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Sample records for strongly-correlated electron systems

  1. PREFACE: Strongly correlated electron systems Strongly correlated electron systems

    Science.gov (United States)

    Saxena, Siddharth S.; Littlewood, P. B.

    2012-07-01

    This special section is dedicated to the Strongly Correlated Electron Systems Conference (SCES) 2011, which was held from 29 August-3 September 2011, in Cambridge, UK. SCES'2011 is dedicated to 100 years of superconductivity and covers a range of topics in the area of strongly correlated systems. The correlated electronic and magnetic materials featured include f-electron based heavy fermion intermetallics and d-electron based transition metal compounds. The selected papers derived from invited presentations seek to deepen our understanding of the rich physical phenomena that arise from correlation effects. The focus is on quantum phase transitions, non-Fermi liquid phenomena, quantum magnetism, unconventional superconductivity and metal-insulator transitions. Both experimental and theoretical work is presented. Based on fundamental advances in the understanding of electronic materials, much of 20th century materials physics was driven by miniaturisation and integration in the electronics industry to the current generation of nanometre scale devices. The achievements of this industry have brought unprecedented advances to society and well-being, and no doubt there is much further to go—note that this progress is founded on investments and studies in the fundamentals of condensed matter physics from more than 50 years ago. Nevertheless, the defining challenges for the 21st century will lie in the discovery in science, and deployment through engineering, of technologies that can deliver the scale needed to have an impact on the sustainability agenda. Thus the big developments in nanotechnology may lie not in the pursuit of yet smaller transistors, but in the design of new structures that can revolutionise the performance of solar cells, batteries, fuel cells, light-weight structural materials, refrigeration, water purification, etc. The science presented in the papers of this special section also highlights the underlying interest in energy-dense materials, which

  2. EDITORIAL: Strongly correlated electron systems Strongly correlated electron systems

    Science.gov (United States)

    Ronning, Filip; Batista, Cristian

    2011-03-01

    Strongly correlated electrons is an exciting and diverse field in condensed matter physics. This special issue aims to capture some of that excitement and recent developments in the field. Given that this issue was inspired by the 2010 International Conference on Strongly Correlated Electron Systems (SCES 2010), we briefly give some history in order to place this issue in context. The 2010 International Conference on Strongly Correlated Electron Systems was held in Santa Fe, New Mexico, a reunion of sorts from the 1989 International Conference on the Physics of Highly Correlated Electron Systems that also convened in Santa Fe. SCES 2010—co-chaired by John Sarrao and Joe Thompson—followed the tradition of earlier conferences, in this century, hosted by Buzios (2008), Houston (2007), Vienna (2005), Karlsruhe (2004), Krakow (2002) and Ann Arbor (2001). Every three years since 1997, SCES has joined the International Conference on Magnetism (ICM), held in Recife (2000), Rome (2003), Kyoto (2006) and Karlsruhe (2009). Like its predecessors, SCES 2010 topics included strongly correlated f- and d-electron systems, heavy-fermion behaviors, quantum-phase transitions, non-Fermi liquid phenomena, unconventional superconductivity, and emergent states that arise from electronic correlations. Recent developments from studies of quantum magnetism and cold atoms complemented the traditional subjects and were included in SCES 2010. 2010 celebrated the 400th anniversary of Santa Fe as well as the birth of astronomy. So what's the connection to SCES? The Dutch invention of the first practical telescope and its use by Galileo in 1610 and subsequent years overturned dogma that the sun revolved about the earth. This revolutionary, and at the time heretical, conclusion required innovative combinations of new instrumentation, observation and mathematics. These same combinations are just as important 400 years later and are the foundation of scientific discoveries that were discussed

  3. NMR study of strongly correlated electron systems

    Science.gov (United States)

    Kitaoka, Y.; Tou, H.; Zheng, G.-q.; Ishida, K.; Asayama, K.; Kobayashi, T. C.; Kohda, A.; Takeshita, N.; Amaya, K.; Onuki, Y.; Geibel, G.; Schank, C.; Steglich, F.

    1995-02-01

    Various types of ground states in strongly correlated electron systems have been systematically investigated by means of NMR/NQR at low temperatures under high magnetic field and pressure. We focus on two well-known heavy-electron families, CeCu 2X 2 (X = Si and Ge) (Ce(122)) and UM 2Al 3 (M = Ni and Pd) (U(123)). The Cu NQR experiments on CeCu 2X 2 under high pressure indicate that the physical property of CeCu 2Ge 2 at high pressure, i.e. above the transition at 7.6 GPa from antiferromagnetic (AF) to superconductivity, are clearly related to tha CeCu 2Si 2 at ambient pressure. In addition to the H-T phase diagram established below 7 T, NMR and specific heat experiments on polycrystal CeCu 2.05Si 2 have revealed the presence of a new phase above 7 T. In a high-quality polycrystal of UPd 2Al 3 with a record high- Tc of 2 K at ambient pressure and the narrowest Al NQR line width, the nuclear-spin lattice relaxation rate, 27(1/ T1) measured in zero field has been found to obey the T3 law down to 0.13 K, giving strong evidence that the energy gap vanishes along lines on the Fermi surface. Thus it seems that all heavy-electron superconductors exhibit lines of zero gap, regardless of their different magnetic properties.

  4. Bound states in strongly correlated magnetic and electronic systems

    International Nuclear Information System (INIS)

    Trebst, S.

    2002-02-01

    A novel strong coupling expansion method to calculate two-particle spectra of quantum lattice models is developed. The technique can be used to study bosonic and fermionic models and in principle it can be applied to systems in any dimension. A number of strongly correlated magnetic and electronic systems are examined including the two-leg spin-half Heisenberg ladder, the dimerized Heisenberg chain with a frustrating next-nearest neighbor interaction, coupled Heisenberg ladders, and the one-dimensional Kondo lattice model. In the various models distinct bound states are found below the two-particle continuum. Quantitative calculations of the dispersion, coherence length and binding energy of these bound states are used to describe spectroscopic experiments on (Ca,La) 14 Cu 24 O 41 and NaV 2 O 5 . (orig.)

  5. Muon spin relaxation studies in strongly correlated electron systems

    Science.gov (United States)

    Uemura, Y. J.; Luke, G. M.

    1993-05-01

    We describe recent progress of muon spin relaxation (μSR) studies in heavy-fermion (HF) and other strongly correlated electron systems. Measurements of the magnetic field penetration depth λ in HF superconductors UPt 3, URu 2Si 2, UPd 2Al 3 and U 2PtC 2 have revealed that these systems are characterized by large ratios Tc/ TF = 0.1-0.01 of Tc vs Fermi temperature TF derived from λ. This feature is common to high- Tc cuprate and other exotic superconductors. Zero-field μSR studies of magnetic order have elucidated a cross-over from spin glass ordering to nonmagnetic ground states in the ‘quadrupolar Kondo regime’ of (Y 1- xU x)Pd 3, and also suggested a possibility of incommensurate spin-density-wave (SDW) ordering in UNi 2Al 3.

  6. PREFACE: International Conference on Strongly Correlated Electron Systems (SCES 2011)

    Science.gov (United States)

    Littlewood, P. B.; Lonzarich, G. G.; Saxena, S. S.; Sutherland, M. L.; Sebastian, S. E.; Artacho, E.; Grosche, F. M.; Hadzibabic, Z.

    2012-11-01

    The Strongly Correlated Electron Systems Conference (SCES) 2011, was held from 29 August-3 September 2011, in Cambridge, UK. SCES'2011 was dedicated to 100 years of superconductivity and covered a range of topics in the area of strongly correlated systems. The correlated electronic and magnetic materials featured include f-electron based heavy fermion intermetallics and d-electron based transition metal compounds. The meeting welcomed to Cambridge 657 participants from 23 countries, who presented 127 talks (including 16 plenary, 57 invited, and 54 contributed) and 736 posters in 40 sessions over five full days of meetings. This proceedings volume contains papers reporting on the science presented at the meeting. This work deepens our understanding of the rich physical phenomena that arise from correlation effects. Strongly correlated systems are known for their remarkable array of emergent phenomena: the traditional subjects of superconductivity, magnetism and metal-insulator transitions have been joined by non-Fermi liquid phenomena, topologically protected quantum states, atomic and photonic gases, and quantum phase transitions. These are some of the most challenging and interesting phenomena in science. As well as the science driver, there is underlying interest in energy-dense materials, which make use of 'small' electrons packed to the highest possible density. These are by definition 'strongly correlated'. For example: good photovoltaics must be efficient optical absorbers, which means that photons will generate tightly bound electron-hole pairs (excitons) that must then be ionised at a heterointerface and transported to contacts; efficient solid state refrigeration depends on substantial entropy changes in a unit cell, with large local electrical or magnetic moments; efficient lighting is in a real sense the inverse of photovoltaics; the limit of an efficient battery is a supercapacitor employing mixed valent ions; fuel cells and solar to fuel conversion

  7. Superconductivity in strongly correlated electron systems: successes and open questions

    International Nuclear Information System (INIS)

    Shastry, B. Sriram

    2000-01-01

    Correlated electronic systems and superconductivity is a field which has unique track record of producing exciting new phases of matter. The article gives an overview of trends in solving the problems of superconductivity and correlated electronic systems

  8. The Electron-Phonon Interaction in Strongly Correlated Systems

    International Nuclear Information System (INIS)

    Castellani, C.; Grilli, M.

    1995-01-01

    We analyze the effect of strong electron-electron repulsion on the electron-phonon interaction from a Fermi-liquid point of view and show that the electron-electron interaction is responsible for vertex corrections, which generically lead to a strong suppression of the electron-phonon coupling in the v F q/ω >>1 region, while such effect is not present when v F q/ω F is the Fermi velocity and q and ω are the transferred momentum and frequency respectively. In particular the e-ph scattering is suppressed in transport properties which are dominated by low-energy-high-momentum processes. On the other hand, analyzing the stability criterion for the compressibility, which involves the effective interactions in the dynamical limit, we show that a sizable electron-phonon interaction can push the system towards a phase-separation instability. Finally a detailed analysis of these ideas is carried out using a slave-boson approach for the infinite-U three-band Hubbard model in the presence of a coupling between the local hole density and a dispersionless optical phonon. (author)

  9. Quantum phase transitions of strongly correlated electron systems

    International Nuclear Information System (INIS)

    Imada, Masatoshi

    1998-01-01

    Interacting electrons in solids undergo various quantum phase transitions driven by quantum fluctuations. The quantum transitions take place at zero temperature by changing a parameter to control quantum fluctuations rather than thermal fluctuations. In contrast to classical phase transitions driven by thermal fluctuations, the quantum transitions have many different features where quantum dynamics introduces a source of intrinsic fluctuations tightly connected with spatial correlations and they have been a subject of recent intensive studies as we see below. Interacting electron systems cannot be fully understood without deep analyses of the quantum phase transitions themselves, because they are widely seen and play essential roles in many phenomena. Typical and important examples of the quantum phase transitions include metal-insulator transitions, (2, 3, 4, 5, 6, 7, 8, 9) metal-superconductor transitions, superconductor-insulator transitions, magnetic transitions to antiferromagnetic or ferromagnetic phases in metals as well as in Mott insulators, and charge ordering transitions. Here, we focus on three different types of transitions

  10. Excitonic condensation in systems of strongly correlated electrons

    Czech Academy of Sciences Publication Activity Database

    Kuneš, Jan

    2015-01-01

    Roč. 27, č. 33 (2015), s. 333201 ISSN 0953-8984 Institutional support: RVO:68378271 Keywords : electronic correlations * exciton * Bose-Einstein condensation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.209, year: 2015

  11. Extended Aharonov-Bohm period analysis of strongly correlated electron systems

    OpenAIRE

    Arita, Ryotaro; Kusakabe, Koichi; Kuroki, Kazuhiko; Aoki, Hideo

    1996-01-01

    The `extended Aharonov-Bohm (AB) period' recently proposed by Kusakabe and Aoki [J. Phys. Soc. Jpn (65), 2772 (1996)] is extensively studied numerically for finite size systems of strongly correlated electrons. While the extended AB period is the system length times the flux quantum for noninteracting systems, we have found the existence of the boundary across which the period is halved or another boundary into an even shorter period on the phase diagram for these models. If we compare this r...

  12. Magnetic and resonant X-ray scattering investigations of strongly correlated electron systems

    International Nuclear Information System (INIS)

    Paolasini, L.; Bergevin, F. de

    2008-01-01

    Resonant X-ray scattering is a method which combines high-Q resolution X-ray elastic diffraction and atomic core-hole spectroscopy for investigating electronic and magnetic long-range ordered structures in condensed matter. During recent years the development of theoretical models to describe resonant X-ray scattering amplitudes and the evolution of experimental techniques, which include the control and analysis of linear photon polarization and the introduction of extreme environment conditions such as low temperatures, high magnetic field and high pressures, have opened a new field of investigation in the domain of strongly correlated electron systems. (authors)

  13. Long Range Order and Spin-Fluctuations in Strongly Correlated Electron System with Valence Instability

    Science.gov (United States)

    Alekseev, P. A.; Menushenkov, A. P.; Mignot, J.-M.; Nemkovski, K. S.; Yaroslavtsev, A. A.; Kozlenko, D. P.

    Rare-earth based strongly correlated electron systems (SCES) exhibit a large variety of different ground states, ranging from the simple paramagnetism of crystal-field-split f-electron multiplets to highly unconventional Kondo-insulator states with a combination of charge gap, spin gap and valence instability, in which long-range magnetic order can eventually arise from an initially singlet state. The physical background for these properties of the electron subsystem may be clarified by performing detailed neutron scattering experiments, namely magnetic neutron scattering spectroscopy and diffraction. This report reviews the results of the previous and new experimental studies on a number of rare-earth intermetallic compounds, which shed light on peculiar features of those unusual ground states.

  14. Electronic Structure of Strongly Correlated Materials

    CERN Document Server

    Anisimov, Vladimir

    2010-01-01

    Electronic structure and physical properties of strongly correlated materials containing elements with partially filled 3d, 4d, 4f and 5f electronic shells is analyzed by Dynamical Mean-Field Theory (DMFT). DMFT is the most universal and effective tool used for the theoretical investigation of electronic states with strong correlation effects. In the present book the basics of the method are given and its application to various material classes is shown. The book is aimed at a broad readership: theoretical physicists and experimentalists studying strongly correlated systems. It also serves as a handbook for students and all those who want to be acquainted with fast developing filed of condensed matter physics.

  15. Holstein-Primakoff representation and supercoherent states for strongly correlated electron systems

    International Nuclear Information System (INIS)

    Azakov, S.

    1999-09-01

    First we show that the algebra of operators entering the Hamiltonian of the t-J model describing the strongly correlated electron system is graded spl(2.1) algebra. Then after a brief discussion of its atypical representations we construct the Holstein-Primakoff nonlinear realization of these operators which allows to carry out the systematic semiclassical approximation, similarly to the spin-wave theory of localized magnetism. The fact that the t-J model describes the itinerant magnetism is reflected in the presence of the spinless fermions. For the supersymmetric spl(2.1) algebra the supercoherent states are proposed and the partition function of the t-J model is represented as a path integral with the help of these states. (author)

  16. Strongly Correlated Electron Systems in The Half Filled Band of The ...

    African Journals Online (AJOL)

    Strong correlation of interacting electrons has been widely studied under the single band Hubbard model with the aid of several techniques. These numerous studies have been carried out at different band filling. In this work, the ground state properties in the half filled band in one dimension are studied employing a ...

  17. Strongly correlated systems experimental techniques

    CERN Document Server

    Mancini, Ferdinando

    2015-01-01

    The continuous evolution and development of experimental techniques is at the basis of any fundamental achievement in modern physics. Strongly correlated systems (SCS), more than any other, need to be investigated through the greatest variety of experimental techniques in order to unveil and crosscheck the numerous and puzzling anomalous behaviors characterizing them. The study of SCS fostered the improvement of many old experimental techniques, but also the advent of many new ones just invented in order to analyze the complex behaviors of these systems. Many novel materials, with functional properties emerging from macroscopic quantum behaviors at the frontier of modern research in physics, chemistry and materials science, belong to this class of systems. The volume presents a representative collection of the modern experimental techniques specifically tailored for the analysis of strongly correlated systems. Any technique is presented in great detail by its own inventor or by one of the world-wide recognize...

  18. Intricacies of modern supercomputing illustrated with recent advances in simulations of strongly correlated electron systems

    Science.gov (United States)

    Schulthess, Thomas C.

    2013-03-01

    The continued thousand-fold improvement in sustained application performance per decade on modern supercomputers keeps opening new opportunities for scientific simulations. But supercomputers have become very complex machines, built with thousands or tens of thousands of complex nodes consisting of multiple CPU cores or, most recently, a combination of CPU and GPU processors. Efficient simulations on such high-end computing systems require tailored algorithms that optimally map numerical methods to particular architectures. These intricacies will be illustrated with simulations of strongly correlated electron systems, where the development of quantum cluster methods, Monte Carlo techniques, as well as their optimal implementation by means of algorithms with improved data locality and high arithmetic density have gone hand in hand with evolving computer architectures. The present work would not have been possible without continued access to computing resources at the National Center for Computational Science of Oak Ridge National Laboratory, which is funded by the Facilities Division of the Office of Advanced Scientific Computing Research, and the Swiss National Supercomputing Center (CSCS) that is funded by ETH Zurich.

  19. Electronic structure and superconductivity in strongly correlated systems in the pseudogap regime

    Energy Technology Data Exchange (ETDEWEB)

    Puig-Puig, L.; Lopez-Aguilar, F. [Grup d`Electromagnetisme, Departament de Fisica, Edifici Cn, Universitat Autonoma de Barcelona, E-08193 Ballaterra (Barcelona) (Spain)

    1995-12-15

    We propose effective potentials from a screened Coulomb interaction which arises from spin-fluctuation effects within a three-dimensional Hubbard single-band model for systems with strongly correlated electrons within the pseudogap regime. This regime is characterized by the existence in the normal state of at least two structures located at both sides of the Fermi level and split by a gap or pseudogap. This is the most crucial assumption in the analysis performed in this work. We consider the proposed effective interactions between fermions, analyzing the possibility of obtaining superconductivity by means of the formulation of the corresponding Dyson-like equations for the normal and anomalous one-body propagators in the state with bosonic condensation. We also include vertex effects within these effective fermion-fermion interactions and discuss their influence in this formalism in order to consider a Migdal-like theory appropriate to Hubbard systems. In cases where superconductivity is found, the critical temperature is obtained and the influence of the band and potential parameters is analyzed.

  20. Strongly Correlated Systems Theoretical Methods

    CERN Document Server

    Avella, Adolfo

    2012-01-01

    The volume presents, for the very first time, an exhaustive collection of those modern theoretical methods specifically tailored for the analysis of Strongly Correlated Systems. Many novel materials, with functional properties emerging from macroscopic quantum behaviors at the frontier of modern research in physics, chemistry and materials science, belong to this class of systems. Any technique is presented in great detail by its own inventor or by one of the world-wide recognized main contributors. The exposition has a clear pedagogical cut and fully reports on the most relevant case study where the specific technique showed to be very successful in describing and enlightening the puzzling physics of a particular strongly correlated system. The book is intended for advanced graduate students and post-docs in the field as textbook and/or main reference, but also for other researchers in the field who appreciates consulting a single, but comprehensive, source or wishes to get acquainted, in a as painless as po...

  1. Strongly correlated systems numerical methods

    CERN Document Server

    Mancini, Ferdinando

    2013-01-01

    This volume presents, for the very first time, an exhaustive collection of those modern numerical methods specifically tailored for the analysis of Strongly Correlated Systems. Many novel materials, with functional properties emerging from macroscopic quantum behaviors at the frontier of modern research in physics, chemistry and material science, belong to this class of systems. Any technique is presented in great detail by its own inventor or by one of the world-wide recognized main contributors. The exposition has a clear pedagogical cut and fully reports on the most relevant case study where the specific technique showed to be very successful in describing and enlightening the puzzling physics of a particular strongly correlated system. The book is intended for advanced graduate students and post-docs in the field as textbook and/or main reference, but also for other researchers in the field who appreciate consulting a single, but comprehensive, source or wishes to get acquainted, in a as painless as possi...

  2. Finite-Temperature Variational Monte Carlo Method for Strongly Correlated Electron Systems

    Science.gov (United States)

    Takai, Kensaku; Ido, Kota; Misawa, Takahiro; Yamaji, Youhei; Imada, Masatoshi

    2016-03-01

    A new computational method for finite-temperature properties of strongly correlated electrons is proposed by extending the variational Monte Carlo method originally developed for the ground state. The method is based on the path integral in the imaginary-time formulation, starting from the infinite-temperature state that is well approximated by a small number of certain random initial states. Lower temperatures are progressively reached by the imaginary-time evolution. The algorithm follows the framework of the quantum transfer matrix and finite-temperature Lanczos methods, but we extend them to treat much larger system sizes without the negative sign problem by optimizing the truncated Hilbert space on the basis of the time-dependent variational principle (TDVP). This optimization algorithm is equivalent to the stochastic reconfiguration (SR) method that has been frequently used for the ground state to optimally truncate the Hilbert space. The obtained finite-temperature states allow an interpretation based on the thermal pure quantum (TPQ) state instead of the conventional canonical-ensemble average. Our method is tested for the one- and two-dimensional Hubbard models and its accuracy and efficiency are demonstrated.

  3. Local Magnetism in Strongly Correlated Electron Systems with Orbital Degrees of Freedom

    Science.gov (United States)

    Ducatman, Samuel Charles

    The central aim of my research is to explain the connection between the macroscopic behavior and the microscopic physics of strongly correlated electron systems with orbital degrees of freedom through the use of effective models. My dissertation focuses on the sub-class of these materials where electrons appear to be localized by interactions, and magnetic ions have well measured magnetic moments. This suggests that we can capture the low-energy physics of the material by employing a minimal model featuring localized spins which interact with each other through exchange couplings. I describe Fe1+y Te and beta-Li2IrO3 with effective models primarily focusing on the spins of the magnetic ions, in this case Fe and Ir, respectively. The goal with both materials is to gain insight and make predictions for experimentalists. In chapter 2, I focus on Fe1+yTe. I describe why we believe the magnetic ground state of this material, with an observed Bragg peak at Q +/- pi/2, pi/2), can be described by a Heisenberg model with 1st, 2nd, and 3rd neighbor interactions. I present two possible ground states of this model in the small J1 limit, the bicollinear and plaquette states. In order to predict which ground state the model prefers, I calculate the spin wave spectrum with 1/S corrections, and I find the model naturally selects the "plaquette state." I give a brief description of the ways this result could be tested using experimental techniques such as polarized neutron scattering. In chapter 3, I extend the model used in chapter 2. This is necessary because the Heisenberg model we employed cannot explain why Fe1+yTe undergoes a phase transition as y is increased. We add an additional elements to our calculation; we assume that electrons in some of the Fe 3D orbitals have selectively localized while others remain itinerant. We write a new Hamiltonian, where localized moments acquire a new long-range RKKY-like interaction from interactions with the itinerant electrons. We are

  4. PREFACE: International Conference on Strongly Correlated Electron Systems 2014 (SCES2014)

    Science.gov (United States)

    2015-03-01

    The 2014 International Conference on Strongly Correlated Electron Systems (SCES) was held in Grenoble from the 7th to 11th of July on the campus of the University of Grenoble. It was a great privilege to have the conference in Grenoble after the series of meetings in Sendai (1992), San Diego (1993), Amsterdam (1994), Goa (1995), Zürich (1996), Paris (1998), Nagano (1999), Ann Arbor (2001), Krakow (2002), Karlsruhe (2004), Vienna (2005), Houston (2007), Buzios (2008), Santa Fe (2010), Cambridge (2011) and Tokyo (2013). Every three years, SCES joins the triennial conference on magnetism ICM. In 2015, ICM will take place in Barcelona. The meeting gathered an audience of 875 participants who actively interacted inside and outside of conference rooms. A large number of posters (530) was balanced with four parallel oral sessions which included 86 invited speakers and 141 short oral contributions. A useful arrangement was the possibility to put poster presentations on the website so participants could see them all through the conference week. Each morning two plenary sessions were held, ending on Friday with experimental and theoretical summaries delivered by Philipp Gegenwart (Augsburg) and Andrew Millis (Columbia). The plenary sessions were given by Gabriel Kotliar (Rutgers), Masashi Kawasaki (Tokyo), Jennifer Hoffman (Harvard), Mathias Vojta (Dresden), Ashvin Vishwanath (Berkeley), Andrea Cavalleri (Hamburg), Marc-Henri Julien (Grenoble), Neil Mathur (Cambridge), Giniyat Khaliullin (Stuttgart), and Toshiro Sakakibara (Tokyo). The parallel oral sessions were prepared by 40 symposium organizers selected by the chairman (Antoine Georges) and co-chairman (Kamran Behnia) of the Program Committee with the supplementary rule that speakers had not delivered an invited talk at the previous SCES conference held in 2013 in Tokyo. Special attention was given to help young researchers via grants to 40 overseas students. Perhaps due to the additional possibility of cheap

  5. On strongly correlated N-electron systems | Enaibe | Journal of the ...

    African Journals Online (AJOL)

    An attempt is made in this work to extend the correlated variational approach of Chen and Mei [1], which was developed for two-electron systems, to N-electron systems (N>2). Preliminary results are reported here for four electrons interacting under a Hubbard-type potential in a one-dimensional lattice with only four sites

  6. Phase separation in strongly correlated electron systems with two types of charge carriers

    International Nuclear Information System (INIS)

    Kugel, K.I.; Rakhmanov, A.L.; Sboychakov, A.O.

    2007-01-01

    Full text: A competition between the localization of the charge carriers due to Jahn-Teller distortions and the energy gain due to their delocalization in doped manganite and related magnetic oxides is analyzed based on a Kondo-lattice type model. The resulting effective Hamiltonian is, in fact, a generalization of the Falicov-Kimball model. We find that the number of itinerant charge carriers can be significantly lower than that implied by the doping level x. The phase diagram of the model in the T plane is constructed. The system exhibits magnetic ordered (antiferromagnetic, ferromagnetic, or canted) states as well the paramagnetic states with zero and nonzero density of the itinerant electrons. It is shown that a phase-separation is favorable in energy for a wide doping range. The characteristic size of inhomogeneities in a phase-separated state is of the order of several lattice constants. We also analyzed the two-band Hubbard model in the limit of strong on-site Coulomb repulsion. It was shown that such a system has a tendency to phase separation into the regions with different charge densities even in the absence of magnetic or any other ordering, if the ratio of the bandwidths is large enough. The work was supported by the European project CoMePhS and by the Russian Foundation for Basic Research, project no. 05-02-17600. (authors)

  7. Quantum Transport in Strongly Correlated Systems

    DEFF Research Database (Denmark)

    Bohr, Dan

    2007-01-01

    the density matrix renormalization group (DMRG) method. We present two DMRG setups for calculating the linear conductance of strongly correlated nanostructures in the infinitesimal source-drain voltage regime. The first setup describes the leads by modified real-space tight-binding chains, whereas the second...... screening plays a much less significant role than in bulk systems due to the reduced size of the objects, therefore making it necessary to consider the importance of correlations between electrons. The work presented in this thesis deals with quantum transport through strongly correlated systems using....... Thus both coherence and correlation effects are important in this model, and the methods applied should be able to handle both these effects rigorously. We present the DMRG setup for this model and benchmark against existing Greens function results for the model. Then we present initial DMRG results...

  8. Photoemission in strongly correlated crystalline f-electron systems: A need for a new approach

    Energy Technology Data Exchange (ETDEWEB)

    Arko, A.J.; Joyce, J.J.; Sarrao, J. [and others

    1998-12-01

    The unusual properties of heavy fermion (or heavy electron) materials have sparked an avalanche of research over the last two decades in order to understand the basic phenomena responsible for these properties. Photoelectron spectroscopy (often referred to as PES in the following sections), the most direct measurement of the electronic structure of a material, should in principle be able to shed considerable light on this matter. In general the distinction between a localized and a band-like state is trivially observed in band dispersion. Much of the past work was performed on poly-crystalline samples, scraped in-situ to expose a clean surface for PES. There have since been considerable advances both in the quality of specimens as well as experimental resolution, which raise questions regarding these conclusions. Much of the past work on poly-crystalline samples has been reported in several review articles, most notably Allen et al., and it is not necessary here to review those efforts again, with the exception of subsequent work performed at high resolution. The primary focus of the present review will be on new measurements obtained on single crystals, cleaved or prepared in situ and measured at high resolution, which seem to suggest that agreement with the GS and NCA approximations is less than perfect, and that perhaps the starting models need to be modified, or that even an entirely new approach is called for. Of the promising new models the Periodic Anderson Model is most closely related to the SIM. Indeed, at high temperatures it reverts to the SIM. However, the charge polaron model of Liu (1997) as well as the two-electron band model of Sheng and Cooper (1995) cannot yet be ruled out. Inasmuch as the bulk of the single crystal work was performed by the Los Alamos group, this review will draw heavily on those results. Moreover, since the GS and NCA approximations represent the most comprehensive and widely accepted treatment of heavy fermion PES, it is only

  9. Onset of magnetic order in strongly-correlated systems from ab initio electronic structure calculations: application to transition metal oxides

    Science.gov (United States)

    Hughes, I. D.; Däne, M.; Ernst, A.; Hergert, W.; Lüders, M.; Staunton, J. B.; Szotek, Z.; Temmerman, W. M.

    2008-06-01

    We describe an ab initio theory of finite temperature magnetism in strongly-correlated electron systems. The formalism is based on spin density functional theory, with a self-interaction corrected local spin density approximation (SIC-LSDA). The self-interaction correction is implemented locally, within the Kohn-Korringa-Rostoker (KKR) multiple-scattering method. Thermally induced magnetic fluctuations are treated using a mean-field 'disordered local moment' (DLM) approach and at no stage is there a fitting to an effective Heisenberg model. We apply the theory to the 3d transition metal oxides, where our calculations reproduce the experimental ordering tendencies, as well as the qualitative trend in ordering temperatures. We find a large insulating gap in the paramagnetic state which hardly changes with the onset of magnetic order.

  10. Universal behavior of strongly correlated Fermi systems

    Energy Technology Data Exchange (ETDEWEB)

    Shaginyan, Vasilii R [B.P. Konstantinov St. Petersburg Institute of Nuclear Physics, Russian Academy of Sciences, Gatchina, Leningrad region, Rusian Federation (Russian Federation); Amusia, M Ya [A.F. Ioffe Physico-Technical Institute, Russian Academy of Sciences, St. Petersburg (Russian Federation); Popov, Konstantin G [Komi Scientific Center, Ural Branch of the Russian Academy of Sciences, Syktyvkar (Russian Federation)

    2007-06-30

    This review discusses the construction of a theory and the analysis of phenomena occurring in strongly correlated Fermi systems such as high-T{sub c} superconductors, heavy-fermion metals, and quasi-two-dimensional Fermi systems. It is shown that the basic properties and the universal behavior of strongly correlated Fermi systems can be described in the framework of the Fermi-condensate quantum phase transition and the well-known Landau paradigm of quasiparticles and the order parameter. The concept of fermion condensation may be fruitful in studying neutron stars, finite Fermi systems, ultra-cold gases in traps, and quark plasma. (reviews of topical problems)

  11. Universal behavior of strongly correlated Fermi systems

    International Nuclear Information System (INIS)

    Shaginyan, Vasilii R; Amusia, M Ya; Popov, Konstantin G

    2007-01-01

    This review discusses the construction of a theory and the analysis of phenomena occurring in strongly correlated Fermi systems such as high-T c superconductors, heavy-fermion metals, and quasi-two-dimensional Fermi systems. It is shown that the basic properties and the universal behavior of strongly correlated Fermi systems can be described in the framework of the Fermi-condensate quantum phase transition and the well-known Landau paradigm of quasiparticles and the order parameter. The concept of fermion condensation may be fruitful in studying neutron stars, finite Fermi systems, ultra-cold gases in traps, and quark plasma. (reviews of topical problems)

  12. Calculations of the one-body electronic structure of the strongly correlated systems including self-energy effects

    Energy Technology Data Exchange (ETDEWEB)

    Costa-Quintana, J.; Sanchez-Lopez, M.M.; Lopez-Aguilar, F. [Grup d`Electromagnetisme, Edifici Cn, Universitat Autonoma de Barcelona 08193, Bellaterra, Barcelona (Spain)

    1996-10-01

    We give a method to obtain the quasiparticle band structure and renormalized density of states by diagonalizing the interacting system Green function. This method operates for any self-energy approximation appropriated to strongly correlated systems. Application to CeSi{sub 2} and YBa{sub 2}Cu{sub 3}O{sub 7} is analyzed as a probe for this band calculation method. {copyright} {ital 1996 The American Physical Society.}

  13. Quantum Liquid Crystal Phases in Strongly Correlated Fermionic Systems

    Science.gov (United States)

    Sun, Kai

    2009-01-01

    This thesis is devoted to the investigation of the quantum liquid crystal phases in strongly correlated electronic systems. Such phases are characterized by their partially broken spatial symmetries and are observed in various strongly correlated systems as being summarized in Chapter 1. Although quantum liquid crystal phases often involve…

  14. The contribution of Diamond Light Source to the study of strongly correlated electron systems and complex magnetic structures.

    Science.gov (United States)

    Radaelli, P G; Dhesi, S S

    2015-03-06

    We review some of the significant contributions to the field of strongly correlated materials and complex magnets, arising from experiments performed at the Diamond Light Source (Harwell Science and Innovation Campus, Didcot, UK) during the first few years of operation (2007-2014). We provide a comprehensive overview of Diamond research on topological insulators, multiferroics, complex oxides and magnetic nanostructures. Several experiments on ultrafast dynamics, magnetic imaging, photoemission electron microscopy, soft X-ray holography and resonant magnetic hard and soft X-ray scattering are described. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  15. Phase diagram of strongly correlated Fermi systems

    International Nuclear Information System (INIS)

    Zverev, M.V.; Khodel', V.A.; Baldo, M.

    2000-01-01

    Phase transitions in uniform Fermi systems with repulsive forces between the particles caused by restructuring of quasiparticle filling n(p) are analyzed. It is found that in terms of variables, i.e. density ρ, nondimensional binding constant η, phase diagram of a strongly correlated Fermi system for rather a wide class of interactions reminds of a puff-pastry pie. Its upper part is filled with fermion condensate, the lower one - with normal Fermi-liquid. They are separated by a narrow interlayer - the Lifshits phase, characterized by the Fermi multibound surface [ru

  16. Magnetic and resonant X-ray scattering investigations of strongly correlated electron systems; Etude de systemes electroniques fortement correles par diffusion magnetique et resonnante des rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Paolasini, L.; Bergevin, F. de [European Synchrotron Radiation Facility, 38 - Grenoble (France)

    2008-06-15

    Resonant X-ray scattering is a method which combines high-Q resolution X-ray elastic diffraction and atomic core-hole spectroscopy for investigating electronic and magnetic long-range ordered structures in condensed matter. During recent years the development of theoretical models to describe resonant X-ray scattering amplitudes and the evolution of experimental techniques, which include the control and analysis of linear photon polarization and the introduction of extreme environment conditions such as low temperatures, high magnetic field and high pressures, have opened a new field of investigation in the domain of strongly correlated electron systems. (authors)

  17. Predictive Modeling for Strongly Correlated f-electron Systems: A first-principles and database driven machine learning approach

    Science.gov (United States)

    Ahmed, Towfiq; Khair, Adnan; Abdullah, Mueen; Harper, Heike; Eriksson, Olle; Wills, John; Zhu, Jian-Xin; Balatsky, Alexander

    Data driven computational tools are being developed for theoretical understanding of electronic properties in f-electron based materials, e.g., Lanthanides and Actnides compounds. Here we show our preliminary work on Ce compounds. Due to a complex interplay among the hybridization of f-electrons to non-interacting conduction band, spin-orbit coupling, and strong coulomb repulsion of f-electrons, no model or first-principles based theory can fully explain all the structural and functional phases of f-electron systems. Motivated by the large need in predictive modeling of actinide compounds, we adopted a data-driven approach. We found negative correlation between the hybridization and atomic volume. Mutual information between these two features were also investigated. In order to extend our search space with more features and predictability of new compounds, we are currently developing electronic structure database. Our f-electron database will be potentially aided by machine learning (ML) algorithm to extract complex electronic, magnetic and structural properties in f-electron system, and thus, will open up new pathways for predictive capabilities and design principles of complex materials. NSEC, IMS at LANL.

  18. TRANSPORT PROPERTIES OF THE STRONGLY CORRELATED SYSTEMS

    Directory of Open Access Journals (Sweden)

    T.Domanski

    2004-01-01

    Full Text Available The transport properties of various systems are studied here in the context of three different models. These are: - the disordered Hubbard model applicable to correlated binary alloys with a general disorder, - the Anderson model used in describing the Kondo physics of a quantum dot connected to the external superconducting leads, and - the Ranninger-Robaszkiewicz model applied to the study of optical properties of the system with preformed electron pairs above the temperature of transition to the superconducting state. We calculate the density of states, specific heat, the Wilson ratio and conductivity of the correlated binary alloy with off-diagonal disorder. We investigate the conditions under which the Kondo peak appears in the density of states and in the conductance of a dot coupled to the external superconducting leads. We analyze the effect of the pseudogap on the optical spectra in the high temperature superconductors described by the boson-fermion model.

  19. Multiorbital simplified parquet equations for strongly correlated electrons

    Czech Academy of Sciences Publication Activity Database

    Augustinský, Pavel; Janiš, Václav

    2011-01-01

    Roč. 83, č. 3 (2011), "035114-1"-"035114-13" ISSN 1098-0121 R&D Projects: GA ČR(CZ) GC202/07/J047 Institutional research plan: CEZ:AV0Z10100520 Keywords : multi-orbital model * strongly correlated electrons * parquet equations * Kondo regime Subject RIV: BE - Theoretical Physics Impact factor: 3.691, year: 2011 http://prb.aps.org/abstract/PRB/v83/i3/e035114

  20. PREFACE: Introduction to Strongly Correlated Electrons in New Materials

    Science.gov (United States)

    Kusmartsev, Feo V.

    2003-09-01

    The discovery of new natural and artificial materials has revolutionized condensed matter physics and our views on the role of correlations between electrons. Novel properties such as high-temperature superconductivity and colossal magnetoresistance discovered in these materials have overturned our conventional representations of condensed matter physics and pushed us to reconsider many well-established concepts. For example, we must treat the Coulomb interaction between electrons far beyond perturbation theory; we must recall long-forgotten ideas of electronic phase separation introduced originally by Nagaev in the 1960s; we must reconsider the role of electron--phonon and electron--magnon interactions, orbital degrees of freedom, the Rashba effect and many other aspects of condensed matter physics that are becoming increasingly important. In many novel materials, such as the two-dimensional electron gas, the energy associated with the Coulomb interaction is typically of the order of (or even larger than) the kinetic energy of electrons or the Fermi energy. Therefore perturbation theory and associated renormalization group methods are not applicable to these situations and we may expect to find a novel state of matter associated with correlation effects. It is worth mentioning the known examples of these states proposed recently, such as marginal Fermi liquids, novel metal--insulator phase transitions in the two-dimensional electron gas associated with new metallic and insulating states, structured liquids, microscopic electronic phase separations, stripes, strings, polarons and others. The discussion of these states is now on the frontier of modern condensed matter physics and is partially covered in this special issue. The demand to treat the Coulomb interaction properly has stimulated a development of many-body theory, which considers correlations as fully as possible. Strong correlations may play an important role in the dynamics of the electronic system. In a

  1. Theory and simulation of strong correlations in quantum Coulomb systems

    Science.gov (United States)

    Bonitz, M.; Semkat, D.; Filinov, A.; Golubnychyi, V.; Kremp, D.; Gericke, D. O.; Murillo, M. S.; Filinov, V.; Fortov, V.; Hoyer, W.; Koch, S. W.

    2003-06-01

    Strong correlations in quantum Coulomb systems (QCS) are attracting increasing interest in many fields ranging from dense plasmas and semiconductors to metal clusters and ultracold trapped ions. Examples are bound states in dense plasmas (atoms, molecules, clusters) and semiconductors (excitons, trions, biexcitons) or Coulomb crystals. We present first-principle simulation results of these systems including path integral Monte Carlo simulations of the equilibrium behaviour of dense hydrogen and electron-hole plasmas and molecular dynamics and quantum kinetic theory simulations of the nonequilibrium properties of QCS. Finally, we critically assess potential and limitations of the various methods in their application to Coulomb systems.

  2. Strongly correlated electron physics in nanotube-encapsulated metallocene chains

    Science.gov (United States)

    García-Suárez, V. M.; Ferrer, J.; Lambert, C. J.

    2006-11-01

    The structural, electronic, and transport properties of metallocene molecules (MCp2) and isolated or nanotube-encapsulated metallocene chains are studied by using a combination of density functional theory and nonequilibrium Green’s functions. The analysis first discusses the whole series of isolated (MCp2) molecules, where M=V , Cr, Mn, Fe, Co, Ni, Ru, and Os. The series presents a rich range of electronic and magnetic behaviors due to the interplay between the crystal field interaction and Hund’s rules, as the occupation of the d shell increases. The article then shows how many of these interesting properties can also be seen when (MCp2) molecules are linked together to form periodic chains. Interestingly, a large portion of these chains display metallic, and eventually magnetic, behavior. These properties may render these systems as useful tools for spintronics applications but this is hindered by the lack of mechanical stability of the chains. It is finally argued that encapsulation of the chains inside carbon nanotubes, that is exothermic for radii larger than 4.5Å , provides the missing mechanical stability and electrical isolation. The structural stability, charge transfer, magnetic, and electronic behavior of the ensuing chains, as well as the modification of the electrostatic potential in the nanotube wall produced by the metallocenes are thoroughly discussed. We argue that the full devices can be characterized by two doped, strongly correlated Hubbard models whose mutual hybridization is almost negligible. The charge transferred from the chains produces a strong modification of the electrostatic potential in the nanotube walls, which is amplified in case of semiconducting and endothermic nanotubes. The transport properties of isolated metallocenes between semi-infinite nanotubes are also analyzed and shown to lead to important changes in the transmission coefficients of clean nanotubes for high energies.

  3. The strongly correlated electron systems CeNi sub 2 Ge sub 2 and Sr sub 2 RuO sub 4

    CERN Document Server

    Diver, A J

    1996-01-01

    susceptibility and magnetoresistance on a single crystal CeNi sub 2 Ge sub 2 sample are discussed. The low temperature resistivity is found to show non-Fermi liquid behaviour both at low field and at 16 T. Chapter four is concerned with the layered perovskite superconductor Sr sub 2 RuO sub 4 which has a very similar structure to the La sub 2 sub - sub x Sr sub x CuO sub 4 family of high-T sub c superconductors. De Haas-van Alphen oscillations were detected allowing a study in which all of the Fermi surface sheets were detected. These oscillations are analysed and shown to obey the form expected for a conventional Fermi liquid. The results are compared with the predictions of recent band structure calculations. Measurements of the Hall effect and upper critical field for superconductivity are explained in terms of the measured Fermi surface. Strongly correlated electron systems provide many challenges for condensed matter physics which attempts to find new ways to understand the behaviour of vast numbers of p...

  4. Exact Kohn-Sham potential of strongly correlated finite systems

    International Nuclear Information System (INIS)

    Helbig, N.; Tokatly, I. V.; Rubio, A.

    2009-01-01

    The dissociation of molecules, even the most simple hydrogen molecule, cannot be described accurately within density functional theory because none of the currently available functionals accounts for strong on-site correlation. This problem led to a discussion of properties that the local Kohn-Sham potential has to satisfy in order to correctly describe strongly correlated systems. We derive an analytic expression for the nontrivial form of the Kohn-Sham potential in between the two fragments for the dissociation of a single bond. We show that the numerical calculations for a one-dimensional two-electron model system indeed approach and reach this limit. It is shown that the functional form of the potential is universal, i.e., independent of the details of the two fragments.

  5. Neutron Scattering and Its Application to Strongly Correlated Systems

    OpenAIRE

    Zaliznyak, Igor A.; Tranquada, John M.

    2013-01-01

    Neutron scattering is a powerful probe of strongly correlated systems. It can directly detect common phenomena such as magnetic order, and can be used to determine the coupling between magnetic moments through measurements of the spin-wave dispersions. In the absence of magnetic order, one can detect diffuse scattering and dynamic correlations. Neutrons are also sensitive to the arrangement of atoms in a solid (crystal structure) and lattice dynamics (phonons). In this chapter, we provide an ...

  6. Strongly correlated electron materials. I. Theory of the quasiparticle structure

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Aguilar, F.; Costa-Quintana, J.; Puig-Puig, L. (Departamento de Fisica, Grupo de Electromagnetismo, Universidad Autonoma de Barcelona, Bellaterra, E-08193 Barcelona (Spain))

    1993-07-01

    In this paper we give a method for analyzing the renormalized electronic structure of the Hubbard systems. The first step is the determination of effective interactions from the random-phase approximation (RPA) and from an extended RPA (ERPA) that introduces vertex effects within the bubble polarization. The second step is the determination of the density of states deduced from the spectral functions. Its analysis leads us to conclude that these systems can exhibit three types of resonances in their electronic structures: the lower-, middle-, and upper-energy resonances. Furthermore, we analyze the conditions for which there is only one type of resonance and the causes that lead to the disappearance of the heavy-fermion state. We finally introduce the RPA and ERPA effective interactions within the strong-coupling theory and we give the conditions for obtaining coupling and superconductivity.

  7. Quantum simulation of strongly correlated condensed matter systems

    Science.gov (United States)

    Hofstetter, W.; Qin, T.

    2018-04-01

    We review recent experimental and theoretical progress in realizing and simulating many-body phases of ultracold atoms in optical lattices, which gives access to analog quantum simulations of fundamental model Hamiltonians for strongly correlated condensed matter systems, such as the Hubbard model. After a general introduction to quantum gases in optical lattices, their preparation and cooling, and measurement techniques for relevant observables, we focus on several examples, where quantum simulations of this type have been performed successfully during the past years: Mott-insulator states, itinerant quantum magnetism, disorder-induced localization and its interplay with interactions, and topological quantum states in synthetic gauge fields.

  8. STIR: Novel Electronic States by Gating Strongly Correlated Materials

    Science.gov (United States)

    2016-03-01

    TITLE AND SUBTITLE 13. SUPPLEMENTARY NOTES 12. DISTRIBUTION AVAILIBILITY STATEMENT 6. AUTHORS 7. PERFORMING ORGANIZATION NAMES AND ADDRESSES 15...REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR/MONITOR’S ACRONYM(S) ARO 8. PERFORMING ORGANIZATION REPORT NUMBER...channel limits induced electron density changes to approximately 1013 cm-2. This is sufficient to gate semiconducting materials, where the electronic

  9. Magnetic properties of metallic impurities with strongly correlated electrons

    Czech Academy of Sciences Publication Activity Database

    Janiš, Václav; Ringel, Matouš

    2009-01-01

    Roč. 115, č. 1 (2009), s. 30-35 ISSN 0587-4246 R&D Projects: GA ČR GA202/07/0644 Institutional research plan: CEZ:AV0Z10100520 Keywords : And erson impurity * strong electron correlations * spin-polarized solution * three-channel parquet equations * magnetic field Subject RIV: BE - Theoretical Physics Impact factor: 0.433, year: 2009 http://przyrbwn.icm.edu.pl/APP/ABSTR/115/a115-1-5.html

  10. Towards a large deviation theory for strongly correlated systems

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, Guiomar, E-mail: guiomar.ruiz@upm.es [Centro Brasileiro de Pesquisas Fisicas and National Institute of Science and Technology for Complex Systems, Rua Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ (Brazil); Departamento de Matemática Aplicada y Estadística, Universidad Politécnica de Madrid, Pza. Cardenal Cisneros s.n., 28040 Madrid (Spain); Tsallis, Constantino, E-mail: tsallis@cbpf.br [Centro Brasileiro de Pesquisas Fisicas and National Institute of Science and Technology for Complex Systems, Rua Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ (Brazil); Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501 (United States)

    2012-07-23

    A large-deviation connection of statistical mechanics is provided by N independent binary variables, the (N→∞) limit yielding Gaussian distributions. The probability of n≠N/2 out of N throws is governed by e{sup −Nr}, r related to the entropy. Large deviations for a strong correlated model characterized by indices (Q,γ) are studied, the (N→∞) limit yielding Q-Gaussians (Q→1 recovers a Gaussian). Its large deviations are governed by e{sub q}{sup −Nr{sub q}} (∝1/N{sup 1/(q−1)}, q>1), q=(Q−1)/(γ[3−Q])+1. This illustration opens the door towards a large-deviation foundation of nonextensive statistical mechanics. -- Highlights: ► We introduce the formalism of relative entropy for a single random binary variable and its q-generalization. ► We study a model of N strongly correlated binary random variables and their large-deviation probabilities. ► Large-deviation probability of strongly correlated model exhibits a q-exponential decay whose argument is proportional to N, as extensivity requires. ► Our results point to a q-generalized large deviation theory and suggest a large-deviation foundation of nonextensive statistical mechanics.

  11. Scaling of non-Ohmic conduction in strongly correlated systems

    Science.gov (United States)

    Talukdar, D.; Nandi, U. N.; Poddar, A.; Mandal, P.; Bardhan, K. K.

    2012-10-01

    A new scaling formalism is used to analyze nonlinear I-V data in the vicinity of metal-insulator transitions (MIT) in five manganite systems. An exponent, called the nonlinearity exponent, and an onset field for nonlinearity, both characteristic of the system under study, are obtained from the analysis. The onset field is found to have an anomalously low value corroborating the theoretically predicted electronically soft phases. The scaling functions above and below the MIT of a polycrystalline sample are found to be the same but with different exponents which are attributed to the distribution of the MIT temperatures. The applicability of the scaling in manganites underlines the universal response of the disordered systems to electric field.

  12. Electronic structure calculations of atomic transport properties in uranium dioxide: influence of strong correlations

    International Nuclear Information System (INIS)

    Dorado, B.

    2010-09-01

    Uranium dioxide UO 2 is the standard nuclear fuel used in pressurized water reactors. During in-reactor operation, the fission of uranium atoms yields a wide variety of fission products (FP) which create numerous point defects while slowing down in the material. Point defects and FP govern in turn the evolution of the fuel physical properties under irradiation. In this study, we use electronic structure calculations in order to better understand the fuel behavior under irradiation. In particular, we investigate point defect behavior, as well as the stability of three volatile FP: iodine, krypton and xenon. In order to take into account the strong correlations of uranium 5f electrons in UO 2 , we use the DFT+U approximation, based on the density functional theory. This approximation, however, creates numerous metastable states which trap the system and induce discrepancies in the results reported in the literature. To solve this issue and to ensure the ground state is systematically approached as much as possible, we use a method based on electronic occupancy control of the correlated orbitals. We show that the DFT+U approximation, when used with electronic occupancy control, can describe accurately point defect and fission product behavior in UO 2 and provide quantitative information regarding point defect transport properties in the oxide fuel. (author)

  13. Some Applications of Holography to Study Strongly Correlated Systems

    Directory of Open Access Journals (Sweden)

    Bhatnagar Neha

    2018-01-01

    Full Text Available In this work, we study the transport coefficients of strongly coupled condensed matter systems using gauge/gravity duality (holography. We consider examples from the real world and evaluate the conductivities from their gravity duals. Adopting the bottom-up approach of holography, we obtain the frequency response of the conductivity for (1+1-dimensional systems. We also evaluate the DC conductivities for non-relativistic condensed matter systems with hyperscaling violating geometry.

  14. Theoretical development and first-principles analysis of strongly correlated systems

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chen [Iowa State Univ., Ames, IA (United States)

    2016-12-17

    A variety of quantum many-body methods have been developed for studying the strongly correlated electron systems. We have also proposed a computationally efficient and accurate approach, named the correlation matrix renormalization (CMR) method, to address the challenges. The initial implementation of the CMR method is designed for molecules which have theoretical advantages, including small size of system, manifest mechanism and strongly correlation effect such as bond breaking process. The theoretic development and benchmark tests of the CMR method are included in this thesis. Meanwhile, ground state total energy is the most important property of electronic calculations. We also investigated an alternative approach to calculate the total energy, and extended this method for magnetic anisotropy energy (MAE) of ferromagnetic materials. In addition, another theoretical tool, dynamical mean- field theory (DMFT) on top of the DFT , has also been used in electronic structure calculations for an Iridium oxide to study the phase transition, which results from an interplay of the d electrons' internal degrees of freedom.

  15. Quantum Monte Carlo methods and strongly correlated electrons on honeycomb structures

    Energy Technology Data Exchange (ETDEWEB)

    Lang, Thomas C.

    2010-12-16

    In this thesis we apply recently developed, as well as sophisticated quantum Monte Carlo methods to numerically investigate models of strongly correlated electron systems on honeycomb structures. The latter are of particular interest owing to their unique properties when simulating electrons on them, like the relativistic dispersion, strong quantum fluctuations and their resistance against instabilities. This work covers several projects including the advancement of the weak-coupling continuous time quantum Monte Carlo and its application to zero temperature and phonons, quantum phase transitions of valence bond solids in spin-1/2 Heisenberg systems using projector quantum Monte Carlo in the valence bond basis, and the magnetic field induced transition to a canted antiferromagnet of the Hubbard model on the honeycomb lattice. The emphasis lies on two projects investigating the phase diagram of the SU(2) and the SU(N)-symmetric Hubbard model on the hexagonal lattice. At sufficiently low temperatures, condensed-matter systems tend to develop order. An exception are quantum spin-liquids, where fluctuations prevent a transition to an ordered state down to the lowest temperatures. Previously elusive in experimentally relevant microscopic two-dimensional models, we show by means of large-scale quantum Monte Carlo simulations of the SU(2) Hubbard model on the honeycomb lattice, that a quantum spin-liquid emerges between the state described by massless Dirac fermions and an antiferromagnetically ordered Mott insulator. This unexpected quantum-disordered state is found to be a short-range resonating valence bond liquid, akin to the one proposed for high temperature superconductors. Inspired by the rich phase diagrams of SU(N) models we study the SU(N)-symmetric Hubbard Heisenberg quantum antiferromagnet on the honeycomb lattice to investigate the reliability of 1/N corrections to large-N results by means of numerically exact QMC simulations. We study the melting of phases

  16. Disorder and pseudogap in strongly correlated systems: Phase diagram in the DMFT + Σ approach

    International Nuclear Information System (INIS)

    Kuleeva, N. A.; Kuchinskii, E. Z.

    2013-01-01

    The influence of disorder and pseudogap fluctuations on the Mott insulator-metal transition in strongly correlated systems has been studied in the framework of the generalized dynamic mean field theory (DMFT + Σ approach). Using the results of investigations of the density of states (DOS) and optical conductivity, a phase diagram (disorder-Hubbard interaction-temperature) is constructed for the paramagnetic Anderson-Hubbard model, which allows both the effects of strong electron correlations and the influence of strong disorder to be considered. Strong correlations are described using the DMFT, while a strong disorder is described using a generalized self-consistent theory of localization. The DOS and optical conductivity of the paramagnetic Hubbard model have been studied in a pseudogap state caused by antiferromagnetic spin (or charge) short-range order fluctuations with a finite correlation length, which have been modeled by a static Gaussian random field. The effect of a pseudogap on the Mott insulator-metal transition has been studied. It is established that, in both cases, the static Gaussian random field (related to the disorder or pseudogap fluctuations) leads to suppression of the Mott transition, broadening of the coexistence region of the insulator and metal phases, and an increase in the critical temperature at which the coexistence region disappears

  17. Two strongly correlated electron systems: the Kondo mode in the strong coupling limit and a 2-D model of electrons close to an electronic topological transition; Deux systemes d'electrons fortement correles: le modele de reseau Kondo dans la limite du couplage fort et un modele bidimensionnel d'electrons au voisinage d'une transition topologique electronique

    Energy Technology Data Exchange (ETDEWEB)

    Bouis, F

    1999-10-14

    Two strongly correlated electron systems are considered in this work, Kondo insulators and high Tc cuprates. Experiments and theory suggest on one hand that the Kondo screening occurs on a rather short length scale and on the other hand that the Kondo coupling is renormalized to infinity in the low energy limit. The strong coupling limit is then the logical approach although the real coupling is moderate. A systematic development is performed around this limit in the first part. The band structure of these materials is reproduced within this scheme. Magnetic fluctuations are also studied. The antiferromagnetic transition is examined in the case where fermionic excitations are shifted to high energy. In the second part, the Popov and Fedotov representation of spins is used to formulate the Kondo and the antiferromagnetic Heisenberg model in terms of a non-polynomial action of boson fields. In the third part the properties of high Tc cuprates are explained by a change of topology of the Fermi surface. This phenomenon would happen near the point of optimal doping and zero temperature. It results in the appearance of a density wave phase in the under-doped regime. The possibility that this phase has a non-conventional symmetry is considered. The phase diagram that described the interaction and coexistence of density wave and superconductivity is established in the mean-field approximation. The similarities with the experimental observations are numerous in particular those concerning the pseudo-gap and the behavior of the resistivity near optimal doping. (author)

  18. Quantum physics of light and matter photons, atoms, and strongly correlated systems

    CERN Document Server

    Salasnich, Luca

    2017-01-01

    This compact but exhaustive textbook, now in its significantly revised and expanded second edition, provides an essential introduction to the field quantization of light and matter with applications to atomic physics and strongly correlated systems. Following an initial review of the origins of special relativity and quantum mechanics, individual chapters are devoted to the second quantization of the electromagnetic field and the consequences of light field quantization for the description of electromagnetic transitions. The spin of the electron is then analyzed, with particular attention to its derivation from the Dirac equation. Subsequent topics include the effects of external electric and magnetic fields on the atomic spectra and the properties of systems composed of many interacting identical particles. The book also provides a detailed explanation of the second quantization of the non-relativistic matter field, i.e., the Schrödinger field, which offers a powerful tool for the investigation of many-body...

  19. Multiconfiguration Pair-Density Functional Theory: A New Way To Treat Strongly Correlated Systems.

    Science.gov (United States)

    Gagliardi, Laura; Truhlar, Donald G; Li Manni, Giovanni; Carlson, Rebecca K; Hoyer, Chad E; Bao, Junwei Lucas

    2017-01-17

    The electronic energy of a system provides the Born-Oppenheimer potential energy for internuclear motion and thus determines molecular structure and spectra, bond energies, conformational energies, reaction barrier heights, and vibrational frequencies. The development of more efficient and more accurate ways to calculate the electronic energy of systems with inherently multiconfigurational electronic structure is essential for many applications, including transition metal and actinide chemistry, systems with partially broken bonds, many transition states, and most electronically excited states. Inherently multiconfigurational systems are called strongly correlated systems or multireference systems, where the latter name refers to the need for using more than one ("multiple") configuration state function to provide a good zero-order reference wave function. This Account describes multiconfiguration pair-density functional theory (MC-PDFT), which was developed as a way to combine the advantages of wave function theory (WFT) and density functional theory (DFT) to provide a better treatment of strongly correlated systems. First we review background material: the widely used Kohn-Sham DFT (which uses only a single Slater determinant as reference wave function), multiconfiguration WFT methods that treat inherently multiconfigurational systems based on an active space, and previous attempts to combine multiconfiguration WFT with DFT. Then we review the formulation of MC-PDFT. It is a generalization of Kohn-Sham DFT in that the electron kinetic energy and classical electrostatic energy are calculated from a reference wave function, while the rest of the energy is obtained from a density functional. However, there are two main differences with respent to Kohn-Sham DFT: (i) The reference wave function is multiconfigurational rather than being a single Slater determinant. (ii) The density functional is a function of the total density and the on-top pair density rather than

  20. Atomic physics of strongly correlated systems: Progress report, 1 February 1988--15 January 1989

    International Nuclear Information System (INIS)

    Lin Chii-Dong.

    1989-01-01

    This report presents the progress made in our continuing study of strongly correlated atomic systems for the last contract period. In the area of hyperspherical coordinates for Coulombic three-body systems of arbitrary masses a general computing code has been developed. Calculation of the adiabatic potential curves have been accomplished for the e/sup /minus//e + e/sup /minus// system of arbitrary L, S and parity π. It was found that these curves behave very similar to the potential curves of H/sup /minus// except for a mass scaling. We have also examined the mass dependence of the ground state potential curves for systems of three charged particles, AAB, and showed that the curves become more attractive as the mass m/sub A/ becomes larger than m/sub B/. For ion-atom collisions we have examined the transfer-excitation (TE) processes to establish the importance of electron correlations in these two-electron transitions. We have also examined the orientation parameters for excited states formed in collisions with positive and negative charged particles to establish the relation between the sign of the charge of the incident particles to the sign of

  1. Ensemble DFT Approach to Excited States of Strongly Correlated Molecular Systems.

    Science.gov (United States)

    Filatov, Michael

    2016-01-01

    Ensemble density functional theory (DFT) is a novel time-independent formalism for obtaining excitation energies of many-body fermionic systems. A considerable advantage of ensemble DFT over the more common Kohn-Sham (KS) DFT and time-dependent DFT formalisms is that it enables one to account for strong non-dynamic electron correlation in the ground and excited states of molecular systems in a transparent and accurate fashion. Despite its positive aspects, ensemble DFT has not so far found its way into the repertoire of methods of modern computational chemistry, probably because of the perceived lack of practically affordable implementations of the theory. The spin-restricted ensemble-referenced KS (REKS) method is perhaps the first computationally feasible implementation of the ideas behind ensemble DFT which enables one to describe accurately electronic transitions in a wide class of molecular systems, including strongly correlated molecules (biradicals, molecules undergoing bond breaking/formation), extended π-conjugated systems, donor-acceptor charge transfer adducts, etc.

  2. The Role of screening in the strongly correlated 2D systems

    CERN Document Server

    Hwang, E H

    2003-01-01

    We investigate recently observed experiments in the strongly correlated 2D systems (r sub s >> 1) (low-density 2D plasmons, metallic behaviour of 2D systems and frictional drag resistivity between two 2D hole layers). We compare them with our theoretical results calculated within a conventional Fermi liquid theory with RPA screening.

  3. Density functional theory and dynamical mean-field theory. A way to model strongly correlated systems

    International Nuclear Information System (INIS)

    Backes, Steffen

    2017-04-01

    -local fluctuations. It has been successfully used to study the whole range of weakly to strongly correlated lattice models, including the metal-insulator transition, since even in the relevant dimensions of d = 2 and d = 3 spatial fluctuations are often small. The extension of DMFT towards realistic system by the use of DFT has been termed LDA+DMFT and has since then allowed for a significant improvement of the understanding of strongly correlated materials. We dedicate this thesis to the LDA+DMFT method and the study of the recently discovered ironpnictide superconductors, which are known to show effects of strong electronic correlations. Thus, in many cases these materials cannot be adequately described by a pure DFT approach alone and provide and ideal case for an investigation of their electronic properties within LDA+DMFT. We will first review the DFT method and point out what kind of approximations have to be made in practical calculations and what deficits they entail. Then we will give an introduction into the Green's function formalism in the real and imaginary time representation and discuss the resulting consequences like analytic continuation to pave the way for the derivation of the DMFT equations. After that, we will discuss the combination of DFT and DMFT into the LDA+DMFT method and how to set up the effective lattice models for practical calculations. Then we will apply the LDA+DMFT method to the hole-doped iron-pnictide superconductor KFe 2 As 2 , which we find to be a rather strongly correlated material that can only be reasonably described when electronic correlations are treated on a proper level beyond the the standard DFT approach. Our results show that the LDA+DMFT method is able to significantly improve the agreement of the theoretical calculation with experimental observations. Then we expand our study towards the isovalent series of KFe 2 As 2 , RbFe 2 As 2 and CsFe 2 As 2 , which we propose to show even stronger effects of electronic correlations due

  4. Density functional theory and dynamical mean-field theory. A way to model strongly correlated systems

    Energy Technology Data Exchange (ETDEWEB)

    Backes, Steffen

    2017-04-15

    -local fluctuations. It has been successfully used to study the whole range of weakly to strongly correlated lattice models, including the metal-insulator transition, since even in the relevant dimensions of d = 2 and d = 3 spatial fluctuations are often small. The extension of DMFT towards realistic system by the use of DFT has been termed LDA+DMFT and has since then allowed for a significant improvement of the understanding of strongly correlated materials. We dedicate this thesis to the LDA+DMFT method and the study of the recently discovered ironpnictide superconductors, which are known to show effects of strong electronic correlations. Thus, in many cases these materials cannot be adequately described by a pure DFT approach alone and provide and ideal case for an investigation of their electronic properties within LDA+DMFT. We will first review the DFT method and point out what kind of approximations have to be made in practical calculations and what deficits they entail. Then we will give an introduction into the Green's function formalism in the real and imaginary time representation and discuss the resulting consequences like analytic continuation to pave the way for the derivation of the DMFT equations. After that, we will discuss the combination of DFT and DMFT into the LDA+DMFT method and how to set up the effective lattice models for practical calculations. Then we will apply the LDA+DMFT method to the hole-doped iron-pnictide superconductor KFe{sub 2}As{sub 2}, which we find to be a rather strongly correlated material that can only be reasonably described when electronic correlations are treated on a proper level beyond the the standard DFT approach. Our results show that the LDA+DMFT method is able to significantly improve the agreement of the theoretical calculation with experimental observations. Then we expand our study towards the isovalent series of KFe{sub 2}As{sub 2}, RbFe{sub 2}As{sub 2} and CsFe{sub 2}As{sub 2}, which we propose to show even stronger

  5. Electronic properties of Pu19Os simulating β-Pu: the strongly correlated Pu phase

    Science.gov (United States)

    Havela, L.; Mašková, S.; Kolorenč, J.; Colineau, E.; Griveau, J.-C.; Eloirdi, R.

    2018-02-01

    We established the basic electronic properties of ζ-Pu19Os, which is a close analogue to β-Pu, and its low-temperature variety, η-Pu19Os. Their magnetic susceptibility is 15% higher than for δ-Pu. A specific heat study of ζ-Pu19Os shows a soft lattice similar to δ-Pu, leading to a low Debye temperature Θ D  =  101 K. The linear electronic coefficient γ related to the quasiparticle density of states at the Fermi level points to a higher value, 55  ±  2 mJ (mol Pu K2)–1, compared to 40 mJ (mol K2)–1 for δ-Pu. The results confirm that β-Pu is probably the most strongly correlated Pu phase, as had been indicated by resistivity measurements. The volume and related Pu–Pu spacing is clearly not the primary tuning parameter for Pu metal, as the β-Pu density stands close to the ground-state α-phase and is much higher than that for δ-Pu. The η-Pu19Os phase has a record γ-value of 74  ±  2 mJ (mol Pu K2)–1. The enhancement is not reproduced by LDA+DMFT calculations in the fcc structure, which suggests that multiple diverse sites can be the key to the understanding of β-Pu.

  6. Electronic properties of Pu19Os simulating β-Pu: the strongly correlated Pu phase.

    Science.gov (United States)

    Havela, Ladislav; Maskova, Silvie; Kolorenc, Jindrich; Colineau, E; Griveau, Jean-Christophe; Eloirdi, Rachel

    2018-01-04

    We established basic electronic properties of ζ-Pu19Os, which is a close analogue to β-Pu, and its low-temperature variety, η-Pu19Os. Their magnetic susceptibility is by 15% higher than for δ-Pu. Specific heat study of ζ-Pu19Os shows a soft lattice similar to δ-Pu, leading to a low Debye temperature ΘD = 101 K. The linear electronic coefficient γ related to the quasiparticle density of states at the Fermi level points to a higher value, 55±2 mJ/mol Pu K2, compared to 40 mJ/mol K2 for δ-Pu. The results confirm that β-Pu is probably the most strongly correlated Pu phase, as had been indicated by resistivity measurements. The volume and related Pu-Pu spacing is clearly not the primary tuning parameter for Pu metal, as the β-Pu density stands close to the ground-state α-phase and is much higher than that for δ-Pu. The η-Pu19Os phase has a record γ-value of 74±2 mJ/mol Pu K2. The enhancement is not reproduced by LDA+DMFT calculations in the fcc structure, which suggests that the multiple diverse sites can be the key to the understanding of β-Pu. © 2018 IOP Publishing Ltd.

  7. Development of high-brightness ultrafast electron microscope for studying nanoscale dynamics associated with strongly correlated materials

    Science.gov (United States)

    Tao, Zhensheng

    Strongly correlated-electron materials are a class of materials that exhibit numerous intriguing emergent phenomena, including metal-to-insulator transition, colossal magnetoresistance, high-temperature superconductivity, etc. These phenomena are beyond the reach of the conventional solid state physics, which is based on the band theory. Instead, strong electron-electron correlations are found to play important roles, which leads to complicated interplay between different degrees of freedoms (charge, lattice, spins...). In this thesis, ultrafast electron diffraction (UED) is used to investigate the photo-induced ultrafast structural dynamics of strongly correlated materials, among which VO2 is taken as an exemplar system, one that reveals the fundamental physics behind photo-induced phase transitions, electron-electron correlation on nanometer scales, and the electron-phonon coupling in this exotic class of materials. The phenomena presented here are expected to have more general significance as they may reflect the physics to which other strongly correlated materials also conform. In polycrystalline VO2 thin films, the structural changes resulting from photoexcitation with femtosecond laser pulses with different wavelengths are observed to lead to non-thermal phase transitions, which require less energy compared to the phase transitions induced by thermal excitation. The details of the structural change are extracted from the UED results revealing stepwise atomic movements after photoexcitation, which suggests the phase transition starts with a dilation of the correlated d electrons. On the other hand, the structural phase transition is found to be decoupled from the metal-to-insulator transition when the sample dimension is reduced to the sub-micrometer scale, which is attributed to the interface charge doping effects from different substrates. A new phase (M3, monoclinic metallic phase) is distinguished, which has not been discussed by the existing theoretical

  8. The strong correlation of the 4f electrons of erbium in silicon

    CERN Document Server

    Fu Yu Rui; Wang Xun; Ye Lin

    2003-01-01

    The local spin density approximation (LSDA) with the Hubbard model correction is adopted to describe the electronic structures of O-codoped Er-Si systems. The electrons in the 4f orbitals of Er atoms are taken as localized electrons in the framework of an all-electron treatment. The total density of states (DOS) and the partial densities of states for Si(3s, 3p), Er(4f), Er(5d), Er(6s), O(2s), and O(2p) in this ErSiO system are calculated. It is found that the inclusion of the Hubbard U greatly influences the partial DOS of the Er 4f electrons. The separation between the spin-up and the spin-down states of the highly localized 4f orbitals is larger than that of the LSDA results obtained without considering the Hubbard U-parameter. The calculation results provide possible explanations of the experimentally observed erbium-induced impurity energy levels in Si detected by deep-level transient spectroscopy.

  9. Auxiliary-Field Quantum Monte Carlo Simulations of Strongly-Correlated Systems, the Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-11-07

    In this final report, we present preliminary results of ground state phases of interacting spinless Dirac fermions. The name "Dirac fermion" originates from the fact that low-energy excitations of electrons hopping on the honeycomb lattice are described by a relativistic Dirac equation. Dirac fermions have received much attention particularly after the seminal work of Haldale1 which shows that the quantum Hall physics can be realized on the honeycomb lattice without magnetic fields. Haldane's work later becomes the foundation of topological insulators (TIs). While the physics of TIs is based largely on spin-orbit coupled non-interacting electrons, it was conjectured that topological insulators can be induced by strong correlations alone.

  10. Microscopic origin of marginal Fermi-liquid in strongly correlated spin systems

    International Nuclear Information System (INIS)

    Protogenov, A.P.; Ryndyk, D.A.

    1992-08-01

    We consider the consequences of separation of spin and charge degrees of freedom in 2+1D strongly correlated spin systems. Self-consistent spin and charge motions induced by doping in sites of ground and dual lattices form such a spectrum of quasiparticles which together with the dispersionless character of the collective excitation spectrum and the chemical potential pinning in the band centre yield the necessary behavior of charge and spin polarizability to support the theory of marginal liquid formulated by C.M. Varma et al. (Phys. Rev. Lett. 63, 1996 (1989)). (author). 28 refs, 4 figs

  11. Entanglement-enhanced information transfer through strongly correlated systems and its application to optical lattices

    Energy Technology Data Exchange (ETDEWEB)

    Yang Song [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom); Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, 230026 (China); Bayat, Abolfazl; Bose, Sougato [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom)

    2011-08-15

    We show that the inherent entanglement of the ground state of strongly correlated systems can be exploited for both classical and quantum communications. Our strategy is based on a single-qubit rotation that encodes information in the entangled nature of the ground state. In classical communication, our mechanism conveys more than one bit of information in each shot, just as dense coding does, without demanding long-range entanglement. In our scheme for quantum communication, the quality is higher than the widely studied attaching scenarios. Moreover, we propose to implement this way of communication in optical lattices.

  12. Generalized-active-space pair-density functional theory: an efficient method to study large, strongly correlated, conjugated systems.

    Science.gov (United States)

    Ghosh, Soumen; Cramer, Christopher J; Truhlar, Donald G; Gagliardi, Laura

    2017-04-01

    Predicting ground- and excited-state properties of open-shell organic molecules by electronic structure theory can be challenging because an accurate treatment has to correctly describe both static and dynamic electron correlation. Strongly correlated systems, i.e. , systems with near-degeneracy correlation effects, are particularly troublesome. Multiconfigurational wave function methods based on an active space are adequate in principle, but it is impractical to capture most of the dynamic correlation in these methods for systems characterized by many active electrons. We recently developed a new method called multiconfiguration pair-density functional theory (MC-PDFT), that combines the advantages of wave function theory and density functional theory to provide a more practical treatment of strongly correlated systems. Here we present calculations of the singlet-triplet gaps in oligoacenes ranging from naphthalene to dodecacene. Calculations were performed for unprecedently large orbitally optimized active spaces of 50 electrons in 50 orbitals, and we test a range of active spaces and active space partitions, including four kinds of frontier orbital partitions. We show that MC-PDFT can predict the singlet-triplet splittings for oligoacenes consistent with the best available and much more expensive methods, and indeed MC-PDFT may constitute the benchmark against which those other models should be compared, given the absence of experimental data.

  13. Analysis of electron-correlation effects in strongly correlated systems (N2 and N2+ ) by applying the density-matrix renormalization-group method and quantum information theory

    Science.gov (United States)

    Stemmle, Christian; Paulus, Beate; Legeza, Örs

    2018-02-01

    The dissociation of N2 and N2 + has been studied by using the ab initio density-matrix renormalization-group (DMRG) method. Accurate potential energy surfaces (PESs) have been obtained for the electronic ground states of N2 (X1 Σg+ ) and N2+ (X2 Σg+ ) as well as for the N2+ excited state B2 Σu+ . Inherent to the DMRG approach, the eigenvalues of the reduced density matrix (ρ ) and their correlation functions are at hand. Thus we can apply quantum information theory directly and investigate how the wave function changes along the PES and depict differences between the different states. Moreover, by characterizing quantum entanglement between different pairs of orbitals and analyzing the reduced density matrix, we achieved a better understanding of the multireference character featured by these systems.

  14. The ALPS project release 2.0: open source software for strongly correlated systems

    International Nuclear Information System (INIS)

    Bauer, B; Gamper, L; Gukelberger, J; Hehn, A; Isakov, S V; Ma, P N; Mates, P; Carr, L D; Evertz, H G; Feiguin, A; Freire, J; Koop, D; Fuchs, S; Gull, E; Guertler, S; Igarashi, R; Matsuo, H; Parcollet, O; Pawłowski, G; Picon, J D

    2011-01-01

    We present release 2.0 of the ALPS (Algorithms and Libraries for Physics Simulations) project, an open source software project to develop libraries and application programs for the simulation of strongly correlated quantum lattice models such as quantum magnets, lattice bosons, and strongly correlated fermion systems. The code development is centered on common XML and HDF5 data formats, libraries to simplify and speed up code development, common evaluation and plotting tools, and simulation programs. The programs enable non-experts to start carrying out serial or parallel numerical simulations by providing basic implementations of the important algorithms for quantum lattice models: classical and quantum Monte Carlo (QMC) using non-local updates, extended ensemble simulations, exact and full diagonalization (ED), the density matrix renormalization group (DMRG) both in a static version and a dynamic time-evolving block decimation (TEBD) code, and quantum Monte Carlo solvers for dynamical mean field theory (DMFT). The ALPS libraries provide a powerful framework for programmers to develop their own applications, which, for instance, greatly simplify the steps of porting a serial code onto a parallel, distributed memory machine. Major changes in release 2.0 include the use of HDF5 for binary data, evaluation tools in Python, support for the Windows operating system, the use of CMake as build system and binary installation packages for Mac OS X and Windows, and integration with the VisTrails workflow provenance tool. The software is available from our web server at http://alps.comp-phys.org/

  15. Hard X-ray PhotoEmission Spectroscopy of strongly correlated systems

    Science.gov (United States)

    Panaccione, Giancarlo; Offi, Francesco; Sacchi, Maurizio; Torelli, Piero

    2008-06-01

    Hard X-ray PhotoEmission Spectroscopy (HAXPES) is a new tool for the study of bulk electronic properties of solids using synchrotron radiation. We review recent achievements of HAXPES, with particular reference to the VOLPE project, showing that high energy resolution and bulk sensitivity can be obtained at kinetic energies of 6-8 keV. We present also the results of recent studies on strongly correlated materials, such as vanadium sesquioxide and bilayered manganites, revealing the presence of different screening properties in the bulk with respect to the surface. We discuss the relevant experimental features of the metal-insulator transition in these materials. To cite this article: G. Panaccione et al., C. R. Physique 9 (2008).

  16. Strongly correlated photons generated by coupling a three- or four-level system to a waveguide

    Science.gov (United States)

    Zheng, Huaixiu; Gauthier, Daniel J.; Baranger, Harold U.

    2012-04-01

    We study the generation of strongly correlated photons by coupling an atom to photonic quantum fields in a one-dimensional waveguide. Specifically, we consider a three-level or four-level system for the atom. Photon-photon bound states emerge as a manifestation of the strong photon-photon correlation mediated by the atom. Effective repulsive or attractive interaction between photons can be produced, causing either suppressed multiphoton transmission (photon blockade) or enhanced multiphoton transmission (photon-induced tunneling). As a result, nonclassical light sources can be generated on demand by sending coherent states into the proposed system. We calculate the second-order correlation function of the transmitted field and observe bunching and antibunching caused by the bound states. Furthermore, we demonstrate that the proposed system can produce photon pairs with a high degree of spectral entanglement, which have a large capacity for carrying information and are important for large-alphabet quantum communication.

  17. Strongly correlated Fermi-systems: Non-Fermi liquid behavior, quasiparticle effective mass and their interplay

    Energy Technology Data Exchange (ETDEWEB)

    Shaginyan, V.R. [Petersburg Nuclear Physics Institute, RAS, Gatchina 188300 (Russian Federation); Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)], E-mail: vrshag@thd.pnpi.spb.ru; Amusia, M.Ya. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Popov, K.G. [Komi Science Center, Ural Division, RAS, Syktyvkar 167982 (Russian Federation)

    2009-06-15

    Basing on the density functional theory of fermion condensation, we analyze the non-Fermi liquid behavior of strongly correlated Fermi-systems such as heavy-fermion metals. When deriving equations for the effective mass of quasiparticles, we consider solids with a lattice and homogeneous systems. We show that the low-temperature thermodynamic and transport properties are formed by quasiparticles, while the dependence of the effective mass on temperature, number density, magnetic fields, etc., gives rise to the non-Fermi liquid behavior. Our theoretical study of the heat capacity, magnetization, energy scales, the longitudinal magnetoresistance and magnetic entropy are in good agreement with the remarkable recent facts collected on the heavy-fermion metal YbRh{sub 2}Si{sub 2}.

  18. Strongly correlated Fermi-systems: Non-Fermi liquid behavior, quasiparticle effective mass and their interplay

    International Nuclear Information System (INIS)

    Shaginyan, V.R.; Amusia, M.Ya.; Popov, K.G.

    2009-01-01

    Basing on the density functional theory of fermion condensation, we analyze the non-Fermi liquid behavior of strongly correlated Fermi-systems such as heavy-fermion metals. When deriving equations for the effective mass of quasiparticles, we consider solids with a lattice and homogeneous systems. We show that the low-temperature thermodynamic and transport properties are formed by quasiparticles, while the dependence of the effective mass on temperature, number density, magnetic fields, etc., gives rise to the non-Fermi liquid behavior. Our theoretical study of the heat capacity, magnetization, energy scales, the longitudinal magnetoresistance and magnetic entropy are in good agreement with the remarkable recent facts collected on the heavy-fermion metal YbRh 2 Si 2 .

  19. Dynamical mean-field theory and path integral renormalisation group calculations of strongly correlated electronic states

    International Nuclear Information System (INIS)

    Heilmann, D.B.

    2007-02-01

    The two-plane HUBBARD model, which is a model for some electronic properties of undoped YBCO superconductors as well as displays a MOTT metal-to-insulator transition and a metal-to-band insulator transition, is studied within Dynamical Mean-Field Theory using HIRSCH-FYE Monte Carlo. In order to find the different transitions and distinguish the types of insulator, we calculate the single-particle spectral densities, the self-energies and the optical conductivities. We conclude that there is a continuous transition from MOTT to band insulator. In the second part, ground state properties of a diagonally disordered HUBBARD model is studied using a generalisation of Path Integral Renormalisation Group, a variational method which can also determine low-lying excitations. In particular, the distribution of antiferromagnetic properties is investigated. We conclude that antiferromagnetism breaks down in a percolation-type transition at a critical disorder, which is not changed appreciably by the inclusion of correlation effects, when compared to earlier studies. Electronic and excitation properties at the system sizes considered turn out to primarily depend on the geometry. (orig.)

  20. Dynamical mean-field theory and path integral renormalisation group calculations of strongly correlated electronic states

    Energy Technology Data Exchange (ETDEWEB)

    Heilmann, D.B.

    2007-02-15

    The two-plane HUBBARD model, which is a model for some electronic properties of undoped YBCO superconductors as well as displays a MOTT metal-to-insulator transition and a metal-to-band insulator transition, is studied within Dynamical Mean-Field Theory using HIRSCH-FYE Monte Carlo. In order to find the different transitions and distinguish the types of insulator, we calculate the single-particle spectral densities, the self-energies and the optical conductivities. We conclude that there is a continuous transition from MOTT to band insulator. In the second part, ground state properties of a diagonally disordered HUBBARD model is studied using a generalisation of Path Integral Renormalisation Group, a variational method which can also determine low-lying excitations. In particular, the distribution of antiferromagnetic properties is investigated. We conclude that antiferromagnetism breaks down in a percolation-type transition at a critical disorder, which is not changed appreciably by the inclusion of correlation effects, when compared to earlier studies. Electronic and excitation properties at the system sizes considered turn out to primarily depend on the geometry. (orig.)

  1. The thermodynamic spin magnetization of strongly correlated 2d electrons in a silicon inversion layer

    OpenAIRE

    Prus, O.; Yaish, Y.; Reznikov, M.; Sivan, U.; Pudalov, V.

    2002-01-01

    A novel method invented to measure the minute thermodynamic spin magnetization of dilute two dimensional fermions is applied to electrons in a silicon inversion layer. Interplay between the ferromagnetic interaction and disorder enhances the low temperature susceptibility up to 7.5 folds compared with the Pauli susceptibility of non-interacting electrons. The magnetization peaks in the vicinity of the density where transition to strong localization takes place. At the same density, the suscep...

  2. Perturbation theory of strongly correlated electrons with and without slave boson technique

    International Nuclear Information System (INIS)

    Nguyen Van Hieu; Ha Vinh Tan; Nguyen Toan Thang; Nguyen Ai Viet.

    1988-10-01

    The Green functions of the electrons in the two-band Hubbard model with the strong on-site Coulomb repulsion were calculated by means of the perturbation theory with respect to the hopping term of the Hamiltonian. It was shown that in the slave boson technique we obtain the expressions different from the results of the calculations involving directly electron operators without using slave bosons. The physical meaning of this discrepancy was discussed. (author)

  3. Concepts relating magnetic interactions, intertwined electronic orders, and strongly correlated superconductivity

    Science.gov (United States)

    Davis, J. C. Séamus; Lee, Dung-Hai

    2013-01-01

    Unconventional superconductivity (SC) is said to occur when Cooper pair formation is dominated by repulsive electron–electron interactions, so that the symmetry of the pair wave function is other than an isotropic s-wave. The strong, on-site, repulsive electron–electron interactions that are the proximate cause of such SC are more typically drivers of commensurate magnetism. Indeed, it is the suppression of commensurate antiferromagnetism (AF) that usually allows this type of unconventional superconductivity to emerge. Importantly, however, intervening between these AF and SC phases, intertwined electronic ordered phases (IP) of an unexpected nature are frequently discovered. For this reason, it has been extremely difficult to distinguish the microscopic essence of the correlated superconductivity from the often spectacular phenomenology of the IPs. Here we introduce a model conceptual framework within which to understand the relationship between AF electron–electron interactions, IPs, and correlated SC. We demonstrate its effectiveness in simultaneously explaining the consequences of AF interactions for the copper-based, iron-based, and heavy-fermion superconductors, as well as for their quite distinct IPs. PMID:24114268

  4. Strain-Induced Enhancement of the Electron Energy Relaxation in Strongly Correlated Superconductors

    Directory of Open Access Journals (Sweden)

    C. Gadermaier

    2014-03-01

    Full Text Available We use femtosecond optical spectroscopy to systematically measure the primary energy relaxation rate Γ_{1} of photoexcited carriers in cuprate and pnictide superconductors. We find that Γ_{1} increases monotonically with increased negative strain in the crystallographic a axis. Generally, the Bardeen-Shockley deformation potential theorem and, specifically, pressure-induced Raman shifts reported in the literature suggest that increased negative strain enhances electron-phonon coupling, which implies that the observed direct correspondence between a and Γ_{1} is consistent with the canonical assignment of Γ_{1} to the electron-phonon interaction. The well-known nonmonotonic dependence of the superconducting critical temperature T_{c} on the a-axis strain is also reflected in a systematic dependence T_{c} on Γ_{1}, with a distinct maximum at intermediate values (∼16  ps^{−1} at room temperature. The empirical nonmonotonic systematic variation of T_{c} with the strength of the electron-phonon interaction provides us with unique insight into the role of electron-phonon interaction in relation to the mechanism of high-T_{c} superconductivity as a crossover phenomenon.

  5. Superconductivity, Antiferromagnetism, and Kinetic Correlation in Strongly Correlated Electron Systems

    Directory of Open Access Journals (Sweden)

    Takashi Yanagisawa

    2015-01-01

    Full Text Available We investigate the ground state of two-dimensional Hubbard model on the basis of the variational Monte Carlo method. We use wave functions that include kinetic correlation and doublon-holon correlation beyond the Gutzwiller ansatz. It is still not clear whether the Hubbard model accounts for high-temperature superconductivity. The antiferromagnetic correlation plays a key role in the study of pairing mechanism because the superconductive phase exists usually close to the antiferromagnetic phase. We investigate the stability of the antiferromagnetic state when holes are doped as a function of the Coulomb repulsion U. We show that the antiferromagnetic correlation is suppressed as U is increased exceeding the bandwidth. High-temperature superconductivity is possible in this region with enhanced antiferromagnetic spin fluctuation and pairing interaction.

  6. Time-resolved THz studies of carrier dynamics in semiconductors, superconductors, and strongly-correlated electron materials

    Energy Technology Data Exchange (ETDEWEB)

    Kaindl, Robert A.; Averitt, Richard D.

    2006-11-14

    Perhaps the most important aspect of contemporary condensed matter physics involves understanding strong Coulomb interactions between the large number of electrons in a solid. Electronic correlations lead to the emergence of new system properties, such as metal-insulator transitions, superconductivity, magneto-resistance, Bose-Einstein condensation, the formation of excitonic gases, or the integer and fractional Quantum Hall effects. The discovery of high-Tc superconductivity in particular was a watershed event, leading to dramatic experimental and theoretical advances in the field of correlated-electron systems. Such materials often exhibit competition between the charge, lattice, spin, and orbital degrees of freedom, whose cause-effect relationships are difficult to ascertain. Experimental insight into the properties of solids is traditionally obtained by time-averaged probes, which measure e.g., linear optical spectra, electrical conduction properties, or the occupied band structure in thermal equilibrium. Many novel physical properties arise from excitations out of the ground state into energetically higher states by thermal, optical, or electrical means. This leads to fundamental interactions between the system's constituents, such as electron-phonon and electron-electron interactions, which occur on ultrafast timescales. While these interactions underlie the physical properties of solids, they are often only indirectly inferred from time-averaged measurements. Time-resolved spectroscopy, consequently, is playing an ever increasing role to provide insight into light-matter interaction, microscopic processes, or cause-effect relationships that determine the physics of complex materials. In the past, experiments using visible and near-infrared femtosecond pulses have been extensively employed, e.g. to follow relaxation and dephasing processes in metals and semiconductors. However, many basic excitations in strongly-correlated electron systems and nanoscale

  7. Deterministic alternatives to the full configuration interaction quantum Monte Carlo method for strongly correlated systems

    Science.gov (United States)

    Tubman, Norm; Whaley, Birgitta

    The development of exponential scaling methods has seen great progress in tackling larger systems than previously thought possible. One such technique, full configuration interaction quantum Monte Carlo, allows exact diagonalization through stochastically sampling of determinants. The method derives its utility from the information in the matrix elements of the Hamiltonian, together with a stochastic projected wave function, which are used to explore the important parts of Hilbert space. However, a stochastic representation of the wave function is not required to search Hilbert space efficiently and new deterministic approaches have recently been shown to efficiently find the important parts of determinant space. We shall discuss the technique of Adaptive Sampling Configuration Interaction (ASCI) and the related heat-bath Configuration Interaction approach for ground state and excited state simulations. We will present several applications for strongly correlated Hamiltonians. This work was supported through the Scientific Discovery through Advanced Computing (SciDAC) program funded by the U.S. Department of Energy, Office of Science, Advanced Scientific Computing Research and Basic Energy Sciences.

  8. Ferromagnetic instabilities in disordered systems in the limit of strong correlations

    International Nuclear Information System (INIS)

    Magalhaes, A.N.; Troper, A.; Gomes, A.A.

    1976-05-01

    One derives the criterion for ferromagnetic instabilities in hybridized disordered systems, e.g. transition metal like systems and actinides, within the Coherent Potential Approximation (CPA), the electron-electron correlations being described by Hubbard' approximation. In the case of actinides, one treats approximately the motion of d electrons while the diagonal disorder within the f band is fully taken into account. In the case of a trnsition metal like system, except for Hubbard's approximation in dealing with d-d electron correlations, our procedure is exact within the spirit of CPA

  9. Assessing the importance of frustration in a narrow-band strongly correlated electronic chain

    International Nuclear Information System (INIS)

    Lal, Siddhartha; Laad, Mukul S.

    2007-08-01

    We study a one-dimensional extended Hubbard model with longer-range Coulomb interactions at quarter-filling in the strong coupling limit. In this limit, we find the one dimensional transverse field Ising model (TFIM) to be the effective Hamiltonian governing the dynamics of the charge degrees of freedom. We find two different charge-ordered (CO) ground states as the strength of the longer range interactions is varied. At lower energies, these CO states drive two different spin-ordered ground states. A variety of response functions computed here bear a remarkable resemblance to recent experimental observations for organic TMTSF systems, and so we propose that these systems are proximate to a QCP associated with T = 0 charge order. (author)

  10. Communication: An adaptive configuration interaction approach for strongly correlated electrons with tunable accuracy

    Energy Technology Data Exchange (ETDEWEB)

    Schriber, Jeffrey B.; Evangelista, Francesco A. [Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322 (United States)

    2016-04-28

    We introduce a new procedure for iterative selection of determinant spaces capable of describing highly correlated systems. This adaptive configuration interaction (ACI) determines an optimal basis by an iterative procedure in which the determinant space is expanded and coarse grained until self-consistency. Two importance criteria control the selection process and tune the ACI to a user-defined level of accuracy. The ACI is shown to yield potential energy curves of N{sub 2} with nearly constant errors, and it predicts singlet-triplet splittings of acenes up to decacene that are in good agreement with the density matrix renormalization group.

  11. Matrix-product states for strongly correlated systems and quantum information processing

    Energy Technology Data Exchange (ETDEWEB)

    Saberi, Hamed

    2008-12-12

    This thesis offers new developments in matrix-product state theory for studying the strongly correlated systems and quantum information processing through three major projects: In the first project, we perform a systematic comparison between Wilson's numerical renormalization group (NRG) and White's density-matrix renormalization group (DMRG). The NRG method for solving quantum impurity models yields a set of energy eigenstates that have the form of matrix-product states (MPS). White's DMRG for treating quantum lattice problems can likewise be reformulated in terms of MPS. Thus, the latter constitute a common algebraic structure for both approaches. We exploit this fact to compare the NRG approach for the single-impurity Anderson model to a variational matrix-product state approach (VMPS), equivalent to single-site DMRG. For the latter, we use an ''unfolded'' Wilson chain, which brings about a significant reduction in numerical costs compared to those of NRG. We show that all NRG eigenstates (kept and discarded) can be reproduced using VMPS, and compare the difference in truncation criteria, sharp vs. smooth in energy space, of the two approaches. Finally, we demonstrate that NRG results can be improved upon systematically by performing a variational optimization in the space of variational matrix-product states, using the states produced by NRG as input. In the second project we demonstrate how the matrix-product state formalism provides a flexible structure to solve the constrained optimization problem associated with the sequential generation of entangled multiqubit states under experimental restrictions. We consider a realistic scenario in which an ancillary system with a limited number of levels performs restricted sequential interactions with qubits in a row. The proposed method relies on a suitable local optimization procedure, yielding an efficient recipe for the realistic and approximate sequential generation of any

  12. Matrix-product states for strongly correlated systems and quantum information processing

    International Nuclear Information System (INIS)

    Saberi, Hamed

    2008-01-01

    This thesis offers new developments in matrix-product state theory for studying the strongly correlated systems and quantum information processing through three major projects: In the first project, we perform a systematic comparison between Wilson's numerical renormalization group (NRG) and White's density-matrix renormalization group (DMRG). The NRG method for solving quantum impurity models yields a set of energy eigenstates that have the form of matrix-product states (MPS). White's DMRG for treating quantum lattice problems can likewise be reformulated in terms of MPS. Thus, the latter constitute a common algebraic structure for both approaches. We exploit this fact to compare the NRG approach for the single-impurity Anderson model to a variational matrix-product state approach (VMPS), equivalent to single-site DMRG. For the latter, we use an ''unfolded'' Wilson chain, which brings about a significant reduction in numerical costs compared to those of NRG. We show that all NRG eigenstates (kept and discarded) can be reproduced using VMPS, and compare the difference in truncation criteria, sharp vs. smooth in energy space, of the two approaches. Finally, we demonstrate that NRG results can be improved upon systematically by performing a variational optimization in the space of variational matrix-product states, using the states produced by NRG as input. In the second project we demonstrate how the matrix-product state formalism provides a flexible structure to solve the constrained optimization problem associated with the sequential generation of entangled multiqubit states under experimental restrictions. We consider a realistic scenario in which an ancillary system with a limited number of levels performs restricted sequential interactions with qubits in a row. The proposed method relies on a suitable local optimization procedure, yielding an efficient recipe for the realistic and approximate sequential generation of any entangled multiqubit state. We give

  13. Competing orders in strongly correlated systems. Dirac materials and iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Classen, Laura

    2016-11-04

    In this work we address the collective phenomena appearing in interacting fermion systems due to the competition of distinct orders at the example of Dirac materials and iron-based superconductors. On the one hand we determine leading ordering tendencies in an unbiased way, when Fermi liquid instabilities are expected simultaneously in the particle-particle and particle-hole channel. In this context we analyze the impact of electron-phonon interactions on the many-body instabilities of electrons on the honeycomb lattice. Furthermore we investigate the interplay between superconductivity, magnetism and orbital order in five-pocket iron-based superconductors including the full orbital composition of low-energy excitations. On the other hand we study how the close proximity of different phases affects the structure of the phase diagram and the nature of transitions, as well as the corresponding quantum multicritical behavior. To this end we consider the semimetal-insulator transitions to an antiferromagnetic and a staggered-density state of low-energy Dirac fermions. To account for the decisive role of interactions and the various degrees of freedom in these models, modern renormalization group techniques are applied.

  14. Strong correlation in acene sheets from the active-space variational two-electron reduced density matrix method: effects of symmetry and size.

    Science.gov (United States)

    Pelzer, Kenley; Greenman, Loren; Gidofalvi, Gergely; Mazziotti, David A

    2011-06-09

    Polyaromatic hydrocarbons (PAHs) are a class of organic molecules with importance in several branches of science, including medicine, combustion chemistry, and materials science. The delocalized π-orbital systems in PAHs require highly accurate electronic structure methods to capture strong electron correlation. Treating correlation in PAHs has been challenging because (i) traditional wave function methods for strong correlation have not been applicable since they scale exponentially in the number of strongly correlated orbitals, and (ii) alternative methods such as the density-matrix renormalization group and variational two-electron reduced density matrix (2-RDM) methods have not been applied beyond linear acene chains. In this paper we extend the earlier results from active-space variational 2-RDM theory [Gidofalvi, G.; Mazziotti, D. A. J. Chem. Phys. 2008, 129, 134108] to the more general two-dimensional arrangement of rings--acene sheets--to study the relationship between geometry and electron correlation in PAHs. The acene-sheet calculations, if performed with conventional wave function methods, would require wave function expansions with as many as 1.5 × 10(17) configuration state functions. To measure electron correlation, we employ several RDM-based metrics: (i) natural-orbital occupation numbers, (ii) the 1-RDM von Neumann entropy, (iii) the correlation energy per carbon atom, and (iv) the squared Frobenius norm of the cumulant 2-RDM. The results confirm a trend of increasing polyradical character with increasing molecular size previously observed in linear PAHs and reveal a corresponding trend in two-dimensional (arch-shaped) PAHs. Furthermore, in PAHs of similar size they show significant variations in correlation with geometry. PAHs with the strictly linear geometry (chains) exhibit more electron correlation than PAHs with nonlinear geometries (sheets).

  15. Single particle Green's functions calculation of the electrical conductivity of strong correlated systems

    International Nuclear Information System (INIS)

    Rodrigues Junior, W.A.

    A calculation of the electrical conductivity for Hubbard materials is presented which is valid when U/t >> 1 (U being the Coulomb repulsion and t the nearest neighbor hopping energy) for arbitrary electron concentration and temperature. The derivation emploies the single particle Green's functions with real and imaginary times instead of the usual two-particle real time Green's function. The result is compared with the experimental data available for some organic charge transfer salts [pt

  16. Quantum glassiness in clean strongly correlated systems: an example of topological overprotection

    Science.gov (United States)

    Chamon, Claudio

    2005-03-01

    Describing matter at near absolute zero temperature requires understanding a system's quantum ground state and the low energy excitations around it, the quasiparticles, which are thermally populated by the system's contact to a heat bath. However, this paradigm breaks down if thermal equilibration is obstructed. I present solvable examples of quantum many-body Hamiltonians of systems that are unable to reach their ground states as the environment temperature is lowered to absolute zero. These examples, three dimensional generalizations of quantum Hamiltonians proposed for topological quantum computing, 1) have no quenched disorder, 2) have solely local interactions, 3) have an exactly solvable spectrum, 4) have topologically ordered ground states, and 5) have slow dynamical relaxation rates akin to those of strong structural glasses.

  17. Impurity self-energy in the strongly-correlated Bose systems

    Science.gov (United States)

    Panochko, Galyna; Pastukhov, Volodymyr; Vakarchuk, Ivan

    2018-02-01

    We proposed the nonperturbative scheme for the calculation of the impurity spectrum in the Bose system at zero temperature. The method is based on the path-integral formulation and describes an impurity as a zero-density ideal Fermi gas interacting with Bose system for which the action is written in terms of density fluctuations. On the example of the 3He atom immersed in the liquid helium-4 a good consistency with experimental data and results of Monte Carlo simulations is shown.

  18. Theory of heavy-fermion compounds theory of strongly correlated Fermi-systems

    CERN Document Server

    Amusia, Miron Ya; Shaginyan, Vasily R; Stephanovich, Vladimir A

    2015-01-01

    This book explains modern and interesting physics in heavy-fermion (HF) compounds to graduate students and researchers in condensed matter physics. It presents a theory of heavy-fermion (HF) compounds such as HF metals, quantum spin liquids, quasicrystals and two-dimensional Fermi systems. The basic low-temperature properties and the scaling behavior of the compounds are described within the framework of the theory of fermion condensation quantum phase transition (FCQPT). Upon reading the book, the reader finds that HF compounds with quite different microscopic nature exhibit the same non-Fermi liquid behavior, while the data collected on very different HF systems have a universal scaling behavior, and these compounds are unexpectedly uniform despite their diversity. For the reader's convenience, the analysis of compounds is carried out in the context of salient experimental results. The numerous calculations of the non-Fermi liquid behavior, thermodynamic, relaxation and transport properties, being in good...

  19. Quantum Glassiness in Strongly Correlated Clean Systems: An Example of Topological Overprotection

    Science.gov (United States)

    Chamon, Claudio

    2005-01-01

    This Letter presents solvable examples of quantum many-body Hamiltonians of systems that are unable to reach their ground states as the environment temperature is lowered to absolute zero. These examples, three-dimensional generalizations of quantum Hamiltonians proposed for topological quantum computing, (1)have no quenched disorder, (2)have solely local interactions, (3)have an exactly solvable spectrum, (4)have topologically ordered ground states, and (5)have slow dynamical relaxation rates akin to those of strong structural glasses.

  20. Strongly correlated electrons at high pressure: an approach by inelastic X-Ray scattering; Electrons correles sous haute pression: une approche par diffusion inelastique des rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Rueff, J.P

    2007-06-15

    Inelastic X-ray scattering (IXS) and associated methods has turn out to be a powerful alternative for high-pressure physics. It is an all-photon technique fully compatible with high-pressure environments and applicable to a vast range of materials. Standard focalization of X-ray in the range of 100 microns is typical of the sample size in the pressure cell. Our main aim is to provide an overview of experimental results obtained by IXS under high pressure in 2 classes of materials which have been at the origin of the renewal of condensed matter physics: strongly correlated transition metal oxides and rare-earth compounds. Under pressure, d and f-electron materials show behaviors far more complex that what would be expected from a simplistic band picture of electron delocalization. These spectroscopic studies have revealed unusual phenomena in the electronic degrees of freedom, brought up by the increased density, the changes in the charge-carrier concentration, the over-lapping between orbitals, and hybridization under high pressure conditions. Particularly we discuss about pressure induced magnetic collapse and metal-insulator transitions in 3d compounds and valence fluctuations phenomena in 4f and 5f compounds. Thanks to its superior penetration depth, chemical selectivity and resonant enhancement, resonant inelastic X-ray scattering has appeared extremely well suited to high pressure physics in strongly correlated materials. (A.C.)

  1. Strongly Correlated Topological Insulators

    Science.gov (United States)

    2016-02-03

    Strongly Correlated Topological Insulators In the past year, the grant was used for work in the field of topological phases, with emphasis on finding...surface of topological insulators. In the past 3 years, we have started a new direction, that of fractional topological insulators. These are materials...in which a topologically nontrivial quasi-flat band is fractionally filled and then subject to strong interactions. The views, opinions and/or

  2. Transport phenomena in strongly correlated Fermi liquids

    Energy Technology Data Exchange (ETDEWEB)

    Kontani, Hiroshi [Nagoya Univ., Aichi (Japan). Dept. of Physics

    2013-03-01

    Comprehensive overview. Written by an expert of this topic. Provides the reader with current developments in the field. In conventional metals, various transport coefficients are scaled according to the quasiparticle relaxation time, {tau}, which implies that the relaxation time approximation (RTA) holds well. However, such a simple scaling does not hold in many strongly correlated electron systems, reflecting their unique electronic states. The most famous example would be cuprate high-Tc superconductors (HTSCs), where almost all the transport coefficients exhibit a significant deviation from the RTA results. To better understand the origin of this discrepancy, we develop a method for calculating various transport coefficients beyond the RTA by employing field theoretical techniques. Near the magnetic quantum critical point, the current vertex correction (CVC), which describes the electron-electron scattering beyond the relaxation time approximation, gives rise to various anomalous transport phenomena. We explain anomalous transport phenomena in cuprate HTSCs and other metals near their magnetic or orbital quantum critical point using a uniform approach. We also discuss spin related transport phenomena in strongly correlated systems. In many d- and f-electron systems, the spin current induced by the spin Hall effect is considerably greater because of the orbital degrees of freedom. This fact attracts much attention due to its potential application in spintronics. We discuss various novel charge, spin and heat transport phenomena in strongly correlated metals.

  3. Spin-flip configuration interaction singles with exact spin-projection: Theory and applications to strongly correlated systems.

    Science.gov (United States)

    Tsuchimochi, Takashi

    2015-10-14

    Spin-flip approaches capture static correlation with the same computational scaling as the ordinary single reference methods. Here, we extend spin-flip configuration interaction singles (SFCIS) by projecting out intrinsic spin-contamination to make it spin-complete, rather than by explicitly complementing it with spin-coupled configurations. We give a general formalism of spin-projection for SFCIS, applicable to any spin states. The proposed method is viewed as a natural unification of SFCIS and spin-projected CIS to achieve a better qualitative accuracy at a low computational cost. While our wave function ansatz is more compact than previously proposed spin-complete SF approaches, it successfully offers more general static correlation beyond biradicals without sacrificing good quantum numbers. It is also shown that our method is invariant with respect to open-shell orbital rotations, due to the uniqueness of spin-projection. We will report benchmark calculations to demonstrate its qualitative performance on strongly correlated systems, including conical intersections that appear both in ground-excited and excited-excited degeneracies.

  4. Nonequilibrium self-energy functional theory. Accessing the real-time dynamics of strongly correlated fermionic lattice systems

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, Felix

    2016-07-05

    The self-energy functional theory (SFT) is extended to the nonequilibrium case and applied to the real-time dynamics of strongly correlated lattice-fermions. Exploiting the basic structure of the well established equilibrium theory the entire formalism is reformulated in the language of Keldysh-Matsubara Green's functions. To this end, a functional of general nonequilibrium self-energies is constructed which is stationary at the physical point where it moreover yields the physical grand potential of the initial thermal state. Nonperturbative approximations to the full self-energy can be constructed by reducing the original lattice problem to smaller reference systems and varying the functional on the space of the respective trial self-energies, which are parametrized by the reference system's one-particle parameters. Approximations constructed in this way can be shown to respect the macroscopic conservation laws related to the underlying symmetries of the original lattice model. Assuming thermal equilibrium, the original SFT is recovered from the extended formalism. However, in the general case, the nonequilibrium variational principle comprises functional derivatives off the physical parameter space. These can be carried out analytically to derive inherently causal conditional equations for the optimal physical parameters of the reference system and a computationally realizable propagation scheme is set up. As a benchmark for the numerical implementation the variational cluster approach is applied to the dynamics of a dimerized Hubbard model after fast ramps of its hopping parameters. Finally, the time-evolution of a homogeneous Hubbard model after sudden quenches and ramps of the interaction parameter is studied by means of a dynamical impurity approximation with a single bath site. Sharply separated by a critical interaction at which fast relaxation to a thermal final state is observed, two differing response regimes can be distinguished, where the

  5. Transport phenomena in strongly correlated Fermi liquids

    CERN Document Server

    Kontani, Hiroshi

    2013-01-01

    In conventional metals, various transport coefficients are scaled according to the quasiparticle relaxation time, \\tau, which implies that the relaxation time approximation (RTA) holds well. However, such a simple scaling does not hold in many strongly correlated electron systems, reflecting their unique electronic states. The most famous example would be cuprate high-Tc superconductors (HTSCs), where almost all the transport coefficients exhibit a significant deviation from the RTA results. To better understand the origin of this discrepancy, we develop a method for calculating various transport coefficients beyond the RTA by employing field theoretical techniques. Near the magnetic quantum critical point, the current vertex correction (CVC), which describes the electron-electron scattering beyond the relaxation time approximation, gives rise to various anomalous transport phenomena. We explain anomalous transport phenomena in cuprate HTSCs and other metals near their magnetic or orbital quantum critical poi...

  6. Theoretical studies of strongly correlated fermions

    Energy Technology Data Exchange (ETDEWEB)

    Logan, D. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    Strongly correlated fermions are investigated. An understanding of strongly correlated fermions underpins a diverse range of phenomena such as metal-insulator transitions, high-temperature superconductivity, magnetic impurity problems and the properties of heavy-fermion systems, in all of which local moments play an important role. (author).

  7. Superconducting states in strongly correlated systems with nonstandard quasiparticles and real space pairing: an unconventional Fermi-liquid limit

    Directory of Open Access Journals (Sweden)

    J. Spałek

    2010-01-01

    Full Text Available We use the concept of generalized (almost localized Fermi Liquid composed of nonstandard quasiparticles with spin-dependence effective masses and the effective field induced by electron correlations. This Fermi liquid is obtained within the so-called statistically-consistent Gutzwiller approximation (SGA proposed recently [cf. J. Jędrak et al., arXiv: 1008.0021] and describes electronic states of the correlated quantum liquid. Particular emphasis is put on real space pairing driven by the electronic correlations, the Fulde-Ferrell state of the heavy-fermion liquid, and the d-wave superconducting state of high temperature curate superconductors in the overdoped limit. The appropriate phase diagrams are discussed showing in particular the limits of stability of the Bardeen-Cooper-Schrieffer (BCS type of state.

  8. Reply to ``Comment on `Cluster methods for strongly correlated electron systems' ''

    Science.gov (United States)

    Biroli, G.; Kotliar, G.

    2005-01-01

    We reply to the Comment by Aryanpour, Maier, and Jarrell [Phys. Rev. B 71, 037101 (2005)] on our paper [Phys. Rev. B 65, 155112 (2002)]. We demonstrate, using general arguments and explicit examples, that whenever the correlation length is finite, local observables converge exponentially fast in the cluster size Lc within cellular dynamical mean field theory. This is a faster rate of convergence than the 1/ L2c behavior of the dynamical cluster approximation, thus refuting the central assertion of their Comment.

  9. Coupled cluster valence bond theory for open-shell systems with application to very long range strong correlation in a polycarbene dimer.

    Science.gov (United States)

    Small, David W; Head-Gordon, Martin

    2017-07-14

    The Coupled Cluster Valence Bond (CCVB) method, previously presented for closed-shell (CS) systems, is extended to open-shell (OS) systems. The theoretical development is based on embedding the basic OS CCVB wavefunction in a fictitious singlet super-system. This approach reveals that the OS CCVB amplitude equations are quite similar to those of CS CCVB, and thus that OS CCVB requires the same level of computational effort as CS CCVB, which is an inexpensive method. We present qualitatively correct CCVB potential energy curves for all low-lying spin states of P 2 and Mn 2 + . CCVB is successfully applied to the low-lying spin states of some model linear polycarbenes, systems that appear to be a hindrance to standard density functionals. We examine an octa-carbene dimer in a side-by-side orientation, which, in the monomer dissociation limit, exhibits maximal strong correlation over the length of the polycarbene.

  10. Excitonic condensation of strongly correlated electrons: the case of Pr.sub.0.5./sub. Ca.sub.0.5./sub. CoO.sub.3./sub..

    Czech Academy of Sciences Publication Activity Database

    Kuneš, Jan; Augustinský, Pavel

    2014-01-01

    Roč. 90, č. 23 (2014), "235112-1"-"235112-5" ISSN 1098-0121 R&D Projects: GA ČR GA13-25251S Institutional support: RVO:68378271 Keywords : excitonic condensation * strongly correlated electrons * cobaltites Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  11. Description of the magnetic properties of strongly correlated disordered solid solutions in the coherent potential approximation

    Science.gov (United States)

    Korotin, M. A.; Skorikov, N. A.

    2015-06-01

    A method for electronic structure calculations of strongly correlated materials based on the coherent potential approximation is formulated and implemented. Method is applied for investigation of the electronic structure and local magnetic moments of the strongly correlated systems with d- and f-electrons: NiO-ZnO solid solution, nonstoichiometric perovskite LaMnO3-x, doped compound TiO2:Fe, and rare-earth transition-metal intermetallic compound GdNi2:Mn.

  12. Global solutions of restricted open-shell Hartree-Fock theory from semidefinite programming with applications to strongly correlated quantum systems.

    Science.gov (United States)

    Veeraraghavan, Srikant; Mazziotti, David A

    2014-03-28

    We present a density matrix approach for computing global solutions of restricted open-shell Hartree-Fock theory, based on semidefinite programming (SDP), that gives upper and lower bounds on the Hartree-Fock energy of quantum systems. While wave function approaches to Hartree-Fock theory yield an upper bound to the Hartree-Fock energy, we derive a semidefinite relaxation of Hartree-Fock theory that yields a rigorous lower bound on the Hartree-Fock energy. We also develop an upper-bound algorithm in which Hartree-Fock theory is cast as a SDP with a nonconvex constraint on the rank of the matrix variable. Equality of the upper- and lower-bound energies guarantees that the computed solution is the globally optimal solution of Hartree-Fock theory. The work extends a previously presented method for closed-shell systems [S. Veeraraghavan and D. A. Mazziotti, Phys. Rev. A 89, 010502-R (2014)]. For strongly correlated systems the SDP approach provides an alternative to the locally optimized Hartree-Fock energies and densities with a certificate of global optimality. Applications are made to the potential energy curves of C2, CN, Cr2, and NO2.

  13. Non-perturbative methodologies for low-dimensional strongly-correlated systems: From non-Abelian bosonization to truncated spectrum methods

    Science.gov (United States)

    James, Andrew J. A.; Konik, Robert M.; Lecheminant, Philippe; Robinson, Neil J.; Tsvelik, Alexei M.

    2018-04-01

    We review two important non-perturbative approaches for extracting the physics of low-dimensional strongly correlated quantum systems. Firstly, we start by providing a comprehensive review of non-Abelian bosonization. This includes an introduction to the basic elements of conformal field theory as applied to systems with a current algebra, and we orient the reader by presenting a number of applications of non-Abelian bosonization to models with large symmetries. We then tie this technique into recent advances in the ability of cold atomic systems to realize complex symmetries. Secondly, we discuss truncated spectrum methods for the numerical study of systems in one and two dimensions. For one-dimensional systems we provide the reader with considerable insight into the methodology by reviewing canonical applications of the technique to the Ising model (and its variants) and the sine-Gordon model. Following this we review recent work on the development of renormalization groups, both numerical and analytical, that alleviate the effects of truncating the spectrum. Using these technologies, we consider a number of applications to one-dimensional systems: properties of carbon nanotubes, quenches in the Lieb–Liniger model, 1  +  1D quantum chromodynamics, as well as Landau–Ginzburg theories. In the final part we move our attention to consider truncated spectrum methods applied to two-dimensional systems. This involves combining truncated spectrum methods with matrix product state algorithms. We describe applications of this method to two-dimensional systems of free fermions and the quantum Ising model, including their non-equilibrium dynamics.

  14. Noise Spectroscopy in Strongly Correlated Oxides

    Science.gov (United States)

    Alsaqqa, Ali M.

    Strongly correlated materials are an interesting class of materials, thanks to the novel electronic and magnetic phenomena they exhibit as a result of the interplay of various degrees of freedom. This gives rise to an array of potential applications, from Mott-FET to magnetic storage. Many experimental probes have been used to study phase transitions in strongly correlated oxides. Among these, resistance noise spectroscopy, together with conventional transport measurements, provides a unique viewpoint to understand the microscopic dynamics near the phase transitions in these oxides. In this thesis, utilizing noise spectroscopy and transport measurements, four different strongly correlated materials were studied: (1) neodymium nickel oxide (NdNiO 3) ultrathin films, (2) vanadium dioxide (VO2) microribbons, (3) copper vanadium bronze (CuxV2O 5) microribbons and (4) niobium triselenide (NbSe3) microribbons. Ultra thin films of rare-earth nickelates exhibit several temperature-driven phase transitions. In this thesis, we studied the metal-insulator and Neel transitions in a series of NdNiO3 films with different lattice mismatches. Upon colling down, the metal-insulator phase transition is accompanied by a structural (orthorohombic to monoclinic) and magnetic (paramagnetic to antiferromagnetic) transitions as well, making the problem more interesting and complex at the same time. The noise is of the 1/f type and is Gaussian in the high temperature phase, however deviations are seen in the low temperature phases. Below the metal-insulator transition, noise magnitude increases by orders of magnitude: a sign of inhomogeneous electrical conduction as result of phase separation. This is further assured by the non-Gaussian noise signature. At very low temperatures (T thesis, we tried to answer this question by utilizing three different tuning parameters: temperature, voltage bias and strain. Our results point to an unusual noise behavior in the high-temperature metallic phase

  15. Towards TDDFT for Strongly Correlated Materials

    Directory of Open Access Journals (Sweden)

    Shree Ram Acharya

    2016-09-01

    Full Text Available We present some details of our recently-proposed Time-Dependent Density-Functional Theory (TDDFT for strongly-correlated materials in which the exchange-correlation (XC kernel is derived from the charge susceptibility obtained using Dynamical Mean-Field Theory (the TDDFT + DMFT approach. We proceed with deriving the expression for the XC kernel for the one-band Hubbard model by solving DMFT equations via two approaches, the Hirsch–Fye Quantum Monte Carlo (HF-QMC and an approximate low-cost perturbation theory approach, and demonstrate that the latter gives results that are comparable to the exact HF-QMC solution. Furthermore, through a variety of applications, we propose a simple analytical formula for the XC kernel. Additionally, we use the exact and approximate kernels to examine the nonhomogeneous ultrafast response of two systems: a one-band Hubbard model and a Mott insulator YTiO3. We show that the frequency dependence of the kernel, i.e., memory effects, is important for dynamics at the femtosecond timescale. We also conclude that strong correlations lead to the presence of beats in the time-dependent electric conductivity in YTiO3, a feature that could be tested experimentally and that could help validate the few approximations used in our formulation. We conclude by proposing an algorithm for the generalization of the theory to non-linear response.

  16. Strong Correlation Physics in Aromatic Hydrocarbon Superconductors

    Science.gov (United States)

    Capone, Massimo; Giovannetti, Gianluca

    2012-02-01

    We show, by means of ab-initio calculations, that electron-electron correlations play an important role in doped aromatic hydrocarbon superconductors, including potassium doped picene with Tc= 18K [1], coronene and phenanthrene [2]. For the case of picene the inclusion of exchange interactions by means of hybrid functionals reproduces the correct gap for the undoped compound and predicts an antiferromagnetic state for x=3, where superconductivity has been observed [3]. The latter finding is compatible with a sizable value of the correlation strength. The differences between the different compounds are analyzed and results of Dynamical Mean-Field Theory including both correlation effects and electron-phonon interactions are presented. Finally we discuss the consequences of strong correlations in an organic superconductor in relation to the properties of Cs3C60, in which electron correlations drive an antiferromagnetic state [4] but also lead to an enhancement of superconductivity [5]. 1. R. Mitsuhashi et al. Nature 464, 76 (2010)2. X.F. Wang et al, Nat. Comm. 2, 507 (2011)3. G. Giovannetti and M. Capone, Phys. Rev. B 83, 134508 (2011)4. Y. Takabayashi et al., Science 323, 1585 (2009)5. M. Capone et al. Rev. Mod. Phys. 81, 943 (2009

  17. Strongly correlating liquids and their isomorphs

    OpenAIRE

    Pedersen, Ulf R.; Gnan, Nicoletta; Bailey, Nicholas P.; Schröder, Thomas B.; Dyre, Jeppe C.

    2010-01-01

    This paper summarizes the properties of strongly correlating liquids, i.e., liquids with strong correlations between virial and potential energy equilibrium fluctuations at constant volume. We proceed to focus on the experimental predictions for strongly correlating glass-forming liquids. These predictions include i) density scaling, ii) isochronal superposition, iii) that there is a single function from which all frequency-dependent viscoelastic response functions may be calculated, iv) that...

  18. Machine Learning Phases of Strongly Correlated Fermions

    Directory of Open Access Journals (Sweden)

    Kelvin Ch’ng

    2017-08-01

    Full Text Available Machine learning offers an unprecedented perspective for the problem of classifying phases in condensed matter physics. We employ neural-network machine learning techniques to distinguish finite-temperature phases of the strongly correlated fermions on cubic lattices. We show that a three-dimensional convolutional network trained on auxiliary field configurations produced by quantum Monte Carlo simulations of the Hubbard model can correctly predict the magnetic phase diagram of the model at the average density of one (half filling. We then use the network, trained at half filling, to explore the trend in the transition temperature as the system is doped away from half filling. This transfer learning approach predicts that the instability to the magnetic phase extends to at least 5% doping in this region. Our results pave the way for other machine learning applications in correlated quantum many-body systems.

  19. Self-consistent random phase approximation - application to systems of strongly correlated fermions; Approximation des phases aleatoires self-consistante - applications a des systemes de fermions fortement correles

    Energy Technology Data Exchange (ETDEWEB)

    Jemai, M

    2004-07-01

    In the present thesis we have applied the self consistent random phase approximation (SCRPA) to the Hubbard model with a small number of sites (a chain of 2, 4, 6,... sites). Earlier SCRPA had produced very good results in other models like the pairing model of Richardson. It was therefore interesting to see what kind of results the method is able to produce in the case of a more complex model like the Hubbard model. To our great satisfaction the case of two sites with two electrons (half-filling) is solved exactly by the SCRPA. This may seem a little trivial but the fact is that other respectable approximations like 'GW' or the approach with the Gutzwiller wave function yield results still far from exact. With this promising starting point, the case of 6 sites at half filling was considered next. For that case, evidently, SCRPA does not any longer give exact results. However, they are still excellent for a wide range of values of the coupling constant U, covering for instance the phase transition region towards a state with non zero magnetisation. We consider this as a good success of the theory. Non the less the case of 4 sites (a plaquette), as indeed all cases with 4n sites at half filling, turned out to have a problem because of degeneracies at the Hartree Fock level. A generalisation of the present method, including in addition to the pairs, quadruples of Fermions operators (called second RPA) is proposed to also include exactly the plaquette case in our approach. This is therefore a very interesting perspective of the present work. (author)

  20. Macroscopic quantum phenomena in strongly correlated fermionic systems; Phenomenes quantiques macroscopiques dans les systemes d'electrons fortement correles

    Energy Technology Data Exchange (ETDEWEB)

    Rech, J

    2006-06-15

    It took several years after the idea of a zero-temperature phase transition emerged to realize the impact of such a quantum critical point over a large region of the phase diagram. Observed in many experimental examples, this quantum critical regime is not yet understood in details theoretically, and one needs to develop new approaches. In the first part, we focused on the ferromagnetic quantum critical point. After constructing a controlled approach allowing us to describe the quantum critical regime, we show through the computation of the static spin susceptibility that the ferromagnetic quantum critical point is unstable, destroyed internally by an effective dynamic long-range interaction generated by the Landau damping. In the second part, we revisit the exactly screened single impurity Kondo model, using a bosonic representation of the local spin and treating it in the limit of large spin degeneracy N. We show that, in this regime, the ground-state is a non-trivial Fermi liquid, unlike what was advocated by previous similar studies. We then extend our method to encompass the physics of two coupled impurities, for which our results are qualitatively comparable to the ones obtained from various approaches carried out in the past. We also develop a Luttinger-Ward formalism, enabling us to cure some of the drawbacks of the original method used to describe the single impurity physics. Finally, we present the main ideas and the first results for an extension of the method towards the description of a Kondo lattice, relevant for the understanding of the quantum critical regime of heavy fermion materials. (authors)

  1. Kondo memory in driven strongly correlated quantum dots.

    Science.gov (United States)

    Zheng, Xiao; Yan, YiJing; Di Ventra, Massimiliano

    2013-08-23

    We investigate the real-time current response of strongly correlated quantum dot systems under sinusoidal driving voltages. By means of an accurate hierarchical equations of motion approach, we demonstrate the presence of prominent memory effects induced by the Kondo resonance on the real-time current response. These memory effects appear as distinctive hysteresis line shapes and self-crossing features in the dynamic current-voltage characteristics, with concomitant excitation of odd-number overtones. They emerge as a cooperative effect of quantum coherence-due to inductive behavior-and electron correlations-due to the Kondo resonance. We also show the suppression of memory effects and the transition to classical behavior as a function of temperature. All these phenomena can be observed in experiments and may lead to novel quantum memory applications.

  2. Charge frustration and quantum criticality for strongly correlated fermions

    NARCIS (Netherlands)

    Huijse, L.; Halverson, J.; Fendley, P.; Schoutens, K.

    2008-01-01

    We study a model of strongly correlated electrons on the square lattice which exhibits charge frustration and quantum critical behavior. The potential is tuned to make the interactions supersymmetric. We establish a rigorous mathematical result which relates quantum ground states to certain tiling

  3. Imaginary-time formulation of strongly correlated nonequilibrium

    Science.gov (United States)

    Heary, Ryan Joseph

    Strongly correlated nanostructures and lattices of electrons are studied when these systems reside in a steady-state nonequilibrium. Much of the work done to date has made use of the nonequilibrium real-time Keldysh Green function technique. These methods include: the Keldysh Green function perturbation theory, time-dependent numerical renormalization group, density matrix renormalization group, and diagrammatic quantum Monte Carlo. In the special case of steady-state nonequilibrium we construct an imaginary-time theory. The motivation to do this is simple: there exist an abundant number of well-established strongly correlated computational solvers for imaginary-time theory and perturbation theory on the imaginary-time contour is much more straightforward than that of the real-time contour. The first model system we focus on is a strongly interacting quantum dot situated between source and drain electron reservoirs. The steady-state nonequilibrium boundary condition is established by applying a voltage bias phi across the reservoirs, in turn modifying the chemical potentials of the leads. For a symmetric voltage drop we have mu source = phi/2 and mudrain = -phi/2. The dynamics of the electrons are governed by the Hamiltonian Ĥ which is inherently independent of the imbalance in the source and drain chemical potentials. The statistics though are determined by the operator Ĥ-Ŷ , where Ŷ imposes the nonequilibrium boundary condition. We show that it is possible to construct a single effective Hamiltonian K̂ able to describe both the dynamics and statistics of the system. Upon formulating the theory we explicitly show that it is consistent with the real-time Keldysh theory both formally and through an example using perturbation theory. In these systems there exists a strong interplay between the interactions and nonequilibrium leading to novel nonperturbative phenomena. Therefore, we combine our theory with the Hirsch-Fye quantum Monte Carlo algorithm to study

  4. High-field magnetostriction in CeNiSn{sub 1-x}Ge{sub x} (0<=x<=1) strongly correlated systems

    Energy Technology Data Exchange (ETDEWEB)

    Moral, A. del, E-mail: delmoral@unizar.e [Laboratorio de Magnetismo de Solidos, Departamento de Fisica de Materia Condensada and ICMA, Universidad de Zaragoza and CSIC, 50009 Zaragoza (Spain); Fuente, C. de la [Laboratorio de Magnetismo de Solidos, Departamento de Fisica de Materia Condensada and ICMA, Universidad de Zaragoza and CSIC, 50009 Zaragoza (Spain)

    2010-05-15

    Magnetization (down to 1.8 K and up to 9 T) and magnetostriction (down to 4.2 K and up to 30 T) measurements have been performed in the series of polycrystalline intermetallics CeNiSn{sub 1-x}Ge{sub x} (0<=x<=1), which show a crossover from Kondo-lattice to fluctuating valence behaviors with x increase. Magnetostriction observed can be denominated as 'colossal' for a paramagnet (up to 0.68% at 150 K and 30 T), with no sign of saturation. Field, H, induced metamagnetic transitions associated to a change in Ce valence are observed. Three kinds of analysis of magnetostriction have been performed to ascertain the magnetostriction origin. At relatively low field and low temperatures these systems follow well the standard theory of magnetostriction (STM), revealing single-ion crystal field and exchange origins, and a determination of the alpha-symmetry microscopic magnetoelastic parameters have been performed. The valence transition is well explained in terms of the interconfigurational model, which needs an extension up to power H{sup 4}. Application of the scaling (thermodynamics corresponding low states) allows the obtainment of the Grueneisen constant, which increases with x. Needed elastic constants measurements are also reported.

  5. Nonlinear phononics and structural control of strongly correlated materials

    Energy Technology Data Exchange (ETDEWEB)

    Mankowsky, Roman

    2016-01-20

    Mid-infrared light pulses can be used to resonantly excite infrared-active vibrational modes for the phase control of strongly correlated materials on subpicosecond timescales. As the energy is transferred directly into atomic motions, dissipation into the electronic system is reduced, allowing for the emergence of unusual low energy collective properties. Light-induced superconductivity, insulator-metal transitions and melting of magnetic order demonstrate the potential of this method. An understanding of the mechanism, by which these transitions are driven, is however missing. The aim of this work is to uncover this process by investigating the nonlinear lattice dynamics induced by the excitation and to elucidate their contribution to the modulation of collective properties of strongly correlated materials. The first signature of nonlinear lattice dynamics was reported in the observation of coherent phonon oscillations, resonant with the excitation of an infrared-active phonon mode in a manganite. This nonlinear phononic coupling can be described within a model, which predicts not only oscillatory coherent phonons dynamics but also directional atomic displacements along the coupled modes on average, which could cause the previously observed transitions. We verified this directional response and quantified the anharmonic coupling constant by tracing the atomic motions in a time-resolved hard X-ray diffraction experiment with sub-picometer spatial and femtosecond temporal resolution. In a subsequent study, we investigated the role of nonlinear lattice dynamics in the emergence of superconductivity far above the equilibrium transition temperature, an intriguing effect found to follow lattice excitation of YBa{sub 2}Cu{sub 3}O{sub 6+x}. By combining density functional theory (DFT) calculations of the anharmonic coupling constants with time-resolved X-ray diffraction experiments, we identified a structural rearrangement, which appears and decays with the same temporal

  6. Electronics and electronic systems

    CERN Document Server

    Olsen, George H

    1987-01-01

    Electronics and Electronic Systems explores the significant developments in the field of electronics and electronic devices. This book is organized into three parts encompassing 11 chapters that discuss the fundamental circuit theory and the principles of analog and digital electronics. This book deals first with the passive components of electronic systems, such as resistors, capacitors, and inductors. These topics are followed by a discussion on the analysis of electronic circuits, which involves three ways, namely, the actual circuit, graphical techniques, and rule of thumb. The remaining p

  7. Strongly correlated superconductivity and quantum criticality

    Science.gov (United States)

    Tremblay, A.-M. S.

    Doped Mott insulators and doped charge-transfer insulators describe classes of materials that can exhibit unconventional superconducting ground states. Examples include the cuprates and the layered organic superconductors of the BEDT family. I present results obtained from plaquette cellular dynamical mean-field theory. Continuous-time quantum Monte Carlo evaluation of the hybridization expansion allows one to study the models in the large interaction limit where quasiparticles can disappear. The normal state which is unstable to the superconducting state exhibits a first-order transition between a pseudogap and a correlated metal phase. That transition is the finite-doping extension of the metal-insulator transition obtained at half-filling. This transition serves as an organizing principle for the normal and superconducting states of both cuprates and doped organic superconductors. In the less strongly correlated limit, these methods also describe the more conventional case where the superconducting dome surrounds an antiferromagnetic quantum critical point. Sponsored by NSERC RGPIN-2014-04584, CIFAR, Research Chair in the Theory of Quantum Materials.

  8. Strongly correlated quasi-one-dimensional bands: Ground states, optical absorption, and phonons

    International Nuclear Information System (INIS)

    Campbell, D.K.; Gammel, J.T.; Loh, E.Y. Jr.

    1989-01-01

    Using the Lanczos method for exact diagonalization on systems up to 14 sites, combined with a novel ''phase randomization'' technique for extracting more information from these small systems, we investigate several aspects of the one-dimensional Peierls-Hubbard Hamiltonian, in the context of trans-polyacetylene: the dependence of the ground state dimerization on the strength of the electron-electron interactions, including the effects of ''off-diagonal'' Coulomb terms generally ignored in the Hubbard model; the phonon vibrational frequencies and dispersion relations, and the optical absorption properties, including the spectrum of absorptions as a function of photon energy. These three different observables provide considerable insight into the effects of electron-electron interactions on the properties of real materials and thus into the nature of strongly correlated electron systems. 29 refs., 11 figs

  9. Describing nonequilibrium behavior in strongly correlated materials via dynamical mean-field theory

    Science.gov (United States)

    Freericks, James

    2010-03-01

    Dynamical mean-field theory was introduced in 1989 and has become one of the most successful methods for solving models of strongly correlated electrons in equilibrium (it becomes exact in the infinite-dimensional limit). In this talk, I show how to generalize dynamical mean-field theory to nonequilibrium situations. For transient response, one discretizes the Kadanoff-Baym-Keldysh contour then solves the discrete problem directly. For steady-state response, one can formulate a theory directly in the long-time limit for the retarded Green's functions. These techniques are applied to the problem of the quenching of Bloch oscillations due to electron-electron interactions and to the problem of time-resolved pump/probe photoemission spectroscopy of strongly correlated electrons when a system is driven to a nonequilibrium steady state and cannot be described by the quasiequilibrium approximation with an effective temperature. This work was completed in collaboration with Tom Devereaux, Sasha Joura, Hulikal Krishnamurthy, Brian Moritz, Thomas Pruschke, Volodomyr Turkowski, and Velko Zlati'c. Recent references include: J. K. Freericks, V. M. Turkowski, and V. Zlati'c, Phys. Rev. Lett. 97, 266408 (2006); J. K. Freericks, Phys. Rev. B 77, 075109 (2008); A. V.Joura, J. K. Freericks, and Th. Pruschke, Phys. Rev. Lett. 101, 196401 (2008); J. K. Freericks, H. R. Krishnamurthy and Th. Pruschke, Phys. Rev. Lett. 102, 136401 (2009); and B. Moritz, T. P. Devereaux, and J. K. Freericks, arXiv:0908.1807.

  10. Disorder effects in strongly correlated uranium compounds

    International Nuclear Information System (INIS)

    Suellow, S.; Maple, M.B.; Tomuta, D.; Nieuwenhuys, G.J.; Menovsky, A.A.; Mydosh, J.A.; Chau, R.

    2001-01-01

    Moderate levels of crystallographic disorder can dramatically affect the ground-state properties of heavy fermion compounds. In particular, the role of disorder close to a quantum critical point has been investigated in detail. However, crystallographic disorder is equally effective in altering the properties of magnetically ordered heavy fermion compounds like URh 2 Ge 2 , where disorder-induced spin-glass behavior has been observed. In this system, moreover, the magnetic ground state can be tuned from a spin-glass to a long-range ordered antiferromagnetic one by means of an annealing treatment. The transformation of the magnetic state is accompanied by a transition in the transport properties from 'quasi-insulating' (dρ/dT 2 Ge 2 will be discussed. Of particular interest is the resistivity of as-grown URh 2 Ge 2 , which resembles the Non-Fermi-liquid system UCu 4 Pd, suggesting that a common mechanism - the crystallographic disorder - controls the transport properties of these materials

  11. Doubly excited helium. From strong correlation to chaos

    International Nuclear Information System (INIS)

    Jiang, Yuhai

    2006-03-01

    In the present dissertation, the double excitation states of helium including the autoionization decay of these states were studied experimentally and theoretically in a broad energy region, which includes the transition from strong correlation below the low single ionization thresholds (SIT) to the region of quantum chaos at energies very close to the double-ionization threshold. Two kind of experiments were performed, namely total-ion-yield measurements with the aim to observe total cross sections (TCS) and electron time-of-flight (TOF) measurements to obtain partial cross sections (PCS) as well as angular distribution parameters (ADP). Both types of measurements were performed at the third generation synchrotron radiation facility BESSY II in Berlin. The TCSs were recorded up to the SIT I 15 , and they were found to be in in excellent agreement with state-of-the-art complex-rotation calculations performed recently by D. Delande. These experimental and theoretical data on the TCSs were analyzed in order to study quantum chaos in doubly excited helium, and interesting signatures of quantum chaos were found. The TOF technique allowed to measure PCSs and ADPs in the energy regions from I 5 to I 9 and I 7 , respectively. These experimental data provide a critical assessment of theoretical models that can be used to explore the dynamics of strong correlation as well as quantum chaos in helium. In the theoretical part of this dissertation, the n- and l-specific PCSs and ADPs below I 4 were calculated employing the R-matrix method. The present theoretical results agree well with a recent experimental study of l-specific PCSs below I 4 by J.R. Harries et al. An analysis of patterns in the PCSs and ADPs on the basis of the present experimental and theoretical l-specific data allowed to improve the present understanding of autoionization decay dynamics in this two-electron atom. (orig.)

  12. Doubly excited helium. From strong correlation to chaos

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yuhai

    2006-03-15

    In the present dissertation, the double excitation states of helium including the autoionization decay of these states were studied experimentally and theoretically in a broad energy region, which includes the transition from strong correlation below the low single ionization thresholds (SIT) to the region of quantum chaos at energies very close to the double-ionization threshold. Two kind of experiments were performed, namely total-ion-yield measurements with the aim to observe total cross sections (TCS) and electron time-of-flight (TOF) measurements to obtain partial cross sections (PCS) as well as angular distribution parameters (ADP). Both types of measurements were performed at the third generation synchrotron radiation facility BESSY II in Berlin. The TCSs were recorded up to the SIT I{sub 15}, and they were found to be in in excellent agreement with state-of-the-art complex-rotation calculations performed recently by D. Delande. These experimental and theoretical data on the TCSs were analyzed in order to study quantum chaos in doubly excited helium, and interesting signatures of quantum chaos were found. The TOF technique allowed to measure PCSs and ADPs in the energy regions from I{sub 5} to I{sub 9} and I{sub 7}, respectively. These experimental data provide a critical assessment of theoretical models that can be used to explore the dynamics of strong correlation as well as quantum chaos in helium. In the theoretical part of this dissertation, the n- and l-specific PCSs and ADPs below I{sub 4} were calculated employing the R-matrix method. The present theoretical results agree well with a recent experimental study of l-specific PCSs below I{sub 4} by J.R. Harries et al. An analysis of patterns in the PCSs and ADPs on the basis of the present experimental and theoretical l-specific data allowed to improve the present understanding of autoionization decay dynamics in this two-electron atom. (orig.)

  13. Weak-coupling superconductivity in a strongly correlated iron pnictide.

    Science.gov (United States)

    Charnukha, A; Post, K W; Thirupathaiah, S; Pröpper, D; Wurmehl, S; Roslova, M; Morozov, I; Büchner, B; Yaresko, A N; Boris, A V; Borisenko, S V; Basov, D N

    2016-01-05

    Iron-based superconductors have been found to exhibit an intimate interplay of orbital, spin, and lattice degrees of freedom, dramatically affecting their low-energy electronic properties, including superconductivity. Albeit the precise pairing mechanism remains unidentified, several candidate interactions have been suggested to mediate the superconducting pairing, both in the orbital and in the spin channel. Here, we employ optical spectroscopy (OS), angle-resolved photoemission spectroscopy (ARPES), ab initio band-structure, and Eliashberg calculations to show that nearly optimally doped NaFe0.978Co0.022As exhibits some of the strongest orbitally selective electronic correlations in the family of iron pnictides. Unexpectedly, we find that the mass enhancement of itinerant charge carriers in the strongly correlated band is dramatically reduced near the Γ point and attribute this effect to orbital mixing induced by pronounced spin-orbit coupling. Embracing the true band structure allows us to describe all low-energy electronic properties obtained in our experiments with remarkable consistency and demonstrate that superconductivity in this material is rather weak and mediated by spin fluctuations.

  14. Algorithmic implementation of particle-particle ladder diagram approximation to study strongly-correlated metals and semiconductors

    Science.gov (United States)

    Prayogi, A.; Majidi, M. A.

    2017-07-01

    In condensed-matter physics, strongly-correlated systems refer to materials that exhibit variety of fascinating properties and ordered phases, depending on temperature, doping, and other factors. Such unique properties most notably arise due to strong electron-electron interactions, and in some cases due to interactions involving other quasiparticles as well. Electronic correlation effects are non-trivial that one may need a sufficiently accurate approximation technique with quite heavy computation, such as Quantum Monte-Carlo, in order to capture particular material properties arising from such effects. Meanwhile, less accurate techniques may come with lower numerical cost, but the ability to capture particular properties may highly depend on the choice of approximation. Among the many-body techniques derivable from Feynman diagrams, we aim to formulate algorithmic implementation of the Ladder Diagram approximation to capture the effects of electron-electron interactions. We wish to investigate how these correlation effects influence the temperature-dependent properties of strongly-correlated metals and semiconductors. As we are interested to study the temperature-dependent properties of the system, the Ladder diagram method needs to be applied in Matsubara frequency domain to obtain the self-consistent self-energy. However, at the end we would also need to compute the dynamical properties like density of states (DOS) and optical conductivity that are defined in the real frequency domain. For this purpose, we need to perform the analytic continuation procedure. At the end of this study, we will test the technique by observing the occurrence of metal-insulator transition in strongly-correlated metals, and renormalization of the band gap in strongly-correlated semiconductors.

  15. Strongly-correlated ultracold atoms in optical lattices

    International Nuclear Information System (INIS)

    Dao, Tung-Lam

    2008-01-01

    This thesis is concerned with the theoretical study of strongly correlated quantum states of ultra-cold fermionic atoms trapped in optical lattices. This field has grown considerably in recent years, following the experimental progress made in cooling and controlling atomic gases, which has led to the observation of the first Bose-Einstein condensation (in 1995). The trapping of these gases in optical lattices has opened a new field of research at the interface between atomic physics and condensed matter physics. The observation of the transition from a superfluid to a Mott insulator for bosonic atoms paved the way for the study of strongly correlated phases and quantum phase transitions in these systems. Very recently, the investigation of the Mott insulator state of fermionic atoms provides additional motivation to conduct such theoretical studies. This thesis can be divided broadly into two types of work: - On the one hand, we have proposed a new type of spectroscopy to measure single-particle correlators and associated physical observables in these strongly correlated states. - On the other hand, we have studied the ground state of the fermionic Hubbard model under different conditions (mass imbalance, population imbalance) by using analytical techniques and numerical simulations. In a collaboration with J. Dalibard and C. Salomon (LKB at the ENS Paris) and I. Carusotto (Trento, Italy), we have proposed and studied a novel spectroscopic method for the measurement and characterization of single particle excitations (in particular, the low energy excitations, namely the quasiparticles) in systems of cold fermionic atoms, with energy and momentum resolution. This type of spectroscopy is an analogue of angular-resolved photoemission in solid state physics (ARPES). We have shown, via simple models, that this method of measurement can characterize quasiparticles not only in the 'conventional' phases such as the weakly interacting gas in the lattice or in Fermi

  16. Electronic properties of strongly correlated fermions in nanostructures

    International Nuclear Information System (INIS)

    Lopez-Sandoval, R; Pastor, G M

    2004-01-01

    Lattice density-functional theory is applied to small clusters described by the Hubbard model in order to study the effect of the correlation on these nano-objects. Results for the ground-state energy and charge excitation gap of small clusters are presented and discussed as a function of the number of sites N a , Coulomb repulsion U/t, and band filling n

  17. Proceedings, strongly correlated electronic materials: The Los Alamos symposium 1993

    International Nuclear Information System (INIS)

    Bedell, K.S.

    1994-01-01

    The subject included such topics as high temperature superconductors, heavy-fermion insulators and superconductors, the metal-insulator transition, the superconductor-insulator transition and unusual (non-Fermi liquid) normal metallic states. The symposium was structured around 13 invited review talks; with each talk, there were several (about 30) related short presentations and discussion sections (90 pages). The review talks and short papers were processed separately for the data base

  18. [Realistic theories of heavy electron and other strongly correlated materials

    International Nuclear Information System (INIS)

    1993-01-01

    Research on the following topics is summarized: non-perturbative treatments of multi-channel Kondo models, non-perturbative treatments of multi-band models for the quadrupolar fluctuation model of the cuprates, extension of the two-channel Kondo model to other materials and treatment of the infinite-dimensional Hubbard model within the Non-crossing approximation. Data on the specific heat of Y 0.8 U 0.2 Pd 3 and the c-axis susceptibility and specific heat of U in ThRu 2 Si are shown. 5 figs., 84 refs

  19. [Realistic theories of heavy electron and other strongly correlated materials

    Energy Technology Data Exchange (ETDEWEB)

    1993-04-01

    Research on the following topics is summarized: non-perturbative treatments of multi-channel Kondo models, non-perturbative treatments of multi-band models for the quadrupolar fluctuation model of the cuprates, extension of the two-channel Kondo model to other materials and treatment of the infinite-dimensional Hubbard model within the Non-crossing approximation. Data on the specific heat of Y{sub 0.8}U{sub 0.2}Pd{sub 3} and the c-axis susceptibility and specific heat of U in ThRu{sub 2}Si are shown. 5 figs., 84 refs.

  20. Mott Transition In Strongly Correlated Materials: Many-Body Methods And Realistic Materials Simulations

    Science.gov (United States)

    Lee, Tsung-Han

    Strongly correlated materials are a class of materials that cannot be properly described by the Density Functional Theory (DFT), which is a single-particle approximation to the original many-body electronic Hamiltonian. These systems contain d or f orbital electrons, i.e., transition metals, actinides, and lanthanides compounds, for which the electron-electron interaction (correlation) effects are too strong to be described by the single-particle approximation of DFT. Therefore, complementary many-body methods have been developed, at the model Hamiltonians level, to describe these strong correlation effects. Dynamical Mean Field Theory (DMFT) and Rotationally Invariant Slave-Boson (RISB) approaches are two successful methods that can capture the correlation effects for a broad interaction strength. However, these many-body methods, as applied to model Hamiltonians, treat the electronic structure of realistic materials in a phenomenological fashion, which only allow to describe their properties qualitatively. Consequently, the combination of DFT and many body methods, e.g., Local Density Approximation augmented by RISB and DMFT (LDA+RISB and LDA+DMFT), have been recently proposed to combine the advantages of both methods into a quantitative tool to analyze strongly correlated systems. In this dissertation, we studied the possible improvements of these approaches, and tested their accuracy on realistic materials. This dissertation is separated into two parts. In the first part, we studied the extension of DMFT and RISB in three directions. First, we extended DMFT framework to investigate the behavior of the domain wall structure in metal-Mott insulator coexistence regime by studying the unstable solution describing the domain wall. We found that this solution, differing qualitatively from both the metallic and the insulating solutions, displays an insulating-like behavior in resistivity while carrying a weak metallic character in its electronic structure. Second, we

  1. Investigating short-range magnetism in strongly correlated materials via magnetic pair distribution function analysis and ab initio theory

    Science.gov (United States)

    Frandsen, Benjamin; Page, Katharine; Brunelli, Michela; Staunton, Julie; Billinge, Simon

    Short-range magnetic correlations are known to exist in a variety of strongly correlated electron systems, but our understanding of the role they play is challenged by the difficulty of experimentally probing such correlations. Magnetic pair distribution function (mPDF) analysis is a newly developed neutron total scattering method that can reveal short-range magnetic correlations directly in real space, and may therefore help ameliorate this difficulty. We present temperature-dependent mPDF measurements of the short-range magnetic correlations in the paramagnetic phase of antiferromagnetic MnO, an archetypal strongly correlated transition-metal oxide. We observe significant correlations on a ~1 nm length scale that differ substantially from the low-temperature long-range-ordered spin arrangement. With no free parameters, ab initio calculations using the self-interaction-corrected local spin density approximation of density functional theory quantitatively reproduce the magnetic correlations to a high degree of accuracy. These results yield valuable insight into the magnetic exchange in MnO and showcase the utility of the mPDF technique for studying magnetic properties of strongly correlated electron systems.

  2. Study of rare earth local moment magnetism and strongly correlated phenomena in various crystal structures

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Tai [Iowa State Univ., Ames, IA (United States)

    2016-12-17

    Benefiting from unique properties of 4f electrons, rare earth based compounds are known for offering a versatile playground for condensed matter physics research as well as industrial applications. This thesis focuses on three specific examples that further explore the rare earth local moment magnetism and strongly correlated phenomena in various crystal structures.

  3. An important role of temperature dependent scattering time in understanding the high temperature thermoelectric behavior of strongly correlated system: La0.75Ba0.25CoO3.

    Science.gov (United States)

    Singh, Saurabh; Kumar, Devendra; Pandey, Sudhir K

    2017-03-15

    In the present work, we report the temperature dependent thermopower (α) behavior of La 0.75 Ba 0.25 CoO 3 compound in the temperature range 300-600 K. Using the Heikes formula, the estimated value of α corresponding to high-spin configuration of Co 3+ and Co 4+ ions is found to be  ∼16 [Formula: see text], which is close to the experimental value, ∼13 [Formula: see text], observed at  ∼600 K. The temperature dependent TE behavior of the compound is studied by combining the WIEN2K and BoltzTrap code. The self consistency field calculations show that the compound have ferromagnetic ground state structure. The electronic structure calculations give half metallic characteristic with a small gap of  ∼50 meV for down spin channel. The large and positive value for down spin channel is obtained due to the unique band structure shown by this spin channel. The temperature dependent relaxation time for both the spin-channel charge carriers is considered to study the thermopower data in temperature range 300-600 K. For evaluation of α, almost linear values of [Formula: see text] and a non-linear values of [Formula: see text] are taken into account. By taking the temperature dependent values of relaxation time for both the spin channels, the calculated values of α using two current model are found to be in good agreement with experimental values in the temperature range 300-600 K. At 300 K, the calculated value of electrical conductivity by using the same value of relaxation time, i.e. 0.1 [Formula: see text] 10 -14 seconds for spin-up and [Formula: see text] seconds for spin-dn channel, is found to be equal to the experimentally reported value.

  4. Importance of strong-correlation on the lattice dynamics of light-actinides Th-Pa alloy

    Science.gov (United States)

    de La Peã+/-A Seaman, Omar; Heid, Rolf; Bohnen, Klaus-Peter

    We have studied the structural, electronic, and lattice dynamics of the Th1-xPax actinide alloy. This system have been analyzed within the framework of density functional perturbation theory, using a mixed-basis pseudopotential method and the virtual crystal approximation (VCA) for modeling the alloy. In particular, the energetics is analyzed as the ground-state crystal structure is changed form fcc to bct, as well as the electronic density of states (DOS), and the phonon frequencies. Such properties have been calculated with and without strong correlations effects through the LDA+U formalism. Although the strong-correlation does not influence on a great manner the Th properties, such effects are more important as the content increases towards Pa, affecting even the definition of the ground-state crystal structure for Pa (experimentally determined as bct). The evolution of the density of states at the Fermi level (N (EF)) and the phonon frequencies as a function of Pa-content are presented and discussed in detail, aiming to understand their influence on the electron-phonon coupling for the Th-Pa alloy. This research was supported by Conacyt-México under project No. CB2013-221807-F.

  5. Strongly correlated Fermi-Bose mixtures in disordered optical lattices

    International Nuclear Information System (INIS)

    Sanchez-Palencia, L; Ahufinger, V; Kantian, A; Zakrzewski, J; Sanpera, A; Lewenstein, M

    2006-01-01

    We investigate theoretically the low-temperature physics of a two-component ultracold mixture of bosons and fermions in disordered optical lattices. We focus on the strongly correlated regime. We show that, under specific conditions, composite fermions, made of one fermion plus one bosonic hole, form. The composite picture is used to derive an effective Hamiltonian whose parameters can be controlled via the boson-boson and the boson-fermion interactions, the tunnelling terms and the inhomogeneities. We finally investigate the quantum phase diagram of the composite fermions and show that it corresponds to the formation of Fermi glasses, spin glasses and quantum percolation regimes

  6. Strongly correlated Fermi-Bose mixtures in disordered optical lattices

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Palencia, L [Laboratoire Charles Fabry de l' Institut d' Optique, CNRS and Universite Paris-Sud XI, Bat 503, Centre scientifique, F-91403 Orsay Cedex (France); Ahufinger, V [ICREA and Grup d' optica, Departament de FIsica, Universitat Autonoma de Barcelona, E-08193 Belaterra (Barcelona) (Spain); Kantian, A [Institut fuer Theoretische Physik, Universitaet Innsbruck, A-6020 Innsbruck (Austria); Zakrzewski, J [Instytut Fizyki imienia Mariana Smoluchowskiego i Centrum Badan Ukladow Zlozonych imienia Marka Kaca, Uniwersytet Jagiellonski, ulica Reymonta 4, PL-30-059 Krakow (Poland); Sanpera, A [ICREA and Grup de FIsica Teorica, Departament de FIsica, Universitat Autonoma de Barcelona, E-08193 Belaterra (Barcelona) (Spain); Lewenstein, M [ICREA and ICFO-Institut de Ciencies Fotoniques, Parc Mediterrani de la TecnologIa, E-08860 Castelldefels (Barcelona) (Spain); Institut fuer Theoretische Physik, Universitaet Hannover, D-30167 Hannover (Germany)

    2006-05-28

    We investigate theoretically the low-temperature physics of a two-component ultracold mixture of bosons and fermions in disordered optical lattices. We focus on the strongly correlated regime. We show that, under specific conditions, composite fermions, made of one fermion plus one bosonic hole, form. The composite picture is used to derive an effective Hamiltonian whose parameters can be controlled via the boson-boson and the boson-fermion interactions, the tunnelling terms and the inhomogeneities. We finally investigate the quantum phase diagram of the composite fermions and show that it corresponds to the formation of Fermi glasses, spin glasses and quantum percolation regimes.

  7. Fulleride Superconductors are Phonon-Driven and Strongly Correlated

    Science.gov (United States)

    Tosatti, Erio; Capone, Massimo; Castellani, Claudio; Fabrizio, Michele

    2010-03-01

    Superconductivity in trivalent alkali fullerides is believed to be phonon-driven and s-wave, similar in that to ordinary BCS systems. There is nonetheless in these materials a metal-Mott insulator transition upon lattice expansion, indicating exceedingly strong electron-electron correlations. Using Dynamical Mean Field Theory we solved a 3-band Hubbard model, including both electron-electron and (simplified) electron-phonon interactions, which yields a phase diagram [1] in striking agreement with the experimental one for the recently discovered expanded fulleride Cs3C60 as a function of pressure.[2] A dome-shaped superconducting order parameter, a pseudogap phase, and the subsequent Mott transition upon expansion thus assimilate the phonon driven fulleride superconductors to cuprates and to 2D organics, despite their obvious differences. Some experimental predictions are made, including a kinetic energy gain and a Drude weight increase in the superconducting state relative to the normal state, contrary to BCS, but similar to cuprates. [1] M. Capone, et al., Rev. Mod. Phys. 81,943 (2009); [2] Y. Takabayashi et al., Science 323, 1585 (2009).

  8. Modeling Strongly Correlated Fermi Systems Using Ultra-Cold Atoms

    National Research Council Canada - National Science Library

    O'Hara, Kenneth M

    2008-01-01

    ... displays, photodynamic therapy, and a pump for Cr:LiSAF lasers. This work also led to new insights into how high-power multi-longitudinal mode fiber lasers can be used for preparing quantum degenerate atomic gases...

  9. ATOMIC SCREENING AND INTERSITE COULOMB REPULSION IN STRONGLY CORRELATED SYSTEMS

    NARCIS (Netherlands)

    Meinders, M.B J; van den Brink, J.; Lorenzana, J.; Sawatzky, G.A

    1995-01-01

    We consider the influence of a nearest-neighbor Coulomb interaction in an extended Hubbard model and introduce an interaction term which simulates atomic polarizabilities. The inclusion of atomic polarizabilities in the model has the effect of screening the on-site Coulomb interaction for charged

  10. String Theory, Strongly Correlated Systems, and Duality Twists

    Science.gov (United States)

    Torres Chicon, Nesty Ray

    In the first part of this dissertation (Chapter 1), I present a construction of a six dimensional (2,0)-theory model that describes the dynamics of the Fractional Quantum Hall Effect (FQHE). The FQHE appears as part of the low energy description of the Coulomb branch of the A1 (2,0)-theory formulated on a geometry (S 1 x R2)/Zk. At low-energy, the configuration is described in terms of a 4+1D supersymmetric Yang-Mills (SYM) theory on a cone (R2/Z k) with additional 2+1D degrees of freedom at the tip of the cone that include fractionally charged particles. These fractionally charged "quasi-particles" are BPS strings of the (2,0)-theory wrapped on short cycles. In this framework, a W-boson can be modeled as a bound state of k quasi-particles, which can be used to understand the dynamics of the FQHE. In the second part of this dissertation (Chapters 2-3), I investigate the N=4 SYM theory compactified on a circle, with a varying coupling constant (Janus configuration) and an S-duality twist. I relate this setup to a three dimensional topological theory and to a dual string theory. The equality of these descriptions is exhibited by matching the operator algebra, and the dimensions of the Hilbert space. Additionally, this dissertation addresses a classic result in number theory, called quadratic reciprocity, using string theory language. I present a proof that quadratic reciprocity is a direct consequence of T-duality of Type-II string theory. This is demonstrated by analyzing a partition function of abelian N=4 SYM theory on a certain supersymmetry-preserving four-manifold with variable coupling constant and a SL(2,Z)-duality twist.

  11. Superconductivity by charge and spin fluctuations in strongly correlated systems

    Energy Technology Data Exchange (ETDEWEB)

    Costa-Quintana, J. [Universitat Autonoma de Barcelona (Spain). Grup d`Electromagnetisme; Gonzalez-Leon, E. [Universitat Autonoma de Barcelona (Spain). Grup d`Electromagnetisme; Lopez Aguilar, F. [Universitat Autonoma de Barcelona (Spain). Grup d`Electromagnetisme; Puig-Puig, L. [Universitat Autonoma de Barcelona (Spain). Grup d`Electromagnetisme; Sanchez-Lopez, M.M. [Universitat Autonoma de Barcelona (Spain). Grup d`Electromagnetisme

    1995-02-01

    We obtain the effective potential from a screened coulombian interaction considering separately the interaction between fermions with parallel and antiparallel spins. In both cases we analyze the possibility of obtaining superconductivity. ((orig.)).

  12. Modeling Strongly Correlated Fermi Systems Using Ultra-Cold Atoms

    National Research Council Canada - National Science Library

    O'Hara, Kenneth M

    2008-01-01

    .... This work resulted in the development of a new all-solid state laser source for red laser light which can be used for lithium spectroscopy and may be useful in other applications such as color...

  13. Joint statistics of strongly correlated neurons via dimensionality reduction

    Science.gov (United States)

    Deniz, Taşkın; Rotter, Stefan

    2017-06-01

    The relative timing of action potentials in neurons recorded from local cortical networks often shows a non-trivial dependence, which is then quantified by cross-correlation functions. Theoretical models emphasize that such spike train correlations are an inevitable consequence of two neurons being part of the same network and sharing some synaptic input. For non-linear neuron models, however, explicit correlation functions are difficult to compute analytically, and perturbative methods work only for weak shared input. In order to treat strong correlations, we suggest here an alternative non-perturbative method. Specifically, we study the case of two leaky integrate-and-fire neurons with strong shared input. Correlation functions derived from simulated spike trains fit our theoretical predictions very accurately. Using our method, we computed the non-linear correlation transfer as well as correlation functions that are asymmetric due to inhomogeneous intrinsic parameters or unequal input.

  14. Lattice disorder in strongly correlated lanthanide and actinide intermetallics

    International Nuclear Information System (INIS)

    Booth, C.H.; Bauer, E.D.; Maple, M.B.; Lawrence, J.M.; Kwei, G.H.; Sarrao, J.L.

    2001-01-01

    Lanthanide and actinide intermetallic compounds display a wide range of correlated-electron behavior, including ferromagnetism, antiferromagnetism, nonmagnetic (Kondo) ground states, and so-called 'non-Fermi liquid' (NFL) behavior. The interaction between f electrons and the conduction band is a dominant factor in determining the ground state of a given system. However, lattice disorder can create a distribution of interactions, generating unusual physical properties. These properties may include NFL behavior in many materials. In addition, lattice disorder can cause deviations from standard Kondo behavior that is less severe than NFL behavior. A review of the lattice disorder mechanism within a tight-binding model is presented, along with measurements of the YbBCu 4 and UPd x Cu 5-x systems, demonstrating the applicability of the model. These measurements indicate that while the YbBCu 4 system appears to be well ordered, both site interchange and continuous bond-length disorder occur in the UPd x Cu 5-x series. Nevertheless, the measured bond-length disorder in UPdCu 4 does not appear to be enough to explain the NFL properties simply with the Kondo disorder model. (au)

  15. Lattice disorder in strongly correlated lanthanide and actinide intermetallics.

    Science.gov (United States)

    Booth, C H; Bauer, E D; Maple, M B; Lawrence, J M; Kwei, G H; Sarrao, J L

    2001-03-01

    Lanthanide and actinide intermetallic compounds display a wide range of correlated-electron behavior, including ferromagnetism, antiferromagnetism, nonmagnetic (Kondo) ground states, and so-called 'non-Fermi liquid' (NFL) behavior. The interaction between f electrons and the conduction band is a dominant factor in determining the ground state of a given system. However, lattice disorder can create a distribution of interactions, generating unusual physical properties. These properties may include NFL behavior in many materials. In addition, lattice disorder can cause deviations from standard Kondo behavior that is less severe than NFL behavior. A review of the lattice disorder mechanism within a tight-binding model is presented, along with measurements of the YbBCu4 and UPd(x)Cu(5-x) systems, demonstrating the applicability of the model. These measurements indicate that while the YbBCu4 system appears to be well ordered, both site interchange and continuous bond-length disorder occur in the UPd(x)Cu(5-x) series. Nevertheless, the measured bond-length disorder in UPdCu4 does not appear to be enough to explain the NFL properties simply with the Kondo disorder model.

  16. Communication: The description of strong correlation within self-consistent Green's function second-order perturbation theory

    International Nuclear Information System (INIS)

    Phillips, Jordan J.; Zgid, Dominika

    2014-01-01

    We report an implementation of self-consistent Green's function many-body theory within a second-order approximation (GF2) for application with molecular systems. This is done by iterative solution of the Dyson equation expressed in matrix form in an atomic orbital basis, where the Green's function and self-energy are built on the imaginary frequency and imaginary time domain, respectively, and fast Fourier transform is used to efficiently transform these quantities as needed. We apply this method to several archetypical examples of strong correlation, such as a H 32 finite lattice that displays a highly multireference electronic ground state even at equilibrium lattice spacing. In all cases, GF2 gives a physically meaningful description of the metal to insulator transition in these systems, without resorting to spin-symmetry breaking. Our results show that self-consistent Green's function many-body theory offers a viable route to describing strong correlations while remaining within a computationally tractable single-particle formalism

  17. Effects of Strong Correlations on the Disorder-Induced Zero Bias Anomaly

    Science.gov (United States)

    Atkinson, William; Song, Yun; Bulut, Sinan; Wortis, Rachel

    2009-03-01

    In conventional metals and semiconductors, density of states anomalies result from the interplay between disorder and interactions. Motivated by a number of experiments that find zero bias anomalies (ZBA) in transition metal oxides, we have performed calculations to determine the effect of strong correlations on the ZBA in disordered interacting systems. We use a self-consistent mean-field theory that incorporates strong correlations and treats spatial fluctuations of the disorder potential exactly. We discuss both the Anderson-Hubbard model and the extended Anderson-Hubbard model. We find that, even for a zero-range interaction, nonlocal self-energy corrections lead to the formation of an Altshuler-Aronov-like ZBA. In the extended Anderson-Hubbard model, Efros-Shklovskii-like physics dominates at large disorder.

  18. Quantum Femtosecond Magnetism: Phase Transition in Step with Light in a Strongly Correlated Manganese Oxide

    Science.gov (United States)

    Wang, Jigang

    2014-03-01

    Research of non-equilibrium phase transitions of strongly correlated electrons is built around addressing an outstanding challenge: how to achieve ultrafast manipulation of competing magnetic/electronic phases and reveal thermodynamically hidden orders at highly non-thermal, femtosecond timescales? Recently we reveal a new paradigm called quantum femtosecond magnetism-photoinduced femtosecond magnetic phase transitions driven by quantum spin flip fluctuations correlated with laser-excited inter-atomic coherent bonding. We demonstrate an antiferromagnetic (AFM) to ferromagnetic (FM) switching during about 100 fs laser pulses in a colossal magneto-resistive manganese oxide. Our results show a huge photoinduced femtosecond spin generation, measured by magnetic circular dichroism, with photo-excitation threshold behavior absent in the picosecond dynamics. This reveals an initial quantum coherent regime of magnetism, while the optical polarization/coherence still interacts with the spins to initiate local FM correlations that compete with the surrounding AFM matrix. Our results thus provide a framework that explores quantum non-equilibrium kinetics to drive phase transitions between exotic ground states in strongly correlated elecrons, and raise fundamental questions regarding some accepted rules, such as free energy and adiabatic potential surface. This work is in collaboration with Tianqi Li, Aaron Patz, Leonidas Mouchliadis, Jiaqiang Yan, Thomas A. Lograsso, Ilias E. Perakis. This work was supported by the National Science Foundation (contract no. DMR-1055352). Material synthesis at the Ames Laboratory was supported by the US Department of Energy-Basic Energy Sciences (contract no. DE-AC02-7CH11358).

  19. Rydberg-atom formation in strongly correlated ultracold plasmas

    International Nuclear Information System (INIS)

    Bannasch, G.; Pohl, T.

    2011-01-01

    In plasmas at very low temperatures, the formation of neutral atoms is dominated by collisional three-body recombination, owing to the strong ∼T -9/2 scaling of the corresponding recombination rate with the electron temperature T. While this law is well established at high temperatures, the unphysical divergence as T→0 clearly suggests a breakdown in the low-temperature regime. Here, we present a combined molecular dynamics Monte Carlo study of electron-ion recombination over a wide range of temperatures and densities. Our results reproduce the known behavior of the recombination rate at high temperatures, but reveal significant deviations with decreasing temperature. We discuss the fate of the kinetic bottleneck and resolve the divergence problem as the plasma enters the ultracold, strongly coupled domain.

  20. Strongly correlated dynamics in multichannel quantum {RC} circuits

    OpenAIRE

    Dutt Prasenjit; Schmidt Thomas L.; Mora Christophe; Le Hur Karyn

    2013-01-01

    We examine dissipation effects in a multichannel quantum RC circuit, comprising a cavity or single-electron box capacitively coupled to a gate and connected to a reservoir lead via several conducting channels. Depending on the engineering details of the quantum RC circuit, the number of channels contributing to transport vary, as do the form of the interchannel couplings. For low-frequency AC transport, the charge-relaxation resistance ($R_{q}$) is a nontrivial function of the parameters of t...

  1. Generalized-active-space pair-density functional theory: an efficient method to study large, strongly correlated, conjugated systems† †Electronic supplementary information (ESI) available: Singlet–triplet energy gaps for CASSCF(4,4), CASSCF(8,8), DFP-1, DFP-3, and KS-DFT methods, numbers of CSFs with more significant figures, occupation numbers for HONO–1, HONO, LUNO and LUNO+1 for FP-1 and DFP-1, singlet–triplet energy gap (kcal mol–1) of decacene for DFP-1 partition with other geometries, singlet–triplet energy gap (kcal mol–1) of hexacene for different on-top functionals, molecular geometries, and absolute energies. See DOI: 10.1039/c6sc05036k Click here for additional data file.

    Science.gov (United States)

    Ghosh, Soumen

    2017-01-01

    Predicting ground- and excited-state properties of open-shell organic molecules by electronic structure theory can be challenging because an accurate treatment has to correctly describe both static and dynamic electron correlation. Strongly correlated systems, i.e., systems with near-degeneracy correlation effects, are particularly troublesome. Multiconfigurational wave function methods based on an active space are adequate in principle, but it is impractical to capture most of the dynamic correlation in these methods for systems characterized by many active electrons. We recently developed a new method called multiconfiguration pair-density functional theory (MC-PDFT), that combines the advantages of wave function theory and density functional theory to provide a more practical treatment of strongly correlated systems. Here we present calculations of the singlet–triplet gaps in oligoacenes ranging from naphthalene to dodecacene. Calculations were performed for unprecedently large orbitally optimized active spaces of 50 electrons in 50 orbitals, and we test a range of active spaces and active space partitions, including four kinds of frontier orbital partitions. We show that MC-PDFT can predict the singlet–triplet splittings for oligoacenes consistent with the best available and much more expensive methods, and indeed MC-PDFT may constitute the benchmark against which those other models should be compared, given the absence of experimental data. PMID:28553509

  2. Nonperturbative stochastic dynamics driven by strongly correlated colored noise

    Science.gov (United States)

    Jing, Jun; Li, Rui; You, J. Q.; Yu, Ting

    2015-02-01

    We propose a quantum model consisting of two remote qubits interacting with two correlated colored noises and establish an exact stochastic Schrödinger equation for this open quantum system. It is shown that the quantum dynamics of the qubit system is profoundly modulated by the mutual correlation between baths and the bath memory capability through dissipation and fluctuation. We report a physical effect on generating inner correlation and entanglement of two distant qubits arising from the strong bath-bath correlation.

  3. Can strong correlations be experimentally revealed for Ҡ -mesons?

    Directory of Open Access Journals (Sweden)

    Hiesmayr Beatrix C.

    2014-01-01

    Full Text Available In 1964 the physicists John St. Bell working at CERN took the 1935-idea of Einstein-Podolsky-Rosen seriously and found that all theories based on local realism have to satisfy a certain inequality, nowadays dubbed Bell’s inequality. Experiments with ordinary matter systems or light show violations of Bell’s inequality favouring the quantum theory though a loophole free experiment has not yet been performed. This contribution presents an experimentally feasible Bell inequality for systems at higher energy scales, i.e. entangled neutral Ҡ -meson pairs that are typically produced in Φ -mesons decays or proton-antiproton annihilation processes. Strong requirements have to be overcome in order to achieve a conclusive tests, such a proposal was recently published. Surprisingly, this new Bell inequality reveals new features for weakly decaying particles, in particular, a strong sensitivity to the combined charge-conjugation-parity (CP symmetry. Here-with, a puzzling relation between a symmetry breaking for mesons and Bell’s inequality—which is a necessary and sufficient condition for the security of quantum cryptography protocols— is established. This becomes the more important since CP symmetry is related to the cosmological question why the antimatter disappeared after the Big Bang.

  4. Spatial complexity due to strong correlations in vanadium dioxide

    Science.gov (United States)

    Liu, Shuo; Phillabaum, Benjamin; Carlson, Erica; Dahmen, Karin; Qazilbash, Mumtaz; Basov, Dmitri; Sudhindra, Vidhyadhiraja

    2013-03-01

    Near-field scanning infrared microscopy on the Mott metal-insulator system vanadium dioxide (VO2) has revealed complex nanoscale pattern formation in the form of insulating and metallic puddles near the insulator-to-metal transition. We use and extend recently developed cluster techniques in order to understand the fundamental physics driving this multiscale pattern formation. We map the observed metallic and insulating clusters to Ising variables by a rigorous choice of threshold amplitude, and quantify the statistics of the sizes and shapes of the geometric clusters. These in turn yield critical exponents including the cluster size distribution exponent τ, and the fractal dimensions associated with the cluster formation. These quantitative measures show power-law behavior over multiple decades, revealing a delicate interplay between interactions and disorder in the material. The cluster techniques employed here can be readily applied to 2D image data in the context of other materials and measurement techniques.

  5. Electronics circuits and systems

    CERN Document Server

    Bishop, Owen

    2011-01-01

    The material in Electronics - Circuits and Systems is a truly up-to-date textbook, with coverage carefully matched to the electronics units of the 2007 BTEC National Engineering and the latest AS and A Level specifications in Electronics from AQA, OCR and WJEC. The material has been organized with a logical learning progression, making it ideal for a wide range of pre-degree courses in electronics. The approach is student-centred and includes: numerous examples and activities; web research topics; Self Test features, highlighted key facts, formulae and definitions. Ea

  6. Electronics circuits and systems

    CERN Document Server

    Bishop, Owen

    2007-01-01

    The material in Electronics - Circuits and Systems is a truly up-to-date textbook, with coverage carefully matched to the electronics units of the 2007 BTEC National Engineering and the latest AS and A Level specifications in Electronics from AQA, OCR and WJEC. The material has been organized with a logical learning progression, making it ideal for a wide range of pre-degree courses in electronics. The approach is student-centred and includes: numerous examples and activities; web research topics; Self Test features, highlighted key facts, formulae and definitions. Each chapter ends with a set

  7. Strongdeco: Expansion of analytical, strongly correlated quantum states into a many-body basis

    Science.gov (United States)

    Juliá-Díaz, Bruno; Graß, Tobias

    2012-03-01

    We provide a Mathematica code for decomposing strongly correlated quantum states described by a first-quantized, analytical wave function into many-body Fock states. Within them, the single-particle occupations refer to the subset of Fock-Darwin functions with no nodes. Such states, commonly appearing in two-dimensional systems subjected to gauge fields, were first discussed in the context of quantum Hall physics and are nowadays very relevant in the field of ultracold quantum gases. As important examples, we explicitly apply our decomposition scheme to the prominent Laughlin and Pfaffian states. This allows for easily calculating the overlap between arbitrary states with these highly correlated test states, and thus provides a useful tool to classify correlated quantum systems. Furthermore, we can directly read off the angular momentum distribution of a state from its decomposition. Finally we make use of our code to calculate the normalization factors for Laughlin's famous quasi-particle/quasi-hole excitations, from which we gain insight into the intriguing fractional behavior of these excitations. Program summaryProgram title: Strongdeco Catalogue identifier: AELA_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AELA_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 5475 No. of bytes in distributed program, including test data, etc.: 31 071 Distribution format: tar.gz Programming language: Mathematica Computer: Any computer on which Mathematica can be installed Operating system: Linux, Windows, Mac Classification: 2.9 Nature of problem: Analysis of strongly correlated quantum states. Solution method: The program makes use of the tools developed in Mathematica to deal with multivariate polynomials to decompose analytical strongly correlated states of bosons

  8. Collective oscillations of strongly correlated one-dimensional bosons on a lattice.

    Science.gov (United States)

    Rigol, M; Rousseau, V; Scalettar, R T; Singh, R R P

    2005-09-09

    We study the dipole oscillations of strongly correlated 1D bosons, in the hard-core limit, on a lattice, by an exact numerical approach. We show that far from the regime where a Mott insulator appears in the system, damping is always present and increases for larger initial displacements of the trap, causing dramatic changes in the momentum distribution, n(k). When a Mott insulator sets in the middle of the trap, the center of mass barely moves after an initial displacement, and n(k) remains very similar to the one in the ground state. We also study changes introduced by the damping in the natural orbital occupations, and the revival of the center-of-mass oscillations after long times.

  9. Selective Mottness as a key to iron superconductors: weak and strong correlations

    Science.gov (United States)

    de Medici, Luca

    2014-03-01

    I will discuss the strength of electronic correlations in the normal phase of Fe-superconductors and trace a comparison with cuprates. The phase diagram of the high-Tc cuprates is dominated by the Mott insulating phase of the parent compounds. Approaching it from large doping, a standard Fermi-liquid is seen to gradually turn into a bad non-Fermi liquid metal in which quasiparticles have heavily differentiated coherence depending on momentum, a process which culminates in the pseudogap regime, in which the antinodal region in momentum space acquires a gap before the material reaches a fully gapped Mott state. I will show that experiments for electron- and hole-doped BaFe2As2 support an analogous scenario. The doping evolution is dominated by the influence of a Mott insulator that would be realized for half-filled conduction bands, while the stoichiometric compound does not play a special role. Weakly and strongly correlated conduction electrons coexist in much of the phase diagram, a differentiation that increases with hole-doping. We identify the reason for this ``selective Mottness'' in a simple emergent mechanism, an ``orbital decoupling,'' triggered by the strong Hund's coupling. When this mechanism is active charge excitations in the different orbitals are decoupled and each orbital behaves as a single band Hubbard model, where the correlation degree almost only depends on how doped is each orbital from half-filling. This scenario reconciles contrasting evidences on the electronic correlation strength, implies a strong asymmetry between hole- and electron-doping and establishes a deep connection with the cuprates. L. de' Medici, G. Giovannetti and M. Capone, ArXiv:1212.3966 Work supported by CNRS - ESPCI ParisTech, France

  10. Electronic components and systems

    CERN Document Server

    Dennis, W H

    2013-01-01

    Electronic Components and Systems focuses on the principles and processes in the field of electronics and the integrated circuit. Covered in the book are basic aspects and physical fundamentals; different types of materials involved in the field; and passive and active electronic components such as capacitors, inductors, diodes, and transistors. Also covered in the book are topics such as the fabrication of semiconductors and integrated circuits; analog circuitry; digital logic technology; and microprocessors. The monograph is recommended for beginning electrical engineers who would like to kn

  11. Electronics a systems approach

    CERN Document Server

    Storey, Neil

    2017-01-01

    Electronics plays a central role in our everyday lives. It is at the heart of almost all of today's essential technology, from mobile phones to computers and from cars to power stations. As such, all engineers, scientists and technologists need to have a fundamental understanding of this exciting subject, and for many this will just be the beginning. Now in its sixth edition, Electronics: A Systems Approach provides an outstanding introduction to this fast-moving and important field. Comprehensively revised and updated to cover the latest developments in the world of electronics, the text continues to use Neil Storey's established and well-respected systems approach. It introduces the basic concepts first before progressing to a more advanced analysis, enabling you to contextualise what a system is designed to achieve before tackling the intricacies of designing or analysing its various components with confidence. This book is accompanied by a website which contains over 100 video tutorials to help explain ke...

  12. Femtosecond switching of magnetism via strongly correlated spin-charge quantum excitations.

    Science.gov (United States)

    Li, Tianqi; Patz, Aaron; Mouchliadis, Leonidas; Yan, Jiaqiang; Lograsso, Thomas A; Perakis, Ilias E; Wang, Jigang

    2013-04-04

    The technological demand to push the gigahertz (10(9) hertz) switching speed limit of today's magnetic memory and logic devices into the terahertz (10(12) hertz) regime underlies the entire field of spin-electronics and integrated multi-functional devices. This challenge is met by all-optical magnetic switching based on coherent spin manipulation. By analogy to femtosecond chemistry and photosynthetic dynamics--in which photoproducts of chemical and biochemical reactions can be influenced by creating suitable superpositions of molecular states--femtosecond-laser-excited coherence between electronic states can switch magnetic order by 'suddenly' breaking the delicate balance between competing phases of correlated materials: for example, manganites exhibiting colossal magneto-resistance suitable for applications. Here we show femtosecond (10(-15) seconds) photo-induced switching from antiferromagnetic to ferromagnetic ordering in Pr0.7Ca0.3MnO3, by observing the establishment (within about 120 femtoseconds) of a huge temperature-dependent magnetization with photo-excitation threshold behaviour absent in the optical reflectivity. The development of ferromagnetic correlations during the femtosecond laser pulse reveals an initial quantum coherent regime of magnetism, distinguished from the picosecond (10(-12) seconds) lattice-heating regime characterized by phase separation without threshold behaviour. Our simulations reproduce the nonlinear femtosecond spin generation and underpin fast quantum spin-flip fluctuations correlated with coherent superpositions of electronic states to initiate local ferromagnetic correlations. These results merge two fields, femtosecond magnetism in metals and band insulators, and non-equilibrium phase transitions of strongly correlated electrons, in which local interactions exceeding the kinetic energy produce a complex balance of competing orders.

  13. Electron-electron interactions in disordered systems

    CERN Document Server

    Efros, AL

    1985-01-01

    ``Electron-Electron Interactions in Disordered Systems'' deals with the interplay of disorder and the Coulomb interaction. Prominent experts give state-of-the-art reviews of the theoretical and experimental work in this field and make it clear that the interplay of the two effects is essential, especially in low-dimensional systems.

  14. Electron beam processing system

    International Nuclear Information System (INIS)

    Kashiwagi, Masayuki

    2004-01-01

    Electron beam Processing Systems (EPS) are used as useful and powerful tools in many industrial application fields such as the production of cross-linked wire, rubber tire, heat shrinkable film and tubing, curing, degradation of polymers, sterilization and environmental application. In this paper, the feature and application fields, the selection of machine ratings and safety measures of EPS will be described. (author)

  15. The shot noise of a strongly correlated quantum dot coupled to the Luttinger liquid leads

    International Nuclear Information System (INIS)

    Yang, Kai-Hua; He, Xian; Wang, Huai-Yu; Liu, Kai-Di; Liu, Bei-Yun

    2014-01-01

    We study the shot noise of a strongly correlated quantum dot weakly coupled to Luttinger liquid leads in the Kondo regime by means of the extended equation of motion method. A general zero-frequency shot noise formula with good convergence is derived. The shot noise exhibits a non-monotonic dependence on voltage for weak intralead interaction. There is a peak around the Kondo temperature at low voltage when the interaction is very weak, and its height decreases rapidly with the intralead interaction increasing. When the interaction is moderately strong the peak disappears and the shot noise scales as a power law in bias voltage, indicating that the intralead electron interaction suppresses the shot noise. It is possible that the measurements of the shot noise spectrum can extract the information of the intralead interaction. - Highlights: • The shot noise of a dot coupled to Luttinger liquid leads in the Kondo regime. • A shot noise formula is derived. • Intralead interaction suppresses the shot noise. • The noise shows different voltage-dependence for different intralead interaction

  16. Supersolidity of lattice bosons immersed in strongly correlated Rydberg dressed atoms

    Science.gov (United States)

    Li, Yongqiang; Geißler, Andreas; Hofstetter, Walter; Li, Weibin

    2018-02-01

    Recent experiments have illustrated that long-range two-body interactions can be induced by laser coupling atoms to highly excited Rydberg states. Stimulated by this achievement, we study the supersolidity of lattice bosons in an experimentally relevant situation. In our setup, we consider two-component atoms on a square lattice, where one species is weakly dressed to an electronically high-lying (Rydberg) state, generating a tunable, soft-core shape long-range interaction. Interactions between atoms of the second species and between the two species are characterized by local inter- and intraspecies interactions. Using a dynamical mean-field calculation, we find that interspecies on-site interactions can stabilize a pronounced region of supersolid phases. This is characterized by two distinctive types of supersolids, where the bare species forms supersolid phases that are immersed in strongly correlated quantum phases, i.e., a crystalline solid or supersolid of the dressed atoms. We show that the interspecies interaction leads to a rotonlike instability in the bare species and therefore is crucially important to the supersolid formation. We provide a detailed calculation of the interaction potential to show how our results can be explored under current experimental conditions.

  17. Inhomogeneities in a strongly correlated d-wave superconductors in the limit of strong disorder

    Science.gov (United States)

    Chakraborty, Debmalya; Sensarma, Rajdeep; Ghosal, Amit

    2015-03-01

    The complex interplay of the strong correlations and impurities in a high temperature superconductor is analyzed within a Hartree-Fock-Bogoliubov theory, augmented with Gutzwiller approximation for taking care of the strong electronic repulsion. The inclusion of such correlations is found to play a crucial role in reducing inhomogeneities in both qualitative and quantitative manner. This difference is comprehended by investigating the underlying one-particle ``normal states'' that includes the order parameters in the Hartree and Fock channels in the absence of superconductivity. This amounts to the renormalization of disorder both on the lattice sites and also on links. These two components of disorder turn out to be spatially anti-correlated through self-consistency. Interestingly, a simple pairing theory in terms of these normal states is found to describe the complex behaviors of dirty cuprates with reasonable accuracy. However, this framework needs modifications in the limit where disorder strengths are comparable to the band width. We will discuss appropriate updates in the formalism to describe physics of inhomogeneities with strong disorder.

  18. MDT DCS Electronics System

    CERN Document Server

    Tsarouchas, Charilaos; Gazis, Evangelos; Tsipolitis, Georgios

    This note has the aim to present the Detector Control System for the Monitor- ing of the electronics values of MDT chambers in ATLAS experiment in CERN. This system is decided to be called in short ELTX. The principal task of DCS is to enable and ensure the coherent and safe oper- ation of the detector. The interaction of detector expers, users or shifters to the detector hardware is also done via DCS. This is the responsible system of moni- toring the operational parameters and the overall state of the detector, the alarm generation and handling, the connection of hardware values to databases and the interaction with the DAQ system. Through this thesis, one can see what ELTX system has to offer as a Detector Control System and in detail, what is the hardware to be controlled and monitored. Moreover it is presented the mainstream of central Atlas DCS concerning the active interfaces.ELTX is a system following these standards.

  19. Exchange and spin-fluctuation superconducting pairing in the strong correlation limit of the Hubbard model

    International Nuclear Information System (INIS)

    Plakida, N. M.; Anton, L.; Adam, S. . Department of Theoretical Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering, PO Box MG-6, RO-76900 Bucharest - Magurele; RO); Adam, Gh. . Department of Theoretical Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering, PO Box MG-6, RO-76900 Bucharest - Magurele; RO)

    2001-01-01

    A microscopical theory of superconductivity in the two-band singlet-hole Hubbard model, in the strong coupling limit in a paramagnetic state, is developed. The model Hamiltonian is obtained by projecting the p-d model to an asymmetric Hubbard model with the lower Hubbard subband occupied by one-hole Cu d-like states and the upper Hubbard subband occupied by two-hole p-d singlet states. The model requires two microscopical parameters only, the p-d hybridization parameter t and the charge-transfer gap Δ. It was previously shown to secure an appropriate description of the normal state properties of the high -T c cuprates. To treat rigorously the strong correlations, the Hubbard operator technique within the projection method for the Green function is used. The Dyson equation is derived. In the molecular field approximation, d-wave superconducting pairing of conventional hole (electron) pairs in one Hubbard subband is found, which is mediated by the exchange interaction given by the interband hopping, J ij = 4 (t ij ) 2 / Δ. The normal and anomalous components of the self-energy matrix are calculated in the self-consistent Born approximation for the electron-spin-fluctuation scattering mediated by kinematic interaction of the second order of the intraband hopping. The derived numerical and analytical solutions predict the occurrence of singlet d x 2 -y 2 -wave pairing both in the d-hole and singlet Hubbard subbands. The gap functions and T c are calculated for different hole concentrations. The exchange interaction is shown to be the most important pairing interaction in the Hubbard model in the strong correlation limit, while the spin-fluctuation coupling results only in a moderate enhancement of T c . The smaller weight of the latter comes from two specific features: its vanishing inside the Brillouin zone (BZ) along the lines, |k x | + |k y |=π pointing towards the hot spots and the existence of a small energy shell within which the pairing is effective. By

  20. Electronics for embedded systems

    CERN Document Server

    Bindal, Ahmet

    2017-01-01

    This book provides semester-length coverage of electronics for embedded systems, covering most common analog and digital circuit-related issues encountered while designing embedded system hardware. It is written for students and young professionals who have basic circuit theory background and want to learn more about passive circuits, diode and bipolar transistor circuits, the state-of-the-art CMOS logic family and its interface with older logic families such as TTL, sensors and sensor physics, operational amplifier circuits to condition sensor signals, data converters and various circuits used in electro-mechanical device control in embedded systems. The book also provides numerous hardware design examples by integrating the topics learned in earlier chapters. The last chapter extensively reviews the combinational and sequential logic design principles to be able to design the digital part of embedded system hardware.

  1. Nonlinear waves from a localized vortex source in strongly correlated fluids

    Science.gov (United States)

    Gupta, Akanksha; Ganesh, Rajaraman; Joy, Ashwin

    2017-11-01

    Highly charged quasi two-dimensional grain medium (complex plasma) is a remarkable test-bed to study wave like phenomena. Understanding of such wave propagation has many important applications in geophysics, petroleum engineering, and mining, earthquakes, and seismology. In the present study, for the first time, the propagation of nonlinear wave which originates from localized coherent vortex source has been studied using molecular dynamics simulation taking Yukawa liquids as a prototype for strongly correlated fluid. In this work, the coupling of transverse and longitudinal mode, effect of azimuthal speed of vortex source on the linear and nonlinear properties of generated wave will be presented as a function of strong correlation.

  2. Novel strongly correlated electron states in filled skutterudite lanthanide osmium antimonides

    International Nuclear Information System (INIS)

    Maple, M.B.; Frederick, N.A.; Ho, P.-C.; Yuhasz, W.M.; Sayles, T.A.; Butch, N.P.; Jeffries, J.R.; Taylor, B.J.

    2005-01-01

    Recent measurements on the filled skutterudite compounds Pr(Os 1-x Ru x ) 4 Sb 12 , NdOs 4 Sb 12 , and SmOs 4 Sb 12 are discussed. Pr(Os 1-x Ru x ) 4 Sb 12 displays superconductivity for all values of x with a minimum at x=0.6, and only the compounds with x 4 Sb 12 and the BCS superconductivity of PrRu 4 Sb 12 . NdOs 4 Sb 12 is a heavy fermion ferromagnet, with a sharp transition observed at 1.0K. SmOs 4 Sb 12 is also a heavy fermion material, and it may display weak ferromagnetic behavior below 2.6K

  3. Hybrid exchange-correlation energy functionals for strongly correlated electrons. Applications to transition-metal monoxides

    Czech Academy of Sciences Publication Activity Database

    Tran, F.; Blaha, P.; Schwarz, K.; Novák, Pavel

    2006-01-01

    Roč. 74, č. 15 (2006), 155108/1-155108/10 ISSN 1098-0121 R&D Projects: GA AV ČR(CZ) IAA1010214 EU Projects: European Commission(XE) HPRN-CT-2002-00293 - SCOOTMO Grant - others:Austrian Science Fondation(AT) AURORA project SFB011 Institutional research plan: CEZ:AV0Z10100521 Keywords : density functional theory * hybrid functional * transition metal monoxides Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.107, year: 2006

  4. Electronic Nicotine Delivery Systems.

    Science.gov (United States)

    Walley, Susan C; Jenssen, Brian P

    2015-11-01

    Electronic nicotine delivery systems (ENDS) are rapidly growing in popularity among youth. ENDS are handheld devices that produce an aerosolized mixture from a solution typically containing concentrated nicotine, flavoring chemicals, and propylene glycol to be inhaled by the user. ENDS are marketed under a variety of names, most commonly electronic cigarettes and e-cigarettes. In 2014, more youth reported using ENDS than any other tobacco product. ENDS pose health risks to both users and nonusers. Nicotine, the major psychoactive ingredient in ENDS solutions, is both highly addictive and toxic. In addition to nicotine, other toxicants, carcinogens, and metal particles have been detected in solutions and aerosols of ENDS. Nonusers are involuntarily exposed to the emissions of these devices with secondhand and thirdhand aerosol. The concentrated and often flavored nicotine in ENDS solutions poses a poisoning risk for young children. Reports of acute nicotine toxicity from US poison control centers have been increasing, with at least 1 child death reported from unintentional exposure to a nicotine-containing ENDS solution. With flavors, design, and marketing that appeal to youth, ENDS threaten to renormalize and glamorize nicotine and tobacco product use. There is a critical need for ENDS regulation, legislative action, and counter promotion to protect youth. ENDS have the potential to addict a new generation of youth to nicotine and reverse more than 50 years of progress in tobacco control. Copyright © 2015 by the American Academy of Pediatrics.

  5. Establishing a Consistent Theory of Transport in Strongly Correlated Fermi Superfluids

    Science.gov (United States)

    Boyack, Rufus M.

    A diagrammatic method of obtaining exact gauge-invariant response functions in strongly correlated Fermi superfluids is implemented for several example condensed matter systems of current interest. These include: topological superfluids, high temperature superconductors, and superfluids with finite center-of-mass momentum pairing known as Fulde-Ferrell superfluids. Much of the literature on these systems has focused on single-particle properties or alternatively has invoked simple approximations to treat response functions. The goal is to show that, for this wide class of topical problems, one can compute exact response functions. This enables assessment of the validity of different physical scenarios and allows a very broad class of experiments to be addressed. The method developed is based on deriving the full electromagnetic vertex, which satisfies the Ward-Takahashi identity, and determining the collective modes in a manner compatible with the self-consistent gap equation. In the condensed phase of a superfluid and a superconductor, where gauge invariance is spontaneously broken, it is crucial to determine the collective modes from the gap equation in a manner which restores gauge invariance. Our diagrammatic framework provides a very general and powerful method for obtaining these collective modes in a variety of strongly correlated Fermi superfluids. We show that a full electromagnetic vertex satisfying the Ward-Takahashi identity ensures the f-sum rule is satisfied and thus charge is conserved. This diagrammatic method is implemented for both normal and superfluid phases. While there are no collective modes in the normal phase, the Ward-Takahashi identity plays a similarly important role. In particular, for the normal phase we study Rashba spin-orbit coupled Fermi gases with intrinsic pairing in the absence and presence of a magnetic field. Exact density and spin response functions are obtained, even in the absence of a spin conservation law, providing

  6. Full momentum- and energy-resolved spectral function of a 2D electronic system

    Science.gov (United States)

    Jang, Joonho; Yoo, Heun Mo; Pfeiffer, L. N.; West, K. W.; Baldwin, K. W.; Ashoori, Raymond C.

    2017-11-01

    The single-particle spectral function measures the density of electronic states in a material as a function of both momentum and energy, providing central insights into strongly correlated electron phenomena. Here we demonstrate a high-resolution method for measuring the full momentum- and energy-resolved electronic spectral function of a two-dimensional (2D) electronic system embedded in a semiconductor. The technique remains operational in the presence of large externally applied magnetic fields and functions even for electronic systems with zero electrical conductivity or with zero electron density. Using the technique on a prototypical 2D system, a GaAs quantum well, we uncover signatures of many-body effects involving electron-phonon interactions, plasmons, polarons, and a phonon analog of the vacuum Rabi splitting in atomic systems.

  7. BESIII online electronics calibration system

    International Nuclear Information System (INIS)

    Wang Liang; Lei Guangkun; Zhu Kejun; Zhao Jingwei; Li Fei

    2006-01-01

    This paper introduce the components of BESIII DAQ System. It describe the relationship of internal online electrionics calibration's components, the mechanism of dataflow and message flow and the implementation of system functions. When BESIII is running, the system will be used to online calibrate electronics channels and provide the calibration params to adjust electronics data. (authors)

  8. Designing, Probing, and Stabilizing Exotic Fabry-Perot Cavities for Studying Strongly Correlated Light

    Science.gov (United States)

    Ryou, Albert

    Synthetic materials made of engineered quasiparticles are a powerful platform for studying manybody physics and strongly correlated systems due to their bottom-up approach to Hamiltonian modeling. Photonic quasiparticles called polaritons are particularly appealing since they inherit fast dynamics from light and strong interaction from matter. This thesis describes the experimental demonstration of cavity Rydberg polaritons, which are composite particles arising from the hybridization of an optical cavity with Rydberg EIT, as well as the tools for probing and stabilizing the cavity. We first describe the design, construction, and testing of a four-mirror Fabry-Perot cavity, whose small waist size on the order of 10 microns is comparable to the Rydberg blockade radius. By achieving strong coupling between the cavity photon and an atomic ensemble undergoing electromagnetically induced transparency (EIT), we observe the emergence of the dark-state polariton and characterize its single-body properties as well as the single-quantum nonlinearity. We then describe the implementation of a holographic spatial light modulator for exciting different transverse modes of the cavity, an essential tool for studying polariton-polariton scattering. For compensating optical aberrations, we employ a digital micromirror device (DMD), combining beam shaping with adaptive optics to produce diffraction-limited light. We quantitatively measure the purity of the DMD-produced Hermite-Gauss modes and confirm up to 99.2% efficiency. One application of the technique is to create Laguerre-Gauss modes, which have been used to probe synthetic Landau levels for photons in a twisted, nonplanar cavity. Finally, we describe the implementation of an FPGA-based FIR filter for stabilizing the cavity. We digitally cancel the acoustical resonances of the feedback-controlled mechanical system, thereby demonstrating an order-of-magnitude enhancement in the feedback bandwidth from 200 Hz to more than 2 k

  9. [Electronic poison information management system].

    Science.gov (United States)

    Kabata, Piotr; Waldman, Wojciech; Kaletha, Krystian; Sein Anand, Jacek

    2013-01-01

    We describe deployment of electronic toxicological information database in poison control center of Pomeranian Center of Toxicology. System was based on Google Apps technology, by Google Inc., using electronic, web-based forms and data tables. During first 6 months from system deployment, we used it to archive 1471 poisoning cases, prepare monthly poisoning reports and facilitate statistical analysis of data. Electronic database usage made Poison Center work much easier.

  10. The ALS Gun Electronics system

    International Nuclear Information System (INIS)

    Lo, C.C.

    1993-05-01

    The ALS Gun Electronics system has been designed to accommodate gun with a custom made socket and high speed electronics circuit which is capable of producing single and multiple electron bunches with time jitters measured at better than 50 PS. The system generates the gated RF signal at ground level before sending it up to the 120 KV-biased gun deck via a fiber optic cable. The current pulse width as a function of grid bias, using an Eimac 8847A planar triode simulating an electron gun, was measured to show the relationship between the two parameters

  11. Kondo lattice model: Unitary transformations, spin dynamics, strongly correlated charged modes, and vacuum instability

    OpenAIRE

    Prats, J. M.; Lopez-Aguilar, F.

    1996-01-01

    Using unitary transformations, we express the Kondo lattice Hamiltonian in terms of fermionic operators that annihilate the ground state of the interacting system and that represent the best possible approximations to the actual charged excitations. In this way, we obtain an effective Hamiltonian which, for small couplings, consists in a kinetic term for conduction electrons and holes, an RKKY-like term, and a renormalized Kondo interaction. The physical picture of the system implied by this ...

  12. Thermal Phase Transitions of Strongly Correlated Bosons with Spin-Orbit Coupling

    Science.gov (United States)

    Hickey, Ciarán; Paramekanti, Arun

    2014-12-01

    Experiments on ultracold atoms have started to explore lattice effects and thermal fluctuations for two-component bosons with spin-orbit coupling (SOC). Motivated by this, we derive and study a t J model for lattice bosons with equal Rashba-Dresselhaus SOC and strong Hubbard repulsion in a uniform Zeeman magnetic field. Using the Gutzwiller ansatz, we find strongly correlated ground states with stripe superfluid (SF) order. We formulate a finite temperature generalization of the Gutzwiller method, and show that thermal fluctuations in the doped Mott insulator drive a two-step melting of the stripe SF, revealing a wide regime of a stripe normal fluid.

  13. A Portable Electron Radiography System

    CERN Document Server

    Merrill, Frank E; Harmon, Frank; Hunt, Alan W; King, B J; Morris, Christopher

    2005-01-01

    The technique of charged particle radiography has been developed and proven with 800 MeV protons at LANSCE and 24 GeV protons at the AGS. Recent work at Los Alamos National Laboratory in collaboration with the Idaho Accelerator Center has extended this diagnostic technique to electron radiography through the development of an inexpensive and portable electron radiography system. This system has been designed to use 30 MeV electrons to radiograph thin static and dynamic systems. The system consists of a compact 30 MeV pulsed electron linear accelerator coupled to a quadrupole lens magnifier constructed from permanent magnet quadrupoles. The design features and operational characteristics of this radiography system are presented as well as the radiographic performance parameters.

  14. Vessel Electronic Reporting System (VERS)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The VERS system is composed of a database and other related applications which facilitate the reporting of electronically collected research data via Fisheries...

  15. Strong correlation between early stage atherosclerosis and electromechanical coupling of aorta

    Science.gov (United States)

    Liu, X. Y.; Yan, F.; Niu, L. L.; Chen, Q. N.; Zheng, H. R.; Li, J. Y.

    2016-03-01

    Atherosclerosis is the underlying cause of cardiovascular diseases that are responsible for many deaths in the world, and the early diagnosis of atherosclerosis is highly desirable. The existing imaging methods, however, are not capable of detecting the early stage of atherosclerosis development due to their limited spatial resolution. Using piezoresponse force microscopy (PFM), we show that the piezoelectric response of an aortic wall increases as atherosclerosis advances, while the stiffness of the aorta shows a less evident correlation with atherosclerosis. Furthermore, we show that there is strong correlation between the coercive electric field necessary to switch the polarity of the artery and the development of atherosclerosis. Thus by measuring the electromechanical coupling of the aortic wall, it is possible to probe atherosclerosis at the early stage of its development, not only improving the spatial resolution by orders of magnitude, but also providing comprehensive quantitative information on the biomechanical properties of the artery.

  16. Strongly correlated impurity band superconductivity in diamond: X-ray spectroscopic evidence

    Directory of Open Access Journals (Sweden)

    G. Baskaran

    2006-01-01

    Full Text Available In a recent X-ray absorption study in boron doped diamond, Nakamura et al. have seen a well isolated narrow boron impurity band in non-superconducting samples and an additional narrow band at the chemical potential in a superconducting sample. We interpret the beautiful spectra as evidence for upper Hubbard band of a Mott insulating impurity band and an additional metallic 'mid-gap band' of a conducting 'self-doped' Mott insulator. This supports the basic framework of a recent theory of the present author of strongly correlated impurity band superconductivity (impurity band resonating valence bond, IBRVB theory in a template of a wide-gap insulator, with no direct involvement of valence band states.

  17. Lattice anharmonicity and thermal properties of strongly correlated Fe1- x Co x Si alloys

    Science.gov (United States)

    Povzner, A. A.; Nogovitsyna, T. A.; Filanovich, A. N.

    2015-10-01

    The temperature dependences of the thermal and elastic properties of strongly correlated metal alloys Fe1- x Co x Si ( x = 0.1, 0.3, 0.5) with different atomic chiralities have been calculated in the framework of the self-consistent thermodynamic model taking into account the influence of lattice anharmonicity. The lattice contributions to the heat capacity and thermal expansion coefficient of the alloys have been determined using the experimental data. It has been demonstrated that the invar effect in the thermal expansion of the lattice observed in the magnetically ordered region of Fe0.7Co0.3Si and Fe0.5Co0.5Si is not related to the lattice anharmonicity, even though its appearance correlates with variations in the atomic chirality.

  18. Component reliability for electronic systems

    CERN Document Server

    Bajenescu, Titu-Marius I

    2010-01-01

    The main reason for the premature breakdown of today's electronic products (computers, cars, tools, appliances, etc.) is the failure of the components used to build these products. Today professionals are looking for effective ways to minimize the degradation of electronic components to help ensure longer-lasting, more technically sound products and systems. This practical book offers engineers specific guidance on how to design more reliable components and build more reliable electronic systems. Professionals learn how to optimize a virtual component prototype, accurately monitor product reliability during the entire production process, and add the burn-in and selection procedures that are the most appropriate for the intended applications. Moreover, the book helps system designers ensure that all components are correctly applied, margins are adequate, wear-out failure modes are prevented during the expected duration of life, and system interfaces cannot lead to failure.

  19. Fundamentals of electronic systems design

    CERN Document Server

    Lienig, Jens

    2017-01-01

    This textbook covers the design of electronic systems from the ground up, from drawing and CAD essentials to recycling requirements. Chapter by chapter, it deals with the challenges any modern system designer faces: the design process and its fundamentals, such as technical drawings and CAD, electronic system levels, assembly and packaging issues and appliance protection classes, reliability analysis, thermal management and cooling, electromagnetic compatibility (EMC), all the way to recycling requirements and environmental-friendly design principles. Enables readers to face various challenges of designing electronic systems, including coverage from various engineering disciplines; Written to be accessible to readers of varying backgrounds; Uses illustrations extensively to reinforce fundamental concepts; Organized to follow essential design process, although chapters are self-contained and can be read in any order.

  20. Analytical purpose electron backscattering system

    International Nuclear Information System (INIS)

    Desdin, L.; Padron, I.; Laria, J.

    1996-01-01

    In this work an analytical purposes electron backscattering system improved at the Center of Applied Studies for Nuclear Development is described. This system can be applied for fast, exact and nondestructive testing of binary and AL/Cu, AL/Ni in alloys and for other applications

  1. Phase transition study in strongly correlated VO{sub 2} based sensing systems

    Energy Technology Data Exchange (ETDEWEB)

    Simo, A., E-mail: alinesimo.aline@gmail.com [UNESCO-UNISA Africa Chair in Nanoscience’s/Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape Province (South Africa); Kaviyarasu, K. [UNESCO-UNISA Africa Chair in Nanoscience’s/Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape Province (South Africa); Mwakikunga, B. [Council for Scientific and Industrial Research, P.O. Box 395, Pretoria 0001 (South Africa); Madjoe, R. [Physics Department, University of Western Cape, 7535 Belville Cape Town (South Africa); Gibaud, A. [Laboratoire de Physique de l’Etat Condensé, Université du Maine Faculte des sciences, UPRESA 6087, 72085, Le Mans Cedex 9 (France); Maaza, M. [UNESCO-UNISA Africa Chair in Nanoscience’s/Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape Province (South Africa)

    2017-04-15

    Highlights: • At 230 °C for about 48 h to prepare successfully VO{sub 2} nanobelts. • 1D shows good sensing performance due to the large active surface of the material. • The good selectivity of methanol compared to acetone and isopropanol. • VOC compounds was observed at room temperature. - Abstract: Intermediate phase monoclinic M2 was observed by inducing in situ X-ray thermo diffraction on VO{sub 2} (M) nanoplatelets. The solid-solid phase transition occurs at around 65 °C assisted with the percolative transition metal-insulator. The existence of an intermediate crystalline phase with room temperature insulator phase and high temperature metallic phase across MIT in VO{sub 2} could be of relevance to understand structural contributions to the phase transition dynamics. In addition, pellet of VO{sub 2} nanostructures have shown to present good sensing properties to various alcohols vapors at room temperature and good selectivity of methanol with 5.54% sensitivity and limit detection below 5 ppm, compared to isopropanol 3.2% and acetone 2.4% respectively.

  2. Portable digital electronic radiography system

    International Nuclear Information System (INIS)

    Sawicka, B.D.

    1995-01-01

    Radiography is a standard nondestructive technique in the industrial testing of materials and components. It is routinely used during the construction, maintenance and repair of nuclear plants. Traditionally, radiography is performed using photographic film (film radiography, FR). Recent developments in solid-state area imaging radiation detectors, miniature electronics and computer software/hardware techniques have brought electronic alternatives to FR. In recent years various electronic radiography (ER) techniques have served as alternatives to FR, these proved beneficial in some applications. While originally developed to provide real time imaging, ER may offer other advantages over FR, depending on the application. Work was undertaken at CRL to review progress in ER techniques and evaluate the possibility of constructing a portable DER (digital electronic radiography) system, for the inspection of power plant components. A suitable DER technique has been developed and a proof of principle portable system constructed. As this paper demonstrates, a properly designed ER system can be small and compact, while providing radiographic examination with acceptable image quality and the benefits of ER imaging. The CRL DER system can operate with radioactive sources typical of FR. While it does not replace FR, our DER system is expected to be beneficial in specific applications for Candu maintenance, reducing cost, labour and time. Practical, cost saving applications of this system are expected to include valve monitoring and foreign object location during maintenance at Candu reactors

  3. Damping at positive frequencies in the limit J⊥-->0 in the strongly correlated Hubbard model

    Science.gov (United States)

    Mohan, Minette M.

    1992-08-01

    I show damping in the two-dimensional strongly correlated Hubbard model within the retraceable-path approximation, using an expansion around dominant poles for the self-energy. The damping half-width ~J2/3z occurs only at positive frequencies ω>5/2Jz, the excitation energy of a pure ``string'' state of length one, where Jz is the Ising part of the superexchange interaction, and occurs even in the absence of spin-flip terms ~J⊥ in contrast to other theoretical treatments. The dispersion relation for both damped and undamped peaks near the upper band edge is found and is shown to have lost the simple J2/3z dependence characteristic of the peaks near the lower band edge. The position of the first three peaks near the upper band edge agrees well with numerical simulations on the t-J model. The weight of the undamped peaks near the upper band edge is ~J4/3z, contrasting with Jz for the weight near the lower band edge.

  4. Variation in Rural African Gut Microbiota Is Strongly Correlated with Colonization by Entamoeba and Subsistence

    Science.gov (United States)

    Morton, Elise R.; Lynch, Joshua; Froment, Alain; Lafosse, Sophie; Heyer, Evelyne; Przeworski, Molly; Blekhman, Ran; Ségurel, Laure

    2015-01-01

    The human gut microbiota is impacted by host nutrition and health status and therefore represents a potentially adaptive phenotype influenced by metabolic and immune constraints. Previous studies contrasting rural populations in developing countries to urban industrialized ones have shown that industrialization is strongly correlated with patterns in human gut microbiota; however, we know little about the relative contribution of factors such as climate, diet, medicine, hygiene practices, host genetics, and parasitism. Here, we focus on fine-scale comparisons of African rural populations in order to (i) contrast the gut microbiota of populations inhabiting similar environments but having different traditional subsistence modes and either shared or distinct genetic ancestry, and (ii) examine the relationship between gut parasites and bacterial communities. Characterizing the fecal microbiota of Pygmy hunter-gatherers as well as Bantu individuals from both farming and fishing populations in Southwest Cameroon, we found that the gut parasite Entamoeba is significantly correlated with microbiome composition and diversity. We show that across populations, colonization by this protozoa can be predicted with 79% accuracy based on the composition of an individual's gut microbiota, and that several of the taxa most important for distinguishing Entamoeba absence or presence are signature taxa for autoimmune disorders. We also found gut communities to vary significantly with subsistence mode, notably with some taxa previously shown to be enriched in other hunter-gatherers groups (in Tanzania and Peru) also discriminating hunter-gatherers from neighboring farming or fishing populations in Cameroon. PMID:26619199

  5. Record statistics of a strongly correlated time series: random walks and Lévy flights

    Science.gov (United States)

    Godrèche, Claude; Majumdar, Satya N.; Schehr, Grégory

    2017-08-01

    We review recent advances on the record statistics of strongly correlated time series, whose entries denote the positions of a random walk or a Lévy flight on a line. After a brief survey of the theory of records for independent and identically distributed random variables, we focus on random walks. During the last few years, it was indeed realized that random walks are a very useful ‘laboratory’ to test the effects of correlations on the record statistics. We start with the simple one-dimensional random walk with symmetric jumps (both continuous and discrete) and discuss in detail the statistics of the number of records, as well as of the ages of the records, i.e. the lapses of time between two successive record breaking events. Then we review the results that were obtained for a wide variety of random walk models, including random walks with a linear drift, continuous time random walks, constrained random walks (like the random walk bridge) and the case of multiple independent random walkers. Finally, we discuss further observables related to records, like the record increments, as well as some questions raised by physical applications of record statistics, like the effects of measurement error and noise.

  6. Variation in Rural African Gut Microbiota Is Strongly Correlated with Colonization by Entamoeba and Subsistence.

    Science.gov (United States)

    Morton, Elise R; Lynch, Joshua; Froment, Alain; Lafosse, Sophie; Heyer, Evelyne; Przeworski, Molly; Blekhman, Ran; Ségurel, Laure

    2015-11-01

    The human gut microbiota is impacted by host nutrition and health status and therefore represents a potentially adaptive phenotype influenced by metabolic and immune constraints. Previous studies contrasting rural populations in developing countries to urban industrialized ones have shown that industrialization is strongly correlated with patterns in human gut microbiota; however, we know little about the relative contribution of factors such as climate, diet, medicine, hygiene practices, host genetics, and parasitism. Here, we focus on fine-scale comparisons of African rural populations in order to (i) contrast the gut microbiota of populations inhabiting similar environments but having different traditional subsistence modes and either shared or distinct genetic ancestry, and (ii) examine the relationship between gut parasites and bacterial communities. Characterizing the fecal microbiota of Pygmy hunter-gatherers as well as Bantu individuals from both farming and fishing populations in Southwest Cameroon, we found that the gut parasite Entamoeba is significantly correlated with microbiome composition and diversity. We show that across populations, colonization by this protozoa can be predicted with 79% accuracy based on the composition of an individual's gut microbiota, and that several of the taxa most important for distinguishing Entamoeba absence or presence are signature taxa for autoimmune disorders. We also found gut communities to vary significantly with subsistence mode, notably with some taxa previously shown to be enriched in other hunter-gatherers groups (in Tanzania and Peru) also discriminating hunter-gatherers from neighboring farming or fishing populations in Cameroon.

  7. Generative electronic background music system

    International Nuclear Information System (INIS)

    Mazurowski, Lukasz

    2015-01-01

    In this short paper-extended abstract the new approach to generation of electronic background music has been presented. The Generative Electronic Background Music System (GEBMS) has been located between other related approaches within the musical algorithm positioning framework proposed by Woller et al. The music composition process is performed by a number of mini-models parameterized by further described properties. The mini-models generate fragments of musical patterns used in output composition. Musical pattern and output generation are controlled by container for the mini-models - a host-model. General mechanism has been presented including the example of the synthesized output compositions

  8. Generative electronic background music system

    Energy Technology Data Exchange (ETDEWEB)

    Mazurowski, Lukasz [Faculty of Computer Science, West Pomeranian University of Technology in Szczecin, Zolnierska Street 49, Szczecin, PL (Poland)

    2015-03-10

    In this short paper-extended abstract the new approach to generation of electronic background music has been presented. The Generative Electronic Background Music System (GEBMS) has been located between other related approaches within the musical algorithm positioning framework proposed by Woller et al. The music composition process is performed by a number of mini-models parameterized by further described properties. The mini-models generate fragments of musical patterns used in output composition. Musical pattern and output generation are controlled by container for the mini-models - a host-model. General mechanism has been presented including the example of the synthesized output compositions.

  9. Decal electronics for printed high performance cmos electronic systems

    KAUST Repository

    Hussain, Muhammad Mustafa

    2017-11-23

    High performance complementary metal oxide semiconductor (CMOS) electronics are critical for any full-fledged electronic system. However, state-of-the-art CMOS electronics are rigid and bulky making them unusable for flexible electronic applications. While there exist bulk material reduction methods to flex them, such thinned CMOS electronics are fragile and vulnerable to handling for high throughput manufacturing. Here, we show a fusion of a CMOS technology compatible fabrication process for flexible CMOS electronics, with inkjet and conductive cellulose based interconnects, followed by additive manufacturing (i.e. 3D printing based packaging) and finally roll-to-roll printing of packaged decal electronics (thin film transistors based circuit components and sensors) focusing on printed high performance flexible electronic systems. This work provides the most pragmatic route for packaged flexible electronic systems for wide ranging applications.

  10. Electron-electron attraction in an engineered electromechanical system

    Science.gov (United States)

    Széchenyi, Gábor; Pályi, András; Droth, Matthias

    2017-12-01

    Two electrons in a quantum dot repel each other: their interaction can be characterized by a positive interaction energy. From the theory of superconductivity, we also know that mechanical vibrations of the crystal lattice can make the electron-electron interaction attractive. Analogously, if a quantum dot interacts with a mechanical degree of freedom, the effective interaction energy can be negative; that is, the electron-electron interaction might be attractive. In this work, we propose and theoretically study an engineered electromechanical system that exhibits electron-electron attraction: a quantum dot suspended on a nonlinear mechanical resonator, tuned by a bottom and a top gate electrode. We focus on the example of a dot embedded in a suspended graphene ribbon, for which we identify conditions for electron-electron attraction. Our results suggest the possibility of electronic transport via tunneling of packets of multiple electrons in such devices, similar to that in superconducting nanostructures, but without the use of any superconducting elements.

  11. Computational time-resolved and resonant x-ray scattering of strongly correlated materials

    Energy Technology Data Exchange (ETDEWEB)

    Bansil, Arun [Northeastern Univ., Boston, MA (United States)

    2016-11-09

    Basic-Energy Sciences of the Department of Energy (BES/DOE) has made large investments in x-ray sources in the U.S. (NSLS-II, LCLS, NGLS, ALS, APS) as powerful enabling tools for opening up unprecedented new opportunities for exploring properties of matter at various length and time scales. The coming online of the pulsed photon source, literally allows us to see and follow the dynamics of processes in materials at their natural timescales. There is an urgent need therefore to develop theoretical methodologies and computational models for understanding how x-rays interact with matter and the related spectroscopies of materials. The present project addressed aspects of this grand challenge of x-ray science. In particular, our Collaborative Research Team (CRT) focused on developing viable computational schemes for modeling x-ray scattering and photoemission spectra of strongly correlated materials in the time-domain. The vast arsenal of formal/numerical techniques and approaches encompassed by the members of our CRT were brought to bear through appropriate generalizations and extensions to model the pumped state and the dynamics of this non-equilibrium state, and how it can be probed via x-ray absorption (XAS), emission (XES), resonant and non-resonant x-ray scattering, and photoemission processes. We explored the conceptual connections between the time-domain problems and other second-order spectroscopies, such as resonant inelastic x-ray scattering (RIXS) because RIXS may be effectively thought of as a pump-probe experiment in which the incoming photon acts as the pump, and the fluorescent decay is the probe. Alternatively, when the core-valence interactions are strong, one can view K-edge RIXS for example, as the dynamic response of the material to the transient presence of a strong core-hole potential. Unlike an actual pump-probe experiment, here there is no mechanism for adjusting the time-delay between the pump and the probe. However, the core hole

  12. Electronic Nicotine Delivery Systems Key Facts Infographic

    Data.gov (United States)

    U.S. Department of Health & Human Services — Explore the Electronic Nicotine Delivery Systems Key Facts Infographic which outlines key facts related to electronic nicotine delivery systems (ENDS), including...

  13. Various scenarios of metal-insulator transition in strongly correlated materials

    Czech Academy of Sciences Publication Activity Database

    Kuneš, Jan; Anisimov, V.I.

    2011-01-01

    Roč. 523, 8-9 (2011), 682-688 ISSN 0003-3804 R&D Projects: GA ČR GAP204/10/0284 Institutional research plan: CEZ:AV0Z10100521 Keywords : electronic correlations * metal-insulator transition * dynamical mean-field theory Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.841, year: 2011

  14. Fermionic Statistics in the Strongly Correlated Limit of Density Functional Theory

    Science.gov (United States)

    2017-01-01

    Exact pieces of information on the adiabatic connection integrand, Wλ[ρ], which allows evaluation of the exchange-correlation energy of Kohn–Sham density functional theory, can be extracted from the leading terms in the strong coupling limit (λ → ∞, where λ is the strength of the electron–electron interaction). In this work, we first compare the theoretical prediction for the two leading terms in the strong coupling limit with data obtained via numerical implementation of the exact Levy functional in the simple case of two electrons confined in one dimension, confirming the asymptotic exactness of these two terms. We then carry out a first study on the incorporation of the Fermionic statistics at large coupling λ, both numerical and theoretical, confirming that spin effects enter at orders ∼e–√λ. PMID:29111724

  15. Modeling of power electronic systems with EMTP

    Science.gov (United States)

    Tam, Kwa-Sur; Dravid, Narayan V.

    1989-01-01

    In view of the potential impact of power electronics on power systems, there is need for a computer modeling/analysis tool to perform simulation studies on power systems with power electronic components as well as to educate engineering students about such systems. The modeling of the major power electronic components of the NASA Space Station Freedom Electric Power System is described along with ElectroMagnetic Transients Program (EMTP) and it is demonstrated that EMTP can serve as a very useful tool for teaching, design, analysis, and research in the area of power systems with power electronic components. EMTP modeling of power electronic circuits is described and simulation results are presented.

  16. Lattice and electronic properties of strongly correlated PuCoGa5 based on first principles calculations and thermodynamic modelling

    Science.gov (United States)

    Filanovich, A. N.; Povzner, A. A.

    2017-12-01

    In the framework of density functional theory method, the ground state energy of the PuCoGa5 compound is calculated for different values of the unit cell volume. The obtained data were incorporated into the thermodynamic model, which was utilized to calculate the temperature dependencies of thermal and elastic properties of PuCoGa5. The parameters of the developed model were estimated based on data of ab initio phonon spectrum. The Gruneisen parameters, which characterize degree of anharmonicity of the acoustic and optical phonons, are obtained. Using experimental data, non-lattice contributions to the coefficient of thermal expansion and heat capacity are determined. The nature of observed anomalies of the properties of PuCoGa5 is discussed, in particular, the possibility of a valence phase transition.

  17. Rare earth monopnictides and monochalcogenides from first principles: towards an electronic phase diagram of strongly correlated materials

    DEFF Research Database (Denmark)

    Petit, Leon; Tyer, R.; Szotek, Z.

    2010-01-01

    -throughput computing made possible by the increasing available computational power. Our findings, including the predicted 'intermediate valent' compounds SmO and TmSe, are in excellent overall agreement with the available experimental data. The accuracy of the approach, proven e.g. through the lattice parameters...... calculated to within ~1.5% of the experimental values, and its ability to describe localization phenomena in solids, makes it a competitive atomistic simulation approach in the search for and design of new materials with specific physical properties and possible technological applications....

  18. Oxygen x-ray emission and absorption spectra as a probe of the electronic structure of strongly correlated oxides

    Czech Academy of Sciences Publication Activity Database

    Kurmaev, E.Z.; Wilks, R.G.; Moewes, A.; Finkelstein, L.D.; Shamin, S.N.; Kuneš, Jan

    2008-01-01

    Roč. 77, č. 16 (2008), 165127/1-165127/5 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10100521 Keywords : transition metal oxides * x-ray spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.322, year: 2008

  19. Quantum criticality and emergence of the T/B scaling in strongly correlated metals

    International Nuclear Information System (INIS)

    Watanabe, Shinji; Miyake, Kazumasa

    2016-01-01

    A new type of scaling observed in heavy-electron metal β-YbAlB 4 , where the magnetic susceptibility is expressed as a single scaling function of the ratio of temperature T and magnetic field B over four decades, is examined theoretically. We develop the mode-coupling theory for critical Yb-valence fluctuations under a magnetic field, verifying that the T/B scaling behavior appears near the QCP of the valence transition. Emergence of the T/B scaling indicates the presence of the small characteristic temperature of the critical Yb-valence fluctuation due to the strong local correlation effect. It is discussed that the T/B scaling as well as the unconventional criticality is explained from the viewpoint of the quantum valence criticality in a unified way.

  20. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    electronic converter systems; anomaly detection and remaining-life prediction for power electronics; reliability of DC-link capacitors in power electronic converters; reliability of power electronics packaging; modeling for life-time prediction of power semiconductor modules; minimization of DC......-tolerant adjustable speed drive systems; mission profile oriented reliability design in wind turbine and photovoltaic systems; reliability of power conversion systems in photovoltaic applications; power supplies for computers; and high-power converters. Reliability of Power Electronic Converter Systems is essential......The main aims of power electronic converter systems (PECS) are to control, convert, and condition electrical power flow from one form to another through the use of solid-state electronics. This book outlines current research into the scientific modeling, experimentation, and remedial measures...

  1. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    for advancing the reliability, availability, system robustness, and maintainability of PECS at different levels of complexity. Drawing on the experience of an international team of experts, this book explores the reliability of PECS covering topics including an introduction to reliability engineering in power...... electronic converter systems; anomaly detection and remaining-life prediction for power electronics; reliability of DC-link capacitors in power electronic converters; reliability of power electronics packaging; modeling for life-time prediction of power semiconductor modules; minimization of DC......-link capacitance in power electronic converter systems; wind turbine systems; smart control strategies for improved reliability of power electronics system; lifetime modelling; power module lifetime test and state monitoring; tools for performance and reliability analysis of power electronics systems; fault...

  2. Cognitive systems in electronic warfare

    Science.gov (United States)

    Kulpa, Krzysztof; Szczepankiewicz, Michał; Żywek, Marcin; Malanowski, Mateusz; Misiurewicz, Jacek; Samczyński, Piotr

    2017-04-01

    Electronic warfare (EW) techniques were invented 70 years ago and are still being developed, all the time with a key role played by their operators. However, a human operator responds far too slowly for the on-going needs since to be adequate to current threats the EW system reaction should be within 1 ms or less. Too slow reaction defers an achievement of the objectives, and generally may lead to disclosure of the applied strategy and to waste of resources. Developing the adequate response to the threat is a multifaceted matter that requires considerable experience and knowledge on the one hand, and thorough observation of outcomes of the applied strategy on the other hand. Such action requires the use of not only intelligence but also more complex algorithms for automatic control than the classical ones, and it heavily builds on the experience. It is therefore a cognitive task in its nature, and a human operator acts naturally this way. Consequently, a proper training and experience gained are what really matters. As a result of tests and actions in EW the operator builds his own knowledge base, thus, gains a capability of responding to the known threats in a balanced way. New threats, however, are much more challenging since they should be handled as fast as possible but in a fresh and creative manner. To this end, adapting the algorithms of radar jamming protection for the new conditions of the battlefield is an example of such challenging tasks. At present, such adjustments are done in a long feedback loop when the operator, after recognizing the problem, notifies the equipment manufacturers, and then, their engineers work on required solutions accordingly. Thus, the reaction time is counted in years, not a single milliseconds or seconds. Speeding up the response time is therefore the key issue, and a solution to it would be feasible only when cognitive systems were used. A concept of such cognitive system is presented in this paper.

  3. Electronic chip cooling system using graphite fins

    OpenAIRE

    Xue , Dong; Wu , Long; Xun , Lian

    2017-01-01

    International audience; As electronic devices get smaller, cooling systems with higher thermal efficiency is demanding by fast growing electronic industry. Great amount of research has been performed on the cooling systems but research on the materials of the cooling systems needs more work. Graphite with high thermal conductivity and light weight is a great candidate to be used in electronic devices. The bottleneck of using graphene in the cooling systems is the thermal transport among the i...

  4. Strongly correlated bosons on optical superlattices: Dynamics and relaxation in the superfluid and insulating regimes

    Science.gov (United States)

    Rigol, Marcos; Olshanii, Maxim; Muramatsu, Alejandro

    2007-03-01

    We study the nonequilibrium dynamics of hard-core bosons (HCB's) on one-dimensional lattices. The dynamics is analyzed after a sudden switch-on or switch-off of a superlattice potential, which can bring the system into insulating or superfluid phases, respectively. A collapse and revival of the zero-momentum peak can be seen in the first case. We study in detail the relaxation of these integrable systems towards equilibrium. We show that after relaxation time averages of physical observables, like the momentum distribution function, can be predicted by means of a generalization of the Gibbs distribution. [M. Rigol, A. Muramatsu, and M. Olshanii, Phys. Rev. A 74, 053616 (2006).

  5. Inelastic light scattering to probe strongly correlated bosons in optical lattices

    International Nuclear Information System (INIS)

    Fort, Chiara; Fabbri, Nicole; Fallani, Leonardo; Clement, David; Inguscio, Massimo

    2011-01-01

    We have used inelastic light scattering to study correlated phases of an array of one-dimensional interacting Bose gases. In the linear response regime, the observed spectra are proportional to the dynamic structure factor. In particular we have investigated the superfluid to Mott insulator crossover loading the one-dimensional gases in an optical lattice and monitoring the appearance of an energy gap due to finite particle-hole excitation energy. We attribute the low frequency side of the spectra to the presence of some superfluid and normal phase fraction between the Mott insulator regions with different fillings produced in the inhomogeneous systems. In the Mott phase we also investigated excitations to higher excited bands of the optical lattice, the spectra obtained in this case being connected to the single particle spectral function. In one-dimensional systems the effect of thermal fluctuations and interactions is enhanced by the reduced dimensionality showing up in the dynamic structure factor. We measured the dynamic structure factor of an array of one-dimensional bosonic gases pointing out the effect of temperature-induced phase fluctuations in reducing the coherence length of the system.

  6. Integrated control system for electron beam processes

    Science.gov (United States)

    Koleva, L.; Koleva, E.; Batchkova, I.; Mladenov, G.

    2018-03-01

    The ISO/IEC 62264 standard is widely used for integration of the business systems of a manufacturer with the corresponding manufacturing control systems based on hierarchical equipment models, functional data and manufacturing operations activity models. In order to achieve the integration of control systems, formal object communication models must be developed, together with manufacturing operations activity models, which coordinate the integration between different levels of control. In this article, the development of integrated control system for electron beam welding process is presented as part of a fully integrated control system of an electron beam plant, including also other additional processes: surface modification, electron beam evaporation, selective melting and electron beam diagnostics.

  7. Generalized virial theorem and pressure relation for a strongly correlated Fermi gas

    International Nuclear Information System (INIS)

    Tan, Shina

    2008-01-01

    For a two-component Fermi gas in the unitarity limit (i.e., with infinite scattering length), there is a well-known virial theorem, first shown by J.E. Thomas et al. A few people rederived this result, and extended it to few-body systems, but their results are all restricted to the unitarity limit. Here I show that there is a generalized virial theorem for FINITE scattering lengths. I also generalize an exact result concerning the pressure to the case of imbalanced populations

  8. Anomalous spin disordered properties of strongly correlated honeycomb compound In3Cu2VO9

    Directory of Open Access Journals (Sweden)

    Shi-Qing Jia

    2017-05-01

    Full Text Available We study the ground-state and finite-temperature magnetic properties of an interlayer frustrated J1 − J2 − Jc Heisenberg model on three-dimensional honeycomb lattice by employing the Schwinger boson mean-field theory, focusing on the low-energy physics in In3Cu2VO9. We find that with the increase of interlayer coupling Jc from 0 to 3.6 meV, the interlayer frustrated system transits from an antiferromagnetic (AFM phase to a state with intralayer AFM order and interlayer disorder. This spin disordered phase explains not only the intralayer phase transition at TN = 38 K, but also the qualitative behaviors of the intermediate-temperature specific heat and magnetic susceptibility of In3Cu2VO9.

  9. Strongly correlated one-dimensional Bose–Fermi quantum mixtures: symmetry and correlations

    Science.gov (United States)

    Decamp, Jean; Jünemann, Johannes; Albert, Mathias; Rizzi, Matteo; Minguzzi, Anna; Vignolo, Patrizia

    2017-12-01

    We consider multi-component quantum mixtures (bosonic, fermionic, or mixed) with strongly repulsive contact interactions in a one-dimensional harmonic trap. In the limit of infinitely strong repulsion and zero temperature, using the class-sum method, we study the symmetries of the spatial wave function of the mixture. We find that the ground state of the system has the most symmetric spatial wave function allowed by the type of mixture. This provides an example of the generalized Lieb–Mattis theorem. Furthermore, we show that the symmetry properties of the mixture are embedded in the large-momentum tails of the momentum distribution, which we evaluate both at infinite repulsion by an exact solution and at finite interactions using a numerical DMRG approach. This implies that an experimental measurement of the Tan’s contact would allow to unambiguously determine the symmetry of any kind of multi-component mixture.

  10. Metastability and avalanche dynamics in strongly correlated gases with long-range interactions

    Science.gov (United States)

    Hruby, Lorenz; Dogra, Nishant; Landini, Manuele; Donner, Tobias; Esslinger, Tilman

    2018-03-01

    We experimentally study the stability of a bosonic Mott insulator against the formation of a density wave induced by long-range interactions and characterize the intrinsic dynamics between these two states. The Mott insulator is created in a quantum degenerate gas of 87-Rubidium atoms, trapped in a 3D optical lattice. The gas is located inside and globally coupled to an optical cavity. This causes interactions of global range, mediated by photons dispersively scattered between a transverse lattice and the cavity. The scattering comes with an atomic density modulation, which is measured by the photon flux leaking from the cavity. We initialize the system in a Mott-insulating state and then rapidly increase the global coupling strength. We observe that the system falls into either of two distinct final states. One is characterized by a low photon flux, signaling a Mott insulator, and the other is characterized by a high photon flux, which we associate with a density wave. Ramping the global coupling slowly, we observe a hysteresis loop between the two states—a further signature of metastability. A comparison with a theoretical model confirms that the metastability originates in the competition between short- and global-range interactions. From the increasing photon flux monitored during the switching process, we find that several thousand atoms tunnel to a neighboring site on the timescale of the single-particle dynamics. We argue that a density modulation, initially forming in the compressible surface of the trapped gas, triggers an avalanche tunneling process in the Mott-insulating region.

  11. Survey of electronic payment methods and systems

    NARCIS (Netherlands)

    Havinga, Paul J.M.; Smit, Gerardus Johannes Maria; Helme, A.; Verbraeck, A.

    1996-01-01

    In this paper an overview of electronic payment methods and systems is given. This survey is done as part of the Moby Dick project. Electronic payment systems can be grouped into three broad classes: traditional money transactions, digital currency and creditdebit payments. Such payment systems have

  12. Quantifying electron transfer reactions in biological systems

    DEFF Research Database (Denmark)

    Sjulstok, Emil Sjulstok; Olsen, Jógvan Magnus Haugaard; Solov'yov, Ilia A

    2015-01-01

    to deduce the driving force for the electron transfer reaction and to establish those interactions that play the major role in propelling the electron. The suggested approach is seen as a general recipe to treat electron transfer events in biological systems computationally, and we utilize it to describe...

  13. Simulation of strongly correlated fermions in two spatial dimensions with fermionic projected entangled-pair states

    Science.gov (United States)

    Corboz, Philippe; Orús, Román; Bauer, Bela; Vidal, Guifré

    2010-04-01

    We explain how to implement, in the context of projected entangled-pair states (PEPSs), the general procedure of fermionization of a tensor network introduced in P. Corboz and G. Vidal, Phys. Rev. B 80, 165129 (2009). The resulting fermionic PEPS, similar to previous proposals, can be used to study the ground state of interacting fermions on a two-dimensional lattice. As in the bosonic case, the cost of simulations depends on the amount of entanglement in the ground state and not directly on the strength of interactions. The present formulation of fermionic PEPS leads to a straightforward numerical implementation that allowed us to recycle much of the code for bosonic PEPS. We demonstrate that fermionic PEPS are a useful variational ansatz for interacting fermion systems by computing approximations to the ground state of several models on an infinite lattice. For a model of interacting spinless fermions, ground state energies lower than Hartree-Fock results are obtained, shifting the boundary between the metal and charge-density wave phases. For the t-J model, energies comparable with those of a specialized Gutzwiller-projected ansatz are also obtained.

  14. Electronic Official Personnel Folder System

    Data.gov (United States)

    US Agency for International Development — The eOPF is a digital recreation of paper personnel folder that stores electronic personnel data spanning an individual's Federal career. eOPF allows employees to...

  15. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    for advancing the reliability, availability, system robustness, and maintainability of PECS at different levels of complexity. Drawing on the experience of an international team of experts, this book explores the reliability of PECS covering topics including an introduction to reliability engineering in power......-tolerant adjustable speed drive systems; mission profile oriented reliability design in wind turbine and photovoltaic systems; reliability of power conversion systems in photovoltaic applications; power supplies for computers; and high-power converters. Reliability of Power Electronic Converter Systems is essential...... reading for researchers, professionals and students working with power electronics and their applications, particularly those specializing in the development and application of power electronic converters and systems....

  16. A simple electron-beam lithography system

    DEFF Research Database (Denmark)

    Mølhave, Kristian; Madsen, Dorte Nørgaard; Bøggild, Peter

    2005-01-01

    A large number of applications of electron-beam lithography (EBL) systems in nanotechnology have been demonstrated in recent years. In this paper we present a simple and general-purpose EBL system constructed by insertion of an electrostatic deflector plate system at the electron-beam exit...... of the column of a scanning electron microscope (SEM). The system can easily be mounted on most standard SEM systems. The tested setup allows an area of up to about 50 x 50 pm to be scanned, if the upper limit for acceptable reduction of the SEM resolution is set to 10 run. We demonstrate how the EBL system can...

  17. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    The main aims of power electronic converter systems (PECS) are to control, convert, and condition electrical power flow from one form to another through the use of solid-state electronics. This book outlines current research into the scientific modeling, experimentation, and remedial measures......-link capacitance in power electronic converter systems; wind turbine systems; smart control strategies for improved reliability of power electronics system; lifetime modelling; power module lifetime test and state monitoring; tools for performance and reliability analysis of power electronics systems; fault...... for advancing the reliability, availability, system robustness, and maintainability of PECS at different levels of complexity. Drawing on the experience of an international team of experts, this book explores the reliability of PECS covering topics including an introduction to reliability engineering in power...

  18. Implementing an electronic patient handover system.

    Science.gov (United States)

    Oakley, Ben; Hunter, James B

    2017-01-02

    Clear communication among health-care teams is paramount for safe patient care and effective handover. Advances in information technology have led to an increased use of electronic systems within modern health care. This quality improvement project introduced an electronic patient handover system that was intended to improve the accuracy of patient handover lists and be readily available to all members of the health-care team. A quality improvement project was undertaken to assess the effect of introducing an electronic patient handover system on maintenance workload and list accuracy. List errors were common before the introduction of the electronic patient handover system, commonly patient location or a patient being incorrectly omitted from the list. These errors decreased significantly after the introduction of the electronic system (Ppatients being missed on ward rounds (Pelectronic handover system was introduced. This reduced the workload associated with maintaining handover lists and the rate of errors.

  19. High perveance electron gun for the electron cooling system

    International Nuclear Information System (INIS)

    Korotaev, Yu.; Meshkov, I.; Petrov, A.; Sidorin, A.; Smirnov, A.; Syresin, E.; Titkova, I.

    2000-01-01

    The cooling time in the electron cooling system is inversely proportional to the beam current. To obtain high current of the electron beam the control electrode of the gun is provided with a positive potential and an electrostatic trap for secondary electrons appears inside the electron gun. This leads to a decrease in the gun perveance. To avoid this problem, the adiabatic high perveance electron gun with the clearing control electrode is designed in JINR (J. Bosser, Y. Korotaev, I. Meshkov, E. Syresin et al., Nucl. Instr. and Meth. A 391 (1996) 103. Yu. Korotaev, I. Meshkov, A. Sidorin, A. Smirnov, E. Syresin, The generation of electron beams with perveance of 3-6 μA/V 3/2 , Proceedings of SCHEF'99). The clearing control electrode has a transverse electric field, which clears secondary electrons. Computer simulations of the potential map were made with RELAX3D computer code (C.J. Kost, F.W. Jones, RELAX3D User's Guide and References Manual)

  20. High perveance electron gun for the electron cooling system

    CERN Document Server

    Korotaev, Yu V; Petrov, A; Sidorin, A; Smirnov, A; Syresin, E M; Titkova, I

    2000-01-01

    The cooling time in the electron cooling system is inversely proportional to the beam current. To obtain high current of the electron beam the control electrode of the gun is provided with a positive potential and an electrostatic trap for secondary electrons appears inside the electron gun. This leads to a decrease in the gun perveance. To avoid this problem, the adiabatic high perveance electron gun with the clearing control electrode is designed in JINR (J. Bosser, Y. Korotaev, I. Meshkov, E. Syresin et al., Nucl. Instr. and Meth. A 391 (1996) 103. Yu. Korotaev, I. Meshkov, A. Sidorin, A. Smirnov, E. Syresin, The generation of electron beams with perveance of 3-6 mu A/V sup 3 sup / sup 2 , Proceedings of SCHEF'99). The clearing control electrode has a transverse electric field, which clears secondary electrons. Computer simulations of the potential map were made with RELAX3D computer code (C.J. Kost, F.W. Jones, RELAX3D User's Guide and References Manual).

  1. Control system for JAERI Free Electron Laser

    International Nuclear Information System (INIS)

    Sugimoto, Masayoshi

    1992-01-01

    A control system comprising of the personal computers network and the CAMAC stations for the JAERI Free Electron Laser is designed and is in the development stage. It controls the equipment and analyzes the electron and optical beam experiments. The concept and the prototype of the control system are described. (author)

  2. Reliability of power electronic converter systems

    CERN Document Server

    Chung, Henry Shu-hung; Blaabjerg, Frede; Pecht, Michael

    2016-01-01

    This book outlines current research into the scientific modeling, experimentation, and remedial measures for advancing the reliability, availability, system robustness, and maintainability of Power Electronic Converter Systems (PECS) at different levels of complexity.

  3. Cavity Born-Oppenheimer Approximation for Correlated Electron-Nuclear-Photon Systems.

    Science.gov (United States)

    Flick, Johannes; Appel, Heiko; Ruggenthaler, Michael; Rubio, Angel

    2017-04-11

    In this work, we illustrate the recently introduced concept of the cavity Born-Oppenheimer approximation [ Flick et al. PNAS 2017 , 10.1073/pnas.1615509114 ] for correlated electron-nuclear-photon problems in detail. We demonstrate how an expansion in terms of conditional electronic and photon-nuclear wave functions accurately describes eigenstates of strongly correlated light-matter systems. For a GaAs quantum ring model in resonance with a photon mode we highlight how the ground-state electronic potential-energy surface changes the usual harmonic potential of the free photon mode to a dressed mode with a double-well structure. This change is accompanied by a splitting of the electronic ground-state density. For a model where the photon mode is in resonance with a vibrational transition, we observe in the excited-state electronic potential-energy surface a splitting from a single minimum to a double minimum. Furthermore, for a time-dependent setup, we show how the dynamics in correlated light-matter systems can be understood in terms of population transfer between potential energy surfaces. This work at the interface of quantum chemistry and quantum optics paves the way for the full ab initio description of matter-photon systems.

  4. High performance electron processing systems

    International Nuclear Information System (INIS)

    Frutiger, W.A.; Nablo, S.V.

    1984-01-01

    Many of the processes of immediate interest for commercial electron curing require large, single pass doses at high speed. The machine designer is faced with some practical upper limits to the dose rate (or electron current density) which can be used efficiently by the chemistry being initiated in the product. In addition, he must pay attention to the temperature excursions in the product due to the relatively low glass transition temperatures or softening temperatures in the substrates of interest. A new family of processors is described capable of delivering up to one megarad at 1500 meters per minute (typically 10 megarads at 150 m/minute). Product temperature excursions are controlled by the use of a shielded drum located within the processor Selfshield. Considerations of the real time diagnosis and control of these processors in production application are discussed, along with typical uniformity and penetration performance in the product

  5. A simple electron-beam lithography system

    International Nuclear Information System (INIS)

    Moelhave, Kristian; Madsen, Dorte Noergaard; Boeggild, Peter

    2005-01-01

    A large number of applications of electron-beam lithography (EBL) systems in nanotechnology have been demonstrated in recent years. In this paper we present a simple and general-purpose EBL system constructed by insertion of an electrostatic deflector plate system at the electron-beam exit of the column of a scanning electron microscope (SEM). The system can easily be mounted on most standard SEM systems. The tested setup allows an area of up to about 50x50 μm to be scanned, if the upper limit for acceptable reduction of the SEM resolution is set to 10 nm. We demonstrate how the EBL system can be used to write three-dimensional nanostructures by electron-beam deposition

  6. Corrosion Reliability of Electronic Systems

    DEFF Research Database (Denmark)

    Ambat, Rajan; Jensen, Stine G.; Møller, Per

    2008-01-01

    Inherently two factors namely multi-material usage and potential bias makes electronic devices susceptible to corrosion if exposed to humid conditions. The problem is compounded today due to miniaturization and contamination effects. The reduction in size of the components and close spacing...... on a Printed Circuit Board (PCB) for high density packing has greatly increased the risk of corrosion under humid conditions. An important issue is the failures due to electrolytic metal migration. This paper describes an investigation of the electrolytic migration of Sn-Pb solder lines on PCBs in humid...

  7. Design for Reliability of Power Electronic Systems

    DEFF Research Database (Denmark)

    Yang, Yongheng; Wang, Huai; Sangwongwanich, Ariya

    2018-01-01

    Power density, efficiency, cost, and reliability are the major challenges when designing a power electronic system. Latest advancements in power semiconductor devices (e.g., silicon carbide devices) and topological innovations have vital contributions to power density and efficiency. Nevertheless.......e., mission profiles) is usually harsh, where the input power can change quickly and randomly, resulting in considerable temperature swings in the power electronics. This may induce failures to the power electronic systems. If remain untreated (i.e., ill-designed system without considering reliability......), the cost for maintenance will increase, thus affecting the reputation for the manufacturers and, more important, the cost of energy in renewables. Hence, it calls for highly reliable power electronic systems, where the reliability together with various common design parameters should be taken into account...

  8. Electronic construction collaboration system : phase III.

    Science.gov (United States)

    2011-12-01

    This phase of the electronic collaboration project involved two major efforts: 1) implementation of AEC Sync (formerly known as Attolist), a web-based project management system (WPMS), on the Broadway Viaduct Bridge Project and the Iowa Falls Arch Br...

  9. Vacuum measuring system for channel electron multipliers

    Science.gov (United States)

    Urban, A.; Ritzinger, W.

    1982-03-01

    A system in which channel electron multipliers can be calibrated to be used as detectors of electrons or protons in space is described. The system consists of an electron gun built in a vacuum chamber and equipped with a control Faraday cup and a high impedance electrometer to measure electron fluxes. It contains an electron flux control with buffer amplifier, a proportional integration differentiation regulation unit, and a heating current power regulation. Detection efficiency dependency on the energy of the incident particles, the saturation that yields decreasing count rates at continuously increasing particle flux, or the statistical pulse height distribution giving information about well or restrictedly usuable multipliers can be measured. The optimum supply voltage of the multipliers at which small fluctuations do not cause any changes of the pulse height distribution, and the function count rates vs. supply voltage for selecting good or poor multipliers can also be determined.

  10. NMR Probe for Electrons in Semiconductor Mesoscopic Structures

    Indian Academy of Sciences (India)

    2009-11-14

    Nov 14, 2009 ... Strongly correlated electron systems: Overview. Problem: How to detect the electronic state in nanoscale structures. Two examples where the usual methods don't work. Solution: We showed NMR techniques can be very useful in such circumstances. Outline ...

  11. Magnetic system of the Tevatron electron lens

    International Nuclear Information System (INIS)

    Bogdanov, I.; Kozub, S.; Pleskach, V.; Sytnik, V.; Tkachenko, L.; Zintchenko, S.; Zubko, V.; Kuznetsov, G.; Sery, A.; Shiltsev, V.

    2000-01-01

    The Tevatron Electron Lens (TEL) system consisting of seven SC and four conventional magnets has been developed and fabricated in IHEP for increase of luminosity in Tevatron. The SC cable tension and preload of SC coils are calculated. The chosen cable design and cooling of the SC magnets ensure sufficient temperature margin for operating of SC magnets and their safety during quench. The system of conventional and SC solenoids create necessary trajectory of magnetic field lines for the TEL electron beam motion. SC dipoles and warm correctors permit to carry out correction of the electron beam motion [ru

  12. Electron correlation energy in confined two-electron systems

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, C.L. [Chemistry Program, Centre College, 600 West Walnut Street, Danville, KY 40422 (United States); Montgomery, H.E., E-mail: ed.montgomery@centre.ed [Chemistry Program, Centre College, 600 West Walnut Street, Danville, KY 40422 (United States); Sen, K.D. [School of Chemistry, University of Hyderabad, Hyderabad 500 046 (India); Thompson, D.C. [Chemistry Systems and High Performance Computing, Boehringer Ingelheim Pharamaceuticals Inc., 900 Ridgebury Road, Ridgefield, CT 06877 (United States)

    2010-09-27

    Radial, angular and total correlation energies are calculated for four two-electron systems with atomic numbers Z=0-3 confined within an impenetrable sphere of radius R. We report accurate results for the non-relativistic, restricted Hartree-Fock and radial limit energies over a range of confinement radii from 0.05-10a{sub 0}. At small R, the correlation energies approach limiting values that are independent of Z while at intermediate R, systems with Z{>=}1 exhibit a characteristic maximum in the correlation energy resulting from an increase in the angular correlation energy which is offset by a decrease in the radial correlation energy.

  13. Data base systems in electronic design engineering

    Science.gov (United States)

    Williams, D.

    1980-01-01

    The concepts of an integrated design data base system (DBMS) as it might apply to an electronic design company are discussed. Data elements of documentation, project specifications, project tracking, firmware, software, electronic and mechanical design can be integrated and managed through a single DBMS. Combining the attributes of a DBMS data handler with specialized systems and functional data can provide users with maximum flexibility, reduced redundancy, and increased overall systems performance. Although some system overhead is lost due to redundancy in transitory data, it is believed the combination of the two data types is advisable rather than trying to do all data handling through a single DBMS.

  14. Design for Reliability of Power Electronic Systems

    DEFF Research Database (Denmark)

    Wang, Huai; Ma, Ke; Blaabjerg, Frede

    2012-01-01

    Advances in power electronics enable efficient and flexible processing of electric power in the application of renewable energy sources, electric vehicles, adjustable-speed drives, etc. More and more efforts are devoted to better power electronic systems in terms of reliability to ensure high...... on a 2.3 MW wind power converter is discussed with emphasis on the reliability critical components IGBTs. Different aspects of improving the reliability of the power converter are mapped. Finally, the challenges and opportunities to achieve more reliable power electronic systems are addressed.......). A collection of methodologies based on Physics-of-Failure (PoF) approach and mission profile analysis are presented in this paper to perform reliability-oriented design of power electronic systems. The corresponding design procedures and reliability prediction models are provided. Further on, a case study...

  15. Control system in the technological electron linacs

    International Nuclear Information System (INIS)

    Boriskin, V.N.; Akchurin, Yu.I.; Bahmetev, N.N.; Gurin, V.A.

    1999-01-01

    The special system has been developed for linac control.It controls the electron beam current,the energy and the position,protects the accelerating and scanning systems from the damage caused by the beam;blocks the modulator and the klystron amplifier in the case of intolerable operating modes;regulates the phase and power of the HF signals in the injecting system and also regulates the source power currents in the magnetic system

  16. The Intelligent Technologies of Electronic Information System

    Science.gov (United States)

    Li, Xianyu

    2017-08-01

    Based upon the synopsis of system intelligence and information services, this paper puts forward the attributes and the logic structure of information service, sets forth intelligent technology framework of electronic information system, and presents a series of measures, such as optimizing business information flow, advancing data decision capability, improving information fusion precision, strengthening deep learning application and enhancing prognostic and health management, and demonstrates system operation effectiveness. This will benefit the enhancement of system intelligence.

  17. Sensor Arrays and Electronic Tongue Systems

    Directory of Open Access Journals (Sweden)

    Manel del Valle

    2012-01-01

    Full Text Available This paper describes recent work performed with electronic tongue systems utilizing electrochemical sensors. The electronic tongues concept is a new trend in sensors that uses arrays of sensors together with chemometric tools to unravel the complex information generated. Initial contributions and also the most used variant employ conventional ion selective electrodes, in which it is named potentiometric electronic tongue. The second important variant is the one that employs voltammetry for its operation. As chemometric processing tool, the use of artificial neural networks as the preferred data processing variant will be described. The use of the sensor arrays inserted in flow injection or sequential injection systems will exemplify attempts made to automate the operation of electronic tongues. Significant use of biosensors, mainly enzyme-based, to form what is already named bioelectronic tongue will be also presented. Application examples will be illustrated with selected study cases from the Sensors and Biosensors Group at the Autonomous University of Barcelona.

  18. Power Electronics in Wind Turbine Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Chen, Zhe; Teodorescu, Remus

    2006-01-01

    the conventional, fossil (and short term) based energy sources to renewable energy resources. The other is to use high efficient power electronics in power systems, power production and end-user application. This paper discuss the most emerging renewable energy source, wind energy, which by means of power...... electronics is changing from being a minor energy source to be acting as an important power source in the energy system. By that wind power is also getting an added value in the power system operation....

  19. Electron localization in one-dimensional systems

    International Nuclear Information System (INIS)

    Chao, K.A.

    1984-01-01

    The pure regional localization and the global localization have been investigated via the inverse participation ratio and te moment analysis. If the envelop function of a localized state is more complicated than the simple exponential function e sup(-r/xi), the inverse participation ratio is inadequate to describe the localization properties of an electron. This is the case discovered recently in a stereo-irregular chain fo atoms including the electron-electron interaction and the structure disorder. The localization properties in this system are analysed in terms of the moments. (Author) [pt

  20. Blind Signatures in Electronic Voting Systems

    Science.gov (United States)

    Kucharczyk, Marcin

    Electronic voting systems are created to facilitate the election, accelerate voting and counting votes and increase turnout for the election. The main problems of the electronic systems are related with the assurance of system security (cryptographic security and protection against frauds) and a guarantee that the voters are anonymous. The authorization of voters and the anonymity of them seem to be contradictory, but it is possible to create such a system where the both requirements are met. Some solutions, the most common e-voting systems, are presented in the paper. These models are adjusted to the demands and implemented in the polls system for quality of teaching evaluation where anonymity is very important. The blind signature protocol, model directed to user's anonymity, is a very good solution of the authorization and anonymity problem in the polls system with remote access only, as it was described in the paper.

  1. VHDL Model of Electronic-Lock System

    Directory of Open Access Journals (Sweden)

    J. Noga

    2000-04-01

    Full Text Available The paper describes the design of an electronic-lock system which wascompleted as part of the Basic VHDL course in the Department of Controland Measurement Faculty of Electrical Engineering and Informatics,Technical University of Ostrava, Czech Republic in co-operation withthe Department if Electronic Engineering, University of Hull, GreatBritain in the frame of TEMPUS project no. S_JEP/09468-95.

  2. Information entropies of many-electron systems

    Energy Technology Data Exchange (ETDEWEB)

    Yanez, R.J.; Angulo, J.C.; Dehesa, J.S. [Universidad de Granada (Spain)

    1995-12-05

    The Boltzmann-Shannon (BS) information entropy S{sub {rho}} = - {integral} {rho}(r)log {rho}(r) dr measures the spread or extent of the one-electron density {rho}(r), which is the basic variable of the density function theory of the many electron systems. This quantity cannot be analytically computed, not even for simple quantum mechanical systems such as, e.g., the harmonic oscillator (HO) and the hydrogen atom (HA) in arbitrary excited states. Here, we first review (i) the present knowledge and open problems in the analytical determination of the BS entropies for the HO and HA systems in both position and momentum spaces and (ii) the known rigorous lower and upper bounds to the position and momentum BS entropies of many-electron systems in terms of the radial expectation values in the corresponding space. Then, we find general inequalities which relate the BS entropies and various density functionals. Particular cases of these results are rigorous relationships of the BS entropies and some relevant density functionals (e.g., the Thomas-Fermi kinetic energy, the Dirac-Slater exchange energy, the average electron density) for finite many-electron systems. 28 refs.

  3. A Flexible Electronic Commerce Recommendation System

    Science.gov (United States)

    Gong, Songjie

    Recommendation systems have become very popular in E-commerce websites. Many of the largest commerce websites are already using recommender technologies to help their customers find products to purchase. An electronic commerce recommendation system learns from a customer and recommends products that the customer will find most valuable from among the available products. But most recommendation methods are hard-wired into the system and they support only fixed recommendations. This paper presented a framework of flexible electronic commerce recommendation system. The framework is composed by user model interface, recommendation engine, recommendation strategy model, recommendation technology group, user interest model and database interface. In the recommender strategy model, the method can be collaborative filtering, content-based filtering, mining associate rules method, knowledge-based filtering method or the mixed method. The system mapped the implementation and demand through strategy model, and the whole system would be design as standard parts to adapt to the change of the recommendation strategy.

  4. Collimation system for electron arc therapy

    International Nuclear Information System (INIS)

    Brunelli, R.J.; Carter, J.C.

    1984-01-01

    An electron collimation system for electron arc therapy treatments consists of a slit collimation system which is movable with the electron beam applicator and is designed to allow for dose compensation in the sagittal direction and a hoop-and-clamp assembly for final field shaping. By correctly designing the shape of the slit in the former and properly adjusting the components of the latter, it is possible to accomplish quite uniform shielding without causing any weight of the shielding material to rest on the patient. The slit collimation system has a specially shaped aperture for confining the radiation beam. The hoop-and-clamp assembly has hoops and clamps which locate shielding over the patient's body. The shielding locating clamps are adjustably movable radially with respect to the hoops. (author)

  5. Electronic instrumentation system for pulsed neutron measurements

    International Nuclear Information System (INIS)

    Burda, J.; Igielski, A.; Kowalik, W.

    1982-01-01

    An essential point of pulsed neutron measurement of thermal neutron parameters for different materials is the registration of the thermal neutron die-away curve after a fast neutron bursts have been injected into the system. An electronic instrumentation system which is successfully applied for pulsed neutron measurements is presented. An important part of the system is the control unit which has been designed and built in the Laboratory of Neutron Parameters of Materials. (author)

  6. Electronic Resources Management System: Recommendation Report 2017

    KAUST Repository

    Ramli, Rindra M.

    2017-05-01

    This recommendation report provides an overview of the selection process for the new Electronic Resources Management System. The library has decided to move away from Innovative Interfaces Millennium ERM module. The library reviewed 3 system as potential replacements namely: Proquest 360 Resource Manager, Ex Libris Alma and Open Source CORAL ERMS. After comparing and trialling the systems, it was decided to go for Proquest 360 Resource Manager.

  7. The second generation of electronic blasting systems

    Energy Technology Data Exchange (ETDEWEB)

    Hammelmann, F.; Petzold, J. [Dynamit Nobel GmbH (Germany)

    2001-07-01

    8 years after the market introduction of the first commercial electronic detonator - DYNATRONIC - the paper describes a new area of electronic blasting systems Made in Germany: i-kon. The results of a joint development between Dynamit Nobel and Orica is a unique universal electronic detonator, which is as simple to use as a standard non-electric detonator. The delay time or delay interval is not factory preprogrammed and the system is not based on a numbered system like conventional detonators. The miner or Blaster decides on site which delay timing he likes to use and is programming the whole blast on site. The new i-kon system allows delay times between 0 and 8000 ms by increments of 1 ms. With the control equipment it is possible to blast up to 1600 detonators in a single blast. The paper describes the construction and functionality of this new electronic blasting system - manufactured and developed by Precision Blasting Systems, a joint venture between Orica and Dynamic Nobel. (orig.)

  8. Power Electronics for Renewable Energy Systems

    DEFF Research Database (Denmark)

    Choi, U. M.; Lee, K. B.; Blaabjerg, Frede

    2012-01-01

    The use of renewable energy sources are increased because of the depletion of natural resources and the increasing pollution level from energy production. The wind energy and the solar energy are most widely used among the renewable energy sources. Power electronics is needed in almost all kinds...... of renewable energy system. It controls the renewable source and interfaces with the load effectively, which can be grid-connected or van work in stand-alone mode. In this presentation, overview of wind and photovoltaic energy systems are introduced. Next, the power electronic circuits behind the most common...

  9. Method of fabricating a cooled electronic system

    Science.gov (United States)

    Chainer, Timothy J; Gaynes, Michael A; Graybill, David P; Iyengar, Madhusudan K; Kamath, Vinod; Kochuparambil, Bejoy J; Schmidt, Roger R; Schultz, Mark D; Simco, Daniel P; Steinke, Mark E

    2014-02-11

    A method of fabricating a liquid-cooled electronic system is provided which includes an electronic assembly having an electronics card and a socket with a latch at one end. The latch facilitates securing of the card within the socket. The method includes providing a liquid-cooled cold rail at the one end of the socket, and a thermal spreader to couple the electronics card to the cold rail. The thermal spreader includes first and second thermal transfer plates coupled to first and second surfaces on opposite sides of the card, and thermally conductive extensions extending from end edges of the plates, which couple the respective transfer plates to the liquid-cooled cold rail. The extensions are disposed to the sides of the latch, and the card is securable within or removable from the socket using the latch without removing the cold rail or the thermal spreader.

  10. Automatic control variac system for electronic accelerator

    International Nuclear Information System (INIS)

    Zhang Shuocheng; Wang Dan; Jing Lan; Qiao Weimin; Ma Yunhai

    2006-01-01

    An automatic control variac system is designed in order to satisfy the controlling requirement of the electronic accelerator developed by the Institute. Both design and operational principles, structure of the system as well as the software of industrial PC and micro controller unit are described. The interfaces of the control module are RS232 and RS485. A fiber optical interface (FOC) could be set up if an industrial FOC network is necessary, which will extend the filed of its application and make the communication of the system better. It is shown in practice that the system can adjust the variac output voltage automatically and assure the accurate and automatic control of the electronic accelerator. The system is designed in accordance with the general design principles and possesses the merits such as easy operation and maintenance, good expansibility, and low cost, thus it could also be used in other industrial branches. (authors)

  11. [Theoretical studies of dynamics and correlations in heavy electron materials:]: Progress report, August 15, 1987-August 15, 1988

    International Nuclear Information System (INIS)

    1988-01-01

    This paper discusses progress in heavy electron research and high temperature superconductivity research. Particular topics discussed are: quadrupolar Kondo effect; coherence in the Anderson Lattice; Hall effect in heavy electron systems, suppression of supeconductivity by disorder in strongly correlated electronic materials; and charge transfer mechanisms for high temperature superconductivity

  12. Electronic warfare receivers and receiving systems

    CERN Document Server

    Poisel, Richard A

    2014-01-01

    Receivers systems are considered the core of electronic warfare (EW) intercept systems. Without them, the fundamental purpose of such systems is null and void. This book considers the major elements that make up receiver systems and the receivers that go in them.This resource provides system design engineers with techniques for design and development of EW receivers for modern modulations (spread spectrum) in addition to receivers for older, common modulation formats. Each major module in these receivers is considered in detail. Design information is included as well as performance tradeoffs o

  13. ELECTRONIC PAYMENT SYSTEM AND ITS PROTECTION

    Directory of Open Access Journals (Sweden)

    Miroslav Milutinovic

    2015-01-01

    Full Text Available All developed countries are in transition from the IT economy to a web economy - the biggest technological innovation that will have a long-term positive effect on the formation of the economic growth rate, the major structural changes and on the differentiated effects on the economic areas that are, at a faster or a slower rate, being included in this technological change. The electronic commerce or e-commerce has a huge potential for development. The electronic commerce between the companies (B-2-B is significantly greater compared to retail electronic commerce (B-2-C. In both spheres of trade, the Internet is used as a platform for the transfer of information and for concluding business deals. Market economy requires Accelerated Payment Processing which is achieved by introducing and improving the electronic payment procedures. There is an emphasized dichotomy between the two spheres of the payment system: large-value and small-value payments. The large value payment systems can be described as the arteries of the payment system, and the small-value transfer systems as a complex network of veins that bind the entire economy.

  14. Accounting Systems and the Electronic Office.

    Science.gov (United States)

    Gafney, Leo

    1986-01-01

    Discusses a systems approach to accounting instruction and examines it from the viewpoint of four components: people (titles and responsibilities, importance of interaction), forms (nonpaper records such as microfiche, floppy disks, hard disks), procedures (for example, electronic funds transfer), and technology (for example, electronic…

  15. Electronic Subsystems For Laser Communication System

    Science.gov (United States)

    Long, Catherine; Maruschak, John; Patschke, Robert; Powers, Michael

    1992-01-01

    Electronic subsystems of free-space laser communication system carry digital signals at 650 Mb/s over long distances. Applicable to general optical communications involving transfer of great quantities of data, and transmission and reception of video images of high definition.

  16. Radiation from systems with relativistic electrons

    International Nuclear Information System (INIS)

    Ternov, I.M.; Khalilov, V.R.; Bagrov, V.G.; Nikitin, M.M.

    1980-01-01

    Different methods of generation of electromagnetic radiation in the course of electron motion in external electromagnetic fields are considered. Singularities of ''free electron lasers'' (FEL), synchrotronous, ondulator and Compton radiation sources are discussed. The effect of induced radiation of electrons moving in a magnetic field is studied on the basis of the quantum theory methods. The results obtained are compared with the results of the classical theory. The theoretical and experimental results of the main singularities of the ondulator radiation (OR) are presented. It is shown that when the recoil effects are negligible and nonequidistancy of the energy spectrum of an electron in a magnetic field is of an error character, the results for the dose rate calculated by the quantum and classical theory methods completely coincide in the range of great filling numbers. Both in the quantum and classical theories the effects of the induced radiation of electrons moving in external electromagnetic fields (nonstationary in a general case) of a rather general type depend on two main mechanisms, which are nonequidistancy of the energy spectrum and the recoil effect (the quantum theory); appearance of phase and longitudinal electron bunching under the effect of an alternating radiation field (the classical theory). On the basis of the investigations the conclusion is made that OR can be successfully used for measuring the charged particle beam parameters (dispersion of angular spread and the absolute energy), as well as for measuring the amplitude of the magnetic field intensity in a space-periodic system

  17. The DIAMANT electronics and data acquisition system

    Science.gov (United States)

    Aïche, M.; Aléonard, M. M.; Balauge, B.; Barreau, G.; Bourgine, F.; Cabaussel, D.; Chemin, J. F.; Diarra, C.; Goudour, J. P.; Harston, M.; Rasolofo, H.; Scheurer, J. N.; Brondi, A.; La Rana, G.; Moro, R.; Moro, R.; Vardaci, E.; Curien, D.

    1997-02-01

    We describe the electronics and data acquisition system of the 4π light particle multidetector array DIAMANT. This system has been conceived to be very modular with regard to both the kind and number of detectors. The whole system is designed to run either with a few additional ancillary detectors (Ge) or linked to 4π γ arrays such as EUROGAM. Part of the electronics has been designed using SMD devices; the acquisition is based on CAMAC ADCs and VME units for data acquisition, data transfer is handled via a 32 bit ECL bus (DT32) used for EUROGAM. The data acquisition, distributed on a network, is based on the VxWorks Real Time kernel and the UNIX Operating System.

  18. Epidermal electronic systems for sensing and therapy

    Science.gov (United States)

    Lu, Nanshu; Ameri, Shideh K.; Ha, Taewoo; Nicolini, Luke; Stier, Andrew; Wang, Pulin

    2017-04-01

    Epidermal electronic system is a class of hair thin, skin soft, stretchable sensors and electronics capable of continuous and long-term physiological sensing and clinical therapy when applied on human skin. The high cost of manpower, materials, and photolithographic facilities associated with its manufacture limit the availability of disposable epidermal electronics. We have invented a cost and time effective, completely dry, benchtop "cut-and-paste" method for the green, freeform and portable manufacture of epidermal electronics within minutes. We have applied the "cut-and-paste" method to manufacture epidermal electrodes, hydration and temperature sensors, conformable power-efficient heaters, as well as cuffless continuous blood pressure monitors out of metal thin films, two-dimensional (2D) materials, and piezoelectric polymer sheets. For demonstration purpose, we will discuss three examples of "cut-and-pasted" epidermal electronic systems in this paper. The first will be submicron thick, transparent epidermal graphene electrodes that can be directly transferred to human skin like a temporary transfer tattoo and can measure electrocardiogram (ECG) with signal-to-noise ratio and motion artifacts on par with conventional gel electrodes. The second will be a chest patch which houses both electrodes and pressure sensors for the synchronous measurements of ECG and seismocardiogram (SCG) such that beat-to-beat blood pressure can be inferred from the time interval between the R peak of the ECG and the AC peak of the SCG. The last example will be a highly conformable, low power consumption epidermal heater for thermal therapy.

  19. Soft errors in modern electronic systems

    CERN Document Server

    Nicolaidis, Michael

    2010-01-01

    This book provides a comprehensive presentation of the most advanced research results and technological developments enabling understanding, qualifying and mitigating the soft errors effect in advanced electronics, including the fundamental physical mechanisms of radiation induced soft errors, the various steps that lead to a system failure, the modelling and simulation of soft error at various levels (including physical, electrical, netlist, event driven, RTL, and system level modelling and simulation), hardware fault injection, accelerated radiation testing and natural environment testing, s

  20. Electron dynamics inside short-coherence systems

    International Nuclear Information System (INIS)

    Ferrari, Giulio; Bordone, Paolo; Jacoboni, Carlo

    2006-01-01

    We present theoretical results on electron dynamics inside nanometric systems, where the coherence of the electron ensemble is maintained in a very short region. The contacts are supposed to spoil such a coherence, therefore the interference processes between the carrier wavefunction and the internal potential profile can be affected by the proximity of the contacts. The problem has been analysed by using the Wigner-function formalism. For very short devices, transport properties, such as tunnelling through potential barriers, are significantly influenced by the distance between the contacts

  1. The electron-neutrino system, ch. 3

    International Nuclear Information System (INIS)

    Kox, A.J.

    1976-01-01

    Relativistic kinetic gas theory is applied to a mixture of electrons and electronic neutrinos. The phenomena of diffusion are especially studied in this system, assuming properties comparable to those of the universe in the lepton era as assumed in the hot big bang theory: a hot (Tapproximately 10 12 K), dense (n = 10 38 ) mixture, colliding elastically. An expression for the diffusion coefficient is derived and numerical values are computed as a function of the reduced temperature z -1 = kT/mc 2 , assuming equal number densities

  2. Electron correlations in narrow band systems

    International Nuclear Information System (INIS)

    Kishore, R.

    1983-01-01

    The effect of the electron correlations in narrow bands, such as d(f) bands in the transition (rare earth) metals and their compounds and the impurity bands in doped semiconductors is studied. The narrow band systems is described, by the Hubbard Hamiltonian. By proposing a local self-energy for the interacting electron, it is found that the results are exact in both atomic and band limits and reduce to the Hartree Fock results for U/Δ → 0, where U is the intra-atomic Coulomb interaction and Δ is the bandwidth of the noninteracting electrons. For the Lorentzian form of the density of states of the noninteracting electrons, this approximation turns out to be equivalent to the third Hubbard approximation. A simple argument, based on the mean free path obtained from the imaginary part of the self energy, shows how the electron correlations can give rise to a discontinous metal-nonmetal transition as proposed by Mott. The band narrowing and the existence of the satellite below the Fermi energy in Ni, found in photoemission experiments, can also be understood. (Author) [pt

  3. System for Cooling of Electronic Components

    Science.gov (United States)

    Vasil'ev, L. L.; Grakovich, L. P.; Dragun, L. A.; Zhuravlev, A. S.; Olekhnovich, V. A.; Rabetskii, M. I.

    2017-01-01

    Results of computational and experimental investigations of heat pipes having a predetermined thermal resistance and a system based on these pipes for air cooling of electronic components and diode assemblies of lasers are presented. An efficient compact cooling system comprising heat pipes with an evaporator having a capillary coating of a caked copper powder and a condenser having a developed outer finning, has been deviced. This system makes it possible to remove, to the ambient air, a heat flow of power more than 300 W at a temperature of 40-50°C.

  4. Zope based electronic operation log system - Zlog

    International Nuclear Information System (INIS)

    Yoshii, K.; Satoh, Y.; Kitabayashi, T.

    2004-01-01

    Since January 2004, the Zope based electronic operation logging system, named Zlog, has been running at the KEKB and AR accelerator facilities. Since Zope is the python based open source web application server software and python language is familiar for the members in the KEKB accelerator control group, we have developed the Zlog system rapidly. In this paper, we report the development history and the present status of Zlog system. Also we show some general plug-in components, called Zope products, have been useful for our Zlog development. (author)

  5. Decal Electronics: Printable Packaged with 3D Printing High-Performance Flexible CMOS Electronic Systems

    KAUST Repository

    Sevilla, Galo T.

    2016-10-14

    High-performance complementary metal oxide semiconductor electronics are flexed, packaged using 3D printing as decal electronics, and then printed in roll-to-roll fashion for highly manufacturable printed flexible high-performance electronic systems.

  6. Electronic Document Management Using Inverted Files System

    Directory of Open Access Journals (Sweden)

    Suhartono Derwin

    2014-03-01

    Full Text Available The amount of documents increases so fast. Those documents exist not only in a paper based but also in an electronic based. It can be seen from the data sample taken by the SpringerLink publisher in 2010, which showed an increase in the number of digital document collections from 2003 to mid of 2010. Then, how to manage them well becomes an important need. This paper describes a new method in managing documents called as inverted files system. Related with the electronic based document, the inverted files system will closely used in term of its usage to document so that it can be searched over the Internet using the Search Engine. It can improve document search mechanism and document save mechanism.

  7. Facilitating Adoption of an Electronic Documentation System.

    Science.gov (United States)

    Jones, Nazarine T; Seckman, Charlotte

    2018-01-12

    Best practice recommends the integration of clinical documentation into the hospital electronic health record to support safe, efficient, and timely patient care. A major barrier to successful adoption and optimization of computerized documentation systems is user satisfaction. The purpose of this descriptive, performance improvement initiative was to implement and evaluate user satisfaction with an electronic documentation system to facilitate successful adoption. The Clinical Procedure Flowsheets application was implemented in a geriatric extended care unit of a large healthcare system. Rogers' Diffusion of Innovation and Davis' Technology Acceptance Model were used to guide system adoption and improve user experience of the innovation. The Perceived Usefulness and Perceived Ease of Use questionnaire was distributed to 24 nursing staff working in the unit 9 weeks after implementation. Results indicated that respondents perceived the Clinical Procedure Flowsheets as easy to use and useful in accomplishing their documentation tasks. The overall mean satisfaction score of 72.17 (SD, 12.13) implied a strong level of user acceptance. The positive perception of the nursing staff in the geriatric extended care unit suggests a high probability of system use that can enhance the documentation of patient care. Further research is recommended to evaluate factors related to system adoption and user satisfaction.

  8. Advanced electronics for the CTF MEG system.

    Science.gov (United States)

    McCubbin, J; Vrba, J; Spear, P; McKenzie, D; Willis, R; Loewen, R; Robinson, S E; Fife, A A

    2004-11-30

    Development of the CTF MEG system has been advanced with the introduction of a computer processing cluster between the data acquisition electronics and the host computer. The advent of fast processors, memory, and network interfaces has made this innovation feasible for large data streams at high sampling rates. We have implemented tasks including anti-alias filter, sample rate decimation, higher gradient balancing, crosstalk correction, and optional filters with a cluster consisting of 4 dual Intel Xeon processors operating on up to 275 channel MEG systems at 12 kHz sample rate. The architecture is expandable with additional processors to implement advanced processing tasks which may include e.g., continuous head localization/motion correction, optional display filters, coherence calculations, or real time synthetic channels (via beamformer). We also describe an electronics configuration upgrade to provide operator console access to the peripheral interface features such as analog signal and trigger I/O. This allows remote location of the acoustically noisy electronics cabinet and fitting of the cabinet with doors for improved EMI shielding. Finally, we present the latest performance results available for the CTF 275 channel MEG system including an unshielded SEF (median nerve electrical stimulation) measurement enhanced by application of an adaptive beamformer technique (SAM) which allows recognition of the nominal 20-ms response in the unaveraged signal.

  9. Effects of electron-electron interactions on electronic transport in disordered systems

    International Nuclear Information System (INIS)

    Foley, Simon Timothy

    2002-01-01

    This thesis is concerned with the role of electron-electron interactions on electronic transport in disordered systems. We first consider a novel non-linear sigma model in order to microscopically treat the effects of disorder and electronic interaction. We successfully reproduce the perturbative results for the zero-bias anomaly and the interaction correction to the conductivity in a weakly disordered system, and discuss possible directions for future work. Secondly we consider the fluctuations of the dephasing rate for a closed diffusive and quantum dot system. Using the Keldysh technique we derive an expression for the inelastic scattering rate with which we self-consistently obtain the fluctuations in the dephasing rate. For the diffusive regime we find the relative fluctuations is given by F ∼ (L φ /L) 2 /g 2 , where g is the dimensionless conductance, L φ is the dephasing length and L is the sample size. For the quantum dot regime we find a perturbative divergence due to the presence of the zero mode. By mapping divergent diagrams to those for the two-level correlation function, we conjecture the existence of an exact relation between the two. Finally we discuss the consequences of this relation. (author)

  10. Development of HF-systems for electron storage systems

    International Nuclear Information System (INIS)

    Androsov, V.P.; Karnaukhov, I.M.; Popkov, Yu.P.; Reva, S.N.; Telegin, Yu.N.

    1999-01-01

    Development of HF systems for electron storages is described. Its final task is construction of 100 kW HF station at 699,3 MHz frequency consisting from low-power HF system, klystron amplifier, wave line for HF power transmission and accelerating section. Functional parameters of HF station are given

  11. Dynamically programmable electronic pill dispenser system.

    Science.gov (United States)

    Boquete, Luciano; Rodriguez-Ascariz, Jose Manuel; Artacho, Irene; Cantos-Frontela, Joaquin; Peixoto, Nathalia

    2010-06-01

    Compliance in medicine dispensation has proven critical for dosage control, diagnosis, and treatment. We have designed, manufactured, and characterized a novel dynamically programmable e-pill dispensing system. Our system is initially programmed remotely through a cell phone. After programming, the system may be reconfigured in order to adapt pill dispensation to new conditions. In this paper we describe the mechanics, electronics, control, and communication protocols implemented. Our dyn-e-pill devices can be actuated for over 350 h with two pill retrievals per hour. We challenged the charging circuit and demonstrated that the system has a lifetime longer than 6 h with a 30 min charging cycle, while it lasts for 14 h of uninterrupted use with a full charge.

  12. Electronic system for Langmuir probe measurements

    Science.gov (United States)

    Mitov, M.; Bankova, A.; Dimitrova, M.; Ivanova, P.; Tutulkov, K.; Djermanova, N.; Dejarnac, R.; Stöckel, J.; Popov, Tsv K.

    2012-03-01

    A newly developed Langmuir probe system for measurements of current-voltage (IV) characteristics in the tokamak divertor area is presented and discussed. The system is partially controlled by a computer allowing simultaneous and independent feeding and registration of signals. The system is mounted in the COMPASS tokamak, Institute of Plasma Physics, Academy of Sciences of the Czech Republic. The new electronic circuit boards include also active low-pass filters which smooth the signal before recording by the data acquisition system (DAQ). The signal is thus less noisy and the data processing is much easier. We also designed and built a microcontroller-driven waveform generator with resolution of 1 Ms/s. The power supply is linear and uses a transformer. We avoided the use of a switching power supply because of the noise that it could generate. Examples of measurements of the IV characteristics by divertor probes in the COMPASS tokamak and evaluation of the EEDF are presented.

  13. Electronic integrated disease surveillance system and pathogen asset control system.

    Science.gov (United States)

    Wahl, Tom G; Burdakov, Aleksey V; Oukharov, Andrey O; Zhilokov, Azamat K

    2012-06-20

    Electronic Integrated Disease Surveillance System (EIDSS) has been used to strengthen and support monitoring and prevention of dangerous diseases within One Health concept by integrating veterinary and human surveillance, passive and active approaches, case-based records including disease-specific clinical data based on standardised case definitions and aggregated data, laboratory data including sample tracking linked to each case and event with test results and epidemiological investigations. Information was collected and shared in secure way by different means: through the distributed nodes which are continuously synchronised amongst each other, through the web service, through the handheld devices. Electronic Integrated Disease Surveillance System provided near real time information flow that has been then disseminated to the appropriate organisations in a timely manner. It has been used for comprehensive analysis and visualisation capabilities including real time mapping of case events as these unfold enhancing decision making. Electronic Integrated Disease Surveillance System facilitated countries to comply with the IHR 2005 requirements through a data transfer module reporting diseases electronically to the World Health Organisation (WHO) data center as well as establish authorised data exchange with other electronic system using Open Architecture approach. Pathogen Asset Control System (PACS) has been used for accounting, management and control of biological agent stocks. Information on samples and strains of any kind throughout their entire lifecycle has been tracked in a comprehensive and flexible solution PACS.Both systems have been used in a combination and individually. Electronic Integrated Disease Surveillance System and PACS are currently deployed in the Republics of Kazakhstan, Georgia and Azerbaijan as a part of the Cooperative Biological Engagement Program (CBEP) sponsored by the US Defense Threat Reduction Agency (DTRA).

  14. Electronic Integrated Disease Surveillance System and Pathogen Asset Control System

    Directory of Open Access Journals (Sweden)

    Tom G. Wahl

    2012-06-01

    Full Text Available Electronic Integrated Disease Surveillance System (EIDSS has been used to strengthen and support monitoring and prevention of dangerous diseases within One Health concept by integrating veterinary and human surveillance, passive and active approaches, case-based records including disease-specific clinical data based on standardised case definitions and aggregated data, laboratory data including sample tracking linked to each case and event with test results and epidemiological investigations. Information was collected and shared in secure way by different means: through the distributed nodes which are continuously synchronised amongst each other, through the web service, through the handheld devices. Electronic Integrated Disease Surveillance System provided near real time information flow that has been then disseminated to the appropriate organisations in a timely manner. It has been used for comprehensive analysis and visualisation capabilities including real time mapping of case events as these unfold enhancing decision making. Electronic Integrated Disease Surveillance System facilitated countries to comply with the IHR 2005 requirements through a data transfer module reporting diseases electronically to the World Health Organisation (WHO data center as well as establish authorised data exchange with other electronic system using Open Architecture approach. Pathogen Asset Control System (PACS has been used for accounting, management and control of biological agent stocks. Information on samples and strains of any kind throughout their entire lifecycle has been tracked in a comprehensive and flexible solution PACS. Both systems have been used in a combination and individually. Electronic Integrated Disease Surveillance System and PACS are currently deployed in the Republics of Kazakhstan, Georgia and Azerbaijan as a part of the Cooperative Biological Engagement Program (CBEP sponsored by the US Defense Threat Reduction Agency (DTRA.

  15. Fisher information of two-electron systems

    Science.gov (United States)

    Saha, Aparna; Talukdar, Benoy; Sarkar, Pranab

    2018-01-01

    We present a theoretical model to compute numbers for position- and momentum-space Fisher information ( I_{ρ} and I_{γ} of correlated two-electron systems. The numbers for the first five members of the helium iso-electronic sequence indicate that i) values of I_{ρ} increase with the atomic number Z while those of I_{γ} decrease, and, ii) the effect of correlation reduces (increases) the bare values of I_{ρ}(I_{γ}) . The observed behavior of Fisher information in i) and ii) is opposite to that exhibited by Shannon information entropy, presumably because in describing disorder in the probability distribution, the former is convex while the latter is concave. The information measures of Fisher and of Shannon have also been found to share some common properties, the origin of which is purely physical rather than statistical.

  16. New Electron Gun System for BEPCII

    CERN Document Server

    Liu, Bo; Long Chi, Yun; Zhang, Chuang

    2005-01-01

    The new electron gun system for BEPCII has been put into operation since Nov. 2004. The article describes the design, experiment and operation of this new system. The design current of the gun is 10 A for the pulse lengths of 1 ns, 2.5 ns and 1 μs with repetition rate of 50 Hz. The gun is operated with a pulsed high voltage power supply which can provide up to 200 kV high voltage. Computer simulations have been carried out in the design stage, including simulation of the gun geometry and beam transportation. Some important relation curves are obtained during the experiment. Two-bunch operation is available and some elementary tests have been performed. New scheme of the gun control system based on EPICS is also presented. The real operation shows that the design and manufacturing is basically successful.

  17. Electronic journal management systems experiences from the field

    CERN Document Server

    Ives, Gary W

    2013-01-01

    Discover how to manage your library's electronic journals?with tips from those who've already met the challenge!The explosive growth of electronic journals presents unique challenges for libraries. Electronic Journal Management Systems: Experiences from the Field comprehensively examines these complex topics, including explanations of the automated systems libraries have developed or adopted, licensing issues, and the provision of access to electronic journals. Respected library professionals discuss their own experiences in the implementation and use of electronic journal management systems,

  18. Controlling Underwater Robots with Electronic Nervous Systems

    Directory of Open Access Journals (Sweden)

    Joseph Ayers

    2010-01-01

    Full Text Available We are developing robot controllers based on biomimetic design principles. The goal is to realise the adaptive capabilities of the animal models in natural environments. We report feasibility studies of a hybrid architecture that instantiates a command and coordinating level with computed discrete-time map-based (DTM neuronal networks and the central pattern generators with analogue VLSI (Very Large Scale Integration electronic neuron (aVLSI networks. DTM networks are realised using neurons based on a 1-D or 2-D Map with two additional parameters that define silent, spiking and bursting regimes. Electronic neurons (ENs based on Hindmarsh–Rose (HR dynamics can be instantiated in analogue VLSI and exhibit similar behaviour to those based on discrete components. We have constructed locomotor central pattern generators (CPGs with aVLSI networks that can be modulated to select different behaviours on the basis of selective command input. The two technologies can be fused by interfacing the signals from the DTM circuits directly to the aVLSI CPGs. Using DTMs, we have been able to simulate complex sensory fusion for rheotaxic behaviour based on both hydrodynamic and optical flow senses. We will illustrate aspects of controllers for ambulatory biomimetic robots. These studies indicate that it is feasible to fabricate an electronic nervous system controller integrating both aVLSI CPGs and layered DTM exteroceptive reflexes.

  19. Electronic resource management systems a workflow approach

    CERN Document Server

    Anderson, Elsa K

    2014-01-01

    To get to the bottom of a successful approach to Electronic Resource Management (ERM), Anderson interviewed staff at 11 institutions about their ERM implementations. Among her conclusions, presented in this issue of Library Technology Reports, is that grasping the intricacies of your workflow-analyzing each step to reveal the gaps and problems-at the beginning is crucial to selecting and implementing an ERM. Whether the system will be used to fill a gap, aggregate critical data, or replace a tedious manual process, the best solution for your library depends on factors such as your current soft

  20. Structural dynamics of electronic and photonic systems

    CERN Document Server

    Suhir, Ephraim; Steinberg, David S

    2011-01-01

    The proposed book will offer comprehensive and versatile methodologies and recommendations on how to determine dynamic characteristics of typical micro- and opto-electronic structural elements (printed circuit boards, solder joints, heavy devices, etc.) and how to design a viable and reliable structure that would be able to withstand high-level dynamic loading. Particular attention will be given to portable devices and systems designed for operation in harsh environments (such as automotive, aerospace, military, etc.)  In-depth discussion from a mechanical engineer's viewpoint will be conducte

  1. Electron correlation and relativity of the 5f electrons in the U-Zr alloy system

    Science.gov (United States)

    Söderlind, P.; Sadigh, B.; Lordi, V.; Landa, A.; Turchi, P. E. A.

    2014-01-01

    coefficient (αL) at room temperature gives us confidence that the quasi-harmonic model is reasonable. The thermal volume expansion shown in the figure further demonstrates (i) that at room temperature α-U has nearly identical volume to Mo-stabilized γ-U (extrapolated to zero Mo content) at the same temperature [23]; and (ii) at about 1100 K the calculated α-U volume is consistent with that measured [23] for the γ phase. Hence, the difference between α and γ volumes is completely explained by thermal expansion with no need for additional f-electron localization. This conclusion is further underscored by a recent study [24] showing that the γ-phase mechanical stabilization is due to phonon-phonon interactions within a weakly correlated picture (DFT) of the electronic structure.Nevertheless, we apply FPLAPW (PAW) calculations for γ-uranium using the Wien2K (VASP) codes in order to explicitly explore the effects of LSDA + U. The results from the two implementations are in qualitative agreement with each other and summarized in Table 1. They predict a metastable non-magnetic (non-spin polarized, NSP) solution, that yield equilibrium V and B in better agreement with experiment than the spin polarized (SP) solution. The spin polarized LSDA + U ground-state solution (ferromagnetic, spin moment = 2.1 μB) has an unrealistically large equilibrium volume of 23 (23.6) Å3/atom, and substantially underestimates the bulk modulus. The total energy difference between the SP and the NSP states, at their respective equilibrium volumes, is a significant 64 (110) meV/atom. The finding of magnetism is contrary to the observed non-magnetic state of uranium metal. We thus conclude that the LSDA + U treatment, while essential for some aspects (i.e. electronic spectra) of the strongly correlated insulating uranium oxide compounds, is detrimental and incorrect for the more weakly correlated metallic U-Zr alloys.In conclusion we find that while the calculations by Landa et al. [2] can be

  2. Wigner-like crystallization of Anderson-localized electron systems with low electron densities

    CERN Document Server

    Slutskin, A A; Pepper, M

    2002-01-01

    We consider an electron system under conditions of strong Anderson localization, taking into account interelectron long-range Coulomb repulsion. We establish that at sufficiently low electron densities and sufficiently low temperatures the Coulomb electron interaction brings about ordering of the Anderson-localized electrons into a structure that is close to an ideal (Wigner) crystal lattice, provided the dimension of the system is > 1. This Anderson-Wigner glass (AWG) is a new macroscopic electron state that, on the one hand, is beyond the conventional Fermi glass concept, and on the other hand, qualitatively differs from the known 'plain' Wigner glass (inherent in self-localized electron systems) in that the random slight electron displacements from the ideal crystal sites essentially depend on the electron density. With increasing electron density the AWG is found to turn into the plain Wigner glass or Fermi glass, depending on the width of the random spread of the electron levels. It is shown that the res...

  3. Complexity in electronic negotiation support systems.

    Science.gov (United States)

    Griessmair, Michele; Strunk, Guido; Vetschera, Rudolf; Koeszegi, Sabine T

    2011-10-01

    It is generally acknowledged that the medium influences the way we communicate and negotiation research directs considerable attention to the impact of different electronic communication modes on the negotiation process and outcomes. Complexity theories offer models and methods that allow the investigation of how pattern and temporal sequences unfold over time in negotiation interactions. By focusing on the dynamic and interactive quality of negotiations as well as the information, choice, and uncertainty contained in the negotiation process, the complexity perspective addresses several issues of central interest in classical negotiation research. In the present study we compare the complexity of the negotiation communication process among synchronous and asynchronous negotiations (IM vs. e-mail) as well as an electronic negotiation support system including a decision support system (DSS). For this purpose, transcripts of 145 negotiations have been coded and analyzed with the Shannon entropy and the grammar complexity. Our results show that negotiating asynchronically via e-mail as well as including a DSS significantly reduces the complexity of the negotiation process. Furthermore, a reduction of the complexity increases the probability of reaching an agreement.

  4. Radiation Risks and Mitigation in Electronic Systems

    CERN Document Server

    Todd, B

    2015-01-01

    Electrical and electronic systems can be disturbed by radiation-induced effects. In some cases, radiation-induced effects are of a low probability and can be ignored; however, radiation effects must be considered when designing systems that have a high mean time to failure requirement, an impact on protection, and/or higher exposure to radiat ion. High-energy physics power systems suffer from a combination of these effects: a high mean time to failure is required, failure can impact on protection, and the proximity of systems to accelerators increases the likelihood of radiation-induced events. This paper presents the principal radiation-induced effects, and radiation environments typical to high-energy physics. It outlines a procedure for designing and validating radiation-tolerant systems using commercial off-the-shelf components. The paper ends with a worked example of radiation-tolerant power converter controls that are being developed for the Large Hadron Collider and High Luminosity-Large Hadron Colli...

  5. CERN Sells its Electronic Document Handling System

    CERN Multimedia

    2001-01-01

    The EDH team. Left to right: Derek Mathieson, Rotislav Titov, Per Gunnar Jonsson, Ivica Dobrovicova, James Purvis. Missing from the photo is Jurgen De Jonghe. In a 1 MCHF deal announced this week, the British company Transacsys bought the rights to CERN's Electronic Document Handling (EDH) system, which has revolutionised the Laboratory's administrative procedures over the last decade. Under the deal, CERN and Transacsys will collaborate on developing EDH over the coming 12 months. CERN will provide manpower and expertise and will retain the rights to use EDH, which will also be available freely to other particle physics laboratories. This development is an excellent example of the active technology transfer policy CERN is currently pursuing. The negotiations were carried out through a fruitful collaboration between AS and ETT Divisions, following the recommendations of the Technology Advisory Board, and with the help of SPL Division. EDH was born in 1991 when John Ferguson and Achille Petrilli of AS Divisi...

  6. New correlated electron physics from new materials

    International Nuclear Information System (INIS)

    Maple, M.B.; Baumbach, R.E.; Hamlin, J.J.; Zocco, D.A.; Taylor, B.J.; Butch, N.P.; Jeffries, J.R.; Weir, S.T.; Sales, B.C.; Mandrus, D.; McGuire, M.A.; Sefat, A.S.; Jin, R.; Vohra, Y.K.; Chu, J.-H.; Fisher, I.R.

    2009-01-01

    Many important advances in the physics of strongly correlated electron systems have been driven by the development of new materials: for instance the filled skutterudites MT 4 X 12 (M=alkali metal, alkaline earth, lanthanide, or actinide; T=Fe, Ru, or Os; X=P, As, or Sb), certain lanthanide and actinide intermetallic compounds such as URu 2-x Re x Si 2 and CeTIn 5 (T=Co, Rh, or Ir), and layered oxypnictides and related materials. These types of complex multinary d- and f-electron compounds have proven to be a vast reservoir of novel strongly correlated electron ground states and phenomena. In these materials, the occurrence of such a wide range of ground states and phenomena arises from a delicate interplay between competing interactions that can be tuned by partial or complete substitution of one element for another, as well as the application of pressure, and magnetic fields, resulting in rich and complex electronic phase diagrams in the hyperspace of temperature, chemical composition, pressure and magnetic field. It seems clear that this type of 'materials driven physics' will continue to play a central role in the development of the field of strongly correlated electron systems in the future, through the discovery of new materials that exhibit unexpected phenomena and experiments on known materials in an effort to optimize their physical properties and test relevant theories.

  7. Ariadne: The Next Generation of Electronic Document Delivery Systems.

    Science.gov (United States)

    Roes, Hans; Dijkstra, Joost

    1994-01-01

    Describes an approach to electronic document delivery which has evolved at Tilburg University (Netherlands), leading to the development of a system called Ariadne. Highlights include various generations of electronic document delivery systems; standards, including the work of the Group on Electronic Document Interchange; and a description of the…

  8. Development of the electron gun control system of SSRF

    International Nuclear Information System (INIS)

    Zhou Dayong; Lin Guoqiang; Liu Dekang; Shen Liren

    2010-01-01

    An electron gun is the key part of a linac, the beam quality of which depends on beam quality of the electron gun, hence the need of a stable control system of the electron gun to ensure its safe operation.In this paper, we report our progresses in developing the linac's electron gun control system of Shanghai Synchrotron Radiation Facility (SSRF). It uses PLC as the device controllers, with the monitoring software developed on EPICS. The whole system is connected by Ethernet. The PLC and Ethernet technology ensures good reliability and easy maintenance of the electron gun control system. (authors)

  9. An Analysis of Electronic Commerce Acquisition Systems: Comparison of a New Pure Electronic Purchasing and Exchange System (Electronic Storefront) and Other Legacy On-line Purchasing Systems

    National Research Council Canada - National Science Library

    Rowe, Arthur

    2002-01-01

    ... as they relate to contracting and purchasing of supplies and services, The issues and concerns with legacy on-line procurement systems will be compared to a newly developed Pure Electronic Ordering System...

  10. One nanosecond pulsed electron gun systems

    International Nuclear Information System (INIS)

    Koontz, R.F.

    1979-02-01

    At SLAC there has been a continuous need for the injection of very short bunches of electrons into the accelerator. Several time-of-flight experiments have used bursts of short pulses during a normal 1.6 micro-second rf acceleration period. Single bunch beam loading experiments made use of a short pulse injection system which included high power transverse beam chopping equipment. Until the equipment described in this paper came on line, the basic grid-controlled gun pulse was limited to a rise time of 7 nanoseconds and a pulse width of 10 nanoseconds. The system described here has a grid-controlled rise time of less than 500 pico-seconds, and a minimum pulse width of less than 1 nanosecond. Pulse burst repetition rate has been demonstrated above 20 MHz during a 1.6 microsecond rf accelerating period. The order-of-magnitude increase in gun grid switching speed comes from a new gun design which minimizes lead inductance and stray capacitance, and also increases gun grid transconductance. These gun improvements coupled with a newly designed fast pulser mounted directly within the gun envelope make possible subnanosecond pulsing of the gun

  11. Power electronic converters and systems frontiers and applications

    CERN Document Server

    Trzynadlowski, Andrzej M

    2016-01-01

    Power electronics is a branch of electrical engineering dealing with conversion and control of electric power using semiconductor power switches. This book provides an overview of modern power electronic converters and systems, and their applications.

  12. Large intrinsic inductance in strongly correlated GaAs two-dimensional holes in the integer quantum hall regime

    International Nuclear Information System (INIS)

    Knighton, Talbot; Tarquini, Vinicio; Wu, Zhe; Huang, Jian; Pfeiffer, Loren; West, Ken

    2014-01-01

    Quantum Hall measurements are performed for a two-dimensional hole system (2DHS) confined to a 20 nm quantum well in 〈100〉 GaAs. Quantum oscillations reveal a density of 4 - 5×10 10  cm −2 with mobility μ = 1 × 10 6 cm 2 /V s. For temperatures less than ∼350 mK, anomalous insulating peaks are observed between integer fillings 1-2, 2-3, and 3-4. A large out-of-phase signal appears at these peaks, which indicates a substantial inductance inherent to the charge carriers

  13. Electronic structure of YBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/ including strong correlation effects

    Energy Technology Data Exchange (ETDEWEB)

    Costa-Quintana, J.; Lopez-Aguilar, F.; Balle, S.; Salvador, R.

    1989-05-01

    The occupied and unoccupied valence-band density of states of YBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/ is determined considering a coherent potential which includes the Coulomb intrasite d-d correlation. The p states tend to be all occupied and, as a consequence, the most localized d states with the XZ symmetry tend to be unoccupied giving rise to an upper Hubbard band. This picture is in good agreement with the direct and inverse photoemission spectroscopies.

  14. Electronic Resource Management System. Vernetzung von Lizenzinformationen

    Directory of Open Access Journals (Sweden)

    Michaela Selbach

    2014-12-01

    collections efficiently. Not only libraries, but also the negotiators of Alliance and National Licences need a software application which helps them to handle these complex licences efficiently. The project presented in this paper aims at developing a national Electronic Resource Management System (ERMS. It is funded by the German Research Foundation/Deutsche Forschungsgemeinschaft (DFG. The project partners are the North Rhine-Westphalian Library Service Centre (hbz, the University Library Johann Christian Senckenberg Frankfurt, the Head Office of the Gemeinsamer Bibliotheksverbund (GBV and the Freiburg University Library. The projected ERMS  will provide a software system with a central knowledge base which supports a unified overview of licence data with a local, regional and national scope. In the current state of development, the focus is on data and function modelling and on designing concepts for rights management, cooperative data management, implementation of interface standards and the intended services such as statistical analyses.

  15. Advanced Photonic and Electronic Systems WILGA 2010

    CERN Document Server

    Romaniuk, R S

    2010-01-01

    SPIE – PSP WILGA Symposium gathers two times a year in January and in May new adepts of advanced photonic and electronic systems. The event is oriented on components and applications. WILGA Symposium on Photonics and Web Engineering is well known on the web for its devotion to “young research” promotion under the eminent sponsorship of international engineering associations like SPIE and IEEE and their Poland Sections or Counterparts. WILGA is supported by the most important national professional organizations like KEiT PAN and PSP-Photonics Society of Poland. The Symposium is organized since 1998 twice a year. It has gathered over 4000 young researchers and published over 2000 papers mainly internationally, including more than 900 in 10 published so far volumes of Proc. SPIE. This paper is a digest of WILGA Symposium Series and WILGA 2010 summary. Introductory part treats WILGA Photonics Applications characteristics over the period 1998-2010. Following part presents a short report on the XXVth and XXVI...

  16. Implementing CORAL: An Electronic Resource Management System

    Science.gov (United States)

    Whitfield, Sharon

    2011-01-01

    A 2010 electronic resource management survey conducted by Maria Collins of North Carolina State University and Jill E. Grogg of University of Alabama Libraries found that the top six electronic resources management priorities included workflow management, communications management, license management, statistics management, administrative…

  17. Coincidence imaging system with electron optics

    Czech Academy of Sciences Publication Activity Database

    Kroupa, M.; Jakubek, J.; Krejčí, F.; Žemlička, J.; Horáček, Miroslav; Radlička, Tomáš; Vlček, Ivan

    2011-01-01

    Roč. 633, Supl. 1 (2011), S270-S273 ISSN 0168-9002 R&D Projects: GA AV ČR IAA100650803 Institutional research plan: CEZ:AV0Z20650511 Keywords : electron optics * coincidence Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.207, year: 2011

  18. Power electronic converter systems for direct drive renewable energy applications

    DEFF Research Database (Denmark)

    Chen, Zhe

    2013-01-01

    This chapter presents power electronic conversion systems for wind and marine energy generation applications, in particular, direct drive generator energy conversion systems. Various topologies are presented and system design optimization and reliability are briefly discussed.......This chapter presents power electronic conversion systems for wind and marine energy generation applications, in particular, direct drive generator energy conversion systems. Various topologies are presented and system design optimization and reliability are briefly discussed....

  19. The Shipboard Employment of a Free Electron Laser Weapon System

    Science.gov (United States)

    2003-12-01

    EMPLOYMENT OF A FREE ELECTRON LASER WEAPON SYSTEM by Gregory G. Allgaier December 2003 Thesis Advisor: William Colson Second Reader...Free Electron Laser Weapon System 6. AUTHOR(S) Allgaier, Gregory G. 5. FUNDING NUMBERS 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Naval...release; distribution is unlimited. THE SHIPBOARD EMPLOYMENT OF A FREE ELECTRON LASER WEAPON SYSTEM Gregory G. Allgaier Lieutenant, United

  20. [Theory of exotic superconducting and normal states of heavy electron and high Tc materials

    International Nuclear Information System (INIS)

    1990-01-01

    This paper discusses: quadrupole Kondo effect; heavy electron transport properties; quadrupolar fluctuation mechanism for high-T c superconductors; research accomplishments for the t--J model of high-T c superconductors; interpretation of high-T c superconductors experimental data; and dynamics of strongly correlated systems

  1. Controlled cooling of an electronic system for reduced energy consumption

    Energy Technology Data Exchange (ETDEWEB)

    David, Milnes P.; Iyengar, Madhusudan K.; Schmidt, Roger R.

    2018-01-30

    Energy efficient control of a cooling system cooling an electronic system is provided. The control includes automatically determining at least one adjusted control setting for at least one adjustable cooling component of a cooling system cooling the electronic system. The automatically determining is based, at least in part, on power being consumed by the cooling system and temperature of a heat sink to which heat extracted by the cooling system is rejected. The automatically determining operates to reduce power consumption of the cooling system and/or the electronic system while ensuring that at least one targeted temperature associated with the cooling system or the electronic system is within a desired range. The automatically determining may be based, at least in part, on one or more experimentally obtained models relating the targeted temperature and power consumption of the one or more adjustable cooling components of the cooling system.

  2. 76 FR 43206 - Electronic Tariff Filing System (ETFS)

    Science.gov (United States)

    2011-07-20

    ... transmittal numbers should continue sequentially from the last non- electronic tariff or associated document... that requiring the electronic filing of all tariffs and associated documents would benefit the public... nondominant carriers shall file their initial Base Document using the Electronic Tariff Filing System no later...

  3. Hund's Rule in Two-Electron Atomic Systems

    Science.gov (United States)

    Harriman, John E.

    2008-01-01

    A model proposed by Rioux to explain Hund's rule is investigated. Although the largest contribution to the singlet-triplet splitting in the two-electron atomic systems is the nuclear attraction term, this arises from different optimum scale factors in the two states and that difference is driven by the electron-electron exchange term. The…

  4. Radiation Hard Electronics for Advanced Communication Systems, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced reconfigurable/reprogrammable communication systems will require use of commercial sub 100 nm electronics. Legacy radiation tolerant circuits fail to...

  5. Radiation Hard Electronics for Advanced Communication Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced reconfigurable/reprogrammable communication systems will require use of commercial sub 100 nm electronics. Legacy radiation tolerant circuits fail to...

  6. VISA Final Report: Fully Integrated Power Electronic Systems in Automotive Electronics

    NARCIS (Netherlands)

    Waffenschmidt, E.

    2011-01-01

    This report summarizes the activities related to the public funded project “Vollintegrierte leistungselektronische Systeme in der Automobilelektronik – VISA” (Fully Integrated Power Electronic Systems in Automotive Electronics). Aim of the project is to investigate the integration of components into

  7. Design, development and characterization of tetrode type electron gun system for generation of low energy electrons

    International Nuclear Information System (INIS)

    Deore, A.V.; Bhoraskar, V.N.; Dhole, S.D.

    2011-01-01

    A tetrode type electron gun system for the generation of low energy electrons was designed, developed and characterized. An electron gun having four electrodes namely cathode, focusing electrode, control electrode and anode has been designed for the irradiation experiments. This electron gun is capable to provide electrons of energy over the range of 1 keV to 20 keV, with current maximum upto 100 μA. The electron gun and a faraday cup are mounted in the evacuated cylindrical chamber. The samples are fixed on the faraday cup and irradiated with low energy electrons at a pressure around 10 -6 mbar. In this electron gun system, at any electron energy over the entire range, the electron beam diameter can be varied from 5 to 120 mm on the Faraday cup mounted at a distance of 200 mm from the anode in the chamber. Also, the circular shape of the beam spot was maintained, even though the beam current and beam diameter are varied. The uniformity of the electron beam over the entire beam area was measured with a multi electrode assembly and found to be well within 15%. This system is being used for the synthesis and diffusion of metal and semiconductor nanoparticles in polymeric materials. (author)

  8. Tuning intermetallic electronic coupling in polyruthenium systems ...

    Indian Academy of Sciences (India)

    molecular architecture. SANDEEP GHUMAAN and GOUTAM KUMAR LAHIRI ... complexes encompassing selective combinations of spacer (bridging ligand, BL) and ancillary (AL) functionalities have been designed. ... plications in designing molecular electronic devices3 such as molecular wires, semi-conductors, rods etc.

  9. ELECTRONIC PAYMENT SYSTEM AND ITS PROTECTION

    OpenAIRE

    Miroslav Milutinovic; Andon Kostadinovic; Nenad Zivkovic

    2015-01-01

    All developed countries are in transition from the IT economy to a web economy - the biggest technological innovation that will have a long-term positive effect on the formation of the economic growth rate, the major structural changes and on the differentiated effects on the economic areas that are, at a faster or a slower rate, being included in this technological change. The electronic commerce or e-commerce has a huge potential for development. The electronic ...

  10. Diagnostic Neural Network Systems for the Electronic Circuits

    International Nuclear Information System (INIS)

    Mohamed, A.H.

    2014-01-01

    Neural Networks is one of the most important artificial intelligent approaches for solving the diagnostic processes. This research concerns with uses the neural networks for diagnosis of the electronic circuits. Modern electronic systems contain both the analog and digital circuits. But, diagnosis of the analog circuits suffers from great complexity due to their nonlinearity. To overcome this problem, the proposed system introduces a diagnostic system that uses the neural network to diagnose both the digital and analog circuits. So, it can face the new requirements for the modern electronic systems. A fault dictionary method was implemented in the system. Experimental results are presented on three electronic systems. They are: artificial kidney, wireless network and personal computer systems. The proposed system has improved the performance of the diagnostic systems when applied for these practical cases

  11. Miniaturized electronic system for the Planetary Integrated Camera-Spectrometer

    Science.gov (United States)

    Soll, Stanley L.; Graham, Richard; Ramirez, Luis J.

    1994-09-01

    This paper discusses the design, and implementation of a miniaturized electronic system for the Planetary Integrated Camera Spectrometer (PICS). The PICS electronics demonstrate the application of Field Programmable Gate Arrays (FPGAs) and of analog hybrid technology to space flight multi-spectral systems. A discussion of the electronic system design illustrates how signals from a multi-sensor instrument containing an UV CCD, two visible CCDs, and a near-IR focal plane assembly can be processed through a common set of electronics. Following the system design discussion, the actual electronic design will be presented. Each miniaturized module will be discussed as to functionality and performance. The test setup for bench checkout of a cooled CCD and an IR FPA, including results with breadboard electronics and with the hybrids are also described.

  12. Freeform Compliant CMOS Electronic Systems for Internet of Everything Applications

    KAUST Repository

    Shaikh, Sohail F.

    2017-01-17

    The state-of-the-art electronics technology has been an integral part of modern advances. The prevalent rise of the mobile device and computational technology in the age of information technology offers exciting applications that are attributed to sophisticated, enormously reliable, and most mature CMOS-based electronics. We are accustomed to high performance, cost-effective, multifunctional, and energy-efficient scaled electronics. However, they are rigid, bulky, and brittle. The convolution of flexibility and stretchability in electronics for emerging Internet of Everything application can unleash smart application horizon in unexplored areas, such as robotics, healthcare, smart cities, transport, and entertainment systems. While flexible and stretchable device themes are being remarkably chased, the realization of the fully compliant electronic system is unaddressed. Integration of data processing, storage, communication, and energy management devices complements a compliant system. Here, a comprehensive review is presented on necessity and design criteria for freeform (physically flexible and stretchable) compliant high-performance CMOS electronic systems.

  13. High quality flux control system for electron gun evaporation

    International Nuclear Information System (INIS)

    Appelbloom, A.M.; Hadley, P.; van der Marel, D.; Mooij, J.E.

    1991-01-01

    This paper reports on a high quality flux control system for electron gun evaporation developed and tested for the MBE growth of high temperature superconductors. The system can be applied to any electron gun without altering the electron gun itself. Essential elements of the system are a high bandwidth mass spectrometer, control electronics and a high voltage modulator to sweep the electron beam over the melt at high frequencies. the sweep amplitude of the electron beam is used to control the evaporation flux at high frequencies. The feedback loop of the system has a bandwidth of over 100 Hz, which makes it possible to grow superlattices and layered structures in a fast and precisely controlled manner

  14. A 20 keV electron gun system for the electron irradiation experiments

    International Nuclear Information System (INIS)

    Mahapatra, S.K.; Dhole, S.D.; Bhoraskar, V.N.

    2005-01-01

    An electron gun consisting of cathode, focusing electrode, control electrode and anode has been designed and fabricated for the electron irradiation experiments. This electron gun can provide electrons of any energy over the range 1-20 keV, with current upto 50 μA. This electron gun and a Faraday cup are mounted in the cylindrical chamber. The samples are fixed on the Faraday cup and irradiated with electrons at a pressure ∼10 -7 mbar. The special features of this electron gun system are that, at any electron energy above 1 keV, the electron beam diameter can be varied from 5 to 120 mm on the Faraday cup mounted at a distance of 200 mm from the anode in the chamber. The variation in the electron current over the beam spot of 120 mm diameter is less than 15% and the beam current stability is better than 5%. This system is being used for studying the irradiation effects of 1-20 keV energy electrons on the space quality materials in which the irradiation time may vary from a few tens of seconds to hours

  15. Assessment of Electronic Absentee System for Elections (EASE) Grants

    Science.gov (United States)

    2015-06-30

    No. DODIG-2015-135 J U N E 3 0 , 2 0 1 5 Assessment of Electronic Absentee System for Elections (EASE) Grants Mission Our mission is to provide...A b u s e DODIG-2015-135 (Project No. D2015-D00SPO-0045.000) │ i Results in Brief Assessment of Electronic Absentee System for Elections (EASE...Member, Military Personnel Subcommittee, House Armed Service Committee. Our objective was to determine whether recipients of Electronic Absentee

  16. Security analysis of electronic voting and online banking systems

    OpenAIRE

    Tjøstheim, Thomas

    2007-01-01

    The main focus of this dissertation is on security analysis of electronic voting and online banking systems. Six papers form the basis of the thesis and include the following topics: a model for analysis of voting systems, a case study where we apply the proposed model, a new scheme for remote electronic voting, and three case studies of commercial online banking solutions in Norway.

  17. A control system for a free electron laser experiment

    International Nuclear Information System (INIS)

    Giove, D.

    1992-01-01

    The general layout of a control and data acquisition system for a Free Electron Laser experiment will be discussed. Some general considerations about the requirements and the architecture of the whole system will be developed. (author)

  18. CSIR's new integrated electronic library information-system

    CSIR Research Space (South Africa)

    Michie, A

    1995-08-01

    Full Text Available The CSIR has developed a CDROM-based electronic library information system which provides the ability to reproduce and search for published information and colour brochures on the computer screen. The system integrates this information with online...

  19. Tuning intermetallic electronic coupling in polyruthenium systems ...

    Indian Academy of Sciences (India)

    A large number of polynuclear ruthenium complexes encompassing selective combinations of spacer (bridging ligand, BL) and ancillary (AL) functionalities have been designed. The extent of intermetallic electronic communication in mixed-valent states and the efficacy of the ligand frameworks towards the tuning of ...

  20. Power electronics for renewable energy systems

    DEFF Research Database (Denmark)

    Iov, Florin; Blaabjerg, Frede

    2009-01-01

    sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. Another is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss some of the most emerging renewable energy sources...

  1. Tuning intermetallic electronic coupling in polyruthenium systems ...

    Indian Academy of Sciences (India)

    Abstract. A large number of polynuclear ruthenium complexes encompassing selective combinations of spacer (bridging ligand, BL) and ancillary (AL) functionalities have been designed. The extent of inter- metallic electronic communication in mixed-valent states and the efficacy of the ligand frameworks to- wards the ...

  2. New Project System for Undergraduate Electronic Engineering

    Science.gov (United States)

    Chiu, Dirk M.; Chiu, Shen Y.

    2005-01-01

    A new approach to projects for undergraduate electronic engineering in an Australian university has been applied successfully for over 10 years. This approach has a number of projects running over three year period. Feedback from past graduates and their managers has confirmed that these projects train the students well, giving them the ability…

  3. Smart parking management system with decal electronics system

    KAUST Repository

    Hussain, Muhammad Mustafa

    2017-09-21

    Various examples are related to parking management, including identifying and reserving empty parking spaces. In one example, a smart parking space system includes a parking controller located at a parking space. The parking controller can identify a vehicle located at the parking space via an input sensor or a transceiver that initiates wireless communication with an electronic tag associated with the vehicle; and communicate a parking vacancy associated with the parking space to a remote computing device based at least in part on the identification of the vehicle. In another example, a computing device can receive parking vacancy data associated with a parking space from a parking controller; determine a parking vacancy associated with the parking space using the parking vacancy data; and encode for display on a client device a network page that includes an indication of the parking vacancy associated with the parking space.

  4. Multi-electron beam system for high resolution electron beam induced deposition

    NARCIS (Netherlands)

    Van Bruggen, M.J.

    2008-01-01

    The development of a multi-electron beam system is described which is dedicated for electron beam induced deposition (EBID) with sub-10 nm resolution. EBID is a promising mask-less nanolithography technique which has the potential to become a viable technique for the fabrication of 20-2 nm

  5. Electronic medical records system user acceptance

    CSIR Research Space (South Africa)

    Erasmus, L

    2015-06-01

    Full Text Available the change due to a lack of understanding of the system with usability of the system playing a large role. Even experienced user will resist a system if they perceive the system to be ineffective in assisting them with their primary task. Thus, based...

  6. Theory of open quantum systems with bath of electrons and phonons and spins: many-dissipaton density matrixes approach.

    Science.gov (United States)

    Yan, YiJing

    2014-02-07

    This work establishes a strongly correlated system-and-bath dynamics theory, the many-dissipaton density operators formalism. It puts forward a quasi-particle picture for environmental influences. This picture unifies the physical descriptions and algebraic treatments on three distinct classes of quantum environments, electron bath, phonon bath, and two-level spin or exciton bath, as their participating in quantum dissipation processes. Dynamical variables for theoretical description are no longer just the reduced density matrix for system, but remarkably also those for quasi-particles of bath. The present theoretical formalism offers efficient and accurate means for the study of steady-state (nonequilibrium and equilibrium) and real-time dynamical properties of both systems and hybridizing environments. It further provides universal evaluations, exact in principle, on various correlation functions, including even those of environmental degrees of freedom in coupling with systems. Induced environmental dynamics could be reflected directly in experimentally measurable quantities, such as Fano resonances and quantum transport current shot noise statistics.

  7. Electronic system for Langmuir probe measurements

    Czech Academy of Sciences Publication Activity Database

    Mitov, M.; Bankova, A.; Dimitrova, M.; Ivanova, P.; Tutulkov, K.; Djermanova, N.; Dejarnac, Renaud; Stöckel, Jan; Popov, Tsv.K.

    2012-01-01

    Roč. 356, č. 1 (2012), s. 012008 ISSN 1742-6588. [InternationalSummerSchoolonVacuum,Electron, and IonTechnologies(VEIT2011)/17./. Sunny Beach, 19.09.2011-23.09.2011] Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma * tokamak * diagnostics * electric probe Subject RIV: BL - Plasma and Gas Discharge Physics http://iopscience.iop.org/1742-6596/356/1/012008/pdf/1742-6596_356_1_012008.pdf

  8. Energy Transformation in Molecular Electronic Systems

    Energy Technology Data Exchange (ETDEWEB)

    Kasha, Michael

    1999-05-17

    This laboratory has developed many new ideas and methods in the electronic spectroscopy of molecules. This report covers the contract period 1993-1995. A number of the projects were completed in 1996, and those papers are included in the report. The DOE contract was terminated at the end of 1995 owing to a reorganizational change eliminating nationally the projects under the Office of Health and Environmental Research, U. S. Department of Energy.

  9. Electronic Equipment Proposal to Improve the Photovoltaic Systems Efficiency

    Science.gov (United States)

    Flores-Mena, J. E.; Juárez Morán, L. A.; Díaz Reyes, J.

    2011-05-01

    This paper reports a new technique proposal to improve the photovoltaic systems. It was made to design and implement an electronic system that will detect, capture, and transfer the maximum power of the photovoltaic (PV) panel to optimize the supplied power of a solar panel. The electronic system works on base technical proposal of electrical sweeping of electric characteristics using capacitive impedance. The maximum power is transformed and the solar panel energy is sent to an automotive battery. This electronic system reduces the energy lost originated when the solar radiation level decreases or the PV panel temperature is increased. This electronic system tracks, captures, and stores the PV module's maximum power into a capacitor. After, a higher voltage level step-up circuit was designed to increase the voltage of the PV module's maximum power and then its current can be sent to a battery. The experimental results show that the developed electronic system has 95% efficiency. The measurement was made to 50 W, the electronic system works rightly with solar radiation rate from 100 to 1,000 W m - 2 and the PV panel temperature rate changed from 1 to 75°C. The main advantage of this electronic system compared with conventional methods is the elimination of microprocessors, computers, and sophisticated numerical approximations, and it does not need any small electrical signals to track the maximum power. The proposed method is simple, fast, and it is also cheaper.

  10. Efficiency improvement of an electron collector intended for electron cooling systems using a Wien filter

    Science.gov (United States)

    Bryzgunov, M. I.; Ivanov, A. V.; Panasyuk, V. M.; Parkhomchuk, V. V.; Reva, V. B.

    2013-06-01

    An efficient collector for high-voltage systems of electron cooling is presented. Its efficiency (ratio of the reflected electron current to the current of the main beam) is greatly improved by suppressing the reflected particle flux in the Wien filter. Secondary electrons deflect in crossed transverse electric and magnetic fields and are absorbed by a special receiver plate (secondary collector). The filter is designed so that the whole backward flow of electrons deflects even if the trajectory and main beam profile are distorted insignificantly. Experiments carried out on a special-purpose test bench show that such a filter raises the efficiency of the collector hundredfold (up to 10-6).

  11. The electronic identification, signature and security of information systems

    Directory of Open Access Journals (Sweden)

    Horovèák Pavel

    2002-12-01

    Full Text Available The contribution deals with the actual methods and technologies of information and communication systems security. It introduces the overview of electronic identification elements such as static password, dynamic password and single sign-on. Into this category belong also biometric and dynamic characteristics of verified person. Widespread is authentication based on identification elements ownership, such as various cards and authentication calculators. In the next part is specified a definition and characterization of electronic signature, its basic functions and certificate categories. Practical utilization of electronic signature consists of electronic signature acquirement, signature of outgoing email message, receiving of electronic signature and verification of electronic signature. The use of electronic signature is continuously growing and in connection with legislation development it exercises in all resorts.

  12. Noise Susceptibility Measurements of Front-End Electronics Systems

    CERN Document Server

    Allongue, B; Blanchot, G; Faccio, F; Fuentes, C; Michelis, S; Orlandi, S; Toro, A

    2008-01-01

    The conducted and radiated noise that is emitted by a power supply constrains the noise performance of the frontend electronics system that it powers. The characterization of the noise susceptibility of the front-end electronics allows setting proper requirements for the back-end power supply in order to achieve the expected system performance. A method to measure the common mode current susceptibility using current probes is presented. The compatibility between power supplies and various front-end systems is explored.

  13. Secure electronic commerce communication system based on CA

    Science.gov (United States)

    Chen, Deyun; Zhang, Junfeng; Pei, Shujun

    2001-07-01

    In this paper, we introduce the situation of electronic commercial security, then we analyze the working process and security for SSL protocol. At last, we propose a secure electronic commerce communication system based on CA. The system provide secure services such as encryption, integer, peer authentication and non-repudiation for application layer communication software of browser clients' and web server. The system can implement automatic allocation and united management of key through setting up the CA in the network.

  14. Electronic systems for the organization and planning of school

    OpenAIRE

    Vodová, Alena

    2014-01-01

    TITLE: Electronic systems for the organization and planning of school AUTHOR: Alena Vodová DEPARTMENT: The Center of School management SUPERVISOR: Ing. Petr Svoboda Ph.D. ABSTRACT: The bachelor thesis gives comprehensive overview electronic systems for organization and planning of school. Maps of species, describes their function, demonstrates the benefits, modes and applications to use in school. In the research part individuals system compares between them and validates their use in schools...

  15. Handbook of power systems engineering with power electronics applications

    CERN Document Server

    Hase, Yoshihide

    2012-01-01

    Formerly known as Handbook of Power System Engineering, this second edition provides rigorous revisions to the original treatment of systems analysis together with a substantial new four-chapter section on power electronics applications. Encompassing a whole range of equipment, phenomena, and analytical approaches, this handbook offers a complete overview of power systems and their power electronics applications, and presents a thorough examination of the fundamental principles, combining theories and technologies that are usually treated in separate specialised fields, in a single u

  16. THERMOELECTRIC DEVICES TO PROVIDE THERMAL BLOCK MODE ELECTRONIC SYSTEMS

    Directory of Open Access Journals (Sweden)

    T. A. Ismailov

    2015-01-01

    Full Text Available The article deals with thermoelectric cooling (TEC device to provide thermal mode power electronics systems cluster design, are areas of constructive solutions use the feasibility study of the device, a description of the experimental facility and methodology of the experiment, the dependences of temperature on the simulator of the electronic board from the exhaust of the feasibility study power, temperatures of hot and cold junctions, the speed of the air flow and the distance between the electronic boards. 

  17. Electron Cyclotron Resonance Heating (ECRH) Control System

    International Nuclear Information System (INIS)

    Heefner, J.W.; Williams, C.W.; Lauze, R.R.; Karsner, P.G.

    1985-01-01

    The ECRH Control System was installed on the Tandem Mirror Experiment-Upgrade (TMX-U) in 1980. The system provides approximately 1 MW of 28 GHz microwave power to the TMX-U plasma. The subsystems of ECRH that must be controlled include high-voltage charging supplies, series pass tubes, and magnet supplies. In addition to the devices that must be controlled, many interlocks must be continuously monitored. The previous control system used relay logic and analog controls to operate the system. This approach has many drawbacks such as lack of system flexibility and maintainability. In order to address these problems, it was decided to go with a CAMAC and Modicon based system that uses a Hewlett-Packard 9836C personal computer to replace the previous analog controls. 2 figs

  18. Electronic consultation system demonstrates educational benefit for primary care providers.

    Science.gov (United States)

    Kwok, Jonas; Olayiwola, J Nwando; Knox, Margae; Murphy, Elizabeth J; Tuot, Delphine S

    2017-01-01

    Background Electronic consultation systems allow primary care providers to receive timely speciality expertise via iterative electronic communication. The use of such systems is expanding across the USA with well-documented high levels of user satisfaction. We characterise the educational impact for primary care providers of a long-standing integrated electronic consultation and referral system. Methods Primary care providers' perceptions of the educational value inherent to electronic consultation system communication and the impact on their ability to manage common speciality clinical conditions and questions were examined by electronic survey using five-point Likert scales. Differences in primary care providers' perceptions were examined overall and by primary care providers' speciality, provider type and years of experience. Results Among 221 primary care provider participants (35% response rate), 83.9% agreed or strongly agreed that the integrated electronic consultation and referral system provided educational value. There were no significant differences in educational value reported by provider type (attending physician, mid-level provider, or trainee physician), primary care providers' speciality, or years of experience. Perceived benefit of the electronic consultation and referral system in clinical management appeared stronger for laboratory-based conditions (i.e. subclinical hypothyroidism) than more diffuse conditions (i.e. abdominal pain). Nurse practitioners/physician assistants and trainee physicians were more likely to report improved abilities to manage specific clinical conditions when using the electronic consultation and/or referral system than were attending physicians, as were primary care providers with ≤10 years experience, versus those with >20 years of experience. Conclusions Primary care providers report overwhelmingly positive perceptions of the educational value of an integrated electronic consultation and referral system. Nurse

  19. INFORMATION SECURITY: IRS Electronic Filing Systems

    National Research Council Canada - National Science Library

    2001-01-01

    ...) computer controls over its external access points and internal networks and systems, we assessed the effectiveness of key computer controls designed to ensure the security, privacy, and reliability...

  20. Electronic referral system for hospitals in Nigeria | Idowu | Ife Journal ...

    African Journals Online (AJOL)

    The advent of Information Technology gave birth to Telemedicine, which has led to electronic-based consultations such as electronic referral system in hospitals. In Nigeria, all the state hospitals are having problems in referring patients from one hospital to another. Most of the time before a patient could be referred from one ...

  1. XXIII International Conference on Nonlinear Dynamics of Electronic Systems

    CERN Document Server

    Stoop, Ruedi; Stramaglia, Sebastiano

    2017-01-01

    This book collects contributions to the XXIII international conference “Nonlinear dynamics of electronic systems”. Topics range from non-linearity in electronic circuits to synchronisation effects in complex networks to biological systems, neural dynamics and the complex organisation of the brain. Resting on a solid mathematical basis, these investigations address highly interdisciplinary problems in physics, engineering, biology and biochemistry.

  2. The development of efficient coding for an electronic mail system

    Science.gov (United States)

    Rice, R. F.

    1983-01-01

    Techniques for efficiently representing scanned electronic documents were investigated. Major results include the definition and preliminary performance results of a Universal System for Efficient Electronic Mail (USEEM), offering a potential order of magnitude improvement over standard facsimile techniques for representing textual material.

  3. Iterative diagonalization of the non-Hermitian transcorrelated Hamiltonian using a plane-wave basis set: Application to sp-electron systems with deep core states

    Energy Technology Data Exchange (ETDEWEB)

    Ochi, Masayuki, E-mail: ochi@phys.sci.osaka-u.ac.jp; Arita, Ryotaro [RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198 (Japan); JST ERATO Isobe Degenerate pi-Integration Project, Advanced Institute for Materials Research (AIMR), Tohoku University, Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yamamoto, Yoshiyuki [Department of Physics, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033 (Japan); Tsuneyuki, Shinji [Department of Physics, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033 (Japan); Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581 (Japan)

    2016-03-14

    We develop an iterative diagonalization scheme in solving a one-body self-consistent-field equation in the transcorrelated (TC) method using a plane-wave basis set. Non-Hermiticity in the TC method is well handled with a block-Davidson algorithm. We verify that the required computational cost is efficiently reduced by our algorithm. In addition, we apply our plane-wave-basis TC calculation to some simple sp-electron systems with deep core states to elucidate an impact of the pseudopotential approximation to the calculated band structures. We find that a position of the deep valence bands is improved by an explicit inclusion of core states, but an overall band structure is consistent with a regular setup that includes core states into the pseudopotentials. This study offers an important understanding for the future application of the TC method to strongly correlated solids.

  4. Color Electronic Prepress Systems: Present And Future

    Science.gov (United States)

    Cloud, Kennard S.

    1989-08-01

    The graphic arts industry has been undergoing a quiet revolution as computerization and electronic imaging have invaded virtually every aspect of print production. Since this industry is one of the largest small businesses in the world (with over 54,400 establishments - over 85% of which employ less than 20 people) there are many opportunities for new development. The problem is, there is very little knowledge about what needs to be done. No area has been more severely impacted or offers the breadth of opportunity as the color prepress sector. This paper attempts to provide some insight and background in this exciting market sector, and offers some opinions as to how it will develop in the future.

  5. Determination of radiation resistant of electronic components in robot system

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Hee Dong [Kyungpook National University, Taegu (Korea); Kim, Do Sung [Taegu University, Taegu (Korea); Woo, Hong [Kyungsan University, Kyungsan (Korea)

    1998-04-01

    We investigated the characteristic change for the electronic components of the systems which were used in radiation area, when those were exposured by gamma rays. Bipolar transistor, FET, TTL, CMOS, operational amplifier, some capacitors, and several electronic components were selected for experiment. We applied irradiated gamma ray to the electronic components in the range of 10{sup 6} rad, by {sup 6}0Co(KAERI). We made up appropriate assessment circuit for each electronic component during the performance test, and assessed the reliability and radiation-resistance of them for the each radiation irradiation. (author). 59 refs., 35 figs., 8 tabs.

  6. Investigation of Noise in Electronic Ultrasonic Systems

    Directory of Open Access Journals (Sweden)

    Paulius Adomavičius

    2011-03-01

    Full Text Available Noise models in ultrasonic control system have been investigated. Ultrasonic system channel consist of exciting generator, ultrasonic transducer, amplitude limiter, amplifier, low band filter and A/D converter. The ultrasonic transducers have been described as Von Hippel model, Van Dyke model or improved Van Dyke model. Advantages and disadvantages of these models are discussed in this paper. Noise models of amplitude limiter and linear operational amplifier are presented. The summary results of calculated noise spectral density of ultrasonic system channel have been presented.Article in Lithuanian

  7. A computer-controlled conformal radiotherapy system. IV: Electronic chart

    International Nuclear Information System (INIS)

    Fraass, Benedick A.; McShan, Daniel L.; Matrone, Gwynne M.; Weaver, Tamar A.; Lewis, James D.; Kessler, Marc L.

    1995-01-01

    Purpose: The design and implementation of a system for electronically tracking relevant plan, prescription, and treatment data for computer-controlled conformal radiation therapy is described. Methods and Materials: The electronic charting system is implemented on a computer cluster coupled by high-speed networks to computer-controlled therapy machines. A methodical approach to the specification and design of an integrated solution has been used in developing the system. The electronic chart system is designed to allow identification and access of patient-specific data including treatment-planning data, treatment prescription information, and charting of doses. An in-house developed database system is used to provide an integrated approach to the database requirements of the design. A hierarchy of databases is used for both centralization and distribution of the treatment data for specific treatment machines. Results: The basic electronic database system has been implemented and has been in use since July 1993. The system has been used to download and manage treatment data on all patients treated on our first fully computer-controlled treatment machine. To date, electronic dose charting functions have not been fully implemented clinically, requiring the continued use of paper charting for dose tracking. Conclusions: The routine clinical application of complex computer-controlled conformal treatment procedures requires the management of large quantities of information for describing and tracking treatments. An integrated and comprehensive approach to this problem has led to a full electronic chart for conformal radiation therapy treatments

  8. Power System Electronics (PSE) Development for SmallSat Technology

    Data.gov (United States)

    National Aeronautics and Space Administration — We develop a modular Power System Electronics (PSE) that is reliable, efficient, and flexible to meet the Goddard Modular Smallsat Architecture (GMSA) challenge....

  9. Assessment of Safety Standards for Automotive Electronic Control Systems

    Science.gov (United States)

    2016-06-01

    This report summarizes the results of a study that assessed and compared six industry and government safety standards relevant to the safety and reliability of automotive electronic control systems. These standards include ISO 26262 (Road Vehicles - ...

  10. Using electronic document management systems to manage highway project files.

    Science.gov (United States)

    2011-12-12

    "WisDOTs Bureau of Technical Services is interested in learning about the practices of other state departments of : transportation in developing and implementing an electronic document management system to manage highway : project files"

  11. Real Time Space Radiation Effects in Electronic Systems

    Data.gov (United States)

    National Aeronautics and Space Administration — The effects that solar particle events can have on operational electronic systems is a significant concern for all missions, but especially for those beyond Low...

  12. System and method for compressive scanning electron microscopy

    Science.gov (United States)

    Reed, Bryan W

    2015-01-13

    A scanning transmission electron microscopy (STEM) system is disclosed. The system may make use of an electron beam scanning system configured to generate a plurality of electron beam scans over substantially an entire sample, with each scan varying in electron-illumination intensity over a course of the scan. A signal acquisition system may be used for obtaining at least one of an image, a diffraction pattern, or a spectrum from the scans, the image, diffraction pattern, or spectrum representing only information from at least one of a select subplurality or linear combination of all pixel locations comprising the image. A dataset may be produced from the information. A subsystem may be used for mathematically analyzing the dataset to predict actual information that would have been produced by each pixel location of the image.

  13. CPSC’s National Electronic Injury Surveillance System (NEISS)

    Data.gov (United States)

    US Consumer Product Safety Commission — CPSC’s National Electronic Injury Surveillance System (NEISS) is a national probability sample of hospitals in the U.S. and its territories. Patient information is...

  14. Automotive mechatronics automotive networking, driving stability systems, electronics

    CERN Document Server

    2015-01-01

    As the complexity of automotive vehicles increases this book presents operational and practical issues of automotive mechatronics. It is a comprehensive introduction to controlled automotive systems and provides detailed information of sensors for travel, angle, engine speed, vehicle speed, acceleration, pressure, temperature, flow, gas concentration etc. The measurement principles of the different sensor groups are explained and examples to show the measurement principles applied in different types. Contents Basics of mechatronics.- Architecture.- Electronic control unit.- Software development.- Basic principles of networking.- Automotive networking.- Bus systems.- Automotive sensors.- Sensor measuring principles.- Sensor types.- Electric actuators.- Electrohydraulic actuators.- Electronic transmission control.- Electronic transmission control unit.- Modules for transmission control.- Antilock braking system.- Traction control system.- Electronic stability program.- Automatic brake functions.- Hydraulic modu...

  15. Electronic construction collaboration system -- phase II.

    Science.gov (United States)

    2010-06-01

    During the first year of research, work was completed to identify Iowa DOT needs for web-based project management system (WPMS) : and evaluate how commercially available solutions could meet these needs. Researchers also worked to pilot test custom d...

  16. Design for Reliability of Power Electronics in Renewable Energy Systems

    DEFF Research Database (Denmark)

    Ma, Ke; Yang, Yongheng; Wang, Huai

    2014-01-01

    Power electronics is the enabling technology for maximizing the power captured from renewable electrical generation, e.g., the wind and solar technology, and also for an efficient integration into the grid. Therefore, it is important that the power electronics are reliable and do not have too many...... electronics technology as well as to know how the power electronics technology is loaded in terms of temperature and other stressors relevant, to reliability. Hence, this chapter will show the basics of power electronics technology for renewable energy systems, describe the mission profile of the technology...... failures during operation which otherwise will increase cost for operation, maintenance and reputation. Typically, power electronics in renewable electrical generation has to be designed for 20–30 years of operation, and in order to do that, it is crucial to know about the mission profile of the power...

  17. Monitoring and control system of the Saclay electron linear accelerator

    International Nuclear Information System (INIS)

    Lafontaine, Antoine

    1974-01-01

    A description is given of the automatic monitoring and control system of the 60MeV electron linear accelerator of the Centre d'Etudes Nucleaires de Saclay. The paper is mostly concerned with the programmation of the system. However, in a real time device, there is a very close association between computer and electronics, the latter are therefore described in details and make up most of the paper. [fr

  18. Beam characterisation of the KIRAMS electron microbeam system

    International Nuclear Information System (INIS)

    Sun, G. M.; Kim, E. H.; Song, K. B.; Jang, M.

    2006-01-01

    An electron microbeam system has been installed at the Korea Inst. of Radiological and Medical Sciences (KIRAMS) for use in radiation biology studies. The electron beam is produced from a commercial electron gun, and the beam size is defined by a 5 μm diameter pinhole. Beam energy can be varied in the range of 1-100 keV, covering a range of linear energy transfer from 0.4 to 12.1 keV μm -1 . The micrometer-sized electron beam selectively irradiates cells cultured in a Mylar-bottomed dish. The positioning of target cells one by one onto the beam exit is automated, as is beam shooting. The electron beam entering the target cells has been calibrated using a Passivated Implanted Planar Silicon (PIPS) detector. This paper describes the KIRAMS microbeam cell irradiation system and its beam characteristics. (authors)

  19. The Mott localization and magnetic properties in condensed fermions systems; Lokalizacja Motta i wlasnosci magnetyczne skondensowanych ukladow fermionowych

    Energy Technology Data Exchange (ETDEWEB)

    Wojcik, W. [Politechnika Krakowska, Cracow (Poland)

    1995-12-31

    In the present thesis the Mott localization and magnetic properties in condensed fermions system are considered. The Hubbard model has been used to strongly correlated electron systems and the Skyrme potential to a dense neutron matter with small concentration of protons. A variational approach to the metal-insulator transition is proposed which combines the Mott and Gutzwiller-Brinkman-Rice aspects of the localization. Magnetic properties of strongly correlated electrons are analyzed within the modified spin-rotation-invariant approach in the slow-boson representation. The theoretical prediction for considered systems are presented. 112 refs, 39 figs.

  20. ELECTRONIC PAYMENT SYSTEMS AND THEIR POSSIBLE WAY OF DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    K. V. Karvai

    2013-01-01

    Full Text Available With development of a century of technologies, the economy has had access also for development in Internet industry sphere too. Thanks to this development have appeared: e-money, electronic payment systems, Internet-banking. In the given work the general scheme of works of electronic payment systems, their conditions and function, examples of possible ways of development are presented. In the conclusion the recommendations how it is possible to optimize the market for development of electronic commerce are given and resulted

  1. Electronic control system for irradiation probes

    International Nuclear Information System (INIS)

    Gluza, E.; Neumann, J.; Zahalka, F.

    1980-01-01

    The EROS-78 system for the supply and power control of six heating sections of the irradiation probe of the CHOUCA type placed in the reactor vessel is described. The system allows temperature control at the location of the heat sensor with an accuracy of +-1% of the rated value within the region of 100 to 1000 degC. The equipment is provided with its own quartz controlled clock. The temperature is picked up by a chromel-alumel jacket thermocouple. The power input of the heating elements is thyristor controlled. (J.B.)

  2. System for cooling hybrid vehicle electronics, method for cooling hybrid vehicle electronics

    Energy Technology Data Exchange (ETDEWEB)

    France, David M.; Yu, Wenhua; Singh, Dileep; Zhao, Weihuan

    2017-11-21

    The invention provides a single radiator cooling system for use in hybrid electric vehicles, the system comprising a surface in thermal communication with electronics, and subcooled boiling fluid contacting the surface. The invention also provides a single radiator method for simultaneously cooling electronics and an internal combustion engine in a hybrid electric vehicle, the method comprising separating a coolant fluid into a first portion and a second portion; directing the first portion to the electronics and the second portion to the internal combustion engine for a time sufficient to maintain the temperature of the electronics at or below 175.degree. C.; combining the first and second portion to reestablish the coolant fluid; and treating the reestablished coolant fluid to the single radiator for a time sufficient to decrease the temperature of the reestablished coolant fluid to the temperature it had before separation.

  3. 2D electron systems: Metals in flatland

    Science.gov (United States)

    Annett, James F.

    2012-01-01

    Is it possible for a metal to exist in a strictly two-dimensional system? This may seem trivial, but it is actually a longstanding problem. The electrical characteristics of an array of superconducting islands on a normal metal suggests that the answer could be 'yes'.

  4. Terrestrial radiation effects in ULSI devices and electronic systems

    CERN Document Server

    Ibe, Eishi H

    2014-01-01

    A practical guide on how mathematical approaches can be used to analyze and control radiation effects in semiconductor devices within various environments Covers faults in ULSI devices to failures in electronic systems caused by a wide variety of radiation fields, including electrons, alpha -rays, muons, gamma rays, neutrons and heavy ions. Readers will learn the environmental radiation features at the ground or avionics altitude. Readers will also learn how to make numerical models from physical insight and what kind of mathematical approaches should be implemented to analyze the radiation effects. A wide variety of mitigation techniques against soft-errors are reviewed and discussed. The author shows how to model sophisticated radiation effects in condensed matter in order to quantify and control them. The book provides the reader with the knowledge on a wide variety of radiation fields and their effects on the electronic devices and systems. It explains how electronic systems including servers and rout...

  5. Power Electronics and Reliability in Renewable Energy Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Ma, Ke; Zhou, Dao

    2012-01-01

    Power Electronics are needed in almost all kind of renewable energy systems. It is used both for controlling the renewable source and also for interfacing to the load, which can be grid-connected or working in stand-alone mode. More and more efforts are put into making renewable energy systems...... better in terms of reliability in order to ensure a high availability of the power sources, in this case the knowledge of mission profile of a certain application is crucial for the reliability evaluation/design of power electronics. In this paper an overview on the power electronic circuits behind...... the most common converter configurations for wind turbine and photovoltaic is done. Next different aspects of improving the system reliability are mapped. Further on examples of how to control the chip temperature in different power electronic configurations as well as operation modes for wind power...

  6. Serum 17-hydroxyprogesterone strongly correlates with intratesticular testosterone in gonadotropin-suppressed normal men receiving various dosages of human chorionic gonadotropin

    Science.gov (United States)

    Amory, John K.; Coviello, Andrea D.; Page, Stephanie T.; Anawalt, Bradley D.; Matsumoto, Alvin M.; Bremner, William J.

    2009-01-01

    Objective: To determine if serum concentrations of testosterone precursors would correlate with intratesticular testosterone (ITT) concentration measured directly by testicular aspiration and allow for a less invasive means of inferring ITT. Design: Controlled clinical study. Setting: Healthy volunteers in an academic research environment. Patients: Twenty-nine normal men. Intervention: We determined ITT concentration by testicular aspiration before and after treatment in men receiving exogenous testosterone to block endogenous gonadotropin production and randomly assigned to one of four doses of human chorionic gonadotropin (hCG) (0, 125 IU, 250 IU, 500 IU every other day) for 3 weeks. Outcome measures: The association between serum 17-hydroxyprogesterone, androstenedione and dihydroepiandrosterone (DHEA) and ITT. Results: With testosterone administration alone, serum 17-hydroxyprogesterone decreased significantly and increased significantly when 500 IU hCG was administered. End-of-treatment ITT strongly correlated with serum 17-hydroxyprogesterone. Moreover, serum 17-hydroxyprogesterone, but not androstenedione or DHEA, was independently associated with end-of-treatment ITT by multivariate linear regression. Conclusion: Serum 17-hydroxyprogesterone is highly correlated with ITT in gonadotropin suppressed normal men receiving testosterone and stimulated with hCG. Serum 17-hydroxyprogesterone is a surrogate biomarker of ITT and may be useful in research and in men receiving gonadotropin therapy for infertility. PMID:17462643

  7. Photovoltaic Systems Are With Power Electronics

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Blaabjerg, Frede

    2005-01-01

    In these days of increasing environmental concern, governments and the scientific community work to maximize the use of renewable energy resources. There is a growing recognition of the valuable role solar power can play in reducing pollution - particularly in the effort to stabilize the carbon...... (lEA) Photovoltaic Power Systems (PVPS) countries grew by 36 %, reaching 1,809 MW. The direct conversion of sunlight into electrical energy undoubtedly has the potential to contribute substantially to the world-wide electricity production in the middle and long term....... dioxide levels. The technology is now available for industrial, commercial and residential consumers. Photovoltaic (PV) power supplied to the utility grid is gaining more and more visibility due to many national incentives. With a continuous reduction in system cost (PV modules, dc!ac inverters...

  8. The integration of cryogenic cooling systems with superconducting electronic systems

    International Nuclear Information System (INIS)

    Green, Michael A.

    2003-01-01

    The need for cryogenic cooling has been critical issue that has kept superconducting electronic devices from reaching the market place. Even though the performance of the superconducting circuit is superior to silicon electronics, the requirement for cryogenic cooling has put the superconducting devices at a disadvantage. This report will talk about the various methods for refrigerating superconducting devices. Cryocooler types will be compared for vibration, efficiency, and cost. Some solutions to specific problems of integrating cryocoolers to superconducting devices are presented.

  9. Renewable Energy Systems in the Power Electronics Curriculum

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Chen, Zhe; Teodorescu, Remus

    2005-01-01

    , magnetics, electrical machines, power systems, analogue and digital control, materials, power converters, electronics, materials, thermal design and EMC. However, those fields may not be enough in order to give the students enough skills. It is also necessary to learn about systems and for the moment one...... of the most important area is renewable energy systems. This paper will discuss the basic courses for the power electronics curriculum. It will also discuss how to teach power electronic systems efficiently through a projectoriented and problem-based learning approach with Aalborg University in Denmark...... as a full-scale example. Different project examples will be given as well as important laboratories for adjustable speed drives and renewable energy systems which are used at the university are described....

  10. Data Acquisition System for Electron Energy Loss Coincident Spectrometers

    International Nuclear Information System (INIS)

    Zhang Chi; Yu Xiaoqi; Yang Tao

    2005-01-01

    A Data Acquisition System (DAQ) for electron energy loss coincident spectrometers (EELCS) has been developed. The system is composed of a Multiplex Time-Digital Converter (TDC) that measures the flying time of positive and negative ions and a one-dimension position-sensitive detector that records the energy loss of scattering electrons. The experimental data are buffered in a first-in-first-out (FIFO) memory module, then transferred from the FIFO memory to PC by the USB interface. The DAQ system can record the flying time of several ions in one collision, and allows of different data collection modes. The system has been demonstrated at the Electron Energy Loss Coincident Spectrometers at the Laboratory of Atomic and Molecular Physics, USTC. A detail description of the whole system is given and experimental results shown

  11. Numerical method for inverting 1s2p resonant inelastic x-ray scattering spectra: Interpretation of hidden electronic excitations in CuO

    Czech Academy of Sciences Publication Activity Database

    Dräger, G.; Machek, Pavel

    2009-01-01

    Roč. 79, č. 3 (2009), 033103/1-033103/4 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10100521 Keywords : copper compounds * Fredholm integral equations * numerical analysis * oscillator strengths * strongly correlated electron systems * XANES * X-ray scattering Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

  12. Advanced Power Electronic Interfaces for Distributed Energy Systems Part 1: Systems and Topologies

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, W.; Chakraborty, S.; Kroposki, B.; Thomas, H.

    2008-03-01

    This report summarizes power electronic interfaces for DE applications and the topologies needed for advanced power electronic interfaces. It focuses on photovoltaic, wind, microturbine, fuel cell, internal combustion engine, battery storage, and flywheel storage systems.

  13. Help system for control of JAERI FEL (Free Electron laser)

    International Nuclear Information System (INIS)

    Sugimoto, Masayoshi

    1993-01-01

    The control system of JAERI FEL (Free Electron Laser) has a help system to provide the information necessary to operate the machine and to develop the new user interface. As the control software is constructed on the MS-Windows 3.x, the hyper-text feature of the Windows help system can be accessed. It consists of three major parts: (1) on-line help, (2) full document, and (3) tutorial system. (author)

  14. Electronic firing systems and methods for firing a device

    Science.gov (United States)

    Frickey, Steven J [Boise, ID; Svoboda, John M [Idaho Falls, ID

    2012-04-24

    An electronic firing system comprising a control system, a charging system, an electrical energy storage device, a shock tube firing circuit, a shock tube connector, a blasting cap firing circuit, and a blasting cap connector. The control system controls the charging system, which charges the electrical energy storage device. The control system also controls the shock tube firing circuit and the blasting cap firing circuit. When desired, the control system signals the shock tube firing circuit or blasting cap firing circuit to electrically connect the electrical energy storage device to the shock tube connector or the blasting cap connector respectively.

  15. Cooled electronic system with thermal spreaders coupling electronics cards to cold rails

    Science.gov (United States)

    Chainer, Timothy J; Gaynes, Michael A; Graybill, David P; Iyengar, Madhusudan K; Kamath, Vinod; Kochuparambil, Bejoy J; Schmidt, Roger R; Schultz, Mark D; Simco, Daniel P; Steinke, Mark E

    2013-07-23

    Liquid-cooled electronic systems are provided which include an electronic assembly having an electronics card and a socket with a latch at one end. The latch facilitates securing of the card within the socket or removal of the card from the socket. A liquid-cooled cold rail is disposed at the one end of the socket, and a thermal spreader couples the electronics card to the cold rail. The thermal spreader includes first and second thermal transfer plates coupled to first and second surfaces on opposite sides of the card, and thermally conductive extensions extending from end edges of the plates, which couple the respective transfer plates to the liquid-cooled cold rail. The thermally conductive extensions are disposed to the sides of the latch, and the card is securable within or removable from the socket using the latch without removing the cold rail or the thermal spreader.

  16. National electronic medical records integration on cloud computing system.

    Science.gov (United States)

    Mirza, Hebah; El-Masri, Samir

    2013-01-01

    Few Healthcare providers have an advanced level of Electronic Medical Record (EMR) adoption. Others have a low level and most have no EMR at all. Cloud computing technology is a new emerging technology that has been used in other industry and showed a great success. Despite the great features of Cloud computing, they haven't been utilized fairly yet in healthcare industry. This study presents an innovative Healthcare Cloud Computing system for Integrating Electronic Health Record (EHR). The proposed Cloud system applies the Cloud Computing technology on EHR system, to present a comprehensive EHR integrated environment.

  17. Electronic systems study topics in physics book 8

    CERN Document Server

    Bolton, William

    2013-01-01

    Electronic Systems is concerned with electronic systems such as sine-wave oscillators, amplifiers with negative feedback, operational amplifiers, analogue and digital computers, switching circuits, bistable circuits, and microprocessors. This text is comprised of five chapters; the first of which introduces the basic ideas of a system, feedback, control, and logic gates. Examples of feedback and closed-loop control are given, and the distinction between the effects of positive and negative feedback is described, along with the functions of AND, OR, NOT, NOR, and NAND logic gates. The next chap

  18. CMS Forward Pixel Upgrade Electronics and System Testing

    CERN Document Server

    Weber, Hannsjorg Artur

    2016-01-01

    This note discusses results of electronics and system testing of the CMS forward pixel (FPIX) detector upgrade for Phase 1. The FPIX detector is comprised of four stand-alone half cylinders, each of which contains frontend readout electronic boards, power regulators, cables and fibers in addition to the pixel modules. All of the components undergo rigorous testing and quality assurance before assembly into the half cylinders. Afterwards, we perform full system tests on the completely assembled half cylinders, including calibrations at final operating temperatures, characterization of the realistic readout chain, and system grounding and noise studies. The results from all these tests are discussed.

  19. Electronic security systems better ways to crime prevention

    CERN Document Server

    Walker, Philip

    2013-01-01

    Electronic Security Systems: Better Ways to Crime Prevention teaches the reader about the application of electronics for security purposes through the use of case histories, analogies, anecdotes, and other related materials. The book is divided into three parts. Part 1 covers the concepts behind security systems - its objectives, limitations, and components; the fundamentals of space detection; detection of intruder movement indoors and outdoors; surveillance; and alarm communication and control. Part 2 discusses equipments involved in security systems such as the different types of sensors,

  20. A set of dosimetry systems for electron beam irradiation

    International Nuclear Information System (INIS)

    Lin Min; Lin Jingwen; Chen Yundong; Li Huazhi; Xiao Zhenhong; Gao Juncheng

    1999-01-01

    To follow the rapid development of radiation processing with electron beams, it is urgent to set up a set of dosimetric standards to provide Quality Assurance (QA) of electron beam irradiation and unify the values of the quality of the absorbed dose measurements for electron beams. This report introduces a set of dosimetry systems established in Radiometrology Center of China Institute of Atomic Energy (RCCIAE), which have been or will be used as dosimetric standards in the Nuclear Industry System (NIS) in China. For instance, the potassium (silver) dichromate and ceric-cerous sulfate dosimetry systems will be used as standard dosimeters, while alanine-ESR dosimetry system as a transfer dosimeter, and FJL-01 CTA as a routine dosimeter. (author)

  1. Progress of electron processing system useful for environmental preservation

    International Nuclear Information System (INIS)

    Hoshi, Yasuhisa

    1998-01-01

    Electron Processing has been used in the field of industrial application, mainly to process plastics or polymers, which is represented by the cross-linking of Polyethylene to improve heat resistance. On the other hand, there has been many research studies to use Electron Beam for an environmental preservation. Typical examples are Sterilization of Food, Flue Gas Treatment, Sterilization of Waste Water Sludge, Purification of Water, Removal of Volatile Organic Compound (VOC), etc. These research works have been done in the USA, Germany, Austria, Japan, etc. They reported some of the features of electron beam method. In addition, there is an unique report that the combination of Ozone and Electron Beam provides a better efficiency of the purification of the water. Recently, they have started the investigation for the practical use of Electron Beam in the environmental application. Flue gas treatment is a remarkable example of the investigation. They built the demonstration plant last year and they started the operation last fall. Presently, the system is in a demonstrative operation. This paper will report an outline of the R and D works of environmental applications of Electron Beam and also will introduce the latest technologies of Electron Processing Systems which will be available for the environmental preservation. (author)

  2. A Comparative Study of Electronic Performance Support Systems

    Science.gov (United States)

    Nguyen, Frank; Klein, James D.; Sullivan, Howard

    2005-01-01

    Electronic performance support systems (EPSS) deliver relevant support information to users while they are performing tasks. The present study examined the effect of different types of EPSS on user performance, attitudes, system use and time on task. Employees at a manufacturing company were asked to complete a procedural software task and…

  3. Teaching Case: Analysis of an Electronic Voting System

    Science.gov (United States)

    Thompson, Nik; Toohey, Danny

    2014-01-01

    This teaching case discusses the analysis of an electronic voting system. The development of the case was motivated by research into information security and management, but as it includes procedural aspects, organizational structure and personnel, it is a suitable basis for all aspects of systems analysis, planning and design tasks. The material…

  4. Use of electronic information systems in nursing management.

    Science.gov (United States)

    Lammintakanen, Johanna; Saranto, Kaija; Kivinen, Tuula

    2010-05-01

    The purpose of this study is to describe nurse managers' perceptions of the use of electronic information systems in their daily work. Several kinds of software are used for administrative and information management purposes in health care organizations, but the issue has been studied less from nurse managers' perspective. The material for this qualitative study was acquired according to the principles of focus group interview. Altogether eight focus groups were held with 48 nurse managers from both primary and specialized health care organizations. The nurse managers were asked in focus groups to describe the use of information systems in their daily work in addition to some other themes. The material was analyzed by inductive content analysis using ATLAS.ti computer program. The main category "pros and cons of using information systems in nursing management" summarized the nurse managers' perceptions of using electronic information systems. The main category consisted of three sub-categories: (1) nurse managers' perceptions of the use of information technology; (2) usability of management information systems; (3) development of personnel competencies and work processes. The nurse managers made several comments on the implementation of immature electronic information systems which caused inefficiencies in working processes. However, they considered electronic information systems to be essential elements of their daily work. Furthermore, the nurse managers' descriptions of the pros and cons of using information systems reflected partly the shortcomings of strategic management and lack of coordination in health care organizations. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

  5. Energy Saving and Efficient Energy Use By Power Electronic Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Wang, Huai; Davari, Pooya

    2017-01-01

    , such as in the applications of adjustable speed drives and solid-state lighting systems. Power electronics gives also a high flexibility when renewable power production is introduced to electrical energy systems. Future research opportunities and challenges will finally be discussed....

  6. Renewable Energy Systems in the Power Electronics Curriculum

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Chen, Zhe; Teodorescu, Remus

    2005-01-01

    , magnetics, electrical machines, power systems, analogue and digital control, materials, power converters, electronics, materials, thermal design and EMC. However, those fields may not be enough in order to give the students enough skills. It is also necessary to learn about systems and for the moment one...

  7. Design of automatic tracking system for electron beam welding

    International Nuclear Information System (INIS)

    He Chengdan; Chinese Academy of Space Technology, Lanzhou; Li Heqi; Li Chunxu; Ying Lei; Luo Yan

    2004-01-01

    The design and experimental process of an automatic tracking system applied to local vacuum electron beam welding are dealt with in this paper. When the annular parts of an exactitude apparatus were welded, the centre of rotation of the electron gun and the centre of the annular weld are usually not superposed because of the machining error, workpiece's setting error and so on. In this teaching process, a little bundle of electron beam is used to scan the weld groove, the amount of the secondary electrons reflected from the workpiece is different when the electron beam scans the both sides and the centre of the weld groove. The difference can indicate the position of the weld and then a computer will record the deviation between the electron beam spot and the centre of the weld groove. The computer will analyze the data and put the data into the storage software. During the welding process, the computer will modify the position of the electron gun based on the deviation to make the electron beam spot centered on the annular weld groove. (authors)

  8. International Conference on Power Electronics and Renewable Energy Systems

    CERN Document Server

    Suresh, L; Dash, Subhransu; Panigrahi, Bijaya

    2015-01-01

    The book is a collection of high-quality peer-reviewed research papers presented in Proceedings of International Conference on Power Electronics and Renewable Energy Systems (ICPERES 2014) held at Rajalakshmi Engineering College, Chennai, India. These research papers provide the latest developments in the broad area of Power Electronics and Renewable Energy. The book discusses wide variety of industrial, engineering and scientific applications of the emerging techniques. It presents invited papers from the inventors/originators of new applications and advanced technologies.

  9. 2D electron systems viewed through an RF spectrometer

    International Nuclear Information System (INIS)

    Andrei, E.Y.

    1994-01-01

    Electrons trapped at the liquid helium-vacuum interface are an almost ideal realization of a 2D electron system. I will describe experiments probing the in-plane as well as the out-of-plane motion of the electrons. The former have emphasized the dynamics and thermodynamics of the electronic motion within the plane to understand the nature of the liquid-solid transition and to outline its phase boundary. The latter have studied the escape out of the electron layer and provided an opportunity to observe tunneling in a clean and well-characterized system as well as to measure the effects of correlations on the tunneling process. More recently experiments in the presence of a magnetic field transverse to the direction of tunneling have revealed several novel phenomena associated with the magnetic coupling between the in-plane and the out-of-plane electronic motions. Together, these experiments helped uncover the multi-faceted physics that can be found in this system. (orig.)

  10. 78 FR 13546 - Defense Federal Acquisition Regulation Supplement; Electronic Subcontracting Reporting System

    Science.gov (United States)

    2013-02-28

    ... Regulation Supplement; Electronic Subcontracting Reporting System AGENCY: Defense Acquisition Regulations... the FAR regarding policy and procedures related to the Electronic Subcontracting Reporting System... procedures and policies related to the Electronic Subcontracting Reporting System (eSRS). There were no...

  11. Energy Saving and Efficient Energy Use By Power Electronic Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Wang, Huai; Davari, Pooya

    2017-01-01

    energy in different applications. This chapter will give an overview of challenges and possibilities in terms of energy saving and also energy efficient use. This includes a discussion on high efficiency power electronics devices and the systems they are used for energy loss reduction. The key enabling......In the development of the modern society, one of the key factors is to save energy in order to become more independent of other energy resources. Two important approaches can be taken—one is to change behavior and thereby save energy—the second one is to develop new technology which is able to save...... technologies are power electronics, Information and Communication Technology (ICT) as well as systems to carry the electrical energy through power transmission, conversion and distribution. A couple of examples will be given to demonstrate the energy saving possibilities by power electronics systems...

  12. Existence of time-dependent density-functional theory for open electronic systems: time-dependent holographic electron density theorem.

    Science.gov (United States)

    Zheng, Xiao; Yam, ChiYung; Wang, Fan; Chen, GuanHua

    2011-08-28

    We present the time-dependent holographic electron density theorem (TD-HEDT), which lays the foundation of time-dependent density-functional theory (TDDFT) for open electronic systems. For any finite electronic system, the TD-HEDT formally establishes a one-to-one correspondence between the electron density inside any finite subsystem and the time-dependent external potential. As a result, any electronic property of an open system in principle can be determined uniquely by the electron density function inside the open region. Implications of the TD-HEDT on the practicality of TDDFT are also discussed.

  13. Feasibility demonstration of a second-generation electronic monitoring system

    Science.gov (United States)

    Murphy, John H.

    1997-02-01

    First generation electronic monitoring systems are being used by the criminal justice system to effect behavioral modifications of persons in pre-trial release programs, on parole, and on probation. Current systems are merely radio frequency proximity detection systems that operate over limited ranges, on the order of 45 to 70 meters. One major defect with proximity detection systems is that when the offenders leave the area being monitored, there is no way to ensure that the offenders travel where they should. As a result, the first generation electronic monitoring systems are only applied to a restricted number of low risk cases. There is a growing need for a second generation electronic monitoring system which utilizes community-wide tracking and location technologies to increase the public safety and to expand the number of offenders monitored by these systems. Even though GPS (Global Positioning System) is rapidly becoming the technology of choice for vehicle tracking and location, GPS is not an ideal candidate for the second generation electronic monitoring system. Urban environments prevent GPS systems from providing continuous and accurate location service due to satellite occlusion by obstacles such as: hills, mountains, vehicles, buildings, and trees. An inverse-GPS approach which overcomes these urban environment related limitations has been evaluated by Northrop Grumman as a means to track people. This paper presents the results of a National Institute of Justice funded program to demonstrate in downtown Pittsburgh the feasibility of spread spectrum based time-of-arrival location systems for intelligently tracking people on probation and parole.

  14. The shipboard employment of a free electron laser weapon system

    OpenAIRE

    Allgaier, Gregory G.

    2003-01-01

    Approved for Public Release; Distribution is Unlimited A megawatt (MW) class Free Electron Laser (FEL) shows promise as a new weapon for antiship cruise missile defense. An FEL weapon system delivers energy at the speed of light at controllable energy levels, giving the war fighter new engagement options. Considerations for this weapon system include employment, design, and stability. In order to reach a MW class laser, system parameters must be optimized and the high power optical beam mu...

  15. Phase synchronized quasiperiodicity in power electronic inverter systems

    DEFF Research Database (Denmark)

    Zhusubaliyev, Zhanybai T.; Mosekilde, Erik; Andriyanov, Alexey I.

    2014-01-01

    The development of switch-mode operated power electronic converter systems has provided a broad range of new effective approaches to the conversion of electric power. In this paper we describe the transitions from regular periodic operation to quasiperiodicity and high-periodic resonance behavior...... findings are verified through comparison with an experimental inverter system. The results shed light on the transitions to quasiperiodicity and to various forms of three-frequency dynamics in non-smooth systems....

  16. Compact pulsed electron beam system for microwave generation

    Science.gov (United States)

    Sharma, S. K.; Deb, P.; Shukla, R.; Banerjee, P.; Prabaharan, T.; Adhikary, B.; Verma, R.; Sharma, A.; Shyam, A.

    2012-11-01

    A compact 180 kV electron beam system is designed for high power microwave generation. The electron beam system is consists of a secondary energy storage device, which can deliver energy to the load at faster rate than usual primary energy storage system such as tesla transformers or marx generator. The short duration, high voltage pulse with fast rise time and good flattop is applied to vacuum diode for high power microwave generation. The compact electron beam system is made up of single turn primary tesla transformer which charges a helical pulse forming line and transfers its energy to vacuum diode through a high voltage pressurized spark gap switch. We have used helical pulse forming line which has higher inductance as compared to coaxial pulse forming line, which in turns increases, the pulse width and reduce the length of the pulse forming line. Water dielectric medium is used because of its high dielectric constant, high dielectric strength and efficient energy storage capability. The time dependent breakdown property and high relative permittivity of water makes it an ideal choice for this system. The high voltage flat-top pulse of 90 kV, 260 ns is measured across the matched load. In this article we have reported the design details, simulation and initial experimental results of 180 kV pulsed electron beam system for high power microwave generation.

  17. A Thermoelectric Generation System and Its Power Electronics Stage

    Science.gov (United States)

    Gao, Junling; Sun, Kai; Ni, Longxian; Chen, Min; Kang, Zhengdong; Zhang, Li; Xing, Yan; Zhang, Jianzhong

    2012-06-01

    The electricity produced by a thermoelectric generator (TEG) must satisfy the requirements of specific loads given the signal level, stability, and power performance. In the design of such systems, one major challenge involves the interactions between the thermoelectric power source and the power stage and signal-conditioning circuits of the load, including DC-DC conversion, the maximum power point tracking (MPPT) controller, and other power management controllers. In this paper, a survey of existing power electronics designs for TEG systems is presented first. Second, a flat, wall-like TEG system consisting of 32 modules is experimentally optimized, and the improved power parameters are tested. Power-conditioning circuitry based on an interleaved boost DC-DC converter is then developed for the TEG system in terms of the tested power specification. The power electronics design features a combined control scheme with an MPPT and a constant output voltage as well as the low-voltage and high-current output characteristics of the TEG system. The experimental results of the TEG system with the power electronics stage and with purely resistive loads are compared. The comparisons verify the feasibility and effectiveness of the proposed design. Finally, the thermal-electric coupling effects caused by current-related heat source terms, such as the Peltier effect etc., are reported and discussed, and the potential influence on the power electronics design due to such coupling is analyzed.

  18. Electronic properties of graphene-based bilayer systems

    Energy Technology Data Exchange (ETDEWEB)

    Rozhkov, A.V., E-mail: arozhkov@gmail.com [CEMS, RIKEN, Saitama 351-0198 (Japan); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412 Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700 (Russian Federation); Sboychakov, A.O. [CEMS, RIKEN, Saitama 351-0198 (Japan); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412 Moscow (Russian Federation); Rakhmanov, A.L. [CEMS, RIKEN, Saitama 351-0198 (Japan); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412 Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700 (Russian Federation); All-Russia Research Institute of Automatics, Moscow, 127055 (Russian Federation); Nori, Franco, E-mail: fnori@riken.jp [CEMS, RIKEN, Saitama 351-0198 (Japan); Physics Department, The University of Michigan, Ann Arbor, MI 48109-1040 (United States)

    2016-08-23

    This article reviews the theoretical and experimental work related to the electronic properties of bilayer graphene systems. Three types of bilayer stackings are discussed: the AA, AB, and twisted bilayer graphene. This review covers single-electron properties, effects of static electric and magnetic fields, bilayer-based mesoscopic systems, spin–orbit coupling, dc transport and optical response, as well as spontaneous symmetry violation and other interaction effects. The selection of the material aims to introduce the reader to the most commonly studied topics of theoretical and experimental research in bilayer graphene.

  19. Radiation Testing of Electronics for the CMS Endcap Muon System

    CERN Document Server

    INSPIRE-00070357; Celik, A.; Durkin, L.S.; Gilmore, J.; Haley, J.; Khotilovich, V.; Lakdawala, S.; Liu, J.; Matveev, M.; Padley, B.P.; Roberts, J.; Roe, J.; Safonov, A.; Suarez, I.; Wood, D.; Zawisza, I.

    2013-01-01

    The electronics used in the data readout and triggering system for the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) particle accelerator at CERN are exposed to high radiation levels. This radiation can cause permanent damage to the electronic circuitry, as well as temporary effects such as data corruption induced by Single Event Upsets. Once the High Luminosity LHC (HL-LHC) accelerator upgrades are completed it will have five times higher instantaneous luminosity than LHC, allowing for detection of rare physics processes, new particles and interactions. Tests have been performed to determine the effects of radiation on the electronic components to be used for the Endcap Muon electronics project currently being designed for installation in the CMS experiment in 2013. During these tests the digital components on the test boards were operating with active data readout while being irradiated with 55 MeV protons. In reactor tests, components were exposed to 30 years equivalent levels o...

  20. Challenges in implementing electronic hand hygiene monitoring systems.

    Science.gov (United States)

    Conway, Laurie J

    2016-05-02

    Electronic hand hygiene (HH) monitoring systems offer the exciting prospect of a more precise, less biased measure of HH performance than direct observation. However, electronic systems are challenging to implement. Selecting a system that minimizes disruption to the physical infrastructure and to clinician workflow, and that fits with the organization's culture and budget, is challenging. Getting front-line workers' buy-in and addressing concerns about the accuracy of the system and how the data will be used are also difficult challenges. Finally, ensuring information from the system reaches front-line workers and is used by them to improve HH practice is a complex challenge. We describe these challenges in detail and suggests ways to overcome them. Copyright © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  1. Probing few nucleon systems with photons and electrons

    International Nuclear Information System (INIS)

    Mukherjee, S.N.

    1988-01-01

    Several of the interesting radiative and electron scattering processes involving few nucleon systems at medium energies are discussed, with emphasis on what is interesting about the reaction, what is currently known both theoretically and experimentally, and what should be done next. One body systems yield fundamental particle properties, two-body (A = 2) systems fix the interaction between nucleons, and their couplings. The next goal is then to predict properties of A > 2 system in terms of dynamical theories whose parameters are determined by A ≤2 systems. Reactions with photons and electrons have been singled out because electromagnetic interaction is sufficiently well understood, it is weak and hence can be treated as perturbation. Failures to reproduce experimental results raises questions about the correctness of theoretical technique used, presence of three body forces and even to speculations that explicit quark degrees of freedom might be required. (author). 24 refs., 7 figs

  2. A decision technology system for health care electronic commerce.

    Science.gov (United States)

    Forgionne, G A; Gangopadhyay, A; Klein, J A; Eckhardt, R

    1999-08-01

    Mounting costs have escalated the pressure on health care providers and payers to improve decision making and control expenses. Transactions to form the needed decision data will routinely flow, often electronically, between the affected parties. Conventional health care information systems facilitate flow, process transactions, and generate useful decision information. Typically, such support is offered through a series of stand-alone systems that lose much useful decision knowledge and wisdom during health care electronic commerce (e-commerce). Integrating the stand-alone functions can enhance the quality and efficiency of the segmented support, create synergistic effects, and augment decision-making performance and value for both providers and payers. This article presents an information system that can provide complete and integrated support for e-commerce-based health care decision making. The article describes health care e-commerce, presents the system, examines the system's potential use and benefits, and draws implications for health care management and practice.

  3. An automatic chip structure optical inspection system for electronic components

    Science.gov (United States)

    Song, Zhichao; Xue, Bindang; Liang, Jiyuan; Wang, Ke; Chen, Junzhang; Liu, Yunhe

    2018-01-01

    An automatic chip structure inspection system based on machine vision is presented to ensure the reliability of electronic components. It consists of four major modules, including a metallographic microscope, a Gigabit Ethernet high-resolution camera, a control system and a high performance computer. An auto-focusing technique is presented to solve the problem that the chip surface is not on the same focusing surface under the high magnification of the microscope. A panoramic high-resolution image stitching algorithm is adopted to deal with the contradiction between resolution and field of view, caused by different sizes of electronic components. In addition, we establish a database to storage and callback appropriate parameters to ensure the consistency of chip images of electronic components with the same model. We use image change detection technology to realize the detection of chip images of electronic components. The system can achieve high-resolution imaging for chips of electronic components with various sizes, and clearly imaging for the surface of chip with different horizontal and standardized imaging for ones with the same model, and can recognize chip defects.

  4. Intermolecular thermoelectric-like effects in molecular nano electronic systems

    International Nuclear Information System (INIS)

    Sabzyan, H.; Safari, R.

    2012-01-01

    Intramolecular thermoelectric-like coefficients are introduced and computed of a single molecule nano electronic system. Values of the electronic Intramolecular thermoelectric-like coefficients are calculated based on the density and energy transfers between different parts of the molecule using quantum theory of atoms in molecule. Since, Joule and Peltier heating are even (symmetrical) and odd (antisymmetric) functions of the external bias, it is possible to divide Intramolecular thermoelectric-like coefficients into two components, symmetrical and antisymmetrical Intramolecular thermoelectric-like coefficients, which describe the intramolecular Joule-like and Peltier-like effects, respectively. In addition, a semiclassical temperature model is presented to describe intramolecular temperature mapping (intramolecular energy distributions) in molecular nano electronic systems.

  5. Modeling power electronics and interfacing energy conversion systems

    CERN Document Server

    Simões, Marcelo Godoy

    2017-01-01

    Discusses the application of mathematical and engineering tools for modeling, simulation and control oriented for energy systems, power electronics and renewable energy. This book builds on the background knowledge of electrical circuits, control of dc/dc converters and inverters, energy conversion and power electronics. The book shows readers how to apply computational methods for multi-domain simulation of energy systems and power electronics engineering problems. Each chapter has a brief introduction on the theoretical background, a description of the problems to be solved, and objectives to be achieved. Block diagrams, electrical circuits, mathematical analysis or computer code are covered. Each chapter concludes with discussions on what should be learned, suggestions for further studies and even some experimental work.

  6. Electron energy-loss spectroscopy of coupled plasmonic systems: beyond the standard electron perspective

    Science.gov (United States)

    Bernasconi, G. D.; Flauraud, V.; Alexander, D. T. L.; Brugger, J.; Martin, O. J. F.; Butet, J.

    2016-09-01

    Electron energy-loss spectroscopy (EELS) has become an experimental method of choice for the investigation of localized surface plasmon resonances, allowing the simultaneous mapping of the associated field distributions and their resonant energies with a nanoscale spatial resolution. The experimental observations have been well-supported by numerical models based on the computation of the Lorentz force acting on the impinging electrons by the scattered field. However, in this framework, the influence of the intrinsic properties of the plasmonic nanostructures studied with the electron energy-loss (EEL) measurements is somehow hidden in the global response. To overcome this limitation, we propose to go beyond this standard, and well-established, electron perspective and instead to interpret the EELS data using directly the intrinsic properties of the nanostructures, without regard to the force acting on the electron. The proposed method is particularly well-suited for the description of coupled plasmonic systems, because the role played by each individual nanoparticle in the observed EEL spectrum can be clearly disentangled, enabling a more subtle understanding of the underlying physical processes. As examples, we consider different plasmonic geometries in order to emphasize the benefits of this new conceptual approach for interpreting experimental EELS data. In particular, we use it to describe results from samples made by traditional thin film patterning and by arranging colloidal nanostructures.

  7. Electronic circuit detects left ventricular ejection events in cardiovascular system

    Science.gov (United States)

    Gebben, V. D.; Webb, J. A., Jr.

    1972-01-01

    Electronic circuit processes arterial blood pressure waveform to produce discrete signals that coincide with beginning and end of left ventricular ejection. Output signals provide timing signals for computers that monitor cardiovascular systems. Circuit operates reliably for heart rates between 50 and 200 beats per minute.

  8. a framework for semantic driven electronic examination system for ...

    African Journals Online (AJOL)

    HOD

    equipment and devices for an assessment or evaluation of knowledge [13]. It is an assessment approach meditated by ... through the computer system where responses are electronically recorded and assessed [13]. The aim is ..... Computer-Based Test: Security and Result. Integrity. International Journal of Computer and.

  9. Electronic Payment System in Nigeria: Its Economic Benefits and Challenges

    Science.gov (United States)

    Okifo, Joseph; Igbunu, Richard

    2015-01-01

    The crux of this study is on the adoption of E-payment system in Nigeria: Its economic benefits and challenges. The arrival of the internet has taken electronic payments and transactions to an exponential growth level. Consumers could purchase goods and services from the internet and send unencrypted credit card numbers across the network, which…

  10. Measuring and recording system for electron beam welding parameters

    International Nuclear Information System (INIS)

    Lobanova, N.G.; Lifshits, M.L.; Efimov, I.I.

    1987-01-01

    The observation possibility during electron beam welding of circular articles with guaranteed clearance of welding bath leading front in joint gap and flare cloud over the bath by means of television monitor is considered. The composition and operation mode of television measuring system for metric characteristics of flare cloud and altitude of welding bath leading front in the clearance are described

  11. Redesigning a collection system for "small" consumer electronics

    NARCIS (Netherlands)

    Melissen, Franciscus

    2006-01-01

    This paper establishes that the collection system within the recycling scheme for consumer electronics in the Netherlands has not been entirely successful in convincing consumers to hand in their used appliances by means of dedicated collection routes. Particularly regarding small appliances,

  12. Impact of CALS on Electronic Publishing Systems and Users.

    Science.gov (United States)

    Beazley, William G.

    1990-01-01

    The U.S. Department of Defense has begun using its buying power to enforce standards on the vendors and contractors of automatic data processing hardware and software. An example of this, the Computer-Aided Acquisition and Logistic Support (CALS) program, is described, and how it will affect electronic publishing systems is discussed. (five…

  13. An Electronic Dictionary and Translation System for Murrinh-Patha

    Science.gov (United States)

    Seiss, Melanie; Nordlinger, Rachel

    2012-01-01

    This paper presents an electronic dictionary and translation system for the Australian language Murrinh-Patha. Its complex verbal structure makes learning Murrinh-Patha very difficult. Design learning materials or a dictionary which is easy to understand and to use also presents a challenge. This paper discusses some of the difficulties posed by…

  14. Electronics system design techniques for safety critical applications

    CERN Document Server

    Sterpone, Luca

    2008-01-01

    Addresses the development of techniques for the evaluation and the hardening of designs implemented on SRAM-based Field Programmable Gate Arrays. This title presents a design methodology solving industrial designer''s needs for implementing electronic systems using SRAM-based FPGAs in critical environments, like the space or avionic ones.

  15. Security of Electronic Payment Systems Based on Digital Money

    Directory of Open Access Journals (Sweden)

    A. B. Vavrenyuk

    2011-12-01

    Full Text Available Electronic payment systems based on digital money are evaluated in terms of information protection. Mechanisms of protection of interests of bank-emitter, buyer and seller are described. Course of life of a digital denomination is resulted: transactions of removal from the account, purchase and transfer into the account.

  16. A security analysis of the Dutch electronic patient record system

    NARCIS (Netherlands)

    van 't Noordende, G.

    2010-01-01

    In this article, we analyze the security architecture of the Dutch Electronic Patient Dossier (EPD) system. Intended as a national infrastructure for exchanging medical patient records among authorized parties (particularly, physicians), the EPD has to address a number of requirements, ranging from

  17. Security in the Dutch electronic patient record system

    NARCIS (Netherlands)

    van 't Noordende, G.

    2010-01-01

    In this article, we analyze the security architecture of the Dutch Electronic Patient Dossier (EPD) system. Intended as a mandatory infrastructure for exchanging medical records of most if not all patients in the Netherlands among authorized parties (particularly, physicians), the EPD has to address

  18. Factors affecting the utilisation of electronic medical records system ...

    African Journals Online (AJOL)

    knowledge and skills needed for electronic record-keeping. Paper-based record systems can ... In Malawi, paper-based medical record-keeping has been observed to exacerbate challenges related to accessing patient records and ..... Med. 2010;7(8). 7. WHO. Management of Patient Information Trends and Challenges in.

  19. Designing a framework for a unified electronic identity system ...

    African Journals Online (AJOL)

    In this paper, a Unified Identity System is proposed where single electronic identity (eID) is issued that can be used across the various platforms of business transaction. The activity/state diagram of the model is presented, and the means of authentication is based on the Secure Assertion Markup Language (SAML) ...

  20. Electronic clinical safety reporting system: a benefits evaluation.

    Science.gov (United States)

    Elliott, Pamela; Martin, Desmond; Neville, Doreen

    2014-06-11

    Eastern Health, a large health care organization in Newfoundland and Labrador (NL), started a staged implementation of an electronic occurrence reporting system (used interchangeably with "clinical safety reporting system") in 2008, completing Phase One in 2009. The electronic clinical safety reporting system (CSRS) was designed to replace a paper-based system. The CSRS involves reporting on occurrences such as falls, safety/security issues, medication errors, treatment and procedural mishaps, medical equipment malfunctions, and close calls. The electronic system was purchased from a vendor in the United Kingdom that had implemented the system in the United Kingdom and other places, such as British Columbia. The main objective of the new system was to improve the reporting process with the goal of improving clinical safety. The project was funded jointly by Eastern Health and Canada Health Infoway. The objectives of the evaluation were to: (1) assess the CSRS on achieving its stated objectives (particularly, the benefits realized and lessons learned), and (2) identify contributions, if any, that can be made to the emerging field of electronic clinical safety reporting. The evaluation involved mixed methods, including extensive stakeholder participation, pre/post comparative study design, and triangulation of data where possible. The data were collected from several sources, such as project documentation, occurrence reporting records, stakeholder workshops, surveys, focus groups, and key informant interviews. The findings provided evidence that frontline staff and managers support the CSRS, identifying both benefits and areas for improvement. Many benefits were realized, such as increases in the number of occurrences reported, in occurrences reported within 48 hours, in occurrences reported by staff other than registered nurses, in close calls reported, and improved timelines for notification. There was also user satisfaction with the tool regarding ease of use

  1. Implementation of the electronic DDA workflow for NSSS system design

    International Nuclear Information System (INIS)

    Eom, Young Sam; Kim, Yeon Sung; Lee, Suk Hee; Kim, Mi Kyung

    1996-06-01

    For improving NSSS design quality, and productivity several cases of the nuclear developed nation's integrated management system, such as Mitsubishi's NUWINGS (Japan), AECL's CANDID (Canada) and Duke Powes's (USA) were investigated, and it was studied in this report that the system implementation of NSSS design document computerization and the major workflow process of the DDA (Document Distribution for Agreement). On the basis of the requirements of design document computerization which covered preparation, review, approval and distribution of the engineering documents, KAERI Engineering Information Management System (KEIMS) was implemented. Major effects of this report are to implement GUI panel for input and retrieval of the document index information, to setup electronic document workflow, and to provide quality assurance verification by tracing the workflow history. Major effects of NSSS design document computerization are the improvement of efficiency and reliability and the engineering cost reduction by means of the fast documents verification capability and electronic document transferring system. 2 tabs., 16 figs., 9 refs. (Author)

  2. New Electronic-Transition Laser Systems. Part I. Electron Pumped Systems

    Science.gov (United States)

    1976-05-01

    important reaction intermediates could absorb the laser photons. Because of their low concentration , this may not affect the gain, but photo...recording the electronic signals from a fast phototube (generally a 1P28. coated, if necessary, with sodium salicylate for vacuum-uv measurements...state ot 1^ which radiates at 342.5 nm, very effectively, concentrates the energy flow from the intermediate atomic states and thereby provides the

  3. Radiation testing of electronics for the CMS endcap muon system

    Science.gov (United States)

    Bylsma, B.; Cady, D.; Celik, A.; Durkin, L. S.; Gilmore, J.; Haley, J.; Khotilovich, V.; Lakdawala, S.; Liu, J.; Matveev, M.; Padley, B. P.; Roberts, J.; Roe, J.; Safonov, A.; Suarez, I.; Wood, D.; Zawisza, I.

    2013-01-01

    The electronics used in the data readout and triggering system for the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) particle accelerator at CERN are exposed to high radiation levels. This radiation can cause permanent damage to the electronic circuitry, as well as temporary effects such as data corruption induced by Single Event Upsets. Once the High Luminosity LHC (HL-LHC) accelerator upgrades are completed it will have five times higher instantaneous luminosity than LHC, allowing for detection of rare physics processes, new particles and interactions. Tests have been performed to determine the effects of radiation on the electronic components to be used for the Endcap Muon electronics project currently being designed for installation in the CMS experiment in 2013. During these tests the digital components on the test boards were operating with active data readout while being irradiated with 55 MeV protons. In reactor tests, components were exposed to 30 years equivalent levels of neutron radiation expected at the HL-LHC. The highest total ionizing dose (TID) for the muon system is expected at the innermost portion of the CMS detector, with 8900 rad over 10 years. Our results show that Commercial Off-The-Shelf (COTS) components selected for the new electronics will operate reliably in the CMS radiation environment.

  4. Beyond electronic disintermediation through multi-agent systems

    OpenAIRE

    Nissen, Mark E.

    2001-01-01

    Supply chain management represents a critical competency in today's global business environment and has been the focus of considerable, but mixed, information systems research. The research described in this paper builds on work in multi-agent systems to argue that intelligent agents offer excellent potential and capability for supply chain management, and contributes to discussion and theory pertaining to electronic markets and supply chain disintermediation. Argues t...

  5. Double deflection system for an electron beam device

    International Nuclear Information System (INIS)

    Parker, N.W.; Crewe, A.V.

    1978-01-01

    A double deflection scanning system for electron beam instruments is provided embodying a means of correcting isotropic coma, and anisotropic coma aberrations induced by the magnetic lens of such an instrument. The scanning system deflects the beam prior to entry into the magnetic lens from the normal on-axis intersection of the beam with the lens according to predetermined formulas and thereby reduces the aberrations

  6. The upper level of control system of electron accelerators

    International Nuclear Information System (INIS)

    Gribov, I.V.; Nedeoglo, F.N.; Shvedunov, I.V.

    2005-01-01

    The upper level software of a three-level control system that supports several electron accelerators is described. This software operates in the Linux and RTLinux (Real Time Linux) environment. The object information model functions on the basis of a parametric description supported by the SQLite Data Base Management System. The Javascript sublanguage is used for script forming, and the Qt Designer application is used to construct the user interface [ru

  7. System Electronics for the ATLAS Upgraded Strip Detector

    CERN Document Server

    Affolder, T; The ATLAS collaboration; Clark, A; Dabrowskic, W; Dewitt, J; Diez Cornell, S; Dressdant, N; Fadeyev, V; Farthouat, P; Ferrere, D; Greenall, A; Grillo, A; Kaplon, J; Key-Charriere, M; La Marra, D; Lipeles, E; Lynn, D; Newcomer, M; Pereirab, F; Phillips, P; Spencer, E; Swientekc, K; Warren, M; Weidberg, A

    2013-01-01

    The basic concept of the front-end system of the Silicon Strip Detector in the Atlas Detector upgraded for the HL-LHC is being elaborated and proposed. The readout electronics of this new detector is based on front-end chips (ABC130), Hybrid Controller chips (HCC) and End of Stave Controller chips (EOSC). This document defines the basic functionality of the front-end system and of the different ASICs.

  8. Development of control system for the electron gun modulator

    International Nuclear Information System (INIS)

    Hasegawa, T.; Nagasawa, S.; Kobayashi, T.; Hanaki, H.

    2004-01-01

    We have been developing a compact and inexpensive electron gun modulator for the SPring-8 Linac. The modulator was redesigned and manufactured to achieve good maintainability and high controllability. A control system of the modulator and a high voltage station is composed mainly of PLCs as a controller and touch panels for human interface. This simplified construction will result in enhancement of its reliability. The rich graphical user interface on the touch panels greatly extends the function of the control system. (author)

  9. STRATEGY FOR EVALUATION AND SELECTION OF SYSTEMS FOR ELECTRONIC LEARNING

    Directory of Open Access Journals (Sweden)

    Dubravka Mandušić

    2012-12-01

    Full Text Available Today`s technology supported and accelerated learning time requires constant and continuous acquisition of new knowledge. On the other hand, it does not leave enough time for additional education. Increasing number of E-learning systems, withdraws a need for precise evaluation of functionality that those systems provide; so they could be reciprocally compared. While implementing new systems for electronic learning, it is very important to pre-evaluate existing systems in order to select the one that meets all defined parameters, with low costs/investment. Proper evaluation can save time and money.

  10. Subsecond Tsunamis and Delays in Decentralized Electronic Systems

    Directory of Open Access Journals (Sweden)

    Pedro D. Manrique

    2017-10-01

    Full Text Available Driven by technological advances and economic gain, society’s electronic systems are becoming larger, faster, more decentralized and autonomous, and yet with increasing global reach. A prime example are the networks of financial markets which—in contrast to popular perception—are largely all-electronic and decentralized with no top-down real-time controller. This prototypical system generates complex subsecond dynamics that emerge from a decentralized network comprising heterogeneous hardware and software components, communications links, and a diverse ecology of trading algorithms that operate and compete within this all-electronics environment. Indeed, these same technological and economic drivers are likely to generate a similarly competitive all-electronic ecology in a variety of future cyberphysical domains such as e-commerce, defense and the transportation system, including the likely appearance of large numbers of autonomous vehicles on the streets of many cities. Hence there is an urgent need to deepen our understanding of stability, safety and security across a wide range of ultrafast, large, decentralized all-electronic systems—in short, society will eventually need to understand what extreme behaviors can occur, why, and what might be the impact of both intentional and unintentional system perturbations. Here we set out a framework for addressing this issue, using a generic model of heterogeneous, adaptive, autonomous components where each has a realistic limit on the amount of information and processing power available to it. We focus on the specific impact of delayed information, possibly through an accidental shift in the latency of information transmission, or an intentional attack from the outside. While much remains to be done in terms of developing formal mathematical results for this system, our preliminary results indicate the type of impact that can occur and the structure of a mathematical theory which may

  11. Electron-assisted magnetization tunneling in single spin systems

    Science.gov (United States)

    Balashov, Timofey; Karlewski, Christian; Märkl, Tobias; Schön, Gerd; Wulfhekel, Wulf

    2018-01-01

    Magnetic excitations of single atoms on surfaces have been widely studied experimentally in the past decade. Lately, systems with unprecedented magnetic stability started to emerge. Here, we present a general theoretical investigation of the stability of rare-earth magnetic atoms exposed to crystal or ligand fields of various symmetry and to exchange scattering with an electron bath. By analyzing the properties of the atomic wave function, we show that certain combinations of symmetry and total angular momentum are inherently stable against first or even higher-order interactions with electrons. Further, we investigate the effect of an external magnetic field on the magnetic stability.

  12. International Conference on Nano-electronics, Circuits & Communication Systems

    CERN Document Server

    2017-01-01

    This volume comprises select papers from the International Conference on Nano-electronics, Circuits & Communication Systems(NCCS). The conference focused on the frontier issues and their applications in business, academia, industry, and other allied areas. This international conference aimed to bring together scientists, researchers, engineers from academia and industry. The book covers technological developments and current trends in key areas such as VLSI design, IC manufacturing, and applications such as communications, ICT, and hybrid electronics. The contents of this volume will prove useful to researchers, professionals, and students alike.

  13. Nonlinear behaviors of a bounded electron beam-plasma system

    International Nuclear Information System (INIS)

    Iizuka, Satoru; Saeki, Koichi; Sato, Noriyoshi; Hatta, Yoshisuke

    1985-01-01

    Nonlinear developments of a bounded electron beam-plasma system including stationary electrons are investigated experimentally. A stable double layer is formed as a result of ion trapping in a growing negative potential dip induced by the Pierce instability above the current regime of the Buneman instability. In the in-between regime of the Buneman and Pierce instabilities, energetic ions are observed. This effective ion heating is caused by ion detrapping due to double-layer disruption, being consistent with computer simulation. (author)

  14. Electronic circuits, systems and standards the best of EDN

    CERN Document Server

    Hickman, Ian

    2013-01-01

    Electronic Circuits, Systems and Standards: The Best of EDN is a collection of 66 EDN articles. The topics covered in this collection are diverse but all are relevant to controlled circulation electronics. The coverage of the text includes topics about software and algorithms, such as simple random number algorithm; simple log algorithm; and efficient algorithm for repeated FFTs. The book also tackles measurement related topics, including test for identifying a Gaussian noise source; enhancing product reliability; and amplitude-locked loop speeds filter test. The text will be useful to student

  15. Electronic health record standards, coding systems, frameworks, and infrastructures

    CERN Document Server

    Sinha, Pradeep K; Bendale, Prashant; Mantri, Manisha; Dande, Atreya

    2013-01-01

    Discover How Electronic Health Records Are Built to Drive the Next Generation of Healthcare Delivery The increased role of IT in the healthcare sector has led to the coining of a new phrase ""health informatics,"" which deals with the use of IT for better healthcare services. Health informatics applications often involve maintaining the health records of individuals, in digital form, which is referred to as an Electronic Health Record (EHR). Building and implementing an EHR infrastructure requires an understanding of healthcare standards, coding systems, and frameworks. This book provides an

  16. Magnetic impurity in a system of interacting electrons

    International Nuclear Information System (INIS)

    Huynh Thanh Duc; Nguyen Toan Thang

    1999-04-01

    The Kondo effect of the Anderson impurity in a correlated conduction electron system is studied within the slave boson mean-field theory. The interacting conduction electrons are described by a Hubbard model with an interaction of strength U. It is shown that the Kondo temperature T K decreases with an increase of U. In the intermediate regime at half-filling the exponential scale of the Kondo temperature T K is lost already at the saddle-point level of slave boson formulation. (author)

  17. Shielding of Electronic Systems against Transient Electromagnetic Interferences

    Directory of Open Access Journals (Sweden)

    H. Herlemann

    2005-01-01

    Full Text Available In order to protect electronic systems against the effects of transient electromagnetic interferences, shields made of electrically conductive material can be used. The subject of this paper is an electrically conductive textile. When applying the shield, a reliable measure is needed in order to determine the effectiveness of the shield to protect against electromagnetic pulses. For this purpose, a time domain measurement technique is presented using double exponential pulses. With these pulses, the susceptibility of an operating electronic device with and without the shield is determined. As a criterion of quality of a shield, the breakdown failure rate found in both cases is compared.

  18. Electronic specific heats in metal--hydrogen systems

    International Nuclear Information System (INIS)

    Flotow, H.E.

    1979-01-01

    The electronic specific heats of metals and metal--hydrogen systems can in many cases be evaluated from the measured specific heats at constant pressure, C/sub p/, in the temperature range 1 to 10 K. For the simplest case, C/sub p/ = γT + βT 3 , where γT represents the specific heat contribution associated with the conduction electrons, and βT 3 represents lattice specific heat contribution. The electronic specific heat coefficient, γ, is important because it is proportional to electron density of states at the Fermi surface. A short description of a low temperature calorimetric cryostat employing a 3 He/ 4 He dilution refrigeration is given. Various considerations and complications encountered in the evaluation of γ from specific heat data are discussed. Finally, the experimental values of γ for the V--Cr--H system and for the Lu--H system are summarized and the variations of γ as function of alloy composition are discussed

  19. HOSPITAL INFORMATION SYSTEMS: A STUDY OF ELECTRONIC PATIENT RECORDS

    Directory of Open Access Journals (Sweden)

    Pedro Luiz Cortês

    2011-05-01

    Full Text Available The importance of patient records, also known as medical records, is related to different needs and objectives, as they constitute permanent documents on the health of patients. With the advancement of information technologies and systems, patient records can be stored in databases, resulting in a positive impact on patient care. Based on these considerations, a research question that arises is “what are the benefits and problems that can be seen with the use of electronic versions of medical records?” This question leads to the formulation of the following hypothesis: although problems can be identified during the process of using electronic record systems, the benefits outweigh the difficulties, thereby justifying their use. To respond to the question and test the presented hypothesis, a research study was developed with users of the same electronic record system, consisting of doctors, nurses, and administrative personnel in three hospitals located in the city of São Paulo, Brazil. The results show that, despite some problems in their usage, the benefits of electronic patient records outweigh possible disadvantages.

  20. 36 CFR 1236.26 - What actions must agencies take to maintain electronic information systems?

    Science.gov (United States)

    2010-07-01

    ... take to maintain electronic information systems? 1236.26 Section 1236.26 Parks, Forests, and Public... electronic information systems? (a) Agencies must maintain inventories of electronic information systems and... electronic information systems that is adequate to: (1) Specify all technical characteristics necessary for...

  1. NASAwide electronic publishing system: Prototype STI electronic document distribution, stage-4 evaluation report

    Science.gov (United States)

    Tuey, Richard C.; Collins, Mary; Caswell, Pamela; Haynes, Bob; Nelson, Michael L.; Holm, Jeanne; Buquo, Lynn; Tingle, Annette; Cooper, Bill; Stiltner, Roy

    1996-01-01

    This evaluation report contains an introduction, seven chapters, and five appendices. The Introduction describes the purpose, conceptual frame work, functional description, and technical report server of the STI Electronic Document Distribution (EDD) project. Chapter 1 documents the results of the prototype STI EDD in actual operation. Chapter 2 documents each NASA center's post processing publication processes. Chapter 3 documents each center's STI software, hardware, and communications configurations. Chapter 7 documents STI EDD policy, practices, and procedures. The appendices, which arc contained in Part 2 of this document, consist of (1) STI EDD Project Plan, (2) Team members, (3) Phasing Schedules, (4) Accessing On-line Reports, and (5) Creating an HTML File and Setting Up an xTRS. In summary, Stage 4 of the NASAwide Electronic Publishing System is the final phase of its implementation through the prototyping and gradual integration of each NASA center's electronic printing systems, desktop publishing systems, and technical report servers to be able to provide to NASA's engineers, researchers, scientists, and external users the widest practicable and appropriate dissemination of information concerning its activities and the result thereof to their work stations.

  2. Neuromorphic adaptive plastic scalable electronics: analog learning systems.

    Science.gov (United States)

    Srinivasa, Narayan; Cruz-Albrecht, Jose

    2012-01-01

    Decades of research to build programmable intelligent machines have demonstrated limited utility in complex, real-world environments. Comparing their performance with biological systems, these machines are less efficient by a factor of 1 million1 billion in complex, real-world environments. The Systems of Neuromorphic Adaptive Plastic Scalable Electronics (SyNAPSE) program is a multifaceted Defense Advanced Research Projects Agency (DARPA) project that seeks to break the programmable machine paradigm and define a new path for creating useful, intelligent machines. Since real-world systems exhibit infinite combinatorial complexity, electronic neuromorphic machine technology would be preferable in a host of applications, but useful and practical implementations still do not exist. HRL Laboratories LLC has embarked on addressing these challenges, and, in this article, we provide an overview of our project and progress made thus far.

  3. Future on Power Electronics for Wind Turbine Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Ma, Ke

    2013-01-01

    generators, power electronic systems, and control solutions have to be introduced to improve the characteristics of the wind power plant and make it more suitable to be integrated into the power grid. Meanwhile, there are also some emerging technology challenges, which need to be further clarified...... and investigated. This paper gives an overview and discusses some development trends in the technologies used for wind power systems. First, the developments of technology and market are generally discussed. Next, several state-of-the-art wind turbine concepts, as well as the corresponding power electronic......Wind power is still the most promising renewable energy in the year of 2013. The wind turbine system (WTS) started with a few tens of kilowatt power in the 1980s. Now, multimegawatt wind turbines are widely installed even up to 6-8 MW. There is a widespread use of wind turbines in the distribution...

  4. Radiation-Hardened Electronics for Advanced Communications Systems

    Science.gov (United States)

    Whitaker, Sterling

    2015-01-01

    Novel approach enables high-speed special-purpose processors Advanced reconfigurable and reprogrammable communication systems will require sub-130-nanometer electronics. Legacy single event upset (SEU) radiation-tolerant circuits are ineffective at speeds greater than 125 megahertz. In Phase I of this project, ICs, LLC, demonstrated new base-level logic circuits that provide SEU immunity for sub-130-nanometer high-speed circuits. In Phase II, the company developed an innovative self-restoring logic (SRL) circuit and a system approach that provides high-speed, SEU-tolerant solutions that are effective for sub-130-nanometer electronics scalable to at least 22-nanometer processes. The SRL system can be used in the design of NASA's next-generation special-purpose processors, especially reconfigurable communication processors.

  5. Supply system with microprocessor control for electron gun

    International Nuclear Information System (INIS)

    Duplin, N.I.; Sergeev, N.N.

    1988-01-01

    Precision supply system for electron gun used in Auger-spectrometer is described. The supply system consists of control and high-voltage parts, made as separate units. Supply high-voltage unit includes system supply module, filament module to supply electron gun cathode and 6 high-volt modules to supply accelerating, modulating and three focusing electrodes of the gun. High-voltage modules have the following characteristics: U-(100-1000)V output voltage, 5x10 -5 U stability, 10 -5 xU pulsation amplitude, J-(0-5)A filament current change range at 10 -4 xJ stability. Control unit including microprocessor, timer and storage devices forms control voltage for all modules and regulates voltage and current of filament at electrodes

  6. Quartz Crystal Microbalance Electronic Interfacing Systems: A Review

    Directory of Open Access Journals (Sweden)

    Abdulrahman Alassi

    2017-12-01

    Full Text Available Quartz Crystal Microbalance (QCM sensors are actively being implemented in various fields due to their compatibility with different operating conditions in gaseous/liquid mediums for a wide range of measurements. This trend has been matched by the parallel advancement in tailored electronic interfacing systems for QCM sensors. That is, selecting the appropriate electronic circuit is vital for accurate sensor measurements. Many techniques were developed over time to cover the expanding measurement requirements (e.g., accommodating highly-damping environments. This paper presents a comprehensive review of the various existing QCM electronic interfacing systems. Namely, impedance-based analysis, oscillators (conventional and lock-in based techniques, exponential decay methods and the emerging phase-mass based characterization. The aforementioned methods are discussed in detail and qualitatively compared in terms of their performance for various applications. In addition, some theoretical improvements and recommendations are introduced for adequate systems implementation. Finally, specific design considerations of high-temperature microbalance systems (e.g., GaPO4 crystals (GCM and Langasite crystals (LCM are introduced, while assessing their overall system performance, stability and quality compared to conventional low-temperature applications.

  7. Quartz Crystal Microbalance Electronic Interfacing Systems: A Review

    Science.gov (United States)

    Benammar, Mohieddine; Brett, Dan

    2017-01-01

    Quartz Crystal Microbalance (QCM) sensors are actively being implemented in various fields due to their compatibility with different operating conditions in gaseous/liquid mediums for a wide range of measurements. This trend has been matched by the parallel advancement in tailored electronic interfacing systems for QCM sensors. That is, selecting the appropriate electronic circuit is vital for accurate sensor measurements. Many techniques were developed over time to cover the expanding measurement requirements (e.g., accommodating highly-damping environments). This paper presents a comprehensive review of the various existing QCM electronic interfacing systems. Namely, impedance-based analysis, oscillators (conventional and lock-in based techniques), exponential decay methods and the emerging phase-mass based characterization. The aforementioned methods are discussed in detail and qualitatively compared in terms of their performance for various applications. In addition, some theoretical improvements and recommendations are introduced for adequate systems implementation. Finally, specific design considerations of high-temperature microbalance systems (e.g., GaPO4 crystals (GCM) and Langasite crystals (LCM)) are introduced, while assessing their overall system performance, stability and quality compared to conventional low-temperature applications. PMID:29206212

  8. Front-end electronics and trigger systems - status and challenges

    International Nuclear Information System (INIS)

    Spieler, Helmuth G; Spieler, Helmuth G

    2007-01-01

    The past quarter century has brought about a revolution in front-end electronics for large-scale detector systems. Custom integrated circuits specifically tailored to the requirements of large detector systems have provided unprecedented performance and enabled systems that once were deemed impossible. The evolution of integrated circuit readouts in strip detectors is summarized, the present status described, and challenges posed by the sLHC and ILC are discussed. Performance requirements increase, but key considerations remain as in the past: power dissipation, material, and services. Smaller CMOS feature sizes will not provide the required electronic noise at lower power, but will improve digital power efficiency. Significant improvements appear to be practical in more efficient power distribution. Enhanced digital electronics have provided powerful trigger processors that greatly improve the trigger efficiency. In data readout systems they also improve data throughput, while reducing power requirements. Concurrently with new developments in high energy physics, detector systems for cosmology and astrophysics have made great strides. As an example, a large-scale readout for superconducting bolometer arrays is described

  9. Trends in Power Electronics and Control of Renewable Energy Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Iov, Florin; Kerekes, Tamas

    2010-01-01

    by means of power electronics are changing the future electrical infrastructure but also contributes steadily more to non-carbon based electricity production. Most focus is on the power electronics technologies used. In the case of photovoltaics transformer-less systems are discussed as they have...... term) based energy sources to renewable energy sources. Another is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss trends of the most emerging renewable energy sources, wind energy and photovoltaics, which......The electrical energy consumption continues to grow and more applications will be based on electricity in the next decades. We can expect that more 60 % of all energy consumption will be converted and used as electricity. It is a demand that production, distribution and use of electrical energy...

  10. Power electronics - key technology for renewable energy systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Iov, Florin; Kerekes, Tamas

    2011-01-01

    are changing and challenging the future electrical infrastructure but also contributes steadily more to non-carbon based electricity production. Most focus in the paper is on the power electronics technologies used. In the case of photovoltaics transformer-less systems are discussed as they have the potential...... as efficient as possible. Further, the emerging climate changes is arguing to find sustainable future solutions. Of many options, two major technologies will play important roles to solve parts of those future problems. One is to change the electrical power production from conventional, fossil based energy...... sources to renewable energy sources. Another is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss trends of the most emerging renewable energy sources, wind energy and photovoltaics, which by means of power electronics...

  11. Revealing electronic open quantum systems with subsystem TDDFT.

    Science.gov (United States)

    Krishtal, Alisa; Pavanello, Michele

    2016-03-28

    Open quantum systems (OQSs) are perhaps the most realistic systems one can approach through simulations. In recent years, describing OQSs with Density Functional Theory (DFT) has been a prominent avenue of research with most approaches based on a density matrix partitioning in conjunction with an ad-hoc description of system-bath interactions. We propose a different theoretical approach to OQSs based on partitioning of the electron density. Employing the machinery of subsystem DFT (and its time-dependent extension), we provide a novel way of isolating and analyzing the various terms contributing to the coupling between the system and the surrounding bath. To illustrate the theory, we provide numerical simulations on a toy system (a molecular dimer) and on a condensed phase system (solvated excimer). The simulations show that non-Markovian dynamics in the electronic system-bath interactions are important in chemical applications. For instance, we show that the superexchange mechanism of transport in donor-bridge-acceptor systems is a non-Markovian interaction between the donor-acceptor (OQS) with the bridge (bath) which is fully characterized by real-time subsystem time-dependent DFT.

  12. Techniques for increasing the reliability of accelerator control system electronics

    International Nuclear Information System (INIS)

    Utterback, J.

    1993-09-01

    As the physical size of modern accelerators becomes larger and larger, the number of required control system circuit boards increases, and the probability of one of those circuit boards failing while in service also increases. In order to do physics, the experimenters need the accelerator to provide beam reliably with as little down time as possible. With the advent of colliding beams physics, reliability becomes even more important due to the fact that a control system failure can cause the loss of painstakingly produced antiprotons. These facts prove the importance of keeping reliability in mind when designing and maintaining accelerator control system electronics

  13. High resolution time-of-flight electronics system

    International Nuclear Information System (INIS)

    Grund, J.E.

    1979-10-01

    A new electronics system for time-of-flight measurements has been developed to meet the performance requirements of the Mark II Detector for operation at the PEP Storage Ring of the Stanford Linear Accelerator Center. This system incorporated high resolution time measurements with the capability to correct systemic errors from the scintillator and photomultiplier tubes. The correction technique involves making three measurements on each photomultiplier signal every storage ring beam interaction. Two timing measurements are made relative to the beam interaction time with different discriminator threshold level settings. The charge integral of each photomultiplier pulse is also recorded

  14. Two-Dimensional Electron System in Electromagnetic Radiation Field

    Science.gov (United States)

    Lungu, Radu Paul; Manolescu, Andrei

    We consider a two-dimensional electron gas in the presence of a monochromatic linear polarized electromagnetic field, within the Floquet formalism. The Floquet states have a simple relation with the energy eigenstates in the absence of the field. Therefore the single-particle and the two-particle Green functions of the many-body system with Coulomb interactions, in the radiation field, can be formally calculated by the standard diagrammatic techniques, as for the conservative system. We derive the elementary excitations of quasi-particle type, the plasma dispersion relation, and the ground state quasi-energy, and we relate them to the corresponding results for the conservative system.

  15. An electron beam imaging system for quality assurance in IORT

    Science.gov (United States)

    Casali, F.; Rossi, M.; Morigi, M. P.; Brancaccio, R.; Paltrinieri, E.; Bettuzzi, M.; Romani, D.; Ciocca, M.; Tosi, G.; Ronsivalle, C.; Vignati, M.

    2004-01-01

    Intraoperative radiation therapy is a special radiotherapy technique, which enables a high dose of radiation to be given in a single fraction during oncological surgery. The major stumbling block to the large-scale application of the technique is the transfer of the patient, with an open wound, from the operating room to the radiation therapy bunker, with the consequent organisational problems and the increased risk of infection. To overcome these limitations, in the last few years a new kind of linear accelerator, the Novac 7, conceived for direct use in the surgical room, has become available. Novac 7 can deliver electron beams of different energies (3, 5, 7 and 9 MeV), with a high dose rate (up to 20 Gy/min). The aim of this work, funded by ENEA in the framework of a research contract, is the development of an innovative system for on-line measurements of 2D dose distributions and electron beam characterisation, before radiotherapy treatment with Novac 7. The system is made up of the following components: (a) an electron-light converter; (b) a 14 bit cooled CCD camera; (c) a personal computer with an ad hoc written software for image acquisition and processing. The performances of the prototype have been characterised experimentally with different electron-light converters. Several tests have concerned the assessment of the detector response as a function of impulse number and electron beam energy. Finally, the experimental results concerning beam profiles have been compared with data acquired with other dosimetric techniques. The achieved results make it possible to say that the developed system is suitable for fast quality assurance measurements and verification of 2D dose distributions.

  16. Electron beam diagnostic system using computed tomography and an annular sensor

    Science.gov (United States)

    Elmer, John W.; Teruya, Alan T.

    2014-07-29

    A system for analyzing an electron beam including a circular electron beam diagnostic sensor adapted to receive the electron beam, the circular electron beam diagnostic sensor having a central axis; an annular sensor structure operatively connected to the circular electron beam diagnostic sensor, wherein the sensor structure receives the electron beam; a system for sweeping the electron beam radially outward from the central axis of the circular electron beam diagnostic sensor to the annular sensor structure wherein the electron beam is intercepted by the annular sensor structure; and a device for measuring the electron beam that is intercepted by the annular sensor structure.

  17. Awareness of Electronic Banking System among Management Students in Pakistan

    Directory of Open Access Journals (Sweden)

    Zeeshan FAREED

    2014-06-01

    Full Text Available Electronic Banking is an essential sector of banking industry. E-banking services are gaining the attention of conventional bank’s customers rapidly. It has brought the revolutionary changes in the Pakistan banking industry in terms of customer and business perspectives. Electronic banking has got popularity in the developed as well as developing countries because it saves people time, reduces costs and people have access to all banking services on the click of a button. More often, the new innovated system allows the customers to touch their accounts at home using a mobile device or electronic terminals. This research paper focuses on growth and awareness of electronic banking among Management Students of the Okara, Pakistan. Questionnaire on 5 point Likert scale was developed to find the views of 200 respondents. Frequency distribution and correlation analysis were employed on data. The results revealed that 74% of the students are well aware about ATM and 82% of management students of our sample populations believe that e-banking is very convenient system of banking. 74% of the Management students feel secure when they have money in credit and debit card while 82% of the students prefer e-banking over traditional banking.

  18. Method for secure electronic voting system: face recognition based approach

    Science.gov (United States)

    Alim, M. Affan; Baig, Misbah M.; Mehboob, Shahzain; Naseem, Imran

    2017-06-01

    In this paper, we propose a framework for low cost secure electronic voting system based on face recognition. Essentially Local Binary Pattern (LBP) is used for face feature characterization in texture format followed by chi-square distribution is used for image classification. Two parallel systems are developed based on smart phone and web applications for face learning and verification modules. The proposed system has two tire security levels by using person ID followed by face verification. Essentially class specific threshold is associated for controlling the security level of face verification. Our system is evaluated three standard databases and one real home based database and achieve the satisfactory recognition accuracies. Consequently our propose system provides secure, hassle free voting system and less intrusive compare with other biometrics.

  19. Integrated Electronic Health Record Database Management System: A Proposal.

    Science.gov (United States)

    Schiza, Eirini C; Panos, George; David, Christiana; Petkov, Nicolai; Schizas, Christos N

    2015-01-01

    eHealth has attained significant importance as a new mechanism for health management and medical practice. However, the technological growth of eHealth is still limited by technical expertise needed to develop appropriate products. Researchers are constantly in a process of developing and testing new software for building and handling Clinical Medical Records, being renamed to Electronic Health Record (EHR) systems; EHRs take full advantage of the technological developments and at the same time provide increased diagnostic and treatment capabilities to doctors. A step to be considered for facilitating this aim is to involve more actively the doctor in building the fundamental steps for creating the EHR system and database. A global clinical patient record database management system can be electronically created by simulating real life medical practice health record taking and utilizing, analyzing the recorded parameters. This proposed approach demonstrates the effective implementation of a universal classic medical record in electronic form, a procedure by which, clinicians are led to utilize algorithms and intelligent systems for their differential diagnosis, final diagnosis and treatment strategies.

  20. Control systems for power electronics a practical guide

    CERN Document Server

    Patil, Mahesh

    2015-01-01

    The scope of the book covers most of the aspects as a primer on power electronics starting from a simple diode bridge to a DC-DC convertor using PWM control. The thyristor-bridge and the mechanism of designing a closed loop system are discussed in chapter one, two and three. The concepts are applied in the fourth chapter as a case study for buck converter which uses MOSFETs as switching devices and the closed loop system is elaborated in the fifth chapter. Chapter six is focused on the embedded system basics and the implementation of controls in the digital domain. Chapter seven is a case study of application of an embedded control system for a DC motor. With this book, the reader will find it easy to work on the practical control systems with microcontroller implementation. The core intent of this book is to help gain an accelerated learning path to practical control system engineering and transform control theory to an implementable control system through electronics. Illustrations are provided for most of...

  1. Tanggung Jawab Hukum Penyelenggara Sistem Elektronik (Law Responsibility of the Electronic System Providers

    Directory of Open Access Journals (Sweden)

    Abdul Salam

    2011-09-01

    Full Text Available Reviewing Edmon Makarim’s book which is about Law Responsibility of the Electronic System Providers, remind us that easiness and availability of electronic system in electronic transaction in private or public happen because the role of electronic system providers. Behind the important and central role, there is big responsibility for electronic system providers. But because of wide of definition of provision of electronic system and so many people who involve in electronic system providers, there is a question in our mind, how is the shape of responsibility of the electronic system providers if the electronic system which is held is broken and / or not in operation as it has to and bring loss to users. Which one from the electronic system providers should take the responsibility in law?

  2. Module and electronics developments for the ATLAS ITk pixel system

    Science.gov (United States)

    Muñoz, F. J.

    2018-03-01

    The ATLAS experiment is preparing for an extensive modification of its detectors in the course of the planned HL-LHC accelerator upgrade around 2025. The ATLAS upgrade includes the replacement of the entire tracking system by an all-silicon detector (Inner Tracker, ITk). The five innermost layers of ITk will be a pixel detector built of new sensor and readout electronics technologies to improve the tracking performance and cope with the severe HL-LHC environment in terms of occupancy and radiation. The total area of the new pixel system could measure up to 14 m2, depending on the final layout choice, which is expected to take place in 2018. In this paper an overview of the ongoing R&D activities on modules and electronics for the ATLAS ITk is given including the main developments and achievements in silicon planar and 3D sensor technologies, readout and power challenges.

  3. MMS: An electronic message management system for emergency response

    DEFF Research Database (Denmark)

    Andersen, H.B.; Garde, H.; Andersen, V.

    1998-01-01

    This paper outlines the main features of an electronic communication system, MMS, designed to support coordination and exchange of information in connection with emergency management (EM) efforts, The design. of the MMS has been motivated by interviews with EM decision makers and reviews of commu......This paper outlines the main features of an electronic communication system, MMS, designed to support coordination and exchange of information in connection with emergency management (EM) efforts, The design. of the MMS has been motivated by interviews with EM decision makers and reviews......, Thus, users are able to define filters that capture, for instance, "unanswered requests sent out by me today" or "requests from me that have not been answered by an unconditional 'OK.'" Last, ne describe an associated preparedness plan module, which contains, for a given Ehl organization, its...

  4. Control of climatics environments to enhance reliability of electronics systems

    International Nuclear Information System (INIS)

    Sekhon, K.S.

    1979-01-01

    The techniques to control temperature and humidity to reduce failures in semiconductor devices are presented. The maximum operating junction temperature affects the electronic system reliability, and the equation for the junction temperature of the device shows that internal and external thermal resistances affect component life. Junction temperature reductions up to 60 C were achieved by the development of heat pipes for microcircuits, which will enhance electronics life by 32 times. Humidity control by improved sealing and use of heaters to prevent moisture condensation proved difficult and costly, and high pressure dehydrators were heavy and expensive. Therefore, low pressure dehydrator was developed which is smaller, lighter, and less expensive. The development of low pressure dehumidifying system including test data is presented

  5. Electronic structure, transport, and collective effects in molecular layered systems

    Directory of Open Access Journals (Sweden)

    Torsten Hahn

    2017-10-01

    Full Text Available The great potential of organic heterostructures for organic device applications is exemplified by the targeted engineering of the electronic properties of phthalocyanine-based systems. The transport properties of two different phthalocyanine systems, a pure copper phthalocyanine (CoPc and a flourinated copper phthalocyanine–manganese phthalocyanine (F16CoPc/MnPc heterostructure, are investigated by means of density functional theory (DFT and the non-equilibrium Green’s function (NEGF approach. Furthermore, a master-equation-based approach is used to include electronic correlations beyond the mean-field-type approximation of DFT. We describe the essential theoretical tools to obtain the parameters needed for the master equation from DFT results. Finally, an interacting molecular monolayer is considered within a master-equation approach.

  6. Module and electronics developments for the ATLAS ITK pixel system

    CERN Document Server

    Munoz Sanchez, Francisca Javiela; The ATLAS collaboration

    2017-01-01

    The ATLAS experiment is preparing for an extensive modification of its detectors in the course of the planned HL-LHC accelerator upgrade around 2025. The ATLAS upgrade includes the replacement of the entire tracking system by an all-silicon detector (Inner Tracker, ITk). The five innermost layers of ITk will be a pixel detector built of new sensor and readout electronics technologies to improve the tracking performance and cope with the severe HL-LHC environment in terms of occupancy and radiation. The total area of the new pixel system could measure up to 14 m2, depending on the final layout choice, which is expected to take place in 2017. In this paper an overview of the ongoing R\\&D activities on modules and electronics for the ATLAS ITk is given including the main developments and achievements in silicon planar and 3D sensor technologies, readout and power challenges.

  7. Electronics and Calibration system for the CMS Beam Halo Monitor

    CERN Document Server

    Tosi, Nicolò; Fabbri, Franco L; Finkel, Alexey; Orfanelli, Stella; Loos, R; Montanari, Alessandro; Rusack, R; Stickland, David P

    2014-01-01

    In the context of increasing luminosity of LHC, it will be important to accurately measure the Machine Induced Background. A new monitoring system will be installed in the cavern of the Compact Muon Solenoid (CMS) experiment for measuring the beam background at high radius. This detector is composed of synthetic quartz Cherenkov radiators, coupled to fast photomultiplier tubes (PMT). The readout chain of this detector will make use of many components developed for the Phase 1 upgrade to the CMS Hadron Calorimeter electronics, with a dedicated firmware and readout adapted to the beam monitoring requirements. The PMT signal will be digitized by a charge integrating ASIC (QIE10), providing both the signal rise time and the charge integrated over one bunch crossing. The backend electronics will record bunch-by-bunch histograms, which will be published to CMS and the LHC using the newly designed CMS beam instrumentation specific DAQ. A calibration monitoring system has been designed to generate triggered pulses of...

  8. XUV free-electron laser-based projection lithography systems

    Energy Technology Data Exchange (ETDEWEB)

    Newnam, B.E.

    1990-01-01

    Free-electron laser sources, driven by rf-linear accelerators, have the potential to operate in the extreme ultraviolet (XUV) spectral range with more than sufficient average power for high-volume projection lithography. For XUV wavelengths from 100 nm to 4 nm, such sources will enable the resolution limit of optical projection lithography to be extended from 0.25 {mu}m to 0.05{mu}m and with an adequate total depth of focus (1 to 2 {mu}m). Recent developments of a photoinjector of very bright electron beams, high-precision magnetic undulators, and ring-resonator cavities raise our confidence that FEL operation below 100 nm is ready for prototype demonstration. We address the motivation for an XUV FEL source for commercial microcircuit production and its integration into a lithographic system, include reflecting reduction masks, reflecting XUV projection optics and alignment systems, and surface-imaging photoresists. 52 refs., 7 figs.

  9. Control system by the technological electron Linac KUT-20

    CERN Document Server

    Akchurin, Y I; Gurin, V A; Demidov, N V

    2001-01-01

    The high-power technological electron linac KUT-20 was developed at the Science Research Complex 'Accelerator' of NSC KIPT. The linac consists of two 1.2 m length accelerating structures with a variable geometry and an injector. The latter comprises a diode electron gun,a klystron type buncher and an accelerating cavity.With a RF supply power at accelerating structure entries of 11 MW and with a current at the accelerator exit of 1A,the beam energy will be up to 20 MeV.An average beam power is planned to be 20 kW.All systems of the accelerator are controlled by a computerised control system. The program and technical complex consist of PC equipped with fast ADC control console, synchronization unit, microprocessor-operated complexes.

  10. Femtosecond electron diffraction: heralding the era of atomically resolved dynamics

    Science.gov (United States)

    Sciaini, Germán; Miller, R. J. Dwayne

    2011-09-01

    One of the great dream experiments in Science is to directly observe atomic motions as they occur. Femtosecond electron diffraction provided the first 'light' of sufficient intensity to achieve this goal by attaining atomic resolution to structural changes on the relevant timescales. This review covers the technical progress that made this new level of acuity possible and gives a survey of the new insights gained from an atomic level perspective of structural dynamics. Atomic level views of the simplest possible structural transition, melting, are discussed for a number of systems in which both thermal and purely electronically driven atomic displacements can be correlated with the degree of directional bonding. Optical manipulation of charge distributions and effects on interatomic forces/bonding can be directly observed through the ensuing atomic motions. New phenomena involving strongly correlated electron-lattice systems are also discussed in which optically induced changes in the potential energy landscape lead to ballistic structural changes. Concepts such as the structural order parameters are now directly observable at the atomic level of inspection to give a remarkable view of the extraordinary degree of cooperativity involved in strongly correlated electron-lattice systems. These recent examples, in combination with time-resolved real space imaging now possible with electron probes, are truly defining an emerging field that holds great promise to make a significant impact in how we understand structural dynamics. This article is dedicated to the memory of Professor David John Hugh Cockayne, a world leader in electron microscopy, who sadly passed away in December.

  11. Thermal control system for SSF sensor/electronics

    Science.gov (United States)

    Akau, R. L.; Lee, D. E.

    1993-01-01

    A thermal control system was designed for the Space Station Freedom (SSF) sensor/electronics box (SSTACK). Multi-layer insulation and heaters are used to maintain the temperatures of the critical components within their operating and survival temperature limits. Detailed and simplified SSTACK thermal models were developed and temperatures were calculated for worst-case orbital conditions. A comparison between the two models showed very good agreement. Temperature predictions were also compared to measured temperatures from a thermal-vacuum test.

  12. A Novel Power Electronic Inverter Circuit for Transformerless Photovoltaic Systems

    OpenAIRE

    Hai-Yan, Cao

    2014-01-01

    Capacitive leakage current is one of the most important issues for transformerless photovoltaic systems. In order to deal with the capacitive leakage current, a new power electronic inverter circuit is proposed in this paper. The inverter circuit consists of six switches and operates with constant common mode voltage. Theoretical analysis is conducted to clarify the circuit operation principle and the common mode characteristic. The performance evaluation test is carried out, and test results...

  13. Electric and electronic systems of the Tokamak Novillo

    International Nuclear Information System (INIS)

    Lopez Callejas, R.; Valencia Alvarado, R.; Melendez Lugo, L.; Chavez Alarcon, E.

    1990-01-01

    The study, design and construction of electric and electronic equipment related to the Tokamak Novillo are described in this report. The equipment consists of: a) power supply and charge control circuits for six capacitor banks, b) control circuit for single and sequential shoots of the storaged energy on the magnetic coils, c) AF oscillator (17.5 kHz, 10kW, 2pps) for the cleaning discharge, d) data acquisition system. (Author)

  14. The Spartan attitude control system - Control electronics assembly

    Science.gov (United States)

    Stone, R. W.

    1986-10-01

    The Spartan attitude control system (ACS) represents an evolutionary development of the previous STRAP-5 ACS through the use of state-of-the-art microprocessors and hardware. Despite a gyro rate signal noise problem that caused the early depletion of argon gas, the Spartan 101 experiment was able to collect several hours of data from two targets. Attention is presently given to the ACS sequencer module, sensor interface box, valve driver box, control electronics software, jam tables, and sequencer programs.

  15. Electron beam extraction system with a ring radiation field

    International Nuclear Information System (INIS)

    Auslender, V.L.; Kuksanov, N.K.; Polyakov, V.A.; Salimov, R.A.; Chertok, I.L.

    1979-01-01

    Description and results of testings of two electron beam extraction systems for shaping of a circular irradiation field are given. One of the systems contains three 20 cm long outlet windows arranged at 120 deg angle with respect to each other. Tests at the ILU-6 accelerator have shown that the given system provides 150 mm zone irradiation from three sides. Beam utilization factor when irradiating three 40 mm dia tubes amounted to 35% which provides capacity of 2.5 txMrad/h at 20 kW beam power. The other extraction system includes two C-form magnets producing nonuniform and opposing magnetic fields. This system tests at the EhLV-2 accelerator have shown that at 0.8-1.5 MeV electron energy it is possible to irradiate of 60 and 100 mm dia objects, accordingly. The system may be used together with both constant-action and pulse-action accelerators having extraction with linear scanning [ru

  16. Evaluation on Electronic Securities Settlements Systems by AHP Methods

    Science.gov (United States)

    Fukaya, Kiyoyuki; Komoda, Norihisa

    Accompanying the spread of Internet and the change of business models, electronic commerce expands buisness areas. Electronic finance commerce becomes popular and especially online security tradings becoome very popular in this area. This online securitiy tradings have some good points such as less mistakes than telephone calls. In order to expand this online security tradings, the transfer of the security paper is one the largest problems to be solved. Because it takes a few days to transfer the security paper from a seller to a buyer. So the dematerialization of security papers is one of the solutions. The demterilization needs the information systems for setteling security. Some countries such as France, German, United Kingdom and U.S.A. have been strating the dematerialization projects. The legacy assesments on these projects focus from the viewpoint of the legal schemes only and there is no assessment from system architectures. This paper focuses on the information system scheme and valuates these dematerlization projects by AHP methods from the viewpoints of “dematerializaion of security papers", “speed of transfer", “usefulness on the system" and “accumulation of risks". This is the first case of valuations on security settlements systems by AHP methods, especially four counties’ systems.

  17. Programmable electronic system for analog and digital gamma cameras modernization

    International Nuclear Information System (INIS)

    Osorio Deliz, J. F.; Diaz Garcia, A.; Arista Omeu, E. J.

    2013-01-01

    At present the use of analog and digital gamma cameras is continuously increasing in developing countries. Many of them still largely rely in old hardware electronics, which in many cases limits their use in actual nuclear medicine diagnostic studies. For this reason worldwide there are different medical equipment manufacturing companies engaged into partial or total Gamma Cameras modernization. Nevertheless in several occasions acquisition prices are not affordable for developing countries. This work describes the basic features of a programmable electronic system that allows improving acquisitions functions and processing of analog and digital gamma cameras. This system is based on an electronic board for the acquisition and digitization of nuclear pulses which have been generated by gamma camera detector. It comprises a hardware interface with PC and the associated software to fully signal processing. Signal shaping and image processing are included. The extensive use of reference tables in the processing and signal imaging software allowed the optimization of the processing speed. Time design and system cost were also decreased. (Author)

  18. Shared Electronic Health Record Systems: Key Legal and Security Challenges.

    Science.gov (United States)

    Christiansen, Ellen K; Skipenes, Eva; Hausken, Marie F; Skeie, Svein; Østbye, Truls; Iversen, Marjolein M

    2017-11-01

    Use of shared electronic health records opens a whole range of new possibilities for flexible and fruitful cooperation among health personnel in different health institutions, to the benefit of the patients. There are, however, unsolved legal and security challenges. The overall aim of this article is to highlight legal and security challenges that should be considered before using shared electronic cooperation platforms and health record systems to avoid legal and security "surprises" subsequent to the implementation. Practical lessons learned from the use of a web-based ulcer record system involving patients, community nurses, GPs, and hospital nurses and doctors in specialist health care are used to illustrate challenges we faced. Discussion of possible legal and security challenges is critical for successful implementation of shared electronic collaboration systems. Key challenges include (1) allocation of responsibility, (2) documentation routines, (3) and integrated or federated access control. We discuss and suggest how challenges of legal and security aspects can be handled. This discussion may be useful for both current and future users, as well as policy makers.

  19. Research on distributed virtual reality system in electronic commerce

    Science.gov (United States)

    Xue, Qiang; Wang, Jiening; Sun, Jizhou

    2004-03-01

    In this paper, Distributed Virtual Reality (DVR) technology applied in Electronical Commerce (EC) is discussed. DVR has the capability of providing a new means for human being to recognize, analyze and resolve the large scale, complex problems, which makes it develop quickly in EC fields. The technology of CSCW (Computer Supported Cooperative Work) and middleware is introduced into the development of EC-DVR system to meet the need of a platform which can provide the necessary cooperation and communication services to avoid developing the basic module repeatedly. Finally, the paper gives a platform structure of EC-DVR system.

  20. APD detector electronics for the NSTX Thomson scattering system

    International Nuclear Information System (INIS)

    Johnson, D.W.; LeBlanc, B.P.; Long, D.L.; Renda, G.

    2000-01-01

    An electronics system has been installed and tested for the readout of APD detectors for the NSTX Thomson scattering system. Similar to previous designs, it features preamps with a fast and a slow output. The fast output uses pulse shaping to optimize sensitivity for the 8 nsec scattered light pulse while rejecting noise in the intrinsic plasma background. A low readout noise of approximately25 photoelectrons is achieved at an APD gain of 75. The design incorporates a number of features to provide flexibility for various modes of calibration