The quiescent H-mode regime for high performance edge localized mode-stable operation in future burning plasmas

Energy Technology Data Exchange (ETDEWEB)

Garofalo, A. M., E-mail: garofalo@fusion.gat.com; Burrell, K. H.; Meneghini, O.; Osborne, T. H.; Paz-Soldan, C.; Smith, S. P.; Snyder, P. B.; Turnbull, A. D. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Eldon, D.; Grierson, B. A.; Solomon, W. M. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States); Hanson, J. M. [Columbia University, 2960 Broadway, New York, New York 10027-6900 (United States); Holland, C. [University of California San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States); Huijsmans, G. T. A.; Liu, F.; Loarte, A. [ITER Organization, Route de Vinon sur Verdon, 13067 St Paul Lez Durance (France); Zeng, L. [University of California Los Angeles, P.O. Box 957099, Los Angeles, California 90095-7099 (United States)

2015-05-15

For the first time, DIII-D experiments have achieved stationary quiescent H-mode (QH-mode) operation for many energy confinement times at simultaneous ITER-relevant values of beta, confinement, and safety factor, in an ITER-like shape. QH-mode provides excellent energy confinement, even at very low plasma rotation, while operating without edge localized modes (ELMs) and with strong impurity transport via the benign edge harmonic oscillation (EHO). By tailoring the plasma shape to improve the edge stability, the QH-mode operating space has also been extended to densities exceeding 80% of the Greenwald limit, overcoming the long-standing low-density limit of QH-mode operation. In the theory, the density range over which the plasma encounters the kink-peeling boundary widens as the plasma cross-section shaping is increased, thus increasing the QH-mode density threshold. The DIII-D results are in excellent agreement with these predictions, and nonlinear magnetohydrodynamic analysis of reconstructed QH-mode equilibria shows unstable low n kink-peeling modes growing to a saturated level, consistent with the theoretical picture of the EHO. Furthermore, high density operation in the QH-mode regime has opened a path to a new, previously predicted region of parameter space, named “Super H-mode” because it is characterized by very high pedestals that can be more than a factor of two above the peeling-ballooning stability limit for similar ELMing H-mode discharges at the same density.

Piezoelectric energy harvesting through shear mode operation

International Nuclear Information System (INIS)

Malakooti, Mohammad H; Sodano, Henry A

2015-01-01

Piezoelectric materials are excellent candidates for use in energy harvesting applications due to their high electromechanical coupling properties that enable them to convert input mechanical energy into useful electric power. The electromechanical coupling coefficient of the piezoelectric material is one of the most significant parameters affecting energy conversion and is dependent on the piezoelectric mode of operation. In most piezoceramics, the d 15 piezoelectric shear coefficient is the highest coefficient compared to the commonly used axial and transverse modes that utilize the d 33 and the d 31 piezoelectric strain coefficients. However, complicated electroding methods and challenges in evaluating the performance of energy harvesting devices operating in the shear mode have slowed research in this area. The shear deformation of a piezoelectric layer can be induced in a vibrating sandwich beam with a piezoelectric core. Here, a model based on Timoshenko beam theory is developed to predict the electric power output from a cantilever piezoelectric sandwich beam under base excitations. It is shown that the energy harvester operating in the shear mode is able to generate ∼50% more power compared to the transverse mode for a numerical case study. Reduced models of both shear and transverse energy harvesters are obtained to determine the optimal load resistance in the system and perform an efficiency comparison between two models with fixed and adaptive resistances. (paper)

A Current-Mode Common-Mode Feedback Circuit (CMFB) with Rail-to-Rail Operation

Science.gov (United States)

Suadet, Apirak; Kasemsuwan, Varakorn

2011-03-01

This paper presents a current-mode common-mode feedback (CMFB) circuit with rail-to-rail operation. The CMFB is a stand-alone circuit, which can be connected to any low voltage transconductor without changing or upsetting the existing circuit. The proposed CMFB employs current mirrors, operating as common-mode detector and current amplifier to enhance the loop gain of the CMFB. The circuit employs positive feedback to enhance the output impedance and gain. The circuit has been designed using a 0.18 μm CMOS technology under 1V supply and analyzed using HSPICE with BSIM3V3 device models. A pseudo-differential amplifier using two common sources and the proposed CMFB shows rail to rail output swing (± 0.7 V) with low common-mode gain (-36 dB) and power dissipation of 390 μW.

CMOS Current-mode Operational Amplifier

DEFF Research Database (Denmark)

Kaulberg, Thomas

1992-01-01

current-mode feedback amplifier or a constant bandwidth in a transimpedance feedback amplifier. The amplifier is found to have a gain bandwidth product of 8 MHz, an offset current of 0.8 ¿A (signal-range ±700¿A) and a (theoretically) unlimited slew-rate. The amplifier is realized in a standard CMOS 2......A fully differential-input differential-output current-mode operational amplifier (COA) is described. The amplifier utilizes three second generation current-conveyors (CCII) as the basic building blocks. It can be configured to provide either a constant gain-bandwidth product in a fully balanced...

Multi-mode operations for on-line uninterruptible power supply

DEFF Research Database (Denmark)

Lu, Jinghang; Savaghebi, Mehdi; Guan, Yajuan

2018-01-01

In this paper, the multi-mode operation of the on-line UPS system is investigated and corresponding control strategies are proposed. The proposed control strategies are able to achieve the seamless transition in traditional normal mode, PV-aided normal mode, enhanced eco-mode and burn-in test mod...

Analysis of a large-break LOCA at lower operational modes

Energy Technology Data Exchange (ETDEWEB)

Jeong, H.Y.; Jun, H.Y.; Lee, K. [Korea Electric Power Corporation, Taejon (Korea)

2000-10-01

To improve Technical Specifications and Emergency Operating Guidelines (EOGs) applicable at lower operational modes it is required to perform the safety analysis reflecting the operational characteristics in those modes. Because the component availability and system configurations at lower modes are different from those of power mode, the plant safety at lower modes should be confirmed through independent analyses. In the present study, a large-break loss-of-coolant accident is analyzed to evaluate the containment pressure and temperature control function for the preparation of EOGs applicable at lower modes. To reach the required shutdown condition, the plant cool-down is controlled by the secondary steam flow and auxiliary feedwater. The mass and energy releases from primary system are obtained from RELAP5/MOD3.1 calculation and the containment pressure and temperature are evaluated with CONTEMPT-LT code. The reference plant is Korean Next Generation Reactor having 4,000 MW thermal power. Two cases of cold leg LOCA initiated at Mode 3 with and without SIT operation are calculated. At the given plant conditions, all safety injection pumps are still available. The calculation at the condition of maximum mass and energy release shows that the containment pressure and temperature can be controlled within acceptable criteria, which means the operations of 2 or 4 fan coolers are the possible success paths to achieve the containment P/T control safety function. The peak cladding temperature with minimum safety injection flow does not show remarkable excursion, which implies the lower mode LOCA at Mode 3 can be bounded by the results obtained at full power from the viewpoint of ECCS performance. (author)

Characterization of pseudosingle bunch kick-and-cancel operational mode

Science.gov (United States)

Sun, C.; Robin, D. S.; Steier, C.; Portmann, G.

2015-12-01

Pseudosingle-bunch kick-and-cancel (PSB-KAC) is a new operational mode at the Advanced Light Source of Lawrence Berkeley National Laboratory that provides full timing and repetition rate control for single x-ray pulse users while being fully transparent to other users of synchrotron radiation light. In this operational mode, a single electron bunch is periodically displaced from a main bunch train by a fast kicker magnet with a user-on-demand repetition rate, creating a single x-ray pulse to be matched to a typical laser excitation pulse rate. This operational mode can significantly improve the signal to noise ratio of single x-ray pulse experiments and drastically reduce dose-induced sample damage rate. It greatly expands the capabilities of synchrotron light sources to carry out dynamics and time-of-flight experiments. In this paper, we carry out extensive characterizations of this PSB-KAC mode both numerically and experimentally. This includes the working principle of this mode, resonance conditions and beam stability, experimental setups, and diagnostic tools and measurements.

Characterization of pseudosingle bunch kick-and-cancel operational mode

Directory of Open Access Journals (Sweden)

C. Sun

2015-12-01

Full Text Available Pseudosingle-bunch kick-and-cancel (PSB-KAC is a new operational mode at the Advanced Light Source of Lawrence Berkeley National Laboratory that provides full timing and repetition rate control for single x-ray pulse users while being fully transparent to other users of synchrotron radiation light. In this operational mode, a single electron bunch is periodically displaced from a main bunch train by a fast kicker magnet with a user-on-demand repetition rate, creating a single x-ray pulse to be matched to a typical laser excitation pulse rate. This operational mode can significantly improve the signal to noise ratio of single x-ray pulse experiments and drastically reduce dose-induced sample damage rate. It greatly expands the capabilities of synchrotron light sources to carry out dynamics and time-of-flight experiments. In this paper, we carry out extensive characterizations of this PSB-KAC mode both numerically and experimentally. This includes the working principle of this mode, resonance conditions and beam stability, experimental setups, and diagnostic tools and measurements.

OPERATION MODES AND CHARACTERISTICS OF PLASMA DIPOLE ANTENNA

Directory of Open Access Journals (Sweden)

Nikolay Nikolaevich Bogachev

2014-02-01

Full Text Available Existence modes of  surface electromagnetic wave on a plasma cylinder, operating modes and characteristics of the plasma antenna were studied in this paper. Solutions of the dispersion equation of surface wave were obtained for a plasma cylinder with finite radius for different plasma density values. Operation modes of the plasma asymmetric dipole antenna with finite length and radius were researched by numerical simulation. The electric field distributions of  the plasma antenna in near antenna field and the radiation pattern were obtained. These characteristics were compared to characteristics of the similar metal antenna. Numerical models verification was carried out by comparing of the counted and measured metal antenna radiation patterns.

Optimal mode of operation for biomass production

NARCIS (Netherlands)

Betlem, Ben H.L.; Roffel, Brian; Mulder, P.

2002-01-01

The rate of biomass production is optimised for a predefined feed exhaustion using the residue ratio as a degree of freedom. Three modes of operation are considered: continuous, repeated batch, and repeated fed-batch operation. By means of the Production Curve, the transition points of the optimal

Mixed-mode Operating System for Real-time Performance

OpenAIRE

M.M. Hasan; S. Sultana; C.K. Foo

2017-01-01

The purpose of the mixed-mode system research is to handle devices with the accuracy of real-time systems and at the same time, having all the benefits and facilities of a matured Graphic User Interface (GUI) operating system which is typically nonreal-time. This mixed-mode operating system comprising of a real-time portion and a non-real-time portion was studied and implemented to identify the feasibilities and performances in practical applications (in the context of scheduled the real-time...

Mixed - mode Operating System for Real - time Performance

OpenAIRE

Hasan M. M.; Sultana S.; Foo C.K.

2017-01-01

The purpose of the mixed-mode system research is to handle devices with the accuracy of real-time systems and at the same time, having all the benefits and facilities of a matured Graphic User Interface(GUI)operating system which is typicallynon-real-time. This mixed-mode operating system comprising of a real-time portion and a non-real-time portion was studied and implemented to identify the feasibilities and performances in practical applications (in the context of scheduled the real-time e...

Suppression and nonlinear excitation of parasitic modes in second harmonic gyrotrons operating in a very high order mode

International Nuclear Information System (INIS)

Nusinovich, Gregory S.; Pu, Ruifeng; Granatstein, Victor L.

2015-01-01

In recent years, there was an active development of high-power, sub-terahertz (sub-THz) gyrotrons for numerous applications. For example, a 0.67 THz gyrotron delivering more than 200 kW with about 20% efficiency was developed. This record high efficiency was achieved because the gyrotron operated in a high-order TE 31,8 -mode with the power of ohmic losses less than 10% of the power of outgoing radiation. That gyrotron operated at the fundamental cyclotron resonance, and a high magnetic field of about 27 T was created by a pulse solenoid. For numerous applications, it is beneficial to use gyrotrons at cyclotron harmonics which can operate in available cryomagnets with fields not exceeding 15 T. However, typically, the gyrotron operation at harmonics faces severe competition from parasitic modes at the fundamental resonance. In the present paper, we consider a similar 0.67 THz gyrotron designed for operation in the same TE 31,8 -mode, but at the second harmonic. We focus on two nonlinear effects typical for interaction between the fundamental and second harmonic modes, viz., the mode suppression and the nonlinear excitation of the mode at the fundamental harmonic by the second harmonic oscillations. Our study includes both the analytical theory and numerical simulations performed with the self-consistent code MAGY. The simulations show that stable second harmonic operation in the TE 31,8 mode is possible with only modest sacrifice of efficiency and power

The H-mode operational window as determined from the ITER H-mode database

International Nuclear Information System (INIS)

Ryter, F.; Kardaun, O.J.W.F.; Stroth, U.

1994-01-01

The H-mode is a promising regime for fusion reactors and it is essential to be able to predict its operational window in future devices. The 'H-Mode Database Working Group' started in 1992 to gather, analyze and compare H-mode threshold data from several divertor tokamaks so that predictions could be made. The database and first results were presented and the threshold database has been improved and extended since. The work has two objectives: 1) to predict the minimum heating power necessary to reach the H-mode in future devices, 2) to contribute to physics studies of the L-H transition. (author) 11 refs., 2 figs

Intensity modulated operating mode of the rotating gamma system.

Science.gov (United States)

Sengupta, Bishwambhar; Gulyas, Laszlo; Medlin, Donald; Koroknai, Tibor; Takacs, David; Filep, Gyorgy; Panko, Peter; Godo, Bence; Hollo, Tamas; Zheng, Xiao Ran; Fedorcsak, Imre; Dobai, Jozsef; Bognar, Laszlo; Takacs, Endre

2018-05-01

The purpose of this work was to explore two novel operation modalities of the rotating gamma systems (RGS) that could expand its clinical application to lesions in close proximity to critical organs at risk (OAR). The approach taken in this study consists of two components. First, a Geant4-based Monte Carlo (MC) simulation toolkit is used to model the dosimetric properties of the RGS Vertex 360™ for the normal, intensity modulated radiosurgery (IMRS), and speed modulated radiosurgery (SMRS) operation modalities. Second, the RGS Vertex 360™ at the Rotating Gamma Institute in Debrecen, Hungary is used to collect experimental data for the normal and IMRS operation modes. An ion chamber is used to record measurements of the absolute dose. The dose profiles are measured using Gafchromic EBT3 films positioned within a spherical water equivalent phantom. A strong dosimetric agreement between the measured and simulated dose profiles and penumbra was found for both the normal and IMRS operation modes for all collimator sizes (4, 8, 14, and 18 mm diameter). The simulated falloff and maximum dose regions agree better with the experimental results for the 4 and 8 mm diameter collimators. Although the falloff regions align well in the 14 and 18 mm collimators, the maximum dose regions have a larger difference. For the IMRS operation mode, the simulated and experimental dose distributions are ellipsoidal, where the short axis aligns with the blocked angles. Similarly, the simulated dose distributions for the SMRS operation mode also adopt an ellipsoidal shape, where the short axis aligns with the angles where the orbital speed is highest. For both modalities, the dose distribution is highly constrained with a sharper penumbra along the short axes. Dose modulation of the RGS can be achieved with the IMRS and SMRS modes. By providing a highly constrained dose distribution with a sharp penumbra, both modes could be clinically applicable for the treatment of lesions in close

A CMOS current-mode operational amplifier

DEFF Research Database (Denmark)

Kaulberg, Thomas

1993-01-01

current-mode feedback amplifier or a constant bandwidth in a transimpedance feedback amplifier. The amplifier is found to have a gain-bandwidth product of 3 MHz, an offset current of 0.8 μA (signal range ±700 μA), and a (theoretically) unlimited slew rate. The amplifier is realized in a standard CMOS 2......A fully differential-input, differential-output, current-mode operational amplifier (COA) is described. The amplifier utilizes three second-generation current conveyors (CCIIs) as the basic building blocks. It can be configured to provide either a constant gain-bandwidth product in a fully balanced...

Multi-operational tuneable Q-switched mode-locking Er fibre laser

Science.gov (United States)

Qamar, F. Z.

2018-01-01

A wavelength-spacing tuneable, Q-switched mode-locking (QML) erbium-doped fibre laser based on non-linear polarization rotation controlled by four waveplates and a cube polarizer is proposed. A mode-locked pulse train using two quarter-wave plates and a half-wave plate (HWP) is obtained first, and then an extra HWP is inserted into the cavity to produce different operation regimes. The evolutions of temporal and spectral dynamics with different orientation angles of the extra HWP are investigated. A fully modulated stable QML pulse train is observed experimentally. This is, to the author’s best knowledge, the first experimental work reporting QML operation without adding an extra saturable absorber inside the laser cavity. Multi-wavelength pulse laser operation, multi-pulse train continuous-wave mode-locking operation and pulse-splitting operations are also reported at certain HWP angles. The observed operational dynamics are interpreted as a mutual interaction of dispersion, non-linear effect and insertion loss. This work provides a new mechanism for fabricating cheap tuneable multi-wavelength lasers with QML pulses.

C5 capsule operation modes analysis

International Nuclear Information System (INIS)

Negut, Gh.; Ancuta, Mirela; Stefan, Violeta

2008-01-01

This paper is part of the Nuclear Research Institute Program 13 dedicated to 'TRIGA Research Reactor performance enhancing' and its objective is improving the engineering of the structural materials irradiation. The paper raises the knowledge level on C5 capsule irradiation modes and utilizes previous results in order to increase C5 performances. In the paper the irradiation modes to test zirconium yttrium sample are assessed. These tests are proposed by AECL. There are presented the C5 initial conditions and models. Also. there are presented the thermal hydraulic conditions during normal and accidental operation. The results will be used in the C5 safety report. (authors)

Startup methods for single-mode gyrotron operation

International Nuclear Information System (INIS)

Whaley, D.R.; Tran, M.Q.; Alberti, S.; Tran, T.M.; Antonsen, T.M. Jr.; Dubrovin, A.; Tran, C.

1995-01-01

Experimental results of startup studies on a 118 GHz TE 22,6 gyrotron are presented and compared with theory. The startup paths through the energy-velocity-pitch-angle plane are determined by the time evolution of the beam parameters during the startup phase. These startup paths are modified by changing the anode and cathode voltage rise from zero to their nominal values and are seen to determine the cavity oscillating mode. Experimental results show specifically that competition between the TE 22,6 and TE -19,7 mode can be completely eliminated by use of the proper startup method in a case where a typical triode startup results in oscillation in the competing TE -19,7 mode. These new results are shown to be in excellent agreement with the theory whose approach is general and therefore applicable to gyrotrons operating in any arbitrary cavity mode. (author) 3 figs., 4 refs

Online probabilistic operational safety assessment of multi-mode engineering systems using Bayesian methods

International Nuclear Information System (INIS)

Lin, Yufei; Chen, Maoyin; Zhou, Donghua

2013-01-01

In the past decades, engineering systems become more and more complex, and generally work at different operational modes. Since incipient fault can lead to dangerous accidents, it is crucial to develop strategies for online operational safety assessment. However, the existing online assessment methods for multi-mode engineering systems commonly assume that samples are independent, which do not hold for practical cases. This paper proposes a probabilistic framework of online operational safety assessment of multi-mode engineering systems with sample dependency. To begin with, a Gaussian mixture model (GMM) is used to characterize multiple operating modes. Then, based on the definition of safety index (SI), the SI for one single mode is calculated. At last, the Bayesian method is presented to calculate the posterior probabilities belonging to each operating mode with sample dependency. The proposed assessment strategy is applied in two examples: one is the aircraft gas turbine, another is an industrial dryer. Both examples illustrate the efficiency of the proposed method

Based on Intelligent Robot of E-business Distribution Center Operation Mode Research

Directory of Open Access Journals (Sweden)

Li Juntao

2016-01-01

Full Text Available According to E-business distribution center operation mode in domestic and advanced experience drawing lessons at home and abroad, this paper based on intelligent robot researches E-business distribution center operation mode. And it proposes the innovation logistics storage in E-business and sorting integration system, and elaborates its principle, characteristics, as well as studies its business mode and logistics process, and its parameters and working mode of AGV equipment.

New information technologies in operative control of modes in regional electrical power systems

OpenAIRE

ANDREY D. TEVJASHEV; TATJANA B. TIMOFEEVA

2003-01-01

The problem of development of software for management of modes in electrical power systems in connection with casual character of a load in network is considered. The stochastic mathematical model of a system for operating control of modes in regional electrical power systems is offered. The methods for problem solving of operating control and operating planning of operational modes in regional electrical power systems are developed. The application of the developed models and methods will al...

Dual-Mode Operation of an Optical Lattice Clock Using Strontium and Ytterbium Atoms.

Science.gov (United States)

Akamatsu, Daisuke; Kobayashi, Takumi; Hisai, Yusuke; Tanabe, Takehiko; Hosaka, Kazumoto; Yasuda, Masami; Hong, Feng-Lei

2018-06-01

We have developed an optical lattice clock that can operate in dual modes: a strontium (Sr) clock mode and an ytterbium (Yb) clock mode. Dual-mode operation of the Sr-Yb optical lattice clock is achieved by alternately cooling and trapping 87 Sr and 171 Yb atoms inside the vacuum chamber of the clock. Optical lattices for Sr and Yb atoms were arranged with horizontal and vertical configurations, respectively, resulting in a small distance of the order of between the trapped Sr and Yb atoms. The 1 S 0 - 3 P 0 clock transitions in the trapped atoms were interrogated in turn and the clock lasers were stabilized to the transitions. We demonstrated the frequency ratio measurement of the Sr and Yb clock transitions by using the dual-mode operation of the Sr-Yb optical lattice clock. The dual-mode operation can reduce the uncertainty of the blackbody radiation shift in the frequency ratio measurement, because both Sr and Yb atoms share the same blackbody radiation.

ANALYSIS OF OPTIMUM OPERATING MODES OF POWER TRANSFORMERS UNDER OPERATING CONDITIONS

Directory of Open Access Journals (Sweden)

I. V. Khomenko

2016-12-01

Full Text Available Purpose. The study of parallel operation optimal modes of transformer equipment for a variety of operating conditions: same or different types of transformers, with or without reactive power flows. Methodology. Losses of energy in transformers make 30 % of all losses. Therefore the choice of the economically justified parallel operation of transformers is effective action to reduce losses. Typically, in the calculations of reactive power flows in the transformers are not taken into account. It is interesting to analyze the optimal operating conditions of transformers with and without reactive power flows. Results. Calculations for transformers in distribution networks showed that the inclusion of reactive power flows in transformers significant impact on the calculated optimum regimes of transformers.

Modeling Operating Modes for the Monju Nuclear Power Plant

DEFF Research Database (Denmark)

Lind, Morten; Yoshikawa, Hidekazu; Jørgensen, Sten Bay

2012-01-01

The specification of supervision and control tasks in complex processes requires definition of plant states on various levels of abstraction related to plant operation in start-up, normal operation and shut-down. Modes of plant operation are often specified in relation to a plant decomposition in...... for the Japanese fast breeder reactor plant MONJU....

Mixed-mode Operating System for Real-time Performance

Directory of Open Access Journals (Sweden)

M.M. Hasan

2017-11-01

Full Text Available The purpose of the mixed-mode system research is to handle devices with the accuracy of real-time systems and at the same time, having all the benefits and facilities of a matured Graphic User Interface (GUI operating system which is typically nonreal-time. This mixed-mode operating system comprising of a real-time portion and a non-real-time portion was studied and implemented to identify the feasibilities and performances in practical applications (in the context of scheduled the real-time events. In this research an i8751 microcontroller-based hardware was used to measure the performance of the system in real-time-only as well as non-real-time-only configurations. The real-time portion is an 486DX-40 IBM PC system running under DOS-based realtime kernel and the non-real-time portion is a Pentium III based system running under Windows NT. It was found that mixed-mode systems performed as good as a typical realtime system and in fact, gave many additional benefits such as simplified/modular programming and load tolerance.

Analysis of the ITER cryoplant operational modes

International Nuclear Information System (INIS)

Henry, D.; Journeaux, J.Y.; Roussel, P.; Michel, F.; Poncet, J.M.; Girard, A.; Kalinin, V.; Chesny, P.

2007-01-01

In the framework of an EFDA task, CEA is carrying out an analysis of the various ITER cryoplant operational modes. According to the project integration document, ITER is designed to be operated 365 days per year in order to optimize the available time of the Tokamak. It is anticipated that operation will be performed in long periods separated by maintenance periods (e.g. 10 days continuous operation and 1 week break) with annual or bi-annual major shutdown periods of a few months for maintenance, further installation and commissioning. For this operation schedule, auxiliary subsystems like the cryoplant and the cryodistribution have to cope with different heat loads which depend on the different ITER operating states. The cryoplant consists of four identical 4.5 K refrigerators and two 80 K helium loops coupled with two LN2 modules. All of these cryogenic subsystems have to operate in parallel to remove the heat loads from the magnet, 80 K shields, cryopumps and other small users. After a brief recall of the main particularities of a cryogenic system operating in a Tokamak environment, the first part of this study is dedicated to the assessment of the main ITER operation states. A new design of refrigeration loop for the HTS current leads, the updated layout of the cryodistribution system and revised strategy for operations of the cryopumps have been taken into consideration. The relevant normal operating scenarios of the cryoplant are checked for the typical ITER operating states like plasma operation state, short term stand by, short term maintenance, or test and conditioning state. The second part of the paper is dedicated to the abnormal operating modes coming from the magnets and from those generated by the cryoplant itself. The occurrence of a fast discharge or a quench of the magnets generates large heat loads disturbances and produces exceptional high mass flow rates which have to be managed by the cryoplant, while a failure of a cryogenic component induces

Study on a New Operational Mode of Economic Operation of Islanded Microgrids Using Electric Springs

Directory of Open Access Journals (Sweden)

Zhao Zhiyu

2018-01-01

Full Text Available With the increasing penetration of intermittent renewable energy sources (RESs into microgrids, the original operation mode of power generation determined by load demand faces severe challenges due to the uncertainties of the RESs power output. The electric springs(ESs, as an emerging technology has been verified to be effective in enabling load demand to follow power generation and stabilizing fluctuation of RESs output. This paper presents a new mode of economic operation for island microgrids including non-critical loads with embedded electric springs. Its connotation includes that i the capacity of energy storage can be reduced through the interaction of the energy storage system (ESS and the electric springs, ii the electric springs reduce the stress of peak load regulation and operational cost and iii the demand of microgrids system for ramping ability of generation units is reduced with the buffer of the electric springs. Numerical results show that the coordinated operation between electric springs and energy storage system of microgrids can bring down the investment cost for the ESS and short-term operational cost in the aspect of economic dispatch, reducing requirements for the capacity and ramp ability of the energy storage system in microgrids. Energy buffering can be achieved with lower cost and the load demand can follow power generation in the new operational mode of islanded microgrids using electric springs.

Advances towards QH-mode viability for ELM-stable operation in ITER

International Nuclear Information System (INIS)

Garofalo, A.M.; Burrell, K.H.; DeBoo, J.C.; Schaffer, M.J.; Snyder, P.B.; Solomon, W.M.; Park, J.-K.; Lanctot, M.J.; Reimerdes, H.; McKee, G.R.; Schmitz, L.

2011-01-01

The application of static, non-axisymmetric, nonresonant magnetic fields (NRMFs) to high beta DIII-D plasmas has allowed sustained operation with a quiescent H-mode (QH-mode) edge and both toroidal rotation and neutral beam injected torque near zero. Previous studies have shown that QH-mode operation can be accessed only if sufficient radial shear in the plasma flow is produced near the plasma edge. In past experiments, this flow shear was produced using neutral beam injection (NBI) to provide toroidal torque. In recent experiments, this torque was nearly completely replaced by the torque from applied NRMFs. The application of the NRMFs does not degrade the global energy confinement of the plasma. Conversely, the experiments show that the energy confinement quality increases with lower plasma rotation. Furthermore, the NRMF torque increases plasma resilience to locked modes at low rotation. These results open a path towards QH-mode utilization as an edge-localized mode (ELM)-stable H-mode in the self-heated burning plasma scenario, where toroidal momentum input from NBI may be small or absent.

The Radiation Safety Interlock System for Top-Up Mode Operation at NSRRC

CERN Document Server

Chen Chien Rong; Kao, Sheau-Ping; Liu, Joseph; Sheu, Rong-Jiun; Wang, Jau-Ping

2005-01-01

The radiation safety interlock systems of NSRRC have been operated for more than a decade. Some modification actions have been implemented in the past to perfect the safe operation. The machine and its interlock system were originally designed to operate at the decay mode. Recently some improvement programs to make the machine injection from original decay mode to top-up mode at NSRRC has initiated. For users at experimental area the radiation dose resulted from top-up re-fill injections where safety shutters of beam-lines are opened will dominate. In addition to radiation safety action plans such as upgrading the shielding, enlarging the exclusion zones and improving the injection efficiency, the interlock system for top-up operation is the most important to make sure that injection efficiency is acceptable. To ensure the personnel radiation safety during the top-up mode, the safety interlock upgrade and action plans will be implemented. This paper will summarize the original design logic of the safety inter...

Identifying a "default" visual search mode with operant conditioning.

Science.gov (United States)

Kawahara, Jun-ichiro

2010-09-01

The presence of a singleton in a task-irrelevant domain can impair visual search. This impairment, known as the attentional capture depends on the set of participants. When narrowly searching for a specific feature (the feature search mode), only matching stimuli capture attention. When searching broadly (the singleton detection mode), any oddball captures attention. The present study examined which strategy represents the "default" mode using an operant conditioning approach in which participants were trained, in the absence of explicit instructions, to search for a target in an ambiguous context in which one of two modes was available. The results revealed that participants behaviorally adopted the singleton detection as the default mode but reported using the feature search mode. Conscious strategies did not eliminate capture. These results challenge the view that a conscious set always modulates capture, suggesting that the visual system tends to rely on stimulus salience to deploy attention.

Energy and Exergy Performance of three FPSO Operational Modes

DEFF Research Database (Denmark)

Sánchez, Yamid Alberto Carranza; Junior, Silvio de Oliveira; da Silva, Julio Augusto Mendes

2015-01-01

by the FPSO operator. Energy and exergy criteria have been applied to evaluate and compare the performance of components and systems of the three operational modes of the FPSO. The processing and utilities plants have been modeled and simulated by using Aspen HYSYS®. Results indicate that higher oil content...

Seven Operation Modes and Simulation Models of Solar Heating System with PCM Storage Tank

Directory of Open Access Journals (Sweden)

Juan Zhao

2017-12-01

Full Text Available A physical model and dynamic simulation models of a solar phase-change heat storage heating system with a plate solar collector, phase-change material (PCM storage tank, plate heat exchanger, and auxiliary heat sources were established. A control strategy and numerical models for each of seven different operation modes that cover the entire heating season of the system were developed for the first time. The seven proposed operation modes are Mode 1: free cooling; Mode 2: reservation of heat absorbed by the solar collector in the PCM storage tank when there is no heating demand; Mode 3: direct supply of the heating demand by the solar collector; Mode 4: use of the heat absorbed by the solar collector to meet the heating demands, with the excess heat stored in the PCM storage tank; Mode 5: use of heat stored in the PCM storage tank to meet the heating demands, Mode 6: combined use of heat stored in the PCM storage tank and the auxiliary heating sources to meet the heating demands; and Mode 7: exclusive use of the auxiliary heat sources in order to meet the heating demands. Mathematical models were established for each of the above seven operation modes, taking into consideration the effects of the outdoor meteorological parameters and terminal load on the heating system. The real-time parameters for the entire heating season of the system with respect to the different operation modes can be obtained by solving the simulation models, and used as reference for the optimal design and operation of the actual system.

Symplectic Group Representation of the Two-Mode Squeezing Operator in the Coherent State Basis

Science.gov (United States)

Fan, Hong-Yi; Chen, Jun-Hua

2003-11-01

We find that the coherent state projection operator representation of the two-mode squeezing operator constitutes a loyal group representation of symplectic group, which is a remarkable property of the coherent state. As a consequence, the resultant effect of successively applying two-mode squeezing operators are equivalent to a single squeezing in the two-mode Fock space. Generalization of this property to the 2n-mode case is also discussed. The project supported by National Natural Science Foundation of China under Grant No. 10575057

Laser modes as an eigenfunction of an operator equation

International Nuclear Information System (INIS)

Ripper, J.E.; Campos, M.D.; Pudensi, M.A.A.

A new method is proposed of arriving to an approximate solution into mode problems which cannot be treated by the traditional methods. Basically the idea is to treat the laser mode as an eigenfunction of an operator equation so that the mathematical methods developed to treat the wave equations in quantum mechanics can be used as tools to solve the equation. (L.C.) [pt

Optimal Protection Coordination for Microgrid under Different Operating Modes

Directory of Open Access Journals (Sweden)

Ming-Ta Yang

2013-01-01

Full Text Available Significant consequences result when a microgrid is connected to a distribution system. This study discusses the impacts of bolted three-phase faults and bolted single line-to-ground faults on the protection coordination of a distribution system connected by a microgrid which operates in utility-only mode or in grid-connected mode. The power system simulation software is used to build the test system. The linear programming method is applied to optimize the coordination of relays, and the relays coordination simulation software is used to verify if the coordination time intervals (CTIs of the primary/backup relay pairs are adequate. In addition, this study also proposes a relays protection coordination strategy when the microgrid operates in islanding mode during a utility power outage. Because conventional CO/LCO relays are not capable of detecting high impedance fault, intelligent electrical device (IED combined with wavelet transformer and neural network is proposed to accurately detect high impedance fault and identify the fault phase.

Simulation and Analysis of the Hybrid Operating Mode in ITER

International Nuclear Information System (INIS)

Kessel, C.E.; Budny, R.V.; Indireshkumar, K.

2005-01-01

The hybrid operating mode in ITER is examined with 0D systems analysis, 1.5D discharge scenario simulations using TSC and TRANSP, and the ideal MHD stability is discussed. The hybrid mode has the potential to provide very long pulses and significant neutron fluence if the physics regime can be produced in ITER. This paper reports progress in establishing the physics basis and engineering limitation for the hybrid mode in ITER

Innovative operating modes and techniques for the spaceborne imaging radar-C instrument

Science.gov (United States)

Huneycutt, Bryan L.

1990-01-01

The operation of the spaceborne imaging radar-C (SIR-C) is discussed. The SIR-C instrument has been designed to obtain simultaneous multifrequency and simultaneous multipolarization radar images from a low earth orbit. It is a multiparameter imaging radar which will be flown during at least two different seasons. The instrument has been designed to operate in innovative modes such as the squint alignment mode, the extended aperture mode, the scansar mode, and the interferometry mode. The instrument has been designed to demonstrate innovative engineering techniques such as beam nulling for echo tracking, pulse-repetition frquency hopping for Doppler centroid tracking, generating the frequency step chirp for radar parameter flexibility, block floating point quantizing for data rate compression, and elevation beamwidth broadening for increasing the swath illumination.

Circuit breaker operation and potential failure modes during an earthquake

International Nuclear Information System (INIS)

Lambert, H.E.; Budnitz, R.J.

1987-01-01

This study addresses the effect of a strong-motion earthquake on circuit breaker operation. It focuses on the loss of offsite power (LOSP) transient caused by a strong-motion earthquake at the Zion Nuclear Power Plant. This paper also describes the operator action necessary to prevent core melt if the above circuit breaker failure modes occur simultaneously on three 4.16 KV buses. Numerous circuit breakers important to plant safety, such as circuit breakers to diesel generators and engineered safety systems (ESS), must open and/or close during this transient while strong motion is occurring. Potential seismically-induced circuit-breaker failures modes were uncovered while the study was conducted. These failure modes include: circuit breaker fails to close; circuit breaker trips inadvertently; circuit breaker fails to reclose after trip. The causes of these failure modes include: Relay chatter causes the circuit breaker to trip; Relay chatter causes anti-pumping relays to seal-in which prevents automatic closure of circuit breakers; Load sequencer failures. The incorporation of these failure modes as well as other instrumentation and control failures into a limited scope seismic probabilistic risk assessment is also discussed in this paper

Online channel operation mode: Game theoretical analysis from the supply chain power structure

Directory of Open Access Journals (Sweden)

Song Huang

2015-11-01

Full Text Available Purpose: Dual-channels have been widely used in practice, and the pricing decisions and the online channel operation mode choice have been the core problems in dual-channel supply chain management. This paper focuses on the online channel operation mode choice from the supply chain power structures based on game theoretical analysis. Design/methodology/approach: This paper utilizes three kinds of game theoretical models to analyze the impact of supply chain power structures on the optimal pricing and online channel operation mode choice. Findings: Results derived in this paper indicate that when the self-price elasticity is large, the power structures have no direct impact on the decisions. However, when the self-price elasticity is small and customers’ preference for the online channel is low, then in the MS market, it is better for the retailer to operate the online channel, while in the RS market or in the VN market, it is better for the manufacturer to operate the online channel. Research limitations/implications: In this paper, we do not consider stochastic demand and asymmetric information, which may not well suit the reality. Originality/value: This paper provides a different perspective to analyze the impact of supply chain power structures on the pricing decisions and online channel operation mode choice. The comparison of these two online channel operation modes in this paper is also a unique point.

Gamma irradiation facility: Evaluation of operational modes

International Nuclear Information System (INIS)

Adesanmi, C.A.; Ali, M.S.; Shonowo, O.A.; Akueche, E.C.; Sadare, O.O.; Mustapha, T.K.; Yusuf, U.; Inyanda, A.K.

2007-01-01

The multipurpose Gamma Irradiation Facility (GIF) at the Nuclear Technology Centre (NTC), Sheda Science and Technology Complex (SHETSCO), Abuja, Nigeria is designed as a semi-commercial plant with facilities for research and development (R and D). The design takes into account the different needs of the various research applications which require a wide dose range, a variety of techniques, different product sizes, shapes, mass, volume, densities and types. Programmable doses are used for food irradiation (0.04 - 10 kGy), biological seed mutation breeding and sterile insect technique (STI) (0.01- 5 kGy) sterilization of medical, pharmaceutical and cosmetic products and packages (up to 25 kGy) and cross-linking of polymers (up to 100 kGy). The six different modes of operations (sample elevator, stationary, swiveling, 2-path inner lane and 2-path outer lane and 4-path line) were evaluated. The dose range, mass range and range of irradiation time practicable were established and advantages for radiation processing of food and industrial products were enumerated for the six modes of operations for the first time

OPTIMIZATION OF AGGREGATION AND SEQUENTIAL-PARALLEL EXECUTION MODES OF INTERSECTING OPERATION SETS

Directory of Open Access Journals (Sweden)

G. М. Levin

2016-01-01

Full Text Available A mathematical model and a method for the problem of optimization of aggregation and of sequential- parallel execution modes of intersecting operation sets are proposed. The proposed method is based on the two-level decomposition scheme. At the top level the variant of aggregation for groups of operations is selected, and at the lower level the execution modes of operations are optimized for a fixed version of aggregation.

An overmoded relativistic backward wave oscillator with efficient dual-mode operation

International Nuclear Information System (INIS)

Xiao, Renzhen; Li, Jiawei; Bai, Xianchen; Song, Zhimin; Teng, Yan; Ye, Hu; Li, Xiaoze; Sun, Jun; Chen, Changhua; Zhang, Xiaowei

2014-01-01

A dual-mode operation mechanism in an overmoded relativistic backward wave oscillator is presented. The electron beam interacts with the −1st space harmonic of TM 01 mode synchronously in the slow wave structure. Then the backward propagating TM 01 mode is converted to the forward propagating TM 02 mode. As the phase velocity of the volume harmonic of TM 02 mode is about twice that of the surface harmonic of TM 01 mode, the TM 02 mode also plays an important role in the high-power microwave generation. Particle-in-cell simulation shows that an efficiency of 48% and a significant improvement of the power capacity have been obtained

Transverse mode instabilities in burst operation of high-power fiber laser systems

Science.gov (United States)

Jauregui, Cesar; Stihler, Christoph; Tünnermann, Andreas; Limpert, Jens

2018-02-01

We propose, to the best of our knowledge, the first mitigation strategy for TMI based on controlling the phase shift between the thermally-induced index grating and the modal intensity pattern. In particular, in this work we present a study of transverse mode instabilities in burst operation in a high-power fiber laser system. It is shown that, with a careful choice of the parameters, this operation regime can potentially lead to the mitigation of TMI by forcing an energy transfer from the higher-order-modes into the fundamental mode during the burst.

Distributed Generation using Indirect Matrix Converter in Boost Operating Mode

DEFF Research Database (Denmark)

Liu, Xiong; Loh, Poh Chiang; Wang, Peng

2011-01-01

, reverse power flow operation of IMC can be implemented to meet voltage boost requirement, where the input ac source is connected to the converter's voltage source side and the output utility grid or load is connected to the current source side. This paper proposes control schemes of IMC under reverse...... power flow operation for both grid-connected and isolated modes with distributed generation suggested as a potential application. In grid-connected mode, the commanded power must be extracted from the input ac source to the grid, in addition to guarantee sinusoidal input/output waveforms, unity input...

Controlling the mode of operation of organic transistors through side-chain engineering

KAUST Repository

Giovannitti, Alexander

2016-10-11

Electrolyte-gated organic transistors offer low bias operation facilitated by direct contact of the transistor channel with an electrolyte. Their operation mode is generally defined by the dimensionality of charge transport, where a field-effect transistor allows for electrostatic charge accumulation at the electrolyte/semiconductor interface, whereas an organic electrochemical transistor (OECT) facilitates penetration of ions into the bulk of the channel, considered a slow process, leading to volumetric doping and electronic transport. Conducting polymer OECTs allow for fast switching and high currents through incorporation of excess, hygroscopic ionic phases, but operate in depletion mode. Here, we show that the use of glycolated side chains on a thiophene backbone can result in accumulation mode OECTs with high currents, transconductance, and sharp subthreshold switching, while maintaining fast switching speeds. Compared with alkylated analogs of the same backbone, the triethylene glycol side chains shift the mode of operation of aqueous electrolyte-gated transistors from interfacial to bulk doping/transport and show complete and reversible electrochromism and high volumetric capacitance at low operating biases. We propose that the glycol side chains facilitate hydration and ion penetration, without compromising electronic mobility, and suggest that this synthetic approach can be used to guide the design of organic mixed conductors.

Controlling the mode of operation of organic transistors through side-chain engineering

Science.gov (United States)

Giovannitti, Alexander; Sbircea, Dan-Tiberiu; Inal, Sahika; Nielsen, Christian B.; Bandiello, Enrico; Hanifi, David A.; Sessolo, Michele; Malliaras, George G.; McCulloch, Iain; Rivnay, Jonathan

2016-01-01

Electrolyte-gated organic transistors offer low bias operation facilitated by direct contact of the transistor channel with an electrolyte. Their operation mode is generally defined by the dimensionality of charge transport, where a field-effect transistor allows for electrostatic charge accumulation at the electrolyte/semiconductor interface, whereas an organic electrochemical transistor (OECT) facilitates penetration of ions into the bulk of the channel, considered a slow process, leading to volumetric doping and electronic transport. Conducting polymer OECTs allow for fast switching and high currents through incorporation of excess, hygroscopic ionic phases, but operate in depletion mode. Here, we show that the use of glycolated side chains on a thiophene backbone can result in accumulation mode OECTs with high currents, transconductance, and sharp subthreshold switching, while maintaining fast switching speeds. Compared with alkylated analogs of the same backbone, the triethylene glycol side chains shift the mode of operation of aqueous electrolyte-gated transistors from interfacial to bulk doping/transport and show complete and reversible electrochromism and high volumetric capacitance at low operating biases. We propose that the glycol side chains facilitate hydration and ion penetration, without compromising electronic mobility, and suggest that this synthetic approach can be used to guide the design of organic mixed conductors. PMID:27790983

The periodically pulsed mode of operation of magnet systems in particle accelerators

International Nuclear Information System (INIS)

Stange, G.

1980-01-01

Since in many applications in particle accelerator technology the beam duty factor, defined by the ratio of beam pulse length to the pulse to pulse period, is very small- typically in the order of 10 - 3 to 10 - 9 - it is interesting to operate the beam optical magnetic system in the periodically pulsed mode as well. Thus, by reducing the average Ohmic losses, it is possible to save energy and material. The pulsed mode of operation of magnet systems is especially adapted to those of linear accelerators and their beam transport systems, since linear accelerators are exclusively operated in this mode. But it is equally suitable for transport systems between cyclic accelerators and large storage rings as they are under development at present. (orig./WL) [de

Mevva ion source operated in purely gaseous mode

International Nuclear Information System (INIS)

Yushkov, G.Y.; MacGill, R.A.; Brown, I. G.

2003-01-01

We have operated a vacuum arc ion source in such a way as to form beams of purely gaseous ions. The vacuum arc configuration that is conventionally used to produce intense beams of metal ions was altered so as to form gaseous ion beams, with only minimal changes to the external circuitry and no changes at all internally to the ion source. In our experiments we formed beams from oxygen (O + and O 2 + ), nitrogen (N + and N 2 + ), argon (Ar + ) and carbon dioxide (C + , CO 2 + , O + and O 2 + ) at extraction voltage of 2 to 50 kV. We used a pulsed mode of operation, with beam pulses approximately 50 milliseconds long and repetition rate 10 pulses per second, for a duty cycle of about 50%. Downstream ion beam current as measured by a 5 cm diameter Faraday cup was typically 0.5 mA pulse or about 250 (micro)A time averaged. This time averaged beam current is very similar to that obtained for metal ions when the source is operated in the usual vacuum arc mode. Here we describe the modifications made to the source and the results of our investigations

Recent progress towards advanced mode of operation on JET

International Nuclear Information System (INIS)

Litaudon, X.; Crisanti, F.; Frigione, D.

2003-01-01

This series of slides presents the recent performance of JET concerning ITB (internal transport barrier) operating mode. Pellet refuelling without ITB destruction has been achieved at n eo /n GW ∼ 1. A wide reversed shear ITB (3.6 m) has been sustained with mild ELM (edge localized modes) and no apparent impurity accumulation. ITBs have been maintained thanks to a simultaneous optimisation of the q-profile and edge condition, which opens the way for a steady-state ITB

Thermal characterization of phacoemulsification probes operated in axial and torsional modes.

Science.gov (United States)

Zacharias, Jaime

2015-01-01

To analyze temperature increases and identify potential sources of heat generated when sleeved and sleeveless phacoemulsification probes were operated in axial and torsional modes using the Infiniti Vision System with the Ozil torsional handpiece. Phacodynamics Laboratory, Pasteur Ophthalmic Clinic, Santiago, Chile. Experimental study. Two computer-controlled thermal transfer systems were developed to evaluate the contribution of internal metal stress and tip-to-sleeve friction on heat generation during phacoemulsification using axial and torsional ultrasound modalities. Both systems incorporated infrared thermal imaging and used a black-body film to accurately capture temperature measurements. Axial mode was consistently associated with greater temperature increases than torsional mode whether tips were operated with or without sleeves. In tests involving bare tips, axial mode and torsional mode peaked at 51.7°C and 34.2°C, respectively. In an example using sleeved tips in which a 30.0 g load was applied for 1 second, temperatures for axial mode reached 45°C and for torsional mode, 38°C. Friction between the sleeved probe and the incisional wall contributed more significantly to the temperature increase than internal metal stress regardless of the mode used. In all experiments, the temperature increase observed with axial mode was greater than that observed with torsional mode, even when conditions such as power or amplitude and flow rate were varied. Tip-to-sleeve friction was a more dominant source of phaco probe heating than internal metal stress. The temperature increase due to internal metal stress was greater with axial mode than with torsional mode. Dr. Zacharias received research funding from Alcon Laboratories, Inc., to conduct this study. He has no financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Scaling of mode shapes from operational modal analysis using harmonic forces

Science.gov (United States)

Brandt, A.; Berardengo, M.; Manzoni, S.; Cigada, A.

2017-10-01

This paper presents a new method for scaling mode shapes obtained by means of operational modal analysis. The method is capable of scaling mode shapes on any structure, also structures with closely coupled modes, and the method can be used in the presence of ambient vibration from traffic or wind loads, etc. Harmonic excitation can be relatively easily accomplished by using general-purpose actuators, also for force levels necessary for driving large structures such as bridges and highrise buildings. The signal processing necessary for mode shape scaling by the proposed method is simple and the method can easily be implemented in most measurement systems capable of generating a sine wave output. The tests necessary to scale the modes are short compared to typical operational modal analysis test time. The proposed method is thus easy to apply and inexpensive relative to some other methods for scaling mode shapes that are available in literature. Although it is not necessary per se, we propose to excite the structure at, or close to, the eigenfrequencies of the modes to be scaled, since this provides better signal-to-noise ratio in the response sensors, thus permitting the use of smaller actuators. An extensive experimental activity on a real structure was carried out and the results reported demonstrate the feasibility and accuracy of the proposed method. Since the method utilizes harmonic excitation for the mode shape scaling, we propose to call the method OMAH.

A novel ToF-SIMS operation mode for sub 100 nm lateral resolution: Application and performance

International Nuclear Information System (INIS)

Kubicek, Markus; Holzlechner, Gerald; Opitz, Alexander K.; Larisegger, Silvia; Hutter, Herbert; Fleig, Jürgen

2014-01-01

A novel operation mode for time of flight-secondary ion mass spectrometry (ToF-SIMS) is described for a TOF.SIMS 5 instrument with a Bi-ion gun. It features sub 100 nm lateral resolution, adjustable primary ion currents and the possibility to measure with high lateral resolution as well as high mass resolution. The adjustment and performance of the novel operation mode are described and compared to established ToF-SIMS operation modes. Several examples of application featuring novel scientific results show the capabilities of the operation mode in terms of lateral resolution, accuracy of isotope analysis of oxygen, and combination of high lateral and mass resolution. The relationship between high lateral resolution and operation of SIMS in static mode is discussed.

Stability of the superconductive operating mode in high current-density devices

International Nuclear Information System (INIS)

Wipf, S.L.

1979-01-01

The superconductive operating mode represents a thermal equilibrium that can tolerate a certain amount of disturbance before it is lost. The basin of attraction (BOA), in many ways equivalent to a potential well, is a measure of the size of disturbance needed to lift the device from the superconductive into a resistive operating mode. The BOA for a simple geometry is calculated and discussed. Experimental results are reported, showing how the concept is used to gain information on the disturbances occurring in a superconducting device

Optimal Control of Micro Grid Operation Mode Seamless Switching Based on Radau Allocation Method

Science.gov (United States)

Chen, Xiaomin; Wang, Gang

2017-05-01

The seamless switching process of micro grid operation mode directly affects the safety and stability of its operation. According to the switching process from island mode to grid-connected mode of micro grid, we establish a dynamic optimization model based on two grid-connected inverters. We use Radau allocation method to discretize the model, and use Newton iteration method to obtain the optimal solution. Finally, we implement the optimization mode in MATLAB and get the optimal control trajectory of the inverters.

Recent progress towards advanced mode of operation on JET

Energy Technology Data Exchange (ETDEWEB)

Litaudon, X. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France); Crisanti, F.; Frigione, D. [Association Euratom-ENEA sulla Fusione Centro Ricerche Energia Frascati (Italy)] [and others

2003-07-01

This series of slides presents the recent performance of JET concerning ITB (internal transport barrier) operating mode. Pellet refuelling without ITB destruction has been achieved at n{sub eo}/n{sub GW} {approx} 1. A wide reversed shear ITB (3.6 m) has been sustained with mild ELM (edge localized modes) and no apparent impurity accumulation. ITBs have been maintained thanks to a simultaneous optimisation of the q-profile and edge condition, which opens the way for a steady-state ITB.

QUIESCENT H-MODE, AN ELM-FREE HIGH-CONFINEMENT MODE ON DIII-D WITH POTENTIAL FOR STATIONARY STATE OPERATION

Energy Technology Data Exchange (ETDEWEB)

WEST,WP; BURRELL,KH; deGRASSIE,JS; DOYLE,EJ; GREENFIELD,CM; LASNIER,CJ; SNYDER,PB; ZENG,L

2003-08-01

OAK-B135 The quiescent H-mode (QH-mode) is an ELM-free and stationary state mode of operation discovered on DIII-D. This mode achieves H-mode levels of confinement and pedestal pressure while maintaining constant density and radiated power. The elimination of edge localized modes (ELMs) and their large divertor loads while maintaining good confinement and good density control is of interest to next generation tokamaks. This paper reports on the correlations found between selected parameters in a QH-mode database developed from several hundred DIII-D counter injected discharges. Time traces of key plasma parameters from a QH-mode discharge are shown. On DIII-D the negative going plasma current (a) indicates that the beam injection direction is counter to the plasma current direction, a common feature of all QH-modes. The D{sub {alpha}} time behavior (c) shows that soon after high powered beam heating (b) is applied, the discharge makes a transition to ELMing H-mode, then the ELMs disappear, indicating the start of the QH period that lasts for the remainder of the high power beam heating (3.5 s). Previously published work showing density and temperature profiles indicates that long-pulse, high-triangularity QH discharges develop an internal transport barrier in combination with the QH edge barrier. These discharges are known as quiescent, double-barrier discharges (QDB). The H-factor (d) and stored energy (c) rise then saturate at a constant level and the measured axial and minimum safety factors remain above 1.0 for the entire QH duration. During QDB operation the performance of the plasma can be very good, with {beta}{sub N}*H{sub 89L} product reaching 7 for > 10 energy confinement times. These discharges show promise that a stationary state can be achieved.

QUIESCENT H-MODE, AN ELM-FREE HIGH-CONFINEMENT MODE ON DIII-D WITH POTENTIAL FOR STATIONARY STATE OPERATION

International Nuclear Information System (INIS)

WEST, WP; BURRELL, KH; DeGRASSIE, JS; DOYLE, EJ; GREENFIELD, CM; LASNIER, CJ; SNYDER, PB; ZENG, L.

2003-01-01

OAK-B135 The quiescent H-mode (QH-mode) is an ELM-free and stationary state mode of operation discovered on DIII-D. This mode achieves H-mode levels of confinement and pedestal pressure while maintaining constant density and radiated power. The elimination of edge localized modes (ELMs) and their large divertor loads while maintaining good confinement and good density control is of interest to next generation tokamaks. This paper reports on the correlations found between selected parameters in a QH-mode database developed from several hundred DIII-D counter injected discharges. Time traces of key plasma parameters from a QH-mode discharge are shown. On DIII-D the negative going plasma current (a) indicates that the beam injection direction is counter to the plasma current direction, a common feature of all QH-modes. The D α time behavior (c) shows that soon after high powered beam heating (b) is applied, the discharge makes a transition to ELMing H-mode, then the ELMs disappear, indicating the start of the QH period that lasts for the remainder of the high power beam heating (3.5 s). Previously published work showing density and temperature profiles indicates that long-pulse, high-triangularity QH discharges develop an internal transport barrier in combination with the QH edge barrier. These discharges are known as quiescent, double-barrier discharges (QDB). The H-factor (d) and stored energy (c) rise then saturate at a constant level and the measured axial and minimum safety factors remain above 1.0 for the entire QH duration. During QDB operation the performance of the plasma can be very good, with β N *H 89L product reaching 7 for > 10 energy confinement times. These discharges show promise that a stationary state can be achieved

Predicting core losses and efficiency of SRM in continuous current mode of operation using improved analytical technique

International Nuclear Information System (INIS)

Parsapour, Amir; Dehkordi, Behzad Mirzaeian; Moallem, Mehdi

2015-01-01

In applications in which the high torque per ampere at low speed and rated power at high speed are required, the continuous current method is the best solution. However, there is no report on calculating the core loss of SRM in continuous current mode of operation. Efficiency and iron loss calculation which are complex tasks in case of conventional mode of operation is even more involved in continuous current mode of operation. In this paper, the Switched Reluctance Motor (SRM) is modeled using finite element method and core loss and copper loss of SRM in discontinuous and continuous current modes of operation are calculated using improved analytical techniques to include the minor loop losses in continuous current mode of operation. Motor efficiency versus speed in both operation modes is obtained and compared. - Highlights: • Continuous current method for Switched Reluctance Motor (SRM) is explained. • An improved analytical technique is presented for SRM core loss calculation. • SRM losses in discontinuous and continuous current operation modes are presented. • Effect of mutual inductances on SRM performance is investigated

Predicting core losses and efficiency of SRM in continuous current mode of operation using improved analytical technique

Energy Technology Data Exchange (ETDEWEB)

Parsapour, Amir, E-mail: amirparsapour@gmail.com [Department of Electrical Engineering, University of Isfahan, Isfahan (Iran, Islamic Republic of); Dehkordi, Behzad Mirzaeian, E-mail: mirzaeian@eng.ui.ac.ir [Department of Electrical Engineering, University of Isfahan, Isfahan (Iran, Islamic Republic of); Moallem, Mehdi, E-mail: moallem@cc.iut.ac.ir [Department of Electrical Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of)

2015-03-15

In applications in which the high torque per ampere at low speed and rated power at high speed are required, the continuous current method is the best solution. However, there is no report on calculating the core loss of SRM in continuous current mode of operation. Efficiency and iron loss calculation which are complex tasks in case of conventional mode of operation is even more involved in continuous current mode of operation. In this paper, the Switched Reluctance Motor (SRM) is modeled using finite element method and core loss and copper loss of SRM in discontinuous and continuous current modes of operation are calculated using improved analytical techniques to include the minor loop losses in continuous current mode of operation. Motor efficiency versus speed in both operation modes is obtained and compared. - Highlights: • Continuous current method for Switched Reluctance Motor (SRM) is explained. • An improved analytical technique is presented for SRM core loss calculation. • SRM losses in discontinuous and continuous current operation modes are presented. • Effect of mutual inductances on SRM performance is investigated.

Definition, analysis and experimental investigation of operation modes in hydrogen-renewable-based power plants incorporating hybrid energy storage

International Nuclear Information System (INIS)

Valverde, L.; Pino, F.J.; Guerra, J.; Rosa, F.

2016-01-01

Highlights: • A conceptual analysis of operation modes in energy storage plants is presented. • Key Performance Indicators to select operation modes are provided. • The approach has been applied to a laboratory hybrid power plant. • The methodology provides guidance for the operation of hybrid power plants. - Abstract: This paper is concerned with Operating Modes in hybrid renewable energy-based power plants with hydrogen as the intermediate energy storage medium. Six operation modes are defined according to plant topology and the possibility of operating electrolyzer and fuel cell at steady-power or partial load. A methodology for the evaluation of plant performance is presented throughout this paper. The approach includes a set of simulations over a fully validated model, which are run in order to compare the proposed operation modes in various weather conditions. Conclusions are drawn from the simulation stage using a set of Key Performance Indicators defined in this paper. This analysis yields the conclusion that certain modes are more appropriate from technical and practical standpoints when they are implemented in a real plant. From the results of the simulation assessment, selected operating modes are applied to an experimental hydrogen-based pilot plant to illustrate and validate the performance of the proposed operation modes. Experimental results confirmed the simulation study, pointing out the advantages and disadvantages of each operation mode in terms of performance and equipment durability.

Development of Abnormal Operating Strategies for Station Blackout in Shutdown Operating Mode in Pressurized Water Reactor

Energy Technology Data Exchange (ETDEWEB)

Yoon, Duk-Joo; Lee, Seung-Chan; Sung, Je-Joong; Ha, Sang-Jun [KHNP CRI, Daejeon (Korea, Republic of); Hwang, Su-Hyun [FNC Tech. Co., Yongin (Korea, Republic of)

2016-10-15

Loss of all AC power is classified as one of multiple failure accident by regulatory guide of Korean accident management program. Therefore we need develop strategies for the abnormal operating procedure both of power operating and shutdown mode. This paper developed abnormal operating guideline for loss of all AC power by analysis of accident scenario in pressurized water reactor. This paper analyzed the loss of ultimate heat sink (LOUHS) in shutdown operating mode and developed the operating strategy of the abnormal procedure. Also we performed the analysis of limiting scenarios that operator actions are not taken in shutdown LOUHS. Therefore, we verified the plant behavior and decided operator action to taken in time in order to protect the fuel of core with safety. From the analysis results of LOUHS, the fuel of core maintained without core uncovery for 73 minutes respectively for opened RCS states after the SBO occurred. Therefore, operator action for the emergency are required to take in 73 minutes for opened RCS state. Strategy is to cooldown by using spent fuel pool cooling system. This method required to change the plant design in some plant. In RCS boundary closed state, first abnormal operating strategy in shutdown LOUHS is first abnormal operating strategy in shutdown LOUHS is to remove the residual heat of core by steam dump flow and auxiliary feedwater of SG.

Control software architecture and operating modes of the Model M-2 maintenance system

Energy Technology Data Exchange (ETDEWEB)

Satterlee, P.E. Jr.; Martin, H.L.; Herndon, J.N.

1984-04-01

The Model M-2 maintenance system is the first completely digitally controlled servomanipulator. The M-2 system allows dexterous operations to be performed remotely using bilateral force-reflecting master/slave techniques, and its integrated operator interface takes advantage of touch-screen-driven menus to allow selection of all possible operating modes. The control system hardware for this system has been described previously. This paper describes the architecture of the overall control system. The system's various modes of operation are identified, the software implementation of each is described, system diagnostic routines are described, and highlights of the computer-augmented operator interface are discussed. 3 references, 5 figures.

Control software architecture and operating modes of the Model M-2 maintenance system

International Nuclear Information System (INIS)

Satterlee, P.E. Jr.; Martin, H.L.; Herndon, J.N.

1984-04-01

The Model M-2 maintenance system is the first completely digitally controlled servomanipulator. The M-2 system allows dexterous operations to be performed remotely using bilateral force-reflecting master/slave techniques, and its integrated operator interface takes advantage of touch-screen-driven menus to allow selection of all possible operating modes. The control system hardware for this system has been described previously. This paper describes the architecture of the overall control system. The system's various modes of operation are identified, the software implementation of each is described, system diagnostic routines are described, and highlights of the computer-augmented operator interface are discussed. 3 references, 5 figures

Research on Integrated Control of Microgrid Operation Mode

Science.gov (United States)

Cheng, ZhiPing; Gao, JinFeng; Li, HangYu

2018-03-01

The mode switching control of microgrid is the focus of its system control. According to the characteristics of different control, an integrated control system is put forward according to the detecting voltage and frequency deviation after switching of microgrid operating mode. This control system employs master-slave and peer-to-peer control. Wind turbine and photovoltaic(PV) adopt P/Q control, so the maximum power output can be achieved. The energy storage will work under the droop control if the system is grid-connected. When the system is off-grid, whether to employ droop control or P/f control is determined by system status. The simulation has been done and the system performance can meet the requirement.

Avalanche and streamer mode operation of resistive plate chambers

International Nuclear Information System (INIS)

Cardarelli, R.; Makeev, V.; Santonico, R.

1996-01-01

A resistive plate chamber was operated at voltages increasing in steps of 200 V over a 3 kV interval and the transition between the avalanche and streamer modes was studied. The avalanche amplitude was observed to be exponentially dependent on the operating voltage up to a value, characteristic of the gas, where the avalanche saturation occurs and delayed streamer signals start to appear. Signal waveforms, charge and timing distributions are reported. (orig.)

Novel operation mode for eliminating influence of inclination angle and friction in atomic force microscopy

International Nuclear Information System (INIS)

Wang, Fei; Wang, Yueyu; Zhou, Faquan; Zhao, Xuezeng

2010-01-01

The accuracy of topography imaging in contact force mode of atomic force microscopy (AFM) depends on the one-to-one corresponding relationship between the cantilever deflection and the tip-sample distance, whereas such a relationship cannot be always achieved in the presence of friction and incline angle of sample surface. Recently, we have developed a novel operation mode in which we keep the van der Waals force as constant instead of the applied normal force, to eliminate the effect of inclination angle and friction on topography imaging in the contact force mode. We have improved our AFM to enable the new operation mode for validation. Comparative experiments have been performed and the results have shown that the effect of friction and inclination angle on topography imaging in contact mode of AFM can be eliminated or at least decreased effectively by working in the new operation mode we present.

Simulation of operation modes of isochronous cyclotron by a new interactive method

International Nuclear Information System (INIS)

Taraszkiewicz, R.; Talach, M.; Sulikowski, J.; Doruch, H.; Norys, T.; Sroka, A.; Kiyan, I.N.; )

2007-01-01

Operation mode simulation methods are based on selection of trim coil currents in the isochronous cyclotron for formation of the required magnetic field at a certain level of the main coil current. The traditional current selection method is based on finding a solution for all trim coils simultaneously. After setting the calculated operation mode, it is usually necessary to perform a control measurement of the magnetic field map and to repeat the calculation for a more accurate solution. The new current selection method is based on successively finding solutions for each particular trim coil. The trim coils are taken one by one in reverse order from the edge to the center of the isochronous cyclotron. The new operation mode simulation method is based on the new current selection method. The new method, as against the traditional one, includes iterative calculation of the kinetic energy at the extraction radius. A series of experiments on proton beam formation within the range of working acceleration radii at extraction energies from 32 to 59 MeV, which were carried out at the AIC144 multipurpose isochronous cyclotron (designed mainly for the eye melanoma treatment and production of radioisotopes) at the INP PAS (Cracow), showed that the new method makes unnecessary any control measurements of magnetic fields for getting the desired operation mode, which indicates a high accuracy of the calculation. (authors)

Analysis of Sleep-Mode Downlink Scheduling Operations in EPON Systems

OpenAIRE

Yan, Ying; Dittmann, Lars

2011-01-01

Energy management strategy has been considered as an important component in the future Ethernet Passive Optical Networks (EPONs). In this paper, a sleeping mode operation is studied, and a downlink packet scheduling scheme is analyzed to preserve energy consumption and maintain the required QoS. This paper proposes a novel sleep-mode downlink packet scheduling scheme in order to enhance the sleep control function. Simulation results confirm that the proposed approach offers effective power ma...

Single-mode operation of a coiled multimode fiber amplifier

International Nuclear Information System (INIS)

Koplow, Jeffrey P.; Kliner, Dahv A. V.; Goldberg, Lew

2000-01-01

We report a new approach to obtaining single-transverse-mode operation of a multimode fiber amplifier in which the gain fiber is coiled to induce significant bend loss for all but the lowest-order mode. We demonstrated this method by constructing a coiled amplifier using Yb-doped, double-clad fiber with a core diameter of 25 μm and a numerical aperture of ∼0.1 (V≅7.4) . When the amplifier was operated as an amplified-spontaneous-emission source, the output beam had an M 2 value of 1.09±0.09 ; when seeded at 1064 nm, the slope efficiency was similar to that of an uncoiled amplifier. This technique will permit scaling of pulsed fiber lasers and amplifiers to significantly higher pulse energies and peak powers and cw fiber sources to higher average powers while maintaining excellent beam quality. (c) 2000 Optical Society of America

High-power and long-pulse operation of TE{sub 31,11} mode gyrotron

Energy Technology Data Exchange (ETDEWEB)

Ikeda, Ryosuke, E-mail: ikeda.ryosuke@jaea.go.jp; Kajiwara, Ken; Oda, Yasuhisa; Takahashi, Koji; Sakamoto, Keishi

2015-10-15

Highlights: • We are under development of TE{sub 31,11} mode gyrotron to aim ITER specification. • HE{sub 11} mode purity reached 96% of ITER specification. • Mode competition was suppressed in initial phase of oscillation by anode voltage control. • Maximum output power of 1.2 MW was achieved. • Steady state operation of 500 MJ was achieved. - Abstract: The ITER electron cyclotron system is designed to inject a 20 MW RF beam by using twenty-four 170 GHz/1 MW gyrotrons. JAEA is currently developing a gyrotron having a high-order mode (TE{sub 31,11}) to reduce the heat load in the cavity resonator and achieve an output power greater than 1 MW. The measured radiation profile at the front of the diamond window agreed with the results of the calculation. In order to suppress RF loss in the equatorial and upper port launchers, a high-quality HE{sub 11} mode is required at the exit of the matching optics unit (MOU). An HE{sub 11} mode purity of 96% was achieved by finely adjusting the two mirrors in the MOU. During the oscillation start-up phase, mode competition with counter-rotating TE{sub 29,12} mode was observed on the higher magnetic field side which caused arcing and pressure increase in the gyrotron. To avoid the counter-rotating TE{sub 29,12} mode from being excited, a start-up scenario that controls the voltage between the anode and cathode electrodes at the initial phase of operation was introduced, which was able to achieve a stable start-up of TE{sub 31,11} mode. A 1.2 MW output power having a total electric efficiency of 43% was obtained in high-power experiments. In steady-state operation, a 1000 s oscillation length and output power of 0.51 MW was achieved.

A novel ToF-SIMS operation mode for sub 100 nm lateral resolution: Application and performance.

Science.gov (United States)

Kubicek, Markus; Holzlechner, Gerald; Opitz, Alexander K; Larisegger, Silvia; Hutter, Herbert; Fleig, Jürgen

2014-01-15

A novel operation mode for time of flight-secondary ion mass spectrometry (ToF-SIMS) is described for a TOF.SIMS 5 instrument with a Bi-ion gun. It features sub 100 nm lateral resolution, adjustable primary ion currents and the possibility to measure with high lateral resolution as well as high mass resolution. The adjustment and performance of the novel operation mode are described and compared to established ToF-SIMS operation modes. Several examples of application featuring novel scientific results show the capabilities of the operation mode in terms of lateral resolution, accuracy of isotope analysis of oxygen, and combination of high lateral and mass resolution. The relationship between high lateral resolution and operation of SIMS in static mode is discussed.

N Reactor thermal plume characterization during Pu-only mode of operation

Energy Technology Data Exchange (ETDEWEB)

Ecker, R.M.; Thompson, F.L.; Whelan, G.

1983-04-01

Pacific Northwest Laboratories (PNL) performed field and modeling studies -from March 1982 through June 1983 to characterize the thermal plume from the N Reactor heated water outfall while the N Reactor operated in the Pu-only mode. Part 1 of this report deals with the field studies conducted to characterize the N Reactor thermal plume while in the Pu-only mode of operation. It includes a description of the study area, a description of field tasks and procedures, and data collection results and discussion. Part 2 describes the computer simulation of the thermal plume under different flow conditions and the calibration of the model used. It includes a description of the computer model and the assumptions on which it is based, a presentation of the input data used in this application, and a discussion of modeling results. Because the field studies were restricted by the NPOES permit variance to the spring months when high Columbia River flows prevail the mathematical modeling of the N Reactor thermal plume while the reactor operates in the Pu-only mode is instrumental in characterizing the plume during low Columbia River flows.

Dual-mode operation of 2D material-base hot electron transistors

KAUST Repository

Lan, Yann-Wen; Jr., Carlos M. Torres,; Zhu, Xiaodan; Qasem, Hussam; Adleman, James R.; Lerner, Mitchell B.; Tsai, Shin-Hung; Shi, Yumeng; Li, Lain-Jong; Yeh, Wen-Kuan; Wang, Kang L.

2016-01-01

Vertical hot electron transistors incorporating atomically-thin 2D materials, such as graphene or MoS2, in the base region have been proposed and demonstrated in the development of electronic and optoelectronic applications. To the best of our knowledge, all previous 2D material-base hot electron transistors only considered applying a positive collector-base potential (V-CB > 0) as is necessary for the typical unipolar hot-electron transistor behavior. Here we demonstrate a novel functionality, specifically a dual-mode operation, in our 2D material-base hot electron transistors (e.g. with either graphene or MoS2 in the base region) with the application of a negative collector-base potential (V-CB < 0). That is, our 2D material-base hot electron transistors can operate in either a hot-electron or a reverse-current dominating mode depending upon the particular polarity of VCB. Furthermore, these devices operate at room temperature and their current gains can be dynamically tuned by varying VCB. We anticipate our multi-functional dual-mode transistors will pave the way towards the realization of novel flexible 2D material-based high-density and low-energy hot-carrier electronic applications.

Dual-mode operation of 2D material-base hot electron transistors

KAUST Repository

Lan, Yann-Wen

2016-09-01

Vertical hot electron transistors incorporating atomically-thin 2D materials, such as graphene or MoS2, in the base region have been proposed and demonstrated in the development of electronic and optoelectronic applications. To the best of our knowledge, all previous 2D material-base hot electron transistors only considered applying a positive collector-base potential (V-CB > 0) as is necessary for the typical unipolar hot-electron transistor behavior. Here we demonstrate a novel functionality, specifically a dual-mode operation, in our 2D material-base hot electron transistors (e.g. with either graphene or MoS2 in the base region) with the application of a negative collector-base potential (V-CB < 0). That is, our 2D material-base hot electron transistors can operate in either a hot-electron or a reverse-current dominating mode depending upon the particular polarity of VCB. Furthermore, these devices operate at room temperature and their current gains can be dynamically tuned by varying VCB. We anticipate our multi-functional dual-mode transistors will pave the way towards the realization of novel flexible 2D material-based high-density and low-energy hot-carrier electronic applications.

Dual-mode operation of 2D material-base hot electron transistors.

Science.gov (United States)

Lan, Yann-Wen; Torres, Carlos M; Zhu, Xiaodan; Qasem, Hussam; Adleman, James R; Lerner, Mitchell B; Tsai, Shin-Hung; Shi, Yumeng; Li, Lain-Jong; Yeh, Wen-Kuan; Wang, Kang L

2016-09-01

Vertical hot electron transistors incorporating atomically-thin 2D materials, such as graphene or MoS2, in the base region have been proposed and demonstrated in the development of electronic and optoelectronic applications. To the best of our knowledge, all previous 2D material-base hot electron transistors only considered applying a positive collector-base potential (VCB > 0) as is necessary for the typical unipolar hot-electron transistor behavior. Here we demonstrate a novel functionality, specifically a dual-mode operation, in our 2D material-base hot electron transistors (e.g. with either graphene or MoS2 in the base region) with the application of a negative collector-base potential (VCB transistors can operate in either a hot-electron or a reverse-current dominating mode depending upon the particular polarity of VCB. Furthermore, these devices operate at room temperature and their current gains can be dynamically tuned by varying VCB. We anticipate our multi-functional dual-mode transistors will pave the way towards the realization of novel flexible 2D material-based high-density and low-energy hot-carrier electronic applications.

The Study of Operation Modes and Control Strategies of a Multidirectional MC for Battery Based System

Directory of Open Access Journals (Sweden)

Saman Toosi

2015-01-01

Full Text Available To enhance the performance of stand-alone battery based system and to achieve the continuous power transmission, the behavior of multidirectional matrix converter (MDMC has been analyzed in different operation modes. A systematic method interfacing a renewable source, a storage battery, and a load is proposed for a stand-alone battery based power system (SABBPS to utilize the MDMC as PWM converter, inverter, or PWM converter and inverter in different operation modes. In this study, the Extended Direct Duty Pulse Width Modulation (EDDPWM technique has been applied to control the power flow path between the renewable source, load, and the battery. Corresponding to generator voltage, input frequency, and loads demands, several operating states and control strategies are possible. Therefore, the boundaries and distribution of operation modes are discussed and illustrated to improve the system performance. The mathematical equation of the EDDPWM under different operation modes has been derived to achieve the maximum voltage ratio in each mode. The theoretical and modulation concepts presented have been verified in simulation using MATLAB and experimental testing. Moreover, the THD, ripple, and power flow direction have been analyzed for output current to investigate the behavior of system in each operation mode.

Grid-Forming-Mode Operation of Boost-Power-Stage Converter in PV-Generator-Interfacing Applications

Directory of Open Access Journals (Sweden)

Jukka Viinamäki

2017-07-01

Full Text Available The application of constant power control and inclusion of energy storage in grid-connected photovoltaic (PV energy systems may increase the use of two-stage system structures composed of DC–DC-converter-interfaced PV generator and grid-connected inverter connected in cascade. A typical PV-generator-interfacing DC–DC converter is a boost-power-stage converter. The renewable energy system may operate in three different operation modes—grid-forming, grid-feeding, and grid-supporting modes. In the last two operation modes, the outmost feedback loops are taken from the input terminal of the associated power electronic converters, which usually does not pose stability problems in terms of their input sources. In the grid-forming operation mode, the outmost feedback loops have to be connected to the output terminal of the associated power electronic converters, and hence the input terminal will behave as a negative incremental resistor at low frequencies. This property will limit the operation of the PV interfacing converter in either the constant voltage or constant current region of the PV generator for ensuring stable operation. The boost-power-stage converter can be applied as a voltage or current-fed converter limiting the stable operation region accordingly. The investigations of this paper show explicitly that only the voltage-fed mode would provide feasible dynamic and stability properties as a viable interfacing converter.

Operation of heavily irradiated silicon detectors in non-depletion mode

International Nuclear Information System (INIS)

Verbitskaya, E.; Eremin, V.; Ilyashenko, I.; Li, Z.; Haerkoenen, J.; Tuovinen, E.; Luukka, P.

2006-01-01

The non-depletion detector operation mode has generally been disregarded as an option in high-energy physics experiments. In this paper, the non-depletion operation is examined by detailed analysis of the electric field distribution and the current pulse response of heavily irradiated silicon (Si) detectors. The previously reported model of double junction in heavily irradiated Si detector is further developed and a simulation of the current pulse response has been performed. It is shown that detectors can operate in a non-depletion mode due to the fact that the value of the electric field in a non-depleted region is high enough for efficient carrier drift. This electric field originates from the current flow through the detector and a consequent drop of the potential across high-resistivity bulk of a non-depleted region. It is anticipated that the electric field in a non-depleted region, which is still electrically neutral, increases with fluence that improves the non-depleted detector operation. Consideration of the electric field in a non-depleted region allows the explanation of the recorded double-peak current pulse shape of heavily irradiated Si detectors and definition of the requirements for the detector operational conditions. Detailed reconstruction of the electric field distribution gives new information on radiation effects in Si detectors

Energy-efficient operation of a booster RF system for Taiwan light source operated in top-up mode

International Nuclear Information System (INIS)

Yeh, Meng-Shu; Wang, Chaoen; Chang, Lung-Hai; Chung, Fu-Tsai; Yu, Tsung-Chi; Lin, Ming-Chyuan; Chen, Ling-Jhen; Yang, Tz-Te; Chang, Mei-Hsia; Lin, Yu-Han; Tsai, Ming-Hsun; Lo, Chih-Hung; Liu, Zong-Kai

2015-01-01

Contemporary light sources operate in a top-up mode to maintain their photon intensity quasi-constant so as to improve significantly the thermal stability of the photon beam and to maximize ultimately the average photon flux at a designed maximum operational beam current. Operating in a top-up mode requires frequent beam injection from the synchrotron booster to the storage ring of the light source, but the injection intervals occupy only a tiny portion of the operational time of the integrated machine. To maintain a high operational reliability, the booster RF system practically operates necessarily under injection conditions around the clock and consumes full electric power whether during top-up injection or not. How to decrease the power consumption of the booster RF system during its stand-by time but not to sacrifice the reliability and availability of the RF system is obviously of fundamental interest for routine operation of the light source in a top-up mode. Here, an energy-efficient operation of a booster RF system adaptive to top-up operation of a light source is proposed that has been developed, realized and integrated into the booster RF system of the Taiwan Light Source (TLS), and routinely operated since the end of year 2008. The klystron cathode current and RF gap voltage of the booster's accelerating RF cavity are both periodically modulated to adapt the injection rhythm during top-up operation, which results in decreased consumption of electric power of the booster RF system by more than 78%. The impact on the reliability and availability of the booster RF system has been carefully monitored during the past five operational years, delivering more than 5000 h scheduled user beam time per year. The booster RF system retains its excellent reliability and availability as previously. Neither a decrease of the service time nor an induced reliability issue from the klystron or any high-power high-voltage component of the transmitter has been

Operation Modes and Control Schemes for Internet-Based Teleoperation System with Time Delay

Institute of Scientific and Technical Information of China (English)

曾庆军; 宋爱国

2003-01-01

Teleoperation system plays an important role in executing task under hazard environment. As the computer networks such as the Internet are being used as the communication channel of teleoperation system, varying time delay causes the overall system unstable and reduces the performance of transparency. This paper proposed twelve operation modes with different control schemes for teleoperation on the Internet with time delay. And an optimal operation mode with control scheme was specified for teleoperation with time delay, based on the tradeoff between passivity and transparency properties. It experimentally confirmed the validity of the proposed optimal mode and control scheme by using a simple one DOF master-slave manipulator system.

Mixed - mode Operating System for Real - time Performance

Directory of Open Access Journals (Sweden)

Hasan M. M.

2017-11-01

Full Text Available The purpose of the mixed-mode system research is to handle devices with the accuracy of real-time systems and at the same time, having all the benefits and facilities of a matured Graphic User Interface(GUIoperating system which is typicallynon-real-time. This mixed-mode operating system comprising of a real-time portion and a non-real-time portion was studied and implemented to identify the feasibilities and performances in practical applications (in the context of scheduled the real-time events. In this research an i8751 microcontroller-based hardware was used to measure the performance of the system in real-time-only as well as non-real-time-only configurations. The real-time portion is an 486DX-40 IBM PC system running under DOS-based real-time kernel and the non-real-time portion is a Pentium IIIbased system running under Windows NT. It was found that mixed-mode systems performed as good as a typical real-time system and in fact, gave many additional benefits such as simplified/modular programming and load tolerance.

DC motor operation controlled from a DC/DC power converter in pulse mode with low duty cycle

OpenAIRE

Stefanov, Goce; Kukuseva, Maja; Citkuseva Dimitrovska, Biljana

2016-01-01

In this paper pulse mode of operation of DC motor controlled by DC/DC power converter is analyzed. DC motor operation with time intervals in which the motor operates without output load is of interest. In this mode it is possible the motor to restore energy. Also, in the paper are represented calculations for the amount of the restored energy in the pulse mode operation of the motor for different duty cycles.

Demand and supply-based operating modes--a framework for analyzing health care service production.

Science.gov (United States)

Lillrank, Paul; Groop, P Johan; Malmström, Tomi J

2010-12-01

The structure of organizations that provide services should reflect the possibilities of and constraints on production that arise from the market segments they serve. Organizational segmentation in health care is based on urgency and severity as well as disease type, bodily function, principal method, or population subgroup. The result is conflicting priorities, goals, and performance metrics. A managerial perspective is needed to identify activities with similar requirements for integration, coordination, and control. The arguments in this article apply new reasoning to the previous literature. The method used in this article to classify health care provision distinguishes different types of health problems that share generic constraints of production. The analysis leads to seven different demand-supply combinations, each with its own operational logic. These are labeled demand and supply-based operating modes (DSO modes), and constitute the managerial building blocks of health care organizations. The modes are Prevention, Emergency, One visit, Project, Elective, Cure, and Care. As analytical categories the DSO modes can be used to understand current problems. Several operating modes in one unit create managerial problems of conflicting priorities, goals, and performance metrics. The DSO modes are constructed as managerially homogeneous categories or care platforms responding to general types of demand, and supply constraints. The DSO modes bring methods of industrial management to bear on efforts to improve health care. © 2010 Milbank Memorial Fund. Published by Wiley Periodicals Inc.

Research on Group Operation Mode of Once-through Steam Generator

International Nuclear Information System (INIS)

Hao, Cheng Ming; Liu, Xinkai; Peng, Min Jun; Xia, Genglei

2011-01-01

Integrated Pressurized Water Reactor (IPWR) owns more than one once-through steam generators (OTSGs). Flow instability may occur in secondary side of OTSG under certain conditions. Trying to avoid the occurrence of flow instability is of great important for the safe and stable operation of OTSG. Because of the fact that flow instability often occurs in certain regions, so when OTSGs operate with low load, OTSGs can be separated into several groups, which can avoid flow instability. In this paper, operational characteristics of IPWR are analyzed by RELAP5/MOD3.4 code and during the discussion of group operation, a rapid change load operation scheme using OTSG group operation mode which can be used in IPWR is proposed

Research on Group Operation Mode of Once-through Steam Generator

Energy Technology Data Exchange (ETDEWEB)

Hao, Cheng Ming; Liu, Xinkai; Peng, Min Jun; Xia, Genglei [Harbin Engineering University, Harbin (China)

2011-08-15

Integrated Pressurized Water Reactor (IPWR) owns more than one once-through steam generators (OTSGs). Flow instability may occur in secondary side of OTSG under certain conditions. Trying to avoid the occurrence of flow instability is of great important for the safe and stable operation of OTSG. Because of the fact that flow instability often occurs in certain regions, so when OTSGs operate with low load, OTSGs can be separated into several groups, which can avoid flow instability. In this paper, operational characteristics of IPWR are analyzed by RELAP5/MOD3.4 code and during the discussion of group operation, a rapid change load operation scheme using OTSG group operation mode which can be used in IPWR is proposed.

Operation of Ferroelectric Plasma Sources in a Gas Discharge Mode

International Nuclear Information System (INIS)

Dunaevsky, A.; Fisch, N.J.

2004-01-01

Ferroelectric plasma sources in vacuum are known as sources of ablative plasma, formed due to surface discharge. In this paper, observations of a gas discharge mode of operation of the ferroelectric plasma sources (FPS) are reported. The gas discharge appears at pressures between approximately 20 and approximately 80 Torr. At pressures of 1-20 Torr, there is a transition from vacuum surface discharge to the gas discharge, when both modes coexist and the surface discharges sustain the gas discharge. At pressures between 20 and 80 Torr, the surface discharges are suppressed, and FPS operate in pure gas discharge mode, with the formation of almost uniform plasma along the entire surface of the ceramics between strips. The density of the expanding plasma is estimated to be about 1013 cm-3 at a distance of 5.5 mm from the surface. The power consumption of the discharge is comparatively low, making it useful for various applications. This paper also presents direct measurements of the yield of secondary electron emission from ferroelectric ceramics, which, at low energies of primary electrons, is high and dependent on the polarization of the ferroelectric material

A multi-mode operation control strategy for flexible microgrid based on sliding-mode direct voltage and hierarchical controls.

Science.gov (United States)

Zhang, Qinjin; Liu, Yancheng; Zhao, Youtao; Wang, Ning

2016-03-01

Multi-mode operation and transient stability are two problems that significantly affect flexible microgrid (MG). This paper proposes a multi-mode operation control strategy for flexible MG based on a three-layer hierarchical structure. The proposed structure is composed of autonomous, cooperative, and scheduling controllers. Autonomous controller is utilized to control the performance of the single micro-source inverter. An adaptive sliding-mode direct voltage loop and an improved droop power loop based on virtual negative impedance are presented respectively to enhance the system disturbance-rejection performance and the power sharing accuracy. Cooperative controller, which is composed of secondary voltage/frequency control and phase synchronization control, is designed to eliminate the voltage/frequency deviations produced by the autonomous controller and prepare for grid connection. Scheduling controller manages the power flow between the MG and the grid. The MG with the improved hierarchical control scheme can achieve seamless transitions from islanded to grid-connected mode and have a good transient performance. In addition the presented work can also optimize the power quality issues and improve the load power sharing accuracy between parallel VSIs. Finally, the transient performance and effectiveness of the proposed control scheme are evaluated by theoretical analysis and simulation results. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Quiescent H-mode operation using torque from non-axisymmetric, non-resonant magnetic fields

International Nuclear Information System (INIS)

Burrell, K.H.; Garofalo, A.M.; Osborne, T.H.; Snyder, P.B.; Solomon, W.M.; Park, J.-K.; Fenstermacher, M.E.; Orlov, D.M.

2013-01-01

Quiescent H-mode (QH-mode) sustained by magnetic torque from non-axisymmetric magnetic fields is a promising operating mode for future burning plasmas including ITER. Using magnetic torque from n = 3 fields to replace counter-I p torque from neutral beam injection, we have achieved long duration, counter-rotating QH-mode operation with neutral beam injection (NBI) torque ranging continuously from counter-I p up to co-I p values of about 1 N m. This co-I p torque is about 3 times the scaled torque that ITER will have. This range also includes operation at zero net NBI torque, applicable to rf wave heated plasmas. These n = 3 fields have been created using coils either inside or, most recently, outside the toroidal coils. Experiments utilized an ITER-relevant lower single-null plasma shape and were done with ITER-relevant values ν ped * ∼0.08, β T ped ∼ 1%$ and β N = 2. Discharges have confinement quality H 98y2 = 1.3, exceeding the value required for ITER. Initial work with low q 95 = 3.4 QH-mode plasmas transiently reached fusion gain values of G = β N H 89 /q 95 2 =0.4, which is the desired value for ITER; the limits on G have not yet been established. This paper also includes the most recent results on QH-mode plasmas run without n = 3 fields and with co-I p NBI; these shots exhibit co-I p plasma rotation and require NBI torque ⩾2 N m. The QH-mode work to date has made significant contact with theory. The importance of edge rotational shear is consistent with peeling–ballooning mode theory. We have seen qualitative and quantitative agreement with the predicted torque from neoclassical toroidal viscosity. (paper)

Operating modes of electrochemical H-concentration probes for tritium sensors

International Nuclear Information System (INIS)

Juhera, E.; Colominas, S.; Abellà, J.

2015-01-01

Highlights: • Synthesis and chemical characterization of Sr(Ce_0_._9–Zr_0_._1)_0_._9_5Yb_0_._0_5O_3_−_α proton conductor ceramic. • Evaluation of the sensor performance at different hydrogen concentrations. • Two different operating modes of the sensors: amperometric and potentiometric. • In amperometric mode sensor sensitivity can be tuned by changing the applied voltage. - Abstract: Potentiometric hydrogen sensors using different solid-state electrolytes have been designed and tested at the Electrochemical Methods Lab at Institut Quimic de Sarria (IQS). The most promising element (Sr(Ce_0_._9–Zr_0_._1)_0_._9_5Yb_0_._0_5O_3_−_α) has been selected for this work in order to evaluate the sensor performance at different hydrogen concentrations in two different operating modes: amperometric and potentiometric. In addition, the sensor response has been evaluated at different working temperatures (500, 575 and 650 °C). The experiments performed proved that when the sensor was used in a potentiometric mode, there is a threshold hydrogen concentration that the sensor can detect depending on the working conditions; 15 mbar at 575 °C and 10 mbar 650 °C. At 500 °C the minimum working temperature of this ceramic has not been achieved, so large deviations between experimental data and theoretical calculations has been obtained. When the sensor was used in an amperometric mode the obtained currents increased as a function of the applied voltage. At a fixed potential, the higher the temperature the higher the current was. So the sensor sensitivity can be tuned by changing the applied voltage at a fixed temperature and hydrogen concentration.

Analysis of Sleep-Mode Downlink Scheduling Operations in EPON Systems

DEFF Research Database (Denmark)

Yan, Ying; Dittmann, Lars

2011-01-01

Energy management strategy has been considered as an important component in the future Ethernet Passive Optical Networks (EPONs). In this paper, a sleeping mode operation is studied, and a downlink packet scheduling scheme is analyzed to preserve energy consumption and maintain the required Qo......S. This paper proposes a novel sleep-mode downlink packet scheduling scheme in order to enhance the sleep control function. Simulation results confirm that the proposed approach offers effective power management on the basis of the traffic conditions. The trade-off between network performances and the power...

Single mode operation of a hybrid optically pumped D2O far infrared laser

International Nuclear Information System (INIS)

Yuan, D.C.; Siegrist, M.R.

1990-04-01

We have achieved single mode operation in a hybrid optically pumped D 2 O far infrared laser. The active volume of the resonator was divided into two sections separated by a thin plastic foil. The larger section served as the main gain medium and the shorter section as mode selective element. The vapor pressure in the smaller volume was either very low or alternatively about 3 times higher than the pressure in the main part. In both cases single mode operation was achieved without any reduction of the total output energy. (author) 13 refs., 7 figs

Flight Simulator Evaluation of Enhanced Propulsion Control Modes for Emergency Operation

Science.gov (United States)

Litt, Jonathan, S; Sowers, T.; Owen, A., Karl; Fulton, Christopher, E.; Chicatelli, Amy, K.

2012-01-01

This paper describes piloted evaluation of enhanced propulsion control modes for emergency operation of aircraft. Fast Response and Overthrust modes were implemented to assess their ability to help avoid or mitigate potentially catastrophic situations, both on the ground and in flight. Tests were conducted to determine the reduction in takeoff distance achievable using the Overthrust mode. Also, improvements in Dutch roll damping, enabled by using yaw rate feedback to the engines to replace the function of a stuck rudder, were investigated. Finally, pilot workload and ability to handle the impaired aircraft on approach and landing were studied. The results showed that improvement in all aspects is possible with these enhanced propulsion control modes, but the way in which they are initiated and incorporated is important for pilot comfort and perceived benefit.

Operational range and transport barrier of the H-mode in the stellarator W7-AS

International Nuclear Information System (INIS)

Hirsch, M.; Amadeo, P.; Anton, M.; Baldzuhn, J.; Brakel, R.; Bleuel, J.; Fiedler, S.; Geist, T.; Grigull, P.; Hartfuss, H.J.; Jaenicke, R.; Kick, M.; Kisslinger, J.; Koponen, J.; Wagner, F.; Weller, A.; Wobig, H.; Zoletnik, S.; Holzhauer, E.

1998-01-01

In W7-AS the H-mode is characterized by an edge transport barrier localized in the first 3-4 cm inside the separatrix. In the ELMy H-mode preceding the quiescent state ELMs appear as a sudden breakdown of the edge transport barrier in coincidence with bursts of fluctuations. Between ELMs fluctuations are identical to those of the quiescent H-mode. The operational range of the quiescent H-mode is determined by narrow windows of the edge rotational transform and a threshold edge electron density. In contrast, ELM-like events are observed for a variety of plasma conditions by far exceeding the narrow operational windows for the quiescent state. (author)

MATHEMATICAL AND EXPERIMENTAL MODELING OF CENTRIFUGAL TURBOMACHINES’ OPERATING MODES WITH A COAXIAL ARRANGEMENT OF IMPELLERS

Directory of Open Access Journals (Sweden)

S. V. Podbolotov

2018-03-01

Full Text Available The relevance of this work is conditioned by the possibility of expanding the range of efficient operation of the turbine by changing the flow pattern of the fluid flow from stage to stage. The purpose of the work is to establish rational modes of operation of turbo machines with coaxially mounted impellers. Research methodology: in this work, we used a systematic approach, which includes the analysis of the results of mathematical modeling and experimental studies. Results. We carried out the analysis of the influence of operating modes on the pressure developed by the turbine. These operating modes include directions of rotation of impellers and the value of their circumferential speeds. The study analyzed the two options of installation: the rotation of the wheels in one direction and the rotation of the wheels in the opposite direction. The theoretical studies were based on a well-known Euler theory under certain assumptions: the cross section averaged for all flow settings; the motion of impellers was made one-dimensional and axisymmetric; the impellers have an infinite number of infinitely thin blades; the flow of fluid does not have viscosity, and the influence of friction forces is absent. The experimental aerodynamic characteristics of the centrifugal turbo machine with coaxial arrangement of driving wheels were obtained on an especially designed aerodynamic stand. Pressure-flow characteristics obtained theoretically and experimentally are presented. Conclusion. The use of coaxial impellers contributes to developing pressure and allows you to extend the range of efficient operation of centrifugal turbo machines. The most rational mode of operation of coaxially mounted impellers is the counter rotation mode. The increase of pressure developed by the Turbo machinery at work in this mode is proven theoretically and confirmed experimentally. Sufficient convergence of mathematical and experimental studies suggests the reliability of the

Efficient single-mode operation of a cladding-pumped ytterbium-doped helical-core fiber laser.

Science.gov (United States)

Wang, P; Cooper, L J; Sahu, J K; Clarkson, W A

2006-01-15

A novel approach to achieving robust single-spatial-mode operation of cladding-pumped fiber lasers with multimode cores is reported. The approach is based on the use of a fiber geometry in which the core has a helical trajectory within the inner cladding to suppress laser oscillation on higher-order modes. In a preliminary proof-of-principle study, efficient single-mode operation of a cladding-pumped ytterbium-doped helical-core fiber laser with a 30 microm diameter core and a numerical aperture of 0.087 has been demonstrated. The laser yielded 60.4 W of output at 1043 nm in a beam with M2 clad fiber lasers.

Multi-Mode Operation for On-line Uninterruptible Power Supply System

DEFF Research Database (Denmark)

Lu, Jinghang; Savaghebi, Mehdi; Golestan, Saeed

2018-01-01

To enhance the robustness and disturbance rejection ability of an on-line uninterruptible power supply (UPS) system, an Internal Model Control (IMC)-based DC-link voltage regulation method is proposed in this paper. Furthermore, the multi-mode operations of the on-line UPS system are investigated...

New operational modes for the Ta2O5-based electrolyte conductance cell

NARCIS (Netherlands)

Olthuis, Wouter; Smith, A.; van der Zalm, R.A.J.; Bergveld, Piet

1994-01-01

Based on the recently presented conductance cell, two specific operational modes are proposed. In the oscillator mode, the conductivity of the electrolyte determines the frequency of an oscillator, experimentally obtaining a shift from 10 to 27 kHz for a KCl concentration range from 0.5 to 100 mM.

Vēja elektrostaciju ietekme uz putniem rudens migrācijas laikā Baltijas jūras piekrastē (Liepāja, Latvija): metodikas aprobācija un pirmie rezultāti

OpenAIRE

Krotova, Ieva

2015-01-01

Vēja enerģijas izmantošana ir potenciāli izdevīgs ziemeļvalstu atjaunojamo energoresursu avots, kas nerada regulāru gaisa, ūdens un augsnes piesārņojumu. Latvijas rietumu un ziemeļu daļas ir piemērotas vēja enerģijas iegūšanai. Svarīgs aspekts vēja enerģētikas attīstībā ir tās ietekme uz vidi un dzīvajiem organismiem. Teorētiskajā daļā tika veikts vēja enerģētikas teorijas un citu valstu vēja elektrostacijas (VES) ietekmes pētījumu metodikas un iegūto rezultātu apskats šādās tēmās – vēja ...

Operation mode switchable charge-trap memory based on few-layer MoS2

Science.gov (United States)

Hou, Xiang; Yan, Xiao; Liu, Chunsen; Ding, Shijin; Zhang, David Wei; Zhou, Peng

2018-03-01

Ultrathin layered two-dimensional (2D) semiconductors like MoS2 and WSe2 have received a lot of attention because of their excellent electrical properties and potential applications in electronic devices. We demonstrate a charge-trap memory with two different tunable operation modes based on a few-layer MoS2 channel and an Al2O3/HfO2/Al2O3 charge storage stack. Our device shows excellent memory properties under the traditional three-terminal operation mode. More importantly, unlike conventional charge-trap devices, this device can also realize the memory performance with just two terminals (drain and source) because of the unique atomic crystal electrical characteristics. Under the two-terminal operation mode, the erase/program current ratio can reach up to 104 with a stable retention property. Our study indicates that the conventional charge-trap memory cell can also realize the memory performance without the gate terminal based on novel two dimensional materials, which is meaningful for low power consumption and high integration density applications.

Trickle-Charge: a New Operational Mode for PEP-II

International Nuclear Information System (INIS)

Kozanecki, W.; Colocho, W.S.; Decker, F.-J.; Ecklund, S.; Fisher, A.S.; Iverson, R.H.; O'Grady, C.; Seeman, J.; Sullivan, M.K.; Turner, J.L.; Weaver, M.; Wienands, U.; SLAC

2005-01-01

In regular top-up-and-coast operation, PEP-II average luminosity is about 70-75% of the peak luminosity due to detector ramp-down and ramp-up times plus the time it takes to top-up both beams. We recently commissioned a new operational mode where the Low Energy Ring is injected continuously without ramping down the detector. The benefits--increased luminosity lifetime and roughly half the number of top-ups per shift--were expected to give an increase in delivered luminosity of about 15% at the same peak luminosity; this was confirmed in test runs. In routine trickle operation, however, it appears that the increase in delivered luminosity is more than twice that due to an increase in availability credited to the more stable operating conditions during trickle operation. Further gains were made when continuous injection was extended to the high energy ring as well. In this paper we will present our operational experience as well as some of the diagnostics we use to monitor and maintain tuning of the machine in order to control injection background and protect the detector

A fluid-coupled transmitting CMUT operated in collapse mode : Semi-analytic modeling and experiments

NARCIS (Netherlands)

Pekař, Martin; van Nispen, Stephan H.M.; Fey, Rob H.B.; Shulepov, Sergei; Mihajlović, Nenad; Nijmeijer, Henk

2017-01-01

An electro-mechanical, semi-analytic, reduced-order (RO) model of a fluid-loaded transmitting capacitive-micromachined ultrasound transducer (CMUT) operated in collapse mode is developed. Simulation of static deflections, approximated by a linear combination of six mode shapes, are benchmarked

The optimization of nuclear power plants operation modes in emergency situations

Science.gov (United States)

Zagrebayev, A. M.; Trifonenkov, A. V.; Ramazanov, R. N.

2018-01-01

An emergency situations resulting in the necessity for temporary reactor trip may occur at the nuclear power plant while normal operating mode. The paper deals with some of the operation c aspects of nuclear power plant operation in emergency situations and during threatened period. The xenon poisoning causes limitations on the variety of statements of the problem of calculating characteristics of a set of optimal reactor power off controls. The article show a possibility and feasibility of new sets of optimization tasks for the operation of nuclear power plants under conditions of xenon poisoning in emergency circumstances.

Density fluctuation measurements via reflectometry on DIII-D during L- and H-mode operation

International Nuclear Information System (INIS)

Doyle, E.J.; Lehecka, T.; Luhmann, N.C. Jr.; Peebles, W.A.; Philipona, R.

1990-01-01

The unique ability of reflectometers to provide radial density fluctuation measurements with high spatial resolution (of the order of ≤ centimeters, is ideally suited to the study of the edge plasma modifications associated with H-mode operation. Consequently, attention has been focused on the study of these phenomena since an improved understanding of the physics of H-mode plasmas is essential if a predictive capability for machine performance is to be developed. In addition, DIII-D is ideally suited for such studies since it is a major device noted for its robust H-mode operation and excellent basic plasma profile diagnostic information. The reflectometer system normally used for fluctuation studies is an O-mode, homodyne, system utilizing 7 discrete channels spanning 15-75 GHz, with corresponding critical densities of 2.8x10 18 to 7x10 19 m -3 . The Gunn diode sources in this system are only narrowly tunable in frequency, so the critical densities are essentially fixed. An X-mode system, utilizing a frequency tunable BWO source, has also been used to obtain fluctuation data, and in particular, to 'fill in the gaps' between the discrete O-mode channels. (author) 12 refs., 5 figs

Dual fuel mode operation in diesel engines using renewable fuels: Rubber seed oil and coir-pith producer gas

Energy Technology Data Exchange (ETDEWEB)

Ramadhas, A.S.; Jayaraj, S.; Muraleedharan, C. [Department of Mechanical Engineering, National Institute of Technology Calicut, Calicut-673601 (India)

2008-09-15

Partial combustion of biomass in the gasifier generates producer gas that can be used as supplementary or sole fuel for internal combustion engines. Dual fuel mode operation using coir-pith derived producer gas and rubber seed oil as pilot fuel was analyzed for various producer gas-air flow ratios and at different load conditions. The engine is experimentally optimized with respect to maximum pilot fuel savings in the dual fuel mode operation. The performance and emission characteristics of the dual fuel engine are compared with that of diesel engine at different load conditions. Specific energy consumption in the dual-fuel mode of operation with oil-coir-pith operation is found to be in the higher side at all load conditions. Exhaust emission was found to be higher in the case of dual fuel mode of operation as compared to neat diesel/oil operation. Engine performance characteristics are inferior in fully renewable fueled engine operation but it suitable for stationary engine application, particularly power generation. (author)

AIR ATMOSPHERIC-PRESSURE DISCHARGERS FOR OPERATION IN HIGH-FREQUENCY SWITCHING MODE.

Directory of Open Access Journals (Sweden)

L.S. Yevdoshenko

2013-10-01

Full Text Available Operation of two designs of compact multigap dischargers has been investigated in a high-frequency switching mode. It is experimentally revealed that the rational length of single discharge gaps in the designs is 0.3 mm, and the maximum switching frequency is 27000 discharges per second under long-term stable operation of the dischargers. It is shown that in pulsed corona discharge reactors, the pulse front sharpening results in increasing the operating electric field strength by 1.3 – 1.8 times.

Single mode operation of a TEA CO2 laser

International Nuclear Information System (INIS)

Wada, Kazuhiro; Tunawaki, Yoshiaki; Yamanaka, Masanobu.

1993-01-01

Single mode operation of a TEA CO 2 laser was performed by using an optical system of Fox-Smith type. Laser beam was taken out from the cavity by using a beam splitter, and was reflected by a mirror back to the cavity. By inserting a Fabry-Perot etalon between the splitter and the mirror, beat of laser pulses can be removed completly. (author)

Representing Operational Modes for Situation Awareness

International Nuclear Information System (INIS)

Kirchhübel, Denis; Lind, Morten; Ravn, Ole

2017-01-01

Operating complex plants is an increasingly demanding task for human operators. Diagnosis of and reaction to on-line events requires the interpretation of real time data. Vast amounts of sensor data as well as operational knowledge about the state and design of the plant are necessary to deduct reasonable reactions to abnormal situations. Intelligent computational support tools can make the operator’s task easier, but they require knowledge about the overall system in form of some model. While tools used for fault-tolerant control design based on physical principles and relations are valuable tools for designing robust systems, the models become too complex when considering the interactions on a plant-wide level. The alarm systems meant to support human operators in the diagnosis of the plant-wide situation on the other hand fail regularly in situations where these interactions of systems lead to many related alarms overloading the operator with alarm floods. Functional modelling can provide a middle way to reduce the complexity of plant-wide models by abstracting from physical details to more general functions and behaviours. Based on functional models the propagation of failures through the interconnected systems can be inferred and alarm floods can potentially be reduced to their root-cause. However, the desired behaviour of a complex system changes due to operating procedures that require more than one physical and functional configuration. In this paper a consistent representation of possible configurations is deduced from the analysis of an exemplary start-up procedure by functional models. The proposed interpretation of the modelling concepts simplifies the functional modelling of distinct modes. The analysis further reveals relevant links between the quantitative sensor data and the qualitative perspective of the diagnostics tool based on functional models. This will form the basis for the ongoing development of a novel real-time diagnostics system based

Representing Operational Modes for Situation Awareness

Science.gov (United States)

Kirchhübel, Denis; Lind, Morten; Ravn, Ole

2017-01-01

Operating complex plants is an increasingly demanding task for human operators. Diagnosis of and reaction to on-line events requires the interpretation of real time data. Vast amounts of sensor data as well as operational knowledge about the state and design of the plant are necessary to deduct reasonable reactions to abnormal situations. Intelligent computational support tools can make the operator’s task easier, but they require knowledge about the overall system in form of some model. While tools used for fault-tolerant control design based on physical principles and relations are valuable tools for designing robust systems, the models become too complex when considering the interactions on a plant-wide level. The alarm systems meant to support human operators in the diagnosis of the plant-wide situation on the other hand fail regularly in situations where these interactions of systems lead to many related alarms overloading the operator with alarm floods. Functional modelling can provide a middle way to reduce the complexity of plant-wide models by abstracting from physical details to more general functions and behaviours. Based on functional models the propagation of failures through the interconnected systems can be inferred and alarm floods can potentially be reduced to their root-cause. However, the desired behaviour of a complex system changes due to operating procedures that require more than one physical and functional configuration. In this paper a consistent representation of possible configurations is deduced from the analysis of an exemplary start-up procedure by functional models. The proposed interpretation of the modelling concepts simplifies the functional modelling of distinct modes. The analysis further reveals relevant links between the quantitative sensor data and the qualitative perspective of the diagnostics tool based on functional models. This will form the basis for the ongoing development of a novel real-time diagnostics system based

Impurity deposition on surface probes during different operation modes at EXTRAP T1

International Nuclear Information System (INIS)

Gudowska, I.; Bergsaker, H.; Hellblom, G.

1991-01-01

Surface probes were used in the impurity control program during initial operation of the EXTRAP T1 device. The EXTRAP concept, design and operation characteristics are given elsewhere. The dimensions of the device are R/a=0.5m/0.06m. Four different modes of operation were studied: pure EXTRAP, mixed EXTRAP, RFP and ULQ. Briefly, all four are toroidal plasma discharges, with poloidal magnetic field due to the toroidal plasma current. In the ULQ case, a relatively strong external toroidal magnetic field is applied. In the RFP, and in the mixed mode, an external toroidal field is applied early in the discharge, and the plasma subsequently relaxes into a state with self-generated toroidal field. In the EXTRAP and mixed EXTRAP modes, an additional strong external octupole field is applied, breaking the poloidal symmetry. Throughout the initial period of operation of the device, the plasma performance was largely dominated by impurities, in particular fluorine, which was present due to an accidental contamination of the vessel. Probes have been exposed in wall/liner position, and the objective has been to measure erosion and deposition and try to identify which mechanisms are mainly responsible for impurity production. (author) 5 refs., 2 figs., 1 tab

The revised program for measurements in intense operation mode according to AVV-IMIS

International Nuclear Information System (INIS)

Bieringer, J.; Wirth, E.; Buehling, A.; Mueller-Neumann, M.; Haase, G.; Heinrich, T.; Steinkopff, T.; Wiezorek, C.

2007-01-01

The monitoring program for measurements in intense operation mode has been revised recently by a working group at the Federal Ministry for Environment, Nature Conservation and Reactor Safety (BMU). The major issues of the revision are reported in this contribution. Measurements in intense operation must be appropriate for fast assessment of the radiological situation, for estimating the dose to the population and for decisions on countermeasures to minimize the dose. In order to meet these requirements the structure of the measurement program in intense operation mode was divided into three phases when different exposition paths are relevant: before and during dispersion of radioactive material, immediately after dispersion of radioactive material has ended and a late phase when contamination values have decreased in different environmental media. For each of these phases a special measurement program was defined that is tailored to achieve the above mentioned objectives. Minimum detectable activity concentrations were introduced similar to the measurement program in routine operation mode. They follow the intervention levels in the catalogue of countermeasures and maximum permitted values given by the European Union (EU) for food and animal feed. The minimum detectable activity concentrations were defined such that the detection of 1/10 of the intervention levels for countermeasures is ensured. (orig.)

Design Considerations for CMOS Current Mode Operational Amplifiers and Current Conveyors

DEFF Research Database (Denmark)

Bruun, Erik

implementations of current mode opamps in CMOS technology are described. Also, current conveyor configurations with multiple outputs and flexible feedback connections from outputs to inputs are introduced. The dissertation includes several examples of circuit configurations ranging from simple class A and class......This dissertation is about CMOS current conveyors and current mode operational amplifiers (opamps). They are generic devices for continuous time signal processing in circuits and systems where signals are represented by currents.Substantial advancements are reported in the dissertation, both...... related to circuit implementations and system configurations and to an analysis of the fundamental limitations of the current mode technique.In the field of system configurations and circuit implementations different configurations of high gain current opamps are introduced and some of the first...

Migration behavior of Cu and Zn in landfill with different operation modes

International Nuclear Information System (INIS)

Long Yuyang; Shen Dongsheng; Wang Hongtao; Lu Wenjing

2010-01-01

Cu and Zn were chosen to study the heavy metal migration behavior and mechanism in three simulated landfills with different operation modes, namely conventional landfill (CL), leachate directly recirculated landfill (RL) and leachate pre-treated bioreactor landfill (BL). It showed that Cu and Zn in refuse experienced periodic migration and retention gradually during decomposition, and the variation of Cu(II) and Zn(II) in leachate correspondingly reflected the releasing behavior of Cu and Zn in landfill refuse at different stabilization stages. Except for their accumulated leaching amounts, Cu(II) and Zn(II) concentrations in leachate from landfills with different operation modes had no significant difference. The accumulated leaching amounts of Cu and Zn from CL showed exponential increase, while those of RL and BL showed exponential decay. The operation of bioreactor landfill with leachate recirculation can obviously attenuate the heavy metal leaching than conventional operation. The introduction of methanogenic reactor (MR) in bioreactor landfill can further promote the immobilization of heavy metal in refuse than leachate recirculation directly.

Early detection of power system disturbances as a condition for safe operation of the Dukovany NPP in the 'Island operation mode'

International Nuclear Information System (INIS)

Petruzela, I.

1997-01-01

The ''Frequency Plan'' worked out for the Czech Power System specifies a set of preventive measures along with the set of the frequency ranges. This problem was solved in details for the Dukovany nuclear power plant. The design changes under preparation support a reliable as well as safe operation in the island-operation mode until a full restoration of the whole power system. The design modifications are based on the following three main innovations: An incorporation of the FREA 16 frequency relay into the protection circuits; large modifications in turbine control loops; installation of software routine for the operator to support the island operation mode. The capability of the island operation has been demanded by relevant regulations both for the operating units and for that under construction. The capability can be tested under the transition to houseloads, as well as through the direct simulation of abnormal grid conditions. 1 fig

Evaluating the operational risks of biomedical waste using failure mode and effects analysis.

Science.gov (United States)

Chen, Ying-Chu; Tsai, Pei-Yi

2017-06-01

The potential problems and risks of biomedical waste generation have become increasingly apparent in recent years. This study applied a failure mode and effects analysis to evaluate the operational problems and risks of biomedical waste. The microbiological contamination of biomedical waste seldom receives the attention of researchers. In this study, the biomedical waste lifecycle was divided into seven processes: Production, classification, packaging, sterilisation, weighing, storage, and transportation. Twenty main failure modes were identified in these phases and risks were assessed based on their risk priority numbers. The failure modes in the production phase accounted for the highest proportion of the risk priority number score (27.7%). In the packaging phase, the failure mode 'sharp articles not placed in solid containers' had the highest risk priority number score, mainly owing to its high severity rating. The sterilisation process is the main difference in the treatment of infectious and non-infectious biomedical waste. The failure modes in the sterilisation phase were mainly owing to human factors (mostly related to operators). This study increases the understanding of the potential problems and risks associated with biomedical waste, thereby increasing awareness of how to improve the management of biomedical waste to better protect workers, the public, and the environment.

Operability test report for rotary mode core sampling system number 3

International Nuclear Information System (INIS)

Corbett, J.E.

1996-01-01

This report documents the successful completion of operability testing for the Rotary Mode Core Sampling (RMCS) system number-sign 3. The Report includes the test procedure (WHC-SD-WM-OTP-174), exception resolutions, data sheets, and a test report summary

Operability test procedure for the Rotary Mode Core Sampling System Exhausters 3 and 4

International Nuclear Information System (INIS)

WSaldo, E.J.

1995-01-01

This document provides a procedure for performing operability testing of the Rotary Mode Core Sampling System Exhausters 3 ampersand 4. Upon completion of testing activities an operability testing report will be issued

Single-Phase Microgrid with Seamless Transition Capabilities between Modes of Operation

DEFF Research Database (Denmark)

Micallef, Alexander; Apap, Maurice; Spiteri-Staines, Cyril

2015-01-01

with the secondary control loops that are used to synchronize the microgrid as a single unit to the grid. Simulation results are given that show the seamless transitions between the two modes without any disconnection times for the CC-VSIs and VC-VSIs connected to the microgrid.......Microgrids are an effective way to increase the penetration of DG into the grid. They are capable of operating either in grid-connected or in islanded mode thereby increasing the supply reliability for the end user. This paper focuses on achieving seamless transitions from islanded to grid-connected...

Single mode operation in a pulsed Ti:sapphire laser oscillator with a grazing-incidence four-mirror cavity

CERN Document Server

Ko, D K; Binks, D J; Gloster, L A W; King, T A

1998-01-01

We demonstrate stable single mode operation in a pulsed Ti:sapphire laser oscillator with a novel grazing-incidence four-mirror coupled cavity. This cavity consists of a grating, a gain medium, and four mirrors and, therefore, has a four-arm interferometer configuration. Through the interferometric effect, we could suppress the adjacent modes and obtain stable single mode operation with a bandwidth of < 200 MHz. We also have developed a general analysis of the laser modes and the threshold conditions for configuration and the experimental results agree well with the theoretical predictions.

Comparative Analysis of Battery Behavior with Different Modes of Discharge for Optimal Capacity Sizing and BMS Operation

Directory of Open Access Journals (Sweden)

Mazhar Abbas

2016-10-01

Full Text Available Battery-operated systems are always concerned about the proper management and sizing of a battery. A Traditional Battery Management System (BMS only includes battery-aware task scheduling based on the discharge characteristics of a whole battery pack and do not take into account the mode of the load being served by the battery. On the other hand, an efficient and intelligent BMS should monitor the battery at a cell level and track the load with significant consideration of the load mode. Depending upon the load modes, the common modes of discharge (MOD of a battery identified so far are Constant Power Mode (CPM, Constant Current Mode (CCM and Constant Impedance Mode (CIM. This paper comparatively analyzes the discharging behavior of batteries at an individual cell level for different load modes. The difference in discharging behavior from mode to mode represents the study of the mode-dependent behavior of the battery before its deployment in some application. Based on simulation results, optimal capacity sizing and BMS operation of battery for an assumed situation in a remote microgrid has been proposed.

The experimental studies of operating modes of a diesel-generator set at variable speed

Science.gov (United States)

Obukhov, S. G.; Plotnikov, I. A.; Surkov, M. A.; Sumarokova, L. P.

2017-02-01

A diesel generator set working at variable speed to save fuel is studied. The results of experimental studies of the operating modes of an autonomous diesel generator set are presented. Areas for regulating operating modes are determined. It is demonstrated that the transfer of the diesel generator set to variable speed of the diesel engine makes it possible to improve the energy efficiency of the autonomous generator source, as well as the environmental and ergonomic performance of the equipment as compared with general industrial analogues.

Reactor-relevant quiescent H-mode operation using torque from non-axisymmetric, non-resonant magnetic fields

International Nuclear Information System (INIS)

Burrell, K. H.; Garofalo, A. M; Osborne, T. H.; Schaffer, M. J.; Snyder, P. B.; Solomon, W. M.; Park, J.-K.; Fenstermacher, M. E.

2012-01-01

Results from recent experiments demonstrate that quiescent H-mode (QH-mode) sustained by magnetic torque from non-axisymmetric magnetic fields is a promising operating mode for future burning plasmas. Using magnetic torque from n=3 fields to replace counter-I p torque from neutral beam injection (NBI), we have achieved long duration, counter-rotating QH-mode operation with NBI torque ranging from counter-I p to up to co-I p values of 1-1.3 Nm. This co-I p torque is 3 to 4 times the scaled torque that ITER will have. These experiments utilized an ITER-relevant lower single-null plasma shape and were done with ITER-relevant values of ν ped * and β N ped . These discharges exhibited confinement quality H 98y2 =1.3, in the range required for ITER. In preliminary experiments using n=3 fields only from a coil outside the toroidal coil, QH-mode plasmas with low q 95 =3.4 have reached fusion gain values of G=β N H 89 /q 95 2 =0.4, which is the desired value for ITER. Shots with the same coil configuration also operated with net zero NBI torque. The limits on G and co-I p torque have not yet been established for this coil configuration. QH-mode work to has made significant contact with theory. The importance of edge rotational shear is consistent with peeling-ballooning mode theory. Qualitative and quantitative agreements with the predicted neoclassical toroidal viscosity torque is seen.

Task Analytic Models to Guide Analysis and Design: Use of the Operator Function Model to Represent Pilot-Autoflight System Mode Problems

Science.gov (United States)

Degani, Asaf; Mitchell, Christine M.; Chappell, Alan R.; Shafto, Mike (Technical Monitor)

1995-01-01

Task-analytic models structure essential information about operator interaction with complex systems, in this case pilot interaction with the autoflight system. Such models serve two purposes: (1) they allow researchers and practitioners to understand pilots' actions; and (2) they provide a compact, computational representation needed to design 'intelligent' aids, e.g., displays, assistants, and training systems. This paper demonstrates the use of the operator function model to trace the process of mode engagements while a pilot is controlling an aircraft via the, autoflight system. The operator function model is a normative and nondeterministic model of how a well-trained, well-motivated operator manages multiple concurrent activities for effective real-time control. For each function, the model links the pilot's actions with the required information. Using the operator function model, this paper describes several mode engagement scenarios. These scenarios were observed and documented during a field study that focused on mode engagements and mode transitions during normal line operations. Data including time, ATC clearances, altitude, system states, and active modes and sub-modes, engagement of modes, were recorded during sixty-six flights. Using these data, seven prototypical mode engagement scenarios were extracted. One scenario details the decision of the crew to disengage a fully automatic mode in favor of a semi-automatic mode, and the consequences of this action. Another describes a mode error involving updating aircraft speed following the engagement of a speed submode. Other scenarios detail mode confusion at various phases of the flight. This analysis uses the operator function model to identify three aspects of mode engagement: (1) the progress of pilot-aircraft-autoflight system interaction; (2) control/display information required to perform mode management activities; and (3) the potential cause(s) of mode confusion. The goal of this paper is twofold

Active pixel image sensor with a winner-take-all mode of operation

Science.gov (United States)

Yadid-Pecht, Orly (Inventor); Fossum, Eric R. (Inventor); Mead, Carver (Inventor)

2003-01-01

An integrated CMOS semiconductor imaging device having two modes of operation that can be performed simultaneously to produce an output image and provide information of a brightest or darkest pixel in the image.

Low-bending loss and single-mode operation in few-mode optical fiber

Science.gov (United States)

Yin, Ping; Wang, Hua; Chen, Ming-Yang; Wei, Jin; Cai, Zhi-Min; Li, Lu-Ming; Yang, Ji-Hai; Zhu, Yuan-Feng

2016-10-01

The technique of eliminating the higher-order modes in a few-mode optical fiber is proposed. The fiber is designed with a group of defect modes in the cladding. The higher-order modes in the fiber can be eliminated by bending the fiber to induce strong coupling between the defect modes and the higher-order modes. Numerical simulation shows the bending losses of the LP01 mode are lower than 1.5×10-4 dB/turn for the wavelength shorter than 1.625 μm. The proposed fiber can be bent multiple turns at small bending radius which are preferable for FTTH related applications.

Performance comparison for modes of operation and suppression cases of the clover detector

International Nuclear Information System (INIS)

Kshetri, R

2014-01-01

Peak-to-total ratios have been extracted for a segmented clover detector for various modes of operation and suppression cases. Based on absorption and scattering of gamma-rays, a formalism has been presented for quantifying the advantages of using addback mode and active suppression. Further investigations have been performed to find if the reduction of background counts is caused more by active suppression or by addback process

Tunable single and dual mode operation of an external cavity quantum-dot injection laser

International Nuclear Information System (INIS)

Biebersdorf, A; Lingk, C; De Giorgi, M; Feldmann, J; Sacher, J; Arzberger, M; Ulbrich, C; Boehm, G; Amann, M-C; Abstreiter, G

2003-01-01

We investigate quantum-dot (QD) lasers in an external cavity using Littrow and Littman configurations. Here, we report on a continuously tunable QD laser with a broad tuning range from 1047 to 1130 nm with high stability and efficient side mode suppression. The full-width at half-maximum of the laser line is 0.85 nm determined mainly by the quality of the external grating. This laser can be operated in a dual-mode modus, where the mode-spacing can be tuned continuously between 1.1 and 34 nm. Simultaneous emission of the two laser modes is shown by sum frequency generation experiments

Two-coordinate mini drift chamber operating in a self-quenching streamer mode

International Nuclear Information System (INIS)

Chernenko, S.P.; Smykov, L.P.; Zanevskij, Yu.V.

1993-01-01

Two-coordinate mini drift chambers operating in a self-quenching streamer mode have been developed. The tests have demonstrated these chambers to possess an extended counting plateau, a high operating stability and a high uniformity of efficiency over detecting area. The space resolution along anode wires is not worse than 250μm; the expected space resolution for the second coordinate is about 100 μm

Self-mode-locking operation of a diode-end-pumped Tm:YAP laser with watt-level output power

Science.gov (United States)

Zhang, Su; Zhang, Xinlu; Huang, Jinjer; Wang, Tianhan; Dai, Junfeng; Dong, Guangzong

2018-03-01

We report on a high power continuous wave (CW) self-mode-locked Tm:YAP laser pumped by a 792 nm laser diode. Without any additional mode-locking elements in the cavity, stable and self-starting mode-locking operation has been realized. The threshold pump power of the CW self-mode-locked Tm:YAP laser is only 5.4 W. The maximum average output power is as high as 1.65 W at the pump power of 12 W, with the repetition frequency of 468 MHz and the center wavelength of 1943 nm. To the best of our knowledge, this is the first CW self-mode-locked Tm:YAP laser. The experiment results show that the Tm:YAP crystal is a promising gain medium for realizing the high power self-mode-locking operation at 2 µm.

Guidance system operations plan for manned CM earth orbital missions using program SKYLARK 1. Section 4: Operational modes

Science.gov (United States)

Dunbar, J. C.

1972-01-01

The operational modes for the guidance system operations plan for Program SKYLARK 1 are presented. The procedures control the guidance and navigation system interfaces with the flight crew and the mission control center. The guidance operational concept is designed to comprise a set of manually initiated programs and functions which may be arranged by the flight crew to implement a large class of flight plans. This concept will permit both a late flight plan definition and a capability for real time flight plan changes.

Analysis and Improvement of Control Algorithm for Operation Mode Transition due to Input Channel Trouble in Control Systems

International Nuclear Information System (INIS)

Ahn, Myunghoon; Kim, Woogoon; Yim, Hyeongsoon

2016-01-01

The PI (Proportional plus Integral) controller, which is the essential functional block in control systems, can automatically perform the stable control of an important plant process while reducing the steady state error and improving the transient response. However, if the received input PV (Process Variable) is not normal due to input channel trouble, it will be difficult to control the system automatically. For this reason, many control systems are implemented to change the operation mode from automatic to manual mode in the PI controller when the failed input PV is detected. If the PI controller is in automatic mode for all the time, the control signal varies as the change of the input PV is continuously reflected in the control algorithm. In the other cases, since the controller changes into the manual mode at t=0, the control signal is fixed at the last PI controller output and thus the feedback control is not performed anymore until the operator takes an action such as the operation mode change. As a result of analysis and simulations for the controller’s operation modes in all the cases of input channel trouble, we discovered that it is more appropriate to maintain the automatic mode despite the bad quality in the PV. Therefore, we improved the control system algorithm reflecting the analysis results for the operator’s convenience and the stability of a control system

Analysis and Improvement of Control Algorithm for Operation Mode Transition due to Input Channel Trouble in Control Systems

Energy Technology Data Exchange (ETDEWEB)

Ahn, Myunghoon; Kim, Woogoon; Yim, Hyeongsoon [KEPCO Engineering and Construction Co., Deajeon (Korea, Republic of)

2016-10-15

The PI (Proportional plus Integral) controller, which is the essential functional block in control systems, can automatically perform the stable control of an important plant process while reducing the steady state error and improving the transient response. However, if the received input PV (Process Variable) is not normal due to input channel trouble, it will be difficult to control the system automatically. For this reason, many control systems are implemented to change the operation mode from automatic to manual mode in the PI controller when the failed input PV is detected. If the PI controller is in automatic mode for all the time, the control signal varies as the change of the input PV is continuously reflected in the control algorithm. In the other cases, since the controller changes into the manual mode at t=0, the control signal is fixed at the last PI controller output and thus the feedback control is not performed anymore until the operator takes an action such as the operation mode change. As a result of analysis and simulations for the controller’s operation modes in all the cases of input channel trouble, we discovered that it is more appropriate to maintain the automatic mode despite the bad quality in the PV. Therefore, we improved the control system algorithm reflecting the analysis results for the operator’s convenience and the stability of a control system.

Research on operation mode of abrasive grain during grinding

Science.gov (United States)

Ivanova, T. N.; Dement’ev, V. B.; Nikitina, O. V.

2018-03-01

The processing of materials by cutting with an abrasive tool is carried out by means of thousands of grains bonded together as a single whole. The quality of the abrasive tool is defined by cutting properties of abrasive grains and depends on features of spreading the temperature field in time and in the abrasive grain volume. Grains are exposed to heating and cooling during work. It leads to undesired effects such as a decrease of durability of grain retention in the binder, hardness, intensification of diffusion and oxidation processes between the binder and the grain, the occurrence of considerable temperature stresses in the grain itself. The obtained equation which allows calculation of temperature field of grain for one rotation of grinding wheel shows that the temperature of the wheel depends on grinding modes and thermophysical properties of abrasive material. Thus, as the time of contact of grain with processed material increases, the temperature in the cutting area rises. As thermophysical properties increase, the temperature in cutting area decreases. Thermal working conditions are determined to be different from each other depending on contact time of the grain and the material. For example, in case of creep-feed grinding, the peak value of temperature is higher than during multistep grinding; the depth of expansion is greater. While the speed of the thermal process in creep-feed grinding is 2-3 times lower than in multistep grinding, the gradient reduces 3-4 times. The analysis of machining methods shows that creep-feed grinding ensures greater depth of grain heating, a smaller heating rate and a reduced velocity gradient. It causes a decrease of probable allotropic modifications and prevents from occurring of heat strokes - cracking of grains due to high temperature falls. Consequently, it is necessary to employ creep-feed grinding to increase the efficiency of abrasive tool employing. Three operation modes of grinding wheel including blunting, full

High beta tokamak operation in DIII-D limited at low density/collisionality by resistive tearing modes

International Nuclear Information System (INIS)

La Haye, R.J.; Lao, L.L.; Strait, E.J.; Taylor, T.S.

1997-01-01

The maximum operational high beta in single-null divertor (SND) long pulse tokamak discharges in the DIII-D tokamak with a cross-sectional shape similar to the proposed International Thermonuclear Experimental Reactor (ITER) device is found to be limited by the onset of resistive instabilities that have the characteristics of neoclassically destabilized tearing modes. There is a soft limit due to the onset of an m/n=3/2 rotating tearing mode that saturates at low amplitude and a hard limit at slightly higher beta due to the onset of an m/n=2/1 rotating tearing mode that grows, slows down and locks. By operating at higher density and thus collisionality, the practical beta limit due to resistive tearing modes approaches the ideal magnetohydrodynamic (MHD) limit. (author). 15 refs, 4 figs

Two-Dimensional Simulation of Mass Transfer in Unitized Regenerative Fuel Cells under Operation Mode Switching

Directory of Open Access Journals (Sweden)

Lulu Wang

2016-01-01

Full Text Available A two-dimensional, single-phase, isothermal, multicomponent, transient model is built to investigate the transport phenomena in unitized regenerative fuel cells (URFCs under the condition of switching from the fuel cell (FC mode to the water electrolysis (WE mode. The model is coupled with an electrochemical reaction. The proton exchange membrane (PEM is selected as the solid electrolyte of the URFC. The work is motivated by the need to elucidate the complex mass transfer and electrochemical process under operation mode switching in order to improve the performance of PEM URFC. A set of governing equations, including conservation of mass, momentum, species, and charge, are considered. These equations are solved by the finite element method. The simulation results indicate the distributions of hydrogen, oxygen, water mass fraction, and electrolyte potential response to the transient phenomena via saltation under operation mode switching. The hydrogen mass fraction gradients are smaller than the oxygen mass fraction gradients. The average mass fractions of the reactants (oxygen and hydrogen and product (water exhibit evident differences between each layer in the steady state of the FC mode. By contrast, the average mass fractions of the reactant (water and products (oxygen and hydrogen exhibit only slight differences between each layer in the steady state of the WE mode. Under either the FC mode or the WE mode, the duration of the transient state is only approximately 0.2 s.

A dual-mode operation overmoded coaxial millimeter-wave generator with high power capacity and pure transverse electric and magnetic mode output

Science.gov (United States)

Bai, Zhen; Zhang, Jun; Zhong, Huihuang

2016-04-01

An overmoded coaxial millimeter-wave generator with high power capacity and pure transverse electric and magnetic (TEM) mode output is designed and presented, by using a kind of coaxial slow wave structure (SWS) with large transversal dimension and small distance between inner and outer conductors. The generator works in dual-mode operation mechanism. The electron beam synchronously interacts with 7π/8 mode of quasi-TEM, at the meanwhile exchanges energy with 3π/8 mode of TM01. The existence of TM01 mode, which is traveling wave, not only increases the beam-wave interaction efficiency but also improves the extraction efficiency. The large transversal dimension of coaxial SWS makes its power capacity higher than that of other reported millimeter-wave devices and the small distance between inner and outer conductors allows only two azimuthally symmetric modes to coexist. The converter after the SWS guarantees the mode purity of output power. Particle-in-cell simulation shows that when the diode voltage is 400 kV and beam current is 3.8 kA, the generation of microwave at 32.26 GHz with an output power of 611 MW and a conversion efficiency of 40% is obtained. The power percentage carried by TEM mode reaches 99.7% in the output power.

Operating modes and practical power flow analysis of bidirectional isolated power interface for distributed power systems

International Nuclear Information System (INIS)

Wen, Huiqing; Su, Bin

2016-01-01

Highlights: • Four operating modes of Dual-Phase-Shift control for Dual Active Bridge converter are presented. • Effects of “minor parameters” such as the deadtime and power device voltage drops are analyzed. • Accurate power flow models with Dual-Phase-Shift control are developed and verified with experimental results. • Optimal operating mode is determined with respect to the efficiency improvement. • Measured efficiency of the Dual Active Bridge converter is improved up to 14%. - Abstract: Due to the intermittent nature of the renewable energy sources including photovoltaic and wind energy, the energy storage systems are essential to stabilize dc bus voltage. Considering the discharge depth of super-capacitors and energy-storage batteries, the bidirectional isolated power interface will operate for a wide range of voltage and power. This study focuses on in-depth analysis of the dual-active-bridge dc–dc converter that is controlled by the dual-phase-shift scheme to improve the conversion efficiency in distributed power system. The power flow of each operating mode with dual-phase-shift control is characterized based on a detailed analysis of the effects of “minor parameters”, including the deadtime and power device voltage drops. The complete output power plane of the dual-active-bridge converter with dual-phase-shift control is obtained and compared with experimental results. The optimal operating mode is determined according to the practical output power range and the power flow characteristics. Experimental evaluation shows the effectiveness of the proposed power flow model with dual-phase-shift control and significant efficiency improvement using the optimal mode of dual-phase-shift compared with the conventional phase shift control.

Features of Synchronous Electronically Commutated Motors in Servomotor Operation Modes

Directory of Open Access Journals (Sweden)

Dirba J.

2017-04-01

Full Text Available The authors consider the features and operation specifics of the synchronous permanent magnet motors and the synchronous reluctance motors with electronic commutation in servomotor operation modes. Calculation results show that mechanical and control characteristics of studied motors are close to a linear shape. The studied motor control is proposed to implement similar to phase control of induction servomotor; it means that angle θ (angle between vectors of the supply voltage and non-load electromotive force or angle ε (angle between rotor direct axis and armature magnetomotive force axis is changed. The analysis results show that synchronous electronically commutated motors could be used as servomotors.

Features of Synchronous Electronically Commutated Motors in Servomotor Operation Modes

Science.gov (United States)

Dirba, J.; Lavrinovicha, L.; Dobriyan, R.

2017-04-01

The authors consider the features and operation specifics of the synchronous permanent magnet motors and the synchronous reluctance motors with electronic commutation in servomotor operation modes. Calculation results show that mechanical and control characteristics of studied motors are close to a linear shape. The studied motor control is proposed to implement similar to phase control of induction servomotor; it means that angle θ (angle between vectors of the supply voltage and non-load electromotive force) or angle ɛ (angle between rotor direct axis and armature magnetomotive force axis) is changed. The analysis results show that synchronous electronically commutated motors could be used as servomotors.

Harmonic voltage excess problem test and analysis in UHV and EHV grid particular operation mode

Science.gov (United States)

Lv, Zhenhua; Shi, Mingming; Fei, Juntao

2018-02-01

The test and analysis of the power quality of some 1000kV UHV transmission lines and 500kV EHV transmission lines is carried out. It is found that there is harmonic voltage excess problems when the power supply of the UHV and EHV voltage line is single-ended or single-loop, the problem basically disappeared after the operation mode change, different operating conditions, the harmonic current has not been greatly affected, indicating that the harmonic voltage changes mainly caused by the system harmonic impedance. With the analysis of MATLAB Simulink system model, it can be seen that there are specific harmonic voltage excess in the system under the specific operating mode, which results in serious distortion of the specific harmonic voltage. Since such phenomena are found in 500kV and 1000kV systems, it is suggested that the test evaluation work should be done under the typical mode of operation in 500kV, 1000kV Planning and construction process to prevent the occurrence of serious distortion and the regional harmonic current monitoring and suppression work should be done.

Communication: Effects of thermionic-gun parameters on operating modes in ultrafast electron microscopy

Directory of Open Access Journals (Sweden)

Erik Kieft

2015-09-01

Full Text Available Ultrafast electron microscopes with thermionic guns and LaB6 sources can be operated in both the nanosecond, single-shot and femtosecond, single-electron modes. This has been demonstrated with conventional Wehnelt electrodes and absent any applied bias. Here, by conducting simulations using the General Particle Tracer code, we define the electron-gun parameter space within which various modes may be optimized. The properties of interest include electron collection efficiency, temporal and energy spreads, and effects of laser-pulse duration incident on the LaB6 source. We find that collection efficiencies can reach 100% for all modes, despite there being no bias applied to the electrode.

A Frequency-Weighted Energy Operator and complementary ensemble empirical mode decomposition for bearing fault detection

Science.gov (United States)

Imaouchen, Yacine; Kedadouche, Mourad; Alkama, Rezak; Thomas, Marc

2017-01-01

Signal processing techniques for non-stationary and noisy signals have recently attracted considerable attentions. Among them, the empirical mode decomposition (EMD) which is an adaptive and efficient method for decomposing signals from high to low frequencies into intrinsic mode functions (IMFs). Ensemble EMD (EEMD) is proposed to overcome the mode mixing problem of the EMD. In the present paper, the Complementary EEMD (CEEMD) is used for bearing fault detection. As a noise-improved method, the CEEMD not only overcomes the mode mixing, but also eliminates the residual of added white noise persisting into the IMFs and enhance the calculation efficiency of the EEMD method. Afterward, a selection method is developed to choose relevant IMFs containing information about defects. Subsequently, a signal is reconstructed from the sum of relevant IMFs and a Frequency-Weighted Energy Operator is tailored to extract both the amplitude and frequency modulations from the selected IMFs. This operator outperforms the conventional energy operator and the enveloping methods, especially in the presence of strong noise and multiple vibration interferences. Furthermore, simulation and experimental results showed that the proposed method improves performances for detecting the bearing faults. The method has also high computational efficiency and is able to detect the fault at an early stage of degradation.

Passively mode-locked Nd:YVO4 laser operating at 1073 nm and 1085 nm

Science.gov (United States)

Waritanant, Tanant; Major, Arkady

2018-02-01

A passively mode-locked Nd:YVO4 laser operating at 1073 nm and 1085 nm was demonstrated with an intracavity birefringent filter as the wavelength selecting element. The average output powers achieved were 2.17 W and 2.18 W with optical-to-optical efficiency of 19.6% and 19.7%, respectively. The slope efficiencies were more than 31% at both output wavelengths. The pulse durations at the highest average output power were 10.3 ps and 8.4 ps, respectively. We believe that this is the first report of mode locking of a Nd:YVO4 laser operating at 1073 nm or 1085 nm lines.

Study of the zero modes of the Faddeev–Popov operator in the maximal Abelian gauge

International Nuclear Information System (INIS)

Capri, M.A.L.; Guimaraes, M.S.; Lemes, V.E.R.; Sorella, S.P.; Tedesco, D.G.

2014-01-01

A study of the zero modes of the Faddeev–Popov operator in the maximal Abelian gauge is presented in the case of the gauge group SU(2) and for different Euclidean space–time dimensions. Explicit examples of classes of normalizable zero modes and corresponding gauge field configurations are constructed by taking into account two boundary conditions, namely: (i) the finite Euclidean Yang–Mills action, (ii) the finite Hilbert norm. -- Highlights: •We study the zero modes of the Faddeev–Popov operator in the maximal Abelian gauge. •For d=2 we obtain solutions with finite action but not finite Hilbert norm. •For d=3,4 we obtain solutions with finite action and finite Hilbert norm. •These results can be compared with those previously obtained in the Landau gauge

Edge localized mode physics and operational aspects in tokamaks

Energy Technology Data Exchange (ETDEWEB)

Becoulet, M [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Huysmans, G [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Sarazin, Y [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Garbet, X [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Ghendrih, Ph [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Rimini, F [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Joffrin, E [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Litaudon, X [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Monier-Garbet, P [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Ane, J-M [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Thomas, P [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Grosman, A [Association Euratom-CEA, CEA Cadarache, F-13108 St Paul-lez-Durance (France); Parail, V [Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom); Wilson, H [Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom); Lomas, P [Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom); Vries, P de[Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom); Zastrow, K-D [Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom); Matthews, G F [Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom); Lonnroth, J [Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom); Gerasimov, S [Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA (United Kingdom)] [and others

2003-12-01

Recent progress in experimental and theoretical studies of edge localized mode (ELM) physics is reviewed for the reactor relevant plasma regimes, namely the high confinement regimes, that is, H-modes and advanced scenarios. Theoretical approaches to ELM physics, from a linear ideal magnetohydrodynamic (MHD) stability analysis to non-linear transport models with ELMs are discussed with respect to experimental observations, in particular the fast collapse of pedestal pressure profiles, magnetic measurements and scrape-off layer transport during ELMs. High confinement regimes with different types of ELMs are addressed in this paper in the context of development of operational scenarios for ITER. The key parameters that have been identified at present to reduce the energy losses in Type I ELMs are operation at high density, high edge magnetic shear and high triangularity. However, according to the present experimental scaling for the energy losses in Type I ELMs, the extrapolation of such regimes for ITER leads to unacceptably large heat loads on the divertor target plates exceeding the material limits. High confinement H-mode scenarios at high triangularity and high density with small ELMs (Type II), mixed regimes (Type II and Type I) and combined advanced regimes at high beta{sub p} are discussed for present-day tokamaks. The optimum combination of high confinement and small MHD activity at the edge in Type II ELM scenarios is of interest to ITER. However, to date, these regimes have been achieved in a rather narrow operational window and far from ITER parameters in terms of collisionality, edge safety factor and beta{sub p}. The compatibility of the alternative internal transport barrier (ITB) scenario with edge pedestal formation and ELMs is also addressed. Edge physics issues related to the possible combination of small benign ELMs (Type III, Type II ELMs, quiescent double barrier) and high performance ITBs are discussed for present-day experiments (JET, JT-60U

Edge localized mode physics and operational aspects in tokamaks

International Nuclear Information System (INIS)

Becoulet, M; Huysmans, G; Sarazin, Y; Garbet, X; Ghendrih, Ph; Rimini, F; Joffrin, E; Litaudon, X; Monier-Garbet, P; Ane, J-M; Thomas, P; Grosman, A; Parail, V; Wilson, H; Lomas, P; Vries, P de; Zastrow, K-D; Matthews, G F; Lonnroth, J; Gerasimov, S; Sharapov, S; Gryaznevich, M; Counsell, G; Kirk, A; Valovic, M; Buttery, R; Loarte, A; Saibene, G; Sartori, R; Leonard, A; Snyder, P; Lao, L L; Gohil, P; Evans, T E; Moyer, R A; Kamada, Y; Chankin, A; Oyama, N; Hatae, T; Asakura, N; Tudisco, O; Giovannozzi, E; Crisanti, F; Perez, C P; Koslowski, H R; Eich, T; Sips, A; Horton, L; Hermann, A; Lang, P; Stober, J; Suttrop, W; Beyer, P; Saarelma, S

2003-01-01

Recent progress in experimental and theoretical studies of edge localized mode (ELM) physics is reviewed for the reactor relevant plasma regimes, namely the high confinement regimes, that is, H-modes and advanced scenarios. Theoretical approaches to ELM physics, from a linear ideal magnetohydrodynamic (MHD) stability analysis to non-linear transport models with ELMs are discussed with respect to experimental observations, in particular the fast collapse of pedestal pressure profiles, magnetic measurements and scrape-off layer transport during ELMs. High confinement regimes with different types of ELMs are addressed in this paper in the context of development of operational scenarios for ITER. The key parameters that have been identified at present to reduce the energy losses in Type I ELMs are operation at high density, high edge magnetic shear and high triangularity. However, according to the present experimental scaling for the energy losses in Type I ELMs, the extrapolation of such regimes for ITER leads to unacceptably large heat loads on the divertor target plates exceeding the material limits. High confinement H-mode scenarios at high triangularity and high density with small ELMs (Type II), mixed regimes (Type II and Type I) and combined advanced regimes at high beta p are discussed for present-day tokamaks. The optimum combination of high confinement and small MHD activity at the edge in Type II ELM scenarios is of interest to ITER. However, to date, these regimes have been achieved in a rather narrow operational window and far from ITER parameters in terms of collisionality, edge safety factor and beta p . The compatibility of the alternative internal transport barrier (ITB) scenario with edge pedestal formation and ELMs is also addressed. Edge physics issues related to the possible combination of small benign ELMs (Type III, Type II ELMs, quiescent double barrier) and high performance ITBs are discussed for present-day experiments (JET, JT-60U, DIII-D) in

A dual-mode operation overmoded coaxial millimeter-wave generator with high power capacity and pure transverse electric and magnetic mode output

Energy Technology Data Exchange (ETDEWEB)

Bai, Zhen; Zhang, Jun, E-mail: zhangjun@nudt.edu.cn; Zhong, Huihuang [College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

2016-04-15

An overmoded coaxial millimeter-wave generator with high power capacity and pure transverse electric and magnetic (TEM) mode output is designed and presented, by using a kind of coaxial slow wave structure (SWS) with large transversal dimension and small distance between inner and outer conductors. The generator works in dual-mode operation mechanism. The electron beam synchronously interacts with 7π/8 mode of quasi-TEM, at the meanwhile exchanges energy with 3π/8 mode of TM{sub 01}. The existence of TM{sub 01} mode, which is traveling wave, not only increases the beam-wave interaction efficiency but also improves the extraction efficiency. The large transversal dimension of coaxial SWS makes its power capacity higher than that of other reported millimeter-wave devices and the small distance between inner and outer conductors allows only two azimuthally symmetric modes to coexist. The converter after the SWS guarantees the mode purity of output power. Particle-in-cell simulation shows that when the diode voltage is 400 kV and beam current is 3.8 kA, the generation of microwave at 32.26 GHz with an output power of 611 MW and a conversion efficiency of 40% is obtained. The power percentage carried by TEM mode reaches 99.7% in the output power.

Modes of mechanical ventilation for the operating room.

Science.gov (United States)

Ball, Lorenzo; Dameri, Maddalena; Pelosi, Paolo

2015-09-01

Most patients undergoing surgical procedures need to be mechanically ventilated, because of the impact of several drugs administered at induction and during maintenance of general anaesthesia on respiratory function. Optimization of intraoperative mechanical ventilation can reduce the incidence of post-operative pulmonary complications and improve the patient's outcome. Preoxygenation at induction of general anaesthesia prolongs the time window for safe intubation, reducing the risk of hypoxia and overweighs the potential risk of reabsorption atelectasis. Non-invasive positive pressure ventilation delivered through different interfaces should be considered at the induction of anaesthesia morbidly obese patients. Anaesthesia ventilators are becoming increasingly sophisticated, integrating many functions that were once exclusive to intensive care. Modern anaesthesia machines provide high performances in delivering the desired volumes and pressures accurately and precisely, including assisted ventilation modes. Therefore, the physicians should be familiar with the potential and pitfalls of the most commonly used intraoperative ventilation modes: volume-controlled, pressure-controlled, dual-controlled and assisted ventilation. Although there is no clear evidence to support the advantage of any one of these ventilation modes over the others, protective mechanical ventilation with low tidal volume and low levels of positive end-expiratory pressure (PEEP) should be considered in patients undergoing surgery. The target tidal volume should be calculated based on the predicted or ideal body weight rather than on the actual body weight. To optimize ventilation monitoring, anaesthesia machines should include end-inspiratory and end-expiratory pause as well as flow-volume loop curves. The routine administration of high PEEP levels should be avoided, as this may lead to haemodynamic impairment and fluid overload. Higher PEEP might be considered during surgery longer than 3 h

Harmonics Suppression for Single-Phase Grid-Connected Photovoltaic Systems in Different Operation Modes

DEFF Research Database (Denmark)

Yang, Yongheng; Zhou, Keliang; Blaabjerg, Frede

2013-01-01

-connected PV inverters may be severely affected in different operation modes. In this paper, a detailed analysis is conducted to reveal the relationship between the harmonics level with the power factor and the current level in the PV systems. A current control solution which employs an Internal Model...... Principle (IMP) is proposed to suppress the harmonic currents injected into the grid. Experiments are carried out to verify the analysis and the performance of the proposed control method. It is demonstrated that the proposed method presents an effective solution to harmonics suppression for single......-phase grid-connected PV systems in different operation modes. Especially, it can remove higher order harmonics effectively leading to a better power quality compared to the Proportional plus Multi-Resonant Controller, and it has less computational burden....

Development of a numerical tool to study the mixing phenomenon occurring during mode one operation of a multi-mode ejector-augmented pulsed detonation rocket engine

Science.gov (United States)

Dawson, Joshua

A novel multi-mode implementation of a pulsed detonation engine, put forth by Wilson et al., consists of four modes; each specifically designed to capitalize on flow features unique to the various flow regimes. This design enables the propulsion system to generate thrust through the entire flow regime. The Multi-Mode Ejector-Augmented Pulsed Detonation Rocket Engine operates in mode one during take-off conditions through the acceleration to supersonic speeds. Once the mixing chamber internal flow exceeds supersonic speed, the propulsion system transitions to mode two. While operating in mode two, supersonic air is compressed in the mixing chamber by an upstream propagating detonation wave and then exhausted through the convergent-divergent nozzle. Once the velocity of the air flow within the mixing chamber exceeds the Chapman-Jouguet Mach number, the upstream propagating detonation wave no longer has sufficient energy to propagate upstream and consequently the propulsive system shifts to mode three. As a result of the inability of the detonation wave to propagate upstream, a steady oblique shock system is established just upstream of the convergent-divergent nozzle to initiate combustion. And finally, the propulsion system progresses on to mode four operation, consisting purely of a pulsed detonation rocket for high Mach number flight and use in the upper atmosphere as is needed for orbital insertion. Modes three and four appear to be a fairly significant challenge to implement, while the challenge of implementing modes one and two may prove to be a more practical goal in the near future. A vast number of potential applications exist for a propulsion system that would utilize modes one and two, namely a high Mach number hypersonic cruise vehicle. There is particular interest in the dynamics of mode one operation, which is the subject of this research paper. Several advantages can be obtained by use of this technology. Geometrically the propulsion system is fairly

Experimental study and performance analysis of a thermoelectric cooling and heating system driven by a photovoltaic/thermal system in summer and winter operation modes

International Nuclear Information System (INIS)

He, Wei; Zhou, JinZhi; Chen, Chi; Ji, Jie

2014-01-01

Highlights: • Thermoelectric heating system driven by heat pipe PV/T system was built and test. • Theoretical analysis has been done and simulation results have been validated by experiments. • The energetic efficiency and exergetic efficiency in summer and winter operation mode was analyzed and compared. - Abstract: This paper presents theoretical and experimental investigations of the winter operation mode of a thermoelectric cooling and heating system driven by a heat pipe photovoltaic/thermal (PV/T) panel. And the energy and exergy analysis of this system in summer and winter operation modes are also done. The winter operation mode of this system is tested in an experimental room which temperature is controlled at 18 °C. The results indicate the average coefficient of performance (COP) of thermoelectric module of this system can be about 1.7, the electrical efficiency of the PV/T panel can reach 16.7%, and the thermal efficiency of this system can reach 23.5%. The energy and exergy analysis show the energetic efficiency of the system in summer operation mode is higher than that of it in winter operation mode, but the exergetic efficiency in summer operation mode is lower than that in winter operation mode, on the contrary

Multiple-bunch-length operating mode design for a storage ring using hybrid low alpha and harmonic cavity method

Energy Technology Data Exchange (ETDEWEB)

Gao, Weiwei, E-mail: gaomqr@mail.ustc.edu.cn [College of Mathematics and Physics, Fujian University of Technology, Fuzhou 350118 (China); Wang, Lin; Li, Heting [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029 (China)

2017-03-11

In this paper we design a simultaneous three bunch length operating mode at the HLS-II (Hefei Light Source II) storage ring by installing two harmonic cavities and minimizing the momentum compaction factor. The short bunches (2.6 mm) presented in this work will meet the requirement of coherent millimeter-wave and sub-THz radiation experiments, while the long bunches (20 mm) will efficiently increase the total beam current. Therefore, this multiple-bunch-length operating mode allows present synchrotron users and coherent millimeter-wave users (or sub THz users) to carry out their experiments simultaneously. Since the relatively low energy characteristic of HLS-II we achieve the multiple-bunch-length operating mode without multicell superconducting RF cavities, which is technically feasible.

Hybrid Systems of Distributed Generation with Renewable Sources: Modeling and Analysis of Their Operational Modes in Electric Power System

Directory of Open Access Journals (Sweden)

A. M. Gashimov

2013-01-01

Full Text Available The paper considers problems pertaining to modeling and simulation of operational hybrid system modes of the distributed generation comprising conventional sources – modular diesel generators, gas-turbine power units; and renewable sources – wind and solar power plants. Operational modes of the hybrid system have been investigated under conditions of electrical connection with electric power system and in case of its isolated operation. As a consequence

Operation modes research of liquefied natural gas storages as a part of the ground complexes equipment

Directory of Open Access Journals (Sweden)

N. S. Korolev

2014-01-01

Full Text Available The use of the Liquefied Natural Gas (LNG in the space-rocket equipment is motivated by some advantages. That is why a lot of tests and works are actively carried out now on rocket engines using liquefied natural gas.To provide the engine tests and subsequent rocket complex operation a creation of LNG storages is demanded as a part of ground processing equipment and support for their safe operation conditions.One of LNG danger factor is its low boiling temperature, and also changing the condition, density and LNG boiling temperature at storage due to evaporation of light component, namely methane. At refill of the storages having fuel remains with a new LNG portion these factors can lead to formation of the stratified macro-layers and cause a mode of the intensive mixing that is called "rollover", with almost instant evaporation of LNG big mass and sharp pressure boost, capable to result in the storage distraction with catastrophic effects.The work objectives are formulated such as a technique development for forecasting of the LNG parameters in operating storages including the rollover mode, a comparison of calculated results of the LNG parameters with the experimental data, and a definition of possible recommendations for safe operation of LNG storages as a part of the ground complexes equipment.The paper reviews 12 publications concerning the issues and proceeding processes at operation of LNG storages, including the rollover mode.To verify the reliability of process simulation results in the LNG, represented in models by the binary methane-ethane mixture the calculated values have been compared with the experimental data for a LNG storage mode in the reservoir of a ground test complex.The reliability of developed models of the heat-mass-exchange processes in stratified on density and temperature in LNG storage with emergence of conditions for the rollover mode has been verified by comparing the settlement characteristics to the published

Characteristics of switched reluctance motor operating in continuous and discontinuous conduction mode

Directory of Open Access Journals (Sweden)

Ćalasan Martin P.

2013-01-01

Full Text Available This paper presents mechanical characteristics of Switched Reluctance Motor (SRM when it operates in Discontinuous Conduction Mode (DCM or in Continuous Conduction Mode (CCM, i.e. when the current through the phase coils (windings flows discontinuously or continuously. Firstly, in order to maximize the output power of SRM optimization of its control parameters was performed, such that the peak and RMS values of the current do not exceed the predefined values. The optimal control parameters vs. rotation speed, as well as the corresponding characteristics of torque, power and efficiency. It is shown that with CCM the machine torque (power, at high speed, can be increased.

Detectors for alpha particles and X-rays operating in ambient air in pulse counting mode and/or with gas amplification

CERN Document Server

Charpak, Georges; Breuil, P; Peskov, Vladimir

2008-01-01

Ionization chambers working in ambient air in current detection mode are widely used in several applications such as smoke detection, dosimetry, therapeutic beam monitoring and cetera. The aim of this work was to investigate if gaseous detectors can operate in ambient air in pulse counting mode as well as with gas amplification. . To investigate the feasibility of this method two types of open- end gaseous detectors were build and successfully tested. The first one was a single wire or multiwire cylindrical geometry detector operating in pulse mode at a gas gain of 1. The second type alpha detector was an innovative GEM-like detector with resistive electrodes operating in air in avalanche mode at high gas gains (up to 10E4). A detailed comparison between these two detectors is given as well as comparison with the commercially available alpha detectors. The main advantages of gaseous detectors operating in air in a pulse detection mode are their simplicity, low cost and high sensitivity. One of the possible ap...

Single longitudinal mode operation of a solid-state dye laser oscillator

CERN Document Server

Lim, G; Kim, H S; Cha, B H; Lee, J M

2000-01-01

We have operated a single longitudinal mode of a solid-state dye laser oscillator in a Littman configuration. The host material of the solid-state gain medium was rhodamine dye-doped poly (methyl methacrylate). The pumping source was the second harmonic of a Nd:YAG laser with a repetition rate of 10 Hz. The measured linewidth of the laser output was about 1.5 GHz.

Path planning during combustion mode switch

Science.gov (United States)

Jiang, Li; Ravi, Nikhil

2015-12-29

Systems and methods are provided for transitioning between a first combustion mode and a second combustion mode in an internal combustion engine. A current operating point of the engine is identified and a target operating point for the internal combustion engine in the second combustion mode is also determined. A predefined optimized transition operating point is selected from memory. While operating in the first combustion mode, one or more engine actuator settings are adjusted to cause the operating point of the internal combustion engine to approach the selected optimized transition operating point. When the engine is operating at the selected optimized transition operating point, the combustion mode is switched from the first combustion mode to the second combustion mode. While operating in the second combustion mode, one or more engine actuator settings are adjusted to cause the operating point of the internal combustion to approach the target operating point.

Voltage Harmonic Compensation of a Microgrid Operating in Islanded and Grid-Connected Modes

DEFF Research Database (Denmark)

Savaghebi, Mehdi; Jalilian, Alireza; Vasquez, Juan C.

2011-01-01

In this paper, a method for voltage harmonic compensation in a microgrid operating in islanded and gridconnected modes is presented. Harmonic compensation is done through proper control of distributed generators (DGs) interface converters. In order to achieve proper sharing of the compensation...

Current distribution measurements inside an electromagnetic plasma gun operated in a gas-puff mode

OpenAIRE

Poehlmann, Flavio R.; Cappelli, Mark A.; Rieker, Gregory B.

2010-01-01

Measurements are presented of the time-dependent current distribution inside a coaxial electromagnetic plasma gun. The measurements are carried out using an array of six axially distributed dual-Rogowski coils in a balanced circuit configuration. The radial current distributions indicate that operation in the gas-puff mode, i.e., the mode in which the electrode voltage is applied before injection of the gas, results in a stationary ionization front consistent with the presence of a plasma def...

Operating modes of superconducting tunnel junction device

Energy Technology Data Exchange (ETDEWEB)

Maehata, Keisuke [Kyushu Univ., Fukuoka (Japan). Faculty of Engineering

1998-07-01

In the Electrotechnical Laboratory, an Nb type superconducting tunnel junction (STJ) device with 200 x 200 sq. micron in area and super high quality was manufactured. By using 55-fe source, response of this large area STJ to X-ray was measured. In this measurement, two action modes with different output wave height from front amplifier were observed. Then, in this study, current-voltage feature of the element in each action mode was analyzed to elucidate a mechanism to form such two action modes. The feature was analyzed by using first order approximate solution on cavity resonance mode of Sine-Gordon equation. From the analytical results, it could be supposed that direction and magnitude of effective magnetic field penetrating into jointed area changed by an induction current effect owing to impressing speed of the magnetic field, which brings two different current-voltage features to make possible to observe two action modes with different pulse wave height. (G.K.)

Overview of long pulse H-mode operation on EAST

Science.gov (United States)

Gong, X.; Garofalo, A. M.; Wan, B.; Li, J.; Qian, J.; Li, E.; Liu, F.; Zhao, Y.; Wang, M.; Xu, H.; EAST Team

2017-10-01

The EAST research program aims to demonstrate steady-state long-pulse high-performance H-mode operations with ITER-like poloidal configuration and RF-dominated heating schemes. In the recent experimental campaign, a long pulse fully non-inductive H-mode discharge lasting over 100 seconds using the upper ITER-like tungsten divertor has been achieved in EAST. This scenario used only RF heating and current drive, but also benefitted from an integrated control of the wall conditioning, plasma configuration, divertor heat flux, particle exhaust, impurity management and superconducting coils safety. Maintaining effective coupling of multiple RF heating and current drive sources on EAST is a critical ingredient. This long pulse discharge had good energy confinement, H98,y2 1.1-1.2, and all of the plasma parameters reach a true steady-state. Power balance indicates that the confinement improvement is due partly to a significantly reduced core electron transport inside minor radius rho<0.4. This work was supported by the National Magnetic Confinement Fusion Program of China Contract No. 2015GB10200 and the US Department of Energy Contract No. DE-SC0010685.

Water calorimetry with thermistor bridge operated in DC and AC mode: comparative results

International Nuclear Information System (INIS)

Guerra, A.S.; Laitano, R.F.; Petrocchi, A.

1997-01-01

An experimental study was carried out to find out the optimal conditions for measuring the output signal in a water calorimeter. To this end the thermistor bridge of the calorimeter was operated in AC and in DC mode, respectively. A comparative analysis of these two alternative methods was the made. In the AC mode measurement a lock-in amplifier based experimental assembly was used and compared to the more conventional system based on a high-sensitivty DC amplifier. The AC system resulted to be preferable as far as the short term and long term reproducibility is concerned. (orig.)

Water calorimetry with thermistor bridge operated in DC and AC mode: comparative results

Energy Technology Data Exchange (ETDEWEB)

Guerra, A S; Laitano, R F; Petrocchi, A [Ist. Nazionale di Metrologia delle Radiazioni Ionizzanti, ENEA, Roma (Italy)

1997-09-01

An experimental study was carried out to find out the optimal conditions for measuring the output signal in a water calorimeter. To this end the thermistor bridge of the calorimeter was operated in AC and in DC mode, respectively. A comparative analysis of these two alternative methods was the made. In the AC mode measurement a lock-in amplifier based experimental assembly was used and compared to the more conventional system based on a high-sensitivty DC amplifier. The AC system resulted to be preferable as far as the short term and long term reproducibility is concerned. (orig.)

Performance enhancement of high-field asymmetric waveform ion mobility spectrometry by applying differential-RF-driven operation mode.

Science.gov (United States)

Zeng, Yue; Tang, Fei; Zhai, Yadong; Wang, Xiaohao

2017-09-01

The traditional operation mode of high-field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) uses a one-way radio frequency (RF) voltage input as the dispersion voltage. This requires a high voltage input and limits power consumption reduction and miniaturization of instruments. With higher dispersion voltages or larger compensation voltages, there also exist problems such as low signal intensity or the fact that the dispersion voltage is no longer much larger than the compensation voltage. In this paper, a differential-RF-driven operation mode of FAIMS is proposed. The two-way RF is used to generate the dispersion field, and a phase difference is added between the two RFs to generate a single step waveform field. Theoretical analysis, and experimental results from an ethanol sample, showed that the peak positions of the ion spectra changed linearly (R 2 = 0.9992) with the phase difference of the two RFs in the differential-RF-driven mode and that the peak intensity of the ion spectrum could be enhanced by more than eight times for ethanol ions. In this way, it is possible to convert the ion spectrum peaks outside the separation or compensation voltage range into a detectable range, by changing the phase difference. To produce the same separation electric field, the high-voltage direct current input voltage can be maximally reduced to half of that in the traditional operation mode. Without changing the drift region size or drift condition, the differential-RF-driven operation mode can reduce power consumption, increase signal-to-noise ratio, extend the application range of the dispersion voltage and compensation voltage, and improve FAIMS detection performance.

Optimization of TW accelerating structures for SLED type modes of operation

International Nuclear Information System (INIS)

Le Duff, J.

1984-02-01

The SLED method was invented at SLAC in order to produce more electron (and positron) energy from the existing klystrons. The LEP injector LINAC, also now is supposed to operate in the SLED-2 mode. At DESY similar developments have been undertaken too, to improve the linac performances. However in all cases the accelerating sections were not initially optimized for such a mode of operation, and in most cases the designers ended with long accelerating sections making a more efficient use of the klystron power, with rectangular pulses, sometimes at the expense of a longer linac. The present study deals with new approaches for designing linacs, and in particular compact linacs, considering from the beginning a pulse compression scheme, where the main feature consists of having an exponential pulse shape instead of rectangular. Moreover a detailed comparison is made between constant impedance and constant gradient travelling wave (TW) accelerating structures. As a matter of fact the constant impedance structure when optimized looks sligthy better than the second one. In addition short structures appear to be more efficient for a given number of RF sources. Consequently linear accelerators can be made more simple and less expensive, and if one allows for higher tolerable accelerating gradients they can be made even compact

Methods on TLD management be applicable in nuclear power plantsunder the multi-reactor operational mode

International Nuclear Information System (INIS)

Luo Huiyong; Wen Qinghua; Li Ruirong; Yu Enjian

2006-01-01

This paper discusses the methods on management of TLD dosimeters adopted in DNMC and other NPPs, analyzes and evaluates their both defects and advantages. Facing the coming of the multi-reactor operational mode applied in NPPs, a new method intelligent management mode is put forward, this optimized method not only assures the accuracy of TLD's measurement but also reduces the cost of production and improves the efficiency of management greatly. (authors)

Dual mode operation, highly selective nanohole array-based plasmonic colour filters

Science.gov (United States)

Fouladi Mahani, Fatemeh; Mokhtari, Arash; Mehran, Mahdiyeh

2017-09-01

Taking advantage of nanostructured metal films as plasmonic colour filters (PCFs) has been evolved remarkably as an alternative to the conventional technologies of chemical colour filtering. However, most of the proposed PCFs depict a poor colour purity focusing on generating either the additive or subtractive colours. In this paper, we present dual mode operation PCFs employing an opaque aluminium film patterned with sub-wavelength holes. Subtractive colours like cyan, magenta, and yellow are the results of reflection mode of these filters yielding optical efficiencies as high as 70%-80% and full width at half maximum of the stop-bands up to 40-50 nm. The colour selectivity of the transmission mode for the additive colours is also significant due to their enhanced performance through the utilization of a relatively thick aluminium film in contact with a modified dielectric environment. These filters provide a simple design with one-step lithography in addition to compatibility with the conventional CMOS processes. Moreover, they are polarization insensitive due to their symmetric geometry. A complete palette of pure subtractive and additive colours has been realized with potential applications, such as multispectral imaging, CMOS image sensors, displays, and colour printing.

A square-plate ultrasonic linear motor operating in two orthogonal first bending modes.

Science.gov (United States)

Chen, Zhijiang; Li, Xiaotian; Chen, Jianguo; Dong, Shuxiang

2013-01-01

A novel square-plate piezoelectric ultrasonic linear motor operated in two orthogonal first bending vibration modes (B₁) is proposed. The piezoelectric vibrator of the linear motor is simply made of a single PZT ceramic plate (sizes: 15 x 15 x 2 mm) and poled in its thickness direction. The top surface electrode of the square ceramic plate was divided into four active areas along its two diagonal lines for exciting two orthogonal B₁ modes. The achieved driving force and speed from the linear motor are 1.8 N and 230 mm/s, respectively, under one pair orthogonal voltage drive of 150 V(p-p) at the resonance frequency of 92 kHz. The proposed linear motor has advantages over conventional ultrasonic linear motors, such as relatively larger driving force, very simple working mode and structure, and low fabrication cost.

Thermo-mechanical and damage analyses of EAST carbon divertor under type-I ELMy H-mode operation

Energy Technology Data Exchange (ETDEWEB)

Li, W.X. [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026 (China); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Song, Y.T. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026 (China); Ye, M.Y. [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026 (China); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Peng, X.B., E-mail: pengxb@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Wu, S.T. [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026 (China); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Qian, X.Y.; Zhu, C.C. [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026 (China)

2016-04-15

Highlights: • Type-I ELMy H-mode is one of the most severe operating environment in tokamak. • An actual time-history heat load has been used in thermo-mechanical analysis. • The analysis results are time-dependent during the whole discharge process. • The analysis could be very useful in evaluating the operational capability of the divertor. - Abstract: The lower carbon divertor has been used since 2008 in EAST, and many significant physical results, like the 410 s long pulse discharge and the 32 s H-mode operation, have been achieved. As the carbon divertor will still be used in the next few years while the injected auxiliary heating power would be increased gradually, it’s necessary to evaluate the operational capability of the carbon divertor under the heat loads during future operation. In this paper, an actual time-history heat load during type-I ELMy H-mode from EAST experiment, as one of the most severe operating environment in tokamak, has been used in the calculation and analysis. The finite element (FE) thermal and mechanical calculations have been carried out to analysis the stress and deformation of the carbon divertor during the heat loads. According to the results, the main impact on the overall temperature comes from the relative stable phase before and after the type-I ELMs and local peak load, and the transient thermal load such as type-I ELMy only has a significant effect on the surface temperature of the graphite tiles. The carbon divertor would work with high stress near the screw bolts in the current operational conditions, because of high preload and conservative frictional coefficient between the bolts and heatsink. For the future operation, new plasma facing materials (PFM) and divertor technology should be developed.

Passive mode-locking dynamics in a 3.1GHz quantum dot laser diode operating around 1.5μm

NARCIS (Netherlands)

Tahvili, M.S.; Heck, M.J.R.; Nötzel, R.; Smit, M.K.; Bente, E.A.J.M.

2010-01-01

We report on passive mode-locking in a 3.1GHz InAs/InP(100) quantum dot laser diode operating around 1.5µm. The range of stable passive mode-locking, detailed measurements of the linewidth of the optical modes and the phase modulation in output pulses are presented.

New VCSEL technology with scalability for single mode operation and densely integrated arrays

Science.gov (United States)

Zhao, Guowei; Demir, Abdullah; Freisem, Sabine; Zhang, Yu; Liu, Xiaohang; Deppe, Dennis G.

2011-06-01

Data are presented demonstrating a new lithographic vertical-cavity surface-emitting laser (VCSEL) technology, which produces simultaneous mode- and current-confinement only by lithography and epitaxial crystal growth. The devices are grown by solid source molecular beam epitaxy, and have lithographically defined sizes that vary from 3 μm to 20 μm. The lithographic process allows the devices to have high uniformity throughout the wafer and scalability to very small size. The 3 μm device shows a threshold current of 310 μA, the slope efficiency of 0.81 W/A, and the maximum output power of more than 5 mW. The 3 μm device also shows single-mode single-polarization operation without the use of surface grating, and has over 25 dB side-mode-suppression-ratio up to 1 mW of output power. The devices have low thermal resistance due to the elimination of oxide aperture. High reliability is achieved by removal of internal strain caused by the oxide, stress test shows no degradation for the 3 μm device operating at very high injection current level of 142 kA/cm2 for 1000 hours, while at this dive level commercial VCSELs fail rapidly. The lithographic VCSEL technology can lead to manufacture of reliable small size laser diode, which will have application in large area 2-D arrays and low power sensors.

Development of Abnormal Operating Strategies for Loss of Ultimate Heat Sink (LOUHS) at Shutdown Mode in Westinghouse Type Nuclear Power Plant

Energy Technology Data Exchange (ETDEWEB)

Yoon, Duk-Joo; Lee, Seung-Chan; Sung, Je-Joong; Ha, Sang Jun [KHNP CRI, Daejeon (Korea, Republic of); Hwang, Su-Hyun [FNC Tech. Co., Yongin (Korea, Republic of)

2016-10-15

Loss of all AC power is classified as one of multiple failure accident by regulatory guide of Korean accident management program. Therefore we need develop strategies for the abnormal operating procedure both of power operating and shutdown mode. This paper developed abnormal operating guideline for loss of all AC power by analysis of accident scenario in pressurized water reactor. This paper analyzed the extended SBO in shutdown operating mode and developed the operating strategy of the abnormal operation procedure. Operator action for the emergency are not required to take in 500 minutes and 60 minutes in intact and opened RCS state respectively.

Possibilities and testing of CPRNG in block cipher mode of operation PM-DC-LM

Energy Technology Data Exchange (ETDEWEB)

Zacek, Petr; Jasek, Roman; Malanik, David [Faculty of applied Informatics, Tomas Bata University in Zlin, Zlin, Czech Republic zacek@fai.utb.cz, jasek@fai.utb.cz, dmalanik@fai.utb.cz (Czech Republic)

2016-06-08

This paper discusses the chaotic pseudo-random number generator (CPRNG), which is used in block cipher mode of operation called PM-DC-LM. PM-DC-LM is one of possible subversions of general PM mode. In this paper is not discussed the design of PM-DC-LM, but only CPRNG as a part of it because designing is written in other papers. Possibilities, how to change or to improve CPRNG are mentioned. The final part is devoted for a little testing of CPRNG and some testing data are shown.

Possibilities and testing of CPRNG in block cipher mode of operation PM-DC-LM

Science.gov (United States)

Zacek, Petr; Jasek, Roman; Malanik, David

2016-06-01

This paper discusses the chaotic pseudo-random number generator (CPRNG), which is used in block cipher mode of operation called PM-DC-LM. PM-DC-LM is one of possible subversions of general PM mode. In this paper is not discussed the design of PM-DC-LM, but only CPRNG as a part of it because designing is written in other papers. Possibilities, how to change or to improve CPRNG are mentioned. The final part is devoted for a little testing of CPRNG and some testing data are shown.

Possibilities and testing of CPRNG in block cipher mode of operation PM-DC-LM

International Nuclear Information System (INIS)

Zacek, Petr; Jasek, Roman; Malanik, David

2016-01-01

This paper discusses the chaotic pseudo-random number generator (CPRNG), which is used in block cipher mode of operation called PM-DC-LM. PM-DC-LM is one of possible subversions of general PM mode. In this paper is not discussed the design of PM-DC-LM, but only CPRNG as a part of it because designing is written in other papers. Possibilities, how to change or to improve CPRNG are mentioned. The final part is devoted for a little testing of CPRNG and some testing data are shown.

Modified Adaptive Control for Region 3 Operation in the Presence of Wind Turbine Structural Modes

Science.gov (United States)

Frost, Susan Alane; Balas, Mark J.; Wright, Alan D.

2010-01-01

Many challenges exist for the operation of wind turbines in an efficient manner that is reliable and avoids component fatigue and failure. Turbines operate in highly turbulent environments resulting in aerodynamic loads that can easily excite turbine structural modes, possibly causing component fatigue and failure. Wind turbine manufacturers are highly motivated to reduce component fatigue and failure that can lead to loss of revenue due to turbine down time and maintenance costs. The trend in wind turbine design is toward larger, more flexible turbines that are ideally suited to adaptive control methods due to the complexity and expense required to create accurate models of their dynamic characteristics. In this paper, we design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed horizontal axis wind turbine operating in Region 3. The objective of the adaptive pitch controller is to regulate generator speed, accommodate wind gusts, and reduce the excitation of structural modes in the wind turbine. The control objective is accomplished by collectively pitching the turbine blades. The adaptive collective pitch controller for Region 3 was compared in simulations with a baseline classical Proportional Integrator (PI) collective pitch controller. The adaptive controller will demonstrate the ability to regulate generator speed in Region 3, while accommodating gusts, and reducing the excitation of certain structural modes in the wind turbine.

Assessment of body mapping sportswear using a manikin operated in constant temperature mode and thermoregulatory model control mode

Science.gov (United States)

Wang, Faming; Del Ferraro, Simona; Molinaro, Vincenzo; Morrissey, Matthew; Rossi, René

2014-09-01

Regional sweating patterns and body surface temperature differences exist between genders. Traditional sportswear made from one material and/or one fabric structure has a limited ability to provide athletes sufficient local wear comfort. Body mapping sportswear consists of one piece of multiple knit structure fabric or of different fabric pieces that may provide athletes better wear comfort. In this study, the `modular' body mapping sportswear was designed and subsequently assessed on a `Newton' type sweating manikin that operated in both constant temperature mode and thermophysiological model control mode. The performance of the modular body mapping sportswear kit and commercial products were also compared. The results demonstrated that such a modular body mapping sportswear kit can meet multiple wear/thermal comfort requirements in various environmental conditions. All body mapping clothing (BMC) presented limited global thermophysiological benefits for the wearers. Nevertheless, BMC showed evident improvements in adjusting local body heat exchanges and local thermal sensations.

H-mode pedestal and threshold studies over an expanded operating space on Alcator C-Moda)

Science.gov (United States)

Hubbard, A. E.; Hughes, J. W.; Bespamyatnov, I. O.; Biewer, T.; Cziegler, I.; LaBombard, B.; Lin, Y.; McDermott, R.; Rice, J. E.; Rowan, W. L.; Snipes, J. A.; Terry, J. L.; Wolfe, S. M.; Wukitch, S.

2007-05-01

This paper reports on studies of the edge transport barrier and transition threshold of the high confinement (H) mode of operation on the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)], over a wide range of toroidal field (2.6-7.86T) and plasma current (0.4-1.7MA). The H-mode power threshold and edge temperature at the transition increase with field. Barrier widths, pressure limits, and confinement are nearly independent of field at constant current, but the operational space at high B shifts toward higher temperature and lower density and collisionality. Experiments with reversed field and current show that scrape-off-layer flows in the high-field side depend primarily on configuration. In configurations with the B ×∇B drift away from the active X-point, these flows lead to more countercurrent core rotation, which apparently contributes to higher H-mode thresholds. In the unfavorable case, edge temperature thresholds are higher, and slow evolution of profiles indicates a reduction in thermal transport prior to the transition in particle confinement. Pedestal temperatures in this case are also higher than in the favorable configuration. Both high-field and reversed-field results suggest that parameters at the L-H transition are influencing the evolution and parameters of the H-mode pedestal.

Calibration and fluctuation of the secular frequency peak amplitude versus initial condition distribution of the ion cloud confined into a three-dimensional quadrupole ion trap using a fourier transform operating mode and a steady ion flow injection mode

International Nuclear Information System (INIS)

Janulyte, A.; Andre, J.; Carette, M.; Mercury, M.; Reynard, C; Zerega, Y.

2009-01-01

A specific Fourier transform operating mode is applied to a 3-dimensional quadrupolar ion trap for mass analysis (Fourier Transform Quadrupolar Ion Trap (FTQIT) Operating Mode or Mass Spectrometer). With this operating mode, an image signal, which is representative of the collective motion of simultaneously confined ions, is made up from a set of recorded time-of-flight histograms. In an ion trap, the secular frequency of ion motion depends on m/Z ratio of the ion. By Fourier transformation of the image signal, one observes the frequency peak of each confined ionic species. When only one ionic species is confined, the peak amplitude is proportional to the maximal amplitude of the image signal. The maximal amplitude of the image signal is expressed according to the operating parameters, the initial conditions of the ions and the number of ions. Simulation tools lead to fluctuation calculation of the maximal amplitude of the image signal. Two origins are explored: (1) the fluctuation of the numbers of ions according to the steady ion flow injection mode (SIFIM) used with this operating mode and (2) the distribution fluctuation of the initial positions and velocities. Initial confinement conditions, obtained with SIFIM injection mode, lead to optimal detection with small fluctuations of the peak amplitude for Fourier transform operating mode applied to an ion trap. (authors)

Physics of increased edge electron temperature and density turbulence during ELM-free QH-mode operation on DIII-D

Science.gov (United States)

Sung, C.; Rhodes, T. L.; Staebler, G. M.; Yan, Z.; McKee, G. R.; Smith, S. P.; Osborne, T. H.; Peebles, W. A.

2018-05-01

For the first time, we report increased edge electron temperature and density turbulence levels ( T˜ e and n˜ e) in Edge Localized Mode free Quiescent H-mode (ELM-free QH-mode) plasmas as compared to the ELMing time period. ELMs can severely damage plasma facing components in fusion plasma devices due to their large transient energy transport, making ELM-free operation a highly sought after goal. The QH-mode is a candidate for this goal as it is ELM-free for times limited only by hardware constraints. It is found that the driving gradients decrease during the QH-mode compared to the ELMing phase, however, a significant decrease in the ExB shearing rate is also observed that taken together is consistent with the increased turbulence. These results are significant as the prediction and control of ELM-free H-mode regimes are crucial for the operation of future fusion devices such as ITER. The changes in the linear growth rates calculated by CGYRO [Candy et al., J. Comput. Phys. 324, 73 (2016)] and the measured ExB shearing rate between ELMing and QH-mode phases are qualitatively consistent with these turbulence changes. Comparison with ELMing and 3D fields ELM suppressed H-mode finds a similar increase in T˜ e and n˜ e, however, with distinctly different origins, the increased driving gradients rather than the changes in the ExB shearing rate in 3D fields ELM suppressed the H-mode. However, linear gyrokinetic calculation results are generally consistent with the increased turbulence in both ELM-controlled discharges.

Gravitationally induced zero modes of the Faddeev-Popov operator in the Coulomb gauge for Abelian gauge theories

Science.gov (United States)

Canfora, Fabrizio; Giacomini, Alex; Oliva, Julio

2010-08-01

It is shown that on curved backgrounds, the Coulomb gauge Faddeev-Popov operator can have zero modes even in the Abelian case. These zero modes cannot be eliminated by restricting the path integral over a certain region in the space of gauge potentials. The conditions for the existence of these zero modes are studied for static spherically symmetric spacetimes in arbitrary dimensions. For this class of metrics, the general analytic expression of the metric components in terms of the zero modes is constructed. Such expression allows one to find the asymptotic behavior of background metrics, which induce zero modes in the Coulomb gauge, an interesting example being the three-dimensional anti-de Sitter spacetime. Some of the implications for quantum field theory on curved spacetimes are discussed.

Acquisition performance of LAPAN-A3/IPB multispectral imager in real-time mode of operation

Science.gov (United States)

Hakim, P. R.; Permala, R.; Jayani, A. P. S.

2018-05-01

LAPAN-A3/IPB satellite was launched in June 2016 and its multispectral imager has been producing Indonesian coverage images. In order to improve its support for remote sensing application, the imager should produce images with high quality and quantity. To improve the quantity of LAPAN-A3/IPB multispectral image captured, image acquisition could be executed in real-time mode from LAPAN ground station in Bogor when the satellite passes west Indonesia region. This research analyses the performance of LAPAN-A3/IPB multispectral imager acquisition in real-time mode, in terms of image quality and quantity, under assumption of several on-board and ground segment limitations. Results show that with real-time operation mode, LAPAN-A3/IPB multispectral imager could produce twice as much as image coverage compare to recorded mode. However, the images produced in real-time mode will have slightly degraded quality due to image compression process involved. Based on several analyses that have been done in this research, it is recommended to use real-time acquisition mode whenever it possible, unless for some circumstances that strictly not allow any quality degradation of the images produced.

A possible way for conservatism reduction at the modelling of WWER operational modes

International Nuclear Information System (INIS)

Shishkov, L. K.

2010-01-01

The paper discusses the way to ensure safety operation of the WWER by meet ing the technological Safety Criteria that are defined in the documents of the state level. That Safety Criteria are ensured by-turn by implementation of the design limits for the number of core parameters at normal operation. Verification of the Safety Criteria adherences for all design modes of NPP operation is conducted in assumption that all (if possible) core parameters that have the design limits reach these limiting values. Additionally, to take into account possible error of modeling, a reactor operates in conditions for the core parameters to not reach the limits with probability greater than 95%. This method is deliberately conservative and it may be substituted with 'probabilistic method'. Probabilistic method supposes the operational parameters are defined with accounting of the possible random deviation to ensure the probability of technological Safety Criteria to be met. (Author)

Comparison of collision operators for drift and MHD-interchange modes in unsheared slab geometry

International Nuclear Information System (INIS)

Rewoldt, G.; Tang, W.M.; Hastie, R.J.

1986-02-01

The general procedure for the kinetic analysis of low-frequency electrostatic and electromagnetic modes in toroidal geometry is now well known. In the collisionless limit, the relevant dynamics (e.g., trapped particles, resonances, etc.) can be treated appropriately. However, with the introduction of collisional effects, it is customary, for tractability, to employ model collision operators which do not rigorously satisfy all conservation properties of more exact collision operators. Insight into the essential required features of such operators can be gained by studying models with increasing levels of completeness for a simpler, unsheared slab geometry. The results presented here for this simpler geometry can provide guidance in choosing model collision operators for toroidal-geometry kinetic calculations. 6 refs., 3 figs

Near-roadway monitoring of vehicle emissions as a function of mode of operation for light-duty vehicles.

Science.gov (United States)

Wen, Dongqi; Zhai, Wenjuan; Xiang, Sheng; Hu, Zhice; Wei, Tongchuan; Noll, Kenneth E

2017-11-01

Determination of the effect of vehicle emissions on air quality near roadways is important because vehicles are a major source of air pollution. A near-roadway monitoring program was undertaken in Chicago between August 4 and October 30, 2014, to measure ultrafine particles, carbon dioxide, carbon monoxide, traffic volume and speed, and wind direction and speed. The objective of this study was to develop a method to relate short-term changes in traffic mode of operation to air quality near roadways using data averaged over 5-min intervals to provide a better understanding of the processes controlling air pollution concentrations near roadways. Three different types of data analysis are provided to demonstrate the type of results that can be obtained from a near-roadway sampling program based on 5-min measurements: (1) development of vehicle emission factors (EFs) for ultrafine particles as a function of vehicle mode of operation, (2) comparison of measured and modeled CO 2 concentrations, and (3) application of dispersion models to determine concentrations near roadways. EFs for ultrafine particles are developed that are a function of traffic volume and mode of operation (free flow and congestion) for light-duty vehicles (LDVs) under real-world conditions. Two air quality models-CALINE4 (California Line Source Dispersion Model, version 4) and AERMOD (American Meteorological Society/U.S. Environmental Protection Agency Regulatory Model)-are used to predict the ultrafine particulate concentrations near roadways for comparison with measured concentrations. When using CALINE4 to predict air quality levels in the mixing cell, changes in surface roughness and stability class have no effect on the predicted concentrations. However, when using AERMOD to predict air quality in the mixing cell, changes in surface roughness have a significant impact on the predicted concentrations. The paper provides emission factors (EFs) that are a function of traffic volume and mode of

Potential profiles in the central core of the cathode in the star mode operation in an inertial-electrostatic fusion neutron source

International Nuclear Information System (INIS)

Yoshikawa, K.; Masuda, K.; Toku, H.

2003-01-01

After the successful measurements of the localized electric fields in the center-spot mode operation with relatively large space-charge effects by the laser-induced fluorescence (LIF) method, measurements of potential profiles in the star mode operation with small space-charge effects on helium gas are made in the central cathode core region of an Inertial-Electrostatic Confinement Fusion (IECF) neutron source, which is most suitable to neutron calibration in the fusion devices. Since the high-voltage is required to the star mode operation on deuterium gas, it is predicted to bring about very small beam space charge-related potential. To increase accuracy, we adopted n=4 (2 1 S to 4 1 D:HeI) transition, instead of previous n=3, which is most sensitive to the local electric fields in the Stark transition, and verified using the well-known U-shaped hollow cathode potential. The localized electric fields thus measured by LIF method using n=4 transition show negligible electric fields in the star mode compared with the center-spot mode. (author)

Operational conditions and characteristics of ELM-events during H-mode plasmas in the stellarator W7-AS

International Nuclear Information System (INIS)

Hirsch, M.; Grigull, P.; Wobig, H.; Kisslinger, J.; McCormick, K.; Anton, M.; Baldzuhn, J.; Fiedler, S.; Fuchs, Ch.; Geiger, J.; Giannone, L.; Hartfuss, H.-J.; Holzhauer, E.; Hirsch, M.; Jaenicke, R.; Kick, M.; Maassberg, H.; Wagner, F.; Weller, A.

2000-01-01

H-mode operation in the low-shear stellarator W7-AS is achieved for specific plasma edge topologies characterized by three 'operational windows' of the edge rotational transform. An explanation for this strong influence of the magnetic configuration could be the increase of viscous damping if rational surfaces and thus island structures occur within the relevant plasma edge layer, thereby impeding the development of an edge transport barrier. Prior to the final transition to a quiescent state, the plasma edge passes a rich phenomenology of dynamic behaviour such as dithering and ELMs. Plasma edge parameters indicate that a quiescent H-mode occurs if a certain edge pressure is achieved. (author)

Research on a Novel Exciting Method for a Sandwich Transducer Operating in Longitudinal-Bending Hybrid Modes

Directory of Open Access Journals (Sweden)

Yingxiang Liu

2017-06-01

Full Text Available A novel exciting method for a sandwich type piezoelectric transducer operating in longitudinal-bending hybrid vibration modes is proposed and discussed, in which the piezoelectric elements for the excitations of the longitudinal and bending vibrations share the same axial location, but correspond to different partitions. Whole-piece type piezoelectric plates with three separated partitions are used, in which the center partitions generate the first longitudinal vibration, while the upper and lower partitions produce the second bending vibration. Detailed comparisons between the proposed exciting method and the traditional one were accomplished by finite element method (FEM calculations, which were further verified by experiments. Compared with the traditional exciting method using independent longitudinal ceramics and bending ceramics, the proposed method achieves higher electromechanical coupling factors and larger vibration amplitudes, especially for the bending vibration mode. This novel exciting method for longitudinal-bending hybrid vibrations has not changed the structural dimensions of the sandwich transducer, but markedly improves the mechanical output ability, which makes it very helpful and meaningful in designing new piezoelectric actuators operated in longitudinal-bending hybrid vibration modes.

Metodika tvorby a využití případových studií ve výuce a formou Open Educational Resources (OER

Directory of Open Access Journals (Sweden)

Jana Dlouhá

2016-04-01

Full Text Available Předložená metodika tvorby regionálních případových studií (PS udržitelného rozvoje pro vysokoškolské vzdělávání má za úkol ukázat, jakým způsobem lze ve výuce využít konkrétní případy z praxe a současně jak rozvíjet výzkumné nástroje relevantní pro místní environmentální problematiku a otázky udržitelného rozvoje území; důraz je přitom kladen na regionální kontext a specifika. Publikace výsledků formou otevřených vzdělávacích zdrojů (tzv. Open Educational Resources, OER umožní využít tyto materiály pro regionálně orientované školství i na nižších stupních vzdělávacího systému, pro prezentaci regionálních zvláštností, a může sloužit též pro podporu dialogu o rozvoji území mezi různými společenskými aktéry.

Damage classification of pipelines under water flow operation using multi-mode actuated sensing technology

International Nuclear Information System (INIS)

Lee, Changgil; Park, Seunghee

2011-01-01

In a structure, several types of damage can occur, ranging from micro-cracking to corrosion or loose bolts. This makes identifying the damage difficult with a single mode of sensing. Therefore, a multi-mode actuated sensing system is proposed based on a self-sensing circuit using a piezoelectric sensor. In self-sensing-based multi-mode actuated sensing, one mode provides a wide frequency-band structural response from the self-sensed impedance measurement and the other mode provides a specific frequency-induced structural wavelet response from the self-sensed guided wave measurement. In this experimental study, a pipeline system under water flow operation was examined to verify the effectiveness and robustness of the proposed structural health monitoring approach. Different types of structural damage were inflicted artificially on the pipeline system. To classify the multiple types of structural damage, supervised learning-based statistical pattern recognition was implemented by composing a three-dimensional space using the damage indices extracted from the impedance and guided wave features as well as temperature variations. For a more systematic damage classification, several control parameters were optimized to determine an optimal decision boundary for the supervised learning-based pattern recognition. Further research issues are also discussed for real-world implementations of the proposed approach

Improving Reliability of High Power Quasi-CW Laser Diode Arrays Operating in Long Pulse Mode

Science.gov (United States)

Amzajerdian, Farzin; Meadows, Byron L.; Barnes, Bruce W.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.; Baker, Nathaniel R.

2006-01-01

Operating high power laser diode arrays in long pulse regime of about 1 msec, which is required for pumping 2-micron thulium and holmium-based lasers, greatly limits their useful lifetime. This paper describes performance of laser diode arrays operating in long pulse mode and presents experimental data of the active region temperature and pulse-to-pulse thermal cycling that are the primary cause of their premature failure and rapid degradation. This paper will then offer a viable approach for determining the optimum design and operational parameters leading to the maximum attainable lifetime.

Experimental Investigation of Operation of VVER Steam Generator in Condensation Mode in the Event of the Severe Accident

Energy Technology Data Exchange (ETDEWEB)

Morozov, Andrey [Institute for Physics and Power Engineering by A.I. Leypunsky, 1 Bondarenko sq. Obninsk, 249033 (Russian Federation)

2008-07-01

For new Russian nuclear power plants with VVER-1200 reactor in the event of a beyond design basis accident, provision is made for the use of passive safety systems for necessary core cooling. These safety systems include the passive heat removal system (PHRS). In the case of leakage in the primary circuit this system assures the transition of steam generators (SG) to operation in the mode of condensation of the primary circuit steam. As a result, the condensate from SG arrives at the core providing its additional cooling. To investigate the condensation mode of VVER SG operation, a large scale HA2M-SG test facility was constructed. The rig incorporates: buffer tank, SG model with scale is 1:46, PHRS heat exchanger. Experiments at the test facility have been performed to investigate condensation mode of operation of SG model at the pressure 0.4 MPa, correspond to VVER reactor pressure at the last stage of the beyond design basis accident. The report presents the test procedure and the basic obtained test results. (authors)

A 9.61-W, b-cut Tm,Ho:YAP laser in Q-switched mode operation

Science.gov (United States)

Li, Guoxing; Yang, Xining; Zhang, Ziqiu; Zhang, Hongda; Zhang, Liang

2018-02-01

A high energy of b-cut Tm, Ho:YAlO3 laser is reported in the paper. The laser operated in acousto-optical Qswitched mode at 2.12 μm. The output average power of 9.61 W was achieved at the pulse repetition frequency of 10 kHz ,and the power of 11.6 W was acquired in continuous wave mode. Moreover, the energy per pulse of 0.961 mJ in 64.4 ns was acquired at 10 kHz with a 14.92-kW peak power.

A Closed-Loop Model of Operator Visual Attention, Situation Awareness, and Performance Across Automation Mode Transitions.

Science.gov (United States)

Johnson, Aaron W; Duda, Kevin R; Sheridan, Thomas B; Oman, Charles M

2017-03-01

This article describes a closed-loop, integrated human-vehicle model designed to help understand the underlying cognitive processes that influenced changes in subject visual attention, mental workload, and situation awareness across control mode transitions in a simulated human-in-the-loop lunar landing experiment. Control mode transitions from autopilot to manual flight may cause total attentional demands to exceed operator capacity. Attentional resources must be reallocated and reprioritized, which can increase the average uncertainty in the operator's estimates of low-priority system states. We define this increase in uncertainty as a reduction in situation awareness. We present a model built upon the optimal control model for state estimation, the crossover model for manual control, and the SEEV (salience, effort, expectancy, value) model for visual attention. We modify the SEEV attention executive to direct visual attention based, in part, on the uncertainty in the operator's estimates of system states. The model was validated using the simulated lunar landing experimental data, demonstrating an average difference in the percentage of attention ≤3.6% for all simulator instruments. The model's predictions of mental workload and situation awareness, measured by task performance and system state uncertainty, also mimicked the experimental data. Our model supports the hypothesis that visual attention is influenced by the uncertainty in system state estimates. Conceptualizing situation awareness around the metric of system state uncertainty is a valuable way for system designers to understand and predict how reallocations in the operator's visual attention during control mode transitions can produce reallocations in situation awareness of certain states.

Self-seeded operation of the LCLS hard X-ray FEL in the long-bunch mode

International Nuclear Information System (INIS)

Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

2010-12-01

Self-seeding options for the LCLS baseline were recently investigated using a scheme which relies on a single-crystal monochromator in Bragg-transmission geometry. The LCLS low-charge (0.02 nC) mode of operation was considered in order to demonstrate the feasibility of the proposed scheme. The wakefield effects from the linac and from the undulator vacuum chamber are much reduced at such low charge, and can be ignored. In this paper we extend our previous investigations to the case of the LCLS mode of operation with nominal charge. Based on the LCLS start-to-end simulation for an electron beam charge of 0.25 nC, and accounting for the wakefields from the undulator vacuum chamber we demonstrate that the same simplest self-seeding system (two undulators with a single-crystal monochromator in between) is appropriate not only for short (few femtosecond) bunches, but for longer bunches too. (orig.)

Self-seeded operation of the LCLS hard X-ray FEL in the long-bunch mode

Energy Technology Data Exchange (ETDEWEB)

Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2010-12-15

Self-seeding options for the LCLS baseline were recently investigated using a scheme which relies on a single-crystal monochromator in Bragg-transmission geometry. The LCLS low-charge (0.02 nC) mode of operation was considered in order to demonstrate the feasibility of the proposed scheme. The wakefield effects from the linac and from the undulator vacuum chamber are much reduced at such low charge, and can be ignored. In this paper we extend our previous investigations to the case of the LCLS mode of operation with nominal charge. Based on the LCLS start-to-end simulation for an electron beam charge of 0.25 nC, and accounting for the wakefields from the undulator vacuum chamber we demonstrate that the same simplest self-seeding system (two undulators with a single-crystal monochromator in between) is appropriate not only for short (few femtosecond) bunches, but for longer bunches too. (orig.)

Single-mode fiber laser based on core-cladding mode conversion.

Science.gov (United States)

Suzuki, Shigeru; Schülzgen, Axel; Peyghambarian, N

2008-02-15

A single-mode fiber laser based on an intracavity core-cladding mode conversion is demonstrated. The fiber laser consists of an Er-doped active fiber and two fiber Bragg gratings. One Bragg grating is a core-cladding mode converter, and the other Bragg grating is a narrowband high reflector that selects the lasing wavelength. Coupling a single core mode and a single cladding mode by the grating mode converter, the laser operates as a hybrid single-mode laser. This approach for designing a laser cavity provides a much larger mode area than conventional large-mode-area step-index fibers.

On Convergence of Extended Dynamic Mode Decomposition to the Koopman Operator

Science.gov (United States)

Korda, Milan; Mezić, Igor

2018-04-01

Extended dynamic mode decomposition (EDMD) (Williams et al. in J Nonlinear Sci 25(6):1307-1346, 2015) is an algorithm that approximates the action of the Koopman operator on an N-dimensional subspace of the space of observables by sampling at M points in the state space. Assuming that the samples are drawn either independently or ergodically from some measure μ , it was shown in Klus et al. (J Comput Dyn 3(1):51-79, 2016) that, in the limit as M→ ∞, the EDMD operator K_{N,M} converges to K_N, where K_N is the L_2(μ )-orthogonal projection of the action of the Koopman operator on the finite-dimensional subspace of observables. We show that, as N → ∞, the operator K_N converges in the strong operator topology to the Koopman operator. This in particular implies convergence of the predictions of future values of a given observable over any finite time horizon, a fact important for practical applications such as forecasting, estimation and control. In addition, we show that accumulation points of the spectra of K_N correspond to the eigenvalues of the Koopman operator with the associated eigenfunctions converging weakly to an eigenfunction of the Koopman operator, provided that the weak limit of the eigenfunctions is nonzero. As a by-product, we propose an analytic version of the EDMD algorithm which, under some assumptions, allows one to construct K_N directly, without the use of sampling. Finally, under additional assumptions, we analyze convergence of K_{N,N} (i.e., M=N), proving convergence, along a subsequence, to weak eigenfunctions (or eigendistributions) related to the eigenmeasures of the Perron-Frobenius operator. No assumptions on the observables belonging to a finite-dimensional invariant subspace of the Koopman operator are required throughout.

Information needs in nuclear power plants during low power operation modes

Energy Technology Data Exchange (ETDEWEB)

Tommila, Teemu; Fantoni, Paolo F.; Zander, Ralf M.

1998-02-01

During the past few years an increasing attention has been paid to the safety of shutdown and refuelling operations. It has turned out that the risks during shutdown may be comparable to the risks of power operation. The goal of this report is to identify information requirements related to low power operating modes of nuclear power plants. These include, for example, warm and cold shutdowns, refuelling and maintenance, as well as related state transitions such as start-up and shut-down. The focus of the report is on planned refuelling outages and the role of the control room in managing the outage activities. As a starting point, the basic terminology and characteristics of low power operation are discussed. The current situation at nuclear power plants and some recent developments in information technology are reviewed. End-users' requirements and enabling technologies are combined in order to identify the opportunities for new information technology tools in low power operation. The required features of process control systems and maintenance information systems are described. Common plant modelling techniques, open software architectures and functional structuring of the process control system are suggested to be the key issues in the long-term development of operator support systems. On a shorter time scale, new tools solving limited practical problems should be developed and evaluated. This would provide a basis for the features needed for low power operation, including for example, outage planning, on-line risk monitoring, management of outage tasks, adaptive alarm handling, computerised procedures and task-oriented human interfaces. (author)

All-fiber optical mode switching based on cascaded mode selective couplers for short-reach MDM networks

Science.gov (United States)

Ren, Fang; Li, Juhao; Wu, Zhongying; Yu, Jinyi; Mo, Qi; Wang, Jianping; He, Yongqi; Chen, Zhangyuan; Li, Zhengbin

2017-04-01

We propose and experimentally demonstrate an all-fiber optical mode switching structure supporting independent switching, exchanging, adding, and dropping functionalities in which each mode can be switched individually. The mode switching structure consists of cascaded mode selective couplers (MSCs) capable of exciting and selecting specific higher order modes in few-mode fibers with high efficiency and one multiport optical switch routing the independent spatial modes to their destinations. The data carried on three different spatial modes can be switched, exchanged, added, and dropped through this all-fiber structure. For this experimental demonstration, optical on-off-keying (OOK) signals at 10-Gb/s carried on three spatial modes are successfully processed with open and clear eye diagrams. The mode switch exhibits power penalties of less than 3.1 dB after through operation, less than 2.7 dB after exchange operation, less than 2.8 dB after switching operation, and less than 1.6 dB after mode adding and dropping operations at the bit-error rate (BER) of 10-3, while all three channels carried on three spatial modes are simultaneously routed. The proposed structure, compatible with current optical switching networks based on single-mode fibers, can potentially be used to expand the switching scalability in advanced and flexible short-reach mode-division multiplexing-based networks.

Detectors for alpha particles and X-rays operating in ambient air in pulse counting mode or/and with gas amplification

International Nuclear Information System (INIS)

Charpak, G; Benaben, P; Breuil, P; Peskov, V

2008-01-01

Ionization chambers working in ambient air in current detection mode are attractive due to their simplicity and low cost and are widely used in several applications such as smoke detection, dosimetry, therapeutic beam monitoring and so on. The aim of this work was to investigate if gaseous detectors can operate in ambient air in pulse counting mode as well as with gas amplification which potentially offers the highest possible sensitivity in applications like alpha particle detection or high energy X-ray photon or electron detection. To investigate the feasibility of this method two types of open- end gaseous detectors were build and successfully tested. The first one was a single wire or multiwire cylindrical geometry detector operating in pulse mode at a gas gain of one (pulse ionization chamber). This detector was readout by a custom made wide -band charge sensitive amplifier able to deal with slow induced signals generated by slow motion of negative and positive ions. The multiwire detector was able to detect alpha particles with an efficiency close to 22%. The second type of an alpha detector was an innovative GEM-like detector with resistive electrodes operating in air in avalanche mode at high gas gains (up to 10 4 ). This detector can also operate in a cascaded mode or being combined with other detectors, for example with MICROMEGAS. This detector was readout by a conventional charge -sensitive amplifier and was able to detect alpha particles with 100% efficiency. This detector could also detect X-ray photons or fast electrons. A detailed comparison between these two detectors is given as well as a comparison with commercially available alpha detectors. The main advantages of gaseous detectors operating in air in a pulse detection mode are their simplicity, low cost and high sensitivity. One of the possible applications of these new detectors is alpha particle background monitors which, due to their low cost can find wide application not only in houses, but

Optimal hysteretic control for a BMAP/SM/1/N queue with two operation modes

Directory of Open Access Journals (Sweden)

Alexander N. Dudin

2000-01-01

Full Text Available We consider BMAP/SM/1 type queueing system with finite buffer of size N. The system has two operation modes, which are characterized by the matrix generating function of BMAP-input, the kernel of the semi-Markovian service process, and utilization cost. An algorithm for determining the optimal hysteresis strategy is presented.

Dual-cavity mode converter for a fundamental mode output in an over-moded relativistic backward-wave oscillator

Energy Technology Data Exchange (ETDEWEB)

Li, Jiawei; Huang, Wenhua [Department of Electronic Engineering and Information Science, University of Science and Technology of China, Hefei 230027 (China); Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Xiao, Renzhen; Bai, Xianchen; Zhang, Yuchuan; Zhang, Xiaowei; Shao, Hao; Chen, Changhua [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Zhu, Qi [Department of Electronic Engineering and Information Science, University of Science and Technology of China, Hefei 230027 (China)

2015-03-16

A dual-cavity TM{sub 02}–TM{sub 01} mode converter is designed for a dual-mode operation over-moded relativistic backward-wave oscillator. With the converter, the fundamental mode output is achieved. Particle-in-cell simulation shows that the efficiency of beam-wave conversion was over 46% and a pureTM{sub 01} mode output was obtained. Effects of end reflection provided by the mode converter were studied. Adequate TM{sub 01} mode feedback provided by the converter enhances conversion efficiency. The distance between the mode converter and extraction cavity critically affect the generation of microwaves depending on the reflection phase of TM{sub 01} mode feedback.

Dual-cavity mode converter for a fundamental mode output in an over-moded relativistic backward-wave oscillator

International Nuclear Information System (INIS)

Li, Jiawei; Huang, Wenhua; Xiao, Renzhen; Bai, Xianchen; Zhang, Yuchuan; Zhang, Xiaowei; Shao, Hao; Chen, Changhua; Zhu, Qi

2015-01-01

A dual-cavity TM 02 –TM 01 mode converter is designed for a dual-mode operation over-moded relativistic backward-wave oscillator. With the converter, the fundamental mode output is achieved. Particle-in-cell simulation shows that the efficiency of beam-wave conversion was over 46% and a pureTM 01 mode output was obtained. Effects of end reflection provided by the mode converter were studied. Adequate TM 01 mode feedback provided by the converter enhances conversion efficiency. The distance between the mode converter and extraction cavity critically affect the generation of microwaves depending on the reflection phase of TM 01 mode feedback

Constant-frequency, clamped-mode resonant converters

Science.gov (United States)

Tsai, Fu-Sheng; Materu, Peter; Lee, Fred C.

1987-01-01

Two novel clamped-mode resonant converters are proposed which operate at a constant frequency while retaining many desired features of conventional series- and parallel-resonant converters. State-plane analysis techniques are used to identify all possible operating modes and define their mode boundaries. Control-to-output characteristics are derived that specify the regions for natural and forced commutation. The predicted operating modes are verified using a prototype circuit.

PF-KO system for single bunch mode operation of a storage ring

International Nuclear Information System (INIS)

Ohgaki, H.; Sugiyama, S.; Mikado, T.; Chiwaki, M.; Yamada, K.; Suzuki, R.; Sei, N.; Noguchi, T.; Yamazaki, T.

1994-01-01

A new RF-KO (RF knockout) system for the single bunch mode operation of a storage ring has been developed. The knockout signal is modulated by the sum signal of the RF acceleration frequency of the storage ring and a bunch selection signal. We do not need any special device or a timing unit with this method. We obtain a high purity of bunch structure in a short knock out time. The single bunch impurity of 0.2% has been achieved. (author)

Current distribution measurements inside an electromagnetic plasma gun operated in a gas-puff mode.

Science.gov (United States)

Poehlmann, Flavio R; Cappelli, Mark A; Rieker, Gregory B

2010-12-01

Measurements are presented of the time-dependent current distribution inside a coaxial electromagnetic plasma gun. The measurements are carried out using an array of six axially distributed dual-Rogowski coils in a balanced circuit configuration. The radial current distributions indicate that operation in the gas-puff mode, i.e., the mode in which the electrode voltage is applied before injection of the gas, results in a stationary ionization front consistent with the presence of a plasma deflagration. The effects of varying the bank capacitance, transmission line inductance, and applied electrode voltage were studied over the range from 14 to 112 μF, 50 to 200 nH, and 1 to 3 kV, respectively.

Adaptive Droop Control Applied to Voltage-Source Inverters Operating in Grid-Connected and Islanded Modes

DEFF Research Database (Denmark)

Vasquez, J. C.; Guerrero, J. M.; Luna, A.

2009-01-01

This paper proposes a novel control for voltagesource inverters with the capability to flexibly operate in gridconnected and islanded modes. The control scheme is based on the droop method, which uses some estimated grid parameters such as the voltage and frequency and the magnitude and angle of ...

The formation of liquid bridge in different operating modes of AFM

Science.gov (United States)

Wei, Zheng; Sun, Yan; Ding, WenXuan; Wang, ZaiRan

2016-09-01

The liquid bridge is one of the principal factors that cause artifacts in ambient-pressure atomic force microscope (AFM) images. Additionally, it is the main component of the adhesion force in ambient conditions. To understand the AFM imaging mechanism and the sample characteristics, it is essential to study the liquid bridge. This study interprets the physical mechanism involved in liquid bridge formation, which is composed of three different physical processes: the squeezing process, capillary condensation, and liquid film flow. We discuss the contributions of these three mechanisms to the volume and the capillary force of the liquid bridge in different AFM operation modes.

Experimental investigation of limit space charge accumulation mode operation in a semi-insulating GaAs photoconductive semiconductor switch

International Nuclear Information System (INIS)

Ma Xiangrong; Shi Wei; Xiang Mei

2013-01-01

Experiments with the limited space-charge accumulation (LSA) mode of oscillation in a large gap semi-insulating (SI) GaAs photoconductive semiconductor switch (PCSS) are discussed. It has been observed that growth and drift of a photo-activated charge domain (PACD) are quenched only when the bias voltage is more than twice the threshold voltage. The original negative resistance characteristics are directly utilized in the LSA mode; during LSA operation the spatial average of the electric field varies over a large portion of the negative differential mobility region of the velocity—electric field characteristic. The work efficiency of an SI GaAs PCSS is remarkably enhanced by electric field excursions into the positive resistance region when the total electric field is only below the threshold part of the time. The LSA mode can only operate in the certain conditions that satisfy the quenching of the accumulation layer and the smaller initial domain voltage. (semiconductor devices)

PLC-based mode multi/demultiplexers for mode division multiplexing

Science.gov (United States)

Saitoh, Kunimasa; Hanzawa, Nobutomo; Sakamoto, Taiji; Fujisawa, Takeshi; Yamashita, Yoko; Matsui, Takashi; Tsujikawa, Kyozo; Nakajima, Kazuhide

2017-02-01

Recently developed PLC-based mode multi/demultiplexers (MUX/DEMUXs) for mode division multiplexing (MDM) transmission are reviewed. We firstly show the operation principle and basic characteristics of PLC-based MUX/DEMUXs with an asymmetric directional coupler (ADC). We then demonstrate the 3-mode (2LP-mode) multiplexing of the LP01, LP11a, and LP11b modes by using fabricated PLC-based mode MUX/DEMUX on one chip. In order to excite LP11b mode in the same plane, a PLC-based LP11 mode rotator is introduced. Finally, we show the PLC-based 6-mode (4LP-mode) MUX/DEMUX with a uniform height by using ADCs, LP11 mode rotators, and tapered waveguides. It is shown that the LP21a mode can be excited from the LP11b mode by using ADC, and the two nearly degenerated LP21b and LP02 modes can be (de)multiplexed separately by using tapered mode converter from E13 (E31) mode to LP21b (LP02) mode.

Effect of low density H-mode operation on edge and divertor plasma parameters

International Nuclear Information System (INIS)

Maingi, R.; Mioduszewski, P.K.; Cuthbertson, J.W.

1994-07-01

We present a study of the impact of H-mode operation at low density on divertor plasma parameters on the DIII-D tokamak. The line-average density in H-mode was scanned by variation of the particle exhaust rate, using the recently installed divertor cryo-condensation pump. The maximum decrease (50%) in line-average electron density was accompanied by a factor of 2 increase in the edge electron temperature, and 10% and 20% reductions in the measured core and divertor radiated power, respectively. The measured total power to the inboard divertor target increased by a factor of 3, with the major contribution coming from a factor of 5 increase in the peak heat flux very close to the inner strike point. The measured increase in power at the inboard divertor target was approximately equal to the measured decrease in core and divertor radiation

Dual-Mode Scramjet Flameholding Operability Measurements

Science.gov (United States)

Donohue, James M.

2012-01-01

Flameholding measurements were made in two different direct connect combustor facilities that were designed to simulate a cavity flameholder in the flowfield of a hydrocarbon fueled dual-mode scramjet combustor. The presence of a shocktrain upstream of the flameholder has a significant impact on the inlet flow to the combustor and on the flameholding limits. A throttle was installed in the downstream end of the test rigs to provide the needed back-pressurization and decouple the operation of the flameholder from the backpressure formed by heat release and thermal choking, as in a flight engine. Measurements were made primarily with ethylene fuel but a limited number of tests were also performed with heated gaseous JP-7 fuel injection. The flameholding limits were measured by ramping inlet air temperature down until blowout was observed. The tests performed in the United Technologies Research Center (UTRC) facility used a hydrogen fueled vitiated air heater, Mach 2.2 and 3.3 inlet nozzles, a scramjet combustor rig with a 1.666 by 6 inch inlet and a 0.65 inch deep cavity. Mean blowout temperature measured at the baseline condition with ethylene fuel, the Mach 2.2 inlet and a cavity pressure of 21 psia was 1502 oR. Flameholding sensitivity to a variety of parameters was assessed. Blowout temperature was found to be most sensitive to fuel injection location and fuel flowrates and surprisingly insensitive to operating pressure (by varying both back-pressurization and inlet flowrate) and inlet Mach number. Video imaging through both the bottom and side wall windows was collected simultaneously and showed that the flame structure was quite unsteady with significant lateral movements as well as movement upstream of the flameholder. Experiments in the University of Virginia (UVa) test facility used a Mach 2 inlet nozzle with a 1 inch by 1.5 inch exit cross section, an aspect ratio of 1.5 versus 3.6 in the UTRC facility. The UVa facility tests were designed to measure the

Passively mode-locked 4.6 and 10.5 GHz quantum dot laser diodes around 1.55 μm with large operating regime

NARCIS (Netherlands)

Heck, M.J.R.; Renault, A.; Bente, E.A.J.M.; Oei, Y.S.; Smit, M.K.; Eikema, K.S.E.; Ubachs, W.; Anantathanasarn, S.; Nötzel, R.

2009-01-01

Passive mode-locking in two-section InAs/InP quantum dot laser diodes operating at wavelengths around 1.55 µm is reported. For a 4.6-GHz laser, a large operating regime of stable mode-locking, with RF-peak heights of over 40 dB, is found for injection currents of 750 mA up to 1.0 A and for values of

Comparative Analysis of Battery Behavior with Different Modes of Discharge for Optimal Capacity Sizing and BMS Operation

OpenAIRE

Mazhar Abbas; Eung-sang Kim; Seul-ki Kim; Yun-su Kim

2016-01-01

Battery-operated systems are always concerned about the proper management and sizing of a battery. A Traditional Battery Management System (BMS) only includes battery-aware task scheduling based on the discharge characteristics of a whole battery pack and do not take into account the mode of the load being served by the battery. On the other hand, an efficient and intelligent BMS should monitor the battery at a cell level and track the load with significant consideration of the load mode. Dep...

An analysis of the binding of repressor protein ModE to modABCD (molybdate transport) operator/promoter DNA of Escherichia coli.

Science.gov (United States)

Grunden, A M; Self, W T; Villain, M; Blalock, J E; Shanmugam, K T

1999-08-20

Expression of the modABCD operon in Escherichia coli, which codes for a molybdate-specific transporter, is repressed by ModE in vivo in a molybdate-dependent fashion. In vitro DNase I-footprinting experiments identified three distinct regions of protection by ModE-molybdate on the modA operator/promoter DNA, GTTATATT (-15 to -8; region 1), GCCTACAT (-4 to +4; region 2), and GTTACAT (+8 to +14; region 3). Within the three regions of the protected DNA, a pentamer sequence, TAYAT (Y = C or T), can be identified. DNA-electrophoretic mobility experiments showed that the protected regions 1 and 2 are essential for binding of ModE-molybdate to DNA, whereas the protected region 3 increases the affinity of the DNA to the repressor. The stoichiometry of this interaction was found to be two ModE-molybdate per modA operator DNA. ModE-molybdate at 5 nM completely protected the modABCD operator/promoter DNA from DNase I-catalyzed hydrolysis, whereas ModE alone failed to protect the DNA even at 100 nM. The apparent K(d) for the interaction between the modA operator DNA and ModE-molybdate was 0.3 nM, and the K(d) increased to 8 nM in the absence of molybdate. Among the various oxyanions tested, only tungstate replaced molybdate in the repression of modA by ModE, but the affinity of ModE-tungstate for modABCD operator DNA was 6 times lower than with ModE-molybdate. A mutant ModE(T125I) protein, which repressed modA-lac even in the absence of molybdate, protected the same region of modA operator DNA in the absence of molybdate. The apparent K(d) for the interaction between modA operator DNA and ModE(T125I) was 3 nM in the presence of molybdate and 4 nM without molybdate. The binding of molybdate to ModE resulted in a decrease in fluorescence emission, indicating a conformational change of the protein upon molybdate binding. The fluorescence emission spectra of mutant ModE proteins, ModE(T125I) and ModE(Q216*), were unaffected by molybdate. The molybdate-independent mutant ModE

The acetone bandpass detector for inverse photoemission: operation in proportional and Geiger–Müller modes

Science.gov (United States)

Thiede, Christian; Niehues, Iris; Schmidt, Anke B.; Donath, Markus

2018-06-01

Inverse photoemission is the most versatile experimental tool to study the unoccupied electronic structure at surfaces of solids. Typically, the experiments are performed in the isochromat mode with bandpass photon detectors. For gas-filled counters, the bandpass behavior is realized by the combination of the photoionization threshold of the counting gas as the high-pass filter and the ultraviolet transmission cutoff of an alkaline earth fluoride entrance window as the low-pass filter. The transmission characteristics of the entrance window determine the optical bandpass. The performance of the counter depends on the composition of the detection gas and the fill-gas pressure, the readout electronics and the counter geometry. For the well-known combination of acetone and CaF2, the detector can be operated in proportional and Geiger–Müller modes. In this work, we review aspects concerning the working principles, the counter construction and the read-out electronics. We identify optimum working parameters and provide a step-by-step recipe how to build, install and operate the device.

Selection of stirling engine parameter and modes of joint operation with the Topaz II

International Nuclear Information System (INIS)

Kirillov, E.Y.; Ogloblin, B.G.; Shalaev, A.I.

1996-01-01

In addition to a high-temperature thermionic conversion cycle, application of a low-temperature machine cycle, such as the Stirling engine, is being considered. To select the optimum mode for joint operation of the Topaz II system and Stirling engine, output electric parameters are obtained as a function of thermal power released in the TFE fuel cores. The hydraulic diagram used for joint operation of the Topaz II and the Stirling engine is considered. Requirements to hydraulic characteristics of the Stirling engine heat exchanges are formulated. Scope of necessary modifications to mount the Stirling Engine on the Topaz II is estimated. copyright 1996 American Institute of Physics

Compressed modes for variational problems in mathematical physics and compactly supported multiresolution basis for the Laplace operator

Science.gov (United States)

Ozolins, Vidvuds; Lai, Rongjie; Caflisch, Russel; Osher, Stanley

2014-03-01

We will describe a general formalism for obtaining spatially localized (``sparse'') solutions to a class of problems in mathematical physics, which can be recast as variational optimization problems, such as the important case of Schrödinger's equation in quantum mechanics. Sparsity is achieved by adding an L1 regularization term to the variational principle, which is shown to yield solutions with compact support (``compressed modes''). Linear combinations of these modes approximate the eigenvalue spectrum and eigenfunctions in a systematically improvable manner, and the localization properties of compressed modes make them an attractive choice for use with efficient numerical algorithms that scale linearly with the problem size. In addition, we introduce an L1 regularized variational framework for developing a spatially localized basis, compressed plane waves (CPWs), that spans the eigenspace of a differential operator, for instance, the Laplace operator. Our approach generalizes the concept of plane waves to an orthogonal real-space basis with multiresolution capabilities. Supported by NSF Award DMR-1106024 (VO), DOE Contract No. DE-FG02-05ER25710 (RC) and ONR Grant No. N00014-11-1-719 (SO).

Squeeze strengthening of magnetorheological fluids using mixed mode operation

Science.gov (United States)

Becnel, A. C.; Sherman, S. G.; Hu, W.; Wereley, N. M.

2015-05-01

This research details a novel method of increasing the shear yield stress of magnetorheological fluids by combining shear and squeeze modes of operation to manipulate particle chain structures, so-called squeeze strengthening. Using a custom built Searle cell magnetorheometer, which is a model device emulating a rotary magnetorheological energy absorber (MREA), the contribution of squeeze strengthening to the total controllable yield force is experimentally investigated. Using an eccentric rotating inner cylinder, characterization data from large (1 mm) and small (0.25 mm) nominal gap geometries are compared to investigate the squeeze strengthening effect. Details of the experimental setup and method are presented, and a hybrid model is used to explain experimental trends. This study demonstrates that it is feasible, utilizing squeeze strengthening to increase yield stress, to either (1) design a rotary MREA of a given volume to achieve higher energy absorption density (energy absorbed normalized by active fluid volume), or (2) reduce the volume of a given rotary MREA to achieve the same energy absorption density.

Mode-locking operation of a flash-lamp-pumped Nd:YAG laser at 1.064 μm with Zakharov-Manakov solitons

International Nuclear Information System (INIS)

Andreana, M; Tonello, A; Couderc, V; Baronio, F; Conforti, M; De Angelis, C

2011-01-01

We report experimental results on the mode-locked operation of a flash-lamp-pumped Nd:YAG laser at 1.064 μm. The KTP crystal, which induces passive mode-locking, exploits the existence and properties of spatial Zakharov-Manakov soliton dynamics. A train of pulses with duration close to 100 ps, repetition rate of 136 MHz and modulation depth almost 100% has been produced. The mode-locked pulses are modulated with a longer 180 ns pulse envelope with repetition rate of 10 Hz

A comparison of co-current and counter-current modes of operation for a novel hydrogen-permselective membrane dual-type FTS reactor in GTL technology

Energy Technology Data Exchange (ETDEWEB)

Rahimpour, M.R.; Forghani, A.A.; Mostafazadeh, A. Khosravanipour; Shariati, A. [Chemical Engineering Department, School of Chemical and Petroleum Engineering, Shiraz University, Shiraz 71345 (Iran)

2010-01-15

In this work, a comparison of co-current and counter-current modes of operation for a novel hydrogen-permselective membrane reactor for Fischer-Tropsch Synthesis (FTS) has been carried out. In both modes of operations, a system with two-catalyst bed instead of one single catalyst bed is developed for FTS reactions. In the first catalytic reactor, the synthesis gas is partly converted to products in a conventional water-cooled fixed-bed reactor, while in the second reactor which is a membrane fixed-bed reactor, the FTS reactions are completed and heat of reaction is used to preheat the feed synthesis gas to the first reactor. In the co-current mode, feed gas is entered into the tubes of the second reactor in the same direction with the reacting gas stream in shell side while in the counter-current mode the gas streams are in the opposite direction. Simulation results for both co-current and counter-current modes have been compared in terms of temperature, gasoline and CO{sub 2} yields, H{sub 2} and CO conversion, selectivity of components as well as permeation rate of hydrogen through the membrane. The results showed that the reactor in the co-current configuration operates with lower conversion and lower permeation rate of hydrogen, but it has more favorable profile of temperature. The counter-current mode of operation decreases undesired products such as CO{sub 2} and CH{sub 4} and also produces more gasoline. (author)

Discovery of multiple, ionization-created CS2 anions and a new mode of operation for drift chambers

International Nuclear Information System (INIS)

Snowden-Ifft, Daniel P.

2014-01-01

This paper focuses on the surprising discovery of multiple species of ionization-created CS 2 anions in gas mixtures containing electronegative CS 2 and O 2 , identified by their slightly different drift velocities. Data are presented to understand the formation mechanism and identity of these new anions. Regardless of the micro-physics, however, this discovery offers a new, trigger-less mode of operation for the drift chambers. A demonstration of trigger-less operation is presented

Study on the operation mode for indigenization and standardization of AP1000 technology

International Nuclear Information System (INIS)

Gao Zhihu; Cheng Huiping

2014-01-01

This paper describes the importance and necessity of developing standardized AP1000 technology, and analyzes the problems faced and measures to be taken. The operation mode, known as the Committee of AP1000 Standardized Design and Innovation Management, was first put forward in China. And the paper also discusses how to arouse the enthusiasm of the owners, designers, manufactures, as well as construction, installation, regulation and other parties, how to exploit the advantage of whole industry to promote the localization and standardization of AP1000 technology. (authors)

VH mode accessibility and global H-mode properties in previous and present JET configurations

Energy Technology Data Exchange (ETDEWEB)

Jones, T T.C.; Ali-Arshad, S; Bures, M; Christiansen, J P; Esch, H P.L. de; Fishpool, G; Jarvis, O N; Koenig, R; Lawson, K D; Lomas, P J; Marcus, F B; Sartori, R; Schunke, B; Smeulders, P; Stork, D; Taroni, A; Thomas, P R; Thomsen, K [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

1994-07-01

In JET VH modes, there is a distinct confinement transition following the cessation of ELMs, observed in a wide variety of tokamak operating conditions, using both NBI and ICRF heating methods. Important factors which influence VH mode accessibility such as magnetic configuration and vessel conditions have been identified. The new JET pumped divertor configuration has much improved plasma shaping control and power and particle exhaust capability and should permit exploitation of plasmas with VH confinement properties over an even wider range of operating regimes, particularly at high plasma current; first H-modes have been obtained in the 1994 JET operating period and initial results are reported. (authors). 7 refs., 6 figs.

A square-plate piezoelectric linear motor operating in two orthogonal and isomorphic face-diagonal-bending modes.

Science.gov (United States)

Ci, Penghong; Chen, Zhijiang; Liu, Guoxi; Dong, Shuxiang

2014-01-01

We report a piezoelectric linear motor made of a single Pb(Zr,Ti)O3 square-plate, which operates in two orthogonal and isomorphic face-diagonal-bending modes to produce precision linear motion. A 15 × 15 × 2 mm prototype was fabricated, and the motor generated a driving force of up to 1.8 N and a speed of 170 mm/s under an applied voltage of 100 Vpp at the resonance frequency of 136.5 kHz. The motor shows such advantages as large driving force under relatively low driving voltage, simple structure, and stable motion because of its isomorphic face-diagonal-bending mode.

Local and global performance of double-gap resistive plate chambers operated in avalanche mode

Energy Technology Data Exchange (ETDEWEB)

Abbrescia, M.; Colaleo, A.; Iaselli, G.; Loddo, F.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Pugliese, G.; Ranieri, A.; Romano, F.; Altieri, S.; Belli, G.; Bruno, G.; Gianini, G.; Ratti, S.P.; Viola, L.; Vitulo, P.; Sergueev, S

1999-09-21

Two large double-gap resistive plate chambers, with 2 and 3 mm gap widths, were tested to study their response uniformity when operated in avalanche mode. The effects of mechanical tolerances and the presence of the spacers is thoroughly examined. Results on efficiency and time resolution are presented. We find that average performance and response uniformity over the whole chamber surface are fully adequate to the requirements of future collider experiments. (author)

The Effects of 10 Communication Modes on the Behavior of Teams During Co-Operative Problem-Solving

Science.gov (United States)

Ochsman, Richard B.; Chapanis, Alphonse

1974-01-01

Sixty teams of two college students each solved credible "real world" problems co-operatively. Conversations were carried on in one of 10 modes of communication: (1) typewriting only, (2) handwriting only, (3) handwriting and typewriting, (4) typewriting and video, (5) handwriting and video, (6) voice only, (7) voice and typewriting, (8) voice and…

A novel current mode operating beam counter based on not preamplified HPDs

CERN Document Server

Fujiwara, M.C.

2002-01-01

A novel system to monitor the intensity and the stability of a bunched beam of $\\simeq 1.2\\times 10^{7}$ antiprotons ($\\bar{p}$s) with a length of $\\simeq$ 250 ns (FWHM) and to measure its trapping efficiency in a Penning trap is described. This system operates parasitically detecting the pions from the annihilation of part of the beam in a degrader. Six plastic scintillators have been coupled from one side to six proximity focused HPDs without preamplifiers and operating in current mode. This device works in the stray field of the ATHENA magnet with no loss of efficiency; the gain can be varied from zero to a few thousands with a precision better than 0.1% and the dynamic range is larger than 8 orders of magnitude. Linearity and stability have been measured up to charge responses of 100 nC, corresponding to the beam completely dumped. The beam counter has been calibrated in two different and independent ways giving consistent results.

The Thermal State Computational Research of the Low-Thrust Oxygen-Methane Gaseous-Propellant Rocket Engine in the Pulse Mode of Operation

Directory of Open Access Journals (Sweden)

O. A. Vorozheeva

2014-01-01

Full Text Available Currently promising development direction of space propulsion engineering is to use, as spacecraft controls, low-thrust rocket engines (RDTM on clean fuels, such as oxygen-methane. Modern RDTM are characterized by a lack regenerative cooling and pulse mode of operation, during which there is accumulation of heat energy to lead to the high thermal stress of RDTM structural elements. To get an idea about the thermal state of its elements, which further will reduce the number of fire tests is therefore necessary in the development phase of a new product. Accordingly, the aim of this work is the mathematical modeling and computational study of the thermal state of gaseous oxygen-methane propellant RDMT operating in pulse mode.In this paper we consider a model RDTM working on gaseous propellants oxygen-methane in pulse mode.To calculate the temperature field of the chamber wall of model RDMT under consideration is used the mathematical model of non-stationary heat conduction in a two-dimensional axisymmetric formulation that takes into account both the axial heat leakages and the nonstationary processes occurring inside the chamber during pulse operation of RDMT.As a result of numerical study of the thermal state of model RDMT, are obtained the temperature fields during engine operation based on convective, conductive, and radiative mechanisms of heat transfer from the combustion products to the wall.It is shown that the elements of flanges of combustion chamber of model RDMT act as heat sinks structural elements. Temperatures in the wall of the combustion chamber during the engine mode of operation are considered relatively low.Raised temperatures can also occur in the mixing head in the feeding area of the oxidant into the combustion chamber.During engine operation in the area forming the critical section, there is an intensive heating of a wall, which can result in its melting, which in turn will increase the minimum nozzle throat area and hence

Improvement of the reliability graph with general gates to analyze the reliability of dynamic systems that have various operation modes

Energy Technology Data Exchange (ETDEWEB)

Shin, Seung Ki [Div. of Research Reactor System Design, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); No, Young Gyu; Seong, Poong Hyun [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

2016-04-15

The safety of nuclear power plants is analyzed by a probabilistic risk assessment, and the fault tree analysis is the most widely used method for a risk assessment with the event tree analysis. One of the well-known disadvantages of the fault tree is that drawing a fault tree for a complex system is a very cumbersome task. Thus, several graphical modeling methods have been proposed for the convenient and intuitive modeling of complex systems. In this paper, the reliability graph with general gates (RGGG) method, one of the intuitive graphical modeling methods based on Bayesian networks, is improved for the reliability analyses of dynamic systems that have various operation modes with time. A reliability matrix is proposed and it is explained how to utilize the reliability matrix in the RGGG for various cases of operation mode changes. The proposed RGGG with a reliability matrix provides a convenient and intuitive modeling of various operation modes of complex systems, and can also be utilized with dynamic nodes that analyze the failure sequences of subcomponents. The combinatorial use of a reliability matrix with dynamic nodes is illustrated through an application to a shutdown cooling system in a nuclear power plant.

Improvement of the reliability graph with general gates to analyze the reliability of dynamic systems that have various operation modes

International Nuclear Information System (INIS)

Shin, Seung Ki; No, Young Gyu; Seong, Poong Hyun

2016-01-01

The safety of nuclear power plants is analyzed by a probabilistic risk assessment, and the fault tree analysis is the most widely used method for a risk assessment with the event tree analysis. One of the well-known disadvantages of the fault tree is that drawing a fault tree for a complex system is a very cumbersome task. Thus, several graphical modeling methods have been proposed for the convenient and intuitive modeling of complex systems. In this paper, the reliability graph with general gates (RGGG) method, one of the intuitive graphical modeling methods based on Bayesian networks, is improved for the reliability analyses of dynamic systems that have various operation modes with time. A reliability matrix is proposed and it is explained how to utilize the reliability matrix in the RGGG for various cases of operation mode changes. The proposed RGGG with a reliability matrix provides a convenient and intuitive modeling of various operation modes of complex systems, and can also be utilized with dynamic nodes that analyze the failure sequences of subcomponents. The combinatorial use of a reliability matrix with dynamic nodes is illustrated through an application to a shutdown cooling system in a nuclear power plant

Comparative economic efficiency, operating costs and fuel consumption rates of freight transport modes between the largest industrial cities and seaports in South Africa

Directory of Open Access Journals (Sweden)

W J (Wessel Pienaar

2013-09-01

Full Text Available The paper deals with aspects of efficiency within the five modes of freight transport, with special reference to the operating cost and fuel consumption rates between South Africa’s largest industrial cities and seaports. In particular, the paper deals with (a the opportunities that exist for the achievement of efficiency in freight transport; (b the subgroups of economies that can enhance efficiency attainment in the freight transport industry; (c prevailing cost structures, operating cost and fuel consumption rates within the five modes of freight transport; and (d the salient economic features of the freight transport market. The research approach and methodology combine (a a literature survey; (b empiric research, (c an analysis of the cost structures of freight transport operators from different modes of transport; and (d interviews conducted with specialists in the freight transport industry.

Testing to expand the rotary-mode core sampling system operating envelope

International Nuclear Information System (INIS)

Witwer, K.S.

1998-01-01

Rotary sampling using the Rotary Mode Core Sampling System (RMCSS) is constrained by what is referred to as the ''Operating Envelope''. The Operating Envelop defines the maximum downward force, maximum rotational speed and minimum purge gas flow allowed during operation of the RMCSS. The original values of 1170 lb. down force, 55 RPM rotational speed, and 30 SCFM nitrogen purge gas were determined during original envelope testing. This envelope was determined by observing the temperature rise on the bitface while drilling into waste simulants. The maximum temperature in single-shell tanks (SSTS) is considered to be approximately 9O C and the critical drill bit temperature, which is the temperature at which an exothermic reaction could be initiated in the tank waste, was previously determined to be 150 C. Thus, the drill bit temperature increase was limited to 60 C. Thermal properties of these simulants approximated typical properties of waste tank saltcake. Later, more detailed envelope testing which used a pumice block simulant, showed a notably higher temperature rise while drilling. This pumice material, which simulated a ''worst case'' foreign object embedded in the waste, has lower thermal conductivity and lower thermal diffusivity than earlier simulants. These properties caused a slower heat transfer in the pumice than in the previous simulants and consequently a higher temperature rise. The maximum downward force was subsequently reduced to 750 lb (at a maximum 55 RPM and minimum 30 SCFM purge gas flow) which was the maximum value at which the drill bit could be operated and still remain below the 60 C temperature rise

INTEGRAL INDEX OF OPERATION QUALITY FOR EVALUATION OF IMPACT OF DISTRIBUTIVE GENERATION SOURCES ON ELECTRIC NETWORK MODES

Directory of Open Access Journals (Sweden)

Petro D. Lezhniuk

2017-06-01

Full Text Available Method of operation quality evaluation of electric network, comprising renewable sources of energy (RSE is considered. Integral index that enables to evaluate the impact of RSE on energy losses and its quality as well as balance reliability in electric network is suggested. Mathematical model is constructed, taking into account the assumption that electric network with RSE may be in various operation modes, characterized by different technical economic indices. To determine the integral index of operation quality of electric network with RSE in all possible states tools of Markov processes theory and criterial method are used.

An evaluation of effects of large-scale introduction of renewable power on capacities and operation modes of power generation systems in Japan

International Nuclear Information System (INIS)

Yamamoto, Hiromi; Yabe, Kuniaki; Bando, Shigeru; Nagai, Yu

2014-01-01

This study aims to establish a methodology to adequately evaluate an optimal power generation mix in Japan taking into account load frequency control (LFC) capacity and operation modes of power plants in case of a large-scale introduction of photovoltaic and wind power. For this purpose, the authors gave such an improvement to the MM-OPG model, a power generation mix optimization model, which it can deal with different operation modes of pumped hydro power in addition to those of thermal power sources. Using the model, the authors calculated the optimal power generation mix and its corresponding operation modes of Japan's power systems in 2030 with additional insights to 2020, and obtained the following results. (1) Introduction of photovoltaic and wind can be substituted for a limited capacity of conventional power sources. The introduction of 150 GW that consists of 108GW of photovoltaic and 42GW of wind in 2030 can replace no greater than 0.5 GW of conventional power sources. (2) The introduction of the renewables will affect the operation patterns of thermal and pumped hydro power generation. The capacity factor of variable speed pumped hydro will be much greater than that of fixed speed pumped hydro since the former can supply LFC at pump modes as well as generation modes. The capacity factor of LNG combined cycle plants decreases from 43% to 29% in the case with the introduction of 150GW of renewables in 2030. On the same assumption, the average cost of power generation excluding the renewables increases by up to 0.55 JPY/kWh in 2030. (author)

Low-timing-jitter, stretched-pulse passively mode-locked fiber laser with tunable repetition rate and high operation stability

International Nuclear Information System (INIS)

Liu, Yuanshan; Zhang, Jian-Guo; Chen, Guofu; Zhao, Wei; Bai, Jing

2010-01-01

We design a low-timing-jitter, repetition-rate-tunable, stretched-pulse passively mode-locked fiber laser by using a nonlinear amplifying loop mirror (NALM), a semiconductor saturable absorber mirror (SESAM), and a tunable optical delay line in the laser configuration. Low-timing-jitter optical pulses are stably produced when a SESAM and a 0.16 m dispersion compensation fiber are employed in the laser cavity. By inserting a tunable optical delay line between NALM and SESAM, the variable repetition-rate operation of a self-starting, passively mode-locked fiber laser is successfully demonstrated over a range from 49.65 to 50.47 MHz. The experimental results show that the newly designed fiber laser can maintain the mode locking at the pumping power of 160 mW to stably generate periodic optical pulses with width less than 170 fs and timing jitter lower than 75 fs in the 1.55 µm wavelength region, when the fundamental repetition rate of the laser is continuously tuned between 49.65 and 50.47 MHz. Moreover, this fiber laser has a feature of turn-key operation with high repeatability of its fundamental repetition rate in practice

Production of structured lipids by acidolysis of an EPA-enriched fish oil and caprylic acid in a packed bed reactor: analysis of three different operation modes.

Science.gov (United States)

González Moreno, P A; Robles Medina, A; Camacho Rubio, F; Camacho Páez, B; Molina Grima, E

2004-01-01

Structured triacylglycerols (ST) enriched in eicosapentaenoic acid (EPA) in position 2 of the triacylglycerol (TAG) backbone were synthesized by acidolysis of a commercially available EPA-rich oil (EPAX4510, 40% EPA) and caprylic acid (CA), catalyzed by the 1,3-specific immobilized lipase Lipozyme IM. The reaction was carried out in a packed bed reactor (PBR) operating in two ways: (1) by recirculating the reaction mixture from the exit of the bed to the substrate reservoir (discontinuous mode) and (2) in continuous mode, directing the product mixture leaving the PBR to a product reservoir. By operating in these two ways and using a simple kinetic model, representative values for the apparent kinetic constants (kX) for each fatty acid (native, Li or odd, M) were obtained. The kinetic model assumes that the rate of incorporation of a fatty acid into TAG per amount of enzyme, rX (mole/(h g lipase)) is proportional to the extent of the deviation from the equilibrium for each fatty acid (i.e., the difference of concentration between the fatty acid in the triacylglycerol and the concentration of the same fatty acid in the triacylglycerol once the equilibrium of the acidolysis reaction is reached). The model allows comparing the two operating modes through the processing intensity, defined as mLt/(V[TG]0) and mL/(q[TG]0), for the discontinuous and continuous operation modes, respectively. In discontinuous mode, ST with 59.5% CA and 9.6% EPA were obtained. In contrast, a ST with 51% CA and 19.6% EPA were obtained when using the continuous operation mode. To enhance the CA incorporation when operating in continuous mode, a two-step acidolysis reaction was performed (third operation mode). This continuous two-step process yields a ST with a 64% CA and a 15% EPA. Finally, after purifying the above ST in a preparative silica gel column, impregnated with boric acid, a ST with 66.9% CA and 19.6% EPA was obtained. The analysis by reverse phase and Ag+ liquid chromatography of

High-power LED light sources for optical measurement systems operated in continuous and overdriven pulsed modes

Science.gov (United States)

Stasicki, Bolesław; Schröder, Andreas; Boden, Fritz; Ludwikowski, Krzysztof

2017-06-01

The rapid progress of light emitting diode (LED) technology has recently resulted in the availability of high power devices with unprecedented light emission intensities comparable to those of visible laser light sources. On this basis two versatile devices have been developed, constructed and tested. The first one is a high-power, single-LED illuminator equipped with exchangeable projection lenses providing a homogenous light spot of defined diameter. The second device is a multi-LED illuminator array consisting of a number of high-power LEDs, each integrated with a separate collimating lens. These devices can emit R, G, CG, B, UV or white light and can be operated in pulsed or continuous wave (CW) mode. Using an external trigger signal they can be easily synchronized with cameras or other devices. The mode of operation and all parameters can be controlled by software. Various experiments have shown that these devices have become a versatile and competitive alternative to laser and xenon lamp based light sources. The principle, design, achieved performances and application examples are given in this paper.

Sloshing motion dynamics of a free surface in the draft tube cone of a Francis turbine operating in synchronous condenser mode

Science.gov (United States)

Vagnoni, Elena; Andolfatto, Loïc; Favrel, Arthur; Avellan, François

2016-11-01

The penetration of the electrical grid by intermittent renewable energy sources induces grid fluctuations which must be compensated in order to guarantee the stability of the grid. Hydropower plants can supply reactive power to ensure the grid stabilization by operating in condenser mode. In this operating mode, the turbine operates with the tail water depressed to let the runner spin in air to reduce the power consumption. Pressurized air is injected in the draft tube cone to maintain the water level below the runner and this induces air-water interaction phenomena which cause important power losses. Flow visualization and pressure fluctuation measurements are performed in a reduced scale physical model of a Francis turbine operating in condenser mode to investigate the dynamics of the air-water interaction in the draft tube cone which causes the sloshing motion of the free surface. An image post-processing method is developed, enabling a quantitative description of the sloshing motion. The latter depends on the Froude number. By increasing the value of the Froude number, the amplitude of the sloshing motion decreases, as well as the amplitude of the pressure fluctuations. The frequency of the sloshing motion corresponds to the first natural frequency of the water volume.

Safety analysis for push-mode and rotary-mode core sampling

International Nuclear Information System (INIS)

Milliken, N.J.; Geschke, G.R.

1995-01-01

This safety analysis analyzes using the push-mode core sampling truck in the push-mode and the rotary-mode core sampling trucks in both the push- and rotary-modes to retrieve core samples that, once taken and analyzed, will yield waste characterization data for the hazardous waste tanks at the Hanford Site. Operation of the core sampling trucks in both the push- and rotary-modes was reviewed to determine whether the release of radioactive materials could occur during operation. It was concluded that there are three credible scenarios: a sample spill outside of the tank, a steam release event, and an unfiltered release to the environment during continuous exhauster operation. The probability of a sample spill was found to be 10 -4 /event, the probability of a steam release event was determined to fall in the unlikely range (10 -2 /event to 10 -4 /event), and the probability of an unfiltered release was calculated to be 5 x 10 -3 /year. Typically, events with probabilities of 10 -6 /event or less are not considered to be risk significant, and the consequences usually are not analyzed. The three accident scenarios were analyzed to calculate the dose consequences. It was determined that the steam release event is the bounding accident. The onsite and offsite dose consequences for this event are calculated to be 0.24 Sv (24 rem) and 3.2 x 10 -4 Sv (32 mrem), respectively. These consequences are below the risk acceptance guidelines for an unlikely event, as established in WHC-CM-4-46, Nonreactor Facility Safety Analysis Manual. With the design features and the use of the controls presented in Section 8.0, this operation represents a minimal risk

A standing wave linear ultrasonic motor operating in in-plane expanding and bending modes.

Science.gov (United States)

Chen, Zhijiang; Li, Xiaotian; Ci, Penghong; Liu, Guoxi; Dong, Shuxiang

2015-03-01

A novel standing wave linear ultrasonic motor operating in in-plane expanding and bending modes was proposed in this study. The stator (or actuator) of the linear motor was made of a simple single Lead Zirconate Titanate (PZT) ceramic square plate (15 × 15 × 2 mm(3)) with a circular hole (D = 6.7 mm) in the center. The geometric parameters of the stator were computed with the finite element analysis to produce in-plane bi-mode standing wave vibration. The calculated results predicted that a driving tip attached at midpoint of one edge of the stator can produce two orthogonal, approximate straight-line trajectories, which can be used to move a slider in linear motion via frictional forces in forward or reverse direction. The investigations showed that the proposed linear motor can produce a six times higher power density than that of a previously reported square plate motor.

STOMP Sparse Vegetation Evapotranspiration Model for the Water-Air-Energy Operational Mode

Energy Technology Data Exchange (ETDEWEB)

Ward, Anderson L.; White, Mark D.; Freeman, Eugene J.; Zhang, Z. F.

2005-09-15

The Water-Air-Energy (WAE) Operational Mode of the Subsurface Transport Over Multiple Phases (STOMP) numerical simulator solves the coupled conservation equations for water mass, air mass, and thermal energy in multiple dimensions. This addendum describes the theory, input file formatting, and application of a soil-vegetation-atmosphere transfer (SVAT) scheme for STOMP that is based on a sparse vegetation evapotranspiration model. The SVAT scheme is implemented as a boundary condition on the upper surface of the computational domain and has capabilities for simulating evaporation from bare surfaces as well as evapotranspiration from sparsely vegetated surfaces populated with single or multiple plant species in response to meteorological forcings. With this extension, the model calculates water mass, air mass and thermal energy across a boundary surface in addition to root-water transport between the subsurface and atmosphere. This mode represents the barrier extension of the WAE mode and is designated as STOMP-WAE-B. Input for STOMP-WAE-B is specified via three input cards and include: atmospheric conditions through the Atmospheric Conditions Card; time-invariant plant species data through the Plant Properties Card; and time varying plant species data through the Boundary Conditions Card. Two optional cards, the Observed Data and UCODE Control Cards allow use of STOMP-WAE with UCODE in an inverse mode to estimate model parameters. STOMP-WAE was validated by solving a number of test problems from the literature that included experimental observations as well as analytical or numerical solutions. Several of the UNSAT-H verification problems are included along with a benchmark simulation derived from a recently published intercode comparison for barrier design tools. Results show that STOMP is able to meet, and in most cases, exceed performance of other commonly used simulation codes without having to resort to may of their simplifying assumptions. Use of the fully

Dual-Mode Combustor

Science.gov (United States)

Trefny, Charles J (Inventor); Dippold, Vance F (Inventor)

2013-01-01

A new dual-mode ramjet combustor used for operation over a wide flight Mach number range is described. Subsonic combustion mode is usable to lower flight Mach numbers than current dual-mode scramjets. High speed mode is characterized by supersonic combustion in a free-jet that traverses the subsonic combustion chamber to a variable nozzle throat. Although a variable combustor exit aperture is required, the need for fuel staging to accommodate the combustion process is eliminated. Local heating from shock-boundary-layer interactions on combustor walls is also eliminated.

How Mode of Delivery Affects Comprehension of an Operations Management Simulation: Online vs Face-to-Face Classrooms

Science.gov (United States)

Riley, Jason M.; Ellegood, William A.; Solomon, Stanislaus; Baker, Jerrine

2017-01-01

Purpose: This study aims to understand how mode of delivery, online versus face-to-face, affects comprehension when teaching operations management concepts via a simulation. Conceptually, the aim is to identify factors that influence the students' ability to learn and retain new concepts. Design/methodology/approach: Leveraging Littlefield…

Radial electric field evolution in various operational modes in the TUMAN-3M tokamak

International Nuclear Information System (INIS)

Askinazi, L G; Kornev, V A; Krikunov, S V; Lebedev, S V; Smirnov, A I; Tukachinsky, A S; Vildjunas, M I; Zhubr, N A; Krupnik, L I; Tendler, M

2008-01-01

Radial electric field evolution has been studied on the TUAMN-3M tokamak in different modes of operation: ohmic and NBI heating, L- and H-modes, with and without strong MHD activity. Peripheral radial electric field was measured using Langmuire probes, which were inserted up to 2cm inside LCFS, while core plasma potential evolution was measured using HIBP diagnostic. It was found, that in presence of strong MHD activity radial electric field in a vicinity of the island changed sign from negative to positive and could reach up to 4kV/m. Central plasma potential exhibited a positive perturbation of ∼700V during the MHD burst. This positive radial electric field might lead to H-mode termination, both in ohmic and NBI heating cases. Possible mechanism of the positive E r generation, namely the electron losses along ergodized magnetic field lines in the presence of MHD-island, is discussed. The same mechanism might be responsible for the positive potential spikes during a saw-tooth crash, also observed using HIBP. Another phenomenon observed using HIBP was quasi-coherent potential oscillations with the frequency close to one of the GAM. Possible location of these oscillations in the core region r/a ∼ 0.33 is discussed

Second-order sliding mode controller with model reference adaptation for automatic train operation

Science.gov (United States)

Ganesan, M.; Ezhilarasi, D.; Benni, Jijo

2017-11-01

In this paper, a new approach to model reference based adaptive second-order sliding mode control together with adaptive state feedback is presented to control the longitudinal dynamic motion of a high speed train for automatic train operation with the objective of minimal jerk travel by the passengers. The nonlinear dynamic model for the longitudinal motion of the train comprises of a locomotive and coach subsystems is constructed using multiple point-mass model by considering the forces acting on the vehicle. An adaptation scheme using Lyapunov criterion is derived to tune the controller gains by considering a linear, stable reference model that ensures the stability of the system in closed loop. The effectiveness of the controller tracking performance is tested under uncertain passenger load, coupler-draft gear parameters, propulsion resistance coefficients variations and environmental disturbances due to side wind and wet rail conditions. The results demonstrate improved tracking performance of the proposed control scheme with a least jerk under maximum parameter uncertainties when compared to constant gain second-order sliding mode control.

Coupled-Mode Theory derivation of the formal equivalence between a three-mode waveguide and a set of three mutually coupled single-mode waveguides

Directory of Open Access Journals (Sweden)

Boucher Yann G.

2017-01-01

Full Text Available The formal identification between a two-mode waveguide and a system of two mutually coupled single-mode waveguides stems from the symmetries of the evolution operator. When the gap tends to zero, the super-modes of the coupled system merge continuously into the modes of the multimode waveguide. For modelling purposes, it is very tempting to extend the analogy to three-mode waveguides (and beyond. But not without some precautions…

LONG-TERM PERFORMANCE OF SOLID OXIDE STACKS WITH ELECTRODE-SUPPORTED CELLS OPERATING IN THE STEAM ELECTROLYSIS MODE

Energy Technology Data Exchange (ETDEWEB)

J. E. O' Brien; R. C. O' Brien; X. Zhang; G. Tao; B. J. Butler

2011-11-01

Performance characterization and durability testing have been completed on two five-cell high-temperature electrolysis stacks constructed with advanced cell and stack technologies. The solid oxide cells incorporate a negative-electrode-supported multi-layer design with nickel-zirconia cermet negative electrodes, thin-film yttria-stabilized zirconia electrolytes, and multi-layer lanthanum ferrite-based positive electrodes. The per-cell active area is 100 cm2. The stack is internally manifolded with compliant mica-glass seals. Treated metallic interconnects with integral flow channels separate the cells. Stack compression is accomplished by means of a custom spring-loaded test fixture. Initial stack performance characterization was determined through a series of DC potential sweeps in both fuel cell and electrolysis modes of operation. Results of these sweeps indicated very good initial performance, with area-specific resistance values less than 0.5 ?.cm2. Long-term durability testing was performed with A test duration of 1000 hours. Overall performance degradation was less than 10% over the 1000-hour period. Final stack performance characterization was again determined by a series of DC potential sweeps at the same flow conditions as the initial sweeps in both electrolysis and fuel cell modes of operation. A final sweep in the fuel cell mode indicated a power density of 0.356 W/cm2, with average per-cell voltage of 0.71 V at a current of 50 A.

Effect of Wave Accessibility on Lower Hybrid Wave Current Drive in Experimental Advanced Superconductor Tokamak with H-Mode Operation

International Nuclear Information System (INIS)

Li Xin-Xia; Xiang Nong; Gan Chun-Yun

2015-01-01

The effect of the wave accessibility condition on the lower hybrid current drive in the experimental advanced superconductor Tokamak (EAST) plasma with H-mode operation is studied. Based on a simplified model, a mode conversion layer of the lower hybrid wave between the fast wave branch and the slow wave branch is proved to exist in the plasma periphery for typical EAST H-mode parameters. Under the framework of the lower hybrid wave simulation code (LSC), the wave ray trajectory and the associated current drive are calculated numerically. The results show that the wave accessibility condition plays an important role on the lower hybrid current drive in EAST plasma. For wave rays with parallel refractive index n ‖ = 2.1 or n ‖ = 2.5 launched from the outside midplane, the wave rays may penetrate the core plasma due to the toroidal geometry effect, while numerous reflections of the wave ray trajectories in the plasma periphery occur. However, low current drive efficiency is obtained. Meanwhile, the wave accessibility condition is improved if a higher confined magnetic field is applied. The simulation results show that for plasma parameters under present EAST H-mode operation, a significant lower hybrid wave current drive could be obtained for the wave spectrum with peak value n ‖ = 2.1 if a toroidal magnetic field B T = 2.5 T is applied. (paper)

Effect of mode of operation on hydrogen production from glycerol at thermal neutral conditions: Thermodynamic analysis

Energy Technology Data Exchange (ETDEWEB)

Pairojpiriyakul, Thirasak; Soottitantawat, Apinan; Arpornwichanop, Amornchai; Assabumrungrat, Suttichai [Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University (Thailand); Kiatkittipong, Worapon [Department of Chemical Engineering, Faculty of Engineering and Industrial Technology, Silpakorn University (Thailand); Wiyaratn, Wisitsree [Department of Production Technology Education, Faculty of Industrial Education and Technology, King Mongkut' s University of Technology Thonburi (Thailand); Laosiripojana, Navadol [The Joint Graduate School of Energy and Environment, King Mongkut' s University of Technology Thonburi (Thailand); Croiset, Eric [Department of Chemical Engineering, University of Waterloo (Canada)

2010-10-15

Thermodynamic analysis of hydrogen production from glycerol under thermal neutral conditions is studied in this work. Heat requirement from the process can be achieved from the exothermic reaction of glycerol with oxygen in air fed to the system. Two modes of operation for air feeding are considered including (i) Single-feed mode in which air is fed in combination with water and glycerol to the reformer, and (ii) Split-feed mode in which air and part of glycerol is fed to a combustor in order to generate heat. The thermal neutral conditions are considered for two levels including Reformer and System levels. It was found that the H{sub 2} yield from both modes is not significantly different at the Reformer level. In contrast, the difference becomes more pronounced at the System level. Single-feed and Split-feed modes offer high H{sub 2} yield in low (600-900 K) and high (900-1200 K) temperature ranges, respectively. The maximum H{sub 2} yields are 5.67 (water to glycerol ratio, WGR = 12, oxygen to glycerol ratio, OGR = 0.37, T = 900 K, Split-feed mode), and 3.28 (WGR = 3, OGR = 1.40, T = 900 K, Single-feed mode), for the Reformer and System levels, respectively. The difference between H{sub 2} yields in both levels mainly arises from the huge heat demand for preheating feeds in the System level, and therefore, a higher amount of air is needed to achieve the thermal neutral condition. Split-feed mode is a favorable choice in term of H{sub 2} purity because the gas product is not diluted with N{sub 2} from the air. The use of pure O{sub 2} and afterburner products (ABP) stream were also considered at the System level. The maximum H{sub 2} yield becomes 3.75 (WGR = 5.21, OGR = 1.28, T = 900 K, Split-feed mode) at thermal neutral condition when utilizing heat from the ABP stream. Finally comparisons between the different modes and levels are addressed in terms of yield of by-products, and carbon formation. (author)

Diagnostic for two-mode variable valve activation device

Science.gov (United States)

Fedewa, Andrew M

2014-01-07

A method is provided for diagnosing a multi-mode valve train device which selectively provides high lift and low lift to a combustion valve of an internal combustion engine having a camshaft phaser actuated by an electric motor. The method includes applying a variable electric current to the electric motor to achieve a desired camshaft phaser operational mode and commanding the multi-mode valve train device to a desired valve train device operational mode selected from a high lift mode and a low lift mode. The method also includes monitoring the variable electric current and calculating a first characteristic of the parameter. The method also includes comparing the calculated first characteristic against a predetermined value of the first characteristic measured when the multi-mode valve train device is known to be in the desired valve train device operational mode.

Determination Of Maximum Power Of The RSG-Gas At Power Operation Mode Using One Line Cooling System

International Nuclear Information System (INIS)

Hastuti, Endiah Puji; Kuntoro, Iman; Darwis Isnaini, M.

2000-01-01

In the frame of minimizing the operation-cost, operation mode using one line cooling system is being evaluated. Maximum reactor power shall be determined to assure that the existing safety criteria are not violated. The analysis was done by means of a core thermal hydraulic code, COOLOD-N. The code solves core thermal hydraulic equation at steady state conditions. By varying the reactor power as the input, thermal hydraulic parameters such as fuel cladding and fuel meat temperatures as well as safety margin against flow instability were calculated. Imposing the safety criteria to the results, maximum permissible power for this operation was obtained as much as 17.1 MW. Nevertheless, for operation the maximum power is limited to 15MW

Approach to the energetic coaxial gun of the steady-state mode operation

International Nuclear Information System (INIS)

Hirano, Kei-ichi

1993-01-01

Behaviors of a coaxial plasma gun operated in a steady-state mode have been studied. It is shown that the gun has potentialities to yield an energetic plasma beam, if a supersonic plasma flow is supplied instead of a neutral gas and if shorting out of the Hall potential is minimized on the surfaces of the electrodes. The former is necessary because a electromagnetic force chokes the subsonic flow appearing in the ionizing zone of the inlet gas. The latter is achieved if the electrodes are segmented into many insulated short elements along the axis. The required minimum number of the segmentation is estimated by the newly developed model based on the boundary layer concept. (author)

Experimental investigation of non-condensable gases effect on operation of VVER steam generator in condensation mode

International Nuclear Information System (INIS)

Efanov, A. D.; Kalyakin, S. G.; Morozov, A. V.; Remizov, O. V.; Tsyganok, A. A.; Generalov, V. N.; Berkovich, V. M.; Taranov, G. S.

2008-01-01

To provide the safety in new Russian NPP designs, protection passive systems which don't depend upon human errors are widely used. In terms of safety, the design of NPP of new generation (NPP-2006) falls into the class of advanced NPPs. In the event of an beyond design basis accident with the rupture of the reactor primary circuit and accompanied by the loss of ac sources, the use of passive safety systems are provided for necessary core cooling. Among these is passive heat removal system (PHRS). In the case of leakage in the primary circuit this system ensures the transition of steam generators (SG) to operation in the mode of condensation of the primary circuit steam coming to SG piping from the reactor. As a result, the condensate from steam generators arrives at the core providing its additional cooling. The SG condensation capacity can be adversely affected by the presence of non-condensable gases in the primary circuit of the reactor. Their main sources are nitrogen arriving at the circuit, as hydro accumulators actuate, products of radiolysis of water and air drawn in from the containment through the pipeline rupture. The accumulation of non-condensable gases in SG piping can result in degradation of its condensation capacity to the extent that condensation completely terminates. In this case, the core cooling conditions may be impaired. To experimental investigation of the condensation mode of operation of WER steam generator, a large scale HA2M-SG test rig was constructed at the SSC RF IPPE. The test rig incorporates: buffer tank, equipped by steam supply system; SG model with volumetric-power scale is 1:46; PHRS heat exchanger imitator, cooling by process water. The rig main equipment connected by pipelines and equipped by valves. The elevations of the main equipment correspond to those of reactor project. The rig maximum operating parameters: steam pressure - 1.6 MPa, temperature - 200 Celsius degrees. Experiments at the HA2M-SG test rig have been

Fluorescence quenching and the "ring-mode" to "red-mode" transition in alkali inductively coupled plasmas

Science.gov (United States)

Huang, M.; Bazurto, R.; Camparo, J.

2018-01-01

The ring-mode to red-mode transition in alkali metal inductively coupled plasmas (ICPs) (i.e., rf-discharge lamps) is perhaps the most important physical phenomenon affecting these devices as optical pumping light sources for atomic clocks and magnetometers. It sets the limit on useful ICP operating temperature, thereby setting a limit on ICP light output for atomic-clock/magnetometer signal generation, and it is a temperature region of ICP operation associated with discharge instability. Previous work has suggested that the mechanism driving the ring-mode to red-mode transition is associated with radiation trapping, but definitive experimental evidence validating that hypothesis has been lacking. Based on that hypothesis, one would predict that the introduction of an alkali-fluorescence quenching gas (i.e., N2) into the ICP would increase the ring-mode to red-mode transition temperature. Here, we test that prediction, finding direct evidence supporting the radiation-trapping hypothesis.

Orbital angular momentum of general astigmatic modes

International Nuclear Information System (INIS)

Visser, Jorrit; Nienhuis, Gerard

2004-01-01

We present an operator method to obtain complete sets of astigmatic Gaussian solutions of the paraxial wave equation. In case of general astigmatism, the astigmatic intensity and phase distribution of the fundamental mode differ in orientation. As a consequence, the fundamental mode has a nonzero orbital angular momentum, which is not due to phase singularities. Analogous to the operator method for the quantum harmonic oscillator, the corresponding astigmatic higher-order modes are obtained by repeated application of raising operators on the fundamental mode. The nature of the higher-order modes is characterized by a point on a sphere, in analogy with the representation of polarization on the Poincare sphere. The north and south poles represent astigmatic Laguerre-Gaussian modes, similar to circular polarization on the Poincare sphere, while astigmatic Hermite-Gaussian modes are associated with points on the equator, analogous to linear polarization. We discuss the propagation properties of the modes and their orbital angular momentum, which depends on the degree of astigmatism and on the location of the point on the sphere

Reduction of NOx emission in tangential fired - furnace by changing the, mode of operation

International Nuclear Information System (INIS)

Chudnovsky, B.; Talanker, A.; Levin, L.; Kahana, S

1998-01-01

The present work analyses tile results of tests on 575 MW units with tangential firing furnace arrangement in sub-stoichiometric combustion. Tangential firing provides good conditions for implementing sub-stoichiometric combustion owing to the delivery scheme of pulverized coal and air. The furnace was tested in several different modes of operation (Over Fire Air, Bunkers Out Of Service, Excess air, Tilt etc.) to achieve low cost NOx reduction. Actual performance data are presented based on experiments made on lEC's boiler in M.D. 'B' power station

Superconducting multi-cell trapped mode deflecting cavity

Science.gov (United States)

Lunin, Andrei; Khabiboulline, Timergali; Gonin, Ivan; Yakovlev, Vyacheslav; Zholents, Alexander

2017-10-10

A method and system for beam deflection. The method and system for beam deflection comprises a compact superconducting RF cavity further comprising a waveguide comprising an open ended resonator volume configured to operate as a trapped dipole mode; a plurality of cells configured to provide a high operating gradient; at least two pairs of protrusions configured for lowering surface electric and magnetic fields; and a main power coupler positioned to optimize necessary coupling for an operating mode and damping lower dipole modes simultaneously.

Relationship between composition of mixture charged and that in circulation in an auto refrigerant cascade and a J-T refrigerator operating in liquid refrigerant supply mode

Science.gov (United States)

Sreenivas, Bura; Nayak, H. Gurudath; Venkatarathnam, G.

2017-01-01

The composition of the refrigerant mixture in circulation during steady state operation of J-T and allied refrigerators is not the same as that charged due to liquid hold up in the heat exchangers and phase separators, as well as the differential solubility of different refrigerant components in the compressor lubricating oil. The performance of refrigerators/liquefiers operating on mixed refrigerant cycles is dependent on the mixture composition. It is therefore important to charge the right mixture that results in an optimum composition in circulation during steady state operation. The relationship between the charged and circulating composition has been experimentally studied in a J-T refrigerator operating in the liquid refrigerant supply (LRS) mode and an auto refrigerant cascade refrigerator (with a phase separator) operating in the gas refrigerant supply (GRS) mode. The results of the study are presented in this work. The results show that the method presented earlier for J-T refrigerators operating in GRS mode is also applicable in the case of refrigerators studied in this work.

Results from prototypes of environmental and health alarm devices based on gaseous detectors operating in air in counting mode

CERN Document Server

Martinengo, P; Peskov, V; Benaben, P; Charpak, G; Breuil, P

2011-01-01

We have developed and successfully tested two prototypes of detectors of dangerous gases based on wire-type counters operating in air in avalanche mode: one is for radon (Rn) detection whereas the other one is for the detection of gases with an ionization potential less than the air components. Due to the operation in pulse counting mode these prototypes have sensitivities comparable to (in the case of the Rn detector) or much higher than (in the case of the detector for low ionization gases) the best commercial devices currently available on the market. We believe that due to their high sensitivity, simplicity and low cost such new detectors will find massive applications. One of them, discussed in this paper, could be the on-line monitoring of Rn for the prediction of earthquakes. (C) 2010 Elsevier B.V. All rights reserved.

Numerical Study of the Dynamic Response of Heat and Mass Transfer to Operation Mode Switching of a Unitized Regenerative Fuel Cell

Directory of Open Access Journals (Sweden)

Hong Xiao

2016-12-01

Full Text Available Knowledge concerning the complicated changes of mass and heat transfer is desired to improve the performance and durability of unitized regenerative fuel cells (URFCs. In this study, a transient, non-isothermal, single-phase, and multi-physics mathematical model for a URFC based on the proton exchange membrane is generated to investigate transient responses in the process of operation mode switching from fuel cell (FC to electrolysis cell (EC. Various heat generation mechanisms, including Joule heat, reaction heat, and the heat attributed to activation polarizations, have been considered in the transient model coupled with electrochemical reaction and mass transfer in porous electrodes. The polarization curves of the steady-state models are validated by experimental data in the literatures. Numerical results reveal that current density, gas mass fractions, and temperature suddenly change with the sudden change of operating voltage in the mode switching process. The response time of temperature is longer than that of current density and gas mass fractions. In both FC and EC modes, the cell temperature and gradient of gas mass fraction in the oxygen side are larger than that in the hydrogen side. The temperature difference of the entire cell is less than 1.5 K. The highest temperature appears at oxygen-side catalyst layer under the FC mode and at membrane under a more stable EC mode. The cell is exothermic all the time. These dynamic responses and phenomena have important implications for heat analysis and provide proven guidelines for the improvement of URFCs mode switching.

Generalized coupling resonance modeling, analysis, and active damping of multi-parallel inverters in microgrid operating in grid-connected mode

DEFF Research Database (Denmark)

Chen, Zhiyong; Chen, Yandong; Guerrero, Josep M.

2016-01-01

This paper firstly presents an equivalent coupling circuit modeling of multi-parallel inverters in microgrid operating in grid-connected mode. By using the model, the coupling resonance phenomena are explicitly investigated through the mathematical approach, and the intrinsic and extrinsic...

Operating principle of Soft Open Points for electrical distribution network operation

International Nuclear Information System (INIS)

Cao, Wanyu; Wu, Jianzhong; Jenkins, Nick; Wang, Chengshan; Green, Timothy

2016-01-01

Highlights: • Two control modes were developed for a B2B VSCs based SOP. • The SOP operating principle was investigated under various network conditions. • The performance of the SOP using two control modes was analyzed. - Abstract: Soft Open Points (SOPs) are power electronic devices installed in place of normally-open points in electrical power distribution networks. They are able to provide active power flow control, reactive power compensation and voltage regulation under normal network operating conditions, as well as fast fault isolation and supply restoration under abnormal conditions. Two control modes were developed for the operation of an SOP, using back-to-back voltage-source converters (VSCs). A power flow control mode with current control provides independent control of real and reactive power. A supply restoration mode with a voltage controller enables power supply to isolated loads due to network faults. The operating principle of the back-to-back VSCs based SOP was investigated under both normal and abnormal network operating conditions. Studies on a two-feeder medium-voltage distribution network showed the performance of the SOP under different network-operating conditions: normal, during a fault and post-fault supply restoration. During the change of network operating conditions, a mode switch method based on the phase locked loop controller was used to achieve the transitions between the two control modes. Hard transitions by a direct mode switching were noticed unfavourable, but seamless transitions were obtained by deploying a soft cold load pickup and voltage synchronization process.

Cross-correlated imaging of single-mode photonic crystal rod fiber with distributed mode filtering

DEFF Research Database (Denmark)

Laurila, Marko; Barankov, Roman; Jørgensen, Mette Marie

2013-01-01

Photonic crystal bandgap fibers employing distributed mode filtering design provide near diffraction-limited light outputs, a critical property of fiber-based high-power lasers. Microstructure of the fibers is tailored to achieve single-mode operation at specific wavelength by resonant mode...... identify regimes of resonant coupling between higher-order core modes and cladding band. We demonstrate a passive fiber design in which the higher-order modal content inside the single-mode guiding regime is suppressed by at least 20 dB even for significantly misaligned input-coupling configurations....

Output Feedback Fractional-Order Nonsingular Terminal Sliding Mode Control of Underwater Remotely Operated Vehicles

Directory of Open Access Journals (Sweden)

Yaoyao Wang

2014-01-01

Full Text Available For the 4-DOF (degrees of freedom trajectory tracking control problem of underwater remotely operated vehicles (ROVs in the presence of model uncertainties and external disturbances, a novel output feedback fractional-order nonsingular terminal sliding mode control (FO-NTSMC technique is introduced in light of the equivalent output injection sliding mode observer (SMO and TSMC principle and fractional calculus technology. The equivalent output injection SMO is applied to reconstruct the full states in finite time. Meanwhile, the FO-NTSMC algorithm, based on a new proposed fractional-order switching manifold, is designed to stabilize the tracking error to equilibrium points in finite time. The corresponding stability analysis of the closed-loop system is presented using the fractional-order version of the Lyapunov stability theory. Comparative numerical simulation results are presented and analyzed to demonstrate the effectiveness of the proposed method. Finally, it is noteworthy that the proposed output feedback FO-NTSMC technique can be used to control a broad range of nonlinear second-order dynamical systems in finite time.

Multiple-Pulse Operation and Bound States of Solitons in Passive Mode-Locked Fiber Lasers

Directory of Open Access Journals (Sweden)

A. Komarov

2012-01-01

Full Text Available We present results of our research on a multiple-pulse operation of passive mode-locked fiber lasers. The research has been performed on basis of numerical simulation. Multihysteresis dependence of both an intracavity energy and peak intensities of intracavity ultrashort pulses on pump power is found. It is shown that the change of a number of ultrashort pulses in a laser cavity can be realized by hard as well as soft regimes of an excitation and an annihilation of new solitons. Bound steady states of interacting solitons are studied for various mechanisms of nonlinear losses shaping ultrashort pulses. Possibility of coding of information on basis of soliton trains with various bonds between neighboring pulses is discussed. The role of dispersive wave emitted by solitons because of lumped intracavity elements in a formation of powerful soliton wings is analyzed. It is found that such powerful wings result in large bounding energies of interacting solitons in steady states. Various problems of a soliton interaction in passive mode-locked fiber lasers are discussed.

On the sloshing free surface in the draft tube cone of a Francis turbine operating in synchronous condenser mode

Science.gov (United States)

Vagnoni, E.; Andolfatto, L.; Avellan, F.

2017-04-01

Hydropower plants may be required to operate in synchronous condenser mode in order to supply reactive power to the grid for compensating the fluctuations introduced by the intermittent renewable energies such wind and solar. When operating in this mode, the tail water in the Francis turbine or pump-turbine is depressed below the runner by injecting pressurized air in order to spin in air to reduce the power consumption. Many air-water interaction phenomena occur in the machine causing air losses and a consequent power consumption to recover the air lost. In this paper, the experimental investigation of the sloshing motion in the cone of a dewatered Francis turbine performed by image visualization and pressure measurements is presented. The developed image post processing method for identifying the amplitude and frequency of the oscillation of the free surface is described and the results obtained are illustrated and discussed.

Observation of a High Performance Operating Regime with Small Edge-Localized Modes in the National Spherical Torus Experiment

International Nuclear Information System (INIS)

Maingi, R.; Tritz, K.; Fredrickson, E.D.; Menard, J.E.; Sabbagh, S.A.; Stutman, D.; Bell, M.G.; Bell, R.E.; Bush, C.E.; Gates, D.A.; Johnson, D.W.; Kaita, R.; Kaye, S.M.; Kugel, H.W.; LeBlanc, B.P.; Mueller, D.; Raman, R.; Roquemore, A.L.; Soukhanovskii, V.A.

2004-01-01

We report observation of a high performance scenario in the National Spherical Torus Experiment with very small edge-localized modes (ELMs). These ELMs have no measurable impact on stored energy and are consistent with high bootstrap current operation with line average density approaching Greenwald scaling. The ELM perturbation is observed to typically originate near the lower divertor region, as opposed to the outer midplane for ELMs described in the literature. If extrapolable, this scenario would provide an attractive operating regime for next step fusion experiments

Sliding Mode Control for Pressurized-Water Nuclear Reactors in load following operations with bounded xenon oscillations

International Nuclear Information System (INIS)

Ansarifar, G.R.; Saadatzi, S.

2015-01-01

Highlights: • We present SMC which is a robust nonlinear controller to control the PWR power. • Xenon oscillations are kept bounded within acceptable limits. • The stability analysis has been based on Lyapunov approach. • Simulation results indicate the high performance of this new control. - Abstract: One of the important operations in nuclear power plants is load-following in which imbalance of axial power distribution induces xenon oscillations. These oscillations must be maintained within acceptable limits otherwise the nuclear power plant could become unstable. Therefore, bounded xenon oscillation considered to be a constraint for the load-following operation. In this paper, sliding mode control (SMC) which is a robust nonlinear controller is designed to control the Pressurized-Water Nuclear Reactor (PWR) power for the load-following operation problem that ensures xenon oscillations are kept bounded within acceptable limits. The proposed controller uses constant axial offset (AO) strategy to maintain xenon oscillations to be bounded. The constant AO is a robust state constraint for load-following problem. The reactor core is simulated based on the two-point nuclear reactor model and one delayed neutron group. The stability analysis is given by means Lyapunov approach, thus the control system is guaranteed to be stable within a large range. The employed method is easy to implement in practical applications and moreover, the sliding mode control exhibits the desired dynamic properties during the entire output-tracking process independent of perturbations. Simulation results are presented to demonstrate the effectiveness of the proposed controller in terms of performance, robustness and stability. Results show that the proposed controller for the load-following operation is sufficiently effective so that the xenon oscillations are kept bounded in the considered region

Pulsed-mode operation and performance of a ferromagnetic shape memory alloy actuator

International Nuclear Information System (INIS)

Asua, E; García-Arribas, A; Etxebarria, V; Feuchtwanger, J

2014-01-01

The actuation capabilities and positioning performance of a single crystal ferromagnetic shape memory alloy (FSMA) operated in pulsed mode are evaluated in a prototype device. It consists of two orthogonal coil pairs that produce the magnetic fields necessary for the non-contact deformation of the material. The position of the top of the crystal after actuation is measured by a capacitive sensor. A specifically designed power module drives the discharge of a set of capacitors through the coils, producing fast current pulses of large amplitudes (about 250 A), the coil pairs are driven independently to control the direction of actuation. Open-loop experiments demonstrate that successive pulses of increasing magnitude successfully produced the desired expansion and contraction of the crystal, depending on the pair of coils that is activated. The deformation achieved is maintained after the pulses, highlighting the advantageous set-and-forget operation of the device. Closed-loop experiments are performed using a double proportional–integral–derivative controller, designed to take advantage of the energy-saving quality of the set-and-forget operation. Despite the nonlinear response and hysteric response of FSMA materials, a reference position can be reached and maintained with a maximum error of 0.5 μm. (paper)

Experimental investigation of the sloshing motion of the water free surface in the draft tube of a Francis turbine operating in synchronous condenser mode

Science.gov (United States)

Vagnoni, Elena; Favrel, Arthur; Andolfatto, Loïc; Avellan, François

2018-06-01

Hydropower units may be required to operate in condenser mode to supply reactive power. In this operating mode, the water level in the turbine or pump-turbine is decreased below the runner by closing the guide vanes and injecting pressurized air. While operating in condenser mode the machine experiences power losses due to several air-water interaction phenomena which cause air losses. One of such phenomena is the sloshing motion of the water free surface below the runner in the draft tube cone of a Francis turbine. The objective of the present work is to experimentally investigate the sloshing motion of the water free surface in the draft tube cone of a reduced scale physical model of a Francis turbine operating in condenser mode. Images acquisition and simultaneous pressure fluctuation measurements are performed and an image processing method is developed to investigate amplitude and frequency of the sloshing motion of the free surface. It is found that this motion is excited at the natural frequency of the water volume and corresponds to the azimuthal wavenumber m = 1 of a rotating gravity wave. The amplitude of the motion is perturbed by wave breaking and it decreases by increasing the densimetric Froude number. The sloshing frequency slightly increases with respect to the natural frequency of the water volume by increasing the densimetric Froude number. Moreover, it results that this resonant phenomenon is not related to the torque perturbation.

Cross focusing of mixed mode operation in an extra dense plasma

Energy Technology Data Exchange (ETDEWEB)

Soni, V S; Nayyar, V P [Punjabi Univ., Patiala (India). Dept. of Physics

1979-08-01

This paper presents a study of the nonlinear propagation of a mixture of two degenerate modes (TEM/sub 00/ and TEM/sub 10/) of a high power laser beam in an extradense plasma. The high irradiance inhomogeneous laser beam creates an electron density gradient region in the overdense plasma (n > nsub(c)) through which the beam can propagate. The focusing effects have been studied for different power ratios of the two modes (TEM/sub 00/ mode is considered to be stronger than the TEM/sub 10/ mode). Self-focusing of the beam in x and y directions for critical power has been extensively studied.

Observation of dynamic interactions between fundamental and second-harmonic modes in a high-power sub-terahertz gyrotron operating in regimes of soft and hard self-excitation.

Science.gov (United States)

Saito, Teruo; Tatematsu, Yoshinori; Yamaguchi, Yuusuke; Ikeuchi, Shinji; Ogasawara, Shinya; Yamada, Naoki; Ikeda, Ryosuke; Ogawa, Isamu; Idehara, Toshitaka

2012-10-12

Dynamic mode interaction between fundamental and second-harmonic modes has been observed in high-power sub-terahertz gyrotrons [T. Notake et al., Phys. Rev. Lett. 103, 225002 (2009); T. Saito et al. Phys. Plasmas 19, 063106 (2012)]. Interaction takes place between a parasitic fundamental or first-harmonic (FH) mode and an operating second-harmonic (SH) mode, as well as among SH modes. In particular, nonlinear excitation of the parasitic FH mode in the hard self-excitation regime with assistance of a SH mode in the soft self-excitation regime was clearly observed. Moreover, both cases of stable two-mode oscillation and oscillation of the FH mode only were observed. These observations and theoretical analyses of the dynamic behavior of the mode interaction verify the nonlinear hard self-excitation of the FH mode.

Measurements of electron beam emittance in the Accelerator Test Facility damping ring operated in multibunch modes

Directory of Open Access Journals (Sweden)

Yosuke Honda

2003-09-01

Full Text Available We present the measurement results of electron beam emittance in the Accelerator Test Facility damping ring operated in multibunch modes. The measurements were carried out with an upgraded laser wire beam profile monitor. The monitor has now a vertical wire as well as a horizontal one and is able to make much faster measurements thanks to an increased effective laser power inside the cavity. The measured emittance shows no large bunch-to-bunch dependence in either the horizontal or vertical directions. The values of the vertical emittance are similar to those obtained in the single-bunch operation. The present results are an important step toward the realization of a high-energy linear collider.

Performance comparison of three-phase flux reversal permanent magnet motors in BLDC and BLAC operation mode

International Nuclear Information System (INIS)

Stumberger, B.; Stumberger, G.; Hadziselimovic, M.; Hamler, A.; Gorican, V.; Jesenik, M.; Trlep, M.

2008-01-01

The paper presents a comparison of torque capability and flux-weakening performance of three-phase flux reversal permanent magnet motors with surface and inset permanent magnets. Finite element analysis is employed to determine the performance of each motor in BLDC and BLAC operation mode. It is shown that the torque capability and flux-weakening performance of surface or inset permanent magnet configuration is strongly dependent on the stator teeth number/rotor pole number combination

Study of accelerated unit unloading mode initiated by turbine feed pump trip with TVSA fuel assemblies operation in WWER-1000

International Nuclear Information System (INIS)

Borysenko, V.I.; Kadenko, I.N.; Samoilenko, D.V.

2012-01-01

This paper provides the study results of accelerated unit unloading mode (AUU) initiated at WWER-1000 unit operated at 100 % power and its expediency in the event of single Turbo Feed Pump (TFP) failure. Modeling was performed using an advanced calculation code RELAP/SCDAPSIM/Mod3.4 and relevant model for KhNPP Unit No. 2. As the study shows, SCRAM cannot be prevented in case of failure of 3 main circulation pumps due to steam generators (SG) level drop. Based on the results obtained, it is reasonably justified to allow SCRAM signal instead of AUU activation in case of single TFP failure at power level more than 90 % of N n om. This will provide more sparing temperature modes for fuel assemblies and equipment, as well as prevent additional thermal cycling loads and violation of safe operation limits as SG water levels

Solar-assisted absorption air-conditioning systems in buildings: Control strategies and operational modes

International Nuclear Information System (INIS)

Shirazi, Ali; Pintaldi, Sergio; White, Stephen D.; Morrison, Graham L.; Rosengarten, Gary; Taylor, Robert A.

2016-01-01

Highlights: • A simulation model of a solar driven absorption chiller is developed in detail. • Three control strategies were proposed in the solar loop of the plant. • Series and parallel auxiliary heater arrangements were investigated. • The results showed the auxiliary-heater in parallel outperformed the series one. • Solar fraction can be increased by 20% by implementing the proposed configuration. - Abstract: Solar-assisted cooling technology has enormous potential for air-conditioning applications since both solar energy supply and cooling energy demand are well correlated. Unfortunately, market uptake of solar cooling technologies has been slow due to the high capital cost and limited design/operational experience. In the present work, different designs and operational modes for solar heating and cooling (SHC) absorption chiller systems are investigated and compared in order to identify the preferred design strategies for these systems. Three control scenarios are proposed for the solar collector loop. The first uses a constant flow pump, while the second and third control schemes employ a variable speed pump, where the solar collector (SC) set-point temperature could be either fixed or adjusted to the required demand. Series and parallel arrangements, between the auxiliary heater and the storage tank, have been examined in detail from an energy efficiency perspective. A simulation model for different system layouts is developed in the transient system simulation environment (TRNSYS, Version 17). Simulation results revealed that the total solar fraction of the plant is increased by up to 11% when a variable speed solar loop pump is used to achieve a collector set-point temperature adjusted according to the building load demand. Another significant finding of this study is that a parallel configuration for the auxiliary heater out-performs a conventional series configuration. The yearly performance of an auxiliary heater in parallel with the storage

Control scheme for direct steam generation in parabolic troughs under recirculation operation mode

Energy Technology Data Exchange (ETDEWEB)

Valenzuela, L.; Zarza, E. [CIEMAT, Plataforma Solar de Almeria, Ctra. Senes s/n, P.O. Box 22, E-04200 Tabernas, Almeria (Spain); Berenguel, M. [Universidad de Almeria, Dpto. Lenguajes y Computacion, Ctra. Sacramento s/n, E-04120 Almeria (Spain); Camacho, E.F. [Universidad de Sevilla, Dpto. de Ingenieria de Sistemas y Automatica, Camino de los Descubrimientos s/n, E-41092 Sevilla (Spain)

2006-01-15

Electricity production using solar thermal energy is one of the main research areas at present in the field of renewable energies, these systems being characterised by the need of reliable control systems aimed at maintaining desired operating conditions in the face of changes in solar radiation, which is the main source of energy. A new prototype of solar system with parabolic trough collectors was implemented at the Plataforma Solar de Almeria (PSA, South-East Spain) to investigate the direct steam generation process under real solar conditions in the parabolic solar collector field of a thermal power plant prototype. This paper presents details and some results of the application of a control scheme designed and tested for the recirculation operation mode, for which the main objective is to obtain steam at constant temperature and pressure at the outlet of the solar field, so that changes produced in the inlet water conditions and/or solar radiation will only affect the amount of steam produced by the solar field. The steam quality and consequently the nominal efficiency of the plant are thus maintained. (author)

Method for determining the optimum mode of operation of the chemical water regime in the water-steam-circuit of power plants

International Nuclear Information System (INIS)

Sommerfeldt, P.; Reisner, H.; Hartmann, G.; Kulicke, P.

1988-01-01

The method aims at increasing the lifetime of secondary coolant circuit components in nuclear power plants through the determination of the optimum mode of operation of the chemical water regime by help of radioisotopes

Wind Farm-LA Coordinated Operation Mode and Dispatch Model in Wind Power Accommodation Promotion

Directory of Open Access Journals (Sweden)

Li Lin

2018-05-01

Full Text Available With the support of a smart grid, a load aggregator (LA that aggregates the demand response resources of small- and medium-sized customers to participate in the electricity market would be a novel way to promote wind power accommodation. This paper proposes a wind farm–LA coordinated operation mode (WLCOM, which enables LAs to deal with wind farms directly at an agreement price. Afterwards, according to the accommodation demand of the wind farm, a coordinated dispatch model taking advantage of the various response capabilities of different flexible loads is set up to maximize the revenue of the LA. A case study was conducted to demonstrate the effectiveness of the proposed WLCOM and the coordinated dispatch model. The demonstration indicates that: (a load fluctuations and wind curtailment were obviously reduced; and (b both the LA and the wind farm participating in coordinated operation obtained higher revenues. Factors that influence the accommodation level, as well as revenues of wind farms and LA, are also investigated.

Modeling of mode purity in high power gyrotrons

International Nuclear Information System (INIS)

Cai, S.Y.; Antonsen, T.M. Jr.; Saraph, G.P.

1993-01-01

Spurious mode generation at the same frequency of the operational mode in a high power gyrotron can significantly reduce the power handling capability and the stability of a gyrotron oscillator because these modes are usually not matched at the output window and thus have high absorption and reflection rates. To study the generation of this kind of mode, the authors developed a numerical model based on an existing multimode self-consistent time-dependent computer code. This model includes both TE and TM modes and accounts for mode transformations due to the waveguide inhomogeneity. With this new tool, they study the mode transformation in the gyrotron and the possibility of excitation of parasitic TE and TM modes in the up taper section due to the gyroklystron mechanism. Their preliminary results show moderate excitation of both TE and TM modes at the same frequency as the main operating mode at locations near their cutoff. Details of the model and further simulation results will be presented

Single Spatial-Mode Room-Temperature-Operated 3.0 to 3.4 micrometer Diode Lasers

Science.gov (United States)

Frez, Clifford F.; Soibel, Alexander; Belenky, Gregory; Shterengas, Leon; Kipshidze, Gela

2010-01-01

Compact, highly efficient, 3.0 to 3.4 m light emitters are in demand for spectroscopic analysis and identification of chemical substances (including methane and formaldehyde), infrared countermeasures technologies, and development of advanced infrared scene projectors. The need for these light emitters can be currently addressed either by bulky solid-state light emitters with limited power conversion efficiency, or cooled Interband Cascade (IC) semiconductor lasers. Researchers here have developed a breakthrough approach to fabrication of diode mid-IR lasers that have several advantages over IC lasers used for the Mars 2009 mission. This breakthrough is due to a novel design utilizing the strain-engineered quantum-well (QW) active region and quinternary barriers, and due to optimization of device material composition and growth conditions (growth temperatures and rates). However, in their present form, these GaSb-based laser diodes cannot be directly used as a part of sensor systems. The device spectrum is too broad to perform spectroscopic analysis of gas species, and operating currents and voltages are too high. In the current work, the emitters were fabricated as narrow-ridge waveguide index-guided lasers rather than broad stripe-gain guided multimode Fabry-Perot (FP) lasers as was done previously. These narrow-ridge waveguide mid-IR lasers exhibit much lower power consumptions, and can operate in a single spatial mode that is necessary for demonstration of single-mode distributed feedback (DBF) devices for spectroscopic applications. These lasers will enable a new generation of compact, tunable diode laser spectrometers with lower power consumption, reduced complexity, and significantly reduced development costs. These lasers can be used for the detection of HCN, C2H2, methane, and ethane.

Interacting collective modes in a laser cavity

International Nuclear Information System (INIS)

Graca, E.L.; Brito, A.L. de; Baseia, B.

1985-01-01

Collective operators are defined for the quantized radiation field in a one-dimensional laser cavity coupled to a semi-infinite outside region and the overlaps of neighbouring collective modes are considered to show how they modify, in the linear appoximation, the time evolution of the radiation field below threshold. The model and procedure work directly within a continuous spectrum of modes and allow us to get an improved insight on the prescription for the laser field in single-mode operation. (Author) [pt

Integrated Mode Choice, Small Aircraft Demand, and Airport Operations Model User's Guide

Science.gov (United States)

Yackovetsky, Robert E. (Technical Monitor); Dollyhigh, Samuel M.

2004-01-01

A mode choice model that generates on-demand air travel forecasts at a set of GA airports based on changes in economic characteristics, vehicle performance characteristics such as speed and cost, and demographic trends has been integrated with a model to generate itinerate aircraft operations by airplane category at a set of 3227 airports. Numerous intermediate outputs can be generated, such as the number of additional trips diverted from automobiles and schedule air by the improved performance and cost of on-demand air vehicles. The total number of transported passenger miles that are diverted is also available. From these results the number of new aircraft to service the increased demand can be calculated. Output from the models discussed is in the format to generate the origin and destination traffic flow between the 3227 airports based on solutions to a gravity model.

Determination of rod insertion limits of the AP600'S M-shim bank at low power operating mode

International Nuclear Information System (INIS)

Sutondo, Tegas

2002-01-01

A series of calculation works had been conducted to determine the AP00's M-shim bank insertion limits during low-power operating mode. This activity was a part of the preliminary studies toward the plan on implementation a Rapid Power Reduction System (RPRS) in AP00's control / operating system, that enable it to operate under low power level (below 50% RTP). The calculations were performed for cycle 1 and equilibrium cycle as function of power levels and the fraction of AO-bank insertion. The results show that the M-shim insertion limits for both cycle 1 and equilibrium cycle were determined based on the limiting conditions at low-burn-up level (BOL), and high burn-up level (EOL) respectively

Nonlinear Polarization Rotation-Based Mode-Locked Erbium-Doped Fiber Laser with Three Switchable Operation States

International Nuclear Information System (INIS)

Tiu Zian Cheak; Tan Sin Jin; Zarei Arman; Ahmad Harith; Harun Sulaiman Wadi

2014-01-01

A simple mode-locked erbium-doped fiber laser (EDFL) with three switchable operation states is proposed and demonstrated based on nonlinear polarization rotation. The EDFL generates a stable square pulse at a third harmonic pulse repetition rate of 87 kHz as the 1480 nm pump power increases from the threshold of 17.5 mW to 34.3 mW. The square pulse duration increases from 105 ns to 245 ns as the pump power increases within this region. The pulse operation switches to the second operation state as the pump power is varied from 48.2 mW to 116.7 mW. The laser operates at a fundamental repetition rate of 29 kHz with a fixed pulse width of 8.5 μs within the pump power region. At a pump power of 116.7 mW, the average output power is 3.84 mW, which corresponds to the pulse energy of 131.5 nJ. When the pump power continues to increase, the pulse train experiences unstable oscillation before it reaches the third stable operation state within a pump power region of 138.9 mW to 145.0 mW. Within this region, the EDFL produces a fixed pulse width of 2.8 μs and a harmonic pulse repetition rate of 58 kHz. (fundamental areas of phenomenology(including applications))

ANALYSIS OF ENERGY EFFICIENCY OF OPERATING MODES OF ELECTRICAL SYSTEMS WITH THE TRACTION LOADS

Directory of Open Access Journals (Sweden)

V. E. Bondarenko

2017-03-01

account operation mode of power systems and the use of software systems with imitation of instantaneous interrelated schemes of transport loads.

Generation of high order modes

CSIR Research Space (South Africa)

Ngcobo, S

2012-07-01

Full Text Available with the location of the Laguerre polynomial zeros. The Diffractive optical element is used to shape the TEM00 Gassian beam and force the laser to operate on a higher order TEMp0 Laguerre-Gaussian modes or high order superposition of Laguerre-Gaussian modes...

A safety equipment list for rotary mode core sampling systems operation in single shell flammable gas tanks

International Nuclear Information System (INIS)

SMALLEY, J.L.

1999-01-01

This document identifies all interim safety equipment to be used for rotary mode core sampling of single-shell flammable gas tanks utilizing Rotary Mode Core Sampling systems (RMCS). This document provides the safety equipment for RMCS trucks HO-68K-4600, HO-68K-4647, trucks three and four respectively, and associated equipment. It is not intended to replace or supersede WHC-SD-WM-SEL-023, (Kelly 1991), or WHC-SD-WM-SEL-032, (Corbett 1994), which classifies 80-68K-4344 and HO-68K-4345 respectively. The term ''safety equipment'' refers to safety class (SC) and safety significant (SS) equipment, where equipment refers to structures, systems and components (SSC's). The identification of safety equipment in this document is based on the credited design safety features and analysis contained in the Authorization Basis (AB) for rotary mode core sampling operations in single-shell flammable gas tanks. This is an interim safety classification since the AB is interim. This document will be updated to reflect the final RMCS equipment safety classification designations upon completion of a final AB which will be implemented with the release of the Final Safety Analysis Report (FSAR)

New Three-Mode Squeezing Operators Gained via Tripartite Entangled State Representation

International Nuclear Information System (INIS)

Jiang Nianquan; Fan Hongyi

2008-01-01

We show that the Agarwal-Simon representation of single-mode squeezed states can be generalized to find new form of three-mode squeezed states. We use the tripartite entangled state representations |p,y,z> and |x,u,v> to realize this goal.

Adaptive Protection Scheme for a Distribution System Considering Grid-Connected and Islanded Modes of Operation

Directory of Open Access Journals (Sweden)

Yavuz Ates

2016-05-01

Full Text Available The renewable energy-based distributed generation (DG implementation in power systems has been an active research area during the last few decades due to several environmental, economic and political factors. Although the integration of DG offers many advantages, several concerns, including protection schemes in systems with the possibility of bi-directional power flow, are raised. Thus, new protection schemes are strongly required in power systems with a significant presence of DG. In this study, an adaptive protection strategy for a distribution system with DG integration is proposed. The proposed strategy considers both grid-connected and islanded operating modes, while the adaptive operation of the protection is dynamically realized considering the availability of DG power production (related to faults or meteorological conditions in each time step. Besides, the modular structure and fast response of the proposed strategy is validated via simulations conducted on the IEEE 13-node test system.

Geometric characterization of separability and entanglement in pure Gaussian states by single-mode unitary operations

Science.gov (United States)

Adesso, Gerardo; Giampaolo, Salvatore M.; Illuminati, Fabrizio

2007-10-01

We present a geometric approach to the characterization of separability and entanglement in pure Gaussian states of an arbitrary number of modes. The analysis is performed adapting to continuous variables a formalism based on single subsystem unitary transformations that has been recently introduced to characterize separability and entanglement in pure states of qubits and qutrits [S. M. Giampaolo and F. Illuminati, Phys. Rev. A 76, 042301 (2007)]. In analogy with the finite-dimensional case, we demonstrate that the 1×M bipartite entanglement of a multimode pure Gaussian state can be quantified by the minimum squared Euclidean distance between the state itself and the set of states obtained by transforming it via suitable local symplectic (unitary) operations. This minimum distance, corresponding to a , uniquely determined, extremal local operation, defines an entanglement monotone equivalent to the entropy of entanglement, and amenable to direct experimental measurement with linear optical schemes.

Geometric characterization of separability and entanglement in pure Gaussian states by single-mode unitary operations

International Nuclear Information System (INIS)

Adesso, Gerardo; Giampaolo, Salvatore M.; Illuminati, Fabrizio

2007-01-01

We present a geometric approach to the characterization of separability and entanglement in pure Gaussian states of an arbitrary number of modes. The analysis is performed adapting to continuous variables a formalism based on single subsystem unitary transformations that has been recently introduced to characterize separability and entanglement in pure states of qubits and qutrits [S. M. Giampaolo and F. Illuminati, Phys. Rev. A 76, 042301 (2007)]. In analogy with the finite-dimensional case, we demonstrate that the 1xM bipartite entanglement of a multimode pure Gaussian state can be quantified by the minimum squared Euclidean distance between the state itself and the set of states obtained by transforming it via suitable local symplectic (unitary) operations. This minimum distance, corresponding to a, uniquely determined, extremal local operation, defines an entanglement monotone equivalent to the entropy of entanglement, and amenable to direct experimental measurement with linear optical schemes

Two-mode Gaussian density matrices and squeezing of photons

International Nuclear Information System (INIS)

Tucci, R.R.

1992-01-01

In this paper, the authors generalize to 2-mode states the 1-mode state results obtained in a previous paper. The authors study 2-mode Gaussian density matrices. The authors find a linear transformation which maps the two annihilation operators, one for each mode, into two new annihilation operators that are uncorrelated and unsqueezed. This allows the authors to express the density matrix as a product of two 1-mode density matrices. The authors find general conditions under which 2-mode Gaussian density matrices become pure states. Possible pure states include the 2-mode squeezed pure states commonly mentioned in the literature, plus other pure states never mentioned before. The authors discuss the entropy and thermodynamic laws (Second Law, Fundamental Equation, and Gibbs-Duhem Equation) for the 2-mode states being considered

Transformation and Modes of Production

DEFF Research Database (Denmark)

Høst, Jeppe Engset

2015-01-01

modes of production and examine the ways of life that are enabled by the two modes of production. The central questions are around how market-based fisheries management transforms the principal preconditions for the self-employed fishers; and, in turn, why capitalist organized large-scale fisheries......The introduction of private and individual transferable quotas is widely considered to have a negative impact on small- and medium-sized fishing operations. In this chapter, I set out to explore this in a theoretical manner. I discuss the differences in the fishing operations as two contrasting...

Hybrid-mode interleaved boost converter design for fuel cell electric vehicles

International Nuclear Information System (INIS)

Wen, Huiqing; Su, Bin

2016-01-01

Highlights: • A high power interleaved boost converter is designed for a 150 kW high-power fuel cell electric vehicle application. • A hybrid-mode scheme is used: Mode I and mode II are used with each boost converter operating in continuous conduction mode and discontinuous conduction mode. • Boundary conditions for different modes are determined with respect to switching duty ratio and load conditions. • With the proposed scheme, the power density is improved by 44.2% and 34.3% in terms of the converter volume and weight. - Abstract: For Fuel Cell Electric Vehicles, DC-DC power converters are essential to provide energy storage buffers between fuel cell stacks and the traction system because fuel cells show characteristics of low-voltage high-current output and wide output voltage variation. This paper presents a hybrid-mode two-phase interleaved boost converter for fuel cell electric vehicle application in order to improve the power density, minimize the input current ripple, and enhance the system efficiency. Two operation modes are adopted in the practical design: mode I and mode II are used with each boost converter operating in continuous conduction mode and discontinuous conduction mode. The operation, design and control of the interleaved boost converter for different operating modes are discussed with their equivalent circuits. The boundary conditions are distinguished with respect to switching duty ratio and load conditions. Transitions between continuous conduction mode and discontinuous conduction mode are illustrated for the whole duty ratio range. The expressions for inductor current ripple, input current ripple and output voltage ripple are derived and verified by simulation and experimental tests. The efficiency and power density improvements are illustrated to verify the effectiveness of the proposed design scheme.

Synergy, a co-operative innovation for joint operations

International Nuclear Information System (INIS)

Todd, C.; Feuchtwanger, T.; Moberg, R.; Lesser, L.

1993-01-01

Industry cooperation in the operation of the large Swan Hills oil field in western Alberta is described. Declining production and increasing costs required innovative approaches to field operation. Traditional operation involved one operator making the majority of decisions with funding controlled by numerous non-operating joint owners, and can suffer from interaction problems due to the inherenty competitive nature of the petroleum industry. The new mode of operation stresses trust, cooperation, teamwork, resource sharing, and continuous improvement. The synergy involves sharing best practices, information, knowledge and expertise, combining resources, and standardizing procedures and specifications. The new mode of operation has resulted in an improved performance of up to 15%. The cooperation lessons learnt at Swan Hills may have broad application across the petroleum industry. 6 refs., 6 figs

ITER-FEAT operation

International Nuclear Information System (INIS)

Shimomura, Y.; Huget, M.; Mizoguchi, T.; Murakami, Y.; Polevoi, A.; Shimada, M.; Aymar, R.; Chuyanov, V.; Matsumoto, H.

2001-01-01

ITER is planned to be the first fusion experimental reactor in the world operating for research in physics and engineering. The first 10 years' operation will be devoted primarily to physics issues at low neutron fluence and the following 10 years' operation to engineering testing at higher fluence. ITER can accommodate various plasma configurations and plasma operation modes such as inductive high Q modes, long pulse hybrid modes, non-inductive steady-state modes, with large ranges of plasma current, density, beta and fusion power, and with various heating and current drive methods. This flexibility will provide an advantage for coping with uncertainties in the physics database, in studying burning plasmas, in introducing advanced features and in optimizing the plasma performance for the different programme objectives. Remote sites will be able to participate in the ITER experiment. This concept will provide an advantage not only in operating ITER for 24 hours per day but also in involving the world-wide fusion communities and in promoting scientific competition among the Parties. (author)

ITER-FEAT operation

International Nuclear Information System (INIS)

Shimomura, Y.; Huguet, M.; Mizoguchi, T.; Murakami, Y.; Polevoi, A.R.; Shimada, M.; Aymar, R.; Chuyanov, V.A.; Matsumoto, H.

2001-01-01

ITER is planned to be the first fusion experimental reactor in the world operating for research in physics and engineering. The first ten years of operation will be devoted primarily to physics issues at low neutron fluence and the following ten years of operation to engineering testing at higher fluence. ITER can accommodate various plasma configurations and plasma operation modes, such as inductive high Q modes, long pulse hybrid modes and non-inductive steady state modes, with large ranges of plasma current, density, beta and fusion power, and with various heating and current drive methods. This flexibility will provide an advantage for coping with uncertainties in the physics database, in studying burning plasmas, in introducing advanced features and in optimizing the plasma performance for the different programme objectives. Remote sites will be able to participate in the ITER experiment. This concept will provide an advantage not only in operating ITER for 24 hours a day but also in involving the worldwide fusion community and in promoting scientific competition among the ITER Parties. (author)

High energy, single frequency, tunable laser source operating in burst mode for space based lidar applications

Science.gov (United States)

Cosentino, Alberto; Mondello, Alessia; Sapia, Adalberto; D'Ottavi, Alessandro; Brotini, Mauro; Gironi, Gianna; Suetta, Enrico

2017-11-01

This paper describes energetic, spatial, temporal and spectral characterization measurements of the Engineering Qualification Model (EQM) of the Laser Transmitter Assembly (TXA) used in the ALADIN instrument currently under development for the ESA ADM-AEOLUS mission (EADS Astrium as prime contractor for the satellite and the instrument). The EQM is equivalent to the Flight Model, with the exception of some engineering grade components. The Laser Transmitter Assembly, based on a diode pumped tripled Nd:YAG laser, is used to generate laser pulses at a nominal wavelength of 355 nm. This laser is operated in burst mode, with a pulse repetition cycle of 100 Hz during bursts. It is capable to operate in Single Longitudinal Mode and to be tuned over 25 GHz range. An internal "network" of sensors has been implemented inside the laser architecture to allow "in flight" monitoring of transmitter. Energy in excess of 100 mJ, with a spatial beam quality factor (M2) lower than 3, a spectral linewidth less than 50 MHz with a frequency stability better than 4 MHz on short term period have been measured on the EQM. Most of the obtained results are well within the expected values and match the Instrument requirements. They constitute an important achievement, showing the absence of major critical areas in terms of performance and the capability to obtain them in a rugged and compact structure suitable for space applications. The EQM will be submitted in the near future to an Environmental test campaign.

Analysis of doubly-fed induction machine operating at motoring mode subjected to voltage sag

Directory of Open Access Journals (Sweden)

Navneet Kumar

2016-09-01

Full Text Available Variable Speed (VS Pumped Storage Plants (PSP equipped with large asynchronous (Doubly-Fed Induction machines are emerging now in hydropower applications. Motoring mode of operation of Doubly-Fed Induction Machine (DFIM is essential and techno-economical in this application due to: (1 its uniqueness in active power controllability, (2 bulk power handing capability with less rated power converters in rotor circuit, and (3 integrating Renewable Energy Sources (RES. This paper investigates the performance of two DFIMs at different power ratings (2.2 kW and 2 MW under voltage sag with different attribute. The test results are analyzed in terms of the peaks in torque, speed, power taken and transient currents in rotor and stator circuits. During sag, stable region for DFIM operation along with speed and stator side reactive power input control is also illustrated. The negative effects of voltage sag are briefly discussed. MATLAB simulation is validated with experimentation. The various observations during simulation and experimental analysis are also supported by the theoretical explanations.

Representing Operational Modes for Situation Awareness

DEFF Research Database (Denmark)

Kirchhübel, Denis; Lind, Morten; Ravn, Ole

2017-01-01

reasonable reactions to abnormal situations. Intelligent computational support tools can make the operator's task easier, but they require knowledge about the overall system in form of some model. While tools used for fault-tolerant control design based on physical principles and relations are valuable tools...... for designing robust systems, the models become too complex when considering the interactions on a plant-wide level. The alarm systems meant to support human operators in the diagnosis of the plant-wide situation on the other hand fail regularly in situations where these interactions of systems lead to many...... the interconnected systems can be inferred and alarm floods can potentially be reduced to their root-cause. However, the desired behaviour of a complex system changes due to operating procedures that require more than one physical and functional configuration. In this paper a consistent representation of possible...

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

Directory of Open Access Journals (Sweden)

Jinhaeng Jang

2015-06-01

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

Combustion mode switching with a turbocharged/supercharged engine

Science.gov (United States)

Mond, Alan; Jiang, Li

2015-09-22

A method for switching between low- and high-dilution combustion modes in an internal combustion engine having an intake passage with an exhaust-driven turbocharger, a crankshaft-driven positive displacement supercharger downstream of the turbocharger and having variable boost controllable with a supercharger bypass valve, and a throttle valve downstream of the supercharger. The current combustion mode and mass air flow are determined. A switch to the target combustion mode is commanded when an operating condition falls within a range of predetermined operating conditions. A target mass air flow to achieve a target air-fuel ratio corresponding to the current operating condition and the target combustion mode is determined. The degree of opening of the supercharger bypass valve and the throttle valve are controlled to achieve the target mass air flow. The amount of residual exhaust gas is manipulated.

Rotary Mode Core Sample System availability improvement

International Nuclear Information System (INIS)

Jenkins, W.W.; Bennett, K.L.; Potter, J.D.; Cross, B.T.; Burkes, J.M.; Rogers, A.C.

1995-01-01

The Rotary Mode Core Sample System (RMCSS) is used to obtain stratified samples of the waste deposits in single-shell and double-shell waste tanks at the Hanford Site. The samples are used to characterize the waste in support of ongoing and future waste remediation efforts. Four sampling trucks have been developed to obtain these samples. Truck I was the first in operation and is currently being used to obtain samples where the push mode is appropriate (i.e., no rotation of drill). Truck 2 is similar to truck 1, except for added safety features, and is in operation to obtain samples using either a push mode or rotary drill mode. Trucks 3 and 4 are now being fabricated to be essentially identical to truck 2

Operating experience feedback report - Solenoid-operated valve problems

International Nuclear Information System (INIS)

Ornstein, H.L.

1991-02-01

This report highlights significant operating events involving observed or potential common-mode failures of solenoid-operated valves (SOVs) in US plants. These events resulted in degradation or malfunction of multiple trains of safety systems as well as of multiple safety systems. On the basis of the evaluation of these events, the Office for Analysis and Evaluation of Operational Data (AEOD) of the US Nuclear Regulatory Commission (NRC) concludes that the problems with solenoid-operated valves are an important issue that needs additional NRC and industry attention. This report also provides AEOD's recommendations for actions to reduce the occurrence of SOV common-mode failures. 115 refs., 7 figs., 2 tabs

Operational limits of high density H-modes in ASDEX Upgrade

International Nuclear Information System (INIS)

Mertens, V.; Borrass, K.; Kaufmann, M.; Lang, P.T.; Lang, R.; Mueller, H.W.; Neuhauser, J.; Schneider, R.; Schweinzer, J.; Suttrop, W.

2001-01-01

Systematic investigations of H-mode density limit (H→L-mode back transition) plasmas with gas fuelling and alternatively with additional pellet injection from the magnetic high-field-side HFS are being performed in the new closed divertor configuration DV-II. The resulting database covering a wide range of the externally controllable plasma parameters I p , B t and P heat confirms that the H-mode threshold power exceeds the generally accepted prediction P L→H heat ∝B-bar t dramatically when one approaches Greenwald densities. Additionally, in contrast to the Greenwald scaling a moderate B t -dependence of the H-mode density limit is found. The limit is observed to coincide with divertor detachment and a strong increase of the edge thermal transport, which has, however, no detrimental effect on global τ E . The pellet injection scheme from the magnetic high-field-side HFS, developed recently on ASDEX Upgrade, leads to fast particle drifts which are, contrary to the standard injection from the low-field-side, directed into the plasma core. This improves markedly the pellet particle fuelling efficiency. The responsible physical mechanism, the diamagnetic particle drift of the pellet ablatant was successfully verified recently. Other increased particle losses on respectively different time scales after the ablation process, however, still persist. Generally, a clear gain in achievable density and plasma stored energy is achieved with stationary HFS pellet injection compared to gas-puffing. (author)

Pellet fuelling and ELMy H-mode physics at JET

International Nuclear Information System (INIS)

Horton, L.D.

2001-01-01

As the reference operating regime for ITER, investigations of the ELMy H-mode have received high priority in the JET experimental programme. Recent experiments have concentrated in particular on operation simultaneously at high density and high confinement using high field side (HFS) pellet launch. The enhanced fuelling efficiency of HFS pellet fuelling is found to scale favourably to a large machine such as JET. The achievable density of ELMy H-mode plasmas in JET has been significantly increased using HFS fuelling although at the expense of confinement degradation back to L-mode levels. Initial experiments using control of the pellet injection frequency have shown that density and confinement can simultaneously be increased close to the values necessary for ITER. The boundaries of the available ELMy H-mode operational space have also been extensively explored. The power necessary to maintain the high confinement normally associated with ELMy H-mode operation is found to be substantially higher than the H-mode threshold power. The compatibility of ELMy H-modes with divertor operation acceptable for a fusion device has been studied. Narrow energy scrape-off widths are measured which place stringent limits on divertor power handling. Deuterium and tritium codeposition profiles are measured to be strongly in/out asymmetric. Successful modelling of these profiles requires the inclusion of the (measured) scrape-off layer flows and of the production in the divertor of hydrocarbon molecules with sticking coefficients below unity. Helium exhaust and compression are found to be within the limits sufficient for a reactor. (author)

MODELING OF OPERATION MODES OF SHIP POWER PLANT OF COMBINED PROPULSION COMPLEX WITH CONTROL SYSTEM BASED ON ELECTRONIC CONTROLLERS

Directory of Open Access Journals (Sweden)

E. A. Yushkov

2016-12-01

Full Text Available Purpose. Designing of diagrams to optimize mathematic model of the ship power plant (SPP combined propulsion complexes (CPC for decreasing operational loss and increasing fuel efficiency with simultaneous load limiting on medium revolutions diesel generator (MRDG by criterion reducing of wear and increasing operation time between repairs. Methodology. After analyzing of ship power plant modes of CPC proposed diagrams to optimize mathematic model of the above mentioned complex. The model based on using of electronic controllers in automatic regulation and control systems for diesel and thruster which allow to actualize more complicated control algorithm with viewpoint of increasing working efficiency of ship power plant at normal and emergency modes. Results. Determined suitability of comparative computer modeling in MatLab Simulink for building of imitation model objects based on it block diagrams and mathematic descriptions. Actualized diagrams to optimize mathematic model of the ship’s power plant (SPP combined propulsion complexes (CPC with Azipod system in MatLab Simulink software package Ships_CPC for decreasing operational loss and increasing fuel efficiency with simultaneous load limiting on medium revolutions diesel generator (MRDG by criterion reducing of wear and increasing operation time between repairs. The function blocks of proposed complex are the main structural units which allow to investigate it normal and emergency modes. Originality. This model represents a set of functional blocks of the components SPP CPC, built on the principle of «input-output». For example, the function boxes outputs of PID-regulators of MRDG depends from set excitation voltage and rotating frequency that in turn depends from power-station load and respond that is a ship moving or dynamically positioning, and come on input (inputs of thruster rotating frequency PID-regulator models. Practical value. The results of researches planned to use in

A high-order mode extended interaction klystron at 0.34 THz

Science.gov (United States)

Wang, Dongyang; Wang, Guangqiang; Wang, Jianguo; Li, Shuang; Zeng, Peng; Teng, Yan

2017-02-01

We propose the concept of high-order mode extended interaction klystron (EIK) at the terahertz band. Compared to the conventional fundamental mode EIK, it operates at the TM31-2π mode, and its remarkable advantage is to obtain a large structure and good performance. The proposed EIK consists of five identical cavities with five gaps in each cavity. The method is discussed to suppress the mode competition and self-oscillation in the high-order mode cavity. Particle-in-cell simulation demonstrates that the EIK indeed operates at TM31-2π mode without self-oscillation while other modes are well suppressed. Driven by the electron beam with a voltage of 15 kV and a current of 0.3 A, the saturation gain of 43 dB and the output power of 60 W are achieved at the center frequency of 342.4 GHz. The EIK operating at high-order mode seems a promising approach to generate high power terahertz waves.

A safety equipment list for rotary mode core sampling systems operation in single shell flammable gas tanks; TOPICAL

International Nuclear Information System (INIS)

SMALLEY, J.L.

1999-01-01

This document identifies all interim safety equipment to be used for rotary mode core sampling of single-shell flammable gas tanks utilizing Rotary Mode Core Sampling systems (RMCS). This document provides the safety equipment for RMCS trucks HO-68K-4600, HO-68K-4647, trucks three and four respectively, and associated equipment. It is not intended to replace or supersede WHC-SD-WM-SEL-023, (Kelly 1991), or WHC-SD-WM-SEL-032, (Corbett 1994), which classifies 80-68K-4344 and HO-68K-4345 respectively. The term ''safety equipment'' refers to safety class (SC) and safety significant (SS) equipment, where equipment refers to structures, systems and components (SSC's). The identification of safety equipment in this document is based on the credited design safety features and analysis contained in the Authorization Basis (AB) for rotary mode core sampling operations in single-shell flammable gas tanks. This is an interim safety classification since the AB is interim. This document will be updated to reflect the final RMCS equipment safety classification designations upon completion of a final AB which will be implemented with the release of the Final Safety Analysis Report (FSAR)

A novel mode-locking technique

International Nuclear Information System (INIS)

Chen Shaoh; Chen Youming; Chen Taolue; Si Xiangdong; Yang Yi; Deng Ximing

1993-01-01

A novel mode-locked Nd:YAG oscillator has been developed by using an ultrafast photoconductive feedback controlled loop, and mode-locked pulses with a duration of 100ps have been obtained. The energy instability of the pulse trains is ±5%. In this type of mode-locking technology, a type of deep-level doped GaAs (Cr-doped) photoconductive switch, which has a fast response in time and is free of avalance process, is used to drive a Pockels' cell to realize mode-locking. The dark resistance of this type of photoconductive switch is 6 orders of magnitude higher than that of the intrinsic single-crystal silicon, and it can reach a level as high as 10 9 ohms. Consequently, it is able to withstand longterm operation at several thousand DC volts. By means of the photoconductive ohmic switch characteristics, the authors have designed a positive feedback control network which has a very fast response time, and can couple a voltage of up to a thousand volts. Using this unit in a Nd:YAG laser, they have successfully realized a very stable mode-locked pulse train with pulse width shorter than 100 ps. The operation principle, and the results of the preliminary experiments are presented here. 1 ref., 3 figs

Residential CCHP microgrid with load aggregator: Operation mode, pricing strategy, and optimal dispatch

International Nuclear Information System (INIS)

Gu, Wei; Lu, Shuai; Wu, Zhi; Zhang, Xuesong; Zhou, Jinhui; Zhao, Bo; Wang, Jun

2017-01-01

Highlights: •A bilateral transaction mode for the residential CCHP microgrid is proposed. •An energy pricing strategy for the residential CCHP system is proposed. •A novel integrated demand response for the residential loads is proposed. •Two-stage operation optimization model for the CCHP microgrid is proposed. •Operations of typical days and annual scale of the CCHP microgrid are studied. -- Abstract: As the global energy crisis, environmental pollution, and global warming grow in intensity, increasing attention is being paid to combined cooling, heating, and power (CCHP) systems that realize high-efficiency cascade utilization of energy. This paper proposes a bilateral transaction mechanism between a residential CCHP system and a load aggregator (LA). The variable energy cost of the CCHP system is analyzed, based on which an energy pricing strategy for the CCHP system is proposed. Under this pricing strategy, the electricity price is constant, while the heat/cool price is ladder-shaped and dependent on the relationship between the electrical, heat, and cool loads. For the LA, an integrated demand response program is proposed that combines electricity-load shifting and a flexible heating/cooling supply, in which a thermodynamic model of buildings is used to determine the appropriate range of heating/cooling supply. Subsequently, a two-stage optimal dispatch model is proposed for the energy system that comprises the CCHP system and the LA. Case studies consisting of three scenarios (winter, summer, and excessive seasons) are delivered to demonstrate the effectiveness of the proposed approach, and the performance of the proposed pricing strategy is also evaluated by annual operation simulations.

Integrated simulations of H-mode operation in ITER including core fuelling, divertor detachment and ELM control

Science.gov (United States)

Polevoi, A. R.; Loarte, A.; Dux, R.; Eich, T.; Fable, E.; Coster, D.; Maruyama, S.; Medvedev, S. Yu.; Köchl, F.; Zhogolev, V. E.

2018-05-01

ELM mitigation to avoid melting of the tungsten (W) divertor is one of the main factors affecting plasma fuelling and detachment control at full current for high Q operation in ITER. Here we derive the ITER operational space, where ELM mitigation to avoid melting of the W divertor monoblocks top surface is not required and appropriate control of W sources and radiation in the main plasma can be ensured through ELM control by pellet pacing. We apply the experimental scaling that relates the maximum ELM energy density deposited at the divertor with the pedestal parameters and this eliminates the uncertainty related with the ELM wetted area for energy deposition at the divertor and enables the definition of the ITER operating space through global plasma parameters. Our evaluation is thus based on this empirical scaling for ELM power loads together with the scaling for the pedestal pressure limit based on predictions from stability codes. In particular, our analysis has revealed that for the pedestal pressure predicted by the EPED1  +  SOLPS scaling, ELM mitigation to avoid melting of the W divertor monoblocks top surface may not be required for 2.65 T H-modes with normalized pedestal densities (to the Greenwald limit) larger than 0.5 to a level of current of 6.5–7.5 MA, which depends on assumptions on the divertor power flux during ELMs and between ELMs that expand the range of experimental uncertainties. The pellet and gas fuelling requirements compatible with control of plasma detachment, core plasma tungsten accumulation and H-mode operation (including post-ELM W transient radiation) have been assessed by 1.5D transport simulations for a range of assumptions regarding W re-deposition at the divertor including the most conservative assumption of zero prompt re-deposition. With such conservative assumptions, the post-ELM W transient radiation imposes a very stringent limit on ELM energy losses and the associated minimum required ELM frequency. Depending on

Linear optical quantum computing in a single spatial mode.

Science.gov (United States)

Humphreys, Peter C; Metcalf, Benjamin J; Spring, Justin B; Moore, Merritt; Jin, Xian-Min; Barbieri, Marco; Kolthammer, W Steven; Walmsley, Ian A

2013-10-11

We present a scheme for linear optical quantum computing using time-bin-encoded qubits in a single spatial mode. We show methods for single-qubit operations and heralded controlled-phase (cphase) gates, providing a sufficient set of operations for universal quantum computing with the Knill-Laflamme-Milburn [Nature (London) 409, 46 (2001)] scheme. Our protocol is suited to currently available photonic devices and ideally allows arbitrary numbers of qubits to be encoded in the same spatial mode, demonstrating the potential for time-frequency modes to dramatically increase the quantum information capacity of fixed spatial resources. As a test of our scheme, we demonstrate the first entirely single spatial mode implementation of a two-qubit quantum gate and show its operation with an average fidelity of 0.84±0.07.

Predictive digital peak current mode controller for DC-DC converters capable of operating over the full 0-100% duty cycle range

DEFF Research Database (Denmark)

Andersen, Karsten Holm; Nymand, Morten

2017-01-01

) and discontinuous conduction mode (DCM) and supports high switching frequencies even with low cost A/D converters. The proposed controller is implemented in a Field Programmable Gate Array (FPGA) to control a 450 W buck converter and the experimental results verify the controller's capability to operate in the full...

Multi-mode interactions in an FEL oscillator

CERN Document Server

Dong Zhi Wei; Masuda, K; Yamazaki, T; Yoshikawa, K

2000-01-01

A 3D time-dependent FEL oscillator simulation code has been developed by using the transverse mode spectral method to analyze interaction among transverse modes. The competition among them in an FEL oscillator was investigated based on the parameters of LANL FEL experiments. It is found that under typical FEL oscillator operation conditions, the TEM sub 0 sub 0 mode is dominant, and the effects of other transverse modes can be negligible.

Feasibility Study of the PS Injection for 2 GeV LIU Beams with an Upgraded KFA-45 Injection Kicker System Operating in Short Circuit Mode

CERN Document Server

Kramer, Thomas; Borburgh, Jan; Ducimetière, Laurent; Feliciano, Luis; Ferrero Colomo, Alvaro; Goddard, Brennan; Sermeus, Luc

2016-01-01

Under the scope of the LIU project the CERN PS Booster to PS beam transfer will be modified to match the requirements for the future 2 GeV beams. This paper describes the evaluation of the proposed upgrade of the PS injection kicker. Different schemes of an injection for LIU beams into the PS have been outlined in the past already under the aspect of individual transfer kicker rise and fall time performances. Homogeneous rise and fall time requirements in the whole PSB to PS transfer chain have been established which allowed to consider an upgrade option of the present injection kicker system operated in short circuit mode. The challenging pulse quality constraints require an improvement of the flat top and post pulse ripples. Both operation modes, terminated and short circuit mode are analysed and analogue circuit simulations for the present and upgraded system are outlined. Recent measurements on the installed kickers are presented and analysed together with the simulation data. First measurements verifying...

Predicting the Diversity of Foreign Entry Modes

DEFF Research Database (Denmark)

Hashai, Niron; Geisler Asmussen, Christian; Benito, Gabriel

2007-01-01

diversity across value chain activities and host markets. Analyzing a sample of Israeli based firms we show that larger firms exhibit a higher degree of entry mode diversity both across value chain activities and across host markets. Higher levels of knowledge intensity are also associated with more......This paper expands entry mode literature by referring to multiple modes exerted in different value chain activities within and across host markets, rather than to a single entry mode at the host market level. Scale of operations and knowledge intensity are argued to affect firms' entry mode...... diversity in firms' entry modes across both dimensions....

Ateities įžvalgos kaip e. valdžios plėtros strateginio planavimo sudedamoji dalis: siūlomas įžvalgų tyrimo proceso modelis

Directory of Open Access Journals (Sweden)

Rokas Grincevičius

2013-01-01

Full Text Available Tikslas – įvertinti įžvalgų poveikį e. valdžios strateginio planavimo procesui, atliekant šią temą nagrinėjančios literatūros bei skirtingų įžvalgų projektų metodikų analizę ir, sintezavus analizės rezultatus, parengti e. valdžios įžvalgų proceso modelį. Metodologija – tyrime taikyti metodai: literatūros apžvalga bei sisteminės analizės metodas. Rezultatai – išnagrinėtas įžvalgų poveikis e. valdžios plėtros procesams, nagrinėjant jį įvairių strateginio planavimo, politinių sprendimų priėmimo dimensijų kontekste, atlikta skirtingų įžvalgų metodikų analizė, remiantis ja, parengtas e. valdžios ateities įžvalgų tyrimo proceso modelis. Tyrimo ribotumas – nepaisant to, kad egzistuoja nemažai bandymų analizuoti e. valdžios strateginį planavimą ir ateities įžvalgas kaip du atskirus fenomenus, tvirtos teorijos, kompleksiškai apimančios abu reiškinius ir atskleidžiančios galimas jų sąveikos ribas, nėra, taigi nėra ir aiškios tyrimo metodologijos. Todėl egzistuoja tam tikra tikimybė, kad, nagrinėjant skirtingas įžvalgų metodikas, galėjo būti parinkti ne visi kintamieji, būtini tiksliam įžvalgų proceso įvertinimui. Praktinė reikšmė – tyrimo rezultatai gali būti taikomi kaip pagrindas organizuojamam įžvalgų proceso projektavimui, jau atlikto tyrimo proceso vertinimui ar siekiant geriau suprasti įžvalgų procesą sudarančius elementus bei jų tarpusavio ryšius. Vertingumas – nepaisant to, kad pasaulinėje prognozavimo praktikoje jau ne pirmus metus egzistuoja priemonės, leidžiančios tinkamai įvertinti ir padėti pasiruošti įvairaus pobūdžio ilgalaikiams iššūkiams, Lietuvoje bei daugelyje kitų Rytų Europos šalių planavimo procesas vis dar vyksta centralizuoto, penkmečiu paremto, planavimo tradicijomis. Dėl šios priežasties buvusio socialistinio bloko valstybės nuo kitų regionų atsilieka e. valdžios ir kitos tematikos ateities �

Monte-Carlo study of ICRF-sustained mode operation in tandem mirrors

Energy Technology Data Exchange (ETDEWEB)

Todd, A.M.M. (Grumman Aerospace Corp., Princeton, NJ (USA))

1984-09-01

A study, using a Monte-Carlo simulation code, of ICRF-sustained mode operation in tandem mirrors by way of ICRF end-cell fuelling and heating is described. Although the basic parameter space considered corresponds to the Phaedrus experiment, the central-cell density and temperatures are extended towards the reactor regime. It is found that significant end cell ion potential barriers can be generated with ICRF, but that, owing to choking of the central-cell ion source stream by the plugging potential, saturation occurs and power requirements rapidly increase, so that the potential rise is limited to about twice the central-cell ion temperature. Although performance is improved as the ion cyclotron resonance approaches the end-cell mid-plane, no significant difference is found between inboard, outboard or double resonance location. As the central-cell density and temperatures are increased, the RF power requirement is found to increase dramatically. Optimum performance for end cell fuelling results when the central-cell electron temperature is higher than the ion temperature, but the magnitude of this ratio is limited by an increase in threshold power level with electron temperature.

Enhanced Sleep Mode MAC Control for EPON

DEFF Research Database (Denmark)

Yan, Ying; Dittmann, Lars

2011-01-01

This paper introduces sleep mode operations for EPON. New MAC control functions are proposed to schedule sleep periods. Traffic profiles are considered to optimize energy efficiency and network performances. Simulation results are analyzed in OPNET modeler.......This paper introduces sleep mode operations for EPON. New MAC control functions are proposed to schedule sleep periods. Traffic profiles are considered to optimize energy efficiency and network performances. Simulation results are analyzed in OPNET modeler....

Study of modes of operation water system movement with bypass system towers cooling by Ecosimpro; Estudio de modos de operacion del sistema de agua de circulacion con sistema de bypass de las torres de refrigeracion mediante Ecosimpro

Energy Technology Data Exchange (ETDEWEB)

Prieto, J.; Molina, M. C.; Gavilan, C.; Molina, J. J.

2013-07-01

The present paper is based on the thermodynamic study of the system of water circulation of the Central Nuclear de Cofrentes. The objective of the study is the operation of the system through different modes of operation, with the aim of analyze the impact of these modes over the operation of the same. For a complete analysis, it has created a computer model of the system through the EcosimPro software, which is the simulation of the operation modes system and through the results, is the analysis of their feasibility.

Fuel element cladding state change mathematical model for a WWER-1000 plant operated in the mode of varying loading

Directory of Open Access Journals (Sweden)

S. N. Pelykh

2010-09-01

Full Text Available Main features of a fuel element cladding state change mathematical model for a WWER-1000 reactor plant operated in the mode of varying loading are listed. The integrated model is based on the energy creep theory, uses the finite element method for imultaneous solution of the fuel element heat conduction and mechanical deformation equa-tions. Proposed mathematical model allows us to determine the influence of the WWER-1000 regime parameters and fuel assembly design characteristics on the change of cladding properties under different loading conditions of normal operation, as well as the cladding limiting state at variable loading depending on the length, depth and number of cycles.

2-LP mode few-mode fiber amplifier employing ring-core erbium-doped fiber.

Science.gov (United States)

Ono, Hirotaka; Hosokawa, Tsukasa; Ichii, Kentaro; Matsuo, Shoichiro; Nasu, Hitoshi; Yamada, Makoto

2015-10-19

A fiber amplifier supporting 2 LP modes that employs a ring-core erbium-doped fiber (RC-EDF) is investigated to reduce differential modal gain (DMG). The inner and outer radii of the ring-core of the RC-EDF are clarified for 2-LP mode operation of the amplifier, and are optimized to reduce the DMG. It is shown that using the overlap integral between the erbium-doped core area and the signal power mode distribution is a good way to optimize the inner and outer radii of the ring-core of the RC-EDF and thus minimize the DMG. A fabricated RC-EDF and a constructed 2-LP mode EDFA are described and a small DMG of around 1 dB is realized for LP01, LP11 and LP21 pumping.

Beta limits in H-modes and VH-modes in JET

Energy Technology Data Exchange (ETDEWEB)

Smeulders, P; Hender, T C; Huysmans, G; Marcus, F; Ali-Arshad, S; Alper, B; Balet, B; Bures, M; Deliyanakis, N; Esch, H de; Fshpool, G; Jarvis, O N; Jones, T T.C.; Ketner, W; Koenig, R; Lawson, K; Lomas, P; O` Brien, D; Sadler, G; Stok, D; Stubberfield, P; Thomas, P; Thomen, K; Wesson, J [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Nave, M F [Universidade Tecnica, Lisbon (Portugal). Inst. Superior Tecnico

1994-07-01

In Hot-ion H- and VH-modes, the highest achieved beta was about 10% below the Troyon value in the best case of discharge 26087. The operational space of the high beta discharges obtained before March 1992 has been explored as function of the parameters H{sub ITER89P}, {beta}{sub n}, q{sub 95}, I{sub p}. Also, a limiting envelope on the fusion reactivity as a function of the average plasma pressure and beta has been observed with R{sub DD} related to {beta}{sub {phi}}{sup 2}.B{sub {phi}}{sup 4}. MHD stability analysis shows that the JET VH modes at the edge are in the second region for ballooning mode stability. The dependence of ballooning stability and the n=1 external kink on the edge current density is analyzed. (authors). 6 figs., 6 refs.

Efficacy of the fractional photothermolysis system with dynamic operating mode on acne scars and enlarged facial pores.

Science.gov (United States)

Cho, Sung Bin; Lee, Ju Hee; Choi, Moon Jung; Lee, Kyu-Yeop; Oh, Sang Ho

2009-01-01

Current treatments for acne scars and enlarged facial pores have shown limited efficacy. To evaluate the efficacy and safety of the fractional photothermolysis system (FPS) with dynamic operating mode on acne scars and enlarged pores. Twelve patients with mild to moderate atrophic acne scars and enlarged pores were included in this study. Three sessions of FPS treatment were performed for acne scars and facial pores monthly. Two blinded dermatologists who compared before and after photos based on a quartile grading scale conducted objective clinical assessments of acne scar- and facial pore-treated areas. We took a biopsy immediately after one treatment with the laser from one of the authors to assess the histologic effects of the laser on facial pores. Follow-up results at 4 months after the last treatment revealed that, of the 12 patients, for acne scars, five demonstrated clinical improvements of 51% to 75% and three demonstrated improvements of 76% to 100%, and for facial pores, five demonstrated moderate clinical improvements of 26% to 50% and three demonstrated improvements of 76% to 100%. Side effects, including pain, post-treatment erythema, and edema, were resolved within 1 week. We suggest that the FPS may provide a new treatment algorithm in some cases with acne scars and enlarged pores. Considering the lack of placebo-controlled, split-face design of our study, optimized, prospective studies should be conducted to fully assess the efficacy of FPS with dynamic operating mode.

Mathematical modeling analysis of regenerative solid oxide fuel cells in switching mode conditions

Science.gov (United States)

Jin, Xinfang; Xue, Xingjian

A 2D transient mathematical model is developed for regenerative solid oxide cells operated in both SOFC mode and SOEC mode. The steady state performance of the model is validated using experimental results of in-house prepared NiO-YSZ/YSZ/LSM cell under different operating temperatures. The model is employed to investigate complicated multi-physics processes during the transient process of mode switching. Simulation results indicate that the trend of internal parameter distributions, including H 2/O 2/H 2O and ionic potentials, flip when the operating cell is switched from one mode to another. However, the electronic potential shows different behaviors. At H 2 electrode, electronic potential keeps at zero voltage level, while at O 2 electrode, it increases from a relatively low level in SOFC mode to a relatively high level in SOEC mode. Transient results also show that an overshooting phenomenon occurs for mass fraction distribution of water vapor at H 2 side when the operating cell switches from SOFC mode to SOEC mode. The mass fractions of O 2 and H 2 as well as charge (electrons and ions) potentials may quickly follow the operating mode changes without over-shootings. The simulation results facilitate the internal mechanism understanding for regenerative SOFCs.

DBD plasma source operated in single-filamentary mode for therapeutic use in dermatology

Energy Technology Data Exchange (ETDEWEB)

Rajasekaran, Priyadarshini; Mertmann, Philipp; Bibinov, Nikita; Awakowicz, Peter [Institute for Electrical Engineering and Plasma Technology, Ruhr-Universitaet Bochum, Universitaetsstr. 150, 44801 Bochum (Germany); Wandke, Dirk [CINOGY GmbH, Max-Naeder-Str. 15, 37114 Duderstadt (Germany); Vioel, Wolfgang, E-mail: rajasekaran@aept.rub.d, E-mail: mertmann@aept.rub.d, E-mail: Nikita.Bibinov@rub.d, E-mail: dirk.wandke@cinogy.co, E-mail: vioel@hawk-hhg.d, E-mail: awakowicz@aept.rub.d [University of Applied Sciences and Arts, Faculty of Natural Sciences and Technology, Von-Ossietzky-Str. 99, 37085 Goettingen (Germany)

2009-11-21

Our dielectric barrier discharge (DBD) plasma source for bio-medical application comprises a copper electrode covered with ceramic. Objects of high capacitance such as the human body can be used as the opposite electrode. In this study, the DBD source is operated in single-filamentary mode using an aluminium spike as the opposite electrode, to imitate the conditions when the discharge is ignited on a raised point, such as hair, during therapeutic use on the human body. The single-filamentary discharge thus obtained is characterized using optical emission spectroscopy, numerical simulation, voltage-current measurements and microphotography. For characterization of the discharge, averaged plasma parameters such as electron distribution function and electron density are determined. Fluxes of nitric oxide (NO), ozone (O{sub 3}) and photons reaching the treated surface are simulated. The calculated fluxes are finally compared with corresponding fluxes used in different bio-medical applications.

Probabilistic safety assessments of nuclear power plants for low power and shutdown modes

International Nuclear Information System (INIS)

2000-03-01

Within the past several years the results of nuclear power plant operating experience and performance of probabilistic safety assessments (PSAs) for low power and shutdown operating modes have revealed that the risk from operating modes other than full power may contribute significantly to the overall risk from plant operations. These early results have led to an increased focus on safety during low power and shutdown operating modes and to an increased interest of many plant operators in performing shutdown and low power PSAs. This publication was developed to provide guidance and insights on the performance of PSA for shutdown and low power operating modes. The preparation of this publication was initiated in 1994. Two technical consultants meetings were conducted in 1994 and one in February 1999 in support of the development of this report

Analysis of Energy Transmission Modes of Flyback Converter

Directory of Open Access Journals (Sweden)

GONG Shu

2014-08-01

Full Text Available It is of significance to investigate energy transmission modes of a flyback converter for its optimum design. In this paper, the ETMs of a flyback converter are divided into three modes, which are continuous conduction mode-complete inductor supply mode, continuous conduction mode- incomplete inductor supply mode and discontinuous conduction mode-incomplete inductor supply mode, respectively. A deep analysis of the operation is made, a reduction of the boundary condition between the modes is conducted and a comparison of current stress, transformer AP and output ripple voltage between the modes is performed. A 30W prototype is developed and its experiment is done. The experiment results are in agreement with the theoretical analysis quite well.

Data-processing program from the operating modes of the nuclear reactor (P0DER)

International Nuclear Information System (INIS)

Totev, T.L.; Boyadzhiev, A.I.

1981-01-01

A program PODER for processing data from the operating modes of the reactors taking into account the effects of corrosion, hydration, and deformation of the nuclear reactor fuel element sheathing, the formation of the corrosion product deposits, the change in the geometric dimensions of the nuclear reactor fuel element due to the temperature deformation, as well as the various gas fillers, are elaborated. The ''hot channel'' method determining the reliability of the system is realized. The basic equations describing the thermohydraulic processes in nuclear reactors are solved by the finite difference method. Approximations are carried out with the approach of least squares. The temperature distribution versus the zirconium sheathing height is computed for the case of WWER-440 type reactors. The advantages of the proposed program P0DER are discussed

Study on variance-to-mean method as subcriticality monitor for accelerator driven system operated with pulse-mode

International Nuclear Information System (INIS)

Yamauchi, Hideto; Kitamura, Yasunori; Yamane, Yoshihiro; Misawa, Tsuyoshi; Unesaki, Hironobu

2003-01-01

Two types of the variance-to-mean methods for the subcritical system that was driven by the periodic and pulsed neutron source were developed and their experimental examination was performed with the Kyoto University Critical Assembly and a pulsed neutron generator. As a result, it was demonstrated that the prompt neutron decay constant could be measured by these methods. From this fact, it was concluded that the present variance-to-mean methods had potential for being used in the subcriticality monitor for the future accelerator driven system operated with the pulse-mode. (author)

Edge-localized mode avoidance and pedestal structure in I-mode plasmas

Energy Technology Data Exchange (ETDEWEB)

Walk, J. R., E-mail: jrwalk@psfc.mit.edu; Hughes, J. W.; Hubbard, A. E.; Terry, J. L.; Whyte, D. G.; White, A. E.; Baek, S. G.; Reinke, M. L.; Theiler, C.; Churchill, R. M.; Rice, J. E. [MIT Plasma Science and Fusion Center, Cambridge, MA 02139-4307 (United States); Snyder, P. B.; Osborne, T. [General Atomics, San Diego, CA 92186-5608 (United States); Dominguez, A [Princeton Plasma Physics Laboratory, Princeton, NJ 08543-0451 (United States); Cziegler, I. [UCSD Center for Momentum Transport and Flow Organization, La Jolla, CA 92093-0417 (United States)

2014-05-15

I-mode is a high-performance tokamak regime characterized by the formation of a temperature pedestal and enhanced energy confinement, without an accompanying density pedestal or drop in particle and impurity transport. I-mode operation appears to have naturally occurring suppression of large Edge-Localized Modes (ELMs) in addition to its highly favorable scalings of pedestal structure and overall performance. Extensive study of the ELMy H-mode has led to the development of the EPED model, which utilizes calculations of coupled peeling-ballooning MHD modes and kinetic-ballooning mode (KBM) stability limits to predict the pedestal structure preceding an ELM crash. We apply similar tools to the structure and ELM stability of I-mode pedestals. Analysis of I-mode discharges prepared with high-resolution pedestal data from the most recent C-Mod campaign reveals favorable pedestal scalings for extrapolation to large machines—pedestal temperature scales strongly with power per particle P{sub net}/n{sup ¯}{sub e}, and likewise pedestal pressure scales as the net heating power (consistent with weak degradation of confinement with heating power). Matched discharges in current, field, and shaping demonstrate the decoupling of energy and particle transport in I-mode, increasing fueling to span nearly a factor of two in density while maintaining matched temperature pedestals with consistent levels of P{sub net}/n{sup ¯}{sub e}. This is consistent with targets for increased performance in I-mode, elevating pedestal β{sub p} and global performance with matched increases in density and heating power. MHD calculations using the ELITE code indicate that I-mode pedestals are strongly stable to edge peeling-ballooning instabilities. Likewise, numerical modeling of the KBM turbulence onset, as well as scalings of the pedestal width with poloidal beta, indicates that I-mode pedestals are not limited by KBM turbulence—both features identified with the trigger for large ELMs

Pedestal structure and stability in H-mode and I-mode: a comparative study on Alcator C-Mod

International Nuclear Information System (INIS)

Hughes, J.W.; Walk, J.R.; Davis, E.M.; LaBombard, B.; Baek, S.G.; Churchill, R.M.; Greenwald, M.; Hubbard, A.E.; Lipschultz, B.; Marmar, E.S.; Reinke, M.L.; Rice, J.E.; Theiler, C.; Terry, J.; White, A.E.; Whyte, D.G.; Snyder, P.B.; Groebner, R.J.; Osborne, T.; Diallo, A.

2013-01-01

New experimental data from the Alcator C-Mod tokamak are used to benchmark predictive modelling of the edge pedestal in various high-confinement regimes, contributing to greater confidence in projection of pedestal height and width in ITER and reactors. ELMy H-modes operate near stability limits for ideal peeling–ballooning modes, as shown by calculations with the ELITE code. Experimental pedestal width in ELMy H-mode scales as the square root of β pol at the pedestal top, i.e. the dependence expected from theory if kinetic ballooning modes (KBMs) were responsible for limiting the pedestal width. A search for KBMs in experiment has revealed a short-wavelength electromagnetic fluctuation in the pedestal that is a candidate driver for inter-edge localized mode (ELM) pedestal regulation. A predictive pedestal model (EPED) has been tested on an extended set of ELMy H-modes from C-Mod, reproducing pedestal height and width reasonably well across the data set, and extending the tested range of EPED to the highest absolute pressures available on any existing tokamak and to within a factor of three of the pedestal pressure targeted for ITER. In addition, C-Mod offers access to two regimes, enhanced D-alpha (EDA) H-mode and I-mode, that have high pedestals, but in which large ELM activity is naturally suppressed and, instead, particle and impurity transport are regulated continuously. Pedestals of EDA H-mode and I-mode discharges are found to be ideal magnetohydrodynamic (MHD) stable with ELITE, consistent with the general absence of ELM activity. Invocation of alternative physics mechanisms may be required to make EPED-like predictions of pedestals in these kinds of intrinsically ELM-suppressed regimes, which would be very beneficial to operation in burning plasma devices. (paper)

A discrete model of the development and relaxation of a local microbreakdown in silicon avalanche photodiodes operating in the Geiger mode

International Nuclear Information System (INIS)

Vanyushin, I. V.; Gergel, V. A.; Gontar', V. M.; Zimoglyad, V. A.; Tishin, Yu. I.; Kholodnov, V. A.; Shcheleva, I. M.

2007-01-01

A new discrete theoretical model of the development and relaxation of a local microbreakdown in silicon avalanche photodiodes operating in the Geiger mode is developed. It is shown that the spreading resistance in the substrate profoundly affects both the amplitude of a single-photon electrical pulse and the possibility of attaining the steady-state form of the avalanche breakdown excluding the Geiger mode of the photodiode's operation. The model is employed to interpret the experimental data obtained using test single-photon cells of avalanche photodiodes fabricated on the basis of the 0.25-μm silicon technology with the use of deep implantation to form the region of avalanche multiplication for the charge carriers. Excellent functional properties of the studied type of the single-photon (Geiger) cell are noted. A typical amplitude characteristic of the cell for optical radiation with the wavelength λ = 0.56 μm in the irradiance range of 10 -3 -10 2 lx is presented; this characteristic indicates that the quantum efficiency of photoconversion is extremely high

Segmentation of a Vibro-Shock Cantilever-Type Piezoelectric Energy Harvester Operating in Higher Transverse Vibration Modes

Directory of Open Access Journals (Sweden)

Darius Zizys

2015-12-01

Full Text Available The piezoelectric transduction mechanism is a common vibration-to-electric energy harvesting approach. Piezoelectric energy harvesters are typically mounted on a vibrating host structure, whereby alternating voltage output is generated by a dynamic strain field. A design target in this case is to match the natural frequency of the harvester to the ambient excitation frequency for the device to operate in resonance mode, thus significantly increasing vibration amplitudes and, as a result, energy output. Other fundamental vibration modes have strain nodes, where the dynamic strain field changes sign in the direction of the cantilever length. The paper reports on a dimensionless numerical transient analysis of a cantilever of a constant cross-section and an optimally-shaped cantilever with the objective to accurately predict the position of a strain node. Total effective strain produced by both cantilevers segmented at the strain node is calculated via transient analysis and compared to the strain output produced by the cantilevers segmented at strain nodes obtained from modal analysis, demonstrating a 7% increase in energy output. Theoretical results were experimentally verified by using open-circuit voltage values measured for the cantilevers segmented at optimal and suboptimal segmentation lines.

Evaluation of waste temperatures in AWF tanks for bypass mode operation of the 702-AZ ventilation system (Project W-030)

International Nuclear Information System (INIS)

Sathyanarayana, K.

1997-01-01

This report describes the results of thermal hydraulic analysis performed to provide data in support of Project W-030 to startup new 702-AZ Primary Ventilation System. During the startup of W-030 system, the ventilation system will be operating in bypass mode. In bypass made of operation, the system is capable of supplying 1000 cfm total flow for all four AWF doubleshell tanks. The design of the W-030 system is based on the assumption that both the recirculation loop of the primary ventilation system and the secondary ventilation which provides cooling would be operating. However, during the startup neither the recirculation system nor the secondary ventilation system will be operating. A minimum flow of 100 cfm is required to prevent any flammable gas associated risk. The remaining 600 cfm flow can be divided among the four tanks as necessary to keep the peak sludge temperatures below the operating temperature limit. For the purpose of determining the minimum flow required for cooling each tank, the thermal hydraulic analysis is performed to predict the peak sludge temperatures in AY/AZ tanks under different ventilation flows. The heat load for AZ farm tanks is taken from characterization reports and for the AY farm tanks, the heat load was estimated by thermal analysis using the measured waste temperatures and the waste liquid evaporation rates. The tank 241-AZ-101 and the tank 241-AZ-102 have heat loads of 241,600 and 199,500 Btu/hr respectively. The tank 241-AY-101 and tank 241-AY-102 have heat loads of 41,000 and 33,000 Btu/hr respectively. Using the ambient meteorological conditions of temperature and relative humidity for the air and tank, some soil surface and the sludge levels reported in recent documents, the peak sludge and supernatant temperatures were predicted for various primary ventilation flows ranging from 100 to 400 cfm for AZ tanks and 100 and 150 cfm for AY tanks. The results of these thermal hydraulic analyses are presented. Based on the

Small reactor operating mode

International Nuclear Information System (INIS)

Snell, V.G.

1997-01-01

There is a potential need for small reactors in the future for applications such as district heating, electricity production at remote sites, and desalination. Nuclear power can provide these at low cost and with insignificant pollution. The economies required by the small scale application, and/or the remote location, require a review of the size and location of the operating staff. Current concepts range all the way from reactors which are fully automatic, and need no local attention for days or weeks, to those with reduced local staff. In general the less dependent a reactor is on local human intervention, the greater its dependence on intrinsic safety features such as passive decay heat removal, low-stored energy and limited reactivity speed and depth in the control systems. A case study of the design and licensing of the SLOWPOKE Energy System heating reactor is presented. (author)

Operation of LIA-30 linear induction accelerator in the mode of generation of two bremsstrahlung pulses

Energy Technology Data Exchange (ETDEWEB)

Bossamykin, V S; Gerasimov, A I; Gordeev, V S; Grishin, A V; Gritsina, V P; Tarasov, A D; Fedotkin, A S; Lazarev, S A; Averchenkov, A Ya [All-Russian Scientific Research Institute of Experimental Physics, Sarov (Russian Federation)

1997-12-31

The operating mode was studied of the LIA-30 linear induction accelerator ({approx} 40 MeV, {approx} 100 kA, {approx} 30 ns) with the generation of two bremsstrahlung pulses separated by a specified time interval from 0 to 5 {mu}s. In the accelerating channel an additional tube cathode was installed, and a synchronization system for two accelerating module groups triggering the formation and acceleration, at different initial times, of two annular electron beams with different outer diameters was changed. The energy limit of each beam electron acceleration can be controlled, and the energy sum limit is {<=} 540 MeV. (author). 2 tabs., 2 figs.

Helicon normal modes in Proto-MPEX

Science.gov (United States)

Piotrowicz, P. A.; Caneses, J. F.; Green, D. L.; Goulding, R. H.; Lau, C.; Caughman, J. B. O.; Rapp, J.; Ruzic, D. N.

2018-05-01

The Proto-MPEX helicon source has been operating in a high electron density ‘helicon-mode’. Establishing plasma densities and magnetic field strengths under the antenna that allow for the formation of normal modes of the fast-wave are believed to be responsible for the ‘helicon-mode’. A 2D finite-element full-wave model of the helicon antenna on Proto-MPEX is used to identify the fast-wave normal modes responsible for the steady-state electron density profile produced by the source. We also show through the simulation that in the regions of operation in which core power deposition is maximum the slow-wave does not deposit significant power besides directly under the antenna. In the case of a simulation where a normal mode is not excited significant edge power is deposited in the mirror region. ).

Resonance Excitation of Longitudinal High Order Modes in Project X Linac

Energy Technology Data Exchange (ETDEWEB)

Khabiboulline, T.N.; Sukhanov, A.AUTHOR = Awida, M.; Gonin, I.; Lunin, A.AUTHOR = Solyak, N.; Yakovlev, V.; /Fermilab

2012-05-01

Results of simulation of power loss due to excitation of longitudinal high order modes (HOMs) in the accelerating superconducting RF system of CW linac of Project X are presented. Beam structures corresponding to the various modes of Project X operation are considered: CW regime for 3 GeV physics program; pulsed mode for neutrino experiments; and pulsed regime, when Project X linac operates as a driver for Neutrino Factory/Muon Collider. Power loss and associated heat load due to resonance excitation of longitudinal HOMs are shown to be small in all modes of operation. Conclusion is made that HOM couplers can be removed from the design of superconducting RF cavities of Project X linac.

Resonance Excitation of Longitudinal High Order Modes in Project X Linac

International Nuclear Information System (INIS)

Gonin, I.V.; Khabiboulline, T.N.; Lunin, A.; Solyak, N.; Sukhanov, A.I.; Yakovlev, V.P.; Awida, M.H.

2012-01-01

Results of simulation of power loss due to excitation of longitudinal high order modes (HOMs) in the accelerating superconducting RF system of CW linac of Project X are presented. Beam structures corresponding to the various modes of Project X operation are considered: CW regime for 3 GeV physics program; pulsed mode for neutrino experiments; and pulsed regime, when Project X linac operates as a driver for Neutrino Factory/Muon Collider. Power loss and associated heat load due to resonance excitation of longitudinal HOMs are shown to be small in all modes of operation. Conclusion is made that HOM couplers can be removed from the design of superconducting RF cavities of Project X linac.

Pulse oximeter using a gain-modulated avalanche photodiode operated in a pseudo lock-in light detection mode

Science.gov (United States)

Miyata, Tsuyoshi; Iwata, Tetsuo; Araki, Tsutomu

2006-01-01

We propose a reflection-type pulse oximeter, which employs two pairs of a light-emitting diode (LED) and a gated avalanche photodiode (APD). One LED is a red one with an emission wavelength λ = 635 nm and the other is a near-infrared one with that λ = 945 nm, which are both driven with a pulse mode at a frequency f (=10 kHz). Superposition of a transistor-transistor-logic (TTL) gate pulse on a direct-current (dc) bias, which is set so as not exceeding the breakdown voltage of each APD, makes the APD work in a gain-enhanced operation mode. Each APD is gated at a frequency 2f (=20 kHz) and its output signal is fed into a laboratory-made lock-in amplifier that works in synchronous with the pulse modulation signal of each LED at a frequency f (=10 kHz). A combination of the gated APD and the lock-in like signal detection scheme is useful for the reflection-type pulse oximeter thanks to the capability of detecting a weak signal against a large background (BG) light.

Self-mode-locked AlGaInP-VECSEL

Science.gov (United States)

Bek, R.; Großmann, M.; Kahle, H.; Koch, M.; Rahimi-Iman, A.; Jetter, M.; Michler, P.

2017-10-01

We report the mode-locked operation of an AlGaInP-based semiconductor disk laser without a saturable absorber. The active region containing 20 GaInP quantum wells is used in a linear cavity with a curved outcoupling mirror. The gain chip is optically pumped by a 532 nm laser, and mode-locking is achieved by carefully adjusting the pump spot size. For a pump power of 6.8 W, an average output power of up to 30 mW is reached at a laser wavelength of 666 nm. The pulsed emission is characterized using a fast oscilloscope and a spectrum analyzer, demonstrating stable single-pulse operation at a repetition rate of 3.5 GHz. Intensity autocorrelation measurements reveal a FWHM pulse duration of 22 ps with an additional coherence peak on top, indicating noise-like pulses. The frequency spectrum, as well as the Gaussian beam profile and the measured beam propagation factor below 1.1, shows no influence of higher order transverse modes contributing to the mode-locked operation.

Acceleration Modes and Transitions in Pulsed Plasma Accelerators

Science.gov (United States)

Polzin, Kurt A.; Greve, Christine M.

2018-01-01

Pulsed plasma accelerators typically operate by storing energy in a capacitor bank and then discharging this energy through a gas, ionizing and accelerating it through the Lorentz body force. Two plasma accelerator types employing this general scheme have typically been studied: the gas-fed pulsed plasma thruster and the quasi-steady magnetoplasmadynamic (MPD) accelerator. The gas-fed pulsed plasma accelerator is generally represented as a completely transient device discharging in approximately 1-10 microseconds. When the capacitor bank is discharged through the gas, a current sheet forms at the breech of the thruster and propagates forward under a j (current density) by B (magnetic field) body force, entraining propellant it encounters. This process is sometimes referred to as detonation-mode acceleration because the current sheet representation approximates that of a strong shock propagating through the gas. Acceleration of the initial current sheet ceases when either the current sheet reaches the end of the device and is ejected or when the current in the circuit reverses, striking a new current sheet at the breech and depriving the initial sheet of additional acceleration. In the quasi-steady MPD accelerator, the pulse is lengthened to approximately 1 millisecond or longer and maintained at an approximately constant level during discharge. The time over which the transient phenomena experienced during startup typically occur is short relative to the overall discharge time, which is now long enough for the plasma to assume a relatively steady-state configuration. The ionized gas flows through a stationary current channel in a manner that is sometimes referred to as the deflagration-mode of operation. The plasma experiences electromagnetic acceleration as it flows through the current channel towards the exit of the device. A device that had a short pulse length but appeared to operate in a plasma acceleration regime different from the gas-fed pulsed plasma

Performance of a residential heat pump operating in the cooling mode with single faults imposed

International Nuclear Information System (INIS)

Kim, Minsung; Payne, W. Vance; Domanski, Piotr A.; Yoon, Seok Ho; Hermes, Christian J.L.

2009-01-01

The system behavior of a R410A residential unitary split heat pump operating in the cooling mode was investigated. Seven artificial faults were implemented: compressor/reversing valve leakage, improper outdoor air flow, improper indoor air flow, liquid line restriction, refrigerant undercharge, refrigerant overcharge, and presence of non-condensable gas in the refrigerant. This study monitored eight fault detection features and identified the most sensitive features for each fault. The effect of the various fault levels on energy efficiency ratio (EER) was also estimated. Since the studied system employed a thermostatic expansion valve (TXV) as an expansion device, it could adapt to some faults making the fault less detectable. The distinctiveness of the fault depended on the TXV status (fully open or not)

MIMO Channel Capacity for Handsets in Data Mode Operation

DEFF Research Database (Denmark)

Nielsen, Jesper Ødum; Yanakiev, Boyan; Bonev, Ivan Bonev

2010-01-01

The current paper concerns realistic evaluation of the capacity of the MIMO channel between a BS and handheld device, such as a PDA or smart phone, held in front of the user’s body (data mode). The work is based on measurements of the MIMO channel between two widely separated BSs in a micro...

Theoretical and experimental studies on a magnetorheological brake operating under compression plus shear mode

International Nuclear Information System (INIS)

Sarkar, C; Hirani, H

2013-01-01

The torque characteristics of magnetorheological brakes, consisting of rotating disks immersed in a MR fluid and enclosed in an electromagnetic casing, are controlled by regulating the yield stress of the MR fluid. An increase in yield stress increases the braking torque, which means that the higher the yield strength of the MR fluid, the better the performance of the MR brake will be. In the present research an application of compressive force on MR fluid has been proposed to increase the torque capacity of MR brakes. The mathematical expressions to estimate the torque values for MR brake, operating under compression plus shear mode accounting Herschel–Bulkley shear thinning model, have been detailed. The required compressive force on MR fluid of the proposed brake has been applied using an electromagnetic actuator. The development of a single-plate MR disk brake and an experimental test rig are described. Experiments have been performed to illustrate braking torque under different control currents (0.0–2.0 A). The torque results have been plotted and compared with theoretical study. Experimental results as well as theoretical calculations indicate that the braking torque of the proposed MR brake is higher than that of the MR brake operating only under shear. (paper)

Numerical simulation of hydrodynamics in a pump-turbine at off-design operating conditions in turbine mode

International Nuclear Information System (INIS)

Yan, J P; Seidel, U; Koutnik, J

2012-01-01

The hydrodynamics of a reduced-scaled model of a radial pump-turbine is investigated under off-design operating conditions, involving runaway and 'S-shape' turbine brake curve at low positive discharge. It is a low specific speed pump-turbine machine of Francis type with 9 impeller blades and 20 stay vanes as well as 20 guide vanes. The computational domain includes the entire water passage from the spiral casing inlet to the draft tube outlet. Completely structured hexahedral meshes generated by the commercial software ANSYS-ICEM are employed. The unsteady incompressible simulations are performed using the commercial code ANSYS-CFX13. For turbulence modeling the standard k-ε model is applied. The numerical results at different operating points are compared to the experimental results. The predicted pressure amplitude is in good agreement with the experimental data and the amplitude of normal force on impeller is in reasonable range. The detailed analysis reveals the onset of the flow instabilities when the machine is brought from a regular operating condition to runaway and turbine break mode. Furthermore, the rotating stall phenomena are well captured at runaway condition as well as low discharge operating condition with one stall cell rotating inside and around the impeller with about 70% of its frequency. Moreover, the rotating stall is found to be the effect of rotating flow separations developed in several consecutive impeller channels which lead to their blockage. The reliable simulation of S-curve characteristics in pump-turbines is a basic requirement for design and optimization at off-design operating conditions.

Chapter 7: High-Density H-Mode Operation in ASDEX Upgrade

International Nuclear Information System (INIS)

Stober, Joerg Karl; Lang, Peter Thomas; Mertens, Vitus

2003-01-01

Recent results are reported on the maximum achievable H-mode density and the behavior of pedestal density and central density peaking as this limit is approached. The maximum achievable H-mode density roughly scales as the Greenwald density, though a dependence on B t is clearly observed. In contrast to the stiff temperature profiles, the density profiles seem to allow more shape variation and especially with high-field-side pellet-injection, strongly peaked profiles with good confinement have been achieved. Also, spontaneous density peaking at high densities is observed in ASDEX Upgrade, which is related to the generally observed large time constants for the density profile equilibration. The equilibrated density profile shapes depend strongly on the heat-flux profile in the sense that central heating leads to significantly flatter profiles

Small break LOCA analysis for YGN 5 and 6 RCP trip strategy in power mode operation

International Nuclear Information System (INIS)

Kim, Tech Mo; Choi, Han Rim

2001-01-01

A continued operation of Reactor Coolant Pumps(RCPs) during a Small Break Loss of Coolant Accident(SBLOCA) in all operation mode may increase unnecessary inventory loss from the Reactor Coolant System(RCS) causing a severe core uncovery which might lead to fuel failure. After Three Mile Island Unit 2(TMI-2) accident, the Combustion Engineering Owner Group(CEOG) developed RCP trip strategy called 'Trip-Two/Leave-Two' (T2/L2). The T2/L2 RCP trip strategy consists of tripping the first two RCPs on low RCS pressure and then tripping the remaining two RCPs if a LOCA has occurred. This analysis demonstrates the inherent safety of RCP trip strategy during an SBLOCA for Youggwang Nuclear Power Plant Unit 5 and 6(YGN 5 and 6). The trip setpoint of the first two RCPs for YGN 5 and 6 is calculated to be 1721 psia in pressurizer pressure based on the limiting SBLOCA with 0.15 ft 2 break size in the hot leg. The analysis results show that YGN 5 and 6 can maintain the core coolability even if the operator fails to trip the second two RCPs or trips at the worst time of minimum liquid inventory

RPC operation at high temperature

CERN Document Server

Aielli, G; Cardarelli, R; Di Ciaccio, A; Di Stante, L; Liberti, B; Paoloni, A; Pastori, E; Santonico, R

2003-01-01

The resistive electrodes of RPCs utilised in several current experiments (ATLAS, CMS, ALICE, BABAR and ARGO) are made of phenolic /melaminic polymers, with room temperature resistivities ranging from 10**1**0 Omega cm, for high rate operation in avalanche mode, to 5 multiplied by 10**1**1 Omega cm, for streamer mode operation at low rate. The resistivity has however a strong temperature dependence, decreasing exponentially with increasing temperature. We have tested several RPCs with different electrode resistivities in avalanche as well as in streamer mode operation. The behaviours of the operating current and of the counting rate have been studied at different temperatures. Long-term operation has also been studied at T = 45 degree C and 35 degree C, respectively, for high and low resistivity electrodes RPCs.

Microbial Community Composition of Polyhydroxyalkanoate-Accumulating Organisms in Full-Scale Wastewater Treatment Plants Operated in Fully Aerobic Mode

Science.gov (United States)

Oshiki, Mamoru; Onuki, Motoharu; Satoh, Hiroyasu; Mino, Takashi

2013-01-01

The removal of biodegradable organic matter is one of the most important objectives in biological wastewater treatments. Polyhydroxyalkanoate (PHA)-accumulating organisms (PHAAOs) significantly contribute to the removal of biodegradable organic matter; however, their microbial community composition is mostly unknown. In the present study, the microbial community composition of PHAAOs was investigated at 8 full-scale wastewater treatment plants (WWTPs), operated in fully aerobic mode, by fluorescence in situ hybridization (FISH) analysis and post-FISH Nile blue A (NBA) staining techniques. Our results demonstrated that 1) PHAAOs were in the range of 11–18% in the total number of cells, and 2) the microbial community composition of PHAAOs was similar at the bacterial domain/phylum/class/order level among the 8 full-scale WWTPs, and dominant PHAAOs were members of the class Alphaproteobacteria and Betaproteobacteria. The microbial community composition of α- and β-proteobacterial PHAAOs was examined by 16S rRNA gene clone library analysis and further by applying a set of newly designed oligonucleotide probes targeting 16S rRNA gene sequences of α- or β-proteobacterial PHAAOs. The results demonstrated that the microbial community composition of PHAAOs differed in the class Alphaproteobacteria and Betaproteobacteria, which possibly resulted in a different PHA accumulation capacity among the WWTPs (8.5–38.2 mg-C g-VSS−1 h−1). The present study extended the knowledge of the microbial diversity of PHAAOs in full-scale WWTPs operated in fully aerobic mode. PMID:23257912

Development of MCP transient operation strategy for the SMART-P

International Nuclear Information System (INIS)

Yoo, S. E.; Choi, B. S.; Kang, H. O.; Yoon, J. H.; Ji, S. K.

2003-01-01

SMART-P MCP(Main Coolant Pump) transient operation strategies are developed. A Modular Modeling System (MMS) computer code is used for the evaluation of the developed operation strategies. In the SMART-P, normal operating modes are classified into MCP high speed(3600 rpm) mode and MCP low speed mode. Also, natural circulation mode is defined as a performance test case. MCP operation transients occur when changing modes from one to another, and system parameters(core power, system pressure, temperature) are having transients. These transients affect on system performance and, in some cases, limit system operation. In this study, MCP operation strategies are developed and obtained acceptable results

Control of spool position of on/off solenoid operated hydraulic valve by sliding-mode controller

Energy Technology Data Exchange (ETDEWEB)

Lee, Jae Hak; Hong, Hyun Wook; Park, Myeong Kwan [Pusan National University, Busan (Korea, Republic of); Yun, Young Won [KHPS, Busan (Korea, Republic of)

2015-11-15

The use of on/off solenoid operated hydraulic valves instead of proportional valves has been attracting the interest of many researchers and engineers. However, there exist difficulties in controlling the on/off valve because of highly nonlinear characteristics including hysteresis and saturation. This paper considers the application of on/off solenoid operated hydraulic valves to control position of a hydraulic cylinder with the aim of evaluating, feasibility and practicability of their implementation and understanding the potential benefits when they are used in existing hydraulic systems. Assuming that only the current is measured, a sliding mode observer is designed to estimate the spool position and velocity. To alleviate the aforementioned difficulties in controlling the spool position, a nonlinear observer-based controller of an on/off solenoid valve is designed, taking into account the estimated values, based on a nonlinear model including hysteresis and saturation. The control objective is to track a desired spool trajectory. Simulation and experimental results illustrate the efficiency of the designed controller. The proposed controller is validated again in a single-rod hydraulic actuator. Experimental results show that the fluid flow through the valve orifice by controlling the spool position was successfully controlled.

A History of Emerging Modes?

Directory of Open Access Journals (Sweden)

Schmitz Michael

2016-03-01

Full Text Available In this paper I first introduce Tomasello’s notion of thought and his account of its emergence and development through differentiation, arguing that it calls into question the theory bias of the philosophical tradition on thought as well as its frequent atomism. I then raise some worries that he may be overextending the concept of thought, arguing that we should recognize an area of intentionality intermediate between action and perception on the one hand and thought on the other. After that I argue that the co-operative nature of humans is reflected in the very structure of their intentionality and thought: in co-operative modes such as the mode of joint attention and action and the we-mode, they experience and represent others as co-subjects of joint relations to situations in the world rather than as mere objects. In conclusion, I briefly comment on what Tomasello refers to as one of two big open questions in the theory of collective intentionality, namely that of the irreducibility of jointness.

Mode competition and hopping in optomechanical nano-oscillators

Science.gov (United States)

Zhang, Xingwang; Lin, Tong; Tian, Feng; Du, Han; Zou, Yongchao; Chau, Fook Siong; Zhou, Guangya

2018-04-01

We investigate the inter-mode nonlinear interaction in the multi-mode optomechanical nano-oscillator which consists of coupled silicon nanocantilevers, where the integrated photonic crystal nanocavities provide the coupling between the optical and mechanical modes. Due to the self-saturation and cross-saturation of the mechanical gain, the inter-mode competition is observed, which leads to the bistable operation of the optomechanical nano-oscillator: only one of the mechanical modes can oscillate at any one time, and the oscillation of one mode extremely suppresses that of the other with a side mode suppression ratio (SMSR) up to 40 dB. In the meantime, mode hopping, i.e., the optomechanical oscillation switches from one mode to the other, is also observed and found to be able to be provoked by excitation laser fluctuations.

Experimental study of pistachio drying behavior in a mixed-mode PV operated forced convection solar dryer

Energy Technology Data Exchange (ETDEWEB)

Zangiabadi, B [Univ. of Stavanger, Stavanger (Norway); Ameri, M; Mahmoudabadi, M M [Shahid Bahonar Univ., Kerman (Iran, Islamic Republic of)

2008-07-01

According to FAO statistics, Iran is the largest exporter of pistachios. Kerman province -south east of Iran- has approximately 200000 hectares of pistachio orchards, which provides practically 80% of whole country production of pistachios. After harvesting the pistachio, nuts must be washed to prevent staining. Therefore the nuts have almost 40% moisture content and it must be decreased to storage moisture of 6% or below. Simply decreasing in the moisture content of the products is called drying. In some areas where the environment conditions meet the minimum standard, solar drying can be an alternative approach for drying agricultural products. This work deals with the design, construction and testing a mixed-mode forced convection PV operated solar dryer. (orig.)

Deformations and Displacements of the LHC Superconducting Dipoles Induced by Standard and Non-Standard Operational Modes

CERN Document Server

La China, M; Gubello, G; Scandale, Walter

2004-01-01

A full-scale and fully-instrumented working model of the LHC lattice cell has been tested at CERN between March and December 2002. Aside of the current, pressure and temperature sensors, controlled by an industrial supervision system, a novel device has been set to monitor magnet positions with respect to the surrounding cryostat. The series of operating modes to test cryogenics, current leads and quench recovery electronics offered the chance to investigate potentially harmful deformations of the superconducting structure. In this paper we present a survey of displacements and deformations experienced by the LHC cell magnets during thermal cycles, current ramps and resistive transitions. Although the system complexity prevented from complete modeling, a preliminary phenomena explanation is given.

Physics of the H-mode

International Nuclear Information System (INIS)

Hinton, F.L.; Chu, M.S.; Dominguez, R.R.

1985-01-01

A theoretical picture of the H-mode is proposed which explains some of the most important features of this good confinement mode in neutral beam heated plasmas with divertors. From consideration of the transport through the separatrix and along the open field lines outside the separatrix, as well as the stability of the plasma inside the separatrix, we show that a bifurcation in the operating parameters is possible. At high edge temperatures, very large particle confinement times are possible because of the Ware pinch. The transport of particles and heat along the open field lines to the divertor region depends on temperature in a non-monotonic way, and the bifurcation of the thermal equilibrium which is implied may correspond to the L- to H-mode transition. The improvement of the interior confinement in the H-mode, when the edge temperature is higher, is shown to follow from the tearing mode stability properties of current profiles with pedestals. (author)

High energy, single frequency, tunable laser source operating in burst mode for space based lidar applications

Science.gov (United States)

Cosentino, Alberto; Mondello, Alessia; Sapia, Adalberto; D'Ottavi, Alessandro; Brotini, Mauro; Nava, Enzo; Stucchi, Emanuele; Trespidi, Franco; Mariottini, Cristina; Wazen, Paul; Falletto, Nicolas; Fruit, Michel

2017-11-01

This paper describes the laser transmitter assembly used in the ALADIN instrument currently in C/D development phase for the ESA ADM-AEOLUS mission (EADS Astrium as prime contractor for the satellite and the instrument). The Laser Transmitter Assembly (TXA), based on a diode pumped tripled Nd:YAG laser, is used to generate tunable laser pulses of 150 mJ at a nominal wavelength of 355 nm. This laser is operated in burst mode, with a pulse repetition cycle of 100 Hz. The TXA is composed of the following units: a diodepumped CW Nd:YAG Laser named Reference Laser Head (RLH), used to inject a diode-pumped, Q-switched, amplified and frequency tripled Nd:YAG Laser working in the third harmonic referred as Power Laser Head (PLH) and a Transmitter Laser Electronics (TLE) containing all the control and power electronics needed for PLH and RLH operation. The TXA is made by an European consortium under the leadership of Galileo Avionica (It), and including CESI (It), Quantel (Fr), TESAT (Ge) and Thales (Fr).

Soft modes and structural phase transitions

Energy Technology Data Exchange (ETDEWEB)

Venkataraman, G [Reactor Research Centre, Kalpakkam (India)

1979-12-01

A survey of soft modes and their relationship to structural phase transitions is presented. After introducing the concept of a soft mode, the origin of softening is considered from a lattice-dynamical point. The Landau theory approach to structural transitions is then discussed, followed by a generalisation of the soft-mode concept through the use of the dynamic order-parameter susceptibility. The relationship of soft modes to broken symmetry is also examined. Experimental results for several classes of crystals are next presented, bringing out various features such as the co-operative Jahn-Teller effect. The survey concludes with a discussion of the central peak, touching upon both the experimental results and the theoretical speculations.

Normalized modes at selected points without normalization

Science.gov (United States)

Kausel, Eduardo

2018-04-01

As every textbook on linear algebra demonstrates, the eigenvectors for the general eigenvalue problem | K - λM | = 0 involving two real, symmetric, positive definite matrices K , M satisfy some well-defined orthogonality conditions. Equally well-known is the fact that those eigenvectors can be normalized so that their modal mass μ =ϕT Mϕ is unity: it suffices to divide each unscaled mode by the square root of the modal mass. Thus, the normalization is the result of an explicit calculation applied to the modes after they were obtained by some means. However, we show herein that the normalized modes are not merely convenient forms of scaling, but that they are actually intrinsic properties of the pair of matrices K , M, that is, the matrices already "know" about normalization even before the modes have been obtained. This means that we can obtain individual components of the normalized modes directly from the eigenvalue problem, and without needing to obtain either all of the modes or for that matter, any one complete mode. These results are achieved by means of the residue theorem of operational calculus, a finding that is rather remarkable inasmuch as the residues themselves do not make use of any orthogonality conditions or normalization in the first place. It appears that this obscure property connecting the general eigenvalue problem of modal analysis with the residue theorem of operational calculus may have been overlooked up until now, but which has in turn interesting theoretical implications.Á

Correlations between locked modes and impurity influxes

Energy Technology Data Exchange (ETDEWEB)

Fishpool, G M [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Lawson, K D [UKAEA Culham Lab., Abingdon (United Kingdom)

1994-07-01

An analysis of pulses that were disturbed by medium Z impurity influxes (Cl, Cr, Fe and Ni) recorded during the 91/92 JET operations, has demonstrated that such influxes can result in MHD modes which subsequently ``lock``. A correlation is found between the power radiated by the influx and the time difference between the start of the influx and the beginning of the locked mode. The growth in the amplitude of the locked mode itself can lead to further impurity influxes. A correlation is noted between intense influxes (superior to 10 MW) and the mode ``unlocking``. (authors). 4 refs., 4 figs.

From dressed particle to dressed mode in plasmas

Energy Technology Data Exchange (ETDEWEB)

Itoh, Sanae-I. [Kyushu Univ., Research Inst. for Applied Mechanics, Kasuga, Fukuoka (Japan); Itoh, Kimitaka [National Inst. for Fusion Science, Toki, Gifu (Japan)

2002-05-01

A theoretical method to analyze the strong turbulence in far-nonequilibrium plasma is discussed. In this approach, a test mode is treated being dressed with interactions with other modes. Nonlinear dispersion relation of the dressed mode and statistical treatment of turbulence is briefly explained. Analogue to the method of dressed particle, which has given Balescu-Lenard collision operator for inter-particle collisions, is mentioned. (author)

Threshold condition for nonlinear tearing modes in tokamaks

Energy Technology Data Exchange (ETDEWEB)

Zabiego, M.F. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Callen, J.D. [Wisconsin Univ., Madison, WI (United States). Dept. of Nuclear Engineering and Engineering Physics

1996-04-01

Low-mode-number tearing mode nonlinear evolution is analyzed emphasizing the need for a threshold condition, to account for observations in tokamaks. The discussion is illustrated by two models recently introduced in the literature. Introducing a threshold condition in the tearing mode stability analysis is found to reveal some bifurcation points and thus domains of intrinsic stability in the island dynamics operational space. (author). 19 refs.

Threshold condition for nonlinear tearing modes in tokamaks

International Nuclear Information System (INIS)

Zabiego, M.F.; Callen, J.D.

1996-04-01

Low-mode-number tearing mode nonlinear evolution is analyzed emphasizing the need for a threshold condition, to account for observations in tokamaks. The discussion is illustrated by two models recently introduced in the literature. Introducing a threshold condition in the tearing mode stability analysis is found to reveal some bifurcation points and thus domains of intrinsic stability in the island dynamics operational space. (author)

Design of Dual-Mode Local Oscillators Using CMOS Technology for Motion Detection Sensors.

Science.gov (United States)

Ha, Keum-Won; Lee, Jeong-Yun; Kim, Jeong-Geun; Baek, Donghyun

2018-04-01

Recently, studies have been actively carried out to implement motion detecting sensors by applying radar techniques. Doppler radar or frequency-modulated continuous wave (FMCW) radar are mainly used, but each type has drawbacks. In Doppler radar, no signal is detected when the movement is stopped. Also, FMCW radar cannot function when the detection object is near the sensor. Therefore, by implementing a single continuous wave (CW) radar for operating in dual-mode, the disadvantages in each mode can be compensated for. In this paper, a dual mode local oscillator (LO) is proposed that makes a CW radar operate as a Doppler or FMCW radar. To make the dual-mode LO, a method that controls the division ratio of the phase locked loop (PLL) is used. To support both radar mode easily, the proposed LO is implemented by adding a frequency sweep generator (FSG) block to a fractional-N PLL. The operation mode of the LO is determined by according to whether this block is operating or not. Since most radar sensors are used in conjunction with microcontroller units (MCUs), the proposed architecture is capable of dual-mode operation by changing only the input control code. In addition, all components such as VCO, LDO, and loop filter are integrated into the chip, so complexity and interface issues can be solved when implementing radar sensors. Thus, the proposed dual-mode LO is suitable as a radar sensor.

Design of Dual-Mode Local Oscillators Using CMOS Technology for Motion Detection Sensors

Directory of Open Access Journals (Sweden)

Keum-Won Ha

2018-04-01

Full Text Available Recently, studies have been actively carried out to implement motion detecting sensors by applying radar techniques. Doppler radar or frequency-modulated continuous wave (FMCW radar are mainly used, but each type has drawbacks. In Doppler radar, no signal is detected when the movement is stopped. Also, FMCW radar cannot function when the detection object is near the sensor. Therefore, by implementing a single continuous wave (CW radar for operating in dual-mode, the disadvantages in each mode can be compensated for. In this paper, a dual mode local oscillator (LO is proposed that makes a CW radar operate as a Doppler or FMCW radar. To make the dual-mode LO, a method that controls the division ratio of the phase locked loop (PLL is used. To support both radar mode easily, the proposed LO is implemented by adding a frequency sweep generator (FSG block to a fractional-N PLL. The operation mode of the LO is determined by according to whether this block is operating or not. Since most radar sensors are used in conjunction with microcontroller units (MCUs, the proposed architecture is capable of dual-mode operation by changing only the input control code. In addition, all components such as VCO, LDO, and loop filter are integrated into the chip, so complexity and interface issues can be solved when implementing radar sensors. Thus, the proposed dual-mode LO is suitable as a radar sensor.

Mode of operation of a nuclear reactor

International Nuclear Information System (INIS)

Morita, T.

1976-01-01

A method is proposed for the operation of a nuclear reactor guaranteeing an essentially symmetrical axial power distribution during normal operation by controlling the changes occuring in the reactor power partly by variation of the concentration of the neutron-absorbing element and partly by variation of the control rod positions. The representative parameters are recorded for the upper and lower half and adjusted to a predetermined reference value. In using this method, the axial power peals are reduced and power losses avoided. (RW) [de

Active mode locking of quantum cascade lasers in an external ring cavity.

Science.gov (United States)

Revin, D G; Hemingway, M; Wang, Y; Cockburn, J W; Belyanin, A

2016-05-05

Stable ultrashort light pulses and frequency combs generated by mode-locked lasers have many important applications including high-resolution spectroscopy, fast chemical detection and identification, studies of ultrafast processes, and laser metrology. While compact mode-locked lasers emitting in the visible and near infrared range have revolutionized photonic technologies, the systems operating in the mid-infrared range where most gases have their strong absorption lines, are bulky and expensive and rely on nonlinear frequency down-conversion. Quantum cascade lasers are the most powerful and versatile compact light sources in the mid-infrared range, yet achieving their mode-locked operation remains a challenge, despite dedicated effort. Here we report the demonstration of active mode locking of an external-cavity quantum cascade laser. The laser operates in the mode-locked regime at room temperature and over the full dynamic range of injection currents.

Optimal hysteretic control for a B M A P / S M / 1 / N queue with two operation modes

Directory of Open Access Journals (Sweden)

Dudin Alexander N.

1999-01-01

Full Text Available We consider B M A P / S M / 1 type queueing system with finite buffer of size N . The system has two operation modes, which are characterized by the matrix generating function of B M A P -input, the kernel of the semi-Markovian service process, and utilization cost. An algorithm for determining the optimal hysteresis strategy is presented.

Observations on resistive wall modes

International Nuclear Information System (INIS)

Gerwin, R.A.; Finn, J.M.

1996-01-01

Several results on resistive wall modes and their application to tokamaks are presented. First, it is observed that in the presence of collisional parallel dynamics there is an exact cancellation to lowest order of the dissipative and sound wave effects for an ideal Ohm's law. This is easily traced to the fact that the parallel dynamics occurs along the perturbed magnetic field lines for such electromagnetic modes. Such a cancellation does not occur in the resistive layer of a tearing-like mode. The relevance to models for resistive wall modes using an electrostatic Hammett-Perkins type operator to model Landau damping will be discussed. Second, we observe that with an ideal Ohm's law, resistive wall modes can be destabilized by rotation in that part of parameter space in which the ideal MHD modes are stable with the wall at infinity. This effect can easily be explained by interpreting the resistive wall instability in terms of mode coupling between the backward stable MHD mode and a stable mode locked into the wall. Such an effect can occur for very small rotation for tearing-resistive wall modes in which inertia dominates viscosity in the layer, but the mode is stabilized by further rotation. For modes for which viscosity dominates in the layer, rotation is purely stabilizing. For both tearing models, a somewhat higher rotation frequency gives stability essentially whenever the tearing mode is stable with a perfectly conducting wall. These tearing/resistive wall results axe also simply explained in terms of mode coupling. It has been shown that resonant external ideal modes can be stabilized in the presence of resistive wall and resistive plasma with rotation of order the nominal tearing mode growth rate. We show that these modes behave as resistive wall tearing modes in the sense above. This strengthens the suggestion that rotational stabilization of the external kink with a resistive wall is due to the presence of resistive layers, even for ideal modes

Quark-interaction in the 1-mode QCD

International Nuclear Information System (INIS)

Wendel, M.H.

1989-01-01

We explain first the field operators in the N-mode representation. We choose the Hamiltonian formulation in temporal gauge. We come then across an intrinsic instability of the canonical formulation of the N-mode idea. The following chapter deals with the overvoming of the instability. It is shown that the generator of the instability carries simultaneously already the dynamical element of its cancelling. This transformation, which performs this, is of the BCS type and contains as quasi particles just the mesonic hybrid states already mentioned for instance by Pottinger and Warner. We come thereby across a second instability, which occurs in the limit of vanishing chromomagnetic contribution B 2 . The chapter concludes with a variational analysis of the transformed Hamiltonian operator. The following chapter deals first with the phenomenological results on the existence of hybride mesons and other oxotic quark-gluon states, as they occur in canonical way in the N-mode model with BCS transformations. We show for this reason, how the transformation can be extended to the spin degrees of freedom and calculate the resulting pairing interaction energies of quarks and antiquarks. In the last chapter we finally enter possible many-mode formulations and sketch thereby methods, which allow in a relatively simple way to conclude from the hitherto 1-mode results to certain N-mode analoga. (orig./HSI) [de

The evolution of investments decision mode in China's telecommunication

Institute of Scientific and Technical Information of China (English)

ZHANG Ai-hua; ZHAO Lian-qiang; SHU Hua-ying

2007-01-01

This essay analyzes the data of Chinese telecommunication market, telecommunication investments and investment benefits over the past 20 years. On the basis of these data, the essay reviews Chinese changing telecommunication policies and discusses the major events in the course of China's telecommunication development. It is argued that telecommunication policies, regime backgrounds and market demand characteristics have a significant impact on investment decision mode in telecommunication industry. The evolution of network investments decision mode in China's telecommunication has corresponded to the transformation of these key factors. Considering the special events in the development of Chinese telecommunication as divisions, the essay discusses three stages of the evolution of investments decision mode in China's telecommunication. With the firm environment and problems that Chinese telecommunication operators have been facing since 2000 analyzed. it is demonstrated that Chinese telecommunication operators should change their mode of investment decision into the "profit-oriented investment decision mode" in order to achieve a high growth performance in the capital market,. This investment decision mode will result in increase of the investment profit with limited investment capital. The main procedure of profit-oriented investment decision mode is set out, which is abstracted to a mathematical model eventually.

A novel L-shaped linear ultrasonic motor operating in a single resonance mode

Science.gov (United States)

Zhang, Bailiang; Yao, Zhiyuan; Liu, Zhen; Li, Xiaoniu

2018-01-01

In this study, a large thrust linear ultrasonic motor using an L-shaped stator is described. The stator is constructed by two mutually perpendicular rectangular plate vibrators, one of which is mounted in parallel with the slider to make the motor structure to be more compact. The symmetric and antisymmetric modes of the stator based on the first order bending vibration of two vibrators are adopted, in which each resonance mode is assigned to drive the slider in one direction. The placement of piezoelectric ceramics in a stator could be determined by finite element analysis, and the influence of slots in the head block on the vibration amplitudes of driving foot was studied as well. Three types of prototypes (non-slotted, dual-slot, and single-slot) were fabricated and experimentally investigated. Experimental results demonstrated that the prototype with one slot exhibited the best mechanical output performance. The maximum loads under the excitation of symmetric mode and antisymmetric mode were 65 and 90 N, respectively.

Physics of resistive wall modes

International Nuclear Information System (INIS)

Igochine, V.

2012-01-01

The advanced tokamak regime is a promising candidate for steady-state tokamak operation which is desirable for a fusion reactor. This regime is characterized by a high bootstrap current fraction and a flat or reversed safety factor profile, which leads to operation close to the pressure limit. At this limit, an external kink mode becomes unstable. This external kink is converted into the slowly growing resistive wall mode (RWM) by the presence of a conducting wall. Reduction of the growth rate allows one to act on the mode and to stabilize it. There are two main factors which determine the stability of the RWM. The first factor comes from external magnetic perturbations (error fields, resistive wall, feedback coils, etc). This part of RWM physics is the same for tokamaks and reversed field pinch configurations. The physics of this interaction is relatively well understood and based on classical electrodynamics. The second ingredient of RWM physics is the interaction of the mode with plasma flow and fast particles. These interactions are particularly important for tokamaks, which have higher plasma flow and stronger trapped particle effects. The influence of the fast particles will also be increasingly more important in ITER and DEMO which will have a large fraction of fusion born alpha particles. These interactions have kinetic origins which make the computations challenging since not only particles influence the mode, but also the mode acts on the particles. Correct prediction of the ‘plasma–RWM’ interaction is an important ingredient which has to be combined with external field's influence (resistive wall, error fields and feedback) to make reliable predictions for RWM behaviour in tokamaks. All these issues are reviewed in this paper. (special topic)

MANGO – Modal Analysis for Grid Operation: A Method for Damping Improvement through Operating Point Adjustment

Energy Technology Data Exchange (ETDEWEB)

Huang, Zhenyu; Zhou, Ning; Tuffner, Francis K.; Chen, Yousu; Trudnowski, Daniel J.; Diao, Ruisheng; Fuller, Jason C.; Mittelstadt, William A.; Hauer, John F.; Dagle, Jeffery E.

2010-10-18

Small signal stability problems are one of the major threats to grid stability and reliability in the U.S. power grid. An undamped mode can cause large-amplitude oscillations and may result in system breakups and large-scale blackouts. There have been several incidents of system-wide oscillations. Of those incidents, the most notable is the August 10, 1996 western system breakup, a result of undamped system-wide oscillations. Significant efforts have been devoted to monitoring system oscillatory behaviors from measurements in the past 20 years. The deployment of phasor measurement units (PMU) provides high-precision, time-synchronized data needed for detecting oscillation modes. Measurement-based modal analysis, also known as ModeMeter, uses real-time phasor measurements to identify system oscillation modes and their damping. Low damping indicates potential system stability issues. Modal analysis has been demonstrated with phasor measurements to have the capability of estimating system modes from both oscillation signals and ambient data. With more and more phasor measurements available and ModeMeter techniques maturing, there is yet a need for methods to bring modal analysis from monitoring to actions. The methods should be able to associate low damping with grid operating conditions, so operators or automated operation schemes can respond when low damping is observed. The work presented in this report aims to develop such a method and establish a Modal Analysis for Grid Operation (MANGO) procedure to aid grid operation decision making to increase inter-area modal damping. The procedure can provide operation suggestions (such as increasing generation or decreasing load) for mitigating inter-area oscillations.

A comparison of process performance during the anaerobic mono- and co-digestion of slaughterhouse waste through different operational modes.

Science.gov (United States)

Pagés-Díaz, Jhosané; Pereda-Reyes, Ileana; Sanz, Jose Luis; Lundin, Magnus; Taherzadeh, Mohammad J; Horváth, Ilona Sárvári

2018-02-01

The use of consecutive feeding was applied to investigate the response of the microbial biomass to a second addition of substrates in terms of biodegradation using batch tests as a promising alternative to predict the behavior of the process. Anaerobic digestion (AD) of the slaughterhouse waste (SB) and its co-digestion with manure (M), various crops (VC), and municipal solid waste were evaluated. The results were then correlated to previous findings obtained by the authors for similar mixtures in batch and semi-continuous operation modes. AD of the SB failed showing total inhibition after a second feeding. Co-digestion of the SB+M showed a significant improvement for all of the response variables investigated after the second feeding, while co-digestion of the SB+VC resulted in a decline in all of these response variables. Similar patterns were previously detected, during both the batch and the semi-continuous modes. Copyright © 2017. Published by Elsevier B.V.

Real-Time Assessment and Diagnosis of Process Operating Performance

Directory of Open Access Journals (Sweden)

Shabnam Sedghi

2017-04-01

Full Text Available Over time, the performance of processes may deviate from the initial design due to process variations and uncertainties, making it necessary to develop systematic methods for online optimality assessment based on routine operating process data. Some processes have multiple operating modes caused by the set point change of the critical process variables to achieve different product specifications. On the other hand, the operating region in each operating mode can alter, due to uncertainties. In this paper, we will establish an optimality assessment framework for processes that typically have multi-mode, multi-region operations, as well as transitions between different modes. The kernel density approach for mode detection is adopted and improved for operating mode detection. For online mode detection, the model-based clustering discriminant analysis (MclustDA approach is incorporated with some a priori knowledge of the system. In addition, multi-modal behavior of steady-state modes is tackled utilizing the mixture probabilistic principal component regression (MPPCR method, and dynamic principal component regression (DPCR is used to investigate transitions between different modes. Moreover, a probabilistic causality detection method based on the sequential forward floating search (SFFS method is introduced for diagnosing poor or non-optimum behavior. Finally, the proposed method is tested on the Tennessee Eastman (TE benchmark simulation process in order to evaluate its performance.

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

OpenAIRE

Jinhaeng Jang; Syam Kumar Pidaparthy; Byungcho Choi

2015-01-01

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

Defense against common-mode failures in protection system design

International Nuclear Information System (INIS)

Wyman, R.H.; Johnson, G.L.

1998-01-01

The introduction of digital instrumentation and control into reactor safety systems creates a heightened concern about common-mode failure. This paper discusses the concern and methods of cope with the concern. Common-mode failures have been a 'fact-of-life' in existing systems. The informal introduction of defense-in-depth and diversity (D-in-D and D) - coupled with the fact that hardware common-mode failures are often distributed in time - has allowed systems to deal with past common-mode failures. However, identical software operating in identical redundant systems presents the potential for simultaneous failure. Consequently, the use of digital systems raises the concern about common-mode failure to a new level. A more methodical approach to mitigating common-mode failure is needed to address these concerns. Purposeful introduction of D-in-D and D has been used as a defense against common-mode failure in reactor protection systems. At least two diverse systems are provided to mitigate any potential initiating event. Additionally, diverse displays and controls are provided to allow the operator to monitor plant status and manually initiate engineered safety features. A special form of common-mode failure analysis called 'defense-in-depth and diversity analysis' has been developed to identify possible common-mode failure vulnerabilities in digital systems. An overview of this analysis technique is provided. (author)

Defense against common-mode failures in protection system design

International Nuclear Information System (INIS)

Wyman, R.H.; Johnson, G.L.

1997-01-01

The introduction of digital instrumentation and control into reactor safety systems creates a heightened concern about common-mode failure. This paper discusses the concern and methods to cope with the concern. Common-mode failures have been a ''fact-of-life'' in existing systems. The informal introduction of defense-in-depth and diversity (D-in-D ampersand D)-coupled with the fact that hardware common-mode failures are often distributed in time-has allowed systems to deal with past common-mode failures. However, identical software operating in identical redundant systems presents the potential for simultaneous failure. Consequently, the use of digital systems raises the concern about common-mode failure to a new level. A more methodical approach to mitigating common-mode failure is needed to address these concerns. Purposeful introduction of D-in-D ampersand D has been used as a defense against common-mode failure in reactor protection systems. At least two diverse systems are provided to mitigate any potential initiating event. Additionally, diverse displays and controls are provided to allow the operator to monitor plant status and manually initiate engineered safety features. A special form of conimon-mode failure analysis called ''defense-in-depth and diversity analysis'' has been developed to identify possible conimon-mode failure vulnerabilities in digital systems. An overview of this analysis technique is provided

Description and characterization of the ACRR's programmable transient rod withdrawal mode

International Nuclear Information System (INIS)

Boldt, K.R.; Sullivan, W.H.; Kefauver, H.L.

1980-01-01

To satisfy experiment needs for Sandia's Advanced Reactor Safety Program, a programmable Transient Rod Withdrawal (TRW) mode has been developed for the Annular Core Research Reactor (ACRR). The programmable mode is a modification of the existing continuous-withdrawal TRW mode and permits speed and direction changes during the pulse sequence. Basically, a TRW operation is similar to a routine pulse operation except that transient rods are mechanically withdrawn rather than pneumatically fired. Being a pulse-type operation, the TRW mode complies with pulse-mode safety system settings. Control system interlocks prevent the pneumatic firing of rods in the TRW mode. The hardware for the programmable TRW mode includes three ACRR transient rods, the ACRR timer, two rod programmers, a minicomputer and a summing circuit for position indication. Each ACRR transient rod is mechanically driven by a stepping motor (rated torque at 4.24 joules) and is capable of a maximum TRW speed of 26.7 centimeters/ second. The maximum reactivity insertion rate is $2.45/second with a transient rod bank worth of $3.00 and $3.47/second with a bank worth of $4.25, which is expected to be installed soon. The ACRR timer is a multifunctional timer used in all operating modes of the reactor. In the programmable TRW mode, the timer starts the rod programmers and drops regulating rods to terminate the operation. Programmed withdrawal capability is provided by one of two rod programmers (a hardwire-based unit and a microprocessor-based unit). The hardwire unit has eight intervals in which speed, direction and distance are selected by switches on the front panel. The microprocessor-based unit has the capability of 64 intervals in which speed, direction, and distance or time can be specified. Programming this unit is accomplished from the front panel or by inputting data from an HP-9845. minicomputer via a digital I/O interface. Self-test programs in the software provide a continual check of an operating

Experimental study on combustion modes and thrust performance of a staged-combustor of the scramjet with dual-strut

Science.gov (United States)

Yang, Qingchun; Chetehouna, Khaled; Gascoin, Nicolas; Bao, Wen

2016-05-01

To enable the scramjet operate in a wider flight Mach number, a staged-combustor with dual-strut is introduced to hold more heat release at low flight Mach conditions. The behavior of mode transition was examined using a direct-connect model scramjet experiment along with pressure measurements. The typical operating modes of the staged-combustor are analyzed. Fuel injection scheme has a significant effect on the combustor operating modes, particularly for the supersonic combustion mode. Thrust performances of the combustor with different combustion modes and fuel distributions are reported in this paper. The first-staged strut injection has a better engine performance in the operation of subsonic combustion mode. On the contrast, the second-staged strut injection has a better engine performance in the operation of supersonic combustion mode.

High-power, cladding-pumped all-fiber laser with selective transverse mode generation property.

Science.gov (United States)

Li, Lei; Wang, Meng; Liu, Tong; Leng, Jinyong; Zhou, Pu; Chen, Jinbao

2017-06-10

We demonstrate, to the best of our knowledge, the first cladding-pumped all-fiber oscillator configuration with selective transverse mode generation based on a mode-selective fiber Bragg grating pair. Operating in the second-order (LP 11 ) mode, maximum output power of 4.2 W is obtained with slope efficiency of about 38%. This is the highest reported output power of single higher-order transverse mode generation in an all-fiber configuration. The intensity distribution profile and spectral evolution have also been investigated in this paper. Our work suggests the potential of realizing higher power with selective transverse mode operation based on a mode-selective fiber Bragg grating pair.

Startup and mode competition in a 420 GHz gyrotron

Science.gov (United States)

Qixiang Zhao, A.; Sheng Yu, B.; Tianzhong Zhang, C.

2017-09-01

In the experiments of a 420 GHz second-harmonic gyrotron, it is found that the electron beam voltage and current ranges for single mode operation of TE17.4 are slightly narrower than those in the simulation. To explain this phenomenon, the startup scenario has been investigated with special emphasis on mode competition. The calculations indicate that the decreases of the operating ranges are caused by the voltage overshoot in the startup scenario.

Intra-cavity generation of high order LGpl modes

CSIR Research Space (South Africa)

Ngcobo, S

2012-08-01

Full Text Available with the location of the Laguerre polynomial zeros. The Diffractive optical element is used to shape the TEM00 Gaussian beam and force the laser to operate on a higher order LGpl Laguerre-Gaussian modes or high order superposition of Laguerre-Gaussian modes...

ITER operational space for full plasma current H-mode operation

Energy Technology Data Exchange (ETDEWEB)

Mattei, M. [Assoc. Euratom-ENEA-CREATE, Seconda University di Napoli, Aversa (Italy)], E-mail: massimiliano.mattei@unirc.it; Cavinato, M.; Saibene, G.; Portone, A. [Fusion for Energy Joint Undertaking, 08019 Barcelona (Spain); Albanese, R.; Ambrosino, G. [Assoc. Euratom-ENEA-CREATE, University Napoli Federico II, Napoli (Italy); Horton, L.D. [Max Planck-Institut fur Plasmaphysik, EURATOM-Association, Garching (Germany); Kessel, C. [Princeton Plasma Physics Laboratory, Princeton University (United States); Koechl, F. [Assoc. EURATOM-OAW/ATI, Vienna (Austria); Lomas, P.J. [Euratom/UKAEA Fusion Assoc., Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Nunes, I. [Assoc. EURATOM/IST, Centro de Fusao Nuclear, Lisbon (Portugal); Parail, V. [Max Planck-Institut fur Plasmaphysik, EURATOM-Association, Garching (Germany); Sartori, R. [Fusion for Energy Joint Undertaking, 08019 Barcelona (Spain); Sips, A.C.C. [Max Planck-Institut fur Plasmaphysik, EURATOM-Association, Garching (Germany); Thomas, P.R. [Fusion for Energy Joint Undertaking, 08019 Barcelona (Spain)

2009-06-15

Sensitivity studies performed as part of the ITER IO design review highlighted a very stiff dependence of the maximum Q attainable on the machine parameters. In particular, in the considered range, the achievable Q scales with I{sub p}{sup 4}. As a consequence, the achievement of the ITER objective of Q = 10 requires the machine to be routinely operated at a nominal current I{sub p} of 15 MA, and at full toroidal field BT of 5.3 T. This paper analyses the capabilities of the poloidal field (PF) system (including the central solenoid) of ITER against realistic full current plasma scenarios. An exploration of the ITER operational space for the 15 and 17 MA inductive scenario is carried out. An extensive analysis includes the evaluation of margins for the closed loop shape control action. The overall results of this analysis indicate that the control of a 15 MA plasma in ITER is likely to be adequate in the range of li 0.7-0.9 whereas, for a 17 MA plasma, control capabilities are strongly reduced. The ITER operational space, provided by the reference pre-2008 PF system, was rather limited if compared to the range of parameters normally observed in present experiment. Proposals for increasing the current and field limits on PF2, PF5 and PF6, adjustment on the number of turns in some of the PF coils, changes to the divertor dome geometry, to the conductor of PF6 to Nb3Sn, moving PF6 radially and/or vertically are described and evaluated in the paper. Some of them have been included in 2008 ITER revised configuration.

Chemical mode control in nuclear power plant decommissioning during operation of technologies in individual radioactive waste processing plants

International Nuclear Information System (INIS)

Horvath, J.; Dugovic, L.

1999-01-01

Sewage treatment of nuclear power plant decommissioning is performed by system of sewage concentration in evaporator with formation of condensed rest, it means radioactive waste concentrate and breeding steam. During sewage treatment plant operation department of chemical mode performs chemical and radiochemical analysis of sewage set for treatment, chemical and radiochemical analysis of breeding steam condensate which is after final cleaning on ionization filter and fulfilling the limiting conditions released to environment; chemical and radiochemical analysis of heating steam condensate which is also after fulfilling the limiting conditions released to environment. Condensed radioactive concentrate is stored in stainless tanks and later converted into easy transportable and chemically stable matrix from the long term storage point of view in republic storage Mochovce. The article also refer to bituminous plant, vitrification plant, swimming pool decontamination plant of long term storage and operation of waste processing plant Bohunice

Modeling and advanced sliding mode controls of crawler cranes considering wire rope elasticity and complicated operations

Science.gov (United States)

Tuan, Le Anh; Lee, Soon-Geul

2018-03-01

In this study, a new mathematical model of crawler cranes is developed for heavy working conditions, with payload-lifting and boom-hoisting motions simultaneously activated. The system model is built with full consideration of wind disturbances, geometrical nonlinearities, and cable elasticities of cargo lifting and boom luffing. On the basis of this dynamic model, three versions of sliding mode control are analyzed and designed to control five system outputs with only two inputs. When used in complicated operations, the effectiveness of the controllers is analyzed using analytical investigation and numerical simulation. Results indicate the effectiveness of the control algorithms and the proposed dynamic model. The control algorithms asymptotically stabilize the system with finite-time convergences, remaining robust amid disturbances and parametric uncertainties.

H-mode and confinement studies in ASDEX Upgrade

International Nuclear Information System (INIS)

Suttrop, W.; Ryter, F.; Mertens, V.; Gruber, O.; Murmann, H.; Salzmann, H.; Schweinzer, J.

2001-01-01

H-mode operational boundaries and H-mode confinement are investigated on ASDEX Upgrade. The local edge parameter threshold for H-mode holds independent of divertor geometry and changes little with ion mass. The deviation of the H-mode power threshold at densities near the Greenwald limit can be understood as a consequence of a confinement deterioration, caused by 'stiff' temperature profiles and lack of core density gradients in gas puff fuelled discharges. Ion and electron temperature profiles can be described by a lower limit of gradient length L T =T/T'. (author)