Fermions Tunneling from Higher-Dimensional Reissner-Nordström Black Hole: Semiclassical and Beyond Semiclassical Approximation

Directory of Open Access Journals (Sweden)

ShuZheng Yang

2016-01-01

Full Text Available Based on semiclassical tunneling method, we focus on charged fermions tunneling from higher-dimensional Reissner-Nordström black hole. We first simplify the Dirac equation by semiclassical approximation, and then a semiclassical Hamilton-Jacobi equation is obtained. Using the Hamilton-Jacobi equation, we study the Hawking temperature and fermions tunneling rate at the event horizon of the higher-dimensional Reissner-Nordström black hole space-time. Finally, the correct entropy is calculation by the method beyond semiclassical approximation.

Improved multidimensional semiclassical tunneling theory.

Science.gov (United States)

Wagner, Albert F

2013-12-12

We show that the analytic multidimensional semiclassical tunneling formula of Miller et al. [Miller, W. H.; Hernandez, R.; Handy, N. C.; Jayatilaka, D.; Willets, A. Chem. Phys. Lett. 1990, 172, 62] is qualitatively incorrect for deep tunneling at energies well below the top of the barrier. The origin of this deficiency is that the formula uses an effective barrier weakly related to the true energetics but correctly adjusted to reproduce the harmonic description and anharmonic corrections of the reaction path at the saddle point as determined by second order vibrational perturbation theory. We present an analytic improved semiclassical formula that correctly includes energetic information and allows a qualitatively correct representation of deep tunneling. This is done by constructing a three segment composite Eckart potential that is continuous everywhere in both value and derivative. This composite potential has an analytic barrier penetration integral from which the semiclassical action can be derived and then used to define the semiclassical tunneling probability. The middle segment of the composite potential by itself is superior to the original formula of Miller et al. because it incorporates the asymmetry of the reaction barrier produced by the known reaction exoergicity. Comparison of the semiclassical and exact quantum tunneling probability for the pure Eckart potential suggests a simple threshold multiplicative factor to the improved formula to account for quantum effects very near threshold not represented by semiclassical theory. The deep tunneling limitations of the original formula are echoed in semiclassical high-energy descriptions of bound vibrational states perpendicular to the reaction path at the saddle point. However, typically ab initio energetic information is not available to correct it. The Supporting Information contains a Fortran code, test input, and test output that implements the improved semiclassical tunneling formula.

Global Decoupling on the RHIC Ramp

CERN Document Server

Luo, Yun; Della Penna, Al; Fischer, Wolfram; Laster, Jonathan S; Marusic, Al; Pilat, Fulvia Caterina; Roser, Thomas; Trbojevic, Dejan

2005-01-01

The global betatron decoupling on the ramp is an important issue for the operation of the Relativistic Heavy Ion Collider (RHIC). In the polarized proton run, the betatron tunes are required to keep almost constant on the ramp to avoid spin resonance line crossing and the beam polarization loss. Some possible correction schemes on the ramp, like three-ramp correction, the coupling amplitude modulation and the coupling phase modulaxtion, have been found. The principles of these schemes are shortly reviewed and compared. Operational results of their applications on the RHIC ramps are given.

The Circuit-Level Decoupling Modulation Strategy for Three-Level Neutral-Point-Clamped (TL-NPC) Inverter

DEFF Research Database (Denmark)

Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

2011-01-01

In this paper, a circuit-level decoupling modulation strategy is proposed for the three-level (TL) neutral-point-clamped (NPC) inverters. With the proposed modulation scheme, the TL-NPC inverter can be decoupled into two three-level Buck converters in each defined operating section, which makes...

Semiclassical expansions of the nuclear relativistic Hartree-Fock theory

International Nuclear Information System (INIS)

Weigel, M.K.; Haddad, S.

1991-01-01

Semiclassical expansions for Green functions, self-energy, phase-space density and density are given and discussed. The many-body problem was treated in the relativistic Hartree-Fock approximation with a Lagrangian with a standard OBE potential structure including the possibility of space-dependent couplings. The expansions are obtained by formulating the many-body problem in the mixed position-momentum (Wigner) representation and application of the (h/2π)-Wigner-Kirkwood expansion scheme. The resulting self-consistency problems for the zeroth and second order are formulated in three versions. (author)

Signatures of unstable semiclassical trajectories in tunneling

International Nuclear Information System (INIS)

Levkov, D G; Panin, A G; Sibiryakov, S M

2009-01-01

It was found recently that processes of multidimensional tunneling are generally described at high energies by unstable semiclassical trajectories. We study two observational signatures related to the instability of trajectories. First, we find an additional power-law dependence of the tunneling probability on the semiclassical parameter as compared to the standard case of potential tunneling. The second signature is a substantial widening of the probability distribution over final-state quantum numbers. These effects are studied using a modified semiclassical technique which incorporates stabilization of the tunneling trajectories. The technique is derived from first principles. We obtain expressions for the inclusive and exclusive tunneling probabilities in the case of unstable semiclassical trajectories. We also investigate the 'phase transition' between the cases of stable and unstable trajectories across certain 'critical' values of energy. Finally, we derive the relation between the semiclassical probabilities of tunneling from the low-lying and highly excited initial states. This puts on firm ground a conjecture made previously in the semiclassical description of collision-induced tunneling in field theory

Optimally combining dynamical decoupling and quantum error correction.

Science.gov (United States)

Paz-Silva, Gerardo A; Lidar, D A

2013-01-01

Quantum control and fault-tolerant quantum computing (FTQC) are two of the cornerstones on which the hope of realizing a large-scale quantum computer is pinned, yet only preliminary steps have been taken towards formalizing the interplay between them. Here we explore this interplay using the powerful strategy of dynamical decoupling (DD), and show how it can be seamlessly and optimally integrated with FTQC. To this end we show how to find the optimal decoupling generator set (DGS) for various subspaces relevant to FTQC, and how to simultaneously decouple them. We focus on stabilizer codes, which represent the largest contribution to the size of the DGS, showing that the intuitive choice comprising the stabilizers and logical operators of the code is in fact optimal, i.e., minimizes a natural cost function associated with the length of DD sequences. Our work brings hybrid DD-FTQC schemes, and their potentially considerable advantages, closer to realization.

Semiclassical methods in field theories

International Nuclear Information System (INIS)

Ventura, I.

1978-10-01

A new scheme is proposed for semi-classical quantization in field theory - the expansion about the charge (EAC) - which is developed within the canonical formalism. This method is suitable for quantizing theories that are invariant under global gauge transformations. It is used in the treatment of the non relativistic logarithmic theory that was proposed by Bialynicki-Birula and Mycielski - a theory we can formulate in any number of spatial dimensions. The non linear Schroedinger equation is also quantized by means of the EAC. The classical logarithmic theories - both, the non relativistic and the relativistic one - are studied in detail. It is shown that the Bohr-Sommerfeld quantization rule(BSQR) in field theory is, in many cases, equivalent to charge quantization. This rule is then applied to the massive Thirring Model and the logarithmic theories. The BSQR can be see as a simplified and non local version of the EAC [pt

Study of some approximation schemes in the spin-boson problem

International Nuclear Information System (INIS)

Kenkre, V.M.; Giuggioli, L.

2004-01-01

Some approximation schemes used in the description of the evolution of the spin-boson system are studied through numerical and analytic methods. Among the procedures investigated are semiclassical approximations and the memory function approach. An infinitely large number of semiclassical approximations are discussed. Their two extreme limits are shown to be characterized, respectively, by effective energy mismatch and effective intersite transfer. The validity of the two limits is explored by explicit numerical calculations for important regions in parameter space, and it is shown that they can provide good descriptions in the so-called adiabatic and anti-adiabatic regimes, respectively. The memory function approach, which provides an excellent approximation scheme for a certain range of parameters, is shown to be connected to other approaches such as the non-interacting blip approximation. New results are derived from the memory approach in semiclassical contexts. Comments are made on thermal effects in the spin-boson problem, the discrete non-linear Schroedinger equation, and connections to the areas of dynamic localization, and quantum control

A semiclassical model for quark jet fragmentation

International Nuclear Information System (INIS)

Andersson, B.; Gustafson, G.; Peterson, C.

1979-01-01

A semiclassical model is presented for the way the energy of a fast quark is transformed into observable hadrons. It reproduces the features of 1+1 dimensional QED (the Schwinger model) concerning a flat rapidity distribution in the central region. It also reproduces results from phenomenological considerations, which, based upon scaling, predict that meson formation in the fragmentation region can be described by an iterative scheme, implying a set of coupled integral equations. In particular the model predicts that the probability to find a meson containing the leading quark is independent of the Feynman scaling variable z. The iterative structure corresponds to a Brownian motion with relevance both to the cofinement problems and to the distribution of mass in the quark jet. (orig.) [de

Protected quantum computing: interleaving gate operations with dynamical decoupling sequences.

Science.gov (United States)

Zhang, Jingfu; Souza, Alexandre M; Brandao, Frederico Dias; Suter, Dieter

2014-02-07

Implementing precise operations on quantum systems is one of the biggest challenges for building quantum devices in a noisy environment. Dynamical decoupling attenuates the destructive effect of the environmental noise, but so far, it has been used primarily in the context of quantum memories. Here, we experimentally demonstrate a general scheme for combining dynamical decoupling with quantum logical gate operations using the example of an electron-spin qubit of a single nitrogen-vacancy center in diamond. We achieve process fidelities >98% for gate times that are 2 orders of magnitude longer than the unprotected dephasing time T2.

Semiclassical versus exact quantization of the Sinh-Gordon model

Energy Technology Data Exchange (ETDEWEB)

Grossehelweg, Juliane

2009-12-15

In this work we investigate the semiclassics of the Sinh-Gordon model. The Sinh-Gordon model is integrable, its explicit solutions of the classical and the quantum model are well known. This allows for a comprehensive investigation of the semiclassical quantization of the classical model as well as of the semiclassical limit of the exact quantum solution. Semiclassical means in this case that the key objects of quantum theory are constructed as formal power series. A quantity playing an important role in the quantum theory is the Q-function. The purpose of this work is to investigate to what extend the classical integrability of the model admits of a construction of the semiclassical expansion of the Q-function. Therefore we used two conceptual independent approaches. In the one approach we start from the exact nonperturbative solution of the quantum model and calculate the semiclassical limit up to the next to leading order. Thereby we found the spectral curve, as well as the semiclassical expansion of the Q-function and of the eigenvalue of the monodromy matrix. In the other approach we constructed the first two orders of the semiclassical expansion of the Q-function, starting from the classical solution theory. The results of both approaches coincide. (orig.)

Coherent semiclassical states for loop quantum cosmology

International Nuclear Information System (INIS)

Corichi, Alejandro; Montoya, Edison

2011-01-01

The spatially flat Friedmann-Robertson-Walker cosmological model with a massless scalar field in loop quantum cosmology admits a description in terms of a completely solvable model. This has been used to prove that: (i) the quantum bounce that replaces the big bang singularity is generic; (ii) there is an upper bound on the energy density for all states, and (iii) semiclassical states at late times had to be semiclassical before the bounce. Here we consider a family of exact solutions to the theory, corresponding to generalized coherent Gaussian and squeezed states. We analyze the behavior of basic physical observables and impose restrictions on the states based on physical considerations. These turn out to be enough to select, from all the generalized coherent states, those that behave semiclassical at late times. We study then the properties of such states near the bounce where the most 'quantum behavior' is expected. As it turns out, the states remain sharply peaked and semiclassical at the bounce and the dynamics is very well approximated by the ''effective theory'' throughout the time evolution. We compare the semiclassicality properties of squeezed states to those of the Gaussian semiclassical states and conclude that the Gaussians are better behaved. In particular, the asymmetry in the relative fluctuations before and after the bounce are negligible, thus ruling out claims of so-called 'cosmic forgetfulness'.

Semiclassical scattering in Yang-Mills theory

International Nuclear Information System (INIS)

Gould, T.M.; Poppitz, E.R.

1994-01-01

A classical solution to the Yang-Mills theory is given a semiclassical interpretation. The boundary value problem on a complex time contour which arises from the semiclassical approximation to multiparticle scattering amplitudes is reviewed and applied to the case of Yang-Mills theory. The solution describes a classically forbidden transition between states with a large average number of particles in the limit g→0. It dominates a transition probability with a semiclassical suppression factor equal to twice the action of the well-known BPST instanton. Hence, it is relevant to the problem of high-energy tunnelling. It describes transitions of unit topological charge for an appropriate time contour. Therefore, it may have a direct interpretation in terms of fermion-number violating processes in electroweak theory. The solution describes a transition between an initial state with parametrically fewer particles than the final state. Thus, it may be relevant to the study of semiclassical initial-state corrections in the limit of a small number of initial particles. The implications of these results for multiparticle production in electroweak theory are also discussed. (orig.)

Semiclassical analysis of loop quantum gravity

International Nuclear Information System (INIS)

Conrady, F.

2005-01-01

In this Ph.D. thesis, we explore and develop new methods that should help in determining an effective semiclassical description of canonical loop quantum gravity and spin foam gravity. A brief introduction to loop quantum gravity is followed by three research papers that present the results of the Ph.D. project. In the first article, we deal with the problem of time and a new proposal for implementing proper time as boundary conditions in a sum over histories: we investigate a concrete realization of this formalism for free scalar field theory. In the second article, we translate semiclassical states of linearized gravity into states of loop quantum gravity. The properties of the latter indicate how semiclassicality manifests itself in the loop framework, and how this may be exploited for doing semiclassical expansions. In the third part, we propose a new formulation of spin foam models that is fully triangulation- and background-independent: by means of a symmetry condition, we identify spin foam models whose triangulation-dependence can be naturally removed. (orig.)

Semiclassical analysis of loop quantum gravity

Energy Technology Data Exchange (ETDEWEB)

Conrady, F.

2005-10-17

In this Ph.D. thesis, we explore and develop new methods that should help in determining an effective semiclassical description of canonical loop quantum gravity and spin foam gravity. A brief introduction to loop quantum gravity is followed by three research papers that present the results of the Ph.D. project. In the first article, we deal with the problem of time and a new proposal for implementing proper time as boundary conditions in a sum over histories: we investigate a concrete realization of this formalism for free scalar field theory. In the second article, we translate semiclassical states of linearized gravity into states of loop quantum gravity. The properties of the latter indicate how semiclassicality manifests itself in the loop framework, and how this may be exploited for doing semiclassical expansions. In the third part, we propose a new formulation of spin foam models that is fully triangulation- and background-independent: by means of a symmetry condition, we identify spin foam models whose triangulation-dependence can be naturally removed. (orig.)

Semiclassical analysis of the kicked Rydberg atom

International Nuclear Information System (INIS)

Yoshida, S.; Persson, E.; Burgdoerfer, J.; Grossmann, F.; Reinhold, C.

2001-01-01

Full text: The kicked atom is known as the testing ground for the study of quantum chaos and proven to show the quantum localization as the scarred wavefunction while the corresponding classical counterpart shows chaotic behavior. This apparent contradiction between the ubiquitousness of classical chaotic dynamics and the lack thereof in quantum dynamics brings into focus the open problem of a semiclassical description of quantum localization. We analyze the kicked atom using a semiclassical approximation based on Gaussian wave packets (Herman-Kluk Propagator) and examine the semiclassical manifestation of quantum localization. (author)

Principle of Global Decoupling with Coupling Angle Modulation

CERN Document Server

Luo, Yun; Pilat, Fulvia Caterina; Roser, Thomas; Trbojevic, Dejan

2005-01-01

The global betatron decoupling on the ramp is an important issue for the operation of the Relativistic Heavy Ion Collider (RHIC). A new scheme coupling phase modulation is found. It introduces a rotating extra coupling into the coupled machine to detect the residual coupling. The eigentune responses are measured with a high resolution phase lock loop (PLL) system. From the minimum and maximum tune splits, the correction strengths are given. The time period occupied by one coupling phase modulation is less than 10 seconds. So it is a very promising solution for the global decoupling on the ramp. In this article the principle of the coupling phase modulation is given. The simulation with the smooth accelerator model is also done. The practical issues concerning its applications are discussed.

Modified semiclassical approximation for trapped Bose gases

International Nuclear Information System (INIS)

Yukalov, V.I.

2005-01-01

A generalization of the semiclassical approximation is suggested allowing for an essential extension of its region of applicability. In particular, it becomes possible to describe Bose-Einstein condensation of a trapped gas in low-dimensional traps and in traps of low confining dimensions, for which the standard semiclassical approximation is not applicable. The result of the modified approach is shown to coincide with purely quantum-mechanical calculations for harmonic traps, including the one-dimensional harmonic trap. The advantage of the semiclassical approximation is in its simplicity and generality. Power-law potentials of arbitrary powers are considered. The effective thermodynamic limit is defined for any confining dimension. The behavior of the specific heat, isothermal compressibility, and density fluctuations is analyzed, with an emphasis on low confining dimensions, where the usual semiclassical method fails. The peculiarities of the thermodynamic characteristics in the effective thermodynamic limit are discussed

The semiclassical way to dynamics and spectroscopy

CERN Document Server

Heller, Eric

2018-01-01

Physical systems have been traditionally described in terms of either classical or quantum mechanics. But in recent years, semiclassical methods have developed rapidly, providing deep physical insight and computational tools for quantum dynamics and spectroscopy. In this book, Eric Heller introduces and develops this subject, demonstrating its power with many examples. In the first half of the book, Heller covers relevant aspects of classical mechanics, building from them the semiclassical way through the semiclassical limit of the Feynman path integral. The second half of the book applies this approach to various kinds of spectroscopy, such as molecular spectroscopy and electron imaging and quantum dynamical systems with an emphasis on tunneling. Adopting a distinctly time-dependent viewpoint, Heller argues for semiclassical theories from experimental and theoretical vantage points valuable to research in physics and chemistry. Featuring more than two hundred figures, the book provides a geometric, phase-sp...

Discontinuous PWM Modulation Strategy with Circuit-Level Decoupling Concept of Three-Level Neutral-Point Clamped (NPC) Inverter

DEFF Research Database (Denmark)

Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

2013-01-01

inverters, but also reduces the switching loss of the inverter along with an inherent neutral point (NP) voltage control. Based on a circuit-level decoupling concept, the NPC inverter can be decoupled into two three-level Buck converters in every defined operating section, and thereby the controller design...... can be reduced by one third. In order to explain the operation of this topology properly, the decoupling principle including the driving signal synthesis and the NP potential variation are analyzed in detail in this paper. Finally the viability and performance of the proposed modulation scheme...

Calculation studies of a multi-layer decoupler system for a decoupled hydrogen moderator

International Nuclear Information System (INIS)

Ooi, M.; Kiyanagi, Y.

2001-01-01

We proposed a multi-layer decoupler as a method to improve pulse characteristics of emitted neutrons from a decoupled hydrogen moderator. Pulse shapes from a moderator with the multi layer-decoupler were compared with those with a traditional single layer decoupler. It was found that the multi-layer decoupler system gave better pulse characteristic with less decrease of peak intensity. (author)

Reverse-time Migration in Tilted Transversely Isotropic Media with Decoupled Equations

KAUST Repository

Zhan, Ge

2012-12-01

Conventional modeling and migration for tilted transversely isotropic (TTI) media may suffer from numerical instabilities and shear wave artifacts due to the coupling of the P-wave and SV-wave modes in the TTI coupled equations. Starting with the separated P- and SV-phase velocity expressions for vertical transversely isotropic (VTI) media, I extend these decoupled equations for modeling and reverse-time migration (RTM) in acoustic TTI media. Compared with the TTI coupled equations published in the geophysical literature, the new TTI decoupled equations provide a more stable solution due to the complete separation of the P-wave and SV-wave modes. The pseudospectral (PS) method is the most convenient method to implement these equations due to the form of wavenumber expressions and has the added benefit of being highly accurate and thus avoiding numerical dispersion. The rapid expansion method (REM) in time is employed to produce a broad band numerically stable time evolution of the wavefields. Synthetic results validate the proposed TTI decoupled equations and show that modeling and RTM in TTI media with the decoupled P-wave equation remain numerically stable even for models with strong anisotropy and sharp contrasts. The most desirable feature of the TTI decoupled P-wave equation is that it is absolutely free of shear-wave artifacts and the consequent alleviation of numerical instabilities generally suffered by some systems of coupled equations. However, due to several forward-backward Fourier transforms in wavefield extrapolation at each time step, the computational cost is also high, and thereby hampers its prevalence. I hereby propose to use a hybrid pseudospectral and finite-difference (FD) scheme to solve the TTI decoupled P-wave equation. In the hybrid solution, most of the cost-consuming wavenumber terms in the equation are replaced by inexpensive FD operators, which in turn accelerates the computation and reduces the computational cost. To demonstrate the

Decoupling of heavy quarks in quantum chromodynamics

International Nuclear Information System (INIS)

Bernreuther, W.

1983-01-01

Decoupling of heavy quarks in quantum chromodynamics (QCD) defined by mass-independent renormalization is investigated. The structure of the relations between the parameters of f flavour QCD below a heavy-quark threshold is discussed to all orders in the loop expansion, and the relations are computed to two-loop approximation for the minimal subtraction schemes (MS) and to one-loop approximation for some Weinberg schemes. These matching relations can be used to systematically determine the renormalization group (RG)-invariant parameters of the effective theory in terms of the RG-invariant parameters of the theory which includes the heavy quark, or vice versa. For MS scheme the connection between Λ/sub f/-1 and Λ/sub f/ to two and three loops is given as well as the two-loop connection between the RG-invariant mass parameters of the f-1 and f flavour theory. The effect of heavy quarks on the evolution of the QCQ coupling is of significance for present QCD phenomenology based on next-to-leading-order perturbation theory. This is illustrated with a few examples within the MS scheme

Semiclassical dynamics and magnetic Weyl calculus

International Nuclear Information System (INIS)

Lein, Maximilian Stefan

2011-01-01

Weyl quantization and related semiclassical techniques can be used to study conduction properties of crystalline solids subjected to slowly-varying, external electromagnetic fields. The case where the external magnetic field is constant, is not covered by existing theory as proofs involving usual Weyl calculus break down. This is the regime of the so-called quantum Hall effect where quantization of transverse conductance is observed. To rigorously derive semiclassical equations of motion, one needs to systematically develop a magnetic Weyl calculus which contains a semiclassical parameter. Mathematically, the operators involved in the analysis are magnetic pseudodifferential operators, a topic which by itself is of interest for the mathematics and mathematical physics community alike. Hence, we will devote two additional chapters to further understanding of properties of those operators. (orig.)

Semi-classical quantization of chaotic billiards

International Nuclear Information System (INIS)

Smilansky, U.

1992-02-01

The semi-classical quantization of chaotic billiards will be developed using scattering theory approach. This will be used to introduce and explain the inherent difficulties in the semi-classical quantization of chaos, and to show some of the modern tools which were developed recently to overcome these difficulties. To this end, we shall first obtain a semi-classical secular equation which is based on a finite number of classical periodic orbits. We shall use it to derive some spectral properties, and in particular to investigate the relationship between spectral statistics of quantum chaotic systems and the predictions of random-matrix theory. We shall finally discuss an important family of chaotic billiard, whose statistics does not follow any of the canonical ensembles, (GOE,GUE,...) but rather, corresponds to a new universality class. (author)

Semiclassical dynamics and magnetic Weyl calculus

Energy Technology Data Exchange (ETDEWEB)

Lein, Maximilian Stefan

2011-01-19

Weyl quantization and related semiclassical techniques can be used to study conduction properties of crystalline solids subjected to slowly-varying, external electromagnetic fields. The case where the external magnetic field is constant, is not covered by existing theory as proofs involving usual Weyl calculus break down. This is the regime of the so-called quantum Hall effect where quantization of transverse conductance is observed. To rigorously derive semiclassical equations of motion, one needs to systematically develop a magnetic Weyl calculus which contains a semiclassical parameter. Mathematically, the operators involved in the analysis are magnetic pseudodifferential operators, a topic which by itself is of interest for the mathematics and mathematical physics community alike. Hence, we will devote two additional chapters to further understanding of properties of those operators. (orig.)

Semiclassical dynamics

International Nuclear Information System (INIS)

Balazs, N.L.

1979-01-01

It is pointed out that in semiclassical dynamics one is encouraged to study the evolution of those curves in phase space which classically represent ensembles corresponding to wave functions. It is shown that the fixed points generate new time scales so that for times longer than the critical times, quantum dynamics will profoundly differ from classical dynamics. (P.L.)

On the semiclassical description of rotating nuclei

International Nuclear Information System (INIS)

Durand, M.; Kunz, J.; Schuck, P.

1983-01-01

The technique of partial h-resummation is used to obtain semiclassical, i.e. average current distributions in the body fixed system of heavy nuclei. It thereby turns out that this average intrinsic current only flows in the nuclear surface. A Strutinsky smoothing of the current is also performed and gives nice agreement with the semiclassical results. We also show how one can incorporate superfluidity into the semiclassical treatment. To lowest order in h we find that the moment of inertia of superfluid nuclei is zero. The same result is obtained by a quantum mechanical calculation if the gap goes to infinity. The importance of including n-corrections is pointed out

Semiclassical description of scattering with internal degrees of freedom

International Nuclear Information System (INIS)

Cruz-Barrios, S.; Gomez-Camacho, J.

1998-01-01

The scattering of systems with internal degrees of freedom is studied in the semi-classical approximation. It is found that a special set of states, named coherent internal states, are specially relevant for the semi-classical treatment. A classical trajectory is defined for each coherent internal state. The semi-classical expressions obtained satisfy the superposition principle and are valid for arbitrary coupling strength. (orig.)

Semiclassical methods in chemical reaction dynamics

Energy Technology Data Exchange (ETDEWEB)

Keshavamurthy, Srihari [Univ. of California, Berkeley, CA (United States)

1994-12-01

Semiclassical approximations, simple as well as rigorous, are formulated in order to be able to describe gas phase chemical reactions in large systems. We formulate a simple but accurate semiclassical model for incorporating multidimensional tunneling in classical trajectory simulations. This model is based on the existence of locally conserved actions around the saddle point region on a multidimensional potential energy surface. Using classical perturbation theory and monitoring the imaginary action as a function of time along a classical trajectory we calculate state-specific unimolecular decay rates for a model two dimensional potential with coupling. Results are in good comparison with exact quantum results for the potential over a wide range of coupling constants. We propose a new semiclassical hybrid method to calculate state-to-state S-matrix elements for bimolecular reactive scattering. The accuracy of the Van Vleck-Gutzwiller propagator and the short time dynamics of the system make this method self-consistent and accurate. We also go beyond the stationary phase approximation by doing the resulting integrals exactly (numerically). As a result, classically forbidden probabilties are calculated with purely real time classical trajectories within this approach. Application to the one dimensional Eckart barrier demonstrates the accuracy of this approach. Successful application of the semiclassical hybrid approach to collinear reactive scattering is prevented by the phenomenon of chaotic scattering. The modified Filinov approach to evaluating the integrals is discussed, but application to collinear systems requires a more careful analysis. In three and higher dimensional scattering systems, chaotic scattering is suppressed and hence the accuracy and usefulness of the semiclassical method should be tested for such systems.

Semiclassical methods in chemical reaction dynamics

International Nuclear Information System (INIS)

Keshavamurthy, S.

1994-12-01

Semiclassical approximations, simple as well as rigorous, are formulated in order to be able to describe gas phase chemical reactions in large systems. We formulate a simple but accurate semiclassical model for incorporating multidimensional tunneling in classical trajectory simulations. This model is based on the existence of locally conserved actions around the saddle point region on a multidimensional potential energy surface. Using classical perturbation theory and monitoring the imaginary action as a function of time along a classical trajectory we calculate state-specific unimolecular decay rates for a model two dimensional potential with coupling. Results are in good comparison with exact quantum results for the potential over a wide range of coupling constants. We propose a new semiclassical hybrid method to calculate state-to-state S-matrix elements for bimolecular reactive scattering. The accuracy of the Van Vleck-Gutzwiller propagator and the short time dynamics of the system make this method self-consistent and accurate. We also go beyond the stationary phase approximation by doing the resulting integrals exactly (numerically). As a result, classically forbidden probabilties are calculated with purely real time classical trajectories within this approach. Application to the one dimensional Eckart barrier demonstrates the accuracy of this approach. Successful application of the semiclassical hybrid approach to collinear reactive scattering is prevented by the phenomenon of chaotic scattering. The modified Filinov approach to evaluating the integrals is discussed, but application to collinear systems requires a more careful analysis. In three and higher dimensional scattering systems, chaotic scattering is suppressed and hence the accuracy and usefulness of the semiclassical method should be tested for such systems

Quantum tunneling beyond semiclassical approximation

International Nuclear Information System (INIS)

Banerjee, Rabin; Majhi, Bibhas Ranjan

2008-01-01

Hawking radiation as tunneling by Hamilton-Jacobi method beyond semiclassical approximation is analysed. We compute all quantum corrections in the single particle action revealing that these are proportional to the usual semiclassical contribution. We show that a simple choice of the proportionality constants reproduces the one loop back reaction effect in the spacetime, found by conformal field theory methods, which modifies the Hawking temperature of the black hole. Using the law of black hole mechanics we give the corrections to the Bekenstein-Hawking area law following from the modified Hawking temperature. Some examples are explicitly worked out.

Decoupling Subtraction Conserving Full Gauge Symmetries : Particles and Fields

OpenAIRE

Noriyasu, OHTSUBO; Hideo, MIYATA; Department of Phycics, Kanazawa Technical College; Department of Information Science, Kanazawa Institute of Technolgy

1984-01-01

A new subtraction scheme (^^^) which realizes the decoupling and conserves the symmetries of full gauge group simultaneously, is proposed. One particle irreducible Green's functions subtracted by ^^^ reveal the effective low energy symmetries at -p^2≪M^2 and the full symmetries at -p^2≫M^2, where M denotes a heavy mass. Also discussed are conditions in order to carry out ^^^ under two-loop approximation.

Quadratic Zeeman spectra for the hydrogen atom by means of semiclassical quantization

International Nuclear Information System (INIS)

Hasegawa, Hiroshi; Adachi, Satoshi

1988-01-01

The elliptic cylindrical coordinates of type I adapted to the Fock hypersphere in momentum space of the Kepler motion and their canonical momenta are used to construct an analytic form of the classical action integrals which yield an adequate parametrization of the KAM (Kolmogorov-Arnold-Moser) tori of the Kepler trajectories weakly perturbed by a uniform magnetic field. The semiclassical quantization formula so provided presents a prototype of the exact EBK (Einstein-Brillouin-Keller) quantization scheme, and the resulting quantized energies vs the magnetic field strength correspond to the quadratic Zeeman spectra of each Rydberg multiplet lifted by the perturbation. (author)

Numerical design of RNnν symmetry-based RF pulse schemes for recoupling and decoupling of nuclear spin interactions at high MAS frequencies

International Nuclear Information System (INIS)

Herbst, Christian; Herbst, Jirada; Leppert, Joerg; Ohlenschlaeger, Oliver; Goerlach, Matthias; Ramachandran, Ramadurai

2009-01-01

An approach for the efficient implementation of RN n ν symmetry-based pulse schemes that are often employed for recoupling and decoupling of nuclear spin interactions in biological solid state NMR investigations is demonstrated at high magic-angle spinning frequencies. RF pulse sequences belonging to the RN n ν symmetry involve the repeated application of the pulse sandwich {R φ R -φ }, corresponding to a propagator U RF = exp(-i4φI z ), where φ = πν/N and R is typically a pulse that rotates the nuclear spins through 180 o about the x-axis. In this study, broadband, phase-modulated 180 o pulses of constant amplitude were employed as the initial 'R' element and the phase-modulation profile of this 'R' element was numerically optimised for generating RN n ν symmetry-based pulse schemes with satisfactory magnetisation transfer characteristics. At representative MAS frequencies, RF pulse sequences were implemented for achieving 13 C- 13 C double-quantum dipolar recoupling and through bond scalar coupling mediated chemical shift correlation and evaluated via numerical simulations and experimental measurements. The results from these investigations are presented here

Second order semiclassics with self-generated magnetic fields

DEFF Research Database (Denmark)

Erdös, Laszlo; Fournais, Søren; Solovej, Jan Philip

2012-01-01

$ effectively determines the strength of the field. We consider the weak field regime with $\\beta h^{2}\\ge {const}>0$, where $h$ is the semiclassical parameter. For smooth potentials we prove that the semiclassical asymptotics of the total energy is given by the non-magnetic Weyl term to leading order...... with an error bound that is smaller by a factor $h^{1+\\e}$, i.e. the subleading term vanishes. However, for potentials with a Coulomb singularity the subleading term does not vanish due to the non-semiclassical effect of the singularity. Combined with a multiscale technique, this refined estimate is used...

Semiclassical theory of plate vibrations

International Nuclear Information System (INIS)

Bogomolny, E.; Hugues, E.

1996-11-01

The bi-harmonic equation of flexural vibrations of elastic plates is studied by a semiclassical method which can easily be generalized for other models of wave propagation. The surface and perimeter terms of the asymptotic number of levels are derived exactly. The next constant term is also derived. A semiclassical approximation of the quantization condition is obtained. A Berry-Tabor formula and a Gutzwiller trace formula are deduced for the integrable and chaotic cases respectively. From 600 eigenvalues of a clamped stadium plate obtained by a specially developed numerical algorithm, the trace formula is assessed, looking at its Fourier transform compared with the membrane case. (author)

Semiclassical shell structure in rotating Fermi systems

International Nuclear Information System (INIS)

Magner, A. G.; Sitdikov, A. S.; Khamzin, A. A.; Bartel, J.

2010-01-01

The collective moment of inertia is derived analytically within the cranking model for any rotational frequency of the harmonic-oscillator potential well and at a finite temperature. Semiclassical shell-structure components of the collective moment of inertia are obtained for any potential by using the periodic-orbit theory. We found semiclassically their relation to the free-energy shell corrections through the shell-structure components of the rigid-body moment of inertia of the statistically equilibrium rotation in terms of short periodic orbits. The shell effects in the moment of inertia exponentially disappear with increasing temperature. For the case of the harmonic-oscillator potential, one observes a perfect agreement of the semiclassical and quantum shell-structure components of the free energy and the moment of inertia for several critical bifurcation deformations and several temperatures.

Nonlinear Decoupling of Torque and Field Amplitude in an Induction Motor

DEFF Research Database (Denmark)

Rasmussen, Henrik; Vadstrup, P.; Børsting, H.

1997-01-01

A novel approach to control of induction motors, based on nonlinear state feedback, is presented. The resulting scheme gives a linearized input-output decoupling of the torque and the amplitude of the field. The proposed approach is used to design controllers for the field amplitude and the motor...... torque. The method is tested both by simulation and by experiments on a motor drive....

On the evaluation of semiclassical nuclear many-particle many-hole level densities

International Nuclear Information System (INIS)

Blin, A.H.; Hiller, B.; Schuck, P.; Yannouleas, C.

1985-10-01

An exact general scheme is described to calculate the m-particle n-hole fermion level densities for an arbitrary single particle Hamiltonian taking into account the Pauli exclusion principle. This technique is applied to obtain level densities of the three dimensional isotropic harmonic oscillator semiclassically in the Thomas-Fermi approach. In addition, we study the l-particle l-hole level density of the Woods-Saxon potential. For the harmonic oscillator we analyze the temperature dependence of the linear response function and the influence of pairing correlations on the l-particle l-hole level density. Finally, a Taylor expansion method of the m-particle n-hole level densities is discussed

Semiclassical approaches to nuclear dynamics

Energy Technology Data Exchange (ETDEWEB)

Magner, A. G., E-mail: magner@kinr.kiev.ua; Gorpinchenko, D. V. [Institute for Nuclear Research NASU (Ukraine); Bartel, J. [Université de Strasbourg, Institut Pluridisciplinaire Hubert Curien, CNRS/IN2P3 (France)

2017-01-15

The extended Gutzwiller trajectory approach is presented for the semiclassical description of nuclear collective dynamics, in line with the main topics of the fruitful activity of V.G. Solovjov. Within the Fermi-liquid droplet model, the leptodermous effective surface approximation was applied to calculations of energies, sum rules, and transition densities for the neutron–proton asymmetry of the isovector giant-dipole resonance and found to be in good agreement with the experimental data. By using the Strutinsky shell correction method, the semiclassical collective transport coefficients, such as nuclear inertia, friction, stiffness, and moments of inertia, can be derived beyond the quantum perturbation approximation of the response function theory and the cranking model. The averaged particle-number dependences of the low-lying collective vibrational states are described in good agreement with the basic experimental data, mainly due to the enhancement of the collective inertia as compared to its irrotational flow value. Shell components of the moment of inertia are derived in terms of the periodic-orbit free-energy shell corrections. A good agreement between the semiclassical extended Thomas–Fermi moments of inertia with shell corrections and the quantum results is obtained for different nuclear deformations and particle numbers. Shell effects are shown to be exponentially dampted out with increasing temperature in all the transport coefficients.

Semiclassical approaches to nuclear dynamics

International Nuclear Information System (INIS)

Magner, A. G.; Gorpinchenko, D. V.; Bartel, J.

2017-01-01

The extended Gutzwiller trajectory approach is presented for the semiclassical description of nuclear collective dynamics, in line with the main topics of the fruitful activity of V.G. Solovjov. Within the Fermi-liquid droplet model, the leptodermous effective surface approximation was applied to calculations of energies, sum rules, and transition densities for the neutron–proton asymmetry of the isovector giant-dipole resonance and found to be in good agreement with the experimental data. By using the Strutinsky shell correction method, the semiclassical collective transport coefficients, such as nuclear inertia, friction, stiffness, and moments of inertia, can be derived beyond the quantum perturbation approximation of the response function theory and the cranking model. The averaged particle-number dependences of the low-lying collective vibrational states are described in good agreement with the basic experimental data, mainly due to the enhancement of the collective inertia as compared to its irrotational flow value. Shell components of the moment of inertia are derived in terms of the periodic-orbit free-energy shell corrections. A good agreement between the semiclassical extended Thomas–Fermi moments of inertia with shell corrections and the quantum results is obtained for different nuclear deformations and particle numbers. Shell effects are shown to be exponentially dampted out with increasing temperature in all the transport coefficients.

A scheme for the hadron spectrum

International Nuclear Information System (INIS)

Hoyer, P.

1978-03-01

A theoretically self-consistent dual scheme is proposed for the hadron spectrum, which follows naturally from basic requirements and phenomenology. All resonance properties and couplings are calculable in terms of a limited number of input parameters. A first application to ππ→ππ explains the linear trajectory and small daughter couplings. The Zweig rule and the decoupling of baryonium from mesons are expected to be consequences of the scheme. (Auth.)

Catalytic Decoupling of Quantum Information

DEFF Research Database (Denmark)

Majenz, Christian; Berta, Mario; Dupuis, Frédéric

2017-01-01

The decoupling technique is a fundamental tool in quantum information theory with applications ranging from quantum thermodynamics to quantum many body physics to the study of black hole radiation. In this work we introduce the notion of catalytic decoupling, that is, decoupling in the presence...... and quantum state merging, and leads to a resource theory of decoupling....

Semi-classical signal analysis

KAUST Repository

Laleg-Kirati, Taous-Meriem; Cré peau, Emmanuelle; Sorine, Michel

2012-01-01

This study introduces a new signal analysis method, based on a semi-classical approach. The main idea in this method is to interpret a pulse-shaped signal as a potential of a Schrödinger operator and then to use the discrete spectrum

Semiclassical multicomponent wave function

NARCIS (Netherlands)

Mostovoy, M.V.

A consistent method for obtaining the semiclassical multicomponent wave function for any value of adiabatic parameter is discussed and illustrated by examining the motion of a neutral particle in a nonuniform magnetic field. The method generalizes the Bohr-Sommerfeld quantization rule to

The MSSM with large tan(beta) beyond the decoupling limit

International Nuclear Information System (INIS)

Hofer, L.; Scherer, D.; Nierste, U.

2009-01-01

If the parameter tan(beta) of the MSSM is large, enhanced loop corrections must be resumed to all orders in perturbation theory. We perform this resummation for flavour-diagonal and flavour-violating tan-beta-enhanced corrections without resorting to the decoupling limit, in which the MSSM is reduced to an effective 2HDM. Our results enable us to clarify the dependence of the resumed expressions on the renormalization scheme and to cover two new classes of processes with supersymmetric particles, which are both intractable with the conventional effective-2HDM method: The first class are collider processes with external supersymmetric particles; the second class are loop processes which vanish in the decoupling limit of supersymmetry. Applying the resummation formulae to FCNC processes in B physics, we find an interesting new effect in observables in which the chromomagnetic effective operator is important. (author)

Nonlinear decoupling of torque and field amplitude in an induction motor

Energy Technology Data Exchange (ETDEWEB)

Rasmussen, H. [Aalborg University, Aalborg (Denmark); Vadstrup, P.; Boersting, H. [Grundfos A/S, Bjerringbro (Denmark)

1997-12-31

A novel approach to control of induction motors, based on nonlinear state feedback, is presented. The resulting scheme gives a linearized input-output decoupling of the torque and the amplitude of the field. The proposed approach is used to design controllers for the field amplitude and the motor torque. The method is tested both by simulation and by experiments on a motor drive. (orig.) 12 refs.

Recoupling and decoupling of nuclear spin interactions at high MAS frequencies: numerical design of CNnν symmetry-based RF pulse schemes

International Nuclear Information System (INIS)

Herbst, Christian; Herbst, Jirada; Kirschstein, Anika; Leppert, Joerg; Ohlenschlaeger, Oliver; Goerlach, Matthias; Ramachandran, Ramadurai

2009-01-01

The CN n ν class of RF pulse schemes, commonly employed for recoupling and decoupling of nuclear spin interactions in magic angle spinning solid state NMR studies of biological systems, involves the application of a basic 'C' element corresponding to an RF cycle with unity propagator. In this study, the design of CN n ν symmetry-based RF pulse sequences for achieving 13 C- 13 C double-quantum dipolar recoupling and through bond scalar coupling mediated 13 C- 13 C chemical shift correlation has been examined at high MAS frequencies employing broadband, constant-amplitude, phase-modulated basic 'C' elements. The basic elements were implemented as a sandwich of a small number of short pulses of equal duration with each pulse characterised by an RF phase value. The phase-modulation profile of the 'C' element was optimised numerically so as to generate efficient RF pulse sequences. The performances of the sequences were evaluated via numerical simulations and experimental measurements and are presented here

Dynamical decoupling of unbounded Hamiltonians

Science.gov (United States)

Arenz, Christian; Burgarth, Daniel; Facchi, Paolo; Hillier, Robin

2018-03-01

We investigate the possibility to suppress interactions between a finite dimensional system and an infinite dimensional environment through a fast sequence of unitary kicks on the finite dimensional system. This method, called dynamical decoupling, is known to work for bounded interactions, but physical environments such as bosonic heat baths are usually modeled with unbounded interactions; hence, here, we initiate a systematic study of dynamical decoupling for unbounded operators. We develop a sufficient decoupling criterion for arbitrary Hamiltonians and a necessary decoupling criterion for semibounded Hamiltonians. We give examples for unbounded Hamiltonians where decoupling works and the limiting evolution as well as the convergence speed can be explicitly computed. We show that decoupling does not always work for unbounded interactions and we provide both physically and mathematically motivated examples.

Decoupling structure and metallogenesis

International Nuclear Information System (INIS)

Tong Hangshou

1993-01-01

The decoupling structure is, at present, a hot spot for the study in geoscience. A study on the decoupling structure is not only of great theoretical significance, but also of more economic importance. The author briefly discusses the study of the decoupling structure in terms of its present status, implication, characteristics, formation mechanism and theoretical significance, in addition, with emphasis on the expounding of the decoupling structure over endogenic metallic deposits such as oil and gas, coal, gold, silver, copper, lead, zinc and iron etc. At last reconsideration is made on the ore control theory of the decoupling structure to the ore control structure in the uranium ore field in South China. The author proposes a superficial idea in order to provide a basis of geological structures for expanding old mining areas, opening up new areas(bases), and prospecting for large and rich uranium deposits

Error of semiclassical eigenvalues in the semiclassical limit - an asymptotic analysis of the Sinai billiard

Science.gov (United States)

Dahlqvist, Per

1999-10-01

We estimate the error in the semiclassical trace formula for the Sinai billiard under the assumption that the largest source of error is due to penumbra diffraction: namely, diffraction effects for trajectories passing within a distance Ricons/Journals/Common/cdot" ALT="cdot" ALIGN="TOP"/>O((kR)-2/3) to the disc and trajectories being scattered in very forward directions. Here k is the momentum and R the radius of the scatterer. The semiclassical error is estimated by perturbing the Berry-Keating formula. The analysis necessitates an asymptotic analysis of very long periodic orbits. This is obtained within an approximation originally due to Baladi, Eckmann and Ruelle. We find that the average error, for sufficiently large values of kR, will exceed the mean level spacing.

Semiclassical initial value treatment of wave functions

International Nuclear Information System (INIS)

Kay, Kenneth G.

2010-01-01

A semiclassical initial value approximation for time-independent wave functions, previously derived for integrable systems, is rederived in a form which allows it to be applied to more general systems. The wave function is expressed as an integral over a Lagrangian manifold that is constructed by propagating trajectories from an initial manifold formed on a Poincare surface. Even in the case of bound, integrable systems, it is unnecessary to identify action-angle variables or construct quantizing tori. The approximation is numerically tested for separable and highly chaotic two-dimensional quartic oscillator systems. For the separable (but highly anharmonic) system, the accuracy of the approximation is found to be excellent: overlaps of the semiclassical wave functions with the corresponding quantum wave functions exceed 0.999. For the chaotic system, semiclassical-quantum overlaps are found to range from 0.989 to 0.994, indicating accuracy that is still very good, despite the short classical trajectories used in the calculations.

Semiclassical quantization of nonadiabatic systems with hopping periodic orbits

International Nuclear Information System (INIS)

Fujii, Mikiya; Yamashita, Koichi

2015-01-01

We present a semiclassical quantization condition, i.e., quantum–classical correspondence, for steady states of nonadiabatic systems consisting of fast and slow degrees of freedom (DOFs) by extending Gutzwiller’s trace formula to a nonadiabatic form. The quantum–classical correspondence indicates that a set of primitive hopping periodic orbits, which are invariant under time evolution in the phase space of the slow DOF, should be quantized. The semiclassical quantization is then applied to a simple nonadiabatic model and accurately reproduces exact quantum energy levels. In addition to the semiclassical quantization condition, we also discuss chaotic dynamics involved in the classical limit of nonadiabatic dynamics

Decoupled Modulation Control

Energy Technology Data Exchange (ETDEWEB)

Wang, Shaobu; Huang, Renke; Huang, Zhenyu; Diao, Ruisheng

2016-06-03

The objective of this research work is to develop decoupled modulation control methods for damping inter-area oscillations with low frequencies, so the damping control can be more effective and easier to design with less interference among different oscillation modes in the power system. A signal-decoupling algorithm was developed that can enable separation of multiple oscillation frequency contents and extraction of a “pure” oscillation frequency mode that are fed into Power System Stabilizers (PSSs) as the modulation input signals. As a result, instead of introducing interferences between different oscillation modes from the traditional approaches, the output of the new PSS modulation control signal mainly affects only one oscillation mode of interest. The new decoupled modulation damping control algorithm has been successfully developed and tested on the standard IEEE 4-machine 2-area test system and a minniWECC system. The results are compared against traditional modulation controls, which demonstrates the validity and effectiveness of the newly-developed decoupled modulation damping control algorithm.

Semiclassical propagator of the Wigner function.

Science.gov (United States)

Dittrich, Thomas; Viviescas, Carlos; Sandoval, Luis

2006-02-24

Propagation of the Wigner function is studied on two levels of semiclassical propagation: one based on the Van Vleck propagator, the other on phase-space path integration. Leading quantum corrections to the classical Liouville propagator take the form of a time-dependent quantum spot. Its oscillatory structure depends on whether the underlying classical flow is elliptic or hyperbolic. It can be interpreted as the result of interference of a pair of classical trajectories, indicating how quantum coherences are to be propagated semiclassically in phase space. The phase-space path-integral approach allows for a finer resolution of the quantum spot in terms of Airy functions.

Semiclassical statistical mechanics

International Nuclear Information System (INIS)

Stratt, R.M.

1979-04-01

On the basis of an approach devised by Miller, a formalism is developed which allows the nonperturbative incorporation of quantum effects into equilibrium classical statistical mechanics. The resulting expressions bear a close similarity to classical phase space integrals and, therefore, are easily molded into forms suitable for examining a wide variety of problems. As a demonstration of this, three such problems are briefly considered: the simple harmonic oscillator, the vibrational state distribution of HCl, and the density-independent radial distribution function of He 4 . A more detailed study is then made of two more general applications involving the statistical mechanics of nonanalytic potentials and of fluids. The former, which is a particularly difficult problem for perturbative schemes, is treated with only limited success by restricting phase space and by adding an effective potential. The problem of fluids, however, is readily found to yield to a semiclassical pairwise interaction approximation, which in turn permits any classical many-body model to be expressed in a convenient form. The remainder of the discussion concentrates on some ramifications of having a phase space version of quantum mechanics. To test the breadth of the formulation, the task of constructing quantal ensemble averages of phase space functions is undertaken, and in the process several limitations of the formalism are revealed. A rather different approach is also pursued. The concept of quantum mechanical ergodicity is examined through the use of numerically evaluated eigenstates of the Barbanis potential, and the existence of this quantal ergodicity - normally associated with classical phase space - is verified. 21 figures, 4 tables

Energy Stability Analysis of Some Fully Discrete Numerical Schemes for Incompressible Navier–Stokes Equations on Staggered Grids

KAUST Repository

Chen, Huangxin

2017-09-01

In this paper we consider the energy stability estimates for some fully discrete schemes which both consider time and spatial discretizations for the incompressible Navier–Stokes equations. We focus on three kinds of fully discrete schemes, i.e., the linear implicit scheme for time discretization with the finite difference method (FDM) on staggered grids for spatial discretization, pressure-correction schemes for time discretization with the FDM on staggered grids for the solutions of the decoupled velocity and pressure equations, and pressure-stabilization schemes for time discretization with the FDM on staggered grids for the solutions of the decoupled velocity and pressure equations. The energy stability estimates are obtained for the above each fully discrete scheme. The upwind scheme is used in the discretization of the convection term which plays an important role in the design of unconditionally stable discrete schemes. Numerical results are given to verify the theoretical analysis.

Semiclassical strings and non-Abelian T-duality

Directory of Open Access Journals (Sweden)

S. Zacarías

2014-10-01

Full Text Available We study semiclassical strings in the Klebanov–Witten and in the non-Abelian T-dual Klebanov–Witten backgrounds. We show that both backgrounds share a subsector of equivalent states up to conditions on the T-dual coordinates. We also analyse string configurations where the strings are stretched along the T-dual coordinates. This semiclassical analysis predicts the existence of (almost chiral primary operators for the dual superconformal field theory whose (anomalous bare dimensions depend on the T-dual coordinates. We briefly discuss the Penrose limit of the dualised background.

On the initial conditions and solutions of the semi-classical Einstein equations in a cosmological scenario

International Nuclear Information System (INIS)

Pinamonti, Nicola

2010-01-01

In this paper we discuss the backreaction of a massive quantum scalar field on the curvature, the latter treated as a classical field. Furthermore, we deal with this problem in the realm of cosmological spacetime by analyzing the Einstein equations in a semiclassical fashion. More precisely, we show that, at least on small intervals of time, solutions for this interacting system exist. This result is achieved furnishing an iteration scheme and showing that it converges in the appropriate Banach space. Moreover, we show that the quantum states with good ultraviolet behavior (Hadamard property) used in order to obtain the backreaction will be completely individuated by their form on the initial surface if chosen to be lightlike. On large intervals of time the situation is more complicated but, if the spacetime is expanding, we show that the end limiting point of the evolution does not depend strongly on the quantum state, because, in this limit, the expectation values of the matter fields responsible for the backreaction do not depend on the particular homogeneous Hadamard state at all. Finally, we comment on the interpretation of the semiclassical Einstein equations for this kind of problems. Although the fluctuations of the expectation values of pointlike fields diverge, if the spacetime and the quantum state have a large spatial symmetry and if we consider the smeared fields on regions of large spatial volume, they tend to vanish. Assuming this point of view the semiclassical Einstein equations become more reliable. (orig.)

On the initial conditions and solutions of the semi-classical Einstein equations in a cosmological scenario

Energy Technology Data Exchange (ETDEWEB)

Pinamonti, Nicola [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

2010-01-15

In this paper we discuss the backreaction of a massive quantum scalar field on the curvature, the latter treated as a classical field. Furthermore, we deal with this problem in the realm of cosmological spacetime by analyzing the Einstein equations in a semiclassical fashion. More precisely, we show that, at least on small intervals of time, solutions for this interacting system exist. This result is achieved furnishing an iteration scheme and showing that it converges in the appropriate Banach space. Moreover, we show that the quantum states with good ultraviolet behavior (Hadamard property) used in order to obtain the backreaction will be completely individuated by their form on the initial surface if chosen to be lightlike. On large intervals of time the situation is more complicated but, if the spacetime is expanding, we show that the end limiting point of the evolution does not depend strongly on the quantum state, because, in this limit, the expectation values of the matter fields responsible for the backreaction do not depend on the particular homogeneous Hadamard state at all. Finally, we comment on the interpretation of the semiclassical Einstein equations for this kind of problems. Although the fluctuations of the expectation values of pointlike fields diverge, if the spacetime and the quantum state have a large spatial symmetry and if we consider the smeared fields on regions of large spatial volume, they tend to vanish. Assuming this point of view the semiclassical Einstein equations become more reliable. (orig.)

Semiclassical analysis of quantum localization of the periodically kicked Rydberg atom

International Nuclear Information System (INIS)

Yoshida, S.; Persson, E.; Burgdoerfer, J.; Grossmann, F.

2004-01-01

The periodically kicked Rydberg atom displays quantum localization, features of which depend on the orientation and strength of the unidirectional kicks. They include scarring of the wave function, localization by cantori, and exponential localization in the regime of strong perturbation resembling dynamical localization. Using the semiclassical Herman-Kluk propagator we investigate the degree to which semiclassical dynamics can mimic quantum localization. While the semiclassical approximation has difficulties to reproduce the scarred wave functions, the exponential tail which is a typical signature of the dynamical localization is well represented in the case of strong classical diffusion. Also the localization by broken tori is observed in the semiclassical recurrence probability for short times but the deviation from the corresponding quantum dynamics becomes more pronounced for the long-time evolution

Interparticle interaction and transport processes in dense semiclassical plasmas

International Nuclear Information System (INIS)

Baimbetov, F.B.; Giniyatova, Sh.G.

2005-01-01

On the basis of the density response formalism an expression for the pseudopotential of dense semiclassical plasma, which takes account of quantum-mechanical effects, local field corrections, and electronic screening effects is obtained. The static structure factors taking into account both local fields and quantum-mechanical effects are calculated. An electrical conductivity, thermal conductivity, and viscosity of dense semiclassical plasma are studied

Semiclassical regime of Regge calculus and spin foams

International Nuclear Information System (INIS)

Bianchi, Eugenio; Satz, Alejandro

2009-01-01

Recent attempts to recover the graviton propagator from spin foam models involve the use of a boundary quantum state peaked on a classical geometry. The question arises whether beyond the case of a single simplex this suffices for peaking the interior geometry in a semiclassical configuration. In this paper we explore this issue in the context of quantum Regge calculus with a general triangulation. Via a stationary phase approximation, we show that the boundary state succeeds in peaking the interior in the appropriate configuration, and that boundary correlations can be computed order by order in an asymptotic expansion. Further, we show that if we replace at each simplex the exponential of the Regge action by its cosine-as expected from the semiclassical limit of spin foam models-then the contribution from the sign-reversed terms is suppressed in the semiclassical regime and the results match those of conventional Regge calculus

General solution to inhomogeneous dephasing and smooth pulse dynamical decoupling

Science.gov (United States)

Zeng, Junkai; Deng, Xiu-Hao; Russo, Antonio; Barnes, Edwin

2018-03-01

In order to achieve the high-fidelity quantum control needed for a broad range of quantum information technologies, reducing the effects of noise and system inhomogeneities is an essential task. It is well known that a system can be decoupled from noise or made insensitive to inhomogeneous dephasing dynamically by using carefully designed pulse sequences based on square or delta-function waveforms such as Hahn spin echo or CPMG. However, such ideal pulses are often challenging to implement experimentally with high fidelity. Here, we uncover a new geometrical framework for visualizing all possible driving fields, which enables one to generate an unlimited number of smooth, experimentally feasible pulses that perform dynamical decoupling or dynamically corrected gates to arbitrarily high order. We demonstrate that this scheme can significantly enhance the fidelity of single-qubit operations in the presence of noise and when realistic limitations on pulse rise times and amplitudes are taken into account.

Semiclassical theory for the nuclear response function

International Nuclear Information System (INIS)

Stroth, U.

1986-01-01

In the first part of this thesis it was demonstrated how on a semiclassical base a RPA theory is developed and applied to electron scattering. It was shown in which fields of nuclear physics this semiclassical theory can be applied and how it is to be understood. In this connection we dedicated an extensive discussion to the Fermi gas model. From the free response function we calculated the RPA response with a finite-range residual interaction which we completely antisymmetrize. In the second part of this thesis we studied with our theory (e,e') data for the separated response functions. (orig./HSI) [de

Stellar Equilibrium in Semiclassical Gravity.

Science.gov (United States)

Carballo-Rubio, Raúl

2018-02-09

The phenomenon of quantum vacuum polarization in the presence of a gravitational field is well understood and is expected to have a physical reality, but studies of its backreaction on the dynamics of spacetime are practically nonexistent outside of the specific context of homogeneous cosmologies. Building on previous results of quantum field theory in curved spacetimes, in this Letter we first derive the semiclassical equations of stellar equilibrium in the s-wave Polyakov approximation. It is highlighted that incorporating the polarization of the quantum vacuum leads to a generalization of the classical Tolman-Oppenheimer-Volkoff equation. Despite the complexity of the resulting field equations, it is possible to find exact solutions. Aside from being the first known exact solutions that describe relativistic stars including the nonperturbative backreaction of semiclassical effects, these are identified as a nontrivial combination of the black star and gravastar proposals.

Semiclassical modelling of finite-pulse effects on non-adiabatic photodynamics via initial condition filtering: The predissociation of NaI as a test case

Energy Technology Data Exchange (ETDEWEB)

Martínez-Mesa, Aliezer [Departmento de Física Teórica, Universidad de la Habana, San Lázaro y L, La Habana 10400 (Cuba); Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, D-14476 Potsdam-Golm (Germany); Saalfrank, Peter [Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, D-14476 Potsdam-Golm (Germany)

2015-05-21

Femtosecond-laser pulse driven non-adiabatic spectroscopy and dynamics in molecular and condensed phase systems continue to be a challenge for theoretical modelling. One of the main obstacles is the “curse of dimensionality” encountered in non-adiabatic, exact wavepacket propagation. A possible route towards treating complex molecular systems is via semiclassical surface-hopping schemes, in particular if they account not only for non-adiabatic post-excitation dynamics but also for the initial optical excitation. One such approach, based on initial condition filtering, will be put forward in what follows. As a simple test case which can be compared with exact wavepacket dynamics, we investigate the influence of the different parameters determining the shape of a laser pulse (e.g., its finite width and a possible chirp) on the predissociation dynamics of a NaI molecule, upon photoexcitation of the A(0{sup +}) state. The finite-pulse effects are mapped into the initial conditions for semiclassical surface-hopping simulations. The simulated surface-hopping diabatic populations are in qualitative agreement with the quantum mechanical results, especially concerning the subpicosend photoinduced dynamics, the main deviations being the relative delay of the non-adiabatic transitions in the semiclassical picture. Likewise, these differences in the time-dependent electronic populations calculated via the semiclassical and the quantum methods are found to have a mild influence on the overall probability density distribution. As a result, the branching ratios between the bound and the dissociative reaction channels and the time-evolution of the molecular wavepacket predicted by the semiclassical method agree with those computed using quantum wavepacket propagation. Implications for more challenging molecular systems are given.

Method for decoupling error correction from privacy amplification

Energy Technology Data Exchange (ETDEWEB)

Lo, Hoi-Kwong [Department of Electrical and Computer Engineering and Department of Physics, University of Toronto, 10 King' s College Road, Toronto, Ontario, Canada, M5S 3G4 (Canada)

2003-04-01

In a standard quantum key distribution (QKD) scheme such as BB84, two procedures, error correction and privacy amplification, are applied to extract a final secure key from a raw key generated from quantum transmission. To simplify the study of protocols, it is commonly assumed that the two procedures can be decoupled from each other. While such a decoupling assumption may be valid for individual attacks, it is actually unproven in the context of ultimate or unconditional security, which is the Holy Grail of quantum cryptography. In particular, this means that the application of standard efficient two-way error-correction protocols like Cascade is not proven to be unconditionally secure. Here, I provide the first proof of such a decoupling principle in the context of unconditional security. The method requires Alice and Bob to share some initial secret string and use it to encrypt their communications in the error correction stage using one-time-pad encryption. Consequently, I prove the unconditional security of the interactive Cascade protocol proposed by Brassard and Salvail for error correction and modified by one-time-pad encryption of the error syndrome, followed by the random matrix protocol for privacy amplification. This is an efficient protocol in terms of both computational power and key generation rate. My proof uses the entanglement purification approach to security proofs of QKD. The proof applies to all adaptive symmetric methods for error correction, which cover all existing methods proposed for BB84. In terms of the net key generation rate, the new method is as efficient as the standard Shor-Preskill proof.

Method for decoupling error correction from privacy amplification

International Nuclear Information System (INIS)

Lo, Hoi-Kwong

2003-01-01

In a standard quantum key distribution (QKD) scheme such as BB84, two procedures, error correction and privacy amplification, are applied to extract a final secure key from a raw key generated from quantum transmission. To simplify the study of protocols, it is commonly assumed that the two procedures can be decoupled from each other. While such a decoupling assumption may be valid for individual attacks, it is actually unproven in the context of ultimate or unconditional security, which is the Holy Grail of quantum cryptography. In particular, this means that the application of standard efficient two-way error-correction protocols like Cascade is not proven to be unconditionally secure. Here, I provide the first proof of such a decoupling principle in the context of unconditional security. The method requires Alice and Bob to share some initial secret string and use it to encrypt their communications in the error correction stage using one-time-pad encryption. Consequently, I prove the unconditional security of the interactive Cascade protocol proposed by Brassard and Salvail for error correction and modified by one-time-pad encryption of the error syndrome, followed by the random matrix protocol for privacy amplification. This is an efficient protocol in terms of both computational power and key generation rate. My proof uses the entanglement purification approach to security proofs of QKD. The proof applies to all adaptive symmetric methods for error correction, which cover all existing methods proposed for BB84. In terms of the net key generation rate, the new method is as efficient as the standard Shor-Preskill proof

Application of the decoupling scheme on complex neutron-gamma shielding problems

Energy Technology Data Exchange (ETDEWEB)

Feher, S. [Institute of Nuclear Technology, Technical University of Budapest, Budapest (Hungary); Leege, P.F.A. de; Hoogenboom, J.E.; Kloosterman, J.L. [Interfaculty Reactor Institute, Delft University of Technology, Delft (Netherlands)

2000-03-01

Coupled neutron-gamma shielding calculations using S{sub n} transport theory can be time consuming, especially for two- and three-dimensional geometries. In general, the CPU time of these calculations increases stronger than linear with increasing number of neutron and gamma energy groups, and depends on the order of Legendre expansion and number of S{sub n} directions used. This fact induced the idea of the decoupling method, which seems applicable to accelerate coupled neutron-gamma shielding calculations. The data included in a combined neutron-gamma library can be readily separated into a library containing neutron data only and another library containing gamma data only. Separate calculations for neutrons and gammas are performed on complex geometries using a different Legendre order expansion for neutrons and gammas. CPU savings of 60 to 85% can be achieved for the two-dimensional DORT and three-dimensional TORT calculations respectively. (author)

Spurious Excitations in Semiclassical Scattering Theory.

Science.gov (United States)

Gross, D. H. E.; And Others

1980-01-01

Shows how through proper handling of the nonuniform motion of semiclassical coordinates spurious excitation terms are eliminated. An application to the problem of nuclear Coulomb excitation is presented as an example. (HM)

Stability and semiclassics in self-generated fields

DEFF Research Database (Denmark)

Erdös, Laszlo; Fournais, Søren; Solovej, Jan Philip

2013-01-01

We consider non-interacting particles subject to a fixed external potential V and a self-generated magnetic field B. The total energy includes the field energy β∫B^2 and we minimize over all particle states and magnetic fields. In the case of spin-1/2 particles this minimization leads...... measuring the field strength in the semiclassical limit is κ=βh. We are not able to give the exact leading order semiclassical asymptotics uniformly in κ or even for fixed κ. We do however give upper and lower bounds on E with almost matching dependence on κ. In the simultaneous limit h→0 and κ→∞ we show...

A semi-classical analysis of Dirac fermions in 2+1 dimensions

International Nuclear Information System (INIS)

Maiti, Moitri; Shankar, R

2012-01-01

We investigate the semi-classical dynamics of massless Dirac fermions in 2+1 dimensions in the presence of external electromagnetic fields. By generalizing the α matrices by two generators of the SU(2) group in the (2S + 1)-dimensional representation and doing a certain scaling, we formulate an S → ∞ limit where the orbital and the spinor degrees become classical. We solve for the classical trajectories for a free particle on a cylinder and a particle in a constant magnetic field. We compare the semi-classical spectrum, obtained by Bohr–Sommerfeld quantization with the exact quantum spectrum for low values of S. For the free particle, the semi-classical spectrum is exact. For the particle in a constant magnetic field, the semi-classical spectrum reproduces all the qualitative features of the exact quantum spectrum at all S. The quantitative fit for S = 1/2 is reasonably good. (paper)

Semiclassical approach to mesoscopic systems classical trajectory correlations and wave interference

CERN Document Server

Waltner, Daniel

2012-01-01

This volume describes mesoscopic systems with classically chaotic dynamics using semiclassical methods which combine elements of classical dynamics and quantum interference effects. Experiments and numerical studies show that Random Matrix Theory (RMT) explains physical properties of these systems well. This was conjectured more than 25 years ago by Bohigas, Giannoni and Schmit for the spectral properties. Since then, it has been a challenge to understand this connection analytically.  The author offers his readers a clearly-written and up-to-date treatment of the topics covered. He extends previous semiclassical approaches that treated spectral and conductance properties. He shows that RMT results can in general only be obtained semiclassically when taking into account classical configurations not considered previously, for example those containing multiply traversed periodic orbits. Furthermore, semiclassics is capable of describing effects beyond RMT. In this context he studies the effect of a non-zero Eh...

Microscopic and semi-classical treatments of octupole deformation in the light actinides

International Nuclear Information System (INIS)

Chasman, R.R.

1984-01-01

Microscopic and semi-classical descriptions of octupole deformation are compared. New semi-classical results, obtained with the use of a Woods-Saxon potential are presented. Comparisons with experiment are made. 21 references

Decoupling Responsible Management Education

DEFF Research Database (Denmark)

Rasche, Andreas; Gilbert, Dirk Ulrich

2015-01-01

This article examines under what conditions business schools may decouple the structural effects of their engagement in responsible management education from actual organizational practices. We argue that schools may be unable to match rising institutional pressures to publicly commit to responsi......This article examines under what conditions business schools may decouple the structural effects of their engagement in responsible management education from actual organizational practices. We argue that schools may be unable to match rising institutional pressures to publicly commit...... to responsible management education with their limited internal capacity for change. Our analysis proposes that decoupling is likely if schools (a) are exposed to resource stringency, (b) face overt or covert resistance against change processes, (c) are confronted with competing institutional pressures, and (d......) perceive institutional demands as ambiguous. We discuss two implications of this proposition. On one hand, decoupling can cause dissonant legitimacy perceptions, leading to cynicism around responsible management education within business schools. On the other hand, a temporary inconsistency between talk...

Wigner measure and semiclassical limits of nonlinear Schrödinger equations

CERN Document Server

Zhang, Ping

2008-01-01

This book is based on a course entitled "Wigner measures and semiclassical limits of nonlinear Schrödinger equations," which the author taught at the Courant Institute of Mathematical Sciences at New York University in the spring of 2007. The author's main purpose is to apply the theory of semiclassical pseudodifferential operators to the study of various high-frequency limits of equations from quantum mechanics. In particular, the focus of attention is on Wigner measure and recent progress on how to use it as a tool to study various problems arising from semiclassical limits of Schrödinger-ty

Semiclassical geometry of integrable systems

Science.gov (United States)

Reshetikhin, Nicolai

2018-04-01

The main result of this paper is a formula for the scalar product of semiclassical eigenvectors of two integrable systems on the same symplectic manifold. An important application of this formula is the Ponzano–Regge type of asymptotic of Racah–Wigner coefficients. Dedicated to the memory of P P Kulish.

New advection schemes for free surface flows

International Nuclear Information System (INIS)

Pavan, Sara

2016-01-01

The purpose of this thesis is to build higher order and less diffusive schemes for pollutant transport in shallow water flows or 3D free surface flows. We want robust schemes which respect the main mathematical properties of the advection equation with relatively low numerical diffusion and apply them to environmental industrial applications. Two techniques are tested in this work: a classical finite volume method and a residual distribution technique combined with a finite element method. For both methods we propose a decoupled approach since it is the most advantageous in terms of accuracy and CPU time. Concerning the first technique, a vertex-centred finite volume method is used to solve the augmented shallow water system where the numerical flux is computed through an Harten-Lax-Van Leer-Contact Riemann solver. Starting from this solution, a decoupled approach is formulated and is preferred since it allows to compute with a larger time step the advection of a tracer. This idea was inspired by Audusse, E. and Bristeau, M.O. [13]. The Monotonic Upwind Scheme for Conservation Law, combined with the decoupled approach, is then used for the second order extension in space. The wetting and drying problem is also analysed and a possible solution is presented. In the second case, the shallow water system is entirely solved using the finite element technique and the residual distribution method is applied to the solution of the tracer equation, focusing on the case of time-dependent problems. However, for consistency reasons the resolution of the continuity equation must be considered in the numerical discretization of the tracer. In order to get second order schemes for unsteady cases a predictor-corrector scheme is used in this work. A first order but less diffusive version of the predictor-corrector scheme is also introduced. Moreover, we also present a new locally semi-implicit version of the residual distribution method which, in addition to good properties in

FRF decoupling of nonlinear systems

Science.gov (United States)

Kalaycıoğlu, Taner; Özgüven, H. Nevzat

2018-03-01

Structural decoupling problem, i.e. predicting dynamic behavior of a particular substructure from the knowledge of the dynamics of the coupled structure and the other substructure, has been well investigated for three decades and led to several decoupling methods. In spite of the inherent nonlinearities in a structural system in various forms such as clearances, friction and nonlinear stiffness, all decoupling studies are for linear systems. In this study, decoupling problem for nonlinear systems is addressed for the first time. A method, named as FRF Decoupling Method for Nonlinear Systems (FDM-NS), is proposed for calculating FRFs of a substructure decoupled from a coupled nonlinear structure where nonlinearity can be modeled as a single nonlinear element. Depending on where nonlinear element is, i.e., either in the known or unknown subsystem, or at the connection point, the formulation differs. The method requires relative displacement information between two end points of the nonlinear element, in addition to point and transfer FRFs at some points of the known subsystem. However, it is not necessary to excite the system from the unknown subsystem even when the nonlinear element is in that subsystem. The validation of FDM-NS is demonstrated with two different case studies using nonlinear lumped parameter systems. Finally, a nonlinear experimental test structure is used in order to show the real-life application and accuracy of FDM-NS.

Regularized semiclassical limits: Linear flows with infinite Lyapunov exponents

KAUST Repository

Athanassoulis, Agissilaos; Katsaounis, Theodoros; Kyza, Irene

2016-01-01

Semiclassical asymptotics for Schrödinger equations with non-smooth potentials give rise to ill-posed formal semiclassical limits. These problems have attracted a lot of attention in the last few years, as a proxy for the treatment of eigenvalue crossings, i.e. general systems. It has recently been shown that the semiclassical limit for conical singularities is in fact well-posed, as long as the Wigner measure (WM) stays away from singular saddle points. In this work we develop a family of refined semiclassical estimates, and use them to derive regularized transport equations for saddle points with infinite Lyapunov exponents, extending the aforementioned recent results. In the process we answer a related question posed by P.L. Lions and T. Paul in 1993. If we consider more singular potentials, our rigorous estimates break down. To investigate whether conical saddle points, such as -|x|, admit a regularized transport asymptotic approximation, we employ a numerical solver based on posteriori error control. Thus rigorous upper bounds for the asymptotic error in concrete problems are generated. In particular, specific phenomena which render invalid any regularized transport for -|x| are identified and quantified. In that sense our rigorous results are sharp. Finally, we use our findings to formulate a precise conjecture for the condition under which conical saddle points admit a regularized transport solution for the WM. © 2016 International Press.

Regularized semiclassical limits: Linear flows with infinite Lyapunov exponents

KAUST Repository

Athanassoulis, Agissilaos

2016-08-30

Semiclassical asymptotics for Schrödinger equations with non-smooth potentials give rise to ill-posed formal semiclassical limits. These problems have attracted a lot of attention in the last few years, as a proxy for the treatment of eigenvalue crossings, i.e. general systems. It has recently been shown that the semiclassical limit for conical singularities is in fact well-posed, as long as the Wigner measure (WM) stays away from singular saddle points. In this work we develop a family of refined semiclassical estimates, and use them to derive regularized transport equations for saddle points with infinite Lyapunov exponents, extending the aforementioned recent results. In the process we answer a related question posed by P.L. Lions and T. Paul in 1993. If we consider more singular potentials, our rigorous estimates break down. To investigate whether conical saddle points, such as -|x|, admit a regularized transport asymptotic approximation, we employ a numerical solver based on posteriori error control. Thus rigorous upper bounds for the asymptotic error in concrete problems are generated. In particular, specific phenomena which render invalid any regularized transport for -|x| are identified and quantified. In that sense our rigorous results are sharp. Finally, we use our findings to formulate a precise conjecture for the condition under which conical saddle points admit a regularized transport solution for the WM. © 2016 International Press.

Closed almost-periodic orbits in semiclassical quantization of generic polygons

Science.gov (United States)

Biswas

2000-05-01

Periodic orbits are the central ingredients of modern semiclassical theories and corrections to these are generally nonclassical in origin. We show here that, for the class of generic polygonal billiards, the corrections are predominantly classical in origin owing to the contributions from closed almost-periodic (CAP) orbit families. Furthermore, CAP orbit families outnumber periodic families but have comparable weights. They are hence indispensable for semiclassical quantization.

A zeta function approach to the semiclassical quantization of maps

International Nuclear Information System (INIS)

Smilansky, Uzi.

1993-11-01

The quantum analogue of an area preserving map on a compact phase space is a unitary (evolution) operator which can be represented by a matrix of dimension L∝ℎ -1 . The semiclassical theory for spectrum of the evolution operator will be reviewed with special emphasize on developing a dynamical zeta function approach, similar to the one introduced recently for a semiclassical quantization of hamiltonian systems. (author)

Linearly decoupled energy-stable numerical methods for multi-component two-phase compressible flow

KAUST Repository

Kou, Jisheng

2017-12-06

In this paper, for the first time we propose two linear, decoupled, energy-stable numerical schemes for multi-component two-phase compressible flow with a realistic equation of state (e.g. Peng-Robinson equation of state). The methods are constructed based on the scalar auxiliary variable (SAV) approaches for Helmholtz free energy and the intermediate velocities that are designed to decouple the tight relationship between velocity and molar densities. The intermediate velocities are also involved in the discrete momentum equation to ensure a consistency relationship with the mass balance equations. Moreover, we propose a component-wise SAV approach for a multi-component fluid, which requires solving a sequence of linear, separate mass balance equations. We prove that the methods have the unconditional energy-dissipation feature. Numerical results are presented to verify the effectiveness of the proposed methods.

Graphics processing units accelerated semiclassical initial value representation molecular dynamics

Energy Technology Data Exchange (ETDEWEB)

Tamascelli, Dario; Dambrosio, Francesco Saverio [Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); Conte, Riccardo [Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322 (United States); Ceotto, Michele, E-mail: michele.ceotto@unimi.it [Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano (Italy)

2014-05-07

This paper presents a Graphics Processing Units (GPUs) implementation of the Semiclassical Initial Value Representation (SC-IVR) propagator for vibrational molecular spectroscopy calculations. The time-averaging formulation of the SC-IVR for power spectrum calculations is employed. Details about the GPU implementation of the semiclassical code are provided. Four molecules with an increasing number of atoms are considered and the GPU-calculated vibrational frequencies perfectly match the benchmark values. The computational time scaling of two GPUs (NVIDIA Tesla C2075 and Kepler K20), respectively, versus two CPUs (Intel Core i5 and Intel Xeon E5-2687W) and the critical issues related to the GPU implementation are discussed. The resulting reduction in computational time and power consumption is significant and semiclassical GPU calculations are shown to be environment friendly.

Decoupling

NARCIS (Netherlands)

Fletcher, Robert; Rammelt, Crelis

2017-01-01

Central to the United Nations’ post-2015 development agenda grounded in the Sustainable Development Goals is the notion of ‘decoupling’: the need to divorce economic growth from its ecological impact. For proponents, decoupling entails increasing the efficiency with which value is derived from

Numerical indications on the semiclassical limit of the flipped vertex

Energy Technology Data Exchange (ETDEWEB)

Magliaro, Elena; Perini, Claudio; Rovelli, Carlo [Centre de Physique Theorique de Luminy , Case 907, F-13288 Marseille (France)

2008-05-07

We introduce a technique for testing the semiclassical limit of a quantum gravity vertex amplitude. The technique is based on the propagation of a semiclassical wave packet. We apply this technique to the newly introduced 'flipped' vertex in loop quantum gravity, in order to test the intertwiner dependence of the vertex. Under some drastic simplifications, we find very preliminary, but surprisingly good numerical evidence for the correct classical limit.

Selective Regulator Decoupling and Organizations' Strategic Responses

NARCIS (Netherlands)

Heese, Jonas; Krishnan, Ranjani; Moers, Frank

2016-01-01

Organizations often respond to institutional pressures by symbolically adopting policies and procedures but decoupling them from actual practice. Literature has examined why organizations decouple from regulatory pressures. In this study, we argue that decoupling occurs within regulatory agencies

Dispersions in Semi-Classical Dynamics

International Nuclear Information System (INIS)

Zielinska-Pfabe, M.; Gregoire, C.

1987-01-01

Dispersions around mean values of one-body observables are obtained by restoring classical many-body correlations in Vlasov and Landau-Vlasov dynamics. The method is applied to the calculation of fluctuations in mass, charge and linear momentum in heavy-ion collisions. Results are compared to those obtained by the Balian-Veneroni variational principle in semi-classical approximation

Semiclassical analysis of quasiexact solvability

International Nuclear Information System (INIS)

Bender, C.M.; Dunne, G.V.; Moshe, M.

1997-01-01

Higher-order WKB methods are used to investigate the border between the solvable and insolvable portions of the spectrum of quasiexactly solvable quantum-mechanical potentials. The analysis reveals scaling and factorization properties that are central to quasiexact solvability. These two properties define a new class of semiclassically quasiexactly solvable potentials. copyright 1997 The American Physical Society

Some applications of semiclassical methods to quantum chaos

International Nuclear Information System (INIS)

Mouchet, A.

1996-01-01

This thesis is made of four chapters. The first chapter is devoted to the description of the band structure, using the semiclassical periodic orbit theory, for a one electron system in a two-dimensional crystal with a high magnetic field perpendicular to the crystal plane. Complex orbits turn out to be fundamental for a proper description of the band structure since they incorporate conduction processes through tunneling mechanisms. In the second part, the author focuses on the role played in semiclassical expansions by complex orbits. They give exponentially small contribution when h is small only in a precise situation. In all other cases, complex orbits give birth to corrections in powers in h but unlike the extreme case they are hidden in the shadow of usual Gutzwiller contributions of real orbits. In the third chapter, a semiclassical expansion of the Berry two-form in terms of finite number of periodic orbits for a discrete chaotic map defined on a compact phase space and governed by external parameters is given. Besides, when dealing with a toroidal geometry, the author gives a similar expansion for the Chern index of any Bloch band of the quasi-energy spectrum and is thus led to a semiclassical interpretation of the Hall effect. In the last chapter, the author sets out a mechanism to explain how symmetries can create Berry phase shifts higher than 2π in a 3D-adiabatic transport. He shows how one can understand in a topological point of view why these shifts are necessarily integer multiple of 2π. An explicit construction of such arbitrary large phase shifts is finally proposed. (N.T.)

Moments of inertia in a semiclassical approach

International Nuclear Information System (INIS)

Benchein, K.

1993-01-01

Semiclassical calculations have been performed for 31 nuclei. As a result of preliminary non-fully self-consistent calculations, the moments of inertia in investigated nuclei abd spin degrees of freedom are found

Unconditionally energy stable numerical schemes for phase-field vesicle membrane model

Science.gov (United States)

Guillén-González, F.; Tierra, G.

2018-02-01

Numerical schemes to simulate the deformation of vesicles membranes via minimizing the bending energy have been widely studied in recent times due to its connection with many biological motivated problems. In this work we propose a new unconditionally energy stable numerical scheme for a vesicle membrane model that satisfies exactly the conservation of volume constraint and penalizes the surface area constraint. Moreover, we extend these ideas to present an unconditionally energy stable splitting scheme decoupling the interaction of the vesicle with a surrounding fluid. Finally, the well behavior of the proposed schemes are illustrated through several computational experiments.

Semiclassical limit and well-posedness of nonlinear Schrodinger-Poisson systems

Directory of Open Access Journals (Sweden)

Hailiang Li

2003-09-01

Full Text Available This paper concerns the well-posedness and semiclassical limit of nonlinear Schrodinger-Poisson systems. We show the local well-posedness and the existence of semiclassical limit of the two models for initial data with Sobolev regularity, before shocks appear in the limit system. We establish the existence of a global solution and show the time-asymptotic behavior of a classical solutions of Schrodinger-Poisson system for a fixed re-scaled Planck constant.

Fast Automated Decoupling at RHIC

CERN Document Server

Beebe-Wang, Joanne

2005-01-01

Coupling correction is essential for the operational performance of RHIC. The independence of the transverse degrees of freedom makes diagnostics and tune control easier, and it is advantageous to operate an accelerator close to the coupling resonance to minimize nearby nonlinear sidebands. An automated decoupling application has been developed at RHIC for coupling correction during routine operations. The application decouples RHIC globally by minimizing the tune separation through finding the optimal settings of two orthogonal skew quadrupole families. The program provides options of automatic, semi-automatic and manual decoupling operations. It accesses tune information from all RHIC tune measurement systems: the PLL (Phase Lock Loop), the high frequency Schottky system, and the tune meter. It also supplies tune and skew quadrupole scans, finding the minimum tune separation, display the real time results and interface with the RHIC control system. We summarize the capabilities of the decoupling application...

A qualitative semi-classical treatment of an isolated semi-polar quantum dot

International Nuclear Information System (INIS)

Young, Toby D

2011-01-01

To qualitatively determine the behaviour of micro-macro properties of a quantum dot grown in a non-polar direction, we propose a simple semi-classical model based on well established ideas. We take into account the following empirical phenomena: (i) The displacement and induced strain at heterojunctions; (ii) The electrostatic potential arising from piezoelectric and spontaneous polarisation; and (iii) The localisation of excitons (particle-hole pairs) arising from quantum confinement. After some algebraic manipulation used to cast the formalism into an arbitrarily rotated frame, a numerical model is developed for the case of a semi-polar wurtzite GaN quantum dot buried in a wurtzite AlN matrix. This scheme is found to provide a satisfying qualitative description of an isolated semi-polar quantum dot in a way that is accessible to further physical interpretation and quantification.

Semiclassical unimodular gravity

International Nuclear Information System (INIS)

Fiol, Bartomeu; Garriga, Jaume

2010-01-01

Classically, unimodular gravity is known to be equivalent to General Relativity (GR), except for the fact that the effective cosmological constant Λ has the status of an integration constant. Here, we explore various formulations of unimodular gravity beyond the classical limit. We first consider the non-generally covariant action formulation in which the determinant of the metric is held fixed to unity. We argue that the corresponding quantum theory is also equivalent to General Relativity for localized perturbative processes which take place in generic backgrounds of infinite volume (such as asymptotically flat spacetimes). Next, using the same action, we calculate semiclassical non-perturbative quantities, which we expect will be dominated by Euclidean instanton solutions. We derive the entropy/area ratio for cosmological and black hole horizons, finding agreement with GR for solutions in backgrounds of infinite volume, but disagreement for backgrounds with finite volume. In deriving the above results, the path integral is taken over histories with fixed 4-volume. We point out that the results are different if we allow the 4-volume of the different histories to vary over a continuum range. In this ''generalized'' version of unimodular gravity, one recovers the full set of Einstein's equations in the classical limit, including the trace, so Λ is no longer an integration constant. Finally, we consider the generally covariant theory due to Henneaux and Teitelboim, which is classically equivalent to unimodular gravity. In this case, the standard semiclassical GR results are recovered provided that the boundary term in the Euclidean action is chosen appropriately

Decoherence and back reaction: The origin of the semiclassical Einstein equations

International Nuclear Information System (INIS)

Paz, J.P.; Sinha, S.

1991-01-01

Two basic properties defining classical behavior are ''decoherence'' and ''correlations between coordinates and momenta.'' We study how the correlations that define the semiclassical decohering histories of the relevant cosmological variables are affected by the interaction with an environment formed by unobserved (''irrelevant'') degrees of freedom. For some quantum cosmological models we analyze under what conditions the semiclassical coarse-grained histories obey the so-called semiclassical Einstein's equations (i.e., G μν =κ left-angle T μν right-angle). These equations are shown to be valid only as a description of adiabatic regions of histories for which the interference effects have been suppressed. We also discuss the problem related to the existence of divergences in the decoherence factor of various quantum cosmological models

Exact decoupling of the Dirac Hamiltonian. II. The generalized Douglas-Kroll-Hess transformation up to arbitrary order

International Nuclear Information System (INIS)

Reiher, Markus; Wolf, Alexander

2004-01-01

In order to achieve exact decoupling of the Dirac Hamiltonian within a unitary transformation scheme, we have discussed in part I of this series that either a purely numerical iterative technique (the Barysz-Sadlej-Snijders method) or a stepwise analytic approach (the Douglas-Kroll-Hess method) are possible. For the evaluation of Douglas-Kroll-Hess Hamiltonians up to a pre-defined order it was shown that a symbolic scheme has to be employed. In this work, an algorithm for this analytic derivation of Douglas-Kroll-Hess Hamiltonians up to any arbitrary order in the external potential is presented. We discuss how an estimate for the necessary order for exact decoupling (within machine precision) for a given system can be determined from the convergence behavior of the Douglas-Kroll-Hess expansion prior to a quantum chemical calculation. Once this maximum order has been accomplished, the spectrum of the positive-energy part of the decoupled Hamiltonian, e.g., for electronic bound states, cannot be distinguished from the corresponding part of the spectrum of the Dirac operator. An efficient scalar-relativistic implementation of the symbolic operations for the evaluation of the positive-energy part of the block-diagonal Hamiltonian is presented, and its accuracy is tested for ground-state energies of one-electron ions over the whole periodic table. Furthermore, the first many-electron calculations employing sixth up to fourteenth order DKH Hamiltonians are presented

Exact decoupling of the Dirac Hamiltonian. II. The generalized Douglas-Kroll-Hess transformation up to arbitrary order.

Science.gov (United States)

Reiher, Markus; Wolf, Alexander

2004-12-08

In order to achieve exact decoupling of the Dirac Hamiltonian within a unitary transformation scheme, we have discussed in part I of this series that either a purely numerical iterative technique (the Barysz-Sadlej-Snijders method) or a stepwise analytic approach (the Douglas-Kroll-Hess method) are possible. For the evaluation of Douglas-Kroll-Hess Hamiltonians up to a pre-defined order it was shown that a symbolic scheme has to be employed. In this work, an algorithm for this analytic derivation of Douglas-Kroll-Hess Hamiltonians up to any arbitrary order in the external potential is presented. We discuss how an estimate for the necessary order for exact decoupling (within machine precision) for a given system can be determined from the convergence behavior of the Douglas-Kroll-Hess expansion prior to a quantum chemical calculation. Once this maximum order has been accomplished, the spectrum of the positive-energy part of the decoupled Hamiltonian, e.g., for electronic bound states, cannot be distinguished from the corresponding part of the spectrum of the Dirac operator. An efficient scalar-relativistic implementation of the symbolic operations for the evaluation of the positive-energy part of the block-diagonal Hamiltonian is presented, and its accuracy is tested for ground-state energies of one-electron ions over the whole periodic table. Furthermore, the first many-electron calculations employing sixth up to fourteenth order DKH Hamiltonians are presented. (c) 2004 American Institute of Physics.

Semi-classical signal analysis

KAUST Repository

Laleg-Kirati, Taous-Meriem

2012-09-30

This study introduces a new signal analysis method, based on a semi-classical approach. The main idea in this method is to interpret a pulse-shaped signal as a potential of a Schrödinger operator and then to use the discrete spectrum of this operator for the analysis of the signal. We present some numerical examples and the first results obtained with this method on the analysis of arterial blood pressure waveforms. © 2012 Springer-Verlag London Limited.

Semiclassical S-matrix for black holes

CERN Document Server

Bezrukov, Fedor; Sibiryakov, Sergey

2015-01-01

We propose a semiclassical method to calculate S-matrix elements for two-stage gravitational transitions involving matter collapse into a black hole and evaporation of the latter. The method consistently incorporates back-reaction of the collapsing and emitted quanta on the metric. We illustrate the method in several toy models describing spherical self-gravitating shells in asymptotically flat and AdS space-times. We find that electrically neutral shells reflect via the above collapse-evaporation process with probability exp(-B), where B is the Bekenstein-Hawking entropy of the intermediate black hole. This is consistent with interpretation of exp(B) as the number of black hole states. The same expression for the probability is obtained in the case of charged shells if one takes into account instability of the Cauchy horizon of the intermediate Reissner-Nordstrom black hole. Our semiclassical method opens a new systematic approach to the gravitational S-matrix in the non-perturbative regime.

Hedge Funds and Risk-Decoupling

DEFF Research Database (Denmark)

Ringe, Wolf-Georg

Negative risk-decoupling, otherwise known as empty voting, is a popular strategy amongst hedge funds and other activist investors. In short, it is the attempt to decouple the economic risk from the share’s ownership position, retaining in particular the voting right without risk. This paper uses ...

Decoupling theorem in supersymmetric theories

Energy Technology Data Exchange (ETDEWEB)

Leon, J; Perez-Mercader, J; Sanchez, M F

1988-07-21

We introduce a superfield extension of Weisberger's method for decoupling calculations in multiscale field theories and generalize our previous method which does not require the computation of any Feynman diagram. We illustrate this for the two-scale Wess-Zumino model, showing explicitly how the decoupling takes place.

A semiclassical approach to many-body interference in Fock-space

Energy Technology Data Exchange (ETDEWEB)

Engl, Thomas

2015-11-01

Many-body systems draw ever more physicists' attention. Such an increase of interest often comes along with the development of new theoretical methods. In this thesis, a non-perturbative semiclassical approach is developed, which allows to analytically study many-body interference effects both in bosonic and fermionic Fock space and is expected to be applicable to many research areas in physics ranging from Quantum Optics and Ultracold Atoms to Solid State Theory and maybe even High Energy Physics. After the derivation of the semiclassical approximation, which is valid in the limit of large total number of particles, first applications manifesting the presence of many-body interference effects are shown. Some of them are confirmed numerically thus verifying the semiclassical predictions. Among these results are coherent back-/forward-scattering in bosonic and fermionic Fock space as well as a many-body spin echo, to name only the two most important ones.

Cluster synchronization for directed community networks via pinning partial schemes

International Nuclear Information System (INIS)

Hu Cheng; Jiang Haijun

2012-01-01

Highlights: ► Cluster synchronization for directed community networks is proposed by pinning partial schemes. ► Each community is considered as a whole. ► Several novel pinning criteria are derived based on the information of communities. ► A numerical example with simulation is provided. - Abstract: In this paper, we focus on driving a class of directed networks to achieve cluster synchronization by pinning schemes. The desired cluster synchronization states are no longer decoupled orbits but a set of un-decoupled trajectories. Each community is considered as a whole and the synchronization criteria are derived based on the information of communities. Several pinning schemes including feedback control and adaptive strategy are proposed to select controlled communities by analyzing the information of each community such as indegrees and outdegrees. In all, this paper answers several challenging problems in pinning control of directed community networks: (1) What communities should be chosen as controlled candidates? (2) How many communities are needed to be controlled? (3) How large should the control gains be used in a given community network to achieve cluster synchronization? Finally, an example with numerical simulations is given to demonstrate the effectiveness of the theoretical results.

Semiclassical shell structure of moments of inertia in deformed Fermi systems

International Nuclear Information System (INIS)

Magner, A.G.; Gzhebinsky, A.M.; Sitdikov, A.S.; Khamzin, A.A.; Bartel, J.

2010-01-01

The collective moment of inertia is derived analytically within the cranking model in the adiabatic mean-field approximation at finite temperature. Using the nonperturbative periodic-orbit theory the semiclassical shell-structure components of the collective moment of inertia are obtained for any potential well. Their relation to the free-energy shell corrections are found semiclassically as being given through the shell-structure components of the rigid-body moment of inertia of the statistically equilibrium rotation in terms of short periodic orbits. Shell effects in the moment of inertia disappear exponentially with increasing temperature. For the case of the harmonic-oscillator potential one observes a perfect agreement between semiclassical and quantum shell-structure components of the free energy and the moment of inertia for several critical bifurcation deformations and several temperatures. (author)

Semiclassical propagation: Hilbert space vs. Wigner representation

Science.gov (United States)

Gottwald, Fabian; Ivanov, Sergei D.

2018-03-01

A unified viewpoint on the van Vleck and Herman-Kluk propagators in Hilbert space and their recently developed counterparts in Wigner representation is presented. Based on this viewpoint, the Wigner Herman-Kluk propagator is conceptually the most general one. Nonetheless, the respective semiclassical expressions for expectation values in terms of the density matrix and the Wigner function are mathematically proven here to coincide. The only remaining difference is a mere technical flexibility of the Wigner version in choosing the Gaussians' width for the underlying coherent states beyond minimal uncertainty. This flexibility is investigated numerically on prototypical potentials and it turns out to provide neither qualitative nor quantitative improvements. Given the aforementioned generality, utilizing the Wigner representation for semiclassical propagation thus leads to the same performance as employing the respective most-developed (Hilbert-space) methods for the density matrix.

Semiclassical quantization of the nonlinear Schrodinger equation

International Nuclear Information System (INIS)

Nohl, C.R.

1976-01-01

Using the functional integral technique of Dashen, Hasslacher, and Neveu, we perform a semiclassical quantization of the nonlinear Schrodinger equation (NLSE), which reproduces McGuire's exact result for the energy levels of the bound states of the theory. We show that the stability angle formalism leads to the one-loop normal ordering and self-energy renormalization expected from perturbation theory, and demonstrate that taking into account center-of-mass motion gives the correct nonrelativistic energy--momentum relation. We interpret the classical solution in the context of the quantum theory, relating it to the matrix element of the field operator between adjacent bound states in the limit of large quantum numbers. Finally, we quantize the NLSE as a theory of N component fermion fields and show that the semiclassical method yields the exact energy levels and correct degeneracies

Semiclassical use of action-angle variables in the presence of tunnelling

International Nuclear Information System (INIS)

Carvalho, R.E. de; Almeida, A.M.O. de

1988-01-01

Semiclassical approximations of quantum mechanics are known to be invariant with respect to classical cannonical transformations even though these are not in general isomorphic to unitary transformations in quantum mechanics. It is verified computationally that the energy eigenlevels of a resonant system computed in a harmonic oscillator basis are in good agreement with the semiclassical values obtained with the use of action-angle variables. (A.C.A.S.) [pt

Communication: importance sampling including path correlation in semiclassical initial value representation calculations for time correlation functions.

Science.gov (United States)

Pan, Feng; Tao, Guohua

2013-03-07

Full semiclassical (SC) initial value representation (IVR) for time correlation functions involves a double phase space average over a set of two phase points, each of which evolves along a classical path. Conventionally, the two initial phase points are sampled independently for all degrees of freedom (DOF) in the Monte Carlo procedure. Here, we present an efficient importance sampling scheme by including the path correlation between the two initial phase points for the bath DOF, which greatly improves the performance of the SC-IVR calculations for large molecular systems. Satisfactory convergence in the study of quantum coherence in vibrational relaxation has been achieved for a benchmark system-bath model with up to 21 DOF.

Semiclassical approximation to time-dependent Hartree--Fock theory

International Nuclear Information System (INIS)

Dworzecka, M.; Poggioli, R.

1976-01-01

Working within a time-dependent Hartree-Fock framework, one develops a semiclassical approximation appropriate for large systems. It is demonstrated that the standard semiclassical approach, the Thomas-Fermi approximation, is inconsistent with Hartree-Fock theory when the basic two-body interaction is short-ranged (as in nuclear systems, for example). However, by introducing a simple extension of the Thomas-Fermi approximation, one overcomes this problem. One also discusses the infinite nuclear matter problem and point out that time-dependent Hartree-Fock theory yields collective modes of the zero sound variety instead of ordinary hydrodynamic (first) sound. One thus emphasizes that one should be extremely circumspect when attempting to cast the equations of motion of time-dependent Hartree-Fock theory into a hydrodynamic-like form

Semiclassical theory of resonance inelastic electron-molecule collisions

International Nuclear Information System (INIS)

Kazanskij, A.K.

1986-01-01

Semiclassical approach to the theory of resonance electron-molecule collisions, unlocal with respect to interatomic distance was developed. Two problems were considered: modified adiabatic approach for sigle-pole approximation of R-matrix and Fano-Feshbach-Bardsley theory. It is shown that these problems are similar in semiclassical approximation. A simple equation system with coefficients expressed in quadratures was obtained. It enables to determine amplitudes of all processes (including dissociation adhesion, association ejection, free-free and free-bound transitions) in energetic representation with respect to nucleus vibrations in molecule with allowance for both descrete and continuous spectra of nucleus motion in molecule. Quantitative investigation of the system results to the notion of dynamic energy curve of intermediate state, generalizing the motion of such curve in boomerang theory

Qutrit squeezing via semiclassical evolution

International Nuclear Information System (INIS)

Klimov, Andrei B; Dinani, Hossein Tavakoli; Medendorp, Zachari E D; Guise, Hubert de

2011-01-01

We introduce a concept of squeezing in collective qutrit systems through a geometrical picture connected to the deformation of the isotropic fluctuations of su(3) operators when evaluated in a coherent state. This kind of squeezing can be generated by Hamiltonians nonlinear in the generators of su(3) algebra. A simplest model of such a nonlinear evolution is analyzed in terms of semiclassical evolution of the SU(3) Wigner function. (paper)

Semiclassical approach to fidelity amplitude

International Nuclear Information System (INIS)

García-Mata, Ignacio; Vallejos, Raúl O; Wisniacki, Diego A

2011-01-01

The fidelity amplitude (FA) is a quantity of paramount importance in echo-type experiments. We use semiclassical theory to study the average FA for quantum chaotic systems under external perturbation. We explain analytically two extreme cases: the random dynamics limit - attained approximately by strongly chaotic systems - and the random perturbation limit, which shows a Lyapunov decay. Numerical simulations help us to bridge the gap between both the extreme cases. (paper)

Quantum flesh on classical bones: Semiclassical bridges across the quantum-classical divide

Energy Technology Data Exchange (ETDEWEB)

Bokulich, Alisa [Center for Philosophy and History of Science, Boston University, Boston, MA (United States)

2014-07-01

Traditionally quantum mechanics is viewed as having made a sharp break from classical mechanics, and the concepts and methods of these two theories are viewed as incommensurable with one another. A closer examination of the history of quantum mechanics, however, reveals that there is a strong sense in which quantum mechanics was built on the backbone of classical mechanics. As a result, there is a considerable structural continuity between these two theories, despite their important differences. These structural continuities provide a ground for semiclassical methods in which classical structures, such as trajectories, are used to investigate and model quantum phenomena. After briefly tracing the history of semiclassical approaches, I show how current research in semiclassical mechanics is revealing new bridges across the quantum-classical divide.

Superluminal warp drives are semiclassically unstable

Energy Technology Data Exchange (ETDEWEB)

Finazzi, S; Liberati, S [SISSA, via Beirut 2-4, Trieste 34151, Italy and INFN sezione di Trieste (Italy); Barcelo, C, E-mail: finazzi@sissa.i, E-mail: liberati@sissa.i, E-mail: carlos@iaa.e [Instituto de Astrofisica de AndalucIa, CSIC, Camino Bajo de Huetor 50, 18008 Granada (Spain)

2010-04-01

Warp drives are very interesting configurations of General Relativity: they provide a way to travel at superluminal speeds, albeit at the cost of requiring exotic matter to build them. Even if one succeeded in providing the necessary exotic matter, it would still be necessary to check whether they would survive to the switching on of quantum effects. Semiclassical corrections to warp-drive geometries created out of an initially flat spacetime have been analyzed in a previous work by the present authors in special locations, close to the wall of the bubble and in its center. Here, we present an exact numerical analysis of the renormalized stress-energy tensor (RSET) in the whole bubble. We find that the the RSET will exponentially grow in time close to the front wall of the superluminal bubble, after some transient terms have disappeared, hence strongly supporting our previous conclusion that the warp-drive geometries are unstable against semiclassical back-reaction. This result seems to implement the chronology protection conjecture, forbiddig the set up of a structure potentially dangerous for causality.

Recent developments in semiclassical mechanics: eigenvalues and reaction rate constants

International Nuclear Information System (INIS)

Miller, W.H.

1976-04-01

A semiclassical treatment of eigenvalues for a multidimensional non-separable potential function and of the rate constant for a chemical reaction with an activation barrier is presented. Both phenomena are seen to be described by essentially the same semiclassical formalism, which is based on a construction of the total Hamiltonian in terms of the complete set of ''good'' action variables (or adiabatic invariants) associated with the minimum in the potential energy surface for the eigenvalue case, or the saddle point in the potential energy surface for the case of chemical reaction

Wave packets, Maslov indices, and semiclassical quantization

International Nuclear Information System (INIS)

Littlejohn, R.G.

1989-01-01

The Bohr-Sommerfeld quantization condition, as refined by Keller and Maslov, reads I=(n+m/4)h, where I is the classical action, n is the quantum number, and where m is the Maslov index, an even integer. The occurrence of the integers n and m in this formula is a reflection of underlying topological features of semiclassical quantization. In particular, the work of Arnold and others has shown that m/2 is a winding number of closed curves on the classical symplectic group manifold, Sp(2N). Wave packets provide a simple and elegant means of establishing the connection between semiclassical quantization and the homotopy classes of Sp(2N), as well as a practical way of calculating Maslov indices in complex problems. Topological methods can also be used to derive general formulas for the Maslov indices of invariant tori in the classical phase space corresponding to resonant motion. (orig.)

Photo double-ionization of helium: a new approach combining R matrix and semiclassical techniques in an hyperspherical framework

International Nuclear Information System (INIS)

Malegat, L.; Kazansky, A.; Selles, P.

1999-01-01

We introduce a new method for computing photo double ionization (PDI) cross sections for two electron atoms. It is formulated in terms of the hyperspherical radius R and relies upon a combination of R matrix techniques in the inner region R≤R 0 with a semiclassical approximation for the R motion in the outer region. We present a first application of this method to the PDI of He within a model of reduced dimensionality where r 1 =r 2 . It demonstrates the validity of our numerical scheme and provides a first quantitative estimate of the energy domain of validity of the Wannier mechanism. (orig.)

Decoupling Revenue from Energy Sales

International Nuclear Information System (INIS)

Potocnik, V.

2011-01-01

Energy sector based on the fossil fuels combustion has the largest greenhouse gases emissions, causing the actual climate change with numerous negative impacts. Therefore, different measures for the climate change mitigation are performed, mostly by increasing ENEF-energy efficiency (saving), and by substituting fossil fuels with renewable energy (RE), mainly with limited results. One of the most serious obstacles for implementation of these measures is an opposition of the energy utilities (power and natural gas), whose energy sales, revenue and profit are thus reduced. Consequently, new solutions are asked to decouple utilities revenues from energy sales. Decoupling has started in the US, where most states have at least one utility with some decoupling experience. California has pioneering role since 1982., with impressive results. (author)

Semiclassical description of hot nuclear systems

International Nuclear Information System (INIS)

Brack, M.

1984-01-01

We present semiclassical density variational calculations for highly excited nuclear systems. We employ the newly derived functionals tau[rho] and sigma[rho] of the extended Thomas-Fermi (ETF) model, generalized to finite temperatures. Excellent agreement is reached with Hartree-Fock (HF) results. We also calculated the fission barrier of 240 Pu as a function of the nuclear temperature

Semiclassical soliton ensembles for the focusing nonlinear Schrödinger equation

CERN Document Server

Kamvissis, Spyridon; Miller, Peter D

2003-01-01

This book represents the first asymptotic analysis, via completely integrable techniques, of the initial value problem for the focusing nonlinear Schrödinger equation in the semiclassical asymptotic regime. This problem is a key model in nonlinear optical physics and has increasingly important applications in the telecommunications industry. The authors exploit complete integrability to establish pointwise asymptotics for this problem's solution in the semiclassical regime and explicit integration for the underlying nonlinear, elliptic, partial differential equations suspected of governing

Lasing in nanowires: Ab initio semiclassical model

DEFF Research Database (Denmark)

Bordo, Vladimir

2013-01-01

The semiclassical equations which describe lasing in nanowires are derived from first principles. Both the lasing threshold condition and the steady-state regime of operation are discussed. It is shown that the lasing is governed by the Fourier coefficients of the field susceptibility averaged ov...

Disturbance Decoupling of Switched Linear Systems

NARCIS (Netherlands)

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

2010-01-01

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

Decoupling, situated cognition and immersion in art.

Science.gov (United States)

Reboul, Anne

2015-09-01

Situated cognition seems incompatible with strong decoupling, where representations are deployed in the absence of their targets and are not oriented toward physical action. Yet, in art consumption, the epitome of a strongly decoupled cognitive process, the artwork is a physical part of the environment and partly controls the perception of its target by the audience, leading to immersion. Hence, art consumption combines strong decoupling with situated cognition.

Semiclassical force for electroweak baryogenesis three-dimensional derivation

CERN Document Server

Kainulainen, K; Schmidt, M G; Weinstock, S; Kainulainen, Kimmo; Prokopec, Tomislav; Schmidt, Michael G.; Weinstock, Steffen

2002-01-01

We derive a semiclassical transport equation for fermions propagating in the presence of a CP-violating planar bubble wall at a first order electroweak phase transition. Starting from the Kadanoff-Baym (KB) equation for the two-point (Wightman) function we perform an expansion in gradients, or equivalently in the Planck constant h-bar. We show that to first order in h-bar the KB equations have a spectral solution, which allows for an on-shell description of the plasma excitations. The CP-violating force acting on these excitations is found to be enhanced by a boost factor in comparison with the 1+1-dimensional case studied in a former paper. We find that an identical semiclassical force can be obtained by the WKB method. Applications to the MSSM are also mentioned.

Semiclassics for matrix Hamiltonians: The Gutzwiller trace formula with applications to graphene-type systems

Science.gov (United States)

Vogl, M.; Pankratov, O.; Shallcross, S.

2017-07-01

We present a tractable and physically transparent semiclassical theory of matrix-valued Hamiltonians, i.e., those that describe quantum systems with internal degrees of freedoms, based on a generalization of the Gutzwiller trace formula for a n ×n dimensional Hamiltonian H (p ̂,q ̂) . The classical dynamics is governed by n Hamilton-Jacobi (HJ) equations that act in a phase space endowed with a classical Berry curvature encoding anholonomy in the parallel transport of the eigenvectors of H (p ,q ) ; these vectors describe the internal structure of the semiclassical particles. At the O (ℏ1) level and for nondegenerate HJ systems, this curvature results in an additional semiclassical phase composed of (i) a Berry phase and (ii) a dynamical phase resulting from the classical particles "moving through the Berry curvature". We show that the dynamical part of this semiclassical phase will, generally, be zero only for the case in which the Berry phase is topological (i.e., depends only on the winding number). We illustrate the method by calculating the Landau spectrum for monolayer graphene, the four-band model of AB bilayer graphene, and for a more complicated matrix Hamiltonian describing the silicene band structure. Finally, we apply our method to an inhomogeneous system consisting of a strain engineered one-dimensional moiré in bilayer graphene, finding localized states near the Dirac point that arise from electron trapping in a semiclassical moiré potential. The semiclassical density of states of these localized states we show to be in perfect agreement with an exact quantum mechanical calculation of the density of states.

Semiclassical relations and IR effects in de Sitter and slow-roll space-times

DEFF Research Database (Denmark)

B. Giddings, Steven; Sloth, Martin Snoager

2010-01-01

We calculate IR divergent graviton one-loop corrections to scalar correlators in de Sitter space, and show that the leading IR contribution may be reproduced via simple semiclassical consistency relations. One can likewise use such semiclassical relations to calculate leading IR corrections to co...... with a sharp perturbative calculation of "missing information" in Hawking radiation....

Uniform semiclassical approximation for absorptive scattering systems

International Nuclear Information System (INIS)

Hussein, M.S.; Pato, M.P.

1987-07-01

The uniform semiclassical approximation of the elastic scattering amplitude is generalized to absorptive systems. An integral equation is derived which connects the absorption modified amplitude to the absorption free one. Division of the amplitude into a diffractive and refractive components is then made possible. (Author) [pt

A new approach to the semi-classical relativistic two-body problem for charged fermions

International Nuclear Information System (INIS)

Leiter, D.

1978-01-01

Generalizing from a recently developed hybrid formulation of classical electrodynamics with ''direct (charge-field) action'' structure an analogous semi-classical Dirac formulation of the theory is constructed, which is capable of describing the semi-classical quantum mechanics of two identical spin-1/2 particles. This semi-classical formulation is to be used as a heuristic aid in searching for the theoretical structure of a fully ''second quantized'' theory. The Pauli exclusion principle is incorporated by making the interaction fields (in the action principle) antisymmetric with respect to ''charge-field'' labeling. In this manner, ''position correlation'' effects associated with ''configuration interaction'' can also be accounted for. By studying the nature of the stationary-state solutions, the formalism is compared with the conventional quantum-mechanical one (to understand the similarities and the differences between this approach and the usual correlated Hartree-Fock approximation of ordinary relativistic quantum theory). The stationary-state solutions to the semi-classical formalism are shown to closely approximate the usual quantum-mechanical solutions when the wave functions are represented as a superposition of Slater determinants of Dirac-Coulombic-type wave functions with radial parts having a form which extremizes the total Breit energy. The manner in which this semi-classical theory might be extended to a fully ''second quantized'' formalism is sketched. (author)

Geometrical method of decoupling

Directory of Open Access Journals (Sweden)

C. Baumgarten

2012-12-01

Full Text Available The computation of tunes and matched beam distributions are essential steps in the analysis of circular accelerators. If certain symmetries—like midplane symmetry—are present, then it is possible to treat the betatron motion in the horizontal, the vertical plane, and (under certain circumstances the longitudinal motion separately using the well-known Courant-Snyder theory, or to apply transformations that have been described previously as, for instance, the method of Teng and Edwards. In a preceding paper, it has been shown that this method requires a modification for the treatment of isochronous cyclotrons with non-negligible space charge forces. Unfortunately, the modification was numerically not as stable as desired and it was still unclear, if the extension would work for all conceivable cases. Hence, a systematic derivation of a more general treatment seemed advisable. In a second paper, the author suggested the use of real Dirac matrices as basic tools for coupled linear optics and gave a straightforward recipe to decouple positive definite Hamiltonians with imaginary eigenvalues. In this article this method is generalized and simplified in order to formulate a straightforward method to decouple Hamiltonian matrices with eigenvalues on the real and the imaginary axis. The decoupling of symplectic matrices which are exponentials of such Hamiltonian matrices can be deduced from this in a few steps. It is shown that this algebraic decoupling is closely related to a geometric “decoupling” by the orthogonalization of the vectors E[over →], B[over →], and P[over →], which were introduced with the so-called “electromechanical equivalence.” A mathematical analysis of the problem can be traced down to the task of finding a structure-preserving block diagonalization of symplectic or Hamiltonian matrices. Structure preservation means in this context that the (sequence of transformations must be symplectic and hence canonical. When

Semiclassical methods in curved spacetime and black hole thermodynamics

International Nuclear Information System (INIS)

Camblong, Horacio E.; Ordonez, Carlos R.

2005-01-01

Improved semiclassical techniques are developed and applied to a treatment of a real scalar field in a D-dimensional gravitational background. This analysis, leading to a derivation of the thermodynamics of black holes, is based on the simultaneous use of (i) a near-horizon description of the scalar field in terms of conformal quantum mechanics; (ii) a novel generalized WKB framework; and (iii) curved-spacetime phase-space methods. In addition, this improved semiclassical approach is shown to be asymptotically exact in the presence of hierarchical expansions of a near-horizon type. Most importantly, this analysis further supports the claim that the thermodynamics of black holes is induced by their near-horizon conformal invariance

Semiclassical approximations for gravity and the issue of backreaction

International Nuclear Information System (INIS)

Padmanabhan, T.

1989-01-01

Semiclassical approximations, which are useful in the study of a quantum system interacting with a classical system, are studied and compared. In particular, we consider the Born-Oppenheimer approximation (BOA) (corresponding to G → O at fixed ℎ), the effective action approach (ℎ → O at fixed G) and their combinations. We show that in the strict BOA limit there is no backreaction on gravity. In the effective action approach one can obtain a semi-classical description of gravity, if certain stringent requirements are satisfied. In most situations of interest these conditions will not be met and the O(ℎ) contribution from gravitons will be comparable to that from quantum fields. (author)

Symplectic and semiclassical aspects of the Schläfli identity

Science.gov (United States)

Hedeman, Austin; Kur, Eugene; Littlejohn, Robert G.; Haggard, Hal M.

2015-03-01

The Schläfli identity, which is important in Regge calculus and loop quantum gravity, is examined from a symplectic and semiclassical standpoint in the special case of flat, three-dimensional space. In this case a proof is given, based on symplectic geometry. A series of symplectic and Lagrangian manifolds related to the Schläfli identity, including several versions of a Lagrangian manifold of tetrahedra, are discussed. Semiclassical interpretations of the various steps are provided. Possible generalizations to three-dimensional spaces of constant (nonzero) curvature, involving Poisson-Lie groups and q-deformed spin networks, are discussed.

A decoupled power flow algorithm using particle swarm optimization technique

International Nuclear Information System (INIS)

Acharjee, P.; Goswami, S.K.

2009-01-01

A robust, nondivergent power flow method has been developed using the particle swarm optimization (PSO) technique. The decoupling properties between the power system quantities have been exploited in developing the power flow algorithm. The speed of the power flow algorithm has been improved using a simple perturbation technique. The basic power flow algorithm and the improvement scheme have been designed to retain the simplicity of the evolutionary approach. The power flow is rugged, can determine the critical loading conditions and also can handle the flexible alternating current transmission system (FACTS) devices efficiently. Test results on standard test systems show that the proposed method can find the solution when the standard power flows fail.

Semi-classical limit of relativistic quantum mechanics

Indian Academy of Sciences (India)

It is shown that the semi-classical limit of solutions to the Klein–Gordon equation gives the particle probability density that is in direct proportion to the inverse of the particle velocity. It is also shown that in the case of the Dirac equation a different result is obtained.

Semiclassical universe from first principles

International Nuclear Information System (INIS)

Ambjorn, J.; Jurkiewicz, J.; Loll, R.

2005-01-01

Causal dynamical triangulations in four dimensions provide a background-independent definition of the sum over space-time geometries in non-perturbative quantum gravity. We show that the macroscopic four-dimensional world which emerges in the Euclidean sector of this theory is a bounce which satisfies a semiclassical equation. After integrating out all degrees of freedom except for a global scale factor, we obtain the ground state wave function of the universe as a function of this scale factor

Strong-coupling constant at three loops in momentum subtraction scheme

International Nuclear Information System (INIS)

Chetyrkin, K.G.; Russian Academy of Sciences, Moscow; Kniehl, B.A.; Steinhauser, M.

2008-12-01

In this paper we compute the three-loop corrections to the β function in a momentum subtraction (MOM) scheme with a massive quark. The calculation is performed in the background field formalism applying asymptotic expansions for small and large momenta. Special emphasis is devoted to the relation between the coupling constant in the MOM and MS schemes as well as their ability to describe the phenomenon of decoupling. It is demonstrated by an explicit comparison that the MS scheme can be consistently used to relate the values of the MOM-scheme strong-coupling constant in the energy regions higher and lower than the massive-quark production threshold. This procedure obviates the necessity to know the full mass dependence of the MOM β function and clearly demonstrates the equivalence of both schemes for the description of physics outside the threshold region. (orig.)

Strong-coupling constant at three loops in momentum subtraction scheme

Energy Technology Data Exchange (ETDEWEB)

Chetyrkin, K.G. [Karlsruhe Univ. (T.H.), Karlsruhe Inst. of Technology (KIT) (Germany). Inst. fuer Theoretische Teilchenphysik]|[Russian Academy of Sciences, Moscow (Russian Federation). Inst. for Nuclear Research; Kniehl, B.A. [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik; Steinhauser, M. [Karlsruhe Univ. (T.H.), Karlsruhe Inst. of Technology (KIT) (Germany). Inst. fuer Theoretische Teilchenphysik

2008-12-15

In this paper we compute the three-loop corrections to the {beta} function in a momentum subtraction (MOM) scheme with a massive quark. The calculation is performed in the background field formalism applying asymptotic expansions for small and large momenta. Special emphasis is devoted to the relation between the coupling constant in the MOM and MS schemes as well as their ability to describe the phenomenon of decoupling. It is demonstrated by an explicit comparison that the MS scheme can be consistently used to relate the values of the MOM-scheme strong-coupling constant in the energy regions higher and lower than the massive-quark production threshold. This procedure obviates the necessity to know the full mass dependence of the MOM {beta} function and clearly demonstrates the equivalence of both schemes for the description of physics outside the threshold region. (orig.)

Foundation of the semiclassical approximation by means of path integral methods

International Nuclear Information System (INIS)

Krisztinkovics, F.

1984-01-01

The aim of our study is to find a technically unique semiclassical treatment to describe the collision processes between heavy ions. Thereby it shall be started from a complete quantum mechanical formulation of the collision process. This aim requires: 1. A completely quantum mechanical initial formulation for the whole system, 2. a unique and conceptually clear transition to semiclassics. In order to fulfil the requirements a method is offered which is in closest connection with the Feynman propagator respectively influence functional. (orig./HSI) [de

Hydrogen atom in a magnetic field: Ghost orbits, catastrophes, and uniform semiclassical approximations

International Nuclear Information System (INIS)

Main, J.; Wunner, G.

1997-01-01

Applying closed-orbit theory to the recurrence spectra of the hydrogen atom in a magnetic field, one can interpret most, but not all, structures semiclassically in terms of closed classical orbits. In particular, conventional closed-orbit theory fails near bifurcations of orbits where semiclassical amplitudes exhibit unphysical divergences. Here we analyze the role of ghost orbits living in complex phase space. The ghosts can explain resonance structures in the spectra of the hydrogen atom in a magnetic field at positions where no real orbits exist. For three different types of catastrophes, viz. fold, cusp, and butterfly catastrophes, we construct uniform semiclassical approximations and demonstrate that these solutions are completely determined by classical parameters of the real orbits and complex ghosts. copyright 1997 The American Physical Society

Modified method of perturbed stationary states. II. Semiclassical and low-velocity quantal approximations

International Nuclear Information System (INIS)

Green, T.A.

1978-10-01

For one-electron heteropolar systems, the wave-theoretic Lagrangian of Paper I 2 is simplified in two distinct approximations. The first is semiclassical; the second is quantal, for velocities below those for which the semiclassical treatment is reliable. For each approximation, unitarity and detailed balancing are discussed. Then, the variational method as described by Demkov is used to determine the coupled equations for the radial functions and the Euler-Lagrange equations for the translational factors which are part of the theory. Specific semiclassical formulae for the translational factors are given in a many-state approximation. Low-velocity quantal formulae are obtained in a one-state approximation. The one-state results of both approximations agree with an earlier determination by Riley. 14 references

A generalized theoretical framework for the description of spin decoupling in solid-state MAS NMR: Offset effect on decoupling performance

Energy Technology Data Exchange (ETDEWEB)

Tan, Kong Ooi; Meier, Beat H., E-mail: beme@ethz.ch, E-mail: maer@ethz.ch; Ernst, Matthias, E-mail: beme@ethz.ch, E-mail: maer@ethz.ch [Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich (Switzerland); Agarwal, Vipin [Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich (Switzerland); TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsinghi, Hyderabad 500 075 (India)

2016-09-07

We present a generalized theoretical framework that allows the approximate but rapid analysis of residual couplings of arbitrary decoupling sequences in solid-state NMR under magic-angle spinning conditions. It is a generalization of the tri-modal Floquet analysis of TPPM decoupling [Scholz et al., J. Chem. Phys. 130, 114510 (2009)] where three characteristic frequencies are used to describe the pulse sequence. Such an approach can be used to describe arbitrary periodic decoupling sequences that differ only in the magnitude of the Fourier coefficients of the interaction-frame transformation. It allows a ∼100 times faster calculation of second-order residual couplings as a function of pulse sequence parameters than full spin-dynamics simulations. By comparing the theoretical calculations with full numerical simulations, we show the potential of the new approach to examine the performance of decoupling sequences. We exemplify the usefulness of this framework by analyzing the performance of commonly used high-power decoupling sequences and low-power decoupling sequences such as amplitude-modulated XiX (AM-XiX) and its super-cycled variant SC-AM-XiX. In addition, the effect of chemical-shift offset is examined for both high- and low-power decoupling sequences. The results show that the cross-terms between the dipolar couplings are the main contributions to the line broadening when offset is present. We also show that the SC-AM-XIX shows a better offset compensation.

A generalized theoretical framework for the description of spin decoupling in solid-state MAS NMR: Offset effect on decoupling performance.

Science.gov (United States)

Tan, Kong Ooi; Agarwal, Vipin; Meier, Beat H; Ernst, Matthias

2016-09-07

We present a generalized theoretical framework that allows the approximate but rapid analysis of residual couplings of arbitrary decoupling sequences in solid-state NMR under magic-angle spinning conditions. It is a generalization of the tri-modal Floquet analysis of TPPM decoupling [Scholz et al., J. Chem. Phys. 130, 114510 (2009)] where three characteristic frequencies are used to describe the pulse sequence. Such an approach can be used to describe arbitrary periodic decoupling sequences that differ only in the magnitude of the Fourier coefficients of the interaction-frame transformation. It allows a ∼100 times faster calculation of second-order residual couplings as a function of pulse sequence parameters than full spin-dynamics simulations. By comparing the theoretical calculations with full numerical simulations, we show the potential of the new approach to examine the performance of decoupling sequences. We exemplify the usefulness of this framework by analyzing the performance of commonly used high-power decoupling sequences and low-power decoupling sequences such as amplitude-modulated XiX (AM-XiX) and its super-cycled variant SC-AM-XiX. In addition, the effect of chemical-shift offset is examined for both high- and low-power decoupling sequences. The results show that the cross-terms between the dipolar couplings are the main contributions to the line broadening when offset is present. We also show that the SC-AM-XIX shows a better offset compensation.

Semiclassical scattering theory

International Nuclear Information System (INIS)

Di Salvo, A.

1985-01-01

It is intended to write the semiclassical scattering amplitude as a sum of terms, each of them being associated to trajectory. First of all the classical equations of motion are studied, considering both the analytical (real and complex) solutions and a certain type of singular solutions, which behave similary to the difracted rays in optics; in particular, in the case of a central nuclear potential, classical effects like rainbow and orbiting and also wave effects like diffraction and direct reflection are singled out. Successively, considering the Debye expansion of the scattering amplitude relative to a central nuclear potential, and evaluating asymptotically each term by means of the saddle point technique, the decay exponents and difraction coefficients relative to such a potential are determined

Nonlinear dynamics of semiclassical coherent states in periodic potentials

International Nuclear Information System (INIS)

Carles, Rémi; Sparber, Christof

2012-01-01

We consider nonlinear Schrödinger equations with either local or nonlocal nonlinearities. In addition, we include periodic potentials as used, for example, in matter wave experiments in optical lattices. By considering the corresponding semiclassical scaling regime, we construct asymptotic solutions, which are concentrated both in space and in frequency around the effective semiclassical phase-space flow induced by Bloch’s spectral problem. The dynamics of these generalized coherent states is governed by a nonlinear Schrödinger model with effective mass. In the case of nonlocal nonlinearities, we establish a novel averaging-type result in the critical case. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Coherent states: mathematical and physical aspects’. (paper)

A semiclassical treatment of correlation energy for nuclear systems

International Nuclear Information System (INIS)

Nielsen, M.

1988-01-01

Starting with the separation of the many-body density operator in two parts, one describing the one-body aspects of the full density and the other containing all dynamic correlations information, the semiclassical approximation for the system correlation energy, was calculated. It is showm that, in this case, the Gaussian Wave Packets Phase Space Representation is more convenient than the Wely-Wigner Rrepresentation for the analysis of the semiclassical correlation energy. Using a phenomenological interaction, the correlation energy to the nuclear matter and some simmetric finite nucleus was calculated. The Fermi Surface Diffusivity, was also calculated. Finally, from the relation between this theory and the pertubation theory, we have done some considerations about the viability on the local densities expansion for energy functionals. (author) [pt

A self-consistent semiclassical sum rule approach to the average properties of giant resonances

International Nuclear Information System (INIS)

Li Guoqiang; Xu Gongou

1990-01-01

The average energies of isovector giant resonances and the widths of isoscalar giant resonances are evaluated with the help of a self-consistent semiclassical Sum rule approach. The comparison of the present results with the experimental ones justifies the self-consistent semiclassical sum rule approach to the average properties of giant resonances

Semiclassical description of soliton-antisoliton pair production in particle collisions

Energy Technology Data Exchange (ETDEWEB)

Demidov, S.V.; Levkov, D.G. [Institute for Nuclear Research of the Russian Academy of Sciences,60th October Anniversary prospect 7a, Moscow 117312 (Russian Federation)

2015-11-10

We develop a consistent semiclassical method to calculate the probability of topological soliton-antisoliton pair production in collisions of elementary particles. In our method one adds an auxiliary external field pulling the soliton and antisoliton in the opposite directions. This transforms the original scattering process into a Schwinger pair creation of the solitons induced by the particle collision. One describes the Schwinger process semiclassically and recovers the original scattering probability in the limit of vanishing external field. We illustrate the method in (1+1)-dimensional scalar field model where the suppression exponents of soliton-antisoliton production in the multiparticle and two-particle collisions are computed numerically.

Chaos in the Dicke model: quantum and semiclassical analysis

International Nuclear Information System (INIS)

Bastarrachea-Magnani, Miguel Angel; Hirsch, Jorge G; López-del-Carpio, Baldemar; Lerma-Hernández, Sergio

2015-01-01

The emergence of chaos in an atom-field system is studied employing both semiclassical and numerical quantum techniques, taking advantage of the algebraic character of the Hamiltonian. A semiclassical Hamiltonian is obtained by considering the expectation value of the quantum Hamiltonian in Glauber (for the field) and Bloch (for the atoms) coherent states. Regular and chaotic regions are identified by looking at the Poincaré sections for different energies and parameter values. An analytical expression for the semiclassical energy density of states is obtained by integrating the available phase space, which provides an exact unfolding to extract the fluctuations in the level statistics. Quantum chaos is recognized in these fluctuations, as a function of the coupling strength, for different regions in the energy spectrum, evaluating the Anderson–Darling (A–D) parameter, which distinguishes the Wigner- or Poisson-like distributions. Peres lattices play a role similar to the Poincaré section for quantum states. They are calculated employing efficient numerical solutions and are a powerful visual tool to identify individual states belonging to a regular or chaotic region, classified by utilizing the Poincaré sections and the A–D parameter. Finally, the quantum Husimi function for selected excited states is shown to have a noticeable similitude with the Poincaré sections at the same energy. (invited comment)

Interior design of a two-dimensional semiclassical black hole: Quantum transition across the singularity

International Nuclear Information System (INIS)

Levanony, Dana; Ori, Amos

2010-01-01

We study the internal structure of a two-dimensional dilatonic evaporating black hole based on the Callan, Giddings, Harvey, and Strominger model. At the semiclassical level, a (weak) spacelike singularity was previously found to develop inside the black hole. We employ here a simplified quantum formulation of spacetime dynamics in the neighborhood of this singularity, using a minisuperspace-like approach. Quantum evolution is found to be regular and well defined at the semiclassical singularity. A well-localized initial wave packet propagating towards the singularity bounces off the latter and retains its well-localized form. Our simplified quantum treatment thus suggests that spacetime may extend semiclassically beyond the singularity, and also signifies the specific extension.

Interior design of a two-dimensional semiclassical black hole: Quantum transition across the singularity

Science.gov (United States)

Levanony, Dana; Ori, Amos

2010-05-01

We study the internal structure of a two-dimensional dilatonic evaporating black hole based on the Callan, Giddings, Harvey, and Strominger model. At the semiclassical level, a (weak) spacelike singularity was previously found to develop inside the black hole. We employ here a simplified quantum formulation of spacetime dynamics in the neighborhood of this singularity, using a minisuperspace-like approach. Quantum evolution is found to be regular and well defined at the semiclassical singularity. A well-localized initial wave packet propagating towards the singularity bounces off the latter and retains its well-localized form. Our simplified quantum treatment thus suggests that spacetime may extend semiclassically beyond the singularity, and also signifies the specific extension.

Comparative study of quantal and semiclassical treatments of charge transfer between O+ and He

Science.gov (United States)

Zhao, L. B.; Joseph, D. C.; Saha, B. C.; Liebermann, H. P.; Funke, P.; Buenker, R. J.

2009-03-01

A comparative study for the electron capture process O+(S40,D20,P20)+He→O(P3)+He+ is reported. The cross sections are calculated using fully quantal and semiclassical molecular-orbital close-coupling (MOCC) approaches in the adiabatic representation. Detailed comparison of transition probabilities and cross sections is made from both MOCC approaches and displays close agreement above ˜125eV/u . The remarkable discrepancies between the earlier semiclassical and quantal MOCC approaches may be attributed to the insufficient step-size resolution in their semiclassical calculation [M. Kimura , Phys. Rev. A 50, 4854 (1994)]. Our results have also been compared with experiment and found to be in good agreement.

Instanton and noninstanton tunneling in periodically perturbed barriers: semiclassical and quantum interpretations.

Science.gov (United States)

Takahashi, Kin'ya; Ikeda, Kensuke S

2012-11-01

In multidimensional barrier tunneling, there exist two different types of tunneling mechanisms, instanton-type tunneling and noninstanton tunneling. In this paper we investigate transitions between the two tunneling mechanisms from the semiclassical and quantum viewpoints taking two simple models: a periodically perturbed Eckart barrier for the semiclassical analysis and a periodically perturbed rectangular barrier for the quantum analysis. As a result, similar transitions are observed with change of the perturbation frequency ω for both systems, and we obtain a comprehensive scenario from both semiclassical and quantum viewpoints for them. In the middle range of ω, in which the plateau spectrum is observed, noninstanton tunneling dominates the tunneling process, and the tunneling amplitude takes the maximum value. Noninstanton tunneling explained by stable-unstable manifold guided tunneling (SUMGT) from the semiclassical viewpoint is interpreted as multiphoton-assisted tunneling from the quantum viewpoint. However, in the limit ω→0, instanton-type tunneling takes the place of noninstanton tunneling, and the tunneling amplitude converges on a constant value depending on the perturbation strength. The spectrum localized around the input energy is observed, and there is a scaling law with respect to the width of the spectrum envelope, i.e., the width ∝ℏω. In the limit ω→∞, the tunneling amplitude converges on that of the unperturbed system, i.e., the instanton of the unperturbed system.

Semiclassical initial value approximation for Green's function.

Science.gov (United States)

Kay, Kenneth G

2010-06-28

A semiclassical initial value approximation is obtained for the energy-dependent Green's function. For a system with f degrees of freedom the Green's function expression has the form of a (2f-1)-dimensional integral over points on the energy surface and an integral over time along classical trajectories initiated from these points. This approximation is derived by requiring an integral ansatz for Green's function to reduce to Gutzwiller's semiclassical formula when the integrations are performed by the stationary phase method. A simpler approximation is also derived involving only an (f-1)-dimensional integral over momentum variables on a Poincare surface and an integral over time. The relationship between the present expressions and an earlier initial value approximation for energy eigenfunctions is explored. Numerical tests for two-dimensional systems indicate that good accuracy can be obtained from the initial value Green's function for calculations of autocorrelation spectra and time-independent wave functions. The relative advantages of initial value approximations for the energy-dependent Green's function and the time-dependent propagator are discussed.

Is Decoupling GDP Growth from Environmental Impact Possible?

Science.gov (United States)

Ward, James D; Sutton, Paul C; Werner, Adrian D; Costanza, Robert; Mohr, Steve H; Simmons, Craig T

2016-01-01

The argument that human society can decouple economic growth-defined as growth in Gross Domestic Product (GDP)-from growth in environmental impacts is appealing. If such decoupling is possible, it means that GDP growth is a sustainable societal goal. Here we show that the decoupling concept can be interpreted using an easily understood model of economic growth and environmental impact. The simple model is compared to historical data and modelled projections to demonstrate that growth in GDP ultimately cannot be decoupled from growth in material and energy use. It is therefore misleading to develop growth-oriented policy around the expectation that decoupling is possible. We also note that GDP is increasingly seen as a poor proxy for societal wellbeing. GDP growth is therefore a questionable societal goal. Society can sustainably improve wellbeing, including the wellbeing of its natural assets, but only by discarding GDP growth as the goal in favor of more comprehensive measures of societal wellbeing.

Semiclassical treatment of nuclear effects in Coulomb excitation

Energy Technology Data Exchange (ETDEWEB)

Canto, L F; Donangelo, R [Universidade Federal do Rio de Janeiro, RJ (Brazil). Inst. de Fisica; Rasmussen, J O; Ring, P; Stoyer, M A [Lawrence Berkeley Lab., CA (USA). Nuclear Science Div.

1990-09-27

We introduce the effects of the nuclear potential in the semiclassical Alder-Winther-de Boer method, both in the coupling matrix elements and as corrections to the Rutherford orbit. We compare our results to those of pure Coulomb excitation and to coupled-channel calculations. (orig.).

Kinematically Decoupled Cores in Dwarf (Elliptical) Galaxies

NARCIS (Netherlands)

Toloba, E.; Peletier, R. F.; Guhathakurta, P.; van de Ven, G.; Boissier, S.; Boselli, A.; Brok, M. d.; Falcón-Barroso, J.; Hensler, G.; Janz, J.; Laurikainen, E.; Lisker, T.; Paudel, S.; Ryś, A.; Salo, H.

An overview is given of what we know about the frequency of kinematically decoupled cores in dwarf elliptical galaxies. New observations show that kinematically decoupled cores happen just as often in dwarf elliptical as in ordinary early-type galaxies. This has important consequences for the

Resolution of potential ambiguities through farside angular structure: Semiclassical analysis

International Nuclear Information System (INIS)

Fricke, S.H.; Brandan, M.E.; McVoy, K.W.

1988-01-01

The optical potential fits summarized in the preceding paper are subjected to a semiclassical analysis of the Ford-Wheeler--Knoll-Schaeffer type. The important broad dips in their farside cross sections, which are essential in greatly reducing potential ambiguities, are found (in partial agreement with a suggestion of Goldberg's) to be mainly weak ''Airy'' or rainbow minima, that serve to identify deeply penetrating trajectories. The semiclassical analysis also permits the identification and understanding of a new category of discrete and continuous potential ambiguities, and suggests the manner in which specific features of the angular distributions (such as spacings and depths of various angular minima) determine the Woods-Saxon parameters found by a chi-squared search

Classical properties and semiclassical quantization of a spherical nuclear potential

International Nuclear Information System (INIS)

Carbonell, J.; Brut, F.; Arvieu, R.; Touchard, J.

1984-03-01

The geometrical properties of the classical energy-action surface are studied for a nuclear Woods-Saxon-like spherical potential, in connection with the E.B.K. semiclassical method of quantization. Comparisons are made with other well known cases: the spherical harmonic oscillator and the spherical billiard. The shift of single particle energies from A = 208 to A = 16 is calculated by a simple method inspired by the Erhenfest adiabatic invariants. Semiclassical results are then compared with exact Schroedinger energies. It is seen that the most significant features of the single particle spectrum are explained by local properties of the energy action surface (curvature, slope) and by their evolution with the particle number

Newtonian semiclassical gravity in the Ghirardi–Rimini–Weber theory with matter density ontology

International Nuclear Information System (INIS)

Derakhshani, Maaneli

2014-01-01

We propose a Newtonian semiclassical gravity theory based on the GRW collapse theory with matter density ontology (GRWm), which we term GRWmN. The theory is proposed because, as we show from previous arguments in the literature, the standard Newtonian semiclassical gravity theory based on the Schroedinger–Newton equations does not have a consistent Born rule probability interpretation for gravitationally self-interacting particles and implies gravitational cat states for macroscopic mass superpositions. By contrast, we show that GRWmN has a consistent statistical description of gravitationally self-interacting particles and adequately suppresses the cat states for macroscopic superpositions. Two possible routes to experimentally testing GRWmN are also considered. We conclude with a discussion of possible variants of GRWmN, what a general relativistic extension would involve, and various objections that might be raised against semiclassical gravity theories like GRWmN.

Newtonian semiclassical gravity in the Ghirardi–Rimini–Weber theory with matter density ontology

Energy Technology Data Exchange (ETDEWEB)

Derakhshani, Maaneli, E-mail: maanelid@yahoo.com

2014-03-01

We propose a Newtonian semiclassical gravity theory based on the GRW collapse theory with matter density ontology (GRWm), which we term GRWmN. The theory is proposed because, as we show from previous arguments in the literature, the standard Newtonian semiclassical gravity theory based on the Schroedinger–Newton equations does not have a consistent Born rule probability interpretation for gravitationally self-interacting particles and implies gravitational cat states for macroscopic mass superpositions. By contrast, we show that GRWmN has a consistent statistical description of gravitationally self-interacting particles and adequately suppresses the cat states for macroscopic superpositions. Two possible routes to experimentally testing GRWmN are also considered. We conclude with a discussion of possible variants of GRWmN, what a general relativistic extension would involve, and various objections that might be raised against semiclassical gravity theories like GRWmN.

Quantum versus semiclassical description of selftrapping: anharmonic effects

International Nuclear Information System (INIS)

Raghavan, S.; Bishop, A.R.; Kenkre, V.M.

1998-09-01

Selftrapping has been traditionally studied on the assumption that quasiparticles interact with harmonic phonons and that this interaction is linear in the displacement of the phonon. To complement recent semiclassical studies of anharmonicity and nonlinearity in this context, we present below a fully quantum mechanical analysis of a two-site system, where the oscillator is described by a tunably anharmonic potential, with a square well with infinite walls and the harmonic potential as its extreme limits, and wherein the interaction is nonlinear in the oscillator displacement. We find that even highly anharmonic polarons behave similar to their harmonic counterparts in that selftrapping is preserved for long times in the limit of strong coupling, and that the polaronic tunneling time scale depends exponentially on the polaron binding energy. Further, in agreement with earlier results related to harmonic polarons, the semiclassical approximation agrees with the full quantum result in the massive oscillator limit of small oscillator frequency and strong quasiparticle-oscillator coupling. (author)

Semiclassical model of cross section for fast neutrons

International Nuclear Information System (INIS)

Rosato, A.; D'Oliveira, A.A.

1977-01-01

A study for main aspects of fast neutron scattering is presented and, a semiclassical approximation applying to several pratic cases is described. The obtained results are compared with experimental data for deformed nuclei, and, with theoretical data based on optical model without treatment of deformations. (M.C.K.) [pt

Structures in semiclassical spectra: a question of scale

International Nuclear Information System (INIS)

Berry, M.V.

1984-01-01

Theories of semiclassical bound state spectra for systems with N freedoms are reviewed, emphasizing the different features occurring on successively finer scales of energy E, measured in terms of h/2π, and attempting to correlate these with whether the underlying classical motion is regular or irregular. (Auth.)

Coupled vs. decoupled boundary layers in VOCALS-REx

Directory of Open Access Journals (Sweden)

C. R. Jones

2011-07-01

Full Text Available We analyze the extent of subtropical stratocumulus-capped boundary layer decoupling and its relation to other boundary-layer characteristics and forcings using aircraft observations from VOCALS-REx along a swath of the subtropical southeast Pacific Ocean running west 1600 km from the coast of Northern Chile. We develop two complementary and consistent measures of decoupling. The first is based on boundary layer moisture and temperature stratification in flight profiles from near the surface to above the capping inversion, and the second is based the difference between the lifted condensation level (LCL and a mean lidar-derived cloud base measured on flight legs at 150 m altitude. Most flights took place during early-mid morning, well before the peak in insolation-induced decoupling.

We find that the boundary layer is typically shallower, drier, and well mixed near the shore, and tends to deepen, decouple, and produce more drizzle further offshore to the west. Decoupling is strongly correlated to the "mixed layer cloud thickness", defined as the difference between the capping inversion height and the LCL; other factors such as wind speed, cloud droplet concentration, and inversion thermodynamic jumps have little additional explanatory power. The results are broadly consistent with the deepening-warming theory of decoupling.

In the deeper boundary layers observed well offshore, there was frequently nearly 100 % boundary-layer cloud cover despite pronounced decoupling. The cloud cover was more strongly correlated to a κ parameter related to the inversion jumps of humidity and temperature, though the exact functional relation is slightly different than found in prior large-eddy simulation studies.

Mathematical and computational methods for semiclassical Schrödinger equations

KAUST Repository

Jin, Shi

2011-04-28

We consider time-dependent (linear and nonlinear) Schrödinger equations in a semiclassical scaling. These equations form a canonical class of (nonlinear) dispersive models whose solutions exhibit high-frequency oscillations. The design of efficient numerical methods which produce an accurate approximation of the solutions, or at least of the associated physical observables, is a formidable mathematical challenge. In this article we shall review the basic analytical methods for dealing with such equations, including WKB asymptotics, Wigner measure techniques and Gaussian beams. Moreover, we shall give an overview of the current state of the art of numerical methods (most of which are based on the described analytical techniques) for the Schrödinger equation in the semiclassical regime. © 2011 Cambridge University Press.

Semiclassical approximation in Batalin-Vilkovisky formalism

International Nuclear Information System (INIS)

Schwarz, A.

1993-01-01

The geometry of supermanifolds provided with a Q-structure (i.e. with an odd vector field Q satisfying {Q, Q}=0), a P-structure (odd symplectic structure) and an S-structure (volume element) or with various combinations of these structures is studied. The results are applied to the analysis of the Batalin-Vilkovisky approach to the quantization of gauge theories. In particular the semiclassical approximation in this approach is expressed in terms of Reidemeister torsion. (orig.)

Semiclassical quantization of integrable systems of few interacting anyons in a strong magnetic field

International Nuclear Information System (INIS)

Sivan, N.; Levit, S.

1992-01-01

We present a semiclassical theory of charged interacting anyons in a strong magnetic field. We derive the appropriate generalization of the WKB quantization conditions and determine the corresponding wave functions for non separable integrable anyonic systems. This theory is applies to a system of two interacting anyons, two interacting anyons in the presence of an impurity and three interacting anyons. We calculate the dependence of the semiclassical energy levels on the statistical parameter and find regions in which dependence follows very different patterns. The semiclassical treatment allows to find the correlation between these patterns and the change in the character of the classical motion of the system. We also test the accuracy of the mean field approximation for low and high energy states of the three anyons. (author)

Semiclassical approximations in a mean-field theory with collision terms

International Nuclear Information System (INIS)

Galetti, D.

1986-01-01

Semiclassical approximations in a mean-field theory with collision terms are discussed taking the time dependent Hartree-Fock method as framework in the obtainment of the relevant parameters.(L.C.) [pt

A Synchronization Scheme for Single-Phase Grid-Tied Inverters Under Harmonic Distortion and Grid Disturbances

DEFF Research Database (Denmark)

Hadjidemetriou, Lenos; Kyriakides, Elias; Yang, Yongheng

2016-01-01

Synchronization is a crucial aspect in grid-tied systems, including single-phase photovoltaic inverters, and it can affect the overall performance of the system. Among prior-art synchronization schemes, the Multi Harmonic Decoupling Cell Phase-Locked Loop (MHDC-PLL) presents a fast response under...

Semiclassical interpretation of the Aharonov-Bohm effect

International Nuclear Information System (INIS)

Weisz, J.F.

1990-10-01

A semiclassical calculation gives the exact answer for the Aharonov-Bohm phase shift due to a magnetic field; either in free space or in metallic or semiconducting rings. The magnetic vector potential is not required. The effect is interpretable as a special case of energy conservation involving the Lorentz force. The effect is nonlocal because conservation of energy is nonlocal. (author). 11 refs, 2 figs

Dynamic decoupling of secondary systems

International Nuclear Information System (INIS)

Gupta, A.K.; Tembulkar, J.M.

1984-01-01

The dynamic analysis of primary systems must often be performed decoupled from the secondary system. In doing so, one should assure that the decoupling does not significantly affect the frequencies and the response of the primary systems. The practice consists of heuristic algorithms intended to limit changes in the frequencies. The change in response is not considered. In this paper, changes in both the frequencies and the response are considered. Rational, but simple algorithms are derived to make accurate predictions. Material up to MDOF primary-SDOF secondary system is presented in this paper. MDOF-MDOF systems are treated in a companion paper. (orig.)

Structural Decoupling and Disturbance Rejection in a Distillation Column

DEFF Research Database (Denmark)

Bahar, Mehrdad; Jantzen, Jan; Commault, C.

1996-01-01

Introduction, distillation column model, input-output decoupling, disturbance rejection, concluding remarks, references.......Introduction, distillation column model, input-output decoupling, disturbance rejection, concluding remarks, references....

Semiclassical description of resonant tunneling

International Nuclear Information System (INIS)

Bogomolny, E.B.; Rouben, D.C.

1996-01-01

A semiclassical formula is calculated for the tunneling current of electrons trapped in a potential well which can tunnel into and across a wide quantum well. The tunneling current is measured at the second interface of this well and the calculations idealized an experimental situation where a strong magnetic field tilted with respect to an electric field was used. It is shown that the contribution to the tunneling current, due to trajectories which begin at the first interface and end on the second, is dominant for periodic orbits which hit both walls of the quantum well. (author)

Reconciling semiclassical and Bohmian mechanics. II. Scattering states for discontinuous potentials

International Nuclear Information System (INIS)

Trahan, Corey; Poirier, Bill

2006-01-01

In a previous paper [B. Poirier, J. Chem. Phys. 121, 4501 (2004)] a unique bipolar decomposition, Ψ=Ψ 1 +Ψ 2 , was presented for stationary bound states Ψ of the one-dimensional Schroedinger equation, such that the components Ψ 1 and Ψ 2 approach their semiclassical WKB analogs in the large action limit. Moreover, by applying the Madelung-Bohm ansatz to the components rather than to Ψ itself, the resultant bipolar Bohmian mechanical formulation satisfies the correspondence principle. As a result, the bipolar quantum trajectories are classical-like and well behaved, even when Ψ has many nodes or is wildly oscillatory. In this paper, the previous decomposition scheme is modified in order to achieve the same desirable properties for stationary scattering states. Discontinuous potential systems are considered (hard wall, step potential, and square barrier/well), for which the bipolar quantum potential is found to be zero everywhere, except at the discontinuities. This approach leads to an exact numerical method for computing stationary scattering states of any desired boundary conditions, and reflection and transmission probabilities. The continuous potential case will be considered in a companion paper [C. Trahan and B. Poirier, J. Chem. Phys. 124, 034116 (2006), following paper

Semiclassical scalar propagators in curved backgrounds: Formalism and ambiguities

International Nuclear Information System (INIS)

Grain, J.; Barrau, A.

2007-01-01

The phenomenology of quantum systems in curved space-times is among the most fascinating fields of physics, allowing--often at the gedankenexperiment level--constraints on tentative theories of quantum gravity. Determining the dynamics of fields in curved backgrounds remains, however, a complicated task because of the highly intricate partial differential equations involved, especially when the space metric exhibits no symmetry. In this article, we provide--in a pedagogical way--a general formalism to determine this dynamics at the semiclassical order. To this purpose, a generic expression for the semiclassical propagator is computed and the equation of motion for the probability four-current is derived. Those results underline a direct analogy between the computation of the propagator in general relativistic quantum mechanics and the computation of the propagator for stationary systems in nonrelativistic quantum mechanics. A possible application of this formalism to curvature-induced quantum interferences is also discussed

Semiclassical shell structure and nuclear double-humped fission barriers

Directory of Open Access Journals (Sweden)

A. G. Magner

2010-09-01

Full Text Available We derived the semiclassical trace formulas for the level density as sums over periodic-orbit families and isolated orbits within the improved stationary phase method. Averaged level-density shell corrections and shell-structure energies are continuous through all symmetry-breaking (bifurcation points with the correct asymptotics of the standard stationary phase approach accounting for continuous symmetries. We found enhancement of the nuclear shell structure near bifurcations in the superdeformed region. Our semiclassical results for the averaged level densities with the gross-shell and more thin-shell structures and the energy shell corrections for critical deformations are in good agreement with the quantum calculations for several single-particle Hamiltonians, in particular for the potentials with a sharp spheroidal shape. Enhancement of the shell structure owing to bifurcations of the shortest 3-dimensional orbits from equatorial orbits is responsible for the second well of fission barrier in a superdeformation region.

Premoderator optimization of decoupled hydrogen moderator

International Nuclear Information System (INIS)

Harada, Masahide; Teshigawara, Makoto; Kai, Tetsuya; Sakata, Hideaki; Watanabe, Noboru; Ikeda, Yujiro

2001-03-01

An optimization study on the premoderator, the reflector material choice and a length of the linear is carried out for the design of high performance decoupled hydrogen moderator. NMTC/JAM and MCNP-4C are used for the neutronics calculation. The result indicates that, assuming premoderator dimensions and decoupling energy is controlled, the decoupled hydrogen moderator with a premoderator can provide better pulse characteristics than that without the premoderator for a Be reflector. On the selection of the reflector material, it is clearly shown that Pb and Hg reflectors give merits in using the premoderator for higher intensity and reduction of energy deposition in moderator. It is also shown that a H 2 O premoderator provides a short tail while a D 2 O premoderator provides the high peak intensity. Minimum liner length is evaluated to be 20 cm from the viewpoint of neutronics. (author)

Studies of spatial decoupling in heterogeneous LMFBR critical assemblies

International Nuclear Information System (INIS)

Brumbach, S.B.; Goin, R.W.; Carpenter, S.G.

1984-01-01

Recent measurements at the Zero Power Plutonium Reactor have studied the spatial decoupling in large, heterogeneous assemblies. These assemblies exhibited a significantly greater degree of decoupling than previous homogeneous assemblies of similar size. The flux distributions in these heterogeneous assemblies were very sensitive reactivity perturbations, and perturbed flux distributions were achieved relatively slowly. Decoupling was investigated using rod-drop, boron-oscillator and noise-coherence techniques which emphasized different times following the perturbations. Reactivity changes could be measured by analyzing the power history from a single detector using inverse kinetics methods with the assumption of an instantaneous efficiency change for the detector. For assemblies more decoupled than ZPPR-13, the instantaneous efficiency change assumption begins to be invalid

Semiclassical quantum gravity: statistics of combinatorial Riemannian geometries

International Nuclear Information System (INIS)

Bombelli, L.; Corichi, A.; Winkler, O.

2005-01-01

This paper is a contribution to the development of a framework, to be used in the context of semiclassical canonical quantum gravity, in which to frame questions about the correspondence between discrete spacetime structures at ''quantum scales'' and continuum, classical geometries at large scales. Such a correspondence can be meaningfully established when one has a ''semiclassical'' state in the underlying quantum gravity theory, and the uncertainties in the correspondence arise both from quantum fluctuations in this state and from the kinematical procedure of matching a smooth geometry to a discrete one. We focus on the latter type of uncertainty, and suggest the use of statistical geometry as a way to quantify it. With a cell complex as an example of discrete structure, we discuss how to construct quantities that define a smooth geometry, and how to estimate the associated uncertainties. We also comment briefly on how to combine our results with uncertainties in the underlying quantum state, and on their use when considering phenomenological aspects of quantum gravity. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

Strong semiclassical approximation of Wigner functions for the Hartree dynamics

KAUST Repository

Athanassoulis, Agissilaos; Paul, Thierry; Pezzotti, Federica; Pulvirenti, Mario

2011-01-01

We consider the Wigner equation corresponding to a nonlinear Schrödinger evolution of the Hartree type in the semiclassical limit h → 0. Under appropriate assumptions on the initial data and the interaction potential, we show that the Wigner function is close in L 2 to its weak limit, the solution of the corresponding Vlasov equation. The strong approximation allows the construction of semiclassical operator-valued observables, approximating their quantum counterparts in Hilbert-Schmidt topology. The proof makes use of a pointwise-positivity manipulation, which seems necessary in working with the L 2 norm and the precise form of the nonlinearity. We employ the Husimi function as a pivot between the classical probability density and the Wigner function, which - as it is well known - is not pointwise positive in general.

A time-dependent semiclassical wavepacket method using a fast Fourier transform (FFT) algorithm

International Nuclear Information System (INIS)

Gauss, J.; Heller, E.J.

1991-01-01

A new semiclassical propagator based on a local expansion of the potential up to second order around the moving center of the wavepackt is proposed. Formulas for the propagator are derived and the implementation using grid and fast Fourier transform (FFT) methods is discussed. The semiclassical propagator can be improved up to the exact quantum mechanical limit by including anharmonic corrections using a split operator approach. Preliminary applications to the CH 3 I photodissociation problem show the applicability and accuracy of the proposed method. (orig.)D

Semiclassical moment of inertia shell-structure within the phase-space approach

International Nuclear Information System (INIS)

Gorpinchenko, D V; Magner, A G; Bartel, J; Blocki, J P

2015-01-01

The moment of inertia for nuclear collective rotations is derived within a semiclassical approach based on the cranking model and the Strutinsky shell-correction method by using the non-perturbative periodic-orbit theory in the phase-space variables. This moment of inertia for adiabatic (statistical-equilibrium) rotations can be approximated by the generalized rigid-body moment of inertia accounting for the shell corrections of the particle density. A semiclassical phase-space trace formula allows us to express the shell components of the moment of inertia quite accurately in terms of the free-energy shell corrections for integrable and partially chaotic Fermi systems, which is in good agreement with the corresponding quantum calculations. (paper)

Semiclassical delta self-energy

International Nuclear Information System (INIS)

Voutier, E.

1992-01-01

We present a semiclassical approach in the Δ self-energy. We show that the in-medium corrections of the Δ width issued from the Pauli blocking and the coupling to the 2N-1h continuum are in good agreement with the previous approaches and particularly with the quantum Δ-h model even for light nuclei. We separate out the different sources of the imaginary part of the self-energy. The predominant corrections come from two antagonistic origins: The Pauli blocking and the contribution to the two-nucleon emission channel, the latter being model dependent. We further show that the non-diagonal spin matrix elements of the self-energy, generated by its tensor component, are mostly due to the Pauli blocking. (orig.)

Quantum complex rotation and uniform semiclassical calculations of complex energy eigenvalues

International Nuclear Information System (INIS)

Connor, J.N.L.; Smith, A.D.

1983-01-01

Quantum and semiclassical calculations of complex energy eigenvalues have been carried out for an exponential potential of the form V 0 r 2 exp(-r) and Lennard-Jones (12,6) potential. A straightforward method, based on the complex coordinate rotation technique, is described for the quantum calculation of complex eigenenergies. For singular potentials, the method involves an inward and outward integration of the radial Schroedinger equation, followed by matching of the logarithmic derivatives of the wave functions at an intermediate point. For regular potentials, the method is simpler, as only an inward integration is required. Attention is drawn to the World War II researches of Hartree and co-workers who anticipated later quantum mechanical work on the complex rotation method. Complex eigenenergies are also calculated from a uniform semiclassical three turning point quantization formula, which allows for the proximity of the outer pair of complex turning points. Limiting cases of this formula, which are valid for very narrow or very broad widths, are also used in the calculations. We obtain good agreement between the semiclassical and quantum results. For the Lennard-Jones (12,6) potential, we compare resonance energies and widths from the complex energy definition of a resonance with those obtained from the time delay definition

"Divide-and-conquer" semiclassical molecular dynamics: An application to water clusters

Science.gov (United States)

Di Liberto, Giovanni; Conte, Riccardo; Ceotto, Michele

2018-03-01

We present an investigation of vibrational features in water clusters performed by means of our recently established divide-and-conquer semiclassical approach [M. Ceotto, G. Di Liberto, and R. Conte, Phys. Rev. Lett. 119, 010401 (2017)]. This technique allows us to simulate quantum vibrational spectra of high-dimensional systems starting from full-dimensional classical trajectories and projection of the semiclassical propagator onto a set of lower dimensional subspaces. The potential energy surface employed is a many-body representation up to three-body terms, in which monomers and two-body interactions are described by the high level Wang-Huang-Braams-Bowman (WHBB) water potential, while, for three-body interactions, calculations adopt a fast permutationally invariant ab initio surface at the same level of theory of the WHBB 3-body potential. Applications range from the water dimer up to the water decamer, a system made of 84 vibrational degrees of freedom. Results are generally in agreement with previous variational estimates in the literature. This is particularly true for the bending and the high-frequency stretching motions, while estimates of modes strongly influenced by hydrogen bonding are red shifted, in a few instances even substantially, as a consequence of the dynamical and global picture provided by the semiclassical approach.

Self-consistent collective-coordinate method for ''maximally-decoupled'' collective subspace and its boson mapping: Quantum theory of ''maximally-decoupled'' collective motion

International Nuclear Information System (INIS)

Marumori, T.; Sakata, F.; Maskawa, T.; Une, T.; Hashimoto, Y.

1983-01-01

The main purpose of this paper is to develop a full quantum theory, which is capable by itself of determining a ''maximally-decoupled'' collective motion. The paper is divided into two parts. In the first part, the motivation and basic idea of the theory are explained, and the ''maximal-decoupling condition'' on the collective motion is formulated within the framework of the time-dependent Hartree-Fock theory, in a general form called the invariance principle of the (time-dependent) Schrodinger equation. In the second part, it is shown that when the author positively utilize the invariance principle, we can construct a full quantum theory of the ''maximally-decoupled'' collective motion. This quantum theory is shown to be a generalization of the kinematical boson-mapping theories so far developed, in such a way that the dynamical ''maximal-decoupling condition'' on the collective motion is automatically satisfied

Semi-classical calculation of the spin-isospin response functions

International Nuclear Information System (INIS)

Chanfray, G.

1987-03-01

We present a semi-classical calculation of the nuclear response functions beyond the Thomas-Fermi approximation. We apply our formalism to the spin-isospin responses and show that the surface peaked h/2π corrections considerably decrease the ratio longitudinal/transverse as obtained through hadronic probes

Development and test of decoupler for ICRF antenna in EAST

Energy Technology Data Exchange (ETDEWEB)

Chen, Gen, E-mail: chengen@ipp.ac.cn; Mao, Yuzhou; Zhao, Yanping; Yuan, Shuai; Zhang, Xinjun; Qing, Chengming

2016-06-15

Highlights: • The mechanism of decoupler for ICRF antenna is proposed. • Three candidate assembly positions for the decouper can be used. • The performance relies on the ohmic dissipation and the assembly position of decoupler. - Abstract: Ion Cyclotron Range of Frequency (ICRF) heating has been adopted in EAST tokamak as one of main auxiliary heating methods. The ICRF antenna usually consists of multiple launching elements because of limited port and space of tokamak device. Mutual coupling between straps has been observed in previous EAST ICRF current drive experiments. Due to adverse effects of such mutual coupling, many issues induced by cross power cannot be ignored, such as power imbalance in feed lines, high voltage standing wave ratio (VSWR), and etc. To restrain such mutual coupling, A device named decoupler was developed and tested in EAST ICRF system. According to the admittance matrix of load, three assembly positions (oscillation position, optimum position, and smooth position) along transmission line for the decoupler were taken into account and tested. The test results showed that ohmic dissipation in decoupler could not be neglected, which partly influenced the decoupling performance. The oscillation position and optimum position could restrain such adverse effects of ohmic dissipation and showed good decoupling performance. However, they cannot ensure the steady operation during H-mod due to the load variation. Finally, the smooth position has been adopted for EAST I port antenna because of steady decoupling performance comprised with engineering error and load resilience, which sincerely enhance the capability of system operation.

Decoupling Responsible Management Education

DEFF Research Database (Denmark)

Rasche, Andreas; Gilbert, Dirk Ulrich

Business schools increasingly aim to embed corporate responsibility, sustainability, and ethics into their curricular and extracurricular activities. This paper examines under what conditions business schools may decouple the structural effects of their engagement in responsible management educat...

Shear Wave Generation by Decoupled and Partially Coupled Explosions

National Research Council Canada - National Science Library

Stevens, Jeffry L; Xu, Heming; Baker, G. E

2008-01-01

The objective of this project is to investigate the sources of shear wave generation by decoupled and partially coupled explosions, and the differences in shear wave generation between tamped and decoupled explosions...

Discontinuous Galerkin Time-Domain Analysis of Power-Ground Planes Taking Into Account Decoupling Capacitors

KAUST Repository

Li, Ping

2017-03-22

In this paper, a discontinuous Galerkin time-domain (DGTD) method is developed to analyze the power-ground planes taking into account the decoupling capacitors. In the presence of decoupling capacitors, the whole physical system can be split into two subsystems: 1) the field subsystem that is governed by Maxwell\\'s equations that will be solved by the DGTD method, and 2) the circuit subsystem including the capacitor and its parasitic inductor and resistor, which is going to be characterized by the modified nodal analysis algorithm constructed circuit equations. With the aim to couple the two subsystems together, a lumped port is defined over a coaxial surface between the via barrel and the ground plane. To reach the coupling from the field to the circuit subsystem, a lumped voltage source calculated by the integration of electric field along the radial direction is introduced. On the other hand, to facilitate the coupling from the circuit to field subsystem, a lumped port current source calculated from the circuit equation is introduced, which serves as an impressed current source for the field subsystem. With these two auxiliary terms, a hybrid field-circuit matrix equation is established, which enables the field and circuit subsystems are solved in a synchronous scheme. Furthermore, the arbitrarily shaped antipads are considered by enforcing the proper wave port excitation using the magnetic surface current source derived from the antipads supported electric eigenmodes. In this way, the S-parameters corresponding to different modes can be conveniently extracted. To further improve the efficiency of the proposed algorithm in handling multiscale meshes, the local time-stepping marching scheme is applied. The proposed algorithm is verified by several representative examples.

Quantization ambiguity, ergodicity and semiclassics

International Nuclear Information System (INIS)

Kaplan, Lev

2002-01-01

It is well known that almost all eigenstates of a classically ergodic system are individually ergodic on coarse-grained scales. This has important implications for the quantization ambiguity in ergodic systems: the difference between alternative quantizations is suppressed compared with the O( h-bar 2 ) ambiguity in the integrable or regular case. For two-dimensional ergodic systems in the high-energy regime, individual eigenstates are independent of the choice of quantization procedure, in contrast with the regular case, where even the ordering of eigenlevels is ambiguous. Surprisingly, semiclassical methods are shown to be much more precise in any dimension for chaotic than for integrable systems

Semiclassical instability of warp drives

Energy Technology Data Exchange (ETDEWEB)

Barcelo, C [Instituto de Astrofisica de Andalucia, IAA-CSIC, Glorieta de la Astronomia s/n, 18008 Granada (Spain); Finazzi, S; Liberati, S, E-mail: carlos@iaa.e, E-mail: finazzi@sissa.i, E-mail: liberati@sissa.i

2010-05-01

Warp drives, at least theoretically, provide a way to travel at superluminal speeds. However, even if one succeeded in providing the necessary exotic matter to construct them, it would still be necessary to check whether they would survive to the switching on of quantum effects. In this contribution we will report on the behaviour of the Renormalized Stress-Energy Tensor (RSET) in the spacetimes associated with superluminal warp drives. We find that the RSET will exponentially grow in time close to the front wall of the superluminal bubble, hence strongly supporting the conclusion that the warp-drive geometries are unstable against semiclassical back-reaction.

Semiclassical evolution of dissipative Markovian systems

International Nuclear Information System (INIS)

Ozorio de Almeida, A M; Rios, P de M; Brodier, O

2009-01-01

A semiclassical approximation for an evolving density operator, driven by a 'closed' Hamiltonian operator and 'open' Markovian Lindblad operators, is obtained. The theory is based on the chord function, i.e. the Fourier transform of the Wigner function. It reduces to an exact solution of the Lindblad master equation if the Hamiltonian operator is a quadratic function and the Lindblad operators are linear functions of positions and momenta. Initially, the semiclassical formulae for the case of Hermitian Lindblad operators are reinterpreted in terms of a (real) double phase space, generated by an appropriate classical double Hamiltonian. An extra 'open' term is added to the double Hamiltonian by the non-Hermitian part of the Lindblad operators in the general case of dissipative Markovian evolution. The particular case of generic Hamiltonian operators, but linear dissipative Lindblad operators, is studied in more detail. A Liouville-type equivariance still holds for the corresponding classical evolution in double phase space, but the centre subspace, which supports the Wigner function, is compressed, along with expansion of its conjugate subspace, which supports the chord function. Decoherence narrows the relevant region of double phase space to the neighbourhood of a caustic for both the Wigner function and the chord function. This difficulty is avoided by a propagator in a mixed representation, so that a further 'small-chord' approximation leads to a simple generalization of the quadratic theory for evolving Wigner functions

Semi-classical scalar propagators in curved backgrounds: formalism and ambiguities

Energy Technology Data Exchange (ETDEWEB)

Grain, J. [Laboratory for Subatomic Physics and Cosmology, Grenoble Universites, CNRS, IN2P3, 53, avenue de Martyrs, 38026 Grenoble cedex (France)]|[AstroParticle and Cosmology, Universite Paris 7, CNRS, IN2P3, 10, rue Alice Domon et Leonie Duquet, 75205 Paris cedex 13 (France); Barrau, A. [Laboratory for Subatomic Physics and Cosmology, Grenoble Universites, CNRS, IN2P3, 53, avenue de Martyrs, 38026 Grenoble cedex (France)

2007-05-15

The phenomenology of quantum systems in curved space-times is among the most fascinating fields of physics, allowing - often at the Gedanken experiment level - constraints on tentative theories of quantum gravity. Determining the dynamics of fields in curved backgrounds remains however a complicated task because of the highly intricate partial differential equations involved, especially when the space metric exhibits no symmetry. In this article, we provide - in a pedagogical way - a general formalism to determine this dynamics at the semi-classical order. To this purpose, a generic expression for the semi-classical propagator is computed and the equation of motion for the probability four-current is derived. Those results underline a direct analogy between the computation of the propagator in general relativistic quantum mechanics and the computation of the propagator for stationary systems in non-relativistic quantum mechanics. (authors)

Semi-classical scalar propagators in curved backgrounds: formalism and ambiguities

International Nuclear Information System (INIS)

Grain, J.; Barrau, A.

2007-05-01

The phenomenology of quantum systems in curved space-times is among the most fascinating fields of physics, allowing - often at the Gedanken experiment level - constraints on tentative theories of quantum gravity. Determining the dynamics of fields in curved backgrounds remains however a complicated task because of the highly intricate partial differential equations involved, especially when the space metric exhibits no symmetry. In this article, we provide - in a pedagogical way - a general formalism to determine this dynamics at the semi-classical order. To this purpose, a generic expression for the semi-classical propagator is computed and the equation of motion for the probability four-current is derived. Those results underline a direct analogy between the computation of the propagator in general relativistic quantum mechanics and the computation of the propagator for stationary systems in non-relativistic quantum mechanics. (authors)

Remnants of semiclassical bistability in the few-photon regime of cavity QED.

Science.gov (United States)

Kerckhoff, Joseph; Armen, Michael A; Mabuchi, Hideo

2011-11-21

Broadband homodyne detection of the light transmitted by a Fabry-Perot cavity containing a strongly-coupled (133)Cs atom is used to probe the dynamic optical response in a regime where semiclassical theory predicts bistability but strong quantum corrections should apply. While quantum fluctuations destabilize true equilibrium bistability, our observations confirm the existence of metastable states with finite lifetimes and a hysteretic response is apparent when the optical drive is modulated on comparable timescales. Our experiment elucidates remnant semiclassical behavior in the attojoule (~10 photon) regime of single-atom cavity QED, of potential significance for ultra-low power photonic signal processing. © 2011 Optical Society of America

Non-trapping condition for semiclassical Schr dinger operators with matrix-valued potentials.

CERN Document Server

Jecko, T

2004-01-01

We consider semiclassical Schr dinger operators with matrix-valued, long-range, smooth potential, for which different eigenvalues may cross on a codimension one submanifold. We denote by h the semiclassical parameter and we consider energies above the bottom of the essential spectrum. Under some invariance condition on the matricial structure of the potential near the eigenvalues crossing and some structure condition at infinity, we prove that the boundary values of the resolvent at energy lambda, as bounded operators on suitable weighted spaces, are O(1/h) if and only if lambda is a non-trapping energy for all the Hamilton flows generated by the eigenvalues of the operator's symbol.

Spectral statistics in semiclassical random-matrix ensembles

International Nuclear Information System (INIS)

Feingold, M.; Leitner, D.M.; Wilkinson, M.

1991-01-01

A novel random-matrix ensemble is introduced which mimics the global structure inherent in the Hamiltonian matrices of autonomous, ergodic systems. Changes in its parameters induce a transition between a Poisson and a Wigner distribution for the level spacings, P(s). The intermediate distributions are uniquely determined by a single scaling variable. Semiclassical constraints force the ensemble to be in a regime with Wigner P(s) for systems with more than two freedoms

A semiclassical study of optical potentials - potential resonances -

International Nuclear Information System (INIS)

Lee, S.Y.; Takigawa, N.; Marty, C.

1977-01-01

A semiclassical method is used to analyze resonances produced by complex potentials. The absorption plays a central role: when it is not too great, resonances manifest themselves by enhancement of cross sections near π. The reverse is not necessarily true, for instance the anomalous large angle scattering for α-Ca is due to a coherent superposition of many partial waves

Optimal Temporal Decoupling in Task Scheduling with Preferences

NARCIS (Netherlands)

Endhoven, L.; Klos, T.B.; Witteveen, C.

2011-01-01

Multi-agent planning and scheduling concerns finding a joint plan to achieve some set of common goals with several independent agents each aiming to find a plan or schedule for their part of the goals. To avoid conflicts in these individual plans or schedules decoupling is used. Such a decoupling

On the late-time behavior of Virasoro blocks and a classification of semiclassical saddles

Energy Technology Data Exchange (ETDEWEB)

Fitzpatrick, A. Liam [Department of Physics, Boston University,Commonwealth Avenue, Boston, MA 02215 (United States); Kaplan, Jared [Department of Physics and Astronomy, Johns Hopkins University,Charles Street, Baltimore, MD 21218 (United States)

2017-04-12

Recent work has demonstrated that black hole thermodynamics and information loss/restoration in AdS{sub 3}/CFT{sub 2} can be derived almost entirely from the behavior of the Virasoro conformal blocks at large central charge, with relatively little dependence on the precise details of the CFT spectrum or OPE coefficients. Here, we elaborate on the non-perturbative behavior of Virasoro blocks by classifying all ‘saddles’ that can contribute for arbitrary values of external and internal operator dimensions in the semiclassical large central charge limit. The leading saddles, which determine the naive semiclassical behavior of the Virasoro blocks, all decay exponentially at late times, and at a rate that is independent of internal operator dimensions. Consequently, the semiclassical contribution of a finite number of high-energy states cannot resolve a well-known version of the information loss problem in AdS{sub 3}. However, we identify two infinite classes of sub-leading saddles, and one of these classes does not decay at late times.

Relativeness in quantum gravity: limitations and frame dependence of semiclassical descriptions

International Nuclear Information System (INIS)

Nomura, Yasunori; Sanches, Fabio; Weinberg, Sean J.

2015-01-01

Consistency between quantum mechanical and general relativistic views of the world is a longstanding problem, which becomes particularly prominent in black hole physics. We develop a coherent picture addressing this issue by studying the quantum mechanics of an evolving black hole. After interpreting the Bekenstein-Hawking entropy as the entropy representing the degrees of freedom that are coarse-grained to obtain a semiclassical description from the microscopic theory of quantum gravity, we discuss the properties these degrees of freedom exhibit when viewed from the semiclassical standpoint. We are led to the conclusion that they show features which we call extreme relativeness and spacetime-matter duality — a nontrivial reference frame dependence of their spacetime distribution and the dual roles they play as the “constituents” of spacetime and as thermal radiation. We describe black hole formation and evaporation processes in distant and infalling reference frames, showing that these two properties allow us to avoid the arguments for firewalls and to make the existence of the black hole interior consistent with unitary evolution in the sense of complementarity. Our analysis provides a concrete answer to how information can be preserved at the quantum level throughout the evolution of a black hole, and gives a basic picture of how general coordinate transformations may work at the level of full quantum gravity beyond the approximation of semiclassical theory.

DECOUPLER DESIGN FOR AN INTERACTING TANKS SYSTEM

Directory of Open Access Journals (Sweden)

Duraid F. Ahmed

2013-05-01

Full Text Available The mathematical model forthe two interacting tanks system was derived and the dynamic behavior of thissystem was studied by introducing a step change in inlet flow rate. In thispaper, the analysis of the interaction loops between the controlled variable(liquid level and manipulated variable (inlet flow rate was carried out usingthe relative gain array. Also decoupling technique is applied to eliminate theeffect this interaction by design suitable decouplers for the system. Theresults show that the gain of each loop is cut in half when the opposite loopis closed and the gain of other loop changes sign when the opposite loop isclosed. The decoupling method show that the liquid level of tank one isconstant when the second inlet flow changes and to keep the liquid level oftank two constant the first inlet flow must be changed.

Gaussian and 1/N approximations in semiclassical cosmology

International Nuclear Information System (INIS)

Mazzitelli, F.D.; Paz, J.P.

1989-01-01

We study the λphi 4 theory and the interacting O(N) model in a curved background using the Gaussian approximation for the former and the large-N approximation for the latter. We obtain the renormalized version of the semiclassical Einstein equations having in mind a future application of these models to investigate the physics of the very early Universe. We show that, while the Gaussian approximation has two different phases, in the large-N limit only one is present. The different features of the two phases are analyzed at the level of the effective field equations. We discuss the initial-value problem and find the initial conditions that make the theory renormalizable. As an example, we study the de Sitter self-consistent solutions of the semiclassical Einstein equations. Finally, for an identically zero mean value of the field we find the evolution equations for the classical field Ω(x) = (λ 2 >)/sup 1/2/ and the spacetime metric. They are very similar to the ones obtained by replacing the classical potential by the one-loop effective potential in the classical equations but do not have the drawbacks of the one-loop approximation

Sign and other aspects of semiclassical Casimir energies

International Nuclear Information System (INIS)

Schaden, Martin

2006-01-01

The Casimir energy of a massless scalar field is semiclassically given by contributions due to classical periodic rays. The required subtractions in the spectral density are determined explicitly. The semiclassical Casimir energies so defined coincide with those of zeta function regularization in the cases studied. Poles in the analytic continuation of zeta function regularization are related to nonuniversal subtractions in the spectral density. The sign of the Casimir energy of a scalar field on a smooth manifold is estimated by the sign of the contribution due to the shortest periodic rays only. Demanding continuity of the Casimir energy under small deformations of the manifold, the method is extended to integrable systems. The Casimir energy of a massless scalar field on a manifold with boundaries includes contributions due to periodic rays that lie entirely within the boundaries. These contributions in general depend on the boundary conditions. Although the Casimir energy due to a massless scalar field may be sensitive to the physical dimensions of manifolds with boundary. In favorable cases its sign can, contrary to conventional wisdom, be inferred without calculation of the Casimir energy

Coherent and semiclassical states in a magnetic field in the presence of the Aharonov-Bohm solenoid

Energy Technology Data Exchange (ETDEWEB)

Bagrov, V G [Department of Physics, Tomsk State University, 634050 Tomsk (Russian Federation); Gavrilov, S P; Gitman, D M; Filho, D P Meira, E-mail: bagrov@phys.tsu.ru, E-mail: gavrilovsergeyp@yahoo.com, E-mail: gitman@dfn.if.usp.br, E-mail: dmeira@dfn.if.usp.br [Institute of Physics, University of Sao Paulo, CP 66318, CEP 05315-970 Sao Paulo, SP (Brazil)

2011-02-04

A new approach to constructing coherent states (CS) and semiclassical states (SS) in a magnetic-solenoid field is proposed. The main idea is based on the fact that the AB solenoid breaks the translational symmetry in the xy-plane; this has a topological effect such that there appear two types of trajectories which embrace and do not embrace the solenoid. Due to this fact, one has to construct two different kinds of CS/SS which correspond to such trajectories in the semiclassical limit. Following this idea, we construct CS in two steps, first the instantaneous CS (ICS) and then the time-dependent CS/SS as an evolution of the ICS. The construction is realized for nonrelativistic and relativistic spinning particles both in (2 + 1) and (3 + 1) dimensions and gives a non-trivial example of SS/CS for systems with a nonquadratic Hamiltonian. It is stressed that CS depending on their parameters (quantum numbers) describe both pure quantum and semiclassical states. An analysis is represented that classifies parameters of the CS in such respect. Such a classification is used for the semiclassical decompositions of various physical quantities.

Coherent and semiclassical states in a magnetic field in the presence of the Aharonov-Bohm solenoid

International Nuclear Information System (INIS)

Bagrov, V G; Gavrilov, S P; Gitman, D M; Filho, D P Meira

2011-01-01

A new approach to constructing coherent states (CS) and semiclassical states (SS) in a magnetic-solenoid field is proposed. The main idea is based on the fact that the AB solenoid breaks the translational symmetry in the xy-plane; this has a topological effect such that there appear two types of trajectories which embrace and do not embrace the solenoid. Due to this fact, one has to construct two different kinds of CS/SS which correspond to such trajectories in the semiclassical limit. Following this idea, we construct CS in two steps, first the instantaneous CS (ICS) and then the time-dependent CS/SS as an evolution of the ICS. The construction is realized for nonrelativistic and relativistic spinning particles both in (2 + 1) and (3 + 1) dimensions and gives a non-trivial example of SS/CS for systems with a nonquadratic Hamiltonian. It is stressed that CS depending on their parameters (quantum numbers) describe both pure quantum and semiclassical states. An analysis is represented that classifies parameters of the CS in such respect. Such a classification is used for the semiclassical decompositions of various physical quantities.

Experimental studies by complementary terahertz techniques and semi-classical calculations of N2- broadening coefficients of CH335Cl

International Nuclear Information System (INIS)

Guinet, M.; Rohart, F.; Buldyreva, J.; Gupta, V.; Eliet, S.; Motiyenko, R.A.; Margulès, L.; Cuisset, A.; Hindle, F.; Mouret, G.

2012-01-01

Room-temperature N 2 -broadening coefficients of methyl chloride rotational lines are measured over a large interval of quantum numbers (6≤J≤50, 0≤K≤18) by a submillimeter frequency-multiplication chain (J≤31) and a terahertz photomixing continuous-wave spectrometer (J≥31). In order to check the accuracy of both techniques, the measurements of identical lines are compared for J=31. The pressure broadening coefficients are deduced from line fits using mainly a Voigt profile model. The excellent signal-to-noise ratio of the frequency-multiplication scheme highlights some speed dependence effect on the line shape. Theoretical values of these coefficients are calculated by a semi-classical approach with exact trajectories. An intermolecular potential including atom-atom interactions is used for the first time. It is shown that, contrary to the previous theoretical predictions, the contributions of short-range forces are important for all values of the rotational quantum numbers. Additional testing of modifications required in the semi-classical formalism for a correct application of the cumulant expansion is also performed. It is stated that the use of the cumulant average on the rotational states of the perturbing molecule leads, for high J and small K values, to slightly higher line-broadening coefficients, as expected for the relatively strong interacting CH 3 Cl-N 2 system. The excellent agreement between the theoretical and the experimental results ensures the reliability of these data.

Experimental studies by complementary terahertz techniques and semi-classical calculations of N2- broadening coefficients of CH335Cl

Science.gov (United States)

Guinet, M.; Rohart, F.; Buldyreva, J.; Gupta, V.; Eliet, S.; Motiyenko, R. A.; Margulès, L.; Cuisset, A.; Hindle, F.; Mouret, G.

2012-07-01

Room-temperature N2-broadening coefficients of methyl chloride rotational lines are measured over a large interval of quantum numbers (6≤J≤50, 0≤K≤18) by a submillimeter frequency-multiplication chain (J≤31) and a terahertz photomixing continuous-wave spectrometer (J≥31). In order to check the accuracy of both techniques, the measurements of identical lines are compared for J=31. The pressure broadening coefficients are deduced from line fits using mainly a Voigt profile model. The excellent signal-to-noise ratio of the frequency-multiplication scheme highlights some speed dependence effect on the line shape. Theoretical values of these coefficients are calculated by a semi-classical approach with exact trajectories. An intermolecular potential including atom-atom interactions is used for the first time. It is shown that, contrary to the previous theoretical predictions, the contributions of short-range forces are important for all values of the rotational quantum numbers. Additional testing of modifications required in the semi-classical formalism for a correct application of the cumulant expansion is also performed. It is stated that the use of the cumulant average on the rotational states of the perturbing molecule leads, for high J and small K values, to slightly higher line-broadening coefficients, as expected for the relatively strong interacting CH3Cl-N2 system. The excellent agreement between the theoretical and the experimental results ensures the reliability of these data.

Semiclassical expansions for confined N fermion systems

International Nuclear Information System (INIS)

Krivine, H.; Martorell, J.; Casas, M.

1989-01-01

A new derivation of the Wigner Kirkwood expansion for N-fermion systems is presented, showing explicitly the connection to the WKB approximation for a single level. This allows to study separately the two ansatz required to obtain the semiclassical expansions: the asymptotic expansions in powers of ℎ and the smoothing of quantal effects. We discuss the one dimensional and three dimensional, with spherical symmetry, cases. Applications for standard potentials used in nuclear physics are described in detail

Semiclassical limit of the FZZT Liouville theory

International Nuclear Information System (INIS)

Hadasz, Leszek; Jaskolski, Zbigniew

2006-01-01

The semiclassical limit of the FZZT Liouville theory on the upper half plane with bulk operators of arbitrary type and with elliptic boundary operators is analyzed. We prove the Polyakov conjecture for an appropriate classical Liouville action. This action is calculated in a number of cases: One bulk operator of arbitrary type, one bulk and one boundary, and two boundary elliptic operators. The results are in agreement with the classical limits of the corresponding quantum correlators

Semiclassical limit of the FZZT Liouville theory

Science.gov (United States)

Hadasz, Leszek; Jaskólski, Zbigniew

2006-11-01

The semiclassical limit of the FZZT Liouville theory on the upper half plane with bulk operators of arbitrary type and with elliptic boundary operators is analyzed. We prove the Polyakov conjecture for an appropriate classical Liouville action. This action is calculated in a number of cases: One bulk operator of arbitrary type, one bulk and one boundary, and two boundary elliptic operators. The results are in agreement with the classical limits of the corresponding quantum correlators.

Semiclassical limit of the FZZT Liouville theory

OpenAIRE

Hadasz, Leszek; Jaskolski, Zbigniew

2006-01-01

The semiclassical limit of the FZZT Liouville theory on the upper half plane with bulk operators of arbitrary type and with elliptic boundary operators is analyzed. We prove the Polyakov conjecture for an appropriate classical Liouville action. This action is calculated in a number of cases: one bulk operator of arbitrary type, one bulk and one boundary, and two boundary elliptic operators. The results are in agreement with the classical limits of the corresponding quantum correlators.

Semiclassical limit of the FZZT Liouville theory

Energy Technology Data Exchange (ETDEWEB)

Hadasz, Leszek [Physikalisches Institut, Rheinische Friedrich-Wilhelms-Universitaet, Nussallee 12, 53115 Bonn (Germany); M. Smoluchowski Institute of Physics, Jagiellonian University, W. Reymonta 4, 30-059 Cracow (Poland)]. E-mail: hadasz@th.if.uj.edu.pl; Jaskolski, Zbigniew [Institute of Theoretical Physics, University of Wroclaw, pl. M. Borna 9, 50-204 Wroclaw (Poland)]. E-mail: jask@ift.uni.wroc.pl

2006-11-27

The semiclassical limit of the FZZT Liouville theory on the upper half plane with bulk operators of arbitrary type and with elliptic boundary operators is analyzed. We prove the Polyakov conjecture for an appropriate classical Liouville action. This action is calculated in a number of cases: One bulk operator of arbitrary type, one bulk and one boundary, and two boundary elliptic operators. The results are in agreement with the classical limits of the corresponding quantum correlators.

Decoupling of Solid 4He Layers under the Superfluid Overlayer

Science.gov (United States)

Ishibashi, Kenji; Hiraide, Jo; Taniguchi, Junko; Suzuki, Masaru

2018-03-01

It has been reported that in a large oscillation amplitude, the mass decoupling of multilayer 4He films adsorbed on graphite results from the depinning of the second solid atomic layer. This decoupling suddenly vanishes below a certain low temperature TD due to the cancellation of mass decoupling by the superfluid counterflow of the the overylayer. We studied the relaxation of the depinned state at various temperatures, after reduction of oscillation amplitude below TD . It was found that above the superfluid transition temperature the mass decoupling revives with a relaxation time of several 100 s. It strongly supports that the depinned state of the second solid atomic layer remains underneath the superfluid overlayer.

Quasinormal modes of semiclassical electrically charged black holes

Energy Technology Data Exchange (ETDEWEB)

Fernandez Piedra, Owen Pavel [Departamento de Fisica y Quimica, Facultad de Mecanica, Universidad de Cienfuegos, Carretera a Rodas, km 4, Cuatro Caminos, Cienfuegos (Cuba); De Oliveira, Jeferson, E-mail: opavel@ucf.edu.cu, E-mail: jeferson@fma.if.usp.br [Instituto de Fisica, Universidade de Sao Paulo, CP 66318, 05315-970, Sao Paulo (Brazil)

2011-04-21

We report the results concerning the influence of vacuum polarization due to quantum massive vector, scalar and spinor fields on the scalar sector of quasinormal modes in spherically symmetric charged black holes. The vacuum polarization from quantized fields produces a shift in the values of the quasinormal frequencies, and correspondingly the semiclassical system becomes a better oscillator with respect to the classical Reissner-Nordstroem black hole.

Domain shape dependence of semiclassical corrections to energy

International Nuclear Information System (INIS)

Kwiatkowski, Grzegorz

2017-01-01

Stationary solution of a one-dimensional sine-Gordon system is embedded in a multidimensional theory with an explicitly finite domain in the added spatial dimensions. Semiclassical corrections to energy are calculated for a static kink solution with emphasis on the impact of the scale of the domain as well as the choice of boundary conditions on the results for a rectangular cross-section. (paper)

Evasive levels in quantisation through wavepacket coupling: a semi-classical investigation

International Nuclear Information System (INIS)

Amiot, P.; Giraud, B.

1984-01-01

A new method is presented to introduce classical mechanics elements into the problem of obtaining the spectrum of an operator H-circumflex(p-circumflex, q-circumflex). A finite-rank functional space is created by centering complex wavepackets on a discrete number of points on an equi-energy of the classical H(p,q) and by placing real wavepackets in the classically forbidden region. The latter span the active subspace, P, and the former the inactive subspace, Q, for an application of the method of Bloch-Horowitz. A semi-classical study of the Green function in the inactive subspace Q, classically allowed, gives a clear explanation of this phenomenon and sheds new light on the significance of this semi-classical approximation for the propagator. An extension to the problem of barrier penetration is proposed. (author)

Few-body semiclassical approach to nucleon transfer and emission reactions

Directory of Open Access Journals (Sweden)

Sultanov Renat A.

2014-04-01

Full Text Available A three-body semiclassical model is proposed to describe the nucleon transfer and emission reactions in a heavy-ion collision. In this model the two heavy particles, i.e. nuclear cores A1(ZA1, MA1 and A2(ZA2, MA2, move along classical trajectories R→1(t${{\\vec R}_1}\\left( t \\right$ and R→2(t${{\\vec R}_2}\\left( t \\right$ respectively, while the dynamics of the lighter neutron (n is considered from a quantum mechanical point of view. Here, Mi are the nucleon masses and Zi are the Coulomb charges of the heavy nuclei (i = 1, 2. A Faddeev-type semiclassical formulation using realistic paired nuclear-nuclear potentials is applied so that all three channels (elastic, rearrangement and break-up are described in a unified manner. In order to solve the time-dependent equations the Faddeev components of the total three-body wave-function are expanded in terms of the input and output channel target eigenfunctions. In the special case, when the nuclear cores are identical (A1 ≡ A2 and also the two-level approximation in the expansion over the target (subsystem functions is used, the time-dependent semiclassical Faddeev equations are resolved in an explicit way. To determine the realistic R→1(t${{\\vec R}_1}\\left( t \\right$ and R→2(t${{\\vec R}_2}\\left( t \\right$ trajectories of the nuclear cores, a self-consistent approach based on the Feynman path integral theory is applied.

Regular black holes from semi-classical down to Planckian size

Science.gov (United States)

Spallucci, Euro; Smailagic, Anais

In this paper, we review various models of curvature singularity free black holes (BHs). In the first part of the review, we describe semi-classical solutions of the Einstein equations which, however, contains a “quantum” input through the matter source. We start by reviewing the early model by Bardeen where the metric is regularized by-hand through a short-distance cutoff, which is justified in terms of nonlinear electro-dynamical effects. This toy-model is useful to point-out the common features shared by all regular semi-classical black holes. Then, we solve Einstein equations with a Gaussian source encoding the quantum spread of an elementary particle. We identify, the a priori arbitrary, Gaussian width with the Compton wavelength of the quantum particle. This Compton-Gauss model leads to the estimate of a terminal density that a gravitationally collapsed object can achieve. We identify this density to be the Planck density, and reformulate the Gaussian model assuming this as its peak density. All these models, are physically reliable as long as the BH mass is big enough with respect to the Planck mass. In the truly Planckian regime, the semi-classical approximation breaks down. In this case, a fully quantum BH description is needed. In the last part of this paper, we propose a nongeometrical quantum model of Planckian BHs implementing the Holographic Principle and realizing the “classicalization” scenario recently introduced by Dvali and collaborators. The classical relation between the mass and radius of the BH emerges only in the classical limit, far away from the Planck scale.

An information-guided channel-hopping scheme for block-fading channels with estimation errors

KAUST Repository

Yang, Yuli

2010-12-01

Information-guided channel-hopping technique employing multiple transmit antennas was previously proposed for supporting high data rate transmission over fading channels. This scheme achieves higher data rates than some mature schemes, such as the well-known cyclic transmit antenna selection and space-time block coding, by exploiting the independence character of multiple channels, which effectively results in having an additional information transmitting channel. Moreover, maximum likelihood decoding may be performed by simply decoupling the signals conveyed by the different mapping methods. In this paper, we investigate the achievable spectral efficiency of this scheme in the case of having channel estimation errors, with optimum pilot overhead for minimum meansquare error channel estimation, when transmitting over blockfading channels. Our numerical results further substantiate the robustness of the presented scheme, even with imperfect channel state information. ©2010 IEEE.

The Geometry of the Semiclassical Wave Front Set for Schrödinger Eigenfunctions on the Torus

Energy Technology Data Exchange (ETDEWEB)

Cardin, Franco, E-mail: cardin@math.unipd.it; Zanelli, Lorenzo, E-mail: lzanelli@math.unipd.it [University of Padova, Department of Mathematics “Tullio Levi Civita” (Italy)

2017-06-15

This paper deals with the phase space analysis for a family of Schrödinger eigenfunctions ψ{sub ℏ} on the flat torus #Mathematical Double-Struck Capital T#{sup n} = (ℝ/2πℤ){sup n} by the semiclassical Wave Front Set. We study those ψ{sub ℏ} such that WF{sub ℏ}(ψ{sub ℏ}) is contained in the graph of the gradient of some viscosity solutions of the Hamilton-Jacobi equation. It turns out that the semiclassical Wave Front Set of such Schrödinger eigenfunctions is stable under viscous perturbations of Mean Field Game kind. These results provide a further viewpoint, and in a wider setting, of the link between the smooth invariant tori of Liouville integrable Hamiltonian systems and the semiclassical localization of Schrödinger eigenfunctions on the torus.

Adaptive decoupled power control method for inverter connected DG

DEFF Research Database (Denmark)

Sun, Xiaofeng; Tian, Yanjun; Chen, Zhe

2014-01-01

an adaptive droop control method based on online evaluation of power decouple matrix for inverter connected distributed generations in distribution system. Traditional decoupled power control is simply based on line impedance parameter, but the load characteristics also cause the power coupling, and alter...

The symmetric = ω -semi-classical orthogonal polynomials of class one

Science.gov (United States)

Maroni, P.; Mejri, M.

2008-12-01

We give the system of Laguerre-Freud equations associated with the = ω -semi-classical functionals of class one, where = ω is the divided difference operator. This system is solved in the symmetric case. There are essentially two canonical cases. The corresponding integral representations are given.

Are CAP Decoupling Policies Really Production Neutral?

OpenAIRE

Katranidis, Stelios D.; Kotakou, Christina A.

2008-01-01

This paper examines the effects of decoupling policies on Greek cotton production. We estimate a system of cotton supply and input derived demand functions under the hypothesis that producers face uncertainty about prices. Using our estimation results we simulate the effects on cotton production under four alternative policy scenarios: the ‘Old’ CAP regime (i.e. the policy practiced until 2005), the Mid Term Review regime, a fully decoupled policy regime and a free trade-no policy scenario. O...

Effects of decoupling of carbon dioxide emission by Chinese nonferrous metals industry

International Nuclear Information System (INIS)

Ren Shenggang; Hu Zhen

2012-01-01

We adopted the refined Laspeyres index approach to explore the impacts of industry scale, energy mix, energy intensity and utility mix on the total carbon dioxide emissions from the Chinese nonferrous metals industry for the period 1996–2008. In addition, we calculated the trend of decoupling effects in nonferrous metals industry in China by presenting a theoretical framework for decoupling. As the results suggest, Chinese nonferrous metals industry has gone through four decoupling stages: strong negative decoupling stage (1996–1998), weak decoupling stage (1999–2000), expensive negative decoupling stage (2001–2003) and weak decoupling stage (2004–2008). We have analyzed the reasons for each phase. Generally speaking, the rapid growth of the industry is the most important factor responsible for the increase of CO 2 emissions, and the change in energy mix was mainly due to the increased proportion of electric energy consumption that has contributed to the increase of CO 2 emissions. Reduction of energy intensity has contributed significantly to emissions decrease, and the utility mix effect has also contributed to the emission decrease to some extent. - Highlights: ► We calculate the decoupling effects of CO 2 from Chinese nonferrous metals industry. ► Results demonstrate that the industry has gone through four decoupling stages. ► The output effect is most important for the increase of CO 2 emissions. ► Reduction of energy intensity has contributed significantly to emissions decrease.

Quantum versus semiclassical description of self-trapping: Anharmonic effects

International Nuclear Information System (INIS)

Raghavan, S.; Bishop, A.R.; Kenkre, V.M.

1999-01-01

Self-trapping has been traditionally studied on the assumption that quasiparticles interact with harmonic phonons and that this interaction is linear in the displacement of the phonon. To complement recent semiclassical studies of anharmonicity and nonlinearity in this context, we present below a fully quantum-mechanical analysis of a two-site system, where the oscillator is described by a tunably anharmonic potential, with a square well with infinite walls and the harmonic potential as its extreme limits, and wherein the interaction is nonlinear in the oscillator displacement. We find that even highly anharmonic polarons behave similar to their harmonic counterparts in that self-trapping is preserved for long times in the limit of strong coupling, and that the polaronic tunneling time scale depends exponentially on the polaron binding energy. Further, in agreement, with earlier results related to harmonic polarons, the semiclassical approximation agrees with the full quantum result in the massive oscillator limit of small oscillator frequency and strong quasiparticle-oscillator coupling. copyright 1999 The American Physical Society

Optimal decoupling controllers revisited

Czech Academy of Sciences Publication Activity Database

Kučera, Vladimír

2013-01-01

Roč. 42, č. 1 (2013), s. 1-16 ISSN 0324-8569 R&D Projects: GA TA ČR(CZ) TE01020197 Institutional support: RVO:67985556 Keywords : linear systems * fractional representations * decoupling control lers * stabilizing control lers * optimal control lers Subject RIV: BC - Control Systems Theory

COMPARATIVE STUDY OF THREE LINEAR SYSTEM SOLVER APPLIED TO FAST DECOUPLED LOAD FLOW METHOD FOR CONTINGENCY ANALYSIS

Directory of Open Access Journals (Sweden)

Syafii

2017-03-01

Full Text Available This paper presents the assessment of fast decoupled load flow computation using three linear system solver scheme. The full matrix version of the fast decoupled load flow based on XB methods used in this study. The numerical investigations are carried out on the small and large test systems. The execution time of small system such as IEEE 14, 30, and 57 are very fast, therefore the computation time can not be compared for these cases. Another cases IEEE 118, 300 and TNB 664 produced significant execution speedup. The superLU factorization sparse matrix solver has best performance and speedup of load flow solution as well as in contigency analysis. The invers full matrix solver can solved only for IEEE 118 bus test system in 3.715 second and for another cases take too long time. However for superLU factorization linear solver can solved all of test system in 7.832 second for a largest of test system. Therefore the superLU factorization linear solver can be a viable alternative applied in contingency analysis.

The Wigner transform and the semi-classical approximations

International Nuclear Information System (INIS)

Shlomo, S.

1985-01-01

The Wigner transform provides a reformulation of quantum mechanics in terms of classical concepts. Some properties of the Wigner transform of the density matrix which justify its interpretation as the quantum-mechanical analog of the classical phase-space distribution function are presented. Considering some applications, it is demonstrated that the Wigner distribution function serves as a good starting point for semi-classical approximations to properties of the (nuclear) many-body system

The shell effects in s-wave neutron resonance level densities ρ according to combinatorial calculations and on the basis of the semi-classical approach

International Nuclear Information System (INIS)

Kaczmarczyk, Maria

2005-01-01

The results of calculations of level densities ρ, in the vicinity of the neutron binding energy S n , are presented. These results were obtained using the Boehning combinatorial method for the calculation of particle-hole state densities dependent on the number of decompositions of the nucleus excitation energy to energies of independent fermions. The calculation was based on the semi-classical model description in the computation of particle-hole state densities and then of the level densities ρ, and takes into account the existence of energy gaps Δ, located near the Fermi level, in a single particle level scheme. This procedure considerably improved and extended the Boehning calculation method. The results, which were obtained in this way for ρ, for 220 nuclei, reproduce the regularities observed in the experimental values of ρ, which are dependent on the neutron number N, and they agree with the experimental data within two orders of magnitude. In addition, the neutron resonance densities ρ were calculated on the basis of the particle-hole state densities obtained using the analytical formula from Boehning's paper. To make the calculations possible, the values of 'complexity' k, as given in the semi-classical model, and the spin factors R(J), according to the paper by Ryckbosch, were used

Relative criterion for validity of a semiclassical approach to the dynamics near quantum critical points.

Science.gov (United States)

Wang, Qian; Qin, Pinquan; Wang, Wen-ge

2015-10-01

Based on an analysis of Feynman's path integral formulation of the propagator, a relative criterion is proposed for validity of a semiclassical approach to the dynamics near critical points in a class of systems undergoing quantum phase transitions. It is given by an effective Planck constant, in the relative sense that a smaller effective Planck constant implies better performance of the semiclassical approach. Numerical tests of this relative criterion are given in the XY model and in the Dicke model.

Semiclassical analysis, Witten Laplacians, and statistical mechanis

CERN Document Server

Helffer, Bernard

2002-01-01

This important book explains how the technique of Witten Laplacians may be useful in statistical mechanics. It considers the problem of analyzing the decay of correlations, after presenting its origin in statistical mechanics. In addition, it compares the Witten Laplacian approach with other techniques, such as the transfer matrix approach and its semiclassical analysis. The author concludes by providing a complete proof of the uniform Log-Sobolev inequality. Contents: Witten Laplacians Approach; Problems in Statistical Mechanics with Discrete Spins; Laplace Integrals and Transfer Operators; S

Quantum Bound to Chaos and the Semiclassical Limit

Science.gov (United States)

Kurchan, Jorge

2018-06-01

We discuss the quantum bound on chaos in the context of the free propagation of a particle in an arbitrarily curved surface at low temperatures. The semiclassical calculation of the Lyapunov exponent can be performed in much the same way as the corresponding one for the `Loschmidt echo'. The bound appears here as the impossibility to scatter a wave, by effect of the curvature, over characteristic lengths smaller than the deBroglie wavelength.

Cures for the shock instability: Development of a shock-stable Roe scheme

CERN Document Server

Kim, S S; Rho, O H; Kyu-Hong, S

2003-01-01

This paper deals with the development of an improved Roe scheme that is free from the shock instability and still preserves the accuracy and efficiency of the original Roe's Flux Difference Splitting (FDS). Roe's FDS is known to possess good accuracy but to suffer from the shock instability, such as the carbuncle phenomenon. As the first step towards a shock-stable scheme, Roe's FDS is compared with the HLLE scheme to identify the source of the shock instability. Through a linear perturbation analysis on the odd-even decoupling problem, damping characteristic is examined and Mach number-based functions f and g are introduced to balance damping and feeding rates, which leads to a shock-stable Roe scheme. In order to satisfy the conservation of total enthalpy, which is crucial in predicting surface heat transfer rate in high-speed steady flows, an analysis of dissipation mechanism in the energy equation is carried out to find out the error source and to make the proposed scheme preserve total enthalpy. By modif...

Particle on a torus knot: Constrained dynamics and semi-classical quantization in a magnetic field

Energy Technology Data Exchange (ETDEWEB)

Das, Praloy, E-mail: praloydasdurgapur@gmail.com; Pramanik, Souvik, E-mail: souvick.in@gmail.com; Ghosh, Subir, E-mail: subirghosh20@gmail.com

2016-11-15

Kinematics and dynamics of a particle moving on a torus knot poses an interesting problem as a constrained system. In the first part of the paper we have derived the modified symplectic structure or Dirac brackets of the above model in Dirac’s Hamiltonian framework, both in toroidal and Cartesian coordinate systems. This algebra has been used to study the dynamics, in particular small fluctuations in motion around a specific torus. The spatial symmetries of the system have also been studied. In the second part of the paper we have considered the quantum theory of a charge moving in a torus knot in the presence of a uniform magnetic field along the axis of the torus in a semiclassical quantization framework. We exploit the Einstein–Brillouin–Keller (EBK) scheme of quantization that is appropriate for multidimensional systems. Embedding of the knot on a specific torus is inherently two dimensional that gives rise to two quantization conditions. This shows that although the system, after imposing the knot condition reduces to a one dimensional system, even then it has manifested non-planar features which shows up again in the study of fractional angular momentum. Finally we compare the results obtained from EBK (multi-dimensional) and Bohr–Sommerfeld (single dimensional) schemes. The energy levels and fractional spin depend on the torus knot parameters that specifies its non-planar features. Interestingly, we show that there can be non-planar corrections to the planar anyon-like fractional spin.

Semiclassical expansions on and near caustics

International Nuclear Information System (INIS)

Meetz, K.

1984-09-01

We show that the standard WKB expansion can be generalized so that it reproduces the behavior of the wave function on and near a caustic in two-dimensional space time. The expansion is related to the unfolding polynomials of the elementary catastrophes occurring in two dimensions: the fold and the cusp catastrophe. The method determines control parameters and transport coefficients in a self-consistent way from differential equations and does not refer to the asymptotic expansion of Feynman path integrals. The lowest order equations are solved explicitly in terms of the multivalued classical action. The result is a generalized semiclassical approximation on and beyond a caustic. (orig.)

Semiclassical approach to black hole evaporation

International Nuclear Information System (INIS)

Lowe, D.A.

1993-01-01

Black hole evaporation may lead to massive or massless remnants, or naked singularities. This paper investigates this process in the context of two quite different two-dimensional black hole models. The first is the original Callan-Giddings-Harvey-Strominger (CGHS) model, the second is another two-dimensional dilaton-gravity model, but with properties much closer to physics in the real, four-dimensional, world. Numerical simulations are performed of the formation and subsequent evaporation of black holes and the results are found to agree qualitatively with the exactly solved modified CGHS models, namely, that the semiclassical approximation breaks down just before a naked singularity appears

Electron self-mass in the semiclassical limit

International Nuclear Information System (INIS)

Pradham, T.; Khare, A.

1978-01-01

The semiclassical limit of the electron self-mass, which is the first order term in an expansion of the exact Dyson self-mass in powers of h/2π, is calculated. The result is quadratically divergent in the limit of the cut-off radius tending to zero. It is noted that the present result is quantum mechanical in the same sense as any WKB result and is exact to all orders in e 2 , in contrast to the logarithmically divergent self-mass given by other resuls. (U.K.)

Introduction to geometric nonlinear control; Linearization, observability, decoupling

Energy Technology Data Exchange (ETDEWEB)

Respondek, W [Laboratoire de Mathematiques, INSA de Rouen (France)

2002-07-15

These notes are devoted to the problems of linearization, observability, and decoupling of nonlinear control systems. Together with notes of Bronislaw Jakubczyk in the same volume, they form an introduction to geometric methods in nonlinear control theory. In the first part we discuss equivalence of control systems. We consider various aspects of the problem: state-space and feedback equivalence, local and global equivalence, equivalence to linear and partially linear systems. In the second part we present the notion of observability and give a geometric rank condition for local observability and an algebraic characterization of local observability. We discuss unm observability, decompositions of non-observable systems, and properties of generic observable systems. In the third part we introduce the notion of invariant distributions and discuss disturbance decoupling and input-output decoupling. Many concepts and results are illustrated with examples. (author)

'Glocalization' versus Notions of Decoupling

DEFF Research Database (Denmark)

Jakobsen, Michael

2011-01-01

Discussing modes of political and/or economic decoupling in an era of economic globalization seems almost contradictory as the dominating keywords in the latter are increasing integration, interdependency and harmonization. For example, when looking towards the political realm it seems problemati...

Semi-classical quantization non-manifestly using the method of harmonic balance

International Nuclear Information System (INIS)

Stepanov, S.S.; Tutik, R.S.; Yaroshenko, A.P.; Schlippe, W. von.

1990-01-01

Based on the ideas of the harmonic balance method and h-expansion a semi-classical procedure for deriving approximations to the energy levels of one-dimensional quantum systems is developed. The procedure is applied to treat the perturbed oscillator potentials. 12 refs.; 2 tabs

Angular momentum projected semiclassics

International Nuclear Information System (INIS)

Hasse, R.W.

1986-10-01

By using angular momentum projected plane waves as wave functions, we derive semiclassical expressions for the single-particle propagator, the partition function, the nonlocal density matrix, the single-particle density and the one particle- one hole level density for fixed angular momentum and fixed z-component or summed over the z-components. Other quantities can be deduced from the propagator. In coordinate space (r, r') the relevant quantities depend on vertical stroker - r 3 vertical stroke instead of vertical stroker - r'vertical stroke and in Wigner space (R, P) they become proportional to the angular momentum constraints δ(vertical strokeRxPvertical stroke/ℎ - l) and δ((RxP) z /ℎ - m). As applications we calculate the single-particle and one particle- one hole level densities for harmonic oscillator and Hill-Wheeler box potentials and the imaginary part of the optical potential and its volume integral with an underlying harmonic oscillator potential and a zero range two-body interaction. (orig.)

Semiclassical description of resonant tunnel effect: bifurcations and periodic orbits in the resonant current

International Nuclear Information System (INIS)

Rouben, D.C.

1997-01-01

A semiclassical method for resonant tunneling in a quantum well in the presence of a magnetic field tilted with regard to an electric field is developed. In particular a semiclassical formula is derived for the total current of electrons after the second barrier of the quantum well. The contribution of the stable and unstable orbits is studied. It appears that the parameters which describe the classical chaos in the quantum well have an important effect on the tunneling current. A numerical experiment is led, the contributions to the current of some particular orbits are evaluated and the results are compared with those given by the quantum theory. (A.C.)

The recurrence coefficients of semi-classical Laguerre polynomials and the fourth Painlevé equation

Science.gov (United States)

Filipuk, Galina; Van Assche, Walter; Zhang, Lun

2012-05-01

We show that the coefficients of the three-term recurrence relation for orthogonal polynomials with respect to a semi-classical extension of the Laguerre weight satisfy the fourth Painlevé equation when viewed as functions of one of the parameters in the weight. We compare different approaches to derive this result, namely, the ladder operators approach, the isomonodromy deformations approach and combining the Toda system for the recurrence coefficients with a discrete equation. We also discuss a relation between the recurrence coefficients for the Freud weight and the semi-classical Laguerre weight and show how it arises from the Bäcklund transformation of the fourth Painlevé equation.

The recurrence coefficients of semi-classical Laguerre polynomials and the fourth Painlevé equation

International Nuclear Information System (INIS)

Filipuk, Galina; Van Assche, Walter; Zhang Lun

2012-01-01

We show that the coefficients of the three-term recurrence relation for orthogonal polynomials with respect to a semi-classical extension of the Laguerre weight satisfy the fourth Painlevé equation when viewed as functions of one of the parameters in the weight. We compare different approaches to derive this result, namely, the ladder operators approach, the isomonodromy deformations approach and combining the Toda system for the recurrence coefficients with a discrete equation. We also discuss a relation between the recurrence coefficients for the Freud weight and the semi-classical Laguerre weight and show how it arises from the Bäcklund transformation of the fourth Painlevé equation. (paper)

Semiclassical perturbation theory for diffraction in heavy atom surface scattering.

Science.gov (United States)

Miret-Artés, Salvador; Daon, Shauli; Pollak, Eli

2012-05-28

The semiclassical perturbation theory formalism of Hubbard and Miller [J. Chem. Phys. 78, 1801 (1983)] for atom surface scattering is used to explore the possibility of observation of heavy atom diffractive scattering. In the limit of vanishing ℏ the semiclassical theory is shown to reduce to the classical perturbation theory. The quantum diffraction pattern is sensitive to the characteristics of the beam of incoming particles. Necessary conditions for observation of quantum diffraction are derived for the angular width of the incoming beam. An analytic expression for the angular distribution as a function of the angular and momentum variance of the incoming beam is obtained. We show both analytically and through some numerical results that increasing the angular width of the incident beam leads to decoherence of the quantum diffraction peaks and one approaches the classical limit. However, the incoherence of the beam in the parallel direction does not destroy the diffraction pattern. We consider the specific example of Ar atoms scattered from a rigid LiF(100) surface.

Combinatorial theory of the semiclassical evaluation of transport moments. I. Equivalence with the random matrix approach

Energy Technology Data Exchange (ETDEWEB)

Berkolaiko, G., E-mail: berko@math.tamu.edu [Department of Mathematics, Texas A and M University, College Station, Texas 77843-3368 (United States); Kuipers, J., E-mail: Jack.Kuipers@physik.uni-regensburg.de [Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg (Germany)

2013-11-15

To study electronic transport through chaotic quantum dots, there are two main theoretical approaches. One involves substituting the quantum system with a random scattering matrix and performing appropriate ensemble averaging. The other treats the transport in the semiclassical approximation and studies correlations among sets of classical trajectories. There are established evaluation procedures within the semiclassical evaluation that, for several linear and nonlinear transport moments to which they were applied, have always resulted in the agreement with random matrix predictions. We prove that this agreement is universal: any semiclassical evaluation within the accepted procedures is equivalent to the evaluation within random matrix theory. The equivalence is shown by developing a combinatorial interpretation of the trajectory sets as ribbon graphs (maps) with certain properties and exhibiting systematic cancellations among their contributions. Remaining trajectory sets can be identified with primitive (palindromic) factorisations whose number gives the coefficients in the corresponding expansion of the moments of random matrices. The equivalence is proved for systems with and without time reversal symmetry.

Efficiency of Decoupled Farm Programs under Distortionary Taxation

OpenAIRE

GianCarlo Moschini; Paolo Sckokai

1994-01-01

When lump-sum taxation is not feasible, decoupled transfers to farmers (which require raising government revenue) will entail welfare loss somewhere in the economy. Assuming the government's objective is to assure a given welfare level for farmers, we show that when decoupling is possible, free trade is always superior to some tariff protection for a small country, even under Distortionary taxation. As expected, for a large country there is scope for an optimal tariff policy that improves the...

Evaluating Decoupling Process in OECD Countries: Case Study of Turkey

Science.gov (United States)

An, Nazan; Şengün Ucal, Meltem; Kurnaz, M. Levent

2017-04-01

Climate change is at the top of the present and future problems facing humanity. Climate change is now largely attributed to human activities and economic activities are the source of human activities that cause climate change by creating pressure on the environment. Providing the sustainability of resources for the future seems possible by reducing the pressure of these economic activities on the environment. Given the increasing population pressure and growth-focused economies, it is possible to say that achieving decoupling is not so easy on a global basis. It is known that there are some problems in developing countries especially in terms of accessing reliable data in transition and implementation process of decoupling. Developed countries' decoupling practices and proper calculation methods can also be a guide for developing countries. In this study, we tried to calculate the comparative decoupling index for OECD countries and Turkey in terms of data suitability, and we showed the differences between them. We tried to indicate the level of decoupling (weak, stable, strong) for each country. We think that the comparison of Turkey can be an example in terms of developing countries. Acknowledgement: This research has been supported by Bogazici University Research Fund Grant Number 12220.

Decoupling mechanisms-paying for conservation

Energy Technology Data Exchange (ETDEWEB)

Cross, P.S.

1993-07-15

In 1988, the National Association of Regulatory Utility Commissioners issued a policy statement that said [open quotes]ratemaking practices should align utilities' pursuit of profit with least-cost planning.[close quotes] This policy coincided with then-current thinkingg at a number of state commissions about the much-touted goal of encouraging utilities to invest in conservation, or demand-side management (DSM) programs, rather than in generating resources to meet system load requirements. Besides utility concerns about recovering conservation program investments, regulators also notices a built-in [open quotes]disincentive[close quotes] to investment in the traditional ratemaking format: If profit is tied to sales, then utilities will always shy away from aggressively promoting conservation. Or so the thinkin went. [open quotes]Decoupling mechanisms[close quotes] were born to remove this disincentive. A number of states have implemented these mechanisms, while several others are investigating the issue. One chief drawback of the mechanisms is that if sales go down, rates go up to cover the shortfall. (Of course, rates go down if sales exceed forecasted levels.) A major problem has been that rate increases have occurred at exactly the wrong time, during economic slowdowns when utilities are struggling to retain price-sensitive customers and residential ratepayers are least likely to bear with quiet stoicism the burden placed on family budgets. Decoupling is seen by some as a step backwards in the move to competitive regulatory reforms that seek to encourage utilities to behave like free-market companies. Indeed, the newest decoupling mechanisms face serious challenge.

Power-optimal force decoupling in a hybrid linear reluctance motor

NARCIS (Netherlands)

Overboom, T.T.; Smeets, J.P.C.; Jansen, J.W.; Lomonova, E.A.; Mavrudieva, D.

2015-01-01

This paper concerns the power-optimal decoupling of the propulsion and normal force created by a hybrid linear reluctance motor. The intrinsic limitations to the decoupling is addressed by the visualizing each force component with a quadric surface in the Euclidean space which is spanned by the

A Decoupling Control Algorithm for Unwinding Tension System Based on Active Disturbance Rejection Control

Directory of Open Access Journals (Sweden)

Shanhui Liu

2013-01-01

Full Text Available This paper presents a new control methodology based on active disturbance rejection control (ADRC for designing the tension decoupling controller of the unwinding system in a gravure printing machine. The dynamic coupling can be actively estimated and compensated in real time, which makes feedback control an ideal approach to designing the decoupling controller of the unwinding system. This feature is unique to ADRC. In this study, a nonlinear mathematical model is established according to the working principle of the unwinding system. A decoupling model is also constructed to determine the order and decoupling plant of the unwinding system. Based on the order and decoupling plant, an ADRC decoupling control methodology is designed to enhance the tension stability in the unwinding system. The effectiveness and capability of the proposed methodology are verified through simulation and experiments. The results show that the proposed strategy not only realises a decoupling control for the unwinding system but also has an effective antidisturbance capability and is robust.

Classical and semi-classical solutions of the Yang--Mills theory

International Nuclear Information System (INIS)

Jackiw, R.; Nohl, C.; Rebbi, C.

1977-12-01

This review summarizes what is known at present about classical solutions to Yang-Mills theory both in Euclidean and Minkowski space. The quantal meaning of these solutions is also discussed. Solutions in Euclidean space expose multiple vacua and tunnelling of the quantum theory. Those in Minkowski space-time provide a semi-classical spectrum for a conformal generator

Decoupling as a mechanism of change in mindfulness and acceptance: a literature review.

Science.gov (United States)

Levin, Michael E; Luoma, Jason B; Haeger, Jack A

2015-11-01

A growing body of research within the acceptance and mindfulness-based therapies suggests that these treatments may function in part by reducing or eliminating (i.e., decoupling) the normative relationships between internal experiences and other internal/overt behavior. Examples of decoupling effects found in this review include reduced relationships between urges to smoke and smoking behavior, between dysphoric mood and depressive cognitions, and between pain intensity and persistence in a painful task. A literature review identified 44 studies on acceptance and mindfulness that demonstrated decoupling effects. Overall, preliminary evidence for decoupling effects were found across a broad range of problem areas, including substance abuse, depression, eating disorders, overeating, chronic pain, anxiety, relationships, anger, avoidance behavior, and self-harm, with the strongest evidence currently available in the area of substance abuse. However, the review also notes a general lack of replication studies on decoupling effects and the need for more well-powered and controlled research testing specific decoupling hypotheses. © The Author(s) 2015.

Decoupling Control Design for the Module Suspension Control System in Maglev Train

Directory of Open Access Journals (Sweden)

Guang He

2015-01-01

Full Text Available An engineering oriented decoupling control method for the module suspension system is proposed to solve the coupling issues of the two levitation units of the module in magnetic levitation (maglev train. According to the format of the system transfer matrix, a modified adjoint transfer matrix based decoupler is designed. Then, a compensated controller is obtained in the light of a desired close loop system performance. Optimization between the performance index and robustness index is also carried out to determine the controller parameters. However, due to the high orders and complexity of the obtained resultant controller, model reduction method is adopted to get a simplified controller with PID structure. Considering the modeling errors of the module suspension system as the uncertainties, experiments have been performed to obtain the weighting function of the system uncertainties. By using this, the robust stability of the decoupled module suspension control system is checked. Finally, the effectiveness of the proposed decoupling design method is validated by simulations and physical experiments. The results illustrate that the presented decoupling design can result in a satisfactory decoupling and better dynamic performance, especially promoting the reliability of the suspension control system in practical engineering application.

A wave propagation matrix method in semiclassical theory

International Nuclear Information System (INIS)

Lee, S.Y.; Takigawa, N.

1977-05-01

A wave propagation matrix method is used to derive the semiclassical formulae of the multiturning point problem. A phase shift matrix and a barrier transformation matrix are introduced to describe the processes of a particle travelling through a potential well and crossing a potential barrier respectively. The wave propagation matrix is given by the products of phase shift matrices and barrier transformation matrices. The method to study scattering by surface transparent potentials and the Bloch wave in solids is then applied

State policy change: Revenue decoupling in the electricity market

Science.gov (United States)

McNeil, Kytson L.

The study seeks to answer the question, why are states adopting revenue decoupling in the electricity market, by investigating the relationship between policy adoption and attributes of the electricity market, the structure of the state utility commissions, and the political climate of the state. The study examines the period 1978-2008. Two econometric models, the marginal risk set model and the conditional risk set model, are estimated to predict the influence of covariates on the probability of the state adopting revenue decoupling in the electricity market. The models are both variants of the Cox proportional hazard model and use different underlying assumptions about the nature of adoption of revenue decoupling and when the states are considered to be at risk of adoption. Results suggest that market attributes, such as the source of electricity generation in the state, state energy intensity, and the distribution of non-public and public utilities, significantly influence the adoption of the policy. Also, the method of selecting commissioners and the party affiliation of elected officials in the state are important factors. The study concludes by suggestions to improve the implementation and evaluation of revenue decoupling in the electricity markets.

Semiclassical scar functions in phase space

International Nuclear Information System (INIS)

Rivas, Alejandro M F

2007-01-01

We develop a semiclassical approximation for the scar function in the Weyl-Wigner representation in the neighborhood of a classically unstable periodic orbit of chaotic two-dimensional systems. The prediction of hyperbolic fringes, asymptotic to the stable and unstable manifolds, is verified computationally for a (linear) cat map, after the theory is adapted to a discrete phase space appropriate to a quantized torus. Characteristic fringe patterns can be distinguished even for quasi-energies where the fixed point is not Bohr-quantized. Also the patterns are highly localized in the neighborhood of the periodic orbit and along its stable and unstable manifolds without any long distance patterns that appear for the case of the spectral Wigner function

Semiclassical analysis spectral correlations in mesoscopic systems

International Nuclear Information System (INIS)

Argaman, N.; Imry, Y.; Smilansky, U.

1991-07-01

We consider the recently developed semiclassical analysis of the quantum mechanical spectral form factor, which may be expressed in terms of classically defiable properties. When applied to electrons whose classical behaviour is diffusive, the results of earlier quantum mechanical perturbative derivations, which were developed under a different set of assumptions, are reproduced. The comparison between the two derivations shows that the results depends not on their specific details, but to a large extent on the principle of quantum coherent superposition, and on the generality of the notion of diffusion. The connection with classical properties facilitates application to many physical situations. (author)

Various semiclassical limits of torus conformal blocks

Energy Technology Data Exchange (ETDEWEB)

Alkalaev, Konstantin [I.E. Tamm Department of Theoretical Physics, P.N. Lebedev Physical Institute,Leninsky ave. 53, Moscow, 119991 (Russian Federation); Department of General and Applied Physics, Moscow Institute of Physics and Technology,Institutskiy per. 7, Dolgoprudnyi, Moscow region, 141700 (Russian Federation); Geiko, Roman [Mathematics Department, National Research University Higher School of Economics,Usacheva str. 6, Moscow, 119048 (Russian Federation); Rappoport, Vladimir [I.E. Tamm Department of Theoretical Physics, P.N. Lebedev Physical Institute,Leninsky ave. 53, Moscow, 119991 (Russian Federation); Department of Quantum Physics, Institute for Information Transmission Problems,Bolshoy Karetny per. 19, Moscow, 127994 (Russian Federation)

2017-04-12

We study four types of one-point torus blocks arising in the large central charge regime. There are the global block, the light block, the heavy-light block, and the linearized classical block, according to different regimes of conformal dimensions. It is shown that the blocks are not independent being connected to each other by various links. We find that the global, light, and heavy-light blocks correspond to three different contractions of the Virasoro algebra. Also, we formulate the c-recursive representation of the one-point torus blocks which is relevant in the semiclassical approximation.

FAST AUTOMATED DECOUPLING AT RHIC

International Nuclear Information System (INIS)

BEEBE-WANG, J.J.

2005-01-01

Coupling correction is essential for the operational performance of RHIC. The independence of the transverse degrees of freedom makes diagnostics and tune control easier, and it is advantageous to operate an accelerator close to the coupling resonance to minimize nearby nonlinear sidebands. An automated coupling correction application iDQmini has been developed for RHIC routine operations. The application decouples RHIC globally by minimizing the tune separation through finding the optimal settings of two orthogonal skew quadrupole families. The program iDQmini provides options of automatic, semi-automatic and manual decoupling operations. It accesses tune information from all RHIC tune measurement systems: the PLL (phase lock loop), the high frequency Schottky system and the tune meter. It also supplies tune and skew quadrupole scans, finding the minimum tune separation, display the real time results and interface with the RHIC control system. We summarize the capabilities of the coupling correction application iDQmini, and discuss the operational protections incorporated in the program

Deep-subwavelength Decoupling for MIMO Antennas in Mobile Handsets with Singular Medium.

Science.gov (United States)

Xu, Su; Zhang, Ming; Wen, Huailin; Wang, Jun

2017-09-22

Decreasing the mutual coupling between Multi-input Multi-output (MIMO) antenna elements in a mobile handset and achieving a high data rate is a challenging topic as the 5 th -generation (5G) communication age is coming. Conventional decoupling components for MIMO antennas have to be re-designed when the geometries or frequencies of antennas have any adjustment. In this paper, we report a novel metamaterial-based decoupling strategy for MIMO antennas in mobile handsets with wide applicability. The decoupling component is made of subwavelength metal/air layers, which can be treated as singular medium over a broad frequency band. The flexible applicable property of the decoupling strategy is verified with different antennas over different frequency bands with the same metamaterial decoupling element. Finally, 1/100-wavelength 10-dB isolation is demonstrated for a 24-element MIMO antenna in mobile handsets over the frequency band from 4.55 to 4.75 GHz.

Quantifying the ice-albedo feedback through decoupling

Science.gov (United States)

Kravitz, B.; Rasch, P. J.

2017-12-01

The ice-albedo feedback involves numerous individual components, whereby warming induces sea ice melt, inducing reduced surface albedo, inducing increased surface shortwave absorption, causing further warming. Here we attempt to quantify the sea ice albedo feedback using an analogue of the "partial radiative perturbation" method, but where the governing mechanisms are directly decoupled in a climate model. As an example, we can isolate the insulating effects of sea ice on surface energy and moisture fluxes by allowing sea ice thickness to change but fixing Arctic surface albedo, or vice versa. Here we present results from such idealized simulations using the Community Earth System Model in which individual components are successively fixed, effectively decoupling the ice-albedo feedback loop. We isolate the different components of this feedback, including temperature change, sea ice extent/thickness, and air-sea exchange of heat and moisture. We explore the interactions between these different components, as well as the strengths of the total feedback in the decoupled feedback loop, to quantify contributions from individual pieces. We also quantify the non-additivity of the effects of the components as a means of investigating the dominant sources of nonlinearity in the ice-albedo feedback.

Contrasting Cloud Composition Between Coupled and Decoupled Marine Boundary Layer Clouds

Science.gov (United States)

WANG, Z.; Mora, M.; Dadashazar, H.; MacDonald, A.; Crosbie, E.; Bates, K. H.; Coggon, M. M.; Craven, J. S.; Xian, P.; Campbell, J. R.; AzadiAghdam, M.; Woods, R. K.; Jonsson, H.; Flagan, R. C.; Seinfeld, J.; Sorooshian, A.

2016-12-01

Marine stratocumulus clouds often become decoupled from the vertical layer immediately above the ocean surface. This study contrasts cloud chemical composition between coupled and decoupled marine stratocumulus clouds. Cloud water and droplet residual particle composition were measured in clouds off the California coast during three airborne experiments in July-August of separate years (E-PEACE 2011, NiCE 2013, BOAS 2015). Decoupled clouds exhibited significantly lower overall mass concentrations in both cloud water and droplet residual particles, consistent with reduced cloud droplet number concentration and sub-cloud aerosol (Dp > 100 nm) number concentration, owing to detachment from surface sources. Non-refractory sub-micrometer aerosol measurements show that coupled clouds exhibit higher sulfate mass fractions in droplet residual particles, owing to more abundant precursor emissions from the ocean and ships. Consequently, decoupled clouds exhibited higher mass fractions of organics, nitrate, and ammonium in droplet residual particles, owing to effects of long-range transport from more distant sources. Total cloud water mass concentration in coupled clouds was dominated by sodium and chloride, and their mass fractions and concentrations exceeded those in decoupled clouds. Conversely, with the exception of sea salt constituents (e.g., Cl, Na, Mg, K), cloud water mass fractions of all species examined were higher in decoupled clouds relative to coupled clouds. These results suggest that an important variable is the extent to which clouds are coupled to the surface layer when interpreting microphysical data relevant to clouds and aerosol particles.

Semiclassical Weyl Formula for a Class of Weakly Regular Elliptic Operators

Energy Technology Data Exchange (ETDEWEB)

Zielinski, Lech [Universite du Littoral, LMPA, Centre Mi-Voix (France)], E-mail: Lech.Zielinski@lmpa.univ-littoral.fr

2006-02-15

We investigate the semiclassical Weyl formula describing the asymptotic behaviour of the counting function for the number of eigenvalues in the case of self-adjoint elliptic differential operators satisfying weak regularity hypotheses. We consider symbols with possible critical points and with coefficients which have Hoelder continuous derivatives of first order.

Semiclassical Weyl Formula for a Class of Weakly Regular Elliptic Operators

International Nuclear Information System (INIS)

Zielinski, Lech

2006-01-01

We investigate the semiclassical Weyl formula describing the asymptotic behaviour of the counting function for the number of eigenvalues in the case of self-adjoint elliptic differential operators satisfying weak regularity hypotheses. We consider symbols with possible critical points and with coefficients which have Hoelder continuous derivatives of first order

Semiclassical calculation for collision induced dissociation. III. Restricted two dimensional Morse oscillator model

International Nuclear Information System (INIS)

Rusinek, I.

1980-01-01

A semiclassical procedure previously used for collinear CID calculations is applied to the perpendicular collisions (2D, no rotation, zero impact parameter) of a Morse homonuclear diatomic molecule and an atom, interacting via an exponential repulsive potential. Values of the dissociation probability (P/sup diss/) are given as a function of total energy (E/sub t/) and initial vibrational state (n 1 =0,1,3,5) for a system with three identical masses. The results are compared with the P/sup diss/ previously reported for an identical one dimensional system. We find: (a) quasiclassical P/sup diss/ that are a good approximation to the semiclassical ones, if CID is classically allowed, (b) vibrational enhancement of CID, and (c) energetic thresholds for dissociation similar to the ones found in the collinear case

Semiclassical and quantum motions on the non-commutative plane

International Nuclear Information System (INIS)

Baldiotti, M.C.; Gazeau, J.P.; Gitman, D.M.

2009-01-01

We study the canonical and the coherent state quantizations of a particle moving in a magnetic field on the non-commutative plane. Using a θ-modified action, we perform the canonical quantization and analyze the gauge dependence of the theory. We compare coherent states quantizations obtained through Malkin-Man'ko states and circular squeezed states. The relation between these states and the 'classical' trajectories is investigated, and we present numerical explorations of some semiclassical quantities.

Decoupling - past trends and prospects for the future[Decoupling of economic growth and environmental impacts

Energy Technology Data Exchange (ETDEWEB)

Azar, Christian; Holmberg, John; Karlsson, Sten [Chalmers Univ. of Tech., Goeteborg (SE). Physical Resource Theory] [and others

2002-05-01

There are widespread demands in society for a dematerialization or decoupling of economic growth from environmental impact. Calls are being made for eco-efficiency and/or an improvement of resource efficiency by a factor of 10. At the same time, some analysts claim there is an environmental Kuznet's curve that supposedly implies a fall in environmental pressure, as we get richer. An improvement in the environmental situation has already been observed in many cases, but there are also many areas where the situation is deteriorating. The purpose of this report is to summarize some key trends of energy and material use over time in both developing and developed countries. We have focused on Sweden, the EU, Japan and the USA as well as China, India and Brazil. The main findings in this paper can be summarized as follows: Absolute emissions of CO{sub 2} have been increasing in most countries and periods studied. Some countries have experienced periods with constant or even falling emissions, but this is the exception rather than the rule, and it has been triggered by oil crises or economic recessions. In order to stabilize atmospheric CO{sub 2} concentrations, CO{sub 2} emissions have to be decoupled much more rapidly than has been the case in the past, and it is extremely unlikely that this will happen by itself. There was some decoupling of CO{sub 2} emissions from GDP in the major economies of the world from 1970 to 1998 in the EU, Japan and the US as well as in some major developing countries such as China, although India actually increased its emissions over GDP by 1.4 per cent/yr over this period. The drop in CO{sub 2} intensity has been prompted by some decoupling of energy from GDP and CO{sub 2} from energy, the latter being a consequence of an increased use of natural gas and nuclear power. In the South, fossil CO 2 per energy tends to increase from rather low levels. With industrialization, the proportion of biomass drops and the proportion of fossil

On semiclassical analysis of pure spinor superstring in an AdS{sub 5} x S{sup 5} background

Energy Technology Data Exchange (ETDEWEB)

Aisaka, Yuri [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Sao Paulo State Univ. (Brazil). Inst. de Fisica Teorica; Ibiapina Bevilaqua, L. [Univ. Federal do Rio Grande do Norte, Natal (Brazil). Esola de Ciencias e Tecnologia; Vallilo, Brenno C. [Santiago Univ. (Chile). Dept. de Ciencias Fisicas

2012-06-15

Relation between semiclassical analyses of Green-Schwarz and pure spinor formalisms in an AdS{sub 5} x S{sup 5} background is clarified. It is shown that the two formalisms have identical semiclassical partition functions for a simple family of classical solutions. It is also shown that, when the classical string is furthermore rigid, this in turn implies that the two formalisms predict the same one-loop corrections to spacetime energies.

On the semiclassical description of shell effects in finite fermion systems; Zur semiklassischen Beschreibung von Schaleneffekten in endlichen Fermionensystemen

Energy Technology Data Exchange (ETDEWEB)

Meier, Peter Johann

2009-09-19

An extension of Gutzwiller's semiclassical ''Periodic Orbit Theory'' for systems with continous symmetries is used to predict the ground state deformations of simple metal clusters which are described in the framework of the shell model. Restrictions of the theory caused by the semiclassical approximations are discussed and possible generalizations are demonstrated. The results are compared with corresponding quantum mechanical calculations. (orig.)

A closer look at non-decoupling D-Terms

CERN Document Server

Staub, Florian

2016-01-01

Non-Decoupling D-Terms are an attractive possibility to enhance the tree-level mass of the standard model like Higgs boson in supersymmetric models. We discuss here for the case of a new Abelian gauge group two effects usually neglected in literature: (i) the size of the additional radiative corrections to the Higgs mass due to the presence of the new gauge coupling, and (ii) the impact of gauge kinetic mixing. It is shown that both effects reduce to some extent the positive effect of the non-decoupling D-terms on the Higgs mass.

Influence of semiclassical plasma on the energy levels and radiative transitions in highly charged ions★

Science.gov (United States)

Hu, Hong-Wei; Chen, Zhan-Bin; Chen, Wen-Cong; Liu, Xiao-Bin; Fu, Nian; Wang, Kai

2017-11-01

Considering the quantum effects of diffraction and the collective screening effects, the potential of test charge in semiclassical plasmas is derived. It is generalized exponential screened Coulomb potential. Using the Ritz variational method incorporating this potential, the effects of semiclassical plasma on the energy levels and radiative transitions are investigated systematically, taking highly charged H-like ion as an example. The Debye plasma model is also employed for comparison purposes. Comparisons and analysis are made between these two sets of results and the differences are discussed. Contribution to the Topical Issue "Atomic and Molecular Data and their Applications", edited by Gordon W.F. Drake, Jung-Sik Yoon, Daiji Kato, Grzegorz Karwasz.

Semiclassical calculation for collision induced dissociation. II. Morse oscillator model

International Nuclear Information System (INIS)

Rusinek, I.; Roberts, R.E.

1978-01-01

A recently developed semiclassical procedure for calculating collision induced dissociation probabilities P/sup diss/ is applied to the collinear collision between a particle and a Morse oscillator diatomic. The particle--diatom interaction is described with a repulsive exponential potential function. P/sup diss/ is reported for a system of three identical particles, as a function of collision energy E/sub t/ and initial vibrational state of the diatomic n 1 . The results are compared with the previously reported values for the collision between a particle and a truncated harmonic oscillator. The two studies show similar features, namely: (a) there is an oscillatory structure in the P/sup diss/ energy profiles, which is directly related to n 1 ; (b) P/sup diss/ becomes noticeable (> or approx. =10 -3 ) for E/sub t/ values appreciably higher than the energetic threshold; (c) vibrational enhancement (inhibition) of collision induced dissociation persists at low (high) energies; and (d) good agreement between the classical and semiclassical results is found above the classical dynamic threshold. Finally, the convergence of P/sup diss/ for increasing box length is shown to be rapid and satisfactory

On the Application of Stark Broadening Data Determined with a Semiclassical Perturbation Approach

Directory of Open Access Journals (Sweden)

Milan S. Dimitrijević

2014-08-01

Full Text Available The significance of Stark broadening data for problems in astrophysics, physics, as well as for technological plasmas is discussed and applications of Stark broadening parameters calculated using a semiclassical perturbation method are analyzed.

Decoupling Analysis of China’s Product Sector Output and Its Embodied Carbon Emissions—An Empirical Study Based on Non-Competitive I-O and Tapio Decoupling Model

Directory of Open Access Journals (Sweden)

Jianbo Hu

2017-05-01

Full Text Available This paper uses the non-competitive I-O model and the Tapio decoupling model to comprehensively analyze the decoupling relationship between the output of the product sector in China and its embodied carbon emissions under trade openness. For this purpose, the Chinese input and output data in 2002, 2005, 2007, 2010, and 2012 are used. This approach is beneficial to identify the direct mechanism for the increased carbon emission in China from a micro perspective and provides a new perspective for the subsequent study about low-carbon economy. The obtained empirical results are as follows: (1 From overall perspective, the decoupling elasticity between the output of the product sector and its embodied carbon emissions decreased. Output and embodied carbon emissions showed a growth link from 2002 to 2005 and a weak decoupling relationship for the rest of the study period. (2 Among the 28 industries in the product sector, the increased growth rate of output in more and more product sectors was no longer accompanied by large CO2 emissions. The number of industries with strong decoupling relationships between output and embodied carbon emissions increased. (3 From the perspective of three industries, the output and embodied carbon emissions in the second and third industries exhibited a growth link only from 2002 to 2005; the three industries presented weak or strong decoupling for the rest of the study period. Through empirical analysis, this paper mainly through the construction of ecological and environmental protection of low carbon agriculture, low carbon cycle industrial system, as well as intensive and efficient service industry to reduce the carbon emissions of China’s product sector.

Semiclassical Loop Quantum Gravity and Black Hole Thermodynamics

Directory of Open Access Journals (Sweden)

Arundhati Dasgupta

2013-02-01

Full Text Available In this article we explore the origin of black hole thermodynamics using semiclassical states in loop quantum gravity. We re-examine the case of entropy using a density matrix for a coherent state and describe correlations across the horizon due to SU(2 intertwiners. We further show that Hawking radiation is a consequence of a non-Hermitian term in the evolution operator, which is necessary for entropy production or depletion at the horizon. This non-unitary evolution is also rooted in formulations of irreversible physics.

Numerical approaches to complex quantum, semiclassical and classical systems

Energy Technology Data Exchange (ETDEWEB)

Schubert, Gerald

2008-11-03

In this work we analyse the capabilities of several numerical techniques for the description of different physical systems. Thereby, the considered systems range from quantum over semiclassical to classical and from few- to many-particle systems. In chapter 1 we investigate the behaviour of a single quantum particle in the presence of an external disordered background (static potentials). Starting from the quantum percolation problem, we address the fundamental question of a disorder induced (Anderson-) transition from extended to localised single-particle eigenstates. Distinguishing isolating from conducting states by applying a local distribution approach for the local density of states (LDOS), we detect the quantum percolation threshold in two- and three-dimensions. Extending the quantum percolation model to a quantum random resistor model, we comment on the possible relevance of our results to the influence of disorder on the conductivity in graphene sheets. For the calculation of the LDOS as well as for the Chebyshev expansion of the time evolution operator, the kernel polynomial method (KPM) is the key numerical technique. In chapter 2 we examine how a single quantum particle is influenced by retarded bosonic fields that are inherent to the system. Within the Holstein model, these bosonic degrees of freedom (phonons) give rise to an infinite dimensional Hilbert space, posing a true many-particle problem. Constituting a minimal model for polaron formation, the Holstein model allows us to study the optical absorption and activated transport in polaronic systems. Using a two-dimensional variant of the KPM, we calculate for the first time quasi-exactly the optical absorption and dc-conductivity as a function of temperature. In chapter 3 we come back to the time evolution of a quantum particle in an external, static potential and investigate the capability of semiclassical approximations to it. We address basic quantum effects as tunneling, interference and

Numerical approaches to complex quantum, semiclassical and classical systems

International Nuclear Information System (INIS)

Schubert, Gerald

2008-01-01

In this work we analyse the capabilities of several numerical techniques for the description of different physical systems. Thereby, the considered systems range from quantum over semiclassical to classical and from few- to many-particle systems. In chapter 1 we investigate the behaviour of a single quantum particle in the presence of an external disordered background (static potentials). Starting from the quantum percolation problem, we address the fundamental question of a disorder induced (Anderson-) transition from extended to localised single-particle eigenstates. Distinguishing isolating from conducting states by applying a local distribution approach for the local density of states (LDOS), we detect the quantum percolation threshold in two- and three-dimensions. Extending the quantum percolation model to a quantum random resistor model, we comment on the possible relevance of our results to the influence of disorder on the conductivity in graphene sheets. For the calculation of the LDOS as well as for the Chebyshev expansion of the time evolution operator, the kernel polynomial method (KPM) is the key numerical technique. In chapter 2 we examine how a single quantum particle is influenced by retarded bosonic fields that are inherent to the system. Within the Holstein model, these bosonic degrees of freedom (phonons) give rise to an infinite dimensional Hilbert space, posing a true many-particle problem. Constituting a minimal model for polaron formation, the Holstein model allows us to study the optical absorption and activated transport in polaronic systems. Using a two-dimensional variant of the KPM, we calculate for the first time quasi-exactly the optical absorption and dc-conductivity as a function of temperature. In chapter 3 we come back to the time evolution of a quantum particle in an external, static potential and investigate the capability of semiclassical approximations to it. We address basic quantum effects as tunneling, interference and

A study of the relationship between the semi-classical and the generator coordinate methods

International Nuclear Information System (INIS)

Passos, E.J.V. de; Souza Cruz, F.F. de.

Using a very simple type of wave-packet which is obtained by letting unitary displacement operators having as generators canonical operators Q and P in the many-body Hilbert space act on a reference state, the relatinship between the semi-classical and the generator coordinate methods is investigated. The semi-classical method is based on the time-dependent variational principle whereas in the generator coordinate method the wave-packets are taken as generator states. To establish the equivalence of the two-methods, the concept of redundancy of the wave-packet and the importance of the zero-point energy effects are examined in detail, using tools developed in previous works. A numerical application to the case of the Goldhaber-Teller mode in 4 He is made. (Author) [pt

SAM revisited: uniform semiclassical approximation with absorption

International Nuclear Information System (INIS)

Hussein, M.S.; Pato, M.P.

1986-01-01

The uniform semiclassical approximation is modified to take into account strong absorption. The resulting theory, very similar to the one developed by Frahn and Gross is used to discuss heavy-ion elastic scattering at intermediate energies. The theory permits a reasonably unambiguos separation of refractive and diffractive effects. The systems 12 C+ 12 C and 12 C+ 16 O, which seem to exhibit a remnant of a nuclear rainbow at E=20 Mev/N, are analysed with theory which is built directly on a model for the S-matrix. Simple relations between the fit S-matrix and the underlying complex potential are derived. (Author) [pt

Semiclassical investigation of the revival phenomena in a one-dimensional system

International Nuclear Information System (INIS)

Wang Zhexian; Heller, Eric J

2009-01-01

In a quantum revival, a localized wave packet re-forms or 'revives' into a compact reincarnation of itself long after it has spread in an unruly fashion over a region restricted only by the potential energy. This is a purely quantum phenomenon, which has no classical analog. Quantum revival and Anderson localization are members of a small class of subtle interference effects resulting in a quantum distribution radically different from the classical after long time evolution under classically nonlinear evolution. However, it is not clear that semiclassical methods, which start with the classical density and add interference effects, are in fact capable of capturing the revival phenomenon. Here we investigate two different one-dimensional systems, the infinite square well and Morse potential. In both the cases, after a long time the underlying classical manifolds are spread rather uniformly over phase space and are correspondingly spread in coordinate space, yet the semiclassical amplitudes are able to destructively interfere over most of coordinate space and constructively interfere in a small region, correctly reproducing a quantum revival. Further implications of this ability are discussed

Semiclassical investigation of the revival phenomena in a one-dimensional system

Energy Technology Data Exchange (ETDEWEB)

Wang Zhexian [Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Heller, Eric J [Department of Physics and Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138 (United States)

2009-07-17

In a quantum revival, a localized wave packet re-forms or 'revives' into a compact reincarnation of itself long after it has spread in an unruly fashion over a region restricted only by the potential energy. This is a purely quantum phenomenon, which has no classical analog. Quantum revival and Anderson localization are members of a small class of subtle interference effects resulting in a quantum distribution radically different from the classical after long time evolution under classically nonlinear evolution. However, it is not clear that semiclassical methods, which start with the classical density and add interference effects, are in fact capable of capturing the revival phenomenon. Here we investigate two different one-dimensional systems, the infinite square well and Morse potential. In both the cases, after a long time the underlying classical manifolds are spread rather uniformly over phase space and are correspondingly spread in coordinate space, yet the semiclassical amplitudes are able to destructively interfere over most of coordinate space and constructively interfere in a small region, correctly reproducing a quantum revival. Further implications of this ability are discussed.

Semiclassical investigation of the revival phenomena in a one-dimensional system

Science.gov (United States)

Wang, Zhe-xian; Heller, Eric J.

2009-07-01

In a quantum revival, a localized wave packet re-forms or 'revives' into a compact reincarnation of itself long after it has spread in an unruly fashion over a region restricted only by the potential energy. This is a purely quantum phenomenon, which has no classical analog. Quantum revival and Anderson localization are members of a small class of subtle interference effects resulting in a quantum distribution radically different from the classical after long time evolution under classically nonlinear evolution. However, it is not clear that semiclassical methods, which start with the classical density and add interference effects, are in fact capable of capturing the revival phenomenon. Here we investigate two different one-dimensional systems, the infinite square well and Morse potential. In both the cases, after a long time the underlying classical manifolds are spread rather uniformly over phase space and are correspondingly spread in coordinate space, yet the semiclassical amplitudes are able to destructively interfere over most of coordinate space and constructively interfere in a small region, correctly reproducing a quantum revival. Further implications of this ability are discussed.

Stochastic semi-classical description of sub-barrier fusion reactions

Directory of Open Access Journals (Sweden)

Ayik Sakir

2011-10-01

Full Text Available A semi-classical method that incorporates the quantum effects of the low-lying vibrational modes is applied to fusion reactions. The quantum effect is simulated by stochastic sampling of initial zero-point fluctuations of the surface modes. In this model, dissipation of the relative energy into non-collective excitations of nuclei can be included straightforwardly. The inclusion of dissipation is shown to increase the agreement with the fusion cross section data of Ni isotopes.

Semiclassical and quantum motions on the non-commutative plane

Energy Technology Data Exchange (ETDEWEB)

Baldiotti, M.C., E-mail: baldiott@fma.if.usp.b [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318-CEP, 05315-970 Sao Paulo, S.P. (Brazil); Gazeau, J.P., E-mail: gazeau@apc.univ-paris7.f [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318-CEP, 05315-970 Sao Paulo, S.P. (Brazil); Gitman, D.M., E-mail: gitman@dfn.if.usp.b [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318-CEP, 05315-970 Sao Paulo, S.P. (Brazil)

2009-10-19

We study the canonical and the coherent state quantizations of a particle moving in a magnetic field on the non-commutative plane. Using a theta-modified action, we perform the canonical quantization and analyze the gauge dependence of the theory. We compare coherent states quantizations obtained through Malkin-Man'ko states and circular squeezed states. The relation between these states and the 'classical' trajectories is investigated, and we present numerical explorations of some semiclassical quantities.

Using lagged dependence to identify (de)coupled surface and subsurface soil moisture values

Science.gov (United States)

Carranza, Coleen D. U.; van der Ploeg, Martine J.; Torfs, Paul J. J. F.

2018-04-01

Recent advances in radar remote sensing popularized the mapping of surface soil moisture at different spatial scales. Surface soil moisture measurements are used in combination with hydrological models to determine subsurface soil moisture values. However, variability of soil moisture across the soil column is important for estimating depth-integrated values, as decoupling between surface and subsurface can occur. In this study, we employ new methods to investigate the occurrence of (de)coupling between surface and subsurface soil moisture. Using time series datasets, lagged dependence was incorporated in assessing (de)coupling with the idea that surface soil moisture conditions will be reflected at the subsurface after a certain delay. The main approach involves the application of a distributed-lag nonlinear model (DLNM) to simultaneously represent both the functional relation and the lag structure in the time series. The results of an exploratory analysis using residuals from a fitted loess function serve as a posteriori information to determine (de)coupled values. Both methods allow for a range of (de)coupled soil moisture values to be quantified. Results provide new insights into the decoupled range as its occurrence among the sites investigated is not limited to dry conditions.

Li-air batteries: Decouple to stabilize

Science.gov (United States)

Xu, Ji-Jing; Zhang, Xin-Bo

2017-09-01

The utilization of porous carbon cathodes in lithium-air batteries is hindered by their severe decomposition during battery cycling. Now, dual redox mediators are shown to decouple the complex electrochemical reactions at the cathode, avoiding cathode passivation and decomposition.

DQ reference frame modeling and control of single-phase active power decoupling circuits

DEFF Research Database (Denmark)

Tang, Yi; Qin, Zian; Blaabjerg, Frede

2015-01-01

. This paper presents the dq synchronous reference frame modeling of single-phase power decoupling circuits and a complete model describing the dynamics of dc-link ripple voltage is presented. The proposed model is universal and valid for both inductive and capacitive decoupling circuits, and the input...... of decoupling circuits can be either dependent or independent of its front-end converters. Based on this model, a dq synchronous reference frame controller is designed which allows the decoupling circuit to operate in two different modes because of the circuit symmetry. Simulation and experimental results...... are presented to verify the effectiveness of the proposed modeling and control method....

Semiclassical magnetotransport in strongly spin-orbit coupled Rashba two-dimensional electron systems

Science.gov (United States)

Xiao, Cong; Li, Dingping

2016-06-01

Semiclassical magnetoelectric and magnetothermoelectric transport in strongly spin-orbit coupled Rashba two-dimensional electron systems is investigated. In the presence of a perpendicular classically weak magnetic field and short-range impurity scattering, we solve the linearized Boltzmann equation self-consistently. Using the solution, it is found that when Fermi energy E F locates below the band crossing point (BCP), the Hall coefficient is a nonmonotonic function of electron density n e and not inversely proportional to n e. While the magnetoresistance (MR) and Nernst coefficient vanish when E F locates above the BCP, non-zero MR and enhanced Nernst coefficient emerge when E F decreases below the BCP. Both of them are nonmonotonic functions of E F below the BCP. The different semiclassical magnetotransport behaviors between the two sides of the BCP can be helpful to experimental identifications of the band valley regime and topological change of Fermi surface in considered systems.

Semiclassical magnetotransport in strongly spin–orbit coupled Rashba two-dimensional electron systems

International Nuclear Information System (INIS)

Xiao, Cong; Li, Dingping

2016-01-01

Semiclassical magnetoelectric and magnetothermoelectric transport in strongly spin–orbit coupled Rashba two-dimensional electron systems is investigated. In the presence of a perpendicular classically weak magnetic field and short-range impurity scattering, we solve the linearized Boltzmann equation self-consistently. Using the solution, it is found that when Fermi energy E F locates below the band crossing point (BCP), the Hall coefficient is a nonmonotonic function of electron density n e and not inversely proportional to n e . While the magnetoresistance (MR) and Nernst coefficient vanish when E F locates above the BCP, non-zero MR and enhanced Nernst coefficient emerge when E F decreases below the BCP. Both of them are nonmonotonic functions of E F below the BCP. The different semiclassical magnetotransport behaviors between the two sides of the BCP can be helpful to experimental identifications of the band valley regime and topological change of Fermi surface in considered systems. (paper)

Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

DEFF Research Database (Denmark)

Christensen, Rasmus Bjerregaard; Lu, Jing Tao; Hedegard, Per

2016-01-01

We employ a semi-classical Langevin approach to study current-induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon. All parameters are obtained from density functional theory. The dehydrogenated carbon dimers behave as effective impurities, whose motion decouples from...

Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

DEFF Research Database (Denmark)

Christensen, Rasmus Bjerregaard; Lu, Jing Tao; Hedegard, Per

2016-01-01

We employ a semi-classical Langevin approach to study current-induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon. All parameters are obtained from density functional theory. The dehydrogenated carbon dimers behave as effective impurities, whose motion decouples fro...

The comparative roles of connected and disconnected trajectories in the evaluation of the semiclassical coherent-state propagator

International Nuclear Information System (INIS)

Rubin, A.; Klauder, J.R.

1995-01-01

The semiclassical approximation of the coherent-state propagator developed by Klauder and subsequently modified by Adachi is applied to the quartic oscillator. This approximation involves classical trajectories which must satisfy complex boundary conditions. It is found that these complex classical trajectories fall into two broad categories basically characterized by the descriptive titles ''continuously connected'' and ''disconnected'' given to the two different types. The continuously connected type is found to always contribute in the evaluation of the semiclassical propagator while the disconnected type will only contribute under specific conditions. copyright 1995 Academic Press, Inc

A closer look at non-decoupling D-terms

Directory of Open Access Journals (Sweden)

Florian Staub

2016-07-01

Full Text Available Non-decoupling D-terms are an attractive possibility to enhance the tree-level mass of the standard model like Higgs boson in supersymmetric models. We discuss here for the case of a new Abelian gauge group two effects usually neglected in literature: (i the size of the additional radiative corrections to the Higgs mass due to the presence of the new gauge coupling, and (ii the impact of gauge kinetic mixing. It is shown that both effects reduce to some extent the positive effect of the non-decoupling D-terms on the Higgs mass.

Dynamically Decoupled 13C Spins in Hyperpolarized Nanodiamond

Science.gov (United States)

Rej, Ewa; Gaebel, Torsten; Boele, Thomas; Waddington, David; Reilly, David

The spin-spin relaxation time, T2, which determines how long a quantum state remains coherent, is an important factor for many applications ranging from MRI to quantum computing. A common technique used in quantum information technology to extend the T2, involves averaging out certain noise spectra via dynamical decoupling sequences. Depending on the nature of the noise in the system, specific sequences, such as CPMG, UDD or KDD, can be tailored to optimize T2. Here we combine hyperpolarization techniques and dynamical decoupling sequences to extend the T2 of 13C nuclear spins in nanodiamond by three orders of magnitude.

Have Market-oriented Reforms Decoupled China’s CO2 Emissions from Total Electricity Generation? An Empirical Analysis

Directory of Open Access Journals (Sweden)

Wei Shang

2016-05-01

Full Text Available Achieving the decoupling of electric CO2 emissions from total electricity generation is important in ensuring the sustainable socioeconomic development of China. To realize this, China implemented market-oriented reforms to its electric power industry at the beginning of 2003. This study used the Tapio decoupling index, the Laspeyres decomposition algorithm, and decoupling-related data from 1993 to 2012 to evaluate the effect of these reforms. Several conclusions can be drawn based on the empirical analysis. (1 The reforms changed the developmental trend of the decoupling index and facilitated its progress towards strong decoupling. (2 The results forecasted through fitting the curve to the decoupling index indicate that strong decoupling would be realized by 2030. (3 Limiting the manufacturing development and upgrading the generation equipment of the thermal power plants are essential for China to achieve strong decoupling at an early date. (4 China should enhance regulatory pressures and guidance for appropriate investment in thermal power plants to ensure the stable development of the decoupling index. (5 Transactions between multiple participants and electricity price bidding play active roles in the stable development of the decoupling index.

Virtual decoupling flight control via real-time trajectory synthesis and tracking

Science.gov (United States)

Zhang, Xuefu

The production of the General Aviation industry has declined in the past 25 years. Ironically, however, the increasing demand for air travel as a fast, safe, and high-quality mode of transportation has been far from satisfied. Addressing this demand shortfall with personal air transportation necessitates advanced systems for navigation, guidance, control, flight management, and flight traffic control. Among them, an effective decoupling flight control system will not only improve flight quality, safety, and simplicity, and increase air space usage, but also reduce expenses on pilot initial and current training, and thus expand the current market and explore new markets. Because of the formidable difficulties encountered in the actual decoupling of non-linear, time-variant, and highly coupled flight control systems through traditional approaches, a new approach, which essentially converts the decoupling problem into a real-time trajectory synthesis and tracking problem, is employed. Then, the converted problem is solved and a virtual decoupling effect is achieved. In this approach, a trajectory in inertial space can be predefined and dynamically modified based on the flight mission and the pilot's commands. A feedforward-feedback control architecture is constructed to guide the airplane along the trajectory as precisely as possible. Through this approach, the pilot has much simpler, virtually decoupled control of the airplane in terms of speed, flight path angle and horizontal radius of curvature. To verify and evaluate this approach, extensive computer simulation is performed. A great deal of test cases are designed for the flight control under different flight conditions. The simulation results show that our decoupling strategy is satisfactory and promising, and therefore the research can serve as a consolidated foundation for future practical applications.

Brain Emotional Learning Based Intelligent Decoupler for Nonlinear Multi-Input Multi-Output Distillation Columns

Directory of Open Access Journals (Sweden)

M. H. El-Saify

2017-01-01

Full Text Available The distillation process is vital in many fields of chemical industries, such as the two-coupled distillation columns that are usually highly nonlinear Multi-Input Multi-Output (MIMO coupled processes. The control of MIMO process is usually implemented via a decentralized approach using a set of Single-Input Single-Output (SISO loop controllers. Decoupling the MIMO process into group of single loops requires proper input-output pairing and development of decoupling compensator unit. This paper proposes a novel intelligent decoupling approach for MIMO processes based on new MIMO brain emotional learning architecture. A MIMO architecture of Brain Emotional Learning Based Intelligent Controller (BELBIC is developed and applied as a decoupler for 4 input/4 output highly nonlinear coupled distillation columns process. Moreover, the performance of the proposed Brain Emotional Learning Based Intelligent Decoupler (BELBID is enhanced using Particle Swarm Optimization (PSO technique. The performance is compared with the PSO optimized steady state decoupling compensation matrix. Mathematical models of the distillation columns and the decouplers are built and tested in simulation environment by applying the same inputs. The results prove remarkable success of the BELBID in minimizing the loops interactions without degrading the output that every input has been paired with.

Semiclassical model of deuteron dissociation in the Coulomb-Nuclear field

International Nuclear Information System (INIS)

Aleshin, V.P.; Sidorenko, B.I.

1995-01-01

We consider the survival probability of a deuteron which moves in the field of a heavy nucleus. This quantity was calculated within a semiclassical approach to the intrinsic motion within a deuteron and in the framework of an approach which makes use of the imaginary part of the phenomenological deuteron optical potential. A close agreement is obtained between these approaches in a broad range of deuteron energies and orbital momenta

A uniform semi-classical approach to the Coulomb fission problem

International Nuclear Information System (INIS)

Levit, S.; Smilansky, U.

1978-01-01

A semi-classical theory based on the path integral formalism is applied to the description of Coulomb fission. Complex classical trajectories are used to compute the classically forbidden transitions from the target's ground state to fission. In a simple model the energy spectrum and angular distributions of the fragments are calculated for the Coulomb fission in the Xe + U collision. Theoretical predictions are made which may be checked experimentally. (author)

Some applications of semiclassical methods to quantum chaos; Quelques applications des methodes semiclassiques en chaos quantique

Energy Technology Data Exchange (ETDEWEB)

Mouchet, A

1996-11-29

This thesis is made of four chapters. The first chapter is devoted to the description of the band structure, using the semiclassical periodic orbit theory, for a one electron system in a two-dimensional crystal with a high magnetic field perpendicular to the crystal plane. Complex orbits turn out to be fundamental for a proper description of the band structure since they incorporate conduction processes through tunneling mechanisms. In the second part, the author focuses on the role played in semiclassical expansions by complex orbits. They give exponentially small contribution when h is small only in a precise situation. In all other cases, complex orbits give birth to corrections in powers in h but unlike the extreme case they are hidden in the shadow of usual Gutzwiller contributions of real orbits. In the third chapter, a semiclassical expansion of the Berry two-form in terms of finite number of periodic orbits for a discrete chaotic map defined on a compact phase space and governed by external parameters is given. Besides, when dealing with a toroidal geometry, the author gives a similar expansion for the Chern index of any Bloch band of the quasi-energy spectrum and is thus led to a semiclassical interpretation of the Hall effect. In the last chapter, the author sets out a mechanism to explain how symmetries can create Berry phase shifts higher than 2{pi} in a 3D-adiabatic transport. He shows how one can understand in a topological point of view why these shifts are necessarily integer multiple of 2{pi}. An explicit construction of such arbitrary large phase shifts is finally proposed. (N.T.).

Decoupled Closed-Form Solution for Humanoid Lower Limb Kinematics

Directory of Open Access Journals (Sweden)

Alejandro Said

2015-01-01

Full Text Available This paper presents an explicit, omnidirectional, analytical, and decoupled closed-form solution for the lower limb kinematics of the humanoid robot NAO. The paper starts by decoupling the position and orientation analysis from the overall Denavit-Hartenberg (DH transformation matrices. Here, the joint activation sequence for the DH matrices is based on the geometry of a triangle. Furthermore, the implementation of a forward and a reversed kinematic analysis for the support and swing phase equations is developed to avoid matrix inversion. The allocation of constant transformations allows the position and orientation end-coordinate systems to be aligned with each other. Also, the redefinition of the DH transformations and the use of constraints allow decoupling the shared DOF between the legs and the torso. Finally, a geometric approach to avoid the singularities during the walking process is indicated. Numerical data is presented along with an experimental implementation to prove the validity of the analytical results.

Nonadiabatic dynamics in the semiclassical Liouville representation: Locality, transformation theory, and the energy budget

Energy Technology Data Exchange (ETDEWEB)

Martens, Craig C., E-mail: cmartens@uci.edu

2016-12-20

In this paper, we revisit the semiclassical Liouville approach to describing molecular dynamics with electronic transitions using classical trajectories. Key features of the formalism are highlighted. The locality in phase space and presence of nonclassical terms in the generalized Liouville equations are emphasized and discussed in light of trajectory surface hopping methodology. The representation dependence of the coupled semiclassical Liouville equations in the diabatic and adiabatic bases are discussed and new results for the transformation theory of the Wigner functions representing the corresponding density matrix elements given. We show that the diagonal energies of the state populations are not conserved during electronic transitions, as energy is stored in the electronic coherence. We discuss the implications of this observation for the validity of imposing strict energy conservation in trajectory based methods for simulating nonadiabatic processes.

Horizons of semiclassical black holes are cold

Energy Technology Data Exchange (ETDEWEB)

Brustein, Ram [Department of Physics, Ben-Gurion University,Beer-Sheva 84105 (Israel); CAS, Ludwig-Maximilians-Universität München,80333 München (Germany); Medved, A.J.M. [Department of Physics & Electronics, Rhodes University,Grahamstown 6140 (South Africa)

2014-06-10

We calculate, using our recently proposed semiclassical framework, the quantum state of the Hawking pairs that are produced during the evaporation of a black hole (BH). Our framework adheres to the standard rules of quantum mechanics and incorporates the quantum fluctuations of the collapsing shell spacetime in Hawking’s original calculation, while accounting for back-reaction effects. We argue that the negative-energy Hawking modes need to be regularly integrated out; and so these are effectively subsumed by the BH and, as a result, the number of coherent negative-energy modes N{sub coh} at any given time is parametrically smaller than the total number of the Hawking particles N{sub total} emitted during the lifetime of the BH. We find that N{sub coh} is determined by the width of the BH wavefunction and scales as the square root of the BH entropy. We also find that the coherent negative-energy modes are strongly entangled with their positive-energy partners. Previously, we have found that N{sub coh} is also the number of coherent outgoing particles and that information can be continually transferred to the outgoing radiation at a rate set by N{sub coh}. Our current results show that, while the BH is semiclassical, information can be released without jeopardizing the nearly maximal inside-out entanglement and imply that the state of matter near the horizon is approximately the vacuum. The BH firewall proposal, on the other hand, is that the state of matter near the horizon deviates substantially from the vacuum, starting at the Page time. We find that, under the usual assumptions for justifying the formation of a firewall, one does indeed form at the Page time. However, the possible loophole lies in the implicit assumption that the number of strongly entangled pairs can be of the same order of N{sub total}.

Classical and semiclassical aspects of chemical dynamics

International Nuclear Information System (INIS)

Gray, S.K.

1982-08-01

Tunneling in the unimolecular reactions H 2 C 2 → HC 2 H, HNC → HCN, and H 2 CO → H 2 + CO is studied with a classical Hamiltonian that allows the reaction coordinate and transverse vibrational modes to be considered directly. A combination of classical perturbation theory and the semiclassical WKB method allows tunneling probabilities to be obtained, and a statistical theory (RRKM) is used to construct rate constants for these reactions in the tunneling regime. In this fashion, it is found that tunneling may be important, particularly for low excitation energies. Nonadiabatic charge transfer in the reaction Na + I → Na + + I - is treated with classical trajectories based on a classical Hamiltonian that is the analogue of a quantum matrix representation. The charge transfer cross section obtained is found to agree reasonably well with the exact quantum results. An approximate semiclassical formula, valid at high energies, is also obtained. The interaction of radiation and matter is treated from a classical viewpoint. The excitation of an HF molecule in a strong laser is described with classical trajectories. Quantum mechanical results are also obtained and compared to the classical results. Although the detailed structure of the pulse time averaged energy absorption cannot be reproduced classically, classical mechanics does predict the correct magnitude of energy absorption, as well as certain other qualitative features. The classical behavior of a nonrotating diatomic molecule in a strong laser field is considered further, by generating a period advance map that allows the solution over many periods of oscillation of the laser to be obtained with relative ease. Classical states are found to form beautiful spirals in phase space as time progresses. A simple pendulum model is found to describe the major qualitative features

Semiclassical relations and IR effects in de Sitter and slow-roll space-times

Energy Technology Data Exchange (ETDEWEB)

Giddings, Steven B. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Sloth, Martin S., E-mail: giddings@physics.ucsb.edu, E-mail: sloth@cern.ch [CERN, Physics Department, Theory Unit, CH-1211 Geneva 23 (Switzerland)

2011-01-01

We calculate IR divergent graviton one-loop corrections to scalar correlators in de Sitter space, and show that the leading IR contribution may be reproduced via simple semiclassical consistency relations. One can likewise use such semiclassical relations to calculate leading IR corrections to correlators in slow-roll inflation. The regulated corrections shift the tensor/scalar ratio and consistency relation of single field inflation, and non-gaussianity parameters averaged over very large distances. For inflation of sufficient duration, for example arising from a chaotic inflationary scenario, these corrections become of order unity. First-order corrections of this size indicate a breakdown of the perturbative expansion, and suggest the need for a non-perturbative description of the corresponding regime. This is analogous to a situation argued to arise in black hole evolution, and to interfere with a sharp perturbative calculation of ''missing information'' in Hawking radiation.

Semiclassical relations and IR effects in de Sitter and slow-roll space-times

International Nuclear Information System (INIS)

Giddings, Steven B.; Sloth, Martin S.

2011-01-01

We calculate IR divergent graviton one-loop corrections to scalar correlators in de Sitter space, and show that the leading IR contribution may be reproduced via simple semiclassical consistency relations. One can likewise use such semiclassical relations to calculate leading IR corrections to correlators in slow-roll inflation. The regulated corrections shift the tensor/scalar ratio and consistency relation of single field inflation, and non-gaussianity parameters averaged over very large distances. For inflation of sufficient duration, for example arising from a chaotic inflationary scenario, these corrections become of order unity. First-order corrections of this size indicate a breakdown of the perturbative expansion, and suggest the need for a non-perturbative description of the corresponding regime. This is analogous to a situation argued to arise in black hole evolution, and to interfere with a sharp perturbative calculation of ''missing information'' in Hawking radiation

An entropy-variables-based formulation of residual distribution schemes for non-equilibrium flows

Science.gov (United States)

Garicano-Mena, Jesús; Lani, Andrea; Degrez, Gérard

2018-06-01

In this paper we present an extension of Residual Distribution techniques for the simulation of compressible flows in non-equilibrium conditions. The latter are modeled by means of a state-of-the-art multi-species and two-temperature model. An entropy-based variable transformation that symmetrizes the projected advective Jacobian for such a thermophysical model is introduced. Moreover, the transformed advection Jacobian matrix presents a block diagonal structure, with mass-species and electronic-vibrational energy being completely decoupled from the momentum and total energy sub-system. The advantageous structure of the transformed advective Jacobian can be exploited by contour-integration-based Residual Distribution techniques: established schemes that operate on dense matrices can be substituted by the same scheme operating on the momentum-energy subsystem matrix and repeated application of scalar scheme to the mass-species and electronic-vibrational energy terms. Finally, the performance gain of the symmetrizing-variables formulation is quantified on a selection of representative testcases, ranging from subsonic to hypersonic, in inviscid or viscous conditions.

Dynamical decoupling assisted acceleration of two-spin evolution in XY spin-chain environment

Energy Technology Data Exchange (ETDEWEB)

Wei, Yong-Bo; Zou, Jian [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Wang, Zhao-Ming [Department of Physics, Ocean University of China, Qingdao 266100 (China); Shao, Bin, E-mail: sbin610@bit.edu.cn [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Li, Hai [School of Information and Electronic Engineering, Shandong Institute of Business and Technology, Yantai 264000 (China)

2016-01-28

We study the speed-up role of dynamical decoupling in an open system, which is modeled as two central spins coupled to their own XY spin-chain environment. We show that the fast bang–bang pulses can suppress the system evolution, which manifests the quantum Zeno effect. In contrast, with the increasing of the pulse interval time, the bang–bang pulses can enhance the decay of the quantum speed limit time and induce the speed-up process, which displays the quantum anti-Zeno effect. In addition, we show that the random pulses can also induce the speed-up of quantum evolution. - Highlights: • We propose a scheme to accelerate the dynamical evolution of central spins in an open system. • The quantum speed limit of central spins can be modulated by changing pulse frequency. • The random pulses can play the same role as the regular pulses do for small perturbation.

A derivation of the Derbenev-Kondratenko formula using semi-classical electrodynamics

International Nuclear Information System (INIS)

Mane, S.R.

1985-11-01

We present a detailed exposition of the mechanism for the build-up of polarization in electron storage rings. A semi-classical approach is used to derive the rate of growth and asymptotic degree of polarization in an electron storage ring (the Derbenev-Kondratenko formula). Statistical mechanical concepts used to obtain as classical an understanding as possible of this phenomenon. (orig.)

Classical properties and semiclassical calculations in a spherical nuclear average potential

International Nuclear Information System (INIS)

Carbonell, J.; Brut, F.; Arvieu, R.; Touchard, J.

1984-03-01

We study the relation between the classical properties or an average nuclear potential and its spectral properties. We have drawn the energy-action surface of this potential and related its properties to the spectral ones in the framework of the EBK semiclassical method. We also describe a method allowing us to get the evolution of the spectrum with the mass number

Semiclassical electronic transport in MnAs thin films

International Nuclear Information System (INIS)

Helman, C.; Milano, J.; Steren, L.; Llois, A.M.

2008-01-01

Magneto-transport experiments have been recently performed on MnAs thin films. Hall effect and transverse magnetoresistance measurements have shown interesting and, until now, unknown results. For instance, the transverse magnetoresistance shows no saturation in the presence of very high magnetic fields. In order to understand the contribution of the electronic band structure to the non-saturating magnetoresistance, we perform ab initio calculations, using the Wien2K code and analyze the magneto-transport properties within the semiclassical approximation. We show that non-saturation may be due to the presence of open orbits on the majority Fermi surface

Semiclassical electronic transport in MnAs thin films

Energy Technology Data Exchange (ETDEWEB)

Helman, C. [Dpto de Fisica, ' Juan Jose Giambiagi' , Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires (Argentina); Unidad de Actividad Fisica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Buenos Aires (Argentina)], E-mail: helman@tandar.cnea.gov.ar; Milano, J.; Steren, L. [Departamento de Fisica, Centro Atomico Bariloche, Comision Nacional de Energia Atomica, S.C. Bariloche (Argentina); Llois, A.M. [Dpto de Fisica, ' Juan Jose Giambiagi' , Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires (Argentina); Unidad de Actividad Fisica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Buenos Aires (Argentina)

2008-07-15

Magneto-transport experiments have been recently performed on MnAs thin films. Hall effect and transverse magnetoresistance measurements have shown interesting and, until now, unknown results. For instance, the transverse magnetoresistance shows no saturation in the presence of very high magnetic fields. In order to understand the contribution of the electronic band structure to the non-saturating magnetoresistance, we perform ab initio calculations, using the Wien2K code and analyze the magneto-transport properties within the semiclassical approximation. We show that non-saturation may be due to the presence of open orbits on the majority Fermi surface.

Robust dynamical decoupling for quantum computing and quantum memory.

Science.gov (United States)

Souza, Alexandre M; Alvarez, Gonzalo A; Suter, Dieter

2011-06-17

Dynamical decoupling (DD) is a popular technique for protecting qubits from the environment. However, unless special care is taken, experimental errors in the control pulses used in this technique can destroy the quantum information instead of preserving it. Here, we investigate techniques for making DD sequences robust against different types of experimental errors while retaining good decoupling efficiency in a fluctuating environment. We present experimental data from solid-state nuclear spin qubits and introduce a new DD sequence that is suitable for quantum computing and quantum memory.

Semiclassical model of atomic collisions: stopping and capture of the heavy charged particles and exotic atom formation

International Nuclear Information System (INIS)

Beck, W.A.

2000-01-01

The semiclassical model of atomic collisions, especially in different areas of the maximum stopping, when proton collides at the velocity of the boron order velocity, providing as the result for interactions of many bodies with an electron target, enabling application of the model with high degree of confidence to a clearly expressed experimental problem, such the antiproton capture on helium, is presented. The semiclassical collision model and stopping energy are considered. The stopping and capture of negatively-charged particles are investigated. The capture and angular moments of antiprotons, captures at the end of the collision cascade, are presented [ru

Neutronic studies on decoupled hydrogen moderator for a short-pulse spallation source

International Nuclear Information System (INIS)

Harada, Masahide; Watanabe, Noboru; Teshigawara, Makoto; Kai, Tetsuya; Ikeda, Yujiro

2005-01-01

Neutronic studies of decoupled hydrogen moderators were performed by calculations taking into account para hydrogen content, decoupling energy, moderator dimensions/shapes and reflector material. Low-energy parts of calculated spectral intensities with different para hydrogen contents were analyzed by a modified Maxwell function to characterize neutron spectra. The result shows that a 100% para hydrogen moderator gives the highest pulse peak intensity together with the narrowest pulse width and the shortest decay times. Pulse broadening with a reflector was explained by time distributions of source neutrons entering into the moderator through a decoupler. Material dependence of time distribution was studied. A decoupling energy higher than 1 eV does not bring about a large improvement in pulse widths and decay times, even at a large penalty in the peak intensity. The optimal moderator thickness was also discussed for a rectangular parallelepipe-shaped and a canteen-shaped moderator

Semiclassical eigenenergies in the wake of fast ions in solids

International Nuclear Information System (INIS)

Mueller, J.; Burgdoerfer, J.; Noid, D.W.

1990-01-01

We compare the semiclassical and quantum mechanical eigenenergies of an electron in the wake of a fast, highly charged ion traversing a solid. The classical dynamics of this system shows a transition from regular to chaotic motion as a function of the binding energy. The transition can also be seen in the quantal spectra. We find evidence for a connection between bifurcation of tori and disorder in the energy level sequences. 21 refs., 4 figs

Decoupled systems on trial: Eliminating bottlenecks to improve aquaponic processes.

Directory of Open Access Journals (Sweden)

Hendrik Monsees

Full Text Available In classical aquaponics (coupled aquaponic systems, 1-loop systems the production of fish in recirculating aquaculture systems (RAS and plants in hydroponics are combined in a single loop, entailing systemic compromises on the optimal production parameters (e.g. pH. Recently presented decoupled aquaponics (2-loop systems have been awarded for eliminating major bottlenecks. In a pilot study, production in an innovative decoupled aquaponic system was compared with a coupled system and, as a control, a conventional RAS, assessing growth parameters of fish (FCR, SGR and plants over an experimental period of 5 months. Soluble nutrients (NO3--N, NO2--N, NH4+-N, PO43-, K+, Ca2+, Mg2+, SO42-, Cl2- and Fe2+, elemental composition of plants, fish and sludge (N, P, K, Ca, Mg, Na, C, abiotic factors (temperature, pH, oxygen, and conductivity, fertilizer and water consumption were determined. Fruit yield was 36% higher in decoupled aquaponics and pH and fertilizer management was more effective, whereas fish production was comparable in both systems. The results of this pilot study clearly illustrate the main advantages of decoupled, two-loop aquaponics and demonstrate how bottlenecks commonly encountered in coupled aquaponics can be managed to promote application in aquaculture.

Decoupled systems on trial: Eliminating bottlenecks to improve aquaponic processes.

Science.gov (United States)

Monsees, Hendrik; Kloas, Werner; Wuertz, Sven

2017-01-01

In classical aquaponics (coupled aquaponic systems, 1-loop systems) the production of fish in recirculating aquaculture systems (RAS) and plants in hydroponics are combined in a single loop, entailing systemic compromises on the optimal production parameters (e.g. pH). Recently presented decoupled aquaponics (2-loop systems) have been awarded for eliminating major bottlenecks. In a pilot study, production in an innovative decoupled aquaponic system was compared with a coupled system and, as a control, a conventional RAS, assessing growth parameters of fish (FCR, SGR) and plants over an experimental period of 5 months. Soluble nutrients (NO3--N, NO2--N, NH4+-N, PO43-, K+, Ca2+, Mg2+, SO42-, Cl2- and Fe2+), elemental composition of plants, fish and sludge (N, P, K, Ca, Mg, Na, C), abiotic factors (temperature, pH, oxygen, and conductivity), fertilizer and water consumption were determined. Fruit yield was 36% higher in decoupled aquaponics and pH and fertilizer management was more effective, whereas fish production was comparable in both systems. The results of this pilot study clearly illustrate the main advantages of decoupled, two-loop aquaponics and demonstrate how bottlenecks commonly encountered in coupled aquaponics can be managed to promote application in aquaculture.

Numerical solutions of the semiclassical Boltzmann ellipsoidal-statistical kinetic model equation

Science.gov (United States)

Yang, Jaw-Yen; Yan, Chin-Yuan; Huang, Juan-Chen; Li, Zhihui

2014-01-01

Computations of rarefied gas dynamical flows governed by the semiclassical Boltzmann ellipsoidal-statistical (ES) kinetic model equation using an accurate numerical method are presented. The semiclassical ES model was derived through the maximum entropy principle and conserves not only the mass, momentum and energy, but also contains additional higher order moments that differ from the standard quantum distributions. A different decoding procedure to obtain the necessary parameters for determining the ES distribution is also devised. The numerical method in phase space combines the discrete-ordinate method in momentum space and the high-resolution shock capturing method in physical space. Numerical solutions of two-dimensional Riemann problems for two configurations covering various degrees of rarefaction are presented and various contours of the quantities unique to this new model are illustrated. When the relaxation time becomes very small, the main flow features a display similar to that of ideal quantum gas dynamics, and the present solutions are found to be consistent with existing calculations for classical gas. The effect of a parameter that permits an adjustable Prandtl number in the flow is also studied. PMID:25104904

Late kinetic decoupling of light magnetic dipole dark matter

International Nuclear Information System (INIS)

Gondolo, Paolo; Kadota, Kenji

2016-01-01

We study the kinetic decoupling of light (≲10 GeV) magnetic dipole dark matter (DM). We find that present bounds from collider, direct DM searches, and structure formation allow magnetic dipole DM to remain in thermal equilibrium with the early universe plasma until as late as the electron-positron annihilation epoch. This late kinetic decoupling leads to a minimal mass for the earliest dark protohalos of thousands of solar masses, in contrast to the conventional weak scale DM scenario where they are of order 10 −6 solar masses.

Semi-classical propagation of wavepackets for the phase space Schroedinger equation: interpretation in terms of the Feichtinger algebra

International Nuclear Information System (INIS)

Gosson, Maurice A de

2008-01-01

The nearby orbit method is a powerful tool for constructing semi-classical solutions of Schroedinger's equation when the initial datum is a coherent state. In this paper, we first extend this method to arbitrary squeezed states and thereafter apply our results to the Schroedinger equation in phase space. This adaptation requires the phase-space Weyl calculus developed in previous work of ours. We also study the regularity of the semi-classical solutions from the point of view of the Feichtinger algebra familiar from the theory of modulation spaces

Revisiting the decoupling effects in the running of the Cosmological Constant

International Nuclear Information System (INIS)

Antipin, Oleg; Melic, Blazenka

2017-01-01

We revisit the decoupling effects associated with heavy particles in the renormalization group running of the vacuum energy in a mass-dependent renormalization scheme. We find the running of the vacuum energy stemming from the Higgs condensate in the entire energy range and show that it behaves as expected from the simple dimensional arguments meaning that it exhibits the quadratic sensitivity to the mass of the heavy particles in the infrared regime. The consequence of such a running to the fine-tuning problem with the measured value of the Cosmological Constant is analyzed and the constraint on the mass spectrum of a given model is derived. We show that in the Standard Model (SM) this fine-tuning constraint is not satisfied while in the massless theories this constraint formally coincides with the well known Veltman condition. We also provide a remarkably simple extension of the SM where saturation of this constraint enables us to predict the radiative Higgs mass correctly. Generalization to constant curvature spaces is also given. (orig.)

Revisiting the decoupling effects in the running of the Cosmological Constant

Energy Technology Data Exchange (ETDEWEB)

Antipin, Oleg; Melic, Blazenka [Rudjer Boskovic Institute, Division of Theoretical Physics, Zagreb (Croatia)

2017-09-15

We revisit the decoupling effects associated with heavy particles in the renormalization group running of the vacuum energy in a mass-dependent renormalization scheme. We find the running of the vacuum energy stemming from the Higgs condensate in the entire energy range and show that it behaves as expected from the simple dimensional arguments meaning that it exhibits the quadratic sensitivity to the mass of the heavy particles in the infrared regime. The consequence of such a running to the fine-tuning problem with the measured value of the Cosmological Constant is analyzed and the constraint on the mass spectrum of a given model is derived. We show that in the Standard Model (SM) this fine-tuning constraint is not satisfied while in the massless theories this constraint formally coincides with the well known Veltman condition. We also provide a remarkably simple extension of the SM where saturation of this constraint enables us to predict the radiative Higgs mass correctly. Generalization to constant curvature spaces is also given. (orig.)

Unmasking decoupling: Redefining the Resource Intensity of the Economy.

Science.gov (United States)

Bithas, Kostas; Kalimeris, Panos

2018-04-01

Interest in investigating the complex link between resources and developments has revived recently following studies which support striking "dematerialized" growth over the last hundred years or so. This so-called decoupling effect is defined as the declining quantity of resources required for producing one unit of GDP. Decoupling studies adopt aggregate GDP as the measure of the outcome of the economy. However, this outcome is contributed by the total population which differs over time and between countries. A valid comparison should use a comparable, standardized indicator that adjusts for population size. GDP per capita, the income index, defines in monetary terms the ultimate outcome of the economy and is adopted by international organizations as the standard index for comparing economies. The income index approximates, in monetary terms, the welfare produced by the economic system and enjoyed by individuals. Recently developed alternative indexes of welfare lack broad data coverage and have limited empirical application as yet. For this reason and for ensuring direct comparison with the standard decoupling estimates, our study remains within the monetary context. The present paper re-evaluates the resources-economy link from the perspective of "the resources required for the production of one unit of GDP per capita (Income)" and hence evaluates the efficiency of turning resources into the actual outcome of the economic system. Our estimates suggest that the dependence of global economic growth on natural resources has increased by over 60% in the last 110years (1900-2009), contrasting with the prevailing decoupling estimates which suggest a reduction by 63%. We find that the actual decoupling, which began in the mid-1970s in post-industrial economies, is counterbalanced by the intensified resource intensity of several developing economies. Accordingly, in the pursuit of sustainability, the dematerialization target needs to be more clearly incorporated into

A critical overview of industrial energy decoupling programs in six developing countries in Asia

International Nuclear Information System (INIS)

Luken, Ralph A.; Piras, Stefano

2011-01-01

In reviewing the journal literature on the decoupling of energy use and industrial output in the Asian region, particularly with respect to developing countries, we found little information about most country programs other than for China and India and only one article that compared the programs of these two countries. For this reason, we used diverse sources to identify the key programmatic features that have contributed, but clearly are not totally responsible for, decoupling achievements of two countries ( China and Thailand) and then, on the basis of these findings, reviewed emerging industrial energy decoupling programs in four other countries (India, Indonesia, Malaysia and Vietnam). We found that the design of the two successful on-going decoupling programs have common features, which are setting an explicit target for decoupling of energy use and industrial output, a government program that offers financial incentives and imposes specific auditing and reporting requirements and involvement of the manufacturing sector in designing and implementing targets as they apply to individual enterprises. We also found that the emerging programs in the other four countries lack some or all of these essential programmatic features. - Highlights: → We reviewed two on-going and four emerging industrial energy decoupling programs. → These six Asian developing countries have very different rates of decoupling. → The two successful on-going programs share three common features. → These are quantitative targets, supportive programs and industry involvement. → The four emerging programs lack some or all of these features.

Instanton calculus without equations of motion: semiclassics from monodromies of a Riemann surface

Science.gov (United States)

Gulden, Tobias; Janas, Michael; Kamenev, Alex

2015-02-01

Instanton calculations in semiclassical quantum mechanics rely on integration along trajectories which solve classical equations of motion. However in systems with higher dimensionality or complexified phase space these are rarely attainable. A prime example are spin-coherent states which are used e.g. to describe single molecule magnets (SMM). We use this example to develop instanton calculus which does not rely on explicit solutions of the classical equations of motion. Energy conservation restricts the complex phase space to a Riemann surface of complex dimension one, allowing to deform integration paths according to Cauchy’s integral theorem. As a result, the semiclassical actions can be evaluated without knowing actual classical paths. Furthermore we show that in many cases such actions may be solely derived from monodromy properties of the corresponding Riemann surface and residue values at its singular points. As an example, we consider quenching of tunneling processes in SMM by an applied magnetic field.

Applications of the semiclassical spectral method to nuclear, atomic, molecular, and polymeric dynamics

International Nuclear Information System (INIS)

Koszykowski, M.L.; Pfeffer, G.A.; Noid, D.W.

1987-01-01

Nonlinear dynamics plays a dominant role in a variety of important problems in chemical physics. Examples are unimolecular reactions, infrared multiphoton decomposition of molecules, the pumping process of the gamma ray laser, dissociation of vibrationally excited state-selected van der Waals's complexes, and many other chemical and atomic processes. The present article discusses recent theoretical studies on the quasi-periodic and chaotic dynamic aspects of vibrational-rotational states of atomic, nuclear, and molecular systems using the semiclassical spectral method (SSM). The authors note that the coordinates, momenta, and so on, are found using classical mechanics in the studies included in this review. They outline the semiclassical spectral method and a wide variety of applications. Although this technique was first developed ten years ago, it has proved to be tremendously successful as a tool used in dynamics problems. Applications include problems in nonlinear dynamics, molecular and atomic spectra, surface science, astronomy and stellar dynamics, nuclear physics, and polymer physics

Hyperspherical time-dependent method with semiclassical outgoing waves for double photoionization of helium

International Nuclear Information System (INIS)

Kazansky, A.K.; Selles, P.; Malegat, L.

2003-01-01

The hyperspherical time-dependent method with semiclassical outgoing waves for study of double photoionization of helium is presented. It is closely related to the hyperspherical R-matrix method with semiclassical outgoing waves [Phys. Rev. A 65, 032711 (2002)]: both split configuration space into two regions to solve the stationary inhomogeneous Schroedinger equation associated with the one-photon ionization problem, and both apply the same treatment to the outer region. However, the two methods differ radically in their treatments of the problem in the inner region: the most recent one applies a time-dependent approach for calculating the stationary wave function, while the previous one uses a R-matrix treatment. The excellent agreement observed between the triple differential cross sections obtained from these two basically different methods provides very strong support for both of them. Importantly, the very different numerical structures of both methods might make the most recent one a better candidate for investigating the near-threshold region

Combinatorial theory of the semiclassical evaluation of transport moments II: Algorithmic approach for moment generating functions

Energy Technology Data Exchange (ETDEWEB)

Berkolaiko, G. [Department of Mathematics, Texas A and M University, College Station, Texas 77843-3368 (United States); Kuipers, J. [Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg (Germany)

2013-12-15

Electronic transport through chaotic quantum dots exhibits universal behaviour which can be understood through the semiclassical approximation. Within the approximation, calculation of transport moments reduces to codifying classical correlations between scattering trajectories. These can be represented as ribbon graphs and we develop an algorithmic combinatorial method to generate all such graphs with a given genus. This provides an expansion of the linear transport moments for systems both with and without time reversal symmetry. The computational implementation is then able to progress several orders further than previous semiclassical formulae as well as those derived from an asymptotic expansion of random matrix results. The patterns observed also suggest a general form for the higher orders.

Frozen Gaussian approximation based domain decomposition methods for the linear Schrödinger equation beyond the semi-classical regime

Science.gov (United States)

Lorin, E.; Yang, X.; Antoine, X.

2016-06-01

The paper is devoted to develop efficient domain decomposition methods for the linear Schrödinger equation beyond the semiclassical regime, which does not carry a small enough rescaled Planck constant for asymptotic methods (e.g. geometric optics) to produce a good accuracy, but which is too computationally expensive if direct methods (e.g. finite difference) are applied. This belongs to the category of computing middle-frequency wave propagation, where neither asymptotic nor direct methods can be directly used with both efficiency and accuracy. Motivated by recent works of the authors on absorbing boundary conditions (Antoine et al. (2014) [13] and Yang and Zhang (2014) [43]), we introduce Semiclassical Schwarz Waveform Relaxation methods (SSWR), which are seamless integrations of semiclassical approximation to Schwarz Waveform Relaxation methods. Two versions are proposed respectively based on Herman-Kluk propagation and geometric optics, and we prove the convergence and provide numerical evidence of efficiency and accuracy of these methods.

Semiclassical Monte Carlo: A first principles approach to non-adiabatic molecular dynamics

International Nuclear Information System (INIS)

White, Alexander J.; Gorshkov, Vyacheslav N.; Wang, Ruixi; Tretiak, Sergei; Mozyrsky, Dmitry

2014-01-01

Modeling the dynamics of photophysical and (photo)chemical reactions in extended molecular systems is a new frontier for quantum chemistry. Many dynamical phenomena, such as intersystem crossing, non-radiative relaxation, and charge and energy transfer, require a non-adiabatic description which incorporate transitions between electronic states. Additionally, these dynamics are often highly sensitive to quantum coherences and interference effects. Several methods exist to simulate non-adiabatic dynamics; however, they are typically either too expensive to be applied to large molecular systems (10's-100's of atoms), or they are based on ad hoc schemes which may include severe approximations due to inconsistencies in classical and quantum mechanics. We present, in detail, an algorithm based on Monte Carlo sampling of the semiclassical time-dependent wavefunction that involves running simple surface hopping dynamics, followed by a post-processing step which adds little cost. The method requires only a few quantities from quantum chemistry calculations, can systematically be improved, and provides excellent agreement with exact quantum mechanical results. Here we show excellent agreement with exact solutions for scattering results of standard test problems. Additionally, we find that convergence of the wavefunction is controlled by complex valued phase factors, the size of the non-adiabatic coupling region, and the choice of sampling function. These results help in determining the range of applicability of the method, and provide a starting point for further improvement

Study between the semi-classical and the generator-coordinate methods

International Nuclear Information System (INIS)

Souza Cruz, F.F. de.

1979-01-01

In this work it is performed a comparison between two microscopic theories of the colective movement: semi-classical theory and the quantum theory from the generator -coordinate method. In boths cases, it is used wave packets |p,q> which depend on two canonical conjugate parameters. These wave packets are constructed by the action of displacement unitory operators, which are generated by canonical operators Q-circumflex and P-circumflex on a referencial state. (A.C.A.S.) [pt

The semiclassical limit of W.sub.N./sub. CFTs and Vasiliev theory

Czech Academy of Sciences Publication Activity Database

Perlmutter, E.; Procházka, Tomáš; Raeymaekers, Joris

2013-01-01

Roč. 2013, č. 5 (2013), s. 1-51 ISSN 1029-8479 R&D Projects: GA ČR(CZ) GAP203/11/1388 Grant - others:EUROHORC and ESF(XE) EYI/07/E010 Institutional support: RVO:68378271 Keywords : field theory * coupling * scalar * matter * spin * semiclassical * gravitation * defect Subject RIV: BE - Theoretical Physics Impact factor: 6.220, year: 2013

Analysis of near-field data from a Soviet decoupling experiment

International Nuclear Information System (INIS)

Saikia, C.K.; McLaren, J.P.; Helmberger, D.V.

1993-01-01

Recently Adushkin et al. (1992a) presented some results on a decoupling experiment performed in a salt dome in Azghir near the Caspian Sea. A large coupled shot (64 kT) was followed five years later by a decoupled shot (8 kT) fired in the cavity formed by the earlier event. Both events were recorded locally and this data has been provided by the Soviet scientists in a cooperative effort to better understand the seismic coupling problem. This data, in conjunction with WWSSN observations, is analyzed in an effort to determine the RDP's and an estimate of t. Our preliminary results suggest that RDP appropriate for the large event is quite similar to that of LONGSHOT (80 kT event). Their teleseismic observations are difficult to distinguish in waveshape. The M s for LONGSHOT is 3.9 while that for the coupled Russian event is 3.3. The m b for the LONGSHOT (5.8) is slightly smaller than for the Russian event (m b = 6.0, ISC). This comparison of m b :M s appears to be common to most Azghir events as compared to the US experience. The t* appropriate for Amchitka (t* = 0.9) was established by near-field and teleseismic modeling of waveform data similar to this study where we obtain a t* = 0.5 to 0.6. The RDP for the small event is less well resolved but appears to be only partially decoupled. Prior estimates of decoupling factors range from 30 (based on this data by Adushkin) to 70 (for the Sterling/Salmon experiment). Our analysis produces a decoupling factor of about 15 using near-field data which is similar to the teleseismic modeling result

Comparative role of potential structure in classical, semiclassical, and quantum mechanics

International Nuclear Information System (INIS)

Judson, R.S.; Shi, S.; Rabitz, H.

1989-01-01

The corresponding effects of features in the potential on classical, semiclassical, and quantum mechanics are probed using the technique of functional sensitivity analysis. It is shown that the classical and quantum functional sensitivities are equivalent in the classical (small (h/2π)) and harmonic limits. Classical and quantum mechanics are known to react in qualitatively similar ways provided that features on the potential are smooth on the length scale of oscillations in the quantum wave function. By using functional sensitivity analysis, we are able to show in detail how the classical and quantum dynamics differ in the way that they sense the potential. Two examples are given, the first of which is the harmonic oscillator. This problem is well understood by other means but is useful to examine because it illustrates the detailed information about the interaction of the potential and the dynamics which can be provided by functional sensitivity analysis, simplifying the analysis of more complex systems. The second example is the collinear H+H 2 reaction. In that case there are a number of detailed and striking differences between the ways that classical and quantum mechanics react to features on the potential. For features which are broad compared to oscillations in the wave function, the two react in qualitatively the same way. The sensitivities are oscillatory, however, and there are phasing differences between the classical and quantum sensitivity functions. This means that using classical mechanics plus experimental data in an inversion scheme intended to find the ''true'' potential will necessarily introduce sizeable errors

Improvements on Semi-Classical Distorted-Wave model

Energy Technology Data Exchange (ETDEWEB)

Sun Weili; Watanabe, Y.; Kuwata, R. [Kyushu Univ., Fukuoka (Japan); Kohno, M.; Ogata, K.; Kawai, M.

1998-03-01

A method of improving the Semi-Classical Distorted Wave (SCDW) model in terms of the Wigner transform of the one-body density matrix is presented. Finite size effect of atomic nuclei can be taken into account by using the single particle wave functions for harmonic oscillator or Wood-Saxon potential, instead of those based on the local Fermi-gas model which were incorporated into previous SCDW model. We carried out a preliminary SCDW calculation of 160 MeV (p,p`x) reaction on {sup 90}Zr with the Wigner transform of harmonic oscillator wave functions. It is shown that the present calculation of angular distributions increase remarkably at backward angles than the previous ones and the agreement with the experimental data is improved. (author)

Decoupled equations for reverse time migration in tilted transversely isotropic media

KAUST Repository

Zhan, Ge; Pestana, Reynam C.; Stoffa, Paul L.

2012-01-01

Conventional modeling and migration for tilted transversely isotropic (TTI) media may suffer from numerical instabilities and shear wave artifacts due to the coupling of the P-wave and SV-wave modes in the TTI coupled equations. Starting with the separated P- and SV-phase velocity expressions for vertical transversely isotropic (VTI) media, we extend these decoupled equations for modeling and reverse time migration (RTM) in acoustic TTI media. Compared with the TTI coupled equations published in the geophysical literature, the new TTI decoupled equations provide a more stable solution due to the complete separation of the P-wave and SV-wave modes. The pseudospectral method is the most convenient method to implement these equations due to the form of wavenumber expressions and has the added benefit of being highly accurate and thus avoiding numerical dispersion. The rapid expansion method (REM) in time is employed to produce a broad band numerically stable time evolution of the wavefields. Synthetic results validate the proposed TTI decoupled equations and show that modeling and RTM in TTI media with the decoupled equations remain numerically stable even for models with strong anisotropy and sharp contrasts. © 2012 Society of Exploration Geophysicists.

Decoupled equations for reverse time migration in tilted transversely isotropic media

KAUST Repository

Zhan, Ge

2012-03-01

Conventional modeling and migration for tilted transversely isotropic (TTI) media may suffer from numerical instabilities and shear wave artifacts due to the coupling of the P-wave and SV-wave modes in the TTI coupled equations. Starting with the separated P- and SV-phase velocity expressions for vertical transversely isotropic (VTI) media, we extend these decoupled equations for modeling and reverse time migration (RTM) in acoustic TTI media. Compared with the TTI coupled equations published in the geophysical literature, the new TTI decoupled equations provide a more stable solution due to the complete separation of the P-wave and SV-wave modes. The pseudospectral method is the most convenient method to implement these equations due to the form of wavenumber expressions and has the added benefit of being highly accurate and thus avoiding numerical dispersion. The rapid expansion method (REM) in time is employed to produce a broad band numerically stable time evolution of the wavefields. Synthetic results validate the proposed TTI decoupled equations and show that modeling and RTM in TTI media with the decoupled equations remain numerically stable even for models with strong anisotropy and sharp contrasts. © 2012 Society of Exploration Geophysicists.

Decoupling limit and throat geometry of non-susy D3 brane

Energy Technology Data Exchange (ETDEWEB)

Nayek, Kuntal, E-mail: kuntal.nayek@saha.ac.in; Roy, Shibaji, E-mail: shibaji.roy@saha.ac.in

2017-03-10

Recently it has been shown by us that, like BPS Dp branes, bulk gravity gets decoupled from the brane even for the non-susy Dp branes of type II string theories indicating a possible extension of AdS/CFT correspondence for the non-supersymmetric case. In that work, the decoupling of gravity on the non-susy Dp branes has been shown numerically for the general case as well as analytically for some special case. Here we discuss the decoupling limit and the throat geometry of the non-susy D3 brane when the charge associated with the brane is very large. We show that in the decoupling limit the throat geometry of the non-susy D3 brane, under appropriate coordinate change, reduces to the Constable–Myers solution and thus confirming that this solution is indeed the holographic dual of a (non-gravitational) gauge theory discussed there. We also show that when one of the parameters of the solution takes a specific value, it reduces, under another coordinate change, to the five-dimensional solution obtained by Csaki and Reece, again confirming its gauge theory interpretation.

Research on Coordinated Robotic Motion Control Based on Fuzzy Decoupling Method in Fluidic Environments

Directory of Open Access Journals (Sweden)

Wei Zhang

2014-01-01

Full Text Available The underwater recovery of autonomous underwater vehicles (AUV is a process of 6-DOF motion control, which is related to characteristics with strong nonlinearity and coupling. In the recovery mission, the vehicle requires high level control accuracy. Considering an AUV called BSAV, this paper established a kinetic model to describe the motion of AUV in the horizontal plane, which consisted of nonlinear equations. On the basis of this model, the main coupling variables were analyzed during recovery. Aiming at the strong coupling problem between the heading control and sway motion, we designed a decoupling compensator based on the fuzzy theory and the decoupling theory. We analyzed to the rules of fuzzy compensation, the input and output membership functions of fuzzy compensator, through compose operation and clear operation of fuzzy reasoning, and obtained decoupling compensation quantity. Simulation results show that the fuzzy decoupling controller effectively reduces the overshoot of the system, and improves the control precision. Through the water tank experiments and analysis of experimental data, the effectiveness and feasibility of AUV recovery movement coordinated control based on fuzzy decoupling method are validated successful, and show that the fuzzy decoupling control method has a high practical value in the recovery mission.

Tourism-Related CO2 Emission and Its Decoupling Effects in China: A Spatiotemporal Perspective

Directory of Open Access Journals (Sweden)

Zi Tang

2018-01-01

Full Text Available The rapid development of the tourism industry has been accompanied by an increase in CO2 emissions and has a certain degree of impact on climate change. This study adopted the bottom-up approach to estimate the spatiotemporal change of CO2 emissions of the tourism industry in China and its 31 provinces over the period 2000–2015. In addition, the decoupling index was applied to analyze the decoupling effects between tourism-related CO2 emissions and tourism economy from 2000 to 2015. The results showed that the total CO2 emissions of the tourism industry rose from 37.95 Mt in 2000 to 100.98 Mt in 2015 with an average annual growth rate of 7.1%. The highest CO2 emissions from the tourism industry occurred in eastern coastal China, whereas the least CO2 emissions were in the west of China. Additionally, the decoupling of CO2 emissions from economic growth in China’s tourism industry had mainly gone through the alternations of negative decoupling and weak decoupling. The decoupling states in most of the Chinese provinces were desirable during the study period. This study may serve as a scientific reference regarding decision-making in the sustainable development of the tourism industry in China.

An improved current control scheme for grid-connected DG unit based distribution system harmonic compensation

DEFF Research Database (Denmark)

He, Jinwei; Wei Li, Yun; Wang, Xiongfei

2013-01-01

In order to utilize DG unit interfacing converters to actively compensate distribution system harmonics, this paper proposes an enhanced current control approach. It seamlessly integrates system harmonic mitigation capabilities with the primary DG power generation function. As the proposed current...... controller has two well decoupled control branches to independently control fundamental and harmonic DG currents, phase-locked loops (PLL) and system harmonic component extractions can be avoided during system harmonic compensation. Moreover, a closed-loop power control scheme is also employed to derive...... the fundamental current reference. The proposed power control scheme effectively eliminates the impacts of steady-state fundamental current tracking errors in the DG units. Thus, an accurate power control is realized even when the harmonic compensation functions are activated. Experimental results from a single...

Semiclassical statistical mechanics of fluids

International Nuclear Information System (INIS)

Singh, Y.; Sinha, S.K.

1981-01-01

The problem of calculating the equilibrium properties of fluids in the semiclassical limit when the quantum effects are small is studied. Particle distribution functions and thermodynamic quantities are defined in terms of the Slater sum and methods for evaluating the Slater sum are discussed. It is shown that the expansion method employing the usual Wigner-Kirkwood or Hemmer-Jancovici series is not suitable to treat the properties of the condensed state. Using the grand canonical ensemble and functional differentiation technique we develop cluster expansion series of the Helmholtz free energy and pair correlation functions. Using topological reduction we transform these series to more compact form involving a renormalized potential or a renormalized Mayer function. Then the convergence of the two series is improved by an optimal choice of the renormalized potential or the Mayer function. Integral equation theories are derived and used to devise perturbation methods. An application of these methods to the calculation of the virial coefficients, thermodynamic properties and the pair correlation function for model fluids is discussed. (orig.)

Analysis of underwater decoupling properties of a locally resonant acoustic metamaterial coating

International Nuclear Information System (INIS)

Huang Ling-Zhi; Xiao Yong; Wen Ji-Hong; Yang Hai-Bin; Wen Xi-Sen

2016-01-01

This paper presents a semi-analytical solution for the vibration and sound radiation of a semi-infinite plate covered by a decoupling layer consisting of locally resonant acoustic metamaterial. Formulations are derived based on a combination use of effective medium theory and the theory of elasticity for the decoupling material. Theoretical results show good agreements between the method developed in this paper and the conventional finite element method (FEM), but the method of this paper is more efficient than FEM. Numerical results also show that system with acoustic metamaterial decoupling layer exhibits significant noise reduction performance at the local resonance frequency of the acoustic metamaterial, and such performance can be ascribed to the vibration suppression of the base plate. It is demonstrated that the effective density of acoustic metamaterial decoupling layer has a great influence on the mechanical impedance of the system. Furthermore, the resonance frequency of locally resonant structure can be effectively predicted by a simple model, and it can be significantly affected by the material properties of the locally resonant structure. (paper)

Semiclassical derivation of a local optical potential for heavy-ion plastic scattering

International Nuclear Information System (INIS)

Donangelo, R.; Qanto, L.F.; Hussein, M.S.

A semiclassical method to determine the contribution to the optical potential in the elastic channel due to the coupling to other processes taking place in heavy-ion collisions is developed. An application is made to the case of coulomb excitation. The lowest order term of our potential is shown to be identical to the quantum mechanical expression of Baltz et al

Decoupling Suspension Controller Based on Magnetic Flux Feedback

Directory of Open Access Journals (Sweden)

Wenqing Zhang

2013-01-01

Full Text Available The suspension module control system model has been established based on MIMO (multiple input and multiple output state feedback linearization. We have completed decoupling between double suspension points, and the new decoupling method has been applied to CMS04 magnetic suspension vehicle in national mid-low-speed maglev experiment field of Tangshan city in China. Double suspension system model is very accurate for investigating stability property of maglev control system. When magnetic flux signal is taken back to the suspension control system, the suspension module’s antijamming capacity for resisting suspension load variety has been proved. Also, the external force interference has been enhanced. As a result, the robustness and stability properties of double-electromagnet suspension control system have been enhanced.

Decoupling suspension controller based on magnetic flux feedback.

Science.gov (United States)

Zhang, Wenqing; Li, Jie; Zhang, Kun; Cui, Peng

2013-01-01

The suspension module control system model has been established based on MIMO (multiple input and multiple output) state feedback linearization. We have completed decoupling between double suspension points, and the new decoupling method has been applied to CMS04 magnetic suspension vehicle in national mid-low-speed maglev experiment field of Tangshan city in China. Double suspension system model is very accurate for investigating stability property of maglev control system. When magnetic flux signal is taken back to the suspension control system, the suspension module's antijamming capacity for resisting suspension load variety has been proved. Also, the external force interference has been enhanced. As a result, the robustness and stability properties of double-electromagnet suspension control system have been enhanced.

Non-decoupling of heavy scalars in cosmology

NARCIS (Netherlands)

Hardeman, Sjoerd Reimer

2012-01-01

The theory describing physics at the highest energy scales likely contains extra dimensions, whose internal degrees of freedom result in many massive field and particles. At accelerator experiments these fields and particles generally decouple from the low energy physics. However, in cosmology

Horizons of semiclassical black holes are cold

International Nuclear Information System (INIS)

Brustein, Ram; Medved, A.J.M.

2014-01-01

We calculate, using our recently proposed semiclassical framework, the quantum state of the Hawking pairs that are produced during the evaporation of a black hole (BH). Our framework adheres to the standard rules of quantum mechanics and incorporates the quantum fluctuations of the collapsing shell spacetime in Hawking’s original calculation, while accounting for back-reaction effects. We argue that the negative-energy Hawking modes need to be regularly integrated out; and so these are effectively subsumed by the BH and, as a result, the number of coherent negative-energy modes N_c_o_h at any given time is parametrically smaller than the total number of the Hawking particles N_t_o_t_a_l emitted during the lifetime of the BH. We find that N_c_o_h is determined by the width of the BH wavefunction and scales as the square root of the BH entropy. We also find that the coherent negative-energy modes are strongly entangled with their positive-energy partners. Previously, we have found that N_c_o_h is also the number of coherent outgoing particles and that information can be continually transferred to the outgoing radiation at a rate set by N_c_o_h. Our current results show that, while the BH is semiclassical, information can be released without jeopardizing the nearly maximal inside-out entanglement and imply that the state of matter near the horizon is approximately the vacuum. The BH firewall proposal, on the other hand, is that the state of matter near the horizon deviates substantially from the vacuum, starting at the Page time. We find that, under the usual assumptions for justifying the formation of a firewall, one does indeed form at the Page time. However, the possible loophole lies in the implicit assumption that the number of strongly entangled pairs can be of the same order of N_t_o_t_a_l

Coupling Mechanism and Decoupled Suspension Control Model of a Half Car

Directory of Open Access Journals (Sweden)

Hailong Zhang

2016-01-01

Full Text Available A structure decoupling control strategy of half-car suspension is proposed to fully decouple the system into independent front and rear quarter-car suspensions in this paper. The coupling mechanism of half-car suspension is firstly revealed and formulated with coupled damping force (CDF in a linear function. Moreover, a novel dual dampers-based controllable quarter-car suspension structure is proposed to realize the independent control of pitch and vertical motions of the half car, in which a newly added controllable damper is suggested to be installed between the lower control arm and connection rod in conventional quarter-car suspension structure. The suggested damper constantly regulates the half-car pitch motion posture in a smooth and steady operation condition meantime achieving the expected completely structure decoupled control of the half-car suspension, by compensating the evolved CDF.

Semiclassical theory of magnetoresistance in positionally disordered organic semiconductors

Science.gov (United States)

Harmon, N. J.; Flatté, M. E.

2012-02-01

A recently introduced percolative theory of unipolar organic magnetoresistance is generalized by treating the hyperfine interaction semiclassically for an arbitrary hopping rate. Compact analytic results for the magnetoresistance are achievable when carrier hopping occurs much more frequently than the hyperfine field precession period. In other regimes the magnetoresistance can be straightforwardly evaluated numerically. Slow and fast hopping magnetoresistance are found to be uniquely characterized by their line shapes. We find that the threshold hopping distance is analogous a phenomenological two-site model's branching parameter, and that the distinction between slow and fast hopping is contingent on the threshold hopping distance.

Quadratic Forms and Semiclassical Eigenfunction Hypothesis for Flat Tori

Science.gov (United States)

T. Sardari, Naser

2018-03-01

Let Q( X) be any integral primitive positive definite quadratic form in k variables, where {k≥4}, and discriminant D. For any integer n, we give an upper bound on the number of integral solutions of Q( X) = n in terms of n, k, and D. As a corollary, we prove a conjecture of Lester and Rudnick on the small scale equidistribution of almost all functions belonging to any orthonormal basis of a given eigenspace of the Laplacian on the flat torus {T^d} for {d≥ 5}. This conjecture is motivated by the work of Berry [2,3] on the semiclassical eigenfunction hypothesis.

Scale-invariant curvature fluctuations from an extended semiclassical gravity

Energy Technology Data Exchange (ETDEWEB)

Pinamonti, Nicola, E-mail: pinamont@dima.unige.it, E-mail: siemssen@dima.unige.it [Dipartimento di Matematica, Università di Genova, Via Dodecaneso 35, 16146 Genova (Italy); INFN Sezione di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Siemssen, Daniel, E-mail: pinamont@dima.unige.it, E-mail: siemssen@dima.unige.it [Dipartimento di Matematica, Università di Genova, Via Dodecaneso 35, 16146 Genova (Italy)

2015-02-15

We present an extension of the semiclassical Einstein equations which couple n-point correlation functions of a stochastic Einstein tensor to the n-point functions of the quantum stress-energy tensor. We apply this extension to calculate the quantum fluctuations during an inflationary period, where we take as a model a massive conformally coupled scalar field on a perturbed de Sitter space and describe how a renormalization independent, almost-scale-invariant power spectrum of the scalar metric perturbation is produced. Furthermore, we discuss how this model yields a natural basis for the calculation of non-Gaussianities of the considered metric fluctuations.

High Field In Vivo 13C Magnetic Resonance Spectroscopy of Brain by Random Radiofrequency Heteronuclear Decoupling and Data Sampling

Science.gov (United States)

Li, Ningzhi; Li, Shizhe; Shen, Jun

2017-06-01

In vivo 13C magnetic resonance spectroscopy (MRS) is a unique and effective tool for studying dynamic human brain metabolism and the cycling of neurotransmitters. One of the major technical challenges for in vivo 13C-MRS is the high radio frequency (RF) power necessary for heteronuclear decoupling. In the common practice of in vivo 13C-MRS, alkanyl carbons are detected in the spectra range of 10-65ppm. The amplitude of decoupling pulses has to be significantly greater than the large one-bond 1H-13C scalar coupling (1JCH=125-145 Hz). Two main proton decoupling methods have been developed: broadband stochastic decoupling and coherent composite or adiabatic pulse decoupling (e.g., WALTZ); the latter is widely used because of its efficiency and superb performance under inhomogeneous B1 field. Because the RF power required for proton decoupling increases quadratically with field strength, in vivo 13C-MRS using coherent decoupling is often limited to low magnetic fields (protons via weak long-range 1H-13C scalar couplings, which can be decoupled using low RF power broadband stochastic decoupling. Recently, the carboxylic/amide 13C-MRS technique using low power random RF heteronuclear decoupling was safely applied to human brain studies at 7T. Here, we review the two major decoupling methods and the carboxylic/amide 13C-MRS with low power decoupling strategy. Further decreases in RF power deposition by frequency-domain windowing and time-domain random under-sampling are also discussed. Low RF power decoupling opens the possibility of performing in vivo 13C experiments of human brain at very high magnetic fields (such as 11.7T), where signal-to-noise ratio as well as spatial and temporal spectral resolution are more favorable than lower fields.

Semiclassical and phase space approaches to dynamic and collisional problems of nuclei

International Nuclear Information System (INIS)

Hasse, R.W.; Gregoire, C.; Remaud, B.; Jaenicke, J.; Schuck, P.

1988-09-01

This article summarises recent work on the semiclassical (Thomas-Fermi like) treatment of nuclear correlations and dynamical problems. After a short outline of hte general technique the nucleon-nucleus optical potential in the doorway approximation (2p-1h and 2h-1p intermediate states) is treated. The imaginary part serves to calculate the energy dependent correction to the real part. The level density parameter, occupation numbers, and the mean free path are discussed. The semiclassical treatment of the nuclear response function is given in detail. Applications to inelastic electron scattering in the quasi-elastic peak region are presented. Analogously, inelastic proton scattering is calculated. Because of the surface absorption this reaction excites the surface response. The imaginary part of the single-particle (hole) potential in the evaluation of the response function introduces a 2p-2h spreading. The missing charge in the longitudinal response is reduced but not all experimental puzzles can be explained. The experience gained in the description of phenomena close to equilibrium serves to construct solutions of the Landau-Vlasov (alias Vlasov-Uehling-Uhlenbeck) equation for the description of non-equilibrium processes encountered in heavy ion reactions

Quantum Dynamical Behaviour in Complex Systems - A Semiclassical Approach

Energy Technology Data Exchange (ETDEWEB)

Ananth, Nandini [Univ. of California, Berkeley, CA (United States)

2008-01-01

One of the biggest challenges in Chemical Dynamics is describing the behavior of complex systems accurately. Classical MD simulations have evolved to a point where calculations involving thousands of atoms are routinely carried out. Capturing coherence, tunneling and other such quantum effects for these systems, however, has proven considerably harder. Semiclassical methods such as the Initial Value Representation (SC-IVR) provide a practical way to include quantum effects while still utilizing only classical trajectory information. For smaller systems, this method has been proven to be most effective, encouraging the hope that it can be extended to deal with a large number of degrees of freedom. Several variations upon the original idea of the SCIVR have been developed to help make these larger calculations more tractable; these range from the simplest, classical limit form, the Linearized IVR (LSC-IVR) to the quantum limit form, the Exact Forward-Backward version (EFB-IVR). In this thesis a method to tune between these limits is described which allows us to choose exactly which degrees of freedom we wish to treat in a more quantum mechanical fashion and to what extent. This formulation is called the Tuning IVR (TIVR). We further describe methodology being developed to evaluate the prefactor term that appears in the IVR formalism. The regular prefactor is composed of the Monodromy matrices (jacobians of the transformation from initial to finial coordinates and momenta) which are time evolved using the Hessian. Standard MD simulations require the potential surfaces and their gradients, but very rarely is there any information on the second derivative. We would like to be able to carry out the SC-IVR calculation without this information too. With this in mind a finite difference scheme to obtain the Hessian on-the-fly is proposed. Wealso apply the IVR formalism to a few problems of current interest. A method to obtain energy eigenvalues accurately for complex

Reconciling semiclassical and Bohmian mechanics. V. Wavepacket dynamics

International Nuclear Information System (INIS)

Poirier, Bill

2008-01-01

In previous articles [B. Poirier J. Chem. Phys. 121, 4501 (2004); C. Trahan and B. Poirier, ibid. 124, 034115 (2006); 124, 034116 (2006); B. Poirier and G. Parlant, J. Phys. Chem. A 111, 10400 (2007)] a bipolar counterpropagating wave decomposition, ψ=ψ + +ψ - , was presented for stationary states ψ of the one-dimensional Schroedinger equation, such that the components ψ ± approach their semiclassical Wentzel-Kramers-Brillouin analogs in the large action limit. The corresponding bipolar quantum trajectories are classical-like and well behaved, even when ψ has many nodes, or is wildly oscillatory. In this paper, the method is generalized for time-dependent wavepacket dynamics applications and applied to several benchmark problems, including multisurface systems with nonadiabatic coupling

Semiclassical regularization of Vlasov equations and wavepackets for nonlinear Schrödinger equations

Science.gov (United States)

Athanassoulis, Agissilaos

2018-03-01

We consider the semiclassical limit of nonlinear Schrödinger equations with initial data that are well localized in both position and momentum (non-parametric wavepackets). We recover the Wigner measure (WM) of the problem, a macroscopic phase-space density which controls the propagation of the physical observables such as mass, energy and momentum. WMs have been used to create effective models for wave propagation in: random media, quantum molecular dynamics, mean field limits, and the propagation of electrons in graphene. In nonlinear settings, the Vlasov-type equations obtained for the WM are often ill-posed on the physically interesting spaces of initial data. In this paper we are able to select the measure-valued solution of the 1  +  1 dimensional Vlasov-Poisson equation which correctly captures the semiclassical limit, thus finally resolving the non-uniqueness in the seminal result of Zhang et al (2012 Comm. Pure Appl. Math. 55 582-632). The same approach is also applied to the Vlasov-Dirac-Benney equation with small wavepacket initial data, extending several known results.

A Simple Differential Modulation Scheme for Quasi-Orthogonal Space-Time Block Codes with Partial Transmit Diversity

Directory of Open Access Journals (Sweden)

Lingyang Song

2007-04-01

Full Text Available We report a simple differential modulation scheme for quasi-orthogonal space-time block codes. A new class of quasi-orthogonal coding structures that can provide partial transmit diversity is presented for various numbers of transmit antennas. Differential encoding and decoding can be simplified for differential Alamouti-like codes by grouping the signals in the transmitted matrix and decoupling the detection of data symbols, respectively. The new scheme can achieve constant amplitude of transmitted signals, and avoid signal constellation expansion; in addition it has a linear signal detector with very low complexity. Simulation results show that these partial-diversity codes can provide very useful results at low SNR for current communication systems. Extension to more than four transmit antennas is also considered.

On a semiclassical analysis of high energy electron diffraction by imperfect crystals: the stacking fault

International Nuclear Information System (INIS)

Smith, A.E.; Chadderton, L.T.; Johnson, E.

1978-01-01

Electron diffraction amplitudes at the lower surface of a displaced sandwich crystal are obtained for the high energy limit in the real space formulation. Using semiclassical methods analytical approximations to a resulting overlap integral - central to the problem - are derived. (Auth.)

Discontinuous Galerkin Time-Domain Analysis of Power-Ground Planes Taking Into Account Decoupling Capacitors

KAUST Repository

Li, Ping; Jiang, Li Jun; Bagci, Hakan

2017-01-01

In this paper, a discontinuous Galerkin time-domain (DGTD) method is developed to analyze the power-ground planes taking into account the decoupling capacitors. In the presence of decoupling capacitors, the whole physical system can be split

Classical, Semi-classical and Quantum Noise

CERN Document Server

Poor, H; Scully, Marlan

2012-01-01

David Middleton was a towering figure of 20th Century engineering and science and one of the founders of statistical communication theory. During the second World War, the young David Middleton, working with Van Fleck, devised the notion of the matched filter, which is the most basic method used for detecting signals in noise. Over the intervening six decades, the contributions of Middleton have become classics. This collection of essays by leading scientists, engineers and colleagues of David are in his honor and reflect the wide  influence that he has had on many fields. Also included is the introduction by Middleton to his forthcoming book, which gives a wonderful view of the field of communication, its history and his own views on the field that he developed over the past 60 years. Focusing on classical noise modeling and applications, Classical, Semi-Classical and Quantum Noise includes coverage of statistical communication theory, non-stationary noise, molecular footprints, noise suppression, Quantum e...

Decoupling economic growth from CO2 emissions: A decomposition analysis of China's household energy consumption

Directory of Open Access Journals (Sweden)

Xiao-Wei Ma

2016-09-01

Full Text Available This paper analyzes Chinese household CO2 emissions in 1994–2012 based on the Logarithmic Mean Divisia Index (LMDI structure decomposition model, and discusses the relationship between household CO2 emissions and economic growth based on a decoupling indicator. The results show that in 1994–2012, household CO2 emissions grew in general and displayed an accelerated growth trend during the early 21st century. Economic growth leading to an increase in energy consumption is the main driving factor of CO2 emission growth (an increase of 1.078 Gt CO2 with cumulative contribution rate of 55.92%, while the decline in energy intensity is the main cause of CO2 emission growth inhibition (0.723 Gt CO2 emission reduction with cumulative contribution rate of 38.27%. Meanwhile, household CO2 emissions are in a weak state of decoupling in general. The change in CO2 emissions caused by population and economic growth shows a weak decoupling and expansive decoupling state, respectively. The CO2 emission change caused by energy intensity is in a state of strong decoupling, and the change caused by energy consumption structure fluctuates between a weak and a strong decoupling state.

Computing Decoupled Residuals for Compact Disc Players

DEFF Research Database (Denmark)

Odgaard, Peter Fogh; Stoustrup, Jakob; Andersen, Palle

2006-01-01

a pair of residuals generated by Compact Disc Player. However, these residuals depend on the performance of position servos in the Compact Disc Player. In other publications of the same authors a pair of decoupled residuals is derived. However, the computation of these alternative residuals has been...

Decomposing the Decoupling of Water Consumption and Economic Growth in China’s Textile Industry

Directory of Open Access Journals (Sweden)

Yi Li

2017-03-01

Full Text Available Unprecedented economic achievement in China’s textile industry (TI has occurred along with rising water consumption. The goal of industrial sustainable development requires the decoupling of economic growth from resource consumption. This paper examines the relationship between water consumption and economic growth, and the internal influence mechanism of China’s TI and its three sub-sectors: the manufacture of textiles (MT sector, the Manufacture of Textile Wearing Apparel, Footwear, and Caps (MTWA sector, and the manufacture of chemical fibers (MCF sector. A decoupling analysis was performed and the Laspeyres decomposition method was applied to the period from 2001 to 2014. We showed that six of the fourteen years analyzed (2003, 2006, 2008, 2009, 2011, and 2013 exhibited a strong decoupling effect and three of the fourteen years (2005, 2007, and 2010 exhibited a weak decoupling effect. Overall, China’s TI experienced a good decoupling between economic growth and water consumption from 2002 to 2014. For the three sub-sectors, the MTWA sector experienced a more significant positive decoupling than the MT and MCF sectors. The decomposition results confirm that the industrial scale factor is the most important driving force of China’s TI water consumption increase, while the water efficiency factor is the most important inhibiting force. The industrial structure adjustment does not significantly affect water consumption. The industrial scale and water use efficiency factors are also the main determinants of change in water consumption for the three sub-sectors.

Quantum screening effects on the electron-ion occurrence scattering time advance in strongly coupled semiclassical plasmas

International Nuclear Information System (INIS)

Song, Mi-Young; Jung, Young-Dae

2003-01-01

Quantum screening effects on the occurrence scattering time advance for elastic electron-ion collisions in strongly coupled semiclassical plasmas are investigated using the second-order eikonal analysis. The electron-ion interaction in strongly coupled semiclassical plasmas is obtained by the pseudopotential model taking into account the plasma screening and quantum effects. It is found that the quantum-mechanical effects significantly reduce the occurrence scattering time advance. It is also found that the occurrence scattering time advance increases with increasing Debye length. It is quite interesting to note that the domain of the maximum occurrence time advance is localized for the forward scattering case. The region of the scaled thermal de Broglie wave length (λ-bar) for the maximum occurrence time advance is found to be 0.4≤λ-bar≤1.4

Decoupling, re-engaging

DEFF Research Database (Denmark)

Rose, Jeremy; Schlichter, Bjarne Rerup

2013-01-01

the life of a major project and the complex demands of managing those fluctuations. We investigate evolving trust relationships in a longitudinal case analysis of a large integrated hospital system implementation for the Faroe Islands. Trust relationships suffered various breakdowns, but the project...... was able to recover and eventually meet its goals. Based on concepts from Giddens’ later work on modernity, we develop two approaches for managing dynamic trust relationships in implementation projects: decoupling and re-engaging....... in the project is contingent upon many factors, is likely to vary over time and should not be taken for granted. Previous studies have identified the relationship between trust and project outcomes and suggested trust-building strategies but have largely ignored the dynamic quality of trust relations through...

Diffraction and angular momentum effects in semiclassical atomic scattering theory

International Nuclear Information System (INIS)

Russek, A.

1979-01-01

The semiclassical scattering theory of Mott and Massey and Ford and Wheeler is here extended to multichannel scattering as occurs at a crossing or pseudocrossing of the transient molecule formed by the colliding atoms. The generalized theory incorporates both interference and diffraction phenomena, but the emphasis in this work is on diffraction. For small-angle scattering, diffraction effects become broader, not narrower, as the collision energy increases: ΔbΔtau > or = h[E/sub inc//(2m)]/sup 1/2/ relates the uncertainties in impact parameter b and reduced scattering angle tau = E/sub inc/theta, and determines the range in b required to resolve a structure in the deflection function of height Δtau. In the kilovolt range of collision energies, the effects of local maxima and minima in the deflection function are washed out, and the Airy-function approximation of Ford and Wheeler is inappropriate to describe the differential cross section. More generally, it is shown that at keV collision energies the stationary-phase approximation, heretofore essential in the reduction to the semiclassical limit, breaks down in the vicinity of a level crossing. An approximate theorem is proposed which remains valid in this region and elsewhere reduces to the standard stationary-phase approximation. Several illustrative examples are considered. A separate development treats the effect on the differential scattering cross section of a change in electronic angular momentum when electronic excitation occurs

Decoupled Power Solution for Dual-input Isolated DC-DC Converters Using Four Quadrants Integrated Transformers (FQIT)

DEFF Research Database (Denmark)

Ouyang, Ziwei; Andersen, Michael A. E.; Thomsen, Ole Cornelius

2012-01-01

) space orthogonal flux is proposed in this paper. And thus a new geometry core and relative winding arrangements are proposed in accordance with the rthogonal flux decoupling technology. Due to the four secondary windings are arranged in a quadratic pattern at the base core plate with the two...... perpendicular primary windings, a name of “four quadrants integrated transformers” (FQIT) is therefore given to the proposed construction. Since the two primary windings are uncoupled, the FQIT allows the two input power stages to transfer the energy into the output load simultaneously or at any...... timemultiplexing scheme, which can optimize the utilization of diversified power energy sources, simplify the system structure, improve the flexibility and reduce the overall cost, so they are attractive for the hybrid renewable power system. Section IV initiates a discussion for the advantages of the FQIT...

Nuclear giant resonances in coordinate space. A semiclassical density functional approach

International Nuclear Information System (INIS)

Gleissl, P.; Brack, M.; Meyer, J.; Quentin, P.

1987-01-01

We discuss the semiclassical description of nuclear giant resonances (GR) using a realistic Skyrme force (SkM*) and complete ETF density functionals. We present monopole (0 + ) eigenmodes of isoscalar (I=0) and isovector (I=1) type, which are in good agreement with experiment, and the corresponding m 1 and m 3 sum rules. We also present the temperature dependence of some typical GR energies (0 + , I=0,1; 1 - , I=1; 2 + , I=0) in 208 Pb

Hamiltonian structure of isospectral deformation equation and semi-classical approximation to factorized S-matrices

International Nuclear Information System (INIS)

Chudnovsky, D.V.; Chudnovsky, G.V.

1980-01-01

We consider semi-classical approximation to factorized S-matrices. We show that this new class of matrices, called s-matrices, defines Hamiltonian structures for isospectral deformation equations. Concrete examples of factorized s-matrices are constructed and they are used to define Hamiltonian structure for general two-dimensional isospectral deformation systems. (orig.)

Semiclassical approach to the quantization of the periodic solutions of the sine-Gordon equation

International Nuclear Information System (INIS)

Ghika, G.; Visinescu, M.

1978-01-01

The periodic solutions of the sine-Gordon equation are proved to be singular. For the semiclassical quantization of the periodic solutions we calculate the fluctuations around them and we use the path integrals in the Gaussian approximation in order to obtain the bound states of the sine-Gordon field equation. (author)

Lattice Boltzmann method and gas-kinetic BGK scheme in the low-Mach number viscous flow simulations

International Nuclear Information System (INIS)

Xu Kun; He Xiaoyi

2003-01-01

Both lattice Boltzmann method (LBM) and the gas-kinetic BGK scheme are based on the numerical discretization of the Boltzmann equation with collisional models, such as, the Bhatnagar-Gross-Krook (BGK) model. LBM tracks limited number of particles and the viscous flow behavior emerges automatically from the intrinsic particle stream and collisions process. On the other hand, the gas-kinetic BGK scheme is a finite volume scheme, where the time-dependent gas distribution function with continuous particle velocity space is constructed and used in the evaluation of the numerical fluxes across cell interfaces. Currently, LBM is mainly used for low Mach number, nearly incompressible flow simulation. For the gas-kinetic scheme, the application is focusing on the high speed compressible flows. In this paper, we are going to compare both schemes in the isothermal low-Mach number flow simulations. The methodology for developing both schemes will be clarified through the introduction of operator splitting Boltzmann model and operator averaging Boltzmann model. From the operator splitting Boltzmann model, the error rooted in many kinetic schemes, which are based on the decoupling of particle transport and collision, can be easily understood. As to the test case, we choose to use the 2D cavity flow since it is one of the most extensively studied cases. Detailed simulation results with different Reynolds numbers, as well as the benchmark solutions, are presented

Mathematical properties of a semi-classical signal analysis method: Noisy signal case

KAUST Repository

Liu, Dayan

2012-08-01

Recently, a new signal analysis method based on a semi-classical approach has been proposed [1]. The main idea in this method is to interpret a signal as a potential of a Schrodinger operator and then to use the discrete spectrum of this operator to analyze the signal. In this paper, we are interested in a mathematical analysis of this method in discrete case considering noisy signals. © 2012 IEEE.

Mathematical properties of a semi-classical signal analysis method: Noisy signal case

KAUST Repository

Liu, Dayan; Laleg-Kirati, Taous-Meriem

2012-01-01

Recently, a new signal analysis method based on a semi-classical approach has been proposed [1]. The main idea in this method is to interpret a signal as a potential of a Schrodinger operator and then to use the discrete spectrum of this operator to analyze the signal. In this paper, we are interested in a mathematical analysis of this method in discrete case considering noisy signals. © 2012 IEEE.

High-order space-time finite element schemes for acoustic and viscodynamic wave equations with temporal decoupling.

Science.gov (United States)

Banks, H T; Birch, Malcolm J; Brewin, Mark P; Greenwald, Stephen E; Hu, Shuhua; Kenz, Zackary R; Kruse, Carola; Maischak, Matthias; Shaw, Simon; Whiteman, John R

2014-04-13

We revisit a method originally introduced by Werder et al. (in Comput. Methods Appl. Mech. Engrg., 190:6685-6708, 2001) for temporally discontinuous Galerkin FEMs applied to a parabolic partial differential equation. In that approach, block systems arise because of the coupling of the spatial systems through inner products of the temporal basis functions. If the spatial finite element space is of dimension D and polynomials of degree r are used in time, the block system has dimension ( r + 1) D and is usually regarded as being too large when r > 1. Werder et al. found that the space-time coupling matrices are diagonalizable over [Formula: see text] for r ⩽ 100, and this means that the time-coupled computations within a time step can actually be decoupled. By using either continuous Galerkin or spectral element methods in space, we apply this DG-in-time methodology, for the first time, to second-order wave equations including elastodynamics with and without Kelvin-Voigt and Maxwell-Zener viscoelasticity. An example set of numerical results is given to demonstrate the favourable effect on error and computational work of the moderately high-order (up to degree 7) temporal and spatio-temporal approximations, and we also touch on an application of this method to an ambitious problem related to the diagnosis of coronary artery disease. Copyright © 2014 The Authors. International Journal for Numerical Methods in Engineering published by John Wiley & Sons Ltd.

Natural relations and Appelquist-Carazzone decoupling theorem

International Nuclear Information System (INIS)

Grzadkowski, B.; Krawczyk, P.; Pokorski, S.

1984-01-01

It is pointed out that in some cases violation of the Appelquist-Carazzone decoupling theorem in spontaneously broken gauge theories is related to the presence in such theories of the so-called natural zeroth-order relations. In this context heavy-fermion effects in the Glashow-Salam-Weinberg model are discussed

Semiclassical treatment of inelastic collisions between electrons and highly ionized atoms

International Nuclear Information System (INIS)

Frasier, S.M.

1984-01-01

The thesis is concerned with the calculation of excitation cross sections of ions by electron impact at intermediate energies in the limit of Z >> N/sub b/, where Z is the atomic number and N/sub b/ is the number of bound electrons. A semiclassical procedure is developed for calculating total cross sections using analytic bound states and averaged free electron wave functions derived in the second eikonal approximation. The analytic bound states are derived assuming a screened Coulomb potential and using orbital energies obtained from Hartree-Fock calculations. The functional form of the bound states reduces naturally to the hydrogen atom functions in the limit Z → infinity. The free electron functions used are semiclassical solutions to the free electron Schroedinger equation with a screened Coulomb potential. An exact solution is obtained in the second eikonal approximation, including all classical path contributions. This solution is averaged to extract the focusing and acceleration effects resulting from the long range Coulomb potential of the ion. The results are presented in the form of Born-like cross section formulae and demonstrate the appropriate correction of the Born cross section which arises from the acceleration and focusing of the free electrons by the long range Coulomb potential. Comparison is made with the Coulomb-Born results; the results agree to within 10% in most cases

Semiclassical expansion of quantum characteristics for many-body potential scattering problem

International Nuclear Information System (INIS)

Krivoruchenko, M.I.; Fuchs, C.; Faessler, A.

2007-01-01

In quantum mechanics, systems can be described in phase space in terms of the Wigner function and the star-product operation. Quantum characteristics, which appear in the Heisenberg picture as the Weyl's symbols of operators of canonical coordinates and momenta, can be used to solve the evolution equations for symbols of other operators acting in the Hilbert space. To any fixed order in the Planck's constant, many-body potential scattering problem simplifies to a statistical-mechanical problem of computing an ensemble of quantum characteristics and their derivatives with respect to the initial canonical coordinates and momenta. The reduction to a system of ordinary differential equations pertains rigorously at any fixed order in ℎ. We present semiclassical expansion of quantum characteristics for many-body scattering problem and provide tools for calculation of average values of time-dependent physical observables and cross sections. The method of quantum characteristics admits the consistent incorporation of specific quantum effects, such as non-locality and coherence in propagation of particles, into the semiclassical transport models. We formulate the principle of stationary action for quantum Hamilton's equations and give quantum-mechanical extensions of the Liouville theorem on conservation of the phase-space volume and the Poincare theorem on conservation of 2p-forms. The lowest order quantum corrections to the Kepler periodic orbits are constructed. These corrections show the resonance behavior. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

Decoupled simulations of offshore wind turbines with reduced rotor loads and aerodynamic damping

Directory of Open Access Journals (Sweden)

S. Schafhirt

2018-02-01

Full Text Available Decoupled load simulations are a computationally efficient method to perform a dynamic analysis of an offshore wind turbine. Modelling the dynamic interactions between rotor and support structure, especially the damping caused by the rotating rotor, is of importance, since it influences the structural response significantly and has a major impact on estimating fatigue lifetime. Linear damping is usually used for this purpose, but experimentally and analytically derived formulas to calculate an aerodynamic damping ratio often show discrepancies to measurement and simulation data. In this study decoupled simulation methods with reduced and full rotor loads are compared to an integrated simulation. The accuracy of decoupled methods is evaluated and an optimization is performed to obtain aerodynamic damping ratios for different wind speeds that provide the best results with respect to variance and equivalent fatigue loads at distinct output locations. Results show that aerodynamic damping is not linear, but it is possible to match desired output using decoupled models. Moreover, damping ratios obtained from the empirical study suggest that aerodynamic damping increases for higher wind speeds.

Power corrections from decoupling of the charm quark

Science.gov (United States)

Knechtli, Francesco; Korzec, Tomasz; Leder, Björn; Moir, Graham; Alpha Collaboration

2017-11-01

Decoupling of heavy quarks at low energies can be described by means of an effective theory as shown by S. Weinberg in Ref. [1]. We study the decoupling of the charm quark by lattice simulations. We simulate a model, QCD with two degenerate charm quarks. In this case the leading order term in the effective theory is a pure gauge theory. The higher order terms are proportional to inverse powers of the charm quark mass M starting at M-2. Ratios of hadronic scales are equal to their value in the pure gauge theory up to power corrections. We show, by precise measurements of ratios of scales defined from the Wilson flow, that these corrections are very small and that they can be described by a term proportional to M-2 down to masses in the region of the charm quark mass.

On semi-classical questions related to signal analysis

KAUST Repository

Helffer, Bernard

2011-12-01

This study explores the reconstruction of a signal using spectral quantities associated with some self-adjoint realization of an h-dependent Schrödinger operator -h2(d2/dx2)-y(x), h>0, when the parameter h tends to 0. Theoretical results in semi-classical analysis are proved. Some numerical results are also presented. We first consider as a toy model the sech2 function. Then we study a real signal given by arterial blood pressure measurements. This approach seems to be very promising in signal analysis. Indeed it provides new spectral quantities that can give relevant information on some signals as it is the case for arterial blood pressure signal. © 2011 - IOS Press and the authors. All rights reserved.

Improved Decoupling for 13C coil Arrays Using Non-Conventional Matching and Preamplifier Impedance

DEFF Research Database (Denmark)

Sanchez, Juan Diego; Johansen, Daniel Højrup; Hansen, Rie Beck

In this study, we describe a method to obtain improved preamplifier decoupling for receive-only coils. The method relies on the better decoupling obtained when coils are matched to an impedance higher than 50 . Preamplifiers with inductive imaginary impedance and low real impedance, increase...

Semi-classical analysis of scattering of deformed heavy-ions below the Coulomb barrier

International Nuclear Information System (INIS)

Johnson, R.C.; Roberts, E.J.; Sukumar, C.V.; Brink, D.M.

1995-01-01

Polarization observables for the sub-Coulomb elastic scattering of a quadrupole deformed projectile of spin 3/2 from a spinless spherical target are evaluated using a new semi-classical method based on a path-integral formalism. Analytic expressions are obtained which agree well with coupled channels calculations and which predict definite deviations from the ''shape-effect'' relations for tensor analyzing powers

Calculation of the spin-isospin response functions in an extended semi-classical theory

International Nuclear Information System (INIS)

Chanfray, G.

1987-01-01

We present a semi-classical calculation of the spin isospin response-functions beyond Thomas-Fermi theory. We show that surface-peaked ℎ 2 corrections reduce the collective effects predicted by Thomas-Fermi calculations. These effects, small for a volume response, become important for surface responses probed by hadrons. This yields a considerable improvement of the agreement with the (p, p') Los Alamos data

Benchmark of AC and DC Active Power Decoupling Circuits for Second-Order Harmonic Mitigation in Kilowatt-Scale Single-Phase Inverters

DEFF Research Database (Denmark)

Qin, Zian; Tang, Yi; Loh, Poh Chiang

2016-01-01

efficiency and high power density is identified and comprehensively studied, and the commercially available film capacitors, the circuit topologies, and the control strategies adopted for active power decoupling are all taken into account. Then, an adaptive decoupling voltage control method is proposed...... to further improve the performance of dc decoupling in terms of efficiency and reliability. The feasibility and superiority of the identified solution for active power decoupling together with the proposed adaptive decoupling voltage control method are finally verified by both the simulation and experimental......This paper presents the benchmark study of ac and dc active power decoupling circuits for second order harmonic mitigation in kW scale single-phase inverters. First of all, a brief comparison of recently reported active power decoupling circuits is given, and the best solution that can achieve high...

Damping in nuclear collective modes in a semiclassical fluid-dynamical approximation

International Nuclear Information System (INIS)

Vignolo, C.E.; Hernandez, Susana

1989-01-01

A semiclassical fluiddynamical model based on an usual scaling approximation (SCA) was extended to investigate the role of one and two-body dissipation in the widths of nuclear collective modes. The competition between one and two-body viscosity in: i) the collisionless (elastic) limit; ii) the hydrodynamical case and iii) the general viscoelastic regime is examined over the whole range of nuclear collision time scales. Numerical solutions are investigated for the first magnetic 2 - twist mode in 208 Pb. (Author) [es

Semiclassical neutral atom as a reference system in density functional theory.

Science.gov (United States)

Constantin, Lucian A; Fabiano, E; Laricchia, S; Della Sala, F

2011-05-06

We use the asymptotic expansions of the semiclassical neutral atom as a reference system in density functional theory to construct accurate generalized gradient approximations (GGAs) for the exchange-correlation and kinetic energies without any empiricism. These asymptotic functionals are among the most accurate GGAs for molecular systems, perform well for solid state, and overcome current GGA state of the art in frozen density embedding calculations. Our results also provide evidence for the conjointness conjecture between exchange and kinetic energies of atomic systems.

Linearized semiclassical initial value time correlation functions with maximum entropy analytic continuation.

Science.gov (United States)

Liu, Jian; Miller, William H

2008-09-28

The maximum entropy analytic continuation (MEAC) method is used to extend the range of accuracy of the linearized semiclassical initial value representation (LSC-IVR)/classical Wigner approximation for real time correlation functions. LSC-IVR provides a very effective "prior" for the MEAC procedure since it is very good for short times, exact for all time and temperature for harmonic potentials (even for correlation functions of nonlinear operators), and becomes exact in the classical high temperature limit. This combined MEAC+LSC/IVR approach is applied here to two highly nonlinear dynamical systems, a pure quartic potential in one dimensional and liquid para-hydrogen at two thermal state points (25 and 14 K under nearly zero external pressure). The former example shows the MEAC procedure to be a very significant enhancement of the LSC-IVR for correlation functions of both linear and nonlinear operators, and especially at low temperature where semiclassical approximations are least accurate. For liquid para-hydrogen, the LSC-IVR is seen already to be excellent at T=25 K, but the MEAC procedure produces a significant correction at the lower temperature (T=14 K). Comparisons are also made as to how the MEAC procedure is able to provide corrections for other trajectory-based dynamical approximations when used as priors.

Decoupling control of vehicle chassis system based on neural network inverse system

Science.gov (United States)

Wang, Chunyan; Zhao, Wanzhong; Luan, Zhongkai; Gao, Qi; Deng, Ke

2018-06-01

Steering and suspension are two important subsystems affecting the handling stability and riding comfort of the chassis system. In order to avoid the interference and coupling of the control channels between active front steering (AFS) and active suspension subsystems (ASS), this paper presents a composite decoupling control method, which consists of a neural network inverse system and a robust controller. The neural network inverse system is composed of a static neural network with several integrators and state feedback of the original chassis system to approach the inverse system of the nonlinear systems. The existence of the inverse system for the chassis system is proved by the reversibility derivation of Interactor algorithm. The robust controller is based on the internal model control (IMC), which is designed to improve the robustness and anti-interference of the decoupled system by adding a pre-compensation controller to the pseudo linear system. The results of the simulation and vehicle test show that the proposed decoupling controller has excellent decoupling performance, which can transform the multivariable system into a number of single input and single output systems, and eliminate the mutual influence and interference. Furthermore, it has satisfactory tracking capability and robust performance, which can improve the comprehensive performance of the chassis system.

Anisotropic solutions by gravitational decoupling

Science.gov (United States)

Ovalle, J.; Casadio, R.; da Rocha, R.; Sotomayor, A.

2018-02-01

We investigate the extension of isotropic interior solutions for static self-gravitating systems to include the effects of anisotropic spherically symmetric gravitational sources by means of the gravitational decoupling realised via the minimal geometric deformation approach. In particular, the matching conditions at the surface of the star with the outer Schwarzschild space-time are studied in great detail, and we describe how to generate, from a single physically acceptable isotropic solution, new families of anisotropic solutions whose physical acceptability is also inherited from their isotropic parent.

Anisotropic solutions by gravitational decoupling

Energy Technology Data Exchange (ETDEWEB)

Ovalle, J. [Silesian University in Opava, Institute of Physics and Research Centre of Theoretical Physics and Astrophysics, Faculty of Philosophy and Science, Opava (Czech Republic); Universidad Simon Bolivar, Departamento de Fisica, Caracas (Venezuela, Bolivarian Republic of); Casadio, R. [Alma Mater Universita di Bologna, Dipartimento di Fisica e Astronomia, Bologna (Italy); Istituto Nazionale di Fisica Nucleare, Bologna (Italy); Rocha, R. da [Universidade Federal do ABC (UFABC), Centro de Matematica, Computacao e Cognicao, Santo Andre, SP (Brazil); Sotomayor, A. [Universidad de Antofagasta, Departamento de Matematicas, Antofagasta (Chile)

2018-02-15

We investigate the extension of isotropic interior solutions for static self-gravitating systems to include the effects of anisotropic spherically symmetric gravitational sources by means of the gravitational decoupling realised via the minimal geometric deformation approach. In particular, the matching conditions at the surface of the star with the outer Schwarzschild space-time are studied in great detail, and we describe how to generate, from a single physically acceptable isotropic solution, new families of anisotropic solutions whose physical acceptability is also inherited from their isotropic parent. (orig.)

Fourier transform methods for calculating action variables and semiclassical eigenvalues for coupled oscillator systems

International Nuclear Information System (INIS)

Eaker, C.W.; Schatz, G.C.; De Leon, N.; Heller, E.J.

1984-01-01

Two methods for calculating the good action variables and semiclassical eigenvalues for coupled oscillator systems are presented, both of which relate the actions to the coefficients appearing in the Fourier representation of the normal coordinates and momenta. The two methods differ in that one is based on the exact expression for the actions together with the EBK semiclassical quantization condition while the other is derived from the Sorbie--Handy (SH) approximation to the actions. However, they are also very similar in that the actions in both methods are related to the same set of Fourier coefficients and both require determining the perturbed frequencies in calculating actions. These frequencies are also determined from the Fourier representations, which means that the actions in both methods are determined from information entirely contained in the Fourier expansion of the coordinates and momenta. We show how these expansions can very conveniently be obtained from fast Fourier transform (FFT) methods and that numerical filtering methods can be used to remove spurious Fourier components associated with the finite trajectory integration duration. In the case of the SH based method, we find that the use of filtering enables us to relax the usual periodicity requirement on the calculated trajectory. Application to two standard Henon--Heiles models is considered and both are shown to give semiclassical eigenvalues in good agreement with previous calculations for nondegenerate and 1:1 resonant systems. In comparing the two methods, we find that although the exact method is quite general in its ability to be used for systems exhibiting complex resonant behavior, it converges more slowly with increasing trajectory integration duration and is more sensitive to the algorithm for choosing perturbed frequencies than the SH based method

Time dependent semiclassical tunneling through one dimensional barriers using only real valued trajectories

International Nuclear Information System (INIS)

Herman, Michael F.

2015-01-01

The time independent semiclassical treatment of barrier tunneling has been understood for a very long time. Several semiclassical approaches to time dependent tunneling through barriers have also been presented. These typically involve trajectories for which the position variable is a complex function of time. In this paper, a method is presented that uses only real valued trajectories, thus avoiding the complications that can arise when complex trajectories are employed. This is accomplished by expressing the time dependent wave packet as an integration over momentum. The action function in the exponent in this expression is expanded to second order in the momentum. The expansion is around the momentum, p 0 * , at which the derivative of the real part of the action is zero. The resulting Gaussian integral is then taken. The stationary phase approximation requires that the derivative of the full action is zero at the expansion point, and this leads to a complex initial momentum and complex tunneling trajectories. The “pseudo-stationary phase” approximation employed in this work results in real values for the initial momentum and real valued trajectories. The transmission probabilities obtained are found to be in good agreement with exact quantum results

Time dependent semiclassical tunneling through one dimensional barriers using only real valued trajectories

Energy Technology Data Exchange (ETDEWEB)

Herman, Michael F. [Department of Chemistry, Tulane University, New Orleans, Louisiana 70118 (United States)

2015-10-28

The time independent semiclassical treatment of barrier tunneling has been understood for a very long time. Several semiclassical approaches to time dependent tunneling through barriers have also been presented. These typically involve trajectories for which the position variable is a complex function of time. In this paper, a method is presented that uses only real valued trajectories, thus avoiding the complications that can arise when complex trajectories are employed. This is accomplished by expressing the time dependent wave packet as an integration over momentum. The action function in the exponent in this expression is expanded to second order in the momentum. The expansion is around the momentum, p{sub 0{sup *}}, at which the derivative of the real part of the action is zero. The resulting Gaussian integral is then taken. The stationary phase approximation requires that the derivative of the full action is zero at the expansion point, and this leads to a complex initial momentum and complex tunneling trajectories. The “pseudo-stationary phase” approximation employed in this work results in real values for the initial momentum and real valued trajectories. The transmission probabilities obtained are found to be in good agreement with exact quantum results.

Semiclassical spectral quantization: Application to two and four coupled molecular degrees of freedom

International Nuclear Information System (INIS)

De Leon, N.; Heller, E.J.

1984-01-01

Semiclassical quantization of the quasiperiodic vibrational motion of molecules is usually based on Einstein--Brillouin--Keller (EBK) conditions for the quantization of the classical actions. Explicit use of the EBK conditions for molecular systems of K degrees of freedom requires K quantization conditions. Therefore, explicit use of the EBK conditions becomes increasingly difficult if not impossible for polyatomic systems of three or more degrees of freedom. In this paper we propose a semiclassical quantization method which makes explicit use of phase coherence of the de Broglie wave associated with the trajectory rather than the EBK conditions. We show that taking advantage of phase coherence reduces the K quantization conditions to a single quantum condition: regardless of the number of degrees of freedom. For reasons that will become obvious we call this method ''spectral quantization.'' Polyatomic vibrational wave functions and energy eigenvalues are generated from quasiperiodic classical trajectories. The spectral method is applied to an ABA linear triatomic molecule with two degrees of freedom and to an anharmonic model of the molecule cyanoacetylene. The usefulness of the technique is demonstrated in this latter calculation since the cyanoacetylene model will have four coupled vibrational degrees of freedom

Semi-classical approaches to the phase space evolutions in intermediate energy heavy ion collisions

Energy Technology Data Exchange (ETDEWEB)

Remaud, B; Sebille, F; Raffray, Y; Gregoire, C; Vinet, L

1986-01-06

The properties of semi-classical phase space evolution equations - as the Vlasov/Boltzmann equations - are discussed in the context of the heavy ion reaction theory at intermediate energies (from 10 to 100 MeV per nucleon). The generalized coherent state set is shown to form a (over) complete basis for the phase space; then every solution of the Vlasov/Boltzmann equations can be defined as a convolution product of the generalized coherent state basis by an appropriate weight function w. The uniform approximation for w is shown to provide an accurate semi-classical description of fermion systems in their ground state: the examples of fermions in a harmonic well and of cold nuclei are discussed. The solution of the Vlasov equation amounts to follow the time evolution of the coherent states which play the role of a moving basis. For the Boltzmann equation, the collision term is taken into account by explicit or implicit variations of the function w. Typical applications are discussed: nuclear response to the giant monopole resonance excitation, fast nucleon emission in heavy-ion reactions. (orig.).

Comparison among Magnus/Floquet/Fer expansion schemes in solid-state NMR

Science.gov (United States)

Takegoshi, K.; Miyazawa, Norihiro; Sharma, Kshama; Madhu, P. K.

2015-04-01

We here revisit expansion schemes used in nuclear magnetic resonance (NMR) for the calculation of effective Hamiltonians and propagators, namely, Magnus, Floquet, and Fer expansions. While all the expansion schemes are powerful methods there are subtle differences among them. To understand the differences, we performed explicit calculation for heteronuclear dipolar decoupling, cross-polarization, and rotary-resonance experiments in solid-state NMR. As the propagator from the Fer expansion takes the form of a product of sub-propagators, it enables us to appreciate effects of time-evolution under Hamiltonians with different orders separately. While 0th-order average Hamiltonian is the same for the three expansion schemes with the three cases examined, there is a case that the 2nd-order term for the Magnus/Floquet expansion is different from that obtained with the Fer expansion. The difference arises due to the separation of the 0th-order term in the Fer expansion. The separation enables us to appreciate time-evolution under the 0th-order average Hamiltonian, however, for that purpose, we use a so-called left-running Fer expansion. Comparison between the left-running Fer expansion and the Magnus expansion indicates that the sign of the odd orders in Magnus may better be reversed if one would like to consider its effect in order.

Comparison among Magnus/Floquet/Fer expansion schemes in solid-state NMR

International Nuclear Information System (INIS)

Takegoshi, K.; Miyazawa, Norihiro; Sharma, Kshama; Madhu, P. K.

2015-01-01

We here revisit expansion schemes used in nuclear magnetic resonance (NMR) for the calculation of effective Hamiltonians and propagators, namely, Magnus, Floquet, and Fer expansions. While all the expansion schemes are powerful methods there are subtle differences among them. To understand the differences, we performed explicit calculation for heteronuclear dipolar decoupling, cross-polarization, and rotary-resonance experiments in solid-state NMR. As the propagator from the Fer expansion takes the form of a product of sub-propagators, it enables us to appreciate effects of time-evolution under Hamiltonians with different orders separately. While 0th-order average Hamiltonian is the same for the three expansion schemes with the three cases examined, there is a case that the 2nd-order term for the Magnus/Floquet expansion is different from that obtained with the Fer expansion. The difference arises due to the separation of the 0th-order term in the Fer expansion. The separation enables us to appreciate time-evolution under the 0th-order average Hamiltonian, however, for that purpose, we use a so-called left-running Fer expansion. Comparison between the left-running Fer expansion and the Magnus expansion indicates that the sign of the odd orders in Magnus may better be reversed if one would like to consider its effect in order

Comparison among Magnus/Floquet/Fer expansion schemes in solid-state NMR

Energy Technology Data Exchange (ETDEWEB)

Takegoshi, K., E-mail: takeyan@kuchem.kyoto-u.ac.jp; Miyazawa, Norihiro [Division of Chemistry, Graduate School of Science, Kyoto University, 606-8502 Kyoto (Japan); Sharma, Kshama [TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsingi, Hyderabad 500 075 (India); Madhu, P. K. [TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsingi, Hyderabad 500 075 (India); Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005 (India)

2015-04-07

We here revisit expansion schemes used in nuclear magnetic resonance (NMR) for the calculation of effective Hamiltonians and propagators, namely, Magnus, Floquet, and Fer expansions. While all the expansion schemes are powerful methods there are subtle differences among them. To understand the differences, we performed explicit calculation for heteronuclear dipolar decoupling, cross-polarization, and rotary-resonance experiments in solid-state NMR. As the propagator from the Fer expansion takes the form of a product of sub-propagators, it enables us to appreciate effects of time-evolution under Hamiltonians with different orders separately. While 0th-order average Hamiltonian is the same for the three expansion schemes with the three cases examined, there is a case that the 2nd-order term for the Magnus/Floquet expansion is different from that obtained with the Fer expansion. The difference arises due to the separation of the 0th-order term in the Fer expansion. The separation enables us to appreciate time-evolution under the 0th-order average Hamiltonian, however, for that purpose, we use a so-called left-running Fer expansion. Comparison between the left-running Fer expansion and the Magnus expansion indicates that the sign of the odd orders in Magnus may better be reversed if one would like to consider its effect in order.

Oblique-wing research airplane motion simulation with decoupling control laws

Science.gov (United States)

Kempel, Robert W.; Mc Neill, Walter E.; Maine, Trindel A.

1988-01-01

A large piloted vertical motion simulator was used to assess the performance of a preliminary decoupling control law for an early version of the F-8 oblique wing research demonstrator airplane. Evaluations were performed for five discrete flight conditions, ranging from low-altitude subsonic Mach numbers to moderate-altitude supersonic Mach numbers. Asymmetric sideforce as a function of angle of attack was found to be the primary cause of both the lateral acceleration noted in pitch and the tendency to roll into left turns and out of right turns. The flight control system was shown to be effective in generally decoupling the airplane and reducing the lateral acceleration in pitch maneuvers.

Multiple estimation channel decoupling and optimization method based on inverse system

Science.gov (United States)

Wu, Peng; Mu, Rongjun; Zhang, Xin; Deng, Yanpeng

2018-03-01

This paper addressed the intelligent autonomous navigation request of intelligent deformation missile, based on the intelligent deformation missile dynamics and kinematics modeling, navigation subsystem solution method and error modeling, and then focuses on the corresponding data fusion and decision fusion technology, decouples the sensitive channel of the filter input through the inverse system of design dynamics to reduce the influence of sudden change of the measurement information on the filter input. Then carrying out a series of simulation experiments, which verified the feasibility of the inverse system decoupling algorithm effectiveness.

Determination of Optimal Opening Scheme for Electromagnetic Loop Networks Based on Fuzzy Analytic Hierarchy Process

Directory of Open Access Journals (Sweden)

Yang Li

2016-01-01

Full Text Available Studying optimization and decision for opening electromagnetic loop networks plays an important role in planning and operation of power grids. First, the basic principle of fuzzy analytic hierarchy process (FAHP is introduced, and then an improved FAHP-based scheme evaluation method is proposed for decoupling electromagnetic loop networks based on a set of indicators reflecting the performance of the candidate schemes. The proposed method combines the advantages of analytic hierarchy process (AHP and fuzzy comprehensive evaluation. On the one hand, AHP effectively combines qualitative and quantitative analysis to ensure the rationality of the evaluation model; on the other hand, the judgment matrix and qualitative indicators are expressed with trapezoidal fuzzy numbers to make decision-making more realistic. The effectiveness of the proposed method is validated by the application results on the real power system of Liaoning province of China.

SAM revisited: absorptive uniform semiclassical approximation and application to heavy-ion elastic scattering

International Nuclear Information System (INIS)

Pato, M.P.; Hussein, M.S.

1989-06-01

The Uniform Semiclassical Approximation is modified to take into account absorption. Symbol calculus and pseudodifferential operators techniques are employed for the purpose. The resulting theory, very similar to the one developed by Frahn and Gross permits the decomposition of the near-side and far-side amplitudes into diffractive and refractive components. Application to several heavy-ion systems at intermediate energies is made. (author) [pt

Focal points and the phase of the semi-classical propagator

International Nuclear Information System (INIS)

Levit, S.; Moehring, K.; Smilansky, U.; Dreyfus, T.

1977-01-01

The relation between the phase of the semi-classical propagator and the number of times the classical trajectory is reflected from a caustic is discussed. It is shown that the accepted prescription based on Morse's focal point theorem is valid only for a restricted class of problems (coordinate representation and a positive definite mass tensor). A more general method to evaluate the phase is derived. It applies to all problems of physical interest involving the most general representations (mixed coordinate and momentum) and complicated Hamiltonian functions. The result is of particular relevance for the classical S-matrix. (author)

Decoupling Identification for Serial Two-Link Two-Inertia System

Science.gov (United States)

Oaki, Junji; Adachi, Shuichi

The purpose of our study is to develop a precise model by applying the technique of system identification for the model-based control of a nonlinear robot arm, under taking joint-elasticity into consideration. We previously proposed a systematic identification method, called “decoupling identification,” for a “SCARA-type” planar two-link robot arm with elastic joints caused by the Harmonic-drive® reduction gears. The proposed method serves as an extension of the conventional rigid-joint-model-based identification. The robot arm is treated as a serial two-link two-inertia system with nonlinearity. The decoupling identification method using link-accelerometer signals enables the serial two-link two-inertia system to be divided into two linear one-link two-inertia systems. The MATLAB®'s commands for state-space model estimation are utilized in the proposed method. Physical parameters such as motor inertias, link inertias, joint-friction coefficients, and joint-spring coefficients are estimated through the identified one-link two-inertia systems using a gray-box approach. This paper describes accuracy evaluations using the two-link arm for the decoupling identification method under introducing closed-loop-controlled elements and varying amplitude-setup of identification-input. Experimental results show that the identification method also works with closed-loop-controlled elements. Therefore, the identification method is applicable to a “PUMA-type” vertical robot arm under gravity.

Benchmark of AC and DC active power decoupling circuits for second-order harmonic mitigation in kW-scale single-phase inverters

DEFF Research Database (Denmark)

Qin, Zian; Tang, Yi; Loh, Poh Chiang

2015-01-01

studied, where the commercially available film capacitors, circuit topologies, and control strategies for active power decoupling are all taken into account. Then, an adaptive decoupling voltage control method is proposed to further improve the performance of dc decoupling in terms of efficiency...... and reliability. The feasibility and superiority of the identified solution for active power decoupling together with the proposed adaptive decoupling voltage control method are finally verified by both the experimental results obtained on a 2 kW single-phase inverter.......This paper presents the benchmark study of ac and dc active power decoupling circuits for second-order harmonic mitigation in kW-scale single-phase inverters. First of all, the best solutions of active power decoupling to achieve high efficiency and power density are identified and comprehensively...

1+1+2 gravitational perturbations on LRS class II spacetimes: decoupling gravito-electromagnetic tensor harmonic amplitudes

International Nuclear Information System (INIS)

Burston, R B

2008-01-01

This is the first in a series of papers which considers gauge-invariant and covariant gravitational perturbations on arbitrary vacuum locally rotationally symmetric (LRS) class II spacetimes. Ultimately, we derive four decoupled equations governing four specific combinations of the gravito-electromagnetic (GEM) 2-tensor harmonic amplitudes. We use the gauge-invariant and covariant 1+1+2 formalism which Clarkson and Barrett (2003 Class. Quantum Grav. 20 3855) developed for analysis of vacuum Schwarzschild perturbations. In particular we focus on the first-order 1+1+2 GEM system and use linear algebra techniques suitable for exploiting its structure. Consequently, we express the GEM system new 1+1+2 complex form by choosing new complex GEM tensors, which is conducive to decoupling. We then show how to derive a gauge-invariant and covariant decoupled equation governing a newly defined complex GEM 2-tensor. Finally, the GEM 2-tensor is expanded in terms of arbitrary tensor harmonics and linear algebra is used once again to decouple the system further into four real decoupled equations

Reliability-based optimal structural design by the decoupling approach

International Nuclear Information System (INIS)

Royset, J.O.; Der Kiureghian, A.; Polak, E.

2001-01-01

A decoupling approach for solving optimal structural design problems involving reliability terms in the objective function, the constraint set or both is discussed and extended. The approach employs a reformulation of each problem, in which reliability terms are replaced by deterministic functions. The reformulated problems can be solved by existing semi-infinite optimization algorithms and computational reliability methods. It is shown that the reformulated problems produce solutions that are identical to those of the original problems when the limit-state functions defining the reliability problem are affine. For nonaffine limit-state functions, approximate solutions are obtained by solving series of reformulated problems. An important advantage of the approach is that the required reliability and optimization calculations are completely decoupled, thus allowing flexibility in the choice of the optimization algorithm and the reliability computation method

Cladding technique for development of Ag-In-Cd decoupler

International Nuclear Information System (INIS)

Teshigawara, M.; Harada, M.; Saito, S.; Kikuchi, K.; Kogawa, H.; Ikeda, Y.; Kawai, M.; Kurishita, H.; Konashi, K.

2005-01-01

To develop a Ag (silver)-In (indium)-Cd (cadmium) alloy decoupler, a method is needed to bond the decoupler between two plates of the Al alloy (A6061-T6). We found that a better HIP condition was temperature, pressure and holding time at 803 K, 100 MPa and 1 h, respectively, for small test pieces (φ 22 mm in diam. x 5 mm in height). Especially, a sandwich case (a Ag-In plate with thickness of 0.5 mm between two Ag-Cd plates with thickness of 1.25 mm) gave easier (or better) bonding results. Though a hardened layer is found in the bonding layer, the rupture strength of the bonding layer is more than 30 MPa, which is higher than the design stress in our application

Decoupling Principle Analysis and Development of a Parallel Three-Dimensional Force Sensor.

Science.gov (United States)

Zhao, Yanzhi; Jiao, Leihao; Weng, Dacheng; Zhang, Dan; Zheng, Rencheng

2016-09-15

In the development of the multi-dimensional force sensor, dimension coupling is the ubiquitous factor restricting the improvement of the measurement accuracy. To effectively reduce the influence of dimension coupling on the parallel multi-dimensional force sensor, a novel parallel three-dimensional force sensor is proposed using a mechanical decoupling principle, and the influence of the friction on dimension coupling is effectively reduced by making the friction rolling instead of sliding friction. In this paper, the mathematical model is established by combining with the structure model of the parallel three-dimensional force sensor, and the modeling and analysis of mechanical decoupling are carried out. The coupling degree (ε) of the designed sensor is defined and calculated, and the calculation results show that the mechanical decoupling parallel structure of the sensor possesses good decoupling performance. A prototype of the parallel three-dimensional force sensor was developed, and FEM analysis was carried out. The load calibration and data acquisition experiment system are built, and then calibration experiments were done. According to the calibration experiments, the measurement accuracy is less than 2.86% and the coupling accuracy is less than 3.02%. The experimental results show that the sensor system possesses high measuring accuracy, which provides a basis for the applied research of the parallel multi-dimensional force sensor.

Note: Decoupling design for high frequency piezoelectric ultrasonic transducers with their clamping connections

Energy Technology Data Exchange (ETDEWEB)

Wang, F. J., E-mail: wangfujun@tju.edu.cn; Liang, C. M.; Tian, Y. L.; Zhao, X. Y.; Zhang, D. W. [Tianjin Key Laboratory of Equipment Design and Manufacturing Technology, School of Mechanical Engineering, Tianjin University, Tianjin 300072 (China); Zhang, H. J. [Tianjin Key Laboratory of Modern Mechatronics Equipment Technology, School of Mechanical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China)

2015-12-15

This work presents the flexure-mechanism based decoupling design between high frequency piezoelectric ultrasonic transducers and their clamping connections to improve ultrasonic energy transmission efficiency. The ring, prismatic beam, and circular notched hinge based flanges were presented, and the crucial geometric dimensions of the transducers with the flexure decoupling flanges were determined. Finite element analysis (FEA) was carried out to investigate the dynamic characteristics of the transducers. Finally, experiments were conducted to examine and verify the effects of the proposed decoupling flanges. FEA and experimental results show that smaller frequency deviations and larger tip displacement amplitudes have been achieved by using the transducers with the flexure flanges compared with the transducer with a rigid ring-type flange, and thus the ultrasonic transmission efficiency can be improved through the flexure flanges.

East Asia in World Trade: The Decoupling Fallacy, Crisis and Policy Challenges

OpenAIRE

Prema-chandra Athukorala; Archanun Kohpaiboon

2010-01-01

This paper examines the export experience of China and other East Asian economies in the aftermaths of the global financial crisis against the backdrop of pre-crisis trade patterns. The analysis is motivated by the ‘decoupling' thesis, which was a popular theme in the Asian policy circles in the lead-up to the onset of the recent financial crisis, and aims to probe three key issues: Was the East Asian trade integration story that underpinned the decoupling thesis simply a statistical artifact...

General decoupling procedure for expectation values of four-operator products in electron–phonon quantum kinetics

International Nuclear Information System (INIS)

Teeny, Nicolas; Fähnle, Manfred

2013-01-01

In the density-matrix formalism of electron–phonon quantum kinetics, the hierarchy of infinitely many coupled equations of motion for the expectation values of products of electron and phonon creation and annihilation operators of arbitrary order is usually terminated on the level of the equations of motion for the expectation values of three-operator products by using decoupling procedures for the four-operator products occurring in these equations. In the literature, decoupling procedures are discussed for special types of electron and phonon states. In the present paper, generalized decoupling procedures are derived for arbitrary electron and phonon states. (paper)

Geometric constraints in semiclassical initial value representation calculations in Cartesian coordinates: accurate reduction in zero-point energy.

Science.gov (United States)

Issack, Bilkiss B; Roy, Pierre-Nicholas

2005-08-22

An approach for the inclusion of geometric constraints in semiclassical initial value representation calculations is introduced. An important aspect of the approach is that Cartesian coordinates are used throughout. We devised an algorithm for the constrained sampling of initial conditions through the use of multivariate Gaussian distribution based on a projected Hessian. We also propose an approach for the constrained evaluation of the so-called Herman-Kluk prefactor in its exact log-derivative form. Sample calculations are performed for free and constrained rare-gas trimers. The results show that the proposed approach provides an accurate evaluation of the reduction in zero-point energy. Exact basis set calculations are used to assess the accuracy of the semiclassical results. Since Cartesian coordinates are used, the approach is general and applicable to a variety of molecular and atomic systems.

Coherent and Semiclassical States of a Charged Particle in a Constant Electric Field

Science.gov (United States)

Adorno, T. C.; Pereira, A. S.

2018-05-01

The method of integrals of motion is used to construct families of generalized coherent states of a nonrelativistic spinless charged particle in a constant electric field. Families of states, differing in the values of their standard deviations at the initial time, are obtained. Depending on the initial values of the standard deviations, and also on the electric field, it turns out to be possible to identify some families with semiclassical states.

A semiclassical method in the theory of light scattering by semiconductor quantum dots

International Nuclear Information System (INIS)

Lang, I. G.; Korovin, L. I.; Pavlov, S. T.

2008-01-01

A semiclassical method is proposed for the theoretical description of elastic light scattering by arbitrary semiconductor quantum dots under conditions of size quantization. This method involves retarded potentials and allows one to dispense with boundary conditions for electric and magnetic fields. Exact results for the Umov-Poynting vector at large distances from quantum dots in the case of monochromatic and pulsed irradiation and formulas for differential scattering cross sections are obtained

Decoupling - past trends and prospects for the future

International Nuclear Information System (INIS)

Azar, Christian; Holmberg, John; Karlsson, Sten

2002-05-01

There are widespread demands in society for a de materialization or decoupling of economic growth from environmental impact. Calls are being made for eco-efficiency and/or an improvement of resource efficiency by a factor of 10. At the same time, some analysts claim there is an environmental Kuznet's curve that supposedly implies a fall in environmental pressure, as we get richer. An improvement in the environmental situation has already been observed in many cases, but there are also many areas where the situation is deteriorating. The purpose of this report is to summarize some key trends of energy and material use over time in both developing and developed countries. We have focused on Sweden, the EU, Japan and the USA as well as China, India and Brazil. The main findings in this paper can be summarized as follows: Absolute emissions of CO 2 have been increasing in most countries and periods studied. Some countries have experienced periods with constant or even falling emissions, but this is the exception rather than the rule, and it has been triggered by oil crises or economic recessions. In order to stabilize atmospheric CO 2 concentrations, CO 2 emissions have to be decoupled much more rapidly than has been the case in the past, and it is extremely unlikely that this will happen by itself. There was some decoupling of CO 2 emissions from GDP in the major economies of the world from 1970 to 1998 in the EU, Japan and the US as well as in some major developing countries such as China, although India actually increased its emissions over GDP by 1.4 per cent/yr over this period. The drop in CO 2 intensity has been prompted by some decoupling of energy from GDP and CO 2 from energy, the latter being a consequence of an increased use of natural gas and nuclear power. In the South, fossil CO 2 per energy tends to increase from rather low levels. With industrialization, the proportion of biomass drops and the proportion of fossil energy rises in the energy supply mix

Coupling and decoupling of the accelerating units for pulsed synchronous linear accelerator

Science.gov (United States)

Shen, Yi; Liu, Yi; Ye, Mao; Zhang, Huang; Wang, Wei; Xia, Liansheng; Wang, Zhiwen; Yang, Chao; Shi, Jinshui; Zhang, Linwen; Deng, Jianjun

2017-12-01

A pulsed synchronous linear accelerator (PSLA), based on the solid-state pulse forming line, photoconductive semiconductor switch, and high gradient insulator technologies, is a novel linear accelerator. During the prototype PSLA commissioning, the energy gain of proton beams was found to be much lower than expected. In this paper, the degradation of the energy gain is explained by the circuit and cavity coupling effect of the accelerating units. The coupling effects of accelerating units are studied, and the circuit topologies of these two kinds of coupling effects are presented. Two methods utilizing inductance and membrane isolations, respectively, are proposed to reduce the circuit coupling effects. The effectiveness of the membrane isolation method is also supported by simulations. The decoupling efficiency of the metal drift tube is also researched. We carried out the experiments on circuit decoupling of the multiple accelerating cavity. The result shows that both circuit decoupling methods could increase the normalized voltage.

Lamb shift in quantum electrodynamics (semiclassical theory)

International Nuclear Information System (INIS)

Blaive, B.; Boudet, R.

1989-01-01

This paper aims to bring some arguments to the proof of the Barut and Van Huele formula, which gives the Lamb shift in the semi-classical theory model: by shortening the calculation owing to the use of a decomposition of the self-potential of the electron; by eliminating the appeal to a divergent series; by bringing justifications and clarifications on some important points of the proof. The effective calculation of the coefficients of the formula is achieved for some of them, and the general analytical form of these coefficients is explicited. It is also proved that the B. and V.H. formula must give results at least as close to the experiment as those of the Bethe formula, which is obtained in Quantum Theory of Fields. Finally one shows that the B. and V.H. formula provides a justification de facto for the cut-off which is used for associating finite numbers to the divergent integrals of the Bethe formula [fr

Classical trajectory perspective of atomic ionization in strong laser fields. Semiclassical modeling

International Nuclear Information System (INIS)

Liu, Jie

2014-01-01

Dealing with timely and interesting issues in strong laser physics. Illustrates complex strong field atomic ionization with the simple semiclassical model of classical trajectory perspective for the first time. Provides a theoretical model that can be used to account for recent experiments. The ionization of atoms and molecules in strong laser fields is an active field in modern physics and has versatile applications in such as attosecond physics, X-ray generation, inertial confined fusion (ICF), medical science and so on. Classical Trajectory Perspective of Atomic Ionization in Strong Laser Fields covers the basic concepts in this field and discusses many interesting topics using the semiclassical model of classical trajectory ensemble simulation, which is one of the most successful ionization models and has the advantages of a clear picture, feasible computing and accounting for many exquisite experiments quantitatively. The book also presents many applications of the model in such topics as the single ionization, double ionization, neutral atom acceleration and other timely issues in strong field physics, and delivers useful messages to readers with presenting the classical trajectory perspective on the strong field atomic ionization. The book is intended for graduate students and researchers in the field of laser physics, atom molecule physics and theoretical physics. Dr. Jie Liu is a professor of Institute of Applied Physics and Computational Mathematics, China and Peking University.

Decoupling of charm beyond leading order

OpenAIRE

Knechtli, Francesco; Korzec, Tomasz; Leder, Björn; Moir, Graham

2017-01-01

We study the effective theory of decoupling of a charm quark at low energies. We do this by simulating a model, QCD with two mass-degenerate charm quarks. At leading order the effective theory is a pure gauge theory. By computing ratios of hadronic scales we have direct access to the power corrections in the effective theory. We show that these corrections follow the expected leading behavior, which is quadratic in the inverse charm quark mass.

Semi-classical description of matter wave interferometers and hybrid quantum systems

Energy Technology Data Exchange (ETDEWEB)

Schneider, Mathias

2015-02-16

This work considers the semi-classical description of two applications involving cold atoms. This is, on one hand, the behavior of a BOSE-EINSTEIN condensate in hybrid systems, i.e. in contact with a microscopic object (carbon nanotubes, fullerenes, etc.). On the other, the evolution of phase space distributions in matter wave interferometers utilizing ray tracing methods was discussed. For describing condensates in hybrid systems, one can map the GROSS-PITAEVSKII equation, a differential equation in the complex-valued macroscopic wave function, onto a system of two differential equations in density and phase. Neglecting quantum dispersion, one obtains a semiclassical description which is easily modified to incorporate interactions between condensate and microscopical object. In our model, these interactions comprise attractive forces (CASIMIR-POLDER forces) and loss of condensed atoms due to inelastic collisions at the surface of the object. Our model exhibited the excitation of sound waves that are triggered by the object's rapid immersion, and spread across the condensate thereafter. Moreover, local particle loss leads to a shrinking of the bulk condensate. We showed that the total number of condensed particles is decreasing potentially in the beginning (large condensate, strong mean field interaction), while it decays exponentially in the long-time limit (small condensate, mean field inetraction negligible). For representing the physics of matter wave interferometers in phase space, we utilized the WIGNER function. In semi-classical approximation, which again consists in ignoring the quantum dispersion, this representation is subject to the same equation of motion as classical phase space distributions, i.e. the LIOUVILLE equation. This implies that time evolution of theWIGNER function follows a phase space flow that consists of classical trajectories (classical transport). This means, for calculating a time-evolved distribution, one has know the initial

Empirical research on decoupling relationship between energy-related carbon emission and economic growth in Guangdong province based on extended Kaya identity.

Science.gov (United States)

Wang, Wenxiu; Kuang, Yaoqiu; Huang, Ningsheng; Zhao, Daiqing

2014-01-01

The decoupling elasticity decomposition quantitative model of energy-related carbon emission in Guangdong is established based on the extended Kaya identity and Tapio decoupling model for the first time, to explore the decoupling relationship and its internal mechanism between energy-related carbon emission and economic growth in Guangdong. Main results are as follows. (1) Total production energy-related carbon emissions in Guangdong increase from 4128 × 10⁴ tC in 1995 to 14396 × 10⁴ tC in 2011. Decoupling elasticity values of energy-related carbon emission and economic growth increase from 0.53 in 1996 to 0.85 in 2011, and its decoupling state turns from weak decoupling in 1996-2004 to expansive coupling in 2005-2011. (2) Land economic output and energy intensity are the first inhibiting factor and the first promoting factor to energy-related carbon emission decoupling from economic growth, respectively. The development speeds of land urbanization and population urbanization, especially land urbanization, play decisive roles in the change of total decoupling elasticity values. (3) Guangdong can realize decoupling of energy-related carbon emission from economic growth effectively by adjusting the energy mix and industrial structure, coordinating the development speed of land urbanization and population urbanization effectively, and strengthening the construction of carbon sink.

A Decoupling Control Method for Shunt Hybrid Active Power Filter Based on Generalized Inverse System

Directory of Open Access Journals (Sweden)

Xin Li

2017-01-01

Full Text Available In this paper, a novel decoupling control method based on generalized inverse system is presented to solve the problem of SHAPF (Shunt Hybrid Active Power Filter possessing the characteristics of 2-input-2-output nonlinearity and strong coupling. Based on the analysis of operation principle, the mathematical model of SHAPF is firstly built, which is verified to be invertible using interactor algorithm; then the generalized inverse system of SHAPF is obtained to connect in series with the original system so that the composite system is decoupled under the generalized inverse system theory. The PI additional controller is finally designed to control the decoupled 1-order pseudolinear system to make it possible to adjust the performance of the subsystem. The simulation results demonstrated by MATLAB show that the presented generalized inverse system strategy can realise the dynamic decoupling of SHAPF. And the control system has fine dynamic and static performance.

Decoupling and Decomposition Analysis of Carbon Emissions from Industry: A Case Study from China

Directory of Open Access Journals (Sweden)

Qiang Wang

2016-10-01

Full Text Available China has overtaken the United States as the world’s largest producer of carbon dioxide, with industrial carbon emissions (ICE accounting for approximately 65% of the country’s total emissions. Understanding the ICE decoupling patterns and factors influencing the decoupling status is a prerequisite for balancing economic growth and carbon emissions. This paper provides an overview of ICE based on decoupling elasticity and the Tapio decoupling model. Furthermore, the study identifies the factors contributing to ICE changes in China, using the Kaya identity and Log Mean Divisia Index (LMDI techniques. Based on the effects and contributions of ICE, we close with a number of recommendations. The results revealed a significant upward trend of ICE during the study period 1994 to 2013, with a total amount of 11,147 million tons. Analyzing the decoupling relationship indicates that “weak decoupling” and “expansive decoupling” were the main states during the study period. The decomposition analysis showed that per capita wealth associated with industrial outputs and energy intensity are the main driving force of ICE, while energy intensity of industrial output and energy structure are major determinants for ICE reduction. The largest contributing cumulative effect to ICE is per capita wealth, at 1.23 in 2013. This factor is followed by energy intensity, with a contributing cumulative effect of −0.32. The cumulative effects of energy structure and population are relatively small, at 0.01 and 0.08, respectively.

Semiclassical Hybrid Approach to Condensed Phase Molecular Dynamics: Application to the I2Kr17 Cluster

Czech Academy of Sciences Publication Activity Database

Buchholz, M.; Goletz, Ch. M.; Grossman, F.; Schmidt, B.; Heyda, J.; Jungwirth, Pavel

2012-01-01

Roč. 116, č. 46 (2012), s. 11199-11210 ISSN 1089-5639 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : semiclassical molecular dynamics * cluster * wavepacket * coherence * spectra Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.771, year: 2012

Decoupled Speed and Torque Control of IPMSM Drives Using a Novel Load Torque Estimator

Directory of Open Access Journals (Sweden)

ZAKY, M.

2017-08-01

Full Text Available This paper proposes decoupled speed and torque control of interior permanent magnet synchronous motor (IPMSM drives using a novel load torque estimator (LTE. The proposed LTE is applied for computing a load torque and yielding a feed-forward value in the speed controller to separate the torque control from the speed control. Indirect flux weakening using direct current component is obtained for high speed operation of the IPMSM drive, and its value for maximum torque per ampere (MTPA control in constant torque region is also used. LTE uses values of direct and quadrature currents to improve the behavior of the speed controller under the reference tracking and torque disturbances. The complete IPMSM drive by Matlab/Simulink is built. The effectiveness of the proposed control scheme using an experimental setup of the complete drive system implemented on a DSP-DS1102 control board is confirmed. Extensive results over a wide speed range are verified. The efficacy of the proposed method is confirmed in comparison to a conventional PI controller under both the reference speed tracking and load torque disturbance.

Resource Allocation and Cluster Formation for Imperfect NOMA in DL/UL Decoupled HetNets

KAUST Repository

Celik, Abdulkadir; Radaydeh, Redha; Al-Qahtani, Fawaz; Abd El-Malek, Ahmed H.; Alouini, Mohamed-Slim

2017-01-01

Being capable of serving multiple users with the same radio resource, non-orthogonal multiple access (NOMA) can provide desirable performance enhancements in a fair and spectral efficient manner. In this paper, we investigate the resource allocation (RA) and cluster formation (CF) aspects of NOMA for downlink (DL) uplink (UL) decoupled (DUDe) heterogeneous networks (HetNets). A non-ideal NOMA scheme is considered with power disparity and sensitivity constraints (PDSCs), delay tolerance, and residual interference after cancellation. Taking the PDSCs into account, we analytically show that using the DL decoding order limits UL-NOMA performance by that of OMA, while employing an inverse order result in a performance gain that is mainly determined by the channel gain disparity of users. Thereafter, a generic CF method is proposed for any type of user graph, which iteratively forms clusters using Blossom algorithm. Finally, highly non-convex RA problem is converted into a convex form by employing geometric programming (GP) where power and bandwidth are optimized to maximize network sumrate and max-min fairness objectives.

Resource Allocation and Cluster Formation for Imperfect NOMA in DL/UL Decoupled HetNets

KAUST Repository

Celik, Abdulkadir

2017-04-15

Being capable of serving multiple users with the same radio resource, non-orthogonal multiple access (NOMA) can provide desirable performance enhancements in a fair and spectral efficient manner. In this paper, we investigate the resource allocation (RA) and cluster formation (CF) aspects of NOMA for downlink (DL) uplink (UL) decoupled (DUDe) heterogeneous networks (HetNets). A non-ideal NOMA scheme is considered with power disparity and sensitivity constraints (PDSCs), delay tolerance, and residual interference after cancellation. Taking the PDSCs into account, we analytically show that using the DL decoding order limits UL-NOMA performance by that of OMA, while employing an inverse order result in a performance gain that is mainly determined by the channel gain disparity of users. Thereafter, a generic CF method is proposed for any type of user graph, which iteratively forms clusters using Blossom algorithm. Finally, highly non-convex RA problem is converted into a convex form by employing geometric programming (GP) where power and bandwidth are optimized to maximize network sumrate and max-min fairness objectives.

Decoupled Multicamera Sensing for Flexible View Generation

Directory of Open Access Journals (Sweden)

Vivek K. Singh

2016-01-01

Full Text Available Any sensing paradigm has three important components, namely, the actor, the sensor, and the environment. Traditionally, the sensors have been attached to either the actor or the environment. This restricts the kind of sensing that can be undertaken. We study a newer decoupled sensing paradigm, which separates the sensors from both the actor and the environment and tremendously increases the flexibility with which the scenes can be viewed. For example, instead of showing just one view, “how the environment sees the actor” or “how the actor sees the environment,” a viewer can choose to see either one or both of these views and even choose to see the scene from any desired position in any desired direction. We describe a methodology using mobile autonomous sensors to undertake such decoupled sensing and study the feasible number as well as the placement of such sensors. Also, we describe how the sensors can coordinate their movements around a moving actor so as to continue capturing the required views with minimum overall cost. The practical results obtained demonstrate the viability of the proposed approach.

Reflection at a complex potential barrier in the semiclassical theory of scattering

International Nuclear Information System (INIS)

Avishai, Y.; Knoll, J.

1976-01-01

The reflection of spherical waves at a complex potential barrier is discussed in the semiclassical approximation. We study the complex WKB method and the Uniform Approximation in the special case of weakly absorptive barriers, typical of surface transparent optical potentials used in heavy-ion reactions. It is found that the complex WKB results lead to a very accurate cross-section despite their inaccuracy in the most important phase shifts. Thereby, the amazing stamina of the WKB has been confirmed once more. (orig.) [de

Power decoupling method for single phase differential buck converter

DEFF Research Database (Denmark)

Yao, Wenli; Tang, Yi; Zhang, Xiaobin

2015-01-01

inverter to improve the dc link power quality, and an improved active power decoupling method is proposed to achieve ripple power reduction for both AC-DC and DC-AC conversions. The ripple energy storage is realized by the filter capacitors, which are connected between the output terminal and the negative...... generation technique is proposed to provide accurate ripple power compensation, and closed-loop controllers are also designed based on small signal models. The effectiveness of this power decoupling method is verified by detailed simulation studies as well as laboratory prototype experimental results....... dc bus. By properly controlling the differential mode voltage of the capacitors, it is possible to transfer desired energy between the DC port and AC port. The common mode voltage is controlled in such a way that the ripple power on the dc side will be reduced. Furthermore, an autonomous reference...

Maximizing biodiversity co-benefits under REDD+: a decoupled approach

International Nuclear Information System (INIS)

Potts, Matthew D; Kelley, Lisa C; Doll, Hannah M

2013-01-01

Current debates on biodiversity co-benefits under REDD+ are marked by considerable ambiguity and contention. Nevertheless, REDD+ continues to represent one of the most important opportunities for global biodiversity conservation, and the question of how best to achieve biodiversity co-benefits remains an important one. Thus far, most biodiversity conservation in the context of REDD+ is predicated on the notion that services are co-located on a landscape. In contrast, this letter argues that decoupling biodiversity and carbon services on a landscape through national-level planning is a better approach to biodiversity conservation under REDD+. We discuss the fundamental ecological differences between the two services and use principles of resource economics to demonstrate that a decoupled approach will be more efficient, more flexible, and better able to mobilize sufficient finance for biodiversity conservation than a coupled approach. (letter)

Maximizing biodiversity co-benefits under REDD+: a decoupled approach

Science.gov (United States)

Potts, Matthew D.; Kelley, Lisa C.; Doll, Hannah M.

2013-06-01

Current debates on biodiversity co-benefits under REDD+ are marked by considerable ambiguity and contention. Nevertheless, REDD+ continues to represent one of the most important opportunities for global biodiversity conservation, and the question of how best to achieve biodiversity co-benefits remains an important one. Thus far, most biodiversity conservation in the context of REDD+ is predicated on the notion that services are co-located on a landscape. In contrast, this letter argues that decoupling biodiversity and carbon services on a landscape through national-level planning is a better approach to biodiversity conservation under REDD+. We discuss the fundamental ecological differences between the two services and use principles of resource economics to demonstrate that a decoupled approach will be more efficient, more flexible, and better able to mobilize sufficient finance for biodiversity conservation than a coupled approach.

Gauge-invariant area distributions for semiclassical magnetotransport through ballistic nanostructures

International Nuclear Information System (INIS)

Wirtz, L.; Yang, Xiazhou; Burgdoerfer, J.E.

1996-01-01

Within the semiclassical theory of magnetotransport, conductance fluctuations in ballistic cavities are determined by distribution functions of directed areas enclose by classical paths. The authors calculate gauge invariant areas which can be visualized as closure of areas by adding a virtual path to the real path connecting the leads. Gauge invariance of the resulting area distribution is found to be important for geometry-sensitive non-universal properties of transport. The authors show that in the presence of direct paths both the area distribution and the two-point pair distribution function for areas of trajectories contribute. Comparison with recent data by Marcus et al. for a stadium-shaped nanostructure is made

Cross-modal decoupling in temporal attention.

Science.gov (United States)

Mühlberg, Stefanie; Oriolo, Giovanni; Soto-Faraco, Salvador

2014-06-01

Prior studies have repeatedly reported behavioural benefits to events occurring at attended, compared to unattended, points in time. It has been suggested that, as for spatial orienting, temporal orienting of attention spreads across sensory modalities in a synergistic fashion. However, the consequences of cross-modal temporal orienting of attention remain poorly understood. One challenge is that the passage of time leads to an increase in event predictability throughout a trial, thus making it difficult to interpret possible effects (or lack thereof). Here we used a design that avoids complete temporal predictability to investigate whether attending to a sensory modality (vision or touch) at a point in time confers beneficial access to events in the other, non-attended, sensory modality (touch or vision, respectively). In contrast to previous studies and to what happens with spatial attention, we found that events in one (unattended) modality do not automatically benefit from happening at the time point when another modality is expected. Instead, it seems that attention can be deployed in time with relative independence for different sensory modalities. Based on these findings, we argue that temporal orienting of attention can be cross-modally decoupled in order to flexibly react according to the environmental demands, and that the efficiency of this selective decoupling unfolds in time. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Dynamic plasma screening effects on semiclassical inelastic electron endash ion collisions in dense plasmas

International Nuclear Information System (INIS)

Jung, Y.

1997-01-01

In dense plasmas, dynamic plasma screening effects are investigated on 1s→2p dipole transition probabilities for electron-impact excitation of hydrogenic ions. The electron endash ion interaction potential is considered by introduction of the plasma dielectric function. A semiclassical straight-line trajectory method is applied to the path of the projectile electron in order to visualize the semiclassical transition probability as a function of the impact parameter, projectile energy, and plasma parameters. The transition probability including the dynamic plasma screening effect is always greater than that including the static plasma screening effect. When the projectile velocity is smaller than the electron thermal velocity, the dynamic polarization screening effect becomes the static plasma screening effect. When the projectile velocity is greater than the electron thermal velocity, then the interaction potential is almost unshielded. The difference between the dynamic and static plasma screening effects is more significant for low-energy projectiles. It is also found that the static plasma screening formula obtained by the Debye endash Hueckel model overestimates the plasma screening effects on the atomic excitation processes in dense plasmas. copyright 1997 American Institute of Physics

Decoupling capabilities of split-loop resonator structure for 7 Tesla MRI surface array coils

Science.gov (United States)

Hurshkainen, A.; Kurdjumov, S.; Simovski, C.; Glybovski, S.; Melchakova, I.; van den Berg, C. A. T.; Raaijmakers, A.; Belov, P.

2017-09-01

In this work we studied electromagnetic properties of one-dimentional periodic structures composed of split-loop res-onators (SLRs) and investigated their capabilities in decoupling of two dipole antennas for full-body magnetic resonance imaging (MRI). Two different finite structures comprising a single-SLR and a double-SLR constitutive elements were studied. Numerical simulations of the structures were performed to evaluate their decoupling capabilities. As it was demonstrated two dipole antennas equipped with either a single or a double-SLR structure exhibit high isolation even for an electrically short distance between the dipoles. Double-SLR structure while dramatically improving isolation of the dipoles keeps the field created by each of the decoupled dipoles comparable with one of a single dipole inside the target area.

Delayed Antiwindup Control Using a Decoupling Structure

Directory of Open Access Journals (Sweden)

Huawei Zhu

2013-01-01

Full Text Available This paper investigates the antiwindup (AW control problem for plants with input saturation. The AW compensator is not activated as soon as input saturation occurs as usual. A delayed decoupling structure is first proposed. Then, appropriate linear matrix inequalities (LMIs are developed to determine a plant-order AW compensator. Effectiveness of the presented AW technique is illustrated by a fighter aircraft model.

Semi-classical approximation to path integrals - phases and catastrophes

International Nuclear Information System (INIS)

Levit, S.

1977-01-01

Problems of phases and catastrophes were encountered when trying to apply the classical S-matrix theory to the scattering phenomena in nuclear physics. The path integral formulation provided a suitable basis for the treatment of these and related problems. Within conventional mathematical language it was possible to give practical prescriptions and discuss their limitations. Since the semi-classical (stationary phase) approximation is commonly used in any application of the path integral method, the results are not restricted to the scattering problems and may be of general interest. The derivation of the uniform approximations in the energy representation should use the exact path integral expression as the starting point, rather than performing Fourier transforms on the expressions derived in the present lecture. (B.G.)

Gauge symmetry from decoupling

Directory of Open Access Journals (Sweden)

C. Wetterich

2017-02-01

Full Text Available Gauge symmetries emerge from a redundant description of the effective action for light degrees of freedom after the decoupling of heavy modes. This redundant description avoids the use of explicit constraints in configuration space. For non-linear constraints the gauge symmetries are non-linear. In a quantum field theory setting the gauge symmetries are local and can describe Yang–Mills theories or quantum gravity. We formulate gauge invariant fields that correspond to the non-linear light degrees of freedom. In the context of functional renormalization gauge symmetries can emerge if the flow generates or preserves large mass-like terms for the heavy degrees of freedom. They correspond to a particular form of gauge fixing terms in quantum field theories.

Quantum and semiclassical spin networks: from atomic and molecular physics to quantum computing and gravity

Science.gov (United States)

Aquilanti, Vincenzo; Bitencourt, Ana Carla P.; Ferreira, Cristiane da S.; Marzuoli, Annalisa; Ragni, Mirco

2008-11-01

The mathematical apparatus of quantum-mechanical angular momentum (re)coupling, developed originally to describe spectroscopic phenomena in atomic, molecular, optical and nuclear physics, is embedded in modern algebraic settings which emphasize the underlying combinatorial aspects. SU(2) recoupling theory, involving Wigner's 3nj symbols, as well as the related problems of their calculations, general properties, asymptotic limits for large entries, nowadays plays a prominent role also in quantum gravity and quantum computing applications. We refer to the ingredients of this theory—and of its extension to other Lie and quantum groups—by using the collective term of 'spin networks'. Recent progress is recorded about the already established connections with the mathematical theory of discrete orthogonal polynomials (the so-called Askey scheme), providing powerful tools based on asymptotic expansions, which correspond on the physical side to various levels of semi-classical limits. These results are useful not only in theoretical molecular physics but also in motivating algorithms for the computationally demanding problems of molecular dynamics and chemical reaction theory, where large angular momenta are typically involved. As for quantum chemistry, applications of these techniques include selection and classification of complete orthogonal basis sets in atomic and molecular problems, either in configuration space (Sturmian orbitals) or in momentum space. In this paper, we list and discuss some aspects of these developments—such as for instance the hyperquantization algorithm—as well as a few applications to quantum gravity and topology, thus providing evidence of a unifying background structure.

Laguerre-Freud Equations for the Recurrence Coefficients of Some Discrete Semi-Classical Orthogonal Polynomials of Class Two

Science.gov (United States)

Hounga, C.; Hounkonnou, M. N.; Ronveaux, A.

2006-10-01

In this paper, we give Laguerre-Freud equations for the recurrence coefficients of discrete semi-classical orthogonal polynomials of class two, when the polynomials in the Pearson equation are of the same degree. The case of generalized Charlier polynomials is also presented.

Randomized dynamical decoupling strategies and improved one-way key rates for quantum cryptography

Energy Technology Data Exchange (ETDEWEB)

Kern, Oliver

2009-05-25

The present thesis deals with various methods of quantum error correction. It is divided into two parts. In the first part, dynamical decoupling methods are considered which have the task of suppressing the influence of residual imperfections in a quantum memory. Such imperfections might be given by couplings between the finite dimensional quantum systems (qudits) constituting the quantum memory, for instance. The suppression is achieved by altering the dynamics of an imperfect quantum memory with the help of a sequence of local unitary operations applied to the qudits. Whereas up to now the operations of such decoupling sequences have been constructed in a deterministic fashion, strategies are developed in this thesis which construct the operations by random selection from a suitable set. Formulas are derived which estimate the average performance of such strategies. As it turns out, randomized decoupling strategies offer advantages and disadvantages over deterministic ones. It is possible to benefit from the advantages of both kind of strategies by designing combined strategies. Furthermore, it is investigated if and how the discussed decoupling strategies can be employed to protect a quantum computation running on the quantum memory. It is shown that a purely randomized decoupling strategy may be used by applying the decoupling operations and adjusted gates of the quantum algorithm in an alternating fashion. Again this method can be enhanced by the means of deterministic methods in order to obtain a combined decoupling method for quantum computations analogously to the combining strategies for quantum memories. The second part of the thesis deals with quantum error-correcting codes and protocols for quantum key distribution. The focus is on the BB84 and the 6-state protocol making use of only one-way communication during the error correction and privacy amplification steps. It is shown that by adding additional errors to the preliminary key (a process called

Randomized dynamical decoupling strategies and improved one-way key rates for quantum cryptography

International Nuclear Information System (INIS)

Kern, Oliver

2009-01-01

The present thesis deals with various methods of quantum error correction. It is divided into two parts. In the first part, dynamical decoupling methods are considered which have the task of suppressing the influence of residual imperfections in a quantum memory. Such imperfections might be given by couplings between the finite dimensional quantum systems (qudits) constituting the quantum memory, for instance. The suppression is achieved by altering the dynamics of an imperfect quantum memory with the help of a sequence of local unitary operations applied to the qudits. Whereas up to now the operations of such decoupling sequences have been constructed in a deterministic fashion, strategies are developed in this thesis which construct the operations by random selection from a suitable set. Formulas are derived which estimate the average performance of such strategies. As it turns out, randomized decoupling strategies offer advantages and disadvantages over deterministic ones. It is possible to benefit from the advantages of both kind of strategies by designing combined strategies. Furthermore, it is investigated if and how the discussed decoupling strategies can be employed to protect a quantum computation running on the quantum memory. It is shown that a purely randomized decoupling strategy may be used by applying the decoupling operations and adjusted gates of the quantum algorithm in an alternating fashion. Again this method can be enhanced by the means of deterministic methods in order to obtain a combined decoupling method for quantum computations analogously to the combining strategies for quantum memories. The second part of the thesis deals with quantum error-correcting codes and protocols for quantum key distribution. The focus is on the BB84 and the 6-state protocol making use of only one-way communication during the error correction and privacy amplification steps. It is shown that by adding additional errors to the preliminary key (a process called

The semiclassical approximation for L- and M-shell coulomb ionization by heavy charged particles

International Nuclear Information System (INIS)

Kocbach, L.

1975-08-01

The semiclassical approximation with straight line trajectories is applied to the Coulomb ionization of K-, L- and M-shells by heavy charged particles. The calculational aspects are discussed in detail. Scaling relations for the experimentally relevant quantities are derived. The theoretical predictions are compared with experimental data. The relation of the present work to earlier SCA results and the PWBA results is discussed in detail. (auth)

Highly efficient F-19 heteronuclear decoupling in solid-state NMR spectroscopy using supercycled refocused-CW irradiation

DEFF Research Database (Denmark)

Equbal, Asif; Basse, Kristoffer; Nielsen, Niels Christian

2016-01-01

We present heteronuclear F-19 refocused CW (rCW) decoupling pulse sequences for solid-state magic-angle- spinning NMR applications. The decoupling sequences have been designed specifically to ensure suppression of the pertinent C-13-F-19 dipolar coupling interactions while simultaneously suppress...

A model partitioning method based on dynamic decoupling for the efficient simulation of multibody systems

Energy Technology Data Exchange (ETDEWEB)

Papadopoulos, Alessandro Vittorio, E-mail: alessandro.papadopoulos@control.lth.se [Lund University, Department of Automatic Control (Sweden); Leva, Alberto, E-mail: alberto.leva@polimi.it [Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria (Italy)

2015-06-15

The presence of different time scales in a dynamic model significantly hampers the efficiency of its simulation. In multibody systems the fact is particularly relevant, as the mentioned time scales may be very different, due, for example, to the coexistence of mechanical components controled by electronic drive units, and may also appear in conjunction with significant nonlinearities. This paper proposes a systematic technique, based on the principles of dynamic decoupling, to partition a model based on the time scales that are relevant for the particular simulation studies to be performed and as transparently as possible for the user. In accordance with said purpose, peculiar to the technique is its neat separation into two parts: a structural analysis of the model, which is general with respect to any possible simulation scenario, and a subsequent decoupled integration, which can conversely be (easily) tailored to the study at hand. Also, since the technique does not aim at reducing but rather at partitioning the model, the state space and the physical interpretation of the dynamic variables are inherently preserved. Moreover, the proposed analysis allows us to define some novel indices relative to the separability of the system, thereby extending the idea of “stiffness” in a way that is particularly keen to its use for the improvement of simulation efficiency, be the envisaged integration scheme monolithic, parallel, or even based on cosimulation. Finally, thanks to the way the analysis phase is conceived, the technique is naturally applicable to both linear and nonlinear models. The paper contains a methodological presentation of the proposed technique, which is related to alternatives available in the literature so as to evidence the peculiarities just sketched, and some application examples illustrating the achieved advantages and motivating the major design choice from an operational viewpoint.

Decoupling interrelated parameters for designing high performance thermoelectric materials.

Science.gov (United States)

Xiao, Chong; Li, Zhou; Li, Kun; Huang, Pengcheng; Xie, Yi

2014-04-15

The world's supply of fossil fuels is quickly being exhausted, and the impact of their overuse is contributing to both climate change and global political unrest. In order to help solve these escalating problems, scientists must find a way to either replace combustion engines or reduce their use. Thermoelectric materials have attracted widespread research interest because of their potential applications as clean and renewable energy sources. They are reliable, lightweight, robust, and environmentally friendly and can reversibly convert between heat and electricity. However, after decades of development, the energy conversion efficiency of thermoelectric devices has been hovering around 10%. This is far below the theoretical predictions, mainly due to the interdependence and coupling between electrical and thermal parameters, which are strongly interrelated through the electronic structure of the materials. Therefore, any strategy that balances or decouples these parameters, in addition to optimizing the materials' intrinsic electronic structure, should be critical to the development of thermoelectric technology. In this Account, we discuss our recently developed strategies to decouple thermoelectric parameters for the synergistic optimization of electrical and thermal transport. We first highlight the phase transition, which is accompanied by an abrupt change of electrical transport, such as with a metal-insulator and semiconductor-superionic conductor transition. This should be a universal and effective strategy to optimize the thermoelectric performance, which takes advantage of modulated electronic structure and critical scattering across phase transitions to decouple the power factor and thermal conductivity. We propose that solid-solution homojunction nanoplates with disordered lattices are promising thermoelectric materials to meet the "phonon glass electron crystal" approach. The formation of a solid solution, coupled with homojunctions, allows for

Decoupled numerical simulation of a solid fuel fired retort boiler

International Nuclear Information System (INIS)

Ryfa, Arkadiusz; Buczynski, Rafal; Chabinski, Michal; Szlek, Andrzej; Bialecki, Ryszard A.

2014-01-01

The paper deals with numerical simulation of the retort boiler fired with solid fuel. Such constructions are very popular for heating systems and their development is mostly based on the designer experience. The simulations have been done in ANSYS/Fluent package and involved two numerical models. The former deals with a fixed-bed combustion of the solid fuel and free-board gas combustion. Solid fuel combustion is based on the coal kinetic parameters. This model encompasses chemical reactions, radiative heat transfer and turbulence. Coal properties have been defined with user defined functions. The latter model describes flow of water inside a water jacked that surrounds the combustion chamber and flue gas ducts. The novelty of the proposed approach is separating of the combustion simulation from the water flow. Such approach allows for reducing the number of degrees of freedom and thus lowering the necessary numerical effort. Decoupling combustion from water flow requires defining interface boundary condition. As this boundary condition is unknown it is adjusted iteratively. The results of the numerical simulation have been successfully validated against measurement data. - Highlights: • New decoupled modelling of small scale boiler is proposed. • Fixed-bed combustion model based on kinetic parameters is introduced. • Decoupling reduced the complexity of the model and computational time. • Simple and computationally inexpensive coupling algorithm is proposed. • Model is successfully validated against measurements

D-FNN Based Modeling and BP Neural Network Decoupling Control of PVC Stripping Process

Directory of Open Access Journals (Sweden)

Shu-zhi Gao

2014-01-01

Full Text Available PVC stripping process is a kind of complicated industrial process with characteristics of highly nonlinear and time varying. Aiming at the problem of establishing the accurate mathematics model due to the multivariable coupling and big time delay, the dynamic fuzzy neural network (D-FNN is adopted to establish the PVC stripping process model based on the actual process operation datum. Then, the PVC stripping process is decoupled by the distributed neural network decoupling module to obtain two single-input-single-output (SISO subsystems (slurry flow to top tower temperature and steam flow to bottom tower temperature. Finally, the PID controller based on BP neural networks is used to control the decoupled PVC stripper system. Simulation results show the effectiveness of the proposed integrated intelligent control method.

Modeling of tamped and decoupled explosions in salt (simulation is easy. Prediction is difficult exclamation point)

International Nuclear Information System (INIS)

Goldstein, P.; Glenn, L.A.

1993-01-01

We compare predictions of the strain hardening model of Glenn (1990), with and without damage, to free field and seismic observations of SALMON, STERLING, and 64 kt (tamped) and 8 kt (decoupled) explosions in an Azgir salt dome in the former Soviet Union (FSU). We find good agreement between the model (without damage) and observations of both SALMON and STERLING. In contrast, the average spectral ratio of the tamped to decoupled Azgir explosions is systematically smaller than predicted by the strain hardening model without damage. Much better agreement is obtained when damage is included in the model of the decoupled Azgir explosion

Modeling of tamped and decoupled explosions in salt (Simulation is easy. Prediction is difficult exclamation point)

International Nuclear Information System (INIS)

Goldstein, P.; Glenn, L.A.

1993-05-01

We compare predictions of the strain hardening model of Glenn (1990), with and without damage, to free field and seismic observations of SALMON, STERLING, and 64 kt (tamped) and 8 kt (decoupled) explosions in an Azgir salt dome in the former Soviet Union (FSU). We find good agreement between the model (without damage) and observations of both SALMON and STERLING. In contrast, the average spectral ratio of the tamped to decoupled Azgir explosions is systematically smaller than predicted by the strain hardening model without damage. Much better agreement is obtained when damage is included in the model of the decoupled Azgir explosion

Perancangan dan Implementasi Kontroler PID dengan Nonlinear Decoupling pada Sistem Kendali UAV Quadcopter

Directory of Open Access Journals (Sweden)

Muhammad Jadid Anggarjito

2013-09-01

Full Text Available Quadcopter merupakan salah salah satu jenis rotorcraft yang memiliki 4 buah rotor yang harus dikendalikan masing-masing rotornya untuk dapat menggerakkan quadcopter. Gerak lateral merupakan gerak quadcopter secara horizontal pada ketinggian atau gerak translasi, gerakan ini sangat vital untuk memenuhi kebutuhan quadcopter dalam mencapai way-to-way point yang telah ditentukan. Pada tugas akhir ini untuk mengatur gerakan lateral dari quadcopter digunakan sistem kendali PID dengan Decoupling Nonlinear. Ada 2 buah kontroler individual yang digunakan yaitu kontroler PID dengan Nonlinear Decoupling untuk mengatur pitch dan roll gerak rotasi, serta kontroler PD untuk mengatur translasi sumbu X dan sumbu Y. Perancangan sistem kontrol PID Decoupling Nonlinear pada simulasi yang digunakan untuk mempertahankan gerak lateral quadcopter dalam mencapai way-to-way point yang ditentukan. Nilai parameter yang didapatkan dari hasil tuning terstruktur pada simulasi adalah pada kontroler PID dengan Nonlinear Decoupling pitch dan roll Kp=5 Ki=0,01 Kd=10 sedangkan pada kontroler PD sumbu X dan sumbu Y Kp=0,05 Kd=0,2. Respon hasil implementasi pada quadcopter belum sesuai pada hasil simulasi. Pada hasil simulasi masih terdapat koreksi pada translasi sumbu X dan sumbu Y masih terdapat kesalahan sebesar ± 0,02 cm, sedangkan pada implementasi gerak lateral menggunakan remote control sistem dapat bergerak stabil menuju way-to-way point yang ditentukan.

Decoupling from international food safety standards

DEFF Research Database (Denmark)

Mercado, Geovana; Hjortsø, Carsten Nico; Honig, Benson

2018-01-01

rural producers who, grounded in culturally-embedded food safety conceptions, face difficulties in complying. We address this gap here through a multiple case study involving four public school feeding programs that source meals from local rural providers in the Bolivian Altiplan. Institutional logics...... in the market. These include: (1) partial adoption of formal rules; (2) selective adoption of convenient rules; and (3) ceremonial adoption to avoid compliance. Decoupling strategies allow local actors to largely disregard the formal food safety regulations while accommodating traditional cultural practices...

Active power decoupling with reduced converter stress for single ...

Indian Academy of Sciences (India)

SUJATA BHOWMICK

Department of Electronic Systems Engineering, Indian Institute of Science, ... Single phase; double-frequency ripple; active power decoupling; reduced stress; ... sation of renewable energy sources (e.g., PV), potential ... In standard grid connected DC/AC H-bridge configuration, ..... solar inverter with reduced-size dc link.

Neutronic performance of decoupled poisoned and unpoisoned composite moderators for high resolution experiments

International Nuclear Information System (INIS)

Kai, Tetsuya; Harada, Masahide; Watanabe, Noboru; Teshigawara, Makoto; Sakata, Hideaki; Ikeda, Yujiro

2001-01-01

We studied decoupled poisoned and un-poisoned composite moderators consisting of 20 mm thick hydrogen and 30 mm thick light water. The neutron pulses from un-poisoned one were much broader with longer decay times than a simple decoupled hydrogen moderator in 50 mm thickness. It was also found that the poisoned composite moderator provides higher pulse peak intensities relative to the hydrogen moderator (poisoned at 20 mm) below several tens meV with no penalty of pulse width. (author)

Semiclassical approach to finite-temperature quantum annealing with trapped ions

Science.gov (United States)

Raventós, David; Graß, Tobias; Juliá-Díaz, Bruno; Lewenstein, Maciej

2018-05-01

Recently it has been demonstrated that an ensemble of trapped ions may serve as a quantum annealer for the number-partitioning problem [Nat. Commun. 7, 11524 (2016), 10.1038/ncomms11524]. This hard computational problem may be addressed by employing a tunable spin-glass architecture. Following the proposal of the trapped-ion annealer, we study here its robustness against thermal effects; that is, we investigate the role played by thermal phonons. For the efficient description of the system, we use a semiclassical approach, and benchmark it against the exact quantum evolution. The aim is to understand better and characterize how the quantum device approaches a solution of an otherwise difficult to solve NP-hard problem.

Research on Inverse Kinematics Program Optimization of 6R Decoupled Robot

Directory of Open Access Journals (Sweden)

Daode ZHANG

2014-02-01

Full Text Available According to complex analytic formula for the six degrees of freedom decoupled robot, a detailed analysis of the six degrees of freedom decoupled robot analytic formula of export process, as well the causes of multiple solutions. The method of increasing the local variables to avoid processor running the same statement repeatedly is proposed. The method to find the most frequency formula appeared in analytic solution replaced with local variables facilitate the use of loop to reduce the amount of code. It effectively reduces the computation time, optimize the computing process. Finally, taking PUMA560-like robot as an example, the calculation result is verified and simulated in Robotics Toolbox of MATLAB.

Semiclassical approximations for a momentum dependent one-body potential

International Nuclear Information System (INIS)

Dworzecka, M.; Moszkowski, S.A.

1976-08-01

Recently a semiclassical approximation was applied by Jennings, et al., for a system of noninteracting fermions in a local one-body potential. This is a way to calculate shell corrections alternative to Strutinsky's method. This method was generalized to a spherical but a momentum dependent potential of the form, V(r) + 1 / 2 (p 2 W(r) + W(r)p 2 ). Explicit expressions are developed for the number of particles and the smooth sum of single particle energies in terms of the Fermi energy and the one-body potential and its first two derivatives. They are calculated for selected values of the parameters and compared with the sum of single particle energies obtained by numerical solution of the Schroedinger equation. The difference between the two is evidently the shell correction

The semiclassical coherent state propagator in the Weyl representation

International Nuclear Information System (INIS)

Braun, Carol; Li, Feifei; Garg, Anupam; Stone, Michael

2015-01-01

It is shown that the semiclassical coherent state propagator takes its simplest form when the quantum mechanical Hamiltonian is replaced by its Weyl symbol in defining the classical action, in that there is then no need for a Solari-Kochetov correction. It is also shown that such a correction exists if a symbol other than the Weyl symbol is chosen and that its form is different depending on the symbol chosen. The various forms of the propagator based on different symbols are shown to be equivalent provided the correspondingly correct Solari-Kochetov correction is included. All these results are shown for both particle and spin coherent state propagators. The global anomaly in the fluctuation determinant is further elucidated by a study of the connection between the discrete fluctuation determinant and the discrete Jacobi equation

Visualizing decoupling in nanocrystalline alloys: A FORC-temperature analysis

Science.gov (United States)

Rivas, M.; Martínez-García, J. C.; Gorria, P.

2016-02-01

Devitrifying ferromagnetic amorphous precursors in the adequate conditions may give rise to disordered assemblies of densely packed nanocrystals with extraordinary magnetic softness well explained by the exchange coupling among multiple crystallites. Whether the magnetic exchange interaction is produced by direct contact or mediated by the intergranular amorphous matrix has a strong influence on the behaviour of the system above room temperature. Multi-phase amorphous-nanocrystalline systems dramatically harden when approaching the amorphous Curie temperature (TC) due to the hard grains decoupling. The study of the thermally induced decoupling of nanosized crystallites embedded in an amorphous matrix has been performed in this work by the first-order reversal curves (FORCs) analysis. We selected a Fe-rich amorphous alloy with TC = 330 K, in order to follow the evolution of the FORC diagrams obtained below and above such temperature in samples with different percentages of nanocrystalline phase. The existence of up to four regions exhibiting unlike magnetic behaviours is unambiguously determined from the temperature evolution of the FORC.

A Fully Symmetric and Completely Decoupled MEMS-SOI Gyroscope

Directory of Open Access Journals (Sweden)

Abdelhameed SHARAF

2011-04-01

Full Text Available This paper introduces a novel MEMS gyroscope that is capable of exciting the drive mode differentially. The structure also decouples the drive and sense modes via an intermediate mass and decoupling beams. Both drive and sense modes are fully differential enabling control over the zero-rate-output for the former and maximizing output sensitivity using a bridge circuit for the latter. Further, the structure is fully symmetric about the x- and y- axes which results in minimizing the temperature sensitivity problem. Complete analytical analysis based on the equations of motion was performed and verified using two commercially available finite element software packages. Results from both methods are in good agreement. The analysis of the sensor shows an electrical sensitivity of 1.14 (mV/(º/s. The gyroscope was fabricated using single mask and deep reactive ion etching. The measurement of the resonance frequency performed showing a good agreement with the analytical and numerical analysis.

Decoupled Access-Execute on ARM big.LITTLE

OpenAIRE

Weber, Anton

2016-01-01

Decoupled Access-Execute (DAE) presents a novel approach to improve power efficiency with a combination of compile-time transformations and Dynamic Voltage Frequency Scaling (DVFS). DAE splits regions of the program into two distinct phases: a memory-bound access phase and a compute-bound execute phase. DVFS is used to run the phases at different frequencies, thus conserving energy while caching data from main memory and performing computations at maximum performance. This project analyses th...

Asia’s decoupling: fact, forecast or fiction?

OpenAIRE

Lillie Lam; James Yetman

2013-01-01

Standard measures of real economic co-movement between Asia-Pacific economies and those elsewhere had been observed to follow a downward trend, leading some commentators to suggest that the region was decoupling. However, this process reversed in response to the International Financial Crisis, and co-movement increased to historically high levels for some economies. We examine co-movement patterns and show that these are very sensitive to changes in macroeconomic volatility over time. Control...

Semi-classical approximation and the problem of boundary conditions in the theory of relativistic particle radiation

International Nuclear Information System (INIS)

Akhiezer, A.I.; Shul'ga, N.F.

1991-01-01

The process of relativistic particle radiation in an external field has been studied in the semi-classical approximation rather extensively. The main problem arising in the studies is in expressing the formula of the quantum theory of radiation in terms of classical quantities, for example of the classical trajectories. However, it still remains unclear how the particle trajectory is assigned, that is which particular initial or boundary conditions determine the trajectory in semi-classical approximation quantum theory of radiation. We shall try to solve this problem. Its importance comes from the fact that in some cases one and the same boundary conditions may give rise to two or more trajectories. We demonstrate that this fact must necessarily be taken into account on deriving the classical limit for the formulae of the quantum theory of radiation, since it leads to a specific interference effect in radiation. The method we used to deal with the problem is similar to the method employed by Fock to analyze the problem of a canonical transformation in classical and quantum mechanics. (author)

Decoupling of Fluctuating Power in Single-Phase Systems Through a Symmetrical Half-Bridge Circuit

DEFF Research Database (Denmark)

Tang, Yi; Blaabjerg, Frede; Loh, Poh Chiang

2015-01-01

approach may inevitably lead to low power density and limited system lifetime. An alternative approach is to use active power decoupling so that the ripple power can be diverted into other energy storage devices to gain an improved system performance. Nevertheless, all existing active methods have...... power decoupling method, and both the input current and output voltage of the converter can be well regulated even when very small dc-link capacitors are employed....

Supercritical water gasification with decoupled pressure and heat transfer modules

KAUST Repository

Dibble, Robert W.; Ng, Kim Choon; Sarathy, Mani

2017-01-01

decouples the function of containing high pressure from the high temperature function. The present invention allows the heat transfer function to be conducted independently from the pressure transfer function such that the system equipment can be designed

The semiclassical S-matrix theory of three body Coulomb break-up

International Nuclear Information System (INIS)

Chocian, P.

1999-01-01

Using semiclassical methods we investigate the threshold behaviour for 3-particle break-up of a system with one particle of charge Z and two other particles of charge -q. For the particular case where the ratio of the charges of the third particle to the wing particles is Z/q = 1/4, the Wannier exponent for break-up diverges and it is found that the threshold law changes from a power law to an exponential law of the form exp(-λ/√E) which is in agreement with other results. Wannier's threshold theory is extended analytically to above threshold energies and it is found that the classical law for the divergent case is identical to an analytical result from the quantal hidden crossing theory. Corrections to the threshold behaviour for hydrogen from the above-threshold derivation are compared with those predicted by a calculation from hidden crossing theory. Excellent agreement is found which confirms the success of our classical derivation. The threshold behaviour is tested using semiclassical S-matrix theory above the region of divergence and it is found that for Z/q - of the initial states in S-matrix theory translates to a uniform distribution of outgoing trajectories on the boundary of the reaction zone. Observations of classical trajectories suggest that the radius of the reaction zone (R b ) is dependent on the total energy of the system. R b is determined numerically from ionization trajectories. When the dependence on R b is included in half-collision calculations, cross sections are produced which are in excellent agreement with full-collision S-matrix results for all values of Z > 0.25. (author)