Harmonic polynomials, hyperspherical harmonics, and atomic spectra
Avery, John Scales
2010-01-01
The properties of monomials, homogeneous polynomials and harmonic polynomials in d-dimensional spaces are discussed. The properties are shown to lead to formulas for the canonical decomposition of homogeneous polynomials and formulas for harmonic projection. Many important properties of spherical harmonics, Gegenbauer polynomials and hyperspherical harmonics follow from these formulas. Harmonic projection also provides alternative ways of treating angular momentum and generalised angular momentum. Several powerful theorems for angular integration and hyperangular integration can be derived in this way. These purely mathematical considerations have important physical applications because hyperspherical harmonics are related to Coulomb Sturmians through the Fock projection, and because both Sturmians and generalised Sturmians have shown themselves to be extremely useful in the quantum theory of atoms and molecules.
Hyperspherical Harmonics and Their Physical Applications
DEFF Research Database (Denmark)
Avery, James Emil; Avery, John Scales
Hyperspherical harmonics are extremely useful in nuclear physics and reactive scattering theory. However, their use has been confined to specialists with very strong backgrounds in mathematics. This book aims to change the theory of hyperspherical harmonics from an esoteric field, mastered...
Hyperspherical harmonics expansion techniques application to problems in physics
Das, Tapan Kumar
2016-01-01
The book provides a generalized theoretical technique for solving the fewbody Schrödinger equation. Straight forward approaches to solve it in terms of position vectors of constituent particles and using standard mathematical techniques become too cumbersome and inconvenient when the system contains more than two particles. The introduction of Jacobi vectors, hyperspherical variables and hyperspherical harmonics as an expansion basis is an elegant way to tackle systematically the problem of an increasing number of interacting particles. Analytic expressions for hyperspherical harmonics, appropriate symmetrisation of the wave function under exchange of identical particles and calculation of matrix elements of the interaction have been presented. Applications of this technique to various problems of physics have been discussed. In spite of straight forward generalization of the mathematical tools for increasing number of particles, the method becomes computationally difficult for more than a few particles. Hen...
Molecular integrals for exponential-type orbitals using hyperspherical harmonics
DEFF Research Database (Denmark)
Avery, James Emil; Avery, John Scales
2015-01-01
Exponential-type orbitals are better suited to calculations of molecular electronic structure than are Gaussians, since ETO's can accurately represent the behavior of molecular orbitals near to atomic nuclei, as well as their long-distance exponential decay. Orbitals based on Gaussians fail in both...... these respects. Nevertheless, Gaussian technology continues to dominate computational quantum chemistry, because of the ease with which difficult molecular integrals may be evaluated when Gaussians are used as a basis.In the present chapter, we hope to contribute to a new movement in quantum chemistry, in which......-dimensional hypersphere. Using this projection, Fock was able to show that the Fourier transforms of Coulomb Sturmian basis functions are very simply related to four-dimensional hyperspherical harmonics.With the help of Fock's relationships and the theory of hyperspherical harmonics we are able to evaluate molecular...
Hyperspherical Harmonics Expansion on Lagrange Meshes for Bosonic Systems in One Dimension
Timofeyuk, N. K.; Baye, D.
2017-12-01
A one-dimensional system of bosons interacting with contact and single-Gaussian forces is studied with an expansion in hyperspherical harmonics. The hyperradial potentials are calculated using the link between the hyperspherical harmonics and the single-particle harmonic-oscillator basis while the coupled hyperradial equations are solved with the Lagrange-mesh method. Extensions of this method are proposed to achieve good convergence with small numbers of mesh points for any truncation of hypermomentum. The convergence with hypermomentum strongly depends on the range of the two-body forces: it is very good for large ranges but deteriorates as the range decreases, being the worst for the contact interaction. In all cases, the lowest-order energy is within 4.5% of the exact solution and shows the correct cubic asymptotic behaviour at large boson numbers. Details of the convergence studies are presented for 3, 5, 20 and 100 bosons. A special treatment for three bosons was found to be necessary. For single-Gaussian interactions, the convergence rate improves with increasing boson number, similar to what happens in the case of three-dimensional systems of bosons.
Hyperspherical Slater determinant approach to few-body fractional quantum Hall states
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Yan, Bin, E-mail: yanbin@purdue.edu; Wooten, Rachel E.; Daily, Kevin M.; Greene, Chris H.
2017-05-15
In a recent study (Daily et al., 2015), a hyperspherical approach has been developed to study few-body fractional quantum Hall states. This method has been successfully applied to the exploration of few boson and fermion problems in the quantum Hall region, as well as the study of inter-Landau level collective excitations (Rittenhouse et al., 2016; Wooten et al., 2016). However, the hyperspherical method as it is normally implemented requires a subsidiary (anti-)symmetrization process, which limits its computational effectiveness. The present work overcomes these difficulties and extends the power of this method by implementing a representation of the hyperspherical many-body basis space in terms of Slater determinants of single particle eigenfunctions. A clear connection between the hyperspherical representation and the conventional single particle picture is presented, along with a compact operator representation of the theoretical framework. - Highlights: • A hyperspherical method has been implemented to study the quantum Hall effect. • The hyperspherical many-body basis space is represented with Slater determinants. • Example numerical studies of the 4- and 8-electron systems are presented.
Directory of Open Access Journals (Sweden)
Igor Salom
2017-07-01
Full Text Available We construct the three-body permutation symmetric hyperspherical harmonics to be used in the non-relativistic three-body Schrödinger equation in three spatial dimensions (3D. We label the state vectors according to the S3⊗SO(3rot⊂O(2⊗SO(3rot⊂U(3⋊S2⊂O(6 subgroup chain, where S3 is the three-body permutation group and S2 is its two element subgroup containing transposition of first two particles, O(2 is the “democracy transformation”, or “kinematic rotation” group for three particles; SO(3rot is the 3D rotation group, and U(3,O(6 are the usual Lie groups. We discuss the good quantum numbers implied by the above chain of algebras, as well as their relation to the S3 permutation properties of the harmonics, particularly in view of the SO(3rot⊂SU(3 degeneracy. We provide a definite, practically implementable algorithm for the calculation of harmonics with arbitrary finite integer values of the hyper angular momentum K, and show an explicit example of this construction in a specific case with degeneracy, as well as tables of K≤6 harmonics. All harmonics are expressed as homogeneous polynomials in the Jacobi vectors (λ,ρ with coefficients given as algebraic numbers unless the “operator method” is chosen for the lifting of the SO(3rot⊂SU(3 multiplicity and the dimension of the degenerate subspace is greater than four – in which case one must resort to numerical diagonalization; the latter condition is not met by any K≤15 harmonic, or by any L≤7 harmonic with arbitrary K. We also calculate a certain type of matrix elements (the Gaunt integrals of products of three harmonics in two ways: 1 by explicit evaluation of integrals and 2 by reduction to known SU(3 Clebsch–Gordan coefficients. In this way we complete the calculation of the ingredients sufficient for the solution to the quantum-mechanical three-body bound state problem.
Spherical hashing: binary code embedding with hyperspheres.
Heo, Jae-Pil; Lee, Youngwoon; He, Junfeng; Chang, Shih-Fu; Yoon, Sung-Eui
2015-11-01
Many binary code embedding schemes have been actively studied recently, since they can provide efficient similarity search, and compact data representations suitable for handling large scale image databases. Existing binary code embedding techniques encode high-dimensional data by using hyperplane-based hashing functions. In this paper we propose a novel hypersphere-based hashing function, spherical hashing, to map more spatially coherent data points into a binary code compared to hyperplane-based hashing functions. We also propose a new binary code distance function, spherical Hamming distance, tailored for our hypersphere-based binary coding scheme, and design an efficient iterative optimization process to achieve both balanced partitioning for each hash function and independence between hashing functions. Furthermore, we generalize spherical hashing to support various similarity measures defined by kernel functions. Our extensive experiments show that our spherical hashing technique significantly outperforms state-of-the-art techniques based on hyperplanes across various benchmarks with sizes ranging from one to 75 million of GIST, BoW and VLAD descriptors. The performance gains are consistent and large, up to 100 percent improvements over the second best method among tested methods. These results confirm the unique merits of using hyperspheres to encode proximity regions in high-dimensional spaces. Finally, our method is intuitive and easy to implement.
Green's Functions and the Adiabatic Hyperspherical Method
Rittenhouse, Seth T; Greene, Chris H
2010-01-01
We address the few-body problem using the adiabatic hyperspherical representation. A general form for the hyperangular Green's function in $d$-dimensions is derived. The resulting Lippmann-Schwinger equation is solved for the case of three-particles with s-wave zero-range interactions. Identical particle symmetry is incorporated in a general and intuitive way. Complete semi-analytic expressions for the nonadiabatic channel couplings are derived. Finally, a model to describe the atom-loss due to three-body recombination for a three-component fermi-gas of $^{6}$Li atoms is presented.
Ganeev, Rashid A
2014-01-01
Preface; Why plasma harmonics? A very brief introduction Early stage of plasma harmonic studies - hopes and frustrations New developments in plasma harmonics studies: first successes Improvements of plasma harmonics; Theoretical basics of plasma harmonics; Basics of HHG Harmonic generation in fullerenes using few-cycle pulsesVarious approaches for description of observed peculiarities of resonant enhancement of a single harmonic in laser plasmaTwo-colour pump resonance-induced enhancement of odd and even harmonics from a tin plasmaCalculations of single harmonic generation from Mn plasma;Low-o
Cator, Lauren J; Zanti, Zacharo
2016-12-01
Several new mosquito control strategies will involve the release of laboratory reared males which will be required to compete with wild males for mates. Currently, the determinants of male mating success remain unclear. The presence of convergence between male and female harmonic flight tone frequencies during a mating attempt have been found to increase male mating success in the yellow fever mosquito, Aedes aegypti. Size has also been implicated as a factor in male mating success. Here, we investigated the relationships among body size, harmonic convergence signalling, and mating success. We predicted that harmonic convergence would be an important determinant of mating success and that large individuals would be more likely to converge. We used diet to manipulate male and female body size and then measured acoustic interactions during mating attempts between pairs of different body sizes. Additionally, we used playback experiments to measure the direct effect of size on signalling performance. In live pair interactions, harmonic convergence was found to be a significant predictor of copula formation. However, we also found interactions between harmonic convergence behaviour and body size. The probability that a given male successfully formed a copula was a consequence of his size, the size of the female encountered, and whether or not they converged. While convergence appears to be predictive of mating success regardless of size, the positive effect of convergence was modulated by size combinations. In playbacks, adult body size did not affect the probability of harmonic convergence responses. Both body size and harmonic convergence signalling were found to be determinants of male mating success. Our results suggest that in addition to measuring convergence ability of mass release lines that the size distribution of released males may need to be adjusted to complement the size distribution of females. We also found that diet amount alone cannot be used to
Agglomerative concentric hypersphere clustering applied to structural damage detection
Silva, Moisés; Santos, Adam; Santos, Reginaldo; Figueiredo, Eloi; Sales, Claudomiro; Costa, João C. W. A.
2017-08-01
The present paper proposes a novel cluster-based method, named as agglomerative concentric hypersphere (ACH), to detect structural damage in engineering structures. Continuous structural monitoring systems often require unsupervised approaches to automatically infer the health condition of a structure. However, when a structure is under linear and nonlinear effects caused by environmental and operational variability, data normalization procedures are also required to overcome these effects. The proposed approach aims, through a straightforward clustering procedure, to discover automatically the optimal number of clusters, representing the main state conditions of a structural system. Three initialization procedures are introduced to evaluate the impact of deterministic and stochastic initializations on the performance of this approach. The ACH is compared to state-of-the-art approaches, based on Gaussian mixture models and Mahalanobis squared distance, on standard data sets from a post-tensioned bridge located in Switzerland: the Z-24 Bridge. The proposed approach demonstrates more efficiency in modeling the normal condition of the structure and its corresponding main clusters. Furthermore, it reveals a better classification performance than the alternative ones in terms of false-positive and false-negative indications of damage, demonstrating a promising applicability in real-world structural health monitoring scenarios.
State-to-state three-atom time-dependent reactive scattering in hyperspherical coordinates.
Crawford, Jeff; Parker, Gregory A
2013-02-07
We present a time-dependent, hyperspherical wave packet method for calculating three-atom state-to-state S-matrix elements. The wave packet is propagated in time using adiabatically adjusting, principal axes hyperspherical coordinates that treat all arrangement channels equivalently, allowing the simultaneous analysis of the products in all three arrangement channels. We take advantage of the symmetry of the potential energy surface and decompose the initial wave packet into its component irreducible representations, propagating each component separately. Each irreducible representation component of the wave packet is analyzed by projecting it onto the hyperspherical basis at a fixed, asymptotic hyperradius, and irreducible representation dependent S-matrix elements are obtained by matching the hyperspherical projections to symmetry-adapted Jacobi coordinate boundary conditions. We obtain arrangement channel-dependent S-matrix elements as linear combinations of the irreducible representation dependent elements. State-to-state H + H(2) and F + H(2) results for zero total angular momentum are presented.
A hyper-spherical adaptive sparse-grid method for high-dimensional discontinuity detection
Energy Technology Data Exchange (ETDEWEB)
Zhang, Guannan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Webster, Clayton G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gunzburger, Max D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Burkardt, John V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2014-03-01
This work proposes and analyzes a hyper-spherical adaptive hierarchical sparse-grid method for detecting jump discontinuities of functions in high-dimensional spaces is proposed. The method is motivated by the theoretical and computational inefficiencies of well-known adaptive sparse-grid methods for discontinuity detection. Our novel approach constructs a function representation of the discontinuity hyper-surface of an N-dimensional dis- continuous quantity of interest, by virtue of a hyper-spherical transformation. Then, a sparse-grid approximation of the transformed function is built in the hyper-spherical coordinate system, whose value at each point is estimated by solving a one-dimensional discontinuity detection problem. Due to the smoothness of the hyper-surface, the new technique can identify jump discontinuities with significantly reduced computational cost, compared to existing methods. Moreover, hierarchical acceleration techniques are also incorporated to further reduce the overall complexity. Rigorous error estimates and complexity analyses of the new method are provided as are several numerical examples that illustrate the effectiveness of the approach.
Directory of Open Access Journals (Sweden)
Kezerashvili Roman Ya.
2014-01-01
Full Text Available The kaonic clusters K̄NN and K̄NNN are studied within the method of hyperspherical functions in the momentum representation. Binding energies and widths of three- and four-body nuclear quasibound states are calculated by employing realistic NN potentials and the energy dependent chiral K̄N interaction, as well as a phenomenological K̄N potential. The comparison of the results of calculations obtained in the framework of the variational method, Faddeev, Faddeev-Yakubovsky equations, and method of hyperspherical functions in configuration space are discussed.
Attracting subspaces in a hyper-spherical representation of autonomous dynamical systems
Ceccato, Alessandro; Nicolini, Paolo; Frezzato, Diego
2017-09-01
In this work, we focus on the possibility to recast the ordinary differential equations (ODEs) governing the evolution of deterministic autonomous dynamical systems (conservative or damped and generally non-linear) into a parameter-free universal format. We term such a representation "hyper-spherical" since the new variables are a "radial" norm having physical units of inverse-of-time and a normalized "state vector" with (possibly complex-valued) dimensionless components. Here we prove that while the system evolves in its physical space, the mirrored evolution in the hyper-spherical space is such that the state vector moves monotonically towards fixed "attracting subspaces" (one at a time). Correspondingly, the physical space can be split into "attractiveness regions." We present the general concepts and provide an example of how such a transformation of ODEs can be achieved for a class of mechanical-like systems where the physical variables are a set of configurational degrees of freedom and the associated velocities in a phase-space representation. A one-dimensional case model (motion in a bi-stable potential) is adopted to illustrate the procedure.
Hyperspherical Manifold for EEG Signals of Epileptic Seizures
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Tahir Ahmad
2012-01-01
Full Text Available The mathematical modelling of EEG signals of epileptic seizures presents a challenge as seizure data is erratic, often with no visible trend. Limitations in existing models indicate a need for a generalized model that can be used to analyze seizures without the need for apriori information, whilst minimizing the loss of signal data due to smoothing. This paper utilizes measure theory to design a discrete probability measure that reformats EEG data without altering its geometric structure. An analysis of EEG data from three patients experiencing epileptic seizures is made using the developed measure, resulting in successful identification of increased potential difference in portions of the brain that correspond to physical symptoms demonstrated by the patients. A mapping then is devised to transport the measure data onto the surface of a high-dimensional manifold, enabling the analysis of seizures using directional statistics and manifold theory. The subset of seizure signals on the manifold is shown to be a topological space, verifying Ahmad's approach to use topological modelling.
Integrable Families of Hard-Core Particles with Unequal Masses in a One-Dimensional Harmonic Trap
Harshman, N. L.; Olshanii, Maxim; Dehkharghani, A. S.; Volosniev, A. G.; Jackson, Steven Glenn; Zinner, N. T.
2017-10-01
We show that the dynamics of particles in a one-dimensional harmonic trap with hard-core interactions can be solvable for certain arrangements of unequal masses. For any number of particles, there exist two families of unequal mass particles that have integrable dynamics, and there are additional exceptional cases for three, four, and five particles. The integrable mass families are classified by Coxeter reflection groups and the corresponding solutions are Bethe-ansatz-like superpositions of hyperspherical harmonics in the relative hyperangular coordinates that are then restricted to sectors of fixed particle order. We also provide evidence for superintegrability of these Coxeter mass families and conjecture maximal superintegrability.
Energy Technology Data Exchange (ETDEWEB)
Eliazar, Iddo, E-mail: eliazar@post.tau.ac.il
2017-05-15
The exponential, the normal, and the Poisson statistical laws are of major importance due to their universality. Harmonic statistics are as universal as the three aforementioned laws, but yet they fall short in their ‘public relations’ for the following reason: the full scope of harmonic statistics cannot be described in terms of a statistical law. In this paper we describe harmonic statistics, in their full scope, via an object termed harmonic Poisson process: a Poisson process, over the positive half-line, with a harmonic intensity. The paper reviews the harmonic Poisson process, investigates its properties, and presents the connections of this object to an assortment of topics: uniform statistics, scale invariance, random multiplicative perturbations, Pareto and inverse-Pareto statistics, exponential growth and exponential decay, power-law renormalization, convergence and domains of attraction, the Langevin equation, diffusions, Benford’s law, and 1/f noise. - Highlights: • Harmonic statistics are described and reviewed in detail. • Connections to various statistical laws are established. • Connections to perturbation, renormalization and dynamics are established.
Hadron spectra from a non-relativistic model with confining harmonic potential
Directory of Open Access Journals (Sweden)
Cuervo-Reyes Eduardo
2003-01-01
Full Text Available Hadron spectra and other properties of quark systems are studied in the framework of a non-relativistic spinindependent phenomenological model. The chosen confining potential is harmonic, which allowed us to obtain analytical solutions for both meson and baryon (of equal constituent quarks spectra. The introduced parameters are fixed from the low-lying levels of heavy quark mesons. The requirement of flavor independence is imposed, and it restricts the possible choices of inter-quark potentials. The hyper-spherical coordinates are considered for the solution of the three-body problem.
A new dipolar potential for numerical simulations of polar fluids on the 4D hypersphere
Caillol, Jean-Michel; Trulsson, Martin
2014-09-01
We present a new method for Monte Carlo or Molecular Dynamics numerical simulations of three-dimensional polar fluids. The simulation cell is defined to be the surface of the northern hemisphere of a four-dimensional (hyper)sphere. The point dipoles are constrained to remain tangent to the sphere and their interactions are derived from the basic laws of electrostatics in this geometry. The dipole-dipole potential has two singularities which correspond to the following boundary conditions: when a dipole leaves the northern hemisphere at some point of the equator, it reappears at the antipodal point bearing the same dipole moment. We derive all the formal expressions needed to obtain the thermodynamic and structural properties of a polar liquid at thermal equilibrium in actual numerical simulation. We notably establish the expression of the static dielectric constant of the fluid as well as the behavior of the pair correlation at large distances. We report and discuss the results of extensive numerical Monte Carlo simulations for two reference states of a fluid of dipolar hard spheres and compare these results with previous methods with a special emphasis on finite size effects.
Indian Academy of Sciences (India)
Harish-Chandra, Gelfand and several other mathematicians and physicists, group-theoretic harmonic analysis is a flourishing industry today paving the way to new developments in the con- text of noncompact Lie groups as well as quantum groups. Since B(n, z) = zn the expansion (3) suggests a link between Fourier series.
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 10. Harmonic Analysis Fourier Series and Beyond. K R Parthasarathy. Book Review Volume 1 Issue 10 October 1996 pp 87-91. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/001/10/0087-0091 ...
Bennett, Charles L [Livermore, CA
2009-10-20
A high efficiency harmonic engine based on a resonantly reciprocating piston expander that extracts work from heat and pressurizes working fluid in a reciprocating piston compressor. The engine preferably includes harmonic oscillator valves capable of oscillating at a resonant frequency for controlling the flow of working fluid into and out of the expander, and also preferably includes a shunt line connecting an expansion chamber of the expander to a buffer chamber of the expander for minimizing pressure variations in the fluidic circuit of the engine. The engine is especially designed to operate with very high temperature input to the expander and very low temperature input to the compressor, to produce very high thermal conversion efficiency.
Bennett, Charles L.; Sewall, Noel; Boroa, Carl
2014-08-19
An engine based on a reciprocating piston engine that extracts work from pressurized working fluid. The engine includes a harmonic oscillator inlet valve capable of oscillating at a resonant frequency for controlling the flow of working fluid into of the engine. In particular, the inlet valve includes an inlet valve head and a spring arranged together as a harmonic oscillator so that the inlet valve head is moveable from an unbiased equilibrium position to a biased closed position occluding an inlet. Upon releasing the inlet valve the inlet valve head undergoes a single oscillation past the equilibrium positio to a maximum open position and returns to a biased return position close to the closed position to choke the flow and produce a pressure drop across the inlet valve causing the inlet valve to close. Protrusions carried either by the inlet valve head or piston head are used to bump open the inlet valve from the closed position and initiate the single oscillation of the inlet valve head, and protrusions carried either by the outlet valve head or piston head are used to close the outlet valve ahead of the bump opening of the inlet valve.
Helson, Henry
2010-01-01
This second edition has been enlarged and considerably rewritten. Among the new topics are infinite product spaces with applications to probability, disintegration of measures on product spaces, positive definite functions on the line, and additional information about Weyl's theorems on equidistribution. Topics that have continued from the first edition include Minkowski's theorem, measures with bounded powers, idempotent measures, spectral sets of bounded functions and a theorem of Szego, and the Wiener Tauberian theorem. Readers of the book should have studied the Lebesgue integral, the elementary theory of analytic and harmonic functions, and the basic theory of Banach spaces. The treatment is classical and as simple as possible. This is an instructional book, not a treatise. Mathematics students interested in analysis will find here what they need to know about Fourier analysis. Physicists and others can use the book as a reference for more advanced topics.
Phononic High Harmonic Generation
Ganesan, Adarsh; Do, Cuong; Seshia, Ashwin A.
2016-01-01
This paper reports the first experimental evidence for phononic low-order to high-order harmonic conversion leading to high harmonic generation. Similar to parametric resonance, phononic high harmonic generation is also mediated by a threshold dependent instability of a driven phonon mode. Once the threshold for instability is met, a cascade of harmonic generation processes is triggered. Firstly, the up-conversion of first harmonic phonons into second harmonic phonons is established. Subseque...
Directory of Open Access Journals (Sweden)
Piotr FOLĘGA
2014-03-01
Full Text Available The variety of types and sizes currently in production harmonic drive is a problem in their rational choice. Properly selected harmonic drive must meet certain requirements during operation, and achieve the anticipated service life. The paper discusses the problems associated with the selection of the harmonic drive. It also presents the algorithm correct choice of harmonic drive. The main objective of this study was to develop a computer program that allows the correct choice of harmonic drive by developed algorithm.
A three-body force model for the harmonic and anharmonic oscillator
Directory of Open Access Journals (Sweden)
A. A. Rajabi
2005-06-01
Full Text Available We present a mathematical method to describe motion of a system based on 3 identical body forces. The 3-body forces are more easily introduced and treated within the hyperspherical harmonics. We have obtained an exact solution of the radial Schrödinger equation for a 3- body system in three dimensions. The interact potential V is assumed to depend on the hyperradius X only where X is a function of the Jacobi relative coordinates ρ and λ which are functions of the three identical particles, relative positions r12 , r23 and r31 . This method has been extensively used in nuclear and molecular physics. This work is interesting to those who are studying hadronic and bosonics physics and problems consisting three - body systems.
Harmonic Morphisms Projecting Harmonic Functions to Harmonic Functions
Mustafa, M. T.
2012-01-01
For Riemannian manifolds $M$ and $N$ , admitting a submersion $\\varphi $ with compact fibres, we introduce the projection of a function via its decomposition intohorizontal and vertical components. By comparing the Laplacians on $M$ and $N$ , we determine conditions under which a harmonic function on $U={\\varphi }^{-1}(V)\\subset M$ projects down, via its horizontal component, to a harmonic function on $V\\subset N$ .
Heemink, Arnold; de Jong, B.; Prins, Harrie
1991-01-01
In this paper we describe a new approach to the harmonic analysis of the tide. For a number of reasons the harmonic constants are not really constant but vary slowly in time. Therefore, we introduce a narrow-band noise process to model the time-varying behaviour of these harmonic parameters.
Axler, Sheldon; Ramey, Wade
2013-01-01
This is a book about harmonic functions in Euclidean space. Readers with a background in real and complex analysis at the beginning graduate level will feel comfortable with the material presented here. The authors have taken unusual care to motivate concepts and simplify proofs. Topics include: basic properties of harmonic functions, Poisson integrals, the Kelvin transform, spherical harmonics, harmonic Hardy spaces, harmonic Bergman spaces, the decomposition theorem, Laurent expansions, isolated singularities, and the Dirichlet problem. The new edition contains a completely rewritten chapter on spherical harmonics, a new section on extensions of Bocher's Theorem, new exercises and proofs, as well as revisions throughout to improve the text. A unique software package-designed by the authors and available by e-mail - supplements the text for readers who wish to explore harmonic function theory on a computer.
The Harmonics of Kansei Images
DEFF Research Database (Denmark)
Su, Jianning; Restrepo-Giraldo, John Dairo
2008-01-01
Delivering the right product experience, which is a user’s reflection of a combination of functionality, usage, cost and appearance, is a key factor for product acquisition and commercial success. Establishing and representing the relation between a product’s shape and the perceived aesthetic...... sensibility it elicits on a person (kansei), is a key factor in the design of tools to support designers in delivering the right product’s appearance. This paper presents an approach to mathematically represent a product’s kansei based on the frequency signature (harmonics) of a shape. This mathematical...
W.H. van Boom (Willem)
2009-01-01
textabstractThis paper presents a review of the literature on comparative tort law and economics. It pays special attention to the economics arguments against and in favour of harmonization of tort law in Europe.
Chen, Shigao; Kinnick, Randall R; Greenleaf, James F; Fatemi, Mostafa
2007-07-01
Vibro-acoustography is an imaging method that uses the radiation force of two interfering ultrasound beams of slightly different frequency to probe an object. An image is made using the acoustic emission resulted from the object vibration at the difference frequency. In this paper, the feasibility of imaging objects at twice the difference frequency (harmonic acoustic emission) is studied. Several possible origins of harmonic acoustic emission are explored. As an example, it is shown that microbubbles close to resonance can produce significant harmonic acoustic emission due to its high nonlinearity. Experiments demonstrate that, compared to the fundamental acoustic emission, harmonic acoustic emission greatly improves the contrast between microbubbles and other objects in vibro-acoustography (an improvement of 17-23 dB in these experiments). Applications of this technique include imaging the nonlinearity of the object and selective detection of microbubbles for perfusion imaging. The impact of microbubble destruction during the imaging process also is discussed.
DEFF Research Database (Denmark)
Nielsen, Jesper Kjær; Jensen, Tobias Lindstrøm; Jensen, Jesper Rindom
2017-01-01
The harmonic chirp signal model has only very recently been in- troduced for modelling approximately periodic signals with a time- varying fundamental frequency. A number of estimators for the pa- rameters of this model have already been proposed, but they are ei- ther inaccurate, non-robust to n......The harmonic chirp signal model has only very recently been in- troduced for modelling approximately periodic signals with a time- varying fundamental frequency. A number of estimators for the pa- rameters of this model have already been proposed, but they are ei- ther inaccurate, non......-robust to noise, or very computationally inten- sive. In this paper, we propose a fast algorithm for the harmonic chirp summation method which has been demonstrated in the liter- ature to be accurate and robust to noise. The proposed algorithm is orders of magnitudes faster than previous algorithms which is also...
Bennett, Charles L.
2016-03-22
A reciprocating-piston uniflow engine includes a harmonic oscillator inlet valve capable of oscillating at a resonant frequency for controlling the flow of working fluid into the engine. In particular, the inlet valve includes an inlet valve head and a spring arranged together as a harmonic oscillator so that the inlet valve head is moveable from an unbiased equilibrium position to a biased closed position occluding an inlet. When released, the inlet valve head undergoes a single oscillation past the equilibrium position to a maximum open position and returns to a biased return position close to the closed position to choke the flow and produce a pressure drop across the inlet valve causing the inlet valve to close. In other embodiments, the harmonic oscillator arrangement of the inlet valve enables the uniflow engine to be reversibly operated as a uniflow compressor.
Second harmonic generation imaging
2013-01-01
Second-harmonic generation (SHG) microscopy has shown great promise for imaging live cells and tissues, with applications in basic science, medical research, and tissue engineering. Second Harmonic Generation Imaging offers a complete guide to this optical modality, from basic principles, instrumentation, methods, and image analysis to biomedical applications. The book features contributions by experts in second-harmonic imaging, including many pioneering researchers in the field. Written for researchers at all levels, it takes an in-depth look at the current state of the art and possibilities of SHG microscopy. Organized into three sections, the book: Provides an introduction to the physics of the process, step-by-step instructions on how to build an SHG microscope, and comparisons with related imaging techniques Gives an overview of the capabilities of SHG microscopy for imaging tissues and cells—including cell membranes, muscle, collagen in tissues, and microtubules in live cells—by summarizing experi...
General Criterion for Harmonicity
Proesmans, Karel; Vandebroek, Hans; Van den Broeck, Christian
2017-10-01
Inspired by Kubo-Anderson Markov processes, we introduce a new class of transfer matrices whose largest eigenvalue is determined by a simple explicit algebraic equation. Applications include the free energy calculation for various equilibrium systems and a general criterion for perfect harmonicity, i.e., a free energy that is exactly quadratic in the external field. As an illustration, we construct a "perfect spring," namely, a polymer with non-Gaussian, exponentially distributed subunits which, nevertheless, remains harmonic until it is fully stretched. This surprising discovery is confirmed by Monte Carlo and Langevin simulations.
Harmonic arbitrary waveform generator
Energy Technology Data Exchange (ETDEWEB)
Roberts, Brock Franklin
2017-11-28
High frequency arbitrary waveforms have applications in radar, communications, medical imaging, therapy, electronic warfare, and charged particle acceleration and control. State of the art arbitrary waveform generators are limited in the frequency they can operate by the speed of the Digital to Analog converters that directly create their arbitrary waveforms. The architecture of the Harmonic Arbitrary Waveform Generator allows the phase and amplitude of the high frequency content of waveforms to be controlled without taxing the Digital to Analog converters that control them. The Harmonic Arbitrary Waveform Generator converts a high frequency input, into a precision, adjustable, high frequency arbitrary waveform.
Quantum harmonically kicked environments
Custódio, M. S.; Strunz, W. T.; Beims, M. W.
2017-11-01
In this work we derive a generalized map which describes the time evolution of a quantum system coupled to a quantum environment composed by a finite number of free particles kicked harmonically at periodic times. Dissipation is introduced via the interaction between system and environment, which is switched on and off simultaneously at regular time intervals. The dynamics of the environmental particles occurs along rotated ellipsis in phase space and can be described by unrotated harmonic oscillators with a new frequency which depends on the kicking time. With the definition of a thermal bath we show that our quantum kicked environment induces an unusual fluctuation-dissipation relation.
Booster Double Harmonic Setup Notes
Energy Technology Data Exchange (ETDEWEB)
Gardner, C. J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.
2015-02-17
The motivation behind implementing a booster double harmonic include the reduced transverse space charge force from a reduced peak beam current and reduced momentum spread of the beam, both of which can be achieved from flattening the RF bucket. RF capture and acceleration of polarized protons (PP) is first set up in the single harmonic mode with RF harmonic h=1. Once capture and acceleration have been set up in the single harmonic mode, the second harmonic system is brought on and programmed to operate in concert with the single harmonic system.
Regulatory harmonization of the Saskatchewan uranium mines
Energy Technology Data Exchange (ETDEWEB)
Forbes, R. [Canadian Nuclear Safety Commission, Ottawa, Ontario (Canada); Moulding, T. [Saskatchewan Environment, Saskatchewan (Canada); Alderman, G. [Saskatchewan Labour, Saskatchewan (Canada)
2006-07-01
The uranium mining industry in Saskatchewan produces approximately 30% of the world's production of uranium. The industry is regulated by federal and provincial regulators. The Canadian Nuclear Safety Commission is the principal federal regulator. The principal Saskatchewan provincial regulators are Saskatchewan Environment for provincial environmental regulations and Saskatchewan Labour for occupational health and safety regulations. In the past, mine and mill operators have requested harmonization in areas such as inspections and reporting requirements from the regulators. On February 14, 2003, Saskatchewan Environment, Saskatchewan Labour and the Canadian Nuclear Safety Commission signed a historical agreement for federal/provincial co-operation called the Canadian Nuclear Safety Commission - Saskatchewan Administrative Agreement for the Regulation of Health, Safety and the Environment at Saskatchewan Uranium Mines and Mills. This initiative responds to a recommendation made by the Joint Federal-Provincial Panel on Uranium Mining Developments in Northern Saskatchewan in 1997 and lays the groundwork to co-ordinate and harmonize their respective regulatory regimes. The implementation of the Agreement has been very successful. This paper will address the content of the Agreement including the commitments, the deliverables and the expectations for a harmonized compliance program, harmonized reporting, and the review of harmonized assessment and licensing processes as well as possible referencing of Saskatchewan Environment and Saskatchewan Labour regulations in the Nuclear Safety and Control Act. The management and implementation process will also be discussed including the schedule, stakeholder communication, the results to date and the lessons learned. (author)
Harmonic Intravascular Ultrasound
M.E. Frijlink (Martijn)
2006-01-01
textabstractMedical ultrasound is a popular imaging modality in cardiology. Harmonic Imaging is a technique that has been shown to increase the image quality of diagnostic ultrasound at frequencies below 10 MHz. However, Intravascular Ultrasound, which is a technique to acoustically investigate
Young children's harmonic perception.
Costa-Giomi, Eugenia
2003-11-01
Harmony and tonality are two of the most difficult elements for young children to perceive and manipulate and are seldom taught in the schools until the end of early childhood. Children's gradual harmonic and tonal development has been attributed to their cumulative exposure to Western tonal music and their increasing experiential knowledge of its rules and principles. Two questions that are relevant to this problem are: (1) Can focused and systematic teaching accelerate the learning of the harmonic/tonal principles that seem to occur in an implicit way throughout childhood? (2) Are there cognitive constraints that make it difficult for young children to perceive and/or manipulate certain harmonic and tonal principles? A series of studies specifically addressed the first question and suggested some possible answers to the second one. Results showed that harmonic instruction has limited effects on children's perception of harmony and indicated that the drastic improvement in the perception of implied harmony noted approximately at age 9 is due to development rather than instruction. I propose that young children's difficulty in perceiving implied harmony stems from their attention behaviors. Older children have less memory constraints and more strategies to direct their attention to the relevant cues of the stimulus. Younger children focus their attention on the melody, if present in the stimulus, and specifically on its concrete elements such as rhythm, pitch, and contour rather than its abstract elements such as harmony and key. The inference of the abstract harmonic organization of a melody required in the perception of implied harmony is thus an elusive task for the young child.
Harmonic Patterns in Forex Trading
Nemček, Sebastian
2013-01-01
This diploma thesis is committed to examination of validity of Harmonic Patterns in Forex trading. Scott Carney described existing and introduced new Harmonic Patterns in 1999 in his book Harmonic Trader. These patterns use the Fibonacci principle to analyze price action and to provide both bullish and bearish trading signals. The goal of this thesis is to find out whether harmonic trading strategy on selected pairs is profitable in FX market, which patterns are the most profitable and what i...
Recursive Harmonic Numbers and Binomial Coefficients
Maw, Aung Phone; Kyaw, Aung
2017-01-01
We define recursive harmonic numbers as a generalization of harmonic numbers. The table of recursive harmonic numbers, which is like Pascal's triangle, is constructed. A formula for recursive harmonic numbers containing binomial coefficients is also presented.
Principles of harmonic analysis
Deitmar, Anton
2014-01-01
This book offers a complete and streamlined treatment of the central principles of abelian harmonic analysis: Pontryagin duality, the Plancherel theorem and the Poisson summation formula, as well as their respective generalizations to non-abelian groups, including the Selberg trace formula. The principles are then applied to spectral analysis of Heisenberg manifolds and Riemann surfaces. This new edition contains a new chapter on p-adic and adelic groups, as well as a complementary section on direct and projective limits. Many of the supporting proofs have been revised and refined. The book is an excellent resource for graduate students who wish to learn and understand harmonic analysis and for researchers seeking to apply it.
Harmonics in transmission power systems
DEFF Research Database (Denmark)
Wiechowski, Wojciech Tomasz
Some time ago, Energinet.dk, the Transmission System Operator of the 150 kV and 400 kV transmission network in Denmark, had experienced operational malfunctions of some of the measuring and protection equipment. Also an overloading of a harmonic filter has been reported, and therefore, a need...... to perform more detailed harmonic studies emerged. Since the transmission network has a complex structure and its impedance varies with frequency in a nonlinear fashion, such harmonic study would require a detailed computer model of the network. Consequently, a PhD project proposal titled "Harmonics......, provided that background harmonic distortion, and the network configuration, are not changing during the measurement. It is shown that switching of a shunt linear power system component can result in variation of the harmonic levels that can be measured and used to verify the harmonic model of the network...
Harmonic and geometric analysis
Citti, Giovanna; Pérez, Carlos; Sarti, Alessandro; Zhong, Xiao
2015-01-01
This book presents an expanded version of four series of lectures delivered by the authors at the CRM. Harmonic analysis, understood in a broad sense, has a very wide interplay with partial differential equations and in particular with the theory of quasiconformal mappings and its applications. Some areas in which real analysis has been extremely influential are PDE's and geometric analysis. Their foundations and subsequent developments made extensive use of the Calderón–Zygmund theory, especially the Lp inequalities for Calderón–Zygmund operators (Beurling transform and Riesz transform, among others) and the theory of Muckenhoupt weights. The first chapter is an application of harmonic analysis and the Heisenberg group to understanding human vision, while the second and third chapters cover some of the main topics on linear and multilinear harmonic analysis. The last serves as a comprehensive introduction to a deep result from De Giorgi, Moser and Nash on the regularity of elliptic partial differen...
Three-dimensional simulations of harmonic radiation and harmonic lasing
Energy Technology Data Exchange (ETDEWEB)
Schmitt, M.J.; McVey, B.D.
1990-01-01
Characteristics of the harmonic emission from free-electron lasers (FELs) are examined in the spontaneous, coherent-spontaneous and stimulated emission regimes. The radiation at both odd and even harmonic frequencies is treated for electron beams with finite emittance and energy spread. In the spontaneous emission regime, the transverse radiation patterns including the transverse frequency dependences, are given. How this expression is modified to include energy spread and emittance is described. In the coherent-spontaneous emission and stimulated emission regimes, the interaction of the radiation fields with the electrons must be treated self-consistently. Here, a single-frequency distributed transverse source function for each electron is used in the harmonic version of the 3-D code FELEX to model the harmonic radiation. The code has recently been modified to simultaneously model the fundamental and harmonic interactions for multiple-pass oscillator simulations. These modifications facilitate the examination of FELs under various operating conditions. When the FEL is lasing at the fundamental, the evolution of the harmonic fields can be examined. This evolution is unique in the sense that the electron beam radiates at the harmonic frequencies in the presence of the harmonic radiation circulating in the cavity. As a result, enhancements of the harmonic emission can be observed. Finally, harmonic lasing can occur in cases where there is sufficient gain to overcome cavity losses and lasing at the fundamental can be suppressed. The characteristics and efficiency of these interactions are explored. 11 refs., 9 figs.
Identification and control of harmonic distortions report on Furnas experience
Energy Technology Data Exchange (ETDEWEB)
Mantuano Filho, Salvatore; Medeiros, Jose Roberto de; Bezerra, Luiz Roberto; Oliveira, Denise Borges de; Praca, Antonio Augusto Souza; Paiva Fontes, Marco Antonio de; Marques, Luiz Carlos Borges C. [FURNAS, Rio de Janeiro, RJ (Brazil)
1994-12-31
This paper describes FURNAS experience on identification and control of harmonic distortions obtained from conservation of system operation and research for solutions. Special attention is paid to the harmonic overload observed at Ibiuna substation, the receiving end of the FURNAS HVDC transmission of the Itaipu 50 Hz energy, and the solutions that have been adopted. Methods of measurement and digital simulation have been developed and successfully tested so far. The present stage of those methods will be described. Not less important is the need for a specific legislation on harmonic distortion as explained in this paper. (author) 6 refs., 2 figs.
Second harmonic generation in Te crystal using free electron laser
Yamauchi, T; Minehara, E J
2002-01-01
The second harmonic generation signal converted from the fundamental wavelength of 22 mu m of a free electron laser was observed for the first time using a birefringent Te crystal. The experimental conversion efficiency of Te crystal for second harmonic generation is 0.53%, which is equivalent to the theoretical value within a factor of 2. The Te crystal has been incorporated into an autocorrelator system to measure the micro-pulse width of infrared free electron laser successfully. (author)
Energy Technology Data Exchange (ETDEWEB)
Ganeev, R A [Ophthalmology and Advanced Laser Medical Center, Saitama Medical University, Saitama 350-0495 (Japan)
2015-09-30
We discuss the emergence of interest in the high-order harmonic generation (HHG) of ultrashort pulses propagated through laser-produced plasmas. It is shown that, during the last few years, substantial amendments of plasma HHG allowed in some cases the characteristics of gas HHG to be surpassed. The attractiveness of a new approach in coherent extreme ultraviolet radiation generation is demonstrated, which can also be used as a tool for laser-ablation-induced HHG spectroscopy of a giant class of solids. We present general ideas and prospects for this relatively new field of nonlinear optics. (review)
Harmonic analysis and applications
Heil, Christopher
2007-01-01
This self-contained volume in honor of John J. Benedetto covers a wide range of topics in harmonic analysis and related areas. These include weighted-norm inequalities, frame theory, wavelet theory, time-frequency analysis, and sampling theory. The chapters are clustered by topic to provide authoritative expositions that will be of lasting interest. The original papers collected are written by prominent researchers and professionals in the field. The book pays tribute to John J. Benedetto's achievements and expresses an appreciation for the mathematical and personal inspiration he has given to
Harmonic Series Meets Fibonacci Sequence
Chen, Hongwei; Kennedy, Chris
2012-01-01
The terms of a conditionally convergent series may be rearranged to converge to any prescribed real value. What if the harmonic series is grouped into Fibonacci length blocks? Or the harmonic series is arranged in alternating Fibonacci length blocks? Or rearranged and alternated into separate blocks of even and odd terms of Fibonacci length?
Means of Harmonization in Religious Discourse
Directory of Open Access Journals (Sweden)
Irina Ščukina
2012-12-01
Full Text Available Means of harmonization of religious discourse are considered by studying communicational behaviour (verbal and nonverbal between the religion institution and believers. The following factors defining specificity of realization of harmonization in Orthodox and other religious texts are taken into account: the communication channel between the author and the reader, a defining speech genre, the command of language (communication code, and extra-linguistic factors. It is shown that sharing the general social, historical and national experience, as well as a lexical overlapping of actors on both sides of the communication channel are the deciding elements of the harmonization process. The analysis also shows that usage of rational argumentation is more likely to lead to harmonisation in comparison to other rhetoric tools (i. e. affective ones or story-telling. Rational and unemotional sermonic discourse is perceived as a sign of respect (namely, for the listener's intelligence. Another successful and much-applied way seems to be evoking a feeling of equality, unity and/or identity between clerics and their flocks.
Power quality issues current harmonics
Mikkili, Suresh
2015-01-01
Power Quality Issues: Current Harmonics provides solutions for the mitigation of power quality problems related to harmonics. Focusing on active power filters (APFs) due to their excellent harmonic and reactive power compensation in two-wire (single phase), three-wire (three-phase without neutral), and four-wire (three-phase with neutral) AC power networks with nonlinear loads, the text:Introduces the APF technology, describing various APF configurations and offering guidelines for the selection of APFs for specific application considerationsCompares shunt active filter (SHAF) control strategi
Introduction to abstract harmonic analysis
Loomis, Lynn H
2011-01-01
Written by a prominent figure in the field of harmonic analysis, this classic monograph is geared toward advanced undergraduates and graduate students and focuses on methods related to Gelfand's theory of Banach algebra. 1953 edition.
Tissue Harmonic Synthetic Aperture Imaging
DEFF Research Database (Denmark)
Rasmussen, Joachim
The main purpose of this PhD project is to develop an ultrasonic method for tissue harmonic synthetic aperture imaging. The motivation is to advance the field of synthetic aperture imaging in ultrasound, which has shown great potentials in the clinic. Suggestions for synthetic aperture tissue...... system complexity compared to conventional synthetic aperture techniques. In this project, SASB is sought combined with a pulse inversion technique for 2nd harmonic tissue harmonic imaging. The advantages in tissue harmonic imaging (THI) are expected to further improve the image quality of SASB....... The first part of the scientific contribution investigates an implementation of pulse inversion for THI on the experimental ultrasound system SARUS. The technique is initially implemented for linear array transducers and then expanded for convex array transducers. The technique is evaluated based on spatial...
Harmonic structures and intrinsic torsion
DEFF Research Database (Denmark)
Conti, Diego; Madsen, Thomas Bruun
We discuss the construction of 8-manifolds with harmonic Sp(2)Sp(1)-structures. In particular, we find 10 new examples of nilmanifolds that admit a closed 4-form Omega whose stabiliser is Sp(2)Sp(1). Our constructions entail the notion of SO(4)-structures on 7-manifolds. We present a thorough inv...... investigation of the intrinsic torsion of such structures; in addition to the construction of harmonic structures, this analysis leads to explicit Lie group examples with invariant intrinsic torsion....
Renken, R; Wiersinga-Post, JEC; Tomaskovic, S; Duifhuis, H
In a two-alternative, forced-choice experiment, subjects had to compare the pitches of two sounds, A and B. Each sound was composed of four successive harmonics of a fundamental frequency between 100 to 250 Hz, added in cosine or Schroder phase. The harmonic frequencies of A were lower than those of
General Lp-harmonic Blaschke bodies
Indian Academy of Sciences (India)
Lutwak introduced the harmonic Blaschke combination and the harmonic Blaschke body of a star body. Further, Feng and Wang introduced the concept of the -harmonic Blaschke body of a star body. In this paper, we define the notion of general -harmonic Blaschke bodies and establish some of its properties.
General Lp-harmonic Blaschke bodies
Indian Academy of Sciences (India)
Abstract. Lutwak introduced the harmonic Blaschke combination and the harmonic. Blaschke body of a star body. Further, Feng and Wang introduced the concept of the L p- harmonic Blaschke body of a star body. In this paper, we define the notion of general. L p-harmonic Blaschke bodies and establish some of its ...
Commutation effect of Adjustable Speed Drives due to installation of active harmonic filters
DEFF Research Database (Denmark)
Asiminoaei, Lucian; Kalaschnikow, Sergej; Hansen, Steffan
2011-01-01
The success of designing an industrial installation with Active Filters depends on how precise the load profile of the application is known, because this determines the amount of harmonic currents to be compensated. However, once the Active Filter is added to the installation, the harmonic currents...... may increase due to changes in the commutation behavior of diode rectifier converters. The change of natural commutation determines higher harmonics currents of the diode rectifiers and therefore higher harmonic loading of the Active Filter in the installation. This paper presents a method to estimate...
Prony Analysis for Power System Transient Harmonics
Directory of Open Access Journals (Sweden)
David Cartes
2007-01-01
Full Text Available Proliferation of nonlinear loads in power systems has increased harmonic pollution and deteriorated power quality. Not required to have prior knowledge of existing harmonics, Prony analysis detects frequencies, magnitudes, phases, and especially damping factors of exponential decaying or growing transient harmonics. In this paper, Prony analysis is implemented to supervise power system transient harmonics, or time-varying harmonics. Further, to improve power quality when transient harmonics appear, the dominant harmonics identified from Prony analysis are used as the harmonic reference for harmonic selective active filters. Simulation results of two test systems during transformer energizing and induction motor starting confirm the effectiveness of the Prony analysis in supervising and canceling power system transient harmonics.
Local field enhanced second-harmonic response of organic nanofibers
DEFF Research Database (Denmark)
Leißner, Till; Kostiučenko, Oksana; Fiutowski, Jacek
Organic CNHP4 nanofibers showing a strong second-harmonic (SH) response have been successfully implemented as active components in a metal-organic hybrid system. Using nondestructive roll-on transfer technique nanofibers were transferred from the growing mica substrates onto electron...
Validation of phantom-based harmonization for patient harmonization.
Panetta, Joseph V; Daube-Witherspoon, Margaret E; Karp, Joel S
2017-07-01
To improve the precision of multicenter clinical trials, several efforts are underway to determine scanner-specific parameters for harmonization using standardized phantom measurements. The goal of this study was to test the correspondence between quantification in phantom and patient images and validate the use of phantoms for harmonization of patient images. The National Electrical Manufacturers' Association image quality phantom with hot spheres was scanned on two time-of-flight PET scanners. Whole-body [18 F]-fluorodeoxyglucose (FDG)-PET scans were acquired of subjects on the same systems. List-mode events from spheres (diam.: 10-28 mm) measured in air on each scanner were embedded into the phantom and subject list-mode data from each scanner to create lesions with known uptake with respect to the local background in the phantom and each subject's liver and lung regions, as a proxy to characterize true lesion quantification. Images were analyzed using the contrast recovery coefficient (CRC) typically used in phantom studies and serving as a surrogate for the standardized uptake value used clinically. Postreconstruction filtering (resolution recovery and Gaussian smoothing) was applied to determine if the effect on the phantom images translates equivalently to subject images. Three postfiltering strategies were selected to harmonize the CRCmean or CRCmax values between the two scanners based on the phantom measurements and then applied to the subject images. Both the average CRCmean and CRCmax values for lesions embedded in the lung and liver in four subjects (BMI range 25-38) agreed to within 5% with the CRC values for lesions embedded in the phantom for all lesion sizes. In addition, the relative changes in CRCmean and CRCmax resulting from the application of the postfilters on the subject and phantom images were consistent within measurement uncertainty. Further, the root mean squared percent difference (RMSpd ) between CRC values on the two scanners
TAX HARMONIZATION VERSUS FISCAL COMPETITION
Directory of Open Access Journals (Sweden)
Florin Alexandru MACSIM
2016-12-01
Full Text Available Recent years have brought into discussion once again subjects like tax harmonization and fiscal competition. Every time the European Union tends to take a step forward critics enter the scene and give contrary arguments to European integration. Through this article we have offered our readers a compelling view over the “battle” between tax harmonization and fiscal competition. While tax harmonization has key advantages as less costs regarding public revenues, leads to higher degree of integration and allows the usage of fiscal transfers between regions, fiscal competition is no less and presents key advantages as high reductions in tax rates and opens a large path for new investments, especially FDI. Choosing tax harmonization or fiscal competition depends on a multitude of variables, of circumstances, the decision of choosing one path or the other being ultimately influenced by the view of central and local authorities. Our analysis indicates that if we refer to a group of countries that are a part of a monetary union or that form a federation, tax harmonization seems to be the best path to choose. Moving the analysis to a group of regions that aren’t taking any kind of correlated actions or that have not signed any major treaties regarding monetary or fiscal policies, the optimal solution is fiscal competition.
HARMONIZED EUROPE OR EUROPEAN HARMONY?
Directory of Open Access Journals (Sweden)
Cosmin Marinescu
2007-07-01
Full Text Available Recent evolutions in Europe raise questions on the viability of the present economic and social model that defines the European construction project. In this paper, the author will try to explain the viability of institutional European model that sticks between free market mechanisms and protectionism. The main challenge for the EU is about the possibility to bring together the institutional convergence and the welfare for all Europeans. This is the result of the view, still dominant, of European politics elite, according to which institutional harmonization is the solution of a more dynamic and prosper Europe. But, economic realities convince us that, more and more, a harmonized, standardized Europe is not necessarily identical with a Europe of harmony and social cooperation. If „development through integration” seems to be harmonization through „institutional transplant”, how could then be the European model one sufficiently wide open to market, which creates the prosperity so long waited for by new member countries?
Towards harmonized data interchange in food consumption data
DEFF Research Database (Denmark)
Pakkala, H.; Christensen, Tue; Presser, K.
2014-01-01
Food consumption data are collected and used in several fields of science. The data are often combined from various sources and interchanged between different systems. There is, however, no harmonized and widely used data interchange format. In addition, food consumption data are often combined...... with other data such as food composition data. In the field of food composition, successful harmonization has recently been achieved by the European Food Information Resource Network, which is now the basis of a standard draft by the European Committee for Standardization. We present an XML-based data...... interchange format for food consumption based on work and experiences related to food composition.The aim is that the data interchange format will provide a basis for wider harmonization in the future....
Elements of abstract harmonic analysis
Bachman, George
2013-01-01
Elements of Abstract Harmonic Analysis provides an introduction to the fundamental concepts and basic theorems of abstract harmonic analysis. In order to give a reasonably complete and self-contained introduction to the subject, most of the proofs have been presented in great detail thereby making the development understandable to a very wide audience. Exercises have been supplied at the end of each chapter. Some of these are meant to extend the theory slightly while others should serve to test the reader's understanding of the material presented. The first chapter and part of the second give
Harmonic functions with varying coefficients
Directory of Open Access Journals (Sweden)
Jacek Dziok
2016-05-01
Full Text Available Abstract Complex-valued harmonic functions that are univalent and sense preserving in the open unit disk can be written in the form f = h + g ‾ $f=h+\\overline{g}$ , where h and g are analytic. In this paper we investigate some classes of univalent harmonic functions with varying coefficients related to Janowski functions. By using the extreme points theory we obtain necessary and sufficient convolution conditions, coefficients estimates, distortion theorems, and integral mean inequalities for these classes of functions. The radii of starlikeness and convexity for these classes are also determined.
Optimal Selective Harmonic Control for Power Harmonics Mitigation
DEFF Research Database (Denmark)
Zhou, Keliang; Yang, Yongheng; Blaabjerg, Frede
2015-01-01
of power harmonics. The proposed optimal SHC is of hybrid structure: all recursive SHC modules with weighted gains are connected in parallel. It bridges the real “nk+-m order RC” and the complex “parallel structure RC”. Compared to other IMP based control solutions, it offers an optimal trade-off among...
Probabilistic Harmonic Modeling of Wind Power Plants
DEFF Research Database (Denmark)
Guest, Emerson; Jensen, Kim H.; Rasmussen, Tonny Wederberg
2017-01-01
A probabilistic sequence domain (SD) harmonic model of a grid-connected voltage-source converter is used to estimate harmonic emissions in a wind power plant (WPP) comprised of Type-IV wind turbines. The SD representation naturally partitioned converter generated voltage harmonics into those...... with deterministic phase and those with probabilistic phase. A case study performed on a string of ten 3MW, Type-IV wind turbines implemented in PSCAD was used to verify the probabilistic SD harmonic model. The probabilistic SD harmonic model can be employed in the planning phase of WPP projects to assess harmonic...
Viability of spectral enhancement with harmonic stimuli
Digiovanni, Jeffrey J.
2003-04-01
Loss of spectral resolution is an established consequence of sensorineural hearing loss. Traditional hearing aid design includes amplification and compression. These do not, however, account for the loss in frequency resolution. Recently, spectral enhancement processing has been designed to at least partially restore aspects of frequency resolution. The critical feature of this design is to increase the peak to trough ratio of the speech spectrum. These have been implemented with mixed success [e.g., Miller et al. (1999); Franck et al. (1999)]. More recently, DiGiovanni et al. (2002) showed promising results for normal and hearing-impaired subjects with psychophysical noise stimuli. The goal of this study was to expand these results to harmonic stimuli while adding peaks at fixed formant places within the spectrum. In that regard, subjects listened in two psychophysical experiments: detecting an F2-like spectral increment in a broadband harmonic complex and detecting the increment with an additional fixed formant peak added at an appropriate F1 place. Preliminary results show that normally hearing subjects have an improved ability to detect a narrowband tone complex when there is a spectral decrement at frequencies adjacent to the increment. These results are further support that the idea of spectral enhancement is viable.
Sums of Generalized Harmonic Series
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 9. Sums of Generalized Harmonic Series: For Kids from Five to Fifteen. Zurab Silagadze. General Article Volume 20 Issue 9 September 2015 pp 822-843 ... Keywords. Riemann zeta function; integral representation; Basel problem.
Chuluunbaatar, O.; Gusev, A. A.; Abrashkevich, A. G.; Amaya-Tapia, A.; Kaschiev, M. S.; Larsen, S. Y.; Vinitsky, S. I.
2007-10-01
A FORTRAN 77 program is presented which calculates energy values, reaction matrix and corresponding radial wave functions in a coupled-channel approximation of the hyperspherical adiabatic approach. In this approach, a multi-dimensional Schrödinger equation is reduced to a system of the coupled second-order ordinary differential equations on the finite interval with homogeneous boundary conditions of the third type. The resulting system of radial equations which contains the potential matrix elements and first-derivative coupling terms is solved using high-order accuracy approximations of the finite-element method. As a test desk, the program is applied to the calculation of the energy values and reaction matrix for an exactly solvable 2D-model of three identical particles on a line with pair zero-range potentials. Program summaryProgram title: KANTBP Catalogue identifier: ADZH_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZH_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 4224 No. of bytes in distributed program, including test data, etc.: 31 232 Distribution format: tar.gz Programming language: FORTRAN 77 Computer: Intel Xeon EM64T, Alpha 21264A, AMD Athlon MP, Pentium IV Xeon, Opteron 248, Intel Pentium IV Operating system: OC Linux, Unix AIX 5.3, SunOS 5.8, Solaris, Windows XP RAM: depends on (a) the number of differential equations; (b) the number and order of finite-elements; (c) the number of hyperradial points; and (d) the number of eigensolutions required. Test run requires 30 MB Classification: 2.1, 2.4 External routines: GAULEG and GAUSSJ [W.H. Press, B.F. Flanery, S.A. Teukolsky, W.T. Vetterley, Numerical Recipes: The Art of Scientific Computing, Cambridge University Press, Cambridge, 1986] Nature of problem: In the hyperspherical adiabatic
Tides and tidal harmonics at Umbharat, Gujarat
Digital Repository Service at National Institute of Oceanography (India)
Suryanarayana, A.; Swamy, G.N.
A part of the data on tides recorded at Machiwada near Umbharat, Gulf of Cambay during April 1978 was subjected to harmonic analysis following the Admiralty procedure. The general tidal characteristics and the value of four major harmonic...
Detection of Harmonic Occurring using Kalman Filtering
DEFF Research Database (Denmark)
Hussain, Dil Muhammad Akbar; Shoro, Ghulam Mustafa; Imran, Raja Muhammed
2014-01-01
As long as the load to a power system is linear which has been the case before 80's, typically no harmonics are produced. However, the modern power electronic equipment for controlled power consumption produces harmonic disturbances, these devices/equipment possess nonlinear voltage/current chara...... using Kalman filter. This may be very useful for example to quickly switching on certain filters based on the harmonic present. We are using a unique technique to detect the occurrence of harmonics....
Multimode Directional Coupler for Utilization of Harmonic Frequencies from TWTAs
Simmons, Rainee N.; Wintucky, Edwin G.
2013-01-01
A novel waveguide multimode directional coupler (MDC) intended for the measurement and potential utilization of the second and higher order harmonic frequencies from high-power traveling wave tube amplifiers (TWTAs) has been successfully designed, fabricated, and tested. The design is based on the characteristic multiple propagation modes of the electrical and magnetic field components of electromagnetic waves in a rectangular waveguide. The purpose was to create a rugged, easily constructed, more efficient waveguide- based MDC for extraction and exploitation of the second harmonic signal from the RF output of high-power TWTs used for space communications. The application would be a satellitebased beacon source needed for Qband and V/W-band atmospheric propagation studies. The MDC could function as a CW narrow-band source or as a wideband source for study of atmospheric group delay effects on highdata- rate links. The MDC is fabricated from two sections of waveguide - a primary one for the fundamental frequency and a secondary waveguide for the second harmonic - that are joined together such that the second harmonic higher order modes are selectively coupled via precision- machined slots for propagation in the secondary waveguide. In the TWTA output waveguide port, both the fundamental and the second harmonic signals are present. These signals propagate in the output waveguide as the dominant and higher order modes, respectively. By including an appropriate mode selective waveguide directional coupler, such as the MDC presented here at the output of the TWTA, the power at the second harmonic can be sampled and amplified to the power level needed for atmospheric propagation studies. The important conclusions from the preliminary test results for the multimode directional coupler are: (1) the second harmonic (Ka-band) can be measured and effectively separated from the fundamental (Ku-band) with no coupling of the latter, (2) power losses in the fundamental frequency
Effective harmonic oscillator description of anharmonic molecular ...
Indian Academy of Sciences (India)
Administrator
Abstract. The validity of an effective harmonic oscillator approximation for anharmonic molecular vibrations is tested and compared with vibrational self consistent field and vibrational configurational interaction results. The effective harmonic oscillator is constructed variationally, by taking the trial wave function as a harmonic ...
Third Harmonic Imaging using a Pulse Inversion
DEFF Research Database (Denmark)
Rasmussen, Joachim; Du, Yigang; Jensen, Jørgen Arendt
2011-01-01
The pulse inversion (PI) technique can be utilized to separate and enhance harmonic components of a waveform for tissue harmonic imaging. While most ultrasound systems can perform pulse inversion, only few image the 3rd harmonic component. PI pulse subtraction can isolate and enhance the 3rd...
Harmonic Detection at Initialization With Kalman Filter
DEFF Research Database (Denmark)
Hussain, Dil Muhammad Akbar; Imran, Raja Muhammad; Shoro, Ghulam Mustafa
2014-01-01
the affect of harmonics on the supply. For the detection of these harmonics various techniques are available and one of that technique is the Kalman filter. In this paper we investigate that what are the consequences when harmonic detection system based on Kalman Filtering is initialized...
2×1 Microstrip Patch Array Antenna with Harmonic Suppression Capability for Rectenna
Directory of Open Access Journals (Sweden)
Nur Aisyah Amir
2017-12-01
Full Text Available This paper is an extension of work originally presented in 2016 IEEE Asia-Pacific Conference on Applied Electromagnetics (APACE. A 2×1 microstrip patch array antenna integrated with photonic bandgap (PBG and stubs is designed and analyzed. The performance of the PBG and stubs structure are explained and analyzed in terms of the elimination of the resonance at the harmonic frequencies of the antenna. The proposed antenna is designed on FR-4 substrate with thickness of 1.6 mm and operated at 2.45 GHz frequency suitable for rectenna design application. From the simulated result, the first harmonic frequency (5.4 GHz, the second harmonic frequency (6.6 GHz and the third harmonic frequency (7.8 GHz are successfully suppressed. For instance, the radiation to the forward of the stubs-PBG antenna is suppressed at more than 15 dB at the second and third harmonic frequencies.
Static harmonization of dynamically harmonized Fourier transform ion cyclotron resonance cell.
Zhdanova, Ekaterina; Kostyukevich, Yury; Nikolaev, Eugene
2017-08-01
Static harmonization in the Fourier transform ion cyclotron resonance cell improves the resolving power of the cell and prevents dephasing of the ion cloud in the case of any trajectory of the charged particle, not necessarily axisymmetric cyclotron (as opposed to dynamic harmonization). We reveal that the Fourier transform ion cyclotron resonance cell with dynamic harmonization (paracell) is proved to be statically harmonized. The volume of the statically harmonized potential distribution increases with an increase in the number of trap segments.
Data harmonization and model performance
The Joint Committee on Urban Storm Drainage of the International Association for Hydraulic Research (IAHR) and International Association on Water Pollution Research and Control (IAWPRC) was formed in 1982. The current committee members are (no more than two from a country): B. C. Yen, Chairman (USA); P. Harremoes, Vice Chairman (Denmark); R. K. Price, Secretary (UK); P. J. Colyer (UK), M. Desbordes (France), W. C. Huber (USA), K. Krauth (FRG), A. Sjoberg (Sweden), and T. Sueishi (Japan).The IAHR/IAWPRC Joint Committee is forming a Task Group on Data Harmonization and Model Performance. One objective is to promote international urban drainage data harmonization for easy data and information exchange. Another objective is to publicize available models and data internationally. Comments and suggestions concerning the formation and charge of the Task Group are welcome and should be sent to: B. C. Yen, Dept. of Civil Engineering, Univ. of Illinois, 208 N. Romine St., Urbana, IL 61801.
Harmonic vibrations of multispan beams
DEFF Research Database (Denmark)
Dyrbye, Claes
1996-01-01
Free and forced harmonic vibrations of multispan beams are determined by a method which implies 1 equation regardless of the configuration. The necessary formulas are given in the paper. For beams with simple supports and the same length of all (n) spans, there is a rather big difference between...... the n´th and the (n+1)´th eigenfrequency. The reason for this phenomenon is explained.Keywords: Vibrations, Eigenfrequencies, Beams....
Representation Discovery using Harmonic Analysis
Mahadevan, Sridhar
2008-01-01
Representations are at the heart of artificial intelligence (AI). This book is devoted to the problem of representation discovery: how can an intelligent system construct representations from its experience? Representation discovery re-parameterizes the state space - prior to the application of information retrieval, machine learning, or optimization techniques - facilitating later inference processes by constructing new task-specific bases adapted to the state space geometry. This book presents a general approach to representation discovery using the framework of harmonic analysis, in particu
Harmonic ratcheting for fast acceleration
Directory of Open Access Journals (Sweden)
N. Cook
2014-04-01
Full Text Available A major challenge in the design of rf cavities for the acceleration of medium-energy charged ions is the need to rapidly sweep the radio frequency over a large range. From low-power medical synchrotrons to high-power accelerator driven subcritical reactor systems, and from fixed focus alternating gradient accelerators to rapid cycling synchrotrons, there is a strong need for more efficient, and faster, acceleration of protons and light ions in the semirelativistic range of hundreds of MeV/u. A conventional way to achieve a large, rapid frequency sweep (perhaps over a range of a factor of 6 is to use custom-designed ferrite-loaded cavities. Ferrite rings enable the precise tuning of the resonant frequency of a cavity, through the control of the incremental permeability that is possible by introducing a pseudoconstant azimuthal magnetic field. However, rapid changes over large permeability ranges incur anomalous behavior such as the “Q-loss” and “f-dot” loss phenomena that limit performance while requiring high bias currents. Notwithstanding the incomplete understanding of these phenomena, they can be ameliorated by introducing a “harmonic ratcheting” acceleration scheme in which two or more rf cavities take turns accelerating the beam—one turns on when the other turns off, at different harmonics—so that the radio frequency can be constrained to remain in a smaller range. Harmonic ratcheting also has straightforward performance advantages, depending on the particular parameter set at hand. In some typical cases it is possible to halve the length of the cavities, or to double the effective gap voltage, or to double the repetition rate. This paper discusses and quantifies the advantages of harmonic ratcheting in general. Simulation results for the particular case of a rapid cycling medical synchrotron ratcheting from harmonic number 9 to 2 show that stability and performance criteria are met even when realistic engineering details
Renormalization for free harmonic oscillators
Sonoda, H.
2013-01-01
We introduce a model of free harmonic oscillators that requires renormalization. The model is similar to but simpler than the soluble Lee model. We introduce two concrete examples: the first, resembling the three dimensional $\\phi^4$ theory, needs only mass renormalization, and the second, resembling the four dimensional $\\phi^4$ theory and the Lee model, needs additional renormalization of a coupling and a wave function.
Input Harmonic Analysis on the Slim DC-Link Drive Using Harmonic State Space Model
DEFF Research Database (Denmark)
Yang, Feng; Kwon, Jun Bum; Wang, Xiongfei
2017-01-01
variation according to the switching instant, the harmonics at the steady-state condition, as well as the coupling between the multiple harmonic impedances. By using this model, the impaction on the harmonics performance by the film capacitor and the grid inductance is derived. Simulation and experimental......The harmonic performance of the slim dc-link adjustable speed drives has shown good performance in some studies but poor in some others. The contradiction indicates that a feasible theoretical analysis is still lacking to characterize the harmonic distortion for the slim dc-link drive. Considering...... the shortcomings of the present harmonic analysis methods, such as the time-domain simulation, or the Fourier analysis, this paper proposes a Harmonic State Space model to study the harmonics performance for this type of drive. In this study, this model is utilized to describe the behavior of the harmonic...
The quantum harmonic oscillator on a circle and a deformed quantum field theory
Energy Technology Data Exchange (ETDEWEB)
Rego-Monteiro, M.A. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). E-mail: regomont@cbpf.br
2001-05-01
We construct a deformed free quantum field theory with an standard Hilbert space based on a deformed Heisenberg algebra. This deformed algebra is a Heisenberg-type algebra describing the first levels of the quantum harmonic oscillator on a circle of large length L. The successive energy levels of this quantum harmonic oscillator on a circle of large length L are interpreted, similarly to the standard quantum one-dimensional harmonic oscillator on an infinite line, as being obtained by the creation of a quantum particle of frequency w at very high energies. (author)
Harmonic generation in the generalized Sagdeev pseudopotential
Akbari-Moghanjoughi, M.
2017-09-01
In this paper, we study the nonlinear harmonic generation effect in different oscillator models. For weakly nonlinear systems, we use the generalized forced Korteweg de Vries Burgers (KdVB) and modified KdVB (mKdVB) models in order to classify three fundamentally different harmonic structures in a nonlinear dynamical system. The first is called the internal harmonic structure which exists due to the self oscillation of the system in the absence of dissipation effect and is shown to follow either relations of nf or (2n - 1)f depending on the symmetry of oscillator potential in which n is an integer number and f is the fundamental frequency which is exactly obtained for the Helmholtz oscillator. The second structure is the resonant harmonics which appears in the presence of damping and follows the harmonic structure nf0 in which f0 is the linear resonance frequency. Finally, the last harmonic structure appears in the presence of dissipation and external periodic forcing effects which we call the external harmonic pattern. It is shown that the external harmonic pattern, in which f1 is the driving frequency, always follows the nf1 rule regardless of the potential symmetry. We then extend our analysis to study the harmonic generation in the fully nonlinear generalized Sagdeev potential for real plasmas with isothermal and adiabatic ion fluids and investigate the effects of different plasma parameters such as the fractional ion temperature and normalized ion acoustic speed on all three kinds of harmonic generation.
Murphy, P J
1999-05-01
The measurement of the harmonics-to-noise ratio (HNR) in speech signals gives an indication of the aperiodicity of the speech waveform. This may be due to the presence of jitter, shimmer, additive noise, waveshape change, or some unknown combination of these factors. In order to estimate the HNR as a measure of the additive noise component only, the contaminating effects of the other contributory components must first be removed. A pitch synchronous harmonic analysis is proposed to overcome this problem. The procedure takes advantage of the time scale compression-frequency expansion property of the Fourier series in order to eliminate jitter and shimmer. Successive spectra are added by harmonic number as opposed to frequency location, and perturbation is removed due to the fact that the relative heights of the harmonic components remain the same for scaled signals. The technique is examined on synthetically generated voice signals. A discussion of the results is given in terms of human voice signals, characterization of jitter, vocal tract filtering effects, perturbation mechanisms, nonlinear dynamics, and the possibility of developing the method for use with inverse filtering strategies.
Making space for harmonic oscillators
Energy Technology Data Exchange (ETDEWEB)
Michelotti, Leo; /Fermilab
2004-11-01
If we restrict the number of harmonic oscillator energy eigenstates to some finite value, N, then the discrete spectrum of the corresponding position operator comprise the roots of the Hermite polynomial H{sub N+1}. Its range is just large enough to accommodate classical motion at high energy. A negative energy term must be added to the Hamiltonian which affects only the last eigenstate, |N>, suggesting it is concentrated at the extrema of this finite ''space''. Calculations support a conjecture that, in the limit of large N, the global distribution of points approaches the differential form for classical action.
Harmonic focus in thyroidectomy for substernal goiter
DEFF Research Database (Denmark)
Hahn, Christoffer Holst; Trolle, Waldemar; Sørensen, Christian Hjort
2015-01-01
OBJECTIVES: No previous prospective study has evaluated harmonic scalpel in thyroidectomy for substernal goiter. The objective of this study was to evaluate the use of harmonic scalpel (FOCUS shear, Ethicon Endo-Surgery) in thyroidectomy for substernal goiter for blood loss, operative time...... and 121 patients had harmonic scalpel thyroidectomy. RESULTS: The use of harmonic scalpel was associated with significant reduction in intraoperative blood loss (50 vs. 100mL, p=0.001), postoperative haemorrhage (4% vs. 12%, p=0.03) and length of hospital stay (2 vs. 3 days, p=0.001). The mean operative...... time was significantly longer in the harmonic group. CONCLUSION: Harmonic scalpel is a safe tool for thyroidectomy for substernal goiter. Its utilisation is associated with reduced blood loss, lower incidence of postoperative haemorrhage and shorter hospital stay....
Efficient third harmonic generation in photonic nanowires
Broderick, N.G.R.; Lohe, M. A.; Lee, T; Shaaram, Afshar V.; Monro, T.M.
2013-01-01
In a photonic nanowire the strong optical confinement allows for the phase matching of nonlinear interactions that would not normally be phase matched, while the large longitudinal component of the electric field serves to further enhance the effective nonlinearity. Thus such waveguides are good choices for studying nonlinear effects such as third harmonic generation. In this paper we analyse third harmonic generation analytically and present the criteria for optimal harmonic generation. In a...
Harmonics Monitoring Survey on LED Lamps
Abdelrahman Ahmed Akila; Kamelia Youssef; Ibrahim Yassin
2017-01-01
Light Emitting Diode (LED) lamps are being increasingly used in many applications. These LED lamps operate using a driver, which is a switching device. Hence, LED lamps will be a source of harmonics in the power system. These harmonics if not well treated, may cause severe performance and operational problems. In this paper, harmonics (amplitude and phase angles) generated by both LED lamps and conventional fluorescent lamps will be studied practically. Then they will be analyzed and evaluate...
Introduction to classical and quantum harmonic oscillators
Bloch, Sylvan C
2013-01-01
From conch shells to lasers . harmonic oscillators, the timeless scientific phenomenon As intriguing to Galileo as they are to scientists today, harmonic oscillators have provided a simple and compelling paradigm for understanding the complexities that underlie some of nature's and mankind's most fascinating creations. From early string and wind instruments fashioned from bows and seashells to the intense precision of lasers, harmonic oscillators have existed in various forms, as objects of beauty and scientific use. And harmonic oscillation has endured as one of science's most fascinating con
Effects of harmonic roving on pitch discrimination
DEFF Research Database (Denmark)
Santurette, Sébastien; de Kérangal, Mathilde le Gal; Joshi, Suyash Narendra
2015-01-01
to impair pitch discrimination performance. Fundamental-frequency difference limens (F0DLs) were obtained in normal-hearing listeners with and without musical training for complex tones filtered between 1.5 and 3.5 kHz with F0s of 300 Hz (resolved harmonics) and 75 Hz (unresolved harmonics). The harmonicity...... of the tone complexes was varied by systematically roving the frequency of individual harmonics, which was taken from a Gaussian distribution centered on the nominal frequency in every stimulus presentation. The amount of roving was determined by the standard deviation of this distribution, which varied...
Effect of undulator harmonics field on free-electron laser harmonic generation
Directory of Open Access Journals (Sweden)
Qika Jia
2011-06-01
Full Text Available The harmonics field effect of a planar undulator on free-electron laser (FEL harmonic generation has been analyzed. For both the linear case and the nonlinear case, the harmonic fraction of the radiation can be characterized by the coupling coefficients. The modification of the coupling coefficients is given when the third harmonics magnetic field component exists, thus the enhancement of the harmonic radiation can be predicted. The numerical results show that with the third harmonics magnetic field component that has the opposite sign to the fundamental, the intensity of third-harmonic radiation can be increased distinctly for both the small signal gain and the nonlinear harmonic generation. The increase is larger for the smaller undulator deflecting parameter.
Nonlinear wave chaos: statistics of second harmonic fields
Zhou, Min; Ott, Edward; Antonsen, Thomas M.; Anlage, Steven M.
2017-10-01
Concepts from the field of wave chaos have been shown to successfully predict the statistical properties of linear electromagnetic fields in electrically large enclosures. The Random Coupling Model (RCM) describes these properties by incorporating both universal features described by Random Matrix Theory and the system-specific features of particular system realizations. In an effort to extend this approach to the nonlinear domain, we add an active nonlinear frequency-doubling circuit to an otherwise linear wave chaotic system, and we measure the statistical properties of the resulting second harmonic fields. We develop an RCM-based model of this system as two linear chaotic cavities coupled by means of a nonlinear transfer function. The harmonic field strengths are predicted to be the product of two statistical quantities and the nonlinearity characteristics. Statistical results from measurement-based calculation, RCM-based simulation, and direct experimental measurements are compared and show good agreement over many decades of power.
INTERNATIONAL STANDARDS FOR FINANCIAL REPORTING: HARMONIZATION IN MACEDONIA
Directory of Open Access Journals (Sweden)
Sasho Kozuharov
2015-12-01
Full Text Available A continuous flow of reliable, relevant and financially important information is necessary for making economically justified and strategic investment decisions. Economic globalization has contributed to the need of creating a unified language for communication, a single set of international financial reporting standards with the sole purpose of enhancing transparency for investors and reducing the cost of capital. Harmonization of financial reporting provides more efficient use of global resources, easier consolidation of multinational companies foreign subsidiaries, alleviation of accounting staff mobility and reducing of audit costs. The research is based on the benefits that the national economy can gain if the international financial reporting standards are successfully implemented. Special attention in the paper is devoted to the factors that determine the harmonization of financial reporting. The analysis of the results show the managers' perception of financial reporting, and emphasize the effects of the implementation of IFRS in Republic of Macedonia.
The Harmonic Organization of Auditory Cortex
Directory of Open Access Journals (Sweden)
Xiaoqin eWang
2013-12-01
Full Text Available A fundamental structure of sounds encountered in the natural environment is the harmonicity. Harmonicity is an essential component of music found in all cultures. It is also a unique feature of vocal communication sounds such as human speech and animal vocalizations. Harmonics in sounds are produced by a variety of acoustic generators and reflectors in the natural environment, including vocal apparatuses of humans and animal species as well as music instruments of many types. We live in an acoustic world full of harmonicity. Given the widespread existence of the harmonicity in many aspects of the hearing environment, it is natural to expect that it be reflected in the evolution and development of the auditory systems of both humans and animals, in particular the auditory cortex. Recent neuroimaging and neurophysiology experiments have identified regions of non-primary auditory cortex in humans and non-human primates that have selective responses to harmonic pitches. Accumulating evidence has also shown that neurons in many regions of the auditory cortex exhibit characteristic responses to harmonically related frequencies beyond the range of pitch. Together, these findings suggest that a fundamental organizational principle of auditory cortex is based on the harmonicity. Such an organization likely plays an important role in music processing by the brain. It may also form the basis of the preference for particular classes of music and voice sounds.
Practical Tools to Foster Harmonic Understanding
Johnson, Erik
2013-01-01
Among the elements required to develop a comprehensive understanding of music is students' ability to perceive, recognize, and label the harmonies they hear. Harmonic dictation is among the strategies that teachers have traditionally chosen to help students develop harmonic awareness. However, the highly idiosyncratic ways that students approach…
Harmonic manifolds with minimal horospheres are flat
Indian Academy of Sciences (India)
MS received 28 May 2013; revised 12 November 2013 ... The known examples of harmonic manifolds include flat ... periodic functions. Finally, using the characteristic property of an almost periodic function we prove that M is Ricci flat. In view of this, it is natural to ask: Can one affirm that harmonic manifolds with mini-.
Harmonic dynamical behaviour of thallous halides
Indian Academy of Sciences (India)
Harmonic dynamical behaviour of thallous halides (TlCl and TlBr) have been studied using the ... that the incorporation of van der Waals interactions is essential for the complete harmonic dynamical behaviour of .... long-range coupling coefficients to the long-wavelength limit q → 0, the expression for zone centre optical ...
Effective harmonic oscillator description of anharmonic molecular ...
Indian Academy of Sciences (India)
... a harmonic oscillator eigenfunction with the centroid and width parameter as variational paraeters. It is found that the effective harmonic oscillator approximation provides a description of the anharmonic eigenstates very similar to the vibrational self consistent field results. Coriolis coupling is also included in these studies.
Sunspots and Their Simple Harmonic Motion
Ribeiro, C. I.
2013-01-01
In this paper an example of a simple harmonic motion, the apparent motion of sunspots due to the Sun's rotation, is described, which can be used to teach this subject to high-school students. Using real images of the Sun, students can calculate the star's rotation period with the simple harmonic motion mathematical expression.
determination of determination of total harmonic distortion
African Journals Online (AJOL)
eobe
Harmonic Distortion (THD) of the Distribution lines in the 33kV distri. Harmonic Distortion (THD) of the Distribution lines in the 33kV distribution network of Island Business District, bution network of Island Business District,. Eko Electricity Distribution Plc, taken. Eko Electricity Distribution Plc, taken as a case study using a set ...
Achieving sustainable development through tax harmonization ...
African Journals Online (AJOL)
Using Nigeria as a case study, this article examines the efficacy of tax harmonization as an option for the achievement of two objectives: the integration of a developing country with other economies, and its sustainable development. It highlights the nexus between tax harmonization – a tax policy option – and sustainable ...
Harmonic Phase Response of Nonlinear Radar Targets
2015-10-01
ARL-TR-7513 ● OCT 2015 US Army Research Laboratory Harmonic Phase Response of Nonlinear Radar Targets by Sean F McGowan, Dr...Laboratory Harmonic Phase Response of Nonlinear Radar Targets by Sean F McGowan and Kelly D Sherbondy Sensors and Electron Devices Directorate...
The harmonic organization of auditory cortex
Wang, Xiaoqin
2013-01-01
A fundamental structure of sounds encountered in the natural environment is the harmonicity. Harmonicity is an essential component of music found in all cultures. It is also a unique feature of vocal communication sounds such as human speech and animal vocalizations. Harmonics in sounds are produced by a variety of acoustic generators and reflectors in the natural environment, including vocal apparatuses of humans and animal species as well as music instruments of many types. We live in an acoustic world full of harmonicity. Given the widespread existence of the harmonicity in many aspects of the hearing environment, it is natural to expect that it be reflected in the evolution and development of the auditory systems of both humans and animals, in particular the auditory cortex. Recent neuroimaging and neurophysiology experiments have identified regions of non-primary auditory cortex in humans and non-human primates that have selective responses to harmonic pitches. Accumulating evidence has also shown that neurons in many regions of the auditory cortex exhibit characteristic responses to harmonically related frequencies beyond the range of pitch. Together, these findings suggest that a fundamental organizational principle of auditory cortex is based on the harmonicity. Such an organization likely plays an important role in music processing by the brain. It may also form the basis of the preference for particular classes of music and voice sounds. PMID:24381544
Uniformly locally univalent harmonic map- pings
Indian Academy of Sciences (India)
63
Uniformly locally univalent harmonic map- pings. Saminathan Ponnusamy, Jinjing Qiao. ∗ and Xiantao Wang. Abstract. The primary aim of this paper is to characterize the uniformly locally univalent harmonic mappings in the unit disk. Then, we obtain sharp distortion, growth and covering theorems for one parameter fam-.
Energy Technology Data Exchange (ETDEWEB)
Lin Li [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Lin Weiqi [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Jiang Jianhui [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Zhou Yanping [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Shen Guoli [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Yu Ruqin [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)]. E-mail: rqyu@hnu.cn
2005-11-03
In the present work, we employed piecewise hyper-sphere modeling by particle swarm optimization (PHMPSO) which splits the dataset into subsets with desired linearity in each model for QSAR studies of a series of 2-aryl(heteroaryl)-2,5-dihydropyrazolo[4,3-c]quinolin-3-(3H)-ones (PQs) for their affinity to benzodiazepine receptor (BzR). The results were compared to those obtained by MLR modeling in a single model with the whole data set as well as in submodels based on K-means clustering analysis. It has been clearly shown that electronic descriptors and spatial descriptors play the important roles in the compounds' affinity to BzR. In addition, the molecular density, the Y component of the principal moment of inertia, the magnitude and the Y component of the dipole moment of the molecules can detrimentally affect PQ analogue BzR affinity, while the X component of the dipole moment of the molecules can favorably affect compounds' affinity.
Pairwise harmonics for shape analysis
Zheng, Youyi
2013-07-01
This paper introduces a simple yet effective shape analysis mechanism for geometry processing. Unlike traditional shape analysis techniques which compute descriptors per surface point up to certain neighborhoods, we introduce a shape analysis framework in which the descriptors are based on pairs of surface points. Such a pairwise analysis approach leads to a new class of shape descriptors that are more global, discriminative, and can effectively capture the variations in the underlying geometry. Specifically, we introduce new shape descriptors based on the isocurves of harmonic functions whose global maximum and minimum occur at the point pair. We show that these shape descriptors can infer shape structures and consistently lead to simpler and more efficient algorithms than the state-of-the-art methods for three applications: intrinsic reflectional symmetry axis computation, matching shape extremities, and simultaneous surface segmentation and skeletonization. © 2012 IEEE.
Harmonic Interaction Analysis in Grid Connected Converter using Harmonic State Space (HSS) Modeling
DEFF Research Database (Denmark)
Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth
2015-01-01
An increasing number of power electronics based Distributed Generation (DG) systems and loads generate coupled harmonic as well as non-characteristic harmonic with each other. Several methods like impedance based analysis, which is derived from conventional small signal- and average...... during the modeling process. This paper investigates grid connected converter by means of Harmonic State Space (HSS) small signal model, which is modeled from Linear Time varying Periodically (LTP) system. Further, a grid connected converter harmonic matrix is investigated to analyze the harmonic...
Harmonics Monitoring Survey on LED Lamps
Directory of Open Access Journals (Sweden)
Abdelrahman Ahmed Akila
2017-03-01
Full Text Available Light Emitting Diode (LED lamps are being increasingly used in many applications. These LED lamps operate using a driver, which is a switching device. Hence, LED lamps will be a source of harmonics in the power system. These harmonics if not well treated, may cause severe performance and operational problems. In this paper, harmonics (amplitude and phase angles generated by both LED lamps and conventional fluorescent lamps will be studied practically. Then they will be analyzed and evaluated. Compared to each other harmonics generated by both LED and conventional florescent lamps, self mitigation may occur based on the phase angle of these harmonics. All data will be measured using power analyzer and will be done on a sample of actual lamps.
High orbital angular momentum harmonic generation
Vieira, J; Alves, E P; Fonseca, R A; Mendonça, J T; Bingham, R; Norreys, P; Silva, L O
2016-01-01
We identify and explore a high orbital angular momentum (OAM) harmonics generation and amplification mechanism that manipulates the OAM independently of any other laser property, by preserving the initial laser wavelength, through stimulated Raman backscattering in a plasma. The high OAM harmonics spectra can extend at least up to the limiting value imposed by the paraxial approximation. We show with theory and particle-in-cell simulations that the orders of the OAM harmonics can be tuned according to a selection rule that depends on the initial OAM of the interacting waves. We illustrate the high OAM harmonics generation in a plasma using several examples including the generation of prime OAM harmonics. The process can also be realised in any nonlinear optical Kerr media supporting three-wave interactions.
Harmonic Generation by Microwave-frequency Microplasma
Parsons, Stephen; Hoskinson, Alan; Hopwood, Jeffrey
2013-09-01
A microplasma may operate as a nonlinear circuit element and generate power at the harmonics of the drive frequency. As an example, microplasma is sustained using 1 W of power at 1.3 GHz in a small discharge gap formed in a split-ring resonator. A probe extends into the microplasma and extracts the 3rd harmonic power through a tuned resonator at 3.9 GHz. The experimental data show that this non-optimized system produces a +38 dB increase in 3rd harmonic power in the presence of a microplasma. Two origins of nonlinearity are described: the harmonic conduction current due to electron collection by microelectrodes, and the harmonic displacement current due to the voltage-dependent sheath capacitance. PIC-MC simulations suggest that the microplasma nonlinearity may also be exploited at frequencies of 100 GHz. Support was provided by the DARPA Microscale Plasma Devices program under award FA9550-12-1-0006.
Metzger, Bernd; Gui, Lili; Fuchs, Jaco; Floess, Dominik; Hentschel, Mario; Giessen, Harald
2015-06-10
We perform second harmonic spectroscopy of aluminum nanoantenna arrays that exhibit plasmonic resonances at the second harmonic wavelength between 450 and 570 nm by focusing sub-30 fs laser pulses tunable from 900 to 1140 nm onto the nanoantenna arrays. We find that a plasmonic resonance at the second harmonic wavelength boosts the overall nonlinear process by more than an order of magnitude. In particular, in the measurement the resonant second harmonic polarization component is a factor of about 70 stronger when compared to the perpendicular off-resonant second harmonic polarization. Furthermore, the maximum of the second harmonic conversion efficiency is found to be slightly blue-shifted with respect to the peak of the linear optical far-field spectrum. This fact can be understood from a simple model that accounts for the almost off-resonant absorption at the fundamental wavelength and the resonant emission process at the second harmonic.
High order harmonic generation in rare gases
Energy Technology Data Exchange (ETDEWEB)
Budil, Kimberly Susan [Univ. of California, Davis, CA (United States)
1994-05-01
The process of high order harmonic generation in atomic gases has shown great promise as a method of generating extremely short wavelength radiation, extending far into the extreme ultraviolet (XUV). The process is conceptually simple. A very intense laser pulse (I ~10^{13}-10^{14} W/cm^{2}) is focused into a dense (~10^{17} particles/cm^{3}) atomic medium, causing the atoms to become polarized. These atomic dipoles are then coherently driven by the laser field and begin to radiate at odd harmonics of the laser field. This dissertation is a study of both the physical mechanism of harmonic generation as well as its development as a source of coherent XUV radiation. Recently, a semiclassical theory has been proposed which provides a simple, intuitive description of harmonic generation. In this picture the process is treated in two steps. The atom ionizes via tunneling after which its classical motion in the laser field is studied. Electron trajectories which return to the vicinity of the nucleus may recombine and emit a harmonic photon, while those which do not return will ionize. An experiment was performed to test the validity of this model wherein the trajectory of the electron as it orbits the nucleus or ion core is perturbed by driving the process with elliptically, rather than linearly, polarized laser radiation. The semiclassical theory predicts a rapid turn-off of harmonic production as the ellipticity of the driving field is increased. This decrease in harmonic production is observed experimentally and a simple quantum mechanical theory is used to model the data. The second major focus of this work was on development of the harmonic "source". A series of experiments were performed examining the spatial profiles of the harmonics. The quality of the spatial profile is crucial if the harmonics are to be used as the source for experiments, particularly if they must be refocused.
Tailored semiconductors for high-harmonic optoelectronics.
Sivis, Murat; Taucer, Marco; Vampa, Giulio; Johnston, Kyle; Staudte, André; Naumov, Andrei Yu; Villeneuve, D M; Ropers, Claus; Corkum, P B
2017-07-21
The advent of high-harmonic generation in gases 30 years ago set the foundation for attosecond science and facilitated ultrafast spectroscopy in atoms, molecules, and solids. We explore high-harmonic generation in the solid state by means of nanostructured and ion-implanted semiconductors. We use wavelength-selective microscopic imaging to map enhanced harmonic emission and show that the generation medium and the driving field can be locally tailored in solids by modifying the chemical composition and morphology. This enables the control of high-harmonic technology within precisely engineered solid targets. We demonstrate customized high-harmonic wave fields with wavelengths down to 225 nanometers (ninth-harmonic order of 2-micrometer laser pulses) and present an integrated Fresnel zone plate target in silicon, which leads to diffraction-limited self-focusing of the generated harmonics down to 1-micrometer spot sizes. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.
High-harmonic generation in amorphous solids.
You, Yong Sing; Yin, Yanchun; Wu, Yi; Chew, Andrew; Ren, Xiaoming; Zhuang, Fengjiang; Gholam-Mirzaei, Shima; Chini, Michael; Chang, Zenghu; Ghimire, Shambhu
2017-09-28
High-harmonic generation in isolated atoms and molecules has been widely utilized in extreme ultraviolet photonics and attosecond pulse metrology. Recently, high-harmonic generation has been observed in solids, which could lead to important applications such as all-optical methods to image valance charge density and reconstruct electronic band structures, as well as compact extreme ultraviolet light sources. So far these studies are confined to crystalline solids; therefore, decoupling the respective roles of long-range periodicity and high density has been challenging. Here we report the observation of high-harmonic generation from amorphous fused silica. We decouple the role of long-range periodicity by comparing harmonics generated from fused silica and crystalline quartz, which contain the same atomic constituents but differ in long-range periodicity. Our results advance current understanding of the strong-field processes leading to high-harmonic generation in solids with implications for the development of robust and compact extreme ultraviolet light sources.Although higher harmonic generation from solids has become of interest in many fields, its observation is typically limited to crystalline solids. Here, the authors demonstrate that higher harmonics can be generated from amorphous solids.
Harmonic Aspects of Offshore Wind Farms
DEFF Research Database (Denmark)
Kocewiak, Lukasz Hubert; Bak, Claus Leth; Hjerrild, Jesper
2010-01-01
This paper presents the aim, the work and the findings of a PhD project entitled "Harmonics in Large Offshore Wind Farms". It focuses on the importance of harmonic analysis in order to obtain a better performance of future wind farms. The topic is investigated by the PhD project at Aalborg...... University (AAU) and DONG Energy. The objective of the project is to improve and understand the nature of harmonic emission and propagation in wind farms (WFs), based on available information, measurement data and simulation tools. The aim of the project is to obtain validated models and analysis methods...... of offshore wind farm (OWF) systems....
Selective harmonic control for power converters
DEFF Research Database (Denmark)
Zhou, Keliang; Yang, Yongheng; Blaabjerg, Frede
2014-01-01
This paper proposes an Internal Model Principle (IMP) based Selective Harmonic Controller (SHC) for power converters. The proposed SHC offers an optimal control solution for power converters to mitigate power harmonics. It makes a good trade-off among cost, complexity and performance. It has high...... accuracy and fast transient response, and it is cost-effective, easy for real-time implementation, and compatible for design rules-of-thumb. An application on a three-phase PWM converter has confirmed the effectiveness of the proposed control scheme in terms of harmonic mitigation....
Harmonic Distortion in CMOS Current Mirrors
DEFF Research Database (Denmark)
Bruun, Erik
1998-01-01
One of the origins of harmonic distortion in CMOS current mirrors is the inevitable mismatch between the MOS transistors involved. In this paper we examine both single current mirrors and complementary class AB current mirrors and develop an analytical model for the mismatch induced harmonic...... distortion. This analytical model is verified through simulations and is used for a discussion of the impact of mismatch on harmonic distortion properties of CMOS current mirrors. It is found that distortion levels somewhat below 1% can be attained by carefully matching the mirror transistors but ultra low...
Double Harmonic Transmission (D.H.T.
Directory of Open Access Journals (Sweden)
Sava Ianici
2006-10-01
Full Text Available The paper presents the construction and functioning of a new type of harmonic drive named double harmonic transmission (D.H.T.. In the second part of this paper is presented the dynamic analysis of the double harmonic transmission, which is based on the results of the experimental researches on the D.H.T. This study of the stress status and the forces distribution is necessary for to determine the durability on the portant elements of the D.H.T.
Effects of harmonic roving on pitch discrimination
DEFF Research Database (Denmark)
Santurette, Sébastien; de Kérangal, Mathilde le Gal; Joshi, Suyash Narendra
2015-01-01
external noise in the physical stimulus (Lu and Dosher, 2008). The present study used this approach to attempt to quantify the “internal noise” involved in pitch coding of harmonic complex tones by estimating the amount of harmonic roving required to impair pitch discrimination performance. It remains...... performance may help clarify pitch coding mechanisms. As training on frequency discrimination tasks has been found to result in a reduction of internal noise (Jones et al., 2013), it was also investigated whether the effect of harmonic roving varied with musical training...
Simulation of Second Harmonic Ultrasound Fields
DEFF Research Database (Denmark)
Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt
2010-01-01
, and the fundamental pressure is calculated by Field II. The second harmonic pressure in k-space along the propagating direction is calculated as an auto-convolution of the fundamental pressure multiplied by an exponential propagating coefficient. In this case, the second harmonic pressure can be calculated using ASA...... for any plane parallel to the initial plane. In the focal plane (elevation-lateral) at 60 mm from the transducer surface, calculated by ASA, the RMS errors for the fundamental component are 2.66% referred to Field II and 4.28% referred to Abersim. For the second harmonic component, the RMS error is 0...
Some aspects of harmonic time series analysis
2012-01-01
Ph.D. Harmonic time series are often used to describe the periodic nature of a time series, for example the periodic nature of a variable star’s observed light curve. Statistical methods for determining the number of harmonic components to include in harmonic time series are limited. In this thesis a stepwise bootstrap procedure based on a F-type statistic is suggested. The performance of the stepwise procedure is compared to that of Schwartz’s Bayesian Criterion (SBC) and a procedure base...
SEVENTH HARMONIC 20 GHz CO-GENERATOR
Energy Technology Data Exchange (ETDEWEB)
Hirshfield, Jay L
2014-04-08
To satisfy the need for multi-MW rf sources in frequency ranges where commercial sources do not exist, a study was undertaken on a class of devices based on gyro-harmonic frequency multiplication. This mechanism relies upon adding energy in gyrating motion to a linear electron beam that traverses a rotating-mode TE111-mode drive cavity in a dc magnetic field. The beam then drifts along the magnetic field into a second cavity, operating in the TEn11-mode tuned to the nth harmonic of the drive cavity. Studies of this configuration have been carried out for 2 < n < 7. Results are given for multi-MW, efficient operation of a 7th harmonic device operating at 20 GHz, and a 2nd harmonic device operating at 22.4 GHz.
Dispersion-enhanced third-harmonic microscopy
Stock, Christian; Zlatanov, Kaloyan; Halfmann, Thomas
2017-06-01
We demonstrate strong enhancements of signal yield and image contrast in third-harmonic microscopy by appropriate choice of driving laser wavelength to modulate the phase-matching conditions of the conversion process by dispersion control. Tuning the laser wavelength in the range of 1010 - 1350 nm at samples containing interfaces with water and glass, we obtained large signal enhancements up to a factor of 19, and improvements in the image contrast by an order of magnitude. The effect is most pronounced at interfaces with media of small and/or not too different nonlinear optical susceptibilities, e.g., as it is the case in typical samples in harmonic microscopy. Beyond the demonstration of this new variant of third-harmonic microscopy, our findings are also of relevance to a proper choice of laser systems for harmonic microscopy setups.
Developing Castable Metal Harmonic Drives Project
National Aeronautics and Space Administration — This effort utilizes the high elastic strain limit and net-shaped processing of metallic glasses to fabricate low-cost harmonic drives that outperform steel. ...
Challenges and Opportunities for Harmonizing Research Methodology
DEFF Research Database (Denmark)
van Hees, V. T.; Thaler-Kall, K.; Wolf, K. H.
2016-01-01
Objectives: Raw accelerometry is increasingly being used in physical activity research, but diversity in sensor design, attachment and signal processing challenges the comparability of research results. Therefore, efforts are needed to harmonize the methodology. In this article we reflect on how...... increased methodological harmonization may be achieved. Methods: The authors of this work convened for a two-day workshop (March 2014) themed on methodological harmonization of raw accelerometry. The discussions at the workshop were used as a basis for this review. Results: Key stakeholders were identified...... algorithms which are pitched as "ready for implementation" should be shared with the community to facilitate replication and ongoing evaluation by independent groups, and v) A dynamic interaction between method stakeholders should be encouraged to facilitate a well-informed harmonization process. Conclusions...
Improved Efficiency Type II Second Harmonic Generation
Barnes, Norman P.; Walsh, Brian M.; Reichle, Donald J., Jr.
2009-01-01
Second harmonic efficiency is limited by lateral and temporal separation of the ordinary and extraordinary components of the fundamental. A mode locked dual beam laser demonstrated these effects and a novel method to minimize them.
Multiculturalism, Europhilia and harmonization: harmony or disharmony?
Directory of Open Access Journals (Sweden)
Ruth Sefton-Green
2010-11-01
Full Text Available This paper examines the difficulties of reconciling the values promoted by multiculturalism with the objectives of harmonization. In the event of conflict, examples from English and French law show that harmonization of private law rules does not always achieve its aim of approximating national laws but, on the contrary, often backfires. The question of whether and why these divergences produce Europhile or Eurosceptic positions amongst Member States is addressed. It appears that when maximum harmonisation clashes with multiculturalism this can lead to legal nationalism, whereas minimum harmonization has less negative effects and can stimulate legal experimentation. It is suggested that harmonization requires a mutual listening and learning process in order to accommodate the multiculturalism of Member States and enable Europhilia to flourish in the European Union.
Reduction of Harmonics by 18-Pulse Rectifier
Directory of Open Access Journals (Sweden)
Stanislav Kocman
2008-01-01
Full Text Available Operation of such electrical devices as data processing and electronics devices, adjustable speed drives or uninterruptible power supply can cause problems by generating harmonic currents into the network, from which they are supplied. Effects of these harmonic currents are various, they can get worse the quality of supply voltage in the network or to have negative influences on devices connected to this network. There are various technical solutions for reduction of harmonics. One of them is using of multi-pulse rectifiers, whereas the 18-pulse rectifier in the structure of adjustable speed drive is briefly presented in this paper including some results of its behaviour. The examined experimental measurements confirmed its very good efficiency in the harmonic mitigation.
Perturbative High Harmonic Wave Front Control.
Li, Zhengyan; Brown, Graham; Ko, Dong Hyuk; Kong, Fanqi; Arissian, Ladan; Corkum, P B
2017-01-20
We pattern the wave front of a high harmonic beam by intersecting the intense driving laser pulse that generates the high harmonic with a weak control pulse. To illustrate the potential of wave-front control, we imprint a Fresnel zone plate pattern on a harmonic beam, causing the harmonics to focus and defocus. The quality of the focus that we achieve is measured using the spectral wave-front optical reconstruction by diffraction method. We will show that it is possible to enhance the peak intensity by orders of magnitude without a physical optical element in the path of the extreme ultraviolet (XUV) beam. Through perturbative wave-front control, XUV beams can be created with a flexibility approaching what technology allows for visible and infrared light.
On conformal supergravity and harmonic superspace
Energy Technology Data Exchange (ETDEWEB)
Butter, Daniel [Nikhef Theory Group,Science Park 105, 1098 XG Amsterdam (Netherlands)
2016-03-16
This paper describes a fully covariant approach to harmonic superspace. It is based on the conformal superspace description of conformal supergravity and involves extending the supermanifold M{sup 4|8} by the tangent bundle of ℂP{sup 1}. The resulting superspace M{sup 4|8}×TℂP{sup 1} can be identified in a certain gauge with the conventional harmonic superspace M{sup 4|8}×S{sup 2}. This approach not only makes the connection to projective superspace transparent, but simplifies calculations in harmonic superspace significantly by eliminating the need to deal directly with supergravity prepotentials. As an application of the covariant approach, we derive from harmonic superspace the full component action for the sigma model of a hyperkähler cone coupled to conformal supergravity. Further applications are also sketched.
Energy Technology Data Exchange (ETDEWEB)
Schneidmiller, E.A.; Yurkov, M.V.
2012-05-15
Harmonic lasing in a free electron laser with a planar undulator (under the condition that the fundamental frequency is suppressed) might be a cheap and efficient way of extension of wavelength ranges of existing and planned X-ray FEL facilities. Contrary to nonlinear harmonic generation, harmonic lasing can provide much more intense, stable, and narrow-band FEL beam which is easier to handle due to the suppressed fundamental frequency. In this paper we perform a parametrization of the solution of the eigenvalue equation for lasing at odd harmonics, and present an explicit expression for FEL gain length, taking into account all essential effects. We propose and discuss methods for suppression of the fundamental harmonic. We also suggest a combined use of harmonic lasing and lasing at the retuned fundamental wavelength in order to reduce bandwidth and to increase brilliance of X-ray beam at saturation. Considering 3rd harmonic lasing as a practical example, we come to the conclusion that it is much more robust than usually thought, and can be widely used in the existing or planned X-ray FEL facilities. In particular, LCLS after a minor modification can lase to saturation at the 3rd harmonic up to the photon energy of 25-30 keV providing multi-gigawatt power level and narrow bandwidth. As for the European XFEL, harmonic lasing would allow to extend operating range (ultimately up to 100 keV), to reduce FEL bandwidth and to increase brilliance, to enable two-color operation for pump-probe experiments, and to provide more flexible operation at different electron energies. Similar improvements can be realized in other X-ray FEL facilities with gap-tunable undulators like FLASH II, SACLA, LCLS II, etc. Harmonic lasing can be an attractive option for compact X-ray FELs (driven by electron beams with a relatively low energy), allowing the use of the standard undulator technology instead of small-gap in-vacuum devices. Finally, in this paper we discover that in a part of the
Fractal harmonic law and waterproof/dustproof
Directory of Open Access Journals (Sweden)
Kong Hai-Yan
2014-01-01
Full Text Available The fractal harmonic law admits that the friction between the pure water and the moving surface is the minimum when fractal dimensions of water in Angstrom scale are equal to fractal dimensions of the moving surface in micro scale. In the paper, the fractal harmonic law is applied to demonstrate the mechanism of waterproof/ dustproof. The waterproof phenomenon of goose feathers and lotus leaves is illustrated to verify our results and experimental results agree well with our theoretical analysis.
Harmonic algebraic curves and noncrossing partitions
Martin, Jeremy; Savitt, David; Singer, Ted
2005-01-01
Motivated by Gauss's first proof of the Fundamental Theorem of Algebra, we study the topology of harmonic algebraic curves. By the maximum principle, a harmonic curve has no bounded components; its topology is determined by the combinatorial data of a noncrossing matching. Similarly, every complex polynomial gives rise to a related combinatorial object that we call a basketball, consisting of a pair of noncrossing matchings satisfying one additional constraint. We prove that every noncrossing...
Harmonic distortion in microwave photonic filters.
Rius, Manuel; Mora, José; Bolea, Mario; Capmany, José
2012-04-09
We present a theoretical and experimental analysis of nonlinear microwave photonic filters. Far from the conventional condition of low modulation index commonly used to neglect high-order terms, we have analyzed the harmonic distortion involved in microwave photonic structures with periodic and non-periodic frequency responses. We show that it is possible to design microwave photonic filters with reduced harmonic distortion and high linearity even under large signal operation.
Harmonic Oscillator SUSY Partners and Evolution Loops
Directory of Open Access Journals (Sweden)
David J. Fernández
2012-07-01
Full Text Available Supersymmetric quantum mechanics is a powerful tool for generating exactly solvable potentials departing from a given initial one. If applied to the harmonic oscillator, a family of Hamiltonians ruled by polynomial Heisenberg algebras is obtained. In this paper it will be shown that the SUSY partner Hamiltonians of the harmonic oscillator can produce evolution loops. The corresponding geometric phases will be as well studied.
Measuring Spherical Harmonic Coefficients on a Sphere
Energy Technology Data Exchange (ETDEWEB)
Pollaine, S; Haan, S W
2003-05-16
The eigenfunctions of Rayleigh-Taylor modes on a spherical capsule are the spherical harmonics Y{sub l,m} These can be measured by measuring the surface perturbations along great circles and fitting them to the first few modes by a procedure described in this article. For higher mode numbers, it is more convenient to average the Fourier power spectra along the great circles, and then transform them to spherical harmonic modes by an algorithm derived here.
TOTAL HARMONIC DISTORTION ANALYSIS OF MATRIX CONVERTER
K. Kandan; Senthilkumar,K.; Dhivya, K.
2016-01-01
This paper deals with the validation and design analysis of Matrix converter for variable frequency using mathematical equations. The analysis was done using Venturini modulation algorithm. The PI controller is used for Matrix converter to reduce Total Harmonic Distortion (THD) in the output current. The comparative study is done for open loop and closed loop PI compensation in MATLAB-Simulink. Furthermore, the output waveforms are produced with significant reduction in the Total Harmonic Dis...
Harmonic focus in thyroidectomy for substernal goiter.
Hahn, Christoffer Holst; Trolle, Waldemar; Sørensen, Christian Hjort
2015-08-01
No previous prospective study has evaluated harmonic scalpel in thyroidectomy for substernal goiter. The objective of this study was to evaluate the use of harmonic scalpel (FOCUS shear, Ethicon Endo-Surgery) in thyroidectomy for substernal goiter for blood loss, operative time, hospital stay and complications. Prospective non-randomised study of 242 consecutive patients with substernal goiter out of 2258 patients (11%) who underwent thyroidectomy. A total of 121 patients had thyroidectomy performed with bipolar electrocoagulation and knot-tying techniques and 121 patients had harmonic scalpel thyroidectomy. The use of harmonic scalpel was associated with significant reduction in intraoperative blood loss (50 vs. 100mL, p=0.001), postoperative haemorrhage (4% vs. 12%, p=0.03) and length of hospital stay (2 vs. 3 days, p=0.001). The mean operative time was significantly longer in the harmonic group. Harmonic scalpel is a safe tool for thyroidectomy for substernal goiter. Its utilisation is associated with reduced blood loss, lower incidence of postoperative haemorrhage and shorter hospital stay. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
High harmonic generation from axial chiral molecules.
Wang, Dian; Zhu, Xiaosong; Liu, Xi; Li, Liang; Zhang, Xiaofan; Lan, Pengfei; Lu, Peixiang
2017-09-18
Axial chiral molecules, whose stereogenic element is an axis rather than a chiral center, have attracted widespread interest due to their important application, such as asymmetric synthesis and chirality transfer. We investigate high harmonic generation from axial chiral molecules with bichromatic counterrotating circularly polarized laser fields. High harmonic generation from three typical molecules: (Sa)-3-chloropropa-1,2-dien-1-ol, propadiene, and (Ra)-2,3-pentadiene is simulated with time-dependent density-functional theory and strong field approximation. We found that harmonic spectra for 3D oriented axial chiral molecules exhibit obvious circular dichroism. However, the circular dichroism of High harmonic generation from an achiral molecule is much trivial. Moreover, the dichroism of high harmonic generation still exists when axial chiral molecules are 1D oriented,such as (Sa) -3-chloropropa-1,2-dien-1-ol. For a special form of axial chiral molecules with the formula abC=C=Cab (a, b are different substituents), like (Ra)-2,3-pentadiene, the dichroism discriminations disappear when the molecules are only in 1D orientation. The circular dichroism of high harmonic generation from axial chiral molecules is well explained by the trajectory analysis based on the semiclassical three-step mechanism.
High-order harmonic generation in laser plasma: Recent achievements
Ganeev, R. A.
2012-07-01
Recent studies of high-order harmonic generation of laser radiation in laser-produced plasma show new attractive developments in this field. Those include generation of extended harmonics in plasma plumes, new approaches in application of two-color pump, generation of extremely broadened harmonics, further developments in harmonic generation in clusters (fullerenes, carbon nanotubes, in-situ produced nanoparticles), destructive interference of harmonics from different emitters, resonance-induced enhancement of harmonics, applications of high pulse repetition rate lasers for the enhancement of average power of generating harmonics, observation of quantum path signatures, etc. We review some of these recent developments.
Development of high-order harmonic focusing system based on ellipsoidal mirror
Energy Technology Data Exchange (ETDEWEB)
Motoyama, H.; Takei, Y.; Kume, T.; Egawa, S.; Mimura, H., E-mail: mimura@edm.t.u-tokyo.ac.jp [Department of Precision Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkuyo-ku, Tokyo 113-8656 (Japan); Sato, T.; Iwasaki, A.; Yamanouchi, K. [Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Hiraguri, K.; Hashizume, H. [Natsume Optical Corp., 3461 Kamichaya, Kanae, Iida, Nagano 395-0808 (Japan)
2016-05-15
We have developed a focusing system for extreme ultraviolet light produced by high-order harmonic generation. An ellipsoidal mirror with a precise surface shape was fabricated and installed into the focusing system. A rigid mirror manipulator and a beam profiler were employed to perform precise and stable mirror alignment. As a demonstration of the focusing performance, high-order harmonics in the wavelength range of 13.5–19.5 nm were successfully focused into a 2.4 × 2.3 μm{sup 2} spot.
XUV digital in-line holography using high-order harmonics
Genoud, G.; Guilbaud, O.; Mengotti, E.; Pettersson, S.-G.; Georgiadou, E.; Pourtal, E.; Wahlström, C.-G.; L'Huillier, A.
2008-03-01
A step towards a successful implementation of time-resolved digital in-line holography with extreme ultraviolet (XUV) radiation is presented. Ultra-short XUV pulses are produced as high-order harmonics of a femtosecond laser and a Schwarzschild objective is used to focus harmonic radiation at 38 nm and to produce a strongly divergent reference beam for holographic recording. Experimental holograms of thin wires are recorded and the objects reconstructed. Descriptions of the simulation and reconstruction theory and algorithms are also given. Spatial resolution of a few hundreds of nanometers is potentially achievable, and the micrometer resolution range is demonstrated.
Microwave harmonic generation and nonlinearity in microplasmas
Gregório, José; Parsons, Stephen; Hopwood, Jeffrey
2016-06-01
Nonlinearities in microplasmas excited by microwaves are described both experimentally and through a 2D fluid model. A split-ring resonator generates a microplasma in a 150 μm discharge gap at 1 GHz. Nonlinearity generates both radiated and conducted harmonics which are measured from 0.2-760 Torr (Ar) for power levels between 0.5 and 3 W. Asymmetric electrode configurations produce the highest 3rd harmonic power (>10 mW) at an optimal pressure of the order of 0.3 Torr. The microplasma is also demonstrated as a mixer. The experimental results are explained with the aid of a fluid model of the microplasma. The model shows that the smaller electrode in an asymmetric device is forced to attain a large microwave potential that strongly modulates the sheath thickness and the local electron energy. The voltage-dependent sheath width gives rises to a nonlinear sheath capacitance as well as short pulses of hot electron flux to the electrode. The modeled 3rd harmonic current is converted to an extractable harmonic power by a microwave circuit model. Using this technique the modeled and measured harmonic production of the microplasma are found to compare favorably.
Relativistic harmonics for turbulent wakefield diagnostics
Kuramitsu, Yasuhiro; Chen, Shih-Hung
2017-06-01
The propagation properties of relativistic harmonics excited in a plasma with an intense laser pulse is investigated theoretically and numerically. Focusing on the frequency separation, a cold electron fluid model in two spatial dimension is discussed to obtain the harmonic amplitude. The theoretical predictions are verified by performing particle-in-cell simulations in two spatial dimensions. When the laser amplitude is large, the strong ponderomotive force expels the electrons, creating a large amplitude density structures associated with the wakefield. The harmonics propagate obliquely with respect to the laser propagation direction, which is well represented by the structure of the high density layer resulting from the transverse poderomotive force. We also discuss a possible experimental setup to observe the density structures relevant to wakefield.
Optical Third-Harmonic Generation in Graphene
Directory of Open Access Journals (Sweden)
Sung-Young Hong
2013-06-01
Full Text Available We report strong third-harmonic generation in monolayer graphene grown by chemical vapor deposition and transferred to an amorphous silica (glass substrate; the photon energy is in three-photon resonance with the exciton-shifted van Hove singularity at the M point of graphene. The polarization selection rules are derived and experimentally verified. In addition, our polarization- and azimuthal-rotation-dependent third-harmonic-generation measurements reveal in-plane isotropy as well as anisotropy between the in-plane and out-of-plane nonlinear optical responses of graphene. Since the third-harmonic signal exceeds that from bulk glass by more than 2 orders of magnitude, the signal contrast permits background-free scanning of graphene and provides insight into the structural properties of graphene.
Does high harmonic generation conserve angular momentum?
Fleischer, Avner; Diskin, Tzvi; Sidorenko, Pavel; Cohen, Oren
2013-01-01
High harmonic generation (HHG) is a unique and useful process in which infrared or visible radiation is frequency up converted into the extreme ultraviolet and x ray spectral regions. As a parametric process, high harmonic generation should conserve the radiation energy, momentum and angular momentum. Indeed, conservation of energy and momentum have been demonstrated. Angular momentum of optical beams can be divided into two components: orbital and spin (polarization). Orbital angular momentum is assumed to be conserved and recently observed deviations were attributed to propagation effects. On the other hand, conservation of spin angular momentum has thus far never been studied, neither experimentally nor theoretically. Here, we present the first study on the role of spin angular momentum in extreme nonlinear optics by experimentally generating high harmonics of bi chromatic elliptically polarized pump beams that interact with isotropic media. While observing that the selection rules qualitatively correspond...
Intense Harmonic Emissions Observed in Saturn's Ionosphere
Sulaiman, A. H.; Kurth, W. S.; Persoon, A. M.; Menietti, J. D.; Farrell, W. M.; Ye, S.-Y.; Hospodarsky, G. B.; Gurnett, D. A.; Hadid, L. Z.
2017-12-01
The Cassini spacecraft's first Grand Finale orbit was carried out in April 2017. This set of 22 orbits had an inclination of 63° with a periapsis grazing Saturn's ionosphere, thus providing unprecedented coverage and proximity to the planet. Cassini's Radio and Plasma Wave Science instrument repeatedly detected intense electrostatic waves and their harmonics near closest approach in the dayside equatorial topside ionosphere. The fundamental modes were found to both scale and trend best with the H+ plasma or lower hybrid frequencies, depending on the plasma composition considered. The fine-structured harmonics are unlike previous observations, which scale with cyclotron frequencies. We explore their generation mechanism and show strong evidence of their association with whistler mode waves, consistent with theory. The possibility of Cassini's presence in the ionosphere influencing the resonance and harmonics is discussed. Given their link to the lower hybrid frequency, these emissions may offer clues to constraining Saturn's ionospheric properties.
Harmonic and complex analysis in several variables
Krantz, Steven G
2017-01-01
Authored by a ranking authority in harmonic analysis of several complex variables, this book embodies a state-of-the-art entrée at the intersection of two important fields of research: complex analysis and harmonic analysis. Written with the graduate student in mind, it is assumed that the reader has familiarity with the basics of complex analysis of one and several complex variables as well as with real and functional analysis. The monograph is largely self-contained and develops the harmonic analysis of several complex variables from the first principles. The text includes copious examples, explanations, an exhaustive bibliography for further reading, and figures that illustrate the geometric nature of the subject. Each chapter ends with an exercise set. Additionally, each chapter begins with a prologue, introducing the reader to the subject matter that follows; capsules presented in each section give perspective and a spirited launch to the segment; preludes help put ideas into context. Mathematicians and...
[Use of Harmonic blade in face lifting].
Firmin, F; Vincent, P-L
2017-10-01
Rapid recovery and return to social activities are what every patient wishes when considering to undergo a face lifting procedure. In our practice, the use of the Harmonic scalpel in order to achieve this goal has greatly improved the postoperative period. We have performed 920 face lifting procedures exclusively using the Harmonic scalpel from 2001 to May 2017. A retrospective chart review was performed. Mean operative time was 110minutes for facelift involving SMAS plication only, and 180minutes for facelift involving SMAS plication with the addition of submental approach for anterior platysma plasty. Return to normal social life was achieved on the 8th postoperative day for the majority of cases. The use of the Harmonic scalpel, once properly integrated in the face lifting procedure, significantly reduces postoperative ecchymosis and oedema and allows a prompt return to normal social life. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
High harmonic phase in molecular nitrogen
Energy Technology Data Exchange (ETDEWEB)
McFarland, Brian K.
2009-10-17
Electronic structure in atoms and molecules modulates the amplitude and phase of high harmonic generation (HHG). We report measurements of the high harmonic spectral amplitude and phase in N{sub 2}. The phase is measured interferometrically by beating the N{sub 2} harmonics with those of an Ar reference oscillator in a gas mixture. A rapid phase shift of 0.2{pi} is observed in the vicinity of the HHG spectral minimum, where a shift of {pi} had been presumed [J. Itatani et al., Nature 432, 867 (2004)]. We compare the phase measurements to a simulation of the HHG recombination step in N{sub 2} that is based on a simple interference model. The results of the simulation suggest that modifications beyond the simple interference model are needed to explain HHG spectra in molecules.
The harmonic oscillator and nuclear physics
Rowe, D. J.
1993-01-01
The three-dimensional harmonic oscillator plays a central role in nuclear physics. It provides the underlying structure of the independent-particle shell model and gives rise to the dynamical group structures on which models of nuclear collective motion are based. It is shown that the three-dimensional harmonic oscillator features a rich variety of coherent states, including vibrations of the monopole, dipole, and quadrupole types, and rotations of the rigid flow, vortex flow, and irrotational flow types. Nuclear collective states exhibit all of these flows. It is also shown that the coherent state representations, which have their origins in applications to the dynamical groups of the simple harmonic oscillator, can be extended to vector coherent state representations with a much wider range of applicability. As a result, coherent state theory and vector coherent state theory become powerful tools in the application of algebraic methods in physics.
Harmonic analysis and the theory of probability
Bochner, Salomon
2005-01-01
Nineteenth-century studies of harmonic analysis were closely linked with the work of Joseph Fourier on the theory of heat and with that of P. S. Laplace on probability. During the 1920s, the Fourier transform developed into one of the most effective tools of modern probabilistic research; conversely, the demands of the probability theory stimulated further research into harmonic analysis.Mathematician Salomon Bochner wrote a pair of landmark books on the subject in the 1930s and 40s. In this volume, originally published in 1955, he adopts a more probabilistic view and emphasizes stochastic pro
Fullerenes: The attractive medium for harmonic generation
Ganeev, R. A.
2011-01-01
We review the results of systematic experimental studies of high-order harmonic generation (HHG) in C60-rich laser-produced plasma under different plasma conditions and laser parameters. The morphology of fullerene clusters before and after ablation is analyzed to define the optimal conditions of excitation of C60-containing targets. The enhancement of HHG efficiency in C60-rich plasmas by using the two-color pump technique is discussed. The conversion efficiency for the odd and even harmonics in the vicinity of surface plasmon resonance of the C60-containing plasma (40-70 nm) was estimated to be in the range of 10-4.
Music of the heavens Kepler's harmonic astronomy
Stephenson, Bruce
2014-01-01
Valued today for its development of the third law of planetary motion, Harmonice mundi (1619) was intended by Kepler to expand on ancient efforts to discern a Creator's plan for the planetary system--an arrangement thought to be based on harmonic relationships. Challenging critics who characterize Kepler's theories of harmonic astronomy as ""mystical,"" Bruce Stephenson offers the first thorough technical analysis of the music the astronomer thought the heavens made, and the logic that led him to find musical patterns in his data. In so doing, Stephenson illuminates crucial aspects of Kepler'
Honeycomb optical lattices with harmonic confinement
DEFF Research Database (Denmark)
Jacobsen, Jens Kusk Block; Nygaard, Nicolai
2010-01-01
We consider the fate of the Dirac points in the spectrum of a honeycomb optical lattice in the presence of a harmonic confining potential. By numerically solving the tight binding model, we calculate the density of states and find that the energy dependence can be understood from analytical...... arguments. In addition, we show that the density of states of the harmonically trapped lattice system can be understood by application of a local density approximation based on the density of states in the homogeneous lattice. The Dirac points are found to survive locally in the trap as evidenced...
Nonlinear harmonic generation in distributed optical klystrons
Freund, H P
2001-01-01
A distributed optical klystron has the potential for dramatically shortening the total interaction length in high-gain free-electron lasers (INP 77-59, Novosibirsk, 1977; Nucl. Instr. and Meth. A 304 (1991) 463) in comparison to a single-wiggler-segment configuration. This shortening can be even more dramatic if a nonlinear harmonic generation mechanism is used to reach the desired wavelength. An example operating at a 4.5(angstrom) fundamental and a 1.5(angstrom) harmonic is discussed.
Probabilistic Aspects of Harmonic Emission of Large Offshore Wind Farms
DEFF Research Database (Denmark)
Jensen, Christian Flytkjær; Bak, Claus Leth; Kocewiak, Lukasz Hubert
2011-01-01
of the harmonic emission. The simulated harmonic distortion at the PCC is compared to measurement. This reveals some diffi-culties regarding harmonic load flow studies. The harmonic background distortion in the grid to where the wind farm is connected must be included in the study. Furthermore, a very detailed......In this article, a new probabilistic method of as-sessment of harmonic emission of large offshore wind farms is presented. Based on measurements from the British wind farm Burbo Banks, probability density functions are estimated for the dominating low order harmonic currents injected by a single...
Harmonic Interaction Analysis in Grid-connected Converter using Harmonic State Space (HSS) Modeling
DEFF Research Database (Denmark)
Kwon, Jun Bum; Wang, Xiongfei; Blaabjerg, Frede
2017-01-01
. Furthermore, a harmonic matrix of the grid-connected converter is developed to analyze the harmonic interaction at the steady-state behavior. Besides, the frequency-domain results are compared with time-domain simulation results by using HSS modeling to verify the theoretical analysis. Experimental results...... research about the harmonic interaction. However, it is found that the Linear Time Invariant (LTI) based model analysis makes it difficult to analyze these phenomena because of the time-varying properties of the power electronic based systems. This paper investigates grid-connected converter by using...
Mak, Lora; Grandison, Scott; Morris, Richard J
2008-04-01
The use of spherical harmonics in the molecular sciences is widespread. They have been employed with success in, for instance, the crystallographic fast rotation function, small-angle scattering particle reconstruction, molecular surface visualisation, protein-protein docking, active site analysis and protein function prediction. An extension of the spherical harmonic expansion method is presented here that enables regions (bodies) rather than contours (surfaces) to be described and which lends itself favourably to the construction of rotationally invariant shape descriptors. This method introduces a radial term that extends the spherical harmonics to 3D polynomials. These polynomials maintain the advantages of the spherical harmonics (orthonormality, completeness, uniqueness and fast computation) but correct the drawbacks (contour based shape description and star-shape objects) and give rise to powerful invariant descriptors. We provide proof-of-principle examples illustrating the potential of this method for accurate object representation, an analysis of the descriptor classification power, and comparisons to other methods.
Hyperbolic Harmonic Mapping for Surface Registration.
Shi, Rui; Zeng, Wei; Su, Zhengyu; Jiang, Jian; Damasio, Hanna; Lu, Zhonglin; Wang, Yalin; Yau, Shing-Tung; Gu, Xianfeng
2017-05-01
Automatic computation of surface correspondence via harmonic map is an active research field in computer vision, computer graphics and computational geometry. It may help document and understand physical and biological phenomena and also has broad applications in biometrics, medical imaging and motion capture industries. Although numerous studies have been devoted to harmonic map research, limited progress has been made to compute a diffeomorphic harmonic map on general topology surfaces with landmark constraints. This work conquers this problem by changing the Riemannian metric on the target surface to a hyperbolic metric so that the harmonic mapping is guaranteed to be a diffeomorphism under landmark constraints. The computational algorithms are based on Ricci flow and nonlinear heat diffusion methods. The approach is general and robust. We employ our algorithm to study the constrained surface registration problem which applies to both computer vision and medical imaging applications. Experimental results demonstrate that, by changing the Riemannian metric, the registrations are always diffeomorphic and achieve relatively high performance when evaluated with some popular surface registration evaluation standards.
SOME THEOREMS ON HARMONIC RENEWAL MEASURES
STAM, AJ
1991-01-01
The harmonic renewal measure nu for the random walk S(n) is defined by nu(A) = SIGMA-n = 1 infinity n-1 P(S(n) is-an-element-of A). The paper gives weak asymptotic relations as x --> infinity for nu([0,x]) under weak conditions.
Psychoacoustic Approaches for Harmonic Music Mixing
Directory of Open Access Journals (Sweden)
Roman B. Gebhardt
2016-05-01
Full Text Available The practice of harmonic mixing is a technique used by DJs for the beat-synchronous and harmonic alignment of two or more pieces of music. In this paper, we present a new harmonic mixing method based on psychoacoustic principles. Unlike existing commercial DJ-mixing software, which determines compatible matches between songs via key estimation and harmonic relationships in the circle of fifths, our approach is built around the measurement of musical consonance. Given two tracks, we first extract a set of partials using a sinusoidal model and average this information over sixteenth note temporal frames. By scaling the partials of one track over ±6 semitones (in 1/8th semitone steps, we determine the pitch-shift that maximizes the consonance of the resulting mix. For this, we measure the consonance between all combinations of dyads within each frame according to psychoacoustic models of roughness and pitch commonality. To evaluate our method, we conducted a listening test where short musical excerpts were mixed together under different pitch shifts and rated according to consonance and pleasantness. Results demonstrate that sensory roughness computed from a small number of partials in each of the musical audio signals constitutes a reliable indicator to yield maximum perceptual consonance and pleasantness ratings by musically-trained listeners.
ACCOUNTING HARMONIZATION AND HISTORICAL COST ACCOUNTING
Directory of Open Access Journals (Sweden)
Valentin Gabriel CRISTEA
2017-05-01
Full Text Available There is a huge interest in accounting harmonization and historical costs accounting, in what they offer us. In this article, different valuation models are discussed. Although one notices the movement from historical cost accounting to fair value accounting, each one has its advantages.
Harmonic analysis of Doubly Fed Induction Generators
DEFF Research Database (Denmark)
Lindholm, Morten; Rasmussen, Tonny Wederberg
2003-01-01
This paper gives an overview of the frequency spectrum of the stator and rotor currents in a doubly fed induction generator (DFIG) used in wind power applications. The paper also presents a method to eliminate higher harmonics and interharmonics in the DFIG stator current. The method is implemented...
Modelling the harmonized tertiary Institutions Salary Structure ...
African Journals Online (AJOL)
This paper analyses the Harmonized Tertiary Institution Salary Structure (HATISS IV) used in Nigeria. The irregularities in the structure are highlighted. A model that assumes a polynomial trend for the zero step salary, and exponential trend for the incremental rates, is suggested for the regularization of the structure.
Information cloning of harmonic oscillator coherent states
Indian Academy of Sciences (India)
Abstract. We show that in the case of unknown harmonic oscillator coherent states it is possible to achieve what we call perfect information cloning. By this we mean that it is still possible to make arbitrary number of copies of a state which has exactly the same information content as the original unknown coherent state.
Hyperchaotic circuit with damped harmonic oscillators
DEFF Research Database (Denmark)
Lindberg, Erik; Murali, K.; Tamasevicius, A.
2001-01-01
A simple fourth-order hyperchaotic circuit with damped harmonic oscillators is described. ANP3 and PSpice simulations including an eigenvalue study of the linearized Jacobian are presented together with a hardware implementation. The circuit contains two inductors with series resistance, two ideal...
Information cloning of harmonic oscillator coherent states
Indian Academy of Sciences (India)
We show that in the case of unknown harmonic oscillator coherent statesit is possible to achieve what we call perfect information cloning. By this we mean that it is still possible to make arbitrary number of copies of a state which has exactly the same information content as the original unknown coherent state. By making use ...
Collective excitations of harmonically trapped ideal gases
Van Schaeybroeck, B.; Lazarides, A.
2009-01-01
We theoretically study the collective excitations of an ideal gas confined in an isotropic harmonic trap. We give an exact solution to the Boltzmann-Vlasov equation; as expected for a single-component system, the associated mode frequencies are integer multiples of the trapping frequency. We show
Optical second harmonic generation from Wannier excitons
DEFF Research Database (Denmark)
Pedersen, Thomas Garm; Cornean, Horia
2007-01-01
, a simplified three-band Wannier exciton model of cubic semiconductors is applied and a closed form expression for the complex second harmonic response function including broadening is derived. Our calculated spectra are found to be in excellent agreement with the measured response near the band edge...
Harmonic Scalpel versus Monopolar Electrocauterization in Cholecystectomy.
Liao, Guanqun; Wen, Shunqian; Xie, Xueyi; Wu, Qing
2016-01-01
Laparoscopic cholecystectomy (LC) using surgical electrocautery is considered to be the gold standard procedure for the treatment of uncomplicated cholecystitis and cholelithiasis. The objective of the current study was to evaluate the effectiveness and safety of the Harmonic scalpel, an advanced laparoscopic technique associated with less thermal damage in LC, when compared to electrocautery. From October 2010 through June 2013, a total of 198 patients were randomly allocated to LC with a Harmonic scalpel (experimental group, 117 patients) or conventional monopolar electrocautery (control group, 81 patients). The main outcome measures were operative time, blood loss, conversion to laparotomy, postoperative hospital stay, post-LC pain, and cost effectiveness. The 2 groups were comparable with respect to baseline patient characteristics. When compared to conventional monopolar electrocautery, there were no significant reductions in the operative time, bleeding, frequency of conversion to laparotomy, and duration of postoperative recovery with the Harmonic scalpel (P > .05 for all). Laparoscopic cholecystectomy using conventional monopolar electrocautery is as effective and safe as that with the Harmonic scalpel, for treating uncomplicated cholecystitis and cholelithiasis.
Virial expansion coefficients in the harmonic approximation
DEFF Research Database (Denmark)
R. Armstrong, J.; Zinner, Nikolaj Thomas; V. Fedorov, D.
2012-01-01
The virial expansion method is applied within a harmonic approximation to an interacting N-body system of identical fermions. We compute the canonical partition functions for two and three particles to get the two lowest orders in the expansion. The energy spectrum is carefully interpolated...
Shedding new light on Gaussian harmonic analysis
Teuwen, J.J.B.
2016-01-01
This dissertation consists out of two rather disjoint parts. One part concerns some results on Gaussian harmonic analysis and the other on an optimization problem in optics. In the first part we study the Ornstein–Uhlenbeck process with respect to the Gaussian measure. We focus on two areas. One is
Sobolev spaces associated to the harmonic oscillator
Indian Academy of Sciences (India)
2Departamento de Matemática, Facultad de Ciencias, Universidad Autónoma de. Madrid, Spain. E-mail: bbongio@math.unl.edu.ar; joseluis.torrea@uam.es. MS received 27 September 2005. Abstract. We define the Hermite–Sobolev spaces naturally associated to the harmonic oscillator H = − + |x|2. Structural properties ...
Thirring model partition functions and harmonic differentials
Freedman, D. Z.; Pilch, K.
1988-10-01
The partition function of the Thirring model on a Riemann surface is calculated using the representation of the model as a fermion interacting with an auxiliary vector potential. The Hodge decomposition of the potential is used and the integral over the harmonic forms is shown to reproduce exactly the soliton sum in the bosonic version of the theory.
Fenestration system energy performance research, implementation, and international harmonization
Energy Technology Data Exchange (ETDEWEB)
McGowan, Raymond F [National Fenestration Rating Council, Greenbelt, MD (United States)
2014-12-23
The research conducted by the NFRC and its contractors adds significantly to the understanding of several areas of investigation. NFRC enables manufacturers to rate fenestration energy performance to comply with building energy codes, participate in ENERGY STAR, and compete fairly. NFRC continuously seeks to improve its ratings and also seeks to simplify the rating process. Several research projects investigated rating improvement potential such as • Complex Product VT Rating Research • Window 6 and Therm 6 Validation Research Project • Complex Product VT Rating Research Conclusions from these research projects led to important changes and increased confidence in the existing NFRC rating process. Conclusions from the Window 6/Therm 6 project will enable window manufacturers to rate an expanded array of products and improve existing ratings. Some research lead to an improved new rating method called the Component Modeling Approach. A primary goal of the CMA was a simplification of the commercial energy rating process to increase participation and make the commercial industry more competitive and code compliant. The project below contributed towards CMA development: • Component Modeling Approach Condensation Resistance Research NFRC continues to implement the Component Modeling Approach program. The program includes the CMA software tool, CMAST, and several procedural documents to govern the certification process. This significant accomplishment was a response the commercial fenestration industry’s need for a simplification of the present NFRC energy rating method (named site built). To date, most commercial fenestration is self-rated by a variety of techniques. The CMA enables commercial fenestration manufacturers to rate according to the NFRC 100/200 as most commercial energy codes require. International Harmonization NFRC achieved significant international harmonization success by continuing its licensing agreements with the Australian Fenestration
Technical notes. Spherical harmonics approximations of neutron transport
Energy Technology Data Exchange (ETDEWEB)
Demeny, A.; Dede, K.M.; Erdei, K.
1976-12-01
A double-range spherical harmonics approximation obtained by expanding the angular flux separately in the two regions combined with the conventional single-range spherical harmonics is found to give superior description of neutron transport.
Voltage harmonic elimination with RLC based interface smoothing filter
Chandrasekaran, K.; Ramachandaramurthy, V. K.
2015-04-01
A method is proposed for designing a Dynamic Voltage Restorer (DVR) with RLC interface smoothing filter. The RLC filter connected between the IGBT based Voltage Source Inverter (VSI) is attempted to eliminate voltage harmonics in the busbar voltage and switching harmonics from VSI by producing a PWM controlled harmonic voltage. In this method, the DVR or series active filter produces PWM voltage that cancels the existing harmonic voltage due to any harmonic voltage source. The proposed method is valid for any distorted busbar voltage. The operating VSI handles no active power but only harmonic power. The DVR is able to suppress the lower order switching harmonics generated by the IGBT based VSI. Good dynamic and transient results obtained. The Total Harmonic Distortion (THD) is minimized to zero at the sensitive load end. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of RLC filter. Simulated results are presented.
Hail, Procrustes! Harmonized accounting standards as a Procrustean bed
Stecher, J.; Suijs, J.P.M.
2012-01-01
This article finds that the use of a harmonized accounting standard, such as the International Financial Reporting Standards, increases the information available to markets only if institutional differences across countries using the harmonized standard are insignificant. In all other cases,
Sequence Domain Harmonic Modeling of Type-IV Wind Turbines
DEFF Research Database (Denmark)
Guest, Emerson; Jensen, Kim Høj; Rasmussen, Tonny Wederberg
2017-01-01
A sequence domain (SD) harmonic model of a gridconnected voltage-source converter is developed for decoupling converter generated voltage harmonics from voltage harmonics in the external grid. The modeling procedure includes a derivation of the baseband frequency response for regular......-sampled pulsewidth modulation and an analysis of converter generated voltage harmonics due to compensated dead-time. The decoupling capabilities of the proposed the SD harmonic model are verified through a power quality (PQ) assessment of a 3MW Type-IV wind turbine. The assessment shows that the magnitude and phase...... of low-order odd converter generated voltage harmonics are dependent on the converter operating point and the phase of the fundamental component of converter current respectively. The SD harmonic model can be used to make PQ assessments of Type-IV wind turbines or incorporated into harmonic load flows...
The evolution of harmonic Indian musical drums: A mathematical perspective
Gaudet, Samuel; Gauthier, Claude; Léger, Sophie
2006-03-01
We explain using mathematics how harmonic musical drums were discovered by Indian artisans and musicians more than 2000 years ago. To this end, we introduce a harmonic error function which measures the quality of the harmonic relationship and degeneracy of the first modes of vibration of a centrally symmetric loaded membrane. We explain that although the tabla configuration found by the ancient Indians is the most natural one, other configurations exist and some are harmonically superior to the classical one.
APF for harmonic voltage resonance suppression in distribution system
DEFF Research Database (Denmark)
Sun, Xiaofeng; Zeng, Jian; Chen, Zhe
2010-01-01
Traditional active power filter (APF) can prevent harmonic current from injecting into power system, but can not damp harmonic propagation in distribution system whereas voltage detection can do. This paper proposes a compound control method of APF based on detection of load current and harmonic...
Harmonics mitigation on industrial loads using series and parallel ...
African Journals Online (AJOL)
This work compared the use of series and parallel resonant harmonic filters in suppressing harmonics using Simulink model of the power system of NICHEMTEX, a Textile industry in Nigeria as a case study. Mathematical analysis representing current harmonics distributions on industrials loads with and without capacitor ...
High-order harmonic generation from eld-distorted orbitals
DEFF Research Database (Denmark)
Spiewanowski, Maciek; Etches, Adam; Madsen, Lars Bojer
We investigate the eect on high-order harmonic generation of the distortion of molecular orbitals by the driving laser eld. Calculations for high-order harmonic generation including orbital distortion are performed for N2 (high polarizability). Our results allow us to suggest that field...... of the minimum in the high-order harmonic spectra. This is in agreement with experiment....
On the harmonic starlike functions with respect to symmetric ...
African Journals Online (AJOL)
In the present paper, we introduce the notions of functions harmonic starlike with respect to symmetric, conjugate and symmetric conjugate points. Such results as coefficient inequalities and structural formulae for these function classes are proved. Keywords: Harmonic functions, harmonic starlike functions, symmetric points, ...
Twenty-Four Tuba Harmonics Using a Single Pipe Length
Holmes, Bud; Ruiz, Michael J.
2017-01-01
Harmonics arise naturally from the resonances in strings and pipes. A video demonstration (Ruiz 2016 "YouTube: Tuba Harmonics" (https://youtu.be/souhEzOP9c4)) is provided where a tubist (coauthor Holmes) produces a phenomenal 24 harmonics using a single tuba pipe length by controlling the buzz of his lips. The frequencies of the…
Harmonic Damping in DG-Penetrated Distribution Network
DEFF Research Database (Denmark)
Lu, Jinghang; Savaghebi, Mehdi; Guerrero, Josep M.
2016-01-01
Grid background harmonics may be amplified, propagate through a long distribution feeder and even lead to power system instability. In this paper, harmonic propagation issue is investigated and mitigation of the harmonics is analyzed by using transmission line theory which has already been applie...
Harmonic calculation software for industrial applications with ASDs
DEFF Research Database (Denmark)
Blaabjerg, Frede; Asiminoaei, Lucian; Hansen, Steffan
2007-01-01
This article describes the evaluation of new harmonic calculation software. By using a combination of a prestored database and new interpolation techniques the software can provide the harmonic data on real applications of a very fast speed. The harmonic results obtained with this software have a...
Transient state work fluctuation theorem for a classical harmonic ...
Indian Academy of Sciences (India)
theorem for a classical harmonic oscillator coupled linearly to a harmonic bath. Because of the coupling to the bath, the system becomes dissipative. We start from a Hamiltonian description for the system plus the harmonic heat bath and then the system is driven by an external agent for a time period of τ for a series. 666.
Harmonic Function of Poincare Cone Condition In Solving Dirichlet ...
African Journals Online (AJOL)
... the dirichlet problem and maximum principle where we conclude that the application of sums , differences and scalar multiples of harmonic functions are again harmonic. Keywords: Harmonic, maximum principles, Vector space, Poincare cone, Holder condition. Journal of the Nigerian Association of Mathematical Physics, ...
Harmonic Calculation Software for Industrial Applications with Adjustable Speed Drives
DEFF Research Database (Denmark)
Asiminoaei, Lucian; Hansen, S.; Blaabjerg, Frede
2005-01-01
This paper describes the evaluation of a new harmonic software. By using a combination of a pre-stored database and new interpolation techniques the software can very fast provide the harmonic data on real applications. The harmonic results obtained with this software have acceptable precision even...
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe
2012-01-01
at the dominant harmonic frequencies. Thus, the harmonic voltage drop on the grid-side inductance and the harmonic resonances throughout a distribution feeder with multiple shunt-connected capacitors can be effectively attenuated. Simulation and laboratory test results validate the performance of the proposed......This paper proposes a harmonic impedance synthesis technique for voltage-controlled distributed generation inverters in order to damp harmonic voltage distortion on a distribution network. The approach employs a multiloop control scheme, where a selective harmonic load current feedforward loop...... based on the bandpass filter is developed, in addition to the inner inductor current and the outer capacitor voltage control loops. Together with the use of multiple resonant integrators in the voltage control loop, the negative harmonic inductances and positive harmonic resistances are synthesized...
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe
2012-01-01
harmonic frequencies. Thus, the harmonic voltage drop and harmonic resonances throughout a distribution line with multiple shunt-connected capacitors can be effectively attenuated. Simulation and laboratory test results are shown to verify the performance of the proposed control method.......This paper proposes a harmonic impedance synthesis technique for voltage-controlled distributed generation inverter in order to damp harmonic voltage distortion on a distribution network. The approach employs a multiloop control scheme, where a selective load harmonic current feedforward loop based...... on band-pass filter is developed in addition to the inner inductor current and the outer capacitor voltage control loops. Together with the use of multiple resonant integrators in the voltage control loop, the negative harmonic inductances and positive harmonic resistances are synthesized at dominant...
DEFF Research Database (Denmark)
Wiechowski, Wojciech Tomasz; Lykkegaard, Jan; Bak, Claus Leth
2007-01-01
In this paper two methods of validation of transmission network harmonic models are introduced. The methods were developed as a result of the work presented in [1]. The first method allows calculating the transfer harmonic impedance between two nodes of a network. Switching a linear, series network...... are used for calculation of the transfer harmonic impedance between the nodes. The determined transfer harmonic impedance can be used to validate a computer model of the network. The second method is an extension of the fist one. It allows switching a series element that contains a shunt branch...... component that links the nodes causes a variation of the background harmonic voltage distortion at the nodes. Harmonic current in the series element is measured together with the harmonic voltages at both nodes, before and after the switching. Obtained incremental values of harmonic voltages and the current...
Physics of tissue harmonic imaging by ultrasound
Jing, Yuan
Tissue Harmonic Imaging (THI) is an imaging modality that is currently deployed on diagnostic ultrasound scanners. In THI the amplitude of the ultrasonic pulse that is used to probe the tissue is large enough that the pulse undergoes nonlinear distortion as it propagates into the tissue. One result of the distortion is that as the pulse propagates energy is shifted from the fundamental frequency of the source pulse into its higher harmonics. These harmonics will scatter off objects in the tissue and images formed from the scattered higher harmonics are considered to have superior quality to the images formed from the fundamental frequency. Processes that have been suggested as possibly responsible for the improved imaging in THI include: (1) reduced sensitivity to reverberation, (2) reduced sensitivity to aberration, and (3) reduction in side lobes. By using a combination of controlled experiments and numerical simulations, these three reasons have been investigated. A single element transducer and a clinical ultrasound scanner with a phased array transducer were used to image a commercial tissue-mimicking phantom with calibrated targets. The higher image quality achieved with THI was quantified in terms of spatial resolution and "clutter" signals. A three-dimensional model of the forward propagation of nonlinear sound beams in media with arbitrary spatial properties (a generalized KZK equation) was developed. A time-domain code for solving the KZK equation was validated with measurements of the acoustic field generated by the single element transducer and the phased array transducer. The code was used to investigate the impact of aberration using tissue-like media with three-dimensional variations in all acoustic properties. The three-dimensional maps of tissue properties were derived from the datasets available through the Visible Female project. The experiments and simulations demonstrated that second harmonic imaging (1) suffers less clutter associated with
DEFF Research Database (Denmark)
Kusumastuti, Sasmita; Derks, Marloes G. M.; Tellier, Siri
2016-01-01
on the objective measurements as determined by researchers. Subsequent sub-clustering analysis pointed to different domains of functioning and various ways of assessment. CONCLUSION: In the current literature two mutually exclusive concepts of successful ageing are circulating that depend on whether the individual......BACKGROUND: Ageing is accompanied by an increased risk of disease and a loss of functioning on several bodily and mental domains and some argue that maintaining health and functioning is essential for a successful old age. Paradoxically, studies have shown that overall wellbeing follows...... a curvilinear pattern with the lowest point at middle age but increases thereafter up to very old age. OBJECTIVE: To shed further light on this paradox, we reviewed the existing literature on how scholars define successful ageing and how they weigh the contribution of health and functioning to define success...
Third Harmonic Mechanism in Complex Plasmonic Fano Structures.
Metzger, Bernd; Schumacher, Thorsten; Hentschel, Mario; Lippitz, Markus; Giessen, Harald
2014-06-18
We perform third harmonic spectroscopy of dolmen-type nanostructures, which exhibit plasmonic Fano resonances in the near-infrared. Strong third harmonic emission is predominantly radiated close to the low energy peak of the Fano resonance. Furthermore, we find that the third harmonic polarization of the subradiant mode interferes destructively and diminishes the nonlinear signal in the far-field. By comparing the experimental third harmonic spectra with finite element simulations and an anharmonic oscillator model, we find strong indications that the source of the third harmonic is the optical nonlinearity of the bare gold enhanced by the resonant plasmonic polarization.
Addition theorems for spin spherical harmonics: II. Results
Energy Technology Data Exchange (ETDEWEB)
Bouzas, Antonio O, E-mail: abouzas@mda.cinvestav.mx [Departamento de Fisica Aplicada, CINVESTAV-IPN, Carretera Antigua a Progreso Km. 6, Apdo. Postal 73 ' Cordemex' , Merida 97310, Yucatan (Mexico)
2011-04-22
Based on the results of part I (2011 J. Phys. A: Math. Theor. 44 165301), we obtain the general form of the addition theorem for spin spherical harmonics and give explicit results in the cases involving one spin-s' and one spin-s spherical harmonics with s', s = 1/2, 1, 3/2, and |s' - s| = 0, 1. We also obtain a fully general addition theorem for one scalar and one tensor spherical harmonic of arbitrary rank. A variety of bilocal sums of ordinary and spin spherical harmonics are given in explicit form, including a general explicit expression for bilocal spherical harmonics.
Kaushik, A; Saini, Ks; Anil, B; Rambabu, S
2010-01-01
Medical device sector is one of the most complex and challenging business segments of the healthcare industry with close collaboration between science and engineering. Despite the fact that Asia has 60% of the world population providing large market potential, Asian healthcare expenditure constitutes only 15% of the global healthcare expenditure. The accelerated ageing population and increasing prevalence of chronic disease are the key drivers that contribute toward the increase in the total healthcare expenditure on medical devices in the region. Several policies clearly showed the eagerness of the government to provide better healthcare infrastructure with better medical devices and facilities. The fundamental objective of the regulatory harmonization is to improve the efficiency of national economies and their ability to adopt to change and remain competitive. After the era of liberalization and globalization, the desires of developing economies is to ensure safety and performance of the product brought to their markets and for this harmonized regulation is an important tool for strengthening the same. If we talk about the industry need, then this approach will eliminate redundant requirements that do not contribute to safety and effectiveness. In addition, Asia is diverse in many respects and with it come the various challenges to harmonizing the regulation which includes diversity in culture, politics, economy, historical issues, etc. If, by any reason, the regulation of medical devices is not harmonized and consequently, the harmonized regulation is not adopted, then it leads to serious concerns like delayed or absent access to innovative technology, continued rise in the cost of medical therapies, etc. So this issue is written to attract all stakeholders to move toward the concept of harmonization, keeping in mind their need, challenges, and risks of not harmonizing the regulation as well.
Harmonics in a Wind Power Plant: Preprint
Energy Technology Data Exchange (ETDEWEB)
Preciado, V.; Madrigal, M.; Muljadi, E.; Gevorgian, V.
2015-04-02
Wind power generation has been growing at a very fast pace for the past decade, and its influence and impact on the electric power grid is significant. As in a conventional power plant, a wind power plant (WPP) must ensure that the quality of the power being delivered to the grid is excellent. At the same time, the wind turbine should be able to operate immune to small disturbances coming from the grid. Harmonics are one of the more common power quality issues presented by large WPPs because of the high switching frequency of the power converters and the possible nonlinear behavior from electric machines (generator, transformer, reactors) within a power plant. This paper presents a summary of the most important issues related to harmonics in WPPs and discusses practical experiences with actual Type 1 and Type 3 wind turbines in two WPPs.
Spatial mode discrimination using second harmonic generation
DEFF Research Database (Denmark)
Delaubert, Vincent; Lassen, Mikael Østergaard; Pulford, David
2007-01-01
-Kleinmann analysis, taking into account the full description of the multi-mode field inside the nonlinear crystal in a type I phase-maching condition. The good agreement between experiments and theory shows that the effect is well understood and that we have reliable models required for the design of novel photonics......Second harmonic generation can be used as a technique for controlling the spatial mode structure of optical beams. We demonstrate experimentally the generation of higher order spatial modes, and that it is possible to use nonlinear phase matching as a predictable and robust technique...... for the conversion of transverse electric modes of the second harmonic output. For a given TEMn0 pump mode the output mode can be altered continuously by adjusting the laser wavelength, the focusing of the pump or the temperature of the nonlinear medium. We make quantitative comparisons with a generalized Boyd...
Harmonic Resonances in Wind Power Plants
DEFF Research Database (Denmark)
Fernandez, Francisco Daniel Freijedo; Chaudhary, Sanjay; Teodorescu, Remus
2015-01-01
This work reviews the state-of-the-art in the field of harmonic resonance problems in Wind Power Plants (WPPs). Firstly, a generic WPP is modeled according to the equivalent circuits of its passive and active components. Main focus is put on modeling active components, i.e. the ones based on power...... converters. Subsequently, pros and cons of frequency and time domain analysis methods are outlined. The next sections are devoted to mitigation methods implemented in the power electronics converters. From the wind turbine perspective, different techniques to enhance the robustness of the controller...... are analyzed. Subsequently, the suitability for active damping of harmonics using STATCOM devices is assessed, with focus both on control techniques and power converter technologies....
Unitary representations and harmonic analysis an introduction
Sugiura, M
1990-01-01
The principal aim of this book is to give an introduction to harmonic analysis and the theory of unitary representations of Lie groups. The second edition has been brought up to date with a number of textual changes in each of the five chapters, a new appendix on Fatou''s theorem has been added in connection with the limits of discrete series, and the bibliography has been tripled in length.
A Passive Harmonic Tag for Humidity Sensing
Antonio Lazaro; Ramon Villarino; David Girbau
2014-01-01
This paper describes a passive harmonic tag for radio frequency identification (RFID) and wireless sensor applications. The tag uses a dual polarized UHF patch antenna as an input antenna. One of the outputs is connected to a frequency doubler, which consists of a Schottky diode with its output connected to a patch tuned at twice the input frequency. The other output of the input antenna feeds a DC power harvested converter that drives an oscillator which modulates its output signal by contro...
Harmonics optical biopsy of human skin
Tai, Shih-Peng; Tsai, Tsung-Han; Chu, Shi-Wei; Lee, Wen-Jeng; Liao, Yi-Hua; Huang, Hsin-Yi; Sun, Chi-Kuang
2005-04-01
Traditional biopsy requires the removal, fixation, and staining of tissues from the human body. Its procedure is invasive and painful. Therefore, a novel method of optical biopsy is desired which can perform in vivo examination and is noninvasive, highly penetrative, with no energy deposition and damage, without invasive pharmaceutical injection, and with three-dimensional (3D) imaging capability and sub-micron spatial resolution. Two-photon fluorescence microscopy (TPFM) is previously applied for biopsy of skin due to its high lateral resolution, low out-of-focus damage, and intrinsic 3D section capability. However, for future clinical applications without surgery, current 700-850 nm based laser scanning technology still presents several limitations including low penetration depth, in-focus cell damages, multi-photon phototoxicity due to high optical intensity in the 800 nm wavelength region, and toxicity if exogenous fluorescence markers were required. Here we demonstrate a novel noninvasive optical biopsy method called harmonics optical biopsy (HOB), which combines both second harmonic generation imaging and third harmonic generation imaging. Due to virtual transition nature of harmonic generations and based on light sources with an optical wavelength located around the biological penetration window (~1300nm), our HOB can serve as a truly non-invasive biopsy tool with sub-micron three-dimensional spatial resolution without any energy deposition and exogenous contrast agents. From preliminary experiment result, our HOB can reconstruct 3D cellular and subcellular images from skin surface through dermis. Besides, by utilizing backward propagating detection geometry, we will show that this technique is ideal for non-invasive clinical biopsy of human skin diseases and even useful for the early diagnosis of skin cancer symptom such as the angiogenesis.
Unlocking higher harmonics in atomic force microscopy with gentle interactions
Directory of Open Access Journals (Sweden)
Sergio Santos
2014-03-01
Full Text Available In dynamic atomic force microscopy, nanoscale properties are encoded in the higher harmonics. Nevertheless, when gentle interactions and minimal invasiveness are required, these harmonics are typically undetectable. Here, we propose to externally drive an arbitrary number of exact higher harmonics above the noise level. In this way, multiple contrast channels that are sensitive to compositional variations are made accessible. Numerical integration of the equation of motion shows that the external introduction of exact harmonic frequencies does not compromise the fundamental frequency. Thermal fluctuations are also considered within the detection bandwidth of interest and discussed in terms of higher-harmonic phase contrast in the presence and absence of an external excitation of higher harmonics. Higher harmonic phase shifts further provide the means to directly decouple the true topography from that induced by compositional heterogeneity.
The Hyperspherical Functions of a Derivative
Directory of Open Access Journals (Sweden)
Nenad Cakic
2010-01-01
Full Text Available We present the results of theoretical research of the generalized hypersherical function (HS by generalizing two known functions related to the sphere hypersurface and hypervolume and the recurrent relation between them. By introducing two-dimensional degrees of freedom k and n (and the third, radius r, we develop the derivative functions for all three arguments and the possibilities of their use. The symbolical evolution, numerical experiment, and graphical presentation of functions are realized using the Mathcad Professional and Mathematica softwares.
Harmonics of circadian gene transcription in mammals.
Directory of Open Access Journals (Sweden)
Michael E Hughes
2009-04-01
Full Text Available The circadian clock is a molecular and cellular oscillator found in most mammalian tissues that regulates rhythmic physiology and behavior. Numerous investigations have addressed the contribution of circadian rhythmicity to cellular, organ, and organismal physiology. We recently developed a method to look at transcriptional oscillations with unprecedented precision and accuracy using high-density time sampling. Here, we report a comparison of oscillating transcription from mouse liver, NIH3T3, and U2OS cells. Several surprising observations resulted from this study, including a 100-fold difference in the number of cycling transcripts in autonomous cellular models of the oscillator versus tissues harvested from intact mice. Strikingly, we found two clusters of genes that cycle at the second and third harmonic of circadian rhythmicity in liver, but not cultured cells. Validation experiments show that 12-hour oscillatory transcripts occur in several other peripheral tissues as well including heart, kidney, and lungs. These harmonics are lost ex vivo, as well as under restricted feeding conditions. Taken in sum, these studies illustrate the importance of time sampling with respect to multiple testing, suggest caution in use of autonomous cellular models to study clock output, and demonstrate the existence of harmonics of circadian gene expression in the mouse.
A Passive Harmonic Tag for Humidity Sensing
Directory of Open Access Journals (Sweden)
Antonio Lazaro
2014-01-01
Full Text Available This paper describes a passive harmonic tag for radio frequency identification (RFID and wireless sensor applications. The tag uses a dual polarized UHF patch antenna as an input antenna. One of the outputs is connected to a frequency doubler, which consists of a Schottky diode with its output connected to a patch tuned at twice the input frequency. The other output of the input antenna feeds a DC power harvested converter that drives an oscillator which modulates its output signal by controlling the bias point of the Schottky diode. The antenna’s output is also used as a humidity sensor. To achieve this, the antenna is loaded with an interdigital capacitor with humidity-dependent capacitance. The antenna is consequently detuned when humidity varies, and therefore the second harmonic power is received. The tag is manufactured using standard fiberglass substrate. The basic theory of harmonic tag operation is described and compared with the standard backscattering approach. Experimental results with a proof of concept using commercial components are presented.
THE HARMONIC SCALPEL APPLICATION IN THYROID SURGERY
Directory of Open Access Journals (Sweden)
Rumen Nenkov
2013-06-01
Full Text Available New, modern devices for tissue resection have been introduced in the surgical treatment of thyroid diseases recent years.Aim: To present our experience with the use of the harmonic scalpel in thyroid surgery.Patients and methods: For the period 2008 - 2011, 1398 patients (6 to 74 years old with various thyroid deseases were operated on in our clinic. The resection was performed through a classic Kocher,s collar incision in 583 patients, using minimally ivasive open access in 641 patients and with video-assisted technique in 174 patients. In all patients a harmonic scalpel device (Ethicon Endosurgery Care Inc has been used. The length of surgical incision, use of haemostatic instruments and ligatures, extent of resection, need of draining, operative time, intra- and postoperative complications, length of postoperative hospital stay have been examined .Results: The volume of resection ranged from istmusectomy to total thyroidectomy. During all operation haemostatic instruments and ligatures have not been used. Lack of bleeding and shortend operating time - up to 45% were found. The use of draining is significantly reduced, regardless of the extent of resection. There was no increase in the incidence of intra- and postoperative complications.Тhe postoperative stay was significantly reduced.Conclusion: In our opinion, the introduction in use of the harmonic scalpel changes the face of modern thyroid surgery providing reliable hemostasis and shortening the operating time significantly.
EUROPEAN HARMONIZATION OF CONSOLIDATED FINANCIAL STATEMENTS REGULATIONS?
Directory of Open Access Journals (Sweden)
Cirstea Andreea
2012-07-01
Full Text Available The purpose of this paper is to analyze the degree of formal accounting harmonization within the European Union with respect to the EC Regulation No. 1606/2002 adopted by the European Parliament and European Council on the 19th of July 2002, which regulates the application of IAS/IFRS regarding the financial reporting of listed European companies. The conclusions of the paper were drawn after the completion of a thorough analysis performed by using correlation and/ or association coefficients, namely: the JaccardÃ¢â‚¬â„¢s Correlation Coefficients, Rogers and Tanimoto Coefficient, Lance and Williams Coefficient and Binary Euclidian Distance Coefficient. The results lead us to conclude that although our first hypothesis is verified, the degree of harmonization between the accounting systems of EU Member States could be truly quantified only through an analysis of the material accounting harmonization, more precisely by analyzing the way the companies put into practice the requirements imposed through the EC Regulation No. 1606/2002.
Chang, Chi-Wei; Chen, Jiang-Ming; Wang, Wei-Kung
2015-01-01
This study was aimed to establish a standard protocol and to quantitatively assess the reliability of harmonic analysis of the radial pulse wave measured by a harmonic wave analyzer (TD01C system). Both intraobserver and interobserver assessments were conducted to investigate whether the values of harmonics are stable in successive measurements. An intraclass correlation coefficient (ICC) and a Bland-Altman plot were used for this purpose. For the reliability assessments of the intraobserver and the interobserver, 22 subjects (mean age 45 ± 14 years; 14 males and 8 females) were enrolled. The first eleven harmonics of the radial pulse wave presented excellent repeatability ([Formula: see text] and [Formula: see text]) for the intraobserver assessment and high reproducibility (ICCs range from 0.83 to 0.96 and [Formula: see text]) for the interobserver assessment. The Bland-Altman plot indicated that more than 90% of harmonic values fell within two standard deviations of the mean difference. Thus, we concluded that the harmonic analysis of the radial pulse wave using the TD01C system is a feasible and reliable method to assess a hemodynamic characteristic in clinical trial.
Harmonic balance approach to the periodic solutions of the (an)harmonic relativistic oscillator
Energy Technology Data Exchange (ETDEWEB)
Belendez, Augusto [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es; Pascual, Carolina [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)
2007-11-19
The first-order harmonic balance method via the first Fourier coefficient is used to construct two approximate frequency-amplitude relations for the relativistic oscillator for which the nonlinearity (anharmonicity) is a relativistic effect due to the time line dilation along the world line. Making a change of variable, a new nonlinear differential equation is obtained and two procedures are used to approximately solve this differential equation. In the first the differential equation is rewritten in a form that does not contain a square-root expression, while in the second the differential equation is solved directly. The approximate frequency obtained using the second procedure is more accurate than the frequency obtained with the first due to the fact that, in the second procedure, application of the harmonic balance method produces an infinite set of harmonics, while in the first procedure only two harmonics are produced. Both approximate frequencies are valid for the complete range of oscillation amplitudes, and excellent agreement of the approximate frequencies with the exact one are demonstrated and discussed. The discrepancy between the first-order approximate frequency obtained by means of the second procedure and the exact frequency never exceeds 1.6%. We also obtained the approximate frequency by applying the second-order harmonic balance method and in this case the relative error is as low 0.31% for all the range of values of amplitude of oscillation A.
DEFF Research Database (Denmark)
Bülow, Morten Hillgaard; Söderqvist, Thomas
2014-01-01
Since the late 1980s, the concept of ‘ successful ageing’ has set the frame for discourse about contemporary ageing research. Through an analysis of the reception to John W. Rowe and Robert L. Kahn's launch of the concept of ‘ successful ageing’ in 1987, this article maps out the important themes...... strategies; and the importance of individual, societal and scientific conceptualisations and understandings of ageing. By presenting an account of the recent historical uses, interpretations and critiques of the concept, the article unfolds the practical and normative complexities of ‘ successful ageing’....... and discussions that have emerged from the interdisciplinary field of ageing research. These include an emphasis on interdisciplinarity; the interaction between biology, psycho-social contexts and lifestyle choices; the experiences of elderly people; life-course perspectives; optimisation and prevention...
DEFF Research Database (Denmark)
Vaio, Gianfranco Di; Waldenström, Daniel; Weisdorf, Jacob Louis
2012-01-01
This study examines the determinants of citation success among authors who have recently published their work in economic history journals. Besides offering clues about how to improve one's scientific impact, our citation analysis also sheds light on the state of the field of economic history....... Consistent with our expectations, we find that full professors, authors appointed at economics and history departments, and authors working in Anglo-Saxon and German countries are more likely to receive citations than other scholars. Long and co-authored articles are also a factor for citation success. We...... find similar patterns when assessing the same authors' citation success in economics journals. As a novel feature, we demonstrate that the diffusion of research — publication of working papers, as well as conference and workshop presentations — has a first-order positive impact on the citation rate....
DEFF Research Database (Denmark)
Di Vaio, Gianfranco; Waldenström, Daniel; Weisdorf, Jacob Louis
This study analyses determinants of citation success among authors publishing in economic history journals. Bibliometric features, like article length and number of authors, are positively correlated with the citation rate up to a certain point. Remarkably, publishing in top-ranked journals hardly...... affects citations. In regard to author-specific characteristics, male authors, full professors and authors working economics or history departments, and authors employed in Anglo-Saxon countries, are more likely to get cited than others. As a ‘shortcut' to citation success, we find that research diffusion...
In vivo optical virtual biopsy of human oral cavity with harmonic generation microscopy
Tsai, M.-R.; Chen, S.-Y.; Shieh, D.-B.; Lou, P.-J.; Sun, C.-K.
2010-02-01
Oral cancer ranked number four in both cancer incident and mortality in Taiwanese male population. Early disease diagnosis and staging is essential for its clinical success. However, most patients were diagnosed in their late disease stage as ideal prescreening procedures are yet to be developed especially when dealing with a large surface of precancerous lesions. Therefore, how to detect and confirm the diagnosis of these early stage lesions are of significant clinical value. Harmonic generation process naturally occurred in biological molecules and requires no energy deposition to the target molecule. Thus harmonic generation microscopy (HGM) could potentially serve as a noninvasive tool for screening of human oral mucosal diseases. The in vivo optical biopsy of human oral cavity with HGM could be achieved with high spatial resolution to resolve dynamic physiological process in the oral mucosal tissue with equal or superior quality but devoid of complicated physical biopsy procedures. The second harmonic generation (SHG) provide significant image contrast for biomolecules with repetitive structures such as the collagen fibers in the lamina propria and the mitotic spindles in dividing cells. The cell morphology in the epithelial layer, blood vessels and blood cells flow through the capillaries can be revealed by third harmonic generation (THG) signals. Tissue transparent technology was used to increase the optical penetration of the tissue. In conclusion, this report demonstrates the first in vivo optical virtual biopsy of human oral mucosa using HGM and revealed a promising future for its clinical application for noninvasive in vivo diseases diagnosis.
Li, Guixin; Wu, Lin; Li, King F; Chen, Shumei; Schlickriede, Christian; Xu, Zhengji; Huang, Siya; Li, Wendi; Liu, Yanjun; Pun, Edwin Y B; Zentgraf, Thomas; Cheah, Kok W; Luo, Yu; Zhang, Shuang
2017-12-13
The spin and orbital angular momentum (SAM and OAM) of light is providing a new gateway toward high capacity and robust optical communications. While the generation of light with angular momentum is well studied in linear optics, its further integration into nonlinear optical devices will open new avenues for increasing the capacity of optical communications through additional information channels at new frequencies. However, it has been challenging to manipulate the both SAM and OAM of nonlinear signals in harmonic generation processes with conventional nonlinear materials. Here, we report the generation of spin-controlled OAM of light in harmonic generations by using ultrathin photonic metasurfaces. The spin manipulation of OAM mode of harmonic waves is experimentally verified by using second harmonic generation (SHG) from gold meta-atom with 3-fold rotational symmetry. By introducing nonlinear phase singularity into the metasurface devices, we successfully generate and measure the topological charges of spin-controlled OAM mode of SHG through an on-chip metasurface interferometer. The nonlinear photonic metasurface proposed in this work not only opens new avenues for manipulating the OAM of nonlinear optical signals but also benefits the understanding of the nonlinear spin-orbit interaction of light in nanoscale devices.
Application of higher harmonic blade feathering on the OH-6A helicopter for vibration reduction
Straub, F. K.; Byrns, E. V., Jr.
1986-01-01
The design, implementation, and flight test results of higher harmonic blade feathering for vibration reduction on the OH-6A helicopter are described. The higher harmonic control (HHC) system superimposes fourth harmonic inputs upon the stationary swashplate. These inputs are transformed into 3P, 4P and 5P blade feathering angles. This results in modified blade loads and reduced fuselage vibrations. The primary elements of this adaptive vibration suppression system are: (1) acceleration transducers sensing the vibratory response of the fuselage; (2) a higher harmonic blade pitch actuator system; (3) a flightworthy microcomputer, incorporating the algorithm for reducing vibrations, and (4) a signal conditioning system, interfacing between the sensors, the microcomputer and the HHC actuators. The program consisted of three distinct phases. First, the HHC system was designed and implemented on the MDHC OH-6A helicopter. Then, the open loop, or manual controlled, flight tests were performed, and finally, the closed loop adaptive control system was tested. In 1983, one portion of the closed loop testing was performed, and in 1984, additional closed loop tests were conducted with improved software. With the HHC system engaged, the 4P pilot seat vibration levels were significantly lower than the baseline ON-6A levels. Moreover, the system did not adversely affect blade loads or helicopter performance. In conclusion, this successful proof of concept project demonstrated HHC to be a viable vibration suppression mechanism.
Performance of Magnetic-Superconductor Non-Contact Harmonic Drive for Cryogenic Space Applications
Directory of Open Access Journals (Sweden)
Jose Luis Perez-Diaz
2015-07-01
Full Text Available Harmonic drives are profusely used in aerospace mainly because of their compactness and large reduction ratio. However, their use in cryogenic environments is still a challenge. Lubrication and fatigue are non-trivial issues under these conditions. The objective of the Magnetic-Superconductor Cryogenic Non-contact Harmonic Drive (MAGDRIVE project, funded by the EU Space FP7, is to design, build, and test a new concept of MAGDRIVE. Non-contact interactions among magnets, soft magnetic materials, and superconductors are efficiently used to provide a high reduction ratio gear that smoothly and naturally operates at cryogenic environments. The limiting elements of conventional harmonic drives (teeth, flexspline, and ball bearings are substituted by contactless mechanical components (magnetic gear and superconducting magnetic bearings. The absence of contact between moving parts prevents wear, lubricants are no longer required, and the operational lifetime is greatly increased. This is the first mechanical reducer in mechanical engineering history without any contact between moving parts. In this paper, the test results of a −1:20 inverse reduction ratio MAGDRIVE prototype are reported. In these tests, successful operation at 40 K and 10−3 Pa was demonstrated for more than 1.5 million input cycles. A maximum torque of 3 N·m and an efficiency of 80% were demonstrated. The maximum tested input speed was 3000 rpm, six times the previous existing record for harmonic drives at cryogenic temperatures.
Toward Rigorous Data Harmonization in Cancer Epidemiology Research: One Approach.
Rolland, Betsy; Reid, Suzanna; Stelling, Deanna; Warnick, Greg; Thornquist, Mark; Feng, Ziding; Potter, John D
2015-12-15
Cancer epidemiologists have a long history of combining data sets in pooled analyses, often harmonizing heterogeneous data from multiple studies into 1 large data set. Although there are useful websites on data harmonization with recommendations and support, there is little research on best practices in data harmonization; each project conducts harmonization according to its own internal standards. The field would be greatly served by charting the process of data harmonization to enhance the quality of the harmonized data. Here, we describe the data harmonization process utilized at the Fred Hutchinson Cancer Research Center (Seattle, Washington) by the coordinating centers of several research projects. We describe a 6-step harmonization process, including: 1) identification of questions the harmonized data set is required to answer; 2) identification of high-level data concepts to answer those questions; 3) assessment of data availability for data concepts; 4) development of common data elements for each data concept; 5) mapping and transformation of individual data points to common data elements; and 6) quality-control procedures. Our aim here is not to claim a "correct" way of doing data harmonization but to encourage others to describe their processes in order that we can begin to create rigorous approaches. We also propose a research agenda around this issue. © The Author 2015. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Study of high-order harmonic generation from nanoparticles
Energy Technology Data Exchange (ETDEWEB)
Singhal, H; Naik, P A; Srivastava, A K; Singh, A; Chari, R; Khan, R A; Chakera, J A; Gupta, P D [Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India); Ganeev, R A, E-mail: himanshu@rrcat.gov.i [Institute of Electronics, Uzbekistan Academy of Sciences, Tashkent 100125 (Uzbekistan)
2010-01-28
An experimental study on high-order harmonic generation from the interaction of 45 fs Ti:sapphire laser pulses with preformed plasma plumes of metal nanoparticles was carried out. Highly efficient harmonic generation in the range of 9th order to 19th order was observed for Ag nanoparticles. The stability of harmonic generation was enhanced by utilizing special target fabrication techniques and through optimizing the conditions of plasma plume formation. Broadband harmonic generation was observed through the optimization of femtosecond laser intensity and through the use of spectrally broadened laser pulses. The harmonic generation was compared for various target materials (nano and bulk) and for Ag nanoparticle targets prepared from different fabrication techniques. Efficient generation of even- and odd-order harmonics was observed through the use of two-colour pulses. The observations can be explained qualitatively from symmetry breaking of high-order harmonic generation through the introduction of second harmonic pulses. The spectral broadening and shift of harmonic radiation can be understood from the self-modulation of the laser and harmonic radiation in the plasma.
Coherent harmonic production using a two-section undulator FEL
Energy Technology Data Exchange (ETDEWEB)
Jaroszynski, D.A. [Commissariat a l`Energie, Bruyeres-le-Chatel (France); Prazeres, R.; Glotin, F. [Centre Universitaire Paris-Sud (France)] [and others
1995-12-31
We present measurements and a theoretical analysis of a new method of generating harmonic radiation in a free-electron laser oscillator with a two section undulator in a single optical cavity. To produce coherent harmonic radiation the undulator is arranged so that the downstream undulator section resonance frequency matches a harmonic of the upstream undulator. Both the fundamental and the harmonic optical fields evolve in the same optical cavity and are coupled out with different extraction fractions using a hole in one of the cavity mirrors. We present measurements that show that the optical power at the second and third harmonic can be enhanced by more than an order of magnitude in this fundamental/harmonic configuration. We compare the production of harmonic radiation of a two sectioned fundamental/harmonic undulator with that produced from a FEL operating at its highest efficiency with a step-tapered undulator, where the bunching at the end of the first section is very large. We examine, the dependence of the harmonic power on the intracavity power by adjusting the optical cavity desynchronism, {delta}L. We also examine the evolution of the fundamental and harmonic powers as a function of cavity roundtrip number to evaluate the importance of the small signal gain at the harmonic. We compare our measurements with predictions of a multi-electron numerical model that follows the evolution of fundamental and harmonic power to saturation. This fundamental/harmonic mode, of operation of the FEL may have useful applications in the production of coherent X-ray and VUV radiation, a spectral range where high reflectivity optical cavity mirrors are difficult or impossible to manufacture.
Algal Supply System Design - Harmonized Version
Energy Technology Data Exchange (ETDEWEB)
Jared Abodeely; Daniel Stevens; Allison Ray; Debor
2013-03-01
The objective of this design report is to provide an assessment of current technologies used for production, dewatering, and converting microalgae cultivated in open-pond systems to biofuel. The original draft design was created in 2011 and has subsequently been brought into agreement with the DOE harmonized model. The design report extends beyond this harmonized model to discuss some of the challenges with assessing algal production systems, including the ability to (1) quickly assess alternative algal production system designs, (2) assess spatial and temporal variability, and (3) perform large-scale assessments considering multiple scenarios for thousands of potential sites. The Algae Logistics Model (ALM) was developed to address each of these limitations of current modeling efforts to enable assessment of the economic feasibility of algal production systems across the United States. The (ALM) enables (1) dynamic assessments using spatiotemporal conditions, (2) exploration of algal production system design configurations, (3) investigation of algal production system operating assumptions, and (4) trade-off assessments with technology decisions and operating assumptions. The report discusses results from the ALM, which is used to assess the baseline design determined by harmonization efforts between U.S. DOE national laboratories. Productivity and resource assessment data is provided by coupling the ALM with the Biomass Assessment Tool developed at PNNL. This high-fidelity data is dynamically passed to the ALM and used to help better understand the impacts of spatial and temporal constraints on algal production systems by providing a cost for producing extracted algal lipids annually for each potential site.
Harmonic analysis on spaces of homogeneous type
Deng, Donggao
2009-01-01
The dramatic changes that came about in analysis during the twentieth century are truly amazing. In the thirties, complex methods and Fourier series played a seminal role. After many improvements, mostly achieved by the Calderón-Zygmund school, the action today is taking place in spaces of homogeneous type. No group structure is available and the Fourier transform is missing, but a version of harmonic analysis is still available. Indeed the geometry is conducting the analysis. The authors succeed in generalizing the construction of wavelet bases to spaces of homogeneous type. However wavelet bases are replaced by frames, which in many applications serve the same purpose.
Second harmonic spectroscopy of semiconductor nanostructures
DEFF Research Database (Denmark)
Østergaard, John Erland; Yu, Ping; Bozhevolnyi, Sergey I.
1999-01-01
in highly anisotropic linear polarization properties, as studied recently in pyramide-shaped self-assembled InGaAs quantum dots, but also in second harmonic generation (SHG), which can be greatly enhanced allowing for detailed studies of such structures. SHG has contributed considerably as a technique...... to investigate solid state systems where the local inversion symmetry is broken by e.g. a surface or an interface, defect states or simply by structures so small that the bulk symmetry properties no longer are valid. Our idea is to use SHG in the configurations, where the bulk and surface contributions...
Promoting Spontaneous Second Harmonic Generation through Organogelation.
Marco, A Belén; Aparicio, Fátima; Faour, Lara; Iliopoulos, Konstantinos; Morille, Yohann; Allain, Magali; Franco, Santiago; Andreu, Raquel; Sahraoui, Bouchta; Gindre, Denis; Canevet, David; Sallé, Marc
2016-07-27
An organogelator based on the Disperse Red nonlinear optical chromophore was synthesized according to a simple and efficient three-step procedure. The supramolecular gel organization leads to xerogels which display a spontaneous second harmonic generation (SHG) response without any need for preprocessing, and this SHG activity appears to be stable over several months. These findings, based on an intrinsic structural approach, are supported by favorable intermolecular supramolecular interactions, which promote a locally non-centrosymmetric NLO-active organization. This is in sharp contrast with most materials designed for SHG purposes, which generally require the use of expensive or heavy-to-handle external techniques for managing the dipoles' alignment.
Glass devices for efficient second harmonic generation
DEFF Research Database (Denmark)
Fage-Pedersen, Jacob; Jacobsen, Rune Shim; Kristensen, Martin
2005-01-01
We show here that quasi-phase matched (QPM) planar nonlinear devices of high quality can be fabricated by means of periodic poling of the glass. The devices, used for second-harmonic generation (SHG), have accurately-controlled centre wavelengths, and the normalised conversion efficiencies...... are approximately one order of magnitude higher than what has previously been reported for periodically poled glass. In conclusion, we have demonstrated that high-quality nonlinear QPM devices can be fabricated in glass-on-silicon. The technology is easily adaptable to any desired wavelength (e.g. 1550 nm) and can...
Harmonic Spinors for Twisted Dirac Operators
Baer, C
1997-01-01
We show that for a suitable class of ``Dirac-like'' operators there holds a Gluing Theorem for connected sums. More precisely, if $M_1$ and $M_2$ are closed Riemannian manifolds of dimension $n\\ge 3$ together with such operators, then the connected sum $M_1 # M_2$ can be given a Riemannian metric such that the spectrum of its associated operator is close to the disjoint union of the spectra of the two original operators. As an application, we show that in dimension $n\\equiv 3$ mod 4 harmonic spinors for the Dirac operator of a spin,
Supersymmetry, quark confinement and the harmonic oscillator
Energy Technology Data Exchange (ETDEWEB)
Bruce, S A; Minning, P C [Department of Physics, University of Concepcion, PO Box 160C, Concepcion (Chile)
2007-12-07
We study some quantum systems described by noncanonical commutation relations formally expressed as [q-hat,p-hat] = i h-bar(I-hat+{chi}-hatH-hat{sub HO}), where H-hat{sub HO} is the associated (harmonic-oscillator-like) Hamiltonian of the system and {chi}-hat is a Hermitian (constant) operator, i.e. [H-hat{sub HO},{chi}-hat]=O-hat. In passing, we also consider a simple ({chi}-hat=O-hat canonical) model, in the framework of a relativistic Klein-Gordon-like wave equation.
Second harmonic generation in resonant optical structures
Energy Technology Data Exchange (ETDEWEB)
Eichenfield, Matt; Moore, Jeremy; Friedmann, Thomas A.; Olsson, Roy H.; Wiwi, Michael; Padilla, Camille; Douglas, James Kenneth; Hattar, Khalid Mikhiel
2018-01-09
An optical second-harmonic generator (or spontaneous parametric down-converter) includes a microresonator formed of a nonlinear optical medium. The microresonator supports at least two modes that can be phase matched at different frequencies so that light can be converted between them: A first resonant mode having substantially radial polarization and a second resonant mode having substantially vertical polarization. The first and second modes have the same radial order. The thickness of the nonlinear medium is less than one-half the pump wavelength within the medium.
Contrast-enhanced harmonic endoscopic ultrasound
DEFF Research Database (Denmark)
Săftoiu, A; Dietrich, C F; Vilmann, P
2012-01-01
Second-generation intravenous blood-pool ultrasound contrast agents are increasingly used in endoscopic ultrasound (EUS) for characterization of microvascularization, differential diagnosis of benign and malignant focal lesions, and improving staging and guidance of therapeutic procedures. Although...... contrast-enhanced harmonic EUS based on a very low mechanical index (0.08 - 0.12). Quantification techniques based on dynamic contrast-enhanced ultrasound have been recommended for perfusion imaging and monitoring of anti-angiogenic treatment, mainly based on time-intensity curve analysis. Most...
Harmonic Analysis and Active Filtering in Offshore Wind Power Plants
DEFF Research Database (Denmark)
Chaudhary, Sanjay Kumar; Freijedo Fernandez, Francisco Daniel; Guerrero, Josep M.
2015-01-01
at the point of common coupling (PCC). The resonance conditions should be avoided in all cases. This paper describes the harmonic analysis techniques applied on an OWPP network model. A method is proposed to estimate the harmonic current compensation from a shunt-connected active power filter to mitigate......Due to presence of long high voltage cable networks, and power transformers for the grid connection, the offshore wind power plants (OWPPs) are susceptible to harmonic distortion and resonances. The grid connection of OWPP should not cause the harmonic distortion beyond the permissible limits...... the harmonic voltage distortion at the PCC. Finally the harmonic distortions in the compensated and the uncompensated systems are compared to demonstrate the efficacy of the compensation....
Extraction of small boat harmonic signatures from passive sonar.
Ogden, George L; Zurk, Lisa M; Jones, Mark E; Peterson, Mary E
2011-06-01
This paper investigates the extraction of acoustic signatures from small boats using a passive sonar system. Noise radiated from a small boats consists of broadband noise and harmonically related tones that correspond to engine and propeller specifications. A signal processing method to automatically extract the harmonic structure of noise radiated from small boats is developed. The Harmonic Extraction and Analysis Tool (HEAT) estimates the instantaneous fundamental frequency of the harmonic tones, refines the fundamental frequency estimate using a Kalman filter, and automatically extracts the amplitudes of the harmonic tonals to generate a harmonic signature for the boat. Results are presented that show the HEAT algorithms ability to extract these signatures. © 2011 Acoustical Society of America
[Value of tissue harmonic imaging in biliary lithiasis].
Flunker, S; Aubé, C; Anglade, E; Vuillemin, E; Bourrée, Y; Burtin, P; Caron-Poitreau, C
2001-01-01
To define the role of harmonic imaging in the study of biliary lithiasis. We included 50 consecutive patients with suspected biliary lithiasis. Three independent observers compared results of harmonic imaging and conventional ultrasonography. This study showed a better interobserver agreement with harmonic imaging for acoustic shadow (kappa=0.87 vs 0.68) and intra-hepatic biliary stones (kappa=0.79 vs 0.49). More stones and more lithiasic gallbladders were seen with harmonic imaging (27 vs 24) and visualization of gallbladder sludge and the acoustic shadow from stones (P=0.01) was better. Ultrasound examination appears to be easier and faster and the diagnosis is more certain with harmonic imaging than with conventional ultrasonography (P=0.005). Harmonic imaging provides more information on biliary lithiasis and a more certain diagnosis.
A Harmonic Impedance Measurement System for Reduction of Harmonics in the Electricity Grid
Heskes, P.J.M.; Myrzik, J.M.A.; Kling, W.L.
2009-01-01
This paper describes the development of a Complex Harmonic Impedance Measurement system, called the CHIME-system. This system performs on-line impedance measurements in the electricity grid and will be designed for implementation in Digital Signal Processor (DSP) control systems of grid-connected
Lifetime increase using passive harmonic cavities in synchrotron light sources
Directory of Open Access Journals (Sweden)
J. M. Byrd
2001-03-01
Full Text Available Harmonic cavities have been used in storage rings to increase beam lifetime and Landau damping by lengthening the bunch. The need for lifetime increase is particularly great in the present generation of low to medium energy synchrotron light sources where the small transverse beam sizes lead to relatively short lifetimes from large-angle intrabeam (Touschek scattering. We review the beam dynamics of harmonic radio-frequency systems and discuss optimization of the beam lifetime using passive harmonic cavities.
Separation of High Order Harmonics with Fluoride Windows
Energy Technology Data Exchange (ETDEWEB)
Allison, Tom; van Tilborg, Jeroen; Wright, Travis; Hertlein, Marcus; Falcone, Roger; Belkacem, Ali
2010-08-02
The lower orders produced in high order harmonic generation can be effciently temporally separated into monochromatic pulses by propagation in a Fluoride window while still preserving their femtosecond pulse duration. We present calculations for MgF2, CaF2, and LiF windows for the third, fifth, and seventh harmonics of 800 nm. We demonstrate the use of this simple and inexpensive technique in a femtosecond pump/probe experiment using the fifth harmonic.
Harmonic Phase Responses of Radio Frequency Electronics: Wireline Test
2015-12-01
ARL-TR-7552 ● DEC 2015 US Army Research Laboratory Harmonic Phase Responses of Radio Frequency Electronics: Wireline Test by...DEC 2015 US Army Research Laboratory Harmonic Phase Responses of Radio Frequency Electronics: Wireline Test by Gregory J Mazzaro, Sean F...DD-MM-YYYY) December 2015 2. REPORT TYPE Final 3. DATES COVERED (From - To) 08/2015 4. TITLE AND SUBTITLE Harmonic Phase Responses of Radio
LED lamp modelling for harmonic studies in distribution systems
Molina, Julio; Mesas García, Juan José; Mesbahi, Nadhir; Sainz Sapera, Luis
2017-01-01
Energy saving policies have boosted the use of light emitting diode (LED) lamps in distribution networks. These lamps are non-linear loads which inject harmonic currents into the distribution system, which has led to a decrease in the system power quality. Study of the modelling of these lamps would allow the prediction of harmonic emissions into distribution systems. This study presents a frequency-domain LED lamp model for harmonic emission calculation, together with a simple estimation pro...
OPTICAL SECOND-HARMONIC GENERATION IN CRYSTALLINE AMINO ACIDS.
RIECKHOFF, K E; PETICOLAS, W L
1965-02-05
Optically active amino acids contain many highly efficient optical second-harmonic generators. When light from a ruby laser at 6943 A falls on the crystalline amino acids with sufficient intensity, the second harmonic of the light at 3471 A can be observed. Although the symmetry requirements for optical second-harmonic generation are always met by isomerically pure optically active substances, there is considerable variation in efficiency for the generation of the second harmonic, ranging from almost zero to greater than that of potassium dihydrogen phosphate, the most efficient known.
Nonlinear harmonic generation and proposed experimental verification in SASE FELs.
Energy Technology Data Exchange (ETDEWEB)
Biedron, S. G.; Freund, H. P.; Milton, S. V.
1999-08-24
Recently, a 3D, polychromatic, nonlinear simulation code was developed to study the growth of nonlinear harmonics in self-amplified spontaneous emission (SASE) free-electron lasers (FELs). The simulation was applied to the parameters for each stage of the Advanced Photon Source (APS) SASE FEL, intended for operation in the visible, UV, and short UV wavelength regimes, respectively, to study the presence of nonlinear harmonic generation. Significant nonlinear harmonic growth is seen. Here, a discussion of the code development, the APS SASE FEL, the simulations and results, and, finally, the proposed experimental procedure for verification of such nonlinear harmonic generation at the APS SASE FEL will be given.
Spectral phase distribution retrieval through coherent control of harmonic generation.
Papalazarou, E; Kovacev, M; Tzallas, P; Benis, E P; Kalpouzos, C; Tsakiris, G D; Charalambidis, D
2006-04-28
The temporal intensity distribution of the third harmonic of a Ti:sapphire laser generated in Xe gas is fully reconstructed from its spectral phase and amplitude distributions. The spectral phases are retrieved by cross correlating the fundamental laser frequency field with that of the third harmonic, in a three laser versus one harmonic photon coupling scheme. The third harmonic spectral amplitude distribution is extracted from its field autocorrelation. The measured pulse duration is found to be in agreement with that expected from lowest order perturbation theory both for unstretched and chirped pulses.
Second and third harmonic waves excited by focused Gaussian beams.
Levy, Uri; Silberberg, Yaron
2015-10-19
Harmonic generation by tightly-focused Gaussian beams is finding important applications, primarily in nonlinear microscopy. It is often naively assumed that the nonlinear signal is generated predominantly in the focal region. However, the intensity of Gaussian-excited electromagnetic harmonic waves is sensitive to the excitation geometry and to the phase matching condition, and may depend on quite an extended region of the material away from the focal plane. Here we solve analytically the amplitude integral for second harmonic and third harmonic waves and study the generated harmonic intensities vs. focal-plane position within the material. We find that maximum intensity for positive wave-vector mismatch values, for both second harmonic and third harmonic waves, is achieved when the fundamental Gaussian is focused few Rayleigh lengths beyond the front surface. Harmonic-generation theory predicts strong intensity oscillations with thickness if the material is very thin. We reproduced these intensity oscillations in glass slabs pumped at 1550nm. From the oscillations of the 517nm third-harmonic waves with slab thickness we estimate the wave-vector mismatch in a Soda-lime glass as Δk(H)= -0.249μm(-1).
Harmonic currents Compensator Grid-Connected Inverter at the Microgrid
DEFF Research Database (Denmark)
Asuhaimi Mohd Zin, A.; Naderipour, A.; Habibuddin, M.H.
2016-01-01
The main challenge associated with the grid-connected inverter in distributed generation (DG) systems is to maintain the harmonic contents in output current below the specified values and compensates for unbalanced loads even when the grid is subject to disturbances such as harmonic distortion...... loads are unbalanced and/or nonlinear and also compensate of the harmonic currents and control the active and reactive power. The main advantage and objective of this method is to effectively compensate for the harmonic currents content of the grid current and microgrid without using any compensation...
Direct harmonic voltage control strategy for shunt active power filter
DEFF Research Database (Denmark)
Munir, Hafiz Mudassir; Zou, JianXiao; Xie, Chuan
2017-01-01
Shunt active power filters (S-APF) are highly popular ways for harmonic compensation due to the high performance and simplicity of installation. S-APF is commonly controlled in current control mode with load harmonic current detection, which is not quite suitable for the distributed power...... generation system (DPGS) where the nonlinear loads are highly dispersed. Local harmonic voltage detection based Resistive-APF (R-APF) seems more suitable to be applied in the DPGS, however, R-APF suffers from poor compensation performance and difficulty of parameter tuning. In this paper, a direct harmonic...
Spatial Mode Control of High-Order Harmonics
Energy Technology Data Exchange (ETDEWEB)
Mercer, I.; Mevel, E.; Zerne, R.; LHuillier, A.; Antoine, P.; Wahlstroem, C. [Department of Physics, Lund Institute of Technology, S-221 00 Lund (Sweden)]|[Commissariat a l`Energie Atomique, DSM/DRECAM/SPAM, Centre d`Etudes de Saclay, 91191 Gif-sur-Yvette (France)
1996-08-01
We demonstrate that the spatial mode of high-order harmonics can be continuously controlled. The control is achieved by spatially modulating the degree of elliptical polarization of the fundamental field using birefringent optics. A highly sensitive relationship between the efficiency of harmonic generation and the degree of laser elliptical polarization leads to atoms emitting harmonics only in regions of linear polarization. The harmonics are emitted as annular beams whose angles of divergence can be continuously varied. {copyright} {ital 1996 The American Physical Society.}
Scalar, vector and tensor harmonics on the three-sphere
Lindblom, Lee; Taylor, Nicholas W.; Zhang, Fan
2017-11-01
Scalar, vector and tensor harmonics on the three-sphere were introduced originally to facilitate the study of various problems in gravitational physics. These harmonics are defined as eigenfunctions of the covariant Laplace operator which satisfy certain divergence and trace identities, and ortho-normality conditions. This paper provides a summary of these properties, along with a new notation that simplifies and clarifies some of the key expressions. Practical methods are described for accurately and efficiently computing these harmonics numerically, and test results are given that illustrate how well the analytical identities are satisfied by the harmonics computed numerically in this way.
Harmonization of pre-analytical quality indicators
Plebani, Mario; Sciacovelli, Laura; Aita, Ada; Chiozza, Maria Laura
2014-01-01
Quality indicators (QIs) measure the extent to which set targets are attained and provide a quantitative basis for achieving improvement in care and, in particular, laboratory services. A body of evidence collected in recent years has demonstrated that most errors fall outside the analytical phase, while the pre- and post-analytical steps have been found to be more vulnerable to the risk of error. However, the current lack of attention to extra-laboratory factors and related QIs prevent clinical laboratories from effectively improving total quality and reducing errors. Errors in the pre-analytical phase, which account for 50% to 75% of all laboratory errors, have long been included in the ‘identification and sample problems’ category. However, according to the International Standard for medical laboratory accreditation and a patient-centered view, some additional QIs are needed. In particular, there is a need to measure the appropriateness of all test request and request forms, as well as the quality of sample transportation. The QIs model developed by a working group of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) is a valuable starting point for promoting the harmonization of available QIs, but further efforts should be made to achieve a consensus on the road map for harmonization. PMID:24627719
Investigating student understanding of simple harmonic motion
Somroob, S.; Wattanakasiwich, P.
2017-09-01
This study aimed to investigate students’ understanding and develop instructional material on a topic of simple harmonic motion. Participants were 60 students taking a course on vibrations and wave and 46 students taking a course on Physics 2 and 28 students taking a course on Fundamental Physics 2 on the 2nd semester of an academic year 2016. A 16-question conceptual test and tutorial activities had been developed from previous research findings and evaluated by three physics experts in teaching mechanics before using in a real classroom. Data collection included both qualitative and quantitative methods. Item analysis and whole-test analysis were determined from student responses in the conceptual test. As results, most students had misconceptions about restoring force and they had problems connecting mathematical solutions to real motions, especially phase angle. Moreover, they had problems with interpreting mechanical energy from graphs and diagrams of the motion. These results were used to develop effective instructional materials to enhance student abilities in understanding simple harmonic motion in term of multiple representations.
Probing energetics with second harmonic generation
Konek, Christopher; Mason, Brian; Stoltz, Chad; Gump, Jared; Wilkinson, John
2009-06-01
We focus on the insensitive high explosive 1,3,5-triamino-2,4,6- trinitrobenzene (TATB) with the goal of obtaining structural information as a function of pressure and temperature. Prior experiments from Los Alamos (Son et al. J. Phys. Chem. B. 1999, 103 (26) 5434) demonstrated that in high temperature environments (approaching 300^o C) TATB increases in efficiency as a nonlinear optical medium, possibly undergoing structural changes which alter the crystal symmetry. We use the nonlinear optical technique second harmonic generation (SHG) to probe TATB in a diamond anvil cell experimental setup to perform measurements at high pressure. Additionally, by exploiting the electronic absorption features of TATB to perform resonantly enhanced second harmonic generation (RE-SHG) experiments, we probe the electronic transitions in the visible range as a function of pressure and temperature, to observe electronic changes that would occur. Polarization resolved SHG experiments allow further insight into changes in crystal structure. These static measurements may have implications for shocked TATB.
Slana, Anka; Repovš, Grega; Fitch, W Tecumseh; Gingras, Bruno
2016-05-01
The context in which a stimulus is presented shapes the way it is processed. This effect has been studied extensively in the field of visual perception. Our understanding of how context affects the processing of auditory stimuli is, however, rather limited. Western music is primarily built on melodies (succession of pitches) typically accompanied by chords (harmonic context), which provides a natural template for the study of context effects in auditory processing. Here, we investigated whether pitch class equivalence judgments of tones are affected by the harmonic context within which the target tones are embedded. Nineteen musicians and 19 non-musicians completed a change detection task in which they were asked to determine whether two successively presented target tones, heard either in isolation or with a chordal accompaniment (same or different chords), belonged to the same pitch class. Both musicians and non-musicians were most accurate when the chords remained the same, less so in the absence of chordal accompaniment, and least when the chords differed between both target tones. Further analysis investigating possible mechanisms underpinning these effects of harmonic context on task performance revealed that both a change in gestalt (change in either chord or pitch class), as well as incongruency between change in target tone pitch class and change in chords, led to reduced accuracy and longer reaction times. Our results demonstrate that, similarly to visual processing, auditory processing is influenced by gestalt and congruency effects. Copyright © 2016 Elsevier B.V. All rights reserved.
Evaluation of tag entanglement as a factor in harmonic radar studies of insect dispersal.
Boiteau, G; Vincent, C; Meloche, F; Leskey, T C; Colpitts, B G
2011-02-01
The observation of insects and other small organisms entangled in the habitat after the addition of vertical or trailing electronic tags to their body has generated concerns on the suitability of harmonic radars to track the dispersal of insects. This study compared the walking behavior of adult Colorado potato beetle (Leptinotarsa decemlineata (Say) Chrysomelidae), plum curculio (Conotrachelus nenuphar (Herbst) Curculionidae), and western corn rootworm (Diabrotica virgifera virgifera (LeConte) Chrysomelidae) with and without vertical and or trailing tags in field plots or arenas. The frequency of the larger Colorado potato beetles crossing bare ground or grassy plots was unaffected by the presence of an 8 cm trailing harmonic radar tag. However, plum curculios and western corn rootworms, were either unable to walk with a 4 cm trailing tag (plum curculio) or displayed a reduced ability to successfully cross a bare ground arena. Our results revealed the significant impact of vegetation on successful insect dispersal, whether tagged or not. The vertical movement of these insects on stems, stalks, and tubes was also unaffected by the presence of vertical tags. Trailing tags had a significant negative effect on the vertical movement of the western corn rootworm. Results show that harmonic radar technology is a suitable method for studying the walking paths of the three insects with appropriate tag type and size. The nuisance factor generated by appropriately sized tags was small relative to that of vegetation. © 2011 Entomological Society of America
Holliday, Ezekiel S. (Inventor)
2014-01-01
Vibrations at harmonic frequencies are reduced by injecting harmonic balancing signals into the armature of a linear motor/alternator coupled to a Stirling machine. The vibrations are sensed to provide a signal representing the mechanical vibrations. A harmonic balancing signal is generated for selected harmonics of the operating frequency by processing the sensed vibration signal with adaptive filter algorithms of adaptive filters for each harmonic. Reference inputs for each harmonic are applied to the adaptive filter algorithms at the frequency of the selected harmonic. The harmonic balancing signals for all of the harmonics are summed with a principal control signal. The harmonic balancing signals modify the principal electrical drive voltage and drive the motor/alternator with a drive voltage component in opposition to the vibration at each harmonic.
Deng, Yufeng; Palmeri, Mark L; Rouze, Ned C; Haystead, Clare M; Nightingale, Kathryn R
2018-02-01
Harmonic imaging techniques have been applied in ultrasonic elasticity imaging to obtain higher-quality tissue motion tracking data. However, harmonic tracking can be signal-to-noise ratio and penetration depth limited during clinical imaging, resulting in decreased yield of successful shear wave speed measurements. A logical approach is to increase the source pressure, but the in situ pressures used in diagnostic ultrasound have been subject to a de facto upper limit based on the Food and Drug Administration guideline for the mechanical index (MI harmonic motion tracking for hepatic shear wave elasticity imaging. The studies indicate that high-MI harmonic tracking increased shear wave speed estimation yield by 27% at a focal depth of 5 cm, with larger yield increase in more difficult-to-image patients. High-MI tracking improved harmonic tracking data quality by increasing the signal-to-noise ratio and decreasing jitter in the tissue motion data. We conclude that there is clinical benefit to use of elevated acoustic output in shear wave tracking, particularly in difficult-to-image patients. Copyright © 2018 World Federation for Ultrasound in Medicine and Biology. Published by Elsevier Inc. All rights reserved.
Zhou, Qinghua; Xiao, Fuliang; Yang, Chang; Liu, Si; He, Yihua; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Funsten, H. O.
2017-06-01
Electrostatic electron cyclotron harmonic (ECH) waves generated by the electron loss cone distribution can produce efficient scattering loss of plasma sheet electrons, which has a significant effect on the dynamics in the outer magnetosphere. Here we report two ECH emission events around the same location L≈ 5.7-5.8, MLT ≈ 12 from Van Allen Probes on 11 February (event A) and 9 January 2014 (event B), respectively. The spectrum of ECH waves was centered at the lower half of the harmonic bands during event A, but the upper half during event B. The observed electron phase space density in both events is fitted by the subtracted bi-Maxwellian distribution, and the fitting functions are used to evaluate the local growth rates of ECH waves based on a linear theory for homogeneous plasmas. ECH waves are excited by the loss cone instability of 50 eV-1 keV electrons in the lower half of harmonic bands in the low-density plasmasphere in event A, and 1-10 keV electrons in the upper half of harmonic bands in a relatively high-density region in event B. The current results successfully explain observations and provide a first direct evidence on how ECH waves are generated in the lower and upper half of harmonic frequency bands.
Free Sixteen Harmonic Fourier Series Web App with Sound
Ruiz, Michael J.
2018-01-01
An online HTML5 Fourier synthesizer app is provided that allows students to manipulate sixteen harmonics and construct periodic waves. Students can set the amplitudes and phases for each harmonic, seeing the resulting waveforms and hearing the sounds. Five waveform presets are included: sine, triangle, square, ramp (sawtooth), and pulse train. The…
Compact fluorescent lamps, LED lamps and harmonic distortion
Franco, A. M. R.; Debatin, R. M.; Cotia, F. C. G.; Silva, M. V. M.; Ribeiro, R. S.; Zampilis, R. R. N.
2015-01-01
The aim of this paper is to evaluate the harmonic distortion in the current waveform of Compact Fluorescent Lamps (CFL) and Lamps Lighting Emitting Diode (LED). For this, we analysed the power factor, voltage waveform, current waveform, total harmonic distortion (THD) and active power consumed.
Deterministic and Stochastic Study of Wind Farm Harmonic Currents
DEFF Research Database (Denmark)
Sainz, Luis; Mesas, Juan Jose; Teodorescu, Remus
2010-01-01
Wind farm harmonic emissions are a well-known power quality problem, but little data based on actual wind farm measurements are available in literature. In this paper, harmonic emissions of an 18 MW wind farm are investigated using extensive measurements, and the deterministic and stochastic char...
Secondary Voltage Control for Harmonics Suppression in Islanded Microgrids
DEFF Research Database (Denmark)
Wang, Xiongfei; Guerrero, Josep M.; Blaabjerg, Frede
2011-01-01
in islanded microgrids. In addition to the centralized controller for fundamental frequency voltage component, a selective harmonic compensator is implemented in the secondary voltage control system. With the help of Park transformation, the cyclic references generated by the selective harmonic compensator...
Determination of Total Harmonic Distortion (THD) on a 33kv ...
African Journals Online (AJOL)
This paper presents the estimation of Total Harmonic Distortion (THD) of the Distribution lines in the 33kV distribution network of Island Business District, Eko Electricity Distribution Plc, taken as a case study using a set of busbar voltage results, obtained from previous studies on power flow and harmonic analyses of each ...
Harmonics and voltage stability analysis in power systems including ...
Indian Academy of Sciences (India)
R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22
steady-state voltage stability analysis. 4. Harmonic power flow algorithm. Network voltages and currents can be expressed by Fourier series for the harmonic power flow analysis, which was developed by Xia & Heydt (1982). Voltages and nonlinear element parameters form the bus variable vector ( ), given in. [X] = [. [ ˙V (1). ] ...
High-order-harmonic generation from field-distorted orbitals
DEFF Research Database (Denmark)
Spiewanowski, Maciek; Etches, Adam; Madsen, Lars Bojer
2013-01-01
We investigate the effect on high-order-harmonic generation of the distortion of molecular orbitals by the driving laser field. Calculations for high-order-harmonic generation including orbital distortion are performed for N2. Our results allow us to suggest that field distortion is the reason why...
Single-shot fluctuations in waveguided high-harmonic generation
Goh, S.J.; Tao, Y.; van der Slot, Petrus J.M.; Bastiaens, Hubertus M.J.; Herek, Jennifer Lynn; Biedron, S.G.; Danailov, M.B.; Milton, S.V.; Boller, Klaus J.
2015-01-01
For exploring the application potential of coherent soft x-ray (SXR) and extreme ultraviolet radiation (XUV) provided by high-harmonic generation, it is important to characterize the central output parameters. Of specific importance are pulse-to-pulse (shot-to-shot) fluctuations of the high-harmonic
The harmonics detection method based on neural network applied ...
African Journals Online (AJOL)
user
Consequently, many structures based on artificial neural network (ANN) have been developed in the literature, The most significant ... Keywords: Artificial Neural Networks (ANN), p-q theory, (SAPF), Harmonics, Total Harmonic Distortion. 1. ..... and pure shunt active fitters, IEEE 38th Conf on Industry Applications, Vol. 2, pp.
Professional Military Development of Major General Ernest N. Harmon
2008-06-13
challenges of American demobilization – with the war over soldiers wanted to go home. Civil-military considerations also dominated the occupation...group’s issues impressed Harmon. Years later Harmon explained that, “It struck me that teen -age Iowa farm boys might know more about soil content
Transient state work fluctuation theorem for a classical harmonic ...
Indian Academy of Sciences (India)
Based on a Hamiltonian description we present a rigorous derivation of the transient state work fluctuation theorem and the Jarzynski equality for a classical harmonic oscillator linearly coupled to a harmonic heat bath, which is dragged by an external agent. Coupling with the bath makes the dynamics dissipative. Since we ...
Harmonics: Generation and Suppression in AC System Networks ...
African Journals Online (AJOL)
Majority of loads such as induction motors, battery chargers, static converters, light fittings, arc furnaces, transformers, cables, transmission lines and so on draw both sinusoidal currents and currents which are multiples of the supply frequency, commonly called harmonics. These harmonics are out of phase with the supply ...
Harmonic measures and Poisson kernels on Klein surfaces
Directory of Open Access Journals (Sweden)
Monica Rosiu
2017-10-01
Full Text Available We introduce harmonic measure on a Klein surface and obtain a formula for the solution of the Dirichlet problem on a Klein surface, which is an analogue for the Poisson integral. We rewrite the Radon-Nikodym derivative of harmonic measure against the corresponding arc length.
Multidistortion-invariant image recognition with radial harmonic Fourier moments.
Ren, Haiping; Ping, Ziliang; Bo, Wurigen; Wu, Wenkai; Sheng, Yunlong
2003-04-01
We propose radial harmonic Fourier moments, which are shifting, scaling, rotation, and intensity invariant. Compared with Chebyshev-Fourier moments, the new moments have superior performance near the origin and better ability to describe small images in terms of image-reconstruction errors and noise sensitivity. A multidistortion-invariant pattern-recognition experiment was performed with radial harmonic Fourier moments.
Spectral inverse problem for q-deformed harmonic oscillator
Indian Academy of Sciences (India)
The supersymmetric quantization condition is used to study the wave functions of SWKB equivalent -deformed harmonic oscillator which are obtained by using only the knowledge of bound-state spectra of -deformed harmonic oscillator. We have also studied the nonuniqueness of the obtained interactions by this ...
Variation of Rainfall in Three Nigerian Stations, Using harmonic ...
African Journals Online (AJOL)
This work is on the variation of rainfall using harmonic analysis for Portharcourt, Kano and Makurdi data, for the three stations the period of study covered 1977 to 2010, for which the time series plot, the amplitude, the first, second and third harmonics were generated. Portharcourt has a gently increasing trend with ...
Harmonic sums and polylogarithms generated by cyclotomic polynomials
Energy Technology Data Exchange (ETDEWEB)
Ablinger, Jakob; Schneider, Carsten [Johannes Kepler Univ., Linz (Austria). Research Inst. for Symbolic Computation; Bluemlein, Johannes [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2011-05-15
The computation of Feynman integrals in massive higher order perturbative calculations in renormalizable Quantum Field Theories requires extensions of multiply nested harmonic sums, which can be generated as real representations by Mellin transforms of Poincare-iterated integrals including denominators of higher cyclotomic polynomials. We derive the cyclotomic harmonic polylogarithms and harmonic sums and study their algebraic and structural relations. The analytic continuation of cyclotomic harmonic sums to complex values of N is performed using analytic representations. We also consider special values of the cyclotomic harmonic polylogarithms at argument x=1, resp., for the cyclotomic harmonic sums at N{yields}{infinity}, which are related to colored multiple zeta values, deriving various of their relations, based on the stuffle and shuffle algebras and three multiple argument relations. We also consider infinite generalized nested harmonic sums at roots of unity which are related to the infinite cyclotomic harmonic sums. Basis representations are derived for weight w=1,2 sums up to cyclotomy l=20. (orig.)
Analysis and control of harmonic distortions on electrical distribution ...
African Journals Online (AJOL)
... peak factor and harmonic distortions of the alternating or sinusoidal wave forms. The consequences of harmonic distortions of transmitted electrical energy might be damage of con-densers, untimely release of circuit breakers, resonance in the networks, warming of transformers and over heat-ing of electrical appliances.
Harmonic factors in the perception of tonal melodies
Povel, D.J.L.; Jansen, E.L.
2002-01-01
By common assumption, the first step in processing a tonal melody consists in setting up the appropriate metrical and harmonic frames required for the mental representation of the sequence of tones. Focusing on the generation of a harmonic frame, this study aims (a) to discover the factors that
Large-Nc quantum chromodynamics and harmonic sums
Indian Academy of Sciences (India)
2012-06-08
Jun 8, 2012 ... In the large-Nc limit of QCD, two-point functions of local operators become harmonic sums. I review some ... spontaneous chiral symmetry breaking and the hadronic spectrum consists then of an infinite ..... [32]), a harmonic sum is characterized by a base function (in our case the kernel in the dispersion ...
New constructions of twistor lifts for harmonic maps
DEFF Research Database (Denmark)
Svensson, Martin; C. Wood, John
2014-01-01
We show that given a harmonic map \\varphi from a Riemann surface into a classical simply connected compact inner symmetric space, there is a J_2-holomorphic twistor lift of \\varphi (or its negative) if and only if it is nilconformal. In the case of harmonic maps of finite uniton number, we give a...
Harmonic Riemannian maps on locally conformal Kaehler manifolds
Indian Academy of Sciences (India)
Abstract. We study harmonic Riemannian maps on locally conformal Kaehler mani- folds (lcK manifolds). We show that if a Riemannian holomorphic map between lcK manifolds is harmonic, then the Lee vector field of the domain belongs to the kernel of the Riemannian map under a condition. When the domain is Kaehler, ...
Harmonic Orientation of Pulse Width Modulation Technique in Multilevel Inverters
Urmila Bandaru; Subba D Rayudu
2011-01-01
The Multilevel Inverter topology gives the advantages of usage in high power and high voltage application with reduced harmonic distortion without a transformer. This paper presents a comparative study of orientation of higher ordered harmonics with increase in switching frequency around the frequency modulation index of nine level diode clamped inverter for different Switching frequency Multicarrier Pulse width Modulation.
harmonics mitigation on industrial loads using series and parallel
African Journals Online (AJOL)
user
system efficiency and provide great energy saving, their vulnerability to harmonics ... wave. Typical examples of harmonics sources include fluorescent lighting, computer switch mode power supplies, static var compensators, variable frequency motor drives, dc-dc converters, inverters, chillers etc. [13]. When considering ...
Second-harmonic imaging of semiconductor quantum dots
DEFF Research Database (Denmark)
Østergaard, John Erland; Bozhevolnyi, Sergey I.; Pedersen, Kjeld
2000-01-01
. In addition, the second-harmonic spectrum exhibits another smaller but well-pronounced peak at 765 nm not found in the linear experiments. We attribute this peak to the generation of second-harmonic radiation in the AlGaAs spacer layer enhanced by the local symmetry at the quantum-dot interface. We further...
Random Harmonic Detection and Compensation Based on Synchronous Reference Frame
Directory of Open Access Journals (Sweden)
Yanbo Che
2017-01-01
Full Text Available Algorithms for harmonic detection and compensation are important guarantees for an active power filter (APF to achieve the harmonic control function and directly determine the overall performance. Existing algorithms usually need a large amount of computation, and the compensation effect of specified order harmonic is also limited. DC side capacitor voltage at sudden change of load is affected by the algorithm as well. This paper proposes a new algorithm for harmonic detection and compensation based on synchronous reference frame (SRF, in which a band-pass filter with center frequency of 6kth harmonic is designed in fundamental frequency SRF to extract random harmonic current with two different frequencies of (6k±1th harmonic in stationary reference frame. This new algorithm can rapidly detect any specified harmonic, and it can adjust the power factor to compensate reactive power. Meanwhile, it has few impacts on DC side capacitor voltage under complicated operating conditions such as sudden change of load. The correctness and effectiveness of this new algorithm are verified by simulation and experiment.
Harmonic analysis of DC capacitor current in sinusoidal and space ...
Indian Academy of Sciences (India)
The voltage ripple and power loss in the DC-capacitor of a voltage source inverter depend on the harmonic currents flowing through the capacitor. This paper presents a double Fourier series based analysis of the harmonic contents of the DC capacitor current in a three-level neutral-point clamped (NPC) inverter, modulated ...
Harmonic balance analysis of the generalized chua's circuit
Savacı, Ferit Acar; Günel, Serkan
2006-01-01
In this paper, the harmonic balance analysis of Generalized Chua's circuit exhibiting n-scroll attractors has been accomplished. The dual-input describing functions of the piecewise-linear characteristics of Chua's diode have been obtained and based on the harmonic balance principle, the existence and the locations of the n-scrolls have been verified.
Improving harmonic rejection for spectrum sensing using crosscorrelation
Oude Alink, M.S.; Kokkeler, Andre B.J.; Klumperink, Eric A.M.; Ru, Z.; Cheng, W.; Nauta, Bram
2012-01-01
Harmonic downmixing may cause a spectrum sensing device to erroneously flag parts of the spectrum as occupied. Receivers employing harmonic rejection (HR) rarely obtain more than 60 dB of HR, which may not be enough for spectrum sensing for dynamic spectrum access. We improve HR by employing two
Legal harmonization and reproductive tourism in Europe.
Pennings, Guido
2004-12-01
Legislation of ethical issues illustrates the uneasy mix of ethics and politics. Although the majority has the political right to express its moral views in the law, a number of important ethical values like autonomy, tolerance and respect for other people's opinions urge the majority to take the minorities' position into account. Ignoring pluralism in society will inevitably lead to reproductive tourism. Although European legislation and harmonization in the domain of medically assisted reproduction is presented as a partial solution to this phenomenon, it is argued that European legislation should be avoided as much as possible. Regulation of these private ethical matters should be left to the national parliaments. A soft or compromise legislation will keep reproductive travelling to a minimum. Reproductive tourism is a safety valve that reduces moral conflict and expresses minimal recognition of the others' moral autonomy.
Asymmetric network connectivity using weighted harmonic averages
Morrison, Greg; Mahadevan, L.
2011-02-01
We propose a non-metric measure of the "closeness" felt between two nodes in an undirected, weighted graph using a simple weighted harmonic average of connectivity, that is a real-valued Generalized Erdös Number (GEN). While our measure is developed with a collaborative network in mind, the approach can be of use in a variety of artificial and real-world networks. We are able to distinguish between network topologies that standard distance metrics view as identical, and use our measure to study some simple analytically tractable networks. We show how this might be used to look at asymmetry in authorship networks such as those that inspired the integer Erdös numbers in mathematical coauthorships. We also show the utility of our approach to devise a ratings scheme that we apply to the data from the NetFlix prize, and find a significant improvement using our method over a baseline.
Optical second harmonic generation from Pt nanowires
Energy Technology Data Exchange (ETDEWEB)
Hayashi, N.; Aratake, K.; Okushio, R.; Iwai, T. [Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Sugawara, A. [Hitachi Advanced Research Laboratory, Akanuma 2520, Hatoyama, Saitama 350-0395 (Japan); Sano, H. [Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Mizutani, G. [Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan)], E-mail: mizutani@jaist.ac.jp
2007-09-15
We have measured optical second harmonic intensity from arrays of Pt nanowires of 20 nm and 9 nm average widths, as a function of the incident and output light polarizations, the azimuthal angle, and the excitation photon energy. The nanowires were fabricated through shadow deposition on self-organized NaCl(1 1 0) faceted templates. The anisotropy of the SH intensity from the Pt nanowires was found to be stronger than that from the Au nanowires reported previously. The effective nonlinear susceptibility element {chi}{sub 222}{sup (2)}, with the suffix 2 indicating the direction [11-bar0], was observed for Pt nanowires, although it was not observed for Au nanowires. This difference is suggested to be due to the weaker suppression of the incident fundamental fields by the depolarization field in the Pt nanowires and the larger anisotropy in the nonlinearity of Pt nanowires due to the thinner widths.
Second Harmonic Generation of Unpolarized Light
Ding, Changqin; Ulcickas, James R. W.; Deng, Fengyuan; Simpson, Garth J.
2017-11-01
A Mueller tensor mathematical framework was applied for predicting and interpreting the second harmonic generation (SHG) produced with an unpolarized fundamental beam. In deep tissue imaging through SHG and multiphoton fluorescence, partial or complete depolarization of the incident light complicates polarization analysis. The proposed framework has the distinct advantage of seamlessly merging the purely polarized theory based on the Jones or Cartesian susceptibility tensors with a more general Mueller tensor framework capable of handling partial depolarized fundamental and/or SHG produced. The predictions of the model are in excellent agreement with experimental measurements of z -cut quartz and mouse tail tendon obtained with polarized and depolarized incident light. The polarization-dependent SHG produced with unpolarized fundamental allowed determination of collagen fiber orientation in agreement with orthogonal methods based on image analysis. This method has the distinct advantage of being immune to birefringence or depolarization of the fundamental beam for structural analysis of tissues.
The feasibility of harmonizing gluten ELISA measurements.
Rzychon, Malgorzata; Brohée, Marcel; Cordeiro, Fernando; Haraszi, Reka; Ulberth, Franz; O'Connor, Gavin
2017-11-01
Many publications have highlighted that routine ELISA methods do not give rise to equivalent gluten content measurement results. In this study, we assess this variation between results and its likely impact on the enforcement of the EU gluten-free legislation. This study systematically examines the feasibility of harmonizing gluten ELISA assays by the introduction of: a common extraction procedure; a common calibrator, such as a pure gluten extract and an incurred matrix material. The comparability of measurements is limited by a weak correlation between kit results caused by differences in the selectivity of the methods. This lack of correlation produces bias that cannot be corrected by using reference materials alone. The use of a common calibrator reduced the between-assay variability to some extent, but variation due to differences in selectivity of the assays was unaffected. Consensus on robust markers and their conversion to "gluten content" are required. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.
Harmonic states for the free particle
Energy Technology Data Exchange (ETDEWEB)
Guerrero, J [Departamento de Matematica Aplicada, Universidad de Murcia, Campus de Espinardo, 30100 Murcia (Spain); Lopez-Ruiz, F F; Aldaya, V; Cossio, F, E-mail: juguerre@um.es, E-mail: flopez@iaa.es, E-mail: valdaya@iaa.es, E-mail: focossiop@gmail.com [Instituto de Astrofisica de Andalucia, CSIC, Apartado Postal 3004, 18080 Granada (Spain)
2011-11-04
Different families of states, which are solutions of the time-dependent free Schroedinger equation, are imported from the harmonic oscillator using the quantum Arnold transformation introduced in Aldaya et al (2011 J. Phys. A: Math. Theor.44 065302). Among them, infinite series of states are given that are normalizable, expand the whole space of solutions, are spatially multi-localized and are eigenstates of a suitably defined number operator. Associated with these states new sets of coherent and squeezed states for the free particle are defined representing traveling, squeezed, multi-localized wave packets. These states are also constructed in higher dimensions, leading to the quantum mechanical version of the Hermite-Gauss and Laguerre-Gauss states of paraxial wave optics. Some applications of these new families of states and procedures to experimentally realize and manipulate them are outlined. (paper)
Conditional Anomaly Detection with Soft Harmonic Functions.
Valko, Michal; Kveton, Branislav; Valizadegan, Hamed; Cooper, Gregory F; Hauskrecht, Milos
2011-01-01
In this paper, we consider the problem of conditional anomaly detection that aims to identify data instances with an unusual response or a class label. We develop a new non-parametric approach for conditional anomaly detection based on the soft harmonic solution, with which we estimate the confidence of the label to detect anomalous mislabeling. We further regularize the solution to avoid the detection of isolated examples and examples on the boundary of the distribution support. We demonstrate the efficacy of the proposed method on several synthetic and UCI ML datasets in detecting unusual labels when compared to several baseline approaches. We also evaluate the performance of our method on a real-world electronic health record dataset where we seek to identify unusual patient-management decisions.
Harmonizing human exposure and toxicity characterization
DEFF Research Database (Denmark)
Fantke, Peter; Jolliet, O.; McKone, T.E.
2017-01-01
The UNEP-SETAC Life Cycle Initiative has launched a project to provide global guidance and build consensus on environmental life cycle impact assessment (LCIA) indicators. Human health effects from exposure to toxic chemicals was selected as impact category due to high relevance of human toxicity...... impacts, past and present efforts in human toxicity assessment, and the need for further harmonization and global guidance. To address this need, an expert workshop was implemented in Utrecht in October 2016 with the aim of building a roadmap for a reliable and consistent approach for improving...... and use of impact factors for toxic chemicals. We propose to couple fate processes in consumer and occupational environments with existing environmental compartments and processes via a consistent and mass balance-based set of transfer fractions to quantify overall aggregated exposure to toxic substances...
Coherent states for the relativistic harmonic oscillator
Aldaya, Victor; Guerrero, J.
1995-01-01
Recently we have obtained, on the basis of a group approach to quantization, a Bargmann-Fock-like realization of the Relativistic Harmonic Oscillator as well as a generalized Bargmann transform relating fock wave functions and a set of relativistic Hermite polynomials. Nevertheless, the relativistic creation and annihilation operators satisfy typical relativistic commutation relations of the Lie product (vector-z, vector-z(sup dagger)) approximately equals Energy (an SL(2,R) algebra). Here we find higher-order polarization operators on the SL(2,R) group, providing canonical creation and annihilation operators satisfying the Lie product (vector-a, vector-a(sup dagger)) = identity vector 1, the eigenstates of which are 'true' coherent states.
Enhanced third harmonic generation with graphene metasurfaces
Jin, Boyuan; Guo, Tianjing; Argyropoulos, Christos
2017-09-01
The nonlinear responses of different materials provide useful mechanisms for optical switching, low noise amplification, and harmonic frequency generation. However, the nonlinear processes usually have an extremely weak nature and require high input power to be excited. To alleviate this severe limitation, we propose new designs of ultrathin nonlinear metasurfaces composed of patterned graphene micro-ribbons to significantly enhance third harmonic generation (THG) at far-infrared and terahertz (THz) frequencies. The incident wave is tightly confined and significantly boosted along the surface of graphene in these configurations due to the excitation of highly localized plasmons. The bandwidth of the resonant response becomes narrower due to the introduction of a metallic substrate below the graphene micro-ribbons, which leads to zero transmission and standing waves inside the intermediate dielectric spacer layer. The enhancement of the incident field, combined with the large nonlinear conductivity of graphene, can dramatically increase the THG conversion efficiency by several orders of magnitude. In addition, the resonant frequency of the metasurface can be adjusted by dynamically tuning the Fermi energy of graphene via electrical or chemical doping. As a result, the THG wave can be optimized and tuned to be emitted at different frequencies without the need to change the nonlinear metasurface geometry. The proposed nonlinear metasurfaces provide a new way to realize compact and efficient nonlinear sources at the far-infrared and THz frequency ranges, as well as new frequency generation and wave mixing devices which are expected to be useful for nonlinear THz spectroscopy and noninvasive THz imaging applications.
Microgrid Reactive and Harmonic Power Sharing Using Enhanced Virtual Impedance
DEFF Research Database (Denmark)
He, Jinwei; Wei Li, Yun; Guerrero, Josep M.
2013-01-01
only a line current feed-forward term is added to the DG voltage reference, the proposed virtual impedances at fundamental and harmonic frequencies are realized using DG line current and point of common coupling (PCC) voltage feed-forward terms, respectively. With this modification, the mismatched DG......To address the load sharing problem in islanding microgrids, this paper proposes an improved approach which regulates the distributed generation (DG) unit interfacing virtual impedance at fundamental and selected harmonic frequencies. In contrast to the conventional virtual impedance control where...... feeder impedances can be properly compensated, resulting in accurate reactive and harmonic power sharing at the same time. In addition, this paper shows that the microgrid PCC harmonic voltages can be mitigated by reducing the magnitude of DG unit equivalent harmonic impedance. Finally, an improved...
High-order harmonic generation from polar molecules
DEFF Research Database (Denmark)
Etches, Adam
When a molecule is submitted to a very intense laser pulse it emits coherent bursts of light in each optical half-cycle of the laser field. This process is known as high-order harmonic generation because the spectrum consists of many peaks at energies corresponding to an integer amount of laser...... photons. The harmonics contain information about the wave function of the loosest bound electron on an Ångström length scale and attosecond time scale. However, accurate theoretical models are needed in order to extract this information. In this thesis the most widely used model of high-order harmonic...... generation is extended to polar molecules by including the laser-induced Stark shift of each molecular orbitals. The Stark shift is shown to have a major influence on the relative strength of harmonic bursts in neighbouring half-cycles, as well as leaving an imprint on the phase of the harmonics...
Frequency Adaptability of Harmonics Controllers for Grid-Interfaced Converters
DEFF Research Database (Denmark)
Yang, Yongheng; Zhou, Keliang; Blaabjerg, Frede
2017-01-01
A wider spread adoption of power electronic converters interfaced renewable energy systems has brought more attention to harmonic issues to the electrical grid, and means are taken to improve it in the control. More advanced closed-loop harmonic controllers are thus demanded to enhance...... sensitivity of the most popular harmonic controllers for grid-interfaced converters. The frequency adaptability of these harmonic controllers is evaluated in the presence of a variable grid frequency within a specified reasonable range, e.g., +-1% of the nominal grid frequency (50 Hz). Solutions...... the renewable energy integration in order to be grid-friendly. However, usually being treated as a constant factor in the design of harmonic controllers, the grid frequency varies with the generation-load imbalance, and thus may lead to deterioration of the power quality. This paper explores the frequency...
Full quantum trajectories resolved high-order harmonic generation.
Ye, Peng; He, Xinkui; Teng, Hao; Zhan, Minjie; Zhong, Shiyang; Zhang, Wei; Wang, Lifeng; Wei, Zhiyi
2014-08-15
We use a carrier-envelope-phase stabilized sub-2-cycle laser pulse to generate high-order harmonics and study how the two-dimensional spectrum of harmonics, with the resolutions in temporal frequency and spatial frequency, is shaped by the laser phase. An arrowlike spectrum obtained experimentally when the gas cell is located in front of the laser focus point shows a resolution of full quantum trajectories; i.e., harmonics from different trajectories stand on different positions in this spectrum. In particular, due to the laser phase combined with the classical-like action, the harmonics from short and long trajectories differ maximally in their curvatures of wave fronts in the generation area, and so occupy very different ranges of spatial frequency at the far field. The result directly gives a full map of quantum trajectories in high-order harmonic generation. The conclusion is supported by an analytical model and quantum mechanics simulations.
Bounce-harmonic Landau Damping of Plasma Waves
Anderegg, Francois
2015-11-01
We present measurement of plasma wave damping, spanning the temperature regimes of direct Landau damping, bounce-harmonic Landau damping, inter-species drag damping, and viscous damping. Direct Landau damping is dominant at high temperatures, but becomes negligible as v harmonics damping, controlled by an applied ``squeeze'' potential, which generates harmonics in the wave potential and in the particle dynamics. A particle moving in z experiences a non-sinusoidal mode potential caused by the squeeze, producing high spatial harmonics with lower phase velocity. These harmonics are Landau damped even when the mode phase velocity vph is large compared to the thermal velocity v , since the nth harmonic is resonant with a particle bouncing at velocity vb =vph / n . Here we increase the bounce harmonics through applied squeeze potential; but some harmonics are always present in finite length systems. For our centered squeeze geometry, theory shows that only odd harmonics are generated, and predicts the Landau damping rate from vph / n . Experimentally, the squeeze potential increases the wave damping and reduces its frequency. The frequency shift occurs because the squeeze potential reduces the number of particle where the mode velocity is the largest, therefore reducing the mode frequency. We observe an increase in the damping proportional to Vs2,and a frequency reduction proportional to Vs , in quantitative agreement with theory. Wave-coherent laser induced fluorescence allows direct observation of bounce resonances on the particle distribution, here predominantly at vph / 3 . A clear increase of the bounce harmonics is visible on the particle distribution when the squeeze potential is applied. Supported by NSF Grant PHY-1414570, and DOE Grants DE-SC0002451 and DE-SC0008693.
Applied and computational harmonic analysis on graphs and networks
Irion, Jeff; Saito, Naoki
2015-09-01
In recent years, the advent of new sensor technologies and social network infrastructure has provided huge opportunities and challenges for analyzing data recorded on such networks. In the case of data on regular lattices, computational harmonic analysis tools such as the Fourier and wavelet transforms have well-developed theories and proven track records of success. It is therefore quite important to extend such tools from the classical setting of regular lattices to the more general setting of graphs and networks. In this article, we first review basics of graph Laplacian matrices, whose eigenpairs are often interpreted as the frequencies and the Fourier basis vectors on a given graph. We point out, however, that such an interpretation is misleading unless the underlying graph is either an unweighted path or cycle. We then discuss our recent effort of constructing multiscale basis dictionaries on a graph, including the Hierarchical Graph Laplacian Eigenbasis Dictionary and the Generalized Haar-Walsh Wavelet Packet Dictionary, which are viewed as generalizations of the classical hierarchical block DCTs and the Haar-Walsh wavelet packets, respectively, to the graph setting. Finally, we demonstrate the usefulness of our dictionaries by using them to simultaneously segment and denoise 1-D noisy signals sampled on regular lattices, a problem where classical tools have difficulty.
Currents and fluctuations of quantum heat transport in harmonic chains
Motz, T.; Ankerhold, J.; Stockburger, J. T.
2017-05-01
Heat transport in open quantum systems is particularly susceptible to the modeling of system-reservoir interactions. It thus requires us to consistently treat the coupling between a quantum system and its environment. While perturbative approaches are successfully used in fields like quantum optics and quantum information, they reveal deficiencies—typically in the context of thermodynamics, when it is essential to respect additional criteria such as fluctuation-dissipation theorems. We use a non-perturbative approach for quantum dissipative dynamics based on a stochastic Liouville-von Neumann equation to provide a very general and extremely efficient formalism for heat currents and their correlations in open harmonic chains. Specific results are derived not only for first- but also for second-order moments, which requires us to account for both real and imaginary parts of bath-bath correlation functions. Spatiotemporal patterns are compared with weak coupling calculations. The regime of stronger system-reservoir couplings gives rise to an intimate interplay between reservoir fluctuations and heat transfer far from equilibrium.
Directory of Open Access Journals (Sweden)
Taufiqurrahman Nasihun
2015-06-01
Full Text Available The emerging concept of successful aging is based on evidence that in healthy individual when they get aged, there areÂ considerable variations in physiological functions alteration. Some people exhibiting greater, but others very few or no age related alteration. The first is called poor aging and the later is called successful pattern of aging (Lambert SW, 2008. Thus, in the simple words the successful aging concept is define as an opportunity of old people to stayÂ active and productive condition despite they get aged chronologically. Aging itself might be defined as the progressive accumulation of changes with time associated with or responsible for the ever-increasing susceptibility to disease and death which accompanies advancing age (Harman D, 1981. The time needed to accumulate changes is attributable to aging process. The marked emerging questions are how does aging happen and where does aging start? To answer these questions and because of the complexity of aging process, there are more than 300 aging theories have been proposed to explain how and where aging occured and started respectively. There are too many to enumerate theories and classification of aging process. In summary, all of these aging theories can be grouped into three clusters: 1. Genetics program theory, this theory suggests that aging is resulted from program directed by the genes; 2. Epigenetic theory, in these theory aging is resulted from environmental random events not determined by the genes; 3. Evolutionary theory, which propose that aging is a medium for disposal mortal soma in order to avoid competition between organism and their progeny for food and space, did not try to explain how aging occur, but possibly answer why aging occur (De la Fuente. 2009. Among the three groups of aging theories, the epigenetic theory is useful to explain and try to solve the enigma of aging which is prominently caused by internal and external environmental influences
Harmonic Tracking of Acoustic Radiation Force Induced Displacements
Doherty, Joshua R.; Dahl, Jeremy J.; Trahey, Gregg E.
2014-01-01
Ultrasound-based elasticity imaging methods rely upon accurate estimates of tissue deformation to characterize the mechanical properties of soft tissues. These methods are corrupted by clutter, which can bias and/or increase variance in displacement estimates. Harmonic imaging methods are routinely used for clutter suppression and improved image quality in conventional B-mode ultrasound, but have not been utilized in ultrasound-based elasticity imaging methods. We introduce a novel, fully-sampled pulse inversion harmonic method for tracking tissue displacements that corrects the loss in temporal sampling frequency associated with conventional pulse inversion techniques. The method is implemented with Acoustic Radiation Force Impulse (ARFI) imaging to monitor the displacements induced by an impulsive acoustic radiation force excitation. Custom pulse sequences were implemented on a diagnostic ultrasound scanner to collect spatially-matched fundamental and harmonic information within a single acquisition. B-mode and ARFI images created from fundamental data collected at 4 MHz and 8 MHz are compared with 8 MHz harmonic images created using a bandpass filter approach and the fully sampled pulse inversion method. In homogeneous, tissue-mimicking phantoms, where no visible clutter was observed, there was little difference in the axial displacements, estimated jitter, and normalized cross-correlation among the fundamental and harmonic tracking methods. The similarity of the lower and higher frequency methods suggests that any improvement due to the increased frequency of the harmonic components is negligible. The harmonic tracking methods demonstrated a marked improvement in B-mode and ARFI image quality of in vivo carotid arteries. Improved feature detection and decreased variance in estimated displacements were observed in the arterial walls of harmonic ARFI images, especially in the pulse inversion harmonic ARFI images. Within the lumen, the harmonic tracking methods
Harmonic tracking of acoustic radiation force-induced displacements.
Doherty, Joshua R; Dahl, Jeremy J; Trahey, Gregg E
2013-11-01
Ultrasound-based elasticity imaging methods rely upon accurate estimates of tissue deformation to characterize the mechanical properties of soft tissues. These methods are corrupted by clutter, which can bias and/or increase variance in displacement estimates. Harmonic imaging methods are routinely used for clutter suppression and improved image quality in conventional B-mode ultrasound, but have not been utilized in ultrasound-based elasticity imaging methods. We introduce a novel, fully-sampled pulse-inversion harmonic method for tracking tissue displacements that corrects the loss in temporal sampling frequency associated with conventional pulse-inversion techniques. The method is implemented with acoustic radiation force impulse (ARFI) imaging to monitor the displacements induced by an impulsive acoustic radiation force excitation. Custom pulse sequences were implemented on a diagnostic ultrasound scanner to collect spatially-matched fundamental and harmonic information within a single acquisition. B-mode and ARFI images created from fundamental data collected at 4 MHz and 8 MHz are compared with 8-MHz harmonic images created using a band-pass filter approach and the fully sampled pulse-inversion method. In homogeneous, tissue-mimicking phantoms, where no visible clutter was observed, there was little difference in the axial displacements, estimated jitter, and normalized cross-correlation among the fundamental and harmonic tracking methods. The similarity of the lower- and higher-frequency methods suggests that any improvement resulting from the increased frequency of the harmonic components is negligible. The harmonic tracking methods demonstrated a marked improvement in B-mode and ARFI image quality of in vivo carotid arteries. Improved feature detection and decreased variance in estimated displacements were observed in the arterial walls of harmonic ARFI images, especially in the pulse-inversion harmonic ARFI images. Within the lumen, the harmonic tracking
Ultrafast high harmonics for probing the fastest spin and charge dynamics in magnetic materials
Grychtol, Patrick
2015-03-01
Ultrafast light based on the high-harmonic up-conversion of femtosecond laser pulses have been successfully employed to access resonantly enhanced magnetic contrast at the Mabsorption edges of the 3d ferromagnets Fe, Co and Ni in a table-top setup. Thus, it has been possible to study element-specific dynamics in magnetic materials at femtosecond time scales in a laboratory environment, providing a wealth of opportunities for a greater fundamental understanding of correlated phenomena in solid-state matter. However, these investigations have so far been limited to linear polarized harmonics, since most techniques by which circular soft x-rays can be generated are highly inefficient reducing the photon flux to a level unfit for scientific applications. Besides presenting key findings of our ultrafast studies on charge and spin dynamics, we introduce a simple setup which allows for the efficient generation of circular harmonics bright enough for XMCD experiments. Our work thus represents a critical advance that enables element-specific imaging and spectroscopy of multiple elements simultaneously in magnetic and other chiral media with very high spatial and temporal resolution on the tabletop. In collboration with Ronny Knut, Emrah Turgut, Dmitriy Zusin, Christian Gentry, Henry Kapteyn, Margaret Murnane, JILA, University of Colorado, Boulder; Justin Shaw, Hans Nembach, Tom Silva, Electromagnetics Division, NIST, Boulder, CO; and Ofer Kfir, Avner Fleischer, Oren Cohen, Extreme Nonlinear Optics Group, Solid State Institute, Technion, Israel.
Developments of VAT Rates in EU Countries in the Context of Harmonization and Fiscal Consolidation
Directory of Open Access Journals (Sweden)
Alena Andrejovská
2015-01-01
Full Text Available Although the value added tax is most often used tax it is a relatively young tax instrument that can assure significant increase in countries tax revenues. The advantage of VAT is that it is a consumption tax and so the tax payers take it as a natural part of the price. To assure the transparency and flexibility of relationships between EU countries, EC stresses the need of harmonizing Member States’ approaches to VAT rates and tax bases. Development of its rates refers to a relative autonomy of the states’ policies and at the same time illustrates the changes in the tax harmonization process, which enhances the need for its research. The paper analyzes the development of VAT rates in the EU since their introduction, with the emphasis on the period 2000–2012. Development is evaluated in terms of harmonization and fiscal consolidation in the crisis years. At the same time the implicit rate of value added tax is determined, which serves as a measure of tax collection success to its base.
Resonant plasmonic nanoparticles for multicolor second harmonic imaging
Accanto, Nicolò; Piatkowski, Lukasz; Hancu, Ion M.; Renger, Jan; van Hulst, Niek F.
2016-02-01
Nanoparticles capable of efficiently generating nonlinear optical signals, like second harmonic generation, are attracting a lot of attention as potential background-free and stable nano-probes for biological imaging. However, second harmonic nanoparticles of different species do not produce readily distinguishable optical signals, as the excitation laser mainly defines their second harmonic spectrum. This is in marked contrast to other fluorescent nano-probes like quantum dots that emit light at different colors depending on their sizes and materials. Here, we present the use of resonant plasmonic nanoparticles, combined with broadband phase-controlled laser pulses, as tunable sources of multicolor second harmonic generation. The resonant plasmonic nanoparticles strongly interact with the electromagnetic field of the incident light, enhancing the efficiency of nonlinear optical processes. Because the plasmon resonance in these structures is spectrally narrower than the laser bandwidth, the plasmonic nanoparticles imprint their fingerprints on the second harmonic spectrum. We show how nanoparticles of different sizes produce different colors in the second harmonic spectra even when excited with the same laser pulse. Using these resonant plasmonic nanoparticles as nano-probes is promising for multicolor second harmonic imaging while keeping all the advantages of nonlinear optical microscopy.
Generation of higher harmonic internal waves by oscillating spheroids
Shmakova, Natalia; Ermanyuk, Evgeny; Flór, Jan-Bert
2017-11-01
Oscillating bodies in stratified fluids may emit higher harmonics in addition to fundamental waves. In the present experimental study, we consider higher harmonics of an internal wave field generated by a horizontally oscillating spheroid in a linearly stratified fluid for moderate to high oscillation amplitudes, i.e., scaled oscillation amplitude A /a ≥0.5 , with a the minor radius of the spheroid. Three different spheroid shapes are tested. The results are discussed in the context of the different theories on the generation of higher harmonics. Higher harmonics are observed at the intersections of fundamental wave beams, and at the critical points of the topography where the topographic slope equals the wave slope. The velocity amplitudes of the fundamental, second, and third harmonic waves grow respectively linearly, quadratically, and with the third power of the scaled oscillation amplitude A /a . Though these amplitudes are generally higher when the object's slope is larger, the increase in amplitude above and below the axisymmetric oscillating objects is found to be due to the effect of focusing. In order to discern the relative importance of the harmonics to the fundamental wave, the horizontal structure of the wave amplitude is measured. The results suggest that the n th harmonic of the internal wave field is associated with a radiation diagram corresponding to a multipole of order 2n, with 2 n directions of propagation.
A Primer on the Physical Principles of Tissue Harmonic Imaging.
Anvari, Arash; Forsberg, Flemming; Samir, Anthony E
2015-01-01
Tissue harmonic imaging (THI) is a routinely used component of diagnostic ultrasonography (US). In this method, higher-frequency harmonic waves produced by nonlinear fundamental US wave propagation are used to generate images that contain fewer artifacts than those seen on conventional fundamental wave US tissue imaging. Harmonic frequencies are integer multiples of the fundamental frequency. The majority of current clinical US systems use second harmonic echoes for THI image formation. Image processing techniques (ie, bandwidth receive filtering, pulse inversion, side-by-side phase cancellation, and pulse-coded harmonics) are used to eliminate the fundamental frequency echoes, and the remaining harmonic frequency data are used to generate the diagnostic image. Advantages of THI include improved signal-to-noise ratio and reduced artifacts produced by side lobes, grating lobes, and reverberation. THI has been accepted in US practice, and variations of the technology are available on most US systems typically used for diagnostic imaging in radiologic practice. Differential THI is a further improvement that combines the advantages of THI, including superior tissue definition and reduced speckle artifact, with the greater penetration of lower frequency US, which permits high-quality harmonic imaging at greater depth than could previously be performed with conventional THI. (©)RSNA, 2015.
Voltage Harmonics Mitigation through Hybrid Active Power Filter
Directory of Open Access Journals (Sweden)
Anwer Ali Sahito
2016-01-01
Full Text Available Fast dynamic response, high efficiency, low cost and small size of power electronic converters have exponentially increased their use in modern power system which resulted in harmonically distorted voltage and currents. Voltage harmonics mainly caused by current harmonics are more dangerous as performance and expected operating life of other power system equipment are affected by harmonically distorted supply voltage. Electronic filter circuits are used to improve system power quality by mitigating adverse effects of harmonics. Hybrid filters having advantages of both passive and active filters are preferred to resolve the problem of harmonics efficiently and avoiding any chance of resonance. In this paper, a three phase three wire network is considered to supply an adjustable speed drive represented by a resistive load connected across a three phase bridge rectifier. Simulation of the considered system shows THD (Total Harmonic Distortion of 18.91 and 7.61% in supply current and voltage respectively. A HAPF (Hybrid Active Power Filter is proposed to reduce these THD values below 5% as recommended by IEEE Standard-519. P-Q theorem is used to calculate required parameters for proposed filter, which is implemented through hysteresis control. Simulation results confirm the effectiveness of the designed filter as THD for both current and voltage have reduced below allowable limit of 5%.
Elastography using harmonic ultrasonic imaging: a feasibility study.
Desai, Raghavendra Reddy; Krouskop, Thomas A; Righetti, Raffaella
2010-04-01
Tissue Harmonic Imaging (THI) is a relatively new modality that has had a significant impact in the ultrasound field. In the recent past, imaging the mechanical properties of tissues using elastography has also gained great interest. In this paper, we investigate the feasibility of combining these two state-of-the-art ultrasound-imaging modalities. The performance of elastograms obtained using harmonic ultrasonic signals is studied with simulations and compared to the performance of conventional elastograms using standard statistical methods. Experiments are used as a proof of the technical feasibility of generating tissue-harmonic elastograms using experimental harmonic signals. The results of our simulation study indicate that all image quality factors considered in this study (elastographic signal-to-noise ratio, elastographic contrast-to-noise ratio and spatial resolution) may be improved when using harmonic ultrasonic signals, provided that the ultrasound system is characterized by high bandwidth, high sampling frequency and large lateral sampling. Preliminary experimental results suggest that it is technically feasible to generate experimental elastograms using harmonic signals, provided that the sonographic signal-to-noise ratio of the pre- and postcompression harmonic frames is sufficiently high to guarantee reliable values of correlation.
Entropic Fluctuations in Thermally Driven Harmonic Networks
Jakšić, V.; Pillet, C.-A.; Shirikyan, A.
2017-02-01
We consider a general network of harmonic oscillators driven out of thermal equilibrium by coupling to several heat reservoirs at different temperatures. The action of the reservoirs is implemented by Langevin forces. Assuming the existence and uniqueness of the steady state of the resulting process, we construct a canonical entropy production functional S^t which satisfies the Gallavotti-Cohen fluctuation theorem. More precisely, we prove that there exists κ _c>1/2 such that the cumulant generating function of S^t has a large-time limit e(α ) which is finite on a closed interval [1/2-κ _c,1/2+κ _c], infinite on its complement and satisfies the Gallavotti-Cohen symmetry e(1-α )=e(α ) for all α in R. Moreover, we show that e(α ) is essentially smooth, i.e., that e'(α )→ ∓ ∞ as α → 1/2 ∓ κ _c. It follows from the Gärtner-Ellis theorem that S^t satisfies a global large deviation principle with a rate function I( s) obeying the Gallavotti-Cohen fluctuation relation I(-s)-I(s)=s for all sin R. We also consider perturbations of S^t by quadratic boundary terms and prove that they satisfy extended fluctuation relations, i.e., a global large deviation principle with a rate function that typically differs from I( s) outside a finite interval. This applies to various physically relevant functionals and, in particular, to the heat dissipation rate of the network. Our approach relies on the properties of the maximal solution of a one-parameter family of algebraic matrix Riccati equations. It turns out that the limiting cumulant generating functions of S^t and its perturbations can be computed in terms of spectral data of a Hamiltonian matrix depending on the harmonic potential of the network and the parameters of the Langevin reservoirs. This approach is well adapted to both analytical and numerical investigations.
Phase Memory Preserving Harmonics from Abruptly Autofocusing Beams
Koulouklidis, Anastasios D.; Papazoglou, Dimitris G.; Fedorov, Vladimir Yu.; Tzortzakis, Stelios
2017-12-01
We demonstrate both theoretically and experimentally that the harmonics from abruptly autofocusing ring-Airy beams present a surprising property: They preserve the phase distribution of the fundamental beam. Consequently, this "phase memory" imparts to the harmonics the abrupt autofocusing behavior, while, under certain conditions, their foci coincide in space with the one of the fundamental. Experiments agree well with our theoretical estimates and detailed numerical calculations. Our findings open the way for the use of such beams and their harmonics in strong field science.
Harmonic Mitigation Techniques Applied to Power Distribution Networks
Directory of Open Access Journals (Sweden)
Hussein A. Kazem
2013-01-01
Full Text Available A growing number of harmonic mitigation techniques are now available including active and passive methods, and the selection of the best-suited technique for a particular case can be a complicated decision-making process. The performance of some of these techniques is largely dependent on system conditions, while others require extensive system analysis to prevent resonance problems and capacitor failure. A classification of the various available harmonic mitigation techniques is presented in this paper aimed at presenting a review of harmonic mitigation methods to researchers, designers, and engineers dealing with power distribution systems.
Harmonic Distortion of Rectifier Topologies for Adjustable Speed Drives
DEFF Research Database (Denmark)
Hansen, Steffan
and to find reasonable (economical) solutions if the harmonic distortion is exceeding acceptable levels. To define some acceptable harmonic levels, the international standards IEC 61000-2-2, IEC 61000-2-4, the harmonic limiting standards EN 61000-3-2, EN 61000-3-12 (draft) and IEEE 519-1992 are reviewed...... are stored in tables. The third level is found by analytical calculations and very precise results are obtained. The fourth level is the use of circuit-based simulators, which guarantees high precision even under non-ideal conditions. By use of the numerical circuit-based simulator SABER the phase...
Wind Farm Structures’ Impact on Harmonic Emission and Grid Interaction
DEFF Research Database (Denmark)
Kocewiak, Lukasz Hubert; Hjerrild, Jesper; Bak, Claus Leth
The impact of a wind farm’s internal structures on harmonic emission at the point of common coupling and on the whole system frequency characteristic is investigated in this paper. The largest wind farms in the world, Horns Rev 2 Offshore Wind Farm and Polish Karnice Onshore Wind Farm......, are thoroughly analyzed. Different wind farm configurations are taken into consideration in order to entirely describe phenomena associated with harmonics. Some aspects of wind farm modelling for harmonic studies are also presented in this paper. The simulation results are compared with measurement data in order...
Soft-x-ray harmonic comb from relativistic electron spikes.
Pirozhkov, A S; Kando, M; Esirkepov, T Zh; Gallegos, P; Ahmed, H; Ragozin, E N; Faenov, A Ya; Pikuz, T A; Kawachi, T; Sagisaka, A; Koga, J K; Coury, M; Green, J; Foster, P; Brenner, C; Dromey, B; Symes, D R; Mori, M; Kawase, K; Kameshima, T; Fukuda, Y; Chen, L; Daito, I; Ogura, K; Hayashi, Y; Kotaki, H; Kiriyama, H; Okada, H; Nishimori, N; Imazono, T; Kondo, K; Kimura, T; Tajima, T; Daido, H; Rajeev, P; McKenna, P; Borghesi, M; Neely, D; Kato, Y; Bulanov, S V
2012-03-30
We demonstrate a new high-order harmonic generation mechanism reaching the "water window" spectral region in experiments with multiterawatt femtosecond lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving μJ/sr pulses. Harmonics are collectively emitted by an oscillating electron spike formed at the joint of the boundaries of a cavity and bow wave created by a relativistically self-focusing laser in underdense plasma. The spike sharpness and stability are explained by catastrophe theory. The mechanism is corroborated by particle-in-cell simulations.
Harmonic and attosecond pulse enhancement in the presence of noise
Feng, Li-Qiang; Chu, Tian-Shu
2012-12-01
In this paper, we theoretically investigate the effect of noise on the photoionization, the generation of the high-order harmonic and the attosecond pulse irradiated from a model He+ ion. It shows that by properly adding noise fields, such as Gaussian white noise, random light or colored noise, both the ionization probabilities (IPs) and the harmonic yields can be enhanced by several orders of magnitude. Further, by tuning the noise intensity, a stochastic resonance-like curve is observed, showing the existence of an optimal noise in the ionization enhancement process. Finally, by superposing a properly selected harmonic, an intense attosecond pulse with a duration of 67 as is directly generated.
Planar Harmonic and Monogenic Polynomials of Type A
Directory of Open Access Journals (Sweden)
Charles F. Dunkl
2016-10-01
Full Text Available Harmonic polynomials of type A are polynomials annihilated by the Dunkl Laplacian associated to the symmetric group acting as a reflection group on R N . The Dunkl operators are denoted by T j for 1 ≤ j ≤ N , and the Laplacian Δ κ = ∑ j = 1 N T j 2 . This paper finds the homogeneous harmonic polynomials annihilated by all T j for j > 2 . The structure constants with respect to the Gaussian and sphere inner products are computed. These harmonic polynomials are used to produce monogenic polynomials, those annihilated by a Dirac-type operator.
Harmonic skeleton guided evaluation of stenoses in human coronary arteries.
Yang, Yan; Zhu, Lei; Haker, Steven; Tannenbaum, Allen R; Giddens, Don P
2005-01-01
This paper presents a novel approach that three-dimensionally visualizes and evaluates stenoses in human coronary arteries by using harmonic skeletons. A harmonic skeleton is the center line of a multi-branched tubular surface extracted based on a harmonic function, which is the solution of the Laplace equation. This skeletonization method guarantees smoothness and connectivity and provides a fast and straightforward way to calculate local cross-sectional areas of the arteries, and thus provides the possibility to localize and evaluate coronary artery stenosis, which is a commonly seen pathology in coronary artery disease.
Nonlinear Diffuse fs-Pulse Reflectometry of Harmonic Upconversion Nanoparticles
Directory of Open Access Journals (Sweden)
Christian Kijatkin
2017-02-01
Full Text Available Nonlinear diffuse femtosecond-pulse reflectometry is introduced as a powerful experimental tool for the unambiguous characterization of polar and non-polar point symmetry groups of harmonic upconversion nanoparticles. Using intense ultrashort 40 femtosecond laser pulses and an appropriate figure of merit (FOM, second and third harmonic emission serve for the structural characterization of polar Yb-doped lithium niobate and non-polar titanium dioxide nanoparticles. The tool is capable of differentiating these two samples by FOM values that differ by up to 13 orders of magnitude. The general applicability to harmonic upconversion nanoparticles over a broad range of intensities and wavelength spectrum, is discussed.
Noble Gas Clusters and Nanoplasmas in High Harmonic Generation
Aladi, M; Rácz, P; Földes, I B
2015-01-01
We report a study of high harmonic generation from noble gas clusters of xenon atoms in a gas jet. Harmonic spectra were investigated as a function of backing pressure, showing spectral shifts due to the nanoplasma electrons in the clusters. At certain value of laser intensity this process may oppose the effect of the well-known ionization-induced blueshift. In addition, these cluster-induced harmonic redshifts may give the possibility to estimate cluster density and cluster size in the laser-gas jet interaction range.
Phenotype harmonization and cross-study collaboration in GWAS consortia: the GENEVA experience.
Bennett, Siiri N; Caporaso, Neil; Fitzpatrick, Annette L; Agrawal, Arpana; Barnes, Kathleen; Boyd, Heather A; Cornelis, Marilyn C; Hansel, Nadia N; Heiss, Gerardo; Heit, John A; Kang, Jae Hee; Kittner, Steven J; Kraft, Peter; Lowe, William; Marazita, Mary L; Monroe, Kristine R; Pasquale, Louis R; Ramos, Erin M; van Dam, Rob M; Udren, Jenna; Williams, Kayleen
2011-04-01
Genome-wide association study (GWAS) consortia and collaborations formed to detect genetic loci for common phenotypes or investigate gene-environment (G*E) interactions are increasingly common. While these consortia effectively increase sample size, phenotype heterogeneity across studies represents a major obstacle that limits successful identification of these associations. Investigators are faced with the challenge of how to harmonize previously collected phenotype data obtained using different data collection instruments which cover topics in varying degrees of detail and over diverse time frames. This process has not been described in detail. We describe here some of the strategies and pitfalls associated with combining phenotype data from varying studies. Using the Gene Environment Association Studies (GENEVA) multi-site GWAS consortium as an example, this paper provides an illustration to guide GWAS consortia through the process of phenotype harmonization and describes key issues that arise when sharing data across disparate studies. GENEVA is unusual in the diversity of disease endpoints and so the issues it faces as its participating studies share data will be informative for many collaborations. Phenotype harmonization requires identifying common phenotypes, determining the feasibility of cross-study analysis for each, preparing common definitions, and applying appropriate algorithms. Other issues to be considered include genotyping timeframes, coordination of parallel efforts by other collaborative groups, analytic approaches, and imputation of genotype data. GENEVA's harmonization efforts and policy of promoting data sharing and collaboration, not only within GENEVA but also with outside collaborations, can provide important guidance to ongoing and new consortia. © 2011 Wiley-Liss, Inc.
Second harmonic generation from the `centrosymmetric' crystals
Directory of Open Access Journals (Sweden)
Venkatram Nalla
2015-05-01
Full Text Available Second harmonic generation (SHG is a well known non-linear optical phenomena which can be observed only in non-centrosymmetric crystals due to non-zero hyperpolarizability. In the current work we observed SHG from a Zn(II complex which was originally thought to have crystallized in the centrosymmetric space group C2/c. This has been attributed to the unequal antiparallel packing of the metal complexes in the non-symmetric space group Cc or residual non-centrosymmetry in C2/c giving rise to polarizability leading to strong SHG. The enhancement of SHG by UV light has been attributed to the increase in non-centrosymmetry and hence polarity of packing due to strain induced in the crystals. The SHG signals measured from these crystals were as large as potassium dihydrogen phosphate crystals, KH2PO4 (KDP, and showed temperature dependence. The highest SHG efficiency was observed at 50 K. The SHG phenomenon was observed at broad wavelengths ranging from visible to below-red in these crystals.
Fighting terrorism in Africa: Benchmarking policy harmonization
Asongu, Simplice A.; Tchamyou, Vanessa S.; Minkoua N., Jules R.; Asongu, Ndemaze; Tchamyou, Nina P.
2018-02-01
This study assesses the feasibility of policy harmonization in the fight against terrorism in 53 African countries with data for the period 1980-2012. Four terrorism variables are used, namely: domestic, transnational, unclear and total terrorism dynamics. The empirical evidence is based on absolute beta catch-up and sigma convergence estimation techniques. There is substantial absence of catch-up. The lowest rate of convergence in terrorism is in landlocked countries for regressions pertaining to unclear terrorism (3.43% per annum for 174.9 years) while the highest rate of convergence is in upper-middle-income countries in domestic terrorism regressions (15.33% per annum for 39.13 years). After comparing results from the two estimation techniques, it is apparent that in the contemporary era, countries with low levels of terrorism are not catching-up their counterparts with high levels of terrorism. As a policy implication, whereas some common policies may be feasibly adopted for the fight against terrorism, the findings based on the last periodic phase (2004-2012) are indicative that country-specific policies would better pay-off in the fight against terrorism than blanket common policies. Some suggestions of measures in fighting transnational terrorism have been discussed in the light of an anticipated surge in cross-national terrorism incidences in the coming years.
Tiltrotor Vibration Reduction Through Higher Harmonic Control
Nixon, Mark W.; Kvaternik, Raymond G.; Settle, T. Ben
1997-01-01
The results of a joint NASA/Army/Bell Helicopter Textron wind-tunnel test to assess the potential of higher harmonic control (HHC) for reducing vibrations in tiltrotor aircraft operating in the airplane mode of flight, and to evaluate the effectiveness of a Bell-developed HHC algorithm called MAVSS (Multipoint Adaptive Vibration Suppression System) are presented. The test was conducted in the Langley Transonic Dynamics Tunnel using an unpowered 1/5-scale semispan aeroelastic model of the V-22 which was modified to incorporate an HHC system employing both the rotor swashplate and the wing flaperon. The effectiveness of the swashplate and the flaperon acting either singly or in combination in reducing IP and 3P wing vibrations over a wide range of tunnel airspeeds and rotor rotational speeds was demonstrated. The MAVSS algorithm was found to be robust to variations in tunnel airspeed and rotor speed, requiring only occasional on-line recalculations of the system transfer matrix. HHC had only a small (usually beneficial) effect on blade loads but increased pitch link loads by 25%. No degradation in aeroelastic stability was noted for any of the conditions tested.
Aeroelastic simulation of higher harmonic control
Robinson, Lawson H.; Friedmann, Peretz P.
1994-01-01
This report describes the development of an aeroelastic analysis of a helicopter rotor and its application to the simulation of helicopter vibration reduction through higher harmonic control (HHC). An improved finite-state, time-domain model of unsteady aerodynamics is developed to capture high frequency aerodynamic effects. An improved trim procedure is implemented which accounts for flap, lead-lag, and torsional deformations of the blade. The effect of unsteady aerodynamics is studied and it is found that its impact on blade aeroelastic stability and low frequency response is small, but it has a significant influence on rotor hub vibrations. Several different HHC algorithms are implemented on a hingeless rotor and their effectiveness in reducing hub vibratory shears is compared. All the controllers are found to be quite effective, but very differing HHC inputs are required depending on the aerodynamic model used. Effects of HHC on rotor stability and power requirements are found to be quite small. Simulations of roughly equivalent articulated and hingeless rotors are carried out, and it is found that hingeless rotors can require considerably larger HHC inputs to reduce vibratory shears. This implies that the practical implementation of HHC on hingeless rotors might be considerably more difficult than on articulated rotors.
Harmonic Balance Computations of Fan Aeroelastic Stability
Bakhle, Milind A.; Reddy, T. S. R.
2010-01-01
A harmonic balance (HB) aeroelastic analysis, which has been recently developed, was used to determine the aeroelastic stability (flutter) characteristics of an experimental fan. To assess the numerical accuracy of this HB aeroelastic analysis, a time-domain aeroelastic analysis was also used to determine the aeroelastic stability characteristics of the same fan. Both of these three-dimensional analysis codes model the unsteady flowfield due to blade vibrations using the Reynolds-averaged Navier-Stokes (RANS) equations. In the HB analysis, the unsteady flow equations are converted to a HB form and solved using a pseudo-time marching method. In the time-domain analysis, the unsteady flow equations are solved using an implicit time-marching approach. Steady and unsteady computations for two vibration modes were carried out at two rotational speeds: 100 percent (design) and 70 percent (part-speed). The steady and unsteady results obtained from the two analysis methods compare well, thus verifying the recently developed HB aeroelastic analysis. Based on the results, the experimental fan was found to have no aeroelastic instability (flutter) at the conditions examined in this study.
Higher Harmonic Control for Tiltrotor Vibration Reduction
Nixon, Mark W.; Kvaternik, Raymond G.; Settle, T. Ben
1997-01-01
The results of a joint NASA/Army/Bell Helicopter Textron wind-tunnel test to assess the potential of higher harmonic control (HHC) for reducing vibrations in tiltrotor aircraft operating in the airplane mode of flight, and to evaluate the effectiveness of a Bell-developed HHC algorithm called MAVSS (Multipoint Adaptive Vibration Suppression System) are presented. The test was conducted in the Langley Transonic Dynamics Tunnel using an unpowered 1/5- scale semispan aeroelastic model of the V-22 which was modified to incorporate an HHC system employing both the rotor swashplate and the wing flaperon. The effectiveness of the swashplate and the flaperon acting either singly or in combination in reducing 1P and 3P wing vibrations over a wide range of tunnel airspeeds and rotor rotational speeds was demonstrated. The MAVSS algorithm was found to be robust to variations in tunnel airspeed and rotor speed, requiring only occasion-al on-line recalculations of the system transfer matrix.
Second-harmonic generation in noncentrosymmetric phosphates
Li, Zhi; Liu, Qiong; Wang, Ying; Iitaka, Toshiaki; Su, Haibin; Tohyama, Takami; Yang, Zhihua; Pan, Shilie
2017-07-01
Motivated by the discovery of more and more phosphates with relatively strong nonlinear optic effect, we studied the mechanism of the second-harmonic generation (SHG) effect in several phosphates by band model and first-principles calculations. When the energy of an incident photon is much smaller than the band gap of material, the SHG is almost frequency independent and determined by the combination of Berry connection and a symmetric tensor. The SHG effect in phosphates can be enhanced by the enhancement of orbital hybridization or the reduction of charge-transfer energy, which results in widened bandwidth of occupied state and reduced band gap in the electronic structure, respectively. By the first-principles calculation on the electronic structures of several phosphates—BPO4, LiCs2PO4 , β -Li3VO4 , and β -Li3PO4 —we interpreted the relatively strong SHG effect in LiCs2PO4 and β -Li3VO4 as the consequence of the reduced charge-transfer energy compared to their parent β -Li3PO4 , while the enhanced SHG in BPO4 is resulting from enhanced orbital hybridization.
Hexagon Wilson Loop OPE and Harmonic Polylogarithms
Papathanasiou, Georgios
2013-01-01
A recent, integrability-based conjecture in the framework of the Wilson loop OPE for N=4 SYM theory, predicts the leading OPE contribution for the hexagon MHV remainder function and NMHV ratio function to all loops, in integral form. We prove that these integrals evaluate to a particular basis of harmonic polylogarithms, at any order in the weak coupling expansion. The proof constitutes an algorithm for the direct computation of the integrals, which we employ in order to obtain the full (N)MHV OPE contribution in question up to 6 loops, and certain parts of it up to 12 loops. We attach computer-readable files with our results, as well as an algorithm implementation which may be readily used to generate higher-loop corrections. The feasibility of obtaining the explicit kinematical dependence of the first term in the OPE in principle at arbitrary loop order, offers promise for the suitability of this approach as a non-perturbative description of Wilson loops/scattering amplitudes.
Bounded relative motion under zonal harmonics perturbations
Baresi, Nicola; Scheeres, Daniel J.
2017-04-01
The problem of finding natural bounded relative trajectories between the different units of a distributed space system is of great interest to the astrodynamics community. This is because most popular initialization methods still fail to establish long-term bounded relative motion when gravitational perturbations are involved. Recent numerical searches based on dynamical systems theory and ergodic maps have demonstrated that bounded relative trajectories not only exist but may extend up to hundreds of kilometers, i.e., well beyond the reach of currently available techniques. To remedy this, we introduce a novel approach that relies on neither linearized equations nor mean-to-osculating orbit element mappings. The proposed algorithm applies to rotationally symmetric bodies and is based on a numerical method for computing quasi-periodic invariant tori via stroboscopic maps, including extra constraints to fix the average of the nodal period and RAAN drift between two consecutive equatorial plane crossings of the quasi-periodic solutions. In this way, bounded relative trajectories of arbitrary size can be found with great accuracy as long as these are allowed by the natural dynamics and the physical constraints of the system (e.g., the surface of the gravitational attractor). This holds under any number of zonal harmonics perturbations and for arbitrary time intervals as demonstrated by numerical simulations about an Earth-like planet and the highly oblate primary of the binary asteroid (66391) 1999 KW4.
Harmonic resolution as a holographic quantum number
Energy Technology Data Exchange (ETDEWEB)
Bousso, Raphael
2004-01-31
The Bekenstein bound takes the holographic principle into the realm of flat space, promising new insights on the relation of non-gravitational physics to quantum gravity. This makes it important to obtain a precise formulation of the bound. Conventionally, one specifies two macroscopic quantities, mass and spatial width, which cannot be simultaneously diagonalized. Thus, the counting of compatible states is not sharply defined. The resolution of this and other formal difficulties leads naturally to a definition in terms of discretized light-cone quantization. In this form, the area difference specified in the covariant bound converts to a single quantum number, the harmonic resolution K. The Bekenstein bound then states that the Fock space sector with K units of longitudinal momentum contains no more than exp(2 pi^2 K) independent discrete states. This conjecture can be tested unambiguously for a given Lagrangian, and it appears to hold true for realistic field theories, including models arising from string compactifications. For large K, it makes contact with more conventional but less well-defined formulations.
Harmonic force field for nitro compounds.
Bellido, Edson P; Seminario, Jorge M
2012-06-01
Molecular simulations leading to sensors for the detection of explosive compounds require force field parameters that can reproduce the mechanical and vibrational properties of energetic materials. We developed precise harmonic force fields for alanine polypeptides and glycine oligopeptides using the FUERZA procedure that uses the Hessian tensor (obtained from ab initio calculations) to calculate precise parameters. In this work, we used the same procedure to calculate generalized force field parameters of several nitro compounds. We found a linear relationship between force constant and bond distance. The average angle in the nitro compounds was 116°, excluding the 90° angle of the carbon atoms in the octanitrocubane. The calculated parameters permitted the accurate molecular modeling of nitro compounds containing many functional groups. Results were acceptable when compared with others obtained using methods that are specific for one type of molecule, and much better than others obtained using methods that are too general (these ignore the chemical effects of surrounding atoms on the bonding and therefore the bond strength, which affects the mechanical and vibrational properties of the whole molecule).
Directory of Open Access Journals (Sweden)
Vodianka LIUBOV
2017-12-01
Full Text Available The article proves the necessity of harmonization of the Ukrainian labour legislation in accordance with Acquis communautaire. The main legal acts in the sphere of Ukrainian labour legislation are analyzed. Special attention in the article is devoted to the critics of the Draft Labour Code of Ukraine, also marked its contradictions, positive sides and shortcomings are indicated. Potential dangers of the protection of labour rights in Ukraine connected with the lack of regulation of activity of trade unions are identified. The conditions necessary for the successful implementation of international labour standards and principles in Ukrainian national law are proposed.
DEFF Research Database (Denmark)
Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth
2015-01-01
As the number of power electronics based systems are increasing, studies about overall stability and harmonic problems are rising. In order to analyze harmonics and stability, most research is using an analysis method, which is based on the Linear Time Invariant (LTI) approach. However, this can...... change compared to the conventional operation. In this paper, a Harmonic State Space modeling method, which is based on the Linear Time varying theory, is used to analyze different operating points of the parallel connected converters. The analyzed results show that the HSS modeling approach explicitly...
Frequency Adaptive Selective Harmonic Control for Grid-Connected Inverters
DEFF Research Database (Denmark)
Yang, Yongheng; Zhou, Keliang; Wang, Huai
2015-01-01
In this paper, a Frequency Adaptive Selective Harmonic Control (FA-SHC) scheme is proposed. The FA-SHC method is developed from a hybrid SHC scheme based on the internal model principle, which can be designed for gridconnected inverters to optimally mitigate feed-in current harmonics. The hybrid...... SHC scheme consists of multiple parallel recursive (nk±m)-order (k = 0, 1, 2, . . ., and m ≤ n/2) harmonic control modules with independent control gains, which can be optimally weighted in accordance with the harmonic distribution. The hybrid SHC thus offers an optimal trade-off among cost...... into the FA-SHC, being the proposed fractional order controller, when it is implemented with a fixed sampling rate. The FASHC is implemented by substituting the fractional order elements with the Lagrange polynomial based interpolation filters. The proposed FA-SHC scheme provides fast on-line computation...
Iceberg Harmonic Tremor, Seismometer Data, Antarctica, Version 1
National Aeronautics and Space Administration — Seismometers were placed on a 25 km by 50 km iceberg called C16 in the Ross Sea, Antarctica, to identify the Iceberg harmonic Tremor (IHT) source mechanism and to...
Effects of the Passive Harmonic Cavity on the Beam Bunch
Chang Lung Hai; Wang, Chaoen; Yeh, Meng-Shu
2005-01-01
In this paper, we present a computer tracking code, which can investigate the bunch length, energy spread and the critical current of Robinson instability under the influence of the passive harmonic cavity. The effects of the radiation damping, quantum excitation and the beam loading of the harmonic cavity are included in the computation. The calculated result shows that the beam has a constant energy spread and blows up as the beam current increases from below to over the threshold current of the Robinson instability. It also indicates that the shunt impedance of the harmonic cavity is critical for whether the harmonic cavity can reach the designed goal, a stable and lengthening beam at the design beam current.
Harmonized Tariff Schedule of the United States (2015) - Revision 1
US International Trade Commission — This dataset is the 2015 Harmonized Tariff Schedule Revision 1 effective July 1, 2015. It provides the applicable tariff rates and statistical categories for all...
Regridded Harmonized World Soil Database v1.2
National Aeronautics and Space Administration — ABSTRACT: This data set describes select global soil parameters from the Harmonized World Soil Database (HWSD) v1.2, including additional calculated parameters such...
Second Harmonic Generation in Subdiffractive Two-Dimensional Photonic Crystals
Nistor, Cristian
2013-01-01
The PhD thesis is devoted to the study of second harmonic generation of narrow beams in photonic crystals. The basic idea is that if both frequencies, the fundamental and second harmonics are in the region of self-collimation, then the second harmonics of narrow beams can be very efficient. The beams do not spread diffractively during propagation and interaction. The phase matching is ensured for all components of the interacting beams. This allows to enhance the nonlinear interaction efficiency several times. The thesis rewises the theory of self-collimation of narrow beams in photonic crystals, and presents the theory of second harmonics in photonic crystals. Calculations in photonic crystals of different configurations are presented, and the recommendations to experimental realisations are given.
A harmonic oscillator having “volleyball damping”
Mickens, R. E.; Oyedeji, K.; Rucker, S. A.
2006-05-01
Volleyball damping corresponds to linear damping up to a certain critical velocity, with zero damping above this value. The dynamics of a linear harmonic oscillator is investigated with this damping mechanism.
Comparative analysis of harmonized forest area stimates for European countries
DEFF Research Database (Denmark)
Seebach, Lucia Maria; Strobl, P.; Miguel-Ayanz, J. San
2011-01-01
Harmonized forest area information provides an important basis for environmental modelling and policy-making at both national and international levels. Traditionally, this information has been provided by national forest inventory statistics but is now increasingly complemented with remote sensing...
Strong nonlinear harmonic generation in a PZT/Aluminum resonator
Parenthoine, D.; Haumesser, L.; Vander Meulen, F.; Tran-Huu-Hue, L.-P.
2009-11-01
In this work, the extentional vibration mode of a coupled PZT/ Aluminum rod resonator is studied experimentally. Geometrical characteristics of the PZT are its 27 mm length and its 4×4 mm2 cross section area. The excitation voltage consists in sinusoidal bursts in the frequency range (20-80 kHz). Velocity measurements are performed at both ends of this system, using a laser probe. Strong harmonic distortions in the mechanical response (up to -20 dB with respect to the primary wave amplitude) have been observed. The corresponding input levels are far lower than those which are necessary to observe quadratic second harmonic generation in a free PZT resonator. The strong nonlinear effect can be explained as a super-harmonic resonance of the system due to a specific ratio between the eigen frequencies of the two parts of the resonator. Evolution of fundamental and harmonic responses are observed as a function of input levels, highlighting hysteretic behavior.
Sideband-Harmonic Instability of Paralleled Inverters with Asynchronous Carriers
DEFF Research Database (Denmark)
Yang, Dongsheng; Wang, Xiongfei; Blaabjerg, Frede
2017-01-01
Paralleled inverters with asynchronous carriers are increasingly emerging into renewable power plants and other power-electronic-based power systems. The sideband harmonics resulting from the pulse width modulation tend to be different from one inverter to another, which may trigger sideband-harmonic...... resonances among the paralleled inverters. To address the sideband-harmonic instability, the nonlinearity of the digital pulse width modulator is analyzed first in this paper based on the harmonic balance principle. It is revealed that the dynamic sideband components corresponding to a given small......-signal perturbation can be far below the Nyquist frequency, and they may not be effectively attenuated by anti-aliasing filters. A multi-frequency impedance model is then developed for the inverter, which characterizes the dynamic coupling between the perturbed frequency component and the sideband frequency component...
New Housing and the Harmonized Sales Tax: Lessons from Ontario
Bev Dahlby; Michael Smart; Benjamin Dachis
2009-01-01
Ontario’s revised plan for the tax treatment of new housing under a Harmonized Sales Tax (HST) is a significant improvement over its original proposal in the 2009 Budget, with lower economic cost and less impact on homebuyers’ decisions.
Bose gases in one-dimensional harmonic trap
Indian Academy of Sciences (India)
dimensional Bose gas confined by a harmonic potential are studied using different ensemble approaches. Combining number theory methods, a new approach is presented to calculate the occupation numbers of different energy levels in ...
Human brain networks function in connectome-specific harmonic waves.
Atasoy, Selen; Donnelly, Isaac; Pearson, Joel
2016-01-21
A key characteristic of human brain activity is coherent, spatially distributed oscillations forming behaviour-dependent brain networks. However, a fundamental principle underlying these networks remains unknown. Here we report that functional networks of the human brain are predicted by harmonic patterns, ubiquitous throughout nature, steered by the anatomy of the human cerebral cortex, the human connectome. We introduce a new technique extending the Fourier basis to the human connectome. In this new frequency-specific representation of cortical activity, that we call 'connectome harmonics', oscillatory networks of the human brain at rest match harmonic wave patterns of certain frequencies. We demonstrate a neural mechanism behind the self-organization of connectome harmonics with a continuous neural field model of excitatory-inhibitory interactions on the connectome. Remarkably, the critical relation between the neural field patterns and the delicate excitation-inhibition balance fits the neurophysiological changes observed during the loss and recovery of consciousness.
The role of legal translation in legal harmonization
Baaij, C.J.W.
2012-01-01
Papers gepresenteerd op de conferentie, 'The Role of Legal Translation in Legal Harmonization', georganiseerd in Amsterdam op 21 januari 2011, door The Amsterdam Circle for Law & Language (ACLL) en the Centre for the Study of European Contract Law (CSECL).
Harmonic Generation in a Traveling-Wave Tube
Wong, Patrick; Zhang, Peng; Lau, Y. Y.; Greening, Geoffrey; Gilgenbach, Ronald; Chernin, David; Simon, David; Hoff, Brad
2016-10-01
Crowding of electron orbits in a traveling-wave tube (TWT) may lead to significant harmonic contents in the beam current, even in the linear regime. Here, we consider a wideband TWT that exhibits gain at the second harmonic. We analytically formulate equations governing the evolution of the generation of second harmonic, including axial variations of the Pierce parameters. The second harmonic output is phase-controlled by the input signal which consists only of a fundamental frequency. Several test cases are performed and compared with simulation using the CHRISTINE code. Reasonable agreement between theory and simulation is found. Work supported by AFOSR FA9550-15-1-0097, ONR N00014-16-1-2353, and L-3 Communications Electron Device Division.
Report on dynamic speed harmonization and queue warning algorithm design.
2014-02-01
This report provides a detailed description of the algorithms that will be used to generate harmonized recommended speeds : and queue warning information in the proposed Intelligent Network Flow Optimization (INFLO) prototype. This document : describ...
Practical Solutions for Harmonics Problems Produced in the Distribution Networks
Directory of Open Access Journals (Sweden)
A. F. Zobaa
2006-03-01
Full Text Available Harmonic distortion on the power system is a modern concern due to the technological advances in silicon technology as it presents an increased non-linear loading of the power system. The effects of harmonics are well known: customers could experience major production losses due to the loss of supply as an example, on the other hand, harmonic load currents cause the utility to supply a higher real energy input then the actual real power needed to maintain a plant’s production at a certain level. The utility carries the extra transmission losses due to the harmonic currents. Different solutions will be reviewed as concepts for solving certain types of problems related to power quality. Both theoretical and a case study are presented.
Regridded Harmonized World Soil Database v1.2
National Aeronautics and Space Administration — This data set describes select global soil parameters from the Harmonized World Soil Database (HWSD) v1.2, including additional calculated parameters such as area...
Higher-order Kerr effect and harmonic cascading in gases
Bache, Morten; Eilenberger, Falk; Minardi, Stefano
2012-01-01
The higher-order Kerr effect (HOKE) has recently been advocated to explain measurements of the saturation of the nonlinear refractive index in gases. Here we show that cascaded third-harmonic generation results in an effective fifth-order nonlinearity that is negative and significant. Higher-order harmonic cascading will also occur from the HOKE, and the cascading contributions may significantly modify the observed nonlinear index change. At lower wavelengths, cascading increases the HOKE sat...
Large second-harmonic generation in thermally poled silica waveguides
DEFF Research Database (Denmark)
Arentoft, Jesper; Kristensen, Martin; Pedersen, K.
2001-01-01
We report the observation of very large second-harmonic signals from thermally poled silica waveguide samples. Secondary ion mass spectrometry measurements show that significant amounts of silver ions are injected from the top electrode during poling.......We report the observation of very large second-harmonic signals from thermally poled silica waveguide samples. Secondary ion mass spectrometry measurements show that significant amounts of silver ions are injected from the top electrode during poling....
Harmonic Structure Predicts the Enjoyment of Uplifting Trance Music.
Agres, Kat; Herremans, Dorien; Bigo, Louis; Conklin, Darrell
2016-01-01
An empirical investigation of how local harmonic structures (e.g., chord progressions) contribute to the experience and enjoyment of uplifting trance (UT) music is presented. The connection between rhythmic and percussive elements and resulting trance-like states has been highlighted by musicologists, but no research, to our knowledge, has explored whether repeated harmonic elements influence affective responses in listeners of trance music. Two alternative hypotheses are discussed, the first highlighting the direct relationship between repetition/complexity and enjoyment, and the second based on the theoretical inverted-U relationship described by the Wundt curve. We investigate the connection between harmonic structure and subjective enjoyment through interdisciplinary behavioral and computational methods: First we discuss an experiment in which listeners provided enjoyment ratings for computer-generated UT anthems with varying levels of harmonic repetition and complexity. The anthems were generated using a statistical model trained on a corpus of 100 uplifting trance anthems created for this purpose, and harmonic structure was constrained by imposing particular repetition structures (semiotic patterns defining the order of chords in the sequence) on a professional UT music production template. Second, the relationship between harmonic structure and enjoyment is further explored using two computational approaches, one based on average Information Content, and another that measures average tonal tension between chords. The results of the listening experiment indicate that harmonic repetition does in fact contribute to the enjoyment of uplifting trance music. More compelling evidence was found for the second hypothesis discussed above, however some maximally repetitive structures were also preferred. Both computational models provide evidence for a Wundt-type relationship between complexity and enjoyment. By systematically manipulating the structure of chord
Surface structure enhanced second harmonic generation in organic nanofibers
DEFF Research Database (Denmark)
Fiutowski, Jacek; Maibohm, Christian; Kostiucenko, Oksana
Second-harmonic generation upon femto-second laser irradiation of nonlinearly optically active nanofibers grown from nonsymmetrically functionalized para-quarterphenylene (CNHP4) molecules is investigated. Following growth on mica templates, the nanofibers have been transferred onto lithography......-defined regular arrays of gold square nanostructures. These nanostructure arrays induce local field enhancement, which significantly lowers the threshold for second harmonic generation in the nanofibers....
Effect of harmonic rank on the streaming of complex tones
DEFF Research Database (Denmark)
Madsen, Sara Miay Kim; Dau, Torsten; Moore, Brian C.J.
2015-01-01
The effect of the rank of the harmonics on sequential stream segregation of complex tones was investigated for normal-hearing participants with no musical training. It was hypothesized that stream segregation would be greater for tones with high pitch salience, as assessed by fundamental frequency....... There was a significant trend for less stream segregation with increasing harmonic rank. The amount of stream segregation was inversely correlated with the f0 difference limens, consistent with the hypothesis....
Harmonic Structure Predicts the Enjoyment of Uplifting Trance Music
Agres, Kat; Herremans, Dorien; Bigo, Louis; Conklin, Darrell
2017-01-01
An empirical investigation of how local harmonic structures (e.g., chord progressions) contribute to the experience and enjoyment of uplifting trance (UT) music is presented. The connection between rhythmic and percussive elements and resulting trance-like states has been highlighted by musicologists, but no research, to our knowledge, has explored whether repeated harmonic elements influence affective responses in listeners of trance music. Two alternative hypotheses are discussed, the first highlighting the direct relationship between repetition/complexity and enjoyment, and the second based on the theoretical inverted-U relationship described by the Wundt curve. We investigate the connection between harmonic structure and subjective enjoyment through interdisciplinary behavioral and computational methods: First we discuss an experiment in which listeners provided enjoyment ratings for computer-generated UT anthems with varying levels of harmonic repetition and complexity. The anthems were generated using a statistical model trained on a corpus of 100 uplifting trance anthems created for this purpose, and harmonic structure was constrained by imposing particular repetition structures (semiotic patterns defining the order of chords in the sequence) on a professional UT music production template. Second, the relationship between harmonic structure and enjoyment is further explored using two computational approaches, one based on average Information Content, and another that measures average tonal tension between chords. The results of the listening experiment indicate that harmonic repetition does in fact contribute to the enjoyment of uplifting trance music. More compelling evidence was found for the second hypothesis discussed above, however some maximally repetitive structures were also preferred. Both computational models provide evidence for a Wundt-type relationship between complexity and enjoyment. By systematically manipulating the structure of chord
Action Principle for the Generalized Harmonic Formulation of General Relativity
Brown, J David
2010-01-01
An action principle for the generalized harmonic formulation of general relativity is presented. The action is a functional of the spacetime metric and the gauge source vector. The Z4 formulation of general relativity also can be defined by an action principle, as discussed by Bona, Bona--Casas and Palenzuela. The relationship between the generalized harmonic and Z4 actions is presented in detail.
General Theory of Harmonics Generation thru Energy Transformation
Czyzyk, Don
2013-04-01
Energy, whatever its form, can be converted into an electrical signal. When analyzed is found to be comprised of a continuum of sinusoidal frequencies called a harmonic spectrum H/S. This paper addresses the question of how/why, in general, are these sinusoidal frequencies (harmonics) generated and in particular how they are produced in electronic circuits. To address this question many varied experiments were performed. Some experiments used just batteries while others used mechanical, acoustic, pneumatic, thermal, magnetic, hydraulic or photonic devices. All these devices were used to investigate the nature of harmonic generation from the perspective of the en masse movement of conduction electrons. Primarily performing electronic experiments on the envelope of a single pulse revealed that a pulse of one wavelength can be separated into basic individual segments. The energy of each individual segment, when absorbed by conduction electrons, is transformed into a unique H/S. Recombining all the individual segments that comprise a pulse envelope, involves the constructive or destructive interactions of their harmonic spectrums leading to the amplitudes of some harmonics being increased and others reduced or eliminated. The result is a pulse envelope with a different harmonic series.
Improved Active Harmonic Current Elimination Based on Voltage Detection.
Directory of Open Access Journals (Sweden)
Tianyuan Tan
Full Text Available With the increasing penetration of power electronic equipment in modern residential distribution systems, harmonics mitigation through the distributed generation (DG interfacing converters has received significant attention. Among recently proposed methods, the so-called active resonance damper (ARD and harmonic voltage compensator (HVC based on voltage detection can effectively reduce the harmonic distortions in selected areas of distribution systems. However, it is found out that when traditional ARD algorithm is used to eliminate harmonic current injected by non-linear loads, its performance is constrained by stability problems and can at most eliminate half of the load harmonic currents. Thus, inspired by the duality between ARD and HVC, this paper presents a novel improved resistive active power filter (R-APF algorithm based on integral-decoupling control. The design guideline for its parameters is then investigated through carefully analyzing the closed-loop poles' trajectory. Computer studies demonstrate that the proposed algorithm can effectively mitigate the load harmonic currents and its performance is much better than traditional ARD based on proportional control.
Digital Filter Design with Harmonics Estimation for Power Supplies
Shah, P. J.; Saxena, R.; Chawla, M. P. S.
2012-06-01
The quality of voltage waveforms is nowadays an issue of the utmost importance for power utilities and electronic equipment. Modern frequency power converters generate a wide spectrum of harmonic components, which deteriorate the quality of the delivered energy, increase the energy losses as well as decrease their liability of a power supplies. In large converters systems not only harmonics, but also considerable interharmonics strongly deteriorate the quality of the power supply voltage. The estimation of the components parameters is very important for control and protection tasks. Digital low pass filter overcome the voltage drift, temperature drift and time drift problems and can be used for harmonic detection for better utilization in real-time. Real-time detection of harmonics can be implemented using MATLAB software and developing simulation circuit set up. With the appropriate cutoff frequency f c and nth order of filter, low pass filter and band-pass filter for real-time harmonic detection can be analyzed. In this paper the aim is to design filters using different methods including Prony analysis. The monitoring of power system harmonics an important issue in the frame of modern power system management and control can be achieved easily using digital filters.
Single-shot fluctuations in waveguided high-harmonic generation.
Goh, S J; Tao, Y; van der Slot, P J M; Bastiaens, H J M; Herek, J; Biedron, S G; Danailov, M B; Milton, S V; Boller, K-J
2015-09-21
For exploring the application potential of coherent soft x-ray (SXR) and extreme ultraviolet radiation (XUV) provided by high-harmonic generation, it is important to characterize the central output parameters. Of specific importance are pulse-to-pulse (shot-to-shot) fluctuations of the high-harmonic output energy, fluctuations of the direction of the emission (pointing instabilities), and fluctuations of the beam divergence and shape that reduce the spatial coherence. We present the first single-shot measurements of waveguided high-harmonic generation in a waveguided (capillary-based) geometry. Using a capillary waveguide filled with Argon gas as the nonlinear medium, we provide the first characterization of shot-to-shot fluctuations of the pulse energy, of the divergence and of the beam pointing. We record the strength of these fluctuations vs. two basic input parameters, which are the drive laser pulse energy and the gas pressure in the capillary waveguide. In correlation measurements between single-shot drive laser beam profiles and single-shot high-harmonic beam profiles we prove the absence of drive laser beam-pointing-induced fluctuations in the high-harmonic output. We attribute the main source of high-harmonic fluctuations to ionization-induced nonlinear mode mixing during propagation of the drive laser pulse inside the capillary waveguide.
Improved Active Harmonic Current Elimination Based on Voltage Detection
Tan, Tianyuan; Dong, Shuan; Huang, Yingwei; Liu, Jian; Le, Jian; Liu, Kaipei
2016-01-01
With the increasing penetration of power electronic equipment in modern residential distribution systems, harmonics mitigation through the distributed generation (DG) interfacing converters has received significant attention. Among recently proposed methods, the so-called active resonance damper (ARD) and harmonic voltage compensator (HVC) based on voltage detection can effectively reduce the harmonic distortions in selected areas of distribution systems. However, it is found out that when traditional ARD algorithm is used to eliminate harmonic current injected by non-linear loads, its performance is constrained by stability problems and can at most eliminate half of the load harmonic currents. Thus, inspired by the duality between ARD and HVC, this paper presents a novel improved resistive active power filter (R-APF) algorithm based on integral-decoupling control. The design guideline for its parameters is then investigated through carefully analyzing the closed-loop poles’ trajectory. Computer studies demonstrate that the proposed algorithm can effectively mitigate the load harmonic currents and its performance is much better than traditional ARD based on proportional control. PMID:27295213
Harmonic filter design consideration for a tire-rubber factory
Energy Technology Data Exchange (ETDEWEB)
Zebardast, A. [Azad Univ., Tehran (Iran, Islamic Republic of). Abhar Branch]|[Sharif Univ., Tehran (Iran, Islamic Republic of); Mokhtari, H. [Azad Univ., Tehran (Iran, Islamic Republic of)
2005-07-01
Nonlinear loads and arc furnace loads are the main sources of harmonic currents in power distribution systems. Harmonic currents can cause reductions in system efficiency, and shorten the lifespan of transformers and capacitor banks. This paper provided details of a filter designed to attenuate harmonic currents at a tire company in Iran. The tire company was supplied by 3 distribution transformers and an emergency transformer. Main supply was through a 132 kV/20 kV transformer, which was connected to 2 A and B stations. The AC/DC drivers generated harmonics. Harmonic measurements were performed to determine the type and size of the required filters. A summary of site harmonic measurements was provided. A passive filter was placed at a medium voltage location. A sensitivity analysis was then performed in order to assess loading effects on filter performance. The analysis was performed on all possible configurations in the plant, including load change, capacitor bank step change, and transformer energization. Resonance conditions were also examined. Results showed that attention must be paid to the filter component rating in addition to potential resonant conditions. It was concluded that resonant conditions alter when system operating conditions change. 5 refs., 7 figs.
First harmonic injection locking of 24-GHz-oscillators
Directory of Open Access Journals (Sweden)
M. R. Kühn
2003-01-01
Full Text Available An increasing number of applications is proposed for the 24 GHz ISM-band, like automotive radar systems and short-range communication links. These applications demand for oscillators providing moderate output power of a few mW and moderate frequency stability of about 0.5%. The maximum oscillation frequency of low-cost off-theshelf transistors is too low for stable operation of a fundamental 24GHz oscillator. Thus, we designed a 24 GHz first harmonic oscillator, where the power generated at the fundamental frequency (12 GHz is reflected resulting in effective generation of output power at the first harmonic. We measured a radiated power from an integrated planar antenna of more than 1mW. Though this oscillator provides superior frequency stability compared to fundamental oscillators, for some applications additional stabilization is required. As a low-cost measure, injection locking can be used to phase lock oscillators that provide sufficient stability in free running mode. Due to our harmonic oscillator concept injection locking has to be achieved at the first harmonic, since only the antenna is accessible for signal injection. We designed, fabricated and characterized a harmonic oscillator using the antenna as a port for injection locking. The locking range was measured versus various parameters. In addition, phase-noise improvement was investigated. A theoretical approach for the mechanism of first harmonic injection locking is presented.
Harmonic Adaptability Remote Testing Method for Offshore Wind Turbines
Directory of Open Access Journals (Sweden)
Zimin Jiang
2017-11-01
Full Text Available Harmonic adaptability (HA capability is required for large-scale onshore and offshore wind turbines (WTs connected to the grid. To ensure that the distortion of the harmonic voltage at the grid access point generated by grid simulator is in accordance with the required value, this paper proposes an on-site HA remote testing method for offshore WTs to eliminate submarine cable effects. The deviation compensation method detects the integer harmonic voltage distortion based on instantaneous reactive power theory, and the deviation from the required value is compensated by series active power filter. In order to further reduce the capacity of the designed device, integer harmonics close to the resonant frequency are suppressed by the selective harmonic damping (SHD method initially. Owing to the attenuation of extreme amplification, the deviation determining the equipment capacity is decreased correspondingly. As a small synthesized impedance working for the selected frequency can suppress the amplification significantly, a low power ratings design for the SHD method can be achieved, and undesired resonance can be avoided. Simulation results indicate that the proposed method can make the harmonic distortion within the error tolerance.
An Arduino Investigation of Simple Harmonic Motion
Galeriu, Calin; Edwards, Scott; Esper, Geoffrey
2014-03-01
We cannot hope for a new generation of scientists and engineers if we don't let our young students take ownership of their scientific and engineering explorations, if we don't let them enjoy the hands-on cycle of design and production, and if we don't let them implant their creativity into a technologically friendly environment. With this educational philosophy in mind, Massimo Banzi and his team have developed and popularized the open source Arduino microcontroller board. The Arduino board has helped countless people in their science, electronics, robotics, or engineering projects, allowing them to build things that we have not even dreamed of. Physics instructors have also realized the advantages of using Arduino boards for lab experiments. The schools are saving money because the homemade experimental equipment is much cheaper than the commercial alternatives. The students are thankful for an educational experience that is more interesting, more loaded with STEM content, and more fun. As further proof of this new trend in physics education, Vernier5 is now documenting the use of their probes with Arduino boards. This is why we have developed an Arduino-based physics investigation of the simple harmonic motion (SHM) of a mass on a spring. The experimental data are collected with the help of an ultrasonic distance sensor and an Arduino Uno board. The data are then graphed and analyzed using Origin 9. This rich cross-curricular STEM activity integrates electronics, computer programming, physics, and mathematics in a way that is both experimentally exciting and intellectually rewarding.
An Approach for harmonizing European Water Portals
Pesquer, Lluís; Stasch, Christoph; Masó, Joan; Jirka, Simon; Domingo, Xavier; Guitart, Francesc; Turner, Thomas; Hinderk Jürrens, Eike
2017-04-01
A number of European funded research projects is developing novel solutions for water monitoring, modeling and management. To generate innovations in the water sector, third parties from industry and the public sector need to take up the solutions and bring them into the market. A variety of portals exists to support this move into the market. Examples on the European level are the EIP Water Online Marketplace(1), the WaterInnEU Marketplace(2), the WISE RTD Water knowledge portal(3), the WIDEST- ICT for Water Observatory(4) or the SWITCH-ON Virtual Product Market and Virtual Water-Science Laboratory(5). Further innovation portals and initiatives exist on the national or regional level, for example, the Denmark knows water platform6 or the Dutch water alliance(7). However, the different portals often cover the same projects, the same products and the same services. Since they are technically separated and have their own data models and databases, people need to duplicate information and maintain it at several endpoints. This requires additional efforts and hinders the interoperable exchange between these portals and tools using the underlying data. In this work, we provide an overview on the existing portals and present an approach for harmonizing and integrating common information that is provided across different portals. The approach aims to integrate the common in formation in a common database utilizing existing vocabularies, where possible. An Application Programming Interface allows access the information in a machine-readable way and utilizing the information in other applications beyond description and discovery purposes. (1) http://www.eip-water.eu/my-market-place (2) https://marketplace.waterinneu.org (3) http://www.wise-rtd.info/ (4) http://iwo.widest.eu (5) http://www.switch-on-vwsl.eu/ (6) http://www.rethinkwater.dk/ (7) http://wateralliance.nl/
Harmonic control: A natural way to bridge resonant control and repetitive control
DEFF Research Database (Denmark)
Zhou, Keliang; Lu, Wenzhou; Yang, Yongheng
2013-01-01
that is in compact recursive form can achieve zero tracking error at all harmonic frequencies, but yields slow convergence rates at selective harmonic frequencies. The analysis and synthesis of harmonic control are addressed. An application example of harmonic controlled three-phase PWM inverter demonstrates...
Lengths, areas and Lipschitz-type spaces of planar harmonic mappings
Chen, Shaolin; Ponnusamy, Saminathan; Rasila, Antti
2013-01-01
In this paper, we establish a three circles type theorem, involving the harmonic area function, for harmonic mappings. Also, we give bounds for length and area distortion for harmonic quasiconformal mappings. Finally, we will study certain Lipschitz-type spaces on harmonic mappings.
Output pressure and harmonic characteristics of a CMUT as function of bias and excitation voltage
DEFF Research Database (Denmark)
Lei, Anders; Diederichsen, Søren Elmin; Hansen, Sebastian Molbech
2015-01-01
The large bandwidth makes CMUT based transducers interesting for both conventional and harmonic imaging. The inherent nonlinear behavior of the CMUT, however, poses an issue for harmonic imaging as it is difficult to dissociate the harmonics generated in the tissue from the harmonic content of th...
DEFF Research Database (Denmark)
Kwon, Jun Bum; Wang, Xiongfei; Blaabjerg, Frede
2016-01-01
The increasing number of renewable energy sources in the distribution grid is becoming a major issue for utility companies since grid-connected converters are operating at different operating points due to the probabilistic characteristics of the renewable energy. Usually, the harmonics and imped...... the harmonic coupling characteristic as well as different dynamic characteristics. The theoretical modeling and analysis are verified by simulations as well as experimental results.......The increasing number of renewable energy sources in the distribution grid is becoming a major issue for utility companies since grid-connected converters are operating at different operating points due to the probabilistic characteristics of the renewable energy. Usually, the harmonics...... and impedance from other renewable energy sources are not taken carefully into account in the installation and design of the systems. It can bring an unknown harmonic instability into a multiple power sourced system and makes the analysis difficult due to the complexity of the grid network. This paper proposes...
Directory of Open Access Journals (Sweden)
Y. SAHALI
2005-09-01
Full Text Available This paper is devoted to the comparative evaluation of the two modulation strategies developed for multilevel inverters control: the harmonic elimination technique with voltage control (OHSW and the optimal minimization of the total harmonic distortion method (OMTHD, which are a very important and efficient strategies of eliminating selected harmonics from spectrum of the output voltage or minimizing its total harmonic distortion in order to improve its quality. First, we describe briefly the basic idea and concept of each technique. Then, we present a study of the performances of each one by the means of a comparison between them. Simulation has also been presented to establish the effectiveness of the proposed analysis. Finally, we conclude with scope of further work.
Studies of harmonic generation in free electron lasers
Energy Technology Data Exchange (ETDEWEB)
Goldammer, K.
2007-11-12
Nonlinear harmonic generation is one of the most interesting aspects of Free Electron Lasers under study today. It provides for coherent, high intensity radiation at higher harmonics of the FEL resonant frequency. The sources, numerical simulation and applications of harmonic radiation in cascaded High Gain Harmonic Generation FELs were the subject of this thesis. Harmonic emission in FELs originates from harmonic microbunching of the particles and the particular electron trajectory during FEL interaction. Numerical FEL simulation codes model these analytical equations and predict the performance of Free Electron Lasers with good accuracy. This thesis has relied heavily upon the FEL simulation code Genesis 1.3 which has been upgraded in the framework of this thesis to compute harmonic generation in a self-consistent manner. Tests against analytical predictions suggest that the harmonic power levels as well as harmonic gain lengths are simulated correctly. A benchmark with the FEL simulation code GINGER yields excellent agreement of the harmonic saturation length and saturation power. The new version of the simulation code Genesis was also tested against measurements from the VUV-FEL FLASH at DESY. The spectral power distributions of fundamental and third harmonic radiation were recorded at 25.9 nm and 8.6 nm, respectively. The relative bandwidths (FWHM) were in the range of 2 % for both the fundamental as well as the third harmonic, which was accurately reproduced by time-dependent simulations with Genesis. The new code was also used to propose and evaluate a new design for the BESSY Soft X-Ray FEL, a cascaded High Gain Harmonic Generation FEL proposed by BESSY in Berlin. The original design for the BESSY High Energy FEL line requires four HGHG stages to convert the initial seed laser wavelength of 297.5 nm down to 1.24 nm. A new scheme is proposed that makes use of fifth harmonic radiation from the first stage and reduces the number of HGHG stages to three. It
Perez-Diaz, Jose Luis; Diez-Jimenez, Efren; Valiente-Blanco, Ignacio; Cristache, Cristian; Alvarez-Valenzuela, Marco-Antonio; Sanchez-Garcia-Casarrubios, Juan
2015-09-01
Harmonic Drives are widely used in space mainly because of their compactness, large reduction ratio ad zero backlash. However, their use in extreme environments like in cryogenic temperatures is still a challenge. Lubrication, lifetime and fatigue are still issues under these conditions.The MAGDRIVE project, funded by the EU Space FP7 was devoted to test a new concept of harmonic drive reducer. By using the magnetic distance force interactions of magnets and ferromagnetic materials, all the conventional mechanical elements of a Harmonic Drives (teeth, flexspline and ball bearings) are substituted by contactless mechanical components (magnetic gear and superconducting magnetic bearings). The absence of contact between any moving parts prevents wear, lubricants are no longer required and the operational life time is greatly increased. As the magnetic transmission is continuous there is no backlash in the reduction. MAG SOAR Company is already providing contactless mechanical components for space applications able to operate in a wide range of temperatures.In this paper the tests results of a -1:20 ratio MAGDRIVE prototype are reported. In these tests successful operation at 40 K and 10-3 Pa was demonstrated for more than 1.5 million input cycles. A maximum torque of 3 Nm and efficiency higher than 75% at 3000 rpm were demonstrated. The maximum tested input speed was 3000 rpm -six times the previous existing record for harmonic drives at cryogenic temperature.
Attosecond lighthouse above 100 eV from high-harmonic generation of mid-infrared pulses
Kovács, K.; Negro, M.; Vozzi, C.; Stagira, S.; Tosa, V.
2017-10-01
In this paper, we numerically investigate the possibility to obtain a lighthouse emission for the attosecond pulses produced by high-order harmonics of a strong mid-infrared fundamental pulse without any optical element inserted in the path of the generating beam. The parameters of the driving pulse, focusing geometry, gas medium and detection configuration are currently experimentally feasible. Here, we study in detail the specific propagation conditions of the laser beam, and describe the exact mechanism of the sensitive space-time variation of the medium’s refractive index that lead to the dynamic wavefront rotation. This basic requirement for the lighthouse phenomenon is transmitted to the harmonic bursts, which are emitted with different divergence in successive optical half-cycles, thus can be detected in the far field at increasing distances from the optical axis. In this configuration, spectral filtering of the harmonics is not necessary, therefore the total harmonic pulse power might be used in further pump-probe experiments.
Nabekawa, Yasuo; Furukawa, Yusuke; Okino, Tomoya; Amani Eilanlou, A.; Yamanouchi, Kaoru; Midorikawa, Katsumi
2014-04-01
We report on a series of studies concerning D2 molecules irradiated by high-harmonic pulses generated from intense femtosecond laser pulses. The kinetic energy (KE) spectrum of dissociated D+ ion fragments with a scanning delay between two replica harmonic pulses exhibits specific characteristics that are completely different from a conventional interferometric autocorrelation signal. We have successfully determined and separated three distinct ionization/dissociation processes by analyzing KE-resolved interferometric fringes by Fourier transform. We call this method for analyzing the KE spectrum of ion fragments "nonlinear Fourier-transform spectroscopy (NFTS)." NFTS provides us molecular information in stationary states because it is intrinsically a frequency domain analysis. Nevertheless, we have resolved the real-time evolution of the vibrational wavepacket of D+ ions with a period of 22 fs by shortening the pulse duration of the fundamental laser pulse to 12 fs and extending the scanning delay range of two harmonic pulses to 150 fs. The probing process of the wavepacket can be described as a model with one-photon absorption of a multicolor harmonic field. We discuss a possible method of reconstructing the phase and magnitude of the wavepacket from the measured delay-KE spectrogram.
Vajpai, Sanjay Kumar; Sawangrat, Choncharoen; Yamaguchi, Osamu; Ciuca, Octav Paul; Ameyama, Kei
2016-01-01
In the present work, Co-Cr-Mo alloy compacts with a unique bimodal microstructural design, harmonic structure design, were successfully prepared via a powder metallurgy route consisting of controlled mechanical milling of pre-alloyed powders followed by spark plasma sintering. The harmonic structured Co-Cr-Mo alloy with bimodal grain size distribution exhibited relatively higher strength together with higher ductility as compared to the coarse-grained specimens. The harmonic Co-Cr-Mo alloy exhibited a very complex deformation behavior wherein it was found that the higher strength and the high retained ductility are derived from fine-grained shell and coarse-grained core regions, respectively. Finally, it was observed that the peculiar spatial/topological arrangement of stronger fine-grained and ductile coarse-grained regions in the harmonic structure promotes uniformity of strain distribution, leading to improved mechanical properties by suppressing the localized plastic deformation during straining. Copyright © 2015 Elsevier B.V. All rights reserved.
Maxfield, Lynn; Palaparthi, Anil; Titze, Ingo
2017-03-01
The traditional source-filter theory of voice production describes a linear relationship between the source (glottal flow pulse) and the filter (vocal tract). Such a linear relationship does not allow for nor explain how changes in the filter may impact the stability and regularity of the source. The objective of this experiment was to examine what effect unpredictable changes to vocal tract dimensions could have on fo stability and individual harmonic intensities in situations in which low frequency harmonics cross formants in a fundamental frequency glide. To determine these effects, eight human subjects (five male, three female) were recorded producing fo glides while their vocal tracts were artificially lengthened by a section of vinyl tubing inserted into the mouth. It was hypothesized that if the source and filter operated as a purely linear system, harmonic intensities would increase and decrease at nearly the same rates as they passed through a formant bandwidth, resulting in a relatively symmetric peak on an intensity-time contour. Additionally, fo stability should not be predictably perturbed by formant/harmonic crossings in a linear system. Acoustic analysis of these recordings, however, revealed that harmonic intensity peaks were asymmetric in 76% of cases, and that 85% of fo instabilities aligned with a crossing of one of the first four harmonics with the first three formants. These results provide further evidence that nonlinear dynamics in the source-filter relationship can impact fo stability as well as harmonic intensities as harmonics cross through formant bandwidths. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.
Ensuring a successful family business management succession
Desbois, Joris
2016-01-01
Succession is the biggest long-term challenge that most family businesses face. Indeed, leaders ‘disposition to plan for their succession is frequently the key factor defining whether their family business subsists or stops. The research seeks to find out how to manage successfully the business management succession over main principles. This work project aims at researching the key points relevant to almost all family firms, to have a viable succession transition and positioni...
Ultracision Harmonic Scalpel in oral and oropharyngeal cancer resection.
Tirelli, Giancarlo; Del Piero, Giulia Carolina; Perrino, Fiorella
2014-07-01
The aim of this prospective study was to evaluate the benefits and risks when using an Ultracision Harmonic Scalpel in the surgical treatment of oral and oropharyngeal carcinomas. Prospective non-randomized. Clinica Otorinolaringoiatrica, Azienda Ospedaliero-Universitaria. Trieste, Italy. In this study, conducted from April 2008 to August 2010, 36 consecutive patients underwent resection of oral or oropharyngeal carcinoma and lateral lymphadenectomy using the Ultracision Harmonic Scalpel. Evaluation criteria included length of the surgical procedure, intraoperative blood loss, quantity of neck drainage on the first, second and third postoperative days, postoperative complications, and a subjective assessment of postoperative pain and lymphatic oedema of the neck. Results were compared with previous surgical procedures carried out between May 2006 and March 2008 using cold knife and bipolar haemostasis (n = 36) when the Harmonic Scalpel was not available. In patients treated with the Harmonic Scalpel, operating time was significantly reduced, both for resection of the carcinoma and the lateral lymphadenectomy. Intraoperative blood loss and neck drainage on the first and second postoperative days were significantly less and pain scores were significantly lower than in the cold knife group. No postoperative complications were noted in the Harmonic Scalpel group. The only disadvantage noted in the Harmonic Scalpel group was the high incidence of lymphatic oedema of the neck. Use of the Harmonic Scalpel during resection of oral cancer and lateral lymphadenectomy is safe and confers some advantages over conventional methods. Copyright © 2013 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
Cluster size dependence of high-order harmonic generation
Tao, Y.; Hagmeijer, R.; Bastiaens, H. M. J.; Goh, S. J.; van der Slot, P. J. M.; Biedron, S. G.; Milton, S. V.; Boller, K.-J.
2017-08-01
We investigate high-order harmonic generation (HHG) from noble gas clusters in a supersonic gas jet. To identify the contribution of harmonic generation from clusters versus that from gas monomers, we measure the high-order harmonic output over a broad range of the total atomic number density in the jet (from 3×1016 to 3 × 1018 {{cm}}-3) at two different reservoir temperatures (303 and 363 K). For the first time in the evaluation of the harmonic yield in such measurements, the variation of the liquid mass fraction, g, versus pressure and temperature is taken into consideration, which we determine, reliably and consistently, to be below 20% within our range of experimental parameters. By comparing the measured harmonic yield from a thin jet with the calculated corresponding yield from monomers alone, we find an increased emission of the harmonics when the average cluster size is less than 3000. Using g, under the assumption that the emission from monomers and clusters add up coherently, we calculate the ratio of the average single-atom response of an atom within a cluster to that of a monomer and find an enhancement of around 100 for very small average cluster size (∼200). We do not find any dependence of the cut-off frequency on the composition of the cluster jet. This implies that HHG in clusters is based on electrons that return to their parent ions and not to neighboring ions in the cluster. To fully employ the enhanced average single-atom response found for small average cluster sizes (∼200), the nozzle producing the cluster jet must provide a large liquid mass fraction at these small cluster sizes for increasing the harmonic yield. Moreover, cluster jets may allow for quasi-phase matching, as the higher mass of clusters allows for a higher density contrast in spatially structuring the nonlinear medium.
Mahmoudian, A.; Scales, W. A.; Bernhardt, P. A.; Samimi, A.; Kendall, E.; Ruohoniemi, J. M.; Isham, B.; Vega-Cancel, O.; Bordikar, M.
2013-03-01
Stimulated electromagnetic emissions (SEEs) are secondary radiation produced during active space experiments in which the ionosphere is actively heated with high power high frequency (HF) ground-based radio transmitters. Recently, there has been significant interest in ion gyro-harmonic structuring the SEE spectrum due to the potential for new diagnostic information available such as electron acceleration and creation of artificial ionization layers. These relatively recently discovered gyro-harmonic spectral features have almost exclusively been studied when the transmitting frequency is near the second electron gyro-harmonic frequency. The first extensive systematic experimental investigations of the possibility of these spectral features for third electron gyro-harmonic heating are provided here. Discrete spectral features shifted from the transmit frequency ordered by harmonics of the ion gyro-frequency were observed for third electron gyro-harmonic heating for the first time at a recent campaign at the High Frequency Active Auroral Research Program (HAARP) facility. These features were also closely correlated with a broader band feature at a larger frequency shift from the transmit frequency known as the downshifted peak (DP). The power threshold of these spectral features was measured, as well as their behavior with heater beam angle, and proximity of the transmit frequency to the third electron gyro-harmonic frequency. Comparisons were also made with similar spectral features observed during second electron gyro-harmonic heating during the same campaign. A theoretical model is provided that interprets these spectral features as resulting from parametric decay instabilities in which the pump field ultimately decays into high frequency upper hybrid/electron Bernstein and low frequency neutralized ion Bernstein IB and/or obliquely propagating ion acoustic waves at the upper hybrid interaction altitude. Coordinated optical and SEE observations were carried out
DEFF Research Database (Denmark)
Micallef, A.; Apap, M.; Spitero-Stanies, C.
2012-01-01
or active filters to selectively compensate harmonic frequencies. However, by adding suitable control strategies to the inverters connected to the microgrid, the power quality of the microgrid can be improved without the installation of any additional equipment. In this paper, a capacitive virtual impedance......This paper focuses on the islanded operation of microgrids. In this mode of operation, the microsources are required to cooperate autonomously to regulate the local grid voltage and frequency. Droop control is typically used to achieve this autonomous voltage and frequency regulation. Inverters...... having LCL output filters would cause voltage distortion to be present at the PCC of the local load when non-linear current is supplied to the load due to the voltage drop across the grid side inductor. Techniques to reduce the output voltage distortion typically consist of installing either passive...
Borne, Adrien; Katsura, Tomotaka; Félix, Corinne; Doppagne, Benjamin; Segonds, Patricia; Bencheikh, Kamel; Levenson, Juan Ariel; Boulanger, Benoit
2016-01-01
Several third-harmonic generation processes were performed in a single step-index germanium-doped silica optical fiber under intermodal phase-matching conditions. The nanosecond fundamental beam range between 1400 and 1600 nm. The transverse distributions of the energy were successfully modeled in the form of Ince-Gauss modes, pointing out some ellipticity of fiber core. From these experiments and theoretical calculations, we discuss the implementation of frequency degenerated triple photon generation that shares the same phase-matching condition as third-harmonic generation, which is its reverse process.
Even harmonic generation in isotropic media of dissociating homonuclear molecules
Silva, R E F; Morales, F; Smirnova, O; Ivanov, M; Martín, F
2016-01-01
Isotropic gases irradiated by long pulses of intense IR light can generate very high harmonics of the incident field. It is generally accepted that, due to the symmetry of the generating medium, be it an atomic or an isotropic molecular gas, only odd harmonics of the driving field can be produced. Here we show how the interplay of electronic and nuclear dynamics can lead to a marked breakdown of this standard picture: a substantial part of the harmonic spectrum can consist of even rather than odd harmonics. We demonstrate the effect using ab-initio solutions of the time-dependent Schr\\"odinger equation for $H$$_2$$^+$ and its isotopes in full dimensionality. By means of a simple analytical model, we identify its physical origin, which is the appearance of a permanent dipole moment in dissociating homonuclear molecules, caused by light-induced localization of the electric charge during dissociation. The effect arises for sufficiently long laser pulses and the region of the spectrum where even harmonics are pro...
Noninvasive tissue temperature estimation using nonlinear ultrasound harmonics
Maraghechi, Borna; Kolios, Michael C.; Tavakkoli, Jahan
2017-03-01
Non-invasive tissue temperature estimation is important in thermal therapies for having an efficient treatment. A noninvasive ultrasonic technique for monitoring tissue temperature changes is proposed based on the changes in the harmonics of ultrasound backscatter as a function of temperature. The backscattered pressure amplitudes of the fundamental frequency (p1), the second (p2) and the third (p3) harmonics generated by nonlinear ultrasound propagation and the ratios of the second and the third harmonics over the fundamental frequency (p2/p1 and p3/p1) were investigated as a function of temperature. The acoustic harmonics were generated and detected with a commercial high frequency ultrasound imaging system in pulse-echo mode. The experiments were performed on tissue-mimicking gel phantoms and ex vivo bovine muscle tissues. The temperature was increased from 26°C to 46°C in increments of 2°C. The average values of p1, p2, p3, p2/p1, p3/p1 increased by 14%, 50%, 117%, 37% and 92% for the gel phantoms, and for the tissue samples increased by 29%, 50%, 170%, 10% and 109%, respectively. The results indicate that the harmonic amplitudes and their ratios are highly sensitive to propagation medium's temperature and could potentially be used for noninvasive ultrasound thermometry.
Symmetric functions and B sub N -invariant spherical harmonics
Dunkl, C F
2002-01-01
The wavefunctions of a quantum isotropic harmonic oscillator modified by reflecting barriers at the coordinate planes in N-dimensional space can be expressed in terms of certain generalized spherical harmonics. These are associated with a product-type weight function on the sphere. Their analysis is carried out by means of differential-difference operators. The symmetries of this system involve the Weyl group of type B, generated by permutations and changes of sign of the coordinates. A new basis for symmetric functions as well as an explicit transition matrix to the monomial basis is constructed. This basis leads to a basis for invariant spherical harmonics. The determinant of the Gram matrix for the basis in the natural inner product over the sphere is evaluated. When the underlying parameter is specialized to zero, the basis consists of ordinary spherical harmonics with cube group symmetry, as used for wavefunctions of electrons in crystals. The harmonic oscillator can also be considered as a degenerate in...
Prototype for harmonic compensation in three phase systems
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Alfonso Alzate Gómez
2017-02-01
Full Text Available Context: The traditional methodology for the control of harmonics consists in the use of passive filters tuned to the harmonic components to be eliminated. Passive filters require a frequency-demanding design to avoid resonance phenomena with other elements and they not respond to changes in the dynamics of the electric power system. Method: A best-performing solution alternative is parallel power active filters. These filters, unlike passive filters, inject compensation currents into the network and have adaptation to changes in operating conditions. The implementation of an active filter involves hardware development but also software development. Algorithms are required for calculation of compensation currents and dc bus voltage control. Results: In this work a prototype for the harmonic compensation of 5kVA is designed and built in three phase distribution systems of 220V. The hardware fundamental elements are: coupling coil, capacitor, semiconductor devices and controller. The control algorithms that are responsible for the operation of the active filter at each instant of time are PQ theory, Linear Control-PWM and PI Control. Conclusions: The active power filters are a solution to the presence of harmonics in power systems. They compensate the harmonics generated by nonlinear loads and they don‘t have resonance problems and good dynamic response.
Two dimensional kinetic analysis of electrostatic harmonic plasma waves
Energy Technology Data Exchange (ETDEWEB)
Fonseca-Pongutá, E. C.; Ziebell, L. F.; Gaelzer, R. [Instituto de Física, UFRGS, 91501-970 Porto Alegre, RS (Brazil); Yoon, P. H. [IPST, University of Maryland, College Park, Maryland 20742 (United States); SSR, Kyung Hee University, Yongin, Gyeonggi 446-701 (Korea, Republic of)
2016-06-15
Electrostatic harmonic Langmuir waves are virtual modes excited in weakly turbulent plasmas, first observed in early laboratory beam-plasma experiments as well as in rocket-borne active experiments in space. However, their unequivocal presence was confirmed through computer simulated experiments and subsequently theoretically explained. The peculiarity of harmonic Langmuir waves is that while their existence requires nonlinear response, their excitation mechanism and subsequent early time evolution are governed by essentially linear process. One of the unresolved theoretical issues regards the role of nonlinear wave-particle interaction process over longer evolution time period. Another outstanding issue is that existing theories for these modes are limited to one-dimensional space. The present paper carries out two dimensional theoretical analysis of fundamental and (first) harmonic Langmuir waves for the first time. The result shows that harmonic Langmuir wave is essentially governed by (quasi)linear process and that nonlinear wave-particle interaction plays no significant role in the time evolution of the wave spectrum. The numerical solutions of the two-dimensional wave spectra for fundamental and harmonic Langmuir waves are also found to be consistent with those obtained by direct particle-in-cell simulation method reported in the literature.
The Tax harmonization in open regionalism ; The European model
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Mouloud MELIKAOUI
2014-06-01
Full Text Available This research examines the subject of alternative regionalism or open regionalism and reality within the multilateral trading system, based on growing liberalization of trade, and the problem of compatibility between them, as well as the limits of economic policy harmonization in the framework of Open regionalism, special tax harmonization, in the light of economic and tax disparities of the Member States, with an overview of the European tax harmonization and limits. The Study concluded the importance of tax harmonization as a tool by activation of the concept of open regionalism, through facilitating capitals flows and investments between member states and reduction of the négatives phenomena of tax. It recommended the need to emphasizing on the importance of gradually harmonization for tax policy, and expand the rule of tax treaties and exchange of tax information and experiences between countries, This is in light a holistic approach to other economic policies as a the exchange rate policy and monetary policy, just as is the case in the European model.
The graph theoretical analysis of the SSVEP harmonic response networks.
Zhang, Yangsong; Guo, Daqing; Cheng, Kaiwen; Yao, Dezhong; Xu, Peng
2015-06-01
Steady-state visually evoked potentials (SSVEP) have been widely used in the neural engineering and cognitive neuroscience researches. Previous studies have indicated that the SSVEP fundamental frequency responses are correlated with the topological properties of the functional networks entrained by the periodic stimuli. Given the different spatial and functional roles of the fundamental frequency and harmonic responses, in this study we further investigated the relation between the harmonic responses and the corresponding functional networks, using the graph theoretical analysis. We found that the second harmonic responses were positively correlated to the mean functional connectivity, clustering coefficient, and global and local efficiencies, while negatively correlated with the characteristic path lengths of the corresponding networks. In addition, similar pattern occurred with the lowest stimulus frequency (6.25 Hz) at the third harmonic responses. These findings demonstrate that more efficient brain networks are related to larger SSVEP responses. Furthermore, we showed that the main connection pattern of the SSVEP harmonic response networks originates from the interactions between the frontal and parietal-occipital regions. Overall, this study may bring new insights into the understanding of the brain mechanisms underlying SSVEP.
Neck dissection with harmonic scalpel and electrocautery? A randomised study.
Verma, Roshan K; Mathiazhagan, Arulalan; Panda, Naresh K
2017-10-01
Is the use of harmonic scalpel for neck dissection useful? Literature search did not show a single, prospective, randomised control trial. We intended to study the role of harmonic scalpel in neck dissection and compare it with conventional electrocautery technique for oral cavity carcinoma. 40 patients undergoing selective neck dissection for primary oral cavity malignancy were enrolled in this study. The harmonic scalpel (HS) group consisted of 20 patients, and the electrocautery technique (ET) group comprised of 20 patients. The following variables were examined: intraoperative blood loss, operative time, number of ligatures used, postoperative drain, and postoperative hospital stay. Intraoperative blood loss was found to be significantly reduced in harmonic scalpel group as compared to electrocautery group. However, we found no difference in other parameters like operative time, postop drain, postoperative hospital stay and number of ligatures used between both groups. Harmonic scalpel for neck dissection is associated with significantly lesser intraoperative blood loss as compared to electrocautery. There is no effect on operative time and postoperative hospital stay in both groups. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Secondary magnetic field harmonics dependence on vacuum beam chamber geometry
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S. Y. Shim
2013-08-01
Full Text Available The harmonic magnetic field properties due to eddy currents have been studied with respect to the geometry of the vacuum beam chamber. We derived a generalized formula enabling the precise prediction of any field harmonics generated by eddy currents in beam tubes with different cross-sectional geometries. Applying our model to study the properties of field harmonics in beam tubes with linear dipole magnetic field ramping clearly proved that the circular cross section tube generates only a dipole field from eddy currents. The elliptic tube showed noticeable magnitudes of sextupole and dipole fields. We demonstrate theoretically that it is feasible to suppress the generation of the sextupole field component by appropriately varying the tube wall thickness as a function of angle around the tube circumference. This result indicates that it is possible to design an elliptical-shaped beam tube that generates a dipole field component with zero magnitude of sextupole. In a rectangular-shaped beam tube, one of the selected harmonic fields can be prevented if an appropriate wall thickness ratio between the horizontal and vertical tube walls is properly chosen. Our generalized formalism can be used for optimization of arbitrarily complex-shaped beam tubes, with respect to suppression of detrimental field harmonics.
The Local Stellar Velocity Field via Vector Spherical Harmonics
Makarov, V. V.; Murphy, D. W.
2007-01-01
We analyze the local field of stellar tangential velocities for a sample of 42,339 nonbinary Hipparcos stars with accurate parallaxes, using a vector spherical harmonic formalism.We derive simple relations between the parameters of the classical linear model (Ogorodnikov-Milne) of the local systemic field and low-degree terms of the general vector harmonic decomposition. Taking advantage of these relationships, we determine the solar velocity with respect to the local stars of (V(sub X), V(sub Y), V(sub Z)) = (10.5, 18.5, 7.3) +/- 0.1 km s(exp -1) not for the asymmetric drift with respect to the local standard of rest. If only stars more distant than 100 pc are considered, the peculiar solar motion is (V(sub X), V(sub Y), V(sub Z)) = (9.9, 15.6, 6.9) +/- 0.2 km s(exp -1). The adverse effects of harmonic leakage, which occurs between the reflex solar motion represented by the three electric vector harmonics in the velocity space and higher degree harmonics in the proper-motion space, are eliminated in our analysis by direct subtraction of the reflex solar velocity in its tangential components for each star...
Opportunities for regional harmonization of appliance standards and l abeling program
Energy Technology Data Exchange (ETDEWEB)
McNeil, Michael A.
2003-09-01
The South Asian Regional Initiative for Energy (SARI/Energy) calls for a series of activities to promote Energy Efficiency Standards and Labeling (EES&L) of end use appliances in the region. In pursuit of this goal, the project supports several seminars and meetings that bring together policymakers and stakeholders from throughout the region. The purpose of these gatherings is to encourage a dialogue among participants as to the benefits and barriers associated with EES&L programs. In addition, it is the role of the program organizers to provide participants with the technical details necessary to make progress towards effective efficiency programs. One component of the initiative is to encourage the harmonization (alignment) of existing program components, and the pursuit of new programs coordinated at the regional level. In support of this goal, the report provides information aimed at motivating and enabling cooperative activities which will provide concrete benefits to programs in each country, whether well developed, or still in the initial planning stage. It should be emphasized that the underlying objective of the harmonization component of the SARI/Energy project is to increase the potential for success of EES&L programs of all countries involved, and to reduce burdens on manufacturers, exporters and importers in each country. Harmonization ''for it's own sake'' is not desirable, nor is it suggested that policymakers should bring their programs in line with international norms if doing so would present a disadvantage to their own efficiency programs, or to commercial interests within their country. If there is no such disadvantage, however, the program encourages alignment of policies and provides a forum at which this alignment can be pursued. The report covers several main topics, with varying emphasis. First, a general discussion of the motivation for an explicit policy of regional harmonization is given. Next, the current status
Directory of Open Access Journals (Sweden)
Elena S. Ratushnyak
2014-01-01
Full Text Available The article provides the tax systems of the countries of the customs union of Belarus, Kazakhstan and Russia, reveals the differences and identifies the need for harmonization and convergence of the structures and principles of taxation, the general tax reforms and harmonization of fiscal policies of member countries in order to increase the investment attractiveness and competitiveness of the national economies in the process of development and integration. The comparison of the existing tax systems of the three countries revealed differences affecting the implementation and development of the foreign economic activity of companies in terms of the common market, in particular, the main obstacles to doing business are high tax rates as well as different rates of value added tax (further - VAT regarding indirect taxation, because this tax is the major budget revenue generating tax involved in the pricing and resulted in decreasing in the export potential of the country. One of the major exporters' obstacles of CU, revealed in the paper, is a VAT refund in export transactions, preventing the development of export activity, which reduces the competitiveness of CU on the foreign markets. The harmonization success of fiscal policy depends on the government, and the institution body taking the harmonization, - this paper looks at the necessity of such harmonization among the three countries of customs union, which at present has interstate form while supranational regulation of Eurasian Economic Commission is absent, since it does not have such empowerment. The paper finds the main tax policy directions of harmonization of customs union countries focused on eliminating of the barriers and for easy the implementation of a process for foreign trade enterprises, the development of the participating countries investment attractiveness, the enhancing the products competitiveness, the development of the export activities efficiency on the whole for the
Harmonic Instability Source Identification in Large Wind Farms
DEFF Research Database (Denmark)
Ebrahimzadeh, Esmaeil; Blaabjerg, Frede; Wang, Xiongfei
2017-01-01
A large-scale power electronics based power system like a wind farm introduces the passive and active impedances. The interactions between the active and passive impedances can lead to harmonic-frequency oscillations above the fundamental frequency, which can be called harmonic instability....... This paper presents an approach to identify which wind turbine and which bus has more contribution to the harmonic instability problems. In the approach, a wind farm is modeled as a Multi-Input Multi-Output (MIMO) dynamic system. The poles of the MIMO transfer matrix are used to predict the system...... instability and the eigenvalues sensitivity analysis in respect to the elements of the MIMO matrix locates the most influencing buses of the wind farm. Time-domain simulations in PSCAD software environment for a 400-MW wind farm validate that the presented approach is an effective tool to determine the main...
Fundamental and Harmonic Oscillations in Neighboring Coronal Loops
Li, Hongbo; Liu, Yu; Vai Tam, Kuan
2017-06-01
We present observations of multimode (fundamental and harmonic) oscillations in a loop system, which appear to be simultaneously excited by a GOES C-class flare. Analysis of the periodic oscillations reveals that (1) the primary loop with a period of P a ≈ 4 minutes and a secondary loop with two periods of P a ≈ 4 minutes and P b ≈ 2 minutes are detected simultaneously in closely spaced loop strands; (2) both oscillation components have their peak amplitudes near the loop apex, while in the second loop the low-frequency component P a dominates in a loop segment that is two times larger than the high-frequency component P b ; (3) the harmonic mode P b shows the largest deviation from a sinusoidal loop shape at the loop apex. We conclude that multiple harmonic modes with different displacement profiles can be excited simultaneously even in closely spaced strands, similar to the overtones of a violin string.
The fractal harmonic law and its application to swimming suit
Directory of Open Access Journals (Sweden)
Kong Hai-Yan
2012-01-01
Full Text Available Decreasing friction force between a swimming suit and water is the key factor to design swimming suits. Water continuum mechanics forbids discontinuous fluids, but in angstrom scale water is indeed discontinuous. Swimming suit is smooth on large scale, but it is discontinuous when the scale becomes smaller. If fractal dimensions of swimming suit and water are the same, a minimum of friction force is predicted, which means fractal harmonization. In the paper, fractal harmonic law is introduced to design a swimsuit whose surface fractal dimensions on a macroscopic scale should be equal to or closed to the water's fractal dimensions on an Angstrom scale. Various possible microstructures of fabric are analyzed and a method to obtain perfect fractal structure of fabric is proposed by spraying nanofibers to its surface. The fractal harmonic law can be used to design a moving surface with a minimal friction.
Solitons and second harmonic radiation in type III bursts
Papadopoulos, K.; Freund, H. P.
1978-01-01
The emission at the second harmonic of the plasma frequency from self-consistent Langmuir solitons is calculated. The theory predicts, in a natural way, the observed transition from the region where the intensity is linearly proportional to the electron flux to the region where the radio intensity is proportional to the square of the electron flux. A detailed comparison of the radiation observed at the second harmonic for the burst of 18:10 UT March 31, 1976, with the one expected on the assumption of radiation from solitons, using the correlated in situ measurements of the electric fields at the second harmonic, and their spatial structure, provides strong evidence that, for the first time, Langmuir solitons have been observed in space.
Enhancement of Non-Stationary Speech using Harmonic Chirp Filters
DEFF Research Database (Denmark)
Nørholm, Sidsel Marie; Jensen, Jesper Rindom; Christensen, Mads Græsbøll
2015-01-01
the non-stationarity nature of voiced speech into account via linear constraints. This is facilitated by imposing a harmonic chirp model on the speech signal. As an implicit part of the filter design, the noise statistics are also estimated based on the observed signal and parameters of the harmonic chirp......In this paper, the issue of single channel speech enhancement of non-stationary voiced speech is addressed. The non-stationarity of speech is well known, but state of the art speech enhancement methods assume stationarity within frames of 20–30 ms. We derive optimal distortionless filters that take...... model. Simulations on real speech show that the chirp based filters perform better than their harmonic counterparts. Further, it is seen that the gain of using the chirp model increases when the estimated chirp parameter is big corresponding to periods in the signal where the instantaneous fundamental...
High-order harmonic generation in laser plasma plumes
Ganeev, Rashid A
2013-01-01
This book represents the first comprehensive treatment of high-order harmonic generation in laser-produced plumes, covering the principles, past and present experimental status and important applications. It shows how this method of frequency conversion of laser radiation towards the extreme ultraviolet range matured over the course of multiple studies and demonstrated new approaches in the generation of strong coherent short-wavelength radiation for various applications. Significant discoveries and pioneering contributions of researchers in this field carried out in various laser scientific centers worldwide are included in this first attempt to describe the important findings in this area of nonlinear spectroscopy. "High-Order Harmonic Generation in Laser Plasma Plumes" is a self-contained and unified review of the most recent achievements in the field, such as the application of clusters (fullerenes, nanoparticles, nanotubes) for efficient harmonic generation of ultrashort laser pulses in cluster-containin...
Theory of second-harmonic generation in silica nanowires
DEFF Research Database (Denmark)
Lægsgaard, Jesper
2010-01-01
The possibility of second-harmonic generation based on surface dipole and bulk multipole nonlinearities in silica nanowires is investigated numerically. Both circular and microstructured nanowires are considered. Phase matching is provided by propagating the pump field in the fundamental mode......, while generating the second harmonic in one of the modes of the LP11 multiplet. This is shown to work in both circular and microstructured nanowires, although only one of the LP11 modes can be phase-matched in the microstructure. The prospect of obtaining large conversion efficiencies in silica......-based nanowires is critically discussed, based on simulations of second-harmonic generation in nanowires with a fluctuating phase-matching wavelength. It is concluded that efficient wavelength conversion will either require strong improvements in the nanowire uniformity, or an increase of the second...
Harmonics generation near ion-cyclotron frequency of ECR plasma
Chowdhury, Satyajit; Biswas, Subir; Chakrabarti, Nikhil; Pal, Rabindranath
2017-10-01
Wave excitation at different frequency regime is employed in the MaPLE device ECR plasma for varied excitation amplitude. At very low amplitude excitation, mainly fundamental frequency mode of the exciter signal frequency comes into play. With the increase in amplitude of applied perturbation, harmonics are generated and dominant over the fundamental frequency mode. There is a fixed critical amplitude of exciter to yield the harmonics and is independent of applied frequency. Observed harmonics and the main frequency mode has propagation characteristics and are discussed here. Exact mode number and propagation nature are also tried to measure in the experiment. Detailed experimental results will be presented. Department of Science and Technology of Government of India (Project No. SB/S2/HEP-005/2014).
Predicting Harmonic Distortion of Multiple Converters in a Power System
Directory of Open Access Journals (Sweden)
P. M. Ivry
2017-01-01
Full Text Available Various uncertainties arise in the operation and management of power systems containing Renewable Energy Sources (RES that affect the systems power quality. These uncertainties may arise due to system parameter changes or design parameter choice. In this work, the impact of uncertainties on the prediction of harmonics in a power system containing multiple Voltage Source Converters (VSCs is investigated. The study focuses on the prediction of harmonic distortion level in multiple VSCs when some system or design parameters are only known within certain constraints. The Univariate Dimension Reduction (UDR method was utilized in this study as an efficient predictive tool for the level of harmonic distortion of the VSCs measured at the Point of Common Coupling (PCC to the grid. Two case studies were considered and the UDR technique was also experimentally validated. The obtained results were compared with that of the Monte Carlo Simulation (MCS results.
Development of a virtual metrology method using plasma harmonics analysis
Directory of Open Access Journals (Sweden)
H. Jun
2017-07-01
Full Text Available A virtual metrology technique based on plasma harmonics is developed for predicting semiconductor processes. From a plasma process performed by 300 mm photoresist stripper equipment, a strong correlation is found between optical plasma harmonics intensities and the process results, such as the photoresist strip rate and strip non-uniformity. Based on this finding, a general process prediction model is developed. The developed virtual metrology model shows that the R-squared (R2 values between the measured and predicted process results are 95% and 64% for the photoresist strip rate and photoresist strip non-uniformity, respectively. This is the first research on process prediction based on optical plasma harmonics analysis, and the results can be applied to semiconductor processes such as dry etching and plasma enhanced chemical vapor deposition.
Development of a virtual metrology method using plasma harmonics analysis
Jun, H.; Shin, J.; Kim, S.; Choi, H.
2017-07-01
A virtual metrology technique based on plasma harmonics is developed for predicting semiconductor processes. From a plasma process performed by 300 mm photoresist stripper equipment, a strong correlation is found between optical plasma harmonics intensities and the process results, such as the photoresist strip rate and strip non-uniformity. Based on this finding, a general process prediction model is developed. The developed virtual metrology model shows that the R-squared (R2) values between the measured and predicted process results are 95% and 64% for the photoresist strip rate and photoresist strip non-uniformity, respectively. This is the first research on process prediction based on optical plasma harmonics analysis, and the results can be applied to semiconductor processes such as dry etching and plasma enhanced chemical vapor deposition.
Power Quality and Harmonic Analysis of End User Devices
Directory of Open Access Journals (Sweden)
Sonia Leva
2012-12-01
Full Text Available Among the non-linear loads used in household, Compact Fluorescent Lamps (CFLs and LED lamps are becoming more widespread, while incandescent lamps are intended to be replaced by these types of lighting devices. LEDs and CFLs are significantly more efficient and economical than incandescent lamps, and are expected to be used in 100% of residential lighting in the future. As nonlinear loads, LEDs and CFLs produce highly distorted currents. A large number of customers using LEDs or CFLs for domestic, commercial and industrial lighting could determine important Power Quality problems. The paper reports experimental measurement results regarding Power Quality in indoor lighting systems. The harmonic absorptions of several types of luminaries are analyzed, highlighting the impact behavior of different lamps function of used luminaries’ technologies. The recorded harmonic absorption allows characterizing the harmonic spectrum variability of the investigated lamps.
Samimi, A.; Scales, W. A.; Bernhardt, P. A.; Briczinski, S. J.; Selcher, C. A.; McCarrick, M. J.
2012-11-01
Recent observations show that, during ionospheric heating experiments at frequencies near the second electron gyro-harmonic, discrete spectral lines separated by harmonics of the ion-gyro frequency appear in the stimulated electromagnetic emission (SEE) spectrum within 1 kHz of the pump frequency. In addition to the ion gyro-harmonic structures, on occasion, a broadband downshifted emission is observed simultaneously with these spectral lines. Parametric decay of the pump field into upper hybrid/electron Bernstein (UH/EB) and low-frequency ion Bernstein (IB) and oblique ion acoustic (IA) modes is considered responsible for generation of these spectral features. Guided by predictions of an analytical model, a two-dimensional particle-in-cell (PIC) computational model is employed to study the nonlinear processes during such heating experiments. The critical parameters that affect the spectrum, such as whether discrete gyro-harmonic on broadband structures is observed, include angle of the pump field relative to the background magnetic field, pump field strength, and proximity of the pump frequency to the gyro-harmonic. Significant electron heating along the magnetic field is observed in the parameter regimes considered.
Harmonic dissection versus electrocautery in breast surgery in regional Victoria.
Kiyingi, Andrew K; Macdonald, Leigh J; Shugg, Sarah A; Bollard, Ruth C
2015-05-01
Harmonic instruments are an alternative tool for surgical dissection. The aim of this study is to evaluate differences in clinical outcomes relating to harmonic dissection when compared with electrocautery in patients undergoing major breast surgery in a regional centre over a 3-year period. Retrospective chart analysis was conducted of 52 patients undergoing major breast surgery for carcinoma or ductal carcinoma in situ by a single surgeon in a regional centre from May 2008 to January 2011. Analysis involved the extraction of qualitative data relating to patient demographics, surgery type and specimen histopathology. Quantitative data were extracted relating to duration of surgery, duration of patient-controlled analgesia (PCA) use, length of hospital admission, drainage output and presence of infection, haematoma or seroma. Fifty-two patients underwent major breast surgery; harmonic dissection n = 32 and electrocautery n = 20. The two groups were comparable. There was no significant difference identified relating the outcome measures. The median operative duration was shorter in the harmonic dissection group, however, was not of statistical significance. No significant difference was identified between groups relating to length of inpatient stay, duration of PCA use and total volume wound drainage and total days of drainage. Incidence of seroma and infection in the groups was not significantly different. The harmonic dissection is safe and effective in major breast surgery. The study did not demonstrate any clinical advantage from the use of harmonic dissection in major breast surgery compared with electrocautery, nor was there any difference in the complication rates measured. © 2014 Royal Australasian College of Surgeons.
[A New HAC Unsupervised Classifier Based on Spectral Harmonic Analysis].
Yang, Ke-ming; Wei, Hua-feng; Shi, Gang-qiang; Sun, Yang-yang; Liu, Fei
2015-07-01
Hyperspectral images classification is one of the important methods to identify image information, which has great significance for feature identification, dynamic monitoring and thematic information extraction, etc. Unsupervised classification without prior knowledge is widely used in hyperspectral image classification. This article proposes a new hyperspectral images unsupervised classification algorithm based on harmonic analysis(HA), which is called the harmonic analysis classifer (HAC). First, the HAC algorithm counts the first harmonic component and draws the histogram, so it can determine the initial feature categories and the pixel of cluster centers according to the number and location of the peak. Then, the algorithm is to map the waveform information of pixels to be classified spectrum into the feature space made up of harmonic decomposition times, amplitude and phase, and the similar features can be gotten together in the feature space, these pixels will be classified according to the principle of minimum distance. Finally, the algorithm computes the Euclidean distance of these pixels between cluster center, and merges the initial classification by setting the distance threshold. so the HAC can achieve the purpose of hyperspectral images classification. The paper collects spectral curves of two feature categories, and obtains harmonic decomposition times, amplitude and phase after harmonic analysis, the distribution of HA components in the feature space verified the correctness of the HAC. While the HAC algorithm is applied to EO-1 satellite Hyperion hyperspectral image and obtains the results of classification. Comparing with the hyperspectral image classifying results of K-MEANS, ISODATA and HAC classifiers, the HAC, as a unsupervised classification method, is confirmed to have better application on hyperspectral image classification.
Higher-order Kerr effect and harmonic cascading in gases
DEFF Research Database (Denmark)
Bache, Morten; Eilenberger, Falk; Minardi, Stefano
2012-01-01
The higher-order Kerr effect (HOKE) has recently been advocated to explain measurements of the saturation of the nonlinear refractive index in gases. Here we show that cascaded third-harmonic generation results in an effective fifth-order nonlinearity that is negative and significant. Higher......-order harmonic cascading will also occur from the HOKE, and the cascading contributions may significantly modify the observed nonlinear index change. At lower wavelengths, cascading increases the HOKE saturation intensity, while for longer wavelengths cascading will decrease the HOKE saturation intensity....
Higher-order Kerr effect and harmonic cascading in gases.
Bache, Morten; Eilenberger, Falk; Minardi, Stefano
2012-11-15
The higher-order Kerr effect (HOKE) has recently been advocated to explain measurements of the saturation of the nonlinear refractive index in gases. Here we show that cascaded third-harmonic generation results in an effective fifth-order nonlinearity that is negative and significant. Higher-order harmonic cascading will also occur from the HOKE, and the cascading contributions may significantly modify the observed nonlinear index change. At lower wavelengths, cascading increases the HOKE saturation intensity, while for longer wavelengths cascading will decrease the HOKE saturation intensity.
Confocal Imaging of Biological Tissues Using Second Harmonic Generation
Energy Technology Data Exchange (ETDEWEB)
Kim, B-M.; Stoller, P.; Reiser, K.; Eichler, J.; Yan, M.; Rubenchik, A.; Da Silva, L.
2000-03-06
A confocal microscopy imaging system was devised to selectively detect Second harmonic signals generated by biological tissues. Several types of biological tissues were examined using this imaging system, including human teeth, bovine blood vessels, and chicken skin. All these tissues generated strong second harmonic signals. There is considerable evidence that the source of these signals in tissue is collagen. Collagen, the predominant component of most tissues, is known to have second order nonlinear susceptibility. This technique may have diagnostic usefulness in pathophysiological conditions characterized by changes in collagen structure including malignant transformation of nevi, progression of diabetic complications, and abnormalities in wound healing.
Plasma high-order-harmonic generation from ultraintense laser pulses
Tang, Suo; Kumar, Naveen; Keitel, Christoph H.
2017-05-01
Plasma high-order-harmonic generation from an extremely intense short-pulse laser is explored by including the effects of ion motion, electron-ion collisions, and radiation reaction force in the plasma dynamics. The laser radiation pressure induces plasma ion motion through the hole-boring effect, resulting in frequency shifting and widening of the harmonic spectra. The classical radiation reaction force slightly mitigates the frequency broadening caused by the ion motion. Based on the results and physical considerations, parameter maps highlighting the optimum regions for generating a single intense attosecond pulse and coherent XUV radiation are presented.
Application of exponential homotopy algorithm in the inverter harmonic elimination
Zhang, Li
2017-02-01
Eliminating harmonic pollution and improving power factor are the quite important task in the field of power electronics. From the mathematical point of view, harmonic elimination problems can be translated into nonlinear equations. But it is difficult to directly solve the nonlinear equations because of complexity. For this reason, exponential homotopy method is proposed based on homotopy method in this paper. It has focused on built up homotopy equations by modifying the singularities of Jacobian matrix, and on this basis homotopy equations are transformed into the differential initial value problems. Numerical results show that the new exponential homotopy method has higher precision than other algorithms, and the singularity is improved.
Note: Double-hole cantilevers for harmonic atomic force microscopy
Zhang, Weijie; Chen, Yuhang; Chu, Jiaru
2017-10-01
To enhance the harmonic signals in intermittent contact atomic force microscopy, we proposed the double-hole structural modification. Finite element analyses and experiments demonstrated the capability and advantages of the developed method. An infinite set of harmonic cantilevers can be optimized by proper selections of hole size, position, and inter-distance. The second and third resonance frequencies are simultaneously regulated to be integer multiples of the fundamental frequency. In the meanwhile, the alteration of cantilever stiffness is kept minimum. The double-hole modifications have prominent advantages of regular geometry, flexible selection of cutting positions/dimensions, and easy-to-meet fabrication tolerances.
High-order harmonic generation in a capillary discharge
Rocca, Jorge J.; Kapteyn, Henry C.; Mumane, Margaret M.; Gaudiosi, David; Grisham, Michael E.; Popmintchev, Tenio V.; Reagan, Brendan A.
2010-06-01
A pre-ionized medium created by a capillary discharge results in more efficient use of laser energy in high-order harmonic generation (HHG) from ions. It extends the cutoff photon energy, and reduces the distortion of the laser pulse as it propagates down the waveguide. The observed enhancements result from a combination of reduced ionization energy loss and reduced ionization-induced defocusing of the driving laser as well as waveguiding of the driving laser pulse. The discharge plasma also provides a means to spectrally tune the harmonics by tailoring the initial level of ionization of the medium.
Harmonic oscillator in an elastic medium with a spiral dislocation
Maia, A. V. D. M.; Bakke, K.
2018-02-01
We investigate the behaviour of a two-dimensional harmonic oscillator in an elastic medium that possesses a spiral dislocation (an edge dislocation). We show that the Schrödinger equation for harmonic oscillator in the presence of a spiral dislocation can be solved analytically. Further, we discuss the effects of this topological defect on the confinement to a hard-wall confining potential. In both cases, we analyse if the effects of the topology of the spiral dislocation gives rise to an Aharonov-Bohm-type effect for bound states.
Magnetic fluid droplet in a harmonic electric field
Energy Technology Data Exchange (ETDEWEB)
Kvasov, D., E-mail: kvasovdmitry@gmail.com [Lomonosov Moscow State University, Moscow (Russian Federation); Naletova, V. [Lomonosov Moscow State University, Moscow (Russian Federation); Beketova, E.; Dikanskii, Yu. [North-Caucasus Federal University, Stavropol (Russian Federation)
2017-06-01
A magnetic fluid droplet immersed in oil in an applied harmonic electric field is studied experimentally and theoretically. It is shown that deformations of the droplet observed experimentally are not described by the well-known theory. New double-layer droplet model which describes experimental data well is proposed. - Highlights: • The magnetic fluid droplet in the oil in a harmonic electric field is studied. • The paradoxical flattening effect of the droplet is observed experimentally. • For explaining this effect the model of the double-layer droplet is proposed. • Numerical and experimental data coincide qualitatively and quantitatively.
Constraint damping in the Z4 formulation and harmonic gauge
Energy Technology Data Exchange (ETDEWEB)
Gundlach, Carsten [School of Mathematics, University of Southampton, Southampton SO17 1BJ (United Kingdom); Calabrese, Gioel [School of Mathematics, University of Southampton, Southampton SO17 1BJ (United Kingdom); Hinder, Ian [School of Mathematics, University of Southampton, Southampton SO17 1BJ (United Kingdom); Martin-GarcIa, Jose M [Instituto de Estructura de la Materia, Centro de Fisica Miguel A Catalan, CSIC, Serrano 123, 28006 Madrid (Spain)
2005-09-07
We show that by adding suitable lower-order terms to the Z4 formulation of the Einstein equations, all constraint violations except constant modes are damped. This makes the Z4 formulation a particularly simple example of a {lambda}-system as suggested by Brodbeck et al (1999 J. Math. Phys. 40 909). We also show that the Einstein equations in harmonic coordinates can be obtained from the Z4 formulation by a change of variables that leaves the implied constraint evolution system unchanged. Therefore, the same method can be used to damp all constraints in the Einstein equations in harmonic gauge.
Addition theorems for spin spherical harmonics: I. Preliminaries
Energy Technology Data Exchange (ETDEWEB)
Bouzas, Antonio O, E-mail: abouzas@mda.cinvestav.mx [Departamento de Fisica Aplicada, CINVESTAV-IPN, Carretera Antigua a Progreso Km. 6, Apdo. Postal 73 ' Cordemex' , Merida 97310, Yucatan (Mexico)
2011-04-22
We develop a systematic approach to deriving addition theorems for, and some other bilocal sums of, spin spherical harmonics. In this first part we establish some necessary technical results. We discuss the factorization of orbital and spin degrees of freedom in certain products of Clebsch-Gordan coefficients, and obtain general explicit results for the matrix elements in configuration space of tensor products of arbitrary rank of the position and angular-momentum operators. These results are the basis of the addition theorems for spin spherical harmonics obtained in part II (2011 J. Phys. A: Math. Theor. 44 165302).
Level of Harmonization and ERP Architecture in Multinational Corporations
DEFF Research Database (Denmark)
Rahimi, Fatemeh; Møller, Charles
2013-01-01
multinational corporations. The ERP distribution decision in MNCs has been mainly associated with the corporate strategy and governance structure. As global ERP deployment benefits mainly come from business consolidation, and as there are significant costs and risks associated with centralized ERP...... implementations, this paper investigates the influence of level of harmonization in the choice of ERP architecture in MNCs. Though the findings indicate a negative relation between the level of harmonization and a centralized ERP systems’ effectiveness, the study identifies the choice of ERP architecture...... to be more directly affected by the factors prohibiting further divergence, namely the corporate business process governance structure and the degree of similarity of its business models....
Harmonic Calculation Toolbox in Industry Application for Adjustable Speed Drive
DEFF Research Database (Denmark)
Asiminoaei, Lucian; Blaabjerg, Frede; Hansen, Steffan
2004-01-01
parameters to be aware oFrede This paper focuses on estimation of line-side harmonic distortion when connecting one or multiple six-pulse diode rectifiers to any supply transformer. Results are put into a practical PC software toolbox for harmonic estimation on real applications. Through a combination...... of an off-line database and new interpolation techniques very good results have been achieved. The final results obtained are very close to the measurements on real applications and the toolbox can be used for future ASD designs and installations....
Violation of smooth observable macroscopic realism in a harmonic oscillator.
Leshem, Amir; Gat, Omri
2009-08-14
We study the emergence of macrorealism in a harmonic oscillator subject to consecutive measurements of a squeezed action. We demonstrate a breakdown of dynamical realism in a wide parameter range that is maximized in a scaling limit of extreme squeezing, where it is based on measurements of smooth observables, implying that macroscopic realism is not valid in the harmonic oscillator. We propose an indirect experimental test of these predictions with entangled photons by demonstrating that local realism in a composite system implies dynamical realism in a subsystem.
Predicting charmonium and bottomonium spectra with a quark harmonic oscillator
Norbury, J. W.; Badavi, F. F.; Townsend, L. W.
1986-01-01
The nonrelativistic quark model is applied to heavy (nonrelativistic) meson (two-body) systems to obtain sufficiently accurate predictions of the spin-averaged mass levels of the charmonium and bottomonium spectra as an example of the three-dimensional harmonic oscillator. The present calculations do not include any spin dependence, but rather, mass values are averaged for different spins. Results for a charmed quark mass value of 1500 MeV/c-squared show that the simple harmonic oscillator model provides good agreement with experimental values for 3P states, and adequate agreement for the 3S1 states.
Modeling of higher harmonics formation in medical ultrasound systems
DEFF Research Database (Denmark)
Taylor, Louise Kold; Schlaikjer, Malene; Jensen, Jørgen Arendt
2002-01-01
The pressure eld emitted from multi-element medical ultrasound transducers can be simulated with Field II in the linear regime. By expanding this program's application to the nonlinear regime, beamforming schemes can be studied under strong focusing and high pressure levels as well, providing...... of the approach is demonstrated by comparing results from simulations and measurements from a convex array transducer. The new simulation tool is capable of simulating the formation of higher harmonics in water on the acoustical axis. The generation of nonlinear higher harmonic components can be predicted...
Kahn, Michael G.; Callahan, Tiffany J.; Barnard, Juliana; Bauck, Alan E.; Brown, Jeff; Davidson, Bruce N.; Estiri, Hossein; Goerg, Carsten; Holve, Erin; Johnson, Steven G.; Liaw, Siaw-Teng; Hamilton-Lopez, Marianne; Meeker, Daniella; Ong, Toan C.; Ryan, Patrick; Shang, Ning; Weiskopf, Nicole G.; Weng, Chunhua; Zozus, Meredith N.; Schilling, Lisa
2016-01-01
Objective: Harmonized data quality (DQ) assessment terms, methods, and reporting practices can establish a common understanding of the strengths and limitations of electronic health record (EHR) data for operational analytics, quality improvement, and research. Existing published DQ terms were harmonized to a comprehensive unified terminology with definitions and examples and organized into a conceptual framework to support a common approach to defining whether EHR data is ‘fit’ for specific uses. Materials and Methods: DQ publications, informatics and analytics experts, managers of established DQ programs, and operational manuals from several mature EHR-based research networks were reviewed to identify potential DQ terms and categories. Two face-to-face stakeholder meetings were used to vet an initial set of DQ terms and definitions that were grouped into an overall conceptual framework. Feedback received from data producers and users was used to construct a draft set of harmonized DQ terms and categories. Multiple rounds of iterative refinement resulted in a set of terms and organizing framework consisting of DQ categories, subcategories, terms, definitions, and examples. The harmonized terminology and logical framework’s inclusiveness was evaluated against ten published DQ terminologies. Results: Existing DQ terms were harmonized and organized into a framework by defining three DQ categories: (1) Conformance (2) Completeness and (3) Plausibility and two DQ assessment contexts: (1) Verification and (2) Validation. Conformance and Plausibility categories were further divided into subcategories. Each category and subcategory was defined with respect to whether the data may be verified with organizational data, or validated against an accepted gold standard, depending on proposed context and uses. The coverage of the harmonized DQ terminology was validated by successfully aligning to multiple published DQ terminologies. Discussion: Existing DQ concepts
A current controller of grid-connected converter for harmonic damping in a distribution network
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe
2011-01-01
Harmonic resonance caused by the increased use of shunt-connected capacitors in LCL-filters and power factor correction devices may become a serious power quality challenge in electric distribution systems. A voltage-detection method based on current control is developed to damp harmonic resonances....... However, it is susceptible to the mismatch between harmonic conductance and characteristic impedance of distribution feeder. This paper proposes a current controller which allows discrete adjustment of harmonic conductance for both the characteristic harmonic and the non-characteristic harmonic voltages...
Harmonic Analysis of Offshore Wind Farms with Full Converter Wind Turbines
DEFF Research Database (Denmark)
Kocewiak, Lukasz Hubert; Hjerrild, Jesper; Bak, Claus Leth
2009-01-01
This paper presents the harmonic analysis of offshore wind farm (OWF) models with full converters represented as harmonic sources and measurement data on the point of common coupling (PCC) during normal operation. The model describes a wind farm (WF) with full rated converters installed connected...... to a shore with a long HV cable. The way of propagation and effects of harmonics are presented for different study cases. Modeling strategies of harmonic sources for harmonic analysis are described and compared. Different results dependent on applied harmonic models are shown and discussed in this paper...
Application of smooth exterior scaling method to calculate the high harmonic generation spectra.
Kalita, Dhruba J; Gupta, Ashish K
2013-02-21
We have calculated the high harmonic generation spectra from Xe atom by imposing different kinds of absorbing potentials. Owing to the center of inversion of the model system, one should get odd harmonics only. However, using negative imaginary potentials as an absorbing boundary condition, we have also got even order harmonics along with the odd order harmonics. These non-odd order harmonics are generated due to the spurious reflections occurring at the grid boundary. On the contrary, when smooth exterior scaling methods are used as an absorbing boundary condition, only odd order harmonics are obtained. Hence, smooth exterior scaling methods impose proper absorbing boundary condition.
Setting the Stage for Harmonized Risk Assessment by Seismic Hazard Harmonization in Europe (SHARE)
Woessner, Jochen; Giardini, Domenico; SHARE Consortium
2010-05-01
Probabilistic seismic hazard assessment (PSHA) is arguably one of the most useful products that seismology can offer to society. PSHA characterizes the best available knowledge on the seismic hazard of a study area, ideally taking into account all sources of uncertainty. Results form the baseline for informed decision making, such as building codes or insurance rates and provide essential input to each risk assessment application. Several large scale national and international projects have recently been launched aimed at improving and harmonizing PSHA standards around the globe. SHARE (www.share-eu.org) is the European Commission funded project in the Framework Programme 7 (FP-7) that will create an updated, living seismic hazard model for the Euro-Mediterranean region. SHARE is a regional component of the Global Earthquake Model (GEM, www.globalquakemodel.org), a public/private partnership initiated and approved by the Global Science Forum of the OECD-GSF. GEM aims to be the uniform, independent and open access standard to calculate and communicate earthquake hazard and risk worldwide. SHARE itself will deliver measurable progress in all steps leading to a harmonized assessment of seismic hazard - in the definition of engineering requirements, in the collection of input data, in procedures for hazard assessment, and in engineering applications. SHARE scientists will create a unified framework and computational infrastructure for seismic hazard assessment and produce an integrated European probabilistic seismic hazard assessment (PSHA) model and specific scenario based modeling tools. The results will deliver long-lasting structural impact in areas of societal and economic relevance, they will serve as reference for the Eurocode 8 (EC8) application, and will provide homogeneous input for the correct seismic safety assessment for critical industry, such as the energy infrastructures and the re-insurance sector. SHARE will cover the whole European territory, the
DEFF Research Database (Denmark)
Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth
2015-01-01
The increasing number of renewable energy sources at the distribution grid is becoming a major issue for utility companies, since the grid connected converters are operating at different operating points due to the probabilistic characteristics of renewable energy. Besides, typically, the harmoni...... impedance matrixes, where that represents the harmonic coupling characteristic as well as the different instability characteristics. The theoretical modeling and analysis are verified by simulations and also experimental results.......The increasing number of renewable energy sources at the distribution grid is becoming a major issue for utility companies, since the grid connected converters are operating at different operating points due to the probabilistic characteristics of renewable energy. Besides, typically, the harmonics...... and impedance from other renewable energy sources are not taken carefully into account in the installation and design. However, this may bring an unknown harmonic instability into the multiple power sourced system and also make the analysis difficult due to the complexity of the grid network. This paper...
Gia, Quoc; Mayeli, Azita; Mhaskar, Hrushikesh; Zhou, Ding-Xuan
2017-01-01
The second of a two volume set on novel methods in harmonic analysis, this book draws on a number of original research and survey papers from well-known specialists detailing the latest innovations and recently discovered links between various fields. Along with many deep theoretical results, these volumes contain numerous applications to problems in signal processing, medical imaging, geodesy, statistics, and data science. The chapters within cover an impressive range of ideas from both traditional and modern harmonic analysis, such as: the Fourier transform, Shannon sampling, frames, wavelets, functions on Euclidean spaces, analysis on function spaces of Riemannian and sub-Riemannian manifolds, Fourier analysis on manifolds and Lie groups, analysis on combinatorial graphs, sheaves, co-sheaves, and persistent homologies on topological spaces. Volume II is organized around the theme of recent applications of harmonic analysis to function spaces, differential equations, and data science, covering topics such a...
Systems Harmonization and Convergence - the GIGAS Approach
Marchetti, P. G.; Biancalana, A.; Coene, Y.; Uslander, T.
2009-04-01
0.1 Background The GIGAS1 Support Action promotes the coherent and interoperable development of the GMES, INSPIRE and GEOSS initiatives through their concerted adoption of standards, protocols, and open architectures. 0.2 Preparing for Coordinated Data Access The GMES Coordinated Data Access System is under design and implementation2. This objective has motivated the definition of the interoperability standards between the contributing missions. The following elements have been addressed with associated papers submitted to OGC: The EO Product Metadata has been based on the OGC Geographic Markup Language, addressing sensor characteristics for optical, radar and atmospheric products. Collection and service discovery: an ISO extension package for CSW ebRim has been proposed. Catalogue Service (CSW): an Earth Observation extension package of the CSW ebRim has been proposed. Feasibility Analysis and Order: an Order interface control document and an Earth Observation profile of the Sensor Planning Service have been proposed. Online Data Access: an Earth Observation profile of the Web Map Services (WMS) for visualization and evaluation purposes has been proposed. Identity (user) management: the objective in the long term is to allow for a single sign-on to the Coordinated Data Access system by users registered in the various Earth Observation ground segments by providing a federated identity across participating ground segments, exploiting OASIS standards. 0.3 The GIGAS proposed harmonization approach The approach proposed by GIGAS is based on three elements: Technology watch Comparative analysis Shaping of initiatives and standards This paper concentrates on the methodology for technology watch and comparative analysis. The complexity of the GIGAS scenario involving huge systems (i.e. GEOSS, INSPIRE, GMES etc.) entails the interaction with different heterogeneous partners, each with a specific competence, expertise and know-how. 0.3.1 Technology watch The methodology
Loganathan, Muthukumaran; Bristow, Douglas A
2014-04-01
This paper presents a method and cantilever design for improving the mechanical measurement sensitivity in the atomic force microscopy (AFM) tapping mode. The method uses two harmonics in the drive signal to generate a bi-harmonic tapping trajectory. Mathematical analysis demonstrates that the wide-valley bi-harmonic tapping trajectory is as much as 70% more sensitive to changes in the sample topography than the standard single-harmonic trajectory typically used. Although standard AFM cantilevers can be driven in the bi-harmonic tapping trajectory, they require large forcing at the second harmonic. A design is presented for a bi-harmonic cantilever that has a second resonant mode at twice its first resonant mode, thereby capable of generating bi-harmonic trajectories with small forcing signals. Bi-harmonic cantilevers are fabricated by milling a small cantilever on the interior of a standard cantilever probe using a focused ion beam. Bi-harmonic drive signals are derived for standard cantilevers and bi-harmonic cantilevers. Experimental results demonstrate better than 30% improvement in measurement sensitivity using the bi-harmonic cantilever. Images obtained through bi-harmonic tapping exhibit improved sharpness and surface tracking, especially at high scan speeds and low force fields.
Symmetry-controlled time structure of high-harmonic carrier fields from a solid.
Langer, F; Hohenleutner, M; Huttner, U; Koch, S W; Kira, M; Huber, R
2017-04-01
High-harmonic (HH) generation in crystalline solids1-6 marks an exciting development, with potential applications in high-efficiency attosecond sources7, all-optical bandstructure reconstruction8,9, and quasiparticle collisions10,11. Although the spectral1-4 and temporal shape5 of the HH intensity has been described microscopically1-6,12, the properties of the underlying HH carrier wave have remained elusive. Here we analyse the train of HH waveforms generated in a crystalline solid by consecutive half cycles of the same driving pulse. Extending the concept of frequency combs13-15 to optical clock rates, we show how the polarization and carrier-envelope phase (CEP) of HH pulses can be controlled by crystal symmetry. For some crystal directions, we can separate two orthogonally polarized HH combs mutually offset by the driving frequency to form a comb of even and odd harmonic orders. The corresponding CEP of successive pulses is constant or offset by π, depending on the polarization. In the context of a quantum description of solids, we identify novel capabilities for polarization- and phase-shaping of HH waveforms that cannot be accessed with gaseous sources.
On quantum harmonic oscillator being subjected to absolute ...
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 88; Issue 1. On quantum ... In a quantum harmonic oscillator (QHO), the energy of the oscillator increases with increased frequency. ... This new function, which corresponds to new sets of particles, has scope to raise the quantum oscillator energy (QOE) up to infinity.
Harmonic chirp imaging method for ultrasound contrast agent
Borsboom, Jerome M.G.; Chin, Chien Ting; Bouakaz, Ayache; Versluis, Michel; de Jong, N.
2005-01-01
Coded excitation is currently used in medical ultrasound to increase signal-to-noise ratio (SNR) and penetration depth. We propose a chirp excitation method for contrast agents using the second harmonic component of the response. This method is based on a compression filter that selectively
Application of potential harmonic expansion method to BEC ...
Indian Academy of Sciences (India)
We adopt the potential harmonics expansion method for an ab initio solution of the many-body system in a Bose condensate containing interacting bosons. Unlike commonly adopted mean-field theories, our method is capable of handling two-body correlation properly. We disregard three- and higher-body correlations.
Quality of potential harmonics expansion method for dilute Bose ...
Indian Academy of Sciences (India)
We present and examine an approximate but ab initio many-body approach, viz., potential harmonics expansion method (PHEM), which includes two-body correlations for dilute Bose–Einstein condensates. Comparing the total ground state energy for three trapped interacting bosons calculated in PHEM with the exact ...
Analytic discrete cosine harmonic wavelet transform based OFDM ...
Indian Academy of Sciences (India)
Abstract. An OFDM based on Analytic Discrete Cosine Harmonic Wavelet Trans- form (ADCHWT_OFDM) has been proposed in this paper. Analytic DCHWT has been realized by applying DCHWT to the original signal and to its Hilbert trans- form. ADCHWT has been found to be computationally efficient and very effective.
Systematic harmonic power laws inter-relating multiple fundamental constants
Chakeres, Donald; Buckhanan, Wayne; Andrianarijaona, Vola
2017-01-01
Power laws and harmonic systems are ubiquitous in physics. We hypothesize that 2, π, the electron, Bohr radius, Rydberg constant, neutron, fine structure constant, Higgs boson, top quark, kaons, pions, muon, Tau, W, and Z when scaled in a common single unit are all inter-related by systematic harmonic powers laws. This implies that if the power law is known it is possible to derive a fundamental constant's scale in the absence of any direct experimental data of that constant. This is true for the case of the hydrogen constants. We created a power law search engine computer program that randomly generated possible positive or negative powers searching when the product of logical groups of constants equals 1, confirming they are physically valid. For 2, π, and the hydrogen constants the search engine found Planck's constant, Coulomb's energy law, and the kinetic energy law. The product of ratios defined by two constants each was the standard general format. The search engine found systematic resonant power laws based on partial harmonic fraction powers of the neutron for all of the constants with products near 1, within their known experimental precision, when utilized with appropriate hydrogen constants. We conclude that multiple fundamental constants are inter-related within a harmonic power law system.
Virtual Admittance Loop for Voltage Harmonic Compensation in Microgrids
DEFF Research Database (Denmark)
Blanco, Cristian; Reigosa, David; Quintero, Juan Carlos Vasquez
2016-01-01
The use of the virtual admittance concept for harmonic and/or unbalance compensation in microgrids when multiple inverters operate in parallel is proposed in this paper. The virtual impedance concept has been traditionally used for these purposes. However, one drawback of the virtual impedance is...
Virtual admittance loop for voltage harmonic compensation in microgrids
DEFF Research Database (Denmark)
Blanco, Cristian; Reigosa, David; Quintero, Juan Carlos Vasquez
2015-01-01
The use of the virtual admittance concept for harmonic and/or unbalance compensation in microgrids when multiple inverters operate in parallel is proposed in this paper. The virtual impedance concept has been traditionally used for these purposes. However, one drawback of the virtual impedance is...
Adomian Decomposition approach to solve the simple harmonic quantum oscillator
Jaradat, Adnan; Adnan Jardat Team; Maen Gharaibeh Team; Mohammad Qaseer Team; Abdalla Obeidat Team
2015-04-01
The simple harmonic quantum oscillator problem has been solved using two methods namely, the algebraic method where the raising and lower operators used and the Frobenius method. Here, we will adopt the Adomian decomposition method to solve this problem and derive the Hermite polynomials in much easier way than the above mentioned methods. This work is supported by Jordan University of Science and Technolgy.
Harmonic Mitigation Methods in Large Offshore Wind Power Plants
DEFF Research Database (Denmark)
Kocewiak, Łukasz Hubert; Chaudhary, Sanjay; Hesselbæk, Bo
2013-01-01
and remedial harmonic mitigation methods in terms of passive and active filtering are described. It is shown that WPP components such as long HVAC cables and park transformers can introduce significant low-frequency resonances which can affect wind turbine control system operation and overall WPP stability...
A Comparative Study of the Use of Harmonic Scalpel versus ...
African Journals Online (AJOL)
2017-05-18
May 18, 2017 ... Breast cancer is the most site‑specific cancer in women.[1] For patients who present late, radical ... The clinical information such as age of the patient, age of menarche, age of menopause, parity of the patient, .... Incidence of hypertension in harmonic scalpel group was 12% and electrocautery group was.
Spectral inverse problem for q-deformed harmonic oscillator
Indian Academy of Sciences (India)
only the knowledge of bound-state spectra of q-deformed harmonic oscillator. We have also studied the ... that these will be continued both at sophisticated and pedagogical levels [2]. In an interesting work, Engelke ... concepts, exact knowledge of the spectrum is not enough for the reconstruction of the potential. For a given ...
Second harmonic generation from photonic structured GaN nanowalls
Energy Technology Data Exchange (ETDEWEB)
Soya, Takahiro; Inose, Yuta; Kunugita, Hideyuki; Ema, Kazuhiro; Yamano, Kouji; Kikuchi, Akihiko; Kishino, Katsumi, E-mail: t-soya@sophia.ac.j [Department of Engineering and Applied Sciences, Sophia University 7-1, Kioi-cho, Chiyoda-ku, Tokyo 102-8554 (Japan)
2009-11-15
We observed large enhancement of reflected second harmonic generation (SHG) using the one-dimensional photonic effect in regularly arranged InGaN/GaN single-quantum-well nanowalls. Using the effect when both fundamental and SH resonate with the photonic mode, we obtained enhancement of about 40 times compared with conditions far from resonance.
Free Fall and Harmonic Oscillations: Analyzing Trampoline Jumps
Pendrill, Ann-Marie; Eager, David
2015-01-01
Trampolines can be found in many gardens and also in some playgrounds. They offer an easily accessible vertical motion that includes free fall. In this work, the motion on a trampoline is modelled by assuming a linear relation between force and deflection, giving harmonic oscillations for small amplitudes. An expression for the cycle-time is…
Multi-order nonlinear diffraction in second harmonic generation
DEFF Research Database (Denmark)
Saltiel, S. M.; Neshev, D.; Krolikowski, Wieslaw
We analyze the emission patterns in the process of second harmonic (SH) generation in χ(2) nonlinear gratings and identify for the first time, to the best of our knowledge, the evidence of Raman-Nath type nonlinear diffraction in frequency doubling processes....
Mechanisms for the production of harmonics in free electron lasers
Elgin, J.N.; Penman, C.
1991-01-01
Harmonics in the radiation of a free electron laser are useful for extending the range of tuning, may originate in spontaneous or parametric processes, and can take part in stimulated emission or amplification. These mechanisms exhibit interesting analogies with those of nonlinear optics. Apart from
High intensity direct third harmonic generation in BBO
Energy Technology Data Exchange (ETDEWEB)
Banks, P.S., LLNL
1998-02-23
The azimuthal dependence of second- and third-order coupling are used to measure the relative contributions of each to direct third harmonic generation with efficiencies up to 6%. The values of {xi}{sub ij}{sup (3)} are measured.
Vowel harmonic amplitude differences in persons with vocal nodules.
Radish Kumar, B; Bhat, Jayashree S; Mukhi, Payal
2011-09-01
Spectrum is a fast Fourier transform-generated power spectrum extracted from the speech sample. It is reported to provide a quantitative acoustic index of the degree of glottal abduction and adduction in voices perceived to be breathy or pressed. In the present study, it was hypothesized that there would be abnormal reduction of higher harmonic amplitudes relative to the amplitude of the first harmonics in the subjects with vocal nodules and hence the present study was carried out. One hundred twenty participants were divided into clinical group and control group. They were instructed to phonate /a/ at their most comfortable pitch and loudness. Fourier transformation of the recorded acoustic signal was first performed to create a spectrum. Amplitudes were measured for the first and second harmonics (H1 and H2) as well as the harmonics at the first, second, and third formants (A1, A2, and A3) using the Computerized Speech Science Lab (Kay Pentax, Lincoln, NJ). There was a significant difference between the means of two groups for all the parameters, such as H1-H2, H1-A1, H1-A2, and H1-A3 at PVoice Foundation. Published by Mosby, Inc. All rights reserved.
On a Subclass of Harmonic Convex Functions of Complex Order
Directory of Open Access Journals (Sweden)
N. Magesh
2012-01-01
Full Text Available We introduce and study a subclass of harmonic convex functions of complex order. Coefficient bounds, extreme points, distortion bounds, convolution conditions, and convex combination are determined for functions in this class. Further, we obtain the closure property of this class under integral operator.
Coherent states of general time-dependent harmonic oscillator
Indian Academy of Sciences (India)
The wave function can then be found easily, by making use of these ladder operators. Glauber proposed standard coherent states for a harmonic oscillator which is the prototype for most of the coherent states [3,4]. The coherent states form a very convenient representation for problems of quantum mechanics and can be ...
Selective compensation of voltage harmonics in grid-connected microgrids
DEFF Research Database (Denmark)
Savaghebi, Mehdi; Vasquez, Juan Carlos; Jalilian, Alireza
2013-01-01
In this paper, a novel approach is proposed for selective compensation of main voltage harmonics in a grid-connected microgrid. The aim of compensation is to provide a high voltage quality at the point of common coupling (PCC). PCC voltage quality is of great importance due to sensitive loads tha...... to an acceptable level....
The Study of Damped Harmonic Oscillations Using an Electronic Counter
Wadhwa, Ajay
2009-01-01
We study damped harmonic oscillations in mechanical systems like the loaded spring and simple pendulum with the help of an oscillation measuring electronic counter. The experimental data are used in a software program that solves the differential equation for damped vibrations of any system and determines its position, velocity and acceleration as…
Teaching Resonance and Harmonics with Guitar and Piano
Sobel, Michael
2014-01-01
In a recent paper, Kasar, Yurumezoglu, and Sengoren show how to use a guitar, or two guitars, to demonstrate resonance. Here we extend this idea by showing how to use a guitar or a piano (both acoustic) to demonstrate resonance, harmonics, and the properties of the musical scale. We discuss the advantages and disadvantages of each instrument.…
Dynamics of 'quantumness' measures in the decohering harmonic ...
Indian Academy of Sciences (India)
2016-07-26
Jul 26, 2016 ... Abstract. We studied the behaviour under decoherence of four different measures of the distance between quantum states and classical states for the harmonic oscillator coupled to a linear Markovian bath. Three of these are relative measures, using different definitions of the distance between the given ...
Analysis of soil temperature harmonics and filtering characteristics ...
African Journals Online (AJOL)
The incident solar energy determines the periodic variation of the soil temperatures and the attenuation with depth. Harmonic analysis of soil ... The results show that the soil behaves like an energy filter and an electrical analogue was modeled to simulate the filtering characteristics of the soil. It was found that the soil acts as ...
Maximal Regularity of the Discrete Harmonic Oscillator Equation
Directory of Open Access Journals (Sweden)
Airton Castro
2009-01-01
Full Text Available We give a representation of the solution for the best approximation of the harmonic oscillator equation formulated in a general Banach space setting, and a characterization of lp-maximal regularity—or well posedness—solely in terms of R-boundedness properties of the resolvent operator involved in the equation.
Some Implicit Methods for Solving Harmonic Variational Inequalities
Directory of Open Access Journals (Sweden)
Muhammad Aslam Noor
2016-08-01
Full Text Available In this paper, we use the auxiliary principle technique to suggest an implicit method for solving the harmonic variational inequalities. It is shown that the convergence of the proposed method only needs pseudo monotonicity of the operator, which is a weaker condition than monotonicity.
Theory of surface second-harmonic generation in silica nanowires
DEFF Research Database (Denmark)
Lægsgaard, Jesper
2010-01-01
-based nanowires is critically discussed, based on simulations of second-harmonic generation in nanowires with a fluctuating phase-matching wavelength. It is concluded that efficient wavelength conversion will require strong improvements in the nanowire uniformity, peak powers well in excess of 10 KW, increase...
Flow Through A Horizontal Porous Channel With A Harmonic ...
African Journals Online (AJOL)
In this research work we provide a finite element solution to the problem of the flow through a horizontal channel with a harmonic pressure gradient. Results obtained shows that the ... due to the viscous dissipation effect. Keywords: Asymptotic techniques, Maxwell fluid, constantly accelerating plates and velocity fields.
The harmonization of banking legislation in the EU
Directory of Open Access Journals (Sweden)
Shkëlqesa Çitaku
2016-03-01
Full Text Available This paper attempts to assess the current legislation of banking in the European Union. The process of unification in Europe is also followed by efforts to harmonize and unify the laws of the member states. In the field of banking industry the precondition for harmonization of laws is the integration of internal market with the free movement of capital. The regulation and supervision of banks in EU still remains fragmented. European member states still have diverse regulations concerning the role of the state. The European Commission has the important function of proposing EU legislation on financial services including banks and ensuring that EU law is properly applied throughout the EU. Banks are considered as a key industry enabling all the economic activities via depositing, crediting and arranging of payments. A number of secondary legislation has been adopted by the EU institutions to harmonize the national banking law of Member States. The principles and objectives set by the European Commission Treaty depend on four EU freedoms with the aim of effective and open market including banks. Therefore it was a continuous process of harmonization of national banking regulation via secondary law since the 70’s.
Singular spectrum analysis, Harmonic regression and El-Nino effect ...
Indian Academy of Sciences (India)
42
1. Singular spectrum analysis, Harmonic regression and El-Nino effect on total ozone (1979-93) over India and surrounding regions. Chandramadhab Pal cmpmagra@gmail.com. Department of Physics, Ramakrishna Mission Vidyamandira, Belurmath, Howrah 711202, W.B.,. India. Abstract: The Total Ozone Mapping ...
Gradient estimation of a p-harmonic map
Directory of Open Access Journals (Sweden)
Bei Wang
2010-02-01
Full Text Available This article presents L^p estimates for the gradient of p-harmonic maps. Since the system satisfies a natural growth condition, it is difficult to use standard elliptic estimates. We use spherical coordinates to convert the system into another system with angle functions. The new system can be estimate by the standard elliptic technique.
High-Efficiency Harmonically Terminated Diode and Transistor Rectifiers
Energy Technology Data Exchange (ETDEWEB)
Roberg, M; Reveyrand, T; Ramos, I; Falkenstein, EA; Popovic, Z
2012-12-01
This paper presents a theoretical analysis of harmonically terminated high-efficiency power rectifiers and experimental validation on a class-C single Schottky-diode rectifier and a class-F-1 GaN transistor rectifier. The theory is based on a Fourier analysis of current and voltage waveforms, which arise across the rectifying element when different harmonic terminations are presented at its terminals. An analogy to harmonically terminated power amplifier (PA) theory is discussed. From the analysis, one can obtain an optimal value for the dc load given the RF circuit design. An upper limit on rectifier efficiency is derived for each case as a function of the device on-resistance. Measured results from fundamental frequency source-pull measurement of a Schottky diode rectifier with short-circuit terminations at the second and third harmonics are presented. A maximal device rectification efficiency of 72.8% at 2.45 GHz matches the theoretical prediction. A 2.14-GHz GaN HEMT rectifier is designed based on a class-F-1 PA. The gate of the transistor is terminated in an optimal impedance for self-synchronous rectification. Measurements of conversion efficiency and output dc voltage for varying gate RF impedance, dc load, and gate bias are shown with varying input RF power at the drain. The rectifier demonstrates an efficiency of 85% for a 10-W input RF power at the transistor drain with a dc voltage of 30 V across a 98-Omega resistor.
A need for harmonized legislation: perspectives in South America.
de F Toledo, M Cecilia
2014-08-01
The harmonization of national food standards in South America has been undertaken by Argentina, Brazil, Paraguay and Uruguay within the Southern Common Market (MERCOSUR). Since food is among the most important commodities traded internationally, the harmonization of national food standards has been considered a priority. MERCOSUR countries have different laws governing food that are based, among other things, on historical, cultural and economic factors. Some regulations are complex and contain many controls while others are less developed and lack basic requirements. As a consequence, from the inception of preparing a common legislation through its adoption by the member countries, a long and difficult task has been foreseen. Although not immediately apparent, the difficulty in achieving consensus within MERCOSUR is not unlike that experience by the members of the European Union. Currently, food harmonization within MERCOSUR has been reached for issues where technical standards may represent serious trade barriers. These decisions have been based on Codex limentarius Commission guidelines and recommendations as well as on the European Union experience. This article will briefly discuss the current status of the MERCOSUR harmonization process with focus on issues related to food safety. A historical background of MERCOSUR and its institutional structure are included. © 2013 Society of Chemical Industry.
Experiences with the harmonization of seed policies, laws and ...
African Journals Online (AJOL)
Mo
Key Words: Eastern and central Africa (ECA), Policy change cycle, rationalization and harmonization, seed sector. Introduction. In Africa,effective policies for achieving economic growth, reducing .... and final group of ASARECA countries, namely the. Democratic Republic of Congo and Madagascar were brought into the ...
Exact complex integrals in two dimensions for shifted harmonic ...
Indian Academy of Sciences (India)
We use rationalization method to study two-dimensional complex dynamical systems (shifted harmonic oscillator in complex plane) on the extended comples phase space (ECPS). The role and scope of the derived invatiants in the context of various physical problems are high-lighted.
A Comparative Study of the Use of Harmonic Scalpel versus ...
African Journals Online (AJOL)
Context: Oncosurgery is an emerging branch with the set goals of prolonging the life and ensuring the best possible quality of life to the surviving patient. The use of harmonic scalpel has proved to be beneficial in a variety of surgeries but its role in breast surgery is still controversial. Aims: We conducted this study to ...
Large-Nc quantum chromodynamics and harmonic sums
Indian Academy of Sciences (India)
In the large- limit of QCD, two-point functions of local operators become harmonic sums. I review some properties which follow from this fact and which are relevant for phenomenological applications. This has led us to consider a class of analytic number theory functions as toy models of large- QCD which also is ...
Thermal state of the general time-dependent harmonic oscillator
Indian Academy of Sciences (India)
Taking advantage of dynamical invariant operator, we derived quantum mechanical solution of general time-dependent harmonic oscillator. The uncertainty relation of the system is always larger than ħ=2 not only in number but also in the thermal state as expected. We used the diagonal elements of density operator ...
Analytic and algorithmic aspects of generalized harmonic sums and polylogarithms
Energy Technology Data Exchange (ETDEWEB)
Ablinger, Jakob; Schneider, Carsten [Johannes Kepler Univ., Linz (Austria). Research Inst. for Symbolic Computation; Bluemlein, Johannes [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2013-01-15
In recent three-loop calculations of massive Feynman integrals within Quantum Chromodynamics (QCD) and, e.g., in recent combinatorial problems the so-called generalized harmonic sums (in short S-sums) arise. They are characterized by rational (or real) numerator weights also different from {+-}1. In this article we explore the algorithmic and analytic properties of these sums systematically. We work out the Mellin and inverse Mellin transform which connects the sums under consideration with the associated Poincare iterated integrals, also called generalized harmonic polylogarithms. In this regard, we obtain explicit analytic continuations by means of asymptotic expansions of the S-sums which started to occur frequently in current QCD calculations. In addition, we derive algebraic and structural relations, like differentiation w.r.t. the external summation index and different multi-argument relations, for the compactification of S-sum expressions. Finally, we calculate algebraic relations for infinite S-sums, or equivalently for generalized harmonic polylogarithms evaluated at special values. The corresponding algorithms and relations are encoded in the computer algebra package HarmonicSums.
The harmonic oscillator in a space with a screw dislocation
Amore, Paolo; Fernández, Francisco M.
2018-01-01
We obtain the eigenvalues of the harmonic oscillator in a space with a screw dislocation. By means of a suitable nonorthogonal basis set with variational parameters we obtain sufficiently accurate eigenvalues for an arbitrary range of values of the space-deformation parameter. The energies exhibit a rich structure of avoided crossings in terms of such model parameter.
Analysis on h-harmonics and Dunkl transforms
2015-01-01
As a unique case in this Advanced Courses book series, the authors have jointly written this introduction to h-harmonics and Dunkl transforms. These are extensions of the ordinary spherical harmonics and Fourier transforms, in which the usual Lebesgue measure is replaced by a reflection-invariant weighted measure. The theory, originally introduced by C. Dunkl, has been expanded on by many authors over the last 20 years. These notes provide an overview of what has been developed so far. The first chapter gives a brief recount of the basics of ordinary spherical harmonics and the Fourier transform. The Dunkl operators, the intertwining operators between partial derivatives and the Dunkl operators are introduced and discussed in the second chapter. The next three chapters are devoted to analysis on the sphere, and the final two chapters to the Dunkl transform. The authors’ focus is on the analysis side of both h-harmonics and Dunkl transforms. The need for background knowledge on reflection groups is kept to a...
Reflection and transmission of plane harmonic waves at an interface ...
Indian Academy of Sciences (India)
Reflection and transmission of plane harmonic waves at an interface between liquid and micropolar viscoelastic solid with stretch. Baljeet Singh. Volume 25 Issue 6 December 2000 pp 589-600 ... Keywords. Micropolar viscoelastic solid; axial stretch; reflection coefficient; longitudinal wave; micropolar viscoelastic waves.
High-order harmonic generation via multicolor beam superposition
Sarikhani, S.; Batebi, S.
2017-09-01
In this article, femtosecond pulses, especially designed by multicolor beam superposition are used for high-order harmonic generation. To achieve this purpose, the spectral difference between the beams, and their width are taken to be small values, i.e., less than 1 nm. Applying a Gaussian distribution to the beam intensities leads to a more distinct pulses. Also, it is seen that these pulses have an intrinsic linear chirp. By changing the width of the Gaussian distributions, we can have several pulses with different bandwidths and hence various pulse duration. Thus, the study of these broadband pulse influences, in contrast with monochromatic pulses, on the atomic or molecular targets was achievable. So, we studied numerically the effect of these femtosecond pulses on behavior of the high-order harmonics generated after interaction between the pulse and the atomic hydrogen. For this study, we adjusted the beam intensities so that the produced pulse intensity be in the over-barrier ionization region. This makes the power spectrum of high-order harmonics more extensive. Cutoff frequency of the power spectrum along with the first harmonic intensity and its shift from the incident pulse are investigated. Additionally, maximum ionization probability with respect to the pulse bandwidth was also studied.
Imaging Collagen Orientation Using Polarization-Modulated Second Harmonic Generation
Energy Technology Data Exchange (ETDEWEB)
Stoller, P; Celliers, P M; Reiser, K M; Rubenchik, A M
2002-01-10
We use polarization-modulated second harmonic generation to image fiber orientation in collagen tissues, with an axial resolution of about 10 {micro}m and a transverse resolution of up to 1 {micro}m. A linearly polarized ultra-short pulse (200 fs) Ti:Sapphire laser beam is modulated using an electro-optic modulator and quarter-wave plate combination and focused onto a translation stage mounted sample using a microscope objective. The generated second harmonic light is collected using a photomultiplier tube and demodulated using phase sensitive detection to obtain signal intensity and fiber orientation information. In order to obtain second harmonic generation images of different types of collagen organization, we analyze several different tissues, including rat-tail tendon, mouse aorta, mouse fibrotic liver, and porcine skin. We can use our technique to image fibrotic tissue in histological sections of damaged liver and to identify burned tissue in porcine skin to a depth of a few hundred microns. Polarization-modulated second harmonic generation potentially could be a useful clinical technique for diagnosing collagen related disease or damage, especially in the skin.
An introduction to non-harmonic Fourier series
Young, Robert M
2001-01-01
An Introduction to Non-Harmonic Fourier Series, Revised Edition is an update of a widely known and highly respected classic textbook.Throughout the book, material has also been added on recent developments, including stability theory, the frame radius, and applications to signal analysis and the control of partial differential equations.
Phase-space treatment of the driven quantum harmonic oscillator
Indian Academy of Sciences (India)
2017-02-22
Feb 22, 2017 ... Phase-space quantum mechanics; coherent states; harmonic oscillator; Husimi distribution; cross- ... is the Weyl operator assigned to the phase-space ...... formulae used in this work. The Hermite polynomials satisfy the following relations: 1. [19, Section 5.6.4],. Hη(y + σ) = η. ∑ k=0. ( η k. ) Hk(y)(2σ)η−k. = η.