WorldWideScience

Sample records for polarization switching system

  1. All-fiber polarization switch

    Science.gov (United States)

    Knape, Harald; Margulis, Walter

    2007-03-01

    We report an all-fiber polarization switch made out of silica-based microstructured fiber suitable for Q-switching all-fiber lasers. Nanosecond high-voltage pulses are used to heat and expand an internal electrode to cause λ/2-polarization rotation in less than 10 ns for 1.5 μm light. The 10 cm long component has an experimentally measured optical insertion loss of 0.2 dB and a 0-10 kHz repetition frequency capacity and has been durability tested for more than 109 pulses.

  2. Nanoscale switch for vortex polarization mediated by Bloch core formation in magnetic hybrid systems

    Science.gov (United States)

    Wohlhüter, Phillip; Bryan, Matthew Thomas; Warnicke, Peter; Gliga, Sebastian; Stevenson, Stephanie Elizabeth; Heldt, Georg; Saharan, Lalita; Suszka, Anna Kinga; Moutafis, Christoforos; Chopdekar, Rajesh Vilas; Raabe, Jörg; Thomson, Thomas; Hrkac, Gino; Heyderman, Laura Jane

    2015-01-01

    Vortices are fundamental magnetic topological structures characterized by a curling magnetization around a highly stable nanometric core. The control of the polarization of this core and its gyration is key to the utilization of vortices in technological applications. So far polarization control has been achieved in single-material structures using magnetic fields, spin-polarized currents or spin waves. Here we demonstrate local control of the vortex core orientation in hybrid structures where the vortex in an in-plane Permalloy film coexists with out-of-plane maze domains in a Co/Pd multilayer. The vortex core reverses its polarization on crossing a maze domain boundary. This reversal is mediated by a pair of magnetic singularities, known as Bloch points, and leads to the transient formation of a three-dimensional magnetization structure: a Bloch core. The interaction between vortex and domain wall thus acts as a nanoscale switch for the vortex core polarization. PMID:26238042

  3. Quantum switching of polarization in mesoscopic ferroelectrics

    International Nuclear Information System (INIS)

    Sa de Melo, C.A.

    1996-01-01

    A single domain of a uniaxial ferroelectric grain may be thought of as a classical permanent memory. At the mesoscopic level this system may experience considerable quantum fluctuations due to tunneling between two possible memory states, thus destroying the classical permanent memory effect. To study these quantum effects the concrete example of a mesoscopic uniaxial ferroelectric grain is discussed, where the orientation of the electric polarization determines two possible memory states. The possibility of quantum switching of the polarization in mesoscopic uniaxial ferroelectric grains is thus proposed. To determine the degree of memory loss, the tunneling rate between the two polarization states is calculated at zero temperature both in the absence and in the presence of an external static electric field. In addition, a discussion of crossover temperature between thermally activated behavior and quantum tunneling behavior is presented. And finally, environmental effects (phonons, defects, and surfaces) are also considered. copyright 1996 The American Physical Society

  4. Stochastic multistep polarization switching in ferroelectrics

    Science.gov (United States)

    Genenko, Y. A.; Khachaturyan, R.; Schultheiß, J.; Ossipov, A.; Daniels, J. E.; Koruza, J.

    2018-04-01

    Consecutive stochastic 90° polarization switching events, clearly resolved in recent experiments, are described by a nucleation and growth multistep model. It extends the classical Kolmogorov-Avrami-Ishibashi approach and includes possible consecutive 90°- and parallel 180° switching events. The model predicts the results of simultaneous time-resolved macroscopic measurements of polarization and strain, performed on a tetragonal Pb (Zr ,Ti ) O3 ceramic in a wide range of electric fields over a time domain of seven orders of magnitude. It allows the determination of the fractions of individual switching processes, their characteristic switching times, activation fields, and respective Avrami indices.

  5. Saturated Switching Systems

    CERN Document Server

    Benzaouia, Abdellah

    2012-01-01

    Saturated Switching Systems treats the problem of actuator saturation, inherent in all dynamical systems by using two approaches: positive invariance in which the controller is designed to work within a region of non-saturating linear behaviour; and saturation technique which allows saturation but guarantees asymptotic stability. The results obtained are extended from the linear systems in which they were first developed to switching systems with uncertainties, 2D switching systems, switching systems with Markovian jumping and switching systems of the Takagi-Sugeno type. The text represents a thoroughly referenced distillation of results obtained in this field during the last decade. The selected tool for analysis and design of stabilizing controllers is based on multiple Lyapunov functions and linear matrix inequalities. All the results are illustrated with numerical examples and figures many of them being modelled using MATLAB®. Saturated Switching Systems will be of interest to academic researchers in con...

  6. Polarization switching kinetics in ultrathin ferroelectric barium titanate film

    Energy Technology Data Exchange (ETDEWEB)

    Gaynutdinov, R., E-mail: rgaynutdinov@gmail.com [Institute of Crystallography, Russian Academy of Sciences, Moscow 119333 (Russian Federation); Minnekaev, M., E-mail: m.minnekaev@gmail.com [NRNU Moscow Engineering Physics Institute, Moscow 115409 (Russian Federation); Mitko, S., E-mail: sergey_m@ntmdt.ru [NT-MDT Co., Moscow 124482 (Russian Federation); Tolstikhina, A., E-mail: alla@ns.crys.ras.ru [Institute of Crystallography, Russian Academy of Sciences, Moscow 119333 (Russian Federation); Zenkevich, A., E-mail: avzenkevich@mephi.ru [NRNU Moscow Engineering Physics Institute, Moscow 115409 (Russian Federation); NRC Kurchatov Institute, Moscow 123182 (Russian Federation); Ducharme, S., E-mail: sducharme@unl.edu [Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, NE 68588-0299 (United States); Fridkin, V., E-mail: fridkin@ns.crys.ras.ru [Institute of Crystallography, Russian Academy of Sciences, Moscow 119333 (Russian Federation)

    2013-09-01

    The investigation of polarization switching kinetics in an ultrathin barium titanate film reveals true threshold switching at a large coercive electric field, evidence that switching is of intrinsic thermodynamic nature, rather than of extrinsic nature initiated by thermal nucleation, which has no true threshold field. The switching speed of a 7 nm thick epitaxial film exhibits a critical slowing as the threshold is approached from above, a key characteristic of intrinsic switching. In contrast, a bulk crystal exhibits nucleation-initiated switching, which has no threshold, and proceeds even at fields well below the nominal coercive field, which was determined independently from the polarization-electric field hysteresis loop. Previously, this phenomenon was only reported for ultrathin ferroelectric polymer Langmuir–Blodgett films. Since both the thermodynamic coercive field and the intrinsic switching kinetics are derived from the mean field theory of ferroelectricity, we expect that these phenomena will be found in other ferroelectric films at the nanoscale.

  7. Optical switching systems using nanostructures

    DEFF Research Database (Denmark)

    Stubkjær, Kristian

    2004-01-01

    High capacity multiservice optical networks require compact and efficient switches. The potential benefits of optical switch elements based on nanostructured material are reviewed considering various material systems.......High capacity multiservice optical networks require compact and efficient switches. The potential benefits of optical switch elements based on nanostructured material are reviewed considering various material systems....

  8. Polarization dependent switching of asymmetric nanorings with a circular field

    Directory of Open Access Journals (Sweden)

    Nihar R. Pradhan

    2016-01-01

    Full Text Available We experimentally investigated the switching from onion to vortex states in asymmetric cobalt nanorings by an applied circular field. An in-plane field is applied along the symmetric or asymmetric axis of the ring to establish domain walls (DWs with symmetric or asymmetric polarization. A circular field is then applied to switch from the onion state to the vortex state, moving the DWs in the process. The asymmetry of the ring leads to different switching fields depending on the location of the DWs and direction of applied field. For polarization along the asymmetric axis, the field required to move the DWs to the narrow side of the ring is smaller than the field required to move the DWs to the larger side of the ring. For polarization along the symmetric axis, establishing one DW in the narrow side and one on the wide side, the field required to switch to the vortex state is an intermediate value.

  9. Control synthesis of switched systems

    CERN Document Server

    Zhao, Xudong; Niu, Ben; Wu, Tingting

    2017-01-01

    This book offers its readers a detailed overview of the synthesis of switched systems, with a focus on switching stabilization and intelligent control. The problems investigated are not only previously unsolved theoretically but also of practical importance in many applications: voltage conversion, naval piloting and navigation and robotics, for example. The book considers general switched-system models and provides more efficient design methods to bring together theory and application more closely than was possible using classical methods. It also discusses several different classes of switched systems. For general switched linear systems and switched nonlinear systems comprising unstable subsystems, it introduces novel ideas such as invariant subspace theory and the time-scheduled Lyapunov function method of designing switching signals to stabilize the underlying systems. For some typical switched nonlinear systems affected by various complex dynamics, the book proposes novel design approaches based on inte...

  10. Nanoscale mechanical switching of ferroelectric polarization via flexoelectricity

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Yijia; Hong, Zijian; Britson, Jason; Chen, Long-Qing [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2015-01-12

    Flexoelectric coefficient is a fourth-rank tensor arising from the coupling between strain gradient and electric polarization and thus exists in all crystals. It is generally ignored for macroscopic crystals due to its small magnitude. However, at the nanoscale, flexoelectric contributions may become significant and can potentially be utilized for device applications. Using the phase-field method, we study the mechanical switching of electric polarization in ferroelectric thin films by a strain gradient created via an atomic force microscope tip. Our simulation results show good agreement with existing experimental observations. We examine the competition between the piezoelectric and flexoelectric effects and provide an understanding of the role of flexoelectricity in the polarization switching. Also, by changing the pressure and film thickness, we reveal that the flexoelectric field at the film bottom can be used as a criterion to determine whether domain switching may happen under a mechanical force.

  11. Nanoscale mechanical switching of ferroelectric polarization via flexoelectricity

    International Nuclear Information System (INIS)

    Gu, Yijia; Hong, Zijian; Britson, Jason; Chen, Long-Qing

    2015-01-01

    Flexoelectric coefficient is a fourth-rank tensor arising from the coupling between strain gradient and electric polarization and thus exists in all crystals. It is generally ignored for macroscopic crystals due to its small magnitude. However, at the nanoscale, flexoelectric contributions may become significant and can potentially be utilized for device applications. Using the phase-field method, we study the mechanical switching of electric polarization in ferroelectric thin films by a strain gradient created via an atomic force microscope tip. Our simulation results show good agreement with existing experimental observations. We examine the competition between the piezoelectric and flexoelectric effects and provide an understanding of the role of flexoelectricity in the polarization switching. Also, by changing the pressure and film thickness, we reveal that the flexoelectric field at the film bottom can be used as a criterion to determine whether domain switching may happen under a mechanical force

  12. Nanoscale mechanical switching of ferroelectric polarization via flexoelectricity

    Science.gov (United States)

    Gu, Yijia; Hong, Zijian; Britson, Jason; Chen, Long-Qing

    2015-01-01

    Flexoelectric coefficient is a fourth-rank tensor arising from the coupling between strain gradient and electric polarization and thus exists in all crystals. It is generally ignored for macroscopic crystals due to its small magnitude. However, at the nanoscale, flexoelectric contributions may become significant and can potentially be utilized for device applications. Using the phase-field method, we study the mechanical switching of electric polarization in ferroelectric thin films by a strain gradient created via an atomic force microscope tip. Our simulation results show good agreement with existing experimental observations. We examine the competition between the piezoelectric and flexoelectric effects and provide an understanding of the role of flexoelectricity in the polarization switching. Also, by changing the pressure and film thickness, we reveal that the flexoelectric field at the film bottom can be used as a criterion to determine whether domain switching may happen under a mechanical force.

  13. Linearly polarized intracavity passive Q-switched Yb-doped ...

    Indian Academy of Sciences (India)

    2014-02-14

    Feb 14, 2014 ... Q-switched fibre lasers with high peak power have attracted a lot of attention due to many applications in the fields of industrial processing and medical treatments. For special applications of nonlinear frequency shifting like frequency doubling and optical paramet- ric oscillation, linearly polarized ...

  14. Multi-polar resistance switching and memory effect in copper phthalocyanine junctions

    International Nuclear Information System (INIS)

    Qiao Shi-Zhu; Kang Shi-Shou; Li Qiang; Zhong Hai; Kang Yun; Yu Shu-Yun; Han Guang-Bing; Yan Shi-Shen; Mei Liang-Mo; Qin Yu-Feng

    2014-01-01

    Copper phthalocyanine junctions, fabricated by magnetron sputtering and evaporating methods, show multi-polar (unipolar and bipolar) resistance switching and the memory effect. The multi-polar resistance switching has not been observed simultaneously in one organic material before. With both electrodes being cobalt, the unipolar resistance switching is universal. The high resistance state is switched to the low resistance state when the bias reaches the set voltage. Generally, the set voltage increases with the thickness of copper phthalocyanine and decreases with increasing dwell time of bias. Moreover, the low resistance state could be switched to the high resistance state by absorbing the phonon energy. The stability of the low resistance state could be tuned by different electrodes. In Au/copper phthalocyanine/Co system, the low resistance state is far more stable, and the bipolar resistance switching is found. Temperature dependence of electrical transport measurements demonstrates that there are no obvious differences in the electrical transport mechanism before and after the resistance switching. They fit quite well with Mott variable range hopping theory. The effect of Al 2 O 3 on the resistance switching is excluded by control experiments. The holes trapping and detrapping in copper phthalocyanine layer are responsible for the resistance switching, and the interfacial effect between electrodes and copper phthalocyanine layer affects the memory effect. (interdisciplinary physics and related areas of science and technology)

  15. Operation of a fast polarization-switching source at the Photon Factory

    Science.gov (United States)

    Tsuchiya, Kimichika; Shioya, Tatsuro; Aoto, Tomohiro; Harada, Kentaro; Obina, Takashi; Sakamaki, Masako; Amemiya, Kenta

    2013-03-01

    We have been developing a fast polarization-switching source for the vacuum ultraviolet and soft X-ray region at the B15-16 straight section of the 2.5-GeV Photon Factory (PF) storage ring. The source consists of two tandem APPLE-II-type elliptically polarizing undulators (EPUs), namely, U#16-1 and U#16-2, and a fast kicker system. The target frequency of polarization switching is 10 Hz. As the first step, we installed U#16-1 and five identical bump kickers in the PF ring in March 2008. Then, we constructed U#16-2 and installed it in August 2010. The orbit switching operation at 10 Hz, for user experiments, started in January 2012. We describe the details of the operation status of two EPUs and the fast local bump system in this report.

  16. Morphological control and polarization switching in polymer ...

    Indian Academy of Sciences (India)

    Abstract. Liquid crystals dispersed in polymer systems constitute novel class of optical materials. The precise control of the liquid crystal droplet morphology in the polymer matrix is essentially required to meet the pre- requisites of display device. Experiments have been carried out to investigate and identify the material pro-.

  17. Morphological control and polarization switching in polymer ...

    Indian Academy of Sciences (India)

    Liquid crystals dispersed in polymer systems constitute novel class of optical materials. The precise control of the liquid crystal droplet morphology in the polymer matrix is essentially required to meet the prerequisites of display device. Experiments have been carried out to investigate and identify the material properties and ...

  18. Switching of charged inverse micelles in non-polar liquids.

    Science.gov (United States)

    Prasad, Manoj; Beunis, Filip; Neyts, Kristiaan; Strubbe, Filip

    2015-11-15

    The electrodynamics of micellar ions in nonpolar liquids are well understood for the case that a voltage is applied or switched off. In this work, the electrodynamics of charged inverse micelles (CIMs) are studied when the applied voltage is switched to the opposite polarity, which is relevant for applications such as electrophoretic displays and liquid toner printing. Transient current measurements are used to characterize the switching of CIMs formed in a solution of surfactant polyisobutylene succinimide in n-dodecane. For reverse voltages with amplitude below 10V the measurements are in good agreement with a drift and diffusion model, confirming the established understanding of CIMs in nonpolar liquids. When the charge content is high, the reversal current shows a characteristic peak which is explained on the basis of dynamic space-charge effects. However, for reverse voltages larger than 10V, the transient currents are influenced by electrohydrodynamic flow in the liquid causing the CIMs to switch faster than predicted by the model. The occurrence of electrohydrodynamic flow is verified by optical tracking of tracer particles. Also, when the polarizing voltage is applied for longer times, an additional current peak emerges which is due to the accumulation of newly generated charges at the electrodes. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Polarization-Independent High-Speed Switching in a Standard Non-Linear Optical Loop Mirror

    DEFF Research Database (Denmark)

    Mulvad, Hans Christian Hansen; Galili, Michael; Oxenløwe, Leif Katsuo

    2008-01-01

    We introduce a scheme which allows polarization-independent switching in a standard NOLM. Experimental verification is performed by switching 10 Gbit/s data with 0.2 dB polarization-dependence and by error-free demultiplexing of polarization-scrambled 320 Gbit/s OTDM data....

  20. Circular polarization switching and bistability in an optically injected 1300 nm spin-vertical cavity surface emitting laser

    Energy Technology Data Exchange (ETDEWEB)

    Alharthi, S. S., E-mail: ssmalh@essex.ac.uk; Henning, I. D.; Adams, M. J. [School of Computer Science and Electronic Engineering, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom); Hurtado, A. [School of Computer Science and Electronic Engineering, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom); Institute of Photonics, Physics Department, University of Strathclyde, Wolfson Centre, 106 Rottenrow East, Glasgow G4 0NW, Scotland (United Kingdom); Korpijarvi, V.-M.; Guina, M. [Optoelectronics Research Centre (ORC), Tampere University of Technology, P.O. Box 692, FIN-33101 Tampere (Finland)

    2015-01-12

    We report the experimental observation of circular polarization switching (PS) and polarization bistability (PB) in a 1300 nm dilute nitride spin-vertical cavity surface emitting laser (VCSEL). We demonstrate that the circularly polarized optical signal at 1300 nm can gradually or abruptly switch the polarization ellipticity of the spin-VCSEL from right-to-left circular polarization and vice versa. Moreover, different forms of PS and PB between right- and left-circular polarizations are observed by controlling the injection strength and the initial wavelength detuning. These results obtained at the telecom wavelength of 1300 nm open the door for novel uses of spin-VCSELs in polarization sensitive applications in future optical systems.

  1. Magnetic Switching of a Single Molecular Magnet due to Spin-Polarized Current

    OpenAIRE

    Misiorny, Maciej; Barnas, Józef

    2006-01-01

    Magnetic switching of a single molecular magnet (SMM) due to spin-polarized current flowing between ferromagnetic metallic electrodes is investigated theoretically. Magnetic moments of the electrodes are assumed to be collinear and parallel to the magnetic easy axis of the molecule. Electrons tunneling through a barrier between magnetic leads are coupled to the SMM via exchange interaction. The current flowing through the system as well as the spin relaxation times of the SMM are calculated f...

  2. Complementary resistive switching in BaTiO{sub 3}/NiO bilayer with opposite switching polarities

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuo [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Institut d’Electronique de Micro-électronique et de Nanotechnologie (IEMN), CNRS, Université des Sciences et Technologies de Lille, avenue Poincaré, BP 60069, 59652, Villeneuve d’Ascq cedex (France); Wei, Xianhua, E-mail: weixianhua@swust.edu.cn [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Lei, Yao [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronics Science and Technology of China, Chengdu 610054 (China); Yuan, Xincai [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Zeng, Huizhong [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronics Science and Technology of China, Chengdu 610054 (China)

    2016-12-15

    Graphical abstract: Au/BaTiO{sub 3}/NiO/Pt bilayer device shows complementary resistive switching (CRS) without electroforming which is mainly ascribed to anti-serial stack of two RRAM cells with bipolar behaviors. - Highlights: • Complementary resistive switching (CRS) has been investigated in Au/BaTiO{sub 3}/NiO/Pt by stacking the two elements with different switching types. • The realization of complementary resistive switching (CRS) is mainly ascribed to the anti-serial stack of two RRAM cells with bipolar behaviors. • Complementary resistive switching (CRS) in bilayer is effective to solve the sneak current problem briefly and economically. - Abstract: Resistive switching behaviors have been investigated in the Au/BaTiO{sub 3}/NiO/Pt structure by stacking the two elements with different switching types. The conducting atomic force microscope measurements on BaTiO{sub 3} thin films and NiO thin films suggest that with the same active resistive switching region, the switching polarities in the two semiconductors are opposite to each other. It is in agreement with the bipolar hysteresis I–V curves with opposite switching polarities for single-layer devices. The bilayer devices show complementary resistive switching (CRS) without electroforming and unipolar resistive switching (URS) after electroforming. The coexistence of CRS and URS is mainly ascribed to the co-effect of electric field and Joule heating mechanisms, indicating that changeable of resistance in this device is dominated by the redistribution of oxygen vacancies in BaTiO{sub 3} and the formation, disruption, restoration of conducting filaments in NiO. CRS in bilayer with opposite switching polarities is effective to solve the sneak current without the introduction of any selector elements or an additional metal electrode.

  3. Model Reduction of Switched Systems Based on Switching Generalized Gramians

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza; Wisniewski, Rafal

    2012-01-01

    In this paper, a general method for model order reduction of discrete-time switched linear systems is presented. The proposed technique uses switching generalized gramians. It is shown that several classical reduction methods can be developed into the generalized gramian framework for the model...... reduction of linear systems and for the reduction of switched systems. Discrete-time balanced reduction within a specified frequency interval is taken as an example within this framework. To avoid numerical instability and to increase the numerical efficiency, a generalized gramian-based Petrov...

  4. Asymmetric bistable reflection and polarization switching in a magnetic nonlinear multilayer structure

    DEFF Research Database (Denmark)

    Tuz, Vladimir R.; Novitsky, Denis V.; Prosvirnin, Sergey L.

    2014-01-01

    , while light reflected from the other side has its polarization unchanged. Using the nonlinear transfer matrix calculations in the frequency domain, it is demonstrated that defect resonances in the nonlinear reflection spectra undergo bending, resulting in polarization bistability of reflected light....... This bistability is shown to result in abrupt switching between linear polarization of the output reflected light when the input intensity is varied. This switching is confirmed in finite-difference time-domain simulations, and its hysteresis character is established....

  5. Switching model photovoltaic pumping system

    Science.gov (United States)

    Anis, Wagdy R.; Abdul-Sadek Nour, M.

    Photovoltaic (PV) pumping systems are widely used due to their simplicity, high reliability and low cost. A directly-coupled PV pumping system is the most reliable and least-cost PV system. The d.c. motor-pump group is not, however, working at its optimum operating point. A battery buffered PV pumping system introduces a battery between the PV array and the d.c. motor-pump group to ensure that the motor-pump group is operating at its optimum point. The size of the battery storage depends on system economics. If the battery is fully charged while solar radiation is available, the battery will discharge through the load while the PV array is disconnected. Hence, a power loss takes place. To overcome the above mentioned difficulty, a switched mode PV pumping is proposed. When solar radiation is available and the battery is fully charged, the battery is disconnected and the d.c. motor-pump group is directly coupled to the PV array. To avoid excessive operating voltage for the motor, a part of the PV array is switched off to reduce the voltage. As a result, the energy loss is significantly eliminated. Detailed analysis of the proposed system shows that the discharged water increases by about 10% when compared with a conventional battery-buffered system. The system transient performance just after the switching moment shows that the system returns to a steady state in short period. The variations in the system parameters lie within 1% of the rated values.

  6. Switching in electrical transmission and distribution systems

    CERN Document Server

    Smeets, René; Kapetanovic, Mirsad; Peelo, David F; Janssen, Anton

    2014-01-01

    Switching in Electrical Transmission and Distribution Systems presents the issues and technological solutions associated with switching in power systems, from medium to ultra-high voltage. The book systematically discusses the electrical aspects of switching, details the way load and fault currents are interrupted, the impact of fault currents, and compares switching equipment in particular circuit-breakers. The authors also explain all examples of practical switching phenomena by examining real measurements from switching tests. Other highlights include: up to date commentary on new develo

  7. Micromagnetic investigation of the dynamics of magnetization switching induced by a spin polarized current

    Science.gov (United States)

    Lee, Kyung-Jin; Dieny, Bernard

    2006-03-01

    Using micromagnetic modeling, we tested a prediction of single-domain spin-torque theory which switching current density depends only weakly on magnetic cell size. The switching time and current density are strongly affected by the cell size for low spin polarization. Larger samples with a small length-to-width ratio and small spin polarization can exhibit a nonmonotonous dependence of switching time on current. Excitation of incoherent spin waves caused by the circular Oersted field due to the current is responsible for this nonmonotonous dependence. However, the magnetic dynamics recovers a single-domain-like behavior when the spin polarization is high and/or the cell size is small.

  8. Switching Phenomena in a System with No Switches

    Science.gov (United States)

    Preis, Tobias; Stanley, H. Eugene

    2010-02-01

    It is widely believed that switching phenomena require switches, but this is actually not true. For an intriguing variety of switching phenomena in nature, the underlying complex system abruptly changes from one state to another in a highly discontinuous fashion. For example, financial market fluctuations are characterized by many abrupt switchings creating increasing trends ("bubble formation") and decreasing trends ("financial collapse"). Such switching occurs on time scales ranging from macroscopic bubbles persisting for hundreds of days to microscopic bubbles persisting only for a few seconds. We analyze a database containing 13,991,275 German DAX Future transactions recorded with a time resolution of 10 msec. For comparison, a database providing 2,592,531 of all S&P500 daily closing prices is used. We ask whether these ubiquitous switching phenomena have quantifiable features independent of the time horizon studied. We find striking scale-free behavior of the volatility after each switching occurs. We interpret our findings as being consistent with time-dependent collective behavior of financial market participants. We test the possible universality of our result by performing a parallel analysis of fluctuations in transaction volume and time intervals between trades. We show that these financial market switching processes have properties similar to those of phase transitions. We suggest that the well-known catastrophic bubbles that occur on large time scales—such as the most recent financial crisis—are no outliers but single dramatic representatives caused by the switching between upward and downward trends on time scales varying over nine orders of magnitude from very large (≈102 days) down to very small (≈10 ms).

  9. Magnetic switching of a single molecular magnet due to spin-polarized current

    Science.gov (United States)

    Misiorny, Maciej; Barnaś, Józef

    2007-04-01

    Magnetic switching of a single molecular magnet (SMM) due to spin-polarized current flowing between ferromagnetic metallic leads (electrodes) is investigated theoretically. Magnetic moments of the leads are assumed to be collinear and parallel to the magnetic easy axis of the molecule. Electrons tunneling through the barrier between magnetic leads are coupled to the SMM via exchange interaction. The current flowing through the system, as well as the spin relaxation times of the SMM, are calculated from the Fermi golden rule. It is shown that spin of the SMM can be reversed by applying a certain voltage between the two magnetic electrodes. Moreover, the switching may be visible in the corresponding current-voltage characteristics.

  10. Research on disk amplifiers as polarizer of electro-optical switch

    International Nuclear Information System (INIS)

    Zheng Kuixing; Cai Bangwei; Feng Bin; Zheng Jiangang; Dong Yun; Peng Zhitao; Lu Jingping; Jing Feng; Wei Xiaofeng

    2002-01-01

    It benefits to decrease the engineering cost and to debase the technical crisis by the polarizer composed of amplifier Nd 3+ : glass slabs located with the Brewster angle in large scale multi-passes laser facility. The relationships of the isolation efficiency with the numbers of slab, the growth of the amplifier and the switch efficiency of Pockels cell are calculated theoretically. The experimental results indicated that the output energy ratio of this Pockels cell-amplifier isolation system is 1 : 8 while Pockels cell is on and off

  11. Research on disk amplifiers as polarizer of electro-optical switch

    CERN Document Server

    Zheng Kui Xing; Feng Bin; Zheng Jian; Dong Yun; Peng Zhi Tao; Lu Jing Ping; Jing Feng; Wei Xiao Feng

    2002-01-01

    It benefits to decrease the engineering cost and to debase the technical crisis by the polarizer composed of amplifier Nd sup 3 sup + : glass slabs located with the Brewster angle in large scale multi-passes laser facility. The relationships of the isolation efficiency with the numbers of slab, the growth of the amplifier and the switch efficiency of Pockels cell are calculated theoretically. The experimental results indicated that the output energy ratio of this Pockels cell-amplifier isolation system is 1 : 8 while Pockels cell is on and off

  12. Switching the response of metasurfaces in polarization standing waves

    OpenAIRE

    Fang, X.; MacDonald, K.F.; Zheludev, N.I.

    2015-01-01

    We demonstrate experimentally that standing waves of polarization, as opposed to intensity, can be engaged to coherently control light-matter interactions in planar photonic nanostructures, presenting unique opportunities for all-optical data processing and polarization-dependent molecular spectroscopy. Such waves, formed by counter-propagating (linear or circular) orthogonally polarized beams can, for example, uniquely detect polarization conversion, planar chirality and related asymmetric t...

  13. On formalism and stability of switched systems

    DEFF Research Database (Denmark)

    Leth, John-Josef; Wisniewski, Rafal

    2012-01-01

    In this paper, we formulate a uniform mathematical framework for studying switched systems with piecewise linear partitioned state space and state dependent switching. Based on known results from the theory of differential inclusions, we devise a Lyapunov stability theorem suitable for this class...... of switched systems. With this, we prove a Lyapunov stability theorem for piecewise linear switched systems by means of a concrete class of Lyapunov functions. Contrary to existing results on the subject, the stability theorems in this paper include Filippov (or relaxed) solutions and allow infinite switching...... in finite time. Finally, we show that for a class of piecewise linear switched systems, the inertia of the system is not sufficient to determine its stability. A number of examples are provided to illustrate the concepts discussed in this paper....

  14. Performance of a plasma opening switch in positive polarity on Gamble I using flashboard plasma sources

    International Nuclear Information System (INIS)

    Renk, T.J.

    1995-01-01

    The successful development of the Plasma Opening Switch (POS) for inductive storage applications has been largely confined to negative polarity operation. Some models of POS behavior suggest that this is because in a positive polarity coaxial configuration, the weaker magnetic field at the cathode position retards the switch opening process. This article describes experiments in which both conductor radii in the POS region were significantly reduced. Anode- and cathode-side current monitors indicate that voltages greater than open-circuit are generated at the POS position, but there is a significant amount of electron flow out of the POS, depending upon load impedance. Flow impedance analysis indicates that a relatively small gap appears in the POS plasma after switch opening. Switch performance is also compared between flashboard and carbon gun plasma sources, with the latter operated both in positive and negative polarity

  15. Nonvolatile data storage using mechanical force-induced polarization switching in ferroelectric polymer

    International Nuclear Information System (INIS)

    Chen, Xin; Tang, Xin; Chen, Xiang-Zhong; Chen, Yu-Lei; Shen, Qun-Dong; Guo, Xu; Ge, Hai-Xiong

    2015-01-01

    Ferroelectric polymers offer the promise of low-cost and flexible electronic products. They are attractive for information storage due to their spontaneous polarization which is usually switched by electric field. Here, we demonstrate that electrical signals can be readily written on ultra-thin ferroelectric polymer films by strain gradient-induced polarization switching (flexoelectric effect). A force with magnitude as small as 64nN is enough to induce highly localized (40 nm feature size) change in the polarization states. The methodology is capable of realizing nonvolatile memory devices with miniaturized cell size and storage density of tens to hundreds Gbit per square inch

  16. Evaluation of polarization mode dispersion in a telecommunication wavelength selective switch using quantum interferometry.

    Science.gov (United States)

    Fraine, A; Minaeva, O; Simon, D S; Egorov, R; Sergienko, A V

    2012-01-30

    A polarization mode dispersion (PMD) measurement of a commercial telecommunication wavelength selective switch (WSS) using a quantum interferometric technique with polarization-entangled states is presented. Polarization-entangled photons with a broad spectral width covering the telecom band are produced using a chirped periodically poled nonlinear crystal. The first demonstration of a quantum metrology application using an industrial commercial device shows a promising future for practical high-resolution quantum interference.

  17. Bistable polarization switching in a continuous wave ruby laser

    Science.gov (United States)

    Lawandy, N. M.; Afzal, R. Sohrab

    1988-01-01

    Bistability in the output power, polarization state, and mode volume of an argon-ion laser pumped single mode ruby laser at 6943 A has been observed. The laser operates in a radially confined mode which exhibits hysteresis and bistability only when the pump polarization is parallel to the c-axis.

  18. Linearly polarized intracavity passive Q-switched Yb-doped ...

    Indian Academy of Sciences (India)

    2014-02-14

    Feb 14, 2014 ... ratio of active core area to inner cladding area, the pump light absorption is improved and smaller fibre length becomes possible. There are reports on the passive Q-switching in. Yb-doped LMA fibre lasers by using Cr4+:YAG crystal as a saturable absorber. Huang et al have reported maximum average ...

  19. Switching Magnetism and Superconductivity with Spin-Polarized Current in Iron-Based Superconductor

    Science.gov (United States)

    Choi, Seokhwan; Choi, Hyoung Joon; Ok, Jong Mok; Lee, Yeonghoon; Jang, Won-Jun; Lee, Alex Taekyung; Kuk, Young; Lee, SungBin; Heinrich, Andreas J.; Cheong, Sang-Wook; Bang, Yunkyu; Johnston, Steven; Kim, Jun Sung; Lee, Jhinhwan

    2017-12-01

    We explore a new mechanism for switching magnetism and superconductivity in a magnetically frustrated iron-based superconductor using spin-polarized scanning tunneling microscopy (SPSTM). Our SPSTM study on single-crystal Sr2VO3FeAs shows that a spin-polarized tunneling current can switch the Fe-layer magnetism into a nontrivial C4 (2 ×2 ) order, which cannot be achieved by thermal excitation with an unpolarized current. Our tunneling spectroscopy study shows that the induced C4 (2 ×2 ) order has characteristics of plaquette antiferromagnetic order in the Fe layer and strongly suppresses superconductivity. Also, thermal agitation beyond the bulk Fe spin ordering temperature erases the C4 state. These results suggest a new possibility of switching local superconductivity by changing the symmetry of magnetic order with spin-polarized and unpolarized tunneling currents in iron-based superconductors.

  20. Switching Magnetism and Superconductivity with Spin-Polarized Current in Iron-Based Superconductor.

    Science.gov (United States)

    Choi, Seokhwan; Choi, Hyoung Joon; Ok, Jong Mok; Lee, Yeonghoon; Jang, Won-Jun; Lee, Alex Taekyung; Kuk, Young; Lee, SungBin; Heinrich, Andreas J; Cheong, Sang-Wook; Bang, Yunkyu; Johnston, Steven; Kim, Jun Sung; Lee, Jhinhwan

    2017-12-01

    We explore a new mechanism for switching magnetism and superconductivity in a magnetically frustrated iron-based superconductor using spin-polarized scanning tunneling microscopy (SPSTM). Our SPSTM study on single-crystal Sr_{2}VO_{3}FeAs shows that a spin-polarized tunneling current can switch the Fe-layer magnetism into a nontrivial C_{4} (2×2) order, which cannot be achieved by thermal excitation with an unpolarized current. Our tunneling spectroscopy study shows that the induced C_{4} (2×2) order has characteristics of plaquette antiferromagnetic order in the Fe layer and strongly suppresses superconductivity. Also, thermal agitation beyond the bulk Fe spin ordering temperature erases the C_{4} state. These results suggest a new possibility of switching local superconductivity by changing the symmetry of magnetic order with spin-polarized and unpolarized tunneling currents in iron-based superconductors.

  1. Fault tolerant control for switched linear systems

    CERN Document Server

    Du, Dongsheng; Shi, Peng

    2015-01-01

    This book presents up-to-date research and novel methodologies on fault diagnosis and fault tolerant control for switched linear systems. It provides a unified yet neat framework of filtering, fault detection, fault diagnosis and fault tolerant control of switched systems. It can therefore serve as a useful textbook for senior and/or graduate students who are interested in knowing the state-of-the-art of filtering, fault detection, fault diagnosis and fault tolerant control areas, as well as recent advances in switched linear systems.  

  2. Modeling of nonlinear responses for reciprocal transducers involving polarization switching

    DEFF Research Database (Denmark)

    Willatzen, Morten; Wang, Linxiang

    2007-01-01

    Nonlinearities and hysteresis effects in a reciprocal PZT transducer are examined by use of a dynamical mathematical model on the basis of phase-transition theory. In particular, we consider the perovskite piezoelectric ceramic in which the polarization process in the material can be modeled...... by Landau theory for the first-order phase transformation, in which each polarization state is associated with a minimum of the Landau free-energy function. Nonlinear constitutive laws are obtained by using thermodynamical equilibrium conditions, and hysteretic behavior of the material can be modeled...

  3. Linearly polarized intracavity passive Q-switched Yb-doped ...

    Indian Academy of Sciences (India)

    2014-02-14

    YAG crystal as a saturable absorber. An average output power of 9.4 W with pulse duration of 64 ns and pulse repetition rate of 57.4 kHz with a slope efficiency of 52% was achieved. Measured polarization extinction ratio (PER) ...

  4. All-optical 2-bit header recognition and packet switching using polarization bistable VCSELs.

    Science.gov (United States)

    Hayashi, Daisuke; Nakao, Kazuya; Katayama, Takeo; Kawaguchi, Hitoshi

    2015-04-06

    We propose and evaluate an all-optical 2-bit header recognition and packet switching method using two 1.55-µm polarization bistable vertical-cavity surface-emitting lasers (VCSELs) and three optical switches. Polarization bistable VCSELs acted as flip-flop devices by using AND-gate operations of the header and set pulses, together with the reset pulses. Optical packets including 40-Gb/s non-return-to-zero pseudo-random bit-sequence payloads were successfully sent to one of four ports according to the state of two bits in the headers with a 4-bit 500-Mb/s return-to-zero format. The input pulse powers were 17.2 to 31.8 dB lower than the VCSEL output power. We also examined an extension of this method to multi-bit header recognition and packet switching.

  5. Polarization control of high transmission/reflection switching by all-dielectric metasurfaces

    Science.gov (United States)

    Shibanuma, Toshihiko; Maier, Stefan A.; Albella, Pablo

    2018-02-01

    Metasurfaces built of high refractive dielectric nanostructures could play a key role in controlling the electromagnetic wave propagation, due to their low energy losses and their ability to excite not only electric but also magnetic resonances. In this study, we theoretically and experimentally demonstrate that an array of high-index dielectric nanodimers can perform as tuneable metasurfaces that can be switched from a high transmitter to a high reflector, by just changing the linear polarization of excitation. The incident polarization alters the hybridization mode of the excited electric and magnetic dipoles in the dimer, and this leads to either spectral overlap or separation of the two dipoles. The hybridization of the electric and magnetic modes modifies the effective permittivity and permeability of the tuneable dielectric metasurface, exhibiting the high transmission and reflection that can be easily switched by simply changing the linear polarization.

  6. System for measuring the proton polarization in a polarized target

    International Nuclear Information System (INIS)

    Karnaukhov, I.M.; Lukhanin, A.A.; Telegin, Yu.N.; Trotsenko, V.I.; Chechetenko, V.F.

    1984-01-01

    The system for measuring the proton polarization in a polarized target representing the high-sensitivity nuclear magnetic resonance (NMR) is described Q-meter with series connection and a circuit for measuring system resonance characteristic is used for NMR-absorption signal recording. Measuring coil is produced of a strip conductor in order to obtain uniform system sensitivity to polarization state in all target volume and improve signal-to-noise ratio. Polarization measuring system operates ion-line with the M-6000 computer. The total measuring error for the value of free proton polarization in target taking into account the error caused by local depolarization of working substance under irradiation by high-intense photon beam is <= 6%. Long-term application of the described system for measuring the proton polarization in the LUEh-20000 accelerator target used in the pion photoproduction experiments has demonstrated its high reliability

  7. Polarization switching and patterning in self-assembled peptide tubular structures

    Science.gov (United States)

    Bdikin, Igor; Bystrov, Vladimir; Delgadillo, Ivonne; Gracio, José; Kopyl, Svitlana; Wojtas, Maciej; Mishina, Elena; Sigov, Alexander; Kholkin, Andrei L.

    2012-04-01

    Self-assembled peptide nanotubes are unique nanoscale objects that have great potential for a multitude of applications, including biosensors, nanotemplates, tissue engineering, biosurfactants, etc. The discovery of strong piezoactivity and polar properties in aromatic dipeptides [A. Kholkin, N. Amdursky, I. Bdikin, E. Gazit, and G. Rosenman, ACS Nano 4, 610 (2010)] opened up a new perspective for their use as biocompatible nanoactuators, nanomotors, and molecular machines. Another, as yet unexplored functional property is the ability to switch polarization and create artificial polarization patterns useful in various electronic and optical applications. In this work, we demonstrate that diphenylalanine peptide nanotubes are indeed electrically switchable if annealed at a temperature of about 150 °C. The new orthorhombic antipolar structure that appears after annealing allows for the existence of a radial polarization component, which is directly probed by piezoresponse force microscopy (PFM) measurements. Observation of the relatively stable polarization patterns and hysteresis loops via PFM testifies to the local reorientation of molecular dipoles in the radial direction. The experimental results are complemented with rigorous molecular calculations and create a solid background of electric-field induced deformation of aromatic rings and corresponding polarization switching in this emergent material.

  8. Microprocessor Controlled Capacitor Bank Switching System for ...

    African Journals Online (AJOL)

    In this work, analysis and development of a microprocessor controlled capacitor bank switching system for deployment in a smart distribution network was carried out. This system was implemented by the use of discreet components such as resistors, capacitors, transistor, diode, automatic voltage regulator, with the ...

  9. Balanced truncation for linear switched systems

    DEFF Research Database (Denmark)

    Petreczky, Mihaly; Wisniewski, Rafal; Leth, John-Josef

    2013-01-01

    In this paper, we present a theoretical analysis of the model reduction algorithm for linear switched systems from Shaker and Wisniewski (2011, 2009) and . This algorithm is a reminiscence of the balanced truncation method for linear parameter varying systems (Wood et al., 1996) [3]. Specifically...

  10. Tip-induced domain structures and polarization switching in ferroelectric amino acid glycine

    Energy Technology Data Exchange (ETDEWEB)

    Seyedhosseini, E., E-mail: Seyedhosseini@ua.pt; Ivanov, M. [CICECO-Aveiro Institute of Materials and Department of Physics, University of Aveiro, 3810-193 Aveiro (Portugal); Bdikin, I. [TEMA and Department of Mechanical Engineering, University of Aveiro, 3810-193 Aveiro (Portugal); Vasileva, D. [Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Kudryavtsev, A. [Moscow State Institute of Radioengineering, Electronics and Automation, 119454 Moscow (Russian Federation); Rodriguez, B. J. [Conway Institute of Biomolecular and Biomedical Research and School of Physics, University College Dublin, Dublin (Ireland); Kholkin, A. L. [CICECO-Aveiro Institute of Materials and Department of Physics, University of Aveiro, 3810-193 Aveiro (Portugal); Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation)

    2015-08-21

    Bioorganic ferroelectrics and piezoelectrics are becoming increasingly important in view of their intrinsic compatibility with biological environment and biofunctionality combined with strong piezoelectric effect and a switchable polarization at room temperature. Here, we study tip-induced domain structures and polarization switching in the smallest amino acid β-glycine, representing a broad class of non-centrosymmetric amino acids. We show that β-glycine is indeed a room-temperature ferroelectric and polarization can be switched by applying a bias to non-polar cuts via a conducting tip of atomic force microscope (AFM). Dynamics of these in-plane domains is studied as a function of an applied voltage and pulse duration. The domain shape is dictated by polarization screening at the domain boundaries and mediated by growth defects. Thermodynamic theory is applied to explain the domain propagation induced by the AFM tip. Our findings suggest that the properties of β-glycine are controlled by the charged domain walls which in turn can be manipulated by an external bias.

  11. New Photonic System for Optical Packet Switching

    Directory of Open Access Journals (Sweden)

    F. Rudge Barbosa

    2003-08-01

    Full Text Available Fast optical switching (ms timebase is realized by using a RF frequency tone inserted in the optical packet that carries a digital payload. By using a highly selective RF filtering for optical packet header frequency recognition, we have obtained excellent performance in optical switching function.. The RF header is detected at optical node input, and signals the node switching control, which instantly directs the packet to a prescribed output. No electronic processing of the digital payload is performed. The optical circuit is noise-free, has very low crosstalk, and is extremely selective in header frequency detection. BER measurements for payload consistently yield figures as low as 10-12 . This system is applicable to optical metropolitan and access networks, and is fully compatible with DWDM systems.

  12. Shotgun lipidomics on a LTQ Orbitrap mass spectrometer by successive switching between acquisition polarity modes

    DEFF Research Database (Denmark)

    Schuhmann, K.; Almeida, R.; Baumert, M.

    2012-01-01

    Topdown shotgun lipidomics relies on direct infusion of total lipid extracts into a high-resolution tandem mass spectrometer and implies that individual lipids are recognized by their accurately determined m/z. Lipid ionization efficiency and detection specificity strongly depend on the acquisition...... polarity, and therefore it is beneficial to analyze lipid mixtures in both positive and negative modes. Hybrid LTQ Orbitrap mass spectrometers are widely applied in topdown lipidomics; however, rapid polarity switching was previously unfeasible because of the severe and immediate degradation of mass...

  13. Multiuser hybrid switched-selection diversity systems

    KAUST Repository

    Shaqfeh, Mohammad

    2011-09-01

    A new multiuser scheduling scheme is proposed and analyzed in this paper. The proposed system combines features of conventional full-feedback selection-based diversity systems and reduced-feedback switch-based diversity systems. The new hybrid system provides flexibility in trading-off the channel information feedback overhead with the prospected multiuser diversity gains. The users are clustered into groups, and the users\\' groups are ordered into a sequence. Per-group feedback thresholds are used and optimized to maximize the system overall achievable rate. The proposed hybrid system applies switched diversity criterion to choose one of the groups, and a selection criterion to decide the user to be scheduled from the chosen group. Numerical results demonstrate that the system capacity increases as the number of users per group increases, but at the cost of more required feedback messages. © 2011 IEEE.

  14. Bisimulation theory for switching linear systems

    NARCIS (Netherlands)

    Pola, G.; van der Schaft, Arjan; Di Benedetto, Maria D.

    2004-01-01

    A general notion of hybrid bisimulation is proposed and related to the notions of algebraic, state-space and input-output equivalences for the class of switching linear systems. An algebraic characterization of hybrid bisimulations and a procedure converging in a finite number of steps to the

  15. Disturbance Decoupling of Switched Linear Systems

    NARCIS (Netherlands)

    Yurtseven, E.; Heemels, W.P.M.H.; Camlibel, M.K.

    2010-01-01

    In this paper we consider disturbance decoupling problems for switched linear systems. We will provide necessary and sufficient conditions for three different versions of disturbance decoupling, which differ based on which signals are considered to be the disturbance. In the first version the

  16. A packet switched communications system for GRO

    Science.gov (United States)

    Husain, Shabu; Yang, Wen-Hsing; Vadlamudi, Rani; Valenti, Joseph

    1993-11-01

    This paper describes the packet switched Instrumenters Communication System (ICS) that was developed for the Command Management Facility at GSFC to support the Gamma Ray Observatory (GRO) spacecraft. The GRO ICS serves as a vital science data acquisition link to the GRO scientists to initiate commands for their spacecraft instruments. The system is ready to send and receive messages at any time, 24 hours a day and seven days a week. The system is based on X.25 and the International Standard Organization's (ISO) 7-layer Open Systems Interconnection (OSI) protocol model and has client and server components. The components of the GRO ICS are discussed along with how the Communications Subsystem for Interconnection (CSFI) and Network Control Program Packet Switching Interface (NPSI) software are used in the system.

  17. Electric polarization switching in an atomically thin binary rock salt structure

    Science.gov (United States)

    Martinez-Castro, Jose; Piantek, Marten; Schubert, Sonja; Persson, Mats; Serrate, David; Hirjibehedin, Cyrus F.

    2018-01-01

    Inducing and controlling electric dipoles is hindered in the ultrathin limit by the finite screening length of surface charges at metal-insulator junctions1-3, although this effect can be circumvented by specially designed interfaces4. Heterostructures of insulating materials hold great promise, as confirmed by perovskite oxide superlattices with compositional substitution to artificially break the structural inversion symmetry5-8. Bringing this concept to the ultrathin limit would substantially broaden the range of materials and functionalities that could be exploited in novel nanoscale device designs. Here, we report that non-zero electric polarization can be induced and reversed in a hysteretic manner in bilayers made of ultrathin insulators whose electric polarization cannot be switched individually. In particular, we explore the interface between ionic rock salt alkali halides such as NaCl or KBr and polar insulating Cu2N terminating bulk copper. The strong compositional asymmetry between the polar Cu2N and the vacuum gap breaks inversion symmetry in the alkali halide layer, inducing out-of-plane dipoles that are stabilized in one orientation (self-poling). The dipole orientation can be reversed by a critical electric field, producing sharp switching of the tunnel current passing through the junction.

  18. Optimization of multi-branch switched diversity systems

    KAUST Repository

    Nam, Haewoon

    2009-10-01

    A performance optimization based on the optimal switching threshold(s) for a multi-branch switched diversity system is discussed in this paper. For the conventional multi-branch switched diversity system with a single switching threshold, the optimal switching threshold is a function of both the average channel SNR and the number of diversity branches, where computing the optimal switching threshold is not a simple task when the number of diversity branches is high. The newly proposed multi-branch switched diversity system is based on a sequence of switching thresholds, instead of a single switching threshold, where a different diversity branch uses a different switching threshold for signal comparison. Thanks to the fact that each switching threshold in the sequence can be optimized only based on the number of the remaining diversity branches, the proposed system makes it easy to find these switching thresholds. Furthermore, some selected numerical and simulation results show that the proposed switched diversity system with the sequence of optimal switching thresholds outperforms the conventional system with the single optimal switching threshold. © 2009 IEEE.

  19. Progress in switching technology for METS systems

    International Nuclear Information System (INIS)

    Honig, E.M.; Swannack, C.E.; Warren, R.W.; Whitaker, D.H.

    1977-01-01

    Three distinct sets of switching requirements have emerged from design optimization studies of large superconducting magnetic energy storage systems, such as the METS system to power the adiabatic plasma compression field in the proposed theta-pinch SFTR. Extremely low joule loss cryogenic disconnects are required between storage coils in the liquid helium environment to allow charging the coils in series over a prolonged time, then to isolate the coils for parallel fast discharging into the load. Another switch must break the current in the series charging loop and absorb the energy from the stray inductance. This action will allow the subsequent opening of the cryogenic disconnects under near zero current condition. The current now has been transferred to the many paralleled circuits, each containing a high current, high voltage interrupter. The opening and arc commutation of the interrupter starts the energy transfer into the load. The primary activities associated with cryogenic disconnect have been testing and development of contact materials, configurations, and closing forces for carrying 26 kA with a resistance less than 40 nΩ, and development of an actuating system that is both reliable and fast acting in a liquid helium environment. The charging loop switch will include a continuous duty switch and a vacuum interrupter. The continuous duty switch resistance can be an order of magnitude larger than that of the cryogenic disconnect because it does not present a refrigeration load. The HVDC interrupter must break 26 kA and withstand 60 kV during the energy transfer time of 700 μs. Testing in progress already has shown successful interruption using single vacuum interrupters up to 31 kA and 66 kV

  20. Switched Systems and Motion Coordination: Combinatorial Challenges

    Science.gov (United States)

    Sadovsky, Alexander V.

    2016-01-01

    Problems of routing commercial air traffic in a terminal airspace encounter different constraints: separation assurance, aircraft performance limitations, regulations. The general setting of these problems is that of a switched control system. Such a system combines the differentiable motion of the aircraft with the combinatorial choices of choosing precedence when traffic routes merge and choosing branches when the routes diverge. This presentation gives an overview of the problem, the ATM context, related literature, and directions for future research.

  1. Robust dynamic output feedback control for switched polytopic systems under asynchronous switching

    Directory of Open Access Journals (Sweden)

    Yang Tingting

    2015-08-01

    Full Text Available The robust controller design problem for switched polytopic systems under asynchronous switching is addressed. These systems exist in many aviation applications, such as dynamical systems involving rapid variations. A switched polytopic system is established to describe the highly maneuverable technology vehicle within the full flight envelope and a robust dynamic output feedback control method is designed for the switched polytopic system. Combining the Lyapunov-like function method and the average dwell time method, a sufficient condition is derived for the switched polytopic system with asynchronous switching and data dropout to be globally, uniformly and asymptotically stable in terms of linear matrix inequality. The robust dynamic output feedback controller is then applied to the highly maneuverable technology vehicle to illustrate the effectiveness of the proposed approach. The simulation results show that the angle of attack tracking performance is acceptable over the time history and the control surface responses are all satisfying along the full flight trajectory.

  2. Atomic switch networks as complex adaptive systems

    Science.gov (United States)

    Scharnhorst, Kelsey S.; Carbajal, Juan P.; Aguilera, Renato C.; Sandouk, Eric J.; Aono, Masakazu; Stieg, Adam Z.; Gimzewski, James K.

    2018-03-01

    Complexity is an increasingly crucial aspect of societal, environmental and biological phenomena. Using a dense unorganized network of synthetic synapses it is shown that a complex adaptive system can be physically created on a microchip built especially for complex problems. These neuro-inspired atomic switch networks (ASNs) are a dynamic system with inherent and distributed memory, recurrent pathways, and up to a billion interacting elements. We demonstrate key parameters describing self-organized behavior such as non-linearity, power law dynamics, and multistate switching regimes. Device dynamics are then investigated using a feedback loop which provides control over current and voltage power-law behavior. Wide ranging prospective applications include understanding and eventually predicting future events that display complex emergent behavior in the critical regime.

  3. Design of frequency-encoded data-based optical master-slave-JK flip-flop using polarization switch

    Science.gov (United States)

    Mandal, Sumana; Mandal, Dhoumendra; Mandal, Mrinal Kanti; Garai, Sisir Kumar

    2017-06-01

    An optical data processing and communication system provides enormous potential bandwidth and a very high processing speed, and it can fulfill the demands of the present generation. For an optical computing system, several data processing units that work in the optical domain are essential. Memory elements are undoubtedly essential to storing any information. Optical flip-flops can store one bit of optical information. From these flip-flop registers, counters can be developed. Here, the authors proposed an optical master-slave (MS)-JK flip-flop with the help of two-input and three-input optical NAND gates. Optical NAND gates have been developed using semiconductor optical amplifiers (SOAs). The nonlinear polarization switching property of an SOA has been exploited here, and it acts as a polarization switch in the proposed scheme. A frequency encoding technique is adopted for representing data. A specific frequency of an optical signal represents a binary data bit. This technique of data representation is helpful because frequency is the fundamental property of a signal, and it remains unaltered during reflection, refraction, absorption, etc. throughout the data propagation. The simulated results enhance the admissibility of the scheme.

  4. The influence of preferred orientation and poling temperature on the polarization switching current in PZT thin films

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Mi; Zhang, Weikang; Zhang, Zebin; Zhang, Ping [Tianjin University, School of Electrical and Information Engineering, Tianjin (China); Lan, Kuibo [Tianjin University, School of Microelectronics, Tianjin (China)

    2017-07-15

    In this paper, Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} (PZT) thin films with different preferred orientation were prepared on platinized silicon substrates by a modified sol-gel method. Our results indicate that the polarization switching current in PZT thin films is dependent on preferred orientation and poling temperature. In our measurements, (111)-oriented PZT has a larger polarization switching current than randomly oriented PZT, and with the increase of the degree of (111) preferred orientation and the poling temperature, the polarization switching current gradually increase. Considering the contact of PZT thin film with electrodes, the space-charged limited conduction (SCLC) combined with domain switching mechanism may be responsible for such phenomena. By analyzing the conduction data, we found the interface-limited Schottky emission (ES) and bulk-limited Poole-Frenkel hopping (PF) are not suitable for our samples. (orig.)

  5. Stability analysis of linear switching systems with time delays

    International Nuclear Information System (INIS)

    Li Ping; Zhong Shouming; Cui Jinzhong

    2009-01-01

    The issue of stability analysis of linear switching system with discrete and distributed time delays is studied in this paper. An appropriate switching rule is applied to guarantee the stability of the whole switching system. Our results use a Riccati-type Lyapunov functional under a condition on the time delay. So, switching systems with mixed delays are developed. A numerical example is given to illustrate the effectiveness of our results.

  6. Instability in time-delayed switched systems induced by fast and random switching

    Science.gov (United States)

    Guo, Yao; Lin, Wei; Chen, Yuming; Wu, Jianhong

    2017-07-01

    In this paper, we consider a switched system comprising finitely or infinitely many subsystems described by linear time-delayed differential equations and a rule that orchestrates the system switching randomly among these subsystems, where the switching times are also randomly chosen. We first construct a counterintuitive example where even though all the time-delayed subsystems are exponentially stable, the behaviors of the randomly switched system change from stable dynamics to unstable dynamics with a decrease of the dwell time. Then by using the theories of stochastic processes and delay differential equations, we present a general result on when this fast and random switching induced instability should occur and we extend this to the case of nonlinear time-delayed switched systems as well.

  7. Polarization encoded all-optical quaternary successor with the help of SOA assisted Sagnac switch

    Science.gov (United States)

    Chattopadhyay, Tanay; Roy, Jitendra Nath

    2011-06-01

    The application of multi-valued (non-binary) signals can provide a considerable relief in transmission, storage and processing of large amount of information in digital signal processing. Optical multi-valued logical operation is an interesting challenge for future optical signal processing where we can expect much innovation. A novel all-optical quaternary successor (QSUC) circuit with the help of semiconductor optical amplifier (SOA)-assisted Sagnac switch is proposed and described. This circuit exploits the polarization properties of light. Different logical states are represented by different polarization state of light. Simulation result confirming described method is given in this paper. Proposed all-optical successor circuit can take an important and significant role in designing of all-optical quaternary universal inverter and modulo arithmetic unit (addition and multiplication).

  8. System for measuring of proton polarization in polarized target

    International Nuclear Information System (INIS)

    Derkach, A.Ya.; Lukhanin, A.A.; Karnaukhov, I.M.; Kuz'menko, V.S.; Telegin, Yu.N.; Trotsenko, V.I.; Chechetenko, V.F.

    1981-01-01

    Measurement system of proton polarization in the target, which uses the method of nuclear magnetic resonance is described. To record the signal of NMR-absorption a parallel Q-meter of voltage with analogous subtraction of resonance characteristics of measurement circuit is used. To obtain gradual sensitivity of the system to polarization state in the whole volume of the target the measurement coils is made of tape conductor. The analysis and mathematical modelling of Q-meter are carried out. Corrections for nonlinearity and dispersion are calculated. Key diagrams of the main electron blocks of Q-meter are presented. The system described operates on line with the M6000 computer. Total error of measurement of polarization value of free protons in the target does not exceed 6% [ru

  9. Electrocoagulation with polarity switch for fast oil removal from oil in water emulsions.

    Science.gov (United States)

    Gobbi, Lorena C A; Nascimento, Izabela L; Muniz, Eduardo P; Rocha, Sandra M S; Porto, Paulo S S

    2018-05-01

    An electrocoagulation technique using a 3.5 L reactor, with aluminum electrodes in a monopolar arrangement with polarity switch at each 10 s was used to separate oil from synthetic oily water similar in oil concentration to produced water from offshore platforms. Up to 98% of oil removal was achieved after 20 min of processing. Processing time dependence of the oil removal and pH was measured and successfully adjusted to exponential models, indicating a pseudo first order behavior. Statistical analysis was used to prove that electrical conductivity and total solids depend significantly on the concentration of electrolyte (NaCl) in the medium. Oil removal depends mostly on the distance between the electrodes but is proportional to electrolyte concentration when initial pH is 8. Electrocoagulation with polarity switch maximizes the lifetime of the electrodes. The process reduced oil concentration to a value below that stipulated by law, proving it can be an efficient technology to minimize the offshore drilling impact in the environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Ferroelectric Polarization Switching Dynamics and Domain Growth of Triglycine Sulfate and Imidazolium Perchlorate

    KAUST Repository

    Ma, He

    2016-04-10

    The weak bond energy and large anisotropic domain wall energy induce many special characteristics of the domain nucleation, growth, and polarization switch in triglycine sulfate (TGS) and imidazolium perchlorate (IM), two typical molecular ferroelectrics. Their domain nucleation and polarization switch are rather slower than those of conventional oxide ferroelectrics, which may be due to the weaker bond energy of hydrogen bond or van der Waals bond than that of ionic bond. These chemical bonds dominate the elastic energy, with the latter being an important component of domain wall energy and playing an important role in domain nucleation and domain growth. The ratio of anisotropic domain wall energy to Gibbs free energy is large in TGS and IM, which allows a favorable domain shape and a special domain evolution under a certain electric field. Therefore, this study not only sheds light on the physical nature but also indicates the application direction for molecular ferroelectrics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  11. Giant quadratic electro-optical effect during polarization switching in ultrathin ferroelectric polymer films

    Energy Technology Data Exchange (ETDEWEB)

    Blinov, L. M., E-mail: lev39blinov@gmail.com; Lazarev, V. V.; Palto, S. P.; Yudin, S. G. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2012-04-15

    The low-frequency quadratic electro-optical effect with a maximum electro-optical coefficient of g = 8 Multiplication-Sign 10{sup -19} m{sup 2}/V{sup 2} (i.e., four orders of magnitude greater than the standard high-frequency value) has been studied in thin films of ferroelectric polymer PVDF(70%)-TrFE(30%). The observed effect is related to the process of spontaneous polarization switching, during which the electron oscillators of C-F and C-H dipole groups rotate to become parallel to the applied field. As a result, the ellipsoid of the refractive index exhibits narrowing in the direction perpendicular to the field. The field dependence of the electro-optical coefficient g correlates with that of the apparent dielectric permittivity, which can be introduced under the condition of ferroelectric polarization switching. The observed electro-optical effect strongly decreases when the frequency increases up to several hundred hertz. The temperature dependence of the effect exhibits clearly pronounced hysteresis in the region of the ferroelectric phase transition.

  12. Switching of a spin-spiral-induced polarization in multiferroic MnWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, Tim; Meier, Dennis; Fiebig, Manfred [HISKP, Universitaet Bonn (Germany); Becker-Bohaty, Petra; Bohaty, Ladislav [Institut fuer Kristallographie, Universitaet zu Koeln (Germany)

    2010-07-01

    Coexisting ferroic orders become interesting when there is an interaction between them. Especially applying an electric field and thus changing the magnetic order is highly desirable for possible applications. In spite of the declared interest in multiferroics to switch a magnetization by an electric field nothing is known about the dynamics of the actual switching process. The coupling of ferroelectric and magnetic order is intrinsically strong in spin-spiral multiferroics, where ferroelectricity emerges as a consequence of complex magnetic long-range order. Here we observe the manipulation of magnetically-induced ferroelectric domains in MnWO{sub 4} by optical second harmonic generation (SHG). Application of an electric field allows to transform the sample to an electric as well as magnetic single-domain state. Moreover we obtained images of the domain structures during the transition revealing the growth of the domains. When cooled in zero-field, the domains have a bubble-like topology. Interestingly, after recovery from a single domain state the shape changes to a stripe structure and the domain size is significantly increased. Effects of the shape and duration of the electric-field poling pulses are investigated. Furthermore, in contrast to typical ionic ferroelectrics the spontaneous polarization can be switched without fatigue - no defects or pinning effects constrain the movement of domain walls.

  13. Energetic ion emission in a positive polarity nanosecond plasma opening switch

    International Nuclear Information System (INIS)

    Sarfaty, M.; Krasik, Ya.E.; Weingarten, A.; Fruchtman, A.; Maron, Y.

    1996-01-01

    The emission was studied of energetic ions from the plasma in a coaxial Plasma Opening Switch (POS) powered by a 300 kV, 15 kA, 90 ns positive polarity pulse. Fluxes lasting 2 - 3 ns of ions flowing radially onto the cathode were observed at all axial locations of the switch plasma within 5 ns of the beginning of the upstream POS current. It is suggested that the termination of this ion flux is due to the formation of a cathode plasma, which is consistent with our spectroscopic measurements. Later in the pulse, longer duration (100 ns) ion fluxes were observed radially, first appearing in the generator side of the switch plasma. Fluxes 30 - 40 ns long of ions flowing axially towards the POS load at velocities (2±1) x 10 8 cm/s were also observed. The dependences of the start time of the axial ion flow, of the ion velocities, and of the ion flux on the POS operation parameters were studied. (author). 6 figs., 5 refs

  14. System of measurement of proton polarization in a polarized target

    Energy Technology Data Exchange (ETDEWEB)

    Karnaukov, I.M.; Chechetenko, V.F.; Lukhanin, A.A.; Telegin, Y.N.; Trotsenko, V.I.

    1985-05-01

    This paper describes a nuclear magnetic resonance spectrometer with high sensitivity. The signal of NMR absorption is recorded by a Q-meter with a series circuit and a circuit for compensation of the resonance characteristic of the measuring circuit. In order to ensure uniform sensitivity of the system to the state of polarization throughout the volume of the target and to enhance the S/N ration the measuring coil is made of a flat conductor. The polarization-measuring system works on-line with an M-6000 computer. The total error of measurement of the polarization of free protons in a target with allowance for the error due to local depolarization of free protons in a target with allowance for the error due to local depolarization of the working substance under irradiation with an intense photon beam is less than or equal to 6%.

  15. New stability and stabilization for switched neutral control systems

    International Nuclear Information System (INIS)

    Xiong Lianglin; Zhong Shouming; Ye Mao; Wu Shiliang

    2009-01-01

    This paper concerns stability and stabilization issues for switched neutral systems and presents new classes of piecewise Lyapunov functionals and multiple Lyapunov functionals, based on which, two new switching rules are introduced to stabilize the neutral systems. One switching rule is designed from the solution of the so-called Lyapunov-Metzler linear matrix inequalities. The other is based on the determination of average dwell time computed from a new class of linear matrix inequalities (LMIs). And then, state-feedback control is derived for the switched neutral control system mainly based on the state switching rules. Finally, three examples are given to demonstrate the effectiveness of the proposed method.

  16. Multi-Polarization Reconfigurable Antenna for Wireless Biomedical System.

    Science.gov (United States)

    Wong, Hang; Lin, Wei; Huitema, Laure; Arnaud, Eric

    2017-06-01

    This paper presents a multi-polarization reconfigurable antenna with four dipole radiators for biomedical applications in body-centric wireless communication system (BWCS). The proposed multi-dipole antenna with switchable 0°, +45°, 90° and -45° linear polarizations is able to overcome the polarization mismatching and multi-path distortion in complex wireless channels as in BWCS. To realize this reconfigurable feature for the first time among all the reported antenna designs, we assembled four dipoles together with 45° rotated sequential arrangements. These dipoles are excited by the same feeding source provided by a ground tapered Balun. A metallic reflector is placed below the dipoles to generate a broadside radiation. By introducing eight PIN diodes as RF switches between the excitation source and the four dipoles, we can control a specific dipole to operate. As the results, 0°, +45°, 90° and -45° linear polarizations can be switched correspondingly to different operating dipoles. Experimental results agree with the simulation and show that the proposed antenna well works in all polarization modes with desirable electrical characteristics. The antenna has a wide impedance bandwidth of 34% from 2.2 to 3.1 GHz (for the reflection coefficient ≤ -10 dB) and exhibits a stable cardioid-shaped radiation pattern across the operating bandwidth with a peak gain of 5.2 dBi. To validate the effectiveness of the multi-dipole antenna for biomedical applications, we also designed a meandered PIFA as the implantable antenna. Finally, the communication link measurement shows that our proposed antenna is able to minimize the polarization mismatching and maintains the optimal communication link thanks to its polarization reconfigurability.

  17. Robust Stability Analysis of Nonlinear Switched Systems with Filippov Solutions

    DEFF Research Database (Denmark)

    Ahmadi, Mohamadreza; Mojallali, Hamed; Wisniewski, Rafal

    2012-01-01

    This paper addresses the stability problem of a class of nonlinear switched systems with partitioned state-space and state-dependent switching. In lieu of the Caratheodory solutions, the general Filippov solutions are considered. This encapsulates solutions with infinite switching in finite time....... which provides sufficient means to construct the corresponding Lyapunov functions via available semi-definite programming techniques....

  18. Organization of the channel-switching process in parallel computer systems based on a matrix optical switch

    Science.gov (United States)

    Golomidov, Y. V.; Li, S. K.; Popov, S. A.; Smolov, V. B.

    1986-01-01

    After a classification and analysis of electronic and optoelectronic switching devices, the design principles and structure of a matrix optical switch is described. The switching and pair-exclusion operations in this type of switch are examined, and a method for the optical switching of communication channels is elaborated. Finally, attention is given to the structural organization of a parallel computer system with a matrix optical switch.

  19. Room-Temperature Magnetic Switching of the Electric Polarization in Ferroelectric Nanopillars.

    Science.gov (United States)

    Poddar, Shashi; de Sa, Pedro; Cai, Ronggang; Delannay, Laurent; Nysten, Bernard; Piraux, Luc; Jonas, Alain M

    2018-01-23

    Magnetoelectric layers with a strong coupling between ferroelectricity and ferromagnetism offer attractive opportunities for the design of new device architectures such as dual-channel memory and multiresponsive sensors and actuators. However, materials in which a magnetic field can switch an electric polarization are extremely rare, work most often only at very low temperatures, and/or comprise complex materials difficult to integrate. Here, we show that magnetostriction and flexoelectricity can be harnessed to strongly couple electric polarization and magnetism in a regularly nanopatterned magnetic metal/ferroelectric polymer layer, to the point that full reversal of the electric polarization can occur at room temperature by the sole application of a magnetic field. Experiments supported by finite element simulations demonstrate that magnetostriction produces large strain gradients at the base of the ferroelectric nanopillars in the magnetoelectric hybrid layer, translating by flexoelectricity into equivalent electric fields larger than the coercive field of the ferroelectric polymer. Our study shows that flexoelectricity can be advantageously used to create a very strong magnetoelectric coupling in a nanopatterned hybrid layer.

  20. Dynamically Switching the Polarization State of Light Based on the Phase Transition of Vanadium Dioxide

    Science.gov (United States)

    Jia, Zhi-Yong; Shu, Fang-Zhou; Gao, Ya-Jun; Cheng, Feng; Peng, Ru-Wen; Fan, Ren-Hao; Liu, Yongmin; Wang, Mu

    2018-03-01

    There have been great endeavors devoted to manipulating the polarization state of light by plasmonic nanostructures in recent decades. However, the topic of active polarizers has attracted much less attention. We present a composite plasmonic nanostructure consisting of vanadium dioxide that can dynamically modulate the polarization state of the reflected light through a thermally induced phase transition of vanadium dioxide. We design a system consisting of anisotropic plasmonic nanostructures with vanadium dioxide that exhibits distinct reflections subjected to different linearly polarized incidence at room temperature and in the heated state. Under a particular linearly polarized incidence, the polarization state of the reflected light changes at room temperature, and reverts to its original polarization state above the phase-transition temperature. The composite structure can also be used to realize a dynamically switchable infrared image, wherein a pattern can be visualized at room temperature while it disappears above the phase-transition temperature. The composite structure could be potentially used for versatile optical modulators, molecular detection, and polarimetric imaging.

  1. Snapshot Mueller matrix polarimetry by wavelength polarization coding and application to the study of switching dynamics in a ferroelectric liquid crystal cell.

    Directory of Open Access Journals (Sweden)

    Le Jeune B.

    2010-06-01

    Full Text Available This paper describes a snapshot Mueller matrix polarimeter by wavelength polarization coding. This device is aimed at encoding polarization states in the spectral domain through use of a broadband source and high-order retarders. This allows one to measure a full Mueller matrix from a single spectrum whose acquisition time only depends on the detection system aperture. The theoretical fundamentals of this technique are developed prior to validation by experiments. The setup calibration is described as well as optimization and stabilization procedures. Then, it is used to study, by time-resolved Mueller matrix polarimetry, the switching dynamics in a ferroelectric liquid crystal cell.

  2. The Ultrathin Limit and Dead-layer Effects in Local Polarization Switching of BiFeO3

    Energy Technology Data Exchange (ETDEWEB)

    Maksymovych, Petro [ORNL; Huijben, Mark [University of Twente, Netherlands; Pan, Minghu [ORNL; Jesse, Stephen [ORNL; Balke, Nina [ORNL; Chang, Hye Jung [ORNL; Borisevich, Albina Y [ORNL; Baddorf, Arthur P [ORNL; Rijnders, Guus [MESA+ University of Twente, Enschede, Netherlands; Blank, Dave H. A. [University of Twente, Netherlands; Ramesh, R. [University of California, Berkeley; Kalinin, Sergei V [ORNL

    2012-01-01

    Using piezoresponse force microscopy in ultra-high vacuum, polarization switching has been detected and quantified in epitaxial BiFeO3 films from 200 down to ~ 4 unit cells. Local remnant piezoresponse was used to infer the applied electric field inside the ferroelectric volume, and account for the elusive effect of dead-layers in ultrathin films. The dead-layer manifested itself in the slower than anticipated decrease of the switching bias with film thickness, yielding apparent Kay-Dunn scaling of the switching field, while the statistical analysis of hysteresis loops revealed lateral variation of the dead-layer with sub-10 nm resolution.

  3. Magnetically switched power supply system for lasers

    Science.gov (United States)

    Pacala, Thomas J. (Inventor)

    1987-01-01

    A laser power supply system is described in which separate pulses are utilized to avalanche ionize the gas within the laser and then produce a sustained discharge to cause the gas to emit light energy. A pulsed voltage source is used to charge a storage device such as a distributed capacitance. A transmission line or other suitable electrical conductor connects the storage device to the laser. A saturable inductor switch is coupled in the transmission line for containing the energy within the storage device until the voltage level across the storage device reaches a predetermined level, which level is less than that required to avalanche ionize the gas. An avalanche ionization pulse generating circuit is coupled to the laser for generating a high voltage pulse of sufficient amplitude to avalanche ionize the laser gas. Once the laser gas is avalanche ionized, the energy within the storage device is discharged through the saturable inductor switch into the laser to provide the sustained discharge. The avalanche ionization generating circuit may include a separate voltage source which is connected across the laser or may be in the form of a voltage multiplier circuit connected between the storage device and the laser.

  4. Optimal Control of Switching Linear Systems

    Directory of Open Access Journals (Sweden)

    Ali Benmerzouga

    2004-06-01

    Full Text Available A solution to the control of switching linear systems with input constraints was given in Benmerzouga (1997 for both the conventional enumeration approach and the new approach. The solution given there turned out to be not unique. The main objective in this work is to determine the optimal control sequences {Ui(k ,  i = 1,..., M ;  k = 0, 1, ...,  N -1} which transfer the system from a given initial state  X0  to a specific target state  XT  (or to be as close as possible by using the same discrete time solution obtained in Benmerzouga (1997 and minimizing a running cost-to-go function. By using the dynamic programming technique, the optimal solution is found for both approaches given in Benmerzouga (1997. The computational complexity of the modified algorithm is also given.

  5. Switched diversity approach for multireceiving optical wireless systems.

    Science.gov (United States)

    Moradi, Hassan; Refai, Hazem H; Lopresti, Peter G

    2011-10-10

    A number of existing spatial diversity schemes have been shown to improve the performance of optical wireless communication systems in diversity-rich environments. Among all, switched diversity has low complexity and is simple to implement. In this paper, an innovative spatial diversity scheme based on switched diversity is proposed. The scheme, namely switch-to-dominant combining, contributes to a higher bit error rate (BER) performance when compared to conventional switched diversity schemes, including switch-and-stay and switch-and-examine diversity. The optical multireceiver wireless system operates in a spatially correlated and lognormally distributed fading channel. Analytical analyses are conducted to demonstrate BER and processing load performance offered by the new scheme and compare them to available schemes, i.e., conventional switched combining and selection combining. © 2011 Optical Society of America

  6. Polarization-selective vortex-core switching by tailored orthogonal Gaussian-pulse currents

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Young-Sang; Lee, Ki-Suk; Jung, Hyunsung; Choi, Youn-Seok; Yoo, Myoung-Woo; Han, Dong-Soo; Im, Mi-Young; Fischer, Peter; Kim, Sang-Koog

    2011-05-01

    We experimentally demonstrate low-power-consumption vortex-core switching in magnetic nanodisks using tailored rotating magnetic fields produced with orthogonal and unipolar Gaussian-pulse currents. The optimal width of the orthogonal pulses and their time delay are found, from analytical and micromagnetic numerical calculations, to be determined only by the angular eigenfrequency ωD for a given vortex-state disk of polarization p, such that σ=1/ωD and Δt=π/2p/ωD. The estimated optimal pulse parameters are in good agreement with the experimental results. Finally, this work lays a foundation for energy-efficient information recording in vortex-core cross-point architecture.

  7. A Density-Dependent Switch Drives Stochastic Clustering and Polarization of Signaling Molecules

    Science.gov (United States)

    Jilkine, Alexandra; Angenent, Sigurd B.; Wu, Lani F.; Altschuler, Steven J.

    2011-01-01

    Positive feedback plays a key role in the ability of signaling molecules to form highly localized clusters in the membrane or cytosol of cells. Such clustering can occur in the absence of localizing mechanisms such as pre-existing spatial cues, diffusional barriers, or molecular cross-linking. What prevents positive feedback from amplifying inevitable biological noise when an un-clustered “off” state is desired? And, what limits the spread of clusters when an “on” state is desired? Here, we show that a minimal positive feedback circuit provides the general principle for both suppressing and amplifying noise: below a critical density of signaling molecules, clustering switches off; above this threshold, highly localized clusters are recurrently generated. Clustering occurs only in the stochastic regime, suggesting that finite sizes of molecular populations cannot be ignored in signal transduction networks. The emergence of a dominant cluster for finite numbers of molecules is partly a phenomenon of random sampling, analogous to the fixation or loss of neutral mutations in finite populations. We refer to our model as the “neutral drift polarity model.” Regulating the density of signaling molecules provides a simple mechanism for a positive feedback circuit to robustly switch between clustered and un-clustered states. The intrinsic ability of positive feedback both to create and suppress clustering is a general mechanism that could operate within diverse biological networks to create dynamic spatial organization. PMID:22102805

  8. A density-dependent switch drives stochastic clustering and polarization of signaling molecules.

    Directory of Open Access Journals (Sweden)

    Alexandra Jilkine

    2011-11-01

    Full Text Available Positive feedback plays a key role in the ability of signaling molecules to form highly localized clusters in the membrane or cytosol of cells. Such clustering can occur in the absence of localizing mechanisms such as pre-existing spatial cues, diffusional barriers, or molecular cross-linking. What prevents positive feedback from amplifying inevitable biological noise when an un-clustered "off" state is desired? And, what limits the spread of clusters when an "on" state is desired? Here, we show that a minimal positive feedback circuit provides the general principle for both suppressing and amplifying noise: below a critical density of signaling molecules, clustering switches off; above this threshold, highly localized clusters are recurrently generated. Clustering occurs only in the stochastic regime, suggesting that finite sizes of molecular populations cannot be ignored in signal transduction networks. The emergence of a dominant cluster for finite numbers of molecules is partly a phenomenon of random sampling, analogous to the fixation or loss of neutral mutations in finite populations. We refer to our model as the "neutral drift polarity model." Regulating the density of signaling molecules provides a simple mechanism for a positive feedback circuit to robustly switch between clustered and un-clustered states. The intrinsic ability of positive feedback both to create and suppress clustering is a general mechanism that could operate within diverse biological networks to create dynamic spatial organization.

  9. Model Reduction of Linear Switched Systems by Restricting Discrete Dynamics

    DEFF Research Database (Denmark)

    Bastug, Mert; Petreczky, Mihaly; Wisniewski, Rafal

    2014-01-01

    We present a procedure for reducing the number of continuous states of discrete-time linear switched systems, such that the reduced system has the same behavior as the original system for a subset of switching sequences. The proposed method is expected to be useful for abstraction based control...

  10. Ultrathin limit and dead-layer effects in local polarization switching of BiFeO3

    NARCIS (Netherlands)

    Maksymovych, P.; Huijben, Mark; Pan, M.; Jesse, S.; Balke, N.; Chu, Y.H.; Chang, H.J.; Borisevich, A.Y.; Baddorf, A.P.; Rijnders, Augustinus J.H.M.; Blank, David H.A.; Ramesh, R.; Kalinin, S.V.

    2012-01-01

    Using piezoresponse force microscopy in an ultrahigh vacuum, polarization switching has been detected and quantified in epitaxial BiFeO3 films from 200 to about 4 unit cells thick. Local remnant piezoresponse was utilized to probe both ferroelectric properties and effects of imperfect electrical

  11. Radially polarized and passively Q-switched Yb-doped fiber laser based on intracavity birefringent mode discrimination

    Science.gov (United States)

    Sun, Xuehuan; Wu, Yongxiao; Chen, Sanbin; Li, Jianlang

    2018-05-01

    In this paper, we demonstrated a passive Q-switched ytterbium-doped fiber laser with radially polarized beam emission by using a c-cut YVO4 birefringent crystal as the intracavity polarization discriminator, and a Cr4+:YAG crystal as the saturable absorber and output coupler. The maximum averaged laser power reached 3.89 W with a high slope efficiency of 66.5%. The laser pulse had a peak power of 161 W, 160 ns duration, and 151 kHz repetition rate at the absorbed pump power of 6.48 W. Such a radially polarized pulse would facilitate numerous applications.

  12. Modelling switching power converters as complementarity systems

    NARCIS (Netherlands)

    Camlibel, Mehmet; Iannelli, Luigi; Vasca, Francesco

    2004-01-01

    Switched complementarity models of linear circuits with ideal diodes and/or ideal switches allow one to study well-posedness and stability issues for these circuits by employing the complementarity problems of the mathematical programming. In this paper, we demonstrate that other types of typical

  13. Consensus of Switched Multiagent Systems under Relative State Constraints

    Directory of Open Access Journals (Sweden)

    Qingling Wang

    2017-01-01

    Full Text Available The consensus problem is presented for the switched multiagent system (MAS, where the MAS is switched between continuous- and discrete-time systems with relative state constraints. With some standard assumptions, we obtain the fact that the switched MAS with relative state constraints can achieve consensus under both fixed undirected graphs and switching undirected graphs. Furthermore, based on the absolute average value of initial states, we propose sufficient conditions for consensus of the switched MAS. The challenge of this study is that relative state constraints are considered, which will make the consensus problem much more complex. One of the main contributions is that, for the switched MAS with relative state constraints, we explore the solvability of the consensus problem. Finally, we present two simulation examples to show the effectiveness of the results.

  14. A study on switched linear system identification using game ...

    African Journals Online (AJOL)

    This study deals with application of game-theoretic strategies and neural computing to switched linear system identification, wherein some of the subsystems may be in failed, standby, or working states. The controller is to detect failed subsystems, and switch standby and working subsystems to maintain stable system ...

  15. Polarization phenomena in few-body systems

    International Nuclear Information System (INIS)

    Conzett, H.E.

    1975-12-01

    Recent polarization studies in N--N scattering at and below 50 MeV have provided specific and significant improvements in the phase-shift parameters. High energy investigations with both polarized proton beams and targets have shown unexpectedly large spin effects, and this provides a challenge for theoretical effort to explain these results. Experimental and theoretical work on the three-nucleon problem continues to yield new and interesting results, with the emphasis now shifting to polarization studies in the breakup reaction. On-going work on several-nucleon systems continues to provide polarization data for general analyses, nuclear structure information, or specific resonance effects. Finally, the basic interaction symmetries continue to have unique and important consequences for polarization observables. 17 figures

  16. Automatic Control System Switching Roadway Lighting

    OpenAIRE

    Agus Trimuji Susilo; Lingga Hermanto Drs. MM

    2002-01-01

    Lack of attention to the information officer street lights, cause is not exactly the timewhen the blame lights street lighting street - the street in this city protocol. And whenit was already dark, the lights had not lit, so it can harm the users of the road. Werecommend that when it got bright lights - the lights switched off late, so muchelectricity is wasted with nothing - nothing.Given the problems above, the automatic switching is required that can control all thelights - the existing l...

  17. [Cell polarity in the cardiovascular system].

    Science.gov (United States)

    Haller, C; Kübler, W

    1999-05-01

    The importance of cell polarity as a fundamental biological principle is increasingly recognized in the cardiovascular system. Polar cell mechanisms underlie not only the development of the heart and blood vessels, but also play a major role in the adult organism for polarized endothelial functions such as the separation of the intra- and extravascular compartment and the vectorial exchange of substances between these compartments. Endothelial cells are connected through intercellular junctions which separate the functionally and structurally distinct luminal and abluminal cell surfaces. The luminal plasma membrane is in contact with the blood and takes part in the regulation of hemostasis. The abluminal cell membrane connects the endothelial cell with the basement membrane and modulates blood flow through the release of vasoactive substances. Results from epithelial model systems have shown that the polarized cell phenotype is generated by specific protein sorting and regulated protein trafficking between the trans-Golgi network and the cell surface. The polarized distribution of cell membrane proteins is maintained by anchorage with the cytoskeleton and limitation of lateral diffusion by tight junctions. Disturbances of cell polarity may contribute to the pathogenesis of disease states, including ischemic and radiocontrast-induced acute renal failure and carcinomas. Recent results have demonstrated the importance of cholesterol for protein traffic from the trans-Golgi network to the apical cell membrane. This novel intracellular function of cholesterol could point to a connection between cell polarity and the pathogenesis of arteriosclerosis. The polarity of the endothelium also has to be taken into account when developing gene-therapeutic strategies, since therapeutic success will not only depend on the efficient expression of the desired gene product, but also on its correct cellular location or secretion into the correct extracellular compartment. These

  18. Perfect switching of the spin polarization in a ferromagnetic gapless graphene/superconducting gapped graphene junction

    International Nuclear Information System (INIS)

    Soodchomshom, Bumned; Tang, I-Ming; Hoonsawat, Rassmidara

    2010-01-01

    With the fabrication of gapped graphene, interest in the tunneling spectroscopy in graphene-based FG/SG junctions in which one side consists of a gapless ferro-magnetic graphene (FG) and the other side, of a gapped superconducting graphene (SG) has arisen. The carriers in the gapless (gapped) graphene are 2D relativistic particles having an energy spectrum given by E=√(h 2 v F 2 k 2 +(mv F 2 ) 2 ) (where mv F 2 is the gap and v F is the Fermi velocity). The spin currents in this FG/SG junction are obtained within the framework of the extended Blonder-Tinkham-Klapwijk (BTK) formalism. The effects of the superconducting energy gap in SG, of the gap mv F 2 which opened in the superconducting graphene, of the exchange field in FG, of the spin-dependent specular Andreev reflection, of the effective Fermi energy (E FF ) of FG and of the bias voltage across the junction (V) are simulated. It is seen that by adjusting E FF or V, the spin polarization (defined as SP(%) = 100% x (G ↑ - G ↓ )/(G ↑ + G ↓ )) can be switched from a pure spin up (SP = +100%) state to pure spin down (SP = -100%) state.

  19. Dependence of polar effect on parameters of coaxial plasma-erosive switches

    International Nuclear Information System (INIS)

    Bystritskij, V.M.; Ivanov, I.B.; Krasik, Ya.E.; Ryzhakin, N.N.; Sinebryukhov, A.A.; Tolmacheva, V.G.

    1988-01-01

    The results of experimental investigations and numerical simulation of the polar effect in a coaxial plasma-erosive switch (PES) established in a circuit of a strong-current nanosecond accelerator are presented. PES characteristics (energy losses, impedance, rate of its increase, etc.) are investigated depending on mutual direction of accelerator current and plasma flow as well as on the cathode radius in the PES region. It is experimentally shown that the magnetic fields near the cathode determined by this electrode radius influences mainly on PES characteristics. Mutual direction of accelerator current and plasma flow is the second significance factor influencing on PES characteristics. The optimal mode of PES operation is realized when providing the less with respect to the positive electrode, cathode radius and coinciding in direction accelerator current and plasma flow. Numerical simulation of dynamic processes in coaxial PES for different ratios of cathode and anode radii and mutual directions of accelerator current and plasma flow gives qualitative agreement with the experimental results

  20. Robust filtering and fault detection of switched delay systems

    CERN Document Server

    Wang, Dong; Wang, Wei

    2013-01-01

    Switched delay systems appear in a wide field of applications including networked control systems, power systems, memristive systems. Though the large amount of ideas with respect to such systems have generated, until now, it still lacks a framework to focus on filter design and fault detection issues which are relevant to life safety and property loss. Beginning with the comprehensive coverage of the new developments in the analysis and control synthesis for switched delay systems, the monograph not only provides a systematic approach to designing the filter and detecting the fault of switched delay systems, but it also covers the model reduction issues. Specific topics covered include: (1) Arbitrary switching signal where delay-independent and delay-dependent conditions are presented by proposing a linearization technique. (2) Average dwell time where a weighted Lyapunov function is come up with dealing with filter design and fault detection issues beside taking model reduction problems. The monograph is in...

  1. On the observer design problem for continuous-time switched linear systems with unknown switchings

    Czech Academy of Sciences Publication Activity Database

    Gómez–Gutiérrez, D.; Čelikovský, Sergej; Ramírez–Trevino, A.; Castillo-Toledo, B.

    2015-01-01

    Roč. 352, č. 4 (2015), s. 1595-1612 ISSN 0016-0032 R&D Projects: GA ČR GA13-20433S Institutional support: RVO:67985556 Keywords : observer design * switched systems Subject RIV: BC - Control Systems Theory Impact factor: 2.327, year: 2015 http://library.utia.cas.cz/separaty/2015/TR/celikovsky-0442959.pdf

  2. Enhanced bipolar resistive switching behavior in polar Cr-doped barium titanate thin films without electro-forming process

    Directory of Open Access Journals (Sweden)

    Atul Thakre

    2017-12-01

    Full Text Available An enhanced, repeatable and robust resistive switching phenomenon was observed in Cr substituted BaTiO3 polar ferroelectric thin films; fabricated and deposited by the sol-gel approach and spin coating technique, respectively. An enhanced bistable bipolar resistive switching (BRS phenomenon without electro-forming process, low switching voltage (∼ 2 V and moderate retention characteristics of 104 s along with a high Roff/Ron resistance ratio ∼103 was achieved. The current conduction analysis showed that the space charge limited conduction (SCLC and Schottky emission conduction dominate in the high voltage range, while thermally active charge carriers (ohmic in the lower voltage range. The impedance spectroscopy study indicates the formation of current conducting path and rupturing of oxygen vacancies during SET and RESET process.

  3. Enhanced bipolar resistive switching behavior in polar Cr-doped barium titanate thin films without electro-forming process

    Science.gov (United States)

    Thakre, Atul; Kumar, Ashok

    2017-12-01

    An enhanced, repeatable and robust resistive switching phenomenon was observed in Cr substituted BaTiO3 polar ferroelectric thin films; fabricated and deposited by the sol-gel approach and spin coating technique, respectively. An enhanced bistable bipolar resistive switching (BRS) phenomenon without electro-forming process, low switching voltage (˜ 2 V) and moderate retention characteristics of 104 s along with a high Roff/Ron resistance ratio ˜103 was achieved. The current conduction analysis showed that the space charge limited conduction (SCLC) and Schottky emission conduction dominate in the high voltage range, while thermally active charge carriers (ohmic) in the lower voltage range. The impedance spectroscopy study indicates the formation of current conducting path and rupturing of oxygen vacancies during SET and RESET process.

  4. Synchronization of switched system and application in communication

    International Nuclear Information System (INIS)

    Yu Wenwu; Cao Jinde; Yuan Kun

    2008-01-01

    In this Letter, synchronization of switched system is investigated based on Lyapunov method. A sufficient condition is derived to ensure the synchronization between two switched systems, and a new communication scheme is also proposed based on this. Furthermore, some secure analysis works, such as return map attack and moving average error attack, are also given to show the security of the proposed scheme. Finally, simulation examples are constructed to verify the theoretical analysis and its application for communication

  5. Switched Systems With Multiple Invariant Sets

    Science.gov (United States)

    2015-05-06

    larger superset. We show the effectiveness of the dwell-time conditions by using examples of switching limit cycles commonly found in robotic locomotion ...commonly found in robotic locomotion and apping ight. 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as Report...1 −1 1 −1 ]( x y ) + ( 2 −2 ) . This is a simplified version of (1), a central pattern generator used for control of swimming [12] or flying robots [2

  6. Switched-Observer-Based Adaptive Neural Control of MIMO Switched Nonlinear Systems With Unknown Control Gains.

    Science.gov (United States)

    Long, Lijun; Zhao, Jun

    2017-07-01

    In this paper, the problem of adaptive neural output-feedback control is addressed for a class of multi-input multioutput (MIMO) switched uncertain nonlinear systems with unknown control gains. Neural networks (NNs) are used to approximate unknown nonlinear functions. In order to avoid the conservativeness caused by adoption of a common observer for all subsystems, an MIMO NN switched observer is designed to estimate unmeasurable states. A new switched observer-based adaptive neural control technique for the problem studied is then provided by exploiting the classical average dwell time (ADT) method and the backstepping method and the Nussbaum gain technique. It effectively handles the obstacle about the coexistence of multiple Nussbaum-type function terms, and improves the classical ADT method, since the exponential decline property of Lyapunov functions for individual subsystems is no longer satisfied. It is shown that the technique proposed is able to guarantee semiglobal uniformly ultimately boundedness of all the signals in the closed-loop system under a class of switching signals with ADT, and the tracking errors converge to a small neighborhood of the origin. The effectiveness of the approach proposed is illustrated by its application to a two inverted pendulum system.

  7. Research on generating various polarization-modes in polarized illumination system

    Science.gov (United States)

    Huang, Jinping; Lin, Wumei; Fan, Zhenjie

    2013-08-01

    With the increase of the numerical aperture (NA), the polarization of light affects the imaging quality of projection lens more significantly. On the contrary, according to the mask pattern, the resolution of projection lens can be improved by using the polarized illumination. That is to say, using the corresponding polarized beam (or polarization-mode) along with the off-axis illumination will improve the resolution and the imaging quality of the of projection lens. Therefore, the research on the generation of various polarization modes and its conversion methods become more and more important. In order to realize various polarization modes in polarized illumination system, after read a lot of references, we provide a way that fitting for the illumination system with the wavelength of 193nm.Six polarization-modes and a depolarized mode are probably considered. Wave-plate stack is used to generate linearly polarization-mode, which have a higher degree polarization. In order to generate X-Y and Y-X polarization mode, the equipment consisting of four sectors of λ/2 wave plate was used. We combined 16 sectors of λ/2 wave plate which have different orientations of the "slow" axis to generate radial and azimuthal polarization. Finally, a multi-polarization control device was designed. Using the kind of multi-polarization control device which applying this method could help to choose the polarization modes conveniently and flexibility for the illumination system.

  8. Multi-switching synchronization of chaotic systems with active controllers

    International Nuclear Information System (INIS)

    Ucar, Ahmet; Lonngren, Karl E.; Bai, Er-Wei

    2008-01-01

    This paper reports the results of an investigation of the multi-switching synchronization of coupled chaotic systems via active controls. The synchronization is achieved with the slave-master scheme, and it is extended to investigate the synchronization problems with different combinations of slave states with master systems. The different active controller are designed for the chosen slave system states to be synchronized with the target master system states. The multi-switching synchronization of Lorenz system is considered. Numerical simulations are provided for illustration and verification of the proposed method

  9. Optimal control of switched systems arising in fermentation processes

    CERN Document Server

    Liu, Chongyang

    2014-01-01

    The book presents, in a systematic manner, the optimal controls under different mathematical models in fermentation processes. Variant mathematical models – i.e., those for multistage systems; switched autonomous systems; time-dependent and state-dependent switched systems; multistage time-delay systems and switched time-delay systems – for fed-batch fermentation processes are proposed and the theories and algorithms of their optimal control problems are studied and discussed. By putting forward novel methods and innovative tools, the book provides a state-of-the-art and comprehensive systematic treatment of optimal control problems arising in fermentation processes. It not only develops nonlinear dynamical system, optimal control theory and optimization algorithms, but can also help to increase productivity and provide valuable reference material on commercial fermentation processes.

  10. Control of delay dominant systems with costs related to switching

    DEFF Research Database (Denmark)

    Deng, Honglian; Larsen, Lars Finn Sloth; Stoustrup, Jakob

    2010-01-01

    The objective of this paper is to extend a novel low complexity method for optimizing switch control developed by the authors earlier to work with delay dominant systems and demonstrate that the method works in practice with a refrigeration test system. The extended method solves switching problems...... for high order systems which can be approximated as a first order with a delay as well. The extension of the method is realized with an observer to retrieve the delay-free information. Experimental validation of the extended method is carried out with a test system. A comparison to a baseline relay...

  11. A Microcontroller-Based Automatic Transfer Switching System for a ...

    African Journals Online (AJOL)

    Michael

    2015-06-01

    Jun 1, 2015 ... The spate of frequent power outages without an effective back-up system is truly a disincentive to investors in any developing economy like Ghana (Kolo, 2007). Indeed, the ravages of power instability have equally necessitated automation of the switching system between national grid energy system and.

  12. Efficient high-pulse-energy eye-safe laser generated by an intracavity Nd:YLF/KTP optical parametric oscillator: role of thermally induced polarization switching

    International Nuclear Information System (INIS)

    Huang, Y J; Tang, C Y; Huang, Y P; Cho, C Y; Su, K W; Chen, Y F

    2012-01-01

    A high-pulse-energy eye-safe laser at 1552 nm is effectually generated by an intracavity Nd:YLF/KTP optical parametric oscillator (OPO) with the help of the thermally induced polarization switching. The polarization characteristics of the c-cut Nd:YLF laser at 1053 nm in the continuous-wave (CW) and Q-switched operation are comprehensively investigated. We experimentally verify the thermally induced birefringence can lead to a polarization switching between the mutually orthogonal components of the fundamental pulses. Consequently, an efficient intracavity nonlinear frequency conversion can be achieved in an optically isotropic laser crystal without any additional polarization control. With this finding, the pulse energy and peak power of the compact Nd:YLF/KTP eye-safe laser under an incident pump power of 12.7 W and a pulse repetition rate of 5 kHz are up to 306 μJ and 4 kW, respectively

  13. Polarization sensitive optical frequency domain imaging system for endobronchial imaging

    NARCIS (Netherlands)

    Li, J.; Feroldi, Fabio; de Lange, J.; Daniels, J.M.A.; Grünberg, K.; de Boer, J.F.

    2015-01-01

    A polarization sensitive endoscopic optical frequency domain imaging (PS-OFDI) system with a motorized distal scanning catheter is demonstrated. It employs a passive polarization delay unit to multiplex two orthogonal probing polarization states in depth, and a polarization diverse detection unit to

  14. Enhancement of polar anchoring strength in a graphene-nematic suspension and its effect on nematic electro-optic switching

    Science.gov (United States)

    Basu, Rajratan

    2017-07-01

    A small quantity of monolayer graphene flakes is doped in a nematic liquid crystal (LC), and the effective polar anchoring strength coefficient between the LC and the alignment substrate is found to increase by an order of magnitude. The hexagonal pattern of graphene can interact with the LC's benzene rings via π -π electron stacking, enabling the LC to anchor to the graphene surface homogeneously (i.e., planar anchoring). When the LC cell is filled with the graphene-doped LC, some graphene flakes are preferentially attached to the alignment layer and modify the substrate's anchoring property. These spontaneously deposited graphene flakes promote planar anchoring at the substrate and the polar anchoring energy at alignment layer is enhanced significantly. The enhanced anchoring energy is found to impact favorably on the electro-optic response of the LC. Additional studies reveal that the nematic electro-optic switching is significantly faster in the LC-graphene hybrid than that of the pure LC.

  15. Switching between Sensory and Affective Systems Incurs Processing Costs

    Science.gov (United States)

    Vermeulen, Nicolas; Niedenthal, Paula M.; Luminet, Olivier

    2007-01-01

    Recent models of the conceptual system hold that concepts are grounded in simulations of actual experiences with instances of those concepts in sensory-motor systems (e.g., Barsalou, 1999, 2003; Solomon & Barsalou, 2001). Studies supportive of such a view have shown that verifying a property of a concept in one modality, and then switching to…

  16. Model Reduction by Moment Matching for Linear Switched Systems

    DEFF Research Database (Denmark)

    Bastug, Mert; Petreczky, Mihaly; Wisniewski, Rafal

    2014-01-01

    A moment-matching method for the model reduction of linear switched systems (LSSs) is developed. The method is based based upon a partial realization theory of LSSs and it is similar to the Krylov subspace methods used for moment matching for linear systems. The results are illustrated by numerical...

  17. Theoretical analysis of balanced truncation for linear switched systems

    DEFF Research Database (Denmark)

    Petreczky, Mihaly; Wisniewski, Rafal; Leth, John-Josef

    2012-01-01

    In this paper we present theoretical analysis of model reduction of linear switched systems based on balanced truncation, presented in [1,2]. More precisely, (1) we provide a bound on the estimation error using L2 gain, (2) we provide a system theoretic interpretation of grammians and their singu...

  18. Polarization Switching and Light-Enhanced Piezoelectricity in Lead Halide Perovskites.

    Science.gov (United States)

    Coll, Mariona; Gomez, Andrés; Mas-Marza, Elena; Almora, Osbel; Garcia-Belmonte, Germà; Campoy-Quiles, Mariano; Bisquert, Juan

    2015-04-16

    We investigate the ferroelectric properties of photovoltaic methylammonium lead halide CH3NH3PbI3 perovskite using piezoelectric force microscopy (PFM) and macroscopic polarization methods. The electric polarization is clearly observed by amplitude and phase hysteresis loops. However, the polarization loop decreases as the frequency is lowered, persisting for a short time only, in the one second regime, indicating that CH3NH3PbI3 does not exhibit permanent polarization at room temperature. This result is confirmed by macroscopic polarization measurement based on a standard capacitive method. We have observed a strong increase of piezoelectric response under illumination, consistent with the previously reported giant photoinduced dielectric constant at low frequencies. We speculate that an intrinsic charge transfer photoinduced dipole in the perovskite cage may lie at the origin of this effect.

  19. Switching and energy-storage characteristics in PLZT 2/95/5 antiferroelectric ceramic system

    Directory of Open Access Journals (Sweden)

    A. Peláiz-Barranco

    2016-12-01

    Full Text Available Switching mechanisms and energy-storage properties have been investigated in (Pb0.98La0.02(Zr0.95Ti0.050.995O3 antiferroelectric ceramics. The electric field dependence of polarization (P–E hysteresis loops indicates that both the ferroelectric (FE and antiferroelectric (AFE phases coexist, being the AFE more stable above 100∘C. It has been observed that the temperature has an important influence on the switching parameters. On the other hand, the energy-storage density, which has been calculated from the P–E hysteresis loops, shows values higher than 1J/cm3 for temperatures above 100∘C with around 73% of efficiency as average. These properties indicate that the studied ceramic system reveals as a promising AFE material for energy-storage devices application.

  20. Magnetization switching of a metallic nanomagnet via current-induced surface spin-polarization of an underlying topological insulator

    International Nuclear Information System (INIS)

    Roy, Urmimala; Dey, Rik; Pramanik, Tanmoy; Ghosh, Bahniman; Register, Leonard F.; Banerjee, Sanjay K.

    2015-01-01

    We consider a thermally stable, metallic nanoscale ferromagnet (FM) subject to spin-polarized current injection and exchange coupling from the spin-helically locked surface states of a topological insulator (TI) to evaluate possible non-volatile memory applications. We consider parallel transport in the TI and the metallic FM, and focus on the efficiency of magnetization switching as a function of transport between the TI and the FM. Transport is modeled as diffusive in the TI beneath the FM, consistent with the mobility in the TI at room temperature, and in the FM, which essentially serves as a constant potential region albeit spin-dependent except in the low conductivity, diffusive limit. Thus, it can be captured by drift-diffusion simulation, which allows for ready interpretation of the results. We calculate switching time and energy consumed per write operation using self-consistent transport, spin-transfer-torque (STT), and magnetization dynamics calculations. Calculated switching energies and times compare favorably to conventional spin-torque memory schemes for substantial interlayer conductivity. Nevertheless, we find that shunting of current from the TI to a metallic nanomagnet can substantially limit efficiency. Exacerbating the problem, STT from the TI effectively increases the TI resistivity. We show that for optimum performance, the sheet resistivity of the FM layer should be comparable to or larger than that of the TI surface layer. Thus, the effective conductivity of the FM layer becomes a critical design consideration for TI-based non-volatile memory

  1. A Novel Single Phase Hybrid Switched Reluctance Motor Drive System

    DEFF Research Database (Denmark)

    Liang, Jianing; Xu, Guoqing; Jian, Linni

    2011-01-01

    phase boost converter is applied to improve the performance of this motor. It is easy to generate a double dclink voltage and dc-link voltage and switch both of them. The voltage of boost capacitor is self balance, so the protective circuit is not need to consider. The fast excitation mode helps hybrid......In this paper, a novel single phase hybrid switched reluctance motor(SRM) drive system is proposed. It integrated a single phase hybrid SRM and a novel single phase boost converter. This motor can reduce the number of phase switch. And the permanent magnet which is used in the motor can improve...... the performance and efficiency of SR motor. However, the inherent characteristic of this motor is that the negative torque is very sensitive with the excitation current near the turn-on angle. The slow excitation current limits the torque generation region and reduces the average torque. Therefore, a novel single...

  2. Stabilization of switched nonlinear systems with unstable modes

    CERN Document Server

    Yang, Hao; Cocquempot, Vincent

    2014-01-01

    This book provides its reader with a good understanding of the stabilization of switched nonlinear systems (SNS), systems that are of practical use in diverse situations: design of fault-tolerant systems in space- and aircraft; traffic control; and heat propagation control of semiconductor power chips. The practical background is emphasized throughout the book; interesting practical examples frequently illustrate the theoretical results with aircraft and spacecraft given particular prominence. Stabilization of Switched Nonlinear Systems with Unstable Modes treats several different subclasses of SNS according to the characteristics of the individual system (time-varying and distributed parameters, for example), the state composition of individual modes and the degree and distribution of instability in its various modes. Achievement and maintenance of stability across the system as a whole is bolstered by trading off between individual modes which may be either stable or unstable, or by exploiting areas of part...

  3. Data Transparent and Polarization Insensitive All-Optical Switch based on Fibers with Enhanced Nonlinearity

    Directory of Open Access Journals (Sweden)

    M. Komanec

    2014-09-01

    Full Text Available We have developed a data transparent optical packet switch prototype employing wavelength conversion based on four-wave mixing. The switch is composed of an electro-optical control unit and an all-optical switching segment. To achieve higher switching efficiencies, Ge-doped silica suspended-core and chalcogenide arsenicselenide single-mode fibers were experimentally evaluated and compared to conventional highly-nonlinear fiber. Improved connectorization technology has been developed for Ge-doped suspended-core fiber, where we achieved connection losses of 0.9 dB. For the arsenic-selenide fiber we present a novel solid joint technology, with connection losses of only 0.25 dB, which is the lowest value presented up-to-date. Conversion efficiency of -13.7 dB was obtained for the highly-nonlinear fiber, which is in perfect correlation with previously published results and thus verifies the functionality of the prototype. Conversion efficiency of -16.1 dB was obtained with arsenic-selenide fiber length reduced to five meters within simulations, based on measurement results with a 26 m long component. Employment of such a short arsenic-selenide fiber segment allows significant broadening of the wavelength conversion spectral range due to possible neglection of dispersion.

  4. Apparatus and Method for Elimination of Polarization-Induced Fading in Fiber-optic Sensor System

    Science.gov (United States)

    Chan, Hon Man (Inventor); Parker, Jr., Allen R. (Inventor)

    2015-01-01

    The invention is an apparatus and method of eliminating polarization-induced fading in interferometric fiber-optic sensor system having a wavelength-swept laser optical signal. The interferometric return signal from the sensor arms are combined and provided to a multi-optical path detector assembly and ultimately to a data acquisition and processing unit by way of a switch that is time synchronized with the laser scan sweep cycle.

  5. High Performance Gigabit Ethernet Switches for DAQ Systems

    CERN Document Server

    Barczyk, Artur

    2005-01-01

    Commercially available high performance Gigabit Ethernet (GbE) switches are optimized mostly for Internet and standard LAN application traffic. DAQ systems on the other hand usually make use of very specific traffic patterns, with e.g. deterministic arrival times. Industry's accepted loss-less limit of 99.999% may be still unacceptably high for DAQ purposes, as e.g. in the case of the LHCb readout system. In addition, even switches passing this criteria under random traffic can show significantly higher loss rates if subject to our traffic pattern, mainly due to buffer memory limitations. We have evaluated the performance of several switches, ranging from "pizza-box" devices with 24 or 48 ports up to chassis based core switches in a test-bed capable to emulate realistic traffic patterns as expected in the readout system of our experiment. The results obtained in our tests have been used to refine and parametrize our packet level simulation of the complete LHCb readout network. In this paper we report on the...

  6. High peak power Q-switched Er:YAG laser with two polarizers and its ablation performance for hard dental tissues.

    Science.gov (United States)

    Yang, Jingwei; Wang, Li; Wu, Xianyou; Cheng, Tingqing; Jiang, Haihe

    2014-06-30

    An electro-optically Q-switched high-energy Er:YAG laser with two polarizers is proposed. By using two Al(2)O(3) polarizing plates and a LiNbO(3) crystal with Brewster angle, the polarization efficiency is significantly improved. As a result, 226 mJ pulse energy with 62 ns pulse width is achieved at the repetition rate of 3 Hz, the corresponding peak power is 3.6 MW. To our knowledge, such a high peak power has not been reported in literature. With our designed laser, in-vitro teeth were irradiated under Q-switched and free-running modes. Results of a laser ablation experiment on hard dental tissue with the high-peak-power laser demonstrates that the Q-switched Er:YAG laser has higher ablation precision and less thermal damage than the free-running Er:YAG laser.

  7. Coherent scattering of electromagnetic radiation by a polarized particle system

    International Nuclear Information System (INIS)

    Agre, M.Ya.; Rapoport, L.P.

    1996-01-01

    The paper deals with the development of the theory of coherent scattering of electromagnetic waves by a polarized atom or molecular system. Peculiarities of the angular distribution and polarization peculiarities of scattered radiation are discussed

  8. Software development for a switch-based data acquisition system

    Energy Technology Data Exchange (ETDEWEB)

    Booth, A. [Superconducting Super Collider Lab., Dallas, TX (United States); Black, D.; Walsh, D. [Fermi National Accelerator Lab., Batavia, IL (United States)

    1991-12-01

    We report on the software aspects of the development of a switch-based data acquisition system at Fermilab. This paper describes how, with the goal of providing an ``integrated systems engineering`` environment, several powerful software tools were put in place to facilitate extensive exploration of all aspects of the design. These tools include a simulation package, graphics package and an Expert System shell which have been integrated to provide an environment which encourages the close interaction of hardware and software engineers. This paper includes a description of the simulation, user interface, embedded software, remote procedure calls, and diagnostic software which together have enabled us to provide real-time control and monitoring of a working prototype switch-based data acquisition (DAQ) system.

  9. Voltage switching technique for detecting nuclear spin polarization in a quantum dot

    International Nuclear Information System (INIS)

    Takahashi, Ryo; Kono, Kimitoshi; Tarucha, Seigo; Ono, Keiji

    2010-01-01

    We have introduced a source-drain voltage switching technique for studying nuclear spins in a vertical double quantum dot. Switching the source-drain voltage between the spin-blockade state and the zero-bias Coulomb blockade state can tune the energy difference between the spin singlet and triplet, and effectively turn on/off the hyperfine interaction. Since the change in the nuclear spin state affects the source-drain current, nuclear spin properties can only be detected by transport measurement. Using this technique, we have succeeded in measuring the timescale of nuclear spin depolarization. Furthermore, combining this technique and an RF ac magnetic field, we successfully detected continuous-wave NMR signals of 75 As, 69 Ga, and 71 Ga, which are contained in a quantum dot. (author)

  10. Fast helicity switching of x-ray circular polarization at beamline P09 at PETRA III

    International Nuclear Information System (INIS)

    Strempfer, J.; Mardegan, J. R. L.; Francoual, S.; Veiga, L. S. I.; Spitzbart, T.; Zink, H.; Bouchenoire, L.

    2016-01-01

    At the resonant scattering and diffraction beamline P09 at PETRA III/DESY, polarization manipulation in the X-ray energy range 3-13 keV is possible using wave-plates. Recently, fast flipping of circular polarization helicity using the Raspberry Pi controlled FPGA (PiLC) device developed at DESY and dedicated piezo-electric flippers has been commissioned. Functionality of the PiLC for XMCD and first XMCD measurements at the Fe K-and Dy-L 3 absorption edges are presented.

  11. Fast helicity switching of x-ray circular polarization at beamline P09 at PETRA III

    Energy Technology Data Exchange (ETDEWEB)

    Strempfer, J., E-mail: Joerg.Strempfer@desy.de; Mardegan, J. R. L.; Francoual, S.; Veiga, L. S. I.; Spitzbart, T.; Zink, H. [Deutsches Elektronen Synchrotron (DESY), Notkestrasse 85, 22603 Hamburg (Germany); Bouchenoire, L. [XMaS, ESRF, 6 rue Jules Horowitz, BP220, Grenoble 38043 (France); Department of Physics, University of Liverpool, Liverpool, L69 7ZE (United Kingdom)

    2016-07-27

    At the resonant scattering and diffraction beamline P09 at PETRA III/DESY, polarization manipulation in the X-ray energy range 3-13 keV is possible using wave-plates. Recently, fast flipping of circular polarization helicity using the Raspberry Pi controlled FPGA (PiLC) device developed at DESY and dedicated piezo-electric flippers has been commissioned. Functionality of the PiLC for XMCD and first XMCD measurements at the Fe K-and Dy-L{sub 3} absorption edges are presented.

  12. Distributed Consensus of Stochastic Delayed Multi-agent Systems Under Asynchronous Switching.

    Science.gov (United States)

    Wu, Xiaotai; Tang, Yang; Cao, Jinde; Zhang, Wenbing

    2016-08-01

    In this paper, the distributed exponential consensus of stochastic delayed multi-agent systems with nonlinear dynamics is investigated under asynchronous switching. The asynchronous switching considered here is to account for the time of identifying the active modes of multi-agent systems. After receipt of confirmation of mode's switching, the matched controller can be applied, which means that the switching time of the matched controller in each node usually lags behind that of system switching. In order to handle the coexistence of switched signals and stochastic disturbances, a comparison principle of stochastic switched delayed systems is first proved. By means of this extended comparison principle, several easy to verified conditions for the existence of an asynchronously switched distributed controller are derived such that stochastic delayed multi-agent systems with asynchronous switching and nonlinear dynamics can achieve global exponential consensus. Two examples are given to illustrate the effectiveness of the proposed method.

  13. Hacking control systems, switching lights off!

    CERN Document Server

    Computer Security Team

    2013-01-01

    Have you ever heard about “Stuxnet”? “Stuxnet” was a very sophisticated cyber-attack against the Iranian nuclear programme. Like in a spy movie, the attackers infiltrated the uranium enrichment plant at Natanz, arranged for infected USB sticks to be inserted into local PCs, and then the USB viruses did the rest.   Not only did the virus employ four distinct - so far unknown - weaknesses in the Windows operating system, but each weakness could have been sold on the underground market for up to $250,000 each. The virus was targeted to disrupt Iran's uranium production. At first, it scanned the infected PCs for dedicated SCADA (Supervisory Control and Data Acquisition) software from Siemens. Once the virus hit upon that software, it tried to identify any control system components, i.e. so-called PLCs (programmable logic controllers), attached to that PC. If the PLC matched a certain brand (Siemens S7) and configuration, the virus downloaded additi...

  14. A polar system of intercontinental bird migration.

    Science.gov (United States)

    Alerstam, Thomas; Bäckman, Johan; Gudmundsson, Gudmundur A; Hedenström, Anders; Henningsson, Sara S; Karlsson, Håkan; Rosén, Mikael; Strandberg, Roine

    2007-10-22

    Studies of bird migration in the Beringia region of Alaska and eastern Siberia are of special interest for revealing the importance of bird migration between Eurasia and North America, for evaluating orientation principles used by the birds at polar latitudes and for understanding the evolutionary implications of intercontinental migratory connectivity among birds as well as their parasites. We used tracking radar placed onboard the ice-breaker Oden to register bird migratory flights from 30 July to 19 August 2005 and we encountered extensive bird migration in the whole Beringia range from latitude 64 degrees N in Bering Strait up to latitude 75 degrees N far north of Wrangel Island, with eastward flights making up 79% of all track directions. The results from Beringia were used in combination with radar studies from the Arctic Ocean north of Siberia and in the Beaufort Sea to make a reconstruction of a major Siberian-American bird migration system in a wide Arctic sector between longitudes 110 degrees E and 130 degrees W, spanning one-third of the entire circumpolar circle. This system was estimated to involve more than 2 million birds, mainly shorebirds, terns and skuas, flying across the Arctic Ocean at mean altitudes exceeding 1 km (maximum altitudes 3-5 km). Great circle orientation provided a significantly better fit with observed flight directions at 20 different sites and areas than constant geographical compass orientation. The long flights over the sea spanned 40-80 degrees of longitude, corresponding to distances and durations of 1400-2600 km and 26-48 hours, respectively. The birds continued from this eastward migration system over the Arctic Ocean into several different flyway systems at the American continents and the Pacific Ocean. Minimization of distances between tundra breeding sectors and northerly stopover sites, in combination with the Beringia glacial refugium and colonization history, seemed to be important for the evolution of this major

  15. Implications of Sepedi/English code switching for ASR systems

    CSIR Research Space (South Africa)

    Modipa, TI

    2013-12-01

    Full Text Available Code switching (the process of switching from one language to another during a conversation) is a common phenomenon in multilingual environments. Where a minority and dominant language coincide, code switching from the minority language...

  16. Q-Switched Nd: YAG Laser Micro-Machining System

    International Nuclear Information System (INIS)

    Messaoud, S.; Allam, A.; Siserir, F.; Bouceta, Y.; Kerdja, T.; Ouadjaout, D.

    2008-01-01

    In this paper, we present the design of a low cost Q-switched Nd: YAG laser micro-machining system for photo masks fabrication. It consists of: Nd:YAG laser source, beam delivery system, X-Y table, PC, The CCD camera and TV monitor. The synchronization between the laser source and the X-Y table is realised by NI PCI-7342, the two axis MID-7602 and LabVIEW based program. The first step of this work consists of engraving continuous and discontinuous lines on a thin film metal with a 100 μm resolution by using the YG 980 Quantel Q-switched Nd:YAG laser.

  17. Optimal placement of switching equipment in reconfigurable distribution systems

    Directory of Open Access Journals (Sweden)

    Mijailović Vladica

    2011-01-01

    Full Text Available This paper presents a comparative analysis of some measures that can improve the reliability of medium-voltage (MV distribution feeder. Strictly speaking, the impact of certain types of switching equipment installed on the feeder and possibilities of backup supply from the adjacent feeders were analyzed. For each analyzed case, equations for the calculation of System Average Interruption Duration Index and energy not delivered to the customers are given. The effects of certain measures are calculated for one real MV-feeder for radial supply to customers and in cases of possible backup supply to the customers. Installation locations of certain types of switching equipment for the given concept of energy supply are determined according to the criterion of minimum value of System Average Interruption Duration Index and according to the criterion of minimum value of energy not delivered to the customers.

  18. Variable neural adaptive robust control: a switched system approach.

    Science.gov (United States)

    Lian, Jianming; Hu, Jianghai; Żak, Stanislaw H

    2015-05-01

    Variable neural adaptive robust control strategies are proposed for the output tracking control of a class of multiinput multioutput uncertain systems. The controllers incorporate a novel variable-structure radial basis function (RBF) network as the self-organizing approximator for unknown system dynamics. It can determine the network structure online dynamically by adding or removing RBFs according to the tracking performance. The structure variation is systematically considered in the stability analysis of the closed-loop system using a switched system approach with the piecewise quadratic Lyapunov function. The performance of the proposed variable neural adaptive robust controllers is illustrated with simulations.

  19. Switch Reluctance Motor Control Based on Fuzzy Logic System

    Directory of Open Access Journals (Sweden)

    S. V. Aleksandrovsky

    2012-01-01

    Full Text Available Due to its intrinsic simplicity and reliability, the switched reluctance motor (SRM has now become a promising candidate for variable-speed drive applications as an alternative induction motor in various industrial application. However, the SRM has the disadvantage of nonlinear characteristic and control. It is suggested to use controller based on fuzzy logic system. Design of FLS controller and simulation model presented.

  20. Electromechanical magnetization switching

    Energy Technology Data Exchange (ETDEWEB)

    Chudnovsky, Eugene M. [Department of Physics and Astronomy, Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Jaafar, Reem [Department of Mathematics, Engineering and Computer Science, LaGuardia Community College, The City University of New York, 31-10 Thomson Avenue, Long Island City, New York 11101 (United States)

    2015-03-14

    We show that the magnetization of a torsional oscillator that, in addition to the magnetic moment also possesses an electrical polarization, can be switched by the electric field that ignites mechanical oscillations at the frequency comparable to the frequency of the ferromagnetic resonance. The 180° switching arises from the spin-rotation coupling and is not prohibited by the different symmetry of the magnetic moment and the electric field as in the case of a stationary magnet. Analytical equations describing the system have been derived and investigated numerically. Phase diagrams showing the range of parameters required for the switching have been obtained.

  1. Electromechanical magnetization switching

    International Nuclear Information System (INIS)

    Chudnovsky, Eugene M.; Jaafar, Reem

    2015-01-01

    We show that the magnetization of a torsional oscillator that, in addition to the magnetic moment also possesses an electrical polarization, can be switched by the electric field that ignites mechanical oscillations at the frequency comparable to the frequency of the ferromagnetic resonance. The 180° switching arises from the spin-rotation coupling and is not prohibited by the different symmetry of the magnetic moment and the electric field as in the case of a stationary magnet. Analytical equations describing the system have been derived and investigated numerically. Phase diagrams showing the range of parameters required for the switching have been obtained

  2. Polarization enhancement and ferroelectric switching enabled by interacting magnetic structures in DyMnO3 thin films

    KAUST Repository

    Lu, Chengliang

    2013-12-02

    The mutual controls of ferroelectricity and magnetism are stepping towards practical applications proposed for quite a few promising devices in which multiferroic thin films are involved. Although ferroelectricity stemming from specific spiral spin ordering has been reported in highly distorted bulk perovskite manganites, the existence of magnetically induced ferroelectricity in the corresponding thin films remains an unresolved issue, which unfortunately halts this step. In this work, we report magnetically induced electric polarization and its remarkable response to magnetic field (an enhancement of ?800% upon a field of 2 Tesla at 2 K) in DyMnO3 thin films grown on Nb-SrTiO3 substrates. Accompanying with the large polarization enhancement, the ferroelectric coercivity corresponding to the magnetic chirality switching field is significantly increased. A picture based on coupled multicomponent magnetic structures is proposed to understand these features. Moreover, different magnetic anisotropy related to strain-suppressed GdFeO 3-type distortion and Jahn-Teller effect is identified in the films.

  3. Multiuser switched diversity scheduling systems with per-user threshold

    KAUST Repository

    Nam, Haewoon

    2010-05-01

    A multiuser switched diversity scheduling scheme with per-user feedback threshold is proposed and analyzed in this paper. The conventional multiuser switched diversity scheduling scheme uses a single feedback threshold for every user, where the threshold is a function of the average signal-to-noise ratios (SNRs) of the users as well as the number of users involved in the scheduling process. The proposed scheme, however, constructs a sequence of feedback thresholds instead of a single feedback threshold such that each user compares its channel quality with the corresponding feedback threshold in the sequence. Numerical and simulation results show that thanks to the flexibility of threshold selection, where a potentially different threshold can be used for each user, the proposed scheme provides a higher system capacity than that for the conventional scheme. © 2006 IEEE.

  4. Joint Polar Satellite System: The United States next generation civilian polar-orbiting environmental satellite system

    Science.gov (United States)

    Goldberg, Mitchell D.; Kilcoyne, Heather; Cikanek, Harry; Mehta, Ajay

    2013-12-01

    next generation polar-orbiting environmental satellite system, designated as the Joint Polar Satellite System (JPSS), was proposed in February 2010, as part of the President's Fiscal Year 2011 budget request, to be the Civilian successor to the restructured National Polar-Orbiting Operational Environmental Satellite System (NPOESS). Beginning 1 October 2013, the JPSS baseline consists of a suite of five instruments: advanced microwave and infrared sounders critical for short- and medium-range weather forecasting; an advanced visible and infrared imager needed for environmental assessments such as snow/ice cover, droughts, volcanic ash, forest fires and surface temperature; ozone sensor primarily used for global monitoring of ozone and input to weather and climate models; and an Earth radiation budget sensor for monitoring the Earth's energy budget. NASA will fund the Earth radiation budget sensor and the ozone limb sensor for the second JPSS operational satellite--JPSS-2. JPSS is implemented through a partnership between NOAA and the U.S. National Aeronautics and Space Administration (NASA). NOAA is responsible for overall funding; maintaining the high-level requirements; establishing international and interagency partnerships; developing the science and algorithms, and user engagement; NOAA also provides product data distribution and archiving of JPSS data. NASA's role is to serve as acquisition Center of Excellence, providing acquisition of instruments, spacecraft and the multimission ground system, and early mission implementation through turnover to NOAA for operations.

  5. A Fast Channel Switching Method in EPON System for IPTV Service

    Science.gov (United States)

    Nie, Yaling; Yoshiuchi, Hideya

    This paper presents a fast channel switching method in Ethernet Passive Optical Network (EPON) system for IPTV service. Fast channel switching is one of the important features of successful IPTV systems. Users surely prefer IPTV systems with small channel switching time rather than a longer one. Thus a channel switching control module and a channel/permission list in EPON system’s ONU or OLT is designed. When EPON system receives channel switching message from IPTV end user, the channel switching control module will catch the message and search the channel list and permission list maintained in EPON system, then got the matching parameter of EPON for the new channel. The new channel’s data transmission will be enabled by directly updating the optical filter of the ONU that end user connected. By using this method in EPON system, it provides a solution for dealing with channel switching delays in IPTV service.

  6. A wireless implantable switched-capacitor based optogenetic stimulating system.

    Science.gov (United States)

    Lee, Hyung-Min; Kwon, Ki-Yong; Li, Wen; Ghovanloo, Maysam

    2014-01-01

    This paper presents a power-efficient implantable optogenetic interface using a wireless switched-capacitor based stimulating (SCS) system. The SCS efficiently charges storage capacitors directly from an inductive link and periodically discharges them into an array of micro-LEDs, providing high instantaneous power without affecting wireless link and system supply voltage. A custom-designed computer interface in LabVIEW environment wirelessly controls stimulation parameters through the inductive link, and an optrode array enables simultaneous neural recording along with optical stimulation. The 4-channel SCS system prototype has been implemented in a 0.35-μm CMOS process and combined with the optrode array. In vivo experiments involving light-induced local field potentials verified the efficacy of the SCS system. An implantable version of the SCS system with flexible hermetic sealing is under development for chronic experiments.

  7. A Wireless Implantable Switched-Capacitor Based Optogenetic Stimulating System

    Science.gov (United States)

    Lee, Hyung-Min; Kwon, Ki-Yong; Li, Wen

    2015-01-01

    This paper presents a power-efficient implantable optogenetic interface using a wireless switched-capacitor based stimulating (SCS) system. The SCS efficiently charges storage capacitors directly from an inductive link and periodically discharges them into an array of micro-LEDs, providing high instantaneous power without affecting wireless link and system supply voltage. A custom-designed computer interface in LabVIEW environment wirelessly controls stimulation parameters through the inductive link, and an optrode array enables simultaneous neural recording along with optical stimulation. The 4-channel SCS system prototype has been implemented in a 0.35-μm CMOS process and combined with the optrode array. In vivo experiments involving light-induced local field potentials verified the efficacy of the SCS system. An implantable version of the SCS system with flexible hermetic sealing is under development for chronic experiments. PMID:25570099

  8. Process control system using polarizing interferometer

    Science.gov (United States)

    Schultz, T.J.; Kotidis, P.A.; Woodroffe, J.A.; Rostler, P.S.

    1994-02-15

    A system for nondestructively measuring an object and controlling industrial processes in response to the measurement is disclosed in which an impulse laser generates a plurality of sound waves over timed increments in an object. A polarizing interferometer is used to measure surface movement of the object caused by the sound waves and sensed by phase shifts in the signal beam. A photon multiplier senses the phase shift and develops an electrical signal. A signal conditioning arrangement modifies the electrical signals to generate an average signal correlated to the sound waves which in turn is correlated to a physical or metallurgical property of the object, such as temperature, which property may then be used to control the process. External, random vibrations of the workpiece are utilized to develop discernible signals which can be sensed in the interferometer by only one photon multiplier. In addition the interferometer includes an arrangement for optimizing its sensitivity so that movement attributed to various waves can be detected in opaque objects. The interferometer also includes a mechanism for sensing objects with rough surfaces which produce speckle light patterns. Finally the interferometer per se, with the addition of a second photon multiplier is capable of accurately recording beam length distance differences with only one reading. 38 figures.

  9. Process control system using polarizing interferometer

    Science.gov (United States)

    Schultz, Thomas J.; Kotidis, Petros A.; Woodroffe, Jaime A.; Rostler, Peter S.

    1994-01-01

    A system for non-destructively measuring an object and controlling industrial processes in response to the measurement is disclosed in which an impulse laser generates a plurality of sound waves over timed increments in an object. A polarizing interferometer is used to measure surface movement of the object caused by the sound waves and sensed by phase shifts in the signal beam. A photon multiplier senses the phase shift and develops an electrical signal. A signal conditioning arrangement modifies the electrical signals to generate an average signal correlated to the sound waves which in turn is correlated to a physical or metallurgical property of the object, such as temperature, which property may then be used to control the process. External, random vibrations of the workpiece are utilized to develop discernible signals which can be sensed in the interferometer by only one photon multiplier. In addition the interferometer includes an arrangement for optimizing its sensitivity so that movement attributed to various waves can be detected in opaque objects. The interferometer also includes a mechanism for sensing objects with rough surfaces which produce speckle light patterns. Finally the interferometer per se, with the addition of a second photon multiplier is capable of accurately recording beam length distance differences with only one reading.

  10. Low-cost fabrication and polar-dependent switching uniformity of memory devices using alumina interfacial layer and Ag nanoparticle monolayer

    Directory of Open Access Journals (Sweden)

    Peng Xia

    2017-11-01

    Full Text Available A facile and low-cost process was developed for fabricating write-once-read-many-times (WORM Cu/Ag NPs/Alumina/Al memory devices, where the alumina passivation layer formed naturally in air at room temperature, whereas the Ag nanoparticle monolayer was in situ prepared through thermal annealing of a 4.5 nm Ag film in air at 150°C. The devices exhibit irreversible transition from initial high resistance (OFF state to low resistance (ON state, with ON/OFF ratio of 107, indicating the introduction of Ag nanoparticle monolayer greatly improves ON/OFF ratio by four orders of magnitude. The uniformity of threshold voltages exhibits a polar-dependent behavior, and a narrow range of threshold voltages of 0.40 V among individual devices was achieved upon the forward voltage. The memory device can be regarded as two switching units connected in series. The uniform alumina interfacial layer and the non-uniform distribution of local electric fields originated from Ag nanoparticles might be responsible for excellent switching uniformity. Since silver ions in active layer can act as fast ion conductor, a plausible mechanism relating to the formation of filaments sequentially among the two switching units connected in series is suggested for the polar-dependent switching behavior. Furthermore, we demonstrate both alumina layer and Ag NPs monolayer play essential roles in improving switching parameters based on comparative experiments.

  11. Low-cost fabrication and polar-dependent switching uniformity of memory devices using alumina interfacial layer and Ag nanoparticle monolayer

    Science.gov (United States)

    Xia, Peng; Li, Luman; Wang, Pengfei; Gan, Ying; Xu, Wei

    2017-11-01

    A facile and low-cost process was developed for fabricating write-once-read-many-times (WORM) Cu/Ag NPs/Alumina/Al memory devices, where the alumina passivation layer formed naturally in air at room temperature, whereas the Ag nanoparticle monolayer was in situ prepared through thermal annealing of a 4.5 nm Ag film in air at 150°C. The devices exhibit irreversible transition from initial high resistance (OFF) state to low resistance (ON) state, with ON/OFF ratio of 107, indicating the introduction of Ag nanoparticle monolayer greatly improves ON/OFF ratio by four orders of magnitude. The uniformity of threshold voltages exhibits a polar-dependent behavior, and a narrow range of threshold voltages of 0.40 V among individual devices was achieved upon the forward voltage. The memory device can be regarded as two switching units connected in series. The uniform alumina interfacial layer and the non-uniform distribution of local electric fields originated from Ag nanoparticles might be responsible for excellent switching uniformity. Since silver ions in active layer can act as fast ion conductor, a plausible mechanism relating to the formation of filaments sequentially among the two switching units connected in series is suggested for the polar-dependent switching behavior. Furthermore, we demonstrate both alumina layer and Ag NPs monolayer play essential roles in improving switching parameters based on comparative experiments.

  12. Floating electrode microelectromechanical system capacitive switches: A different actuation mechanism

    Science.gov (United States)

    Papaioannou, G.; Giacomozzi, F.; Papandreou, E.; Margesin, B.

    2011-08-01

    The paper investigates the actuation mechanism in floating electrode microelectromechanical system capacitive switches. It is demonstrated that in the pull-in state, the device operation turns from voltage to current controlled actuation. The current arises from Poole-Frenkel mechanism in the dielectric film and Fowler-Nordheim in the bridge-floating electrode air gap. The pull-out voltage seems to arise from the abrupt decrease of Fowler-Nordheim electric field intensity. This mechanism seems to be responsible for the very small difference with respect to the pull-in voltage.

  13. Practice and Preparation Time Facilitate System-Switching in Perceptual Categorization

    Directory of Open Access Journals (Sweden)

    Sébastien Hélie

    2017-11-01

    Full Text Available Mounting evidence suggests that category learning is achieved using different psychological and biological systems. While existing multiple-system theories and models of categorization may disagree about the number or nature of the different systems, all assume that people can switch between systems seamlessly. However, little empirical data has been collected to test this assumption, and recent available data suggest that system-switching is difficult. The main goal of this article is to identify factors influencing the proportion of participants who successfully learn to switch between procedural and declarative systems on a trial-by-trial basis. Specifically, we tested the effects of preparation time and practice, two factors that have been useful in task-switching, in a system-switching experiment. The results suggest that practice and preparation time can be beneficial to system-switching (as calculated by a higher proportion of switchers and lower switch costs, especially when they are jointly present. However, this improved system-switching comes at the cost of a larger button-switch interference when changing the location of the response buttons. The article concludes with a discussion of the implications of these findings for empirical research on system-switching and theoretical work on multiple-systems of category learning.

  14. VME Switch for CERN's PS Analog Video System

    CERN Document Server

    Acebes, I; Heinze, W; Lewis, J; Serrano, J

    2003-01-01

    Analog video signal switching is used in CERN's Proton Synchrotron (PS) complex to route the video signals coming from Beam Diagnostics systems to the Meyrin Control Room (MCR). Traditionally, this has been done with custom electromechanical relay-based cards controlled serially via CAMAC crates. In order to improve the robustness and maintainability of the system, while keeping it analog to preserve the low latency, a VME card based on Analog Devices' AD8116 analog matrix chip has been developed. Video signals go into the front panel and exit the switch through the P2 connector of the VME backplane. The module is a 16 input, 32 output matrix. Larger matrices can be built using more modules and bussing their outputs together, thanks to the high impedance feature of the AD8116. Another VME module takes the selected signals from the P2 connector and performs automatic gain to send them at nominal output level through its front panel. This paper discusses both designs and presents experimental test results.

  15. Filippov systems and quasi-synchronization control for switched networks.

    Science.gov (United States)

    Liu, Xiaoyang; Cao, Jinde; Yu, Wenwu

    2012-09-01

    This paper is concerned with the quasi-synchronization issue of linearly coupled networks with discontinuous nonlinear functions in each isolated node. Under the framework of Filippov systems, the existence and boundedness of solutions for such complex networks can be guaranteed by the matrix measure approach. A design method is presented for the synchronization controllers of coupled networks with non-identical discontinuous systems. Moreover, a sufficient condition is derived to ensure the quasi-synchronization of switched coupled complex networks with discontinuous isolated nodes, which could be controlled by some designed linear controllers. The obtained results extend the previous work on the synchronization issue of coupled complex networks with Lipschitz continuous conditions. Numerical simulations on the coupled chaotic systems are given to demonstrate the effectiveness of the theoretical results.

  16. Orthogonal polynomials describing polarization aberration for rotationally symmetric optical systems.

    Science.gov (United States)

    Xu, Xiangru; Huang, Wei; Xu, Mingfei

    2015-10-19

    Optical lithography has approached a regime of high numerical aperture and wide field, where the impact of polarization aberration on imaging quality turns to be serious. Most of the existing studies focused on the distribution rule of polarization aberration on the pupil, and little attention had been paid to the field. In this paper, a new orthonormal set of polynomials is established to describe the polarization aberration of rotationally symmetric optical systems. The polynomials can simultaneously reveal the distribution rules of polarization aberration on the exit pupil and the field. Two examples are given to verify the polynomials.

  17. Huge capacity optical packet switching and buffering.

    Science.gov (United States)

    Shinada, Satoshi; Furukawa, Hideaki; Wada, Naoya

    2011-12-12

    We demonstrate 2.56 Tbit/s/port dual-polarization DWDM/DQPSK variable-length optical packet (20 Gbit/s × 64 wavelengths × 2 polarizations) switching and buffering by using a 2×2 optical packet switch (OPS) system. The optical data plane of the OPS system was constructed of multi-connected electro-optical switches and fiber delay lines. The accumulated polarization dependent loss of each optical path in the data plane was less than 5 dB. This low-polarization-dependence OPS system enabled us to handle DWDM/DQPSK optical packets (1.28 Tbit/s/port) with time-varying polarization after transmission through 100 km fiber in the field. © 2011 Optical Society of America

  18. A polar system of intercontinental bird migration

    OpenAIRE

    Alerstam, Thomas; Bäckman, Johan; Gudmundsson, Gudmundur A; Hedenström, Anders; Henningsson, Sara S; Karlsson, Håkan; Rosén, Mikael; Strandberg, Roine

    2007-01-01

    Studies of bird migration in the Beringia region of Alaska and eastern Siberia are of special interest for revealing the importance of bird migration between Eurasia and North America, for evaluating orientation principles used by the birds at polar latitudes and for understanding the evolutionary implications of intercontinental migratory connectivity among birds as well as their parasites. We used tracking radar placed onboard the ice-breaker Oden to register bird migratory flights from 30 ...

  19. Joint Polar Satellite System Common Ground System Overview

    Science.gov (United States)

    Jamilkowski, M. L.; Miller, S. W.; Grant, K. D.

    2012-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). JPSS will contribute the afternoon orbit component and ground processing system of the restructured National Polar-orbiting Operational Environmental Satellite System (NPOESS). As such, JPSS replaces the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA and the ground processing component of both Polar-orbiting Operational Environmental Satellites and the Defense Meteorological Satellite Program (DMSP) replacement, previously known as the Defense Weather Satellite System (DWSS), managed by the Department of Defense (DoD). The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS), and consists of a Command, Control, and Communications Segment (C3S) and an Interface Data Processing Segment (IDPS). Both segments are developed by Raytheon Intelligence and Information Systems (IIS). The C3S currently flies the Suomi National Polar Partnership (Suomi NPP) satellite and transfers mission data from Suomi NPP and between the ground facilities. The IDPS processes Suomi NPP satellite data to provide Environmental Data Records (EDRs) to NOAA and DoD processing centers operated by the United States government. When the JPSS-1 satellite is launched in early 2017, the responsibilities of the C3S and the IDPS will be expanded to support both Suomi NPP and JPSS-1. The JPSS CGS currently provides data processing for Suomi NPP, generating multiple terabytes per day across over two dozen environmental data products; that workload will be multiplied by two when the JPSS-1 satellite is

  20. Control of systems with costs related to switching: applications to air-condition systems

    DEFF Research Database (Denmark)

    Thybo (Deng), Honglian; Larsen, Lars Finn Sloth; Stoustrup, Jakob

    2009-01-01

    The objective of this paper is to investigate a low complexity method for controlling systems with binary inputs that have costs related to switching. The control objective for this type of systems is often a trade off between the deviation from the reference and the number of switches (weariness...... energy efficiency etc.). For such systems a steady state solution might never be attained, but rather the optimal behavior might be constituted by a limit cycle. In this paper we consider the problem of finding and controlling the system towards an optimal limit cycle. A low complexity approach giving...

  1. The Formation of Self-Organized Domain Structures at Non-Polar Cuts of Lithium Niobate as a Result of Local Switching by an SPM Tip

    Directory of Open Access Journals (Sweden)

    Anton Turygin

    2017-09-01

    Full Text Available We have studied experimentally the interaction of isolated needle-like domains created in an array via local switching using a biased scanning probe microscope (SPM tip and visualized via piezoelectric force microscopy (PFM at the non-polar cuts of MgO-doped lithium niobate (MgOLN crystals. It has been found that the domain interaction leads to the intermittent quasiperiodic and chaotic behavior of the domain length in the array in a manner similar to that of polar cuts, but with greater spacing between the points of bias application and voltage amplitudes. It has also been found that the polarization reversal at the non-polar cuts and domain interaction significantly depend on humidity. The spatial distribution of the surface potential measured by Kelvin probe force microscopy in the vicinity of the charged domain walls revealed the decrease of the domain length as a result of the partial backswitching after pulse termination. The phase diagram of switching behavior as a function of tip voltage and spacing between the points of bias application has been plotted. The obtained results provide new insight into the problem of the domain interaction during forward growth and can provide a basis for useful application in nanodomain engineering and development of non-linear optical frequency converters, data storage, and computing devices.

  2. Method for detecting an open-switch fault in a grid-connected NPC inverter system

    DEFF Research Database (Denmark)

    Choi, Ui-Min; Jeong, Hae-Gwang; Lee, Kyo-Beum

    2012-01-01

    This paper proposes a fault-detection method for an open-switch fault in the switches of grid-connected neutral-point-clamped inverter systems. The proposed method can not only detect the fault condition but also identify the location of the faulty switch. In the proposed method, which is designed...... by incorporating a simple switching control in the conventional method, the fault condition is detected on the basis of the radius of the Concordia current pattern, and the location of the faulty switch can be identified. By using the proposed method, it is possible to detect the open-switch fault and identify...... the faulty switch within two fundamental periods, without using additional sensors or performing complex calculations. Simulations and experiments are carried out to confirm the reliability of the proposed fault-detection method....

  3. Photonics in switching: Architectures, systems and enabling technologies

    DEFF Research Database (Denmark)

    Raffaelli, C.; Vlachos, K.; Andriolli, N.

    2008-01-01

    This paper describes recent research activities and results in the area of photonic switching carried out within the Virtual Department on Switching (VDS) of the European e-Photon/ONe Network of Excellence. Contributions from outstanding European research groups in this field are collected to offer...

  4. On the transient dynamics of piezoelectric-based, state-switched systems

    Science.gov (United States)

    Lopp, Garrett K.; Kelley, Christopher R.; Kauffman, Jeffrey L.

    2018-01-01

    This letter reports on the induced mechanical transients for piezoelectric-based, state-switching approaches utilizing both experimental tests and a numerical model that more accurately captures the dynamics associated with a switch between stiffness states. Currently, switching models instantaneously dissipate the stored piezoelectric voltage, resulting in a discrete change in effective stiffness states and a discontinuity in the system dynamics during the switching event. The proposed model allows for a rapid but continuous voltage dissipation and the corresponding variation between stiffness states, as one sees in physical implementations. This rapid variation in system stiffness when switching at a point of non-zero strain leads to high-frequency, large-amplitude transients in the system acceleration response. Utilizing a fundamental piezoelectric bimorph, a comparison between the numerical and experimental results reveals that these mechanical transients are much stronger than originally anticipated and masked by measurement hardware limitations, thus highlighting the significance of an appropriate system model governing the switch dynamics. Such a model enables designers to analyze systems that incorporate piezoelectric-based state switching with greater accuracy to ensure that these transients do not degrade the intended performance. Finally, if the switching does create unacceptable transients, controlling the duration of voltage dissipation enables control over the frequency content and peak amplitudes associated with the switch-induced acceleration transients.

  5. Polarization sensitive optical frequency domain imaging system for endobronchial imaging.

    Science.gov (United States)

    Li, Jianan; Feroldi, Fabio; de Lange, Joop; Daniels, Johannes M A; Grünberg, Katrien; de Boer, Johannes F

    2015-02-09

    A polarization sensitive endoscopic optical frequency domain imaging (PS-OFDI) system with a motorized distal scanning catheter is demonstrated. It employs a passive polarization delay unit to multiplex two orthogonal probing polarization states in depth, and a polarization diverse detection unit to detect interference signal in two orthogonal polarization channels. Per depth location four electro-magnetic field components are measured that can be represented in a complex 2x2 field matrix. A Jones matrix of the sample is derived and the sample birefringence is extracted by eigenvalue decomposition. The condition of balanced detection and the polarization mode dispersion are quantified. A complex field averaging method based on the alignment of randomly pointing field phasors is developed to reduce speckle noise. The variation of the polarization states incident on the tissue due to the circular scanning and catheter sheath birefringence is investigated. With this system we demonstrated imaging of ex vivo chicken muscle, in vivo pig lung and ex vivo human lung specimens.

  6. Joint Polar Satellite System: the United States New Generation Civilian Polar Orbiting Environmental Satellite System

    Science.gov (United States)

    Mandt, G.

    2017-12-01

    The Joint Polar Satellite System (JPSS) is the Nation's advanced series of polar-orbiting environmental satellites. JPSS represents significant technological and scientific advancements in observations used for severe weather prediction and environmental monitoring. The Suomi National Polar-orbiting Partnership (S-NPP) is providing state-of-the art atmospheric, oceanographic, and environmental data, as the first of the JPSS satellites while the second in the series, J-1, is scheduled to launch in October 2017. The JPSS baseline consists of a suite of four instruments: an advanced microwave and infrared sounders which are critical for weather forecasting; a leading-edge visible and infrared imager critical to data sparse areas such as Alaska and needed for environmental assessments such as snow/ice cover, droughts, volcanic ash, forest fires and surface temperature; and an ozone sensor primarily used for global monitoring of ozone and input to weather and climate models. The same suite of instruments that are on JPSS-1 will be on JPSS-2, 3 and 4. The JPSS-2 instruments are well into their assembly and test phases and are scheduled to be completed in 2018. The JPSS-2 spacecraft critical design review (CDR) is scheduled for 2Q 2018 with the launch in 2021. The sensors for the JPSS-3 and 4 spacecraft have been approved to enter into their acquisition phases. JPSS partnership with the US National Aeronautics and Space Agency (NASA) continues to provide a strong foundation for the program's success. JPSS also continues to maintain its important international relationships with European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) and the Japan Aerospace Exploration Agency (JAXA). JPSS works closely with its user community through the Proving Ground and Risk Reduction (PGRR) Program to identify opportunities to maximize the operational application of current JPSS capabilities. The PGRR Program also helps identify and evaluate the use of JPSS

  7. Optimal Coordination of Automatic Line Switches for Distribution Systems

    Directory of Open Access Journals (Sweden)

    Jyh-Cherng Gu

    2012-04-01

    Full Text Available For the Taiwan Power Company (Taipower, the margins of coordination times between the lateral circuit breakers (LCB of underground 4-way automatic line switches and the protection equipment of high voltage customers are often too small. This could lead to sympathy tripping by the feeder circuit breaker (FCB of the distribution feeder and create difficulties in protection coordination between upstream and downstream protection equipment, identification of faults, and restoration operations. In order to solve the problem, it is necessary to reexamine the protection coordination between LCBs and high voltage customers’ protection equipment, and between LCBs and FCBs, in order to bring forth new proposals for settings and operations. This paper applies linear programming to optimize the protection coordination of protection devices, and proposes new time current curves (TCCs for the overcurrent (CO and low-energy overcurrent (LCO relays used in normally open distribution systems by performing simulations in the Electrical Transient Analyzer Program (ETAP environment. The simulation results show that the new TCCs solve the coordination problems among high voltage customer, lateral, feeder, bus-interconnection, and distribution transformer. The new proposals also satisfy the requirements of Taipower on protection coordination of the distribution feeder automation system (DFAS. Finally, the authors believe that the system configuration, operation experience, and relevant criteria mentioned in this paper may serve as valuable references for other companies or utilities when building DFAS of their own.

  8. Smooth Optimal Control for a Class of Switched Systems Based on Fuzzy Theory and PSO

    Science.gov (United States)

    Atashpaz-Gargari, Esmaeil

    2017-10-01

    This paper proposes an approach to smooth optimal control design of two-point boundary value problem of switched systems with fuzzy operating regions. The switched system is modeled via a T-S fuzzy system, and then the fuzzy inference method of T-S fuzzy system is used to transform the switched system to a nonlinear system. For this nonlinear system, an optimal controller is designed. The control signal is a fuzzy control with weighted average defuzzifier. The fuzzy sets are used to partition the time space and a Particle Swarm Optimization (PSO) algorithm is proposed to optimize the weights. Simulations results demonstrate the applicability and effectiveness of the proposed method.

  9. Robust switched PI controller design for a simple hysteretic mechanical system

    NARCIS (Netherlands)

    Jayawardhana, B.

    2010-01-01

    In this paper, we consider the design of a robust switched PI controller for a simple hysteretic mechanical system. The design procedure ensures that the closed-loop system remains inputto-state stable under arbitrary switching signals among a family of PI controllers, it has an exponential

  10. Single-Mask Fabrication of Temperature Triggered MEMS Switch for Cooling Control in SSL System

    NARCIS (Netherlands)

    Wei, J.; Ye, H.; Van Zeijl, H.W.; Sarro, P.M.; Zhang, G.Q.

    2012-01-01

    A micro-electro-mechanical-system (MEMS) based, temperature triggered, switch is developed as a cost-effective solution for smart cooling control of solid-state-lighting systems. The switch (1.0x0.4 mm2) is embedded in a silicon substrate and fabricated with a single-mask 3D micro-machining process.

  11. A Novel Attitude Determination System Aided by Polarization Sensor

    Directory of Open Access Journals (Sweden)

    Wei Zhi

    2018-01-01

    Full Text Available This paper aims to develop a novel attitude determination system aided by polarization sensor. An improved heading angle function is derived using the perpendicular relationship between directions of E-vector of linearly polarized light and solar vector in the atmospheric polarization distribution model. The Extended Kalman filter (EKF with quaternion differential equation as a dynamic model is applied to fuse the data from sensors. The covariance functions of filter process and measurement noises are deduced in detail. The indoor and outdoor tests are conducted to verify the validity and feasibility of proposed attitude determination system. The test results showed that polarization sensor is not affected by magnetic field, thus the proposed system can work properly in environments containing the magnetic interference. The results also showed that proposed system has higher measurement accuracy than common attitude determination system and can provide precise parameters for Unmanned Aerial Vehicle (UAV flight control. The main contribution of this paper is implementation of the EKF for incorporating the self-developed polarization sensor into the conventional attitude determination system. The real-world experiment with the quad-rotor proved that proposed system can work in a magnetic interference environment and provide sufficient accuracy in attitude determination for autonomous navigation of vehicle.

  12. Switching theory-based steganographic system for JPEG images

    Science.gov (United States)

    Cherukuri, Ravindranath C.; Agaian, Sos S.

    2007-04-01

    Cellular communications constitute a significant portion of the global telecommunications market. Therefore, the need for secured communication over a mobile platform has increased exponentially. Steganography is an art of hiding critical data into an innocuous signal, which provide answers to the above needs. The JPEG is one of commonly used format for storing and transmitting images on the web. In addition, the pictures captured using mobile cameras are in mostly in JPEG format. In this article, we introduce a switching theory based steganographic system for JPEG images which is applicable for mobile and computer platforms. The proposed algorithm uses the fact that energy distribution among the quantized AC coefficients varies from block to block and coefficient to coefficient. Existing approaches are effective with a part of these coefficients but when employed over all the coefficients they show there ineffectiveness. Therefore, we propose an approach that works each set of AC coefficients with different frame work thus enhancing the performance of the approach. The proposed system offers a high capacity and embedding efficiency simultaneously withstanding to simple statistical attacks. In addition, the embedded information could be retrieved without prior knowledge of the cover image. Based on simulation results, the proposed method demonstrates an improved embedding capacity over existing algorithms while maintaining a high embedding efficiency and preserving the statistics of the JPEG image after hiding information.

  13. Exponential Stability of Time-Switched Two-Subsystem Nonlinear Systems with Application to Intermittent Control

    Directory of Open Access Journals (Sweden)

    Huang Tingwen

    2009-01-01

    Full Text Available This paper studies the exponential stability of a class of periodically time-switched nonlinear systems. Three cases of such systems which are composed, respectively, of a pair of unstable subsystems, of both stable and unstable subsystems, and of a pair of stable systems, are considered. For the first case, the proposed result shows that there exists periodically switching rule guaranteeing the exponential stability of the whole system with (sufficient small switching period if there is a Hurwitz linear convex combination of two uncertain linear systems derived from two subsystems by certain linearization. For the second case, we present two general switching criteria by means of multiple and single Lyapunov function, respectively. We also investigate the stability issue of the third case, and the switching criteria of exponential stability are proposed. The present results for the second case are further applied to the periodically intermittent control. Several numerical examples are also given to show the effectiveness of theoretical results.

  14. Switched periodic systems in discrete time: stability and input-output norms

    Science.gov (United States)

    Bolzern, Paolo; Colaneri, Patrizio

    2013-07-01

    This paper deals with the analysis of stability and the characterisation of input-output norms for discrete-time periodic switched linear systems. Such systems consist of a network of time-periodic linear subsystems sharing the same state vector and an exogenous switching signal that triggers the jumps between the subsystems. The overall system exhibits a complex dynamic behaviour due to the interplay between the time periodicity of the subsystem parameters and the switching signal. Both arbitrary switching signals and signals satisfying a dwell-time constraint are considered. Linear matrix inequality conditions for stability and guaranteed H2 and H∞ performances are provided. The results heavily rely on the merge of the theory of linear periodic systems and recent developments on switched linear time-invariant systems.

  15. Novel calibration system with sparse wires for CMB polarization receivers

    Energy Technology Data Exchange (ETDEWEB)

    Tajima, O.; /KEK, Tsukuba /Chicago U., KICP; Nguyen, H.; /Fermilab; Bischoff, C.; /Chicago U., KICP /Harvard-Smithsonian Ctr. Astrophys.; Brizius, A.; Buder, I.; Kusaka, A. /Chicago U., KICP

    2011-07-01

    B-modes in the cosmic microwave background (CMB) polarization is a smoking gun signature of the inflationary universe. To achieve better sensitivity to this faint signal, CMB polarization experiments aim to maximize the number of detector elements, resulting in a large focal plane receiver. Detector calibration of the polarization response becomes essential. It is extremely useful to be able to calibrate 'simultaneously' all detectors on the large focal plane. We developed a novel calibration system that rotates a large 'sparse' grid of metal wires, in front of and fully covering the field of view of the focal plane receiver. Polarized radiation is created via the reflection of ambient temperature from the wire surface. Since the detector has a finite beam size, the observed signal is smeared according to the beam property. The resulting smeared polarized radiation has a reasonable intensity (a few Kelvin or less) compared to the sky temperature ({approx}10 K observing condition). The system played a successful role for receiver calibration of QUIET, a CMB polarization experiment located in the Atacama desert in Chile. The successful performance revealed that this system is applicable to other experiments based on different technologies, e.g. TES bolometers.

  16. Switched diversity strategies for dual-hop relaying systems

    KAUST Repository

    Gaaloul, Fakhreddine

    2011-04-29

    This paper investigates the effect of different switched diversity configurations on the implementation complexity and achieved performance of dual-hop amplify-and-forward (AF) relaying networks. A low-complexity model of the relay station is adopted, wherein single-input single-output antenna configuration is employed. Each of the transmitter and the receiver however employs multiple antennas to improve the overall link performance. Single-phase and two-phase based receive switching strategies are investigated assuming optimum first hop signal-to-noise ratio (SNR). Moreover, the simple scheme in which the switched diversity is applied independently over the two hops is studied using tight upper bounds. Thorough performance comparisons and switching thresholds optimization for the aforementioned strategies are presented. Simulation results are also provided to validate the mathematical development and to verify the numerical computations.

  17. Open-switch fault detection method of an NPC converter for wind turbine systems

    DEFF Research Database (Denmark)

    Lee, June-Seok; Lee, Kyo-Beum; Blaabjerg, Frede

    2013-01-01

    In wind turbine generation (WTG) systems, the neutral-point-clamped (NPC) topology is widely used as the part of a back-to-back converter since the three-level NPC topology has more advantages than the conventional two-level inverter especially for high power. There are twelve switches in the NPC...... topology and an open-switch fault of the NPC converter leads to current distortion and the torque ripple in the system. Furthermore, WTG systems can breakdown in the worst case by this ripple. To improve the reliability of WTG systems, an open-switch fault detection method is required. The open......-switch detection method of the NPC converter is different from that of the NPC inverter due to the different current paths of the NPC converter. This paper proposes the open-switch fault detection method of the NPC converter connected the permanent-magnet synchronous generator (PMSG). Moreover, the open...

  18. Does sleep quality affect involuntary attention switching system?

    Science.gov (United States)

    Salmi, Juha; Huotilainen, Minna; Pakarinen, Satu; Siren, Teo; Alho, Kimmo; Aronen, Eeva T

    2005-12-30

    We studied the relationship between sleep quality and quantity and subsequently recorded automatically evoked event-related potential (ERP) responses. In previous studies decrement of attentional processing has been associated with changes in sleep. Sleep is shown to associate also with ERPs elicited by unattended sound stream, however, there is no consensus on these effects. A recent study suggested that the early anterior P3a to novel stimuli in attended stream is attenuated and the late parietal P3a is strengthened by total sleep deprivation. We carried out 72-h consecutive actigraphy measurements in a naturalistic setting to collect information about variation in sleep duration, sleep onset latency, sleep efficiency, and percentage of sleep. MMN and P3a deflections to infrequent changes in sound duration and pitch in unattended sound stream were obtained in a separate recording session from the same subjects when they were awake. No significant correlations were found between sleep and MMN parameters, indicating that MMN is resistant to normal variation in sleep. However, P3a to both pitch and duration changes correlated positively with sleep onset latency, and P3a to duration changes correlated negatively with sleep efficiency and percentage of sleep. The correlation was higher in the posterior scalp areas. Our results suggest that the involuntary attention switching system, reflected by the P3a is sensitized as a function of decreased sleep quality.

  19. What makes the lac-pathway switch: identifying the fluctuations that trigger phenotype switching in gene regulatory systems.

    Science.gov (United States)

    Bhogale, Prasanna M; Sorg, Robin A; Veening, Jan-Willem; Berg, Johannes

    2014-10-01

    Multistable gene regulatory systems sustain different levels of gene expression under identical external conditions. Such multistability is used to encode phenotypic states in processes including nutrient uptake and persistence in bacteria, fate selection in viral infection, cell-cycle control and development. Stochastic switching between different phenotypes can occur as the result of random fluctuations in molecular copy numbers of mRNA and proteins arising in transcription, translation, transport and binding. However, which component of a pathway triggers such a transition is generally not known. By linking single-cell experiments on the lactose-uptake pathway in E. coli to molecular simulations, we devise a general method to pinpoint the particular fluctuation driving phenotype switching and apply this method to the transition between the uninduced and induced states of the lac-genes. We find that the transition to the induced state is not caused only by the single event of lac-repressor unbinding, but depends crucially on the time period over which the repressor remains unbound from the lac-operon. We confirm this notion in strains with a high expression level of the lac-repressor (leading to shorter periods over which the lac-operon remains unbound), which show a reduced switching rate. Our techniques apply to multistable gene regulatory systems in general and allow to identify the molecular mechanisms behind stochastic transitions in gene regulatory circuits. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

  20. Global finite-time stabilisation of a class of switched nonlinear systems

    Science.gov (United States)

    Liang, Ying-Jiu; Ma, Ruicheng; Wang, Min; Fu, Jun

    2015-12-01

    This paper is concerned with the global finite-time stabilisation problem for a class of switched nonlinear systems under arbitrary switchings. All subsystems of the studied switched system under consideration are in lower triangular form. Based on the adding one power integrator technique, both a class of non-Lipschitz continuous state feedback controllers and a common Lyapunov function are simultaneously constructed such that the closed-loop switched system is global finite-time stable under arbitrary switchings. In the controller design process, a common coordinate transformation of all subsystems is exploited to avoid using individual coordinate transformations for subsystems. Finally, two examples are given to show the effectiveness of the proposed method.

  1. Solid-state active switch matrix for high energy, moderate power battery systems

    Science.gov (United States)

    Deal, Larry; Paris, Peter; Ye, Changqing

    2016-06-07

    A battery management system employs electronic switches and capacitors. No traditional cell-balancing resistors are used. The BMS electronically switches individual cells into and out of a module of cells in order to use the maximum amount of energy available in each cell and to completely charge and discharge each cell without overcharging or under-discharging.

  2. Polarity-Free Resistive Switching Characteristics of CuxO Films for Non-volatile Memory Applications

    International Nuclear Information System (INIS)

    Hang-Bing, Lv; Peng, Zhou; Xiu-Feng, Fu; Ming, Yin; Ya-Li, Song; Li, Tang; Ting-Ao, Tang; Yin-Yin, Lin

    2008-01-01

    Resistive switching characteristics of Cu x O films grown by plasma oxidation process at room temperature are investigated. Both bipolar and unipolar stable resistive switching behaviours are observed and confirmed by repeated current–voltage measurements. It is found that the RESET current is dependent on SET compliance current. The mechanism behind this new phenomenon can be understood in terms of conductive filaments formation/rupture with the contribution of Joule heating

  3. Polarization-independent, differential-phase-shift, quantum-key distribution system using upconversion detectors.

    Science.gov (United States)

    Iwai, Yuki; Honjo, Toshimori; Inoue, Kyo; Kamada, Hidehiko; Nishida, Yoshiki; Tadanaga, Osamu; Asobe, Masaki

    2009-05-15

    We propose and demonstrate a polarization-independent, differential-phase-shift, quantum-key distribution system with upconversion detectors. Even though the detectors have polarization dependency, use of alternative polarization modulation and a two-bit delay interferometer achieves polarization-insensitive operation. In an experiment, sifted key bits were polarization-independently generated over 50 km fiber.

  4. Spectrally efficient switched transmit diversity for spectrum sharing systems

    KAUST Repository

    Bouida, Zied

    2011-09-01

    Under the scenario of an underlay cognitive radio network, we propose in this paper an adaptive scheme using switched transmit diversity and adaptive modulation in order to increase the spectral efficiency of the secondary link. The proposed bandwidth efficient scheme (BES) uses the scan and wait (SWC) combining technique where a transmission occurs only when a branch with an acceptable performance is found, otherwise data is buffered. In our scheme, the modulation constellation size and the used transmit branch are determined to achieve the highest spectral efficiency given the fading channel conditions, the required error rate performance, and a peak interference constraint to the primary receiver. Selected numerical examples show that the BES scheme increases the capacity of the secondary link when compared to an existing switching efficient scheme (SES). This spectral efficiency comes at the expense of an increased average number of switched branches and thus an increased average delay. © 2011 IEEE.

  5. Finite-Time Stabilization of Uncertain Switched Positive Linear Systems with Time-Varying Delays

    Directory of Open Access Journals (Sweden)

    Tianjian Yu

    2015-01-01

    Full Text Available This paper is concerned with finite-time stabilization (FTS analysis for a class of uncertain switched positive linear systems with time-varying delays. First, a new definition of finite-time boundedness (FTB is introduced for switched positive system. This definition can simplify FTS analysis. Taking interval and polytopic uncertainties into account, a robust state feedback controller is built such that the switched positive linear system is finite-time bounded. Finally, an example is employed to illustrate the validities of obtained results.

  6. Observed-Based Adaptive Fuzzy Tracking Control for Switched Nonlinear Systems With Dead-Zone.

    Science.gov (United States)

    Tong, Shaocheng; Sui, Shuai; Li, Yongming

    2015-12-01

    In this paper, the problem of adaptive fuzzy output-feedback control is investigated for a class of uncertain switched nonlinear systems in strict-feedback form. The considered switched systems contain unknown nonlinearities, dead-zone, and immeasurable states. Fuzzy logic systems are utilized to approximate the unknown nonlinear functions, a switched fuzzy state observer is designed and thus the immeasurable states are obtained by it. By applying the adaptive backstepping design principle and the average dwell time method, an adaptive fuzzy output-feedback tracking control approach is developed. It is proved that the proposed control approach can guarantee that all the variables in the closed-loop system are bounded under a class of switching signals with average dwell time, and also that the system output can track a given reference signal as closely as possible. The simulation results are given to check the effectiveness of the proposed approach.

  7. Opioids Switching with Transdermal Systems in Chronic Cancer Pain

    Directory of Open Access Journals (Sweden)

    Barbarisi M

    2009-05-01

    Full Text Available Abstract Background Due to tolerance development and adverse side effects, chronic pain patients frequently need to be switched to alternative opioid therapy Objective To assess the efficacy and tolerability of an alternative transdermally applied (TDS opioid in patients with chronic cancer pain receiving insufficient analgesia using their present treatment. Methods A total of 32 patients received alternative opioid therapy, 16 were switched from buprenorphine to fentanyl and 16 were switched from fentanyl to buprenorphine. The dosage used was 50% of that indicated in equipotency conversion tables. Pain relief was assessed at weekly intervals for the next 3 weeks Results Pain relief as assessed by VAS, PPI, and PRI significantly improved (p Conclusion Opioid switching at 50% of the calculated equianalgesic dose produced a significant reduction in pain levels and rescue medication. The incidence of side effects decreased and no new side effects were noted. Further studies are required to provide individualized treatment for patients according to their different types of cancer.

  8. Low-Loss, High-Isolation Microwave Microelectromechanical Systems (MEMS) Switches Being Developed

    Science.gov (United States)

    Ponchak, George E.

    2002-01-01

    Switches, electrical components that either permit or prevent the flow of electricity, are the most important and widely used electrical devices in integrated circuits. In microwave systems, switches are required for switching between the transmitter and receiver; in communication systems, they are needed for phase shifters in phased-array antennas, for radar and communication systems, and for the new class of digital or software definable radios. Ideally, switches would be lossless devices that did not depend on the electrical signal's frequency or power, and they would not consume electrical power to change from OFF to ON or to maintain one of these two states. Reality is quite different, especially at microwave frequencies. Typical switches in microwave integrated circuits are pin diodes or gallium arsenide (GaAs) field-effect transistors that are nonlinear, with characteristics that depend on the power of the signal. In addition, they are frequency-dependent, lossy, and require electrical power to maintain a certain state. A new type of component has been developed that overcomes most of these technical difficulties. Microelectromechanical (MEMS) switches rely on mechanical movement as a response to an applied electrical force to either transmit or reflect electrical signal power. The NASA Glenn Research Center has been actively developing MEMS for microwave applications for over the last 5 years. Complete fabrication procedures have been developed so that the moving parts of the switch can be released with near 100-percent yield. Moreover, the switches fabricated at Glenn have demonstrated state-of-the-art performance. A typical MEMS switch is shown. The switch extends over the signal and ground lines of a finite ground coplanar waveguide, a commonly used microwave transmission line. In the state shown, the switch is in the UP state and all the microwave power traveling along the transmission line proceeds unimpeded. When a potential difference is applied

  9. Dual-wavelength passively Q-switched ytterbium-doped fiber laser using Fe3O4-nanoparticle saturable absorber and intracavity polarization

    Science.gov (United States)

    Al-Hayali, S. K. M.; Al-Janabi, A. H.

    2018-03-01

    We have experimentally demonstrated the operation of a dual-wavelength passively Q-switched ytterbium-doped fiber laser by using a saturable absorber (SA) based on Fe3O4 nanoparticles in a magnetic fluid. The SA was fabricated by depositing magnetic fluid at the end of an optical fiber ferrule. By performing adjustments to the pump power and polarization controller state in the cavity, a stable dual-wavelength lasing operation was generated without intracavity spectral filters or modulation elements. The Q-switched laser output was achieved at a pump threshold of 80 mW with a maximum output pulse energy of 38.8 nJ, a repetition rate of 73.4 kHz and a minimum pulse width of 3.4 µs. To the best of the authors’ knowledge, this is the first demonstration of a dual-wavelength passively Q-switched fiber laser using Fe3O4 nanoparticles as the SA in the 1.0 µm operation region.

  10. Guaranteed Cost H∞ Controller Synthesis for Switched Systems Defined on Semi-algebraic Sets

    DEFF Research Database (Denmark)

    Ahmadi, Mohamadreza; Mojallali, Hamed; Wisniewski, Rafael

    2014-01-01

    A methodology to design guaranteed cost H∞ controllers for a class of switched systems with polynomial vector fields is proposed. To this end, we use sum of squares programming techniques. In addition, instead of the customary Carathéodory solutions, the analysis is performed in the framework...... of Filippov solutions which subsumes solutions with infinite switching in finite time and sliding modes. Firstly, conditions assuring asymptotic stability of Filippov solutions pertained to a switched system defined on semi-algebraic sets are formulated. Accordingly, we derive a set of sum of squares...

  11. Adaptive Neural Tracking Control for Discrete-Time Switched Nonlinear Systems with Dead Zone Inputs

    Directory of Open Access Journals (Sweden)

    Jidong Wang

    2017-01-01

    Full Text Available In this paper, the adaptive neural controllers of subsystems are proposed for a class of discrete-time switched nonlinear systems with dead zone inputs under arbitrary switching signals. Due to the complicated framework of the discrete-time switched nonlinear systems and the existence of the dead zone, it brings about difficulties for controlling such a class of systems. In addition, the radial basis function neural networks are employed to approximate the unknown terms of each subsystem. Switched update laws are designed while the parameter estimation is invariable until its corresponding subsystem is active. Then, the closed-loop system is stable and all the signals are bounded. Finally, to illustrate the effectiveness of the proposed method, an example is employed.

  12. Optical Interconnects for Smart Antenna Driver-Receiver-Switch System for Wireless Communication

    National Research Council Canada - National Science Library

    Esener, Sadik

    2002-01-01

    ... at 0.3THz-30THz for telecommunication applications in general and for interconnects within the box, in particular, for example for Smart Antenna Driver-Receiver-Switch System for Wireless Communication...

  13. Joint Polar Satellite System Common Ground System Overview

    Science.gov (United States)

    Jamilkowski, M. L.; Smith, D. C.

    2011-12-01

    Jointly acquired by NOAA & NASA, the next-generation civilian environmental satellite system, Joint Polar Satellite System (JPSS), will supply the afternoon orbit & ground system of the restructured NPOESS program. JPSS will replace NOAA's current POES satellites and the ground processing part of both POES & DoD's Defense Weather Satellite System (DWSS)(DMSP replacement). JPSS sensors will collect meteorological, oceanographic, climatological and solar-geophysical data. The ground system, or JPSS Common Ground System (CGS), has 6 integrated product teams/segments: Command, Control & Communications (C3S); Interface Data Processing (IDPS); Field Terminal (FTS); Systems Engineering, Integration & Test (SEIT); Operations & Support (O&S); and Sustainment developed by Raytheon Intelligence & Information Systems. The IDPS will process JPSS data to provide Environmental Data Records (EDRs) to NOAA & DoD processing centers beginning with the NPOESS Preparatory Project (NPP) and through JPSS & DWSS eras. C3S will: manage overall JPSS & DWSS missions from control/status of space/ground assets to ensure timely delivery of high-quality data to IDPS; provide globally-distributed ground assets to collect/transport mission, telemetry and command data between satellites & processing locations; provide all commanding & state-of-health monitoring functions of NPP, JPSS and DWSS satellites, and delivery of mission data to each Central IDP and monitor/report system-wide health/status and data communications with external systems and between CGS segments. SEIT leads the overall effort, including: manage/coordinate/execute JPSS CGS activities with NASA participation/oversight; plan/conduct all activities related to systems engineering, develop & ensure completeness of JPSS CGS functional & technical baselines and perform integration, deployment, testing and verification; sponsor/support modeling & simulation, performance analysis and trade studies; provide engineering for the product

  14. 1.114-gb/s time/space division switch system

    Science.gov (United States)

    Pawelski, Robert L.; Nordin, Ronald A.; Huisman, R. F.; Kelly, S.; Payne, William A.; Veach, R. S.

    1990-10-01

    Advanced digital communication services11 such as Broadband ISDN High Definition Television (HDTV) and enhanced data networking are expected to require high bandwidth and fast reconfiguration time switching centers available in the 1990''s. Digital GaAs IC''s can allow the implementation of these switching centers providing these services efficiently and at a low cost. The low cost arises from the reduction in hardware power maintenance etc. when the switch is designed to operate at the incoming data rate instead of at a lower rate. In order to utilize the capacity of a high bandwidth data link time division multiplexing is employed. This is a technique where multiple digital signals are interleaved (bit byte or block) on one data link. Clearly it is advantageous to have a switch that not only has a large bandwidth but can reconfigure at the data rate so as to provide bit byte or block switching functions thus being compatible with many different transmission formats. We present an experimental Time/Space Division Switch System capable of operating at over 1 Gb/s. Both custom and commercial Gallium Arsenide (GaAs) devices are used in the design of the various system functional blocks. These functional blocks include a Time Slot Interchanger (TSI) Time Multiplexed Switch (TMS) TMS Controller Multiplexer and Demultiplexers. In addition to the system overview we discuss such issues as printed circuit board microwave interconnections and CAD tools for high speed

  15. Mode switching control of dual-evaporator air-conditioning systems

    International Nuclear Information System (INIS)

    Lin, J.-L.; Yeh, T.-J.

    2009-01-01

    Modern air-conditioners incorporate variable-speed compressors and variable-opening expansion valves as the actuators for improving cooling performance and energy efficiency. These actuators have to be properly feedback-controlled; otherwise the systems may exhibit even poorer performance than the conventional machines which use fixed-speed compressors and mechanical expansion valves. Particularly for an air-conditioner with multiple evaporators, there are occasions that the machine is operated in a mode that only selected evaporator(s) is(are) turned on, and switching(s) between modes occurs(occur) during the control process. In this case, one needs to have more carefully designed control and switching strategies to ensure the system performance. In this paper, a framework for mode switching control of the dual-evaporator air-conditioning (DEAC) system is proposed. The framework is basically an integration of a controller and a dynamic compensator. The controller, which possesses the flow-distribution capability and assumes both evaporators are on throughout the control process, is intended to provide nominal performance. While mode switching is achieved by varying the reference settings in the controller, the dynamic compensator is used to improve the transient responses immediately after the switching. Experiments indicate that the proposed framework can achieve satisfactory indoor temperature regulation and provide bumpless switching between different modes of operation.

  16. Method and system for a gas tube switch-based voltage source high voltage direct current transmission system

    Science.gov (United States)

    She, Xu; Chokhawala, Rahul Shantilal; Zhou, Rui; Zhang, Di; Sommerer, Timothy John; Bray, James William

    2016-12-13

    A voltage source converter based high-voltage direct-current (HVDC) transmission system includes a voltage source converter (VSC)-based power converter channel. The VSC-based power converter channel includes an AC-DC converter and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and a DC-AC inverter include at least one gas tube switching device coupled in electrical anti-parallel with a respective gas tube diode. The VSC-based power converter channel includes a commutating circuit communicatively coupled to one or more of the at least one gas tube switching devices. The commutating circuit is configured to "switch on" a respective one of the one or more gas tube switching devices during a first portion of an operational cycle and "switch off" the respective one of the one or more gas tube switching devices during a second portion of the operational cycle.

  17. Theoretical test of Jarzynski's equality for reversible volume-switching processes of an ideal gas system.

    Science.gov (United States)

    Sung, Jaeyoung

    2007-07-01

    We present an exact theoretical test of Jarzynski's equality (JE) for reversible volume-switching processes of an ideal gas system. The exact analysis shows that the prediction of JE for the free energy difference is the same as the work done on the gas system during the reversible process that is dependent on the shape of path of the reversible volume-switching process.

  18. Arc detector system for extraction switches in LHC CERN

    CERN Document Server

    Dahlerup-Petersen, K; Kuper, E; Ovchar, V; Zverev, S

    2006-01-01

    The opening switches, which will be used in case of quenches or other failures in CERN’s future LHC collider to extract the large amounts of energy stored in the magnetic field of the superconducting chains of main dipoles (8 chains with 1350 MJ each) and main quadrupoles (16 chains with about 24 MJ each) consist of an array of series/parallel connected, electro-mechanical D.C. breakers, specifically designed for this particular application. During the opening process the magnet excitation current is transferred from the cluster of breakers to extraction resistors for rapid de-excitation of the magnet chain. An arc detector has been developed in order to facilitate the determination of the need for maintenance interventions on the switches. The paper describes the arc detector and highlight results from operation of the detector with a LHC pilot extraction...

  19. A switched state feedback law for the stabilization of LTI systems.

    Energy Technology Data Exchange (ETDEWEB)

    Santarelli, Keith R.

    2009-09-01

    Inspired by prior work in the design of switched feedback controllers for second order systems, we develop a switched state feedback control law for the stabilization of LTI systems of arbitrary dimension. The control law operates by switching between two static gain vectors in such a way that the state trajectory is driven onto a stable n - 1 dimensional hyperplane (where n represents the system dimension). We begin by briefly examining relevant geometric properties of the phase portraits in the case of two-dimensional systems to develop intuition, and we then show how these geometric properties can be expressed as algebraic constraints on the switched vector fields that are applicable to LTI systems of arbitrary dimension. We then derive necessary and sufficient conditions to ensure stabilizability of the resulting switched system (characterized primarily by simple conditions on eigenvalues), and describe an explicit procedure for designing stabilizing controllers. We then show how the newly developed control law can be applied to the problem of minimizing the maximal Lyapunov exponent of the corresponding closed-loop state trajectories, and we illustrate the closed-loop transient performance of these switched state feedback controllers via multiple examples.

  20. Third-order superintegrable systems separating in polar coordinates

    Energy Technology Data Exchange (ETDEWEB)

    Tremblay, Frederick; Winternitz, Pavel, E-mail: tremblaf@crm.umontreal.c, E-mail: wintern@crm.umontreal.c [Centre de Recherches Mathematiques and Departement de Mathematiques et de Statistique, Universite de Montreal, C.P. 6128, succ. Centre-Ville, Montreal, QC H3C 3J7 (Canada)

    2010-04-30

    A complete classification of quantum and classical superintegrable systems in E{sub 2} is presented that allow the separation of variables in polar coordinates and admit an additional integral of motion of order 3 in the momentum. New quantum superintegrable systems are discovered for which the potential is expressed in terms of the sixth Painleve transcendent or in terms of the Weierstrass elliptic function.

  1. Performance evaluation of 100 Gigabit ethernet switching system

    DEFF Research Database (Denmark)

    Rytlig, Andreas; Ruepp, Sarah Renée; Manolova, Anna Vasileva

    2010-01-01

    100 Gigabit Ethernet is an emerging technology and to support it, existing switch fabrics need to be redesigned. High throughput and QoS are required. A scalable multi-stage fabric based on a Clos architecture is envisaged to meet these demands. Using OPNET modeler, a design based on a variation ...... and trans-diagonal patterns, as well as self-similar traffic obtained from ON/OFF Pareto distributed processes....

  2. Global dynamics for switching systems and their extensions by linear differential equations

    Science.gov (United States)

    Huttinga, Zane; Cummins, Bree; Gedeon, Tomáš; Mischaikow, Konstantin

    2018-03-01

    Switching systems use piecewise constant nonlinearities to model gene regulatory networks. This choice provides advantages in the analysis of behavior and allows the global description of dynamics in terms of Morse graphs associated to nodes of a parameter graph. The parameter graph captures spatial characteristics of a decomposition of parameter space into domains with identical Morse graphs. However, there are many cellular processes that do not exhibit threshold-like behavior and thus are not well described by a switching system. We consider a class of extensions of switching systems formed by a mixture of switching interactions and chains of variables governed by linear differential equations. We show that the parameter graphs associated to the switching system and any of its extensions are identical. For each parameter graph node, there is an order-preserving map from the Morse graph of the switching system to the Morse graph of any of its extensions. We provide counterexamples that show why possible stronger relationships between the Morse graphs are not valid.

  3. Cryogenic control system of the large COMPASS polarized target

    CERN Document Server

    Gautheron, F; Baum, G; Berglund, P; Doshita, N; Görtz, S; Gustafsson, K K; Horikawa, N; Kisselev, Yu V; Koivuniemi, J H; Kondo, K; Meyer, Werner T; Reicherz, G

    2004-01-01

    The dilution refrigerator used to cool the large COMPASS polarized target is monitored through a PC running LabVIEW trademark 6.1 under Windows 2000 trademark . About 60 parameters of the target (temperatures, pressures, flow rates) are continuously plotted and checked. They are periodically recorded in an Oracle trademark database and in a data file. An alarm for every parameter can be individually activated and optionally connected to a GSM (Global System for Mobile Communication) delivery message system. A web server receives and publishes the online status of the target with online tables and graphics on a dedicated COMPASS polarized target information web site. A Siemens programmable logic controller (PLC) powered by an uninterruptable source keeps the cryogenic system safe and stable during the long beam periods by controlling valves and interlocks. This safety feature protects the dilution refrigerator against potential damages in case of power failure.

  4. Cryogenic control system of the large COMPASS polarized target

    Science.gov (United States)

    Gautheron, F.; Ball, J.; Baum, G.; Berglund, P.; Doshita, N.; Goertz, St.; Gustafsson, K.; Horikawa, N.; Kisselev, Y.; Koivuniemi, J.; Kondo, K.; Meyer, W.; Reicherz, G.

    2004-06-01

    The dilution refrigerator used to cool the large COMPASS polarized target is monitored through a PC running LabVIEW TM 6.1 under Windows 2000 TM. About 60 parameters of the target (temperatures, pressures, flow rates) are continuously plotted and checked. They are periodically recorded in an Oracle TM database and in a data file. An alarm for every parameter can be individually activated and optionally connected to a GSM (Global System for Mobile Communication) delivery message system. A web server receives and publishes the online status of the target with online tables and graphics on a dedicated COMPASS polarized target information web site. A Siemens programmable logic controller (PLC) powered by an uninterruptable source keeps the cryogenic system safe and stable during the long beam periods by controlling valves and interlocks. This safety feature protects the dilution refrigerator against potential damages in case of power failure.

  5. Line Capacity Expansion and Transmission Switching in Power Systems With Large-Scale Wind Power

    DEFF Research Database (Denmark)

    Villumsen, Jonas Christoffer; Bronmo, Geir; Philpott, Andy B.

    2013-01-01

    In 2020 electricity production from wind power should constitute nearly 50% of electricity demand in Denmark. In this paper we look at optimal expansion of the transmission network in order to integrate 50% wind power in the system, while minimizing total fixed investment cost and expected cost...... of power generation. We allow for active switching of transmission elements to reduce congestion effects caused by Kirchhoff's voltage law. Results show that actively switching transmission lines may yield a better utilization of transmission networks with large-scale wind power and increase wind power...... penetration. Furthermore, it is shown that transmission switching is likely to affect the optimal line capacity expansion plan....

  6. A polynomial approach for generating a monoparametric family of chaotic attractors via switched linear systems

    International Nuclear Information System (INIS)

    Aguirre-Hernández, B.; Campos-Cantón, E.; López-Renteria, J.A.; Díaz González, E.C.

    2015-01-01

    In this paper, we consider characteristic polynomials of n-dimensional systems that determine a segment of polynomials. One parameter is used to characterize this segment of polynomials in order to determine the maximal interval of dissipativity and unstability. Then we apply this result to the generation of a family of attractors based on a class of unstable dissipative systems (UDS) of type affine linear systems. This class of systems is comprised of switched linear systems yielding strange attractors. A family of these chaotic switched systems is determined by the maximal interval of perturbation of the matrix that governs the dynamics for still having scroll attractors

  7. Stable polarization short pulse passively Q-switched monolithic microchip laser with [110] cut Cr4+:YAG

    International Nuclear Information System (INIS)

    Wang, Y; Gong, M; Yan, P; Huang, L; Li, D

    2009-01-01

    A monolithic Nd:YAG microchip laser with [110] cut Cr 4+ :YAG is presented. The output beam is linearly polarized with polarization ratio higher than 100:1. The polarization direction is stable, independent of pump power, crystal temperature, LD temperature. In single longitudinal mode operation, stable 259 ps pulses at 2.5 kHz with 82 kW peak power and diffraction limited beam mode are output. With a simple and compact one-pass Nd:YVO 4 amplifier, 144 kW peak power is achieved. Single longitudinal and fundamental transverse mode is kept after passing through the amplifier stage. The microchip laser can be operated in two longitudinal modes with two sets of output pulses by increasing the pump power

  8. Planetary systems in polarized light: Debris disk observations and instrumentation

    Science.gov (United States)

    Millar-Blanchaer, Maxwell A.

    Understanding planet formation is one of the major challenges of modern astronomy. Polarimetry is a powerful tool with which we can confront this challenge. In particular, polarimetric observations can be useful for imaging debris disks and characterizing exoplanet atmospheres. With that in mind, this thesis has been constructed with two main aspects: i) observational studies of two debris disk systems, beta Pic and HD 157587, using the Gemini Planet Imager and ii) the characterization and testing of a new type of diffraction grating, called a polarization grating, that we plan to use for future observations of exoplanet atmospheres. The Gemini Planet Imager is a high-contrast imager that includes a polarimetry mode designed to image circumstellar disks. Here we detail the development of new data analysis techniques that reduce systematics and noise in processed GPI data. We apply these techniques to observations of the beta Pic and HD 157587 debris disks and then fit each disk image to a geometric disk model. The beta Pic disk model's morphology cannot be explained by interactions with the planet beta Pic b, and the presence of a second planet could be invoked to explain the discrepancy. In the case of HD 157587, the disk model's geometric centre is offset from the location of the star, which could be explained by a perturbing planet. Characterization of the planets' interactions with their debris disks is a critical method to gain more information about these two systems. The second component of this thesis focuses on polarization gratings, thin film optical devices that can simultaneously act as polarizing beam splitters and as spectral dispersive elements. Moreover, they can be designed for high diffraction efficiency across a broad wavelength range. These features make polarization gratings useful for many types of astronomical observations. We have carried out laboratory and on-sky test observations using a polarization grating optimized for visible

  9. Switched Control Strategies of Aggregated Commercial HVAC Systems for Demand Response in Smart Grids

    Directory of Open Access Journals (Sweden)

    Kai Ma

    2017-07-01

    Full Text Available This work proposes three switched control strategies for aggregated heating, ventilation, and air conditioning (HVAC systems in commercial buildings to track the automatic generation control (AGC signal in smart grid. The existing control strategies include the direct load control strategy and the setpoint regulation strategy. The direct load control strategy cannot track the AGC signal when the state of charge (SOC of the aggregated thermostatically controlled loads (TCLs exceeds their regulation capacity, while the setpoint regulation strategy provides flexible regulation capacity, but causes larger tracking errors. To improve the tracking performance, we took the advantages of the two control modes and developed three switched control strategies. The control strategies switch between the direct load control mode and the setpoint regulation mode according to different switching indices. Specifically, we design a discrete-time controller and optimize the controller parameter for the setpoint regulation strategy using the Fibonacci optimization algorithm, enabling us to propose two switched control strategies across multiple time steps. Furthermore, we extend the switched control strategies by introducing a two-stage regulation in a single time step. Simulation results demonstrate that the proposed switched control strategies can reduce the tracking errors for frequency regulation.

  10. Nonlinear graphene-based nanophotonic switch working in dense wavelength division multiplexing (DWDM) systems

    Science.gov (United States)

    Wirth L., A. J.; Ferreira, A. C.; Sombra, A. S. B.

    2017-05-01

    Fiber-based devices for operation in fully optical networks are relatively large in size and can not be used in photonic integrated circuits (PICs). We have developed an efficient graphene-based nanophotonic switching nanocell, working in linear regime (cross state) and in non-linear regime (bar state) with relatively low optical power, so that they can be cascaded and integrated in PICs. Indeed, that device is a fully optical switch, which can work in dense wavelength division multiplexing systems.

  11. An optical switch of natural light guiding system based on cubic structure with fresnel surface

    Science.gov (United States)

    Chou, Kao-Hsu; Chen, Yi-Yung; Whang, Allen Jong-Woei

    2009-08-01

    Recently, many researches focus on illumination with sunlight for saving energy and healthy lighting. A Natural Light Guiding System has collecting, transmitting, and lighting parts. In most systems, the paths on transmitting part are fixed so the collected sunlight of the Natural Light Guiding System can not be free managed and is sometime wasted. In this paper, we design an optical switch to change the path of the collected sunlight on the transmitting sunlight. The switch is cubic structure that includes a 45 degree mirror for reflecting sunlight. According to the structure of the optical switch, we can rotate the switch to manage the path of the collected sunlight. When the path is parallel with the mirror, the sunlight will pass through the switch; and when the included angle between the path and mirror is 45 degree, we can change the path of light. For coupling the exit beam into lightpipe, we design the surfaces of cubic structure to be aspheric surface with Fresnel surface. Finally, we simulate the efficiency of the optical switch when the path is changed by the mirror.

  12. Three-tier multi-granularity switching system based on PCE

    Science.gov (United States)

    Wang, Yubao; Sun, Hao; Liu, Yanfei

    2017-10-01

    With the growing demand for business communications, electrical signal processing optical path switching can't meet the demand. The multi-granularity switch system that can improve node routing and switching capabilities came into being. In the traditional network, each node is responsible for calculating the path; synchronize the whole network state, which will increase the burden on the network, so the concept of path calculation element (PCE) is proposed. The PCE is responsible for routing and allocating resources in the network1. In the traditional band-switched optical network, the wavelength is used as the basic routing unit, resulting in relatively low wavelength utilization. Due to the limitation of wavelength continuity, the routing design of the band technology becomes complicated, which directly affects the utilization of the system. In this paper, optical code granularity is adopted. There is no continuity of the optical code, and the number of optical codes is more flexible than the wavelength. For the introduction of optical code switching, we propose a Code Group Routing Entity (CGRE) algorithm. In short, the combination of three-tier multi-granularity optical switching system and PCE can simplify the network structure, reduce the node load, and enhance the network scalability and survivability. Realize the intelligentization of optical network.

  13. Fault detection for discrete-time switched systems with sensor stuck faults and servo inputs.

    Science.gov (United States)

    Zhong, Guang-Xin; Yang, Guang-Hong

    2015-09-01

    This paper addresses the fault detection problem of switched systems with servo inputs and sensor stuck faults. The attention is focused on designing a switching law and its associated fault detection filters (FDFs). The proposed switching law uses only the current states of FDFs, which guarantees the residuals are sensitive to the servo inputs with known frequency ranges in faulty cases and robust against them in fault-free case. Thus, the arbitrarily small sensor stuck faults, including outage faults can be detected in finite-frequency domain. The levels of sensitivity and robustness are measured in terms of the finite-frequency H- index and l2-gain. Finally, the switching law and FDFs are obtained by the solution of a convex optimization problem. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  14. Developmental excitatory-to-inhibitory GABA-polarity switch is disrupted in 22q11.2 deletion syndrome: a potential target for clinical therapeutics.

    Science.gov (United States)

    Amin, Hayder; Marinaro, Federica; De Pietri Tonelli, Davide; Berdondini, Luca

    2017-11-16

    Individuals with 22q11.2 microdeletion syndrome (22q11.2 DS) show cognitive and behavioral dysfunctions, developmental delays in childhood and risk of developing schizophrenia and autism. Despite extensive previous studies in adult animal models, a possible embryonic root of this syndrome has not been determined. Here, in neurons from a 22q11.2 DS mouse model (Lgdel +/- ), we found embryonic-premature alterations in the neuronal chloride cotransporters indicated by dysregulated NKCC1 and KCC2 protein expression levels. We demonstrate with large-scale spiking activity recordings a concurrent deregulation of the spontaneous network activity and homeostatic network plasticity. Additionally, Lgdel +/- networks at early development show abnormal neuritogenesis and void of synchronized spontaneous activity. Furthermore, parallel experiments on Dgcr8 +/- mouse cultures reveal a significant, yet not exclusive contribution of the dgcr8 gene to our phenotypes of Lgdel +/- networks. Finally, we show that application of bumetanide, an inhibitor of NKCC1, significantly decreases the hyper-excitable action of GABA A receptor signaling and restores network homeostatic plasticity in Lgdel +/- networks. Overall, by exploiting an on-a-chip 22q11.2 DS model, our results suggest a delayed GABA-switch in Lgdel +/- neurons, which may contribute to a delayed embryonic development. Prospectively, acting on the GABA-polarity switch offers a potential target for 22q11.2 DS therapeutic intervention.

  15. Diagnosis and Tolerant Strategy of an Open-Switch Fault for T-type Three-Level Inverter Systems

    DEFF Research Database (Denmark)

    Choi, Uimin; Lee, Kyo Beum; Blaabjerg, Frede

    2014-01-01

    This paper proposes a new diagnosis method of an open-switch fault and fault-tolerant control strategy for T-type three-level inverter systems. The location of faulty switch can be identified by the average of normalized phase current and the change of the neutral-point voltage. The proposed fault......-tolerant strategy is explained by dividing into two cases: the faulty condition of half-bridge switches and the neutral-point switches. The performance of the T-type inverter system improves considerably by the proposed fault tolerant algorithm when a switch fails. The roposed method does not require additional...

  16. Development of the switch requirements and architecture of a safety data communication system

    International Nuclear Information System (INIS)

    Jeong, K.I.; Lee, J.K.; Park, H.Y.; Koo, I.S.

    2004-12-01

    In accordance with digitalising the Instrumentation and Control(I and C) systems in the integral reactor, a communication network is required for effective information exchanges between the different equipment, an enhancement of the design flexibility, a simple installation and cost reduction. Generally, a communication network consists of a topology, the protocol, a communication medium, an interconnection device, etc. In this report, the development methods of switch and the architecture of a Safety Data Communication System(SDCS) are investigated and analyzed. In this report, the design requirements for switch are presented, which are the essential requirements to develop the switch in a SDCS of the SMART-P. To establish these requirements, the evaluation and analysis of the design and implementation method of the COTS switches, the architecture of SDCS and the design requirements of a SDCS were performed. At the detail design stage, these requirements will be used for the top-tier requirements, especially the design target and design basis. To develop the detail design requirements in the future, more quantitative and qualitative analyses are required. In the case of selecting the COTS switch and developing the switch, these requirements will also be used for the evaluation guide

  17. Global Uniform Asymptotic Stability of a Class of Switched Linear Systems with an Infinite Number of Subsystems

    Directory of Open Access Journals (Sweden)

    L. F. Araghi

    2014-01-01

    Full Text Available Stability of switching systems with an infinite number of subsystems is important in some structure of systems, like fuzzy systems, neural networks, and so forth. Because of the relationship between stability of a set of matrices and switching systems, this paper first studies the stability of a set of matrices, then and the results are applied for stability of switching systems. Some new conditions for globally uniformly asymptotically stability (GUAS of discrete-time switched linear systems with an infinite number of subsystems are proposed. The paper considers some examples and simulation results.

  18. Homogeneous Stabilizer by State Feedback for Switched Nonlinear Systems Using Multiple Lyapunov Functions’ Approach

    Directory of Open Access Journals (Sweden)

    Hui Ye

    2017-01-01

    Full Text Available This paper investigates the problem of global stabilization for a class of switched nonlinear systems using multiple Lyapunov functions (MLFs. The restrictions on nonlinearities are neither linear growth condition nor Lipschitz condition with respect to system states. Based on adding a power integrator technique, we design homogeneous state feedback controllers of all subsystems and a switching law to guarantee that the closed-loop system is globally asymptotically stable. Finally, an example is given to illustrate the validity of the proposed control scheme.

  19. FUZZY LOGIC CONTROLLED SWITCHED RELUCTANCE MOTOR DRIVER DESIGNING FOR A LIFT SYSTEM

    Directory of Open Access Journals (Sweden)

    Mahir DURSUN

    2006-02-01

    Full Text Available In this study, a 8/6 poles, four phases, 3.44 kW switched reluctance motor driver was used for a elavator load. For this aim, it has been designed a swithed reluctance motor driver for a lift system. At the driver system was used a buck konverter. The speed was controlled by motor phase voltage control. The voltage value has been controlled with fuzzy logic controller by using TMS320LF2407 controller. Fuzzy controlled switched reluctance motor was used for a elavator load by using designed driver system.

  20. High Performance Polar Decomposition on Distributed Memory Systems

    KAUST Repository

    Sukkari, Dalal E.

    2016-08-08

    The polar decomposition of a dense matrix is an important operation in linear algebra. It can be directly calculated through the singular value decomposition (SVD) or iteratively using the QR dynamically-weighted Halley algorithm (QDWH). The former is difficult to parallelize due to the preponderant number of memory-bound operations during the bidiagonal reduction. We investigate the latter scenario, which performs more floating-point operations but exposes at the same time more parallelism, and therefore, runs closer to the theoretical peak performance of the system, thanks to more compute-bound matrix operations. Profiling results show the performance scalability of QDWH for calculating the polar decomposition using around 9200 MPI processes on well and ill-conditioned matrices of 100K×100K problem size. We study then the performance impact of the QDWH-based polar decomposition as a pre-processing step toward calculating the SVD itself. The new distributed-memory implementation of the QDWH-SVD solver achieves up to five-fold speedup against current state-of-the-art vendor SVD implementations. © Springer International Publishing Switzerland 2016.

  1. Compact rf polarizer and its application to pulse compression systems

    Directory of Open Access Journals (Sweden)

    Matthew Franzi

    2016-06-01

    Full Text Available We present a novel method of reducing the footprint and increasing the efficiency of the modern multi-MW rf pulse compressor. This system utilizes a high power rf polarizer to couple two circular waveguide modes in quadrature to a single resonant cavity in order to replicate the response of a traditional two cavity configuration using a 4-port hybrid. The 11.424 GHz, high-Q, spherical cavity has a 5.875 cm radius and is fed by the circularly polarized signal to simultaneously excite the degenerate TE_{114} modes. The overcoupled spherical cavity has a Q_{0} of 9.4×10^{4} and coupling factor (β of 7.69 thus providing a loaded quality factor Q_{L} of 1.06×10^{4} with a fill time of 150 ns. Cold tests of the polarizer demonstrated good agreement with the numerical design, showing transmission of -0.05  dB and reflection back to the input rectangular WR 90 waveguide less than -40  dB over a 100 MHz bandwidth. This novel rf pulse compressor was tested at SLAC using XL-4 Klystron that provided rf power up to 32 MW and generated peak output power of 205 MW and an average of 135 MW over the discharged signal. A general network analysis of the polarizer is discussed as well as the design and high power test of the rf pulse compressor.

  2. Mathematical solutions of rate equations of a laser-diode end-pumped passively Q-switched and mode locked Nd-laser with Cr4+:YAG polarized saturable absorber

    International Nuclear Information System (INIS)

    Abdul Ghani, B.; Hammadi, M.

    2012-01-01

    The intracavity frequency-doubling (IFD) of a simultaneous passively Q-switched mode-locked diode-pumped Nd 3 + - laser is studied with a polarized isotropic Cr 4 +: YAG saturable absorber. A general recurrence formula for the mode-locked pulses under the Q-switched envelope at fundamental wavelength has been reconstructed in order to analyze the temporal shape behavior of a single Q-switched envelope with mode-locking pulse trains. This formula has been derived taking into account the impact of the IFD and polarized Cr 4 +: YAG saturable absorber.The presented mathematical model describes the self-induced anisotropy appeared in the polarized Cr 4 +: YAG in the nonlinear stage of the giant pulse formation. For the anisotropic Nd 3 +: YVO 4 active medium, the generated polarized waves are assumed to be fixed through the lasing cycle. Besides, the maximum absorber initial transmission and the minimum mirror reflectivity values have been determined from the second threshold criterion. The calculated numerical results demonstrate the impact of the variation of the input laser parameters (rotational angle of the polarized crystal, absorber initial transmission and the output mirror reflectivity) on the characteristics of the output laser pulse (SH peak power, pulse width, pulse duration and shift pulse position of central mode). The calculated numerical results in this work is in good qualitative and quantitative agreement with the available experimental data reported in the references. (author)

  3. Event-triggered Dynamic Output Feedback Control for Switched Linear Systems

    NARCIS (Netherlands)

    Qi, Yiwen; Cao, Ming

    2016-01-01

    Switched linear systems and their control have been an active research field in the past two decades; however, no systematic results have been reported in the literature on how such systems behave when event-triggered control is introduced. While the potential advantage of introducing

  4. Finite-time boundedness and stabilisation of switched linear systems using event-triggered controllers

    NARCIS (Netherlands)

    Qi, Yiwen; Cao, Ming

    2017-01-01

    This study proposes a systematic control design approach to consider jointly the event-triggered communication mechanism and state-feedback control for switched linear systems. The systems determine the necessary samplings of the feedback signal by constructing predefined events that can reduce

  5. Reversible Polarization Rotation in Epitaxial Ferroelectric Bilayers

    DEFF Research Database (Denmark)

    Liu, Guangqing; Zhang, Qi; Huang, Hsin-Hui

    2016-01-01

    large-scale polarization rotation switching (≈60 μC cm−2) and an effective d 33 response 500% (≈250 pm V−1) larger than the PZT-R layer alone. Furthermore, this enhancement is stable for more than 107 electrical switching cycles. These bilayers present a simple and highly controllable means to design...... and optimize rotational polar systems as an alternate to traditional composition-based approaches. The precise control of the subtle interface-driven interactions between the lattice and the external factors that control polarization opens a new door to enhanced—or completely new—functional properties....

  6. Switch and examine transmit diversity for spectrum sharing systems

    KAUST Repository

    Abdallah, Mohamed M.

    2011-06-01

    In this paper, we develop a switch and examine transmit diversity algorithm for spectrum sharing cognitive networks. We consider a cognitive network composed of a primary link that employs constant rate and constant power transmission scheme with automatic-and-repeat request (ARQ) protocol, while the secondary link is composed of a fixed power multiple-antenna secondary transmitter and a single antenna receiver. Our objective is to develop a low complex transmit diversity algorithm at the secondary transmitter that maximizes the performance of the secondary link in terms of the effective throughput while maintaining a predetermined maximum loss in the packet rate of the primary link. In achieving this objective, we develop an algorithm that selects the best antenna, which maintains the quality of the secondary link in terms of signal-to-noise ratio above a specific threshold, based on overhearing the acknowledgment (ACK) and negative acknowledgment (NACK) feedback messages transmitted over the primary link. We also develop closed form expressions for the bit error rates and the effective throughput of the secondary link. © 2011 IEEE.

  7. Design of an unmanned Martian polar exploration system

    Science.gov (United States)

    Baldwin, Curt; Chitwood, Denny; Demann, Brian; Ducheny, Jordan; Hampton, Richard; Kuhns, Jesse; Mercer, Amy; Newman, Shawn; Patrick, Chris; Polakowski, Tony

    1994-01-01

    The design of an unmanned Martian polar exploration system is presented. The system elements include subsystems for transportation of material from earth to Mars, study of the Martian north pole, power generation, and communications. Early next century, three Atlas 2AS launch vehicles will be used to insert three Earth-Mars transfer vehicles, or buses, into a low-energy transfer orbit. Capture at Mars will be accomplished by aerobraking into a circular orbit. Each bus contains four landers and a communications satellite. Six of the twelve total landers will be deployed at 60 deg intervals along 80 deg N, and the remaining six landers at 5 deg intervals along 30 deg E from 65 deg N to 90 deg N by a combination of retrorockets and parachutes. The three communications satellites will be deployed at altitudes of 500 km in circular polar orbits that are 120 deg out of phase. These placements maximize the polar coverage of the science and communications subsystems. Each lander contains scientific equipment, two microrovers, power supplies, communications equipment, and a science computer. The lander scientific equipment includes a microweather station, seismometer, thermal probe, x-ray spectrometer, camera, and sounding rockets. One rover, designed for short-range (less than 2 km) excursions from the lander, includes a mass spectrometer for mineral analysis, an auger/borescope system for depth profiling, a deployable thermal probe, and charge coupled device cameras for terrain visualization/navigation. The second rover, designed for longer-range (2-5 km) excursions from the lander, includes radar sounding/mapping equipment, a seismometer, and laser ranging devices. Power for all subsystems is supplied by a combination of solar cells, Ni-H batteries, and radioisotope thermoelectric generators. Communications are sequenced from rovers, sounding rockets, and remote sensors to the lander, then to the satellites, through the Deep Space Network to and from earth.

  8. Automatic limit switch system for scintillation device and method of operation

    International Nuclear Information System (INIS)

    Brunnett, C.J.; Ioannou, B.N.

    1976-01-01

    A scintillation scanner is described having an automatic limit switch system for setting the limits of travel of the radiation detection device which is carried by a scanning boom. The automatic limit switch system incorporates position responsive circuitry for developing a signal representative of the position of the boom, reference signal circuitry for developing a signal representative of a selected limit of travel of the boom, and comparator circuitry for comparng these signals in order to control the operation of a boom drive and indexing mechanism. (author)

  9. Results from a data acquisition system prototype project using a switch-based event builder

    International Nuclear Information System (INIS)

    Black, D.; Andresen, J.; Barsotti, E.; Baumbaugh, A.; Esterline, D.; Knickerbocker, K.; Kwarciany, R.; Moore, G.; Patrick, J.; Swoboda, C.; Treptow, K.; Trevizo, O.; Urish, J.; VanConant, R.; Walsh, D.; Bowden, M.; Booth, A.; Cancelo, G.

    1991-11-01

    A prototype of a high bandwidth parallel event builder has been designed and tested. The architecture is based on a simple switching network and is adaptable to a wide variety of data acquisition systems. An eight channel system with a peak throughput of 160 Megabytes per second has been implemented. It is modularly expandable to 64 channels (over one Gigabyte per second). The prototype uses a number of relatively recent commercial technologies, including very high speed fiber-optic data links, high integration crossbar switches and embedded RISC processors. It is based on an open architecture which permits the installation of new technologies with little redesign effort. 5 refs., 6 figs

  10. Generalized Gramian Framework for Model/Controller Order Reduction of Switched Systems

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza; Wisniewski, Rafal

    2011-01-01

    In this article, a general method for model/controller order reduction of switched linear dynamical systems is presented. The proposed technique is based on the generalised gramian framework for model reduction. It is shown that different classical reduction methods can be developed into a genera......In this article, a general method for model/controller order reduction of switched linear dynamical systems is presented. The proposed technique is based on the generalised gramian framework for model reduction. It is shown that different classical reduction methods can be developed...

  11. Identification of fractional-order systems via a switching differential evolution subject to noise perturbations

    International Nuclear Information System (INIS)

    Zhu, Wu; Fang, Jian-an; Tang, Yang; Zhang, Wenbing; Xu, Yulong

    2012-01-01

    In this Letter, a differential evolution variant, called switching DE (SDE), has been employed to estimate the orders and parameters in incommensurate fractional-order chaotic systems. The proposed algorithm includes a switching population utilization strategy, where the population size is adjusted dynamically based on the solution-searching status. Thus, this adaptive control method realizes the identification of fractional-order Lorenz, Lü and Chen systems in both deterministic and stochastic environments, respectively. Numerical simulations are provided, where comparisons are made with five other State-of-the-Art evolutionary algorithms (EAs) to verify the effectiveness of the proposed method. -- Highlights: ► Switching population utilization strategy is applied for differential evolution. ► The parameters are estimated in both deterministic and stochastic environments. ► Comparisons with five other EAs verify the effectiveness of the proposed method.

  12. Asynchronous H∞ Dynamic Output Feedback Control of Switched Time-Delay Systems with Sensor Nonlinearity and Missing Measurements

    Directory of Open Access Journals (Sweden)

    Jiwei Wen

    2014-01-01

    Full Text Available The H∞ dynamic output feedback control problem for a class of discrete-time switched time-delay systems under asynchronous switching is investigated in this paper. Sensor nonlinearity and missing measurements are considered when collecting output knowledge of the system. Firstly, when there exists asynchronous switching between the switching modes and the candidate controllers, new results on the regional stability and l2 gain analysis for the underlying system are given by allowing the Lyapunov-like function (LLF to increase with a random probability. Then, a mean square stabilizing output feedback controller and a switching law subject to average dwell time (ADT are obtained with a given disturbance attenuation level. Moreover, the mean square domain of attraction could be estimated by a convex combination of a set of ellipsoids, the number of which depends on the number of switching modes. Finally, a numerical example is given to illustrate the effectiveness of the proposed method.

  13. Reliability modelling and simulation of switched linear system ...

    African Journals Online (AJOL)

    Thus, constructing a subsystem Markov model and matching its parameters with the specified safety factors provides the basis for the entire system analysis. For the system simulation, temporal databases and predictive control algorithm are designed. The simulation results are analyzed to assess the reliability of the system ...

  14. Design and Prototype of an Automated Column-Switching HPLC System for Radiometabolite Analysis.

    Science.gov (United States)

    Vasdev, Neil; Collier, Thomas Lee

    2016-08-17

    Column-switching high performance liquid chromatography (HPLC) is extensively used for the critical analysis of radiolabeled ligands and their metabolites in plasma. However, the lack of streamlined apparatus and consequently varying protocols remain as a challenge among positron emission tomography laboratories. We report here the prototype apparatus and implementation of a fully automated and simplified column-switching procedure to allow for the easy and automated determination of radioligands and their metabolites in up to 5 mL of plasma. The system has been used with conventional UV and coincidence radiation detectors, as well as with a single quadrupole mass spectrometer.

  15. Reconfigurable radio-over-fiber system based on optical switch and tunable filter

    Science.gov (United States)

    Li, Xiao; Yin, Rui; Ji, Wei; Sun, Kai; Zhang, Shicheng

    2017-09-01

    As the best candidate for wireless-access networks, radio-over-fiber (RoF) technology can carry a variety of business. It is necessary to provide differentiated services for different users, so the network needs to produce signals with different modulation formats and different frequencies. A reconfigurable RoF system based on a switch and tunable optical filter that can realize modulation format conversion and multiple frequency signal switching functions is designed. It has a good performance in terms of bit error rate and an eye diagram. The design can help to use radio frequency resources efficiently and make dynamic bandwidth resources controllable.

  16. Multiuser switched scheduling systems with per-user threshold and post-user selection

    KAUST Repository

    Nam, Haewoon

    2010-06-01

    A multiuser switched diversity scheduling scheme with per-user feedback threshold is proposed in this paper. Unlike the conventional multiuser switched diversity scheduling scheme where a single threshold is used by all the users in order to determine whether to transmit a feedback, the proposed scheme deploys per-user threshold, where each user uses a potentially different threshold than other users thresholds. This paper first provides a generic analytical framework for the optimal feedback thresholds in a closed form. Then we investigates the impact of user sequence strategies and post selection strategies on the performance of the multiuser switched scheduling scheme with per-user threshold. Numerical and simulation results show that the proposed scheme provides a higher system capacity compared to the conventional scheme. © 2010 IEEE.

  17. A System for English Vocabulary Acquisition Based on Code-Switching

    Science.gov (United States)

    Mazur, Michal; Karolczak, Krzysztof; Rzepka, Rafal; Araki, Kenji

    2016-01-01

    Vocabulary plays an important part in second language learning and there are many existing techniques to facilitate word acquisition. One of these methods is code-switching, or mixing the vocabulary of two languages in one sentence. In this paper the authors propose an experimental system for computer-assisted English vocabulary learning in…

  18. Adaptive Neural Networks Prescribed Performance Control Design for Switched Interconnected Uncertain Nonlinear Systems.

    Science.gov (United States)

    Li, Yongming; Tong, Shaocheng

    2017-06-28

    In this paper, an adaptive neural networks (NNs)-based decentralized control scheme with the prescribed performance is proposed for uncertain switched nonstrict-feedback interconnected nonlinear systems. It is assumed that nonlinear interconnected terms and nonlinear functions of the concerned systems are unknown, and also the switching signals are unknown and arbitrary. A linear state estimator is constructed to solve the problem of unmeasured states. The NNs are employed to approximate unknown interconnected terms and nonlinear functions. A new output feedback decentralized control scheme is developed by using the adaptive backstepping design technique. The control design problem of nonlinear interconnected switched systems with unknown switching signals can be solved by the proposed scheme, and only a tuning parameter is needed for each subsystem. The proposed scheme can ensure that all variables of the control systems are semi-globally uniformly ultimately bounded and the tracking errors converge to a small residual set with the prescribed performance bound. The effectiveness of the proposed control approach is verified by some simulation results.

  19. pth Moment stability of impulsive stochastic delay differential systems with Markovian switching

    Science.gov (United States)

    Wu, Xiaotai; Zhang, Wenbing; Tang, Yang

    2013-07-01

    This paper is concerned with the pth moment stability of impulsive stochastic delay differential systems with Markovian switching. By using the Razumikhin-type method, some stability criteria are obtained, which can loosen the constraints of the existing results and thus reduce the conservativeness. Two examples are presented to demonstrate the usefulness of the proposed results.

  20. Analytical and computational study of magnetization switching in kinetic Ising systems with demagnetizing fields

    DEFF Research Database (Denmark)

    Richards, H.L.; Rikvold, P.A.

    1996-01-01

    particularly promising as materials for high-density magnetic recording media. In this paper we use analytic arguments and Monte Carlo simulations to quantitatively study the effects of the demagnetizing field on the dynamics of magnetization switching in two-dimensional, single-domain, kinetic Ising systems...

  1. Novel flat datacenter network architecture based on scalable and flow-controlled optical switch system.

    Science.gov (United States)

    Miao, Wang; Luo, Jun; Di Lucente, Stefano; Dorren, Harm; Calabretta, Nicola

    2014-02-10

    We propose and demonstrate an optical flat datacenter network based on scalable optical switch system with optical flow control. Modular structure with distributed control results in port-count independent optical switch reconfiguration time. RF tone in-band labeling technique allowing parallel processing of the label bits ensures the low latency operation regardless of the switch port-count. Hardware flow control is conducted at optical level by re-using the label wavelength without occupying extra bandwidth, space, and network resources which further improves the performance of latency within a simple structure. Dynamic switching including multicasting operation is validated for a 4 x 4 system. Error free operation of 40 Gb/s data packets has been achieved with only 1 dB penalty. The system could handle an input load up to 0.5 providing a packet loss lower that 10(-5) and an average latency less that 500 ns when a buffer size of 16 packets is employed. Investigation on scalability also indicates that the proposed system could potentially scale up to large port count with limited power penalty.

  2. Switched modified function projective synchronization of hyperchaotic Qi system with uncertain parameters

    Science.gov (United States)

    Sebastian Sudheer, K.; Sabir, M.

    2010-12-01

    This work is involved with switched modified function projective synchronization of two identical Qi hyperchaotic systems using adaptive control method. Switched synchronization of chaotic systems in which a state variable of the drive system synchronize with a different state variable of the response system is a promising type of synchronization as it provides greater security in secure communication. Modified function projective synchronization with the unpredictability of scaling functions can enhance security. Recently formulated hyperchaotic Qi system in the hyperchaotic mode has an extremely broad frequency bandwidth of high magnitudes, verifying its unusual random nature and indicating its great potential for some relevant engineering applications such as secure communications. By Lyapunove stability theory, the adaptive control law and the parameter update law are derived to make the state of two chaotic systems modified function projective synchronized. Synchronization under the effect of noise is also considered. Numerical simulations are presented to demonstrate the effectiveness of the proposed adaptive controllers.

  3. Polarization mode dispersion in optical fiber transmission systems

    Science.gov (United States)

    Cameron, John Charles

    The birefringence of optical fibers causes pulse broadening in fiber-optic communication systems. This phenomenon is known as polarization mode dispersion (PMD). PMD is one of the most important limiting factors for high capacity fiber-optic systems. A number of aspects of PMD are examined in this thesis. In Chapter 2 an expression is derived for the probability density function of the pulse broadening due to first-order PMD. This result is used to obtain an expression for the system limitation due to PMD. The birefringence of optical fibers is commonly simulated with the waveplate model. In Chapter 3 two standard versions of the waveplate model are introduced. In addition, a novel waveplate model is proposed. The characteristics of the three versions of the waveplate model are examined to confirm their suitability for use in subsequent chapters of the thesis. Simulations with the waveplate model are performed in Chapter 4 for three purposes: (1) to determine the impact of chromatic dispersion on the system limitation due to PMD, (2) to examine the effectiveness of three different PMD compensation techniques in the presence of chromatic dispersion, and (3) to examine the interaction of second-order chromatic dispersion with PMD. The simulations in Chapter 4 reveal that it is possible with one compensation technique to have output pulses that are narrower than the input pulses. In Chapter 5, this anomalous pulse narrowing is demonstrated analytically for a simple model of PMD and through experiment. It is also shown that this pulse narrowing can be explained as an interference phenomenon. Chapter 6 presents measurements of PMD and state of polarization on installed optical fibers. The PMD coefficients of 122 fibers are presented and the results are analyzed in terms of the age of the fibers and the type of cabling. Measurements of the time evolution of PMD and state of polarization are presented for fibers installed in both buried and aerial cables. The uncertainty

  4. Magnetospheric convection and current system in the dayside polar cap

    International Nuclear Information System (INIS)

    Nishida, A.; Mukai, T.; Tsuruda, K.; Hayakawa, H.

    1992-01-01

    Field and particle observations on EXOS-D (Akebono) have yielded new information on convection and current system in the dayside polar cap. Convection patterns are distinctly different depending upon whether IMF B z is northward or southward. The number of convection cells is two when B z is southward but four when B z is northward. Lobe cells in which plasma flows sunward in the region of open field lines are observed as a pair (of which one is in the dawn and the other in the dusk sector) for any polarity of IMF B y and B z . Ions in the keV range precipitate not only in the dayside cusp region but also along the sunward directed streamlines of the dawn and dusk lobe cells. These observations require reconsideration on the position and the extent of the reconnection region on the magnetopause. They also suggest that the magnetotail plays a vital role in some phenomena which have been ascribed to dayside magnetopause processes. We have not been able to find evidence to prove the presence of the viscous cell under southward IMF

  5. Massively Parallel Polar Decomposition on Distributed-Memory Systems

    KAUST Repository

    Ltaief, Hatem

    2018-01-01

    We present a high-performance implementation of the Polar Decomposition (PD) on distributed-memory systems. Building upon on the QR-based Dynamically Weighted Halley (QDWH) algorithm, the key idea lies in finding the best rational approximation for the scalar sign function, which also corresponds to the polar factor for symmetric matrices, to further accelerate the QDWH convergence. Based on the Zolotarev rational functions—introduced by Zolotarev (ZOLO) in 1877— this new PD algorithm ZOLO-PD converges within two iterations even for ill-conditioned matrices, instead of the original six iterations needed for QDWH. ZOLO-PD uses the property of Zolotarev functions that optimality is maintained when two functions are composed in an appropriate manner. The resulting ZOLO-PD has a convergence rate up to seventeen, in contrast to the cubic convergence rate for QDWH. This comes at the price of higher arithmetic costs and memory footprint. These extra floating-point operations can, however, be processed in an embarrassingly parallel fashion. We demonstrate performance using up to 102, 400 cores on two supercomputers. We demonstrate that, in the presence of a large number of processing units, ZOLO-PD is able to outperform QDWH by up to 2.3X speedup, especially in situations where QDWH runs out of work, for instance, in the strong scaling mode of operation.

  6. Realisation and Optimization the System of Ridge Waveguide Polarizer by Genetic Algorithms for Telecommunication Satellite Antennas

    OpenAIRE

    BOUSALAH, FAYZA; BOUKLI HACENE, NOUR EDDINE

    2012-01-01

    The ridged waveguide polarizer is considered as the better way to get right-hand and left-hand circular polarization in the antennas of telecommunications satellites. In fact, it is a system of three ports used to feed a square waveguide antenna in order to achieve high purity in the right-hand and left-hand circular polarization. Obtaining a great purity of polarization results by the addition from screw from adaptation and blades from correction. A solution with ...

  7. Power Electronic Systems for Switched Reluctance Generator based Wind Farms and DC Networks

    DEFF Research Database (Denmark)

    Park, Kiwoo

    . Under these circumstances, research on dc network connection with a novel wind power generator system is presented in this thesis, which mainly consists of two major parts: control of a Switched Reluctance Generator (SRG) system and development of dc-dc converters for a dc network system in a wind farm...... for generators in wind turbine systems. However, despite all these advantageous features, the SRG has not been widely employed in wind energy applications. The most renowned technical disadvantages of the SRG are its nonlinearity and high torque ripples, which should be overcome to promote the application...... are presented to verify the feasibility and operational principles of the proposed converters. Finally, modelling and control of a dc-grid wind farm using one of the proposed dc-dc converters are presented. An average model provides insight into the overall performance of the system. Meanwhile, a switching...

  8. Fuel switching in Harare : An almost ideal demand system approach

    NARCIS (Netherlands)

    Chambwera, Muyeye; Folmer, Henk

    In urban areas several energy choices are available and the amount of (a given type of) fuel consumed is based on complex household decision processes. This paper analyzes urban fuel (particularly firewood) demand in an energy mix context by means of an Almost Ideal Demand System based on a survey

  9. Fuel switching in Harare: An almost ideal demand system approach

    NARCIS (Netherlands)

    Chambwera, M.; Folmer, H.

    2007-01-01

    In urban areas several energy choices are available and the amount of (a given type of) fuel consumed is based on complex household decision processes. This paper analyzes urban fuel (particularly firewood) demand in an energy mix context by means of an Almost Ideal Demand System based on a survey

  10. A fuzzy expert system for predicting the performance of switched reluctance motor

    International Nuclear Information System (INIS)

    Mirzaeian, B.; Moallem, M.; Lucas, Caro

    2001-01-01

    In this paper a fuzzy expert system for predicting the performance of a switched reluctance motor has been developed. The design vector consists of design parameters, and output performance variables are efficiency and torque ripple. An accurate analysis program based on Improved Magnetic Equivalent Circuit method has been used to generate the input-output data. These input-output data is used to produce the initial fuzzy rules for predicting the performance of Switched Reluctance Motor. The initial set of fuzzy rules with triangular membership functions has been devised using a table look-up scheme. The initial fuzzy rules have been optimized to a set of fuzzy rules with Gaussian membership functions using gradient descent training scheme. The performance prediction results for a 6/8, 4 kw, Switched Reluctance Motor shows good agreement with the results obtained from Improved Magnetic Equivalent Circuit method or Finite Element analysis. The developed fuzzy expert system can be used for fast prediction of motor performance in the optimal design process or on-line control schemes of Switched Reluctance motor

  11. Fault Detection for Wireless Networked Control Systems with Stochastic Switching Topology and Time Delay

    Directory of Open Access Journals (Sweden)

    Pengfei Guo

    2014-01-01

    Full Text Available This paper deals with the fault detection problem for a class of discrete-time wireless networked control systems described by switching topology with uncertainties and disturbances. System states of each individual node are affected not only by its own measurements, but also by other nodes’ measurements according to a certain network topology. As the topology of system can be switched in a stochastic way, we aim to design H∞ fault detection observers for nodes in the dynamic time-delay systems. By using the Lyapunov method and stochastic analysis techniques, sufficient conditions are acquired to guarantee the existence of the filters satisfying the H∞ performance constraint, and observer gains are derived by solving linear matrix inequalities. Finally, an illustrated example is provided to verify the effectiveness of the theoretical results.

  12. Energy-Efficient Distributed Filtering in Sensor Networks: A Unified Switched System Approach.

    Science.gov (United States)

    Zhang, Dan; Shi, Peng; Zhang, Wen-An; Yu, Li

    2016-04-21

    This paper is concerned with the energy-efficient distributed filtering in sensor networks, and a unified switched system approach is proposed to achieve this goal. For the system under study, the measurement is first sampled under nonuniform sampling periods, then the local measurement elements are selected and quantized for transmission. Then, the transmission rate is further reduced to save constrained power in sensors. Based on the switched system approach, a unified model is presented to capture the nonuniform sampling, the measurement size reduction, the transmission rate reduction, the signal quantization, and the measurement missing phenomena. Sufficient conditions are obtained such that the filtering error system is exponentially stable in the mean-square sense with a prescribed H∞ performance level. Both simulation and experiment studies are given to show the effectiveness of the proposed new design technique.

  13. Control and switching synchronization of fractional order chaotic systems using active control technique

    KAUST Repository

    Radwan, A.G.

    2013-03-13

    This paper discusses the continuous effect of the fractional order parameter of the Lü system where the system response starts stable, passing by chaotic behavior then reaching periodic response as the fractional-order increases. In addition, this paper presents the concept of synchronization of different fractional order chaotic systems using active control technique. Four different synchronization cases are introduced based on the switching parameters. Also, the static and dynamic synchronizations can be obtained when the switching parameters are functions of time. The nonstandard finite difference method is used for the numerical solution of the fractional order master and slave systems. Many numeric simulations are presented to validate the concept for different fractional order parameters.

  14. A switched energy saving position controller for variable-pressure electro-hydraulic servo systems.

    Science.gov (United States)

    Tivay, Ali; Zareinejad, Mohammad; Rezaei, S Mehdi; Baghestan, Keivan

    2014-07-01

    The electro-hydraulic servo system (EHSS) demonstrates a relatively low level of efficiency compared to other available actuation methods. The objective of this paper is to increase this efficiency by introducing a variable supply pressure into the system and controlling this pressure during the task of position tracking. For this purpose, an EHSS structure with controllable supply pressure is proposed and its dynamic model is derived from the basic laws of physics. A switching control structure is then proposed to control both the supply pressure and the cylinder position at the same time, in a way that reduces the overall energy consumption of the system. The stability of the proposed switching control system is guaranteed by proof, and its performance is verified by experimental testing. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

  15. Open-Switch Fault Detection Method of a Back-to-Back Converter Using NPC Topology for Wind Turbine Systems

    DEFF Research Database (Denmark)

    Lee, June-Seok; Lee, Kyo_Beum; Blaabjerg, Frede

    2015-01-01

    In wind turbine generation (WTG) systems, a back-to-back converter with a neutral-point-clamped (NPC) topology is widely used because this topology has more advantages than a conventional two-level topology, particularly when operating at high power. There are 12 switches in the NPC topology....... An open-switch fault in the NPC rectifier of the back-to-back converter leads to the distortion of the input current and torque vibration in the system. Additionally, an open-switch fault in the NPC inverter of the back-to-back converter causes the distortion of the output current. Furthermore, the WTG...... system can break down in the worst case scenario. To improve the reliability of WTG systems, an open-switch fault detection method for back-to-back converters using the NPC topology is required. This study analyzes effects of inner and outer open-switch faults of the NPC rectifier and inverter...

  16. A switched capacitor array based system for high-speed calorimetry

    International Nuclear Information System (INIS)

    Levi, M.; Bebek, C.; Ely, R.; Jared, R.; Kipnis, I.; Kirsten, F.; Kleinfelder, S.; Merrick, T.; Milgrome, O.

    1991-12-01

    A sixteen channel analog transient recorder with 256 cells per channel has been fabricated as an integrated circuit. The circuit uses switched capacitor array technology to achieve simultaneous read/write capability and twelve bit dynamic range. Combined with highly parallel analog-to-digital converter and readout control circuitry being developed this system should satisfy the demanding electronics requirements for calorimeter detectors at the SSC. The system design and test results are presented

  17. Adaptive Morse-coded single-switch communication system for the disabled.

    Science.gov (United States)

    Luo, C H; Shih, C H

    1996-04-01

    Automatic recognition of Morse-code is generally developed at a fixed typing rate. However, this is not suitable for the disabled due to their difficulty in maintaining a stable typing rate. In this paper, a system recognizing varying typing speeds is developed using an adaptive technique, the Least-Mean Square (LMS) algorithm. This system helps the disabled have a wide latitude and varying typing speeds in single-switch communication with the Morse-code.

  18. Temperature Control of Gas Chromatograph Based on Switched Delayed System Techniques

    Directory of Open Access Journals (Sweden)

    Xiao-Liang Wang

    2014-01-01

    Full Text Available We address the temperature control problem of the gas chromatograph. We model the temperature control system of the gas chromatograph into a switched delayed system and analyze the stability by common Lyapunov functional technique. The PI controller parameters can be given based on the proposed linear matrix inequalities (LMIs condition and the designed controller can make the temperature of gas chromatograph track the reference signal asymptotically. An experiment is given to illustrate the effectiveness of the stability criterion.

  19. The Need for System Scale Studies in Polar Regions

    Science.gov (United States)

    Hinzman, L. D.; Newman, D.

    2010-12-01

    The understanding of polar regions has advanced tremendously in the past two decades and much of the improved insight into our knowledge of environmental dynamics is due to multidisciplinary and interdisciplinary studies conducted by coordinated and collaborative research programs supported by national funding agencies. Although much remains to be learned with respect to component processes, many of the most urgent scientific, engineering and social questions can only be addressed through the broader perspective of studies on system scales in which these components are coupled to each other. Questions such as quantifying feedbacks, understanding the implications of sea ice loss to adjacent land areas or society, resolving future predictions of ecosystem evolution or population dynamics all require consideration of complex interactions and interdependent linkages among system components. Research that has identified physical controls on biological processes, or quantified impact/response relationships in physical and biological systems is critically important, and must be continued; however we are approaching a limitation in our ability to accurately project how the Arctic and the Antarctic will respond to a continued warming climate. Complex issues, such as developing accurate model algorithms of feedback processes require higher level synthesis of multiple component interactions. Several examples of important questions that may only be addressed through coupled complex systems analyses will be addressed.

  20. Application Criteria for Nine-Switch Power Conversion Systems with Improved Thermal Performance

    DEFF Research Database (Denmark)

    Qin, Zian; Loh, Poh Chiang; Blaabjerg, Frede

    2015-01-01

    -switch converter can at times be lower than the twelve-switch back-to-back converter. The scope of this paper is thus to identify application criteria for the nine-switch converter, which upon met, will lead to lower conduction and hence total losses. Loss distribution among switches of the nine-switch converter...

  1. Adaptive output-feedback control for switched stochastic uncertain nonlinear systems with time-varying delay.

    Science.gov (United States)

    Song, Zhibao; Zhai, Junyong

    2018-02-22

    This paper addresses the problem of adaptive output-feedback control for a class of switched stochastic time-delay nonlinear systems with uncertain output function, where both the control coefficients and time-varying delay are unknown. The drift and diffusion terms are subject to unknown homogeneous growth condition. By virtue of adding a power integrator technique, an adaptive output-feedback controller is designed to render that the closed-loop system is bounded in probability, and the state of switched stochastic nonlinear system can be globally regulated to the origin almost surely. A numerical example is provided to demonstrate the validity of the proposed control method. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

  2. Synchronized femtosecond laser pulse switching system based nano-patterning technology

    Science.gov (United States)

    Sohn, Ik-Bu; Choi, Hun-Kook; Yoo, Dongyoon; Noh, Young-Chul; Sung, Jae-Hee; Lee, Seong-Ku; Ahsan, Md. Shamim; Lee, Ho

    2017-07-01

    This paper demonstrates the design and development of a synchronized femtosecond laser pulse switching system and its applications in nano-patterning of transparent materials. Due to synchronization, we are able to control the location of each irradiated laser pulse in any kind of substrate. The control over the scanning speed and scanning step of the laser beam enables us to pattern periodic micro/nano-metric holes, voids, and/or lines in various materials. Using the synchronized laser system, we pattern synchronized nano-holes on the surface of and inside various transparent materials including fused silica glass and polymethyl methacrylate to replicate any image or pattern on the surface of or inside (transparent) materials. We also investigate the application areas of the proposed synchronized femtosecond laser pulse switching system in a diverse field of science and technology, especially in optical memory, color marking, and synchronized micro/nano-scale patterning of materials.

  3. Robust Stability and H∞ Control of Uncertain Piecewise Linear Switched Systems with Filippov Solutions

    DEFF Research Database (Denmark)

    Ahmadi, Mohamadreza; Mojallali, Hamed; Wisniewski, Rafal

    2012-01-01

    This paper addresses the robust stability and control problem of uncertain piecewise linear switched systems where, instead of the conventional Carathe ́odory solutions, we allow for Filippov solutions. In other words, in contrast to the previous studies, solutions with infinite switching in fini...... algorithm is proposed to surmount the aforementioned matrix inequality conditions....... time along the facets and on faces of arbitrary dimensions are also taken into account. Firstly, based on earlier results, the stability problem of piecewise linear systems with Filippov solutions is translated into a number of linear matrix inequality feasibility tests. Subsequently, a set of matrix...... inequalities are brought forward, which determines the asymptotic stability of the Filippov solutions of a given uncertain piecewise linear system. Afterwards, bilinear matrix inequality conditions for synthesizing a robust controller with a guaranteed H∞ per- formance are formulated. Finally, a V-K iteration...

  4. Fuel switching in Harare: An almost ideal demand system approach

    International Nuclear Information System (INIS)

    Chambwera, Muyeye; Folmer, Henk

    2007-01-01

    In urban areas several energy choices are available and the amount of (a given type of) fuel consumed is based on complex household decision processes. This paper analyzes urban fuel (particularly firewood) demand in an energy mix context by means of an Almost Ideal Demand System based on a survey carried out among 500 households in Harare in 2003. Using a multi-stage budgeting approach, the model estimates the share of energy in total household expenditure and the shares of firewood, electricity and kerosene in total energy expenditure. Using the model results simulations show that the main policy handles to reduce the demand for firewood and to mitigate environmental degradation such as deforestation include decreasing prices of alternative fuels, notably kerosene. Moreover, in the long run sound economic policy will positively impact on the energy budget whereas education and the degree of electrification will contribute to a reduction of the use of firewood

  5. On multiuser switched diversity transmission for spectrum sharing systems

    KAUST Repository

    Qaraqe, Marwa

    2012-01-01

    In this paper, we develop multiuser access schemes for spectrum sharing systems whereby secondary users share the spectrum with primary users. In particular, we devise two schemes for selecting the user among those that satisfy the interference constraints and achieve an acceptable signal-to-noise ratio (SNR) level. The first scheme selects the user with the maximum SNR at the receiver, whereas in the second scheme the users are scanned in a sequential manner until an acceptable user is found. In addition, we consider two power adaptive settings. In the on/off power adaptive setting, the users transmit based on whether the interference constraint is met or not while in the full power adaptive setting, the users vary their transmission power to satisfy the interference constraint. Finally, we present numerical results of our proposed algorithms where we show the trade-off between the average spectral efficiency and average feedback load of both schemes. © 2012 ICST.

  6. On the use of polar coordinate system in the projective graphic drawings

    Directory of Open Access Journals (Sweden)

    Ivashchenko Andrey Viktorovich

    2016-11-01

    Full Text Available Projective graphics is a polyhedra simulation method, which is based on the use of trace diagrams of initial polyhedron. Previously developed computer software allows using Cartesian coordinates. In some cases it is advisable to use polar coordinate system for description of projective graphics drawings. Using the example of icosahedron the authors analyzed the advantages of using projective graphics drawings in the polar coordinate system. The transition to the polar coordinate system is a tool that allows using certain patterns of projective graphics drawings in the process of calculation. When using polar coordinate system the search of Polar correspondence for the directs is simplified. In order to analyze the two lines in the polar coordinate system it is enough to compare the corresponding coefficients of the equations of these lines. The authors consider a diagram of the icosahedron in polar coordinates, and a corresponding fragment of calculation program in the Mathematica system. Some examples of forming based on icosahedrons are offered. Optimization of computer programs using polar coordinate system will simplifies the calculations of projective graphics drawings, accelerates the process of constructing three-dimensional models, which expand the possibilities of selecting original solutions. Finally, the authors conclude that it is appropriate to use the polar coordinate system only in the construction of projective graphics diagrams of the planes system having rich symmetry. All Platonic and Archimedean solids, Catalan solid possess this property.

  7. Power adaptation for joint switched diversity and adaptive modulation schemes in spectrum sharing systems

    KAUST Repository

    Bouida, Zied

    2012-09-01

    Under the scenario of an underlay cognitive radio network, we propose in this paper an adaptive scheme using transmit power adaptation, switched transmit diversity, and adaptive modulation in order to improve the performance of existing switching efficient schemes (SES) and bandwidth efficient schemes (BES). Taking advantage of the channel reciprocity principle, we assume that the channel state information (CSI) of the interference link is available to the secondary transmitter. This information is then used by the secondary transmitter to adapt its transmit power, modulation constellation size, and used transmit branch. The goal of this joint adaptation is to minimize the average number of switched branches and the average system delay given the fading channel conditions, the required error rate performance, and a peak interference constraint to the primary receiver. We analyze the proposed scheme in terms of the average number of branch switching, average delay, and we provide a closed-form expression of the average bit error rate (BER). We demonstrate through numerical examples that the proposed scheme provides a compromise between the SES and the BES schemes. © 2012 IEEE.

  8. A digital receiver with fast frequency- and gain-switching capabilities for MRI systems.

    Science.gov (United States)

    Ruipeng, Ning; Yidong, Dai; Guang, Yang; Gengying, Li

    2009-12-01

    In this article, two issues pertaining to MRI digital receivers are addressed. One is the maintenance of phase coherence between the transmitter and the receiver-an effective solution is proposed, in which the receiver frequency is switched synchronously with the transmitter frequency. The other is the dynamic range of the receiver-gain-switching technique is utilized to improve the dynamic range. To meet the hardware requirements of these solutions, a digital receiver with fast frequency- and gain-switching capabilities was implemented. The primary components of the proposed digital receiver are a variable gain amplifier, a high-speed analog-to-digital converter and a single-chip digital receiver core. The radio-frequency magnetic resonance signal is directly sampled by the analog-to-digital converter and processed in the digital receiver core. By pre-storing the receiver waveform in the on-board SDRAM, the frequency and gain of the receiver may be switched very quickly. The performance of the proposed digital receiver is verified by embedding it in an imaging spectrometer. It is then demonstrated by conducting experiments on a home-built 0.3-T magnetic resonance imaging system. The results show that the phase coherence between the transmitter and the receiver and the dynamic range of the receiver are greatly improved. Consequently, the proposed digital receiver may be useful for obtaining multiple-slice two-dimensional magnetic resonance images with very high resolution.

  9. Theoretical and experimental studies of polarization fluctuations over atmospheric turbulent channels for wireless optical communication systems.

    Science.gov (United States)

    Zhang, Jiankun; Ding, Shengli; Zhai, Huili; Dang, Anhong

    2014-12-29

    In wireless optical communications (WOC), polarization multiplexing systems and coherent polarization systems have excellent performance and wide applications, while its state of polarization affected by atmospheric turbulence is not clearly understood. This paper focuses on the polarization fluctuations caused by atmospheric turbulence in a WOC link. Firstly, the relationship between the polarization fluctuations and the index of refraction structure parameter is introduced and the distribution of received polarization angle is obtained through theoretical derivations. Then, turbulent conditions are adjusted and measured elaborately in a wide range of scintillation indexes (SI). As a result, the root-mean-square (RMS) variation and probability distribution function (PDF) of polarization angle conforms closely to that of theoretical model.

  10. Adaptive Backstepping-Based Neural Tracking Control for MIMO Nonlinear Switched Systems Subject to Input Delays.

    Science.gov (United States)

    Niu, Ben; Li, Lu

    2017-04-17

    This brief proposes a new neural-network (NN)-based adaptive output tracking control scheme for a class of disturbed multiple-input multiple-output uncertain nonlinear switched systems with input delays. By combining the universal approximation ability of radial basis function NNs and adaptive backstepping recursive design with an improved multiple Lyapunov function (MLF) scheme, a novel adaptive neural output tracking controller design method is presented for the switched system. The feature of the developed design is that different coordinate transformations are adopted to overcome the conservativeness caused by adopting a common coordinate transformation for all subsystems. It is shown that all the variables of the resulting closed-loop system are semiglobally uniformly ultimately bounded under a class of switching signals in the presence of MLF and that the system output can follow the desired reference signal. To demonstrate the practicability of the obtained result, an adaptive neural output tracking controller is designed for a mass-spring-damper system.

  11. System-Level Demonstration of a Dynamically Reconfigured Burst-Mode Link Using a Nanosecond Si-Photonic Switch

    DEFF Research Database (Denmark)

    Forencich, Alex; Kamchevska, Valerija; Dupuis, Nicolas

    2018-01-01

    Using a novel FPGA-based network emulator, microsecond-scale packets with 12.5-20-Gb/s data are generated, routed through a nanosecond Si-photonic switch, and received in a fast-locking burst-mode receiver. Error-free links with <382-ns system-level switching are shown....

  12. Satellite Observation Systems for Polar Climate Change Studies

    Science.gov (United States)

    Comiso, Josefino C.

    2012-01-01

    The key observational tools for detecting large scale changes of various parameters in the polar regions have been satellite sensors. The sensors include passive and active satellite systems in the visible, infrared and microwave frequencies. The monitoring started with Tiros and Nimbus research satellites series in the 1970s but during the period, not much data was stored digitally because of limitations and cost of the needed storage systems. Continuous global data came about starting with the launch of ocean color, passive microwave, and thermal infrared sensors on board Nimbus-7 and Synthetic Aperture Radar, Radar Altimeter and Scatterometer on board SeaSat satellite both launched in 1978. The Nimbus-7 lasted longer than expected and provided about 9 years of useful data while SeaSat quit working after 3 months but provided very useful data that became the baseline for follow-up systems with similar capabilities. Over the years, many new sensors were launched, some from Japan Aeronautics and Space Agency (JAXA), some from the European Space Agency (ESA) and more recently, from RuSSia, China, Korea, Canada and India. For polar studies, among the most useful sensors has been the passive microwave sensor which provides day/night and almost all weather observation of the surface. The sensor provide sea surface temperature, precipitation, wind, water vapor and sea ice concentration data that have been very useful in monitoring the climate of the region. More than 30 years of such data are now available, starting with the Scanning Multichannel Microwave Radiometer (SMMR) on board the Nimbus-7, the Special Scanning Microwave/Imager (SSM/I) on board a Defense Meteorological Satellite Program (DMSP) and the Advanced Microwave Scanning Radiometer on board the EOS/ Aqua satellite. The techniques that have been developed to derive geophysical parameters from data provided by these and other sensors and associated instrumental and algorithm errors and validation techniques

  13. Output Tracking Control of Switched Hybrid Systems: A Fliess Functional Expansion Approach

    Directory of Open Access Journals (Sweden)

    Fenghua He

    2013-01-01

    Full Text Available The output tracking problem is investigated for a nonlinear affine system with multiple modes of continuous control inputs. We convert the family of nonlinear affine systems under consideration into a switched hybrid system by introducing a multiple-valued logic variable. The Fliess functional expansion is adopted to express the input and output relationship of the switched hybrid system. The optimal switching control is determined for a multiple-step output tracking performance index. The proposed approach is applied to a multitarget tracking problem for a flight vehicle aiming for one real target with several decoys flying around it in the terminal guidance course. These decoys appear as apparent targets and have to be distinguished with the approaching of the flight vehicle. The guidance problem of one flight vehicle versus multiple apparent targets should be considered if no large miss distance might be caused due to the limitation of the flight vehicle maneuverability. The target orientation at each time interval is determined. Simulation results show the effectiveness of the proposed method.

  14. Development and Testing of a Variable Conductance Thermal Acquisition, Transport, and Switching System

    Science.gov (United States)

    Bugby, David C.; Farmer, Jeffery T.; Stouffer, Charles J.

    2013-01-01

    This paper describes the development and testing of a scalable thermal management architecture for instruments, subsystems, or systems that must operate in severe space environments with wide variations in sink temperature. The architecture involves a serial linkage of one or more hot-side variable conductance heat pipes (VCHPs) to one or more cold-side loop heat pipes (LHPs). The VCHPs provide wide area heat acquisition, limited distance thermal transport, modest against gravity pumping, concentrated LHP startup heating, and high switching ratio variable conductance operation. The LHPs provide localized heat acquisition, long distance thermal transport, significant against gravity pumping, and high switching ratio variable conductance operation. The single-VCHP, single-LHP system described herein was developed to maintain thermal control of a small robotic lunar lander throughout the lunar day-night thermal cycle. It is also applicable to other variable heat rejection space missions in severe environments. Operationally, despite a 60-70% gas blocked VCHP condenser during ON testing, the system was still able to provide 2-4 W/K ON conductance, 0.01 W/K OFF conductance, and an end-to-end switching ratio of 200-400. The paper provides a detailed analysis of VCHP condenser performance, which quantified the gas blockage situation. Future multi-VCHP/multi-LHP thermal management system concepts that provide power/transport length scalability are also discussed.

  15. Cellular ion channel-pump system modeling using switched stochastic differential equations.

    Science.gov (United States)

    Weaver, Jeffrey

    2007-01-01

    This paper identifies a multidimensional random switched process model of a neuron with embedded Ca++ ion channel and pump molecules adiabatically interacting based on local ion concentrations near the cell membrane. The model interprets known physiology of the channels as a coupled set of switched random processes and derives mechanical equations based on concentration flow among different states of the system. Rapid changes to channel barrier energies occurring during channel opening and closing transitions are modeled as another degree of freedom commutating the state of the overall system. An ion reservoir model is used as the primary tool to incorporate stochastic effects in channel operation. The complete model is analyzed numerically and then the equations are used to motivate a stochastic model for closed state dwell times. The result is compared against expected results of a leaky-integrator and known single-channel histograms.

  16. Design of a PC based Data Acquistion System for a Switched Reluctance Motor

    OpenAIRE

    Chandramouli, G.

    1988-01-01

    The Switched Reluctance Motors(SRM) have gained considerable attention in the variable speed drive market mainly due to the simple construction of the motor and the possibility of developing low cost converters and controllers. As these machines are under development, a considerable amount of research effort is directed to the experimental performance evaluation of the SRM drives. System efficiency, electromagnetic torque, torque ripple, output and losses are some of the requir...

  17. State exact reconstruction for switched linear systems via a super-twisting algorithm

    Science.gov (United States)

    Bejarano, Francisco J.; Fridman, Leonid

    2011-05-01

    This article discusses the problem of state reconstruction synthesis for switched linear systems. Based only on the continuous output information, an observer is proposed ensuring the reconstruction of the entire state (continuous and discrete) in finite time. For the observer design an exact sliding mode differentiator is used, which allows the finite time convergence of the observer trajectories to the actual trajectories. The design scheme includes both cases: zero control input and nonzero control input. Simulations illustrate the effectiveness of the proposed observer.

  18. Phase-controlled all-optical switching based on coherent population oscillation in a two-level system

    International Nuclear Information System (INIS)

    Liao, Ping; Yu, Song; Luo, Bin; Shen, Jing; Gu, Wanyi; Guo, Hong

    2011-01-01

    We theoretically propose a scheme of phase-controlled all-optical switching due to the effect of degenerate four-wave mixing (FWM) and coherent population oscillation (CPO) in a two-level system driven by a strong coupling field and two weak symmetrically detuned fields. The results show that the phase of the FWM field can be utilized to switch between constructive and destructive interference, which can lead to the transmission or attenuation of the probe field and thus switch the field on or off. We also find the intensity of the coupling field and the propagation distance have great influence on the performance of the switching. In our scheme, due to the quick response in semiconductor systems, a fast all-optical switching can be realized at low light level. -- Highlights: ► We study a new all-optical switching based on coherent population oscillation. ► The phase of the FWM field can be utilized to switch the probe field on or off. ► A fast and low-light-level switching can be realized in semiconductors.

  19. Theory and analysis of a large field polarization imaging system with obliquely incident light.

    Science.gov (United States)

    Lu, Xiaotian; Jin, Weiqi; Li, Li; Wang, Xia; Qiu, Su; Liu, Jing

    2018-02-05

    Polarization imaging technology provides information about not only the irradiance of a target but also the polarization degree and angle of polarization, which indicates extensive application potential. However, polarization imaging theory is based on paraxial optics. When a beam of obliquely incident light passes an analyser, the direction of light propagation is not perpendicular to the surface of the analyser and the applicability of the traditional paraxial optical polarization imaging theory is challenged. This paper investigates a theoretical model of a polarization imaging system with obliquely incident light and establishes a polarization imaging transmission model with a large field of obliquely incident light. In an imaging experiment with an integrating sphere light source and rotatable polarizer, the polarization imaging transmission model is verified and analysed for two cases of natural light and linearly polarized light incidence. Although the results indicate that the theoretical model is consistent with the experimental results, the theoretical model distinctly differs from the traditional paraxial approximation model. The results prove the accuracy and necessity of the theoretical model and the theoretical guiding significance for theoretical and systematic research of large field polarization imaging.

  20. Misfire detection based on switched state observer of hybrid system in internal combustion engine

    Science.gov (United States)

    Zhang, Yu; Zhou, Tonglin; Zheng, Taixiong; Han, Weimin; Tan, Rui; Wang, Yanjun

    2017-04-01

    This paper proposes a novel switched state observer of hybrid system using Luenberger sliding mode observer to estimate crankshaft angular acceleration which is further applied to detect misfire fault. The output error of hybrid system of internal combustion engine (engine speed) and the designed observer (estimated speed) is taken as input of observer to estimate crankshaft acceleration. Convergence of hybrid system is proven through Lyapunov stability theory. The experimental results show that the presented estimated technique has a higher accuracy and can be effectively used to misfire detection compared with reduced-order observer and sliding mode observer.

  1. Polar On-Line Acquisition Relay and Transmission System (POLARATS)

    Energy Technology Data Exchange (ETDEWEB)

    Yuracko, K.

    2004-07-15

    POLARATS (Polar On-Line Acquisition Relay And Transmission System) is being developed by YAHSGS LLC (YAHSGS) and Oak Ridge National Laboratory (ORNL) to provide remote, unattended monitoring of environmental parameters under harsh environmental conditions. In particular, instrumental design and engineering is oriented towards protection of human health in the Arctic, and with the additional goal of advancing Arctic education and research. POLARATS will obtain and transmit environmental data from hardened monitoring devices deployed in locations important to understanding atmospheric and aquatic pollutant migration as it is biomagnified in Arctic food chains. An Internet- and personal computer (PC)-based educational module will provide real time sensor data, on-line educational content, and will be integrated with workbooks and textbooks for use in middle and high school science programs. The educational elements of POLARATS include an Internet-based educational module that will instruct students in the use of the data and how those data fit into changing Arctic environments and food chains. POLARATS will: (1) Enable students, members of the community, and scientific researchers to monitor local environmental conditions in real time over the Internet; and (2) Provide additional educational benefits through integration with middle- and high-school science curricula. Information will be relayed from POLARATS devices to classrooms and libraries along with custom-designed POLARATS teaching materials that will be integrated into existing curricula to enhance the educational benefits realized from the information obtained.

  2. Adding a Mission to the Joint Polar Satellite System (JPSS) Common Ground System (CGS)

    Science.gov (United States)

    Miller, S. W.; Grant, K. D.; Jamilkowski, M. L.

    2014-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). The Joint Polar Satellite System will replace the afternoon orbit component and ground processing system of the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA. The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological and geophysical observations of the Earth. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS). Developed and maintained by Raytheon Intelligence, Information and Services (IIS), the CGS is a multi-mission enterprise system serving NOAA, NASA and their national and international partners. The CGS provides a wide range of support to a number of missions: 1) Command and control and mission management for the Suomi National Polar-orbiting Partnership (S-NPP) mission today, expanding this support to the JPSS-1 satellite and the Polar Free Flyer mission in 2017 2) Data acquisition via a Polar Receptor Network (PRN) for S-NPP, the Japan Aerospace Exploration Agency's (JAXA) Global Change Observation Mission - Water (GCOM-W1), POES, and the Defense Meteorological Satellite Program (DMSP) and Coriolis/WindSat for the Department of Defense (DoD) 3) Data routing over a global fiber Wide Area Network (WAN) for S-NPP, JPSS-1, Polar Free Flyer, GCOM-W1, POES, DMSP, Coriolis/WindSat, the NASA Space Communications and Navigation (SCaN, which includes several Earth Observing System [EOS] missions), MetOp for the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and the National Science Foundation (NSF) 4) Environmental data processing and distribution for S-NPP, GCOM-W1 and JPSS-1 With this established infrastructure and existing suite of missions, the CGS

  3. Energy extraction system using dual-capacitor switching for quench protection of HTS magnet

    International Nuclear Information System (INIS)

    Chi, Yo Jong; Song, Seung Hyun; Jeon, Hae Ryong; Ko, Tae Kuk; Lee, Woo Seung; Kang, Hyoung Ku

    2017-01-01

    The superconducting magnets have a large inductance as well as high operating current. Therefore, mega-joule scale energy can be stored in the magnet. The energy stored in the magnet is sufficient to damage the magnet when a quench occurs. Quench heater and dump resistor can be used to protect the magnet. However, using quench heater to create quench resistors through heat transfer can be slower than instantly switching resistors. Also, electrical short, overheating and breakdown can occur due to quench heater. Moreover, the number of dump resistor should be limited to avoid large terminal voltage. Therefore, in this paper, we propose a quench protection method for extracting the energy stored in a magnet by charging and discharging energy through a capacitor switching without increasing resistance. The simulation results show that the proposed system has a faster current decay within the allowable voltage level

  4. Energy extraction system using dual-capacitor switching for quench protection of HTS magnet

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Yo Jong; Song, Seung Hyun; Jeon, Hae Ryong; Ko, Tae Kuk [Yonsei University, Seoul (Korea, Republic of); Lee, Woo Seung [JH ENGINEERING CO., LTD., Anyang (Korea, Republic of); Kang, Hyoung Ku [Korea National University of Transportation, Chungju (Korea, Republic of)

    2017-09-15

    The superconducting magnets have a large inductance as well as high operating current. Therefore, mega-joule scale energy can be stored in the magnet. The energy stored in the magnet is sufficient to damage the magnet when a quench occurs. Quench heater and dump resistor can be used to protect the magnet. However, using quench heater to create quench resistors through heat transfer can be slower than instantly switching resistors. Also, electrical short, overheating and breakdown can occur due to quench heater. Moreover, the number of dump resistor should be limited to avoid large terminal voltage. Therefore, in this paper, we propose a quench protection method for extracting the energy stored in a magnet by charging and discharging energy through a capacitor switching without increasing resistance. The simulation results show that the proposed system has a faster current decay within the allowable voltage level.

  5. NATO Advanced Research Workshop on Optical Switching in Low-Dimensional Systems

    CERN Document Server

    Bányai, L

    1989-01-01

    This book contains all the papers presented at the NATO workshop on "Optical Switching in Low Dimensional Systems" held in Marbella, Spain from October 6th to 8th, 1988. Optical switching is a basic function for optical data processing, which is of technological interest because of its potential parallelism and its potential speed. Semiconductors which exhibit resonance enhanced optical nonlinearities in the frequency range close to the band edge are the most intensively studied materials for optical bistability and fast gate operation. Modern crystal growth techniques, particularly molecular beam epitaxy, allow the manufacture of semiconductor microstructures such as quantum wells, quantum wires and quantum dots in which the electrons are only free to move in two, one or zero dimensions, of the optically excited electron-hole pairs in these low respectively. The spatial confinement dimensional structures gives rise to an enhancement of the excitonic nonlinearities. Furthermore, the variations of the microstr...

  6. Joint Polar Satellite System (JPSS) Common Ground System (CGS) Performance for Suomi NPP

    Science.gov (United States)

    Idol, J.; Grant, K. D.; Waas, W.; Austin, J.

    2012-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). JPSS will contribute the afternoon orbit component and ground processing system of the restructured National Polar-orbiting Operational Environmental Satellite System (NPOESS). As such, the Joint Polar Satellite System replaces the current Polar-orbiting Operational Environmental Satellites (POES) managed by the National Oceanic and Atmospheric Administration and the ground processing component of both Polar-orbiting Operational Environmental Satellites and the Defense Meteorological Satellite Program (DMSP) replacement, previously known as the Defense Weather Satellite System (DWSS), managed by the Department of Defense (DoD). The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS), and consists of a Command, Control, and Communications Segment (C3S) and an Interface Data Processing Segment (IDPS). Both segments are developed by Raytheon Intelligence and Information Systems (IIS). The C3S currently flies the Suomi National Polar Partnership (Suomi NPP) satellite and transfers mission data from Suomi NPP and between the ground facilities. The IDPS processes Suomi NPP satellite data to provide Environmental Data Records (EDRs) to NOAA and DoD processing centers operated by the United States government. When the JPSS-1 satellite is launched in early 2017, the responsibilities of the C3S and the IDPS will be expanded to support both Suomi NPP and JPSS-1. The Suomi NPP launched on October 28, 2011. Launch was followed by a phase of sensor activation, and full volume data traffic is now flowing from the

  7. The Kaleidoscope switch-a new concept for implementation of a large and fault tolerant ATM switch system

    DEFF Research Database (Denmark)

    Dittmann, Lars

    1997-01-01

    This paper describes a new concept for implementing a large switch network based on smaller modules. The concept is based an an alternative self-routing structure that due to a point symmetry allows the bit in the routing tag to be processed in a random order. Among others this property provides...... an inherent fault protection and allows a simple implementation of broadcast and multicast. The concept has been implemented as a small prototype, that currently is used in a national experimental ATM network in Denmark...

  8. A progress report of the switch-based data acquisition system prototype project and the application of switches from industry to high-energy physics event building

    International Nuclear Information System (INIS)

    Barsotti, E.; Booth, A.; Bowden, M.; Swoboda, C.

    1990-01-01

    A prototype of a data acquisition system based on a new scalable, highly-parallel, open-system architecture is being developed at Fermilab. The major component of the new architecture, the parallel event builder, is based on a telecommunications industry technique used in the implementation of switching systems, a barrel-shift switch. The architecture is scalable both in the expandability of the number of input channels and in the throughput of the system. Because of its scalability, the system is well suited for low to high-rate experiments, test beams and all SSC detectors. The architecture is open in that as new technologies are developed and made into commercial products (e.g., arrays of processors and workstations and standard data links), these new products can be easily integrated into the system with minimal system modifications and no modifications to the system's basic architecture. Scalability and openness should guarantee that the data acquisition system does not become obsolete during the lifetime of the experiment. The paper first gives a description of the architecture and the prototype project and then details both the prototype project's software and hardware status including details of some architecture simulation studies. Suggestions for future R and D work on the new data acquisition system architecture are then described. The paper concludes by examining interconnection networks from industry and their application to event building and to other areas of high-energy physics data acquisition systems

  9. ICEPOD: A Multidisciplinary Imaging System for Application in Polar Regions

    Science.gov (United States)

    Zappa, C. J.; Frearson, N.

    2012-12-01

    The ICEPOD program is in it's third year of a five-year effort to develop a modular airborne ice imaging system mounted on New York Air National Guard (NYANG) LC-130 aircraft to map the surface and sub-surface topography of ice sheets, ice streams, outlet glaciers, ice-shelves and sea-ice for the NSF Major Research Instrumentation program. The project is funded by the American Recovery and Reinvestment Act. The fundamental goal of the ICEPOD program is to develop an instrumentation package that can capture the dynamics of the changing polar regions, focusing on ice, ice margins and ocean systems. To achieve this the instruments include a Scanning Lidar for precise measurements of the ice surface, Stereo photogrammetry from both a high sensitivity Infra-Red camera and a high resolution Visible Imaging camera to document the ice surface and temperature, sea-ice thickness imaging radar and a deep ice radar used to study interior and basal processes of glaciers, ice streams and ice-sheets. All instrument data sets will be time-tagged and geo-referenced by recording precision GPS satellite data. Aircraft orientation will be corrected using inertial measurement technology integrated into the pod. The vision is that this instrumentation will be operated both on routine flights of the NYANG in the polar regions, such as on missions between McMurdo and South Pole Station and on missions throughout Greenland, and on targeted science missions, from mapping sea ice in marginal ice zones and outlet glaciers such as those surrounding Ross Island or Greenland to quantifying large sub-glacial drainage systems in East Antarctica. Recent years have seen extreme changes in the Arctic. Particularly striking are changes within the Pacific sector of the Arctic Ocean, and especially in the seas north of the Alaskan coast. These areas have experienced record warming, reduced sea ice extent, and loss of ice in areas that had been ice-covered throughout human memory. Even the oldest and

  10. Investigating the Effect of Voltage-Switching on Low-Energy Task Scheduling in Hard Real-Time Systems

    National Research Council Canada - National Science Library

    Swaminathan, Vishnu; Chakrabarty, Krishnendu

    2005-01-01

    We investigate the effect of voltage-switching on task execution times and energy consumption for dual-speed hard real-time systems, and present a new approach for scheduling workloads containing periodic tasks...

  11. Design and implementation of microcontroller-based automatic sequence counting and switching system

    Directory of Open Access Journals (Sweden)

    Joshua ABOLARINWA

    2015-05-01

    Full Text Available Technological advancement and its influence on human being have been on the increase in recent time. Major areas of such influence, include monitoring and control activities. In order to keep track of human movement in and out of a particular building, there is the need for an automatic counting system. Therefore, in this paper, we present the design and implementation of a microcontroller-based automatic sequence counting and switching system. This system was designed and developed to save cost, time, energy, and to achieve seamless control in the event of switching on or off of electrical appliances within a building. Top-down modular design approach was used in conjunction with the versatility of microcontroller. The system is able to monitor, sequentially count the number of entry and exit of people through an entrance, afterwards, automatically control any electrical device connected to it. From various tests and measurements obtained, there are comparative benefits derived from the deployment of this system in terms of simplicity and accuracy over similar system that is not microcontroller-based. Therefore, this system can be deployed at commercial quantity with wide range of applications in homes, offices and other public places.

  12. Electric Drive Discrete Control System with Automatic Switching-On Reserve for Autonomous Settlement

    Directory of Open Access Journals (Sweden)

    Tsytovich L.I.

    2015-08-01

    Full Text Available The paper aims at developing of control the water supply system’s electric drives for autonomous settlement. The system provides automatic switching to a reserve control channel at refusal of any of the functional elements of the working regulation channel. Usually, such systems have a test signal generator and analyzer to system response to their impact. This result to an increase in the structural redundancy of the system, increase its cost and increase the requirements for the staff qualification. A specific feature of the system is its ability to self-diagnosis of catastrophic malfunctions of scheme’s components and an automatic switching-on the reserve control channels, without applying any test signals to the whole complex of electrical equipment. Multi-zone integrating regulator with frequency-pulse-width modulation realizes this technical solution. Control system structure and signals timing diagrams are presented. The construction principle of adaptive interval-code synchronization device with improved noise stability to control the voltage regulators serving for smooth start-up of asynchronous motors of water pumps is considered as well. Such solution allowing increase noise stability and reliability work of the system in conditions of limited power electrical networks, which is characteristic for the autonomous settlements. The article may be of interest to specialists in the field of power electronics and information electronics, electric drives and process automation.

  13. Development of a Next Generation Polar Multidisciplinary Airborne Imaging System for the International Polar Year 2007-2009

    Science.gov (United States)

    Bell, R. E.; Studinger, M.; Frearson, N.; Gogineni, P.; Braaten, D.

    2007-12-01

    Key elements in Earth's geodynamic and climatic systems, the polar regions are very sensitive to changing global environmental conditions such as increasing sea surface temperatures and have the potential to trigger significant global sea level rise as large volumes of ice melt. Locked within these icy regions are the records of past global climate shifts and novel ecosystems sealed from open interactions with the atmosphere for millions of years. While satellite missions can image the surface of the polar ice sheet, many of the key processes occur beneath the surface beyond the reach of space based observations. These crucial processes can only be efficiently examined through airborne instrumentation designed to study the vast expanses of snow and ice of the Antarctic continent, the sub-continent of Greenland and the surrounding oceans. The expanding logistical infrastructure associated with the International Polar Year (2007-2009) will enable the scientific community access major new portions of the polar regions. We are developing a state-of-the-art integrated multidisciplinary aerogeophysical instrumentation package for deployment during multi-national expeditions as part of the International Polar Year. This development project brings together the recent developments in radar sounding by the University of Kansas CReSIS (Center for Remote Sensing of Ice Sheets), that now permit the full characterization of the entire ice sheet and the major advances in the accuracy, resolution and efficiency of airborne gravity technology emerging from the private sector. Integrating the full spectrum of ice sheet imaging with high-resolution gravity and magnetics will enable the imaging of the previously invisible world of subglacial hydrodynamics.

  14. A Non-Hermitian Approach to Non-Linear Switching Dynamics in Coupled Cavity-Waveguide Systems

    DEFF Research Database (Denmark)

    Heuck, Mikkel; Kristensen, Philip Trøst; Mørk, Jesper

    2012-01-01

    We present a non-Hermitian perturbation theory employing quasi-normal modes to investigate non-linear all-optical switching dynamics in a photonic crystal coupled cavity-waveguide system and compare with finite-difference-time-domain simulations.......We present a non-Hermitian perturbation theory employing quasi-normal modes to investigate non-linear all-optical switching dynamics in a photonic crystal coupled cavity-waveguide system and compare with finite-difference-time-domain simulations....

  15. Development of laser marking system with electro-optic Q-switch

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Cheol Jung; Kim, Jeong Moog; Kim, Kwang Suk; Park, Seung Kyu; Baik, Sung Hoon

    1995-11-01

    We developed a high repetition electro-optic Q switch Nd:YAG laser and scan system for laser marking. We localized the scan mirrors and their mounts. We made the database for the optical properties of commercial flat-field lenses with our optics design software. We fabricated the detailed network between the galvanometer based beam scanning system and the laser generator. To accelerate the commercialization by the joint company, the training and transfer of technology were pursued in the joint participation by company researchers from the early stage. (author). 8 refs., 6 tabs., 27 figs.

  16. Development of laser marking system with electro-optic Q-switch

    International Nuclear Information System (INIS)

    Kim, Cheol Jung; Kim, Jeong Moog; Kim, Kwang Suk; Park, Seung Kyu; Baik, Sung Hoon.

    1995-11-01

    We developed a high repetition electro-optic Q switch Nd:YAG laser and scan system for laser marking. We localized the scan mirrors and their mounts. We made the database for the optical properties of commercial flat-field lenses with our optics design software. We fabricated the detailed network between the galvanometer based beam scanning system and the laser generator. To accelerate the commercialization by the joint company, the training and transfer of technology were pursued in the joint participation by company researchers from the early stage. (author). 8 refs., 6 tabs., 27 figs

  17. Phase inductance estimation for switched reluctance motor using adaptive neuro-fuzzy inference system

    International Nuclear Information System (INIS)

    Daldaban, Ferhat; Ustkoyuncu, Nurettin; Guney, Kerim

    2006-01-01

    A new method based on an adaptive neuro-fuzzy inference system (ANFIS) for estimating the phase inductance of switched reluctance motors (SRMs) is presented. The ANFIS has the advantages of expert knowledge of the fuzzy inference system and the learning capability of neural networks. A hybrid learning algorithm, which combines the least square method and the back propagation algorithm, is used to identify the parameters of the ANFIS. The rotor position and the phase current of the 6/4 pole SRM are used to predict the phase inductance. The phase inductance results predicted by the ANFIS are in excellent agreement with the results of the finite element method

  18. Robust Hinf control of uncertain switched systems defined on polyhedral sets with Filippov solutions

    DEFF Research Database (Denmark)

    Ahmadi, Mohamadreza; Mojallali, Hamed; Wisniewski, Rafal

    2012-01-01

    solutions. Subsequently, bilinear matrix inequality conditions for synthesizing a robust controller with a guaranteed Hinf performance are presented. Furthermore, these results has been generalized to the case of piecewise affine systems. Finally, a V–K iteration algorithm is proposed to deal...... with infinite switching in finite time along the facets and on faces of arbitrary dimensions are also taken into account. Firstly, established upon previous studies, a set of linear matrix inequalities are brought forward which determines the asymptotic stability of piecewise linear systems with Filippov...... with the aforementioned bilinear matrix inequalities. The validity of the proposed method is verified through the analysis of two simulation examples....

  19. Guaranteed Cost Finite-Time Control of Fractional-Order Positive Switched Systems

    Directory of Open Access Journals (Sweden)

    Leipo Liu

    2017-01-01

    Full Text Available The problem of guaranteed cost finite-time control of fractional-order positive switched systems (FOPSS is considered in this paper. Firstly, a new cost function is defined. Then, by constructing linear copositive Lyapunov functions and using the average dwell time (ADT approach, a state feedback controller and a static output feedback controller are constructed, respectively, and sufficient conditions are derived to guarantee that the corresponding closed-loop systems are guaranteed cost finite-time stable (GCFTS. Such conditions can be easily solved by linear programming. Finally, two examples are given to illustrate the effectiveness of the proposed method.

  20. Design of Filter for a Class of Switched Linear Neutral Systems

    Directory of Open Access Journals (Sweden)

    Caiyun Wu

    2013-01-01

    Full Text Available This paper is concerned with the filtering problem for a class of switched linear neutral systems with time-varying delays. The time-varying delays appear not only in the state but also in the state derivatives. Based on the average dwell time approach and the piecewise Lyapunov functional technique, sufficient conditions are proposed for the exponential stability of the filtering error dynamic system. Then, the corresponding solvability condition for a desired filter satisfying a weighted performance is established. All the conditions obtained are delay-dependent. Finally, two numerical examples are given to illustrate the effectiveness of the proposed theory.

  1. Guaranteed Cost Finite-Time Control of Discrete-Time Positive Impulsive Switched Systems

    Directory of Open Access Journals (Sweden)

    Leipo Liu

    2018-01-01

    Full Text Available This paper considers the guaranteed cost finite-time boundedness of discrete-time positive impulsive switched systems. Firstly, the definition of guaranteed cost finite-time boundedness is introduced. By using the multiple linear copositive Lyapunov function (MLCLF and average dwell time (ADT approach, a state feedback controller is designed and sufficient conditions are obtained to guarantee that the corresponding closed-loop system is guaranteed cost finite-time boundedness (GCFTB. Such conditions can be solved by linear programming. Finally, a numerical example is provided to show the effectiveness of the proposed method.

  2. 3-5 modulation and switching devices for optical systems applications

    Science.gov (United States)

    Singh, Jasprit; Bhattacharya, Pallab

    1995-04-01

    The thrust for this three year program has been to develop novel devices and systems applications for multiple quantum well based devices. We have investigated architectures based upon the quantum confined Stark effect (QCSE), a means by which excitonic resonances in a quantum well are electric field tuned to shift the peaked absorption spectrum of the material. The devices based upon this concept have been used, in the past, to realize switching structures employing the characteristic negative differential resistance available in PIN-MQW diodes under illumination. We have focuses, primarily on three schemes based upon the QCSE, to extend the utility of quantum well based devices. Firstly, we have developed, tested and optimized a novel tunable optical filter for wavelength selective applications. Secondly, we have demonstrated an MQW based scheme for optical pattern recognition which we have applied towards header recognition in a packet switching network environment. Thirdly, we have extended previous MQW based switching schemes to implement an optical read only memory (ROM) which can store two bits of information on a single sight, read by two different probe wavelengths of light.

  3. Switched diversity strategies for dual-hop amplify-and-forward relaying systems

    KAUST Repository

    Gaaloul, Fakhreddine

    2012-01-01

    This study investigates different receive single-branch switch-based diversity schemes for dual-hop amplify-and-forward relaying networks. Specifically, three receive processing algorithms are adopted, in which the receive branch is selected using the arbitrary selection algorithm, the switching algorithm, or the switching algorithm with post-examining best branch selection. The identification of the receive branch is carried out for two different system models. For the first model, a single-antenna relaying station is used in conjunction with a multiple-antenna transceiver, where the processing is performed independently of the first hop-fading conditions. The second model suggests the use of parallel deployment of single-antenna relays to transfer information from a multiple-antenna transmitter to a single-antenna receiver, where the active relaying station is determined based on the pre-combining end-to-end fading conditions. Performance comparisons for various transmission scenarios on the first hop are presented using new formulations for the statistics of the combined signal-to-noise ratio. Simulation results are also provided to validate the mathematical development and to verify the numerical computations. © 2012 The Institution of Engineering and Technology.

  4. Derivation of global vegetation biophysical parameters from EUMETSAT Polar System

    Science.gov (United States)

    García-Haro, Francisco Javier; Campos-Taberner, Manuel; Muñoz-Marí, Jordi; Laparra, Valero; Camacho, Fernando; Sánchez-Zapero, Jorge; Camps-Valls, Gustau

    2018-05-01

    This paper presents the algorithm developed in LSA-SAF (Satellite Application Facility for Land Surface Analysis) for the derivation of global vegetation parameters from the AVHRR (Advanced Very High Resolution Radiometer) sensor on board MetOp (Meteorological-Operational) satellites forming the EUMETSAT (European Organization for the Exploitation of Meteorological Satellites) Polar System (EPS). The suite of LSA-SAF EPS vegetation products includes the leaf area index (LAI), the fractional vegetation cover (FVC), and the fraction of absorbed photosynthetically active radiation (FAPAR). LAI, FAPAR, and FVC characterize the structure and the functioning of vegetation and are key parameters for a wide range of land-biosphere applications. The algorithm is based on a hybrid approach that blends the generalization capabilities offered by physical radiative transfer models with the accuracy and computational efficiency of machine learning methods. One major feature is the implementation of multi-output retrieval methods able to jointly and more consistently estimate all the biophysical parameters at the same time. We propose a multi-output Gaussian process regression (GPRmulti), which outperforms other considered methods over PROSAIL (coupling of PROSPECT and SAIL (Scattering by Arbitrary Inclined Leaves) radiative transfer models) EPS simulations. The global EPS products include uncertainty estimates taking into account the uncertainty captured by the retrieval method and input errors propagation. A sensitivity analysis is performed to assess several sources of uncertainties in retrievals and maximize the positive impact of modeling the noise in training simulations. The paper discusses initial validation studies and provides details about the characteristics and overall quality of the products, which can be of interest to assist the successful use of the data by a broad user's community. The consistent generation and distribution of the EPS vegetation products will

  5. A β-Ta system for current induced magnetic switching in the absence of external magnetic field

    Science.gov (United States)

    Chen, Wenzhe; Qian, Lijuan; Xiao, Gang

    2018-05-01

    Magnetic switching via Giant Spin Hall Effect (GSHE) has received great interest for its role in developing future spintronics logic or memory devices. In this work, a new material system (i.e. a transition metal sandwiched between two ferromagnetic layers) with interlayer exchange coupling is introduced to realize the deterministic field-free perpendicular magnetic switching. This system uses β-Ta, as the GSHE agent to generate a spin current and as the interlayer exchange coupling medium to generate an internal field. The critical switching current density at zero field is on the order of 106 A/cm2 due to the large spin Hall angle of β-Ta. The internal field, along with switching efficiency, depends strongly on the orthogonal magnetization states of two ferromagnetic coupling layers in this system.

  6. Modeling the Kelvin polarization force actuation of Micro- and Nanomechanical systems

    DEFF Research Database (Denmark)

    Schmid, Silvan; Hierold, C.; Boisen, Anja

    2010-01-01

    Polarization forces have become of high interest in micro- and nanomechanical systems. In this paper, an analytical model for a transduction scheme based on the Kelvin polarization force is presented. A dielectric beam is actuated by placing it over the gap of two coplanar electrodes. Finite...

  7. A novel supervisory control approach to switching operations for hybrid wind/diesel/battery/mains energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Gu, T. [Guilin Inst. of Electronic Technology, School of Computer Engineering, Guilin (China); Keerthipala, W.W.; Islam, S.M.; Nayar, C.V. [Curtin Univ. of Technology, School of Electrical and Computer Engineering, Perth (Australia)

    2000-12-01

    Hybrid energy systems, integrating renewable energy technologies with diesel generators, batteries and inverters, can provide 24 h grid quality power to remote communities. Work in the Centre for Renewable Energy Systems Technology Australia (CRESTA) has been carried out to develop a new hybrid/wind/diesel/battery/mains energy system. In the system, the switching operations of different modes play an important role in the proper running of the system. From the view of discrete event dynamic systems, a novel supervisory control approach for the switching operations of modes has been explored, in which the switching actions are defined as events, switching modes as states and events take the system from one state to another. The supervisory controller for a prototype of the hybrid wind/diesel/battery mains energy system has been designed and it has been simulated in PSCAD/EMTDC. The results reveal that this technique could facilitate the analysis and design of supervisory controllers for switching operations, particularly in the complicated hybrid energy systems. (Author)

  8. Party System Nationalization and Non-Uniform Vote Switching: Evidence from the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Linek, Lukáš; Lyons, Pat

    2010-01-01

    Roč. 46, č. 3 (2010), s. 375-399 ISSN 0038-0288 R&D Projects: GA ČR GA407/07/1395 Institutional research plan: CEZ:AV0Z70280505 Keywords : party system nationalisation * vote switching * ecological inference Subject RIV: AD - Politology ; Political Sciences Impact factor: 0.389, year: 2010 http://sreview.soc.cas.cz/uploads/c926357558e5bf662b62f54b2ba9293933f542c6_LinekLyonssoccas2010-3.pdf

  9. Simulation And Application of Fuzzy Logic Controlled Adjustable Speed Switched Reluctance Motor to Elevator System

    OpenAIRE

    DURSUN, Mahir; ÖZDEN, Semih

    2008-01-01

    Switched reluctance motors (SRM) can be use at adjustable speed driver and these motors have high start up torque, high efficiency and simple construction. In this study, an SRM which have 8/6 poles, four phase and 3,44 kW power was used to drive an elevator load. Carrying capacity of elevator is 320 kg. Two PIC 18F452 microcontrollers was used to manage an elevator system and motor control. Motor speed was controlled by PI (proportional+integral) and Fuzzy Logic Control (FLC) method. Elevato...

  10. An early warning system for inflation using Markov-Switching and logistic models approach

    OpenAIRE

    Katleho Makatjane; Diteboho Xaba

    2016-01-01

    With the adoption of the inflation targeting by the South African Reserve Bank (SARB) in 2000, the average inflation radically went down. Earlier 2000, the inflation rate was recorded at 8.8% that is January 1999; then a year later went down to 2.65%. What’s more, this paper builds up an early warning system (EWS) model for predicting the event of high inflation in South Africa. Periods of high and low inflation were distinguished by utilizing Markov-switching model. Utilizing the results of ...

  11. Hardware enabled performance counters with support for operating system context switching

    Science.gov (United States)

    Salapura, Valentina; Wisniewski, Robert W.

    2015-06-30

    A device for supporting hardware enabled performance counters with support for context switching include a plurality of performance counters operable to collect information associated with one or more computer system related activities, a first register operable to store a memory address, a second register operable to store a mode indication, and a state machine operable to read the second register and cause the plurality of performance counters to copy the information to memory area indicated by the memory address based on the mode indication.

  12. Gas chromatographical detection of oxygenated compounds in gasoline with a switching capillary column system

    Energy Technology Data Exchange (ETDEWEB)

    Winskowski, J.

    1988-01-01

    In this paper the separation and identification of oxygenated compounds in gasoline is described. Using a two-dimensional column system swtiching from a high polar TCEP-capillary column (1,2,3-Tris(cyanoethoxy)propan) to a non-polar column with a greater filmthickness of DMS (dimethylpolysiloxane) acetone and alcohols as well as further ketones and esters were separated from the hydrocarbon matrix without any difficulties. The analysis of the ethers is more difficult, especially in presence of olefinic compounds, mainly occuring in crack and pyrolysis gasoline, and can only be carried out if highly efficient capillary columns are applied. A test mixture is proposed which can be used to find out whether column systems are suitable for this purpose. The total amount of oxygen can be calculated from the single components after identification. (orig.)

  13. Cause Analysis of Pressure Plate Breakage of Valve Limit Switch in Turbine Bypass System of Nuclear Power Plant

    Science.gov (United States)

    Li, Nan; Wang, Ming chang; Guan, Jian jun; Li, Guo dong

    2017-07-01

    The limit switch plates of nuclear power plant unit 1 in the turbine bypass system valve are finding multiple fractures. On the basis of metallographic analysis and vibration analysis, the stress state of the pressure plate is simulated and calculated. The results show that there are some creases in the original plate of the limit switch and the installation error of the pressure plate is the main reason for the break.

  14. Switch: a planning tool for power systems with large shares of intermittent renewable energy.

    Science.gov (United States)

    Fripp, Matthias

    2012-06-05

    Wind and solar power are highly variable, so it is it unclear how large a role they can play in future power systems. This work introduces a new open-source electricity planning model--Switch--that identifies the least-cost strategy for using renewable and conventional generators and transmission in a large power system over a multidecade period. Switch includes an unprecedented amount of spatial and temporal detail, making it possible to address a new type of question about the optimal design and operation of power systems with large amounts of renewable power. A case study of California for 2012-2027 finds that there is no maximum possible penetration of wind and solar power--these resources could potentially be used to reduce emissions 90% or more below 1990 levels without reducing reliability or severely raising the cost of electricity. This work also finds that policies that encourage customers to shift electricity demand to times when renewable power is most abundant (e.g., well-timed charging of electric vehicles) could make it possible to achieve radical emission reductions at moderate costs.

  15. Distributed Leader-Following Finite-Time Consensus Control for Linear Multiagent Systems under Switching Topology

    Science.gov (United States)

    Xu, Xiaole; Chen, Shengyong

    2014-01-01

    This paper investigates the finite-time consensus problem of leader-following multiagent systems. The dynamical models for all following agents and the leader are assumed the same general form of linear system, and the interconnection topology among the agents is assumed to be switching and undirected. We mostly consider the continuous-time case. By assuming that the states of neighbouring agents are known to each agent, a sufficient condition is established for finite-time consensus via a neighbor-based state feedback protocol. While the states of neighbouring agents cannot be available and only the outputs of neighbouring agents can be accessed, the distributed observer-based consensus protocol is proposed for each following agent. A sufficient condition is provided in terms of linear matrix inequalities to design the observer-based consensus protocol, which makes the multiagent systems achieve finite-time consensus under switching topologies. Then, we discuss the counterparts for discrete-time case. Finally, we provide an illustrative example to show the effectiveness of the design approach. PMID:24883367

  16. Modeling and analysis of a robust thermal control system based on forced convection thermal switches

    Science.gov (United States)

    Williams, Andrew D.; Palo, Scott E.

    2006-05-01

    There is a critical need, not just in the Department of Defense (DOD) but the entire space industry, to reduce the development time and overall cost of satellite missions. To that end, the DOD is actively pursuing the capability to reduce the deployment time of a new system from years to weeks or even days. The goal is to provide the advantages space affords not just to the strategic planner but also to the battlefield commanders. One of the most challenging aspects of this problem is the satellite's thermal control system (TCS). Traditionally the TCS must be vigorously designed, analyzed, tested, and optimized from the ground up for every satellite mission. This "reinvention of the wheel" is costly and time intensive. The next generation satellite TCS must be modular and scalable in order to cover a wide range of applications, orbits, and mission requirements. To meet these requirements a robust thermal control system utilizing forced convection thermal switches was investigated. The problem was investigated in two separate stages. The first focused on the overall design of the bus. The second stage focused on the overarching bus architecture and the design impacts of employing a thermal switch based TCS design. For the hot case, the fan provided additional cooling to increase the heat transfer rate of the subsystem. During the cold case, the result was a significant reduction in survival heater power.

  17. [Influence of water source switching on water quality in drinking water distribution system].

    Science.gov (United States)

    Wang, Yang; Niu, Zhang-bin; Zhang, Xiao-jian; Chen, Chao; He, Wen-jie; Han, Hong-da

    2007-10-01

    This study investigates the regularity of the change on the physical and chemical water qualities in the distribution system during the process of water source switching in A city. Due to the water source switching, the water quality is chemical-astable. Because of the differences between the two water sources, pH reduced from 7.54 to 7.18, alkalinity reduced from 188 mg x L(-1) to 117 mg x L(-1), chloride (Cl(-)) reduced from 310 mg x L(-1) to 132 mg x L(-1), conductance reduced from 0.176 S x m(-1) to 0.087 S x m(-1) and the ions of calcium and magnesium reduced to 15 mg x L(-1) and 11 mg x L(-1) respectively. Residual chlorine changed while the increase of the chlorine demand and the water quantity decreasing at night, and the changes of pH, alkalinity and residual chlorine brought the iron increased to 0.4 mg x L(-1) at the tiptop, which was over the standard. The influence of the change of the water parameters on the water chemical-stability in the drinking water distribution system is analyzed, and the controlling countermeasure is advanced: increasing pH, using phosphate and enhancing the quality of the water in distribution system especially the residual chlorine.

  18. Stability Analysis and H∞ Model Reduction for Switched Discrete-Time Time-Delay Systems

    Directory of Open Access Journals (Sweden)

    Zheng-Fan Liu

    2014-01-01

    Full Text Available This paper is concerned with the problem of exponential stability and H∞ model reduction of a class of switched discrete-time systems with state time-varying delay. Some subsystems can be unstable. Based on the average dwell time technique and Lyapunov-Krasovskii functional (LKF approach, sufficient conditions for exponential stability with H∞ performance of such systems are derived in terms of linear matrix inequalities (LMIs. For the high-order systems, sufficient conditions for the existence of reduced-order model are derived in terms of LMIs. Moreover, the error system is guaranteed to be exponentially stable and an H∞ error performance is guaranteed. Numerical examples are also given to demonstrate the effectiveness and reduced conservatism of the obtained results.

  19. Decoupling Control for Dual-Winding Bearingless Switched Reluctance Motor Based on Improved Inverse System Method

    Directory of Open Access Journals (Sweden)

    Zhiying Zhu

    2017-01-01

    Full Text Available Dual-winding bearingless switched reluctance motor (BSRM is a multivariable high-nonlinear system characterized by strong coupling, and it is not completely reversible. In this paper, a new decoupling control strategy based on improved inverse system method is proposed. Robust servo regulator is adopted for the decoupled plants to guarantee control performances and robustness. A phase dynamic compensation filter is also designed to improve system stability at high-speed. In order to explain the advantages of the proposed method, traditional methods are compared. The tracking and decoupling characteristics as well as disturbance rejection and robustness are deeply analyzed. Simulation and experiments results show that the decoupling control of dual-winding BSRM in both reversible and irreversible domains can be successfully resolved with the improved inverse system method. The stability and robustness problems induced by inverse controller can be effectively solved by introducing robust servo regulator and dynamic compensation filter.

  20. Numerical analysis of intrinsic bistability and chromatic switching in Tm3+ single-doped systems under photon avalanche pumping scheme

    International Nuclear Information System (INIS)

    Li Li; Zhang Xinlu; Chen Lixue

    2008-01-01

    In this paper, we predict and numerically demonstrate the intrinsic intensity bistability, spectra bistability and chromatic switching of visible-infrared emission in Tm 3+ single-doped systems that are pumped by the photon avalanche scheme at 648 nm. Based on the coupled rate equation theory, the evolutions of the populations at various Tm 3+ energy levels, emission spectra and fluorescence intensity versus pump excitation are numerically investigated in detail. The results show that intrinsic optical bistability (IOB) associated with emission spectra and luminescence intensity takes place in the vicinity of the avalanche threshold (∼10 kW cm -2 ). When the pump excitation rises above the switching threshold (∼17.5 kW cm -2 ), the chromatic switching between the infrared (1716 nm) and the visible blue (452/469 nm) spectra can be performed. Moreover, the influences of system parameters on IOB and the origin of chromatic switching are discussed. These unique characteristics of Tm 3+ -doped systems would lead to the new possibility of the development of pump-controlled all-solid-state luminescence switches and optical bistability switches.

  1. Performance Analysis of Multiradio Transmitter with Polar or Cartesian Architectures Associated with High Efficiency Switched-Mode Power Amplifiers (invited paper

    Directory of Open Access Journals (Sweden)

    F. Robert

    2010-12-01

    Full Text Available This paper deals with wireless multi-radio transmitter architectures operating in the frequency band of 800 MHz – 6 GHz. As a consequence of the constant evolution in the communication systems, mobile transmitters must be able to operate at different frequency bands and modes according to existing standards specifications. The concept of a unique multiradio architecture is an evolution of the multistandard transceiver characterized by a parallelization of circuits for each standard. Multi-radio concept optimizes surface and power consumption. Transmitter architectures using sampling techniques and baseband ΣΔ or PWM coding of signals before their amplification appear as good candidates for multiradio transmitters for several reasons. They allow using high efficiency power amplifiers such as switched-mode PAs. They are highly flexible and easy to integrate because of their digital nature. But when the transmitter efficiency is considered, many elements have to be taken into account: signal coding efficiency, PA efficiency, RF filter. This paper investigates the interest of these architectures for a multiradio transmitter able to support existing wireless communications standards between 800 MHz and 6 GHz. It evaluates and compares the different possible architectures for WiMAX and LTE standards in terms of signal quality and transmitter power efficiency.

  2. Joint Polar Satellite System (JPSS) Common Ground System (CGS) Overview and Architectural Tenets

    Science.gov (United States)

    Miller, S. W.; Grant, K. D.; Jamilkowski, M. L.

    2013-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). The Joint Polar Satellite System will replace the afternoon orbit component and ground processing system of the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA. The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological and geophysical observations of the Earth. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS). Developed and maintained by Raytheon Intelligence and Information Systems (IIS), the CGS is a multi-mission enterprise system serving NOAA, NASA and their national and international partners. The CGS provides a wide range of support to a number of missions: 1) Command and control and mission management for the Suomi National Polar Partnership (S-NPP) mission today, expanding this support to the JPSS-1 satellite and the Polar Free Flyer mission in 2017 2) Data acquisition via a Polar Receptor Network (PRN) for S-NPP, the Japan Aerospace Exploration Agency's (JAXA) Global Change Observation Mission - Water (GCOM-W1), POES, and the Defense Meteorological Satellite Program (DMSP) and Coriolis/WindSat for the Department of Defense (DoD) 3) Data routing over a global fiber Wide Area Network (WAN) for S-NPP, JPSS-1, Polar Free Flyer, GCOM-W1, POES, DMSP, Coriolis/WindSat, the NASA Space Communications and Navigation (SCaN, which includes several Earth Observing System [EOS] missions), MetOp for the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and the National Science Foundation (NSF) 4) Environmental data processing and distribution for S-NPP, GCOM-W1 and JPSS-1 The CGS architecture will receive a technology refresh in 2015 to satisfy several key

  3. Joint Polar Satellite System (JPSS) System Architecture: Suomi-NPP to the Future

    Science.gov (United States)

    Furgerson, J.; Layns, A.; Feeley, J. H.; Griffin, A.; Trumbower, G.

    2014-12-01

    The National Oceanic and Atmospheric Administration (NOAA) is acquiring the next-generation weather and environmental satellite system, named the Joint Polar Satellite System (JPSS). NOAA has overall responsibility for the system including funding and requirements while the National Aeronautics and Space Administration (NASA) serves as the acquisition and development agent. The Suomi National Polar-orbiting Partnership (S-NPP) satellite was launched on 28 October, 2011, and is a pathfinder for JPSS and provides continuity for the NASA Earth Observation System and the NOAA Polar-orbiting Operational Environmental Satellite (POES) system. S-NPP and the follow-on JPSS satellites will operate in the 1330 LTAN orbit. JPSS-1 is scheduled to launch in early 2017. NASA is developing the Common Ground System which will process JPSS data and has the flexibility to process data from other satellites. This poster will provide a top level status update of the program, as well as an overview of the JPSS system architecture. The space segment carries a suite of sensors that collect meteorological, oceanographic, and climatological observations of the earth and atmosphere. The system design allows centralized mission management and delivers high quality environmental products to military, civil and scientific users through a Command, Control, and Communication Segment (C3S). The data processing for S-NPP/JPSS is accomplished through an Interface Data Processing Segment (IDPS)/Field Terminal Segment (FTS) that processes S-NPP/JPSS satellite data to provide environmental data products to U.S. and international partners as well as remote terminal users throughout the world.

  4. Stability of Large Direct-Current Power Systems That Use Switching Converters and the Application of Switching Converters to the International Space Station

    Science.gov (United States)

    Manners, Bruce A.; Gholdston, E. W.; Karimi, K.; Lee, F. C.; Rajagopalan, J.; Panov, Y.

    1997-01-01

    As direct-current space power systems continue to grow in size, switching power converters are playing an ever larger role in power conditioning and control. When a large direct-current system that uses power converters of this type is being designed, special attention must be placed on the electrical stability of the system and of the individual loads on the system. The impedance specification approach for system stability was accomplished as a result of cooperative work of the International Space Station program team, which consists of the NASA Lewis Research Center, the Boeing Company, and Rocketdyne Division/Rockwell International. In addition, major contributions were provided by the Virginia Polytechnic Institute and State University working under a grant to NASA Lewis.

  5. The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jiquan [Stanford Univ., CA (United States)

    2008-12-01

    In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an element capable of switching hundreds of megawatts of RF power in a short time compared to the compressed pulse width is still an open problem. In this dissertation, we present a switch module composed of an active window based on the bulk effects in semiconductor, a circular waveguide three-port network and a movable short plane, with the capability to adjust the S-parameters before and after switching. The RF properties of the switch module were analyzed. We give the scaling laws of the multiple-element switch systems, which allow the expansion of the system to a higher power level. We present a novel overmoded design for the circular waveguide three-port network and the associated circular-to-rectangular mode-converter. We also detail the design and synthesis process of this novel mode-converter. We demonstrate an electrically controlled ultra-fast high power X-band RF active window built with PIN diodes on high resistivity silicon. The window is capable of handling multi-megawatt RF power and can switch in 2-300ns with a 1000A current driver. A low power active pulse compression experiment was carried out with the switch module and a 375ns resonant delay line, obtaining 8 times compression gain with a compression ratio of 20.

  6. Early Warning System in ASEAN Countries Using Capital Market Index Return: Modiied Markov Regime Switching Model

    Directory of Open Access Journals (Sweden)

    Imam Wahyudi

    2014-08-01

    Full Text Available Asia's  inancial  crisis  in  July  1997  affects  currency,  capital  market,  and  real  market throughout  Asian  countries.  Countries  in  southeast  region  (ASEAN,  including  Indonesia, Malaysia, Philippines, Singapore, and Thailand, are some of the countries where the crisis hit  the  most.  In  these  countries,  where  inancial  sectors  are  far  more  developed  than  real sectors  and  the  money  market  sectors,  most  of  the  economic  activities  are  conducted  in capital  market.  Movement  in  the  capital  market  could  be  a  proxy  to  describe  the  overall economic  situation  and  therefore  the  prediction  of  it  could  be  an  early  warning  system  of economic crises. This paper tries to investigate movement in ASEAN (Indonesia, Malaysia, Philippines,  Singapore,  and  Thailand  capital  market  to  build  an  early  warning  system from inancial sectors perspective. This paper will be very beneicial for the government to anticipate the forthcoming crisis. The insight of this paper is from Hamilton (1990 model of regime switching process in which he divide the movement of currency into two regimes, describe the switching transition based on Markov process and creates different model for each regimes. Differ from Hamilton, our research focuses on index return instead of currency to  model  the  regime  switching.  This  research  aimed  to  ind  the  probability  of  crisis  in  the future by combining the probability of switching and the probability distribution function of each  regime.  Probability  of  switching  is  estimated  by  categorizing  the  movement  in  index return  into  two  regimes  (negative  return  in  regime  1  and  positive  return  in  regime  2  then measuring  the  proportion  of  switching  to  regime  1  in  t  given  regime

  7. Control system of mutually coupled switched reluctance motor drive of mining machines in generator mode

    Science.gov (United States)

    Ivanov, A. S.; Kalanchin, I. Yu; Pugacheva, E. E.

    2017-09-01

    One of the first electric motors, based on the use of electromagnets, was a reluctance motor in the XIX century. Due to the complexities in the implementation of control system the development of switched reluctance electric machines was repeatedly initiated only in 1960 thanks to the development of computers and power electronic devices. The main feature of these machines is the capacity to work both in engine mode and in generator mode. Thanks to a simple and reliable design in which there is no winding of the rotor, commutator, permanent magnets, a reactive gate-inductor electric drive operating in the engine mode is actively being introduced into various areas such as car industry, production of household appliances, wind power engineering, as well as responsible production processes in the oil and mining industries. However, the existing shortcomings of switched reluctance electric machines, such as nonlinear pulsations of electromagnetic moment, the presence of three or four phase supply system and sensor of rotor position prevent wide distribution of this kind of electric machines.

  8. Performance analysis of switch-based multiuser scheduling schemes with adaptive modulation in spectrum sharing systems

    KAUST Repository

    Qaraqe, Marwa

    2014-04-01

    This paper focuses on the development of multiuser access schemes for spectrum sharing systems whereby secondary users are allowed to share the spectrum with primary users under the condition that the interference observed at the primary receiver is below a predetermined threshold. In particular, two scheduling schemes are proposed for selecting a user among those that satisfy the interference constraint and achieve an acceptable signal-to-noise ratio level. The first scheme focuses on optimizing the average spectral efficiency by selecting the user that reports the best channel quality. In order to alleviate the relatively high feedback required by the first scheme, a second scheme based on the concept of switched diversity is proposed, where the base station (BS) scans the secondary users in a sequential manner until a user whose channel quality is above an acceptable predetermined threshold is found. We develop expressions for the statistics of the signal-to-interference and noise ratio as well as the average spectral efficiency, average feedback load, and the delay at the secondary BS. We then present numerical results for the effect of the number of users and the interference constraint on the optimal switching threshold and the system performance and show that our analysis results are in perfect agreement with the numerical results. © 2014 John Wiley & Sons, Ltd.

  9. Beam Tracking in Switched-Beam Antenna System for V2V Communication

    Directory of Open Access Journals (Sweden)

    Settawit Poochaya

    2016-01-01

    Full Text Available This paper presents the proposed switched beam antenna system for V2V communication including optimum antenna half power beamwidth determination in urban road environments. SQP optimization method is selected for the computation of optimum antenna half power beamwidth. In addition, beam tracking algorithm is applied to guarantee the best beam selection with maximum RSSI. The results present the success of the proposed system with the increasing of V2V performance metrics. Also, V2V data dissemination via the proposed system introduces the enhancement of V2V link in terms of RSSI, PER, BER, Tsafe, and Rsafe. The results indicate the improvement of V2V link reliability. Consequently, the road safety is improved.

  10. System of polarization phasometry of polycrystalline blood plasma networks in mammary gland pathology diagnostics

    Science.gov (United States)

    Zabolotna, Natalia I.; Oliinychenko, Bogdan P.; Radchenko, Kostiantyn O.; Krasnoshchoka, Anastasiia K.; Shcherba, Olga K.

    2015-09-01

    The polarizing phase meter system of polycrystalline networks of human blood plasma which is used for the mammary gland pathology diagnostics was proposed in this paper. Increasing the accuracy of the phase value determination was achieved using a combination of low coherent source of radiation and circularly polarized probing of biological object. Thus, high informativity of polarizing phase meter system for the diagnosis of breast pathology using the phase mapping of the human blood plasma films were determined, thereafter statistical, correlational, fractal structure analysis of the obtained phase maps was carried out and the quantitative criterias of the phase diagnostics and differentiation of the breast pathological conditions were determined too.

  11. Joint Polar Satellite System (JPSS) Common Ground System (CGS) Current Technical Performance Measures

    Science.gov (United States)

    Cochran, S.; Panas, M.; Jamilkowski, M. L.; Miller, S. W.

    2015-12-01

    ABSTRACT The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). The Joint Polar Satellite System will replace the afternoon orbit component and ground processing system of the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA. The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological and geophysical observations of the Earth. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS). Developed and maintained by Raytheon Intelligence, Information and Services (IIS), the CGS is a multi-mission enterprise system serving NOAA, NASA and their national and international partners. The CGS has demonstrated its scalability and flexibility to incorporate multiple missions efficiently and with minimal cost, schedule and risk, while strengthening global partnerships in weather and environmental monitoring. The CGS architecture is being upgraded to Block 2.0 in 2015 to "operationalize" S-NPP, leverage lessons learned to date in multi-mission support, take advantage of more reliable and efficient technologies, and satisfy new requirements and constraints in the continually evolving budgetary environment. To ensure the CGS meets these needs, we have developed 49 Technical Performance Measures (TPMs) across 10 categories, such as data latency, operational availability and scalability. This paper will provide an overview of the CGS Block 2.0 architecture, with particular focus on the 10 TPM categories listed above. We will provide updates on how we ensure the deployed architecture meets these TPMs to satisfy our multi-mission objectives with the deployment of Block 2.0.

  12. Tri Band Dual Polarized Patch Antenna System For Next Generation Cellular Networks

    Directory of Open Access Journals (Sweden)

    Syed Daniyal Ali Shah

    2017-12-01

    Full Text Available In fifth generation networks much emphasis is given to reduce the handset and base station sizes while incorporating even more features for ubiquitous connectivity. Polarization diversity is one of the methods in which a single multi-polarized antenna brings the advantages of antenna diversity. The multiband handset antennas can be made dual-polarized for improved compensation of fading effects of propagation environment especially in terrestrial bands. This paper focuses on the outcomes of the development of a horizontal and vertical polarized patch antenna scheme that operates on 3 bands 900 MHz 1.8 GHz and 2.4 GHz. The antenna system is tested for gain directivity reflection loss polarization radiation pattern and other parameters. The results are published and found are found to satisfy the requirements of cellular and data communication networks in the specified bands.

  13. Quantitative infrared spectroscopy of lipids in solution: II. Novel polar solvent systems.

    Science.gov (United States)

    Schmid, P; Steiner, R N

    1975-01-01

    In the second part of this series, previous solvent limitations in infrared studies are discussed and novel polar solvent systems for the analysis of nonpolar and polar lipids described. Limitation of potassium bromide windows for infrared cells are discussed. The use of calcium fluoride cells with crude lipids is discussed. Problems related to hydrogen bonding of lipid solutes in various solvent systems are discussed as well as hydrogen-deuterium exchange in biologically important lipids.

  14. PPARγ ligands switched high fat diet-induced macrophage M2b polarization toward M2a thereby improving intestinal Candida elimination

    DEFF Research Database (Denmark)

    Lefèvre, Lise; Galès, Amandine; Olagnier, David

    2010-01-01

    of Candida albicans through the activation of alternative M2 macrophage polarization. Here, we evaluated the impact of high fat diet (HFD)-induced obesity and the effect of rosiglitazone (PPARγ ligand) or WY14643 (PPARα ligand) both on the phenotypic M1/M2 polarization of peritoneal and cecal tissue...

  15. Lidar Electro-Optic Beam Switch with a Liquid Crystal Variable Retarder

    Science.gov (United States)

    Baer, James

    2012-01-01

    A document discusses a liquid crystal variable retarder, an electro-optic element that changes the polarization of an optical beam in response to a low-voltage electronic signal. This device can be fabricated so that the element creates, among other states, a half-wave of retardance that can be reduced to a very small retardance. When aligned to a polarized source, this can act to rotate the polarization by 90 in one state, but generate no rotation in the other state. If the beam is then incident on a polarization beam splitter, it will efficiently switch from one path to the other when the voltage is applied. The laser beam switching system has no moving parts, improving reliability over mechanical switching. It is low cost, tolerant of high laser power density, and needs only simple drive electronics, minimizing the required system resources.

  16. Theoretical and Experimental Studies of a Switched Inertance Hydraulic System in a Four-Port High-Speed Switching Valve Configuration

    Directory of Open Access Journals (Sweden)

    Min Pan

    2017-06-01

    Full Text Available The switched inertance hydraulic system (SIHS is a novel high-bandwidth and energy-efficient digital device which can adjust or control flow and pressure by a means that does not rely on throttling the flow and dissipation of power. An SIHS can provide an efficient step-up or step-down of pressure or flow rate by using a digital control signal. In this article, analytical models of an SIHS in a four-port high-speed switching valve configuration are proposed, and the system dynamics and performance are investigated theoretically and experimentally. The flow responses, system characteristics, and power consumption can be predicted effectively and accurately by using the proposed models, which were validated by comparing with experiments and with numerical simulation. The four-port configuration is compared with the three-port configuration, and it is concluded that the former one is less efficient for valves of the same size, but provides a bi-direction control capability. As bi-direction control is a common requirement, this constitutes an important contribution to the development of efficient digital hydraulics.

  17. Flexible, Polarization-Diverse UWB Antennas for Implantable Neural Recording Systems.

    Science.gov (United States)

    Bahrami, Hadi; Mirbozorgi, S Abdollah; Ameli, Reza; Rusch, Leslie A; Gosselin, Benoit

    2016-02-01

    Implanted antennas for implant-to-air data communications must be composed of material compatible with biological tissues. We design single and dual-polarization antennas for wireless ultra-wideband neural recording systems using an inhomogeneous multi-layer model of the human head. Antennas made from flexible materials are more easily adapted to implantation; we investigate both flexible and rigid materials and examine performance trade-offs. The proposed antennas are designed to operate in a frequency range of 2-11 GHz (having S11 below -10 dB) covering both the 2.45 GHz (ISM) band and the 3.1-10.6 GHz UWB band. Measurements confirm simulation results showing flexible antennas have little performance degradation due to bending effects (in terms of impedance matching). Our miniaturized flexible antennas are 12 mm×12 mm and 10 mm×9 mm for single- and dual-polarizations, respectively. Finally, a comparison is made of four implantable antennas covering the 2-11 GHz range: 1) rigid, single polarization, 2) rigid, dual polarization, 3) flexible, single polarization and 4) flexible, dual polarization. In all cases a rigid antenna is used outside the body, with an appropriate polarization. Several advantages were confirmed for dual polarization antennas: 1) smaller size, 2) lower sensitivity to angular misalignments, and 3) higher fidelity.

  18. Joint Polar Satellite System (JPSS) Common Ground System (CGS) Block 3.0 Communications Strategies

    Science.gov (United States)

    Miller, S. W.; Grant, K. D.; Ottinger, K.

    2015-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). The JPSS program is the follow-on for both space and ground systems to the Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA. The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological and geophysical observations of the Earth. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS). Developed and maintained by Raytheon Intelligence, Information and Services (IIS), the CGS is a globally distributed, multi-mission system serving NOAA, NASA and their national and international partners. The CGS has demonstrated its scalability and flexibility to incorporate multiple missions efficiently and with minimal cost, schedule and risk, while strengthening global partnerships in weather and environmental monitoring. In a highly successful international partnership between NOAA and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), the CGS currently provides data routing from McMurdo Station in Antarctica to the EUMETSAT processing center in Darmstadt, Germany. Continuing and building upon that partnership, NOAA and EUMETSAT are collaborating on the development of a new path forward for the 2020's. One approach being explored is a concept of operations where each organization shares satellite downlink resources with the other. This paper will describe that approach, as well as modeling results that demonstrate its feasibility and expected performance.

  19. FM-AM Conversion Induced by Polarization Mode Dispersion in Fiber Systems

    International Nuclear Information System (INIS)

    Xiao-Dong, Huang; Sheng-Zhi, Zhao; Jian-Jun, Wang; Ming-Zhong, Li; Dang-Peng, Xu; Hong-Huan, Lin; Rui, Zhang; Ying, Deng; Xiao-Min, Zhang

    2010-01-01

    The conversion of the frequency modulated pulse induced from frequency modulation (FM) to amplitude modulation (AM) by the polarization mode dispersion (PMD) is theoretically and experimentally investigated. When there is no polarizer at the output end of a fiber system, the amplitude modulation depth is stable by 8%. Random amplitude modulation is observed when a polarizer is placed at the output end of the fiber system. The observed minimum and maximum modulation depths in our experiment are 5% and 80%, respectively. Simulation results show that the amplitude modulation is stable by 4% induced mainly by group velocity dispersion (GVD) when there is no polarizer, and the amplitude modulation depth displays the random variation character induced by the GVD and PMD. Lastly, a new fiber system scheme is proposed and little amplitude modulation is observed at the top of the output pulse

  20. Distributed reconfigurable control strategies for switching topology networked multi-agent systems.

    Science.gov (United States)

    Gallehdari, Z; Meskin, N; Khorasani, K

    2017-11-01

    In this paper, distributed control reconfiguration strategies for directed switching topology networked multi-agent systems are developed and investigated. The proposed control strategies are invoked when the agents are subject to actuator faults and while the available fault detection and isolation (FDI) modules provide inaccurate and unreliable information on the estimation of faults severities. Our proposed strategies will ensure that the agents reach a consensus while an upper bound on the team performance index is ensured and satisfied. Three types of actuator faults are considered, namely: the loss of effectiveness fault, the outage fault, and the stuck fault. By utilizing quadratic and convex hull (composite) Lyapunov functions, two cooperative and distributed recovery strategies are designed and provided to select the gains of the proposed control laws such that the team objectives are guaranteed. Our proposed reconfigurable control laws are applied to a team of autonomous underwater vehicles (AUVs) under directed switching topologies and subject to simultaneous actuator faults. Simulation results demonstrate the effectiveness of our proposed distributed reconfiguration control laws in compensating for the effects of sudden actuator faults and subject to fault diagnosis module uncertainties and unreliabilities. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  1. Sensitivity analysis of repairable redundant system with switching failure and geometric reneging

    Directory of Open Access Journals (Sweden)

    Chandra Shekhar

    2017-09-01

    Full Text Available This study deals with the performance modeling and reliability analysis of a redundant machining system composed of several functional machines. To analyze the more realistic scenarios, the concepts of switching failure and geometric reneging are included. The time-to-breakdown and repair time of operating and standby machines are assumed to follow the exponential distribution. For the quantitative assessment of the machine interference problem, various performance measures such as mean-time-to-failure, reliability, reneging rate, etc. have been formulated. To show the practicability of the developed model, a numerical illustration has been presented. For the practical justification and validity of the results established, the sensitivity analysis of reliability indices has been presented by varying different system descriptors.

  2. Leader-Following Consensus of Linear Multiagent Systems with State Observer under Switching Topologies

    Directory of Open Access Journals (Sweden)

    Lixin Gao

    2013-01-01

    Full Text Available The leader-following consensus problem of higher order multiagent systems is considered. The dynamics of each agent are given in general form of linear system, and the communication topology among the agents is assumed to be directed and switching. To track the leader, two kinds of distributed observer-based consensus protocols are proposed for each following agent, whose distributed observers are used to estimate the leader’s state and tracking error based on the relative outputs of the neighboring agents, respectively. Some sufficient consensus conditions are established by using parameter-dependent Lyapunov function method under a class of directed interaction topologies. As special cases, the consensus conditions for balanced and undirected interconnection topology cases can be obtained directly. The protocol design technique is based on algebraic graph theory, Riccati equation, and Sylvester equation. Finally, a simulation example is given to illustrate our obtained result.

  3. Design and implementation of sensorless techniques for switched reluctance drive systems

    Science.gov (United States)

    Liu, Tian-Hua; Chen, Ching-Guo

    2010-09-01

    This article proposes two different methods for estimating the shaft position for a switched reluctance motor (SRM). Method 1 uses the self-inductance estimation technique to obtain the rotor position. First, by on-line measuring the slope of the stator current and compensating for the back electromotive force (EMF) effect, the self-inductance of the SRM can be detected. Then, the shaft position of the motor can be estimated according to the self-inductance. Method 2, on the other hand, uses the phase-locked loop technique to generate high-frequency signals. These signals can be used to estimate the shaft position of the SRM. The two proposed methods are compared and discussed in the article. Several experimental results are shown to validate the theoretical analysis. The adjustable speed range of the system is from 10 to 3000 rpm. Additionally, the proposed drive system can automatically start from a standstill to a setting speed.

  4. Versatile lipid profiling by liquid chromatography–high resolution mass spectrometry using all ion fragmentation and polarity switching. Preliminary application for serum samples phenotyping related to canine mammary cancer

    Energy Technology Data Exchange (ETDEWEB)

    Gallart-Ayala, H., E-mail: laberca@oniris-nantes.fr [LUNAM, Ecole Nationale Vétérinaire, Agroalimentaire et de l’Alimentation Nantes Atlantique (Oniris), USC 1329 INRA Laboratoire d’Etude des résidus et Contaminants dans les Aliments (LABERCA), Site de la Chantrerie – CS50707, 44307 Nantes cedex 3 (France); Courant, F.; Severe, S.; Antignac, J.-P. [LUNAM, Ecole Nationale Vétérinaire, Agroalimentaire et de l’Alimentation Nantes Atlantique (Oniris), USC 1329 INRA Laboratoire d’Etude des résidus et Contaminants dans les Aliments (LABERCA), Site de la Chantrerie – CS50707, 44307 Nantes cedex 3 (France); Morio, F.; Abadie, J. [LUNAM, Ecole Nationale Vétérinaire, Agroalimentaire et de l’Alimentation Nantes Atlantique (Oniris), Cancers Animaux, Modèles pour la Recherche en Oncologie Comparée (AMaROC), Site de la Chantrerie–CS50707, 44307 Nantes cedex 3 (France); Le Bizec, B. [LUNAM, Ecole Nationale Vétérinaire, Agroalimentaire et de l’Alimentation Nantes Atlantique (Oniris), USC 1329 INRA Laboratoire d’Etude des résidus et Contaminants dans les Aliments (LABERCA), Site de la Chantrerie – CS50707, 44307 Nantes cedex 3 (France)

    2013-09-24

    Graphical abstract: -- Highlights: •Lipidomics, high resolution mass spectrometry, polarity switching, serum, canine mammary cancer. -- Abstract: Lipids represent an extended class of substances characterized by such high variety and complexity that makes their unified analyses by liquid chromatography coupled to either high resolution or tandem mass spectrometry (LC–HRMS or LC–MS/MS) a real challenge. In the present study, a new versatile methodology associating ultra high performance liquid chromatography coupled to high resolution tandem mass spectrometry (UHPLC–HRMS/MS) have been developed for a comprehensive analysis of lipids. The use of polarity switching and “all ion fragmentation” (AIF) have been two action levels particularly exploited to finally permit the detection and identification of a multi-class and multi-analyte extended range of lipids in a single run. For identification purposes, both higher energy collision dissociation (HCD) and in-source CID (collision induced dissociation) fragmentation were evaluated in order to obtain information about the precursor and product ions in the same spectra. This approach provides both class-specific and lipid-specific fragments, enhancing lipid identification. Finally, the developed method was applied for differential phenotyping of serum samples collected from pet dogs developing spontaneous malignant mammary tumors and health controls. A biological signature associated with the presence of cancer was then successfully revealed from this lipidome analysis, which required to be further investigated and confirmed at larger scale.

  5. Stability of large DC power systems using switching converters, with application to the international space station

    Science.gov (United States)

    Manners, B.; Gholdston, E. W.; Karimi, K.; Lee, F. C.; Rajagopalan, J.; Panov, Y.

    1996-01-01

    As space direct current (dc) power systems continue to grow in size, switching power converters are playing an ever larger role in power conditioning and control. When designing a large dc system using power converters of this type, special attention must be placed on the electrical stability of the system and of the individual loads on the system. In the design of the electric power system (EPS) of the International Space Station (ISS), the National Aeronautics and Space Administration (NASA) and its contractor team led by Boeing Defense & Space Group has placed a great deal of emphasis on designing for system and load stability. To achieve this goal, the team has expended considerable effort deriving a dear concept on defining system stability in both a general sense and specifically with respect to the space station. The ISS power system presents numerous challenges with respect to system stability, such as high power, complex sources and undefined loads. To complicate these issues, source and load components have been designed in parallel by three major subcontractors (Boeing, Rocketdyne, and McDonnell Douglas) with interfaces to both sources and loads being designed in different countries (Russia, Japan, Canada, Europe, etc.). These issues, coupled with the program goal of limiting costs, have proven a significant challenge to the program. As a result, the program has derived an impedance specification approach for system stability. This approach is based on the significant relationship between source and load impedances and the effect of this relationship on system stability. This approach is limited in its applicability by the theoretical and practical limits on component designs as presented by each system segment. As a result, the overall approach to system stability implemented by the ISS program consists of specific hardware requirements coupled with extensive system analysis and hardware testing. Following this approach, the ISS program plans to begin

  6. Sensory systems for a control rod position using reed switches for the integral reactor

    International Nuclear Information System (INIS)

    Yu, J. Y.; Choi, S.; Kim, J. H.; Lee, D. J.

    2007-01-01

    The system-integrated modular advanced reactor (SMART) currently under development at the Korea Atomic Energy Research Institute is being designed with a soluble boron free operation and the use of nuclear heating for the reactor start-up. These design features require a Control Element Drive Mechanism (CEDM) for the SMART to have a fine-step movement capability as well as a high reliability for a fine reactivity control. Also the reliability and accuracy of the information for the control rod position is very important to the reactor safety as well as the design of the core protection system. The position indicator is classified as a Class 1E component because the rod position signal of the position indicator is used in the safety related systems. Therefore it will be separated from the control systems to the extent that a failure of any single control system component of a channel and shall have sufficient independence, redundancy, and testability to perform its safety functions assuming a single failure. The position indicator is composed of a permanent magnet, reed switches and a voltage divider. Four independent position indicators around the upper pressure housing provide an indication of the position of a control rod comprising of a permanent magnet with a magnetic field concentrator which moves with the extension shaft connected to the control rod. The zigzag arranged reed switches are positioned along a line parallel to the path of the movement of the permanent magnet and it is activated selectively when the permanent magnet passes by. A voltage divider electrically connected to the reed switches provides a signal commensurate with the position of the control rod. The signal may then be transmitted to a position indicating device. In order to monitor the operating condition of the rotary step motor of CEDM, the angular position detector was installed at the top of the rotary step motor by means of connecting between the planetary gear and the rotating

  7. Efficacy of fixed filtration for rapid kVp-switching dual energy x-ray systems.

    Science.gov (United States)

    Yao, Yuan; Wang, Adam S; Pelc, Norbert J

    2014-03-01

    Dose efficiency of dual kVp imaging can be improved if the two beams are filtered to remove photons in the common part of their spectra, thereby increasing spectral separation. While there are a number of advantages to rapid kVp-switching for dual energy, it may not be feasible to have two different filters for the two spectra. Therefore, the authors are interested in whether a fixed added filter can improve the dose efficiency of kVp-switching dual energy x-ray systems. The authors hypothesized that a K-edge filter would provide the energy selectivity needed to remove overlap of the spectra and hence increase the precision of material separation at constant dose. Preliminary simulations were done using calcium and water basis materials and 80 and 140 kVp x-ray spectra. Precision of the decomposition was evaluated based on the propagation of the Poisson noise through the decomposition function. Considering availability and cost, the authors chose a commercial Gd2O2S screen as the filter for their experimental validation. Experiments were conducted on a table-top system using a phantom with various thicknesses of acrylic and copper and 70 and 125 kVp x-ray spectra. The authors kept the phantom exposure roughly constant with and without filtration by adjusting the tube current. The filtered and unfiltered raw data of both low and high energy were decomposed into basis material and the variance of the decomposition for each thickness pair was calculated. To evaluate the filtration performance, the authors measured the ratio of material decomposition variance with and without filtration. Simulation results show that the ideal filter material depends on the object composition and thickness, and ranges across the lanthanide series, with higher atomic number filters being preferred for more attenuating objects. Variance reduction increases with filter thickness, and substantial reductions (40%) can be achieved with a 2× loss in intensity. The authors' experimental

  8. Design and analysis of all-optical switches based on fiber parametric devices

    Science.gov (United States)

    Ma, Jing; Jiang, Chun

    2008-05-01

    We propose a novel 2 × 2 wavelength-convertible optical switch based on dual-pump fiber parametric devices: one is driven by linearly parallel pumps, and the other one by perpendicular pumps. Theoretical analysis is made on the polarization effects on the switching performance of the two devices. The result predicts that two incident signals which are positioned symmetrically with respect to one pump can be switched independently, with judicious combinations of the relative pump-signal polarization states. Simulations performed in OptiSystem show that the scheme can achieve crosstalk-free packet switching with acceptable extinction ratios for both signals. Besides, future applications of this novel scheme in high-speed switching nodes are discussed.

  9. Spectrally efficient polarization multiplexed direct-detection OFDM system without frequency gap.

    Science.gov (United States)

    Wei, Chia-Chien; Zeng, Wei-Siang; Lin, Chun-Ting

    2016-01-25

    We experimentally demonstrate a spectrally efficient direct-detection orthogonal frequency-division multiplexing (DD-OFDM) system. In addition to polarization-division multiplexing, removing the frequency gap further improves the spectral efficiency of the OFDM system. The frequency gap between a reference carrier and OFDM subcarriers avoids subcarrier-to-subcarrier beating interference (SSBI) in traditional DD-OFDM systems. Without dynamic polarization control, the resulting interference after square-law direct detection in the proposed gap-less system is polarization-dependent and composed of linear inter-carrier interference (ICI) and nonlinear SSBI. Thus, this work proposes an iterative multiple-input multiple-output detection scheme to remove the mixed polarization-dependent interference. Compared to the previous scheme, which only removes ICI, the proposed scheme can further eliminate SSBI to achieve the improvement of ∼ 7 dB in signal-to-noise ratio. Without the need for polarization control, we successfully utilize 7-GHz bandwidth to transmit a 39.5-Gbps polarization multiplexed OFDM signal over 100 km.

  10. A Damping Grid Strapdown Inertial Navigation System Based on a Kalman Filter for Ships in Polar Regions.

    Science.gov (United States)

    Huang, Weiquan; Fang, Tao; Luo, Li; Zhao, Lin; Che, Fengzhu

    2017-07-03

    The grid strapdown inertial navigation system (SINS) used in polar navigation also includes three kinds of periodic oscillation errors as common SINS are based on a geographic coordinate system. Aiming ships which have the external information to conduct a system reset regularly, suppressing the Schuler periodic oscillation is an effective way to enhance navigation accuracy. The Kalman filter based on the grid SINS error model which applies to the ship is established in this paper. The errors of grid-level attitude angles can be accurately estimated when the external velocity contains constant error, and then correcting the errors of the grid-level attitude angles through feedback correction can effectively dampen the Schuler periodic oscillation. The simulation results show that with the aid of external reference velocity, the proposed external level damping algorithm based on the Kalman filter can suppress the Schuler periodic oscillation effectively. Compared with the traditional external level damping algorithm based on the damping network, the algorithm proposed in this paper can reduce the overshoot errors when the state of grid SINS is switched from the non-damping state to the damping state, and this effectively improves the navigation accuracy of the system.

  11. A 65-kV insulated gate bipolar transistor switch applied in damped AC voltages partial discharge detection system.

    Science.gov (United States)

    Jiang, J; Ma, G M; Luo, D P; Li, C R; Li, Q M; Wang, W

    2014-02-01

    Damped AC voltages detection system (DAC) is a productive way to detect the faults in power cables. To solve the problems of large volume, complicated structure and electromagnetic interference in existing switches, this paper developed a compact solid state switch based on electromagnetic trigger, which is suitable for DAC test system. Synchronous electromagnetic trigger of 32 Insulated Gate Bipolar Transistors (IGBTs) in series was realized by the topological structure of single line based on pulse width modulation control technology. In this way, external extension was easily achieved. Electromagnetic trigger and resistor-capacitor-diode snubber circuit were optimized to reduce the switch turn-on time and circular layout. Epoxy encapsulating was chosen to enhance the level of partial discharge initial voltage (PDIV). The combination of synchronous trigger and power supply is proposed to reduce the switch volume. Moreover, we have overcome the drawback of the electromagnetic interference and improved the detection sensitivity of DAC by using capacitor storage energy to maintain IGBT gate driving voltage. The experimental results demonstrated that the solid-state switch, with compact size, whose turn-on time was less than 400 ns and PDIV was more than 65 kV, was able to meet the actual demands of 35 kV DAC test system.

  12. Verification of global numerical weather forecasting systems in polar regions using TIGGE data

    OpenAIRE

    Jung, Thomas; Matsueda, Mio

    2016-01-01

    High-latitude climate change is expected to increase the demand for reliable weather and environmental forecasts in polar regions. In this study, a quantitative assessment of the skill of state-of-the-art global weather prediction systems in polar regions is given using data from the THORPEX Interactive Grand Global Ensemble (TIGGE) for the period 2006/2007 – 2012/2013. Forecast skill in the Arctic is comparable to that found in the North- ern Hemisphere ...

  13. Biomechanical Effects of Platform Switching in Two Different Implant Systems: A Three-Dimensional Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Mahasti Sahabi

    2013-01-01

    Full Text Available Aims: The purpose of this study was to determine the influence of platform switching on stress distribution of two different implant systems, using three-dimensional (3D finite element models.Methods: Six 3D finite element models were created to replicate two different implant systems with peri-implant bone tissue, in which six different implant-abutment configurations were represented: model XiVE-a: 3.8-mm-diameter implant and 3.8-mm-diameter abutment; model XiVE-b (platform-switching model: 4.5-mm-diameter implant and 3.8-mm-diameter abutment; model XiVE-c: 4.5-mm-diameter implant and 4.5-mm-diameter abutment; model 3i-a: 4.0-mm-diameter implant and 4.1-mm-diameter abutment; model 3i-b (platform-switching model: 5.0-mm-diameter implant and 4.1-mm-diameter abutment; model 3i-c: 5.0-mm-diameter implant and 5.0-mm-diameter abutment. Axial and oblique loads of 100 were applied to all models.Results: While the pattern of stress distribution was similar for both loading situations, oblique loading resulted in higher intensity and greater distribution of stress than axial loading in both cortical bone and abutment-implant interface. Stress distribution at peri-implant bone was almost identical with similar magnitudes for all six models. In both implant systems, platform switching models demonstrated lower maximum von Mises stress in cortical bone than conventional models. However, in both implant systems and under both loading situation, platform switching models showed higher stresses at the abutment-implant interface than conventional models.Conclusion: In both implant systems, platform switching design reduced the stress concentration in the crestal bone and shifted it towards the area of implant-abutment interface

  14. In-line polarization holographic memory system using PQ doped PMMA photopolymer (Conference Presentation)

    Science.gov (United States)

    Lin, Shiuan-Huei; Lin, Lun Kuang; Marinova, Vera; Hsu, Ken-Yuh

    2016-09-01

    Polarization hologram provides some unique features over classical phase or amplitude hologram. One of the most important features is that the photo-induced anisotropy in those materials leads to the polarization-dependent diffraction from the hologram. This property is useful for many applications, such as optical interconnection, holographic data storage and bio-imaging …etc. Recently, the 9, 10-phenanthrenequinone -doped poly(methyl methacrylate) (PQ/PMMA) photopolymer with cm thickness has attracted intense research interesting for the volume holographic applications because the experiments demonstrated that PQ/PMMA photopolymers possess not only high optical quality but also negligible shrinkage effect under light exposure [3-5]. Additionally, in terms of chemical formula, the PQ/PMMA consists of planar structures PQ molecules dispersed in amorphous PMMA polymer so that it is possible to be oriented if irradiated with polarized light, resulting in a photoinduced birefringence. This phenomenon makes it capable for permanent polarization holographic recording via photochemical reaction. Thus, combining these two properties may make PQ/PMMA photopolymer attractive for volume polarization holographic applications. In this paper, we particularly characterize polarization holographic recording in our materials for high-density data storage. Then, we will demonstrate a in-line polarization holographic memory system using PQ/PMMA photopolymer.

  15. Reversible optical switching memristors with tunable STDP synaptic plasticity: a route to hierarchical control in artificial intelligent systems.

    Science.gov (United States)

    Jaafar, Ayoub H; Gray, Robert J; Verrelli, Emanuele; O'Neill, Mary; Kelly, Stephen M; Kemp, Neil T

    2017-11-09

    Optical control of memristors opens the route to new applications in optoelectronic switching and neuromorphic computing. Motivated by the need for reversible and latched optical switching we report on the development of a memristor with electronic properties tunable and switchable by wavelength and polarization specific light. The device consists of an optically active azobenzene polymer, poly(disperse red 1 acrylate), overlaying a forest of vertically aligned ZnO nanorods. Illumination induces trans-cis isomerization of the azobenzene molecules, which expands or contracts the polymer layer and alters the resistance of the off/on states, their ratio and retention time. The reversible optical effect enables dynamic control of a memristor's learning properties including control of synaptic potentiation and depression, optical switching between short-term and long-term memory and optical modulation of the synaptic efficacy via spike timing dependent plasticity. The work opens the route to the dynamic patterning of memristor networks both spatially and temporally by light, thus allowing the development of new optically reconfigurable neural networks and adaptive electronic circuits.

  16. A gain-coefficient switched Alexandrite laser

    International Nuclear Information System (INIS)

    Lee, Chris J; Van der Slot, Peter J M; Boller, Klaus-J

    2013-01-01

    We report on a gain-coefficient switched Alexandrite laser. An electro-optic modulator is used to switch between high and low gain states by making use of the polarization dependent gain of Alexandrite. In gain-coefficient switched mode, the laser produces 85 ns pulses with a pulse energy of 240 mJ at a repetition rate of 5 Hz.

  17. A novel solid-state control system for the minimization of re-switching transient currents of induction motor

    International Nuclear Information System (INIS)

    Abro, M.R.; Larik, A.S.; Mahar, M.A.

    2005-01-01

    This work is an investigation into the minimizing re-closure transient currents of induction motors by activating NOVEL solid state control system switching at a matched condition. This emphasis is placed upon-circuit transition starting of cage motors, particularly star-delta switching. The initial study is carried out on single-phase induction motion. This system is capable of effective sensing re-closure of a switched off running single-phase induction motor. Further this scheme could be developed to give sequential delta closure of a switched off running three-phase induction motor during 1st cycles following the opening of the star mode. Consideration is also given to the possibility of using sensed re-closure to minimize transient whenever the supply to a running induction motor is briefly interrupted, irrespective of whether the interruption is by accident design. A brief study is made into the type of transient currents generated by opening the circuit of a running induction motor. The importance of the switching pattern for star-delta starting is explained and emphasized. (author)

  18. Artificial OFF-Riboswitches That Downregulate Internal Ribosome Entry without Hybridization Switches in a Eukaryotic Cell-Free Translation System.

    Science.gov (United States)

    Ogawa, Atsushi; Masuoka, Hiroki; Ota, Tsubasa

    2017-09-15

    We constructed novel artificial riboswitches that function in a eukaryotic translation system (wheat germ extract), by rationally implanting an in vitro-selected aptamer into the intergenic internal ribosome entry site (IRES) of Plautia stali intestine virus. These eukaryotic OFF-riboswitches (OFF-eRSs) ligand-dose-dependently downregulate IRES-mediated translation without hybridization switches, which typical riboswitches utilize for gene regulation. The hybridization-switch-free mechanism not only allows for easy design but also requires less energy for regulation, resulting in a higher switching efficiency than hybridization-switch-based OFF-eRSs provide. In addition, even a small ligand such as theophylline can induce satisfactory repression, in contrast to other types of OFF-eRSs that modulate the 5' cap-dependent canonical translation. Because our proposed hybridization-switch-free OFF-eRSs are based on a versatile IRES that functions well in many types of eukaryotic translation systems, they would be widely usable elements for synthetic gene circuits in both cell-free and cell-based synthetic biology.

  19. What makes the lac-pathway switch : identifying the fluctuations that trigger phenotype switching in gene regulatory systems

    NARCIS (Netherlands)

    Bhogale, Prasanna M; Sorg, Robin A; Veening, Jan-Willem; Berg, Johannes

    2014-01-01

    Multistable gene regulatory systems sustain different levels of gene expression under identical external conditions. Such multistability is used to encode phenotypic states in processes including nutrient uptake and persistence in bacteria, fate selection in viral infection, cell-cycle control and

  20. Bidirectional fiber-IVLLC and fiber-wireless convergence system with two orthogonally polarized optical sidebands.

    Science.gov (United States)

    Lu, Hai-Han; Wu, Hsiao-Wen; Li, Chung-Yi; Ho, Chun-Ming; Yang, Zih-Yi; Cheng, Ming-Te; Lu, Chang-Kai

    2017-05-01

    A bidirectional fiber-invisible laser light communication (IVLLC) and fiber-wireless convergence system with two orthogonally polarized optical sidebands for hybrid cable television (CATV)/millimeter-wave (MMW)/baseband (BB) signal transmission is proposed and experimentally demonstrated. Two optical sidebands generated by a 60-GHz MMW signal are orthogonally polarized and separated into different polarizations. These orthogonally polarized optical sidebands are delivered over a 40-km single-mode fiber (SMF) transport to effectually reduce the fiber dispersion induced by a 40-km SMF transmission and the distortion caused by the parallel polarized optical sidebands. To the best of our knowledge, this work is the first to adopt two orthogonally polarized optical sidebands in a bidirectional fiber-IVLLC and fiber-wireless convergence system to reduce fiber dispersion and distortion effectually. Good carrier-to-noise ratio, composite second order, composite triple beat, and bit error rate (BER) are achieved for downlink transmission at a 40-km SMF operation and a 100-m free-space optical (FSO) link/3-m RF wireless transmission. For up-link transmission, good BER performance is acquired over a 40-km SMF transport and a 100-m FSO link. The approach presented in this work signifies the advancements in the convergence of SMF-based backbone and optical/RF wireless-based feeder.

  1. Realisation and Optimization the System of Ridge WaveguidePolarizer by Genetic Algorithms for Telecommunication Satellite Antennas

    OpenAIRE

    BOUSALAH1, FAYZA; NOUR EDDINE2; BOUKLI HACENE

    2013-01-01

    The ridged waveguide polarizer is considered as the better way to get right-hand and left-hand circular polarization in the antennas of telecommunications satellites. In fact, it is a system of three ports used to feed a square waveguide antenna in order to achieve high purity in the right-hand and left-hand circular polarization. Obtaining a great purity of polarization results by the addition from screw from adaptation and blades from correction. A solution with this pr...

  2. Spin-orbital dynamics in a system of polar molecules

    Science.gov (United States)

    Syzranov, Sergey V.; Wall, Michael L.; Gurarie, Victor; Rey, Ana Maria

    2014-11-01

    Spin-orbit coupling in solids normally originates from the electron motion in the electric field of the crystal. It is key to understanding a variety of spin-transport and topological phenomena, such as Majorana fermions and recently discovered topological insulators. Implementing and controlling spin-orbit coupling is thus highly desirable and could open untapped opportunities for the exploration of unique quantum physics. Here we show that dipole-dipole interactions can produce an effective spin-orbit coupling in two-dimensional ultracold polar molecule gases. This spin-orbit coupling generates chiral excitations with a non-trivial Berry phase 2π. These excitations, which we call chirons, resemble low-energy quasiparticles in bilayer graphene and emerge regardless of the quantum statistics and for arbitrary ratios of kinetic to interaction energies. Chirons manifest themselves in the dynamics of the spin density profile, spin currents and spin coherences, even for molecules pinned in a deep optical lattice and should be observable in current experiments.

  3. Joint switched multi-spectrum and transmit antenna diversity for spectrum sharing systems

    KAUST Repository

    Sayed, Mostafa M.

    2013-10-01

    In spectrum sharing systems, a secondary user (SU) is allowed to share the spectrum with a primary (licensed) network under the condition that the interference observed at the receivers of the primary users (PU-Rxs) is below a predetermined level. In this paper, we consider a secondary network comprised of a secondary transmitter (SU-Tx) equipped with multiple antennas and a single-antenna secondary receiver (SU-Rx) sharing the same spectrum with multiple primary users (PUs), each with a distinct spectrum. We develop transmit antenna diversity schemes at the SU-Tx that exploit the multi-spectrum diversity provided by the existence of multiple PUs so as to optimize the signal-to-noise ratio (SNR) at the SU-Rx. In particular, assuming bounded transmit power at the SU-Tx, we develop switched selection schemes that select the primary spectrum and the SU-Tx transmit antenna that maintain the SNR at the SU-Rx above a specific threshold. Assuming Rayleigh fading channels and binary phase-shift keying (BPSK) transmission, we derive the average bit-error-rate (BER) and average feedback load expressions for the proposed schemes. For the sake of comparison, we also derive a BER expression for the optimal selection scheme that selects the best antenna/spectrum pair that maximizes the SNR at the SU-Rx, in exchange of high feedback load and switching complexity. Finally, we show that our analytical results are in perfect agreement with the simulation results. © 2013 IEEE.

  4. A High-Resolution Continuous Flow Analysis System for Polar Ice Cores

    DEFF Research Database (Denmark)

    Dallmayr, Remi; Goto-Azuma, Kumiko; Kjær, Helle Astrid

    2016-01-01

    signals of abrupt climate change in deep polar ice cores. To test its performance, we used the system to analyze different climate intervals in ice drilled at the NEEM (North Greenland Eemian Ice Drilling) site, Greenland. The quality of our continuous measurement of stable water isotopes has been...... of Polar Research (NIPR) in Tokyo. The system allows the continuous analysis of stable water isotopes and electrical conductivity, as well as the collection of discrete samples from both inner and outer parts of the core. This CFA system was designed to have sufficiently high temporal resolution to detect...

  5. Analysis of Switching Transient Overvoltages in the Power System of Floating Production Storage and Offloading Vessel

    NARCIS (Netherlands)

    Xue, H.; Popov, M.

    2013-01-01

    Large transient overvoltages are normally caused by vacuum circuit breaker (VCB) switching operation during disconnection of induction motors. In this paper VCBs, cables, generators, busbars, induction motors and surge arresters are modeled by making use of ATP-EMTP. Switching transient overvoltages

  6. FreeSWITCH Cookbook

    CERN Document Server

    Minessale, Anthony

    2012-01-01

    This is a problem-solution approach to take your FreeSWITCH skills to the next level, where everything is explained in a practical way. If you are a system administrator, hobbyist, or someone who uses FreeSWITCH on a regular basis, this book is for you. Whether you are a FreeSWITCH expert or just getting started, this book will take your skills to the next level.

  7. Managed and Supported Missions in the Joint Polar Satellite System (JPSS) Common Ground System (CGS)

    Science.gov (United States)

    Jamilkowski, M. L.; Grant, K. D.; Miller, S. W.; Cochran, S.

    2015-12-01

    NOAA & NASA are acquiring the next-generation civilian operational weather satellite: Joint Polar Satellite System (JPSS). Replacing the p.m. orbit & ground system (GS) of POES satellites, JPSS sensors will collect weather, ocean & climate data. JPSS's Common Ground System (CGS), made up of C3 & IDP parts and developed by Raytheon, now flies the Suomi National Polar-orbiting Partnership (S-NPP) satellite, transfers data between ground facilities, processes them into Environmental Data Records for NOAA's weather centers and evolves to support JPSS-1 in 2017. CGS processed S-NPP data creates many TBs/day across >2 dozen environmental data products (EDPs), doubling after JPSS launch. But CGS goes beyond this by providing data routing to other missions: GCOM-W1, Coriolis/Windsat, EOS, NSF's McMurdo Station, Defense Meteorological Satellite Program, and POES & MetOp satellites. Each system orbits 14 times/day, downlinking data 1-2 times/orbit at up to 100s of MBs/sec, to support the creation of 10s of TBs of data/day across 100s of EDPs. CGS's flexible, multimission capabilities offer major chances for cost reduction & improved information integration across the missions. CGS gives a vital flexible-expandable-virtualized modern GS architecture. Using 5 global ground stations to receive S-NPP & JPSS-1 data, CGS links with high-bandwidth commercial fiber to rapidly move data to the IDP for EDP creation & delivery and leverages these networks to provide added support to more missions. CGS data latency will be < 80 minutes. JPSS CGS is a mature, tested solution for support to operational weather forecasting for civil, military and international partners and climate research. It features a flexible design handling order-of-magnitude increases in data over legacy systems and meets tough science accuracy needs. The Raytheon-built CGS gives the full GS capability, from design & development through operations & sustainment, facilitating future evolution to support more missions.

  8. Protective systems and its protective switching elements on local failures of large slow-capacitor bank system

    International Nuclear Information System (INIS)

    Hasegawa, Mitsuo; Inoue, Kunikazu; Ueno, Isao.

    1994-01-01

    In various applications of pulsed power technologies, large capacitor bank systems are used to feed high current impulse to different experimental devices. The accidental electric breakdown in one of the capacitors in a parallel connection of the large bank may result in serious damages such as mechanical explosion and oil effusion or fire. In most fast banks, each unit capacitor has an output gap switch, which is expected to decouple the capacitors one another. However, no such special element is adopted usually in the slow bank system, partly because of the economical consideration. We have developed a novel and inexpensive protective element for these relatively slow capacitor banks, utilizing a concept of the enclosed type of the fast breakers. The principle of the operation of the protection elements is verified by a simulation experiment. Their practical effectiveness is also successfully demonstrated in the application to the system of the pulsed high magnetic field generator. (author)

  9. Sensing system with USB camera for experiments of polarization of the light

    Directory of Open Access Journals (Sweden)

    José Luís Fabris

    2017-08-01

    Full Text Available This work shows a sensor system for educational experiments, composed of a USB camera and a software developed and provided by the authors. The sensor system is suitable for the purpose of studying phenomena related to the polarization of the light. The system was tested in experiments performed to verify the Malus’ Law and the spectral efficiency of polarizers. Details of the experimental setup are shown. The camera captures the light in the visible spectral range from a LED that illuminates a white screen after passing through two polarizers. The software uses the image captured by the camera to provide the relative intensity of the light. With the use of two rotating H-sheet linear polarizers, a linear fitting of the Malus’s Law to the transmitted light intensity data resulted in correlation coefficients R larger than 0.9988. The efficiency of the polarizers in different visible spectral regions was verified with the aid of color filters added to the experimental setup. The system was also used to evaluate the intensity time stability of a white LED.

  10. Quorum-Sensing Synchronization of Synthetic Toggle Switches: A Design Based on Monotone Dynamical Systems Theory.

    Directory of Open Access Journals (Sweden)

    Evgeni V Nikolaev

    2016-04-01

    Full Text Available Synthetic constructs in biotechnology, biocomputing, and modern gene therapy interventions are often based on plasmids or transfected circuits which implement some form of "on-off" switch. For example, the expression of a protein used for therapeutic purposes might be triggered by the recognition of a specific combination of inducers (e.g., antigens, and memory of this event should be maintained across a cell population until a specific stimulus commands a coordinated shut-off. The robustness of such a design is hampered by molecular ("intrinsic" or environmental ("extrinsic" noise, which may lead to spontaneous changes of state in a subset of the population and is reflected in the bimodality of protein expression, as measured for example using flow cytometry. In this context, a "majority-vote" correction circuit, which brings deviant cells back into the required state, is highly desirable, and quorum-sensing has been suggested as a way for cells to broadcast their states to the population as a whole so as to facilitate consensus. In this paper, we propose what we believe is the first such a design that has mathematically guaranteed properties of stability and auto-correction under certain conditions. Our approach is guided by concepts and theory from the field of "monotone" dynamical systems developed by M. Hirsch, H. Smith, and others. We benchmark our design by comparing it to an existing design which has been the subject of experimental and theoretical studies, illustrating its superiority in stability and self-correction of synchronization errors. Our stability analysis, based on dynamical systems theory, guarantees global convergence to steady states, ruling out unpredictable ("chaotic" behaviors and even sustained oscillations in the limit of convergence. These results are valid no matter what are the values of parameters, and are based only on the wiring diagram. The theory is complemented by extensive computational bifurcation analysis

  11. Investigation study of geometric dimensions of the magnetic system of the switched-reluctance machine influence on magnetic moment

    Science.gov (United States)

    Petrushin, A.; Shevkunova, A.

    2018-02-01

    The article deals with the investigation concentrated to optimizing the active part of the switched-reluctance motor with the aim of increasing the value of the average electromagnetic torque. Susceptibility of the average value of the electromagnetic torque to changes of the geometric dimensions of the magnetic system found in the optimization process was set.

  12. Modernization of the Electric Power Systems (transformers, rods and switches) in the Laguna Verde Nuclear Power Plant (Mexico)

    International Nuclear Information System (INIS)

    Gonzalez Solarzano, J. J.; Gabaldon Martin, M. A.; Pallisa Nunez, J.; Florez Ordeonez, A.; Fernandez Corbeira, A.; Prieto Diez, I.

    2010-01-01

    Description of the changes made in the Electric Power Systems as a part of the power increase project in the Laguna Verde Nuclear Power Plant (Mexico). The main electrical changes to make, besides the turbo group, are the main generation transformers, the isolated rods and the generation switch.

  13. Atomic switch networks-nanoarchitectonic design of a complex system for natural computing.

    Science.gov (United States)

    Demis, E C; Aguilera, R; Sillin, H O; Scharnhorst, K; Sandouk, E J; Aono, M; Stieg, A Z; Gimzewski, J K

    2015-05-22

    Self-organized complex systems are ubiquitous in nature, and the structural complexity of these natural systems can be used as a model to design new classes of functional nanotechnology based on highly interconnected networks of interacting units. Conventional fabrication methods for electronic computing devices are subject to known scaling limits, confining the diversity of possible architectures. This work explores methods of fabricating a self-organized complex device known as an atomic switch network and discusses its potential utility in computing. Through a merger of top-down and bottom-up techniques guided by mathematical and nanoarchitectonic design principles, we have produced functional devices comprising nanoscale elements whose intrinsic nonlinear dynamics and memorization capabilities produce robust patterns of distributed activity and a capacity for nonlinear transformation of input signals when configured in the appropriate network architecture. Their operational characteristics represent a unique potential for hardware implementation of natural computation, specifically in the area of reservoir computing-a burgeoning field that investigates the computational aptitude of complex biologically inspired systems.

  14. Atomic switch networks—nanoarchitectonic design of a complex system for natural computing

    Science.gov (United States)

    Demis, E. C.; Aguilera, R.; Sillin, H. O.; Scharnhorst, K.; Sandouk, E. J.; Aono, M.; Stieg, A. Z.; Gimzewski, J. K.

    2015-05-01

    Self-organized complex systems are ubiquitous in nature, and the structural complexity of these natural systems can be used as a model to design new classes of functional nanotechnology based on highly interconnected networks of interacting units. Conventional fabrication methods for electronic computing devices are subject to known scaling limits, confining the diversity of possible architectures. This work explores methods of fabricating a self-organized complex device known as an atomic switch network and discusses its potential utility in computing. Through a merger of top-down and bottom-up techniques guided by mathematical and nanoarchitectonic design principles, we have produced functional devices comprising nanoscale elements whose intrinsic nonlinear dynamics and memorization capabilities produce robust patterns of distributed activity and a capacity for nonlinear transformation of input signals when configured in the appropriate network architecture. Their operational characteristics represent a unique potential for hardware implementation of natural computation, specifically in the area of reservoir computing—a burgeoning field that investigates the computational aptitude of complex biologically inspired systems.

  15. Sufficient and necessary conditions for discrete-time nonlinear switched systems with uniform local exponential stability

    Science.gov (United States)

    Lu, Junjie; She, Zhikun

    2016-11-01

    In this paper, we investigate sufficient and necessary conditions of uniform local exponential stability (ULES) for the discrete-time nonlinear switched system (DTNSS). We start with the definition of T-step common Lyapunov functions (CLFs), which is a relaxation of traditional CLFs. Then, for a time-varying DTNSS, by constructing such a T-step CLF, a necessary and sufficient condition for its ULES is provided. Afterwards, we strengthen it based on a T-step Lipschitz continuous CLF. Especially, when the system is time-invariant, by the smooth approximation theorem, the Lipschitz continuity condition of T-step CLFs can further be replaced by continuous differentiability; and when the system is time-invariant and homogeneous, due to the extension of Weierstrass approximation theorem, T-step continuously differentiable CLFs can even be strengthened to be T-step polynomial CLFs. Furthermore, three illustrative examples are additionally used to explain our main contribution. In the end, an equivalence between time-varying DTNSSs and their corresponding linearisations is discussed.

  16. Space-Time Block Coding with Beamforming for Triple-Polarized Uniform Linear Array Systems

    Directory of Open Access Journals (Sweden)

    Xin Su

    2015-01-01

    Full Text Available Generally, space-time block coding (STBC and beamforming (BF gains cannot be obtained simultaneously because the former performs well under a low correlated MIMO channel, and the latter works efficiently in an environment with high correlation. However, array systems with antenna polarization have the potential to achieve gains with both techniques simultaneously because the cross-branch links in the system are usually uncorrelated. The cross-array links, on the other hand, can be highly correlated by setting the array element space equal to, or less than, a half-wavelength. This paper proposes a scheme to explore STBC and BF simultaneously via a triple-polarized uniform linear array (TPULA system. The proposed scheme was verified based on the Long Term Evolution-Advanced (LTE-A specification under a polarized MIMO (PMIMO channel model, and therewith, the simulation results confirmed the validity of our proposed scheme.

  17. Polarized Uniform Linear Array System: Beam Radiation Pattern, Beamforming Diversity Order, and Channel Capacity

    Directory of Open Access Journals (Sweden)

    Xin Su

    2015-01-01

    Full Text Available There have been many studies regarding antenna polarization; however, there have been few publications on the analysis of the channel capacity for polarized antenna systems using the beamforming technique. According to Chung et al., the channel capacity is determined by the density of scatterers and the transmission power, which is obtained based on the assumption that scatterers are uniformly distributed on a 3D spherical scattering model. However, it contradicts the practical scenario, where scatterers may not be uniformly distributed under outdoor environment, and lacks the consideration of fading channel gain. In this study, we derive the channel capacity of polarized uniform linear array (PULA systems using the beamforming technique in a practical scattering environment. The results show that, for PULA systems, the channel capacity, which is boosted by beamforming diversity, can be determined using the channel gain, beam radiation pattern, and beamforming diversity order (BDO, where the BDO is dependent on the antenna characteristics and array configurations.

  18. Rotatable high-resolution ARPES system for tunable linear-polarization geometry.

    Science.gov (United States)

    Iwasawa, H; Shimada, K; Schwier, E F; Zheng, M; Kojima, Y; Hayashi, H; Jiang, J; Higashiguchi, M; Aiura, Y; Namatame, H; Taniguchi, M

    2017-07-01

    A rotatable high-resolution angle-resolved photoemission spectroscopy (ARPES) system has been developed to utilize tunable linear-polarization geometries on the linear undulator beamline (BL-1) at Hiroshima Synchrotron Radiation Center. By rotating the whole ARPES measurement system, the photoelectron detection plane can be continuously changed from parallel to normal against the electric field vector of linearly polarized undulator radiation. This polarization tunability enables us to identify the symmetry of the initial electronic states with respect to the mirror planes, and to selectively observe the electronic states based on the dipole selection rule in the photoemission process. Specifications of the rotatable high-resolution ARPES system are described, as well as its capabilities with some representative experimental results.

  19. (Ingezonden en geaccepteerd) Effect of switching off unidirectional downflow systems of operating theaters during prolonged inactivity on the period before the operating theater can safely be used

    NARCIS (Netherlands)

    Traversari, A.A.L.; Bottenheft, C.; Heumen, S.P.M. van; Goedhart, C.A.; Vos, M.C.

    2016-01-01

    Background: Switching off air handling systems in operating theaters during periods of prolonged inactivity (eg, nights, weekends) can produce a substantial reduction of energy expenditure. However, little evidence is available regarding the effect of switching off the air handling system during

  20. Design and Performance Analysis of 2D OCDMA System with Polarization States

    Science.gov (United States)

    Bharti, Manisha; Sharma, Ajay K.; Kumar, Manoj

    2016-12-01

    This paper focuses on increasing the number of subscribers in optical code-division multiple access (OCDMA) system by using one of the features of light signal that it can be propagated in two polarization states. The performance of two-dimensional (2D) OCDMA system based on wavelength-time coding scheme by adding polarization state is investigated at varying data rates from 1 GHz to 6 GHz and for various modulation formats. It is reported that with increase in data rate of system, the performance of the system deteriorates due to polarization mode dispersion. Non-return to-zero (RZ), return to-zero (RZ), carrier suppressed return-to-zero (CSRZ) and differential phase shift keying (DPSK) modulation formats are simulated for a single user system with polarization. Investigations reveal that differential phase shift keying (DPSK) modulation format suits best to the proposed system and exhibit the potential to improve the flexibility of system for more number of users. The investigations are reported in terms of Q-factor, BER, received optical power (ROP) and eye diagrams.

  1. Mid-infrared imaging system based on polarizers for detecting marine targets covered in sun glint.

    Science.gov (United States)

    Zhao, Huijie; Ji, Zheng; Zhang, Ying; Sun, Xiaofeng; Song, Pengfei; Li, Yansong

    2016-07-25

    When a marine target is detected by a mid-infrared detector on a sunny day, the target's information could be lost if it is located in sun glint. Therefore, we developed a new mid-infrared imaging system capable of effectively detecting marine targets in regions of strong sun glint, which is presented in this report. Firstly, the theory of the analysis methods employed in different detection scenarios is briefly described to establish whether one or two polarizers should be utilized to suppress further the p-polarized component of sun glint. Secondly, for the case in which a second polarizer is employed, the formula for the optimum angle between the two polarizers is given. Then, the results of our field experiment are presented, demonstrating that the developed system can significantly reduce sun glint and can enhance the contrast of target images. A commonly used image processing algorithm proved capable of identifying a target in sun glint, confirming the effectiveness of our proposed mid-infrared polarization imaging system.

  2. A simple polarized-based diffused reflectance colour imaging system

    African Journals Online (AJOL)

    The system uses a commercial web camera and a halogen lamp that makes it relatively simple and less expensive for diagnostic research and teaching. The system has been used to demonstrate ... Predicting the area of the sample using a method of counting dark pixels is presented. This method avoids complex and more ...

  3. Distributed Synchronization in Networks of Agent Systems With Nonlinearities and Random Switchings.

    Science.gov (United States)

    Tang, Yang; Gao, Huijun; Zou, Wei; Kurths, Jürgen

    2013-02-01

    In this paper, the distributed synchronization problem of networks of agent systems with controllers and nonlinearities subject to Bernoulli switchings is investigated. Controllers and adaptive updating laws injected in each vertex of networks depend on the state information of its neighborhood. Three sets of Bernoulli stochastic variables are introduced to describe the occurrence probabilities of distributed adaptive controllers, updating laws and nonlinearities, respectively. By the Lyapunov functions method, we show that the distributed synchronization of networks composed of agent systems with multiple randomly occurring nonlinearities, multiple randomly occurring controllers, and multiple randomly occurring updating laws can be achieved in mean square under certain criteria. The conditions derived in this paper can be solved by semi-definite programming. Moreover, by mathematical analysis, we find that the coupling strength, the probabilities of the Bernoulli stochastic variables, and the form of nonlinearities have great impacts on the convergence speed and the terminal control strength. The synchronization criteria and the observed phenomena are demonstrated by several numerical simulation examples. In addition, the advantage of distributed adaptive controllers over conventional adaptive controllers is illustrated.

  4. Social defeat stress switches the neural system mediating benzodiazepine conditioned motivation.

    Science.gov (United States)

    Riad-Allen, Lilian; van der Kooy, Derek

    2013-08-01

    Benzodiazepines have been demonstrated to have a high abuse liability in persons suffering from anxiety but have demonstrated mixed abuse liability findings in preclinical models. We hypothesized that by modeling anxiety in a male C57BL/6 mouse model it would be possible to reveal a preference for benzodiazepines within this subpopulation through negative reinforcement. Using the Tube Test of Social Dominance and the Resident/Intruder Paradigm we investigated whether animals identified as dominant or submissive/defeated would differentially display a preference for midazolam (a short acting benzodiazepine) in a conditioned place preference paradigm. Consistent with our hypotheses, benzodiazepine conditioned motivation was mediated by negative reinforcement as submissive but not dominant mice displayed a preference for midazolam. Furthermore, different neural systems mediated midazolam conditioned motivation depending on the stress status of the animal (single vs. repeated stress-as induced by the Resident/Intruder Paradigm). Singly stressed animals showed midazolam place preferences through a dopamine-independent pathway, whereas the place preferences of repeatedly stressed animals were mediated through a dopamine-dependent pathway. This demonstrates that stress is sufficient for switching the neural system mediating midazolam conditioned motivation. Finally, midazolam reinforcement in the conditioned place preference paradigm was shown to be predictive for dominance/submission status.

  5. Design of a polarization-controlled launcher for the ECH system on J-TEXT

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.H.; Xia, D.H., E-mail: xiadh@hust.edu.cn; Sun, D.L.; Wang, Z.J.; Xiao, J.X.; Zeng, Z.; Cui, F.T.; Yu, Z.X.; Zhuang, G.

    2016-11-15

    Highlights: • A polarization-controlled launcher is designed for the ECH system on J-TEXT. • The coordinate transformation method is used for the polarizer design of the launcher. • O-mode purity of no less than 97% for all possible injection can be achieved with this launcher. - Abstract: Based on main components including gyrotrons, magnets, auxiliary power supplies, transmission parts, etc. donated by the Culham Science Center, an electron cyclotron heating (ECH) system with four 60 GHz/200 kW/0.5 s subunits is being developed on J-TEXT for effective plasma heating and MHD studies. A launcher has been designed to inject the beam of the first subunit into plasma with the desired polarization and direction. The launcher mainly consists of a polarizer, an ellipsoidal mirror, a steerable flat mirror and a gate valve. When the beam arrives at the launcher, it is firstly diffracted by the polarizer and then focused by the ellipsoidal mirror. Finally, the beam is delivered to plasma by the steerable mirror. Owing to the limited space of the port for beam injection, the scanning range in both the toroidal and poloidal direction is about −8° to 8°. With optimization design, the available mode purity for all possible injection is no less than 97% and the beam radius at the center of plasma is about 38 mm, making it possible for high efficient coupling and localized absorption of the wave power.

  6. Highly compact (4F2) and well behaved nano-pillar transistor controlled resistive switching cell for neuromorphic system application.

    Science.gov (United States)

    Chen, Bing; Wang, Xinpeng; Gao, Bin; Fang, Zheng; Kang, Jinfeng; Liu, Lifeng; Liu, Xiaoyan; Lo, Guo-Qiang; Kwong, Dim-Lee

    2014-10-31

    To simplify the architecture of a neuromorphic system, it is extremely desirable to develop synaptic cells with the capacity of low operation power, high density integration, and well controlled synaptic behaviors. In this study, we develop a resistive switching device (ReRAM)-based synaptic cell, fabricated by the CMOS compatible nano-fabrication technology. The developed synaptic cell consists of one vertical gate-all-around Si nano-pillar transistor (1T) and one transition metal-oxide based resistive switching device (1R) stacked on top of the vertical transistor directly. Thanks to the vertical architecture and excellent controllability on the ON/OFF performance of the nano-pillar transistor, the 1T1R synaptic cell shows excellent characteristics such as extremely high-density integration ability with 4F(2) footprint, ultra-low operation current (<2 nA), fast switching speed (<10 ns), multilevel data storage and controllable synaptic switching, which are extremely desirable for simplifying the architecture of neuromorphic system.

  7. Energy reversible switching from amorphous metal based nanoelectromechanical switch

    KAUST Repository

    Mayet, Abdulilah M.

    2013-08-01

    We report observation of energy reversible switching from amorphous metal based nanoelectromechanical (NEM) switch. For ultra-low power electronics, NEM switches can be used as a complementary switching element in many nanoelectronic system applications. Its inherent zero power consumption because of mechanical detachment is an attractive feature. However, its operating voltage needs to be in the realm of 1 volt or lower. Appropriate design and lower Young\\'s modulus can contribute achieving lower operating voltage. Therefore, we have developed amorphous metal with low Young\\'s modulus and in this paper reporting the energy reversible switching from a laterally actuated double electrode NEM switch. © 2013 IEEE.

  8. Diversity and Multiplexing Technologies by 3D Beams in Polarized Massive MIMO Systems

    Directory of Open Access Journals (Sweden)

    Xin Su

    2016-01-01

    Full Text Available Massive multiple input, multiple output (M-MIMO technologies have been proposed to scale up data rates reaching gigabits per second in the forthcoming 5G mobile communications systems. However, one of crucial constraints is a dimension in space to implement the M-MIMO. To cope with the space constraint and to utilize more flexibility in 3D beamforming (3D-BF, we propose antenna polarization in M-MIMO systems. In this paper, we design a polarized M-MIMO (PM-MIMO system associated with 3D-BF applications, where the system architectures for diversity and multiplexing technologies achieved by polarized 3D beams are provided. Different from the conventional 3D-BF achieved by planar M-MIMO technology to control the downtilted beam in a vertical domain, the proposed PM-MIMO realizes 3D-BF via the linear combination of polarized beams. In addition, an effective array selection scheme is proposed to optimize the beam-width and to enhance system performance by the exploration of diversity and multiplexing gains; and a blind channel estimation (BCE approach is also proposed to avoid pilot contamination in PM-MIMO. Based on the Long Term Evolution-Advanced (LTE-A specification, the simulation results finally confirm the validity of our proposals.

  9. Chapter 2. Mode-switching in Hydraulic Actuator Systems - An Experiment

    DEFF Research Database (Denmark)

    Andersen, Torben Ole; Conrad, Finn; Ravn, Anders P.

    1996-01-01

    Experiments with mode-switching adaptive control of actuators to drive a hydraulic test robot.The research is a cooperation with IT, DTU within the IMCIA Research Programme supported by the Danish Technical Research Council, STVF.......Experiments with mode-switching adaptive control of actuators to drive a hydraulic test robot.The research is a cooperation with IT, DTU within the IMCIA Research Programme supported by the Danish Technical Research Council, STVF....

  10. An emergency call system for patients in locked-in state using an SSVEP-based brain switch.

    Science.gov (United States)

    Lim, Jeong-Hwan; Kim, Yong-Wook; Lee, Jun-Hak; An, Kwang-Ok; Hwang, Han-Jeong; Cha, Ho-Seung; Han, Chang-Hee; Im, Chang-Hwan

    2017-11-01

    Patients in a locked-in state (LIS) due to severe neurological disorders such as amyotrophic lateral sclerosis (ALS) require seamless emergency care by their caregivers or guardians. However, it is a difficult job for the guardians to continuously monitor the patients' state, especially when direct communication is not possible. In the present study, we developed an emergency call system for such patients using a steady-state visual evoked potential (SSVEP)-based brain switch. Although there have been previous studies to implement SSVEP-based brain switch system, they have not been applied to patients in LIS, and thus their clinical value has not been validated. In this study, we verified whether the SSVEP-based brain switch system can be practically used as an emergency call system for patients in LIS. The brain switch used for our system adopted a chromatic visual stimulus, which proved to be visually less stimulating than conventional checkerboard-type stimuli but could generate SSVEP responses strong enough to be used for brain-computer interface (BCI) applications. To verify the feasibility of our emergency call system, 14 healthy participants and 3 patients with severe ALS took part in online experiments. All three ALS patients successfully called their guardians to their bedsides in about 6.56 seconds. Furthermore, additional experiments with one of these patients demonstrated that our emergency call system maintains fairly good performance even up to 4 weeks after the first experiment without renewing initial calibration data. Our results suggest that our SSVEP-based emergency call system might be successfully used in practical scenarios. © 2017 Society for Psychophysiological Research.

  11. Environmental switching during biofilm development in a cold seep system and functional determinants of species sorting

    KAUST Repository

    Zhang, Weipeng

    2015-11-28

    The functional basis for species sorting theory remains elusive, especially for microbial community assembly in deep sea environments. Using artificial surface-based biofilm models, our recent work revealed taxonomic succession during biofilm development in a newly defined cold seep system, the Thuwal cold seeps II, which comprises a brine pool and the adjacent normal bottom water (NBW) to form a metacommunity via the potential immigration of organisms from one patch to another. Here, we designed an experiment to investigate the effects of environmental switching between the brine pool and the NBW on biofilm assembly, which could reflect environmental filtering effects during bacterial immigration to new environments. Analyses of 16S rRNA genes of 71 biofilm samples suggested that the microbial composition of biofilms established in new environments was determined by both the source community and the incubation conditions. Moreover, a comparison of 18 metagenomes provided evidence for biofilm community assembly that was based primarily on functional features rather than taxonomic identities; metal ion resistance and amino acid metabolism were the major species sorting determinants for the succession of biofilm communities. Genome binning and pathway reconstruction of two bacterial species (Marinobacter sp. and Oleispira sp.) further demonstrated metal ion resistance and amino acid metabolism as functional traits conferring the survival of habitat generalists in both the brine pool and NBW. The results of the present study sheds new light on microbial community assembly in special habitats and bridges a gap in species sorting theory.

  12. Joint multiuser switched diversity and adaptive modulation schemes for spectrum sharing systems

    KAUST Repository

    Qaraqe, Marwa

    2012-12-01

    In this paper, we develop multiuser access schemes for spectrum sharing systems whereby secondary users are allowed to share the spectrum with primary users under the condition that the interference observed at the primary receiver is below a predetermined threshold. In particular, we devise two schemes for selecting a user among those that satisfy the interference constraint and achieve an acceptable signal-to-noise ratio level. The first scheme selects the user that reports the best channel quality. In order to alleviate the high feedback load associated with the first scheme, we develop a second scheme based on the concept of switched diversity where the base station scans the users in a sequential manner until an acceptable user is found. In addition to these two selection schemes, we consider two power adaptive settings at the secondary users based on the amount of interference available at the secondary transmitter. In the On/Off power setting, users are allowed to transmit based on whether the interference constraint is met or not, while in the full power adaptive setting, the users are allowed to vary their transmission power to satisfy the interference constraint. Finally, we present numerical results for our proposed algorithms where we show the trade-off between the average spectral efficiency and average feedback load for both schemes. © 2012 IEEE.

  13. Environmental switching during biofilm development in a cold seep system and functional determinants of species sorting.

    Science.gov (United States)

    Zhang, Weipeng; Tian, Renmao; Bo, Yang; Cao, Huiluo; Cai, Lin; Chen, Lianguo; Zhou, Guowei; Sun, Jin; Zhang, Xixiang; Al-Suwailem, Abdulaziz; Qian, Pei-Yuan

    2016-05-01

    The functional basis for species sorting theory remains elusive, especially for microbial community assembly in deep-sea environments. Using artificial surface-based biofilm models, our recent work revealed taxonomic succession during biofilm development in a newly defined cold seep system, the Thuwal cold seeps II, which comprises a brine pool and the adjacent normal bottom water (NBW) to form a metacommunity via the potential immigration of organisms from one patch to another. Here, we designed an experiment to investigate the effects of environmental switching between the brine pool and the NBW on biofilm assembly, which could reflect environmental filtering effects during bacterial immigration to new environments. Analyses of 16S rRNA genes of 71 biofilm samples suggested that the microbial composition of biofilms established in new environments was determined by both the source community and the incubation conditions. Moreover, a comparison of 18 metagenomes provided evidence for biofilm community assembly that was based primarily on functional features rather than taxonomic identities; metal ion resistance and amino acid metabolism were the major species sorting determinants for the succession of biofilm communities. Genome binning and pathway reconstruction of two bacterial species (Marinobacter sp. and Oleispira sp.) further demonstrated metal ion resistance and amino acid metabolism as functional traits conferring the survival of habitat generalists in both the brine pool and NBW. The results of this study shed new light on microbial community assembly in special habitats and bridge a gap in species sorting theory. © 2015 John Wiley & Sons Ltd.

  14. Automatic Human Movement Assessment With Switching Linear Dynamic System: Motion Segmentation and Motor Performance.

    Science.gov (United States)

    de Souza Baptista, Roberto; Bo, Antonio P L; Hayashibe, Mitsuhiro

    2017-06-01

    Performance assessment of human movement is critical in diagnosis and motor-control rehabilitation. Recent developments in portable sensor technology enable clinicians to measure spatiotemporal aspects to aid in the neurological assessment. However, the extraction of quantitative information from such measurements is usually done manually through visual inspection. This paper presents a novel framework for automatic human movement assessment that executes segmentation and motor performance parameter extraction in time-series of measurements from a sequence of human movements. We use the elements of a Switching Linear Dynamic System model as building blocks to translate formal definitions and procedures from human movement analysis. Our approach provides a method for users with no expertise in signal processing to create models for movements using labeled dataset and later use it for automatic assessment. We validated our framework on preliminary tests involving six healthy adult subjects that executed common movements in functional tests and rehabilitation exercise sessions, such as sit-to-stand and lateral elevation of the arms and five elderly subjects, two of which with limited mobility, that executed the sit-to-stand movement. The proposed method worked on random motion sequences for the dual purpose of movement segmentation (accuracy of 72%-100%) and motor performance assessment (mean error of 0%-12%).

  15. Radar systems for a polar mission, volume 1

    Science.gov (United States)

    Moore, R. K.; Claassen, J. P.; Erickson, R. L.; Fong, R. K. T.; Komen, M. J.; Mccauley, J.; Mcmillan, S. B.; Parashar, S. K.

    1977-01-01

    The application of synthetic aperture radar (SAR) in monitoring and managing earth resources is examined. Synthetic aperture radars form a class of side-looking airborne radar, often referred to as coherent SLAR, which permits fine-resolution radar imagery to be generated at long operating ranges by the use of signal processing techniques. By orienting the antenna beam orthogonal to the motion of the spacecraft carrying the radar, a one-dimensional imagery ray system is converted into a two-dimensional or terrain imaging system. The radar's ability to distinguish - or resolve - closely spaced transverse objects is determined by the length of the pulse. The transmitter components receivers, and the mixer are described in details.

  16. Coupled Atom-Polar Molecule Condensate Systems: A Theoretical Adventure

    Science.gov (United States)

    2014-07-14

    Bose gases 6 VI. Landau-Ginzburg Perspective of Finite-Temperature Phase Diagrams of a Two-Component Fermi-Bose Mixture 8 VII. Collective Excitations and...state, while the latter is a tightly bound state. It is then, in principle, di¢ cult to locate a single excited state, capable of a large spatial...chain of systems. In this project, we aim to generalize the idea of chainwise stimulated Raman adiabatic passage (STI- RAP ) [Kuznetsova et al., Phys

  17. Optimized fiber delivery system for Q-switched, Nd:YAG lasers

    International Nuclear Information System (INIS)

    Setchell, R.E.

    1997-01-01

    Interest in the transmission of high intensities through optical fibers is being motivated by an increasing number of applications. Using different laser types and fiber materials, various studies are encountering transmission limitations due to laser-induced damage processes. For a number of years we have been investigating these limiting processes during the transmission of Q-switched, multimode, Nd:YAG laser pulses through step-index, multimode, fused-silica fiber. We have found that fiber transmission is often limited by a plasma-forming breakdown occurring at the fiber entrance face. This breakdown can result in subtle surface modifications that leave the entrance face more resistant to further breakdown or damage events. Catastrophic fiber damage can also occur as a result of a variety of mechanisms, with damage appearing at fiber entrance and exit faces, within the initial entry segment of the fiber path, and at other internal sites due to fiber fixturing and routing effects. System attributes that will affect breakdown and damage thresholds include laser characteristics, the design and alignment of laser-to-fiber injection optics, and fiber end-face preparation. In the present work we have combined insights gained in past studies in order to establish what thresholds can be achieved if all system attributes can be optimized to some degree. Our multimode laser utilized past modifications that produced a relatively smooth, quasi-Gaussian profile. The laser-to-fiber injection system achieved a relatively low value for the ratio of peak-to-average fluences at the fiber entrance face, incorporated a mode scrambler to generate a broad mode power distribution within the initial segment of the fiber path, and had improved fixturing to insure that the fiber axis was collinear with the incident laser beam. Test fibers were from a particular production lot for which initial-strength characteristics were established and a high-stress proof test was performed

  18. Automated system to acquire fluorescence, polarization and anisotropy maps within liquid flows.

    Science.gov (United States)

    Quintella, Cristina M; Gonçalves, Cristiane C; Pepe, Iuri; Lima, Angelo M V; Musse, Ana Paula S

    2002-01-01

    Maps of polarization and anisotropy can be helpful for flow analysis systems (FIA, CFA, etc.) with reactions dependent on the intermolecular alignment as well as for dispersion control. Maps can be acquired manually, but when a scan over a sample area is required, the acquisition becomes tiresome and has low precision. The paper describes an automatic flexible system for high-precision sample positioning with closed loop self control, remote data acquisition and storage controlled by a BASIC program. The system was developed to acquire maps up to 850 mm(2) of the sample (liquid flows, solids, interfaces, etc.), with up to 100 mum(2) precision. To evaluate the equipment, performance is presented as the scan of a thin liquid film of monoethylene glycol (MEG) flowing on borosilicate. Tests were performed with and without surfactantes at submicellar concentrations: two concentrations of sodium dodecyl sulphate (SDS) and one of polyethylene oxide (PEO). For pure MEG, the intermolecular alignment initially increased, then decreased. When SDS was added, both polarization and anisotropy only increased progressively with the flow. This might be explained by the surfactant decrease of interfacial interaction. When PEO was added, both polarization and anisotropy decreased pronouncedly over the entire map, which might be due to macromolecular aggregates within the bulk generating misaligned molecular domains. The system presented as sample positioning repeatability of 0.1% and a high polarization reproducibility (error margin < 6 in 1000).

  19. Moving systems of polar dimeric capsules out of thermal equilibrium by light irradiation.

    Science.gov (United States)

    Díaz-Moscoso, Alejandro; Arroyave, Frank A; Ballester, Pablo

    2016-02-18

    Heterodimeric capsules self-assembled from tetraurea calix[4]pyrrole and tetraurea calix[4]arene provide unique molecular containers for the organised inclusion of small polar molecules. By inserting stimuli-responsive groups (azobenzene) in the heterocapsule structure, we are able to modify the equilibrium state of the system or the exchange between different host-guest assemblies in a reversible manner.

  20. A method to evaluate residual phase error for polar formatted synthetic aperture radar systems

    Science.gov (United States)

    Musgrove, Cameron; Naething, Richard

    2013-05-01

    Synthetic aperture radar systems that use the polar format algorithm are subject to a focused scene size limit inherent to the polar format algorithm. The classic focused scene size limit is determined from the dominant residual range phase error term. Given the many sources of phase error in a synthetic aperture radar, a system designer is interested in how much phase error results from the assumptions made with the polar format algorithm. Autofocus algorithms have limits to the amount and type of phase error that can be corrected. Current methods correct only one or a few terms of the residual phase error. A system designer needs to be able to evaluate the contribution of the residual or uncorrected phase error terms to determine the new focused scene size limit. This paper describes a method to estimate the complete residual phase error, not just one or a few of the dominant residual terms. This method is demonstrated with polar format image formation, but is equally applicable to other image formation algorithms. A benefit for the system designer is that additional correction terms can be added or deleted from the analysis as necessary to evaluate the resulting effect upon image quality.

  1. Quantum entropy and polarization measurements of the two-photon system

    Science.gov (United States)

    Alexanian, Moorad; Mkrtchian, Vanik E.

    2018-02-01

    We consider the bipartite state of a two-photon polarization system and obtain the exact analytical expression for the von Neumann entropy in the particular case of a five-parameter polarization density matrix. We investigate and graphically illustrate the dependence of the entropy on these five parameters, in particular, the existence of exotic, transition from exotic to nonexotic, and nonexotic states, where the quantum conditional entropy is negative, both positive and negative, and positive, respectively. We study the "cooling" or "heating" effect that follows from the reduced density of photon 2 when a measurement is performed on photon 1.

  2. High-automated system of film data mathematical processing for polarized deuteron experiments

    International Nuclear Information System (INIS)

    Balgansuren, Ya.; Buzdavina, N.A.; Glagolev, V.V.

    1986-01-01

    A specialized software system which allowed to reduce essentially the time of experimental data analysis has been developed in order to provide timely processing of film information in polarized deuteron experiments. With its help preliminary data on deuteron polarization has been obtained in a few months after experiment start up, and the total data processing (15 thousand events) has been carried out in less than in a year from the chamber irradiation time. High rate of data processing has been achieved due to complex automation of all stages of processing

  3. Dynamical model of coherent circularly polarized optical pulse interactions with two-level quantum systems

    International Nuclear Information System (INIS)

    Slavcheva, G.; Hess, O.

    2005-01-01

    We propose and develop a method for theoretical description of circularly (elliptically) polarized optical pulse resonant coherent interactions with two-level atoms. The method is based on the time-evolution equations of a two-level quantum system in the presence of a time-dependent dipole perturbation for electric dipole transitions between states with total angular-momentum projection difference (ΔJ z =±1) excited by a circularly polarized electromagnetic field [Feynman et al., J. Appl. Phys. 28, 49 (1957)]. The adopted real-vector representation approach allows for coupling with the vectorial Maxwell's equations for the optical wave propagation and thus the resulting Maxwell pseudospin equations can be numerically solved in the time domain without any approximations. The model permits a more exact study of the ultrafast coherent pulse propagation effects taking into account the vector nature of the electromagnetic field and hence the polarization state of the optical excitation. We demonstrate self-induced transparency effects and formation of polarized solitons. The model represents a qualitative extension of the well-known optical Maxwell-Bloch equations valid for linearly polarized light and a tool for studying coherent quantum control mechanisms

  4. Polarization Monitoring of the Lens System JVAS B0218+357

    Directory of Open Access Journals (Sweden)

    Andrew Biggs

    2017-10-01

    Full Text Available Monitoring of the lens system JVAS B0218+357 with the Fermi Gamma-ray Space Telescope measured a different time delay to that derived from radio observations. We have re-analysed three months of archival Very Large Array data to produce variability curves with an average sampling of one epoch per day in total flux, polarized flux and polarization position angle (PPA at 15, 8.4 and 5 GHz. The variability is particularly strong in polarized flux. Dense sampling and improved subtraction of the Einstein ring has allowed us to produce superior variability curves and a preliminary analysis has resulted in a time delay (11.5 days which agrees well with the γ -ray value. Both images of 0218+357 are subject to strong Faraday rotation and depolarization as a result of the radio waves passing through the interstellar medium of the spiral lens galaxy. Our data reveal frequency-dependent variations in the PPA that are different in each image and which must therefore result from variable Faraday rotation in the lens galaxy on timescales of a few days. Our analysis has revealed systematic errors in the polarization position angle measurements that strongly correlate with hour angle. Although we have been able to correct for these, we caution that all VLA polarization observations are potentially affected.

  5. Monopolar radiofrequency ablation using a dual-switching system and a separable clustered electrode: Evaluation of the in vivo efficiency

    International Nuclear Information System (INIS)

    Yoon, Jeong Hee; Lee, Jeong Min; Hwang, Eui Jin; Hwang, In Pyung; Beak, Jee Hyun; Han, Joon Koo; Choi, Byung Ihn

    2014-01-01

    To determine the in vivo efficiency of monopolar radiofrequency ablation (RFA) using a dual-switching (DS) system and a separable clustered (SC) electrode to create coagulation in swine liver. Thirty-three ablation zones were created in nine pigs using a DS system and an SC electrode in the switching monopolar mode. The pigs were divided into two groups for two experiments: 1) preliminary experiments (n = 3) to identify the optimal inter-electrode distances (IEDs) for dual-switching monopolar (DSM)-RFA, and 2) main experiments (n = 6) to compare the in vivo efficiency of DSM-RFA with that of a single-switching monopolar (SSM)-RFA. RF energy was alternatively applied to one of the three electrodes (SSM-RFA) or concurrently applied to a pair of electrodes (DSM-RFA) for 12 minutes in in vivo porcine livers. The delivered RFA energy and the shapes and dimensions of the coagulation areas were compared between the two groups. No pig died during RFA. The ideal IEDs for creating round or oval coagulation area using the DSM-RFA were 2.0 and 2.5 cm. DSM-RFA allowed more efficient RF energy delivery than SSM-RFA at the given time (23.0 ± 4.0 kcal vs. 16.92 ± 2.0 kcal, respectively; p 0.0005). DSM-RFA created a significantly larger coagulation volume than SSM-RFA (40.4 ± 16.4 cm 3 vs. 20.8 ± 10.7 cm 3 ; p < 0.001). Both groups showed similar circularity of the ablation zones (p = 0.29). Dual-switching monopolar-radiofrequency ablation using an SC electrode is feasible and can create larger ablation zones than SSM-RFA as it allows more RF energy delivery at a given time.

  6. NOAA's Joint Polar Satellite System's Proving Ground and Risk Reduction Program - Bringing New Capabilities to Operations!

    Science.gov (United States)

    Sjoberg, B.

    2015-12-01

    This presentation will focus on the NOAA Joint Polar Satellite System (JPSS) Program's Proving Ground and Risk Reduction (PGRR) initiative and how it has prepared NOAA users to effectively utilize new polar-orbiting capabilities. The PGRR Program was established in 2012, following the launch of the Suomi National Polar Partnership (SNPP) satellite. Two sets of PGRR Projects have been established grouped together in thirteen different initiatives. Details about how these projects have been continually tailored through the years to meet user requirements, will be highlighted. The presenter will focus on how the success of the first set of PGRR projects have been used to evaluate a follow-on set of projects and focus on exactly what the JPSS user community needs to meet their mission requirements. Details on the Dec 2014 PGRR Call-for-Proposals and the projects selected for funding will be discussed.

  7. Monolithic InP-based fast optical switch module for optical networks of the future

    DEFF Research Database (Denmark)

    Xi, Chen; Regan, James; Durrant, Tim

    2015-01-01

    We summarized the development of Venture Photonics’ sub-10 ns fast optical switch which demonstrates low insertion loss, excellent crosstalk level and polarization independent switching performance.......We summarized the development of Venture Photonics’ sub-10 ns fast optical switch which demonstrates low insertion loss, excellent crosstalk level and polarization independent switching performance....

  8. Experimental demonstration of polar coded IM/DD optical OFDM for short reach system

    Science.gov (United States)

    Fang, Jiafei; Xiao, Shilin; Liu, Ling; Bi, Meihua; Zhang, Lu; Zhang, Yunhao; Hu, Weisheng

    2017-11-01

    In this paper, we propose a novel polar coded intensity modulation direct detection (IM/DD) optical orthogonal frequency division multiplexing (OFDM) system for short reach system. A method of evaluating the channel signal noise ratio (SNR) is proposed for soft-demodulation. The experimental results demonstrate that, compared to the conventional case, ∼9.5 dB net coding gain (NCG) at the bit error rate (BER) of 1E-3 can be achieved after 40-km standard single mode fiber (SSMF) transmission. Based on the experimental result, (512,256) polar code with low complexity and satisfactory BER performance meets the requirement of low latency in short reach system, which is a promising candidate for latency-stringent short reach optical system.

  9. Multiplexed polarization OTDR system with high DOP and ability of multi-event detection.

    Science.gov (United States)

    Wang, Xuefeng; Wang, Chaodong; Tang, Ming; Fu, Songnian; Shum, Perry

    2017-05-01

    A novel polarization optical time domain reflectometry (POTDR) with high degree of polarization is proposed for multi-event detection. By employing multiple 2×2 optical fiber couplers and fiber mirrors, an arbitrary number and customized length of sensing fiber can be multiplexed into the system without modification of the other components, e.g., the light source, photodetector, signal processing device, etc. More importantly, the signal-to-noise ratio of this system is significantly improved, and the temporal depolarization effect can be almost completely suppressed. Additionally, the system response time is considerably reduced by dispensing with data averaging, so that intrusion events such as touching and moving fiber can be detected instantaneously and precisely located. Experiments have been conducted that proved the capability of multi-event simultaneous detection and vibration frequency measurement. This system promises application potential in multi-zone perimeter security and physical field measurement.

  10. Thresholds, switches and hysteresis in hydrology from the pedon to the catchment scale: a non-linear systems theory

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available Hysteresis is a rate-independent non-linearity that is expressed through thresholds, switches, and branches. Exceedance of a threshold, or the occurrence of a turning point in the input, switches the output onto a particular output branch. Rate-independent branching on a very large set of switches with non-local memory is the central concept in the new definition of hysteresis. Hysteretic loops are a special case. A self-consistent mathematical description of hydrological systems with hysteresis demands a new non-linear systems theory of adequate generality. The goal of this paper is to establish this and to show how this may be done. Two results are presented: a conceptual model for the hysteretic soil-moisture characteristic at the pedon scale and a hysteretic linear reservoir at the catchment scale. Both are based on the Preisach model. A result of particular significance is the demonstration that the independent domain model of the soil moisture characteristic due to Childs, Poulavassilis, Mualem and others, is equivalent to the Preisach hysteresis model of non-linear systems theory, a result reminiscent of the reduction of the theory of the unit hydrograph to linear systems theory in the 1950s. A significant reduction in the number of model parameters is also achieved. The new theory implies a change in modelling paradigm.

  11. Expert system in power distribution lines switching; Sistema especialista em manobras de redes de distribuicao de energia eletrica

    Energy Technology Data Exchange (ETDEWEB)

    Cavellucci, Celso

    1989-07-01

    This work proposes an expert system integrated to procedures of numerical computation, denominated RD and projected to suggest alternatives of switching plans in the isolation and re-establishment of power distribution lines. The switching plans are based on the specialist's knowledge (network operator) and in evaluations of the electric conditions of the switching. Specialist's knowledge is represented in the form of triples (context, attribute, value) and production rules, that are evaluated conveniently by the machine of inference of the RD system. The electric power distribution is represented by a graph model, where the knots are load blocks and the arcs are key of the system. The evaluation of the electric requirements (voltage drop and physical capacity of the components of the power distribution lines) it is obtained through a maneuver simulator (numeric computation). The maneuver simulator bases on the Method of the Moments for the calculation of the voltage drop. With base in these ideas a prototype of the RD system was developed.

  12. Multi-Valued Spin Switch in a Semiconductor Microcavity

    Science.gov (United States)

    Paraïso, T. K.; Wouters, M.; Léger, Y.; Morier-Genoud, F.; Deveaudhyphen; Plédran, B.

    2011-12-01

    In this work, we report on the first realization of multi-valued spin switching in the solid-state. We investigate the physics of spinor bistability with microcavity polaritons in a trap. Spinor interactions lead to special bistability regimes with decoupled thresholds for spin-up and spin-down polaritons. This allows us to establish state-of-the-art spin switching operations. We evidence polarization hysteresis and determine appropriate conditions to achieve spin multistability. For a given excitation condition, three stable spin states coexist for the system. These results open new pathways for the development of innovative spin-based logic gates and memory devices.

  13. Development of High Power X-Band Semiconductor RF Switch for Pulse Compression Systems of Future Linear Colliders

    International Nuclear Information System (INIS)

    Tantawi, Sami

    2000-01-01

    We describe development of semiconductor X-band high-power RF switches. The target applications are high-power RF pulse compression systems for future linear colliders. We describe the design methodology of the architecture of the whole switch systems. We present the scaling law that governs the relation between power handling capability and number of elements. We designed and built several active waveguide windows for the active element. The waveguide window is a silicon wafer with an array of four hundred PIN/NIP diodes covering the surface of the window. This waveguide window is located in an over-moded TE01 circular waveguide. The results of high power RF measurements of the active waveguide window are presented. The experiment is performed at power levels of a few megawatts at X-band

  14. The switching-activity estimation of SAD engine for video coding systems

    Science.gov (United States)

    Lee, Yu-Hsuan; Wu, Tsai-Hsing

    2014-10-01

    The sum of absolute difference (SAD) is generally adopted as a cost function in motion estimation (ME) and temporal error concealment (TEC) algorithm owing to its efficiency. The hardware architecture of SAD also consumes considerable power dissipation in video codec chip. Hence, the switching-activity analysis on SAD is quite essential from algorithm/architecture perspectives. This work develops the estimation formulas for switching-activity dedicated for SAD engine according to probability theory. The experiment results reveal that the probability error rate (PER) of the SAD engine is as minor as 5.61%. Consequently, this leads to a precise switching-activity estimation of the SAD-based algorithm/architecture for video signal processing.

  15. Adaptive Synchronization for Heterogeneous Multi-Agent Systems with Switching Topologies

    Directory of Open Access Journals (Sweden)

    Muhammad Ridho Rosa

    2018-02-01

    Full Text Available This work provides a multi-agent extension of output-feedback model reference adaptive control (MRAC, designed to synchronize a network of heterogeneous uncertain agents. The implementation of this scheme is based on multi-agent matching conditions. The practical advantage of the proposed MRAC is the possibility of handling the case of the unknown dynamics of the agents only by using the output and the control input of its neighbors. In addition, it is reasonable to consider the case when the communication topology is time-varying. In this work, the time-varying communication leads to a switching control structure that depends on the number of the predecessor of the agents. By using the switching control structure to handle the time-varying topologies, we show that synchronization can be achieved. The multi-agent adaptive switching controller is first analyzed, and numerical simulations based on formation control of simplifier quadcopter dynamics are provided.

  16. A compact seven switches topology and reduced DC-link capacitor size for single-phase stand-alone PV system with hybrid energy storages

    DEFF Research Database (Denmark)

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

    2011-01-01

    Single-phase stand-alone PV system is suitable for household applications in remote area. Hybrid battery/ultra-capacitor energy storage can reduce charge and discharge cycles and avoid deep discharges of battery. This paper proposes a compact seven switches structure for stand-alone PV system......-order harmonic current caused by single-phase inverter. In the proposed compact topology, a small size DC-link capacitor can achieve the same function through charging/discharging control of ultra-capacitor to mitigate second-order ripple current. Simulation results are provided to validate the effectiveness......, which otherwise needs nine switches configuration, inclusive of one switch for boost converter, four switches for single-phase inverter and four switches for two DC/DC converters of battery and ultra-capacitor. It is well-known that a bulky DC-link capacitor is always required to absorb second...

  17. Design and Implementation of a Novel Control System for Four Quadrant Operation of a Two-Phase Switched Reluctance Motor

    OpenAIRE

    Morse, Justin C.

    2003-01-01

    In the emergence of switched reluctance motors to the commercial market, two-phase motors have received relatively little attention. Higher power and industrial applications have focused on the use of three and occasionally four phase machines, while low cost applications demanding only modest performance have largely been the domain of single phase machines. By contrast, while two phase systems have been the subject of occasional studies, they have not been widely applied. Two phase...

  18. Fault Detection and Location by Static Switches in Microgrids Using Wavelet Transform and Adaptive Network-Based Fuzzy Inference System

    Directory of Open Access Journals (Sweden)

    Ying-Yi Hong

    2014-04-01

    Full Text Available Microgrids are a highly efficient means of embedding distributed generation sources in a power system. However, if a fault occurs inside or outside the microgrid, the microgrid should be immediately disconnected from the main grid using a static switch installed at the secondary side of the main transformer near the point of common coupling (PCC. The static switch should have a reliable module implemented in a chip to detect/locate the fault and activate the breaker to open the circuit immediately. This paper proposes a novel approach to design this module in a static switch using the discrete wavelet transform (DWT and adaptive network-based fuzzy inference system (ANFIS. The wavelet coefficient of the fault voltage and the inference results of ANFIS with the wavelet energy of the fault current at the secondary side of the main transformer determine the control action (open or close of a static switch. The ANFIS identifies the faulty zones inside or outside the microgrid. The proposed method is applied to the first outdoor microgrid test bed in Taiwan, with a generation capacity of 360.5 kW. This microgrid test bed is studied using the real-time simulator eMegaSim developed by Opal-RT Technology Inc. (Montreal, QC, Canada. The proposed method based on DWT and ANFIS is implemented in a field programmable gate array (FPGA by using the Xilinx System Generator. Simulation results reveal that the proposed method is efficient and applicable in the real-time control environment of a power system.

  19. Reversal mechanisms and interactions in magnetic systems: coercivity versus switching field and thermally assisted demagnetization

    Directory of Open Access Journals (Sweden)

    Cebollada, F.

    2005-06-01

    Full Text Available In this paper we present a comparative analysis of the magnetic interactions and reversal mechanisms of two different systems: NdFeB-type alloys with grain sizes in the single domain range and Fe-SiO2 nanocomposites with Fe concentrations above and below the percolation threshold. We evidence that the use of the coercivity as the main parameter to analyse them might be misleading due to the convolution of both reversible and irreversible magnetization variations. We show that the switching field and thermally assisted demagnetization allow a better understanding of these mechanisms since they involve just irreversible magnetization changes. Specifically, the experimental analysis of the coercivity adquisition process for the NdFeB-type system suggests that the magnetization reversal is nucleated at the spin misalignments present due to intergranular exchange interactions. On the other hand, the study of the magnetic viscosity and of the isothermal remanent magnetization (IRM and direct field demagnetization (DCD remanence curves indicates that the dipolar interactions are responsible for the propagation of the switching started at individual particles.

    En este artículo presentamos un análisis comparativo de la influencia de la microestructura a través de las interacciones magnéticas en los mecanismos de inversión de la magnetización en dos sistemas diferentes: aleaciones tipo NdFeB con tamaños de grano en el rango de monodominio y nanocompuestos de Fe-SiO2 con concentraciones de Fe tanto por encima como por debajo del umbral de percolación. Ponemos de manifiesto que el uso del campo coercitivo como parámetro de análisis puede llevar a equívocos debido a la coexistencia de variaciones reversibles e irreversibles de la magnetización. También mostramos que el campo de conmutación y la desimanación térmicamente asistida permiten una mejor comprensión de dichos mecanismos ya que reflejan exclusivamente cambios irreversibles de

  20. Understanding the effects of electronic polarization and delocalization on charge-transport levels in oligoacene systems

    KAUST Repository

    Sutton, Christopher

    2017-06-13

    Electronic polarization and charge delocalization are important aspects that affect the charge-transport levels in organic materials. Here, using a quantum mechanical/ embedded-charge (QM/EC) approach based on a combination of the long-range corrected omega B97X-D exchange-correlation functional (QM) and charge model 5 (CM5) point-charge model (EC), we evaluate the vertical detachment energies and polarization energies of various sizes of crystalline and amorphous anionic oligoacene clusters. Our results indicate that QM/EC calculations yield vertical detachment energies and polarization energies that compare well with the experimental values obtained from ultraviolet photoemission spectroscopy measurements. In order to understand the effect of charge delocalization on the transport levels, we considered crystalline naphthalene systems with QM regions including one or five-molecules. The results for these systems show that the delocalization and polarization effects are additive; therefore, allowing for electron delocalization by increasing the size of the QM region leads to the additional stabilization of the transport levels. Published by AIP Publishing.

  1. A Double-Switch Cell Fusion-Inducible Transgene Expression System for Neural Stem Cell-Based Antiglioma Gene Therapy

    Directory of Open Access Journals (Sweden)

    Yumei Luo

    2015-01-01

    Full Text Available Recent progress in neural stem cell- (NSC- based tumor-targeted gene therapy showed that NSC vectors expressing an artificially engineered viral fusogenic protein, VSV-G H162R, could cause tumor cell death specifically under acidic tumor microenvironment by syncytia formation; however, the killing efficiency still had much room to improve. In the view that coexpression of another antitumoral gene with VSV-G can augment the bystander effect, a synthetic regulatory system that triggers transgene expression in a cell fusion-inducible manner has been proposed. Here we have developed a double-switch cell fusion-inducible transgene expression system (DoFIT to drive transgene expression upon VSV-G-mediated NSC-glioma cell fusion. In this binary system, transgene expression is coregulated by a glioma-specific promoter and targeting sequences of a microRNA (miR that is highly expressed in NSCs but lowly expressed in glioma cells. Thus, transgene expression is “switched off” by the miR in NSC vectors, but after cell fusion with glioma cells, the miR is diluted and loses its suppressive effect. Meanwhile, in the syncytia, transgene expression is “switched on” by the glioma-specific promoter. Our in vitro and in vivo experimental data show that DoFIT successfully abolishes luciferase reporter gene expression in NSC vectors but activates it specifically after VSV-G-mediated NSC-glioma cell fusion.

  2. Switching Device Dead Time Optimization of Resonant Double-Sided LCC Wireless Charging System for Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Xi Zhang

    2017-11-01

    Full Text Available Aiming at the reduction of the influence of the dead time setting on power level and efficiency of the inverter of double-sided LCC resonant wireless power transfer (WPT system, a dead time soft switching optimization method for metal–oxide–semiconductor field-effect transistor (MOSFET is proposed. At first, the mathematic description of double-sided LCC resonant wireless charging system is established, and the operating mode is analyzed as well, deducing the quantitative characteristic that the secondary side compensation capacitor C2 can be adjusted to ensure that the circuit is inductive. A dead time optimization design method is proposed, contributing to achieving zero-voltage switching (ZVS of the inverter, which is closely related to the performance of the WPT system. In the end, a prototype is built. The experimental results verify that dead time calculated by this optimized method can ensure the soft switching of the inverter MOSFET and promote the power and efficiency of the WPT.

  3. Pseudospark switches

    International Nuclear Information System (INIS)

    Billault, P.; Riege, H.; Gulik, M. van; Boggasch, E.; Frank, K.

    1987-01-01

    The pseudospark discharge is bound to a geometrical structure which is particularly well suited for switching high currents and voltages at high power levels. This type of discharge offers the potential for improvement in essentially all areas of switching operation: peak current and current density, current rise, stand-off voltage, reverse current capability, cathode life, and forward drop. The first pseudospark switch was built at CERN at 1981. Since then, the basic switching characteristics of pseudospark chambers have been studied in detail. The main feature of a pseudospark switch is the confinement of the discharge plasma to the device axis. The current transition to the hollow electrodes is spread over a rather large surface area. Another essential feature is the easy and precise triggering of the pseudospark switch from the interior of the hollow electrodes, relatively far from the main discharge gap. Nanosecond delay and jitter values can be achieved with trigger energies of less than 0.1 mJ, although cathode heating is not required. Pseudospark gaps may cover a wide range of high-voltage, high-current, and high-pulse-power switching at repetition rates of many kilohertz. This report reviews the basic researh on pseudospark switches which has been going on at CERN. So far, applications have been developed in the range of thyratron-like medium-power switches at typically 20 to 40 kV and 0.5 to 10 kA. High-current pseudospark switches have been built for a high-power 20 kJ pulse generator which is being used for long-term tests of plasma lenses developed for the future CERN Antiproton Collector (ACOL). The high-current switches have operated for several hundred thousand shots, with 20 to 50 ns jitter at 16 kV charging voltage and more than 100 kA peak current amplitude. (orig.)

  4. Issue evolution and partisan polarization in a European multiparty system: Elite and mass repositioning in Denmark 1968–2011

    DEFF Research Database (Denmark)

    Arndt, Christoph

    2016-01-01

    Issue evolution is a well-established theoretical perspective in the analysis of long-term party competition and partisanship in the US. However, this perspective has rarely been used to analyze political elite effects on partisan polarization in European multiparty systems. Consequently, I apply...... the issue evolution perspective to polarization in a European multiparty system. I find an emergence of cultural issues in Denmark, where mass level polarization on cultural issues followed elite level polarization. Unlike two-party systems, niche parties drive issue evolution on the elite level, which...... is then followed by niche partisan polarization and, finally, mainstream party adaption. The findings illustrate the mechanisms of issue evolution in a European-style multiparty system and the role of niche parties....

  5. Tunable 13C/1H dual channel matching circuit for dynamic nuclear polarization system with cross-polarization

    DEFF Research Database (Denmark)

    Rybalko, Oleksandr; Bowen, Sean; Zhurbenko, Vitaliy

    2016-01-01

    In this paper we report initial results of design and practical implementation of tuning and matching circuit to estimate a performance of Dynamic Nuclear Polarization (DNP) at a magnetic field of 6.7 T. It is shown that developed circuit for signal observation is compact, easy to make and provides...

  6. A Hamiltonian viewpoint in the modelling of switching power converters, Special Issue on Hybrid Systems

    NARCIS (Netherlands)

    Escobar, Gerardo; van der Schaft, Arjan; Ortega, Romeo

    1999-01-01

    In this paper we show how, using the Hamiltonian formalism, we can systematically derive mathematical models that describe the behaviour of a large class of switching power converters, including the “Boost”, “Buck”, “Buck-Boost”, “ uk” and “Flyback” converters. We follow the approach proposed by van

  7. Joint switched transmit diversity and adaptive modulation in spectrum sharing systems

    KAUST Repository

    Qaraqe, Khalid A.

    2011-01-01

    Under the scenario of an underlay cognitive radio network, we propose in this paper an adaptive scheme using switched transmit diversity and adaptive modulation in order to minimize the average number of switched branches at the secondary transmitter while increasing the capacity of the secondary link. The proposed switching efficient scheme (SES) uses the scan and wait (SWC) combining technique where a transmission occurs only when a branch with an acceptable performance is found, otherwise data is buffered. In our scheme, the modulation constellation size and the used transmit branch are determined to achieve the highest spectral efficiency with a minimum processing power, given the fading channel conditions, the required error rate performance, and a peak interference constraint to the primary receiver. Selected numerical examples show that the SES scheme minimizes the average number of switched branches for the average and the high secondary signal-to-noise ratio range. This improvement comes at the expense of a small delay introduced by the SWC technique. For reference, we also compare the performance of the SES scheme to the selection diversity scheme (SDS) where the best branch verifying the modulation mode and the interference constraint is always selected. © 2011 ICST.

  8. Resistive switching in mixed conductors : Ag2S as a model system

    NARCIS (Netherlands)

    Morales Masis, Monica

    2012-01-01

    Resistive switching memories have gained an increased interest due to the possibilities for downscaling of memory devices down to a few nanometers. These memories consist of a resistive material sandwiched between two metal electrodes, and applying a voltage between them induces resistance

  9. Switching antidepressants

    African Journals Online (AJOL)

    depressive disorder, with response rates of 50-60%. Switching within or between classes of antidepressants is often required in patients with an insufficient response to SSRIs.12 Because they share a similar mechanism of action, the immediate substitution of one SSRI for another is probably the easiest switching option.

  10. Rad-hard vertical JFET switch for the HV-MUX system of the ATLAS upgrade Inner Tracker

    CERN Document Server

    Fernandez-Martinez, Pablo; Flores, David; Hidalgo, Salvador; Quirion, David; Lynn, David

    2016-01-01

    This work presents a new silicon vertical JFET (V-JFET) device, based on the trenched 3D-detector technology developed at IMB-CNM, to be used as switches for the High-Voltage powering scheme of the ATLAS upgrade Inner Tracker. The optimization of the device characteristics is performed by 2D and 3D TCAD simulations. Special attention has been paid to the on-resistance and the switch-off and breakdown voltages to meet the specific requirements of the system. In addition, a set of parameter values has been extracted from the simulated curves to implement a SPICE model of the proposed V-JFET transistor. As these devices are expected to operate under very high radiation conditions during the whole experiment life-time, a study of the radiation damage effects and the expected degradation on the device performance is also presented at the end of the paper.

  11. Research on Polarization Cancellation of Nonstationary Ionosphere Clutter in HF Radar System

    Directory of Open Access Journals (Sweden)

    Xingpeng Mao

    2015-01-01

    Full Text Available Oblique projection polarization filter (OPPF can be applied as an effective approach for interference cancellation in high-frequency surface wave radar (HFSWR and other systems. In order to suppress the nonstationary ionosphere clutter further, a novel OPPF based clutter suppressing scheme is proposed in this paper. The polarization and nonstationary characteristic of the clutter are taken into account in the algorithms referred to as range-Doppler domain polarization suppression (RDDPS and the range-time domain polarization suppression (RTDPS method, respectively. The RDDPS is designed for weak ionosphere clutter and implemented in the range-Doppler domain directly, whereas the RTDPS algorithm is designed to suppress the powerful ionosphere clutter with a multisegment estimation and suppression scheme. About 15–23 dB signal to interference ratio (SIR improvement can be excepted when using the proposed method, whereas the targets can be more easily detected in the range-Doppler map. Experimental results demonstrate that the scheme proposed is effective for nonstationary ionosphere clutter and is proven to be a practical interference cancellation technique for HFSWR.

  12. A portable liquid crystal-based polarized light system for the detection of organophosphorus nerve gas

    Science.gov (United States)

    He, Feng Jie; Liu, Hui Long; Chen, Long Cong; Xiong, Xing Liang

    2018-03-01

    Liquid crystal (LC)-based sensors have the advantageous properties of being fast, sensitive, and label-free, the results of which can be accessed directly only through the naked eye. However, the inherent disadvantages possessed by LC sensors, such as relying heavily on polarizing microscopes and the difficulty to quantify, have limited the possibility of field applications. Herein, we have addressed these issues by constructing a portable polarized detection system with constant temperature control. This system is mainly composed of four parts: the LC cell, the optics unit, the automatic temperature control unit, and the image processing unit. The LC cell was based on the ordering transitions of LCs in the presence of analytes. The optics unit based on the imaging principle of LCs was designed to substitute the polarizing microscope for the real-time observation. The image processing unit is expected to quantify the concentration of analytes. The results have shown that the presented system can detect dimethyl methyl phosphonate (a stimulant for organophosphorus nerve gas) within 25 s, and the limit of detection is about 10 ppb. In all, our portable system has potential in field applications.

  13. Proinflammatory-Activated Glioma Cells Induce a Switch in Microglial Polarization and Activation Status, From a Predominant M2b Phenotype to a Mixture of M1 and M2a/B Polarized Cells

    Directory of Open Access Journals (Sweden)

    Lucia Lisi

    2014-04-01

    Full Text Available Malignant gliomas are primary brain tumors characterized by morphological and genetic complexities, as well as diffuse infiltration into normal brain parenchyma. Within gliomas, microglia/macrophages represent the largest tumor-infiltrating cell population, contributing by at least one-third to the total tumor mass. Bi-directional interactions between glioma cells and microglia may therefore play an important role on tumor growth and biology. In the present study, we have characterized the influence of glioma-soluble factors on microglial function, comparing the effects of media harvested under basal conditions with those of media obtained after inducing a pro-inflammatory activation state in glioma cells. We found that microglial cells undergo a different pattern of activation depending on the stimulus; in the presence of activated glioma-derived factors, i.e. a condition mimicking the late stage of pathology, microglia presents as a mixture of polarization phenotypes (M1 and M2a/b, with up-regulation of iNOS (inducible nitric oxide synthase, ARG (arginase and IL (interleukine-10. At variance, microglia exposed to basal glioma-derived factors, i.e. a condition resembling the early stage of pathology, shows a more specific pattern of activation, with increased M2b polarization status and up-regulation of IL-10 only. As far as viability and cell proliferation are concerned, both LI-CM [LPS (lipopolysaccharide—IFNγ (interferon γ conditioned media] and C-CM (control-conditioned media induce similar effects on microglial morphology. Finally, in human glioma tissue obtained from surgical resection of patients with IV grade glioblastoma, we detected a significant amount of CD68 positive cells, which is a marker of macrophage/microglial phagocytic activity, suggesting that in vitro findings presented here might have a relevance in the human pathology as well.

  14. Use of the Polarized Radiance Distribution Camera System in the RADYO Program

    Science.gov (United States)

    2011-01-28

    polarizer’s (Melles Griot , 03 FPG 019). Polarizer’s are orientated at 0 deg, 60 deg, and 120 deg (angles relative to the first polarizer). The combination...combination of a broadband mica quarter wave plate (Melles Griot , 02 WRM001) and a polarizer to form a circular polarization analyzer. The combination of the

  15. Lateral refraction and reflection of light polarized lenses principle. Coplanar lens systems

    International Nuclear Information System (INIS)

    Miranda, L.

    2012-01-01

    Studying the behavior of the linearly polarized light to impact a lens and in the lens itself, resulted in the discovery of a physical principle of optics, not mentioned or used so far. This phenomenon is very useful in practice. Perhaps the manifestation of the phenomenon occurs in the plane perpendicular to the road or optical axis, is due the reason that was not seen before, but it has always been there when polarized light passes through a lens. Known and mastered the principle has been manipulated for better research results, using for the first time a planar lens system, which according to the placement of the lens allows for accurate lags between the light beams ar the exits the system. (Author)

  16. Symmetry evaluation for an interferometric fiber optic gyro coil utilizing a bidirectional distributed polarization measurement system.

    Science.gov (United States)

    Peng, Feng; Li, Chuang; Yang, Jun; Hou, Chengcheng; Zhang, Haoliang; Yu, Zhangjun; Yuan, Yonggui; Li, Hanyang; Yuan, Libo

    2017-07-10

    We propose a dual-channel measurement system for evaluating the optical path symmetry of an interferometric fiber optic gyro (IFOG) coil. Utilizing a bidirectional distributed polarization measurement system, the forward and backward transmission performances of an IFOG coil are characterized simultaneously by just a one-time measurement. The simple but practical configuration is composed of a bidirectional Mach-Zehnder interferometer and multichannel transmission devices connected to the IFOG coil under test. The static and dynamic temperature results of the IFOG coil reveal that its polarization-related symmetric properties can be effectively obtained with high accuracy. The optical path symmetry investigation is highly beneficial in monitoring and improving the winding technology of an IFOG coil and reducing the nonreciprocal effect of an IFOG.

  17. An IIR adaptive electronic equalizer for polarization multiplexed fiber optic communication systems

    Science.gov (United States)

    Zeng, Xiang-Ye; Liu, Jian-Fei; Zhao, Qi-Da

    2011-09-01

    An electronic digital equalizer for polarization multiplex coherent fiber optic communication systems is designed to compensate polarization mode dispersion (PMD) and residual chromatic dispersion (CD) of transmission channel. The proposed equalizer is realized with fraction spaced infinite impulse response (IIR) butterfly structure with 21 feedforward taps and 2 feedback taps. Compared with finite impulse response (FIR) structure, this structure can reduce implementation complexity of hardware under the same condition. To keep track of the random variation of channel characteristics, the filter weights are updated by least mean square (LMS) algorithm. The simulation results show that the proposed equalizer can compensate residual chromatic dispersion (CD) of 1600 ps/nm and differential group delay (DGD) of 90 ps simultaneously, and also can increase the PMD and residual CD tolerance of the whole communication system.

  18. Activities and Issues of a Developed Information System for the Italian Polar Research

    Directory of Open Access Journals (Sweden)

    A Damiani

    2010-02-01

    Full Text Available Activities performed to develop an information system for the diffusion of Italian polar research (SIRIA project are here described. The system collects and shares information related to research projects carried out in both the Antarctic (since 1985 and Arctic (since 1997 regions. It is addressed primarily to dedicated users in order to foster interdisciplinary research but non-specialists may also be interested in the major results. SIRIA is in charge of managing the National Antarctic Data Center of Italy and confers its metadata to the Antarctic Master Directory. Since 2003, the National Antarctic Research Program has funded this project, which, by restyling its tasks, databases, and web site, is becoming the portal of Italian polar research. Issues concerning data management and policy in Italy are also covered.

  19. Optical computer switching network

    Science.gov (United States)

    Clymer, B.; Collins, S. A., Jr.

    1985-01-01

    The design for an optical switching system for minicomputers that uses an optical spatial light modulator such as a Hughes liquid crystal light valve is presented. The switching system is designed to connect 80 minicomputers coupled to the switching system by optical fibers. The system has two major parts: the connection system that connects the data lines by which the computers communicate via a two-dimensional optical matrix array and the control system that controls which computers are connected. The basic system, the matrix-based connecting system, and some of the optical components to be used are described. Finally, the details of the control system are given and illustrated with a discussion of timing.

  20. Capillary column switching restricted-access media-liquid chromatography-electrospray ionization-tandem mass spectrometry system for simultaneous and direct analysis of drugs in biofluids.

    Science.gov (United States)

    Santos-Neto, Alvaro J; Markides, Karin E; Sjöberg, Per J R; Bergquist, Jonas; Lancas, Fernando M

    2007-08-15

    Capillary online restricted-access media-liquid chromatography-electrospray ionization-tandem mass spectrometry (RAM-LC-ESI-MS/MS) for direct analysis of drugs and metabolites spiked in biological fluids was developed. Using a column switching setup it was possible to perform effective sample preparation and analysis of raw biological fluids (plasma and urine) without matrix effects in the electrospray mass spectrometric detection step. The peak focusing efficiency of the extraction column was more effective in backflush compared to foreflush mode. The system was able to concentrate diminished samples of polar drugs and their metabolites reaching quantifiable results as low as 1 ng/mL utilizing a sample volume of only 333 nL of biofluids. New column hardware was developed to circumvent clogging problems experienced with plasma injections. The glass fiber filter frit, which is commonly used, was replaced with a short piece of 20 microm i.d. fused silica capillary. The extraction columns were able to handle up to 60 injections and showed a high loading capacity, making the saturation of the MS detector the limiting factor on the linear dynamic range. The simultaneous separation and detection of 10 drugs and metabolites was obtained in 8 min of analysis, including the online sample preparation and enrichment step.

  1. Two-dimensional spatially ordered system of nickel nanowires probed by polarized SANS

    International Nuclear Information System (INIS)

    Napolskii, K.S.; Chumakov, A.P.; Grigoriev, S.V.; Grigoryeva, N.A.; Eckerlebe, H.; Eliseev, A.A.; Lukashin, A.V.; Tretyakov, Yu.D.

    2009-01-01

    Structural and magnetic properties of two-dimensional spatially ordered system of ferromagnetic nickel nanowires embedded into Al 2 O 3 matrix have been studied using polarized small-angle neutron scattering. The small-angle diffraction pattern exhibits many diffraction peaks, which corresponds to the scattering from highly correlated hexagonal structure of pores and magnetic nanowires. Magnetic contribution to the scattering has complex behavior and cannot be explained without taking into account stray fields located between magnetized nanowires.

  2. Resistive switching in individual ZnO nanorods: delineating the ionic current by photo-stimulation

    Science.gov (United States)

    Bandopadhyay, K.; Prajapati, K. N.; Mitra, J.

    2018-03-01

    Resistive switching in nanostructured metal oxide semiconductors has been broadly understood to originate from the dynamics of its native point defects. Experimental results of switching observed in individual n-ZnO nanorods grown on a p-type polymer is presented along with an empirical model describing the underlying defect dynamics necessary to observe bi-polar switching. Selective photo excitation of electrons into the defect states delineates the incidence and role of an ionic current in the switching behavior. The understanding further extends to the observance of a negative differential resistance regime that is often coincident in such systems. The analysis not only unifies the underlying physics of the two phenomena but also offers further confidence in the proposed mechanism. We conclude by demonstrating that the effective memresistance of such devices is a strong function of the operating bias and identify parameters that optimize switching performance.

  3. Introduction to the next generation EUMETSAT Polar System (EPS-SG) observation missions

    Science.gov (United States)

    Schlüssel, Peter; Kayal, Gökhan

    2017-09-01

    EUMETSAT is conducting the activities for the development of the second generation EUMETSAT Polar System Second Generation (EPS-SG), to replace the current EPS from 2021 onwards and contribute to the Joint Polar System to be set up with NOAA. EPS-SG covers nine observation missions in support of operational meteorology and climate monitoring. The observation missions will be supported by ten instruments that will be carried by a two-satellite system. The Metop Second Generation (Metop-SG) satellites will occupy the same orbit as their Metop predecessors in a Sun synchronous, low earth orbit at 820 km altitude and 09:30 descending equatorial crossing time. The observation missions will be implemented by multi-spectral optical and polarisation imaging, atmospheric sounding in the optical and microwave spectral domains, radio occultation sounding, scatterometry as well as microwave and sub-millimetre-wave imaging. Two polar ground stations will receive global data from both satellites. A network of direct-broadcast reception stations will allow to support a North-Atlantic/European regional mission with high timeliness. Additionally, raw mission data are continuously broadcasted to local users world-wide. Global and regional data will be processed at EUMETSAT into well-calibrated and geo-located sensor data, and further on into geophysical products. All data will be disseminated to users in near-real time and archived in the EUMETSAT Data Centre for later retrieval by users.

  4. Feeding and wounding responses in Hydra suggest functional and structural polarization of the tentacle nervous system.

    Science.gov (United States)

    Shimizu, H

    2002-03-01

    The nervous system of Hydra, a freshwater cnidaria, occurs as dispersed, or diffuse, nerve net throughout the animal. It is widely accepted that in a diffuse nervous system an external stimulus is conducted in all directions over the net. Here I report observations that hydra tentacles respond to feeding and wounding stimuli in a unidirectional manner. Upon contact of a tentacle with a brine shrimp larva during feeding, tissue on the proximal side of the point of contact contracted strongly, whereas tissue on the distal side contracted only very weakly. Feeding a tentacle to which a second tentacle was grafted to the proximal end in the reversed orientation showed that unidirectional conduction, once initiated, was blocked by the reversal of polarity, demonstrating that the distal to proximal polarity of tissue is crucial for unidirectional conduction. Unidirectional conduction was obtained also by mechanically pinching the tissue. The response of tentacles devoid of neurons examined was bidirectional, demonstrating that the nervous system is responsible for the unidirectional responses. These observations suggest that polarized property of the nerve net in hydra tentacles is responsible for the unidirectional tentacle contraction.

  5. System for producing high-resolution polarized and unpolarized beams with a tandem accelerator

    International Nuclear Information System (INIS)

    Westerfeldt, C.R.; Bilpuch, E.G.; Bleck, M.E.; Outlaw, D.A.; Wells, W.K.; Wilkerson, J.F.; Clegg, T.B.

    1983-01-01

    A tandem accelerator beam energy stabilizer, which utilizes an optically coupled fast feedback loop to the accelerator terminal stripper, is described. Emphasis is placed on the components of the feedback system and on the application of this system to production of high energy-resolution beams. This system produces beam energy spreads ranging from 450 to 600 eV FWHM for 2 to 16 MeV unpolarized protons. Polarized beam energy spreads range from 550 to 700 eV FWHM, for the same beam energy range

  6. Orthonormal polynomials describing polarization aberration for M-fold optical systems.

    Science.gov (United States)

    Xu, Xiangru; Huang, Wei; Xu, Mingfei

    2016-03-07

    Polarization aberration (PA) is a serious issue that affects imaging quality for optical systems with high numerical aperture. Numerous studies have focused on the distribution rule of PA on the pupil, but the field remains poorly studied. We previously developed an orthonormal set of polynomials to reveal the pupil and field dependences of PA in rotationally symmetric optical systems. However, factors, such as intrinsic birefringence of cubic crystalline material in deep ultraviolet optics and tolerance, break the rotational symmetry of PA. In this paper, we extend the polynomials from rotationally symmetric to M-fold to describe the PA of M-fold optical systems. Two examples are presented to verify the polynomials.

  7. A Biological-Realtime Neuromorphic System in 28 nm CMOS Using Low-Leakage Switched Capacitor Circuits.

    Science.gov (United States)

    Mayr, Christian; Partzsch, Johannes; Noack, Marko; Hänzsche, Stefan; Scholze, Stefan; Höppner, Sebastian; Ellguth, Georg; Schüffny, Rene

    2016-02-01

    A switched-capacitor (SC) neuromorphic system for closed-loop neural coupling in 28 nm CMOS is presented, occupying 600 um by 600 um. It offers 128 input channels (i.e., presynaptic terminals), 8192 synapses and 64 output channels (i.e., neurons). Biologically realistic neuron and synapse dynamics are achieved via a faithful translation of the behavioural equations to SC circuits. As leakage currents significantly affect circuit behaviour at this technology node, dedicated compensation techniques are employed to achieve biological-realtime operation, with faithful reproduction of time constants of several 100 ms at room temperature. Power draw of the overall system is 1.9 mW.

  8. Robust Stability and H∞ Stabilization of Switched Systems with Time-Varying Delays Using Delta Operator Approach

    Directory of Open Access Journals (Sweden)

    Chen Qin

    2013-01-01

    Full Text Available This paper considers the problems of the robust stability and robust H∞ controller design for time-varying delay switched systems using delta operator approach. Based on the average dwell time approach and delta operator theory, a sufficient condition of the robust exponential stability is presented by choosing an appropriate Lyapunov-Krasovskii functional candidate. Then, a state feedback controller is designed such that the resulting closed-loop system is exponentially stable with a guaranteed H∞ performance. The obtained results are formulated in the form of linear matrix inequalities (LMIs. Finally, a numerical example is provided to explicitly illustrate the feasibility and effectiveness of the proposed method.

  9. Permanence and asymptotic behaviors of stochastic predator-prey system with Markovian switching and Lévy noise

    Science.gov (United States)

    Wang, Sheng; Wang, Linshan; Wei, Tengda

    2018-04-01

    This paper concerns the dynamics of a stochastic predator-prey system with Markovian switching and Lévy noise. First, the existence and uniqueness of global positive solution to the system is proved. Then, by combining stochastic analytical techniques with M-matrix analysis, sufficient conditions of stochastic permanence and extinction are obtained. Furthermore, for the stochastic permanence case, by means of four constants related to the stationary probability distribution of the Markov chain and the parameters of the subsystems, both the superior limit and the inferior limit of the average in time of the sample path of the solution are estimated. Finally, our conclusions are illustrated through an example.

  10. Application of Theory of Hybrid Systems to Control the Switching of Buck Converter

    KAUST Repository

    Benmiloud, Mohammed

    2013-08-01

    The field of power electronics poses challenging control problems that can’t be treated in a complete manner using traditional modeling. In this paper, the buck converter operating in Continuous Conduction Mode (CCM) is represented analytically by hybrid automaton model and graphically representation is also given. The hybrid trajectory and the model behavior are presented. The control problem of buck switching converters is transformed to a guard selection problem. The guard selection calculation formulas of buck converter are derived from the basic circuit laws. The stability of the switching is established analytically by the use of multiple Lyapunov functions to ensure the convergence and Poincare map to assess the local stability of the limit cycle. Numerical results clearly bring out the advantages and effectiveness of the proposed control law under varying line voltage and load conditions. Simulation studies are carried out in Matlab/Simulink/Stateflow.

  11. Vibrating mirror system suitable for q-switching large-aperture lasers

    Energy Technology Data Exchange (ETDEWEB)

    Beckwith, P.J.

    1977-11-01

    Resonant vibrating mirrors provide a convenient means of Q-switching a laser, but large-aperture versions require careful design if the drive power is not to become excessive. This report outlines the design principles involved in the optimisation of moving-iron galvanometer drivers, and describes a prototype device with an aperture of 40 mm x 80 mm which is capable of beam deflections of + or - 40 mrad at 800 Hz. Some suggestions are made concerning more refined designs.

  12. Single-Photon Switching and Entanglement of Solid- State Qubits in an Integrated Nanophotonic System

    Science.gov (United States)

    Evans, Ruffin; Sipahigil, Alp; Sukachev, Denis; Burek, Michael; Borregaard, Johannes; Bhaskar, Mihir; Nguyen, Christian; Pacheco, Jose; Bielejec, Edward; Loncar, Marko; Lukin, Mikhail

    2017-04-01

    Efficient interfaces between photons and quantum emitters form the basis for quantum networks and enable optical nonlinearities at the single-photon level. We demonstrate a platform for scalable quantum nanophotonics based on silicon-vacancy (SiV) color centers coupled to diamond nanodevices. By placing SiV centers inside diamond photonic crystal cavities, we realize a quantum-optical switch controlled by a single color center. We control the switch using SiV metastable states and observe switching at the single-photon level. Raman transitions are used to realize a single-photon source with a tunable frequency and bandwidth in a diamond waveguide. By measuring intensity correlations of indistinguishable Raman photons emitted into a single waveguide, we observe quantum interference resulting from the superradiant emission of two entangled SiV centers. We also discuss current work to extend the coherence time of the SiV spin degree of freedom, engineer deterministic multi-emitter interactions via the cavity mode, and related work with the Germanium-Vacancy center.

  13. Versatile lipid profiling by liquid chromatography-high resolution mass spectrometry using all ion fragmentation and polarity switching. Preliminary application for serum samples phenotyping related to canine mammary cancer.

    Science.gov (United States)

    Gallart-Ayala, H; Courant, F; Severe, S; Antignac, J-P; Morio, F; Abadie, J; Le Bizec, B

    2013-09-24

    Lipids represent an extended class of substances characterized by such high variety and complexity that makes their unified analyses by liquid chromatography coupled to either high resolution or tandem mass spectrometry (LC-HRMS or LC-MS/MS) a real challenge. In the present study, a new versatile methodology associating ultra high performance liquid chromatography coupled to high resolution tandem mass spectrometry (UHPLC-HRMS/MS) have been developed for a comprehensive analysis of lipids. The use of polarity switching and "all ion fragmentation" (AIF) have been two action levels particularly exploited to finally permit the detection and identification of a multi-class and multi-analyte extended range of lipids in a single run. For identification purposes, both higher energy collision dissociation (HCD) and in-source CID (collision induced dissociation) fragmentation were evaluated in order to obtain information about the precursor and product ions in the same spectra. This approach provides both class-specific and lipid-specific fragments, enhancing lipid identification. Finally, the developed method was applied for differential phenotyping of serum samples collected from pet dogs developing spontaneous malignant mammary tumors and health controls. A biological signature associated with the presence of cancer was then successfully revealed from this lipidome analysis, which required to be further investigated and confirmed at larger scale. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Latency features of SafetyNet ground systems architecture for the National Polar-orbiting Operational Environmental Satellite System (NPOESS)

    Science.gov (United States)

    Duda, James L.; Mulligan, Joseph; Valenti, James; Wenkel, Michael

    2005-01-01

    A key feature of the National Polar-orbiting Operational Environmental Satellite System (NPOESS) is the Northrop Grumman Space Technology patent-pending innovative data routing and retrieval architecture called SafetyNetTM. The SafetyNetTM ground system architecture for the National Polar-orbiting Operational Environmental Satellite System (NPOESS), combined with the Interface Data Processing Segment (IDPS), will together provide low data latency and high data availability to its customers. The NPOESS will cut the time between observation and delivery by a factor of four when compared with today's space-based weather systems, the Defense Meteorological Satellite Program (DMSP) and NOAA's Polar-orbiting Operational Environmental Satellites (POES). SafetyNetTM will be a key element of the NPOESS architecture, delivering near real-time data over commercial telecommunications networks. Scattered around the globe, the 15 unmanned ground receptors are linked by fiber-optic systems to four central data processing centers in the U. S. known as Weather Centrals. The National Environmental Satellite, Data and Information Service; Air Force Weather Agency; Fleet Numerical Meteorology and Oceanography Center, and the Naval Oceanographic Office operate the Centrals. In addition, this ground system architecture will have unused capacity attendant with an infrastructure that can accommodate additional users.

  15. Optical polarization modulation by competing atomic coherence effects in a degenerate four-level Yb atomic system

    International Nuclear Information System (INIS)

    Park, Sung Jong; Park, Chang Yong; Yoon, Tai Hyun

    2005-01-01

    A scheme of optical polarization modulation of a linearly polarized infrared probe field is studied in a degenerate four-level Yb atomic system. We have observed an anomalous transmission spectra of two circular polarization components of the probe field exhibiting an enhanced two-photon absorption and a three-photon gain with comparable magnitude, leading to the lossless transmission and enhanced circular dichroism. We carried out a proof-of-principle experiment of fast optical polarization modulation in such a system by modulating the polarization state of the coupling field. The observed enhanced two-photon absorption and three-photon gain of the probe field are due to the result of competing atomic coherence effects

  16. Spin temperatures under dynamic polarization in a one-dimensional system, the TANOL

    International Nuclear Information System (INIS)

    Barjhoux, Yves.

    1974-01-01

    A quantitative model of Tanol submitted to dynamic polarization has been developed. The spin systems are described using a network of interconnected reservoirs. The model involves six (or ten) Zeeman nuclear reservoirs mutually coupled by nuclear-nuclear dipole interactions and coupled to electron spins by hyperfine interactions. When the electronic line is saturated, different nuclear temperatures appear in the molecule. These temperatures have been calculated as a function of the magnetic field orientation against the crystallographic axes. Experimental results are correctly reproduced. A quantitative agreement is obtained for the anisotropy of total polarization. The calculation also shows that, in certain directions, positive and negative spin temperatures simultaneously appear, that explains the complex shape of the signals observed. Nuclear relaxation processes involving two electron spins of the same exchange chain are taken into account for the calculation. The different possible chain directions (a, a+c, or c vectors) were envisaged. Only the c-vector hypothesis succeeded in interpreting experimental results [fr

  17. uv preilluminated gas switches

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, L.P.; Orham, E.L.; Stowers, I.F.; Braucht, J.R.

    1980-06-03

    We have designed, built, and characterized uv preilluminated gas switches for a trigger circuit and a low inductance discharge circuit. These switches have been incorporated into a 54 x 76 x 150 cm pulser module to produce a 1 Ma output current rising at 5 x 10/sup 12/ amps/sec with 1 ns jitter. Twenty such modules will be used on the Nova Inertial Confinement Fusion Laser System for plasma retropulse shutters.

  18. uv preilluminated gas switches

    International Nuclear Information System (INIS)

    Bradley, L.P.; Orham, E.L.; Stowers, I.F.; Braucht, J.R.

    1980-01-01

    We have designed, built, and characterized uv preilluminated gas switches for a trigger circuit and a low inductance discharge circuit. These switches have been incorporated into a 54 x 76 x 150 cm pulser module to produce a 1 Ma output current rising at 5 x 10 12 amps/sec with 1 ns jitter. Twenty such modules will be used on the Nova Inertial Confinement Fusion Laser System for plasma retropulse shutters

  19. Photonics in switching

    CERN Document Server

    Midwinter, John E; Kelley, Paul

    1993-01-01

    Photonics in Switching provides a broad, balanced overview of the use of optics or photonics in switching, from materials and devices to system architecture. The chapters, each written by an expert in the field, survey the key technologies, setting them in context and highlighting their benefits and possible applications. This book is a valuable resource for those working in the communications industry, either at the professional or student level, who do not have extensive background knowledge or the underlying physics of the technology.

  20. Magnetic switching

    International Nuclear Information System (INIS)

    Kirbie, H.C.

    1989-01-01

    Magnetic switching is a pulse compression technique that uses a saturable inductor (reactor) to pass pulses of energy between two capacitors. A high degree of pulse compression can be achieved in a network when several of these simple, magnetically switched circuits are connected in series. Individual inductors are designed to saturate in cascade as a pulse moves along the network. The technique is particularly useful when a single-pulse network must be very reliable or when a multi-pulse network must operate at a high pulse repetition frequency (PRF). Today, magnetic switches trigger spark gaps, sharpen the risetimes of high energy pulses, power large lasers, and drive high PRF linear induction accelerators. This paper will describe the technique of magnetic pulse compression using simple networks and design equations. A brief review of modern magnetic materials and of their role in magnetic switch design will be presented. 12 refs., 8 figs

  1. Joint Polar Satellite System's Operational and Research Applications from Suomi NPP

    Science.gov (United States)

    Goldberg, M.

    2014-12-01

    The Joint Polar Satellite System is NOAA's new operational satellite program and includes the Suomi National Polar-orbiting Partnership (S-NPP) as a bridge between NOAA's operational Polar Orbiting Environmental Satellite (POES) series, which began in 1978, and the first JPSS operational satellite scheduled for launch in 2017. JPSS provides critical data for key operational and research applications, and includes: 1) Weather forecasting - data from the JPSS Cross-track Infrared Sounder (CrIS) and the Advanced Technology Microwave Sounder (ATMS) are needed to forecast weather events out to 7 days. Nearly 85% of all data used in weather forecasting are from polar orbiting satellites. 2) Environmental monitoring - data from the JPSS Visible Infrared Imager Radiometer Suite (VIIRS) are used to monitor the environment including the health of coastal ecosystems, drought conditions, fire, smoke, dust, snow and ice, and the state of oceans, including sea surface temperature and ocean color. 3) Climate monitoring - data from JPSS instruments, including OMPS and CERES will provide continuity to climate data records established using NOAA POES and NASA Earth Observing System (EOS) satellite observations. These data records provide a unified and coherent long-term observation of the environment; the records and products are critical to climate modelers, scientists, and decision makers concerned with advancing climate change understanding, prediction, mitigation and adaptation strategies, and policies. To bridge the gap between products and applications, the JPSS Program has established a proving ground program to optimize the use of JPSS data with other data sources to improve key products and services. A number of operational and research applications will be discussed, including the use of CrIS and ATMS for improved weather forecasting, the use of VIIRS for environmental monitoring of sea ice, smoke, fire, floods, droughts, coastal water quality (e.g. harmful algal blooms

  2. A Fault-Tolerant Modulation Method to Counteract the Double Open-Switch Fault in Matrix Converter Drive Systems without Redundant Power Devices

    DEFF Research Database (Denmark)

    Chen, Der-Fa; Nguyen-Duy, Khiem; Liu, Tian-Hua

    2012-01-01

    This paper studies the double open-switch fault issue occurring within the conventional matrix converter driving a three-phase permanent-magnet synchronous motor system and proposes a fault-tolerant solution by introducing a revised modulation strategy. In this switching strategy, the rectifier......-stage modulation is adjusted based on the knowledge of the switching logics of the inverter-stage and the operating input voltage sectors. However, the proposed fault-tolerant method does not rely on the assist of any redundant power devices or any reconfiguration of the matrix converter circuit by means of using...

  3. Real time polarization sensor image processing on an embedded FPGA/multi-core DSP system

    Science.gov (United States)

    Bednara, Marcus; Chuchacz-Kowalczyk, Katarzyna

    2015-05-01

    Most embedded image processing SoCs available on the market are highly optimized for typical consumer applications like video encoding/decoding, motion estimation or several image enhancement processes as used in DSLR or digital video cameras. For non-consumer applications, on the other hand, optimized embedded hardware is rarely available, so often PC based image processing systems are used. We show how a real time capable image processing system for a non-consumer application - namely polarization image data processing - can be efficiently implemented on an FPGA and multi-core DSP based embedded hardware platform.

  4. Stokes image reconstruction for two-color microgrid polarization imaging systems.

    Science.gov (United States)

    Lemaster, Daniel A

    2011-07-18

    The Air Force Research Laboratory has developed a new microgrid polarization imaging system capable of simultaneously reconstructing linear Stokes parameter images in two colors on a single focal plane array. In this paper, an effective method for extracting Stokes images is presented for this type of camera system. It is also shown that correlations between the color bands can be exploited to significantly increase overall spatial resolution. Test data is used to show the advantages of this approach over bilinear interpolation. The bounds (in terms of available reconstruction bandwidth) on image resolution are also provided.

  5. Optical fiber switch

    Science.gov (United States)

    Early, James W.; Lester, Charles S.

    2002-01-01

    Optical fiber switches operated by electrical activation of at least one laser light modulator through which laser light is directed into at least one polarizer are used for the sequential transport of laser light from a single laser into a plurality of optical fibers. In one embodiment of the invention, laser light from a single excitation laser is sequentially transported to a plurality of optical fibers which in turn transport the laser light to separate individual remotely located laser fuel ignitors. The invention can be operated electro-optically with no need for any mechanical or moving parts, or, alternatively, can be operated electro-mechanically. The invention can be used to switch either pulsed or continuous wave laser light.

  6. Application of small-signal modeling and measurement techniques to the stability analysis of an integrated switching-mode power system. [onboard Dynamics Explorer Satellite

    Science.gov (United States)

    Wong, R. C.; Owen, H. A., Jr.; Wilson, T. G.; Rodriguez, G. E.

    1980-01-01

    Small-signal modeling techniques are used in a system stability analysis of a breadboard version of a complete functional electrical power system. The system consists of a regulated switching dc-to-dc converter, a solar-cell-array simulator, a solar-array EMI filter, battery chargers and linear shunt regulators. Loss mechanisms in the converter power stage, including switching-time effects in the semiconductor elements, are incorporated into the modeling procedure to provide an accurate representation of the system without requiring frequency-domain measurements to determine the damping factor. The small-signal system model is validated by the use of special measurement techniques which are adapted to the poor signal-to-noise ratio encountered in switching-mode systems. The complete electrical power system with the solar-array EMI filter is shown to be stable over the intended range of operation.

  7. Low frequency noise in the unstable contact region of Au-to-Au microcontact for microelectromechanical system switches

    International Nuclear Information System (INIS)

    Qiu, Haodong; Wang, Hong; Ke, Feixiang

    2014-01-01

    The noise behavior of Au-to-Au microcontact for microelectromechanical system switches has been experimentally studied in the unstable contact region. The results suggest that the electrical conduction remains nonmetallic at the initial stage during contact formation due to the existence of alien films, and traps in the alien layer located at the contact interface could play an important role in determining the conduction noise. The conduction fluctuation induced by electron trapping-detrapping associated with the hydrocarbon layer is found to be an intrinsic noise source contributing to the low frequency noise in the unstable contact region.

  8. 2x2 MIMO-OFDM Gigabit fiber-wireless access system based on polarization division multiplexed WDM-PON

    DEFF Research Database (Denmark)

    Deng, Lei; Pang, Xiaodan; Zhao, Ying

    2012-01-01

    We propose a spectral efficient radio over wavelength division multiplexed passive optical network (WDM-PON) system by combining optical polarization division multiplexing (PDM) and wireless multiple input multiple output (MIMO) spatial multiplexing techniques. In our experiment, a training...

  9. A novel variable field system for field-cycled dynamic nuclear polarization spectroscopy

    Science.gov (United States)

    Shet, Keerthi; Caia, George L.; Kesselring, Eric; Samouilov, Alexandre; Petryakov, Sergey; Lurie, David J.; Zweier, Jay L.

    2010-08-01

    Dynamic nuclear polarization (DNP) is an NMR-based technique which enables detection and spectral characterization of endogenous and exogenous paramagnetic substances measured via transfer of polarization from the saturated unpaired electron spin system to the NMR active nuclei. A variable field system capable of performing DNP spectroscopy with NMR detection at any magnetic field in the range 0-0.38 T is described. The system is built around a clinical open-MRI system. To obtain EPR spectra via DNP, partial cancellation of the detection field B0NMR is required to alter the evolution field B0EPR at which the EPR excitation is achieved. The addition of resistive actively shielded field cancellation coils in the gap of the primary magnet provides this field offset in the range of 0-100 mT. A description of the primary magnet, cancellation coils, power supplies, interfacing hardware, RF electronics and console are included. Performance of the instrument has been evaluated by acquiring DNP spectra of phantoms with aqueous nitroxide solutions (TEMPOL) at three NMR detection fields of 97 G, 200 G and 587 G corresponding to 413 kHz, 851.6 kHz and 2.5 MHz respectively and fixed EPR evolution field of 100 G corresponding to an irradiation frequency of 282.3 MHz. This variable-field DNP system offers great flexibility for the performance of DNP spectroscopy with independent optimum choice of EPR excitation and NMR detection fields.

  10. An intelligent switch with back-propagation neural network based hybrid power system

    Science.gov (United States)

    Perdana, R. H. Y.; Fibriana, F.

    2018-03-01

    The consumption of conventional energy such as fossil fuels plays the critical role in the global warming issues. The carbon dioxide, methane, nitrous oxide, etc. could lead the greenhouse effects and change the climate pattern. In fact, 77% of the electrical energy is generated from fossil fuels combustion. Therefore, it is necessary to use the renewable energy sources for reducing the conventional energy consumption regarding electricity generation. This paper presents an intelligent switch to combine both energy resources, i.e., the solar panels as the renewable energy with the conventional energy from the State Electricity Enterprise (PLN). The artificial intelligence technology with the back-propagation neural network was designed to control the flow of energy that is distributed dynamically based on renewable energy generation. By the continuous monitoring on each load and source, the dynamic pattern of the intelligent switch was better than the conventional switching method. The first experimental results for 60 W solar panels showed the standard deviation of the trial at 0.7 and standard deviation of the experiment at 0.28. The second operation for a 900 W of solar panel obtained the standard deviation of the trial at 0.05 and 0.18 for the standard deviation of the experiment. Moreover, the accuracy reached 83% using this method. By the combination of the back-propagation neural network with the observation of energy usage of the load using wireless sensor network, each load can be evenly distributed and will impact on the reduction of conventional energy usage.

  11. Spectrum sensing using single-radio switched-beam antenna systems

    DEFF Research Database (Denmark)

    Tsakalaki, Elpiniki; Wilcox, David; De Carvalho, Elisabeth

    2012-01-01

    The paper describes spectrum sensing using single-radio switched-beam arrays with reactance-loaded parasitic elements. At a given frequency, the antenna's loading conditions (reactive loads) are optimized for maximum average beamforming gain in the beampattern look direction. Circular permutations...... of the reactive loads rotate the narrowband beampattern to different angular positions dividing the whole space around the cognitive receiver into several angular subspaces. The beampattern directionality leverages the performance of spectrum sensing algorithms like the energy detection by enhancing the receive...

  12. Spin Mode Switching at the Edge of a Quantum Hall System.

    Science.gov (United States)

    Khanna, Udit; Murthy, Ganpathy; Rao, Sumathi; Gefen, Yuval

    2017-11-03

    Quantum Hall states can be characterized by their chiral edge modes. Upon softening the edge potential, the edge has long been known to undergo spontaneous reconstruction driven by charging effects. In this Letter we demonstrate a qualitatively distinct phenomenon driven by exchange effects, in which the ordering of the edge modes at ν=3 switches abruptly as the edge potential is made softer, while the ordering in the bulk remains intact. We demonstrate that this phenomenon is robust, and has many verifiable experimental signatures in transport.

  13. Design and Fabrication of a Strain-Powered Microelectromechanical System (MEMS) Switch

    Science.gov (United States)

    2014-09-01

    to describe our two main fabrication approaches in the Appendices. 1.1 Design The switch devices were designed in AutoCAD with variations in hinge...evaporation in the Evatec evaporator. Hinge anchoring after dry etching required an extension of the sacrificial Si layer through AutoCAD redesign and mask...anchored along this top edge. This required us to make an AutoCAD and mask design revision reducing the dimension of the second PVD step so that it did

  14. An HARQ scheme with antenna switching for V-BLAST system

    Directory of Open Access Journals (Sweden)

    Bonghoe Kim

    2004-12-01

    Full Text Available Bell-labs layered space-time (BLAST achieves high spectral efficiency in rich scattering environments by transmitting independent data streams via each transmit antenna. However, this high spectral efficiency is significantly reduced if the signals ate the receiver go through correlated channels. In this paper, we propose a hybrid automatic request (HARQ scheme to alleviate the adverse effect of the channel correlation by simply switching the transmission in retransmission. With the proposed scheme, we can achieve significant improvement over the correlated channels with negligible complexity increase.

  15. Dual-Polarized On-Chip Antenna for 300 GHz Full-Duplex Communication System

    Directory of Open Access Journals (Sweden)

    Linyan Guo

    2017-01-01

    Full Text Available This paper presents a novel design of compact orthogonally polarized on-chip antenna to realize 300 GHz full-duplex communication system with high isolation. It consists of a dipole antenna for horizontal polarization and a disk-loaded monopole antenna for vertical polarization. They are in good cross-polarization state with more than 90 dB of self-interference suppression and then can be used to achieve good isolation between transmitting and receiving antennas. In addition, two dual-polarized antennas have been adopted in two separated transceivers to study their isolation performance. Furthermore, this compact antenna only occupies an active area of 390 μm × 300 μm × 78 μm and can be used for multiple-input multiple-output application as well.

  16. An analysis of the electromagnetic field in multi-polar linear induction system

    International Nuclear Information System (INIS)

    Chervenkova, Todorka; Chervenkov, Atanas

    2002-01-01

    In this paper a new method for determination of the electromagnetic field vectors in a multi-polar linear induction system (LIS) is described. The analysis of the electromagnetic field has been done by four dimensional electromagnetic potentials in conjunction with theory of the magnetic loops . The electromagnetic field vectors are determined in the Minkovski's space as elements of the Maxwell's tensor. The results obtained are compared with those got from the analysis made by the finite elements method (FEM).With the method represented in this paper one can determine the electromagnetic field vectors in the multi-polar linear induction system using four-dimensional potential. A priority of this method is the obtaining of analytical results for the electromagnetic field vectors. These results are also valid for linear media. The dependencies are valid also at high speeds of movement. The results of the investigated linear induction system are comparable to those got by the finite elements method. The investigations may be continued in the determination of other characteristics such as drag force, levitation force, etc. The method proposed in this paper for an analysis of linear induction system can be used for optimization calculations. (Author)

  17. The EUMETSAT Polar System - Second Generation (EPS-SG) micro-wave imaging (MWI) mission

    Science.gov (United States)

    Bojkov, B. R.; Accadia, C.; Klaes, D.; Canestri, A.; Cohen, M.

    2017-12-01

    The EUMETSAT Polar System (EPS) will be followed by a second generation system called EPS-SG. This new family of missions will contribute to the Joint Polar System being jointly set up with NOAA in the timeframe 2020-2040. These satellites will fly, like Metop (EPS), in a sun synchronous, low earth orbit at 830 km altitude and 09:30 local time descending node, providing observations over the full globe with revisit times of 12 hours. EPS-SG consists of two different satellites configurations, the EPS-SGa series dedicated to IR and MW sounding, and the EPS-SGb series dedicated to microwave imaging and scatterometry. The EPS-SG family will consist of three successive launches of each satellite-type. The Microwave Imager (MWI) will be hosted on Metop-SGb series of satellites, with the primary objective of supporting Numerical Weather Prediction (NWP) at regional and global scales. Other applications will be observation of surface parameters such as sea ice concentration and hydrology applications. The 18 MWI instrument frequencies range from 18.7 GHz to 183 GHz. All MWI channels up to 89 GHz will measure V- and H polarizations. The MWI was also designed to provide continuity of measurements for select heritage microwave imager channels (e.g. SSM/I, AMSR-E). The additional sounding channels such as the 50-55 and 118 GHz bands will provide additional cloud and precipitation information over sea and land. This combination of channels was successfully tested on the NPOESS Aircraft Sounder Testbed - Microwave Sounder (NAST-M) airborne radiometer, and it is the first time that will be implemented in a conical scanning configuration in a single instrument. An overview of the EPS-SG programme and the MWI instrument will be presented.

  18. A Novel Method for Performance Analysis of OFDM Polarization Diversity System in Ricean Fading Environment

    DEFF Research Database (Denmark)

    Ilic-Delibasic, M.; Pejanovic-Djurisic, M.; Prasad, R.

    2012-01-01

    OFDM (Orthogonal Frequency Division Multiplexing) is proven to be a very effective modulation and multiple access technique that enables high data rate transmission. Due to its good performance it is already implemented in several standardized technologies, and it is very promising technique...... conditions. In order to calculate BER (Bit Error Rate) for the considered OFDM polarization diversity system with a certain level of the received signals correlation, we propose a novel analytical method. The obtained results are compared with the ones attained by simulation....

  19. High Speed Inter-Satellite Communication System by Incorporating Hybrid Polarization-Wavelength Division Multiplexing Scheme

    Science.gov (United States)

    Chaudhary, Sushank; Chaudhary, Neha; Sharma, Saurabh; Choudhary, BC

    2017-12-01

    Inter-Satellite communication is one of remarkable technologies that can be used to communicate between satellites. This work is focused to carry out the investigations of polarization scheme by incorporating dense wavelength division multiplexing (DWDM) scheme in inter-satellite communication system. A 20×6 Gbps data are transported over inter-satellite optical link having span of 5,000 km to realize the total data transmission of 120 Gbps. Moreover, results are also reported with the effect of RZ and NRZ modulation schemes. The performance of proposed inter-satellite communication link is measured in terms of signal-to-noise ratio, received power and eye diagrams.

  20. Self-organization of the climate system: Synchronized polar and oceanic teleconnections

    Science.gov (United States)

    Reischmann, Elizabeth Piccard

    Synchronization is a widespread phenomenon in nonlinear, physical systems. It describes the phenomena of two or more weakly interacting, nonlinear oscillators adjust their natural frequencies until they come into phase and frequency lock. This behavior has been observed in biological, chemical and electronic systems, including neurons, fireflies, and computers, but has not been widely studied in climate. This thesis presents a study of several major examples of synchronized climatic systems, starting with ice age timings seemingly caused by the global climate's gradual synchronization to the Earth's 413kyr orbital eccentricity band, which may be responsible for the shift of ice age timings and amplitudes at the Mid-Pleistocene transition. The focus of the thesis, however, is centered the second major example of stable synchronization in the climate system: the continuous, 90 degree phase relationship of the polar climate signals for the entirety of the available ice record. The existence of a relationship between polar climates has been widely observed since ice core proxies became available in both Greenland and Antarctica. However, my work focuses on refining this phase relationship, utilizing it's linear nature to apply deconvolution and establish an energy transfer function. This transfer function shows a distinctly singular frequency, suggesting that climate signal is predominately communicated north to south with a period of 1.6kyrs. This narrows down possible mechanisms of polar connection dramatically, and is further investigated via a collection of intermediate proxy datasets and a set of more contemporary, synchronized, sea surface temperature dipoles. While the former fails to show any strong indication of the nature of the polar signal due in part to the overwhelming uncertainties present on the centennial and millennial scales, the latter demonstrates a large set of synchronized climate oscillations exist, communicate in a variety of networks, and have

  1. Optical code division multiple access secure communications systems with rapid reconfigurable polarization shift key user code

    Science.gov (United States)

    Gao, Kaiqiang; Wu, Chongqing; Sheng, Xinzhi; Shang, Chao; Liu, Lanlan; Wang, Jian

    2015-09-01

    An optical code division multiple access (OCDMA) secure communications system scheme with rapid reconfigurable polarization shift key (Pol-SK) bipolar user code is proposed and demonstrated. Compared to fix code OCDMA, by constantly changing the user code, the performance of anti-eavesdropping is greatly improved. The Pol-SK OCDMA experiment with a 10 Gchip/s user code and a 1.25 Gb/s user data of payload has been realized, which means this scheme has better tolerance and could be easily realized.

  2. Stability Switches and Hopf Bifurcation in a Coupled FitzHugh-Nagumo Neural System with Multiple Delays

    Directory of Open Access Journals (Sweden)

    Shengwei Yao

    2014-01-01

    Full Text Available A FitzHugh-Nagumo (FHN neural system with multiple delays has been proposed. The number of equilibrium point is analyzed. It implies that the neural system exhibits a unique equilibrium and three ones for the different values of coupling weight by employing the saddle-node bifurcation of nontrivial equilibrium point and transcritical bifurcation of trivial one. Further, the stability of equilibrium point is studied by analyzing the corresponding characteristic equation. Some stability criteria involving the multiple delays and coupling weight are obtained. The results show that the neural system exhibits the delay-independence and delay-dependence stability. Increasing delay induces the stability switching between resting state and periodic activity in some parameter regions of coupling weight. Finally, numerical simulations are taken to support the theoretical results.

  3. Multiobjective optimal placement of switches and protective devices in electric power distribution systems using ant colony optimization

    Energy Technology Data Exchange (ETDEWEB)

    Tippachon, Wiwat; Rerkpreedapong, Dulpichet [Department of Electrical Engineering, Kasetsart University, 50 Phaholyothin Rd., Ladyao, Jatujak, Bangkok 10900 (Thailand)

    2009-07-15

    This paper presents a multiobjective optimization methodology to optimally place switches and protective devices in electric power distribution networks. Identifying the type and location of them is a combinatorial optimization problem described by a nonlinear and nondifferential function. The multiobjective ant colony optimization (MACO) has been applied to this problem to minimize the total cost while simultaneously minimize two distribution network reliability indices including system average interruption frequency index (SAIFI) and system interruption duration index (SAIDI). Actual distribution feeders are used in the tests, and test results have shown that the algorithm can determine the set of optimal nondominated solutions. It allows the utility to obtain the optimal type and location of devices to achieve the best system reliability with the lowest cost. (author)

  4. Scaling of the polarization amplitude in quantum many-body systems in one dimension

    Science.gov (United States)

    Kobayashi, Ryohei; Nakagawa, Yuya O.; Fukusumi, Yoshiki; Oshikawa, Masaki

    2018-04-01

    Resta proposed a definition of the electric polarization in one-dimensional systems in terms of the ground-state expectation value of the large gauge transformation operator. Vanishing of the expectation value in the thermodynamic limit implies that the system is a conductor. We study Resta's polarization amplitude (expectation value) in the S =1 /2 XXZ chain and its several generalizations, in the gapless conducting Tomonaga-Luttinger liquid phase. We obtain an analytical expression in the lowest-order perturbation theory about the free fermion point (XY chain) and an exact result for the Haldane-Shastry model with long-range interactions. We also obtain numerical results, mostly using the exact diagonalization method. We find that the amplitude exhibits a power-law scaling in the system size (chain length) and vanishes in the thermodynamic limit. On the other hand, the exponent depends on the model even when the low-energy limit is described by the Tomonaga-Luttinger liquid with the same Luttinger parameter. We find that a change in the exponent occurs when the Umklapp term(s) are eliminated, suggesting the importance of the Umklapp terms.

  5. Monitoring tooth demineralization using a cross polarization optical coherence tomographic system with an integrated MEMS scanner

    Science.gov (United States)

    Fried, Daniel; Staninec, Michal; Darling, Cynthia; Kang, Hobin; Chan, Kenneth

    2012-01-01

    New methods are needed for the nondestructive measurement of tooth demineralization and remineralization to monitor the progression of incipient caries lesions (tooth decay) for effective nonsurgical intervention and to evaluate the performance of anti-caries treatments such as chemical treatments or laser irradiation. Studies have shown that optical coherence tomography (OCT) has great potential to fulfill this role since it can be used to measure the depth and severity of early lesions with an axial resolution exceeding 10-μm, it is easy to apply in vivo and it can be used to image the convoluted topography of tooth occlusal surfaces. In this paper we present early results using a new cross-polarization OCT system introduced by Santec. This system utilizes a swept laser source and a MEMS scanner for rapid acquisition of cross polarization images. Preliminary studies show that this system is useful for measurement of the severity of demineralization on tooth surfaces and for showing the spread of occlusal lesions under the dentinal-enamel junction.

  6. National Polar-orbiting Operational Environmental Satellite System (NPOESS) Design and Architecture

    Science.gov (United States)

    Hinnant, F.

    2008-12-01

    The National Oceanic and Atmospheric Administration (NOAA), Department of Defense (DoD), and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation weather and environmental satellite system - the National Polar-orbiting Operational Environmental Satellite System (NPOESS). NPOESS will replace the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA and the Defense Meteorological Satellite Program (DMSP) managed by the DoD and will provide continuity for the NASA Earth Observing System (EOS) with the launch of the NPOESS Preparatory Project (NPP). This poster will provide an overview of the NPOESS architecture, which includes four segments. The space segment includes satellites in two orbits that carry a suite of sensors to collect meteorological, oceanographic, climatological, and solar-geophysical observations of the Earth, atmosphere, and near-Earth space environment. The NPOESS design allows centralized mission management and delivers high quality environmental products to military, civil and scientific users through a Command, Control, and Communication Segment (C3S). The data processing for NPOESS is accomplished through an Interface Data Processing Segment (IDPS)/Field Terminal Segment (FTS) that processes NPOESS satellite data to provide environmental data products to NOAA and DoD processing centers operated by the United States government as well as to remote terminal users. The Launch Support Segment completes the four segments that make up NPOESS that will enhance the connectivity between research and operations and provide critical operational and scientific environmental measurements to military, civil, and scientific users until 2026.

  7. Cirlularly Polarized Proximity- Fed Microstrip Array Antenna for LAPAN TUBSAT Micro Satellite System

    Directory of Open Access Journals (Sweden)

    Endra Wijaya

    2013-11-01

    Full Text Available The design microstrip of array antenna circular polarization characteristic developed for support LAPAN TUBSAT micro satellite system. The antenna on the micro satellite systems transmit data to ground stations operating at S band frequencies.The antenna is designed for impedance matching at frequencies of 2:25 GHz.The four elements of the square patch antenna array composed using linear methods, where the design of the transmission lines used by federal corporate structure model network consisting of three elements of the quarter wave transformer of a power divider. The feeding techniques for antenna designed using proximity coupling method, which for the type of substrate material used is similar. Circularly polarized antenna characteristics are influenced by the truncated corner pieces on the patch. To design the overall antenna used simulated method of moments in microwave office software applications. The results of measurements and simulations obtained antenna parameters, such as: bandwidth of return loss under 10 dB is 200 MHz (shifted 35%, bandwidth of axial ratio under 3dB is 1.7% and maximum gain directivity is 9 dB. Overall results obtained antenna parameters to meet the specifications of LAPAN TUBSAT micro satellite system.

  8. Analysis of Performance for 100 Gbit/s Dual-Polarization QPSK Modulation Format System

    Science.gov (United States)

    Li, Li; Xiao-bo, Guo; Jing, Li

    2016-03-01

    This article introduces modulation technology, coherent reception technology, the overall design and other key issues for 100 Gbit/s dual-polarization quadrature phase shift keying (DP-QPSK) modulation. Using the technologies based on digital signal processing (DSP), it realizes the long-range transmissions of 100 Gbit/s optical systems to achieve optical signal dispersion compensation, polarized solution reuse and phase estimation. The effect of this scheme is verified with OptiSystem, and the simulation results indicate, with the help of DSP module for processing of the received signal, that the last constellation is ideal and the data transmission error rate is less than 1.3 e-4. The scheme is implemented simply and has high reliability, and it also has reference significance for the optimization of coherent optical detection hardware. As they feature in high spectrum efficiency and large dispersion and PMD tolerances, the DP-QPSK modulation can improve the line efficiency, and maximize the spectral efficiency of the dense wavelength division multiplexing systems. The quality of eye diagram is high, which is clean and has decent open degree.

  9. Inventory control with two switch-over levels for a class of M/G/1 queueing systems with variable arrival and service rate

    NARCIS (Netherlands)

    Tijms, H.C.; van der Duyn Schouten, F.A.

    1978-01-01

    This paper deals with inventory control in a class of M/G/1 queueing systems. At each point of time the system can be switched from one of two possible stages to another. The rate of arrival process and the service rate depend on the stage of the system. The cost structure imposed on the model

  10. Low inductance gas switching.

    Energy Technology Data Exchange (ETDEWEB)

    Chavez, Ray; Harjes, Henry Charles III; Wallace, Zachariah; Elizondo, Juan E.

    2007-10-01

    The laser trigger switch (LTS) is a key component in ZR-type pulsed power systems. In ZR, the pulse rise time through the LTS is > 200 ns and additional stages of pulse compression are required to achieve the desired <100 ns rise time. The inductance of the LTS ({approx}500nH) in large part determines the energy transfer time through the switch and there is much to be gained in improving system performance and reducing system costs by reducing this inductance. The current path through the cascade section of the ZR LTS is at a diameter of {approx} 6-inches which is certainly not optimal from an inductance point of view. The LTS connects components of much greater diameter (typically 4-5 feet). In this LDRD the viability of switch concepts in which the diameter of cascade section is greatly increased have been investigated. The key technical question to be answered was, will the desired multi-channel behavior be maintained in a cascade section of larger diameter. This LDRD proceeded in 2 distinct phases. The original plan for the LDRD was to develop a promising switch concept and then design, build, and test a moderate scale switch which would demonstrate the key features of the concept. In phase I, a switch concept which meet all electrical design criteria and had a calculated inductance of 150 nH was developed. A 1.5 MV test switch was designed and fabrication was initiated. The LDRD was then redirected due to budgetary concerns. The fabrication of the switch was halted and the focus of the LDRD was shifted to small scale experiments designed to answer the key technical question concerning multi-channel behavior. In phase II, the Multi-channel switch test bed (MCST) was designed and constructed. The purpose of MCST was to provide a versatile, fast turn around facility for the study the multi-channel electrical breakdown behavior of a ZR type cascade switch gap in a parameter space near that of a ZR LTS. Parameter scans on source impedance, gap tilt, gap spacing and

  11. Performance improvement of per-user threshold based multiuser switched scheduling system

    KAUST Repository

    Nam, Haewoon

    2013-01-01

    SUMMARY This letter proposes a multiuser switched scheduling scheme with per-user threshold and post user selection and provides a generic analytical framework for determining the optimal feedback thresholds. The proposed scheme applies an individual feedback threshold for each user rather than a single common threshold for all users to achieve some capacity gain due to the flexibility of threshold selection as well as a lower scheduling outage probability. In addition, since scheduling outage may occur with a non-negligible probability, the proposed scheme employs post user selection in order to further improve the ergodic capacity, where the user with the highest potential for a higher channel quality than other users is selected. Numerical and simulation results show that the capacity gain by post user selection is significant when random sequence is used. Copyright © 2013 The Institute of Electronics, Information and Communication Engineers.

  12. A polarized multispectral imaging system for quantitative assessment of hypertrophic scars.

    Science.gov (United States)

    Ghassemi, Pejhman; Travis, Taryn E; Moffatt, Lauren T; Shupp, Jeffrey W; Ramella-Roman, Jessica C

    2014-10-01

    Hypertrophic scars (HTS) are a pathologic reaction of the skin and soft tissue to burn or other traumatic injury. Scar tissue can cause patients serious functional and cosmetic issues. Scar management strategies, specifically scar assessment techniques, are vital to improve clinical outcome. To date, no entirely objective method for scar assessment has been embraced by the medical community. In this study, we introduce for the first time, a novel polarized multispectral imaging system combining out-of-plane Stokes polarimetry and Spatial Frequency Domain Imaging (SFDI). This imaging system enables us to assess the pathophysiology (hemoglobin, blood oxygenation, water, and melanin) and structural features (cellularity and roughness) of HTS. To apply the proposed technique in an in vivo experiment, dermal wounds were created in a porcine model and allowed to form into scars. The developed scars were then measured at various time points using the imaging system. Results showed a good agreement with clinical Vancouver Scar Scale assessment and histological examinations.

  13. Design of FBG En/decoders in Coherent 2-D Time-polarization OCDMA Systems

    Science.gov (United States)

    Hou, Fen-fei; Yang, Ming

    2012-12-01

    A novel fiber Bragg grating (FBG)-based en/decoder for the two-dimensional (2-D) time-spreading and polarization multiplexer optical coding is proposed. Compared with other 2-D en/decoders, the proposed en/decoding for an optical code-division multiple-access (OCDMA) system uses a single phase-encoded FBG and coherent en/decoding. Furthermore, combined with reconstruction-equivalent-chirp technology, such en/decoders can be realized with a conventional simple fabrication setup. Experimental results of such en/decoders and the corresponding system test at a data rate of 5 Gbit/s demonstrate that this kind of 2-D FBG-based en/decoders could improve the performances of OCDMA systems.

  14. Process for preparing organoclays for aqueous and polar-organic systems

    Science.gov (United States)

    Chaiko, David J.

    2001-01-01

    A process for preparing organoclays as thixotropic agents to control the rheology of water-based paints and other aqueous and polar-organic systems. The process relates to treating low-grade clay ores to achieve highly purified organoclays and/or to incorporate surface modifying agents onto the clay by adsorption and/or to produce highly dispersed organoclays without excessive grinding or high shear dispersion. The process involves the treatment of impure, or run-of-mine, clay using an aqueous biphasic extraction system to produce a highly dispersed clay, free of mineral impurities and with modified surface properties brought about by adsorption of the water-soluble polymers used in generating the aqueous biphasic extraction system. This invention purifies the clay to greater than 95%.

  15. Selective control of multiple ferroelectric switching pathways using a trailing flexoelectric field.

    Science.gov (United States)

    Park, Sung Min; Wang, Bo; Das, Saikat; Chae, Seung Chul; Chung, Jin-Seok; Yoon, Jong-Gul; Chen, Long-Qing; Yang, Sang Mo; Noh, Tae Won

    2018-03-12

    Flexoelectricity is an electromechanical coupling between electrical polarization and a strain gradient 1 that enables mechanical manipulation of polarization without applying an electrical bias 2,3 . Recently, flexoelectricity was directly demonstrated by mechanically switching the out-of-plane polarization of a uniaxial system with a scanning probe microscope tip 3,4 . However, the successful application of flexoelectricity in low-symmetry multiaxial ferroelectrics and therefore active manipulation of multiple domains via flexoelectricity have not yet been achieved. Here, we demonstrate that the symmetry-breaking flexoelectricity offers a powerful route for the selective control of multiple domain switching pathways in multiaxial ferroelectric materials. Specifically, we use a trailing flexoelectric field that is created by the motion of a mechanically loaded scanning probe microscope tip. By controlling the SPM scan direction, we can deterministically select either stable 71° ferroelastic switching or 180° ferroelectric switching in a multiferroic magnetoelectric BiFeO 3 thin film. Phase-field simulations reveal that the amplified in-plane trailing flexoelectric field is essential for this domain engineering. Moreover, we show that mechanically switched domains have a good retention property. This work opens a new avenue for the deterministic selection of nanoscale ferroelectric domains in low-symmetry materials for non-volatile magnetoelectric devices and multilevel data storage.

  16. Stochastic Switching Dynamics

    DEFF Research Database (Denmark)

    Simonsen, Maria

    mode control. It is investigated how to understand and interpret solutions to models of switched systems, which are exposed to discontinuous dynamics and uncertainties (primarily) in the form of white noise. The goal is to gain knowledge about the performance of the system by interpreting the solution...

  17. Quantum mechanical systems interacting with different polarizations of gravitational waves in noncommutative phase space

    Science.gov (United States)

    Saha, Anirban; Gangopadhyay, Sunandan; Saha, Swarup

    2018-02-01

    Owing to the extreme smallness of any noncommutative scale that may exist in nature, both in the spatial and momentum sector of the quantum phase space, a credible possibility of their detection lies in the gravitational wave (GW) detection scenario, where one effectively probes the relative length-scale variations ˜O [10-20-10-23] . With this motivation, we have theoretically constructed how a free particle and a harmonic oscillator will respond to linearly and circularly polarized gravitational waves if their quantum mechanical phase space has a noncommutative structure. We critically analyze the formal solutions which show resonance behavior in the responses of both free particle and HO systems to GW with both kind of polarizations. We discuss the possible implications of these solutions in detecting noncommutativity in a GW detection experiment. We use the currently available upper-bound estimates on various noncommutative parameters to anticipate the relative importance of various terms in the solutions. We also argue how the quantum harmonic oscillator system we considered here can be very relevant in the context of the resonant bar detectors of GW which are already operational.

  18. Effects of astigmatism on spectra, coherence and polarization of stochastic electromagnetic beams passing through an astigmatic optical system.

    Science.gov (United States)

    Pan, Liuzhan; Sun, Mengle; Ding, Chaoliang; Zhao, Zhiguo; Lü, Baida

    2009-04-27

    Analytical formulas for the cross-spectral density matrix of stochastic electromagnetic Gaussian Schell-model (EGSM) beams passing through an astigmatic optical system are derived. We show both analytically and by numerical examples the effects of astigmatism on spectra, coherence and polarization of stochastic electromagnetic EGSM beams propagating through an astigmatic lens. A comparison with the aberration-free case is made, and shows that the astigmatism has significant effect on the spectra, coherence and polarization.

  19. MEMS-based Optic Fiber Fabry-Perot Sensor for Underwater Acoustic Measurement with A Wavelength-switched System

    Science.gov (United States)

    Xia, J.; Y Wang, F.; Luo, H.; Hu, Y. M.; Xiong, S. D.

    2017-12-01

    In this paper, a MEMS-based extrinsic Farby-Perot Interferometric (EFPI) acoustic pressure acoustic sensor is presented. The diaphragm structure is used as the second reflected surface, and the sensitive surface to acoustic pressure. A wavelength-switched phase demodulation system for EFPI sensors is used for acoustic signal recovery. The modified phase demodulation system has been demonstrated to recover the signal to a stable intensity fluctuation level of ±0.5 dB at the test frequency of 2000 Hz. In the test depth of 50cm, the sensor has a resonant frequency of 3.7 kHz, a flat frequency range of 10-800Hz, and a corresponding acoustic pressure sensitivity of -159 dB re. 1/μPa.

  20. Signal Processing for Wireless Communication MIMO System with Nano- Scaled CSDG MOSFET based DP4T RF Switch.

    Science.gov (United States)

    Srivastava, Viranjay M

    2015-01-01

    In the present technological expansion, the radio frequency integrated circuits in the wireless communication technologies became useful because of the replacement of increasing number of functions, traditional hardware components by modern digital signal processing. The carrier frequencies used for communication systems, now a day, shifted toward the microwave regime. The signal processing for the multiple inputs multiple output wireless communication system using the Metal- Oxide-Semiconductor Field-Effect-Transistor (MOSFET) has been done a lot. In this research the signal processing with help of nano-scaled Cylindrical Surrounding Double Gate (CSDG) MOSFET by means of Double- Pole Four-Throw Radio-Frequency (DP4T RF) switch, in terms of Insertion loss, Isolation, Reverse isolation and Inter modulation have been analyzed. In addition to this a channel model has been presented. Here, we also discussed some patents relevant to the topic.