar, E.; Herranz, J.; Sanchez, E.; Luna, E. de la; Pastor, I.

2006-01-01

TJ-II is ha heliac type stellarator characterised by high, but almost constant, vacuum rotational transform throughout the confining volume. In ECRH plasmas, moderate induced ohmic currents (negligible heating and modification of the magnetic field nodules) are enough to disregard the bootstrap contribution, which allows us performing a fair calculation of the evolution of the rotational transform. We use the loop voltage diagnostic to estimate the plasma electrical conductivity. Then the evolution of the rotational transform and shear is related to changes in the profiles of electron and thermal diffusivities: negative shear correlates with decreasing diffusivities in the region of steepest density gradient; transport increases toward zero shear but the achieved positive values are too small to draw conclusions. The radial sweeping of lowest order rational magnetic surfaces does not determine the observed trends in transport. (Author)43 refs

Multi-agent and complex systems

CERN Document Server

Ren, Fenghui; Fujita, Katsuhide; Zhang, Minjie; Ito, Takayuki

2017-01-01

This book provides a description of advanced multi-agent and artificial intelligence technologies for the modeling and simulation of complex systems, as well as an overview of the latest scientific efforts in this field. A complex system features a large number of interacting components, whose aggregate activities are nonlinear and self-organized. A multi-agent system is a group or society of agents which interact with others cooperatively and/or competitively in order to reach their individual or common goals. Multi-agent systems are suitable for modeling and simulation of complex systems, which is difficult to accomplish using traditional computational approaches.

Digital radiography: optimization of image quality and dose using multi-frequency software.

Science.gov (United States)

Precht, H; Gerke, O; Rosendahl, K; Tingberg, A; Waaler, D

2012-09-01

New developments in processing of digital radiographs (DR), including multi-frequency processing (MFP), allow optimization of image quality and radiation dose. This is particularly promising in children as they are believed to be more sensitive to ionizing radiation than adults. To examine whether the use of MFP software reduces the radiation dose without compromising quality at DR of the femur in 5-year-old-equivalent anthropomorphic and technical phantoms. A total of 110 images of an anthropomorphic phantom were imaged on a DR system (Canon DR with CXDI-50 C detector and MLT[S] software) and analyzed by three pediatric radiologists using Visual Grading Analysis. In addition, 3,500 images taken of a technical contrast-detail phantom (CDRAD 2.0) provide an objective image-quality assessment. Optimal image-quality was maintained at a dose reduction of 61% with MLT(S) optimized images. Even for images of diagnostic quality, MLT(S) provided a dose reduction of 88% as compared to the reference image. Software impact on image quality was found significant for dose (mAs), dynamic range dark region and frequency band. By optimizing image processing parameters, a significant dose reduction is possible without significant loss of image quality.

A wireless multi-channel bioimpedance measurement system for personalized healthcare and lifestyle.

Science.gov (United States)

Ramos, Javier; Ausín, José Luis; Lorido, Antonio Manuel; Redondo, Francisco; Duque-Carrillo, Juan Francisco

2013-01-01

Miniaturized, noninvasive, wearable sensors constitute a fundamental prerequisite for pervasive, predictive, and preventive healthcare systems. In this sense, this paper presents the design, realization, and evaluation of a wireless multi-channel measurement system based on a cost-effective high-performance integrated circuit for electrical bioimpedance (EBI) measurements in the frequency range from 1 kHz to 1 MHz. The resulting on-chip spectrometer provides high measuring EBI capabilities and together with a low-cost, commercially available radio frequency transceiver device. It provides reliable wireless communication, constitutes the basic node to build EBI wireless sensor networks (EBI-WSNs). The proposed EBI-WSN behaves as a high-performance wireless multi-channel EBI spectrometer, where the number of channels is completely scalable and independently configurable to satisfy specific measurement requirements of each individual. A prototype of the EBI node leads to a very small printed circuit board of approximately 8 cm2 including chip-antenna, which can operate several years on one 3-V coin cell battery and make it suitable for long-term preventive healthcare monitoring.

SU-E-I-52: Validation of Multi-Frequency Electrical Impedance Tomography Using Computed Tomography

Energy Technology Data Exchange (ETDEWEB)

Kohli, K; Liu, F; Krishnan, K [BC Cancer Agency, Surrey, BC (United Kingdom)

2014-06-01

Purpose: Multi-frequency EIT has been reported to be a potential tool in distinguishing a tissue anomaly from background. In this study, we investigate the feasibility of acquiring functional information by comparing multi-frequency EIT images in reference to the structural information from the CT image through fusion. Methods: EIT data was acquired from a slice of winter melon using sixteen electrodes around the phantom, injecting a current of 0.4mA at 100, 66, 24.8 and 9.9 kHz. Differential EIT images were generated by considering different combinations of pair frequencies, one serving as reference data and the other as test data. The experiment was repeated after creating an anomaly in the form of an off-centered cavity of diameter 4.5 cm inside the melon. All EIT images were reconstructed using Electrical Impedance Tomography and Diffuse Optical Tomography Reconstruction Software (EIDORS) package in 2-D differential imaging mode using one-step Gaussian Newton minimization solver. CT image of the melon was obtained using a Phillips CT Scanner. A segmented binary mask image was generated based on the reference electrode position and the CT image to define the regions of interest. The region selected by the user was fused with the CT image through logical indexing. Results: Differential images based on the reference and test signal frequencies were reconstructed from EIT data. Result illustrated distinct structural inhomogeneity in seeded region compared to fruit flesh. The seeded region was seen as a higherimpedance region if the test frequency was lower than the base frequency in the differential EIT reconstruction. When the test frequency was higher than the base frequency, the signal experienced less electrical impedance in the seeded region during the EIT data acquisition. Conclusion: Frequency-based differential EIT imaging can be explored to provide additional functional information along with structural information from CT for identifying different tissues.

SU-E-I-52: Validation of Multi-Frequency Electrical Impedance Tomography Using Computed Tomography

International Nuclear Information System (INIS)

Kohli, K; Liu, F; Krishnan, K

2014-01-01

Purpose: Multi-frequency EIT has been reported to be a potential tool in distinguishing a tissue anomaly from background. In this study, we investigate the feasibility of acquiring functional information by comparing multi-frequency EIT images in reference to the structural information from the CT image through fusion. Methods: EIT data was acquired from a slice of winter melon using sixteen electrodes around the phantom, injecting a current of 0.4mA at 100, 66, 24.8 and 9.9 kHz. Differential EIT images were generated by considering different combinations of pair frequencies, one serving as reference data and the other as test data. The experiment was repeated after creating an anomaly in the form of an off-centered cavity of diameter 4.5 cm inside the melon. All EIT images were reconstructed using Electrical Impedance Tomography and Diffuse Optical Tomography Reconstruction Software (EIDORS) package in 2-D differential imaging mode using one-step Gaussian Newton minimization solver. CT image of the melon was obtained using a Phillips CT Scanner. A segmented binary mask image was generated based on the reference electrode position and the CT image to define the regions of interest. The region selected by the user was fused with the CT image through logical indexing. Results: Differential images based on the reference and test signal frequencies were reconstructed from EIT data. Result illustrated distinct structural inhomogeneity in seeded region compared to fruit flesh. The seeded region was seen as a higherimpedance region if the test frequency was lower than the base frequency in the differential EIT reconstruction. When the test frequency was higher than the base frequency, the signal experienced less electrical impedance in the seeded region during the EIT data acquisition. Conclusion: Frequency-based differential EIT imaging can be explored to provide additional functional information along with structural information from CT for identifying different tissues

Cyber security with radio frequency interferences mitigation study for satellite systems

Science.gov (United States)

Wang, Gang; Wei, Sixiao; Chen, Genshe; Tian, Xin; Shen, Dan; Pham, Khanh; Nguyen, Tien M.; Blasch, Erik

2016-05-01

Satellite systems including the Global Navigation Satellite System (GNSS) and the satellite communications (SATCOM) system provide great convenience and utility to human life including emergency response, wide area efficient communications, and effective transportation. Elements of satellite systems incorporate technologies such as navigation with the global positioning system (GPS), satellite digital video broadcasting, and information transmission with a very small aperture terminal (VSAT), etc. The satellite systems importance is growing in prominence with end users' requirement for globally high data rate transmissions; the cost reduction of launching satellites; development of smaller sized satellites including cubesat, nanosat, picosat, and femtosat; and integrating internet services with satellite networks. However, with the promising benefits, challenges remain to fully develop secure and robust satellite systems with pervasive computing and communications. In this paper, we investigate both cyber security and radio frequency (RF) interferences mitigation for satellite systems, and demonstrate that they are not isolated. The action space for both cyber security and RF interferences are firstly summarized for satellite systems, based on which the mitigation schemes for both cyber security and RF interferences are given. A multi-layered satellite systems structure is provided with cross-layer design considering multi-path routing and channel coding, to provide great security and diversity gains for secure and robust satellite systems.

Pilot-Assisted Channel Estimation for Orthogonal Multi-Carrier DS-CDMA with Frequency-Domain Equalization

Science.gov (United States)

Shima, Tomoyuki; Tomeba, Hiromichi; Adachi, Fumiyuki

Orthogonal multi-carrier direct sequence code division multiple access (orthogonal MC DS-CDMA) is a combination of time-domain spreading and orthogonal frequency division multiplexing (OFDM). In orthogonal MC DS-CDMA, the frequency diversity gain can be obtained by applying frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion to a block of OFDM symbols and can improve the bit error rate (BER) performance in a severe frequency-selective fading channel. FDE requires an accurate estimate of the channel gain. The channel gain can be estimated by removing the pilot modulation in the frequency domain. In this paper, we propose a pilot-assisted channel estimation suitable for orthogonal MC DS-CDMA with FDE and evaluate, by computer simulation, the BER performance in a frequency-selective Rayleigh fading channel.

Regulated open multi-agent systems (ROMAS) a multi-agent approach for designing normative open systems

CERN Document Server

Garcia, Emilia; Botti, Vicente

2015-01-01

Addressing the open problem of engineering normative open systems using the multi-agent paradigm, normative open systems are explained as systems in which heterogeneous and autonomous entities and institutions coexist in a complex social and legal framework that can evolve to address the different and often conflicting objectives of the many stakeholders involved. Presenting  a software engineering approach which covers both the analysis and design of these kinds of systems, and which deals with the open issues in the area, ROMAS (Regulated Open Multi-Agent Systems) defines a specific multi-agent architecture, meta-model, methodology and CASE tool. This CASE tool is based on Model-Driven technology and integrates the graphical design with the formal verification of some properties of these systems by means of model checking techniques. Utilizing tables to enhance reader insights into the most important requirements for designing normative open multi-agent systems, the book also provides a detailed and easy t...

System Frequency as Information Carrier in AC Power Systems

DEFF Research Database (Denmark)

Douglass, Philip James; Heussen, Kai; You, Shi

2015-01-01

Power generators contain control systems able to regulate system frequency, but the frequency setpoint values are only rarely modified from nominal values. This paper describes design considerations for a communication system from generators to frequency sensitive distributed energy resourc es (FS......-DER) using changes to frequency setpoint values of genera- tors. Signaling discrete system states by generating off-nominal system frequency values can be used as a novel narrowband unidirectional broadcast communications channel. This paper describes two protocols for utilizing off-nominal frequencies...... to carry information: First, a protocol for dispatching blocks of FS- DER that is suitable for systems restricted to relatively slow rates of change of frequency (ROCOF). Second, for systems that allow higher ROCOF values, the feasibility of using power generation resources as a power line communication...

Multi-criteria objective based climate change impact assessment for multi-purpose multi-reservoir systems

Science.gov (United States)

Müller, Ruben; Schütze, Niels

2014-05-01

Water resources systems with reservoirs are expected to be sensitive to climate change. Assessment studies that analyze the impact of climate change on the performance of reservoirs can be divided in two groups: (1) Studies that simulate the operation under projected inflows with the current set of operational rules. Due to non adapted operational rules the future performance of these reservoirs can be underestimated and the impact overestimated. (2) Studies that optimize the operational rules for best adaption of the system to the projected conditions before the assessment of the impact. The latter allows for estimating more realistically future performance and adaption strategies based on new operation rules are available if required. Multi-purpose reservoirs serve various, often conflicting functions. If all functions cannot be served simultaneously at a maximum level, an effective compromise between multiple objectives of the reservoir operation has to be provided. Yet under climate change the historically preferenced compromise may no longer be the most suitable compromise in the future. Therefore a multi-objective based climate change impact assessment approach for multi-purpose multi-reservoir systems is proposed in the study. Projected inflows are provided in a first step using a physically based rainfall-runoff model. In a second step, a time series model is applied to generate long-term inflow time series. Finally, the long-term inflow series are used as driving variables for a simulation-based multi-objective optimization of the reservoir system in order to derive optimal operation rules. As a result, the adapted Pareto-optimal set of diverse best compromise solutions can be presented to the decision maker in order to assist him in assessing climate change adaption measures with respect to the future performance of the multi-purpose reservoir system. The approach is tested on a multi-purpose multi-reservoir system in a mountainous catchment in Germany. A

A reconfigurable frequency-selective surface for dual-mode multi-band filtering applications

Science.gov (United States)

Majidzadeh, Maryam; Ghobadi, Changiz; Nourinia, Javad

2017-03-01

A reconfigurable single-layer frequency-selective surface (FSS) with dual-mode multi-band modes of operation is presented. The proposed structure is printed on a compact 10 × 10 mm2 FR4 substrate with the thickness of 1.6 mm. A simple square loop is printed on the front side while another one along with two defected vertical arms is deployed on the backside. To realise the reconfiguration, two pin diodes are embedded on the backside square loop. Suitable insertion of conductive elements along with pin diodes yields in dual-mode multi-band rejection of applicable in service frequency ranges. The first operating mode due to diodes' 'ON' state provides rejection of 2.4 GHz WLAN in 2-3 GHz, 5.2/5.8 GHz WLAN and X band in 5-12 GHz, and a part of Ku band in 13.9-16 GHz. In diodes 'OFF' state, the FSS blocks WLAN in 4-7.3 GHz, X band in 8-12.7 GHz as well as part of Ku band in 13.7-16.7 GHz. As well, high attenuation of incident waves is observed by a high shielding effectiveness (SE) in the blocked frequency bands. Also, a stable behaviour against different polarisations and angles of incidence is obtained. Comprehensive studies are conducted on a fabricated prototype to assess its performance from which encouraging results are obtained.

Fairness in multi-agent systems

NARCIS (Netherlands)

Jong, de S.; Tuyls, K.P.; Verbeeck, K.

2008-01-01

Multi-agent systems are complex systems in which multiple autonomous entities, called agents, cooperate in order to achieve a common or personal goal. These entities may be computer software, robots, and also humans. In fact, many multi-agent systems are intended to operate in cooperation with or as

Time-Frequency Feature Representation Using Multi-Resolution Texture Analysis and Acoustic Activity Detector for Real-Life Speech Emotion Recognition

Directory of Open Access Journals (Sweden)

Kun-Ching Wang

2015-01-01

Full Text Available The classification of emotional speech is mostly considered in speech-related research on human-computer interaction (HCI. In this paper, the purpose is to present a novel feature extraction based on multi-resolutions texture image information (MRTII. The MRTII feature set is derived from multi-resolution texture analysis for characterization and classification of different emotions in a speech signal. The motivation is that we have to consider emotions have different intensity values in different frequency bands. In terms of human visual perceptual, the texture property on multi-resolution of emotional speech spectrogram should be a good feature set for emotion classification in speech. Furthermore, the multi-resolution analysis on texture can give a clearer discrimination between each emotion than uniform-resolution analysis on texture. In order to provide high accuracy of emotional discrimination especially in real-life, an acoustic activity detection (AAD algorithm must be applied into the MRTII-based feature extraction. Considering the presence of many blended emotions in real life, in this paper make use of two corpora of naturally-occurring dialogs recorded in real-life call centers. Compared with the traditional Mel-scale Frequency Cepstral Coefficients (MFCC and the state-of-the-art features, the MRTII features also can improve the correct classification rates of proposed systems among different language databases. Experimental results show that the proposed MRTII-based feature information inspired by human visual perception of the spectrogram image can provide significant classification for real-life emotional recognition in speech.

A robust multi-frequency mixing algorithm for suppression of rivet signal in GMR inspection of riveted structures

Science.gov (United States)

Safdernejad, Morteza S.; Karpenko, Oleksii; Ye, Chaofeng; Udpa, Lalita; Udpa, Satish

2016-02-01

The advent of Giant Magneto-Resistive (GMR) technology permits development of novel highly sensitive array probes for Eddy Current (EC) inspection of multi-layer riveted structures. Multi-frequency GMR measurements with different EC pene-tration depths show promise for detection of bottom layer notches at fastener sites. However, the distortion of the induced magnetic field due to flaws is dominated by the strong fastener signal, which makes defect detection and classification a challenging prob-lem. This issue is more pronounced for ferromagnetic fasteners that concentrate most of the magnetic flux. In the present work, a novel multi-frequency mixing algorithm is proposed to suppress rivet signal response and enhance defect detection capability of the GMR array probe. The algorithm is baseline-free and does not require any assumptions about the sample geometry being inspected. Fastener signal suppression is based upon the random sample consensus (RANSAC) method, which iteratively estimates parameters of a mathematical model from a set of observed data with outliers. Bottom layer defects at fastener site are simulated as EDM notches of different length. Performance of the proposed multi-frequency mixing approach is evaluated on finite element data and experimental GMR measurements obtained with unidirectional planar current excitation. Initial results are promising demonstrating the feasibility of the approach.

Carrier-interleaved orthogonal multi-electrode multi-carrier resistivity-measurement tool

International Nuclear Information System (INIS)

Cai, Yu; Sha, Shuang

2016-01-01

This paper proposes a new carrier-interleaved orthogonal multi-electrode multi-carrier resistivity-measurement tool used in a cylindrical borehole environment during oil-based mud drilling processes. The new tool is an orthogonal frequency division multiplexing access-based contactless multi-measurand detection tool. The tool can measure formation resistivity in different azimuthal angles and elevational depths. It can measure many more measurands simultaneously in a specified bandwidth than the legacy frequency division multiplexing multi-measurand tool without a channel-select filter while avoiding inter-carrier interference. The paper also shows that formation resistivity is not sensitive to frequency in certain frequency bands. The average resistivity collected from N subcarriers can increase the measurement of the signal-to-noise ratio (SNR) by N times given no amplitude clipping in the current-injection electrode. If the clipping limit is taken into account, with the phase rotation of each single carrier, the amplitude peak-to-average ratio can be reduced by 3 times, and the SNR can achieve a 9/ N times gain over the single-carrier system. The carrier-interleaving technique is also introduced to counter the carrier frequency offset (CFO) effect, where the CFO will cause inter-pad interference. A qualitative analysis and simulations demonstrate that block-interleaving performs better than tone-interleaving when coping with a large CFO. The theoretical analysis also suggests that increasing the subcarrier number can increase the measurement speed or enhance elevational resolution without sacrificing receiver performance. The complex orthogonal multi-pad multi-carrier resistivity logging tool, in which all subcarriers are complex signals, can provide a larger available subcarrier pool than other types of transceivers. (paper)

The detection of structural defects in metallic materials and components using a non-destructive multi-frequency eddy current method

International Nuclear Information System (INIS)

Becker, R.

1980-01-01

Application of the multi-frequency method in eddy current testing is shown to be usefull for many important and complex problems in the field of non-destructive testing, which cannot be solved by the single frequency method because of principle reasons. Also in the presence of several perturbing signals the method can be applied successfully, thus very often difference coils can be replaced by absolute coils. Introducing the algorithm of multidimensional direction selection, the calibration of the test system is simpler, allowing automization of the calibration process. In addition, the test signals related with the defect parameters can be evaluated in an objective way. (orig./RW) [de

On Sea Ice Characterisation By Multi-Frequency SAR

Science.gov (United States)

Grahn, Jakob; Brekke, Camilla; Eltoft, Torbjorn; Holt, Benjamin

2013-12-01

By means of polarimetric target decomposition, quad-pol SAR data of sea ice is analysed at two frequency bands. In particular, the non negative eigenvalue decomposition (NNED) is applied on L- and C-band NASA/JPL AIR- SAR data acquired over the Beaufort sea in 2004. The de- composition separates the scattered radar signal into three types, dominated by double, volume and single bounce scattering respectively. Using ground truth derived from RADARSAT-1 and meteorological data, we investigate how the different frequency bands compare in terms of these scattering types. The ground truth contains multi year ice and three types of first year ice of different age and thickness. We find that C-band yields a higher scattered intensity in most ice and scattering types, as well as a more homogeneous intensity. L-band on the other hand yields more pronounced deformation features, such as ridges. The mean intensity contrast between the two thinnest ice types is highest in the double scattering component of C- band, although the contrast of the total signal is greater in L-band. This may indicate that the choice of polarimetric parameters is important for discriminating thin ice types.

A compensated multi-pole linear ion trap mercury frequency standard for ultra-stable timekeeping.

Science.gov (United States)

Burt, Eric A; Diener, William A; Tjoelker, Robert L

2008-12-01

The multi-pole linear ion trap frequency standard (LITS) being developed at the Jet Propulsion Laboratory (JPL) has demonstrated excellent short- and long-term stability. The technology has now demonstrated long-term field operation providing a new capability for timekeeping standards. Recently implemented enhancements have resulted in a record line Q of 5 x 10(12) for a room temperature microwave atomic transition and a short-term fractional frequency stability of 5 x 10(-14)/tau(1/2). A scheme for compensating the second order Doppler shift has led to a reduction of the combined sensitivity to the primary LITS systematic effects below 5 x 10(-17) fractional frequency. Initial comparisons to JPL's cesium fountain clock show a systematic floor of less than 2 x 10(-16). The compensated multi-pole LITS at JPL was operated continuously and unattended for a 9-mo period from October 2006 to July 2007. During that time it was used as the frequency reference for the JPL geodetic receiver known as JPLT, enabling comparisons to any clock used as a reference for an International GNSS Service (IGS) site. Comparisons with the laser-cooled primary frequency standards that reported to the Bureau International des Poids et Mesures (BIPM) over this period show a frequency deviation less than 2.7 x 10(-17)/day. In the capacity of a stand-alone ultra-stable flywheel, such a standard could be invaluable for long-term timekeeping applications in metrology labs while its methodology and robustness make it ideal for space applications as well.

Multi-Layer Soft Frequency Reuse Scheme for 5G Heterogeneous Cellular Networks

DEFF Research Database (Denmark)

Shakir, Md. Hossain; Tariq, Faisal; Safdar, Ghazanfar

2017-01-01

Heterogeneous network (HetNet) is a promising cell deployment technique where low power access points are deployed overlaid on a macrocell system. It attains high throughput by intelligently reusing spectrum, and brings a trade-off between energy- and spectral-efficiency. An efficient resource...... allocation strategy is required to significantly improve its throughput in a bid to meet the fifth-generation (5G) high data rate requirements. In this correspondence, a new resource allocation scheme for HetNet, called multi-level soft frequency reuse for HetNet (ML-SFR HetNet), is proposed which increases...... the throughput several fold. We derived spectrum and power allocation expression for a generalized HetNet scenario. In addition, analytical expressions for the throughput and area spectral efficiency (ASE) are also developed. The simulations results demonstrates the efficiency of the proposed scheme which...

Chronic Neck Pain Assessment using Multi-Frequency Bioimpedance

DEFF Research Database (Denmark)

Fener, Dilay Kesgin; Bartels, Else Marie; Elbrønd, Vibeke Sødring

2016-01-01

Scope: Chronic neck pain (CNP) is a disabling condition where the cause is often unknown, making treatment difficult. Muscle involvement is suspected in most cases, and assessment of muscle condition and changes following treatment may be possible with multi-frequency bioimpedance (mfBIA). Our aim...... involvement in chronic neck pain patients. AtlasBalans treatment did not show any clear indication as being an efficient form of treatment to relieve muscle tension in CNP patients....... was to test mfBIA as an assessment method of possible involvement of the neck, back and other related muscles in two CNP patients, prior to and following physiotherapy treatment with AtlasBalans. Methods: mfBIA measurements were carried out pre-treatment on m. sternocleidomastoideus, m. trapezius, upper back...

Systematic design and simulation of a tearing mode suppression feedback control system for the TEXTOR tokamak

International Nuclear Information System (INIS)

Hennen, B.A.; Westerhof, E.; De Baar, M.R.; Nuij, P.W.J.M.; Steinbuch, M.

2012-01-01

Suppression of tearing modes is essential for the operation of tokamaks. This paper describes the design and simulation of a tearing mode suppression feedback control system for the TEXTOR tokamak. The two main control tasks of this feedback control system are the radial alignment of electron cyclotron resonance heating and current drive (ECRH/ECCD) with a tearing mode and the stabilization of a mode at a specific width. In order to simulate these control tasks, the time evolution of a tearing mode subject to suppression by ECRH/ECCD and destabilization by a magnetic perturbation field is modelled using the generalized Rutherford equation. The model includes an equilibrium model and an ECRH/ECCD launcher model. The dynamics and static equilibria of this model are analysed. The model is linearized and based on the linearized model, linear feedback controllers are designed and simulated, demonstrating both alignment and width control of tearing modes in TEXTOR. (paper)

Frequency domain phase retrieval of simultaneous multi-wavelength phase-shifting interferometry

International Nuclear Information System (INIS)

Yin, Zhenxing; Zhong, Liyun; Xu, Xiaofei; Zhang, Wangping; Lu, Xiaoxu; Tian, Jindong

2016-01-01

In simultaneous multi-wavelength phase-shifting interferometry, we propose a novel frequency domain phase retrieval (FDPR) algorithm. First, using only a one-time phase-shifting operation, a sequence of simultaneous multi-wavelength phase-shifting interferograms (SPSMWIs) are captured by a monochrome charge-coupled device. Second, by performing a Fourier transform for each pixel of SPSMWIs, the wrapped phases of each wavelength can be retrieved from the complex amplitude located in the spectral peak of each wavelength. Finally, the phase of the synthetic wavelength can be obtained by the subtraction between the wrapped phases of a single wavelength. In this study, the principle and the application condition of the proposed approach are discussed. Both the simulation and the experimental result demonstrate the simple and convenient performance of the proposed FDPR approach. (paper)

Radio frequency system for nuclear fusion

International Nuclear Information System (INIS)

Kozeki, Shoichiro; Sagawa, Norimoto; Takizawa, Teruhiro

1987-01-01

The importance of radio frequency waves has been increasing in the area of nuclear fusion since they are indispensable for heating of plasma, etc. This report outlines radio frequency techniques used for nuclear fusion and describes the development of radio frequency systems (radio frequency plasma heating system and current drive system). Presently, in-depth studies are underway at various research institutes to achieve plasma heating by injection of radio frequency electric power. Three ranges of frequencies, ICRF (ion cyclotron range of frequency), LHRF (lower hybrid range of frequency) and ECRF (electron cyclotron range of frequency), are considered promissing for radio frequency heating. Candidate waves for plasma current driving include ECW (electron cyclotron wave), LHW (lower hybrid wave), MSW (magnetic sound wave), ICW (ion cyclotron wave) with minority component, and FW (fast wave). FW is the greatest in terms of current drive efficiency. In general, a radio frequency system for nuclear fusion consists of a radio frequency power source, transmission/matching circuit component and plasma connection component. (Nogami, K.)

Analysis of Low Frequency Oscillation Using the Multi-Interval Parameter Estimation Method on a Rolling Blackout in the KEPCO System

Directory of Open Access Journals (Sweden)

Kwan-Shik Shim

2017-04-01

Full Text Available This paper describes a multiple time interval (“multi-interval” parameter estimation method. The multi-interval parameter estimation method estimates a parameter from a new multi-interval prediction error polynomial that can simultaneously consider multiple time intervals. The root of the multi-interval prediction error polynomial includes the effect on each time interval, and the important mode can be estimated by solving one polynomial for multiple time intervals or signals. The algorithm of the multi-interval parameter estimation method proposed in this paper is applied to the test function and the data measured from a PMU (phasor measurement unit installed in the KEPCO (Korea Electric Power Corporation system. The results confirm that the proposed multi-interval parameter estimation method accurately and reliably estimates important parameters.

Coordinated frequency control from offshore wind power plants connected to multi terminal DC system considering wind speed variation

DEFF Research Database (Denmark)

Sakamuri, Jayachandra N.; Altin, Müfit; Hansen, Anca Daniela

2017-01-01

A coordinated fast primary frequency control scheme from offshore wind power plants (OWPPs) integrated to a three terminal high voltage DC (HVDC) system is proposed in this study. The impact of wind speed variation on the OWPP active power output and thus on the AC grid frequency and DC grid...... the active power support from OWPP with a ramp rate limiter and (iii) An alternative method for the wind turbine overloading considering rotor speed. The effectiveness of the proposed control scheme is demonstrated on a wind power plant integrated into a three terminal HVDC system developed in DIg......SILIENT PowerFactory. The results show that the proposed coordinated frequency control method performs effectively at different wind speeds and minimises the secondary effects on frequency and DC voltage....

Numerical optimization of quasi-optical mode converter for frequency step-tunable gyrotron

International Nuclear Information System (INIS)

Drumm, O.

2002-08-01

This work concentrates on the design of a quasi-optical mode converter for a frequency step-tunable gyrotron. Special attention is paid to the optimization of the conversion and forming of the exited wave of different frequencies inside the resonator. The investigations were part of the HGF-strategy-fonds-project ''Optimization of Tokamak Operation with controlled ECRH-Deposition''. In the resonator of the gyrotron modes can be exited at frequencies between 105 and 140 GHz. With the designed converter the desired field distribution at the output window for all frequencies will be approximately obtained. The newly gained knowledge and invented synthesis methods are applied to this practical example and verified. In this work, the waveguide antenna and the mirror system of the quasi-optical mode converter are presented separately from each other. At the beginning the synthesis of the aperture antenna for a frequency step-tunable design of the Vlasov-type as well as the Denisov-type is considered. As a conclusion of the investigation, the important parameters for the design of all antennas are summarized and the frequency behavior is compared. In the second part of this work new broadband design methods for the synthesis of the mirror surface are presented. These mirrors make an optimal wave forming for all frequencies equally possible. Therefore new quality criteria are introduced for the broadband evaluation of the mirror. Afterwards the surface is varied until the criteria reach an optimum. For the numerical optimization, in this work the gradient method and the extended Katsenelenbaum-Semenov algorithm are invented and applied. The efficient realization of the described algorithms on a computer is the significant point. The theoretical background of the presented methods for the synthesis of a mirror system is based on the general solution of the Helmholtz equation. Due to this, these methods can be utilized in other fields outside the microwave applications in

Fast 2D Fluid-Analytical Simulation of IEDs and Plasma Uniformity in Multi-frequency CCPs

Science.gov (United States)

Kawamura, E.; Lieberman, M. A.; Graves, D. B.

2014-10-01

A fast 2D axisymmetric fluid-analytical model using the finite elements tool COMSOL is interfaced with a 1D particle-in-cell (PIC) code to study ion energy distributions (IEDs) in multi-frequency argon capacitively coupled plasmas (CCPs). A bulk fluid plasma model which solves the time-dependent plasma fluid equations is coupled with an analytical sheath model which solves for the sheath parameters. The fluid-analytical results are used as input to a PIC simulation of the sheath region of the discharge to obtain the IEDs at the wafer electrode. Each fluid-analytical-PIC simulation on a moderate 2.2 GHz CPU workstation with 8 GB of memory took about 15-20 minutes. The 2D multi-frequency fluid-analytical model was compared to 1D PIC simulations of a symmetric parallel plate discharge, showing good agreement. Fluid-analytical simulations of a 2/60/162 MHz argon CCP with a typical asymmetric reactor geometry were also conducted. The low 2 MHz frequency controlled the sheath width and voltage while the higher frequencies controlled the plasma production. A standing wave was observable at the highest frequency of 162 MHz. Adding 2 MHz power to a 60 MHz discharge or 162 MHz to a dual frequency 2 MHz/60 MHz discharge enhanced the plasma uniformity. This work was supported by the Department of Energy Office of Fusion Energy Science Contract DE-SC000193, and in part by gifts from Lam Research Corporation and Micron Corporation.

ECRH scenarios with selective heating of trapped/passing electrons in the W7-X Stellarator

Directory of Open Access Journals (Sweden)

Marushchenko N.B.

2015-01-01

Full Text Available Using specific features of the magnetic equilibrium in the W7-X stellarator, the ECRH scenarios with combined X2 and X3 modes are discussed. The RF beams for operation with X2 and X3 modes need to be launched from low- and, via the remote steering launcher, high-field-side, respectivaly, in the different crosssections of the device where the maximum and minimum of the magnetic field located. The aim is to explore the possibility of selective heating of the different classes of electrons, passing and trapped, by changing direction of the beam for X3 or switching between the beams for X2 and X3 launched from the different ports. The numerical predictions for this kind of experiments in W7-X are performed by coupled transport and ray tracing codes

A multi-frequency sparse hemispherical ultrasound phased array for microbubble-mediated transcranial therapy and simultaneous cavitation mapping.

Science.gov (United States)

Deng, Lulu; O'Reilly, Meaghan A; Jones, Ryan M; An, Ran; Hynynen, Kullervo

2016-12-21

Focused ultrasound (FUS) phased arrays show promise for non-invasive brain therapy. However, the majority of them are limited to a single transmit/receive frequency and therefore lack the versatility to expose and monitor the treatment volume. Multi-frequency arrays could offer variable transmit focal sizes under a fixed aperture, and detect different spectral content on receive for imaging purposes. Here, a three-frequency (306, 612, and 1224 kHz) sparse hemispherical ultrasound phased array (31.8 cm aperture; 128 transducer modules) was constructed and evaluated for microbubble-mediated transcranial therapy and simultaneous cavitation mapping. The array is able to perform effective electronic beam steering over a volume spanning (-40, 40) and (-30, 50) mm in the lateral and axial directions, respectively. The focal size at the geometric center is approximately 0.9 (2.1) mm, 1.7 (3.9) mm, and 3.1 (6.5) mm in lateral (axial) pressure full width at half maximum (FWHM) at 1224, 612, and 306 kHz, respectively. The array was also found capable of dual-frequency excitation and simultaneous multi-foci sonication, which enables the future exploration of more complex exposure strategies. Passive acoustic mapping of dilute microbubble clouds demonstrated that the point spread function of the receive array has a lateral (axial) intensity FWHM between 0.8-3.5 mm (1.7-11.7 mm) over a volume spanning (-25, 25) mm in both the lateral and axial directions, depending on the transmit/receive frequency combination and the imaging location. The device enabled both half and second harmonic imaging through the intact skull, which may be useful for improving the contrast-to-tissue ratio or imaging resolution, respectively. Preliminary in vivo experiments demonstrated the system's ability to induce blood-brain barrier opening and simultaneously spatially map microbubble cavitation activity in a rat model. This work presents a tool to investigate optimal strategies for non

High-resolution time-frequency representation of EEG data using multi-scale wavelets

Science.gov (United States)

Li, Yang; Cui, Wei-Gang; Luo, Mei-Lin; Li, Ke; Wang, Lina

2017-09-01

An efficient time-varying autoregressive (TVAR) modelling scheme that expands the time-varying parameters onto the multi-scale wavelet basis functions is presented for modelling nonstationary signals and with applications to time-frequency analysis (TFA) of electroencephalogram (EEG) signals. In the new parametric modelling framework, the time-dependent parameters of the TVAR model are locally represented by using a novel multi-scale wavelet decomposition scheme, which can allow the capability to capture the smooth trends as well as track the abrupt changes of time-varying parameters simultaneously. A forward orthogonal least square (FOLS) algorithm aided by mutual information criteria are then applied for sparse model term selection and parameter estimation. Two simulation examples illustrate that the performance of the proposed multi-scale wavelet basis functions outperforms the only single-scale wavelet basis functions or Kalman filter algorithm for many nonstationary processes. Furthermore, an application of the proposed method to a real EEG signal demonstrates the new approach can provide highly time-dependent spectral resolution capability.

Nonlinear dynamical analysis of an aeroelastic system with multi-segmented moment in the pitch degree-of-freedom

Science.gov (United States)

Vasconcellos, Rui; Abdelkefi, Abdessattar

2015-01-01

The effects of a multi-segmented nonlinearity in the pitch degree of freedom on the behavior of a two-degree of freedom aeroelastic system are investigated. The aeroelastic system is free to plunge and pitch and is supported by linear translational and nonlinear torsional springs and is subjected to an incoming flow. The unsteady representation based on the Duhamel formulation is used to model the aerodynamic loads. Using modern method of nonlinear dynamics, a nonlinear characterization is performed to identify the system's response when increasing the wind speed. It is demonstrated that four sudden transitions take place with a change in the system's response. It is shown that, in the first transition, the system's response changes from simply periodic (only main oscillating frequency) to two periods (having the main oscillating frequency and its superharmonic of order 2). In the second transition, the response of the system changes from two periods (having the main oscillating frequency and its superharmonic of order 2) to a period-1. The results also show that the third transition is accompanied by a change in the system's response from simply periodic to two periods (having the main oscillating frequency and its superharmonic of order 3). After this transition, chaotic responses take place and then the fourth transition is accompanied by a sudden change in the system's response from chaotic to two periods (having the main oscillating frequency and its superharmonic of order 3). The results show that these transitions are caused by the tangential contact between the trajectory and the multi-segmented nonlinearity boundaries and with a zero-pitch speed incidence. This observation is associated with the definition of grazing bifurcation.

Multi-core System Architecture for Safety-critical Control Applications

DEFF Research Database (Denmark)

Li, Gang

and size, and high power consumption. Increasing the frequency of a processor is becoming painful now due to the explosive power consumption. Furthermore, components integrated into a single-core processor have to be certified to the highest SIL, due to that no isolation is provided in a traditional single...... certification cost. Meanwhile, hardware platforms with improved processing power are required to execute the applications of larger size. To tackle the two issues mentioned above, the state of the art approaches are using more Electronic Control Units (ECU) in a federated architecture or increasing......-core processor. A promising alternative to improve processing power and provide isolation is to adopt a multi-core architecture with on-chip isolation. In general, a specific multi-core architecture can facilitate the development and certification of safety-related systems, due to its physical isolation between...

Sliding mode load frequency control for multi-area time-delay power system with wind power integration

DEFF Research Database (Denmark)

Mi, Yang; Hao, Xuezhi; Liu, Yongjuan

2017-01-01

The interconnected time-delay power system has become an important issue for the open communication network. Meanwhile, due to the output power fluctuation of integrated wind energy, load frequency control (LFC) for power system with variable sources and loads has become more complicated. The novel...

Closure relations for the multi-species Euler system. Construction and study of relaxation schemes for the multi-species and multi-components Euler systems; Relations de fermeture pour le systeme des equations d'Euler multi-especes. Construction et etude de schemas de relaxation en multi-especes et en multi-constituants

Energy Technology Data Exchange (ETDEWEB)

Dellacherie, St. [CEA Saclay, Dir. de l' Energie Nucleaire DEN/SFNME/LMPE, Lab. de Modelisation Physique et de l' Enrichissement, 91 - Gif sur Yvette (France); Rency, N. [Paris-11 Univ., CNRS UMR 8628, 91 - Orsay (France)

2001-07-01

After having recalled the formal convergence of the semi-classical multi-species Boltzmann equations toward the multi-species Euler system (i.e. mixture of gases having the same velocity), we generalize to this system the closure relations proposed by B. Despres and by F. Lagoutiere for the multi-components Euler system (i.e. mixture of non miscible fluids having the same velocity). Then, we extend the energy relaxation schemes proposed by F. Coquel and by B. Perthame for the numerical resolution of the mono-species Euler system to the multi-species isothermal Euler system and to the multi-components isobar-isothermal Euler system. This allows to obtain a class of entropic schemes under a CFL criteria. In the multi-components case, this class of entropic schemes is perhaps a way for the treatment of interface problems and, then, for the treatment of the numerical mixture area by using a Lagrange + projection scheme. Nevertheless, we have to find a good projection stage in the multi-components case. At last, in the last chapter, we discuss, through the study of a dynamical system, about a system proposed by R. Abgrall and by R. Saurel for the numerical resolution of the multi-components Euler system.

Noise and Spurious Tones Management Techniques for Multi-GHz RF-CMOS Frequency Synthesizers Operating in Large Mixed Analog-Digital SOCs

Directory of Open Access Journals (Sweden)

Maxim Adrian

2006-01-01

Full Text Available This paper presents circuit techniques and power supply partitioning, filtering, and regulation methods aimed at reducing the phase noise and spurious tones in frequency synthesizers operating in large mixed analog-digital system-on-chip (SOC. The different noise and spur coupling mechanisms are presented together with solutions to minimize their impact on the overall PLL phase noise performance. Challenges specific to deep-submicron CMOS integration of multi-GHz PLLs are revealed, while new architectures that address these issues are presented. Layout techniques that help reducing the parasitic noise and spur coupling between digital and analog blocks are described. Combining system-level and circuit-level low noise design methods, low phase noise frequency synthesizers were achieved which are compatible with the demanding nowadays wireless communication standards.

High frequency CARM driver for rf linacs

International Nuclear Information System (INIS)

Danly, B.G.

1993-01-01

This CARM program has successfully demonstrated the first ever long-pulse CARM oscillator operation; these results demonstrate the potential of CARMs as an alternative source of millimeter waves to the gyrotron for ECRH plasma heating. The result of 1.8 MW at 27.8 GHz and 0.5 μs pulse width in the TE 11 mode represent a clear demonstration of the capabilities of the CARM oscillator for the production of high powers with large frequency upshift. It is hoped that this successful proof-of-principle demonstration.will lead to further development of the CARM as an ECRH source by the DOE Office of Fusion Energy, Development and Technology Division. This success is a direct outcome of this support of the Advanced Energy Projects Office of DOE in the form of this program. The CARM amplifier component of the program, although unsuccessful at obtaining CARM amplifier operation at 17 GHz, has succeeded by furthering the understanding of the limitations and difficulties that lie ahead for continued CARM amplifier development. The amplifier component of the program has successfully demonstrated a high power second and third harmonic gyro-TWT amplifier. Up to 5 MW of power at 17.1 GHz and >50dB gain have been obtained. These results should be viewed as an important contribution of this program to the development of viable microwave sources for powering the next linear collider. Indeed, the present gyro-amplifier, which resulted from this program, is presently being used in ongoing high-gradient accelerator research at MIT under a DOE High Energy Physics grant. As a result of both the oscillator and amplifier advances made during this program, the CARM and harmonic gyro-TWT have reached a significantly more mature level; their future role in specific applications of benefit to DOEs OFE and HEP offices may now be pursued

Object discrimination using optimized multi-frequency auditory cross-modal haptic feedback.

Science.gov (United States)

Gibson, Alison; Artemiadis, Panagiotis

2014-01-01

As the field of brain-machine interfaces and neuro-prosthetics continues to grow, there is a high need for sensor and actuation mechanisms that can provide haptic feedback to the user. Current technologies employ expensive, invasive and often inefficient force feedback methods, resulting in an unrealistic solution for individuals who rely on these devices. This paper responds through the development, integration and analysis of a novel feedback architecture where haptic information during the neural control of a prosthetic hand is perceived through multi-frequency auditory signals. Through representing force magnitude with volume and force location with frequency, the feedback architecture can translate the haptic experiences of a robotic end effector into the alternative sensory modality of sound. Previous research with the proposed cross-modal feedback method confirmed its learnability, so the current work aimed to investigate which frequency map (i.e. frequency-specific locations on the hand) is optimal in helping users distinguish between hand-held objects and tasks associated with them. After short use with the cross-modal feedback during the electromyographic (EMG) control of a prosthetic hand, testing results show that users are able to use audial feedback alone to discriminate between everyday objects. While users showed adaptation to three different frequency maps, the simplest map containing only two frequencies was found to be the most useful in discriminating between objects. This outcome provides support for the feasibility and practicality of the cross-modal feedback method during the neural control of prosthetics.

Combined frequency modulated atomic force microscopy and scanning tunneling microscopy detection for multi-tip scanning probe microscopy applications

International Nuclear Information System (INIS)

Morawski, Ireneusz; Spiegelberg, Richard; Korte, Stefan; Voigtländer, Bert

2015-01-01

A method which allows scanning tunneling microscopy (STM) tip biasing independent of the sample bias during frequency modulated atomic force microscopy (AFM) operation is presented. The AFM sensor is supplied by an electronic circuit combining both a frequency shift signal and a tunneling current signal by means of an inductive coupling. This solution enables a control of the tip potential independent of the sample potential. Individual tip biasing is specifically important in order to implement multi-tip STM/AFM applications. An extensional quartz sensor (needle sensor) with a conductive tip is applied to record simultaneously topography and conductivity of the sample. The high resonance frequency of the needle sensor (1 MHz) allows scanning of a large area of the surface being investigated in a reasonably short time. A recipe for the amplitude calibration which is based only on the frequency shift signal and does not require the tip being in contact is presented. Additionally, we show spectral measurements of the mechanical vibration noise of the scanning system used in the investigations

Combined frequency modulated atomic force microscopy and scanning tunneling microscopy detection for multi-tip scanning probe microscopy applications

Energy Technology Data Exchange (ETDEWEB)

Morawski, Ireneusz [Peter Grünberg Institut (PGI-3) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425 Jülich (Germany); Institute of Experimental Physics, University of Wrocław, pl. M. Borna 9, 50-204 Wrocław (Poland); Spiegelberg, Richard; Korte, Stefan; Voigtländer, Bert [Peter Grünberg Institut (PGI-3) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425 Jülich (Germany)

2015-12-15

A method which allows scanning tunneling microscopy (STM) tip biasing independent of the sample bias during frequency modulated atomic force microscopy (AFM) operation is presented. The AFM sensor is supplied by an electronic circuit combining both a frequency shift signal and a tunneling current signal by means of an inductive coupling. This solution enables a control of the tip potential independent of the sample potential. Individual tip biasing is specifically important in order to implement multi-tip STM/AFM applications. An extensional quartz sensor (needle sensor) with a conductive tip is applied to record simultaneously topography and conductivity of the sample. The high resonance frequency of the needle sensor (1 MHz) allows scanning of a large area of the surface being investigated in a reasonably short time. A recipe for the amplitude calibration which is based only on the frequency shift signal and does not require the tip being in contact is presented. Additionally, we show spectral measurements of the mechanical vibration noise of the scanning system used in the investigations.

Load Frequency Control of Two-Area Network using Renewable Energy Resources and Battery Energy Storage System

Directory of Open Access Journals (Sweden)

Norhafiz Bin SALIM

2017-06-01

Full Text Available In an interconnected system, the frequency and tie-line power interchange are very susceptible with the diversification of power load demand. Literally, in a multi-area power system, the load frequency control (LFC is substantially aimed to minimise the deviations of these parameters relatively. Knowingly, the power production from renewable energy resources could offer promising solutions despite their intermittency (i.e. photovoltaic/wind generation, hence in this context, a battery energy storage system (BESS is proposed to delineate dynamic response along with grid—connection. This study has proposed LFC with BESS control method to suppress frequency deviations for a power system and being compared with photovoltaic (PV approach. The effectiveness was verified using newly developed AGC30 model of Japanese Power System and was modelled using MATLAB Simulink. Furthermore, an analysis of the tie-line power oscillations also are carried out and comparison analysis demonstrates further the reliability of the proposed model and control methods.

Fast 2D fluid-analytical simulation of ion energy distributions and electromagnetic effects in multi-frequency capacitive discharges

Science.gov (United States)

Kawamura, E.; Lieberman, M. A.; Graves, D. B.

2014-12-01

A fast 2D axisymmetric fluid-analytical plasma reactor model using the finite elements simulation tool COMSOL is interfaced with a 1D particle-in-cell (PIC) code to study ion energy distributions (IEDs) in multi-frequency capacitive argon discharges. A bulk fluid plasma model, which solves the time-dependent plasma fluid equations for the ion continuity and electron energy balance, is coupled with an analytical sheath model, which solves for the sheath parameters. The time-independent Helmholtz equation is used to solve for the fields and a gas flow model solves for the steady-state pressure, temperature and velocity of the neutrals. The results of the fluid-analytical model are used as inputs to a PIC simulation of the sheath region of the discharge to obtain the IEDs at the target electrode. Each 2D fluid-analytical-PIC simulation on a moderate 2.2 GHz CPU workstation with 8 GB of memory took about 15-20 min. The multi-frequency 2D fluid-analytical model was compared to 1D PIC simulations of a symmetric parallel-plate discharge, showing good agreement. We also conducted fluid-analytical simulations of a multi-frequency argon capacitively coupled plasma (CCP) with a typical asymmetric reactor geometry at 2/60/162 MHz. The low frequency 2 MHz power controlled the sheath width and sheath voltage while the high frequencies controlled the plasma production. A standing wave was observable at the highest frequency of 162 MHz. We noticed that adding 2 MHz power to a 60 MHz discharge or 162 MHz to a dual frequency 2 MHz/60 MHz discharge can enhance the plasma uniformity. We found that multiple frequencies were not only useful for controlling IEDs but also plasma uniformity in CCP reactors.

Noise Suppression and Enhanced Focusability in Plasma Raman Amplifier with Multi-frequency Pump

International Nuclear Information System (INIS)

Balakin, A.A.; Fraiman, G.M.; Fisch, N.J.; Malkin, V.M.

2003-01-01

Laser pulse compression/amplification through Raman backscattering in plasmas can be facilitated by using multi-frequency pump laser beams. The efficiency of amplification is increased by suppressing the Raman instability of thermal fluctuations and seed precursors. Also the focusability of the amplified radiation is enhanced due to the suppression of large-scale longitudinal speckles in the pump wave structure

Non-contact radio frequency shielding and wave guiding by multi-folded transformation optics method.

Science.gov (United States)

Madni, Hamza Ahmad; Zheng, Bin; Yang, Yihao; Wang, Huaping; Zhang, Xianmin; Yin, Wenyan; Li, Erping; Chen, Hongsheng

2016-11-14

Compared with conventional radio frequency (RF) shielding methods in which the conductive coating material encloses the circuits design and the leakage problem occurs due to the gap in such conductive material, non-contact RF shielding at a distance is very promising but still impossible to achieve so far. In this paper, a multi-folded transformation optics method is proposed to design a non-contact device for RF shielding. This "open-shielded" device can shield any object at a distance from the electromagnetic waves at the operating frequency, while the object is still physically open to the outer space. Based on this, an open-carpet cloak is proposed and the functionality of the open-carpet cloak is demonstrated. Furthermore, we investigate a scheme of non-contact wave guiding to remotely control the propagation of surface waves over any obstacles. The flexibilities of such multi-folded transformation optics method demonstrate the powerfulness of the method in the design of novel remote devices with impressive new functionalities.

Multi-target consensus circle pursuit for multi-agent systems via a distributed multi-flocking method

Science.gov (United States)

Pei, Huiqin; Chen, Shiming; Lai, Qiang

2016-12-01

This paper studies the multi-target consensus pursuit problem of multi-agent systems. For solving the problem, a distributed multi-flocking method is designed based on the partial information exchange, which is employed to realise the pursuit of multi-target and the uniform distribution of the number of pursuing agents with the dynamic target. Combining with the proposed circle formation control strategy, agents can adaptively choose the target to form the different circle formation groups accomplishing a multi-target pursuit. The speed state of pursuing agents in each group converges to the same value. A Lyapunov approach is utilised to analyse the stability of multi-agent systems. In addition, a sufficient condition is given for achieving the dynamic target consensus pursuit, and which is then analysed. Finally, simulation results verify the effectiveness of the proposed approaches.

Neural Network Based Load Frequency Control for Restructuring ...

African Journals Online (AJOL)

Neural Network Based Load Frequency Control for Restructuring Power Industry. ... an artificial neural network (ANN) application of load frequency control (LFC) of a Multi-Area power system by using a neural network controller is presented.

Predictive simulations of radio frequency heated plasmas of Tore Supra using the Multi-Mode model

International Nuclear Information System (INIS)

Voitsekhovitch, Irina; Bateman, Glenn; Kritz, Arnold H.; Pankin, Alexei

2002-01-01

Multichannel integrated predictive simulations using the Multi-Mode transport model are carried out for radio frequency heated Tore Supra tokamak discharges in which helium is the primary ion component. Lower hybrid heated discharges in which the total current is driven noninductively [X. Litaudon et al., Plasma Phys. Controlled Fusion 43, 677 (2001)] and a discharge with ion cyclotron radio frequency heating of the hydrogen minority ions [G. T. Hoang et al., Nucl. Fusion 38, 117 (1998)] are simulated. The simulations of these discharges represent the first test of the Multi-Mode model in helium plasmas with dominant electron heating. Also for the first time, the particle transport in Tore Supra discharges is computed and the density profiles are predicted self-consistently with other transport channels. It is found in these simulations that the anomalous transport driven by trapped electron mode turbulence is dominant compared to the transport driven by the ion temperature gradient turbulence. The feature of the Multi-Mode model to calculate the impurity transport self-consistently with other transport channels is used in this study to predict the influence of carbon impurity influx on the discharge evolution

Multi-cavity locally resonant structure with the low frequency and broad band-gaps

Directory of Open Access Journals (Sweden)

Jiulong Jiang

2016-11-01

Full Text Available A multi-cavity periodic structure with the characteristic of local resonance was proposed in the paper. The low frequency band-gap structure was comparatively analyzed by the finite element method (FEM and electric circuit analogy (ECA. Low frequency band-gap can be opened through the dual influence of the coupling’s resonance in the cavity and the interaction among the couplings between structures. Finally, the influence of the structural factors on the band-gap was analyzed. The results show that the structure, which is divided into three parts equally, has a broader effective band-gap below the frequency of 200 Hz. It is also proved that reducing the interval between unit structures can increase the intensity of the couplings among the structures. And in this way, the width of band-gap would be expanded significantly. Through the parameters adjustment, the structure enjoys a satisfied sound insulation effect below the frequency of 500Hz. In the area of low frequency noise reduction, the structure has a lot of potential applications.

Improvement of ISI techniques by multi-frequency eddy current testing method for steam generator tube in PWR plant

International Nuclear Information System (INIS)

Endo, Takashi; Kamimura, Takeo; Nishihara, Masatoshi; Araki, Yasuo; Fukui, Shigetaka.

1982-05-01

Eddy current flaw detection techniques are applied to the in-service inspection (ISI) of steam generator tubes in pressurized water reactors (PWR) plant. To improve the reliability and operating efficiency of the plants, efforts are being made to develop eddy current testing methods of various kinds. Multi-frequency eddy current testing method, one of new method, has recently been applied to actual heat exchanger tubes, contributing to the improvement of the detectability and signal evaluation of the ISI. The outline of multi-frequency eddy current testing method and its effects on the improvement of flaw detecting and signal evaluation accuracy are described. (author)

Real-time multi-GNSS single-frequency precise point positioning

NARCIS (Netherlands)

de Bakker, P.F.; Tiberius, C.C.J.M.

2017-01-01

Precise Point Positioning (PPP) is a popular Global Positioning System (GPS) processing strategy, thanks to its high precision without requiring additional GPS infrastructure. Single-Frequency PPP (SF-PPP) takes this one step further by no longer relying on expensive dual-frequency GPS receivers,

Multi-Frequency Blazar Micro-Variability as a Tool to Investigate Relativistic Jets

Directory of Open Access Journals (Sweden)

James R. Webb

2016-08-01

Full Text Available For the past 12 years we have been studying optical micro-variability of a sample of 15 Blazars. We summarize the results of this study and draw some basic conclusions about the characteristics of micro-variability. The intermittency, the stochastic nature, and the similar profile shapes seen in micro-variations at different times and in different objects have led us to a possible model to explain the observed micro-variations. The model is based on a strong shock propagating down a relativistic jet and encountering turbulence which causes density or magnetic field enhancements. We use the theory of Kirk, Reiger, and Mastichiadis (1998 to describe the pulse of synchrotron emission emanating from individual density enhancements energized by the shock. By fitting these “pulses” to micro-variability observations, we obtain excellent fits to actual micro-variations. The model predicts that the spectral index changes as a function of pulse duration. This effect should be observable in multi-frequency micro-variability data. We present the theoretical model, model fits of our micro-variability light curves, and preliminary multi-frequency micro-variability observations that support this model. A further test that has yet to be carried out involves observing polarization changes in different pulses.

Fault-tolerant design approach for reliable offshore multi-megawatt variable frequency converters

Directory of Open Access Journals (Sweden)

N. Vedachalam

2016-09-01

Full Text Available Inverters play a key role in realizing reliable multi-megawatt power electronic converters used in offshore applications, as their failure leads to production losses and impairs safety. The performance of high power handing semiconductor devices with high speed control capabilities and redundant configurations helps in realizing a fault-tolerant design. This paper describes the reliability modeling done for an industry standard, 3-level neutral point clamped multi-megawatt inverter, the significance of semiconductor redundancy in reducing inverter failure rates, and proposes methods for achieving static and dynamic redundancy in series connected press pack type insulated gate bipolar transistors (IGBT. It is identified that, with the multi megawatt inverter having 3+2 IGBT in each half leg with dynamic redundancy incorporated, it is possible to reduce the failure rate of the inverter from 53.8% to 15% in 5 years of continuous operation. The simulation results indicate that with dynamic redundancy, it is possible to force an untriggered press pack IGBT to short circuit in <1s, when operated with a pulse width modulation frequency of 1kHz.

Multi-level predictive maintenance for multi-component systems

International Nuclear Information System (INIS)

Nguyen, Kim-Anh; Do, Phuc; Grall, Antoine

2015-01-01

In this paper, a novel predictive maintenance policy with multi-level decision-making is proposed for multi-component system with complex structure. The main idea is to propose a decision-making process considered on two levels: system level and component one. The goal of the decision rules at the system level is to address if preventive maintenance actions are needed regarding the predictive reliability of the system. At component level the decision rules aim at identifying optimally a group of several components to be preventively maintained when preventive maintenance is trigged due to the system level decision. Selecting optimal components is based on a cost-based group improvement factor taking into account the predictive reliability of the components, the economic dependencies as well as the location of the components in the system. Moreover, a cost model is developed to find the optimal maintenance decision variables. A 14-component system is finally introduced to illustrate the use and the performance of the proposed predictive maintenance policy. Different sensitivity analysis are also investigated and discussed. Indeed, the proposed policy provides more flexibility in maintenance decision-making for complex structure systems, hence leading to significant profits in terms of maintenance cost when compared with existing policies. - Highlights: • A predictive maintenance policy for complex structure systems is proposed. • Multi-level decision process based on prognostic results is proposed. • A cost-based group importance measure is introduced for decision-making. • Both positive and negative dependencies between components are investigated. • A cost model and Monte Carlo simulation are developed for optimization process.

Efficient Inversion of Mult-frequency and Multi-Source Electromagnetic Data

Energy Technology Data Exchange (ETDEWEB)

Gary D. Egbert

2007-03-22

The project covered by this report focused on development of efficient but robust non-linear inversion algorithms for electromagnetic induction data, in particular for data collected with multiple receivers, and multiple transmitters, a situation extremely common in eophysical EM subsurface imaging methods. A key observation is that for such multi-transmitter problems each step in commonly used linearized iterative limited memory search schemes such as conjugate gradients (CG) requires solution of forward and adjoint EM problems for each of the N frequencies or sources, essentially generating data sensitivities for an N dimensional data-subspace. These multiple sensitivities allow a good approximation to the full Jacobian of the data mapping to be built up in many fewer search steps than would be required by application of textbook optimization methods, which take no account of the multiplicity of forward problems that must be solved for each search step. We have applied this idea to a develop a hybrid inversion scheme that combines features of the iterative limited memory type methods with a Newton-type approach using a partial calculation of the Jacobian. Initial tests on 2D problems show that the new approach produces results essentially identical to a Newton type Occam minimum structure inversion, while running more rapidly than an iterative (fixed regularization parameter) CG style inversion. Memory requirements, while greater than for something like CG, are modest enough that even in 3D the scheme should allow 3D inverse problems to be solved on a common desktop PC, at least for modest (~ 100 sites, 15-20 frequencies) data sets. A secondary focus of the research has been development of a modular system for EM inversion, using an object oriented approach. This system has proven useful for more rapid prototyping of inversion algorithms, in particular allowing initial development and testing to be conducted with two-dimensional example problems, before

Hot-electron plasma formation and confinement in the Tandem Mirror Experiment-Upgrade

International Nuclear Information System (INIS)

Ress, D.B.

1988-01-01

Electron-cyclotron range-of-frequency heating (ECRH) at 28 GHz is used to create a population of mirror-confined hot electrons in the Tandem Mirror Experiment-Upgrade (TMX-U). Generation of a large fraction of such electrons within each end-cell of TMX-U is essential to the formation of the desired electrostatic potential profile of the thermal-barrier tandem mirror. The formation and confinement of the ECRH-generated hot-electron plasma was investigated with a variety of diagnostic instruments, including a novel instrumented limiter probe. The author characterized the spatial structure of the hot-electron plasma. Details of the heating process cause the plasma to separate into two regions: a halo, consisting entirely of energetic electrons, and a core, which is dominated by cooler electrons. The plasma structure forms rapidly under the action of second-harmonic ECRH. Fundamental ECRH, which is typically applied simultaneously, is only weakly absorbed and generally does not create energetic electrons. The ECRH-generated plasma displays several loss mechanisms. Hot electrons in the halo region, with T e ∼ 30 keV, are formed by localized ECRH near the plasma boundary, and are lost through a radial process involving open magnetic-curvature-drift surfaces

Distributed Model Predictive Load Frequency Control of Multi-area Power System with DFIGs

Institute of Scientific and Technical Information of China (English)

Yi Zhang; Xiangjie Liu; Bin Qu

2017-01-01

Reliable load frequency control(LFC) is crucial to the operation and design of modern electric power systems. Considering the LFC problem of a four-area interconnected power system with wind turbines, this paper presents a distributed model predictive control(DMPC) based on coordination scheme.The proposed algorithm solves a series of local optimization problems to minimize a performance objective for each control area. The generation rate constraints(GRCs), load disturbance changes, and the wind speed constraints are considered. Furthermore, the DMPC algorithm may reduce the impact of the randomness and intermittence of wind turbine effectively. A performance comparison between the proposed controller with and without the participation of the wind turbines is carried out. Analysis and simulation results show possible improvements on closed–loop performance, and computational burden with the physical constraints.

An acoustic metamaterial composed of multi-layer membrane-coated perforated plates for low-frequency sound insulation

Science.gov (United States)

Fan, Li; Chen, Zhe; Zhang, Shu-yi; Ding, Jin; Li, Xiao-juan; Zhang, Hui

2015-04-01

Insulating against low-frequency sound (below 500 Hz ) remains challenging despite the progress that has been achieved in sound insulation and absorption. In this work, an acoustic metamaterial based on membrane-coated perforated plates is presented for achieving sound insulation in a low-frequency range, even covering the lower audio frequency limit, 20 Hz . Theoretical analysis and finite element simulations demonstrate that this metamaterial can effectively block acoustic waves over a wide low-frequency band regardless of incident angles. Two mechanisms, non-resonance and monopolar resonance, operate in the metamaterial, resulting in a more powerful sound insulation ability than that achieved using periodically arranged multi-layer solid plates.

Multi-Agent Systems for E-Commerce

OpenAIRE

Solodukha, T. V.; Sosnovskiy, O. A.; Zhelezko, B. A.

2009-01-01

The article focuses on multi-agent systems (MAS) and domains that can benefit from multi-agent technology. In the last few years, the agent based modeling (ABM) community has developed several practical agent based modeling toolkits that enable individuals to develop agent-based applications. The comparison of agent-based modeling toolkits is given. Multi-agent systems are designed to handle changing and dynamic business processes. Any organization with complex and distributed business pro...

Combating Impairments in Multi-carrier Systems: A Compressed Sensing Approach

KAUST Repository

Al-Shuhail, Shamael

2015-05-01

Multi-carrier systems suffer from several impairments, and communication system engineers use powerful signal processing tools to combat these impairments and keep up with the capacity/rate demands. Compressed sensing (CS) is one such tool that allows recovering any sparse signal, requiring only a few measurements in a domain that is incoherent with the domain of sparsity. Almost all signals of interest have some degree of sparsity, and in this work we utilize the sparsity of impairments in orthogonal frequency division multiplexing (OFDM) and its variants (i.e., orthogonal frequency division multiplexing access (OFDMA) and single-carrier frequency-division multiple access (SC-FDMA)) to combat them using CS. We start with the problem of peak-to-average power ratio (PAPR) reduction in OFDM. OFDM signals suffer from high PAPR and clipping is the simplest PAPR reduction scheme. However, clipping introduces inband distortions that result in compromised performance and hence needs to be mitigated at the receiver. Due to the high PAPR nature of the OFDM signal, only a few instances are clipped, these clipping distortions can be recovered at the receiver by employing CS. We then extend the proposed clipping recovery scheme to an interleaved OFDMA system. Interleaved OFDMA presents a special structure that result in only self-inflicted clipping distortions. In this work, we prove that distortions do not spread over multiple users (while utilizing interleaved carrier assignment in OFDMA) and construct a CS system that recovers the clipping distortions on each user. Finally, we address the problem of narrowband interference (NBI) in SC-FDMA. Unlike OFDM and OFDMA systems, SC-FDMA does not suffer from high PAPR, but (as the data is encoded in time domain) is seriously vulnerable to information loss owing to NBI. Utilizing the sparse nature of NBI (in frequency domain) we combat its effect on SC-FDMA system by CS recovery.

Quantitative, depth-resolved determination of particle motion using multi-exposure, spatial frequency domain laser speckle imaging.

Science.gov (United States)

Rice, Tyler B; Kwan, Elliott; Hayakawa, Carole K; Durkin, Anthony J; Choi, Bernard; Tromberg, Bruce J

2013-01-01

Laser Speckle Imaging (LSI) is a simple, noninvasive technique for rapid imaging of particle motion in scattering media such as biological tissue. LSI is generally used to derive a qualitative index of relative blood flow due to unknown impact from several variables that affect speckle contrast. These variables may include optical absorption and scattering coefficients, multi-layer dynamics including static, non-ergodic regions, and systematic effects such as laser coherence length. In order to account for these effects and move toward quantitative, depth-resolved LSI, we have developed a method that combines Monte Carlo modeling, multi-exposure speckle imaging (MESI), spatial frequency domain imaging (SFDI), and careful instrument calibration. Monte Carlo models were used to generate total and layer-specific fractional momentum transfer distributions. This information was used to predict speckle contrast as a function of exposure time, spatial frequency, layer thickness, and layer dynamics. To verify with experimental data, controlled phantom experiments with characteristic tissue optical properties were performed using a structured light speckle imaging system. Three main geometries were explored: 1) diffusive dynamic layer beneath a static layer, 2) static layer beneath a diffuse dynamic layer, and 3) directed flow (tube) submerged in a dynamic scattering layer. Data fits were performed using the Monte Carlo model, which accurately reconstructed the type of particle flow (diffusive or directed) in each layer, the layer thickness, and absolute flow speeds to within 15% or better.

Ontology-based multi-agent systems

Energy Technology Data Exchange (ETDEWEB)

Hadzic, Maja; Wongthongtham, Pornpit; Dillon, Tharam; Chang, Elizabeth [Digital Ecosystems and Business Intelligence Institute, Perth, WA (Australia)

2009-07-01

The Semantic web has given a great deal of impetus to the development of ontologies and multi-agent systems. Several books have appeared which discuss the development of ontologies or of multi-agent systems separately on their own. The growing interaction between agents and ontologies has highlighted the need for integrated development of these. This book is unique in being the first to provide an integrated treatment of the modeling, design and implementation of such combined ontology/multi-agent systems. It provides clear exposition of this integrated modeling and design methodology. It further illustrates this with two detailed case studies in (a) the biomedical area and (b) the software engineering area. The book is, therefore, of interest to researchers, graduate students and practitioners in the semantic web and web science area. (orig.)

An Extended System Frequency Response Model Considering Wind Power Participation in Frequency Regulation

Directory of Open Access Journals (Sweden)

Yi Tang

2017-11-01

Full Text Available With increasing penetration of wind power into the power system, wind power participation in frequency regulation is regarded as a beneficial strategy to improve the dynamic frequency response characteristics of power systems. The traditional power system frequency response (SFR model, which only includes synchronous generators, is no longer suitable for power systems with high penetrated wind power. An extended SFR model, based on the reduced-order model of wind turbine generator (WTG and the traditional SFR model, is presented in this paper. In the extended SFR model, the reduced-order model of WTG with combined frequency control is deduced by employing small signal analysis theory. Afterwards, the stability analysis of a closed-loop control system for the extended SFR model is carried out. Time-domain simulations using a test system are performed to validate the effectiveness of the extended SFR model; this model can provide a simpler, clearer and faster way to analyze the dynamic frequency response characteristic for a high-wind integrated power systems. The impact of additional frequency control parameters and wind speed disturbances on the system dynamic frequency response characteristics are investigated.

Kepler Confirmation of Multi-Planet Systems

Science.gov (United States)

Cochran, W. D.

2011-10-01

The NASA Kepler spacecraft has detected 170 candidate multi-planet systems in the first two quarters of data released in February 2011 by Borucki et al. (2011). These systems comprise 115 double candidate systems, 45 triple candidate sys- tems, and 10 systems with 4 or more candidate planets. The architecture and dynamics of these systems were discussed by Lissauer et al. (2011), and a comparison of candidates in single- and multi-planet systems was presented by Latham et al. (2011). Proceeding from "planetary candidate" systems to confirmed and validated multi-planet systems is a difficult process, as most of these systems orbit stars too faint to obtain extremely precise (1ms-1) radial velocity confimation. Here, we discuss in detail the use of transit timing vari- ations (cf. e.g. Holman et al., 2010) to confirm planets near a mean motion resonance. We also discuss extensions to the BLENDER validation (Torres et al., 2004, 2011; Fressin et al., 2011) to validate planets in multi-planet systems. Kepler was competitively selected as the tenth Discovery mission. Funding for the Kepler Mis- sion is provided by NASA's Science Mission Direc- torate. We are deeply grateful for the very hard work of the entire Kepler team.

Application of Linear Quadratic Gaussian and Coefficient Diagram Techniques to Distributed Load Frequency Control of Power Systems

Directory of Open Access Journals (Sweden)

Tarek Hassan Mohamed

2015-12-01

Full Text Available This paper presented both the linear quadratic Gaussian technique (LQG and the coefficient diagram method (CDM as load frequency controllers in a multi-area power system to deal with the problem of variations in system parameters and load demand change. The full states of the system including the area frequency deviation have been estimated using the Kalman filter technique. The efficiency of the proposed control method has been checked using a digital simulation. Simulation results indicated that, with the proposed CDM + LQG technique, the system is robust in the face of parameter uncertainties and load disturbances. A comparison between the proposed technique and other schemes is carried out, confirming the superiority of the proposed CDM + LQG technique.

A hybrid DE–PS algorithm for load frequency control under deregulated power system with UPFC and RFB

Directory of Open Access Journals (Sweden)

Rabindra Kumar Sahu

2015-09-01

Full Text Available In this paper, a Modified Integral Derivative (MID controller is proposed for Load Frequency Control (LFC of multi-area multi-source power system in deregulated environment. The multi-source power system is having different sources of power generation such as thermal, hydro, wind and diesel generating units considering boiler dynamics for thermal plants, Generation Rate Constraint (GRC and Governor Dead Band (GDB non-linearity. The superiority of proposed hybrid Differential Evolution and Pattern Search (hDE-PS optimized MID controller over GA and DE techniques is demonstrated. Further, the effectiveness of proposed hDE-PS optimized MID controller over Integral (I and Integral Derivative (ID controller is verified. Then, to further improve the system performance, Unified Power Flow Controller (UPFC is placed in the tie-line and Redox Flow Batteries (RFBs are considered in the first area. The performance of proposed approach is evaluated at all possible power transactions that take place in a deregulated power market.

Block-Iterative Frequency-Domain Equalizations for SC-IDMA Systems

Directory of Open Access Journals (Sweden)

Salah Awad Salman

2015-07-01

Full Text Available In wireless broadband communications using single-carrier interleave division multiple access (SC-IDMA systems, efficient multiuser detection (MUD classes that make use of joint hybrid decision feedback equalization (HDFE/ frequency decision-feedback equalization (FDFE and interference cancellation (IC techniques, are proposed in conjunction with channel coding to deal with several users accessing the multipath fading channels. In FDFE-IDMA, the feedforward (FF and feedback (FB filtering operations of FDFE, which use to remove intersymbol interference (ISI, are implemented by Fast Fourier Transforms (FFTs, while in HDFE-IDMA the only FF filter is implemented by FFTs. Further, the parameters involved in the FDFE/HDFE filtering are derived according to the minimum mean square error (MMSE criteria, and the feedback symbol decisions are directly designed from soft detection of the decoded signals at the previous iteration. The simulation results including comparisons with those of frequency domain equalization (FDE, SC-FDE-IDMA and multi-carrier OFDM-IDMA schemes, with cyclic prefixing (CP and zero padding (ZP techniques, show that the combination of FDFE-IC/HDFE-IC provides an efficient solution with good performance for IDMA systems in ISI channels. Moreover, these iterative structures with block equalization yield a much lower complexity than equivalent existing structures, making them attractive for a wealth of applications.

Structural analysis of ITER multi-purpose deployer

International Nuclear Information System (INIS)

Manuelraj, Manoah Stephen; Dutta, Pramit; Gotewal, Krishan Kumar; Rastogi, Naveen; Tesini, Alessandro; Choi, Chang-Hwan

2016-01-01

Highlights: • System modelling for structural analysis of the Multi-Purpose Deployer (MPD). • Finite element modeling of the Multi-Purpose Deployer (MPD). • Static, modal and seismic response analysis of the Multi-Purpose Deployer (MPD). • Iterative structural analysis and design update to satisfy the structural criteria. • Modal analysis for various kinematic configurations. • Reaction force calculations on the interfacing systems. - Abstract: The Multi-Purpose Deployer (MPD) is a general purpose ITER in-vessel remote handling (RH) system. The main handling equipment, known as the MPD Transporter, consists of a series of linked bodies, which provide anchoring to the vacuum vessel port and an articulated multi-degree of freedom motion to perform various in-vessel maintenance tasks. During the in-vessel operations, the structural integrity of the system should be guaranteed against various operational and seismic loads. This paper presents the structural analysis results of the concept design of the MPD Transporter considering the seismic events. Static structural, modal and frequency response spectrum analyses have been performed to verify the structural integrity of the system, and to provide reaction forces to the interfacing systems such as vacuum vessel and cask. Iterative analyses and design updates are carried out based on the reference design of the system to improve the structural behavior of the system. The frequency responses of the system in various kinematics and payloads are assessed.

A fractional-N frequency divider for multi-standard wireless transceiver fabricated in 0.18 μm CMOS process

Science.gov (United States)

Wang, Jiafeng; Fan, Xiangning; Shi, Xiaoyang; Wang, Zhigong

2017-12-01

With the rapid evolution of wireless communication technology, integrating various communication modes in a mobile terminal has become the popular trend. Because of this, multi-standard wireless technology is one of the hot spots in current research. This paper presents a wideband fractional-N frequency divider of the multi-standard wireless transceiver for many applications. High-speed divider-by-2 with traditional source-coupled-logic is designed for very wide band usage. Phase switching technique and a chain of divider-by-2/3 are applied to the programmable frequency divider with 0.5 step. The phase noise of the whole frequency synthesizer will be decreased by the narrower step of programmable frequency divider. Δ-Σ modulator is achieved by an improved MASH 1-1-1 structure. This structure has excellent performance in many ways, such as noise, spur and input dynamic range. Fabricated in TSMC 0.18μm CMOS process, the fractional-N frequency divider occupies a chip area of 1130 × 510 μm2 and it can correctly divide within the frequency range of 0.8-9 GHz. With 1.8 V supply voltage, its division ratio ranges from 62.5 to 254 and the total current consumption is 29 mA.

Model based PI power system stabilizer design for damping low frequency oscillations in power systems.

Science.gov (United States)

Salgotra, Aprajita; Pan, Somnath

2018-05-01

This paper explores a two-level control strategy by blending local controller with centralized controller for the low frequency oscillations in a power system. The proposed control scheme provides stabilization of local modes using a local controller and minimizes the effect of inter-connection of sub-systems performance through a centralized control. For designing the local controllers in the form of proportional-integral power system stabilizer (PI-PSS), a simple and straight forward frequency domain direct synthesis method is considered that works on use of a suitable reference model which is based on the desired requirements. Several examples both on one machine infinite bus and multi-machine systems taken from the literature are illustrated to show the efficacy of the proposed PI-PSS. The effective damping of the systems is found to be increased remarkably which is reflected in the time-responses; even unstable operation has been stabilized with improved damping after applying the proposed controller. The proposed controllers give remarkable improvement in damping the oscillations in all the illustrations considered here and as for example, the value of damping factor has been increased from 0.0217 to 0.666 in Example 1. The simulation results obtained by the proposed control strategy are favourably compared with some controllers prevalent in the literature. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Acoustical characteristic predictions of a multi-layer system of a submerged vehicle hull mounted sonar simplified to an infinite planar model

Directory of Open Access Journals (Sweden)

Sung-Hee Kim

2012-06-01

Full Text Available Hull Mounted Sonar (HMS is a long range submerged vehicle's hull-mounted passive sonar system which detects low-frequency noise caused by machineries of enemy ships or submerged vehicles. The HMS needs a sound absorption /insulation multi-layer structure to shut out the self-noise from own machineries and to amplify signals from outside. Therefore, acoustic analysis of the multi-layer system should be performed when the HMS is designed. This paper simplified the HMS multi-layer system to be an infinite planar multi-layer model. Also, main excitations that influence the HMS were classified into mechanical, plane wave and turbulent flow excitation, and the investigations for each excitation were performed for various models. Stiffened multi-layer analysis for mechanical excitation and general multi-layer analysis for turbulent flow excitation were developed. The infinite planar multi-layer analysis was expected to be more useful for preliminary design stage of HMS system than the infinite cylindrical model because of short analysis time and easiness of parameter study.

Adaptive Droop Control for Microgrids Based on the Synergetic Control of Multi-Agent Systems

Directory of Open Access Journals (Sweden)

Zhiwen Yu

2016-12-01

Full Text Available In this paper, a distributed synergetic control based on multi-agent systems is proposed to solve the problems of frequency and voltage errors, system stability and power sharing accuracy in the traditional droop control of microgrids. Starting with power flow equations, we build the secondary-order dynamic model of DG, which consists of three parts: (1 active power allocation; (2 active power-frequency; and (3 reactive power-voltage droop control. Considering time-delays in communication networks, a leaderless synergetic control algorithm is proposed to allocate the active power in inverse proportion to the droop coefficient, and the synergetic control with a virtual leader is proposed to control the system frequency and voltage to keep at the expected value. Besides, the direct Lyapunov method is introduced to verify the globally asymptotical stability. Moreover, the impacts of communication disturbance are also discussed from the aspects of control precision and system stability. Finally, based on a test microgrid, numerous cases are designed as illustration, and the simulation results validate the proposed method.

Ant Colony Optimization Algorithm for Centralized Dynamic Channel Allocation in Multi-Cell OFDMA Systems

Science.gov (United States)

Kim, Hyo-Su; Kim, Dong-Hoi

The dynamic channel allocation (DCA) scheme in multi-cell systems causes serious inter-cell interference (ICI) problem to some existing calls when channels for new calls are allocated. Such a problem can be addressed by advanced centralized DCA design that is able to minimize ICI. Thus, in this paper, a centralized DCA is developed for the downlink of multi-cell orthogonal frequency division multiple access (OFDMA) systems with full spectral reuse. However, in practice, as the search space of channel assignment for centralized DCA scheme in multi-cell systems grows exponentially with the increase of the number of required calls, channels, and cells, it becomes an NP-hard problem and is currently too complicated to find an optimum channel allocation. In this paper, we propose an ant colony optimization (ACO) based DCA scheme using a low-complexity ACO algorithm which is a kind of heuristic algorithm in order to solve the aforementioned problem. Simulation results demonstrate significant performance improvements compared to the existing schemes in terms of the grade of service (GoS) performance and the forced termination probability of existing calls without degrading the system performance of the average throughput.

Systematic Multi-variable H-infinity Control Design for Primary Frequency Regulation in Stand-alone Microgrids with High Penetration of Renewable Energy Sources

OpenAIRE

Lam , Quang Linh; Bratcu , Antoneta Iuliana; Riu , Delphine

2016-01-01

International audience; In this paper, a systematic design of a robust multi-variable control structure for primary frequency regulation in microgrids with high rate of renewable source penetration is proposed. The considered microgrid represents a diesel-photovoltaic-supercapacitor hybrid power generation system operating in stand-alone mode. The proposed control structure relies on a two-level architecture: classical PI-based current tracking controllers are placed on the low control level ...

Operational upgrades to the DIII-D 60 GHz electron cyclotron resonant heating system

International Nuclear Information System (INIS)

Harris, T.E.; Cary, W.P.

1993-10-01

One of the primary components of the DIII-D radio frequency (rf) program over the past seven years has been the 60 GHz electron cyclotron resonant heating (ECRH) system. The system now consists of eight units capable of operating and controlling eight Varian VGE-8006 60 GHz, 200 kW gyrotrons along with their associated waveguide components. This paper will discuss the operational upgrades and the overall system performance. Many modifications were instituted to enhance the system operation and performance. Modifications discussed in this paper include an improved gyrotron tube-fault response network, a computer controlled pulse-timing and sequencing system, and an improved high-voltage power supply control interface. The discussion on overall system performance will include operating techniques used to improve system operations and reliability. The techniques discussed apply to system start-up procedures, operating the system in a conditioning mode, and operating the system during DIII-D plasma operations

Energy-aware Thread and Data Management in Heterogeneous Multi-core, Multi-memory Systems

Energy Technology Data Exchange (ETDEWEB)

Su, Chun-Yi [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

2014-12-16

By 2004, microprocessor design focused on multicore scaling—increasing the number of cores per die in each generation—as the primary strategy for improving performance. These multicore processors typically equip multiple memory subsystems to improve data throughput. In addition, these systems employ heterogeneous processors such as GPUs and heterogeneous memories like non-volatile memory to improve performance, capacity, and energy efficiency. With the increasing volume of hardware resources and system complexity caused by heterogeneity, future systems will require intelligent ways to manage hardware resources. Early research to improve performance and energy efficiency on heterogeneous, multi-core, multi-memory systems focused on tuning a single primitive or at best a few primitives in the systems. The key limitation of past efforts is their lack of a holistic approach to resource management that balances the tradeoff between performance and energy consumption. In addition, the shift from simple, homogeneous systems to these heterogeneous, multicore, multi-memory systems requires in-depth understanding of efficient resource management for scalable execution, including new models that capture the interchange between performance and energy, smarter resource management strategies, and novel low-level performance/energy tuning primitives and runtime systems. Tuning an application to control available resources efficiently has become a daunting challenge; managing resources in automation is still a dark art since the tradeoffs among programming, energy, and performance remain insufficiently understood. In this dissertation, I have developed theories, models, and resource management techniques to enable energy-efficient execution of parallel applications through thread and data management in these heterogeneous multi-core, multi-memory systems. I study the effect of dynamic concurrent throttling on the performance and energy of multi-core, non-uniform memory access

Projected changes in precipitation intensity and frequency over complex topography: a multi-model perspective

Science.gov (United States)

Fischer, Andreas; Keller, Denise; Liniger, Mark; Rajczak, Jan; Schär, Christoph; Appenzeller, Christof

2014-05-01

Fundamental changes in the hydrological cycle are expected in a future warmer climate. This is of particular relevance for the Alpine region, as a source and reservoir of several major rivers in Europe and being prone to extreme events such as floodings. For this region, climate change assessments based on the ENSEMBLES regional climate models (RCMs) project a significant decrease in summer mean precipitation under the A1B emission scenario by the mid-to-end of this century, while winter mean precipitation is expected to slightly rise. From an impact perspective, projected changes in seasonal means, however, are often insufficient to adequately address the multifaceted challenges of climate change adaptation. In this study, we revisit the full matrix of the ENSEMBLES RCM projections regarding changes in frequency and intensity, precipitation-type (convective versus stratiform) and temporal structure (wet/dry spells and transition probabilities) over Switzerland and surroundings. As proxies for raintype changes, we rely on the model parameterized convective and large-scale precipitation components. Part of the analysis involves a Bayesian multi-model combination algorithm to infer changes from the multi-model ensemble. The analysis suggests a summer drying that evolves altitude-specific: over low-land regions it is associated with wet-day frequency decreases of convective and large-scale precipitation, while over elevated regions it is primarily associated with a decline in large-scale precipitation only. As a consequence, almost all the models project an increase in the convective fraction at elevated Alpine altitudes. The decrease in the number of wet days during summer is accompanied by decreases (increases) in multi-day wet (dry) spells. This shift in multi-day episodes also lowers the likelihood of short dry spell occurrence in all of the models. For spring and autumn the combined multi-model projections indicate higher mean precipitation intensity north of the

Firewater system inadvertent actuation frequencies

International Nuclear Information System (INIS)

Schroeder, J.A.; Eide, S.A.

1993-01-01

This paper presents some recommended generic values for fire protection system inadvertent actuation frequencies. The frequencies are based on actual data from Department of Energy and commercial reactor plant facilities

Optimizing survivability of multi-state systems with multi-level protection by multi-processor genetic algorithm

International Nuclear Information System (INIS)

Levitin, Gregory; Dai Yuanshun; Xie Min; Leng Poh, Kim

2003-01-01

In this paper we consider vulnerable systems which can have different states corresponding to different combinations of available elements composing the system. Each state can be characterized by a performance rate, which is the quantitative measure of a system's ability to perform its task. Both the impact of external factors (stress) and internal causes (failures) affect system survivability, which is determined as probability of meeting a given demand. In order to increase the survivability of the system, a multi-level protection is applied to its subsystems. This means that a subsystem and its inner level of protection are in their turn protected by the protection of an outer level. This double-protected subsystem has its outer protection and so forth. In such systems, the protected subsystems can be destroyed only if all of the levels of their protection are destroyed. Each level of protection can be destroyed only if all of the outer levels of protection are destroyed. We formulate the problem of finding the structure of series-parallel multi-state system (including choice of system elements, choice of structure of multi-level protection and choice of protection methods) in order to achieve a desired level of system survivability by the minimal cost. An algorithm based on the universal generating function method is used for determination of the system survivability. A multi-processor version of genetic algorithm is used as optimization tool in order to solve the structure optimization problem. An application example is presented to illustrate the procedure presented in this paper

Multi-bunch Feedback Systems

CERN Document Server

Lonza, M.

2014-12-19

Coupled-bunch instabilities excited by the interaction of the particle beam with its surroundings can seriously limit the performance of circular particle accelerators. These instabilities can be cured by the use of active feedback systems based on sensors capable of detecting the unwanted beam motion and actuators that apply the feedback correction to the beam. Advances in electronic technology now allow the implementation of feedback loops using programmable digital systems. Besides important advantages in terms of flexibility and reproducibility, digital systems open the way to the use of novel diagnostic tools and additional features. We first introduce coupled-bunch instabilities, analysing the equation of motion of charged particles and the different modes of oscillation of a multi-bunch beam, showing how they can be observed and measured. Different types of feedback systems will then be presented as examples of real implementations that belong to the history of multi-bunch feedback systems. The main co...

Calculation and analysis of whiplash effect in multi-DOF system

Science.gov (United States)

Chen, Gong; Qi, Qunfu; Yang, Hongmei; Li, Ling

2017-04-01

The response of structural vibration depends on the degree of freedomss, mass, stiffness, external effect of the structure. Natural frequency of structure is its inherent property, also it is related to its own factors, but not related to the external factors. Firstly the nature and characteristics of resonance effect and whiplash effect are analyzed. Secondly whiplash effect of multi-degree freedomss system is analyzed, then orthogonality in main models is used to verify the results of calculation. Then the improvements of whiplash effect are proposed, also the improved models are analyzed. Finally the conclusions are made.

Real-time digital signal recovery for a multi-pole low-pass transfer function system.

Science.gov (United States)

Lee, Jhinhwan

2017-08-01

In order to solve the problems of waveform distortion and signal delay by many physical and electrical systems with multi-pole linear low-pass transfer characteristics, a simple digital-signal-processing (DSP)-based method of real-time recovery of the original source waveform from the distorted output waveform is proposed. A mathematical analysis on the convolution kernel representation of the single-pole low-pass transfer function shows that the original source waveform can be accurately recovered in real time using a particular moving average algorithm applied on the input stream of the distorted waveform, which can also significantly reduce the overall delay time constant. This method is generalized for multi-pole low-pass systems and has noise characteristics of the inverse of the low-pass filter characteristics. This method can be applied to most sensors and amplifiers operating close to their frequency response limits to improve the overall performance of data acquisition systems and digital feedback control systems.

Optimization of multi-branch switched diversity systems

KAUST Repository

Nam, Haewoon; Alouini, Mohamed-Slim

2009-01-01

A performance optimization based on the optimal switching threshold(s) for a multi-branch switched diversity system is discussed in this paper. For the conventional multi-branch switched diversity system with a single switching threshold

Robust power system frequency control

CERN Document Server

Bevrani, Hassan

2014-01-01

This updated edition of the industry standard reference on power system frequency control provides practical, systematic and flexible algorithms for regulating load frequency, offering new solutions to the technical challenges introduced by the escalating role of distributed generation and renewable energy sources in smart electric grids. The author emphasizes the physical constraints and practical engineering issues related to frequency in a deregulated environment, while fostering a conceptual understanding of frequency regulation and robust control techniques. The resulting control strategi

A design method of compensators for multi-variable control system with PID controllers 'CHARLY'

International Nuclear Information System (INIS)

Fujiwara, Toshitaka; Yamada, Katsumi

1985-01-01

A systematic design method of compensators for a multi-variable control system having usual PID controllers in its loops is presented in this paper. The method itself is able: to determine the main manipulating variable corresponding to each controlled variable with a sensitivity analysis in the frequency domain. to tune PID controllers sufficiently to realize adequate control actions with a searching technique of minimum values of cost functionals. to design compensators improving the control preformance and to simulate a total system for confirming the designed compensators. In the phase of compensator design, the state variable feed-back gain is obtained by means of the OPTIMAL REGULATOR THEORY for the composite system of plant and PID controllers. The transfer function type compensators the configurations of which were previously given are, then, designed to approximate the frequency responces of the above mentioned state feed-back system. An example is illustrated for convenience. (author)

Frequency Domain Multi-parameter Full Waveform Inversion for Acoustic VTI Media

KAUST Repository

Djebbi, Ramzi

2017-05-26

Multi-parameter full waveform inversion (FWI) for transversely isotropic (TI) media with vertical axis of symmetry (VTI) suffers from the trade-off between the parameters. The trade-off results in the leakage of one parameter\\'s update into the other during the inversion. It affects the accuracy and convergence of the inversion. The sensitivity analyses suggested a parameterisation using the horizontal velocity vh, epsilon and eta to reduce the trade-off for surface recorded seismic data.We test the (vh, epsilon, eta) parameterisation for acoustic VTI media using a scattering integral (SI) based inversion. The data is modeled in frequency domain and the model is updated using a preconditioned conjugate gradient method. We applied the method to the VTI Marmousi II model and in the inversion, we keep eta parameter fixed as the background initial model and we invert simultaneously for both vh and epsilon. The results show the suitability of the parameterisation for multi-parameter VTI acoustic inversion as well as the accuracy of the inversion approach.

Applications of Multi-Agent Technology to Power Systems

Science.gov (United States)

Nagata, Takeshi

Currently, agents are focus of intense on many sub-fields of computer science and artificial intelligence. Agents are being used in an increasingly wide variety of applications. Many important computing applications such as planning, process control, communication networks and concurrent systems will benefit from using multi-agent system approach. A multi-agent system is a structure given by an environment together with a set of artificial agents capable to act on this environment. Multi-agent models are oriented towards interactions, collaborative phenomena, and autonomy. This article presents the applications of multi-agent technology to the power systems.

Institute for Plasma Research, Stuttgart University. Annual report 1986

International Nuclear Information System (INIS)

1987-01-01

In 1986 the IPP-IPF cooperation in the field of fusion related research and development has been successfully continued. The ECRH project as the largest activity is concentrated on the completion of the 1 MW/70 GHz long-pulse ECRH-system for the W VII-AS stellarator. The components tests promise optimum technical and - hopefully - physical results. Theoretical investigations mainly concern ray propagation and time dependent transport calculations for stellarators at ECRH conditions. A first successful experimental demonstration of the LIDAR scattering concept on JET was a rather encouraging progress for the laser diagnostic group. Besides this project the FIR scattering was continued on ASDEX with measurements of the k-spectra of the low frequency fluctuations during the various kinds of plasma heating. On the WEGA stellarator a programme of flux surface measurements with electron beams has been started. A meanwhile improved detection method will be applied - in cooperation with the Wendelstein team - at the coming W VII-AS stellarator. In the last year the plasma focus experiment POSEIDON achieved successful operation at full bank energy. (orig.)

High frequency system project implementation plan

International Nuclear Information System (INIS)

Moon, L.L.

1976-01-01

The High Frequency System is a new mobile, digital diagnostic recording system for use at the Nevada Test Site. Many different kinds of event data will be digitized in real-time by this system, and these data will be recorded and stored for later read-out and transmission to NADCEN. The hardware and software requirements of the High Frequency System are examined, and the parameters of the system are proposed

Performance of the Multi-Radar Multi-Sensor System over the Lower Colorado River, Texas

Science.gov (United States)

Bayabil, H. K.; Sharif, H. O.; Fares, A.; Awal, R.; Risch, E.

2017-12-01

Recently observed increases in intensities and frequencies of climate extremes (e.g., floods, dam failure, and overtopping of river banks) necessitate the development of effective disaster prevention and mitigation strategies. Hydrologic models can be useful tools in predicting such events at different spatial and temporal scales. However, accuracy and prediction capability of such models are often constrained by the availability of high-quality representative hydro-meteorological data (e.g., precipitation) that are required to calibrate and validate such models. Improved technologies and products such as the Multi-Radar Multi-Sensor (MRMS) system that allows gathering and transmission of vast meteorological data have been developed to provide such data needs. While the MRMS data are available with high spatial and temporal resolutions (1 km and 15 min, respectively), its accuracy in estimating precipitation is yet to be fully investigated. Therefore, the main objective of this study is to evaluate the performance of the MRMS system in effectively capturing precipitation over the Lower Colorado River, Texas using observations from a dense rain gauge network. In addition, effects of spatial and temporal aggregation scales on the performance of the MRMS system were evaluated. Point scale comparisons were made at 215 gauging locations using rain gauges and MRMS data from May 2015. Moreover, the effects of temporal and spatial data aggregation scales (30, 45, 60, 75, 90, 105, and 120 min) and (4 to 50 km), respectively on the performance of the MRMS system were tested. Overall, the MRMS system (at 15 min temporal resolution) captured precipitation reasonably well, with an average R2 value of 0.65 and RMSE of 0.5 mm. In addition, spatial and temporal data aggregations resulted in increases in R2 values. However, reduction in RMSE was achieved only with an increase in spatial aggregations.

Frequency response functions for nonlinear convergent systems

NARCIS (Netherlands)

Pavlov, A.V.; Wouw, van de N.; Nijmeijer, H.

2007-01-01

Convergent systems constitute a practically important class of nonlinear systems that extends the class of asymptotically stable linear time-invariant systems. In this note, we extend frequency response functions defined for linear systems to nonlinear convergent systems. Such nonlinear frequency

A multi-objective optimization problem for multi-state series-parallel systems: A two-stage flow-shop manufacturing system

International Nuclear Information System (INIS)

Azadeh, A.; Maleki Shoja, B.; Ghanei, S.; Sheikhalishahi, M.

2015-01-01

This research investigates a redundancy-scheduling optimization problem for a multi-state series parallel system. The system is a flow shop manufacturing system with multi-state machines. Each manufacturing machine may have different performance rates including perfect performance, decreased performance and complete failure. Moreover, warm standby redundancy is considered for the redundancy allocation problem. Three objectives are considered for the problem: (1) minimizing system purchasing cost, (2) minimizing makespan, and (3) maximizing system reliability. Universal generating function is employed to evaluate system performance and overall reliability of the system. Since the problem is in the NP-hard class of combinatorial problems, genetic algorithm (GA) is used to find optimal/near optimal solutions. Different test problems are generated to evaluate the effectiveness and efficiency of proposed approach and compared to simulated annealing optimization method. The results show the proposed approach is capable of finding optimal/near optimal solution within a very reasonable time. - Highlights: • A redundancy-scheduling optimization problem for a multi-state series parallel system. • A flow shop with multi-state machines and warm standby redundancy. • Objectives are to optimize system purchasing cost, makespan and reliability. • Different test problems are generated and evaluated by a unique genetic algorithm. • It locates optimal/near optimal solution within a very reasonable time

Exact free vibration of multi-step Timoshenko beam system with several attachments

Science.gov (United States)

Farghaly, S. H.; El-Sayed, T. A.

2016-05-01

This paper deals with the analysis of the natural frequencies, mode shapes of an axially loaded multi-step Timoshenko beam combined system carrying several attachments. The influence of system design and the proposed sub-system non-dimensional parameters on the combined system characteristics are the major part of this investigation. The effect of material properties, rotary inertia and shear deformation of the beam system for each span are included. The end masses are elastically supported against rotation and translation at an offset point from the point of attachment. A sub-system having two degrees of freedom is located at the beam ends and at any of the intermediate stations and acts as a support and/or a suspension. The boundary conditions of the ordinary differential equation governing the lateral deflections and slope due to bending of the beam system including the shear force term, due to the sub-system, have been formulated. Exact global coefficient matrices for the combined modal frequencies, the modal shape and for the discrete sub-system have been derived. Based on these formulae, detailed parametric studies of the combined system are carried out. The applied mathematical model is valid for wide range of applications especially in mechanical, naval and structural engineering fields.

Feasibility study for a multi-channel pulsed radar reflectometer for the jet divertor region

International Nuclear Information System (INIS)

Heijnen, S.H.; Pol, M.J. van de.

1994-09-01

In this report, the feasibility of a pulsed radar system for measuring the electron density profile in the divertor region of JET is studied. Some dedicated experiments are performed with a four-channel system, which was designed for the Rijnhuizen Tokamak Project. To simulate divertor plasmas the measurements are performed in ECRH induced plasmas without current. The parameters of these kinds of plasmas are: n e 19 m -3 , T e <100 eV, and a diameter of ∼30 cm. (HSI)

Efficient string similarity join in multi-core and distributed systems.

Directory of Open Access Journals (Sweden)

Cairong Yan

Full Text Available In big data area a significant challenge about string similarity join is to find all similar pairs more efficiently. In this paper, we propose a parallel processing framework for efficient string similarity join. First, the input is split into some disjoint small subsets according to the joint frequency distribution and the interval distribution of strings. Then the filter-verification strategy is adopted in the computation of string similarity for each subset so that the number of candidate pairs is reduced before an effective pruning strategy is used to improve the performance. Finally, the operation of string join is executed in parallel. Para-Join algorithm based on the multi-threading technique is proposed to implement the framework in a multi-core system while Pada-Join algorithm based on Spark platform is proposed to implement the framework in a cluster system. We prove that Para-Join and Pada-Join cannot only avoid reduplicate computation but also ensure the completeness of the result. Experimental results show that Para-Join can achieve high efficiency and significantly outperform than state-of-the-art approaches, meanwhile, Pada-Join can work on large datasets.

Analytical Evaluation of Chunk-Based Tractable Multi-cell OFDMA system

Directory of Open Access Journals (Sweden)

P.Kavitha

2018-04-01

Full Text Available This paper evaluates thoroughly the performance of multi-cell OFDMA system. The two types of deployment in multi-cell OFDMA system, such as Strict Fractional Frequency Reuse (FFR and Soft FFR (SFR were evaluated. In order to model the base station locations, homogeneous Poisson point processes were used, i.e. tractable model instead of hexagonal grid was considered. In order to reduce complexity, chunk-based resource allocation scheme was embedded. Each cell divides the users into the users of the central cell area and the users of the cell edge area according to their average received Signal to Interference and Noise Ratio (SINR compared with FFR threshold. The primary stage of the analysis includes the spectral efficiency’s expression deriving from these two deployment scenarios, followed by the analysis with the use of coverage probability. However, the improvement of spectral efficiency is achieved in the case of SFR. On the contrary, coverage probability is far improved by using strict FFR scheme. Through numerical anaysis, We have shown that the optimal FFR threshold to achieve the highest spectral efficiency was 12 dB for both Strict FFR as well as SFR.

The quantitative evaluation of complex defect signals from eddy current testings with multi-frequency methods

International Nuclear Information System (INIS)

Naegele, W.

1982-01-01

The usual formulation of multi-frequency eddy current signals of large defects by linearized impedance diagrams may lead to misinterpretations. Here a developement of the linear superposition principle is proposed, which takes into account also the curvature of the impedance diagrams thus allowing to identify even large defects in an unambiguous way. (orig.) [de

Perceptual and Attentional Influences on Continuous 2:1 and 3:2 Multi-Frequency Bimanual Coordination

Science.gov (United States)

Kovacs, Attila J.; Buchanan, John J.; Shea, Charles H.

2010-01-01

Two experiments were conducted to determine if multi-frequency (2:1 and 3:2) coordination between the limbs is enhanced when integrated feedback is provided in the form of Lissajous plots, attention demands are reduced, and attempts to consciously coordinate the limbs are not encouraged. To determine the influence of vision of the limbs, covered…

Physics of the Brain. Prevention of the Epileptic Seizures by the Multi-photon Pulsed-operated Fiber Lasers in the Ultraviolet Range of Frequencies.

Science.gov (United States)

Stefan, V. Alexander; IAPS Team

The novel study of the epileptogenesis mechanisms is proposed. It is based on the pulsed-operated (amplitude modulation) multi-photon (frequency modulation) fiber-laser interaction with the brain epilepsy-topion (the epilepsy onset area), so as to prevent the excessive electrical discharge (epileptic seizure) in the brain. The repetition frequency, Ω, matches the low frequency (epileptic) phonon waves in the brain. The laser repetition frequency (5-100 pulses per second) enables the resonance-scanning of the wide range of the phonon (possible epileptic-to-be) activity in the brain. The tunable fiber laser frequencies, Δω (multi photon operation), are in the ultraviolet frequency range, thus enabling monitoring of the electrical charge imbalance (within the 10s of milliseconds), and the DNA-corruption in the epilepsy-topion, as the possible cause of the disease. Supported by Nikola Tesla Labs., Stefan University.

Multi-bunch feedback systems

CERN Document Server

Lonza, M

2008-01-01

Coupled-bunch instabilities excited by the interaction of the particle beam with its surroundings can seriously limit the performance of circular particle accelerators. These instabilities can be cured by the use of active feedback systems based on sensors capable of detecting the unwanted beam motion and actuators that apply the feedback correction to the beam. The advances in electronic technology now allow the implementation of feedback loops using programmable digital systems. Besides important advantages in terms of flexibility and reproducibility, digital systems open the way to the use of novel diagnostic tools and additional features. The lecture will first introduce coupled-bunch instabilities analysing the equation of motion of charged particles and the different modes of oscillation of a multi-bunch beam, showing how they can be observed and measured. Different types of feedbacks systems will then be presented as examples of real implementations that belong to the history of multi-bunch feedback sy...

Multi-channel data acquisition system for CT

International Nuclear Information System (INIS)

Cao Fuqiang; He Bin; Liu Guohua; Xu Minjian

2009-01-01

The architecture design and realization of a data acquisition system for multi-channel CT is described. The article introduces the conversion of analog signal to digital signal, the data cache and transmission. This data acquisition system can be widely used in the system which requires the multi-channel, weak current signal detection. (authors)

Research on the Multi-Energy Management Strategy of the Electric Drive System of a Tracked Bulldozer

Directory of Open Access Journals (Sweden)

Ming Pan

2016-01-01

Full Text Available The multi-energy management strategy of electric drive system of tracked bulldozer was researched. Firstly, based on power requirement of typical working condition of a tracked bulldozer, the power distribution strategy for three energy sources in the front power chain was proposed by using wavelet theory and fuzzy control theory. Secondly, the electric drive system simulation platform was built in MATLAB/Simulink. At last, a driver-controller based HILS (hardware-in-the-loop simulation platform was built and the multi-energy management strategy was verified. The HILS result shows that front power chain’s power output can meet the back power chain’s requirement, the engine-generator set works near the best fuel consumption curve, and the battery pack’s charge-discharge frequency and current are low. Thus the designed multi-energy management strategy can be used in real-time control of electric drive bulldozer.

Seismic isolation systems designed with distinct multiple frequencies

International Nuclear Information System (INIS)

Wu, Ting-shu; Seidensticker, R.W.

1991-01-01

Two systems for seismic base isolation are presented. The main feature of these system is that, instead of only one isolation frequency as in conventional isolation systems, they are designed to have two distinct isolation frequencies. When the responses during an earthquake exceed the design value(s), the system will automatically and passively shift to the secondly isolation frequency. Responses of these two systems to different ground motions including a harmonic motion with frequency same as the primary isolation frequency, show that no excessive amplification will occur. Adoption of these new systems certainly will greatly enhance the safety and reliability of an isolated superstructure against future strong earthquakes. 3 refs

Photon correlation in single-photon frequency upconversion.

Science.gov (United States)

Gu, Xiaorong; Huang, Kun; Pan, Haifeng; Wu, E; Zeng, Heping

2012-01-30

We experimentally investigated the intensity cross-correlation between the upconverted photons and the unconverted photons in the single-photon frequency upconversion process with multi-longitudinal mode pump and signal sources. In theoretical analysis, with this multi-longitudinal mode of both signal and pump sources system, the properties of the signal photons could also be maintained as in the single-mode frequency upconversion system. Experimentally, based on the conversion efficiency of 80.5%, the joint probability of simultaneously detecting at upconverted and unconverted photons showed an anti-correlation as a function of conversion efficiency which indicated the upconverted photons were one-to-one from the signal photons. While due to the coherent state of the signal photons, the intensity cross-correlation function g(2)(0) was shown to be equal to unity at any conversion efficiency, agreeing with the theoretical prediction. This study will benefit the high-speed wavelength-tunable quantum state translation or photonic quantum interface together with the mature frequency tuning or longitudinal mode selection techniques.

Implementation method of multi-terminal DC control system

Science.gov (United States)

Yi, Liu; Hao-Ran, Huang; Jun-Wen, Zhou; Hong-Guang, Guo; Yu-Yong, Zhou

2018-04-01

Currently the multi-terminal DC system (MTDC) has more stations. Each station needs operators to monitor and control the device. It needs much more operation and maintenance, low efficiency and small reliability; for the most important reason, multi-terminal DC system has complex control mode. If one of the stations has some problem, the control of the whole system should have problems. According to research of the characteristics of multi-terminal DC (VSC-MTDC) systems, this paper presents a strong implementation of the multi-terminal DC Supervisory Control and Data Acquisition (SCADA) system. This system is intelligent, can be networking, integration and intelligent. A master control system is added in each station to communication with the other stations to send current and DC voltage value to pole control system for each station. Based on the practical application and information feedback in the China South Power Grid research center VSC-MTDC project, this system is higher efficiency and save the cost on the maintenance of convertor station to improve the intelligent level and comprehensive effect. And because of the master control system, a multi-terminal system hierarchy coordination control strategy is formed, this make the control and protection system more efficiency and reliability.

Progress in long sustainment and high density experiments with potential confinement on GAMMA 10

International Nuclear Information System (INIS)

Yatsu, K.; Cho, T.; Hirata, M.

2001-01-01

The improvement of potential confinement reported in the last IAEA meeting was attained by axisymmetrization of heating pattern of electron cyclotron resonance heating (ECRH). It was experimentally shown that the axisymmetrization of ECRH really produced axisymmetric potential profile. GAMMA 10 experiments have advanced in longer sustainment and high density operation of potential confinement. Experiments for long sustainment of potential confinement were carried out in order to study problems of steady state operation of a tandem mirror reactor. A confining potential was sustained for 150 ms by sequentially injecting two (ECRH) powers in the plug region. It was difficult before to increase the central cell density higher than about 2.5x10 12 cm -3 with and/or without potential confinement due to some density limiting mechanism. In order to overcome this problem, a new higher frequency ion cyclotron range of frequency (ICRF) system (RF3: 36-76 MHz) has been installed. A higher density plasma has been produced with RF3. In addition to RF3, neutral beam injection (NBI) in the anchor cell became effective by reducing neutral gas from beam injectors. Potential confinement experiments have advanced to higher central cell densities up to 4x10 12 cm -3 with RF3 and NBI. A 20% density increase due to the potential confinement was obtained in the high density experiments. (author)

An adjustable multi-scale single beam acoustic tweezers based on ultrahigh frequency ultrasonic transducer.

Science.gov (United States)

Chen, Xiaoyang; Lam, Kwok Ho; Chen, Ruimin; Chen, Zeyu; Yu, Ping; Chen, Zhongping; Shung, K Kirk; Zhou, Qifa

2017-11-01

This paper reports the fabrication, characterization, and microparticle manipulation capability of an adjustable multi-scale single beam acoustic tweezers (SBAT) that is capable of flexibly changing the size of "tweezers" like ordinary metal tweezers with a single-element ultrahigh frequency (UHF) ultrasonic transducer. The measured resonant frequency of the developed transducer at 526 MHz is the highest frequency of piezoelectric single crystal based ultrasonic transducers ever reported. This focused UHF ultrasonic transducer exhibits a wide bandwidth (95.5% at -10 dB) due to high attenuation of high-frequency ultrasound wave, which allows the SBAT effectively excite with a wide range of excitation frequency from 150 to 400 MHz by using the "piezoelectric actuator" model. Through controlling the excitation frequency, the wavelength of ultrasound emitted from the SBAT can be changed to selectively manipulate a single microparticle of different sizes (3-100 μm) by using only one transducer. This concept of flexibly changing "tweezers" size is firstly introduced into the study of SBAT. At the same time, it was found that this incident ultrasound wavelength play an important role in lateral trapping and manipulation for microparticle of different sizes. Biotechnol. Bioeng. 2017;114: 2637-2647. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Synergy of multi-frequency studies from observations of NGC 6334I

International Nuclear Information System (INIS)

Seifahrt, Andreas; Thorwirth, Sven; Menten, Karl M; Beuther, Henrik; Brogan, Crystal L; Hunter, Todd R; Stecklum, Bringfried; Leurini, Silvia

2008-01-01

We combine multi-frequency observations from the millimeter to near infrared wavelengths that demonstrate the spatial distributions of H 2 , CO, and NH 3 emission, which are all manifestations of various shocks driven by outflows of deeply embedded source(s) in NGC 6334I. In addition to the well-known northeast-southwest outflow we detect at least one more outflow in the region by combining observations from APEX, ATCA, SMA, Spitzer and VLT/ISAAC. Potential driving sources will be discussed. NGC 6334I exhibits several signs of active star formation and will be a major target for future observatories such as Herschel and ALMA.

Periodic rotation noise induced by the crosstalk between two beat-frequency signals in multi-oscillator ring laser gyros

International Nuclear Information System (INIS)

Lu, Guangfeng; Wang, Zhiguo; Fan, Zhenfang; Luo, Hui

2014-01-01

Periodic rotation noise in the outputs of multi-oscillator ring laser gyros (MRLGs) is investigated in this paper for the first time. It is proved theoretically and experimentally that noise is induced by the crosstalk between two beat-frequency signals, which are combined from the left and right circularly polarized counter-propagating beams in MRLGs. Theoretical analysis and experimental results also indicate that the fundamental frequency of this noise is equal to the frequency difference between the two beat-frequency signals and the amplitude of the fundamental component is proportional to the crosstalk ratio between the two beat-frequency signals. Further, the amplitude of the nth-order component is proportional to the nth power of the crosstalk ratio. (paper)

Fusion of space-borne multi-baseline and multi-frequency interferometric results based on extended Kalman filter to generate high quality DEMs

Science.gov (United States)

Zhang, Xiaojie; Zeng, Qiming; Jiao, Jian; Zhang, Jingfa

2016-01-01

Repeat-pass Interferometric Synthetic Aperture Radar (InSAR) is a technique that can be used to generate DEMs. But the accuracy of InSAR is greatly limited by geometrical distortions, atmospheric effect, and decorrelations, particularly in mountainous areas, such as western China where no high quality DEM has so far been accomplished. Since each of InSAR DEMs generated using data of different frequencies and baselines has their own advantages and disadvantages, it is therefore very potential to overcome some of the limitations of InSAR by fusing Multi-baseline and Multi-frequency Interferometric Results (MMIRs). This paper proposed a fusion method based on Extended Kalman Filter (EKF), which takes the InSAR-derived DEMs as states in prediction step and the flattened interferograms as observations in control step to generate the final fused DEM. Before the fusion, detection of layover and shadow regions, low-coherence regions and regions with large height error is carried out because MMIRs in these regions are believed to be unreliable and thereafter are excluded. The whole processing flow is tested with TerraSAR-X and Envisat ASAR datasets. Finally, the fused DEM is validated with ASTER GDEM and national standard DEM of China. The results demonstrate that the proposed method is effective even in low coherence areas.

Millimetre wave attenuation of prototype diagnostic components for the ITER bolometers

Energy Technology Data Exchange (ETDEWEB)

Meister, H., E-mail: meister@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, Garching (Germany); Kasparek, W. [Universität Stuttgart, Institut für Grenzflächenverfahrenstechnik & Plasmatechnologie, Stuttgart (Germany); Zhang, D.; Hirsch, M. [Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald, Greifswald (Germany); Koll, J. [Max-Planck-Institut für Plasmaphysik, Garching (Germany); Zeitler, A. [Universität Stuttgart, Institut für Grenzflächenverfahrenstechnik & Plasmatechnologie, Stuttgart (Germany)

2015-10-15

Highlights: • Attenuation of ECRH stray radiation in ITER demonstrated for bolometer prototypes. • Collimator with microwave reflecting grid achieves >70 dB at 170 GHz (ITER frequency). • For frequencies >250 GHz (ECE radiation) ceramic coating showed 40 dB attenuation. • Good shielding at joints of components is prerequisite to prevent microwave leakage. • These methods prevent the impact of ECRH stray radiation on bolometer measurements. - Abstract: Bolometers in current and future fusion devices, in particular those in ITER, are vulnerable to stray radiation from electron cyclotron resonance heating (ECRH) which results in measurement errors for plasma radiation detection. To protect the detectors from this stray radiation in the millimetre wavelength range, dedicated diagnostic components have been designed and tested. One option is to place a top plate which contains a microwave-reflecting grid onto the collimators. Another option investigated is the coating of the collimator channels using a microwave absorbing ceramic. Measurements of the mm-wave attenuation of the collimator in front of the bolometer detectors with and without top plate or coated collimator channels have been performed in the frequency range of 125–420 GHz. The attenuation factor of the collimator channels at 170 GHz (the ECRH frequency for ITER) with neither microwave grid nor coating is typically 10 dB. The coating enhances this to 40 dB and including the microwave grid yields at least an attenuation factor of 70 dB, which is sufficient to reduce the residual ECRH induced signal significantly below the one due to plasma radiation. Placing a bolometer camera (collimator connected to detector housing) inside the isotropic microwave field of the test facility MISTRAL, the attenuation factor of the full diagnostic set-up using a top plate was determined to be in the order of 45 dB. This degraded attenuation implies that particular attention has to be paid to design and quality

Multi-echelon systems : a service measure perspective

NARCIS (Netherlands)

Diks, E.B.; Kok, de A.G.; Lagodimos, A.G.

1996-01-01

This paper reviews the most important results on divergent multi-echelon systems. In particular, we concentrate on the interactions between the elements that constitute such a multi-echelon system, in order to determine several service measures (e.g. external customer service level and inventory

Improved Kalman Filter Method for Measurement Noise Reduction in Multi Sensor RFID Systems

OpenAIRE

Eom, Ki Hwan; Lee, Seung Joon; Kyung, Yeo Sun; Lee, Chang Won; Kim, Min Chul; Jung, Kyung Kwon

2011-01-01

Recently, the range of available Radio Frequency Identification (RFID) tags has been widened to include smart RFID tags which can monitor their varying surroundings. One of the most important factors for better performance of smart RFID system is accurate measurement from various sensors. In the multi-sensing environment, some noisy signals are obtained because of the changing surroundings. We propose in this paper an improved Kalman filter method to reduce noise and obtain correct data. Perf...

Precise orbit determination of Multi-GNSS constellation including GPS GLONASS BDS and GALIEO

Science.gov (United States)

Dai, Xiaolei

2014-05-01

In addition to the existing American global positioning system (GPS) and the Russian global navigation satellite system (GLONASS), the new generation of GNSS is emerging and developing, such as the Chinese BeiDou satellite navigation system (BDS) and the European GALILEO system. Multi-constellation is expected to contribute to more accurate and reliable positioning and navigation service. However, the application of multi-constellation challenges the traditional precise orbit determination (POD) strategy that was designed usually for single constellation. In this contribution, we exploit a more rigorous multi-constellation POD strategy for the ongoing IGS multi-GNSS experiment (MGEX) where the common parameters are identical for each system, and the frequency- and system-specified parameters are employed to account for the inter-frequency and inter-system biases. Since the authorized BDS attitude model is not yet released, different BDS attitude model are implemented and their impact on orbit accuracy are studied. The proposed POD strategy was implemented in the PANDA (Position and Navigation Data Analyst) software and can process observations from GPS, GLONASS, BDS and GALILEO together. The strategy is evaluated with the multi-constellation observations from about 90 MGEX stations and BDS observations from the BeiDou experimental tracking network (BETN) of Wuhan University (WHU). Of all the MGEX stations, 28 stations record BDS observation, and about 80 stations record GALILEO observations. All these data were processed together in our software, resulting in the multi-constellation POD solutions. We assessed the orbit accuracy for GPS and GLONASS by comparing our solutions with the IGS final orbit, and for BDS and GALILEO by overlapping our daily orbit solution. The stability of inter-frequency bias of GLONASS and inter-system biases w.r.t. GPS for GLONASS, BDS and GALILEO were investigated. At last, we carried out precise point positioning (PPP) using the multi

Optimizing an Actuator Array for the Control of Multi-Frequency Noise in Aircraft Interiors

Science.gov (United States)

Palumbo, D. L.; Padula, S. L.

1997-01-01

Techniques developed for selecting an optimized actuator array for interior noise reduction at a single frequency are extended to the multi-frequency case. Transfer functions for 64 actuators were obtained at 5 frequencies from ground testing the rear section of a fully trimmed DC-9 fuselage. A single loudspeaker facing the left side of the aircraft was the primary source. A combinatorial search procedure (tabu search) was employed to find optimum actuator subsets of from 2 to 16 actuators. Noise reduction predictions derived from the transfer functions were used as a basis for evaluating actuator subsets during optimization. Results indicate that it is necessary to constrain actuator forces during optimization. Unconstrained optimizations selected actuators which require unrealistically large forces. Two methods of constraint are evaluated. It is shown that a fast, but approximate, method yields results equivalent to an accurate, but computationally expensive, method.

Multi-Frequency Polarimetric SAR Classification Based on Riemannian Manifold and Simultaneous Sparse Representation

Directory of Open Access Journals (Sweden)

Fan Yang

2015-07-01

Full Text Available Normally, polarimetric SAR classification is a high-dimensional nonlinear mapping problem. In the realm of pattern recognition, sparse representation is a very efficacious and powerful approach. As classical descriptors of polarimetric SAR, covariance and coherency matrices are Hermitian semidefinite and form a Riemannian manifold. Conventional Euclidean metrics are not suitable for a Riemannian manifold, and hence, normal sparse representation classification cannot be applied to polarimetric SAR directly. This paper proposes a new land cover classification approach for polarimetric SAR. There are two principal novelties in this paper. First, a Stein kernel on a Riemannian manifold instead of Euclidean metrics, combined with sparse representation, is employed for polarimetric SAR land cover classification. This approach is named Stein-sparse representation-based classification (SRC. Second, using simultaneous sparse representation and reasonable assumptions of the correlation of representation among different frequency bands, Stein-SRC is generalized to simultaneous Stein-SRC for multi-frequency polarimetric SAR classification. These classifiers are assessed using polarimetric SAR images from the Airborne Synthetic Aperture Radar (AIRSAR sensor of the Jet Propulsion Laboratory (JPL and the Electromagnetics Institute Synthetic Aperture Radar (EMISAR sensor of the Technical University of Denmark (DTU. Experiments on single-band and multi-band data both show that these approaches acquire more accurate classification results in comparison to many conventional and advanced classifiers.

MFTF-B quasi-optical ECRH transmission system

International Nuclear Information System (INIS)

Yugo, J.J.; Shearer, J.W.; Ziolkowski, R.W.

1983-01-01

The microwave transmission system for ERCH on MFTF-B will utilize quasi-optical transmission techniques. The system consists of ten gyrotron oscillators: two gyrotrons at 28 GHz, two at 35 GHz, and six at 56 GHz. The 28 and 35 GHz gyrotrons both heat the electrons in the end plug (potential peak) while the 56 GHz sources heat the minimum-B anchor region (potential minimum). Microwaves are launched into a pair of cylindrical mirrors that form a pseudo-cavity which directs the microwaves through the plasma numerous times before they are lost out of the cavity. The cavity allows the microwave beam to reach the resonance zone over a wide range of plasma densities and temperatures. The fundamental electron cyclotron resonance moves to higher axial positions as a result of beta-depression of the magnetic field, doppler shifting of the resonance, and relativistic mass corrections for the electrons. With this system the microwave beam will reach the resonance surface at the correct angle of incidence for any density or temperature without active aiming of the antennas. The cavity also allows the beam to make multiple passes through the plasma to increase the heating efficiency at low temperatures and densities when the single pass absorption is low. In addition, neutral beams and diagnostics have an unobstructed view of the plasma

Multi-disciplinary coupling for integrated design of propulsion systems

Science.gov (United States)

Chamis, C. C.; Singhal, S. N.

1993-01-01

Effective computational simulation procedures are described for modeling the inherent multi-disciplinary interactions for determining the true response of propulsion systems. Results are presented for propulsion system responses including multi-discipline coupling effects via (1) coupled multi-discipline tailoring, (2) an integrated system of multidisciplinary simulators, (3) coupled material-behavior/fabrication-process tailoring, (4) sensitivities using a probabilistic simulator, and (5) coupled materials/structures/fracture/probabilistic behavior simulator. The results show that the best designs can be determined if the analysis/tailoring methods account for the multi-disciplinary coupling effects. The coupling across disciplines can be used to develop an integrated interactive multi-discipline numerical propulsion system simulator.

Microphysics in Multi-scale Modeling System with Unified Physics

Science.gov (United States)

Tao, Wei-Kuo

2012-01-01

Recently, a multi-scale modeling system with unified physics was developed at NASA Goddard. It consists of (1) a cloud-resolving model (Goddard Cumulus Ensemble model, GCE model), (2) a regional scale model (a NASA unified weather research and forecast, WRF), (3) a coupled CRM and global model (Goddard Multi-scale Modeling Framework, MMF), and (4) a land modeling system. The same microphysical processes, long and short wave radiative transfer and land processes and the explicit cloud-radiation, and cloud-land surface interactive processes are applied in this multi-scale modeling system. This modeling system has been coupled with a multi-satellite simulator to use NASA high-resolution satellite data to identify the strengths and weaknesses of cloud and precipitation processes simulated by the model. In this talk, a review of developments and applications of the multi-scale modeling system will be presented. In particular, the microphysics development and its performance for the multi-scale modeling system will be presented.

Arrhythmia Classification Based on Multi-Domain Feature Extraction for an ECG Recognition System

Directory of Open Access Journals (Sweden)

Hongqiang Li

2016-10-01

Full Text Available Automatic recognition of arrhythmias is particularly important in the diagnosis of heart diseases. This study presents an electrocardiogram (ECG recognition system based on multi-domain feature extraction to classify ECG beats. An improved wavelet threshold method for ECG signal pre-processing is applied to remove noise interference. A novel multi-domain feature extraction method is proposed; this method employs kernel-independent component analysis in nonlinear feature extraction and uses discrete wavelet transform to extract frequency domain features. The proposed system utilises a support vector machine classifier optimized with a genetic algorithm to recognize different types of heartbeats. An ECG acquisition experimental platform, in which ECG beats are collected as ECG data for classification, is constructed to demonstrate the effectiveness of the system in ECG beat classification. The presented system, when applied to the MIT-BIH arrhythmia database, achieves a high classification accuracy of 98.8%. Experimental results based on the ECG acquisition experimental platform show that the system obtains a satisfactory classification accuracy of 97.3% and is able to classify ECG beats efficiently for the automatic identification of cardiac arrhythmias.

Efficient coding schemes with power allocation using space-time-frequency spreading

Institute of Scientific and Technical Information of China (English)

Jiang Haining; Luo Hanwen; Tian Jifeng; Song Wentao; Liu Xingzhao

2006-01-01

An efficient space-time-frequency (STF) coding strategy for multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems is presented for high bit rate data transmission over frequency selective fading channels. The proposed scheme is a new approach to space-time-frequency coded OFDM (COFDM) that combines OFDM with space-time coding, linear precoding and adaptive power allocation to provide higher quality of transmission in terms of the bit error rate performance and power efficiency. In addition to exploiting the maximum diversity gain in frequency, time and space, the proposed scheme enjoys high coding advantages and low-complexity decoding. The significant performance improvement of our design is confirmed by corroborating numerical simulations.

Multi-core fiber undersea transmission systems

DEFF Research Database (Denmark)

Nooruzzaman, Md; Morioka, Toshio

2017-01-01

Various potential architectures of branching units for multi-core fiber undersea transmission systems are presented. It is also investigated how different architectures of branching unit influence the number of fibers and those of inline components.......Various potential architectures of branching units for multi-core fiber undersea transmission systems are presented. It is also investigated how different architectures of branching unit influence the number of fibers and those of inline components....

The ECRH system for dite and compass experiments

International Nuclear Information System (INIS)

Riviere, A.C.; Alcock, M.W.; Collins, P.R.; Ainsworth, N.R.; Dellis, A.N.; Moody, D.; Goodenough, S.; Green, S.R.

1987-01-01

Electron Cyclotron Resonance Heating is one of the main auxiliary heating mechanisms in the Culham Laboratory Fusion programme. The system described here is aimed initially at injecting 0.6MW of 60 GHz power into the existing DITE tokamak. A planned increase in power by the addition of further stages will result in a system capable of delivering up to 2MW of power at 60 GHz into the new COMPASS tokamak currently under construction. The scientific aims and the general technical structure of the system are described. The description will cover layout, power supplies, cooling systems, safety and the microwave transmission system necessary to convey the power from the gyrotron sources to the plasmas which can be situated up to 50 metres distant. A highly specialized transmission line consisting of circular overmoded waveguide with filters, bends and mode converters is necessary and data are presented showing the performance of these items and their method of manufacture. Most of these units have been previously tested on the CLEO experiment. In addition to the 2 MW 60 GHz system a single 200 KW source at 28 GHz will be used for preionisation

Optimal Multi-Level Lot Sizing for Requirements Planning Systems

OpenAIRE

Earle Steinberg; H. Albert Napier

1980-01-01

The wide spread use of advanced information systems such as Material Requirements Planning (MRP) has significantly altered the practice of dependent demand inventory management. Recent research has focused on development of multi-level lot sizing heuristics for such systems. In this paper, we develop an optimal procedure for the multi-period, multi-product, multi-level lot sizing problem by modeling the system as a constrained generalized network with fixed charge arcs and side constraints. T...

Generalized Tensor Analysis Model for Multi-Subcarrier Analog Optical Systems

DEFF Research Database (Denmark)

Zhao, Ying; Yu, Xianbin; Zheng, Xiaoping

2011-01-01

We propose and develop a general tensor analysis framework for a subcarrier multiplex analog optical fiber link for applications in microwave photonics. The goal of this work is to construct an uniform method to address nonlinear distortions of a discrete frequency transmission system. We employ....... In addition, it is demonstrated that each corresponding tensor is formally determined by device structures, which allows for a synthesized study of device combinations more systematically. For implementing numerical methods, the practical significance of the tensor model is it simplifies the derivation...... details compared with series-based approaches by hiding the underlying multi-fold summation and index operation. The integrity of the proposed methodology is validated by investigating the classical intensity modulated system. Furthermore, to give an application model of the tensor formalism, we make...

The heat capacity of polyethylene fibers measured by multi-frequency temperature-modulated calorimetry

International Nuclear Information System (INIS)

Pyda, M.; Nowak-Pyda, E.; Wunderlich, B.

2006-01-01

The apparent heat capacity of polyethylene fibers in the melting region was measured by quasi-isothermal, temperature-modulated differential scanning calorimetry (TMDSC) and compared with results from standard differential scanning calorimetry (DSC) and the solid and liquid thermodynamic heat capacity as references from the ATHAS Data Bank. Using a multi-frequency, complex sawtooth modulation in the quasi-isothermal mode disclosed for the first time that the uncorrected apparent heat capacity C p =A Φ /(A T s ω) of the liquid polyethylene fiber increases with increasing frequency (A Φ is the differential heat-flow rate and A T s is the sample temperature). The frequency-dependent heat capacity cannot be represented by the expression: C p =A Φ /(A T s νω)[1+(τνω) 2 ] 0.5 because of a negative τ 2 . The results were later confirmed by independent measurements on single sinusoidal quasi-isothermal TMDSC on the same material. The error is caused by shrinking of the fiber, which deforms the sample pan

Radio frequency electromagnetic field compliance assessment of multi-band and MIMO equipped radio base stations.

Science.gov (United States)

Thors, Björn; Thielens, Arno; Fridén, Jonas; Colombi, Davide; Törnevik, Christer; Vermeeren, Günter; Martens, Luc; Joseph, Wout

2014-05-01

In this paper, different methods for practical numerical radio frequency exposure compliance assessments of radio base station products were investigated. Both multi-band base station antennas and antennas designed for multiple input multiple output (MIMO) transmission schemes were considered. For the multi-band case, various standardized assessment methods were evaluated in terms of resulting compliance distance with respect to the reference levels and basic restrictions of the International Commission on Non-Ionizing Radiation Protection. Both single frequency and multiple frequency (cumulative) compliance distances were determined using numerical simulations for a mobile communication base station antenna transmitting in four frequency bands between 800 and 2600 MHz. The assessments were conducted in terms of root-mean-squared electromagnetic fields, whole-body averaged specific absorption rate (SAR) and peak 10 g averaged SAR. In general, assessments based on peak field strengths were found to be less computationally intensive, but lead to larger compliance distances than spatial averaging of electromagnetic fields used in combination with localized SAR assessments. For adult exposure, the results indicated that even shorter compliance distances were obtained by using assessments based on localized and whole-body SAR. Numerical simulations, using base station products employing MIMO transmission schemes, were performed as well and were in agreement with reference measurements. The applicability of various field combination methods for correlated exposure was investigated, and best estimate methods were proposed. Our results showed that field combining methods generally considered as conservative could be used to efficiently assess compliance boundary dimensions of single- and dual-polarized multicolumn base station antennas with only minor increases in compliance distances. © 2014 Wiley Periodicals, Inc.

Design of a Fractional Order Frequency PID Controller for an Islanded Microgrid: A Multi-Objective Extremal Optimization Method

Directory of Open Access Journals (Sweden)

Huan Wang

2017-10-01

Full Text Available Fractional order proportional-integral-derivative(FOPID controllers have attracted increasing attentions recently due to their better control performance than the traditional integer-order proportional-integral-derivative (PID controllers. However, there are only few studies concerning the fractional order control of microgrids based on evolutionary algorithms. From the perspective of multi-objective optimization, this paper presents an effective FOPID based frequency controller design method called MOEO-FOPID for an islanded microgrid by using a Multi-objective extremal optimization (MOEO algorithm to minimize frequency deviation and controller output signal simultaneously in order to improve finally the efficient operation of distributed generations and energy storage devices. Its superiority to nondominated sorting genetic algorithm-II (NSGA-II based FOPID/PID controllers and other recently reported single-objective evolutionary algorithms such as Kriging-based surrogate modeling and real-coded population extremal optimization-based FOPID controllers is demonstrated by the simulation studies on a typical islanded microgrid in terms of the control performance including frequency deviation, deficit grid power, controller output signal and robustness.

Recent Advances in System Reliability Signatures, Multi-state Systems and Statistical Inference

CERN Document Server

Frenkel, Ilia

2012-01-01

Recent Advances in System Reliability discusses developments in modern reliability theory such as signatures, multi-state systems and statistical inference. It describes the latest achievements in these fields, and covers the application of these achievements to reliability engineering practice. The chapters cover a wide range of new theoretical subjects and have been written by leading experts in reliability theory and its applications.  The topics include: concepts and different definitions of signatures (D-spectra),  their  properties and applications  to  reliability of coherent systems and network-type structures; Lz-transform of Markov stochastic process and its application to multi-state system reliability analysis; methods for cost-reliability and cost-availability analysis of multi-state systems; optimal replacement and protection strategy; and statistical inference. Recent Advances in System Reliability presents many examples to illustrate the theoretical results. Real world multi-state systems...

Multi-bunch Feedback Systems

International Nuclear Information System (INIS)

Lonza, M; Schmickler, H

2014-01-01

Coupled-bunch instabilities excited by the interaction of the particle beam with its surroundings can seriously limit the performance of circular particle accelerators. These instabilities can be cured by the use of active feedback systems based on sensors capable of detecting the unwanted beam motion and actuators that apply the feedback correction to the beam. Advances in electronic technology now allow the implementation of feedback loops using programmable digital systems. Besides important advantages in terms of flexibility and reproducibility, digital systems open the way to the use of novel diagnostic tools and additional features. We first introduce coupled-bunch instabilities, analysing the equation of motion of charged particles and the different modes of oscillation of a multi-bunch beam, showing how they can be observed and measured. Different types of feedback systems will then be presented as examples of real implementations that belong to the history of multi-bunch feedback systems. The main components of a feedback system and the related issues will also be analysed. Finally, we shall focus on digital feedback systems, their characteristics, and features, as well as on how they can be concretely exploited for both the optimization of feedback performance and for beam dynamics studies

A low frequency RFI monitoring system

Science.gov (United States)

Amiri, Shahram; Shankar, N. Udaya; Girish, B. S.; Somashekar, R.

Radio frequency interference (RFI) is a growing problem for research in radio astronomy particularly at wavelengths longer than 2m. For satisfactory operation of a radio telescope, several bands have been protected for radio astronomy observations by the International Telecommunication Union. Since the radiation from cosmic sources are typically 40 to 100 dB below the emission from services operating in unprotected bands, often the out-of-band emission limits the sensitivity of astronomical observations. Moreover, several radio spectral emissions from cosmic sources are present in the frequency range outside the allocated band for radio astronomy. Thus monitoring of RFI is essential before building a receiver system for low frequency radio astronomy. We describe the design and development of an RFI monitoring system operating in the frequency band 30 to 100 MHz. This was designed keeping in view our proposal to extend the frequency of operation of GMRT down to 40 MHz. The monitor is a PC based spectrometer recording the voltage output of a receiver connected to an antenna, capable of digitizing the low frequency RF directly with an 8 bit ADC and sampling bandwidths up to 16 MHz. The system can operate continuously in almost real-time with a loss of only 2% of data. Here we will present the systems design aspects and the results of RFI monitoring carried out at the Raman Research Institute, Bangalore and at the GMRT site in Khodad.

Wearable Multi-Frequency and Multi-Segment Bioelectrical Impedance Spectroscopy for Unobtrusively Tracking Body Fluid Shifts during Physical Activity in Real-Field Applications: A Preliminary Study

Directory of Open Access Journals (Sweden)

Federica Villa

2016-05-01

Full Text Available Bioelectrical Impedance Spectroscopy (BIS allows assessing the composition of body districts noninvasively and quickly, potentially providing important physiological/clinical information. However, neither portable commercial instruments nor more advanced wearable prototypes simultaneously satisfy the demanding needs of unobtrusively tracking body fluid shifts in different segments simultaneously, over a broad frequency range, for long periods and with high measurements rate. These needs are often required to evaluate exercise tests in sports or rehabilitation medicine, or to assess gravitational stresses in aerospace medicine. Therefore, the aim of this work is to present a new wearable prototype for monitoring multi-segment and multi-frequency BIS unobtrusively over long periods. Our prototype guarantees low weight, small size and low power consumption. An analog board with current-injecting and voltage-sensing electrodes across three body segments interfaces a digital board that generates square-wave current stimuli and computes impedance at 10 frequencies from 1 to 796 kHz. To evaluate the information derivable from our device, we monitored the BIS of three body segments in a volunteer before, during and after physical exercise and postural shift. We show that it can describe the dynamics of exercise-induced changes and the effect of a sit-to-stand maneuver in active and inactive muscular districts separately and simultaneously.

Models of Emission-Line Profiles and Spectral Energy Distributions to Characterize the Multi-Frequency Properties of Active Galactic Nuclei

Directory of Open Access Journals (Sweden)

Giovanni La Mura

2017-11-01

Full Text Available The spectra of active galactic nuclei (AGNs are often characterized by a wealth of emission lines with different profiles and intensity ratios that lead to a complicated classification. Their electromagnetic radiation spans more than 10 orders of magnitude in frequency. In spite of the differences between various classes, the origin of their activity is attributed to a combination of emitting components, surrounding an accreting supermassive black hole (SMBH, in the unified model. Currently, the execution of sky surveys, with instruments operating at various frequencies, provides the possibility to detect and to investigate the properties of AGNs on very large statistical samples. As a result of the spectroscopic surveys that allow the investigation of many objects, we have the opportunity to place new constraints on the nature and evolution of AGNs. In this contribution, we present the results obtained by working on multi-frequency data, and we discuss their relations with the available optical spectra. We compare our findings with the AGN unified model predictions, and we present a revised technique to select AGNs of different types from other line-emitting objects. We discuss the multi-frequency properties in terms of the innermost structures of the sources.

Multi-level RF identification system

Science.gov (United States)

Steele, Kerry D.; Anderson, Gordon A.; Gilbert, Ronald W.

2004-07-20

A radio frequency identification system having a radio frequency transceiver for generating a continuous wave RF interrogation signal that impinges upon an RF identification tag. An oscillation circuit in the RF identification tag modulates the interrogation signal with a subcarrier of a predetermined frequency and modulates the frequency-modulated signal back to the transmitting interrogator. The interrogator recovers and analyzes the subcarrier signal and determines its frequency. The interrogator generates an output indicative of the frequency of the subcarrier frequency, thereby identifying the responding RFID tag as one of a "class" of RFID tags configured to respond with a subcarrier signal of a predetermined frequency.

Multi-disciplinary coupling effects for integrated design of propulsion systems

Science.gov (United States)

Chamis, C. C.; Singhal, S. N.

1993-01-01

Effective computational simulation procedures are described for modeling the inherent multi-disciplinary interactions which govern the accurate response of propulsion systems. Results are presented for propulsion system responses including multi-disciplinary coupling effects using coupled multi-discipline thermal, structural, and acoustic tailoring; an integrated system of multi-disciplinary simulators; coupled material behavior/fabrication process tailoring; sensitivities using a probabilistic simulator; and coupled materials, structures, fracture, and probabilistic behavior simulator. The results demonstrate that superior designs can be achieved if the analysis/tailoring methods account for the multi-disciplinary coupling effects. The coupling across disciplines can be used to develop an integrated coupled multi-discipline numerical propulsion system simulator.

A Multi-Model Approach for System Diagnosis

DEFF Research Database (Denmark)

Niemann, Hans Henrik; Poulsen, Niels Kjølstad; Bækgaard, Mikkel Ask Buur

2007-01-01

A multi-model approach for system diagnosis is presented in this paper. The relation with fault diagnosis as well as performance validation is considered. The approach is based on testing a number of pre-described models and find which one is the best. It is based on an active approach......,i.e. an auxiliary input to the system is applied. The multi-model approach is applied on a wind turbine system....

Photometric solution and frequency analysis of the oEA system EW Boo

International Nuclear Information System (INIS)

Zhang, X. B.; Wang, K.; Luo, Y. P.

2015-01-01

We present the first photometric solution and frequency analysis of the neglected oscillating Algol-type (oEA) binary EW Boo. B- and V-band light curves of the star were obtained on 11 nights in 2014. Using the Wilson–Devinney code, the eclipsing light curves were synthesized and the first photometric solution was derived for the binary system. The results reveal that EW Boo could be a semi-detached system with the less-massive secondary component filling its Roche lobe. By subtracting the eclipsing light changes from the data, we obtained the intrinsic pulsating light curves of the hotter, massive primary component. Frequency analysis of residual light shows multi-mode pulsation with the dominant period at 0.01909 days. A preliminary mode identification suggests that the star could be pulsating in non-radial (l = 1) modes. The long-term orbital period variation of the system was also investigated for the first time. An improved orbital period and new ephemerides of the eclipsing binary are given. The O−C analysis indicates a secular period increasing at a rate of dP/dt=2.9×10 −7 days yr −1 , which could be interpreted as mass transfer from the cooler secondary to the primary component.

The Goddard multi-scale modeling system with unified physics

Directory of Open Access Journals (Sweden)

W.-K. Tao

2009-08-01

Full Text Available Recently, a multi-scale modeling system with unified physics was developed at NASA Goddard. It consists of (1 a cloud-resolving model (CRM, (2 a regional-scale model, the NASA unified Weather Research and Forecasting Model (WRF, and (3 a coupled CRM-GCM (general circulation model, known as the Goddard Multi-scale Modeling Framework or MMF. The same cloud-microphysical processes, long- and short-wave radiative transfer and land-surface processes are applied in all of the models to study explicit cloud-radiation and cloud-surface interactive processes in this multi-scale modeling system. This modeling system has been coupled with a multi-satellite simulator for comparison and validation with NASA high-resolution satellite data.

This paper reviews the development and presents some applications of the multi-scale modeling system, including results from using the multi-scale modeling system to study the interactions between clouds, precipitation, and aerosols. In addition, use of the multi-satellite simulator to identify the strengths and weaknesses of the model-simulated precipitation processes will be discussed as well as future model developments and applications.

Practical system for the generation of pulsed quantum frequency combs.

Science.gov (United States)

Roztocki, Piotr; Kues, Michael; Reimer, Christian; Wetzel, Benjamin; Sciara, Stefania; Zhang, Yanbing; Cino, Alfonso; Little, Brent E; Chu, Sai T; Moss, David J; Morandotti, Roberto

2017-08-07

The on-chip generation of large and complex optical quantum states will enable low-cost and accessible advances for quantum technologies, such as secure communications and quantum computation. Integrated frequency combs are on-chip light sources with a broad spectrum of evenly-spaced frequency modes, commonly generated by four-wave mixing in optically-excited nonlinear micro-cavities, whose recent use for quantum state generation has provided a solution for scalable and multi-mode quantum light sources. Pulsed quantum frequency combs are of particular interest, since they allow the generation of single-frequency-mode photons, required for scaling state complexity towards, e.g., multi-photon states, and for quantum information applications. However, generation schemes for such pulsed combs have, to date, relied on micro-cavity excitation via lasers external to the sources, being neither versatile nor power-efficient, and impractical for scalable realizations of quantum technologies. Here, we introduce an actively-modulated, nested-cavity configuration that exploits the resonance pass-band characteristic of the micro-cavity to enable a mode-locked and energy-efficient excitation. We demonstrate that the scheme allows the generation of high-purity photons at large coincidence-to-accidental ratios (CAR). Furthermore, by increasing the repetition rate of the excitation field via harmonic mode-locking (i.e. driving the cavity modulation at harmonics of the fundamental repetition rate), we managed to increase the pair production rates (i.e. source efficiency), while maintaining a high CAR and photon purity. Our approach represents a significant step towards the realization of fully on-chip, stable, and versatile sources of pulsed quantum frequency combs, crucial for the development of accessible quantum technologies.

Development of MARS for multi-dimensional and multi-purpose thermal-hydraulic system analysis

Energy Technology Data Exchange (ETDEWEB)

Lee, Won Jae; Chung, Bub Dong; Kim, Kyung Doo; Hwang, Moon Kyu; Jeong, Jae Jun; Ha, Kwi Seok; Joo, Han Gyu [Korea Atomic Energy Research Institute, T/H Safety Research Team, Yusung, Daejeon (Korea)

2000-10-01

MARS (Multi-dimensional Analysis of Reactor Safety) code is being developed by KAERI for the realistic thermal-hydraulic simulation of light water reactor system transients. MARS 1.4 has been developed as a final version of basic code frame for the multi-dimensional analysis of system thermal-hydraulics. Since MARS 1.3, MARS 1.4 has been improved to have the enhanced code capability and user friendliness through the unification of input/output features, code models and code functions, and through the code modernization. Further improvements of thermal-hydraulic models, numerical method and user friendliness are being carried out for the enhanced code accuracy. As a multi-purpose safety analysis code system, a coupled analysis system, MARS/MASTER/CONTEMPT, has been developed using multiple DLL (Dynamic Link Library) techniques of Windows system. This code system enables the coupled, that is, more realistic analysis of multi-dimensional thermal-hydraulics (MARS 2.0), three-dimensional core kinetics (MASTER) and containment thermal-hydraulics (CONTEMPT). This paper discusses the MARS development program, and the developmental progress of the MARS 1.4 and the MARS/MASTER/CONTEMPT focusing on major features of the codes and their verification. It also discusses thermal hydraulic models and new code features under development. (author)

Development of MARS for multi-dimensional and multi-purpose thermal-hydraulic system analysis

International Nuclear Information System (INIS)

Lee, Won Jae; Chung, Bub Dong; Kim, Kyung Doo; Hwang, Moon Kyu; Jeong, Jae Jun; Ha, Kwi Seok; Joo, Han Gyu

2000-01-01

MARS (Multi-dimensional Analysis of Reactor Safety) code is being developed by KAERI for the realistic thermal-hydraulic simulation of light water reactor system transients. MARS 1.4 has been developed as a final version of basic code frame for the multi-dimensional analysis of system thermal-hydraulics. Since MARS 1.3, MARS 1.4 has been improved to have the enhanced code capability and user friendliness through the unification of input/output features, code models and code functions, and through the code modernization. Further improvements of thermal-hydraulic models, numerical method and user friendliness are being carried out for the enhanced code accuracy. As a multi-purpose safety analysis code system, a coupled analysis system, MARS/MASTER/CONTEMPT, has been developed using multiple DLL (Dynamic Link Library) techniques of Windows system. This code system enables the coupled, that is, more realistic analysis of multi-dimensional thermal-hydraulics (MARS 2.0), three-dimensional core kinetics (MASTER) and containment thermal-hydraulics (CONTEMPT). This paper discusses the MARS development program, and the developmental progress of the MARS 1.4 and the MARS/MASTER/CONTEMPT focusing on major features of the codes and their verification. It also discusses thermal hydraulic models and new code features under development. (author)

Adaptive fuzzy sliding-mode control for multi-input multi-output chaotic systems

International Nuclear Information System (INIS)

Poursamad, Amir; Markazi, Amir H.D.

2009-01-01

This paper describes an adaptive fuzzy sliding-mode control algorithm for controlling unknown or uncertain, multi-input multi-output (MIMO), possibly chaotic, dynamical systems. The control approach encompasses a fuzzy system and a robust controller. The fuzzy system is designed to mimic an ideal sliding-mode controller, and the robust controller compensates the difference between the fuzzy controller and the ideal one. The parameters of the fuzzy system, as well as the uncertainty bound of the robust controller, are tuned adaptively. The adaptive laws are derived in the Lyapunov sense to guarantee the asymptotic stability and tracking of the controlled system. The effectiveness of the proposed method is shown by applying it to some well-known chaotic systems.

EU Developments of the ITER ECRH System

International Nuclear Information System (INIS)

Henderson, M.

2006-01-01

The electron cyclotron (EC) heating and current drive (H (and) CD) system of ITER will deliver 20 MW/CW in the plasma at 170 GHz for H (and) CD in addition to 2.5 MW/3 s at 120 GHz for plasma start-up. The EC system is composed of power supplies (PS), up to 24 H (and) CD gyrotrons (1 to 2 MW tubes), 3 start-up gyrotrons (1 MW tubes), 24 transmission lines and two sets of launching antennas: equatorial (EL) and upper (UL) launchers. Under the present ITER procurement package the EU is responsible for one third of the H (and) CD 170 GHz gyrotrons, all PSs associated with the H (and) CD system, and the whole set (4) of upper launchers. In all areas of participation, the EU EC partnership (coordinated by the European Fusion Development Association - EFDA) aims toward advancing the technology of each of these subsystems. For example, procurement of Pulse Step Modulator (PSM) HVPS is under consideration, which might have equivalent costs to the present ITER design (thyristor HVPS and HV series switch), but with an increased flexibility in operation and variation in the EC power waveform. The EU is at the forefront in gyrotron research and is developing a 2 MW CW 170 GHz coaxial cavity gyrotron offering an increase in output power while maintaining moderate power densities in the gyrotron cavity and collector. THALES R in collaboration with its EFDA partners (FZK, CRPP, TEKES) is manufacturing a series of prototype tubes in three phases of typically 1 s, 100 s and then CW pulse capacity (∼ 20 10 ). A 2 MW, CW gyrotron test facility is being built at CRPP that will be used to develop the 2 MW coaxial tube, in addition to testing various components required by the EC system. EFDA has undertaken a parallel development of two launcher options: front (FS) and remote (RS) steering, with the aim of providing an optimum launcher for ITER weighing EC physics aspects and operation reliability. The FS launcher (ITER reference design) offers a significant enhancement in physics

Improving Multi-Agent Systems Using Jason

DEFF Research Database (Denmark)

Vester, Steen; Boss, Niklas Skamriis; Jensen, Andreas Schmidt

2011-01-01

We describe the approach used to develop the multi-agent system of herders that competed as the Jason-DTU team at the Multi-Agent Programming Contest 2010. We also participated in 2009 with a system developed in the agentoriented programming language Jason which is an extension of AgentSpeak. We ...... used the implementation from 2009 as a foundation and therefore much of the work done this year was on improving that implementation. We present a description which includes design and analysis of the system as well as the main features of our agent team strategy. In addition we discuss...

Multi-photon transitions and Rabi resonance in continuous wave EPR.

Science.gov (United States)

Saiko, Alexander P; Fedaruk, Ryhor; Markevich, Siarhei A

2015-10-01

The study of microwave-radiofrequency multi-photon transitions in continuous wave (CW) EPR spectroscopy is extended to a Rabi resonance condition, when the radio frequency of the magnetic-field modulation matches the Rabi frequency of a spin system in the microwave field. Using the non-secular perturbation theory based on the Bogoliubov averaging method, the analytical description of the response of the spin system is derived for all modulation frequency harmonics. When the modulation frequency exceeds the EPR linewidth, multi-photon transitions result in sidebands in absorption EPR spectra measured with phase-sensitive detection at any harmonic. The saturation of different-order multi-photon transitions is shown to be significantly different and to be sensitive to the Rabi resonance. The noticeable frequency shifts of sidebands are found to be the signatures of this resonance. The inversion of two-photon lines in some spectral intervals of the out-of-phase first-harmonic signal is predicted under passage through the Rabi resonance. The inversion indicates the transition from absorption to stimulated emission or vice versa, depending on the sideband. The manifestation of the primary and secondary Rabi resonance is also demonstrated in the time evolution of steady-state EPR signals formed by all harmonics of the modulation frequency. Our results provide a theoretical framework for future developments in multi-photon CW EPR spectroscopy, which can be useful for samples with long spin relaxation times and extremely narrow EPR lines. Copyright © 2015 Elsevier Inc. All rights reserved.

Multi-angle compound imaging

DEFF Research Database (Denmark)

Jespersen, Søren Kragh; Wilhjelm, Jens Erik; Sillesen, Henrik

1998-01-01

This paper reports on a scanning technique, denoted multi-angle compound imaging (MACI), using spatial compounding. The MACI method also contains elements of frequency compounding, as the transmit frequency is lowered for the highest beam angles in order to reduce grating lobes. Compared to conve......This paper reports on a scanning technique, denoted multi-angle compound imaging (MACI), using spatial compounding. The MACI method also contains elements of frequency compounding, as the transmit frequency is lowered for the highest beam angles in order to reduce grating lobes. Compared...... to conventional B-mode imaging MACI offers better defined tissue boundaries and lower variance of the speckle pattern, resulting in an image with reduced random variations. Design and implementation of a compound imaging system is described, images of rubber tubes and porcine aorta are shown and effects...... on visualization are discussed. The speckle reduction is analyzed numerically and the results are found to be in excellent agreement with existing theory. An investigation of detectability of low-contrast lesions shows significant improvements compared to conventional imaging. Finally, possibilities for improving...

Backscatter Analysis Using Multi-Temporal and Multi-Frequency SAR Data in the Context of Flood Mapping at River Saale, Germany

Directory of Open Access Journals (Sweden)

Sandro Martinis

2015-06-01

Full Text Available In this study, an analysis of multi-temporal and multi-frequency Synthetic Aperture Radar data is performed to investigate the backscatter behavior of various semantic classes in the context of flood mapping in central Europe. The focus is mainly on partially submerged vegetation such as forests and agricultural fields. The test area is located at River Saale, Saxony-Anhalt, Germany, which is covered by a time series of 39 TerraSAR-X data acquired within the time interval December 2009 to June 2013. The data set is supplemented by ALOS PALSAR L-band and RADARSAT-2 C-band data. The time series covers two inundations in January 2011 and June 2013 which allows evaluating backscatter variations between flood periods and normal water level conditions using different radar wavelengths. According to the results, there is potential in detecting flooding beneath vegetation in all microwave wavelengths, even in X-band for sparse vegetation or leaf-off forests.

Nanoelectromechanical systems: Nanodevice motion at microwave frequencies

Science.gov (United States)

Henry Huang, Xue Ming; Zorman, Christian A.; Mehregany, Mehran; Roukes, Michael L.

2003-01-01

It has been almost forgotten that the first computers envisaged by Charles Babbage in the early 1800s were mechanical and not electronic, but the development of high-frequency nanoelectromechanical systems is now promising a range of new applications, including sensitive mechanical charge detectors and mechanical devices for high-frequency signal processing, biological imaging and quantum measurement. Here we describe the construction of nanodevices that will operate with fundamental frequencies in the previously inaccessible microwave range (greater than 1 gigahertz). This achievement represents a significant advance in the quest for extremely high-frequency nanoelectromechanical systems.